TECHNICAL FIELD AND PRIOR ART
[0001] The invention relates to a method for determining with a sensor device a configuration
               of a drive mechanism having a moving element for driving a heald frame of a weaving
               machine. The invention further relates to a moving element of a drive mechanism for
               driving a heald frame of a weaving machine, and to a system comprising a moving element
               and a sensor device.
 
            [0002] Different types of drive mechanisms are known for driving heald frames of a weaving
               machine to move up and down heald frames, for example a cam mechanism as shown in
               
US5273079, a dobby mechanism, an eccentric mechanism as shown in 
WO2004081113A1, or a mechanism in which each heald frame is driven by a separate drive motor independently
               from the weaving machine as shown in 
EP3341509A1.
 
            [0003] More particular, 
EP3341509A1 shows the drive mechanism comprising a crank rotating about a crank axis, a coupling
               rod, and a lever having a first arm and a second arm, wherein the lever is swivelable
               to-and-fro about a swivel axis between an upper position and a lower position, and
               wherein the coupling rod is linked to the crank by a first hinged joint, which first
               hinged joint is eccentric to the crank axis, wherein the coupling rod is linked to
               the first arm of the lever by a second hinged joint, and wherein a location of the
               second hinged joint is adjustable with respect to the first arm of the lever for adjusting
               a stroke of the heald frame moved by the drive mechanism. 
EP3341509A1 further shows a sensor device comprising a target set arranged on the lever with
               a first target and a second target, and a detector arranged stationary on the weaving
               machine in a measuring position, wherein the targets of the target set have different
               characteristics for generating a first signal when approaching the measuring position
               from the upper position or when departing from the measuring position towards the
               upper position and for generating a second signal when approaching the measuring position
               from the lower position or when departing from the measuring position towards the
               lower position, wherein the second signal differs from the first signal. In accordance
               with 
EP3341509A1, movement profiles or movement courses are known in advance for different strokes.
               Therefore, a stroke can be determined based on the first signal, the second signal
               and the known movement profiles.
 
            SUMMARY OF THE INVENTION
[0004] It is the object of the invention to provide a method for determining with a sensor
               device a configuration of a drive mechanism having a moving element for driving a
               heald frame of a weaving machine requiring less or even no advance information of
               a movement profile. It is a further object of the invention to provide a moving element
               of a drive mechanism for driving a heald frame of a weaving machine allowing such
               a determination, and to a system comprising a moving element and a sensor device.
 
            [0005] According to a first aspect, a method for determining with a sensor device a configuration
               of a drive mechanism having a moving element for driving a heald frame of a weaving
               machine is provided, wherein the sensor device comprises a target set provided on
               the moving element of the drive mechanism with an upper target, a middle target and
               a lower target, wherein the middle target is arranged between the upper target and
               the lower target, and the sensor device comprises a sensor element arranged stationary
               on the weaving machine and configured for detecting a presence of the targets of the
               target set within a sensing range. The method comprises operating the drive mechanism
               to move the moving element so that the target set passes the sensor element, detecting
               with the sensor element the presence of the upper target, the middle target, and the
               lower target within the sensing range, determining an upper target detecting moment
               in a weaving cycle upon detecting the upper target, determining a middle target detecting
               moment in the weaving cycle upon detecting the middle target, and determining a lower
               target detecting moment in a weaving cycle upon detecting the lower target, and determining
               a configuration of the drive mechanism based on the upper target detecting moment,
               the middle target detecting moment, and the lower target detecting moment.
 
            [0006] Throughout this application, the indefinite article "a" or "an" means "one or more".
               In particular, the drive mechanism may comprise more than one moving element, wherein
               each moving element is configured for driving one heald frame. Reference to "a first
               element" does not mandate presence of a "second element". Further, the expressions
               "first" and "second" are only used to distinguish one element from another element
               and not to indicate any order of the elements.
 
            [0007] Although in the application, the expressions "upper" and "lower" are used in conformity
               with a movement of the heald frame driven by the drive mechanism, the method can also
               be used with a moving element, which moves left to right, wherein the sensor element
               is approached by the targets provided on the moving element from the left and from
               the right depending on the movement direction of the moving element.
 
            [0008] In the following, the expression determined target detecting moment will be used
               to refer to one, several or all of a determined upper target detecting moment, a determined
               lower target detecting moment, and a determined middle target detecting moment.
 
            [0009] In the context of the application, a moment in the weaving cycle is defined as a
               moment in relation to an angle of the weaving machine, for example a moment in which
               the moving element reaches or is in a certain position in relation to an angle of
               the weaving machine.
 
            [0010] In the context of the application, a configuration of a drive mechanism is defined
               as a configuration or set-up associated with at least one settable configuration parameter
               of a movement profile of the drive mechanism selected of the group comprising a stroke,
               a zero-crossing moment, a crossing moment, a movement profile type, and/or a binding
               pattern. In other words, by determining the configuration of a drive mechanism at
               least one of the stroke, the zero-crossing moment, the crossing moment, the movement
               profile type, and/or the binding pattern are determined, allowing a determination
               of the movement profile, i.e. a movement path or curve of the moving element.
 
            [0011] In the context of the application, the stroke, also referred to as stroke length,
               is the distance travelled by the moving element between two extreme positions also
               referred to as reversal points, typically an upper extreme position and a lower extreme
               position. The stroke of the moving element is the same as or proportional to the stroke
               of the heald frame driven by the moving element. A position in the middle of the travelled
               distance of the moving element, with the same distance to both extreme positions,
               is referred to as zero position. A zero-crossing moment is defined as a moment in
               the weaving cycle at which the moving element passes the zero position during an upward
               and a downward movement.
 
            [0012] In weaving machines, depending on a drive mechanism and/or a configuration of a drive
               mechanism so called symmetrical movements and asymmetrical movements of a moving element
               and thus of the heald frame driven by the moving element are possible, which are referred
               to in the context of the application as movement profile types. When using an asymmetrical
               movement, typically the movement profile is different for the lower warp threads than
               for the upper warp threads.
 
            [0013] A crossing moment is defined as a moment in the weaving cycle, in which the moving
               element is in a position where the moving element should cross itself when moving
               from one extreme position to the other extreme position. The crossing moment may differ
               from a zero-crossing moment, in particular for asymmetrical movement profile types.
               A position of the moving element at the crossing moment is referred to as crossing
               position. A distance between the zero position and the crossing position is referred
               to as crossing height.
 
            [0014] A binding pattern or weaving pattern is defined as a pattern in which weft threads
               and warp threads interlace. Depending on the binding pattern, not all heald frames
               are moved from one extreme position to the other extreme position in each weaving
               cycle.
 
            [0015] The configuration of the drive mechanism can be set-up to adapt the movement profile
               of the moving element of the drive mechanism, and thus the heald frame driven by the
               moving element, to different weaving conditions and/or weaving patterns. In particular,
               depending on the drive mechanism, the configuration can be set-up to alter one or
               more configuration parameters selected for example from the group comprising the stroke,
               the zero-crossing moment, the crossing moment, the crossing height, the movement profile
               type, and/or the binding pattern.
 
            [0016] According to the invention, a method is provided which allows the determination of
               the configuration of the drive mechanism requiring no or at least only little advance
               information about any configuration parameter by observing a movement of the moving
               element using a target set with three targets, namely an upper target, a middle target,
               and a lower target, so that the configuration of the drive mechanism can be determined
               in embodiments without the necessity of any input in a control device of the weaving
               machine from a user or operator of the weaving machine.
 
            [0017] The determined configuration in embodiments of the method is stored in a control
               device of the weaving machine. The determined configuration can thus be used for a
               subsequent operation of the weaving machine and/or for set-up of the drive mechanism
               to set-up the drive mechanism with a desired configuration. The determined configuration
               in one embodiment is used to optimize the revolution speed of the weaving machine
               and/or to optimize the insertion parameters of the weaving machine for a set revolution
               speed of the weaving machine.
 
            [0018] In an embodiment, the sensor element is a Hall sensor, wherein the targets are magnets
               provided at the moving element, in particular at a side end of the moving element,
               wherein the method comprises detecting with the sensor element the magnets when moving
               the magnets into or out of the sensing range. In an alternative embodiment, the targets
               are separate elements provided at the moving element, for example elements such as
               blocks that are fixed or glued to the moving element, in particular that are fixed
               to the moving element at a side of the moving element. A fixing or gluing may be performed
               per block individually or via an assembly of several blocks.
 
            [0019] In other embodiments, the sensor element is a proximity sensor, wherein the targets
               are protrusions provided at the moving element, in particular at a side end of the
               moving element, which protrusions are separated by notches, wherein the method comprises
               detecting with the sensor element rising edges of the targets when moving the targets
               into the sensing range. This allows the targets to be manufactured integrally with
               the moving element. In addition or in alternative to the rising edges, in one embodiment
               falling edges are also detected and processed for determining the configuration of
               the drive mechanism.
 
            [0020] In one embodiment, the drive mechanism is operated in a weaving direction to move
               the moving element back-and-forth so that the target set passes the sensor element
               from below and from above, wherein the method for determining the configuration of
               the drive mechanism comprises detecting the presence of the targets within the sensing
               range when passing the sensor element from below and from above, and determining target
               detecting moments including a first upper target detecting moment in the weaving cycle
               upon detecting the upper target when passing the sensor element from below, a second
               upper target detecting moment in the weaving cycle upon detecting the upper target
               when passing the sensor element from above, a first middle target detecting moment
               in the weaving cycle upon detecting the middle target when passing the sensor element
               from below, a second middle target detecting moment in the weaving cycle upon detecting
               the middle target when passing the sensor element from above, a first lower target
               detecting moment in the weaving cycle upon detecting the lower target when passing
               the sensor element from below, and a second lower target detecting moment in the weaving
               cycle upon detecting the lower target when passing the sensor element from above.
 
