Sewing machine

Abstract

 The present invention relates to a sewing machine that stably detects a seam allowance. A sewing machine (100) includes a main feed mechanism (20) and a lateral feed mechanism (30, 50) that feed a workpiece cloth (CU, CD) in crossing directions (X, Y), a cloth edge detecting device (40, 60) that detects a seam allowance of the workpiece cloth (CU, CD), and a control section (13) that controls the lateral feed mechanism (30, 50) such that the seam allowance has a target width. The cloth edge detecting device (40, 60) includes a light source (42, 62), and a detection section (45, 65) having a plurality of light receiving elements arranged along the workpiece cloth width direction (X) and detects the position of the cloth edge in the workpiece cloth width direction (X) of the workpiece cloth (CU, CD) from irradiation light blocked by the cloth edge of the workpiece cloth (CU, CD). The sewing machine (100) further includes an actuator (47, 67) that moves the cloth edge detecting device (40, 60) along the workpiece cloth width direction (X), and the control section (13) controls the actuator (47, 67) in accordance with a change in the target width of the seam allowance.

Description

[0001] The present invention relates to a sewing machine that detects a position of a cloth edge (lateral edge portion with respect to a cloth feeding direction) of a workpiece cloth and controls a seam allowance of the workpiece cloth to have a target width.

[0002] As shown in Fig. 16, to sew an upper cloth and a lower cloth together such that seam allowances of the upper and lower cloths match each other, a conventional sewing machine 100 includes a feed dog (not illustrated) that feeds the upper and lower cloths along a seam forming direction, upper and lower lateral feed mechanisms 130 (see Fig. 19) that feed the upper and lower cloths individually in a direction orthogonal to the cloth feeding direction on the upstream side of a sewing needle 101, and cloth edge detecting devices 110, 120 that detect cloth edge positions on the seam allowance sides of the upper and lower cloths (see, e.g., JP09-248390A).

[0003] Fig. 17 is an enlarged front view of the cloth edge detecting device 110 for the upper cloth CU of the sewing machine 100. The cloth edge detecting device 110 includes a light source 111 that irradiates slit-shaped irradiation light along the direction (left-right direction in Fig. 17) orthogonal to the direction of conveyance by the feed dog, and a line sensor 112 that receives the irradiation light. The upper cloth CU passes through the portion between the light source 111 and the line sensor 112, and a position at which the irradiation light is blocked by the upper cloth CU and the light intensity is lowered is identified from an output of the line sensor 112, and based on this, the position of the cloth edge of the upper cloth CU is detected. The cloth edge detecting device 120 for the lower cloth is also configured similarly. By adjusting the upper and lower cloths to appropriate positions by the lateral feed mechanisms based on the positions of the cloth edges of the upper and lower cloths detected by the cloth edge detecting devices 110, 120, sewing with seam allowances set to the target width is performed.

[0004] In the cloth edge detecting device 110, the cloth edge of the upper cloth CU is preferably positioned right in the middle of the detection range of the line sensor 112 as shown in Fig. 18A. In this state, the cloth edge of the upper cloth CU is evenly at a distance d0 from both end portions of the detection range of the line sensor 112 when the detection range has a length of 2d0, so that the cloth edge of the upper cloth CU is equally prevented from moving out from the detection region regardless of whether upper cloth CU is shifted to the left or to the right.

[0005] However, the cloth edge detecting device 110 is attached to the sewing machine frame in a fixed manner. Therefore, when the set value of the seam allowance of the upper cloth CU is small or large, as shown in Fig. 18B and Fig. 18C, sewing is performed with the upper cloth CU being shifted to the left or right. As a result, in either the leftward or rightward direction in which the distance from the current cloth edge of the upper cloth CU to the end portion of the detection region of the line sensor 112 is small, the line sensor can cope with a change in position of the cloth edge only in the range of the distance d1 (<d0), and when the change in position of the cloth edge of the upper cloth CU is more than d1, the cloth edge position is lost, and sewing cannot be continued and an event such as an error stop occurs.

[0006] Further, in the cloth edge detecting device 110, when the upper and lower cloths are straight, as described above, the center of the detection range of the line sensor 112 is preferably set as a target position. However, as shown in Fig. 19, when the shapes of the cloth edges include not only the straight sections S but also curved sections K curved to one side, a position offset from the center of the detection range is preferably set as a target position.

[0007] Fig. 19 is an explanatory diagram in a plan view, illustrating a positional relationship among a stitch point of the sewing needle 101, the lateral feed mechanism 130, and the cloth edge detecting device 110 of the sewing machine 110 with respect to the upper or lower cloth (only the upper cloth CU is illustrated) at the time of sewing. The reference sign F in the drawing indicates an advancing direction of the upper and lower cloths when they are being conveyed. As shown in Fig. 19, when one side of the lateral feed direction is defined as a forward direction, and the other side is defined as a reverse direction, Fig. 20A shows a detection output of the straight section S of the cloth edge of the upper or lower cloth by the cloth edge detecting device 110, and Fig. 20B shows a detection output of the curved section K of the upper or lower cloth by the cloth edge detecting device 110.

[0008] In the straight section S of the upper or lower cloth, deviations occur in both forward and reverse directions, and the occurrence of the deviations is not biased to either side, i.e. the deviations occur evenly in both directions. However, in the curved section K, a great deviation tends to occur toward the curving direction of the cloth edge of the cloth. Thus, when it is known before sewing that a great deviation will occur in either the forward or reverse direction in accordance with the shape of the cloth edge of the upper or lower cloth, it is preferable that the detection range is ensured to be wide in the direction in which such a deviation easily occurs. However, the conventional sewing machine 100 cannot meet this demand.

[0009] It is an object of the present invention to reduce a deviation of a cloth edge of a workpiece cloth from a detection range of a cloth edge detecting device that detects a seam allowance of the workpiece cloth.

[0010] According to an aspect of the present invention, a sewing machine includes a main feed mechanism configured to feed a workpiece cloth in a predetermined feeding direction along a horizontal plane, a lateral feed mechanism configured to move the workpiece cloth along a workpiece cloth width direction parallel to the horizontal plane and orthogonal to the feeding direction, a cloth edge detecting device configured to detect a seam allowance from a cloth edge to a stitch point in the workpiece cloth width direction of the workpiece cloth, and a control section configured to control the lateral feed mechanism based on the detection of the cloth edge detecting device such that the seam allowance of the workpiece cloth has a target width. The cloth edge detecting device includes a light source for irradiating the cloth edge of the workpiece cloth to be conveyed, and a detection section having a plurality of light receiving elements arranged along the workpiece cloth width direction and configured to detect a position in the workpiece cloth width direction of the cloth edge of the workpiece cloth based on a difference in light amount of a portion of irradiation light blocked by the cloth edge of the workpiece cloth. The sewing machine is characterized in that it further includes an actuator configured to move the cloth edge detecting device along the workpiece cloth width direction, and in that the control section controls the actuator to move the cloth edge detecting device in accordance with a change in target width of the seam allowance.

[0011] The control section may control the actuator such that a target position in a detection range of the cloth edge detecting device that corresponds to the target width of the seam allowance matches a predetermined specified in the detection range.

