BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a technique for preventing weft bars from being
formed upon stoppage of a loom by setting the loom on standby with the warp shed in
a closed state (leveling state). In particular, the present invention relates to a
technique for preventing disadvantages caused by an operational error made when the
loom is in such a standby state.
2. Description of the Related Art
[0002] In order to satisfy an increasing demand for high-value-added weaving products, an
increasing number of weaving mills use looms that have shedding devices capable of
easily editing weave structures (for example, a dobby device, a jacquard device, an
electric shedding device that drives heald frames in a shedding motion using designated
motors, etc.) so that various weave structures can be attained. With these shedding
devices, complex weaves, such as twill weaves, satin weaves, and dobby weaves, can
be readily attained using shedding patterns of the corresponding weaving specifications.
In these shedding devices, however, the heald frames are driven in a shedding motion
in which some of the heald frames are maintained at the same shedding position for
one or more picks. For this reason, even when the loom main shaft is rotated in the
reverse direction to the cross timing of the shedding device to set the loom on standby,
it is not possible to set all of the warp threads in a closed-shed state. Consequently,
if the operator arrives late to the loom such that the loom is kept stopped for a
long period of time, a tension difference (stretching of the warp threads) may occur
between the upper and lower warp threads, leading to formation of weft bars.
[0003] As a device for solving this problem,
Japanese Unexamined Patent Application Publication No. 6-116841 (Figs. 1 to 14) (hereinafter referred to as Document 1), for example, discloses a
loom equipped with an electronic dobby device having a leveling function. To briefly
describe this loom, when a cause of stoppage occurs, the loom is temporarily stopped,
and an inverted shedding pattern to be used in the next step is subsequently output,
the inverted shedding pattern being obtained by inverting upper and lower heald positions
in the shedding pattern used in the current step. While the inverted shedding pattern
is being output, the loom main shaft is rotated in the reverse direction to an angle
corresponding to the cross timing of the shedding device so that the warp shed is
set to a central closed-shed state. Before the reactivation of the loom, there is
a case where, if the cause of stoppage is, for example, weft stopping, it is necessary
to remove the defective weft thread after the leveling state has been cancelled by
rotating the loom main shaft forward at low speed to a predetermined angle (in other
words, in a case where the operator commands the loom for activation after commanding
the loom for a reverse rotation). There is also a case where such a weft removal process
is not necessary, such as when the stoppage is caused by other factors (such as warp
stopping). In that case, the loom is directly activated after the broken thread, such
as broken warp, has been repaired. In other words, the procedure to be implemented
before the reactivation of the loom varies depending on the cause of stoppage. Therefore,
if the operator erroneously operates the loom without realizing the cause of stoppage,
the operational error will inevitably lead to defects in the woven cloth. In contrast,
in the technique disclosed in Document 1, the operation to be performed by the operator
after the loom has been set on standby in the leveling state is integrally performed
by means of a recovery button or an activation button, and when one of these buttons
is operated, a control device selects an activation sequence that corresponds to the
cause of stoppage. Accordingly, the loom main shaft is rotated to a predetermined
angle, and the loom is activated.
[0004] However, in weaving mills, there are many looms equipped with shedding devices that
do not have a leveling function, or even if the looms do have a leveling function,
the leveling function may be set in an inoperative mode depending on the weaving specifications.
For example, if weft stopping occurs in a loom not having a leveling function, the
operator commands the loom in the standby state for a reverse rotation so that a defectively
inserted weft thread can be removed. Subsequently, the loom undergoes a reverse rotation
to a predetermined activation position and is then reactivated.
[0005] In contrast, for an operator in charge of a mixture of looms with the leveling function
set in an operative mode and looms with the leveling function set in an inoperative
mode, there are cases where the operator intuitively operates operation buttons of
the looms without being aware of these set conditions, which can lead to serious defects
in the quality of the woven cloths. More specifically, when the loom in Document 1
is in a standby state with the leveling function set in an operative mode, the operator
should normally operate a recovery button or an activation button. However, there
are cases where the operator mistakenly believes that the loom does not have a leveling
function set therein and thus erroneously operates a reverse-rotation button. When
the loom undergoes further reverse rotation from the leveling state attained on the
basis of the inverted shedding pattern, the tensile relationships among the warp threads
in the open-shed state become vertically inverted, causing the cloth-fell position
to become displaced by a large amount. This can cause formation of a new weft bar
upon activation of the loom. In addition, as the loom undergoes further reverse rotation
without the operator realizing that he/she has made the operational error, the cloth
fell displaced in the upper or forward direction and the reed moved forward interfere
with each other, resulting in a cloth breakage. In either case, the quality of the
woven cloth becomes seriously impaired.
[0006] These problems are not limited to a type of loom in which the operation to be performed
by the operator after the loom has been set on standby in the leveling state is integrally
performed by means of a designated button. Such problems can occur in looms in which
the central closed-shed state is attained by rotating the loom main shaft in the reverse
direction while outputting an inverted shedding pattern to be used in the subsequent
step, which is obtained by inverting the current shedding pattern. However, there
are no known techniques for restricting the operation by the operator with respect
to looms that have the possibility of quality impairment of woven cloth caused by
such an operational error.
SUMMARY OF THE INVENTION
[0007] Accordingly, it is an object of the present invention to provide a technique for
preventing quality impairment of woven cloth in a loom equipped with a shedding device
having a leveling function by prohibiting a reverse rotation even if the operator
erroneously commands the loom to perform a reverse rotation. Specifically, such a
loom is a type in which a central closed-shed state is attained by rotating a loom
main shaft in the reverse direction while outputting an inverted shedding pattern
to be used in the subsequent step, which is obtained by inverting the current shedding
pattern.
[0008] According to an aspect of the present invention, an operational-error preventing
device for a loom includes a main controller that receives a loom-main-shaft-angle
signal and also controls the driving of a loom main shaft in response to input of
an operation-button signal including a reverse-rotation button signal, and a shedding
device having a plurality of shedding patterns preliminarily set therein in correspondence
to a plurality of steps and driving a plurality of healds in response to a rotation
of the loom main shaft on the basis of a selected one of the shedding patterns. When
the shedding device receives a leveling command output from the main controller, the
shedding device changes a shedding pattern to be used for driving the healds in the
subsequent step to an inverted shedding pattern obtained by inverting upper and lower
positions of the healds in the current shedding pattern. When a cause of stoppage
occurs in the course of a weaving operation, the main controller stops the loom main
shaft, the main controller then outputting the leveling command and allowing the loom
main shaft to rotate automatically in the reverse direction to a set angle so that
a warp shed of the loom is set to a central closed-shed state. The main controller
has a reverse-rotation prohibition angle preliminarily set therein, the reverse-rotation
prohibition angle being set within a main-shaft-angle range in which the shedding
device is driven on the basis of the inverted shedding pattern. When a main-shaft
angle reaches the reverse-rotation prohibition angle due to the automatic reverse
rotation executed after the loom main shaft has been stopped or a reverse rotation
executed in response to the input of the reverse-rotation button signal, the main
controller prohibits the reverse rotation of the loom main shaft even if the main
controller receives the reverse-rotation button signal.