            [0021] In the context of the application, the weaving direction is defined as a movement
               direction used in normal operation of the weaving machine. When operating the drive
               mechanism in the weaving direction, the moving element within one, two or several
               weaving cycles is moved back-and-forth to move a driven heald frame up and down. In
               accordance with the application, the drive mechanism is operated for a sufficient
               period so that each target of the target set passes the sensor element at least once
               from above and once from below, wherein - using three targets - six target detecting
               moments are identified, for example using rising edges, which can be used for a subsequent
               determination of the configuration of the drive mechanism.
 
            [0022] In accordance with the above, although in the application and the claims the expressions
               "from below" and "from above" are used in conformity with a movement of the heald
               frames driven by the drive mechanism, the method can also be used with a moving element,
               which moves left to right, wherein the sensor element is approached by the targets
               provided on the moving element from the left and from the right depending on the movement
               direction of the moving element.
 
            [0023] In one embodiment, the drive mechanism is operated in a reverse direction to move
               the moving element back-and-forth so that the target set passes the sensor element
               from below and from above, wherein the method for determining the configuration of
               the drive mechanism further comprises detecting the presence of the targets within
               the sensing range when passing the sensor element from below and from above, and determining
               target detecting moments including a third upper target detecting moment in the weaving
               cycle upon detecting the upper target when passing the sensor element from below,
               a fourth upper target detecting moment in the weaving cycle upon detecting the upper
               target when passing the sensor element from above, a third middle target detecting
               moment in the weaving cycle upon detecting the middle target when passing the sensor
               element from below, a fourth middle target detecting moment in the weaving cycle upon
               detecting the middle target when passing the sensor element from above, a third lower
               target detecting moment in the weaving cycle upon detecting the lower target when
               passing the sensor element from below, and a fourth lower target detecting moment
               in the weaving cycle upon detecting the lower target when passing the sensor element
               from above.
 
            [0024] In the context of the application, the reverse direction is defined as a direction
               opposite to the weaving direction. When operating the drive mechanism in the weaving
               direction and in the reverse direction for a sufficient period so that each target
               of the target set passes the sensor element twice from above and twice from below,
               twelve target detecting moments are identified, for example using rising edges, which
               can be used for a subsequent determination of the configuration of the drive mechanism.
 
            [0025] In one embodiment, determining the configuration of the drive mechanism comprises
               determining a zero-crossing moment in the weaving cycle when the moving element is
               in a zero position based on two determined middle target detecting moments, which
               determined middle target detecting moments have been determined upon detecting the
               middle target when passing the sensor element from above and from below, wherein in
               particular the middle target is arranged symmetrically to a zero position line when
               the moving element is in a zero position and the sensor element is arranged at a height
               of the zero position line.
 
            [0026] As defined above, the zero position is the position in the middle of the stroke or
               travel distance of the moving element. For determining the zero position, a moment
               when a midpoint of the middle target is at the height of the sensor element is determined,
               wherein in embodiments, the sensor is arranged at the height of the zero position
               line and the middle target is arranged such that the midpoint is at the zero position
               line in the zero position. Depending on the embodiment, two middle target detecting
               moments are determined, namely the first and the second middle target detecting moment
               or the third and the fourth middle target detecting moment, or all four middle target
               detecting moments are determined. For determining the moment when the midpoint of
               the middle target is at the height of the sensor element, two of these determined
               middle target detecting moments are used, in particular the first and the second middle
               target detecting moment or the first and the fourth middle target detecting moment,
               the third and the fourth middle target detecting moment, or the third and the second
               middle target detecting moment. In other words, moments, when the middle target is
               detected by the sensor element, when moving the middle target past the sensor element
               from two opposite directions, are used for determining a moment, when a midpoint of
               the middle target is at the height of the sensor element. Of course, embodiments are
               also conceivable in which more than two determined middle target detecting moments
               are used.
 
            [0027] In an embodiment, determining the configuration of the drive mechanism further comprises
               determining a movement profile type, wherein information about different movement
               profile types is pre-stored, and the movement profile type is determined based on
               the determined zero-crossing moment.
 
            [0028] The movement profile types can comprise a symmetrical type and an asymmetrical type.
               In embodiments, different symmetrical types and/or asymmetrical types are considered.
               The method makes use of the characteristic that the different movement profile types
               differ in the zero-crossing moment. Hence, using the determined zero-crossing moment
               and pre-stored information about possible movement profile types, the movement profile
               type can be determined without the necessity of any input from a user or operator.
 
            [0029] In an embodiment, determining the configuration of the drive mechanism comprises
               determining a crossing moment, wherein a reversal point moment in the weaving cycle,
               when the moving element is in one of its reversal points, is determined based on the
               determined target detecting moments, and the crossing moment is defined based on the
               reversal point moment.
 
            [0030] As defined above, the crossing moment is the moment in the weaving cycle, in which
               the moving element is in a position where the moving element should cross itself when
               moving from the upper position to the lower position or from the lower position to
               the upper position. In an embodiment, the reversal point moment is defined using a
               selected first determined target detecting moment determined for one target of the
               target set when driving the drive mechanism in the weaving direction and a selected
               second determined target detecting moment determined for said one target of the target
               set when driving the drive mechanism in the reverse direction, wherein the reversal
               point moment is the midpoint between the selected first determined target detecting
               moment and the selected second determined target detecting moment. In other embodiments,
               more than two determined target detecting moments are used to allow for a compensation
               of measurement inaccuracies.
 
            [0031] In an embodiment, determining the configuration of the drive mechanism comprises
               determining a crossing height at the crossing moment relative to the zero position
               based on the movement profile type. In one embodiment, the movement profile type is
               determined based on the zero-crossing moment, which is determined based on the determined
               middle target detecting moment. In other embodiments, the movement profile type is
               known in advance or entered by a user or operator.
 
            [0032] In an embodiment, determining the configuration of the drive mechanism further comprises
               determining a stroke of the heald frame, wherein the stroke is determined via a first
               way based on the upper target detecting moment and the lower target detecting moment,
               and wherein the stroke is determined via another way, which another way is selected
               out of a group comprising a second way based on the upper target detecting moment
               and the middle target detecting moment, a third way based on the middle target detecting
               moment and the lower target detecting moment, and a fourth way based on distances,
               in particular notches, between the upper target and the middle target and the middle
               target and the lower target.
 
            [0033] As described in 
EP3341509A1, an angular difference between two determined target detecting moments can be used
               for determining the stroke of the moving element, and thus the stroke of the heald
               frame driven by the moving element. For this purpose, in one embodiment, for a first
               way an angular distance between a movement of midpoints of the upper target and the
               lower target past the sensor element is determined. For said another way, in embodiments,
               the moments, when midpoints of the middle target are moved past the sensor element,
               are used. According to the fourth way, midpoints of the distance between the targets,
               in particular midpoints of notches between targets in the form of protrusions are
               used for a determination of the stroke.
 
            [0034] In an embodiment, the stroke is determined using an assumed movement profile type
               selected out of a plurality of pre-stored movement profile types. In case an advance
               information is available about the movement profile type, a determination of the stroke
               is possible using two target detecting moments as described in 
EP3341509A1. The invention allows a determination of the stroke without such an advance information
               of the movement profile type. For this purpose, it is assumed that the configuration
               has an assumed movement profile type selected out of a plurality of possible movement
               profile types, next the stroke is determined in at least two different ways in using
               the assumed movement profile. In case the same stroke within limits is determined
               using the two different ways, it is concluded that the assumed movement profile type
               is the actual movement profile type, and that the determined stroke is the actual
               stroke. If the strokes determined in two different ways differ, it is concluded that
               the assumed movement profile type is not the actual movement profile type. Hence,
               an alternative movement profile type is selected out of the plurality of possible
               movement profile types, and the determination is repeated. In this way, the stroke
               and the movement profile type can be determined without advance information about
               the actual movement profile type.
 
            [0035] In an embodiment, a distance between the upper target and the middle target differs
               from a distance between the middle target and the lower target, wherein the method
               comprises determining a movement direction of the moving element based on a first
               angular distance between a first moment when detecting a first target of the target
               set and a second moment when detecting a second target of the target set and a second
               angular distance between the second moment when detecting a second target of the target
               set and a third moment when detecting a third target of the target set.
 
            [0036] In an embodiment, determining the configuration of the drive mechanism comprises
               determining a binding pattern, wherein the drive mechanism is operated over a number
               of weaving cycles to move the moving element back-and-forth.
 
            [0037] For a determination of the binding pattern, in an embodiment, it is determined based
               on determined target detecting moments, when the moving element is moved to drive
               the heald frame into a first extreme position and for how many weaving cycles the
               heald frame is maintained in the first extreme position, and when the moving element
               is moved to drive the heald frame into the second extreme position and for how many
               weaving cycles the heald frame is maintained in the second extreme position. In one
               embodiment, for this determination, the determined movement direction of the heald
               frame is used. The number of weaving cycles is determined based on a maximum number
               of weaving cycles for possible binding patterns. In one embodiment, e.g. for a cam
               mechanism wherein the number of weaving cycles for a binding pattern can be four,
               five or six weaving cycles, thus wherein the maximum number of weaving cycles for
               a binding pattern is six weaving cycles, the configuration can be determined when
               the target set passes the sensor element eleven times.
 