[0012] The specified position may be the center position in the detection range.

[0013] The sewing machine may further include a setting means capable of setting the specified position to be an optional position in the detection range.

[0014] When the target width of the seam allowance changes during sewing and when a distance from a target position in the detection range of the cloth edge detecting device that corresponds to a new target width of the seam allowance to the specified position is less than a predetermined distance, the control section may set the target position in the detection range of the cloth edge detecting device that corresponds to the new target width of the seam allowance as a new target position, and when the distance from the target position that corresponds to the new target width of the seam allowance to the specified position is equal to or more than the predetermined distance, the control section may control the actuator such that the target position in the detection range of the cloth edge detecting device that corresponds to the new target width of the seam allowance matches the specified position.

[0015] According to an aspect of the present invention, the sewing machine includes an actuator that moves the cloth edge detecting device along the workpiece cloth width direction, and controls the actuator to move the cloth edge detecting device in accordance with a change in target width of the seam allowance. Therefore, for example, when the target position in the detection range of the cloth edge detecting device that corresponds to the target width of the seam allowance deviates from a predetermined position in the detection range, the cloth edge detecting device can be moved so as to shift back the target position in the detection range of the cloth edge detecting device that corresponds to the target width of the seam allowance to the predetermined position in the detecting range. Accordingly, it is possible to avoid a situation where the cloth edge of the workpiece cloth deviates from the detection range of the cloth edge detecting device, or where the position detection range becomes insufficient on only one side in the workpiece cloth width direction with respect to the cloth edge of the workpiece cloth, and the sewing machine can cope with a change in position of the workpiece cloth in a wide range, and a state where the position of the cloth edge of the workpiece cloth cannot be detected and the sewing machine is stopped is prevented, so that a stable sewing operation can be performed.

[0016] For example, when the target position in the detection range of the cloth edge detecting device that corresponds to the target width of the seam allowance deviates from the specified position in the detection range in accordance with a change in target width of the seam allowance, the control section controls the actuator to shift back the target position in the detection range of the cloth edge detecting device that corresponds to the target width of the seam allowance to the specified position in the detection range. The specified position may be the center position of the detection range or an optional position in the detection range determined by the setting means.

[0017] For example, when the cloth edge of the workpiece cloth is straight, the specified position is preferably the center position of the detection range. For example, when the cloth edge of the workpiece cloth is curved in one direction, by considering this, a specified position offset to one side from the center position is preferably set in advance so that the detection range can be widely ensured in the direction in which the position of the cloth edge of the workpiece cloth easily deviates in accordance with the curving direction.

[0018] Accordingly, it is possible to more effectively avoid a situation where the cloth edge of the workpiece cloth deviates from the detection range or where the position detection range becomes insufficient on only one side in the workpiece cloth width direction with respect to the cloth edge of the workpiece cloth, and the sewing machine can better cope with a change in position of the workpiece cloth in a wide range.

[0019] For example, when a distance from a target position in the detection range of the cloth edge detecting device that corresponds to a new target width of the seam allowance to the specified position is equal to or more than a predetermined distance, the control section controls the actuator such that the target position in the detection range of the cloth edge detecting device that corresponds to the new target width of the seam allowance matches the specified position. In this case, the cloth edge of the workpiece cloth can be detected at the center position of the detection range, and the cloth edge can be prevented from deviating from the detection range and becoming undetectable, thereby enabling a stable detection.

[0020] Further, when the distance from the target position in the detection range of the cloth edge detecting device that corresponds to the new target width of the seam allowance to the specified position is less than the predetermined distance determined in advance, the control section sets the target position in the detection range of the cloth edge detecting device that corresponds to the new target width of the seam allowance as a new target position. Therefore, when the amount of change in target width of the seam allowance is smaller than the resolution of the actuator, without moving the cloth edge detecting device, the cloth edge of the workpiece cloth can be detected by setting a new target position in the detection range of the cloth edge detecting device.

[0021] The following description of embodiments of the present invention describes the present invention in greater detail along with the drawings. The drawings include:

Fig. 1: a perspective view showing a main portion of a top and bottom feed sewing machine as a first embodiment;

Fig. 2: an explanatory diagram schematically illustrating a configuration of the main portion of the top and bottom feed sewing machine viewed from the front side;

Fig. 3: a sectional view of an upper lateral feed mechanism;

Fig. 4: a perspective view of an upper cloth detecting device and a lower cloth detecting device;

Fig. 5: a front view of the upper cloth detecting device and the lower cloth detecting device viewed in a Y-axis forward direction;

Fig. 6: a block diagram illustrating a control system of the top and bottom feed sewing machine;

Fig. 7 (A) illustrating a relationship among a stitch point, a target width of seam allowances, and a target position in a detection range of a sensor, and (B) illustrating a case where the target width of the seam allowance changes and a new target position is set while the sensor position is kept;

Fig. 8(A) illustrating a relationship among a stitch point, a target width of seam allowances, and a target position in the detection range of the sensor, and (B) illustrating a case where the target width of the seam allowance changes and a new target position to which the sensor position is moved is set to the center position of the detection range;

Fig. 9: a diagram illustrating an example of sewing of an upper cloth and a lower cloth;

Fig. 10: a table showing a list of sewing conditions for performing the sewing shown in Fig. 9;

Fig. 11: a table showing setting of sewing data for performing first and second seam allowance adjusting controls in the sewing shown in Fig. 9;

Fig. 12: a diagram showing a relationship between a main shaft angle and a needle bar position (height);

Fig. 13: a diagram showing state changes at the respective stitch numbers when performing the sewing shown in Fig. 9, where (A) shows movement amounts in the X-axis direction of the detecting devices moved by upper and lower detection range adjusting mechanisms, (B) shows a change in target position in an image sensor detection range corresponding to a target width of the seam allowance, and (C) shows a change in target width of the seam allowance;

Fig. 14: a process flowchart of first and second seam allowance adjusting controls;

Fig. 15: a diagram showing state changes at the respective stitch numbers when considering movement times of the upper cloth and lower cloth detecting devices, where (A) showing movement amounts in the X-axis direction of the detecting devices moved by upper and lower detection range adjusting mechanisms, (B) showing a change in target position in an image sensor detection range corresponding to a target width of the seam allowance, and (C) showing a change in target width of the seam allowance.

Fig. 16: a front view of a conventional sewing machine;

Fig. 17: an enlarged front view of a cloth edge detecting device for an upper cloth of the conventional sewing machine;

Fig. 18A: a diagram illustrating a detection in a state where a reference position is set to the center position in the cloth edge detecting device;

Fig. 18B: a diagram illustrating a detection in a state where the reference position is biased in the cloth edge detecting device;

Fig. 18C: a diagram illustrating a detection in a state where the reference position is biased in the cloth edge detecting device;

Fig. 19: an plan view explanatory diagram illustrating a positional relationship among a stitch point of a sewing needle, a lateral feed mechanism, and a cloth edge detecting device of the sewing machine for upper or lower cloth, when sewing;

Fig. 20A: a diagram showing a detection output of the cloth edge detecting device in a straight section of the cloth edge of the upper or lower cloth; and

Fig. 20B: a diagram showing a detection output of the cloth edge detecting device in a curved section of the upper or lower cloth.