[0009] The "set angle" used for stopping the automatic reverse rotation of the loom main
shaft is set to a cross timing (i.e. an angle at which the healds being driven become
closed) of the warp shedding device or near the cross timing. The cross timing of
the shedding device is a set parameter related to a connection phase between the loom
main shaft and a drive shaft and indicates a loom-main-shaft angle at which the shed
amount of the vertically driven healds is zero. However, in the present invention,
the central closed-shed state is not specifically limited to a state where the shed
amount of warp threads is zero, and may include a state where the shed amount of warp
threads is several centimeters or less (more specifically, 2 cm or less). With this
shed amount, weft bars are substantially prevented or are relatively unnoticeable.
The range of the aforementioned cross timing serving as a set range for the aforementioned
"set angle" includes a main-shaft angle at which the shed amount of warp threads due
to the driven healds is several centimeters or less.
[0010] The expression "a main-shaft-angle range in which the shedding device is driven on
the basis of the inverted shedding pattern" will be described in more detail. This
range indicates a range in which information corresponding to the inverted shedding
pattern to be used in the subsequent step is output and then the heald frames are
actually driven on the basis of that information. Specifically, in terms of the main-shaft
angle, this range can be set above and below the cross timing of the shedding device,
at which the warp shed becomes in a central closed-shed state in response to a reverse
rotation, by 180° (total: 360°). Accordingly, the main-shaft angle which is the start
point and end point of the range within which the heald frames are driven, namely,
the main-shaft angle at which the shed amount of warp threads is at the maximum, is
excluded from the reverse-rotation prohibition angle set within the aforementioned
range.
[0011] According to the above-described aspect of the present invention, even when the operator
erroneously operates the reverse-rotation button, the main controller prohibits the
reverse rotation of the loom main shaft if the main-shaft angle exceeds the reverse-rotation
prohibition angle within the range in which the shedding device is driven on the basis
of the inverted shedding pattern. Accordingly, this prevents quality impairment of
woven cloth, such as formation of weft bars caused by a displaced cloth fell or a
cloth breakage caused by a beating motion resulting from driving of the loom main
shaft, namely, the warp shedding device, in response to an erroneous reverse-rotation
command.
[0012] The reverse-rotation prohibition angle is set to an angle at which the quality impairment
of woven cloth actually does not occur. The reverse-rotation prohibition angle may
be set to an angle preliminarily determined by the manufacturer in view of the above
or may be adjustable by the user.
[0013] Like the aforementioned "set angle", the reverse-rotation prohibition angle is preferably
set to or near the cross timing (closed-shed timing) of the shedding device. This
range for the reverse-rotation prohibition angle includes a main-shaft-angle range
in which the shed amount of warp threads shed by the driven healds is several centimeters
or less (for example, a range above and below the cross timing of the shedding device
by 50°). Accordingly, a reverse rotation that causes the cloth-fell position to become
displaced by a large amount can be prohibited. More preferably, the reverse-rotation
prohibition angle is set equal to the set angle at which the aforementioned automatic
reverse rotation is stopped. Accordingly, when the loom is set on standby with the
warp shed in a central closed-shed state due to an occurrence of a cause of stoppage,
a manual reverse-rotating operation cannot be performed, whereby the aforementioned
quality impairment of woven cloth can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]
Fig. 1 is a block diagram showing the inside of a control device for a loom and a
shedding device, which function as an operational-error preventing device;
Fig. 2 illustrates the operation of the shedding device from a point at which the
loom is set on standby with a warp shed in a central closed-shed state due to an occurrence
of a weft breakage, which is a kind of a weft-insertion error, to a point at which
the loom is reactivated, Fig. 2 showing two set ranges for a reverse-rotation prohibition
angle respectively indicated by circled letters "a" and "b" below the horizontal axis
(main-shaft angle);
Figs. 3A and 3B illustrate two kinds of shedding patterns, respectively, Fig. 3A showing
normal shedding patterns and Fig. 3B showing inverted patterns obtained by inverting
the normal shedding patterns;
Fig. 4 is a flowchart of a process executed by a main controller serving as the operational-error
preventing device according to the present invention, the process being performed
after the loom is stopped with the warp shed in the central closed-shed state;
Fig. 5 illustrates the warp shed and the cloth-fell position when the main shaft is
at an angle indicated by a circled letter "A" in Fig. 2;
Fig. 6 illustrates the warp shed and the cloth-fell position when the main shaft is
at an angle indicated by a circled letter "B" in Fig. 2;
Fig. 7 illustrates the warp shed and the cloth-fell position when the main shaft is
at an angle indicated by a circled letter "C" in Fig. 2; and
Fig. 8 illustrates the warp shed and the cloth-fell position when the main shaft is
at an angle indicated by a circled letter "D" in Fig. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] An exemplary embodiment of the present invention will now be described with reference
to the drawings.
[0016] Fig. 1 is a block diagram showing the inside of a control device 10 for a loom and
a warp shedding device 50 for generating a warp shedding motion. The control device
10 functioning as a control system for the loom mainly includes a setting unit 12
for setting various weaving parameters and a main controller 14 for controlling the
loom on the basis of the set parameters input to the setting unit 12 and other input
data.
[0017] The main controller 14 includes an input port 16 that receives input signals, an
output port 18 that outputs output signals, a central processing unit (CPU) 20 that
outputs control signals to various circuits, and a storage unit 22 that stores various
kinds of information. In the storage unit 22, a plurality of control programs (control
routines) written by the machinery manufacturer is preliminarily stored. The storage
unit 22 also temporarily stores control data, such as a current control value.
[0018] The main controller 14 is connected to a drive circuit 28 for driving a main-shaft
motor 26, and to a drive circuit 32 for driving an electromagnetic brake 30. Furthermore,
although not shown, the main controller 14 is also connected to a take-up control
circuit for driving a take-up motor, a let-off control circuit for driving a let-off
motor, and a weft-insertion controller for controlling weft insertion. These circuits
are controlled on the basis of signals output from the main controller 14 via the
output port 18.