            [0038] In an embodiment, a height detector is provided comprising a height detector target
               provided on a heald frame driven by the moving element and a height detector sensor
               element, wherein a height detector passing moment of the heald frame is detected,
               i.e. a moment in which the height detector target passes the height detector sensor
               element, and a height position of the heald frame is determined based on the height
               detector passing moment and a configuration of the drive mechanism, in particular
               the determined configuration of the drive mechanism using the above mentioned method,
               in particular using an assumed movement profile type selected out of a plurality of
               pre-stored movement profile types. The heald frame driven by the moving element may
               be coupled at different heights to the moving element, wherein in the context of the
               application, the relative position of heald frame with respect to the drive mechanism
               is referred to as height position of the heald frame.
 
            [0039] According to a second aspect, a moving element of a drive mechanism for driving a
               heald frame of a weaving machine comprising a target set with an upper target and
               a lower target is provided, wherein the target set further comprises a middle target,
               wherein the middle target is arranged between the upper target and the lower target,
               wherein in particular the targets are protrusions provided at the moving element,
               in particular at a side end of the moving element, which protrusions are separated
               by notches. The moving element in preferred embodiments is a lever, in particular
               a lever arranged at a non-driven side of the drive mechanism. A lever having protrusions
               in an embodiment is manufactured by punching. In embodiments, the lever according
               to the invention replaces levers of existing drive mechanisms to allow the inventive
               method to be carried out.
 
            [0040] According to a third aspect, a system comprising a control device, a drive mechanism
               for driving a heald frame of a weaving machine, the drive mechanism having a moving
               element, and a sensor device with a target set provided on the moving element and
               with a sensor element mountable stationary on the weaving machine and configured for
               detecting a presence of targets of the target set within a sensing range, is provided
               wherein the target set comprises an upper target, a middle target, and a lower target,
               wherein the middle target is arranged between the upper target and the lower target,
               wherein the drive mechanism is configured for being operated to move the moving element
               so that the target set passes the sensor element, wherein the control device is configured
               for determining an upper target detecting moment in a weaving cycle upon detecting
               the upper target, a middle target detecting moment in the weaving cycle upon detecting
               the middle target, and a lower target detecting moment in a weaving cycle upon detecting
               the lower target, and wherein the control device is configured for determining a configuration
               of the drive mechanism based on the upper target detecting moment, the middle target
               detecting moment, and the lower target detecting moment.
 
            [0041] The system using a target set with three targets allows a determination of the configuration
               of the drive mechanism without advance information about certain configuration parameters,
               for example a movement profile type. Of course, the system can also be used in case
               at least some of the configuration parameters are known in advance and/or to check
               if the configuration parameters present or entered into the control unit of the weaving
               machine are correct.
 
            [0042] In an embodiment, the sensor element is a proximity sensor, wherein the targets are
               protrusions provided at the moving element, in particular at a side end of the moving
               element, which protrusions are separated by notches, wherein the sensor device is
               configured for detecting with the sensor element rising edges of the targets when
               moving the targets into the sensing range.
 
            [0043] In an embodiment, the system has a height detector configured for detecting a height
               detector passing moment of a heald frame and for determining a height position of
               the heald frame based on the height detector passing moment and the determined configuration
               of the drive mechanism, in particular using an assumed movement profile type selected
               out of a plurality of pre-stored movement profile types, wherein in particular the
               height detector comprises a height detector sensor element and a height detector target
               provided on a heald frame driven by the moving element of the drive mechanism.
 
            [0044] Detecting a height detector passing moment of a heald frame and determining a height
               position of the heald frame based on the height detector passing moment does not necessarily
               require that a configuration of the drive mechanism is determined using a sensor device
               with three targets in accordance with claim 1. In an advantageous modification, a
               height position of the heald frame is determined based on a detected height detector
               passing moment and a known configuration of a drive mechanism driving the heald frame,
               in particular based on a known movement profile, a known zero-crossing line and/or
               a known zero-crossing moment. In another advantageous modification, a height position
               of the heald frame is determined based on a detected height detector passing moment
               and a determined configuration of a drive mechanism driving the heald frame, in particular
               a determined movement profile, a determined zero-crossing line and/or a determined
               zero-crossing moment, wherein in an embodiment the configuration is determined using
               a sensor device with only one target or with only two targets or with more than three
               targets.
 
            BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In the following, embodiments of the invention will be described in detail with reference
               to the drawings. Throughout the drawings, the same elements will be denoted by the
               same reference numerals.
               
               
                  - Fig. 1
- shows in a front view an embodiment of a drive mechanism for driving a heald frame
                     of a weaving machine with a system for determining a configuration of the drive mechanism.
- Fig. 2
- shows a detail of the drive mechanism of Fig. 1 in enlarged scale.
- Fig. 3
- shows a detail of Fig. 2 in enlarged scale.
- Fig. 4
- shows in a front view the drive mechanism according to Fig. 1 with an alternative
                     system for determining the configuration of the drive mechanism.
- Fig. 5
- shows a possible movement profile of a moving element of the drive mechanism of Fig.
                     1 over two weaving cycles.
- Fig. 6
- shows two movement profiles of two different movement profile types over three weaving
                     cycles.
- Fig. 7
- shows four different movement profiles of four different movement profile types over
                     two weaving cycles.
- Fig. 8
- shows a movement profile of a moving element for illustrating a stroke determination
                     via a first way.
- Fig. 9
- shows the movement profile of Fig. 8 for illustrating a stroke determination via a
                     second way or a third way.
- Fig. 10
- shows the movement profile of Fig. 8 for illustrating a stroke determination via a
                     fourth way.
- Fig. 11
- shows three different movement profiles of one asymmetrical movement profile type
                     for three different strokes and associated crossing heights.
- Fig. 12
- shows a movement profile of a heald frame and a movement profile of a moving element
                     driving the heald frame for illustrating a determination of a height position of a
                     heald frame using a height detector.
- Fig. 13
- shows a movement profile of a heald frame and a movement profile of a moving element
                     driving the heald frame for illustrating a determination of a height position of a
                     heald frame using a height detector via another way.
- Fig. 14
- shows a movement profile of a moving element for a binding pattern over six weaving
                     cycles during twelve weaving cycles.
 
            DETAILED DESCRIPTION OF EMBODIMENTS
[0046] Fig. 1 shows a heald frame 1 and a drive mechanism 2 of a shed-forming device 3 of
               a weaving machine. Fig. 2 shows a detail of the drive mechanism of Fig. 1 in enlarged
               scale, while Fig. 3 shows a detail of Fig. 2 in enlarged scale.
 
            [0047] The shed-forming device 3 comprises a number of heald frames 1, wherein one drive
               mechanism 2 is assigned to each heald frame 1. In the embodiment shown, the number
               of drive mechanisms 2 are driven by a common drive system 26 with an axis 4. A stationary
               frame 9 of the weaving machine is schematically shown in Fig. 1.
 
            [0048] The drive mechanism 2 for driving the heald frame 1 shown in Fig. 1 is a cam mechanism.
               It comprises two cams 5, 6 rotating about the axis 4, a drive lever 7 driven by the
               cams 5, 6 to oscillate about an axis 8, a coupling rod 10 coupled to the drive lever
               7 via a hinged joint 11, and a first lever 12. The first lever 12 is swivelable to-and-fro
               about a stationary arranged first swivel axis 13 between an upper position and a lower
               position. The first lever 12 has a first arm 14 and a second arm 15, and the first
               lever 12 is coupled to the coupling rod 10 at the first arm 14. The drive mechanism
               2 further comprises a second lever 16, that is swivelable to-and-fro about a second
               swivel axis 18 between an upper position and a lower position, and a third lever 17,
               that is swivelable to-and-fro about a third swivel axis 19 between an upper position
               and a lower position. The second lever 16 and the third lever 17 are linked to the
               first arm 14 of the first lever 12 by means of a connecting rod 20 and driven by the
               first lever 12 to conjointly move with the first lever 12. The first lever 12, the
               second lever 16 and the third lever 17 are conjointly referred to as levers 12, 16,
               17. As will be understood by the person skilled in the art, other embodiments are
               conceivable, wherein only two of the levers 12, 16, 17 or more than three levers 12,
               16, 17 are provided.
 
            [0049] The heald frame 1 is linked to the second arm 15 of the first lever 12 by means of
               a lifting rod 21 and a fixation element 22 that is guided in a stationary guide element
               23 of the weaving machine.
 
            [0050] The second lever 16 and the third lever 17 are also linked via a lifting rod 21 and
               a fixation element 22 to the heald frame 1.
 
            [0051] For determining a configuration of the drive mechanism 2, a sensor device 40 comprising
               a target set 41 and a sensor element 42 arranged stationary on the weaving machine
               are provided. As best seen in Fig. 2, the sensor device 40 comprises a target set
               41 with an upper target 43, a middle target 44, and a lower target 45, which in the
               embodiment shown are provided on the third lever 17. The sensor element 42 is configured
               for detecting a presence of the targets 43, 44, 45 of the target set 41 within a sensing
               range of the sensor element 42.
 
            [0052] In the embodiment shown in Fig. 1, in addition a height detector 50 is provided,
               which comprises a height detector target 51 provided on the heald frame 1 and a height
               detector sensor element 52 arranged stationary on the weaving machine, wherein the
               height detector sensor element 52 is configured for detecting a presence of the height
               detector target 51 within a sensing range of the height detector sensor element 52.
 