[0022] In the following description, the Y-axis direction is a horizontal direction, the X-axis direction is horizontal and orthogonal to the Y-axis direction, and the Z-axis direction is a vertical up-down direction.

[0023] In the X-axis direction and the Y-axis direction, "+" and "-" in each drawing indicate "forward" and "backward". For example, the feeding direction of the upper cloth CU (upper workpiece cloth) and the lower cloth CD (lower workpiece cloth) by the main feed mechanism 20 is parallel to the Y-axis direction, and the advancing direction of the feeding is the Y-axis forward direction, and the opposite direction is the Y-axis backward direction.

[0024] The lateral feed mechanisms 30 and 40 can move the upper cloth CU and the lower cloth CD to both sides in the X-axis direction, and in Fig. 1, the right side is the X-axis forward direction, and the left side is the X-axis backward direction. This X-axis direction corresponds to "workpiece cloth width direction."

[0025] The top and bottom feed sewing machine 100 performs sewing control to sew the upper cloth CU and the lower cloth CD overlapping each other and placed on the throat plate 14 so that the cloth edge on the X-axis forward side of the upper cloth CU and the cloth edge in the X-axis forward side of the lower cloth CD match each other without deviation and the seam allowances have a target width determined by sewing data while feeding the upper cloth CU and the lower cloth CD in the Y-axis forward direction.

[0026] As shown in Fig. 1 and Fig. 2, the top and bottom feed sewing machine 100 includes a needle bar up-down movement mechanism not illustrated that moves a needle bar holding a sewing needle up and down, a main feed mechanism 20 that feeds the upper cloth CU and the lower cloth CD in the Y-axis forward direction when sewing, an upper lateral feed mechanism 30 that is positioned in the Y-axis backward side with respect to a stitch point and moves the upper cloth CU forward and reverse in the X-axis direction, a lower lateral feed mechanism 50 that is positioned on the Y-axis backward side with respect to the stitch point and moves the lower cloth CD forward and reverse in the X-axis direction, a partition plate 11 that partitions the upper cloth CU and the lower cloth CD to prevent these from interfering with each other in lateral feeding operations of the lateral feed mechanisms, an upper cloth detecting device 40 as a cloth edge detecting device provided between the stitch point and the upper lateral feed mechanism 30, a lower cloth detecting device 60 as a cloth edge detecting device provided between the stitch point and the lower lateral feed mechanism 50, an upper detection range adjusting mechanism 46 that can move the upper cloth detecting device 40 along the X-axis direction, a lower detection range adjusting mechanism 66 that can move the lower cloth detecting device 60 along the X-axis direction, a shuttle mechanism not illustrated that captures an upper thread from the sewing needle below the throat plate 14 and entwines the upper thread with a lower thread, a control device 13 that controls the components around the upper cloth detecting device 40 and the lower cloth detecting device 60, and a sewing machine controller 19 that controls the entirety of the sewing machine 100.

[0027] The needle bar up-down movement mechanism and the shuttle mechanism are the same as those conventionally known, and detailed description thereof is omitted.

[0028] Main Feed Mechanism

[0029] As shown in Fig. 2, the main feed mechanism 20 includes a cloth presser 23 that continuously moves up and down above the throat plate 14 and presses the upper cloth CU and the lower cloth CD, a feed dog 21 that is provided below the throat plate 14 and makes elliptical movement along the Y-axis direction to project from and withdraw into an opening portion of the throat plate 14, a feed foot 22 that is provided above the throat plate 14 and makes elliptical movement along the Y-axis direction, and a movement transmission mechanism not illustrated that applies up-down movement or elliptical movement to the cloth presser 23, the feed dog 21, and the feed foot 22.

[0030] The feed dog 21 circles so that the upper section in the elliptical movement becomes the Y-axis forward direction, and the feed foot 22 circles so that the lower section in the elliptical movement becomes the Y-axis forward direction. Accordingly, the feed dog 21 and the feed foot 22 sandwich the upper cloth CU and the lower cloth CD on the throat plate 14 and intermittently feed these at predetermined feed pitches.

[0031] The cloth presser 23 moves up and down in synchronization with the circling of the feed dog 21 and the feed foot 22, and moves down at a timing at which the feed dog 21 withdraws downward and the feed foot 22 withdraws upward to press the upper cloth CU and the lower cloth CD, and moves up at a timing at which the feed dog 21 and the feed foot 22 mesh with each other and feed the cloths.

[0032] The feed dog 21, the feed foot 22, and the cloth presser 23 obtain power from a sewing machine motor 15 (see Fig. 6) that serves as a drive source of the needle bar up-down movement mechanism and the shuttle mechanism. Specifically, the feed dog 21 makes elliptical movement by being subjected to application of up-down and back-and-forth reciprocating movements by a transmission mechanism that converts the rotation of the sewing machine motor 15 into the up-down reciprocating movement and a transmission mechanism that converts the rotation into back-and-forth reciprocating movement synchronously.

[0033] The feed foot 22 operates in the same manner, and the feed foot 22 is reciprocated back and forth by converting the rotation of the sewing machine motor 15 into the back-and-forth movement and applying the movement to a rod supporting the feed foot 22, and is moved up and down by converting the rotation of the sewing machine motor 15 into the up-down movement and applying the movement to the rod supporting the feed foot 22. Accordingly, the feed foot 22 is caused to make elliptical movement.

[0034] The rotation of the sewing machine motor is converted into up-down movement and transmitted to the rod supporting the cloth presser 23, whereby realizing the up-down movement.

[0035] The sewing machine motor 15 applies power to the needle up-down movement mechanism and the main feed mechanism 20 through a main shaft not illustrated, and according to one rotation of the main shaft, the needle up-down movement mechanism performs stitching of one stitch, and the main feed mechanism 20 performs a feeding operation for one pitch. At this time, when the main shaft angle when the needle bar is at the upper dead point is 0°, the sewing needle does not stick in the upper cloth CU and the lower cloth CD in the main shaft angle range of 270° to 90°. The cloth feeding operation by the feed dog 21 and the feed foot 22 is performed in the main shaft angle range of 270° to 90°.

[0036] Partition Plate

[0037] The partition plate 11 is a long flat plate along the X-axis direction, and an end portion on the X-axis forward side thereof is supported in a cantilevered state by a sewing machine frame.

[0038] The lower side of the partition plate 11 is slightly spaced upward from the upper surface of the bed portion to form a clearance, and through this clearance, the lower cloth CD is conveyed. On the upper side of the partition plate 11, the upper cloth CU is conveyed, and accordingly, the upper cloth CU and the lower cloth CD are separated and lateral feeding is carried out individually.

[0039] Upper Lateral Feed Mechanism and Lower Lateral Feed Mechanism

[0040] Fig. 3 is a sectional view of the upper lateral feed mechanism 30.