[0019] The main controller 14 is also connected to an activation button 41 operated for
activating the loom, an inching button 42 that functions as a low-speed forward-rotation
button operated when forward inching rotation is to be performed, a reverse rotation
button 43 that functions as a low-speed reverse rotation button operated when reverse
rotation is to be performed, and a stop button 44 operated when the loom in continuous
operation is to be stopped. Thus, the main controller 14 receives operation signals
from these operation buttons through the input port 16, the operation signals including
an activation operation signal S1, an inching operation signal S2, a reverse operation
signal S3, and a stop operation signal S4. In addition to these operation signals,
the main controller 14 also receives, through the input port 16, a weft-insertion
error signal S10 from a weft detection circuit 47, a warp breakage signal S11 from
a warp breakage sensor 48, and a main-shaft-angle signal θ from an angle-signal generator
46 connected to a loom main shaft 24. The CPU 20 executes the control programs (control
routines) stored in the storage unit 22 and controls the drive circuit 28, the drive
circuit 32, other circuits that are not shown, and a shedding controller 56 by outputting
one or more control signals thereto through the output port 18.
[0020] The main shaft 24 functioning as a crankshaft of the loom is connected to the angle-signal
generator (ENC) 46, such as a known absolute encoder, which detects the angle θ as
a rotational phase. The angle-signal generator 46 is capable of outputting the main-shaft-angle
signal θ of which the beating timing is set at 0°. The main-shaft-angle signal θ is
used by the main controller 14 for controlling the overall operation of the loom,
such as activating and stopping the loom. In addition, as described below, the main-shaft-angle
signal θ is also used for stopping the loom to set the loom in a central closed-shed
state upon occurrence of a cause of stoppage. This involves rotating the loom main
shaft 24 in the reverse direction and stopping the loom main shaft 24 at a set angle.
[0021] Depending on the type of signal output from the main controller 14 (namely, an activation
signal S5, a forward rotation signal S6, or a reverse rotation signal S7), the drive
circuit 28 supplies power to the main-shaft motor 26 in correspondence to a drive
mode (high-speed forward rotation, low-speed forward rotation, low-speed reverse rotation,
etc.). If the main-shaft motor 26 is, for example, an induction motor, the drive circuit
28 may include a known inverter that generates an alternating-current power having
a frequency that corresponds to the drive mode of the main-shaft motor 26. Alternatively,
the drive circuit 28 may also be a known drive circuit including a low-frequency-output
inverter device that functions as a low-speed drive source, a commercial power source
that functions as a high-speed drive source, and an electromagnetic switch that selectively
supplies the power output from the inverter device or the commercial power source
to the primary winding of the main-shaft motor 26.
[0022] When the loom is in operation, the drive circuit 28 receives an ON output of the
activation signal S5 (activation ON signal S5) from the main controller 14 and rotates
the main-shaft motor 26 forward at high speed, thus maintaining the normal operational
state of the loom. When the loom is to be driven forward at low speed, the drive circuit
28 receives an ON output of the forward rotation signal S6 (forward rotation ON signal
S6) and rotates the main-shaft motor 26 forward at low speed. When the loom is to
be driven in the reverse direction at low speed, the drive circuit 28 receives an
ON output of the reverse rotation signal S7 (reverse rotation ON signal S7) and rotates
the main-shaft motor 26 in the reverse direction at low speed.
[0023] When the forward rotation, the reverse rotation, or the operation of the loom is
to be terminated, the drive circuit 32 receives an ON output of a brake signal S8
(brake ON signal S8) from the main controller 14 and sends power to the electromagnetic
brake 30 necessary for braking the main shaft 24. The electromagnetic brake 30 may
be of any type as long as it can generate a braking force in response to a brake command,
and is not limited to a type that generates a braking force by applying an attractive
force to a disc by excitation.
[0024] The weft detection circuit 47 is a known circuit that determines whether or not a
weft thread is properly inserted during the normal operation of the loom on the basis
of a thread signal sent from a feeler head (not shown), such as an H1 feeler and an
H2 feeler. Such a feeler head is disposed on a weft traveling path and located near
the cloth edge that is distant from the thread feeding side. In the case of a weft
insertion error or weft breakage, the weft detection circuit 47 generates a weft-insertion
error signal S10 that indicates such a condition. The warp breakage sensor 48 is a
known sensor that has, for example, a plurality of pins through which the warp threads
individually extend. When a pin drops in response to a warp breakage, the warp breakage
sensor 48 electrically detects the pin and generates a warp breakage signal S11.
[0025] The setting unit 12 includes a touch panel having both a function for displaying
the conditions of the set parameters and control information of the loom in the form
of characters, numbers, or graphics and a function as a setting unit for inputting
information. The setting unit 12 exchanges information with the circuits in the main
controller 14 and the shedding controller 56. The parameters set in the setting unit
12 include parameters for starting and stopping the loom (the detailed operations
will be described below with reference to Fig. 2) and weaving parameters. The weaving
parameters include, for example, a weft density, a warp tension, information regarding
the types of weft and warp threads, set values for the weft-insertion controller,
the weft detection circuit 47, and the warp breakage sensor 48, a warp shedding pattern
for the warp shedding device 50, and a weft selection mode. The operator can input
set values into the setting unit 12 by touching a display section for setting values,
and then touching a selection menu and a keypad for inputting numerical values, etc.
displayed on a screen (not shown). In addition, selection information representing
whether or not to use a control function, such as a leveling function, for the above-described
electronic dobby device can be set in the setting unit 12 by operating the screen
(not shown).
[0026] On the other hand, the loom 1 includes the warp shedding device 50. In this embodiment,
an electronic dobby device is described as an example of a warp shedding device. Specifically,
such an electronic dobby device outputs an electric selection signal in accordance
with an electrically stored shedding pattern preliminarily set for each shedding step
number. Using the electronic dobby device, a shedding motion of each heald frame can
be arbitrarily selected.