            [0053] The sensor device 40 and the height detector 50, in particular the sensor element
               42 of the sensor device 40 and the height detector sensor element 52 of the height
               detector 50 are both communicated to a control device 25, which control device 25
               is for example part of a central control unit of the weaving machine or communicates
               with the central control unit of the weaving machine.
 
            [0054] In the embodiment shown, the targets 43, 44, 45 of the target set 41 are protrusions
               provided on the lever 17, which lever 17 is arranged at a non-driven side of the drive
               mechanism 2, i.e. a side opposite to the drive lever 7. The targets 43, 44, 45 are
               provided in the form of protrusions protruding from a side end of the lever 17 facing
               away from the drive lever 7. This arrangement allows for sufficient mounting space
               for the target set 41 and the sensor element 42. However, the invention is not limited
               to this arrangement and other arrangements are conceivable to the person skilled in
               the art, for example the targets 43, 44, 45 of the target set 41 can be protrusions
               that are provided on the lever 12 or on the lever 16.
 
            [0055] The first lever 12 is coupled to the drive lever 7 via the coupling rod 10. In the
               embodiment shown, the drive lever 7 is curved and the location of the hinged joint
               11 connecting the connecting rod 10 to the drive lever 7 is adjustable along the drive
               lever 7 by sliding the hinged joint 11 along the drive lever 7. A curvature of the
               drive lever 7 is chosen so that upon adjusting the location of the hinged joint 11
               along the drive lever 7, the hinged joint 11 remains situated on an arc of an imaginary
               circle schematically shown by a dashed-dotted line in Fig. 1 having its center at
               the connecting point between the first arm 14 and the coupling rod 10 and a radius
               as schematically indicated by an arrow 29 in Fig. 1. Therefore, in the embodiment
               shown, when adjusting the location of the hinged joint 11 along the drive lever 7
               for adjusting a stroke of the heald frame 1, a zero position of the levers 12, 16,
               17 as shown in Fig. 1 remains unchanged, wherein for example the zero position is
               a position in the middle of the travelled distance of the levers 12, 16, 17 with the
               same distance to both extreme positions. A line through the third swivel axis 19 when
               the lever 17 is in the zero position is referred to as zero position line 46, wherein
               as shown in Fig. 2 the zero position line 46 is a horizontal line through the swivel
               axis 19 of the lever 17 and the swivel axis 24 connecting the lever 17 and the lifting
               rod 21 for the heald frame 1.
 
            [0056] As best seen in Figs. 2 and 3, in the embodiment shown, the sensor element 42 is
               arranged for example at a height of the zero position line 46 and the middle target
               44 is arranged symmetrically or approximately symmetrically to the zero position line
               46 when the lever 17 is in the zero position. Further, in the embodiment shown, a
               distance between the upper target 43 and the middle target 44, i.e. a size of a notch
               30 provided between the upper target 43 and the middle target 44, differs from a distance
               between the middle target 44 and the lower target 45, i.e. a size of a notch 31 provided
               between the middle target 44 and the lower target 45. The upper target 43 is arranged
               symmetrically to a central line 27 through the third swivel axis 19, while the lower
               target 45 is arranged symmetrically to a central line 28 through the third swivel
               axis 19. In the embodiment shown, the upper target 43 and the lower target 45 differ
               in size, wherein as shown in Fig. 2 the zero position line 46 is for example arranged
               in the bisector of both central lines 27, 28. As in the embodiment shown, the upper
               target 43 and the lower target 45 differ in size, also the notches 30, 31 differ in
               size.
 
            [0057] In operation, the heald frame 1 is driven to move up and down, wherein a movement
               profile of the drive mechanism 2 and, thus the heald frame 1 coupled thereto, depends
               inter alia on a configuration of the drive mechanism 2. As described above, a stroke
               of the heald frame 1 is settable by adjusting a location of the hinged joint 11 along
               the drive lever 7. Depending on the type of drive mechanism 2 additional or other
               elements are adjustable either in use or upon set-up or manufacturing of the drive
               mechanism 2. The weaving machine allows for setting and determining configuration
               parameters of a movement profile of the drive mechanism 2 selected of the group comprising
               a stroke, a zero-crossing moment, a crossing height, a crossing moment, a movement
               profile type and/or a binding pattern.
 
            [0058] The first lever 12, the second lever 16, the third lever 17, the connecting rod 20,
               the lifting rods 21 and the fixation elements 22 are conjointly referred to as moving
               elements. In the embodiment shown in Figs. 1 and 2, the target set 41 is provided
               on the third lever 17 arranged at the non-driven side of the drive mechanism 2.
 
            [0059] Fig. 4 shows the shed-forming device 3 together with another embodiment of the sensor
               device 40 for determining a configuration of the drive mechanism 2, wherein in contrast
               to the embodiment of Fig. 1 the target set 41 is provided on a different moving element,
               in particular on the connecting rod 20. The sensor element 42 is arranged opposite
               the target set 41. The target set 41 comprises three targets 43, 44, 45, which are
               all arranged at the same height. Despite their arrangement, the targets are referred
               to as upper target 43, middle target 44 and lower target 45 in conformity with a movement
               of the heald frame 1 driven by the drive mechanism 2. As shown in Fig. 4, the sensor
               device 40 and the height detector 50 are both communicated to a control device 25.
 
            [0060] Fig. 5 shows a possible movement profile 70 of a moving element, in particular the
               third lever 17 of the drive mechanism 2 (see Fig. 1) over two weaving cycles, wherein
               in a first weaving cycle the moving elements 12, 16, 17, 20, 21, 22 and thus the heald
               frame 1 (see Fig. 1) are moved from a lower extreme position towards an upper extreme
               position and in a second weaving cycle the moving elements 12, 16, 17, 20, 21, 22
               and thus the heald frame 1 are moved back into the lower extreme position. A zero-crossing
               line 53 for the moving element when the moving element is in the zero position is
               shown by a dashed-dotted line.
 
            [0061] When moving from the lower extreme position towards the upper extreme position, the
               upper target 43, the middle target 44, and the lower target 45 (see Figs. 1 and 2)
               are moved one after the other past the sensor element 42 (see Figs. 1 and 2). Likewise,
               when moving from the upper extreme position towards the lower extreme position, the
               lower target 45, the middle target 44, and the upper target 43 are moved one after
               the other past the sensor element 42.
 
            [0062] The presence of the targets 43, 44, 45 within the sensing range of the sensor element
               42 when passing the sensor element 42 from below and from above is detectable, and
               target detecting moments can be determined.
 
            [0063] In the embodiment shown, the sensor element 42 is configured to detect rising edges
               of the targets 43, 44, 45 when moving the targets 43, 44, 45 into the sensing range,
               so that when operating the drive mechanism 2 to move the lever 17 back-and-forth with
               the movement profile of Fig. 5, six target detecting moments can be detected, namely
               a first upper target detecting moment 1.43 in the weaving cycle upon detecting the
               upper target 43 when passing the sensor element 42 from below, a second upper target
               detecting moment 2.43 in the weaving cycle upon detecting the upper target 43 when
               passing the sensor element 42 from above, a first middle target detecting moment 1.44
               in the weaving cycle upon detecting the middle target 44 when passing the sensor element
               42 from below, a second middle target detecting moment 2.44 in the weaving cycle upon
               detecting the middle target 44 when passing the sensor element 42 from above, a first
               lower target detecting moment 1.45 in the weaving cycle upon detecting the lower target
               45 when passing the sensor element 42 from below, and a second lower target detecting
               moment 2.45 in the weaving cycle upon detecting the lower target 45 when passing the
               sensor element 42 from above.
 
            [0064] In the embodiment shown, the drive mechanism 2 is further operable in a reverse direction,
               wherein the lever 17 is moved with the same movement profile. When operating the drive
               mechanism 2 to move the lever 17 in a reverse direction back-and-forth with the movement
               profile of Fig. 5, again six target detecting moments can be detected, namely a third
               upper target detecting moment 3.43 in the weaving cycle upon detecting the upper target
               43 when passing the sensor element 42 from below, a fourth upper target detecting
               moment 4.43 in the weaving cycle upon detecting the upper target 43 when passing the
               sensor element 42 from above, a third middle target detecting moment 3.44 in the weaving
               cycle upon detecting the middle target 44 when passing the sensor element 42 from
               below, a fourth middle target detecting moment 4.44 in the weaving cycle upon detecting
               the middle target 44 when passing the sensor element 42 from above, a third lower
               target detecting moment 3.45 in the weaving cycle upon detecting the lower target
               45 when passing the sensor element 42 from below, and a fourth lower target detecting
               moment 4.45 in the weaving cycle upon detecting the lower target 45 when passing the
               sensor element 42 from above. Determining the third and fourth target detecting moments
               allows to reduce or even eliminate detection inaccuracies due to an upward or a downward
               movement of a heald frame 1 by the moving element 12, 16, 17, 20, 21, 22 over one
               revolution of the weaving machine.
 
            [0065] Based on the target detecting moments shown in Fig. 5, an unknown configuration of
               the drive mechanism 2 can be determined as will be explained with reference to the
               following drawings.
 
            Zero-Crossing Moment
[0066] In one embodiment, a zero-crossing moment 48 (shown by a dashed line in Fig. 5) in
               the weaving cycle is determined, i.e. a moment in the weaving cycle, when the moving
               element 12, 16, 17, 20, 21, 22 is in the position in the middle of the stroke or travel
               distance of the moving element (referred to as zero position).
 