[0041] The upper lateral feed mechanism 30 includes a rotating body 31 that conveys the upper cloth CU to be conveyed to the main feed mechanism 20 in the Y-axis forward direction in conjunction with the main feed mechanism 20, a plurality of pinions 32 that are disposed at even intervals along the outer periphery of the rotating body 31 and come into contact with the upper surface of the upper cloth CU to move the upper cloth CU in the X-axis direction (lateral feed direction), a conveyance drive mechanism 33 that applies a torque for conveying the upper cloth CU in the Y-axis forward direction to the rotating body 31, a lateral feed drive mechanism 34 that applies rotating power for lateral feeding to the plurality of pinions 32, and a frame body 35 that supports these components.

[0042] The rotating body 31 is a structural body hollow inside formed of two cups opposed to each other and integrated, and is supported on one end portion of a hollow pivot 332 of the conveyance drive mechanism 33 that will be described later so that the rotation center thereof is concentric with the hollow shaft. These are supported on the frame body 35 rotatably around the X-axis.

[0043] The rotating body 31 supports rotatably eight pinions 32 at 45° intervals radially inside the rotating body as viewed from the X-axis direction. Each pinion 32 is supported so that a part of the outer periphery is exposed from a slit-like opening portion formed along the X-axis direction in the outer periphery of the rotating body 31, and the rotating body 31 is contactable with the upper cloth CU via these pinions 32.

[0044] Each pinion 32 is axially supported by a rotary shaft along the tangential direction of a circle concentric with the rotating body 31, and teeth formed on the outer peripheries of all pinions 32 mesh with a worm gear 343 of the lateral feed drive mechanism 34 that is disposed at the center of the rotating body 31 and rotates around the X-axis. Specifically, inside the rotating body 31, when the worm gear 343 concentric with the rotating body 31 rotates relative to the rotating body 31, the pinions 32 rotate.

[0045] The rotary drive mechanism 33 includes a feeding motor 331 being a rotary drive source of the rotating body 31, a hollow pivot 332 that supports the rotating body 31 by one end portion, a main drive sprocket 333 fixed to the output shaft of the feeding motor 331, a driven sprocket 334 fixed to the hollow pivot 332, and a timing belt 335 laid across the sprockets 333, 334.

[0046] The hollow pivot 332 is supported along the X-axis direction rotatably by the frame body 35. On one end portion thereof, the rotating body 31 is fixed and supported. The hollow pivot 332 is hollow across the entire length, and inside the hollow pivot, a transmission shaft 342 of the lateral feed drive mechanism 34 is inserted concentrically.

[0047] The feeding motor 331 is a stepping motor, and the output shaft thereof is held on the frame body 35 in a state where it is along the X-axis direction. A torque is applied from the main drive sprocket 333 provided on the output shaft of the feeding motor 331 to the hollow pivot 332 via the timing belt 335 and the driven sprocket 334 to rotate the rotating body 31 around the X-axis.

[0048] The main feed mechanism 20 inevitably performs periodic intermittent feeding due to its structure for feeding the upper cloth CU by using the feed dog 21 and the feed foot 22, however, the feeding motor 331 is a stepping motor whose operation timing and rotation speed are arbitrarily controllable, so that conveyance of the upper cloth CU can be performed in synchronization with the main feed mechanism 20.

[0049] The lateral feed drive mechanism 34 includes a lateral feed motor 341 being a rotary drive source of the pinions 32, the transmission shaft 342 that penetrates through the hollow shaft 332 and is along the X-axis direction, and the worm gear 343 fixed to one end portion of the transmission shaft 342 inside the rotating body 31.

[0050] The worm gear 343 is positioned at the center of the pinions 32 inside the rotating body 31, and mesh with all pinions 32.

[0051] The lateral feed motor 341 is a stepping motor, and its output shaft is directly connected to the transmission shaft 342. In addition, the lateral feed motor is a stepping motor, so that its operation timing and rotation speed are arbitrarily controllable.

[0052] The frame body 35 is fixed to the sewing machine frame so that the rotating body 31 comes into contact with the upper cloth CU to be conveyed, however, for sufficient contact of the rotating body 31 with the upper cloth CU to be conveyed, the frame body 35 may be structured so that the rotating body 31 is brought into contact with the upper cloth CU to be conveyed by its own weight by making the frame body 35 movable up and down with respect to the sewing machine frame or making the frame body 35 swingable around the Y-axis, or the rotating body 31 may be brought into contact with the upper cloth CU to be conveyed by using an actuator.

[0053] With the above-described configuration, the upper lateral feed mechanism 30 can be structured so that the feeding motor 331 is driven to rotate the rotating body 31, and the upper cloth CU that comes into contact with the rotating body 31 via the pinions 32 can be fed in the Y-axis forward direction.

[0054] By driving the lateral feed motor 341, the worm gear 343 rotates and the pinions 32 rotate, and accordingly, without obstructing conveyance in the Y-axis direction of the upper cloth CU, the upper cloth can also be moved in the X-axis direction, and accordingly, the seam allowance of the upper cloth CU can be adjusted.

[0055] To rotatively drive the pinions 32 during rotation of the rotating body 31, the transmission shaft 342 needs to be rotated relative to the hollow pivot 332. Therefore, when lateral-feeding the upper cloth CU, to obtain necessary rotations of the pinions 32, the rotation speed of the lateral feed motor 341 is controlled to have a predetermined speed difference from the rotation speed of the feeding motor 331.

[0056] The lower lateral feed mechanism 50 includes components that are substantially the same as those of the upper lateral feed mechanism 30, so that description of these components is not given.

[0057] The lower lateral feed mechanism 50 is installed inside the bed portion so that the upper portion of the rotating body thereof projects slightly higher than the upper surface of the throat plate 14, and comes into contact with the lower cloth CD to be conveyed on the lower side of the partition plate 11 from below to feed the lower cloth in the Y-axis direction and move the lower cloth in the X-axis direction.

[0058] The feeding motor 531 and the lateral feed motor 541 (see Fig. 6) of the lower lateral feed mechanism 50 are controlled by the control device 13 together with the feeding motor 331 and the lateral feed motor 341 of the upper lateral feed mechanism 30.

[0059] Upper Cloth and Lower Cloth Detecting Devices

[0060] Fig. 4 is a perspective view of the upper cloth detecting device 40 and the lower cloth detecting device 60. As illustrated, the upper cloth detecting device 40 and the lower cloth detecting device 60 are supported slidably along the X-axis direction by the upper portion and the lower portion of a base portion 18 that supports a reflector 12 formed of a thin metal plate whose both surfaces are lustrous.

[0061] The base portion 18 is a long structural body along the X-axis direction, and the end portion in the X-axis forward direction thereof is supported in a cantilevered state by the sewing machine frame, and from the end portion in the X-axis backward direction, the reflector 12 is extended.

[0062] From the upper surface and the lower surface of the end portion in the X-axis backward direction of the base portion 18, the upper cloth detecting device 40 and the lower cloth detecting device 60 are extended toward the X-axis backward direction, and extended end portions of these detecting devices 40, 60 form a shape opened in a U-shape toward the X-axis backward direction. Inside the U-shaped opening portion formed by the upper cloth detecting device 40 and the lower cloth detecting device 60, the reflector 12 is sandwiched so that its surface-side and back-side reflecting surfaces are along the X-Y plane.