[0027] The shedding device 50 basically includes a shedding-device drive shaft 52 connected
to the loom main shaft 24, the shedding controller 56, and a shedding-motion driving
mechanism 58. A plurality of healds 63 arranged in the cloth width direction and in
the warp traveling direction is held by a plurality of heald frames (not shown) extending
in the width direction. The shedding-motion driving mechanism 58 is a known mechanism
that can drive these heald frames individually. Moreover, the shedding-motion driving
mechanism 58 contains selection solenoids 57 having a plurality of solenoids that
correspond to the respective heald frames. Consequently, the shedding device 50 is
a known electronic dobby shedding device that drives the heald frames in accordance
with the driving modes of the plurality of solenoids. The drive shaft 52 is mechanically
connected to the shedding-motion driving mechanism 58 and serves as a power source
for moving each heald frame by transmitting the rotational force of the main shaft
24. In addition, the drive shaft 52 has a dog 53 attached thereto for generating two
step signals S16 and S17, and moreover, sensors 54 and 55 are arranged so as to detect
a detection piece of the dog 53 with an angular delay. The step signals S16 and S17
are obtained by the respective sensors 54 and 55 and are sent to the shedding controller
56.
[0028] The shedding controller 56 preliminarily receives information related to each shedding
step number set in the setting unit 12, the information including a drive mode of
each heald frame (selection of up-and-down motion of the heald frame) and an output
mode of selection signals used for switching weft threads in multicolor weft insertion
or for changing the weft insertion density. The received information is stored in
a storage unit (not shown) included in the shedding controller 56. The shedding controller
56 determines the rotating direction of the drive shaft 52, or in other words, the
rotating direction of the loom main shaft 24, on the basis of the step signals S16
and S17 from the respective sensors 54 and 55. The shedding controller 56 increments
or decrements the shedding step number by one in accordance with the number of turns
of the drive shaft 52, and updates the shedding pattern and the selection pattern
in a one-by-one fashion. Based on the updated shedding pattern and selection pattern,
the shedding controller 56 outputs a selection signal S18, which represents the drive
mode of each of the heald frames to be driven in the subsequent shedding step, to
the selection solenoids 57 provided as actuators for the respective heald frames through
an electronic circuit (not shown). In addition, the shedding controller 56 outputs
various selection signals S13, such as a weft selection signal, to the circuits included
in the loom and also outputs reversal-prohibiting signals S15a and S15b to the main
controller 14 to prohibit the reversal of the rotating direction when the loom is
in a reversal-prohibiting period that inevitably exists due to the structure of the
electronic dobby device. When the shedding controller 56 receives a leveling command
S14 from the main controller 14, the shedding controller 56 outputs the signal S18
on the basis of an inverted shedding pattern obtained by inverting a reverse-rotation
shedding pattern to be used in the subsequent shedding step for reverse rotation with
respect to a current shedding step number, thereby performing a leveling function
for setting the warp shed in a central closed-shed state.
[0029] Fig. 2 is a chart that shows transitions in the operational state of the loom. In
Fig. 2, the horizontal axis represents the loom-main-shaft angle θ, and the vertical
axis represents the output mode of each signal and the actual shedding pattern of
the warp threads. More specifically, Fig. 2 shows, from the top to the bottom of the
page, the actual warp shedding pattern, pattern numbers of the heald-frame patterns
output by the shedding controller 56 for forward and reverse rotations, and the logical
output states of the step signals S16 and S17 from the sensors 54 and 55, respectively.
In addition, the angular transition in the operational state that occurs in accordance
with the rotation of the loom main shaft is shown in a time-series fashion towards
the bottom of the page with the angle (timing) at which the weft-insertion error signal
S10 is generated being located at the center. Moreover, the actual warp shedding pattern
obtained when the leveling command S14 is input to the shedding controller 56 and
the logical output state of the heald-frame pattern output by the shedding controller
56 for reverse rotation are shown at the bottom.
[0030] A process for restarting the loom after an occurrence of a weft breakage, which is
one of the causes of stoppage in a continuous operation of the loom performing weft
insertion, will be described below as an example. This example is based on the assumption
that when a weft breakage occurs, the operator manually performs the recovery process
instead of using an automatic recovery device. This implies that the loom holds the
warp shed in a central closed-shed state while waiting for the operator to arrive.
In addition, the central closed-shed state is set using the leveling function of the
electronic dobby device, as described in detail below. These operations, including
the leveling function, are performed mainly in response to various commands output
from the main controller 14 and are implemented by executing the control programs
(control routines) stored in the main controller 14 or the shedding controller 56.
The process will be described in detail below with reference to Fig. 2.
[0031] Referring to Fig. 2, when a stoppage occurs during a continuous operation of the
loom, the main controller 14 determines the cause of stoppage on the basis of signals
output from the various sensors. Then, a process that corresponds to the determined
cause of stoppage is implemented. In this example, it is assumed that the cause of
stoppage is weft breakage. First, the weft detection circuit 47 detects a weft breakage
and outputs the weft-insertion error signal S10 at a main-shaft angle of 310°. The
main controller 14 then immediately turns off the activation signal S5 and outputs
the brake signal S8 for a predetermined period. Thus, the drive circuit 28 stops supplying
electricity to the main-shaft motor 26, and the drive circuit 32 activates the electromagnetic
brake 30 by supplying electricity thereto, thereby stopping the loom main shaft 24.
As a result, as shown in Fig. 2, the main shaft 24 rotates about one turn after the
detection of the weft insertion error and stops at 320°. It is needless to say that,
for causes of stoppage other than a weft insertion error, such as a warp breakage,
the processes corresponding to such causes are implemented.
[0032] Next, in order to set the loom 1 in a standby state in which the loom 1 waits for
the operator, the main controller 14 turns off the brake signal S8 and turns on the
reverse rotation signal S7 so that the main shaft 24 automatically rotates about one
turn in the reverse direction to 300° at which the warp shed is set to a central closed-shed
state. The main-shaft angle that corresponds to the standby state is an angle at which
the heald frames are set at the central closed-shed position, that is, a set cross
timing 300° of the shedding device 50. The reverse rotation is performed by executing
a control routine for rotating the main shaft 24 in the reverse direction until the
main shaft 24 reaches the angle 300° which is preliminarily set in the setting unit
12. The cross timing for the shedding device is appropriately set by adjusting the
connection phase between the main shaft 24 and the drive shaft 52, and is adequately
adjusted within the range of ± several tens of degrees in terms of the main-shaft
angle depending on the weaving specification. In Fig. 2, the cross timing for the
shedding device is set at 300°.