            [0067] Such a determination in one embodiment is made based on determined middle target
               detecting moments 1.44, 2.44, 3.44, 4.44.
 
            [0068] As described for Fig. 2, in the embodiment shown, the middle target 44 is arranged
               symmetrically to a zero position line 46 when the moving element is in a zero position
               and the sensor element 42 is arranged at a height of the zero position line 46. In
               this case, a zero-crossing line 53 and, thus, zero-crossing moments 48, 54 can be
               determined based on two middle target detecting moments determined when the middle
               target 44 is moving past the sensor element 42 from above and from below, in particular
               the zero-crossing line 53 can be determined based on the first middle target detecting
               moment 1.44 and the second middle target detecting moment 2.44 or based on the third
               middle target detecting moment 3.44 and the fourth middle target detecting moment
               4.44, while a first zero-crossing moment 48 can be determined based on the first middle
               target detecting moment 1.44 and the fourth middle target detecting moment 4.44 and
               a second zero-crossing moment 54 can be determined based on the third middle target
               detecting moment 3.44 and the second middle target detecting moment 2.44.
 
            Crossing Moment
[0069] In the context of the application, the crossing moment is defined as the moment when
               the moving element 12, 16, 17, 20, 21, 22, in particular the lever 17, is in a position
               in relation to an angle of the weaving machine, in which the moving element 12, 16,
               17, 20, 21, 22 should cross itself when moving from up to down or from down to up.
 
            [0070] Fig. 6 shows two movement profiles of two different movement profile types over three
               weaving cycles, wherein a movement profile 70 of a first movement profile type, which
               is a symmetrical movement, is shown in a solid line, and a movement profile 71 of
               second movement profile type, which is an asymmetrical movement, is shown in a dashed
               line.
 
            [0071] A zero-crossing line 53 is shown as a solid line. The zero-crossing line 53 is either
               known or determined using the above described method. Crossing moments 49 are shown
               by solid lines, wherein the crossing moments 49 are to be determined.
 
            [0072] For a determination of the crossing moment 49, a reversal point moment 47 in the
               weaving cycle (shown in Fig. 5 and 6) is determined, wherein the reversal point moment
               47 is defined as the moment, when the moving element is in one of its extreme positions
               and the movement is reversed. The reversal point moment 47 is deemed to be half of
               a weaving cycle, i.e. 180°, shifted from the crossing moment. Hence, based on the
               determined reversal point moment 47, the crossing moment 49 can be determined. The
               reversal point moment 47 can be determined as an average middle line between the target
               detection moments 1.43 and 3.43, the target detection moments 4.43 and 2.43, the target
               detection moments 1.44 and 3.44, the target detection moments 4.44 and 2.44, the target
               detection moments 1.45 and 3.45, and the target detection moments 4.45 and 2.45.
 
            [0073] The movement profile type of the movement profile 70 shown in a solid in Fig. 6 is
               a symmetrical movement profile. Hence, the crossing moment 49 coincides with the zero-crossing
               moment 48 (shown by the dashed line in Fig. 5). The movement profile type of the movement
               profile 71 shown in a dashed line in Fig. 6 is an asymmetrical movement profile. Hence,
               the crossing moment 49 does not coincide with the zero-crossing moments 55, 56 (shown
               by the dashed-dotted line in Fig. 6) for the asymmetrical movement profile 71.
 
            [0074] A position of the moving element 12, 16, 17, 20, 21, 22, in particular the lever
               17, at the crossing moment is referred to as crossing position. A distance between
               the zero position and the crossing position is referred to as a crossing height H1.
               The movement profile type of the movement profile 70 shown in Fig. 6 is a symmetrical
               movement profile and the zero position coincides with the crossing position. The movement
               profile type of the movement profile 71 shown in Fig. 6 is an asymmetrical movement
               profile and the distance between the zero position and the crossing position is the
               crossing height H1, in particular the distance between the zero-crossing line 53 and
               the crossing line 58.
 
            Movement Profile Type and Stroke Determination
[0075] In the context of the application, different movement profiles defined by a configuration
               of a drive mechanism are referred to as movement profile types, wherein the movement
               profile types can be symmetrical movements or asymmetrical movements. When using an
               asymmetrical movement profile, typically the movement profile is different for the
               lower warp threads than for the upper warp threads.
 
            [0076] In an embodiment of the invention, a movement profile type is determined.
 
            [0077] A determination of a movement profile type in one embodiment is used for a determination
               of a configuration of the drive mechanism 2 in the form of a cam mechanism as shown
               in Fig. 1, wherein a profile of the cams 5, 6 and/or an angular offset of the cams
               5, 6 in relation to a main shaft of a weaving machine is not known in advance.
 
            [0078] As shown in Fig. 6, for a symmetrical movement profile 70 shown by the solid line,
               the zero position, i.e. a position of the moving element 12, 16, 17, 20, 21, 22, in
               particular the lever 17, half-way between the extreme positions, coincides with the
               crossing position, i.e. a position of the moving element 12, 16, 17, 20, 21, 22, in
               particular the lever 17, at the crossing moment 49, in which the moving element 12,
               16, 17, 20, 21, 22 should cross itself when moving from up to down or from down to
               up. As indicated by double arrows, in the embodiment of Fig. 6, the distance A1 is
               equal to the distance A2.
 
            [0079] For an asymmetrical movement profile 71 shown by the dashed line, the zero position
               i.e. a position of the moving element 12, 16, 17, 20, 21, 22, in particular the lever
               17, half-way between the extreme positions at the zero-crossing moment 48 of the asymmetrical
               movement profile 71, is offset to the crossing position, i.e. the crossing position
               is closer to one of the extreme positions. As indicated by double arrows, in the embodiment
               shown in Fig. 6, the crossing position is closer to a lower extreme position, in other
               words the distance B1 is less than the distance B2.
 
            [0080] Hence, based on the information that the crossing position does or does not coincide
               with the zero position, a symmetrical movement can be distinguished from an asymmetrical
               movement.
 
            [0081] In an embodiment, based on the determined information whether the movement profile
               type is a symmetrical movement or an asymmetrical movement, and pre-stored knowledge
               about the drive mechanism 2, and thus pre-stored knowledge about possible movement
               profile types when using the drive mechanism 2, the actual movement profile type can
               be determined without the necessity of any input from a user or an operator.
 
            [0082] For example, in the drive mechanism 2 shown in Fig. 1 different cam sets and cam
               set arrangements can be used allowing for the two symmetrical movement profiles 70,
               72 and the two asymmetrical movement profiles 71, 73 as shown in Fig. 7 over two weaving
               cycles. A zero-crossing line 53 is shown as a solid line.
 
            [0083] As shown in Fig. 7, the two symmetrical movement profiles 70, 72 both have a crossing
               position at the zero position.
 
            [0084] The asymmetrical movement profiles 71, 73 differ in an angular distance or shift
               between a crossing moment 49 and their respective zero-crossing moment 55 or 57. Hence,
               based on the determined zero-crossing moment 55 or 57 in relation to the determined
               crossing moment 49 and the pre-stored information about the asymmetrical movement
               profile types, it is possible to determine for the two asymmetrical movement profiles
               71, 73 a cam configuration of the drive mechanism 2, and thus, the associated movement
               profile type.
 
            [0085] As shown in Fig. 7, the symmetrical movement profiles 70, 72 all have the same crossing
               moment 49, which is the zero-crossing moment.
 
            [0086] In order to identify the actual symmetrical movement profile type, in one embodiment,
               a stroke is determined via at least two different ways for each possible symmetrical
               movement profile type, and the actual symmetrical movement profile type is determined
               as the symmetrical movement profile type for which the stroke determined via the at
               least two different ways is identical or shows the least deviation.
 
            [0087] Fig. 8 shows a movement profile 70 of a moving element for illustrating a stroke
               determination via a first way, wherein the stroke is determined based on an upper
               target detecting moment 63 and a lower target detecting moment 65. More particular,
               the stroke is determined based on the angular distance D1 between the upper target
               detecting moment 63 and the lower target detecting moment 65 for each possible movement
               profile type, for example for the two symmetrical movement profile types. The determination
               can be carried out as described in 
EP3341509, the content of which is hereby incorporated by reference.
 
            [0088] In the embodiment shown, the upper target detecting moment 63 is determined based
               on at least two of the first, second, third or fourth upper target detecting moments
               1.43, 2.43, 3.43, 4.43 associated with two different edges of the upper target 43
               (see Fig. 2), in particular is determined in the example based on the upper target
               detecting moments 1.43 and 4.43. The lower target detecting moment 65 is determined
               based on at least two of the first, second, third or fourth lower target detecting
               moments 1.45, 2.45, 3.45, 4.45 associated with two different edges of the lower target
               45 (see Fig. 2), in particular is determined in the example based on the lower target
               detecting moments 1.45 and 4.45. In the alternative, one of the first, second, third
               or fourth upper target detecting moments 1.43, 2.43, 3.43, 4.43 is used as the upper
               target detecting moment and one of the first, second, third or fourth lower target
               detecting moments 1.45, 2.45, 3.45, 4.45 is used as the lower target detecting moment.
 
            [0089] Fig. 9 shows the movement profile 70 of Fig. 8 for illustrating a stroke determination
               via a second way or a third way, wherein the stroke is determined via the second way
               based on the upper target detecting moment 63 and a middle target detecting moment
               64 and/or via the third way based on the middle target detecting moment 64 and the
               lower target detecting moment 65. The stroke is then determined based on the angular
               distance D2 between the upper target detecting moment 63 and the middle target detecting
               moment 64 or based on the angular distance D3 between the middle target detecting
               moment 64 and the lower target detecting moment 65.
 