[0063] Specifically, the lower surface of the extended end portion of the upper cloth detecting device 40 faces the upper reflecting surface of the reflector 12, and the upper surface of the extended end portion of the lower cloth detecting device 60 faces the lower reflecting surface of the reflector 12.

[0064] At the time of sewing, in a state where the cloth edge on the X-axis forward side of the lower cloth CD is inserted to the side below the reflector 12 in the opening portion, the presence of this cloth edge and its position in the X-axis direction are detected, and in a state where the cloth edge on the X-axis forward side of the upper cloth CU is inserted to the side above the reflector 12 in the opening portion, the presence of this cloth edge and its position in the X-axis direction are detected.

[0065] The lower cloth detecting device 60 includes a housing 61 that supports the components inside, a light source unit 62 as a light source that irradiates light for detecting the position in the X-axis direction of the cloth edge of the lower cloth CD, a CMOS image sensor 65 as a detection section that receives reflected light from the reflector 12 based on irradiation light from the light source unit 62, an LED 64 as a light source that irradiates light for detecting the presence of the cloth edge of the lower cloth CD, and a light receiving LED 63 as a detecting element that receives reflected light from the reflector 12 based on irradiation light from the LED 64.

[0066] The light source unit 62 has a function of emitting slit-shaped parallel light along the X-axis direction, and is constituted by, for example, a point light source such as an LED, a lens that converts diffused light from the point light source into parallel light, and a diaphragm for forming the parallel light into a slit shape, etc. This light source unit 62 can prevent the position detection accuracy from deteriorating due to, for example, a difference in height of the irradiation surface of the lower cloth CD by irradiating parallel light.

[0067] The image sensor 65 is formed by arranging minute light receiving elements with widths in the X-axis direction of 10 to 20 micrometers in the X-axis direction, and detect light intensities at positions in the longitudinal direction of reflected light at a position at which slit-shaped irradiation light of the light source unit 62 is reflected by the reflector 12.

[0068] In the above-described configuration, the light source unit 62 irradiates slit-shaped parallel light along the X-axis direction onto the reflector 12, and at this time, the cloth edge of the lower cloth CD covers a part of the lower reflecting surface of the reflector 12. Therefore, the reflected light of the slit-shaped parallel light lowers in light intensity at a part in the longitudinal direction according to the position of the cloth edge of the lower cloth CD. On the other hand, the image sensor 65 includes light receiving elements arranged along the X-axis direction, so that based on their detection outputs, a position at which the light intensity of the reflected light of the slit-shaped parallel light lowered can be identified. Then, by specifying the position at which the light intensity lowered, the position in the X-axis direction of the cloth edge of the lower cloth CD, that is, a seam allowance at the time of detection is obtained.

[0069] The LED 64 and the light receiving LED 63 are disposed closer to the X-axis backward side than the light source unit 62 and the image sensor 65, and are used to detect a deviation of the lower cloth CD from the opening portion at the time of sewing and detect passage of the terminal end of the lower cloth CD through the portion between the reflector 12 and the lower cloth detecting device 60 at the end of conveyance.

[0070] The LED 64 is a point light source and irradiates diffused light, however, the irradiation light may not be parallel light as long as the presence of the lower cloth CD can be detected at the irradiation position.

[0071] The light receiving LED 63 is provided on the position of reflection of the irradiation light of the LED 64 by the reflector 12.

[0072] The upper cloth detecting device 40 includes a housing 41 that supports the components inside, a light source unit 42 as a light source that irradiates light for detecting the position in the X-axis direction of the cloth edge of the upper cloth CU, an image sensor 45 as a detection section that receives reflected light from the reflector 12 based on the irradiation light from the light source unit 42, an LED 44 as a light source that irradiates light for detecting the presence of the cloth edge of the upper cloth CU, and a light receiving LED 43 as a detecting element that receives reflected light from the reflector 12 based on the irradiation light from the LED 44. These components are the same as those of the lower cloth detecting device 60, so that description of these is omitted.

[0073] Detection Range Adjusting Mechanisms

[0074] Fig. 5 is a front view of the upper cloth detecting device 40 and the lower cloth detecting device 60 along the line of sight in the Y-axis forward direction.

[0075] As shown in Fig. 5, alongside the upper cloth detecting device 40 and the lower cloth detecting device 60 described above, an upper detection range adjusting mechanism 46 and a lower detection range adjusting mechanism 66 that make the upper cloth detecting device 40 or the lower cloth detecting device 60 movable along the X-axis direction with respect to the base portion 18 are provided.

[0076] The upper detection range adjusting mechanism 46 includes a position adjustment motor 47 as an actuator that moves the upper cloth detecting device 40 along the X-axis direction, rack teeth 48 provided on the end portion upper surface on the X-axis forward side of the casing 41 of the upper cloth detecting device 40, and a pinion gear 49 that is provided on the output shaft of the position adjustment motor 47 and meshes with the rack teeth 48.

[0077] The position adjustment motor 47 is a stepping motor, and is driven according to control by the control device 13, and according to driving of the position adjustment motor 47, the upper cloth detecting device 40 is arbitrarily moved along the X-axis direction.

[0078] The lower detection range adjusting mechanism 66 includes a position adjustment motor 67, rack teeth 68, and a pinion gear 69 that are configured in substantially the same manner as in the upper detection range adjusting mechanism 46, and the position adjustment motor 67 of the lower detection range adjusting mechanism 66 is also controlled by the control device 13 to arbitrarily move the lower cloth detecting device 60 along the X-axis direction.

[0079] Control Device

[0080] Fig. 6 is a block diagram showing a control system of the top and bottom feed sewing machine 100.

[0081] The top and bottom feed sewing machine 100 includes the sewing machine controller 19 that controls the entire sewing machine at the time of sewing, and the control device 13 that controls the components around the upper cloth detecting device 40 and the lower cloth detecting device 60.

[0082] To the sewing machine controller 19, a sewing machine motor 15 for moving the sewing needle up and down is connected via a driving circuit 15a. A sewing machine main shaft not illustrated that is driven to rotate by the sewing machine motor 15 is provided with an encoder 16 that detects the shaft angle thereof, and outputs a detected shaft angle to the sewing machine controller 19 via an interface 16a. This encoder 16 outputs a resolution of 0.25 [deg] for the main shaft angle, that is, outputs 1440 pulses per one rotation of the main shaft.

[0083] Further, the top and bottom feed sewing machine 100 includes an operation panel 17 for inputting various settings and displaying various information, and the operation panel 17 is also connected to the sewing machine controller 19 via the interface 17a.

[0084] On the other hand, to the control device 13, feeding motors 331 and 531 of the lateral feed devices 30, 50, lateral feed motors 341 and 541, and position adjustment motors 47, 67 for the upper cloth CU and the lower cloth CD are connected via driving circuits 331a, 531a,341a,541a,47a,67a.

[0085] To the control device 13, the lower cloth detecting device 60 and the upper cloth detecting device 40 are connected via interfaces 60a and 40a, respectively. The image sensors 65 and 45 output analog detection signals, so that the control device 13 includes A/D converters 135 and 136 for the image sensors 65 and 45, so that digitized detection data can be obtained.