[0033] The operation of the electronic dobby device (shedding controller 56) will be briefly
described below. In the example shown in Fig. 2, the actual shedding pattern is set
such that a single repeat includes five cycles, i.e. 2 → 3 → 4 → 5 → 1···, which correspond
to five turns of the loom main shaft 24. A forward-rotation frame pattern that contributes
to the shedding pattern for forward rotation is generated in response to the step
signals S16 and S17 received from the respective sensors 54 and 55 such as to precede
the actual shedding pattern by one cycle as 3 → 4 → 5 → 1 → 2 ..., whereby a predetermined
shedding motion can be achieved. When the loom main shaft is rotated in the reverse
direction, that is, when the actual shedding pattern changes in the direction from
the right to the left of the figure as 5 → 4 → 3 → 2 ..., a reverse-rotation frame
pattern that contributes to the shedding pattern for reverse rotation is generated
in response to the step signals S16 and S17 such as to precede the actual shedding
pattern by one cycle as 4 → 3 → 2 → 1 ... in the direction from the right to the left
of the figure, whereby a predetermined shedding motion can be achieved. A period in
which the signal of the solenoid-selection shedding pattern is output corresponds
to a predetermined period in which a shedding motion in a certain cycle is changed
to a shedding motion in the subsequent cycle, that is, a range of a main-shaft angle
that corresponds to the maximum shed amount by the shedding device.
[0034] The reversal-prohibiting signals S15a and S15b are output from the shedding controller
56 on the basis of the step signals S16 and S17 from the sensors 54 and 55, respectively.
This is because the electronic dobby device has a period that prohibits a reversal
of rotating direction of the drive shaft 52, that is, a reversal of rotating direction
of the main shaft 24, due to the mechanism for selecting the heald-frame motion. If
the rotation of the drive shaft 52 is reversed within this prohibition period, a heald-frame
selection failure (so-called harness-skip) will occur. Accordingly, the shedding controller
56 determines a rotating direction of the drive shaft 52 when the activation signal
S5, the forward rotation signal S6, or the reverse rotation signal S7 from the main
controller 14 is turned on, and selectively outputs the reversal-prohibiting signal
S15a or S15b in synchronization with the step signal S16 or S17 depending on the determined
rotating direction. More specifically, when the rotating direction is forward, only
the reversal-prohibiting signal S15b that prohibits reversal from forward rotation
to reverse rotation is output in synchronization with the step signal S17. On the
other hand, when the rotating direction is reverse, only the reversal-prohibiting
signal S15a that prohibits reversal from reverse rotation to forward rotation is output
in synchronization with the step signal S16. The reversal-prohibiting signals S15a
and S15b are input to the main controller 14, and the main controller 14 prevents
a reversal of rotating direction of the loom main shaft, which is prohibited in accordance
with the state of signal input, from being executed when a manual operation button
is operated or automatic rotation is started.
[0035] Fig. 3A shows an example of the setting state of a normal shedding pattern for weaving
using five heald frames H1, H2, ..., H5. In Fig. 3A, the spaces with "x" show that
the heald frames are at the upper position, whereas the blank spaces show that the
heald frames are at the lower position. As the shedding step number changes from "1"
to "5" in the vertical direction, or in other words, as the shedding pattern changes
from "1" to "5", one heald frame is at the upper position whereas the remaining heald
frames are at the lower position.
[0036] When the shedding controller 56 performs the leveling operation, the loom main shaft
is rotated one turn in the reverse direction to establish the leveling state. At this
time, prior to the reverse rotation, the current solenoid selection pattern is changed
to a pattern obtained by inverting the actual current shedding pattern, whereby a
reverse-rotation frame pattern is output. In the figures, the inverted patterns are
denoted by numbers having bars over them. Fig. 3B shows inverted patterns that are
obtained by inverting the normal shedding patterns. In this case, the inverted patterns
are patterns that are obtained by reversing the upper and lower positions of the heald
frames in the corresponding normal shedding patterns.
[0037] Consequently, the main controller 14 outputs the leveling command S14 to the shedding
controller 56, and the shedding controller 56 inverts the signal to be output to the
selection solenoids 57, namely, the solenoid-selection shedding pattern. In addition,
the main controller 14 turns off the brake signal S8 and turns on the reverse rotation
signal S7 so that the loom main shaft rotates about one turn in the reverse direction.
While the loom main shaft rotates about one turn in the reverse direction, the actual
shedding pattern changes in accordance with the inverted pattern. Accordingly, all
of the heald frames H1, H2, ..., H5 move upward or downward. More specifically, when
the normal actual shedding pattern is pattern "4", the four heald frames H1, H2, H4,
and H5 are set to the lower position and the remaining one heald frame H3 is set to
the upper position. Therefore, while the loom main shaft rotates about one turn in
the reverse direction, the heald frames H1, H2, H4, and H5 at the lower position are
moved upward and the heald frame H3 at the upper position is moved downward in accordance
with the inverted pattern 4. As a result, all of the heald frames H1, H2, ..., H5
are moved to the leveling position, that is, to the vertical center, as the loom main
shaft approaches an angle (300°) where the upper and lower heald frames cross each
other. Such a function is not limited to the normal shedding pattern in which a single
repeat includes five cycles, and may also be obtained in a plain-weave shedding pattern
or shedding patterns for other weave structures.
[0038] Referring back to Fig. 2, when the loom main shaft is to be rotated in the reverse
direction from the current angle of 320°, the main controller 14 executes the leveling
function by outputting the leveling command S14 to the shedding controller 56 at an
angle prior to the cross timing by one-half turn (180°) in terms of the main-shaft
angle. Consequently, the shedding pattern obtained by inverting the current shedding
pattern is input to the selection solenoids 57. In addition, the main controller 14
turns off the brake signal S8 and turns on the reverse rotation signal S7 so that
the loom main shaft is rotated in the reverse direction at low speed. When the main-shaft
angle θ reaches 300° in response to the reverse rotation, the main controller 14 turns
off the leveling command S14 and stops the main shaft 24. Then, the main controller
14 informs the operator that the loom is in a standby state by turning on a tower
lamp (not shown) or presenting a display that indicates the current situation on the
display screen of the setting unit 12. As a result, all of the heald frames are moved
to the central position, whereby the warp shed is set to the central closed-shed state
(central leveling), as shown in Fig. 6.
[0039] Fig. 5 shows the state of the warp shed when the leveling function is inoperative
and the main shaft is stopped at 300°. When the loom is on standby with the warp shed
in the state shown in Fig. 5, the warp threads in the open-shed state become stretched
as time progresses, leading to weft bars (so-called filling bars). However, by setting
all of the heald frames in the central closed-shed state as shown in Fig. 6, all the
warp threads can extend through the healds with uniform tension, whereby such weft
bars can be prevented.