            [0090] In the embodiment shown, the middle target detecting moment 64 is determined based
               on at least two of the first, second, third or fourth middle target detecting moments
               1.44, 2.44, 3.44, 4.44 associated with two different edges of the middle target 44
               (see Fig. 2), in particular is determined in the example based on the middle target
               detecting moments 1.44 and 4.44.
 
            [0091] By providing a sensor device 40 with a target set 41 having three targets 43, 44,
               45, the angular distances D1, D2 or D3 between at least two different pairs of targets
               43, 44, 45 can be determined and the stroke can be determined based on these angular
               distances for each possible movement profile type, in particular for each possible
               symmetrical movement profile type. The symmetrical movement profile type for which
               the stroke determined using the angular distances between at least two different pairs
               of targets 43, 44, 45 via the at least two different ways that is identical or shows
               the least deviation between the different ways, is identified as the actual symmetrical
               movement profile type.
 
            [0092] Fig. 10 shows the movement profile 70 of Fig. 8 for illustrating a stroke determination
               via a fourth way, wherein the stroke is determined based on the angular distance D4.
               In the embodiment shown, the angular distance D4 is determined based on the notch
               30 (see Fig. 2) between the upper target 43 and the middle target 44 and the notch
               31 (see Fig. 2) between the middle target 44 and the lower target 45. As shown in
               the example of Fig. 10, the center 61 of the notch 30 can be determined based on the
               distance between the fourth upper target detecting moment 4.43 and the first middle
               target detecting moment 1.44, while the center 62 of the notch 31 can be determined
               based on the distance between the fourth middle target detecting moment 4.44 and the
               first lower target detecting moment 1.45. The angular distance D4 can be determined
               as the distance between the center 61 and the center 62. In an alternative, the center
               61 can be determined based on the distance between second upper target detecting moment
               2.43 and the third middle target detecting moment 3.44, while the center 62 can be
               determined based on the distance between the second middle target detecting moment
               2.44 and the third lower target detecting moment 3.45.
 
            [0093] Hence, by providing a sensor device 40 with a target set 41 having three targets
               43, 44, 45, in alternative or in addition to the ways for determining the stroke described
               above, the angular distance between notches 30, 31 or other distances between the
               targets can be determined and the stroke can be determined based on this angular distance
               for each possible movement profile type.
 
            [0094] As mentioned above, asymmetrical movement profile types can be determined directly
               based on the angular distance or shift between a crossing moment 49 and a zero-crossing
               moment 55, 57. Of course it is also possible to determine the stroke for an asymmetrical
               movement profile in a way as described above for a symmetrical movement profile, for
               example in case both asymmetrical movement profiles have a same zero-crossing moment.
               If the movement profile type is known, it is sufficient to determine the stroke using
               only one of the four ways described above. In an embodiment, the first way is used
               for the determination of the stroke as the angular distance between the upper target
               and the lower target is larger than any other angular distance determined, and the
               stroke determination is more accurate. However, in other embodiments, the stroke is
               determined for the asymmetrical movement profile types via another way than the first
               way or via more than one way.
 
            Crossing height
[0095] As mentioned above, for asymmetrical movement profile types the crossing position
               is offset from a zero position. The crossing position depends on the asymmetrical
               movement profile type and the stroke.
 
            [0096] Fig. 11 shows three different movement profiles 71, 74, 75 of one asymmetrical movement
               profile type for three different strokes. If the movement profile type and the crossing
               moments are known, a crossing height H 1, H2, H3 of the movement profile 71, 74, 75
               can be determined, i.e. a distance between the zero position indicated by the zero-crossing
               line 53 and the crossing position at the crossing moment 49 indicated by the crossing
               lines 58, 59, 60.
 
            [0097] The determined crossing height H1, H2, H3 in one embodiment can be used to optimize
               a height position of the heald frame 1, in other words a relative position of the
               heald frame 1 with respect to the levers 12, 16, 17.
 
            Height position of the heald frame
[0098] In the embodiment shown in Figs. 1 and 4, the shed-forming device 3 further comprises
               a height detector 50 with a height detector target 51 provided on the heald frame
               1 and a height detector sensor element 52 arranged stationary on the weaving machine.
 
            [0099] Fig. 12 shows a movement profile 80 of the heald frame 1 and a movement profile 70
               of a moving element, in particular the lever 17 (see Fig. 1), driving the heald frame
               1 for illustrating a determination of a relative height position of the heald frame
               1, also referred to as height position, using the height detector 50 (see Fig. 1).
               The movement profile 80 of the heald frame 1 follows the movement profile 70 of the
               moving element, because the heald frame 1 is driven by the moving element.
 
            [0100] The movement profile 70 of the moving element can be determined as described above,
               wherein in particular a zero-crossing line 53 and a zero-crossing moment 48 are determined.
 
            [0101] The height detector target 51 is for example a protrusion and the height detector
               sensor element 52 is configured for example to detect a rising edge of the height
               detector target 51 when the height detector target 51 is approaching the height detector
               sensor element 52 from above and from below.
 
            [0102] Hence, driving the heald frame 1 with the drive mechanism 2 to move up and down in
               the weaving direction and in the reverse direction, similar as explained in Fig. 5,
               in the embodiment shown four height detector target detecting moments can be determined,
               namely a first height detector target detecting moment 1.51, a second height detector
               target detecting moment 2.51, a third height detector target detecting moment 3.51,
               and a fourth height detector target detecting moment 4.51 as illustrated in Fig. 12.
 
            [0103] In the embodiment shown, in a standard height position the heald frame 1 is connected
               to the drive mechanism 2 such that a center of the height detector target 51 is arranged
               opposite the height detector sensor element 52, when the center of the middle target
               44 is arranged opposite the sensor element 42. The movement profile 80 of the heald
               frame 1, when the heald frame 1 is set in the standard height position is shown in
               a solid line, is referred to as standard movement profile 80. For this standard movement
               profile 80, for example the zero-crossing moment 48 of the movement profile 70 coincides
               with the moment in which the height detector target 51 is opposite the height detector
               sensor element 52.
 
            [0104] For setting the standard height position of the heald frame 1 the drive mechanism
               2 can be arranged in a standard position, preferably the zero position, while the
               height target detector 51 and/or the height detector sensor element 52 are mutually
               shifted up and down until the height detector target 51 is arranged opposite the height
               detector sensor element 52. In this way, a zero-crossing line 82 of the standard movement
               profile 80 crosses the standard movement profile 80 at the standard zero-crossing
               height target detecting moment 76, which in the example coincides with the zero-crossing
               moment 48 of the movement profile 70. In this example, the zero-crossing moment 48
               also coincides with the middle target detecting moment 64 of Fig. 9.
 
            [0105] To this end the zero-crossing line 82 for the standard movement profile 80 can determined
               based on the first height detector target detecting moment 1.51, the second height
               detector target detecting moment 2.51, the third height detector target detecting
               moment 3.51 and/or the fourth height detector target detecting moment 4.51, for example
               is determined based on the first height detector target detecting moment 1.51 and
               the fourth height detector target detecting moment 4.51.
 
            [0106] When attaching the heald frame 1 in a different height position to the drive mechanism
               2, a movement profile 81 of the heald frame 1 is shifted in position. The height position
               of the heald frame 1 relative to the drive mechanism 2 can for example be changed
               by changing the distance between the levers 12, 16, 17 and the heald frame 1, such
               as described in 
EP520540A1. Of course, other height position setting devices can be used, for example as described
               in 
EP2619361 or in 
EP1322805B1.
 
            [0107] Fig. 12 shows in a dashed line a movement profile 81 of a heald frame 1 attached
               in a position above the standard height position to the drive mechanism 2. As shown
               in Fig. 12, in this case, the height detector target 51 passes the height detector
               sensor element 52 before the zero-crossing moment 48, i.e. the zero-crossing height
               target detecting moment 66 of the heald frame 1 is before the zero-crossing moment
               48 of the moving element.
 
            [0108] The movement profile 81 of the heald frame 1 follows the movement profile 70 of the
               moving element. Hence, based on the movement profile 70 of the moving element and
               an absolute height position of the heald frame 1 detected by the height detector 50,
               a relative position of the heald frame 1 with respect to a zero position of the moving
               element can be determined, in other words a relative height position of the heald
               frame 1 can be determined.
 
            [0109] For the standard movement profile 80 representing the standard height position as
               explained above, the standard zero-crossing height target detecting moment 76 of the
               standard movement profile 80 coincides with is the zero-crossing moment 48 of the
               movement profile 70.
 
            [0110] For a different movement profile 81 a first height detector target detecting moment
               1.61, a second height detector target detecting moment 2.61, a third height detector
               target detecting moment 3.61 and/or a fourth height detector target detecting moment
               4.61 can be determined and based on these height detector target detecting moments,
               the zero-crossing height target detecting moment 66 for the movement profile 81 can
               be determined, for example based on the first height detector target detecting moment
               1.61 and the fourth height detector target detecting moment 4.61.
 
            [0111] The angular distance D5 between the zero-crossing moment 48 and the zero-crossing
               height target detecting moment 66 determines a value that is in relation to, in particular
               is proportional to the relative height position of the heald frame 1, which for example
               can be determined by geometrical calculation based on the distance D5 and the determined
               movement profile. For the movement profile 81 with respect to the standard movement
               profile 80, the height position is indicated by an arrow H5 in Fig. 12. In Fig. 12
               the arrow H5 points upwards, which means that the heald frame 1 is arranged further
               away from the drive mechanism 2 such that the height detector target 51 reaches the
               height detector sensor element 52 before the moving element reaches its zero position.
               Alternatively, if the heald frame 1 is arranged closer to the drive mechanism 2, the
               height detector target 51 will reach the height detector sensor element 52 after the
               moving element reaches its zero position, such that the associated arrow will point
               downwards.
 