[0086] The control device 13 includes a CPU 131 that performs various arithmetic processes, a ROM 132 in which a program on operation controls of the above-described components has been stored, a RAM 133 that stores various data on the processes of the CPU 131 in a work area, an EEPROM 134 as a storage section that stores various setting data and sewing data, etc., and the above-described A/D converters 135 and 136.

[0087] Overview of Sewing Control

[0088] The top and bottom feed sewing machine 100 performs sewing according to sewing data (described later) in which values of seam allowances for stitch numbers are set. First, the overview of a basic sewing operation to be performed by the sewing machine controller 19 and the control device 13 is described.

[0089] When sewing is started according to driving of the sewing machine motor 15 in a state where the cloth edge of the upper cloth CU is inserted between the upper cloth detecting device 40 and the reflector 12 and the cloth edge of the lower cloth CD is inserted between the lower cloth detecting device 60 and the reflector 12, the control device 13 monitors a main shaft angle based on pulse signals input from the encoder 16 through the sewing machine controller 19, and drives the feeding motors 331 and 531 and the lateral feed motors 341 and 541 of the upper lateral feed mechanism 30 and the lower lateral feed mechanism 50 to perform feeding of the upper cloth CU by the upper lateral feed mechanism 30 and feeding of the lower cloth CD by the lower lateral feed mechanism 50 in synchronization with the intermittent feeding operation in the main feed mechanism 20.

[0090] Specifically, in the main feed mechanism 20, the feed dog 21 and the feed foot 22 circle in an elliptical orbit, and in a part of the orbit, they come into contact with the upper cloth CU and the lower cloth CD and convey these, so that the angle range of the main shaft angle for conveyance is always fixed, and the feeding pitch is also determined by setting. Therefore, from the output of the encoder 16, reach to the angle range of the main shaft angle in which conveyance is performed is monitored, and driving of the feeding motors 331 and 531 and the lateral feed motors 341 and 541 is controlled so that feeding of feeding pitches in this angle range is performed. When lateral feeding of the upper cloth CU or the lower cloth CD is not carried out, the feeding motors 331 and 531 and the lateral feed motors 341 and 541 are driven at speeds equal to each other so as not to cause a relative speed difference, and controlled to prevent the pinions 32 from rotating.

[0091] The control device 13 reads a target width of the seam allowances for the next stitch number from the sewing data and monitors the main shaft angle based on the output of the encoder 16, and when the predetermined main shaft angle (main shaft angle at which the sewing needle does not stick in the upper cloth CU and the lower cloth CD) is reached, reads the sensor outputs of the image sensors 45 and 65 of the upper cloth detecting device 40 and the lower cloth detecting device 60 and calculates current seam allowances of the upper cloth CU and the lower cloth CD.

[0092] Then, the target width of the seam allowances and the detected seam allowances are compared, and for example, when the seam allowance detected on the upper cloth CU is small, the lateral feed motor 341 of the upper lateral feed mechanism 30 is rotated at a speed higher than that of the feeding motor 331, and the transmission shaft 342 is rotated relative to the hollow pivot 332 to apply the rotation to the pinions 32 of the rotating body 31, whereby moving the upper cloth CU in the X-axis forward direction. Accordingly, the seam allowance of the upper cloth CU is adjusted to increase. When the seam allowance detected on the upper cloth CU is large, the lateral feed motor 341 of the upper lateral feed mechanism 30 is rotated at a speed lower than that of the feeding motor 331 to apply the rotation to the pinions 32, whereby moving the upper cloth CU in a direction to reduce the seam allowance of the upper cloth CU.

[0093] The lower lateral feed mechanism 50 for the lower cloth CD is controlled in the same manner. Then, when stitching of the number of stitches determined by the sewing data is completed, the sewing machine motor stops and sewing is ended.

[0094] First Seam Allowance Adjusting Control

[0095] As described above, the top and bottom feed sewing machine 100 is set so that the target width of the seam allowances changes among the plurality of stitch numbers of a series of sewing, and at the time of sewing, and controls the upper and lower lateral feed mechanisms 30, 50 so that the seam allowances for each stitch have each target width. Thus, for each stitch, the upper cloth detecting device 40 and the lower cloth detecting device 60 detect seam allowances of the upper cloth CU and the lower cloth CD (hereinafter, these may be collectively referred to as "cloth" for convenience) so that the seam allowances for each stitch follow the setting.

[0096] Then, as one of the features of the top and bottom feed sewing machine 100, either one of the first seam allowance adjusting control and the second seam allowance adjusting mechanism is selectively performed in the detection of the seam allowances for each stitch.

[0097] First, the first seam allowance adjusting control to be performed by the control device 13 is described.

[0098] For seam allowance detection, the image sensors 45 and 65 are used, and each of these image sensors 45 and 65 receives slit-shaped reflected light in a detection range constituted by a plurality of minute light receiving elements arranged along the X-axis direction, and identifies a tip end position of the cloth edge of the workpiece cloth from a position which is covered by the cloth edge of the workpiece cloth and at which a difference in light intensity occurs, that is, a seam allowance.

[0099] As described above, when a target width of the seam allowances is determined in advance, the control device 13 obtains target positions in the detection ranges of the image sensors 45 and 65 that corresponds to the target width of the seam allowances, compares the target positions and actually detected cloth edge positions of the workpiece cloths, and judges in which direction the workpiece cloths deviate.

[0100] For example, as shown in (A) of Fig. 7, the control device 13 determines a position separated by the target width W0 of the seam allowances from the stitch point N toward the X-axis forward direction as a target position P0.

[0101] The detection range adjusting mechanisms 46, 66 perform positioning control to match the first target position P0 after sewing start with the center position C that is at the distance d0 (2d0 is the width in the X-axis direction of the detection range) from both end portions of the detection range of the image sensor 45, 65. This is for suppressing deviations of the workpiece cloths to the outsides of the detection ranges even when the cloth edges of the workpiece cloths suddenly fluctuate in the X-axis forward or backward direction.

[0102] Then, at the time of sewing, this target position P0 and the detected positions of the cloth edges of the workpiece cloths are compared, and based on which direction the positions of the workpiece cloths deviate in, the upper and lower lateral feed mechanisms 30, 50 perform control to move the workpiece cloths in the X-axis forward or backward direction.

[0103] Further, when the target width W0 of the seam allowances changes to the new target width W1 during sewing and the position at the distance W1 from the stitch point N is not separated by a predetermined distance (for example, 1 [mm]) or more from the center position C of each detection range described above, without operating the detection range adjusting mechanisms 46, 66, the new target position P1 is set. Specifically, the previous target position P0 matches the center position C of each detection range, however, the new target position P1 is set to a position deviating from the center position C.

[0104] For example, as shown in (B) of Fig. 7, when the new target width W1 of the seam allowances is W1 = W0-d1 and d < 1 [mm], the new target position P1 that is at the distance W1 from the stitch point N is set while the upper cloth detecting device 40 and the lower cloth detecting device 60 keep their current positions.

[0105] Then, this target position P1 is compared with detected positions of the cloth edges of the workpiece cloths, and the workpiece cloth lateral feeding operation control is performed by the upper and lower lateral feed mechanisms 30, 50.