[0040] Figs. 5 and 6 schematically illustrate a reed 64 of the loom 1 as viewed from the
right side thereof. A plurality of warp threads 61 is let off from a warp beam (not
shown) and extends to a cloth fell 62 by passing through a back roller (not shown),
a warp breakage sensor (not shown), healds 63, and the reed 64. A woven cloth 60 extending
from the cloth fell 62 is guided forward by a temple 65 and is taken up by a cloth
roller (not shown) after passing through a guide roller (not shown) and a take-up
roller (not shown). A motion converting mechanism (not shown) connected to the main
shaft 24 converts the rotation of the main shaft 24 into a rocking motion for the
reed 64 so that the reed 64 is driven in a beating motion. The warp threads 61 are
transferred from the left to the right of the figure.
[0041] When the loom is on standby with the warp shed in a central closed-shed state, the
operator manually repairs the broken weft thread or manually rotates the main shaft
in the reverse direction to an activation position. However, if the operator makes
an error in this manual operation, the error can lead to defects in the quality of
the woven cloth, such as weft bars and cloth breakages, caused by shifting of the
cloth fell, which is one of the problems to be solved by the invention. Therefore,
for descriptive purposes, the proper operation that should be performed by the operator
will be described first before proceeding to the detailed description of the device
according to the invention.
[0042] In order to activate the loom on standby with the warp shed in a central closed-shed
state, the operator operates the inching button 42 to rotate the main shaft 24 forward
at low speed so that the warp shed is changed back to an open-shed state, based on
the normal shedding pattern, from the central closed-shed state, based on the aforementioned
inverted pattern. In this case, the angle at which the manual forward rotation is
stopped may be a timing at which the driving of the heald frames is to be started
on the basis of the normal shedding pattern. The main controller 14 may continuously
output the forward rotation signal S6 to rotate the main shaft 24 forward at low speed
until the main shaft 24 leaves the reversal prohibition period of the electronic dobby
device (specifically, until the main-shaft angle exceeds 210° at which the step signal
S15 output in synchronization with the step signal S16 is turned off).
[0043] When the leveling state is canceled in this manner, the operator operates the reverse
rotation button 43. The main controller 14 has already turned off the leveling command
S14 while continuously outputting the reverse rotation signal S7 in response to the
reverse operation signal S3 until the main shaft reaches an angle at which the broken
weft thread appears at the cloth fell (specifically, until the main shaft reaches
180°). On the other hand, in accordance with the leveling command S14 in the off state,
the shedding controller 56 outputs the pattern "3" as the shedding pattern, which
is the normal shedding drive mode, so as to drive the heald frames. Consequently,
the defectively inserted weft thread appears at the cloth fell and thus becomes removable.
The operator then removes the broken weft thread from the cloth fell and operates
the reverse rotation button 43 again so that the main shaft 24 is rotated in the reverse
direction at low speed to 300°, which corresponds to the predetermined activation
start position. Subsequently, when the operator presses the activation button 41,
the main controller 14 turns off the brake signal S8 and turns on the activation signal
S5, whereby the main shaft 24 is activated. Thus, the main shaft 24 is rotated forward
at high speed, and the loom enters a continuous operational mode and starts the weft
insertion process. In the above-described manner, a series of steps from a point at
which the weft-insertion error signal S10 as a stop signal is generated to a point
at which the loom is reactivated is implemented.
[0044] As described above, the loom in a standby state is reactivated after several operations
have been performed by the operator, such as thread repairing and manual operation.
However, this does not necessarily mean that the operator always performs the same
operations. For example, if the loom is set on standby with the warp shed in the central
closed-shed state due to weft stopping, it is necessary to operate the loom in a forward
inching rotation, cancel the leveling state, and then operate the loom in a reverse
rotation. However, if the operator is focused on removing a weft thread, there are
often cases where the operator intuitively operates the loom in a reverse rotation
without the forward inching rotation. Therefore, as shown with a dotted arrow in Fig.
2, it is assumed that the heald frames are rotated further in the reverse direction
from the position corresponding to the cross timing 300°, which is within a range
in which the driving is implemented on the basis of an inverted shedding pattern.
Based on this assumption, Fig. 7 illustrates the state of the warp shed when the main
shaft is rotated about one-half turn further in the reverse direction from the cross
timing 300° (angle of 180°; indicated by a circled letter "C" in Fig. 2). Once the
cloth fell 62 is shifted by a large amount in this manner, even if a shedding motion
is subsequently implemented on the basis of the normal shedding pattern, the cloth
fell 62 cannot be shifted back to its normal position, thus leading to weft bars.
Furthermore, since the heald frames are driven on the basis of an inverted pattern
instead of the normal shedding pattern, the defectively inserted weft thread cannot
be removed from the warp threads even if the angle is the same as that at the time
of occurrence of the weft insertion error. In other words, the operator cannot remove
the defectively inserted weft thread interwoven with the warp threads. There are also
cases where the operator operates the loom to further rotate the main shaft about
one-half turn in the reverse direction without realizing that the cause of inability
to remove the defective weft thread is in the previous operational error by the operator.
Fig. 8 illustrates the state of the warp shed based on the assumption that the main
shaft is rotated in the reverse direction (angle of 300°; and indicated by a circled
letter "D" in Fig. 2). While reaching such a state, the cloth fell 62 is shifted upstream
even further, and the reed 64 shifted forward in response to the reverse rotation
of the main shaft 24 interferes with the cloth fell 62, resulting in a cloth breakage.
In Figs. 5, 7 and 8, the woven cloth and the traveling path of the warp threads in
the central closed-shed state shown in Fig. 6 are indicated by dotted lines as a reference.
[0045] In contrast, according to the operational-error preventing device of the present
embodiment, even when the operator operates the reverse rotation button of the loom
in which the warp heald frames are driven on the basis of an inverted pattern, the
device executes a control routine that prevents the angle of the main shaft rotated
in the reverse direction from exceeding a predetermined reverse-rotation prohibition
angle, thereby providing an operational-error preventing function in the loom. In
this embodiment, the main controller 14 that receives a loom activation operation
signal and controls the entire operation of the loom functions as the operational-error
preventing device.
[0046] Fig. 4 is a flowchart of the process executed by the main controller 14 in response
to input of an operation-button signal when the loom is in a stopped state. When the
operator operates one of the plurality of manual operation buttons 41 to 44 (step
ST001), the process proceeds to step ST002. In step ST002, the main controller 14
determines the input conditions of the plurality of operation-button signals, and
the process proceeds from the current step to a subsequent step that corresponds to
the determined result of the operation signals. In this case, the main controller
14 receives the reverse operation signal S3 in an ON state, whereby the process proceeds
to step ST003.