            [0112] Fig. 13 shows a determination of a height position of a heald frame 1 using a height
               detector 52 via another way. In this example, the zero-crossing moment 48 is determined
               based on the upper target detecting moment 63 and the lower target detecting moment
               65. When using a sensor device 40 as shown in Fig. 3, wherein the zero position line
               46 is arranged in the bisector of both central lines 27, 28, the zero-crossing moment
               48 can be determined as the average of the upper target detecting moment 63 and the
               lower target detecting moment 65. The heald frame 1 can also be arranged in a height
               position such that the zero-crossing moment 48 coincides with the standard zero-crossing
               height target detecting moment 76 when the standard movement profile 80 crosses the
               zero-crossing line 82 of the standard movement profile 80. The relative height position
               of the heald frame 1 can further be determined as in the example of Fig. 12.
 
            [0113] Both methods as described with reference to Figs. 12 and 13 in an embodiment are
               used in combination for determining the height position of the heald frame 1 in two
               alternative ways, thereby determining the height position more accurately, for example
               based on an average of the values obtained by the two alternative ways.
 
            [0114] As will be understood by the person skilled in the art, detecting a height detector
               passing moment of a heald frame and determining a height position of the heald frame
               based on the height detector passing moment with any of the methods described above
               with reference to Fig. 12 and 13 does not necessarily require that a configuration
               of the drive mechanism is determined using a target set 41 having three targets 43,
               44, 45 as shown in Fig. 3 and/or that a moving element of the drive mechanism is equipped
               with three targets.
 
            [0115] Rather, in the exemplary method described with reference to Fig. 12, only target
               detection moments are used that are based on the middle target 44, while in the exemplary
               method described with reference to Fig. 13 only target detection moments are used
               that are based on the upper target 43 and the lower 45.
 
            [0116] As will be understood by the person skilled in the art, the standard height position
               can also be determined using the method described with reference to Fig. 12 based
               on the upper target 43 or based on the lower target 45, instead of based on the middle
               target 44. Similarly, the standard height position can also be determined using the
               method described with reference to Fig. 13 based on the upper target 43 and the middle
               target 44, or based on the lower target 45 and the middle target 44, instead of based
               on the upper target 43 and the lower target 45.
 
            [0117] In other words, the above in general discloses a method for determining a height
               position of the heald frame in relation to a standard height position based on the
               height detector passing moment, the zero-crossing line 53 and/or the zero-crossing
               moment 48, wherein the height detector passing moment is determined using the height
               detector 50 comprising the height detector sensor element 52 and the height detector
               target 51 provided on the heald frame 1, and wherein the zero-crossing line 53 and
               the zero-crossing moment 48 are determined using a sensor device with a sensor element
               and at least one target provided on a moving element of the drive mechanism, in particular
               exactly one target, two targets or three targets.
 
            [0118] In an embodiment the height position of the heald frame 1 is determined in two alternative
               ways using a sensor device with a target set having two targets, wherein the height
               position is determined based on an average of the values obtained by the two alternative
               ways.
 
            Binding Pattern
[0119] In the embodiments described above, a movement profile was determined having a 1:1
               binding pattern, wherein in each weaving cycle the heald frame 1 is moved up or down.
               However, weaving with different binding patterns is well known.
 
            [0120] Typically, in case the drive mechanism 2 is a dobby mechanism or a motor driven mechanism,
               the binding pattern is known to a control unit of the weaving machine and no determination
               is necessary.
 
            [0121] However, for a drive mechanism in form of a cam mechanism, typically the binding
               pattern is not known to the control unit of the weaving machine and needs to be manually
               input by a user.
 
            [0122] Therefore, in one embodiment, the determination of the configuration of the drive
               mechanism 2 in alternative or in addition comprises a determination of a binding pattern
               based on the data of the sensor device 40 having a target set 41 with three targets.
               Such a determination can also be used for verifying the correctness of a binding pattern,
               in case a dobby mechanism or a motor driven mechanism is used.
 
            [0123] Fig. 14 shows a movement profile 70 of a moving element for a binding pattern over
               six weaving cycles, and shows the movement profile 70 over twelve weaving cycles.
 
            [0124] In order to determine the binding pattern, in one embodiment, the drive mechanism
               2 (see Fig. 1) is driven in a forward or weaving direction and a movement direction
               of the heald frame 1 and/or the moving element driving the heald frame 1 is determined.
               Such a determination in an embodiment is carried out based on determined target detecting
               moments 1.43, 2.43, 1.44, 2.44, 1.45, 2.45 when moving in a weaving direction (see
               Fig. 5).
 
            [0125] The number of weaving cycles for the determination is chosen based on a maximum number
               of weaving cycles for possible binding patterns. In one embodiment, e.g. for a cam
               mechanism, wherein the maximum number of weaving cycles for a binding pattern is six
               weaving cycles, as described above the configuration can be determined when the target
               set passes the sensor element at least eleven times. This allow to determine the binding
               pattern irrespectively if the binding pattern has a number of weaving cycles less
               than six weaving cycles.
 
            [0126] Based on the determined target detecting moments 1.43, 2.43, 1.44, 2.44, 1.45, 2.45
               it can be determined, when the moving element, in particular the lever 17, is moved
               to drive the heald frame 1 into a first extreme position and for how many weaving
               cycles the heald frame 1 is maintained in the first extreme position, and when the
               moving element is moved to drive the heald frame 1 into the second extreme position
               and for how many weaving cycles the heald frame 1 is maintained in the second extreme
               position.
 
            [0127] In one embodiment, for a determination of the binding pattern starting from an unknown
               initial position, a movement direction of the heald frame is determined.
 
            [0128] For this purpose, in the embodiment shown in Fig. 2, a distance between the upper
               target 43 and the middle target 44 differs from a distance between the middle target
               43 and the lower target 45. It should be noted that the difference in distance in
               the embodiment shown is achieved by providing targets 43, 45 of different length.
               In alternative or in addition, the difference in distance is achieved by providing
               notches 30, 31 of different length between the targets 43, 44, 45.
 
            [0129] Due to the different distances, a movement direction of the lever 17 can be determined
               based on angular distances between determined target detecting moments 1.43, 2.43,
               1.44, 2.44, 1.45, 2.45 and/or moments derived from said determined target detecting
               moments 1.43, 2.43, 1.44, 2.44, 1.45, 2.45. It should be noted that for this purpose
               it is not necessary to determine the exact values of the target detecting moments
               1.43, 2.43, 1.44, 2.44, 1.45, 2.45, but a signal pattern can be sufficient.
 
            [0130] In one embodiment, the determination of the movement direction is carried out by
               using only a subset of two targets of the target set.
 
            [0131] In Fig. 5 the target detecting moments 1.43, 4.43, 1.44, 4.44, 1.45, 4.45, 2.43,
               3.43, 2.44, 3.44, 2.45, 3.45 are determined during two weaving cycles. For a binding
               pattern as in Fig. 14 it is possible to determine the detecting moments 1.43, 4.43,
               1.44, 4.44, 1.45, 4.45, 2.43, 3.43, 2.44, 3.44, 2.45, 3.45 during a number of different
               weaving cycles, for example over six weaving cycles, and to take an average value
               for the respective detecting moments 1.43, 4.43, 1.44, 4.44, 1.45, 4.45, 2.43, 3.43,
               2.44, 3.44, 2.45, 3.45. For example, the detecting moments 1.43, 1.44, 1.45, 4.45,
               4.44, 4.43 can be detected one time in the area 67, while the detecting moments 2.43,
               2.44, 2.45, 3.45, 3.44, 3.43 can be detected one time in the area 68 and one time
               in the area 69, so that an average of these detecting moments can be determined as
               respective detecting moments. The embodiment of Fig. 5 can be seen as determining
               the respective detecting moments in the areas 67 and 69 of the binding pattern of
               Fig. 14.
 
          
         
            
            1. Method for determining with a sensor device (40) a configuration of a drive mechanism
               (2) having a moving element (12, 16, 17, 20, 21, 22) for driving a heald frame (1)
               of a weaving machine, wherein the sensor device (40) comprises a target set (41) provided
               on the moving element (12, 16, 17, 20, 21, 22) of the drive mechanism (2) with an
               upper target (43) and a lower target (45), and the sensor device (40) comprises a
               sensor element (42) arranged stationary on the weaving machine and configured for
               detecting a presence of the targets (43, 45) of the target set (41) within a sensing
               range, wherein the method comprises operating the drive mechanism (2) to move the
               moving element (12, 16, 17, 20, 21, 22) so that the target set (41) passes the sensor
               element (42), detecting with the sensor element (42) the presence of the upper target
               (43) and the lower target (45) within the sensing range, and determining an upper
               target detecting moment (63) in a weaving cycle upon detecting the upper target (43)
               and determining a lower target detecting moment (65) in a weaving cycle upon detecting
               the lower target (45), characterized in that the method comprises detecting with the sensor element (42) the presence of a middle
               target (44) within the sensing range, wherein the middle target (44) is provided on
               the moving element (12, 16, 17, 20, 21, 22) of the drive mechanism (2) and arranged
               between the upper target (43) and the lower target (45), determining a middle target
               detecting moment (64) in the weaving cycle upon detecting the middle target (44),
               and determining a configuration of the drive mechanism (2) based on the upper target
               detecting moment (63), the middle target detecting moment (64), and the lower target
               detecting moment (65).
 