[0106] Thus, in the first seam allowance adjusting control, when the distance from the center position C of the detection range of the image sensors 45, 65 to the position in the detection range that corresponds to the new target width of the seam allowances is less than the predetermined distance, without operating the detection range adjusting mechanism 46, 66 of the detecting devices 40, 60, the new target position is set.

[0107] In this case, without mechanical operations like the operations for moving the detecting devices 40, 60, software processing such as a change in setting of the target position for judgment of the positions of the cloth edges of the workpiece cloths is just performed, so that the processing can be performed at a speed corresponding to the processing ability of the control device 13.

[0108] Second Seam Allowance Adjusting Control

[0109] Next, the second seam allowance adjusting control to be performed by the control device 13 is described.

[0110] In the second seam allowance adjusting control, when the target width of the seam allowances changes to the new target width W1 during sewing and the position at the distance W1 from the stitch point N is at a predetermined distance (for example, 1 [mm]) or more from the center position C of the above-described detection range, each detection range adjusting mechanism 46, 66 is operated to match the new target position P1 and the center position C of the detection range with each other.

[0111] (A) of Fig. 8 shows the same state as shown in (A) of Fig. 7, and (B) of Fig. 8 shows a case where the target width W0 of the seam allowances changes to the new target width W1. As shown in Fig. 8, when the new target width W1 of the seam allowances is W1 = W0 - d1 and d1 ≥ 1 [mm], the upper cloth detecting device 40 and the lower cloth detecting device 60 are moved by d1 in the X-axis backward direction by the detection range adjusting mechanisms 46, 66. Accordingly, the new target position P1 matches the center position C of each detection range.

[0112] Then, this center position C is compared with detected positions of the cloth edges of the workpiece cloths, and the upper and lower lateral feed mechanisms 30, 50 perform workpiece cloth movement control.

[0113] Thus, in the second seam allowance adjusting control, the new target position P1 matches the center position C of the detection range, so that even after the target width of the seam allowances is changed, in each detecting device 40, 60, the cloth edge of the workpiece cloth can be detected by using the center of the detection range as a reference, and even in the case where the position of the cloth edge of the workpiece cloth fluctuates unexpectedly, the cloth edge of the workpiece cloth can be prevented from deviating from the detection range and causing a state where sewing is impossible.

[0114] A reference amount compared with d1 to determine which of the first seam allowance adjusting control and the second seam allowance adjusting control is to be performed is a minimum unit movement amount based on the resolution of the position adjustment motor 47, 67 of the detection range adjusting mechanism 46, 66. Specifically, in this example, the minimum distances of movements of the detecting devices 40, 60 by the position adjustment motors 47, 67 being stepping motors according to their resolutions are 1 [mm].

[0115] When the target width of the seam allowances is changed, the second seam allowance adjusting control is preferably always performed to match the position in each detection range that corresponds to the new target width of the seam allowances with the center position C of the detection range, however, fine position adjustment is limited by the resolution of the position adjustment motor 47, 67, so that when the necessary movement amount of the detecting device 40, 60 is small, the first seam allowance adjusting control is performed so that the seam allowances have the target width.

[0116] In the top and bottom feed sewing machine 100, normally, the seam allowances of the upper cloth CU and the lower cloth CD are set to the same value, so that the case where the first seam allowance adjusting control and the second seam allowance adjusting control are the same between the upper cloth detecting device 40 and the lower cloth detecting device 60 and between the upper lateral feed mechanism 30 and the lower lateral feed mechanism 50 is described, however, the seam allowances of the upper cloth CU and the lower cloth CD may be set to values different from each other. In this case, based on the respective target widths of the seam allowances of the upper cloth CU and the lower cloth CD, the first seam allowance adjusting control and the second seam allowance adjusting control are performed for the upper cloth and the lower cloth individually.

[0117] In Fig. 7 and Fig. 8, illustration of the detection range adjusting mechanism 66 is omitted.

[0118] Detailed setting for performing first and second seam allowance adjusting controls

[0119] Fig. 9 is an example of sewing of the upper cloth CU and the lower cloth CD. In the top and bottom feed sewing machine 100, the upper cloth CU and the lower cloth CD (hereinafter, referred to as workpiece cloths) are conveyed toward the upper side of the drawing, and a seam is formed from the upper end to the lower end.

[0120] In the process of stitching of 300 stitches on the workpiece cloths, an initial target width of the seam allowances is set to 10 [mm], and sewing is performed to change the seam allowances to 11 [mm]. In detail, until the 94th stitch after the sewing start, stitching is performed by setting the target width of the seam allowances to 10 [mm], and from the 95th stitch to the 99th stitch, the seam allowances are increased by 0.1 [mm] per stitch, from the 100th stitch to 194th stitch, stitching is performed by keeping the seam allowances at 10.5 [mm], from 195th stitch to 199th stitch, the seam allowances are increased by 0.1 [mm] per stitch, and from the 200th stitch to the 300th stitch, stitching is performed by keeping the seam allowances at 11 [mm].

[0121] Fig. 10 is a table showing a list of sewing conditions for performing the sewing shown in Fig. 9. As illustrated, the total number of stitches in the sewing is 300 stitches, the maximum speed of the sewing machine motor 15 during sewing is 3000 [sti/min] (rpm), the resolution of the encoder 16 is 0.25 [deg], the settings of the seam allowances for the respective stitches are as described above, the sensing periods of the image sensors 45 and 65 are 10 [ms], the widths in the X-axis direction of the detection ranges are 100 [mm], the resolutions are 0.1 [mm], and resolutions of sensor movements by the position adjustment motors 47, 67 are 1.0 [mm]. These settings are common to the upper cloth CU and the lower cloth CD.

[0122] Fig. 11 is a table showing setting contents of sewing data for performing the first and second seam allowance adjusting controls in the sewing shown in Fig. 9. As illustrated, in the sewing data, data numbers indicating the order of the first and second seam allowance adjusting controls, stitch numbers (PINNUM) at which the first and second seam allowance adjusting controls are performed, main shaft angles (FREQ) at which the first and second seam allowance adjusting controls are performed, change points (POINT) that are cumulated values of encoder output signals at which the first and second seam allowance adjusting controls are performed, and deviations (OFFSET) between a target position in the detection range of the image sensor 45, 65 corresponding to a target width of the seam allowances and the center position C, are set. The values of the deviations (OFFSET) between the target position and the center position C are expressed in units of 0.1 [mm].

[0123] The data numbers in the sewing data indicate the process order, and the control device 13 reads the setting contents in this order.

[0124] The stitch number (PINNUM), the main shaft angle (FREQ), and the change point (POINT) are parameters for converting the timing to perform the first or second seam allowance adjusting control at each data number from the sewing start into a cumulated value (encoder unit system) of the output pulses of the encoder 16. These parameters satisfy the relationship shown by the following formula (1):

[0125] Fig. 12 is a diagram showing a relationship between the main shaft angle and the needle bar position (height). When the upper dead point of the needle bar is 0°, the range of the main shaft angle in which the sewing needle does not stick in the workpiece cloths is 270 to 90°. Therefore, the first or second seam allowance adjusting control and workpiece cloth lateral feeding operation control must be performed at 270 [deg] at the stitch number just before the target stitch number.