[0047] In step ST003, the main controller 14 determines whether the leveling function is
set in an operative or inoperative mode. The process then proceeds from step ST003
to a subsequent step that corresponds to the determined result. The operative/inoperative
information of the leveling function is set in the setting unit 12 prior to the continuous
operation of the loom, such as during a looming operation. For example, when the leveling
function is set in the operative mode, if the loom is to be set on standby after an
occurrence of a cause of stoppage, the main controller 14 will output the leveling
command S14 so that the driving is implemented on the basis of an inverted shedding
pattern as shown in Figs. 2 and 5, thereby setting the warp shed to the central closed-shed
state. On the other hand, if the leveling function is set in the inoperative mode,
the main controller 14 will not output the leveling command S14, which means that
the driving is implemented on the basis of the normal shedding pattern.
[0048] The process related to reversal prohibition in the course of driving based on an
inverted pattern, which is a characteristic of the present invention, may be implemented
only when the leveling function is operative. If the leveling function is determined
to be inoperative in step ST003 (that is, if the determination result is "NO"), the
determination steps to be described below will be skipped so that the process proceeds
directly to step ST006 where the loom is controlled on the basis of a manual reverse
rotation mode as a control mode of the loom. On the other hand, if the leveling function
is determined to be operative in step ST003 (that is, if the determination result
is "YES"), the process proceeds to step ST004.
[0049] In step ST004, the main controller 14 determines whether or not the warp heald frames
are currently driven on the basis of an inverted shedding pattern (reverse-rotation
frame pattern) generated for central leveling. The main controller 14 is capable of
controlling the overall operation of the loom from the point of occurrence of the
cause of stoppage to the point of reactivation of the loom. In addition to controlling
the output of the leveling command S14, the main controller 14 also receives the main-shaft
angle signal θ and the signals S15a and S15b from the shedding device. More specifically,
the signals S15a and S15b are called a forward-rotation prohibition signal and a reverse-rotation
prohibition signal, respectively, and are output regardless of whether or not a leveling
function is provided as in the present invention. The signals S15a and S15b are output
in accordance with the rotating direction of the drive shaft 52. More specifically,
when the shedding controller 56 receives the activation signal S5 or the forward rotation
signal S6, the shedding controller 56 turns off the signal S15a serving as the forward-rotation
prohibition signal and outputs the signal S15b serving as the reverse-rotation prohibition
signal in synchronization with input of the step signal S17. On the other hand, when
the shedding controller 56 receives the reverse rotation signal S7, the shedding controller
56 turns off the signal S15b serving as the reverse-rotation prohibition signal and
outputs the signal S15a serving as the forward-rotation prohibition signal in synchronization
with input of the step signal S16.
[0050] Accordingly, in a state where the leveling command S14 is output from the main controller
14, the logical input state of the signal S15b is switched from off to on, whereby
the drive mode is determined to be based on the inverted pattern for leveling and
an internal process flag A is thus set to an ON state. In addition, the number of
times the signals are input (i.e. the number of times the main shaft passes this angle)
is subsequently counted so as to correspond to multiple reverse rotations. Supposedly,
after such a state where the drive shaft of the shedding device is rotated in the
reverse direction by multiple turns on the basis of the inverted pattern for leveling,
the drive shaft can be rotated forward to switch the signal S15a from on to off, so
that the count value for the number of outputs can be decremented by one. Eventually,
when the count value reaches zero, the internal process flag A is set to an OFF state.
This process can be implemented by the main controller 14 as a control routine.
[0051] In other words, if the logical state of the internal process flag A is on, it can
be determined that the drive mode is based on the inverted shedding pattern for leveling,
whereas if the logical state is off, it can be determined that the drive mode is based
on the normal shedding pattern. Thus, in step ST004, the main controller 14 determines
whether or not the drive mode is based on the inverted shedding pattern in accordance
with the set state of the internal process flag A. If the internal process flag A
is on, it is determined that the drive mode is based on the inverted pattern, and
the process proceeds to the next step (step ST005).
[0052] In step ST005, the main controller 14 determines whether or not the current main-shaft
angle θ has reached the reverse-rotation prohibition angle preliminarily set in the
setting unit 12. If the current main-shaft angle θ has not reached the reverse-rotation
prohibition angle, the process proceeds to step ST006 where the loom is driven on
the basis of a manual reverse-rotation mode as the control mode of the loom. On the
other hand, if the current main-shaft angle θ has reached the reverse-rotation prohibition
angle, the process proceeds to step ST007 where the control mode of the loom is set
to a stop mode.
[0053] In step ST006, the control mode of the loom is set to the manual reverse-rotation
mode, and the brake signal S8 is turned off so that the electromagnetic brake 30 is
released. In addition, the reverse rotation signal S7 is turned on so that the main
shaft 24 is rotated in the reverse direction at low speed. In contrast, in step ST007,
the brake signal S8 is turned on and the signals S5, S6, and S7 are turned off so
that the control mode of the loom is set to the stop mode.
[0054] Furthermore, in step ST002 described above, if signals excluding the reverse operation
signal S3, namely, the activation operation signal S1, the inching operation signal
S2, and the stop operation signal S4, are received by the main controller 14, the
process proceeds to step STOXX, which is not described in detail. In step STOXX, a
necessary determination process and switching process of the control mode are performed,
and the corresponding signal is output so that the loom is driven in accordance with
the corresponding operation button. On the other hand, when the inching operation
signal S2 and the reverse operation signal S3 are turned off, the process proceeds
to step ST007 along a flow indicated by a circled letter "A". In step ST007, the control
mode of the loom is set to the stop mode. Thus, the previously output forward rotation
signal S6 and reverse rotation signal S7 are turned off, and the brake signal S8 is
turned on so that the loom is stopped.
[0055] Furthermore, if the determination result regarding the leveling function in step
ST003 is NO, or if the determination result in step ST004 regarding whether or not
the drive mode is based on the inverted pattern is NO, the process proceeds directly
to step ST006 where the mode is switched to the manual reverse-rotation mode so that
the low-speed reverse rotation of the loom is immediately executed.