            2. The method according to claim 1, characterized in that the sensor element (42) is a proximity sensor, wherein the targets (43, 44, 45) are
               protrusions provided at the moving element (12, 16, 17, 20, 21, 22), which protrusions
               are separated by notches, wherein the method comprises detecting with the sensor element
               (42) rising edges of the targets (43, 44, 45) when moving the targets (43, 44, 45)
               into the sensing range.
 
            3. The method according to claim 1 or 2, characterized in that the drive mechanism (2) is operated in a weaving direction to move the moving element
               (12, 16, 17, 20, 21, 22) back-and-forth so that the target set (41) passes the sensor
               element (42) from below and from above, wherein the presence of the targets (43, 44,
               45) within the sensing range is detected when passing the sensor element (42) from
               below and from above, and wherein target detecting moments are determined, which target
               detecting moments include a first upper target detecting moment (1.43) in the weaving
               cycle upon detecting the upper target (43) when passing the sensor element (42) from
               below, a second upper target detecting moment (2.43) in the weaving cycle upon detecting
               the upper target (43) when passing the sensor element (42) from above, a first middle
               target detecting moment (1.44) in the weaving cycle upon detecting the middle target
               (44) when passing the sensor element (42) from below, a second middle target detecting
               moment (2.44) in the weaving cycle upon detecting the middle target (44) when passing
               the sensor element (42) from above, a first lower target detecting moment (1.45) in
               the weaving cycle upon detecting the lower target (45) when passing the sensor element
               (42) from below, and a second lower target detecting moment (2.45) in the weaving
               cycle upon detecting the lower target (45) when passing the sensor element (42) from
               above.
 
            4. The method according to claim 3, characterized in that the drive mechanism (2) is operated in a reverse direction to move the moving element
               (12, 16, 17, 20, 21, 22) back-and-forth so that the target set (41) passes the sensor
               element (42) from below and from above, wherein the presence of the targets (43, 44,
               45) within the sensing range is detected when passing the sensor element (42) from
               below and from above, and wherein target detecting moments are determined, which target
               detecting moments include a third upper target detecting moment (3.43) in the weaving
               cycle upon detecting the upper target (43) when passing the sensor element (42) from
               below, a fourth upper target detecting moment (4.43) in the weaving cycle upon detecting
               the upper target (43) when passing the sensor element (42) from above, a third middle
               target detecting moment (3.44) in the weaving cycle upon detecting the middle target
               (44) when passing the sensor element (42) from below, a fourth middle target detecting
               moment (4.44) in the weaving cycle upon detecting the middle target (44) when passing
               the sensor element (42) from above, a third lower target detecting moment (3.45) in
               the weaving cycle upon detecting the lower target (45) when passing the sensor element
               (42) from below, and a fourth lower target detecting moment (4.45) in the weaving
               cycle upon detecting the lower target (45) when passing the sensor element (42) from
               above.
 
            5. The method according to claim 3 or 4, characterized in that determining the configuration of the drive mechanism (2) comprises determining a
               zero-crossing moment (48) in the weaving cycle when the moving element (12, 16, 17,
               20, 21, 22) is in a zero position based on two determined middle target detecting
               moments (64), which determined middle target detecting moments (64) have been determined
               upon detecting the middle target (44) when passing the sensor element (42) from above
               and from below, wherein in particular the middle target (44) is arranged symmetrically
               to a zero position line (46) when the moving element is in a zero position and the
               sensor element (42) is arranged at a height of the zero position line (46).
 
            6. The method according to claim 5, characterized in that determining the configuration of the drive mechanism (2) comprises determining a
               movement profile type, wherein information about different movement profile types
               is pre-stored, and the movement profile type is determined based on the determined
               zero-crossing moment (48).
 
            7. The method according to any one of claims 3 to 6, characterized in that determining the configuration of the drive mechanism (2) comprises determining a
               crossing moment (49), wherein a reversal point moment (47) in the weaving cycle, when
               the moving element (12, 16, 17, 20, 21, 22) is in one of its reversal points, is determined
               based on the determined target detecting moments, and the crossing moment (49) is
               defined based on the reversal point moment (47).
 
            8. The method according to claim 7, characterized in that determining the configuration of the drive mechanism (2) comprises determining a
               crossing height (H1, H2, H3) at the crossing moment relative to the zero position
               based on the movement profile type.
 
            9. The method according to any one of claims 1 to 8, characterized in that determining the configuration of the drive mechanism (2) comprises determining a
               stroke of the heald frame (1), wherein the stroke is determined via a first way based
               on the upper target detecting moment (63) and the lower target detecting moment (65),
               and wherein the stroke is determined via another way, which another way is selected
               out of a group comprising a second way based on the upper target detecting moment
               (63) and the middle target detecting moment (64), a third way based on the middle
               target detecting moment (64) and the lower target detecting moment (65), and a fourth
               way based on distances, in particular notches (30, 31), between the upper target (43)
               and the middle target (44) and the middle target (44) and the lower target (45).
 
            10. The method according to claim 9, characterized in that the stroke is determined using an assumed movement profile type selected out of a
               plurality of pre-stored movement profile types.
 
            11. The method according to any one of claims 1 to 10, characterized in that a distance between the upper target (43) and the middle target (44) differs from
               a distance between the middle target (44) and the lower target (45), wherein the method
               comprises determining a movement direction of the moving element (12, 16, 17, 20,
               21, 22) based on a first angular distance between a first moment when detecting a
               first target of the target set (41) and a second moment when detecting a second target
               of the target set (41) and a second angular distance between the second moment when
               detecting a second target of the target set (41) and a third moment when detecting
               a third target of the target set (41).
 
            12. The method according to any one of claims 1 to 11, characterized in that determining the configuration of the drive mechanism (2) comprises determining a
               binding pattern, wherein the drive mechanism (2) is operated over a number of weaving
               cycles to move the moving element (12, 16, 17, 20, 21, 22) back-and-forth.
 
            13. The method according to any one of claims 1 to 12, characterized in that a height detector passing moment of the heald frame (1) is detected and a height
               position of the heald frame (1) is determined based on the height detector passing
               moment and the determined configuration of the drive mechanism (2), in particular
               using an assumed movement profile type selected out of a plurality of pre-stored movement
               profile types.
 
            14. Moving element of a drive mechanism (2) for driving a heald frame (1) of a weaving
               machine comprising a target set (41) with an upper target (43) and a lower target
               (45), characterized in that the target set (41) comprises a middle target (44), wherein the middle target (44)
               is arranged between the upper target (43) and the lower target (45), wherein in particular
               the targets (43, 44, 45) are protrusions provided at the moving element (12, 16, 17,
               20, 21, 22), in particular at a side end of the moving element (12, 16, 17, 20, 21,
               22), which protrusions are separated by notches.
 
            15. Moving element according to claim 14, characterized in that the moving element is a lever (17), in particular a lever (17) arranged at a non-driven
               side of the drive mechanism (2).
 
            16. System comprising a control device (25), a drive mechanism (2) for driving a heald
               frame (1) of a weaving machine, the drive mechanism (2) having a moving element (12,
               16, 17, 20, 21, 22), and a sensor device (40) with a target set (41) provided on the
               moving element (12, 16, 17, 20, 21, 22) and with a sensor element (42) mountable stationary
               on the weaving machine and configured for detecting a presence of targets (43, 44,
               45) of the target set (41) within a sensing range, wherein the target set (41) comprises
               an upper target (43) and a lower target (45), wherein the drive mechanism (2) is configured
               for being operated to move the moving element (12, 16, 17, 20, 21, 22) so that the
               target set (41) passes the sensor element (42), wherein the control device (25) is
               configured for determining an upper target detecting moment (63) in a weaving cycle
               upon detecting the upper target (43) and a lower target detecting moment (65) in a
               weaving cycle upon detecting the lower target (45), characterized in that the target set (41) comprises a middle target (44), wherein the middle target (44)
               is arranged between the upper target (43) and the lower target (45), wherein the control
               device (25) is configured for determining a middle target detecting moment (64) in
               a weaving cycle upon detecting the middle target (44), and wherein the control device
               (25) is configured for determining a configuration of the drive mechanism (2) based
               on the upper target detecting moment (63), the middle target detecting moment (64),
               and the lower target detecting moment (65).
 
            17. The system according to claim 16, characterized in that the sensor element (42) is a proximity sensor, wherein the targets are protrusions
               provided at the moving element (12, 16, 17, 20, 21, 22), in particular at a side end
               of the moving element (12, 16, 17, 20, 21, 22), which protrusions are separated by
               notches, wherein the sensor device (40) is configured for detecting with the sensor
               element (42) rising edges of the targets (43, 44, 45) when moving the targets (43,
               44, 45) into the sensing range.
 
            18. The system according to claim 16 or 17, characterized in that the system has a height detector (50) configured for detecting a height detector
               passing moment of a heald frame (1) and for determining a height position of the heald
               frame (1) based on the height detector passing moment and the determined configuration
               of the drive mechanism (2), in particular using an assumed movement profile type selected
               out of a plurality of pre-stored movement profile types, wherein in particular the
               height detector (50) comprises a height detector target (51) provided on a heald frame
               (1) driven by the moving element (12, 16, 17, 20, 21, 22) and a height detector sensor
               element (52).