[0056] The series of steps shown in Fig. 4 is performed repetitively while the loom is in
the stopped state. While the reverse rotation button 43 is pressed, the process proceeds
through steps ST004 and ST005 so that the low-speed reverse rotation is continuously
executed. When the reverse rotation button 43 is continuously pressed and the main-shaft
angle reaches the manual reverse-rotation prohibition angle preliminarily set in the
setting unit 12 in step ST005 (i.e. the determination result is YES), the process
proceeds to step ST007 where the loom is automatically stopped at the reverse-rotation
prohibition angle. The preliminarily set reverse-rotation prohibition angle may be
set by means of the setting unit 12, or may be determined automatically when, for
example, the cross timing of the shedding device is set, or may be set to a value
preliminarily determined by the manufacturer. The present embodiment is based on the
assumption that the reverse-rotation prohibition angle is set by means of the setting
unit 12 and is preliminarily set to 280° included within the range of several tens
of degrees with respect to 300° which is the angle that corresponds to the cross timing
of the shedding device.
[0057] Referring to Fig. 2, when the loom is on standby with the warp shed in the central
closed-shed state and the main shaft stopped at 300°, the operator should cancel the
central closed-shed state by a forward inching operation. However, supposing that
the operator erroneously performs a manual reverse-rotating operation instead of the
forward inching operation for releasing the central closed-shed state, the determination
results for steps ST003 and ST004 will both be "YES" in the process shown in Fig.
4. For this reason, the process will proceed to step ST005. In this case, since the
main-shaft angle θ has not reached the reverse-rotation prohibition angle 280°, the
determination result will be "NO". Thus, the process proceeds to step ST006 where
the loom starts to rotate further in the reverse direction at low speed. On the other
hand, the process shown in Fig. 4 is repeated at short time cycles, and the determination
result in step ST005 becomes "YES" at the point when the main-shaft angle reaches
the preliminarily set reverse-rotation prohibition angle 280° as a result of the low-speed
reverse rotation. The process thus proceeds to step ST007 where the control mode of
the loom is switched to the stop mode, whereby the low-speed reverse rotation is immediately
terminated so that the loom is stopped. Consequently, even if the operator operates
the reverse rotation button 43 again, the reverse rotation is prohibited as long as
the leveling state is not canceled (in other words, until the internal process flag
A is turned off by rotating the main shaft forward to the main-shaft angle corresponding
to the shed position based on the normal shedding pattern). Accordingly, the operator
can realize that he/she had erroneously performed the reverse-rotating operation.
Thus, the operator can perform the forward inching operation, which is the proper
operation that should have been performed by the operator, so as to cancel the leveling
state and set the drive mode that is based on the normal shedding pattern. Subsequently,
the operator can implement the reverse-rotating operation so as to repair a defectively
inserted weft thread or a broken thread, and can then reactivate the loom. Accordingly,
preventing these operational errors can properly solve serious problems that can affect
the quality of the woven cloth, such as weft bars and cloth breakages.
[0058] The reverse-rotation prohibition angle used in the above-described manner may be
arbitrarily determined within a range in which the angle does not cause serious defects
in the woven cloth. For example, two set ranges for the reverse-rotation prohibition
angle are indicated by circled letters "a" and "b" below the horizontal axis (the
main-shaft angle) in Fig. 2. The set range indicated by "a" specifically shows a range
in which the shedding device is driven on the basis of an inverted shedding pattern.
The blank circles indicate that the main-shaft angle at which the shed amount of warp
threads is at the maximum is not included within the set range "a". More specifically,
the set range "a" is above and below 300° by 180° (that is, between 120° of the current
pick and 120° of the next pick but not including 120° at both ends). The set range
indicated by "b" is a preferred range that is above and below the cross timing of
the shedding device by several tens of degrees. More specifically, the preferred set
range is above and below 300° by 50° (that is, between 250° and 350°). Accordingly,
these set ranges at least prevent the occurrence of weft bars that are caused by large
displacement of the cloth-fell position.
[0059] More preferably, the reverse-rotation prohibition angle may be set to 300°, which
is the set angle for the cross timing. For example, the reverse-rotation prohibition
angle may be set to an angle, such as 320°, which is subsequent to the aforementioned
cross timing. Thus, when the loom is temporarily stopped due to an occurrence of a
cause of stoppage, the loom is set to the central closed-shed state by having the
main shaft rotated automatically in the reverse direction to the set angle of 300°.
In this case, with either of the abovementioned set angles, the main-shaft angle will
have already exceeded the reverse-rotation prohibition angle at the point when this
automatic reverse rotation is finished. Therefore, even if the reverse rotation button
is operated in this standby state, the determination result in step ST005 of the process
shown in Fig. 4 will always be "YES". Thus, the process proceeds to step ST007 where
the control mode of the loom is set to the stop mode, thereby prohibiting the reverse
rotation.
[0060] Although the above embodiment is directed to a case where the loom is stopped in
response to an occurrence of a cause of stoppage, the condition for setting the loom
on standby with the warp shed in the central closed-shed state is not limited to the
above. For example, the present invention is similarly applicable to a case where
an additional manual leveling button is provided, such that when the manual leveling
button is operated, the loom main shaft is automatically rotated in the reverse direction
and an inverted shedding pattern is output from the shedding controller, thereby achieving
the central closed-shed state.
[0061] The following modification of the above embodiment is permissible. Although the process
for determining whether or not the warp heald frames are driven on the basis of an
inverted pattern for leveling is implemented in the main controller 14 in the above
embodiment, the load of such a determination process may alternatively be shared between
the main controller 14 and the shedding controller 56, or between the main controller
14 and a separately provided determination circuit. In detail, the shedding controller
56 may generate a manual reverse-rotation prohibition signal in a period in which
the warp healds are driven on the basis of the inverted pattern for leveling. Thus,
while the manual reverse-rotation prohibition signal is being output, the main controller
14 does not output the reverse rotation signal S7 even if the main controller 14 receives
the reverse operation signal S3.
[0062] The above embodiment has been described with reference to a loom equipped with a
so-called electronic dobby shedding device as a shedding device. However, the shedding
device is not limited to such an electronic dobby shedding device and may include
other devices that drive the warp healds on the basis of a preliminarily set shedding
pattern in response to an electric selection signal. Specific examples of the shedding
device are an electronic jacquard device that drives the healds in a shedding motion
by means of an electromagnetic actuator provided in correspondence to the warp threads
and an electric shedding device that drives the heald frames by means of electric
motors provided for the respective heald frames. Furthermore, the present invention
is applicable to looms that are equipped with such devices. Moreover, examples of
looms to which the present invention can be applied are fluid jet looms, such as air
jet looms, and shuttleless looms, such as rapier looms.