[0126] Therefore, when this start timing is converted into the encoder unit system, it is as shown by the formula (1) above. 1440 is the resolution of the encoder 16 (the number of output pulses per one rotation of the main shaft).

[0127] Fig. 13 shows a movement amount in the X-axis direction of each detecting device 40, 60, a change in target position in the detection range of the image sensor 45, 65, and a change in target width of the seam allowances when performing the sewing shown in Fig. 9, and Fig. 14 is a flowchart showing contents of processes of the first and second seam allowance adjusting controls to be performed by the control device 13 when performing the sewing shown in Fig. 9.

[0128] Based on these, the processes of the first and second seam allowance adjusting controls are described.

[0129] First, in the control device 13, various settings are initialized (Step S1). That is, a count value i of the data numbers the sewing data of which is read is set to 0, and a set offset value that is a count of the deviations between the target position in the detection range of the image sensor 45, 65 that corresponds to the target width of the seam allowances and the center position C is set to 0 (1 count is 0.1 [mm]), and a sensor position offset value that is a count of the movement amount of the upper/lower detecting device 40, 60 is set to 0 (1 count is 1.0 [mm]).

[0130] The initial positions of the upper and lower cloth detecting devices 40, 60 are set to positions 10 [mm] from the stitch point N that is a seam allowance initial value so as to match the center position C of the detection ranges of the upper and lower image sensors 45 and 65.

[0131] Then, the process waits for an input of sewing start into the operation panel 17 by an operator of the sewing machine (Step S3), and when the start is input, driving of the sewing machine motor 15 is started (Step S5). When driving of the sewing machine motor 15 is started, the control device 13 starts counting of output signals of the encoder 16 (Step S7). At this time, the encoder 16 also starts to output a number-of-rotations signal of one pulse per one rotation of the main shaft, and the control device 13 starts to count a stitch number count value.

[0132] Then, it is judged whether the count value of the encoder 16 has reached the value of the change point at the current data number (Step S9). For example, when the count value of the data numbers is i = 0, the change point is 135630.

[0133] Then, when the count value does not reach the change point at the time of judgment, the process is returned to Step S7 and counting of the encoder outputs is continued. When the count value of the encoder 16 reaches the change point, the value of the deviation (OFFSET) between the target position at the current data number and the center position C is added to the set offset value that is a count of the deviations between the target position in the detection range and the center position C (Step S11). For example, a state change that increases the deviation between the target position and the center position C in the section of 95th to 99th stitches and in the section of 195th to 199th stitches shown in (B) of Fig. 13 correspond to this process of Step S11.

[0134] For example, when the count value of the data numbers is i = 0, the deviation (OFFSET) is "1." By adding this, the new target position P1 is set to the position 10.1 [mm] from the stitch point N (see Fig. 7). In this case, the new target position P1 deviates by 0.1 [mm] in the X-axis forward direction from the center position C. The cloth edges of the workpiece cloths are laterally fed by the upper and lower lateral feed mechanisms 30, 50 to the target position P1 to correct the seam allowances to 10.1 [mm].

[0135] Then, when the set offset value is added, the count value i of the data numbers is also incremented by 1 (step S13). Accordingly, the control device 13 reads setting contents of the next data number. Further, the control device 13 judges whether the added set offset value has reached 10 (Step S15). When the set offset value does not reach 10, the control device returns the process to Step S7.

[0136] When this set offset value is less than 10, this means that the deviation between the target position in each detection range and the center position C is less than 1 [mm], and therefore, the control device 13 performs the first seam allowance adjusting control to change only the target position in each detection range without moving the upper cloth detecting device 40 and the lower cloth detecting device 60.

[0137] When the set offset value reaches 10, this means that the deviation between the target position in each detecting range and the center position C reaches 1 [mm], so that the control device 13 performs the second seam allowance adjusting control. Specifically, the control device resets the set offset value to 0, and adds 1 to the sensor position offset value. By this addition, the control device 13 drives the position adjustment motors 47, 67 to move the upper cloth detecting device 40 and the lower cloth detecting device 60 by 1 [mm] in the X-axis forward direction. In addition, the target position in each detecting range is matched with the center position C. For example, the state change at the 200th stitch shown in (A) and (B) of Fig. 13 corresponds to this.

[0138] More precisely, in Step S15, it is judged whether the cumulated set offset has reached +10 or -10. Specifically, even when the deviation toward the X-axis backward side of the target position in each detection range from the center position C reaches 1 [mm], control to match the target position in each detection range with the center position C is also performed. In this case, the control device 13 drives the position adjustment motors 47, 67 to move the upper cloth detecting device 40 and the lower cloth detecting device 60 by 1 [mm] in the X-axis backward direction.

[0139] Next, the control device 13 judges whether the stitch number count value has reached 300 that is a planned stitch number by referring to the stitch number count value (Step S19). Then, when it does not reach 300, the control device returns the process to Step S7, and when the stitch number count value reaches 300, the control device stops driving of the sewing machine motor 15 and ends the process.

[0140] Technical Effect of Embodiment of the Invention

[0141] As described above, the top and bottom feed sewing machine 100 includes position adjustment motors 47, 67 that move the detecting devices 40, 60 for the upper cloth CU and the lower cloth CD along the x-axis direction, and in the case where a target width of the seam allowances changes, when the target position in each detection range of the image sensor 45 and 65 for the upper cloth CU and the lower cloth CD that corresponds to the target width of the seam allowances separate by a predetermined distance (for example, 1 [mm]) or more from the center position C, the second seam allowance adjusting control is performed to move the upper and lower detecting devices 40, 60 by the upper and lower detection range adjusting mechanisms 46, 66 so that the target position and the center position C match each other, and the positions of the cloth edges of the upper cloth CU and the lower cloth CD can be detected at the center position C in each detection range of the image sensors 45 and 65, so that the cloth edges of the upper cloth CU and the lower cloth CD can be effectively prevented from deviating from the detection ranges and becoming undetectable, and seam allowance adjusting control can be stably performed.

[0142] In the case where the target width of the seam allowances changes, when the target position in each detection range of the image sensors 45 and 65 for the upper cloth CU and the lower cloth CD that corresponds to the target width of the seam allowances is at a distance less than the predetermined distance from the center position C, the control device 13 does not move the upper or lower detecting device 40 or 60, and performs the first seam allowance adjusting control to change only the target position in the detection range. Therefore, for example, even when the change in target width of the seam allowances is a minute distance smaller than the resolution of the position adjustment motors 47, 67, the target position in the detection range of the image sensor 45, 65 is set, and position detection of the cloth edges of the upper cloth CU and the lower cloth CD and lateral feeding operation control for sewing with seam allowances having the target width can be accurately performed.

[0143] The example shown in (A) of Fig. 13 illustrates a case where the detecting devices 40, 60 for the upper cloth CU and the lower cloth CD are moved at a high speed instantaneously in the above-described second seam allowance adjusting control, and a time required for the movement is not considered, however, a certain time is required for the movement as shown in (A) of Fig. 15 depending on the actual performance of the actuators.

[0144] Therefore, when the movement speed and the required time are known in advance, it is preferable that, according to the movement speed of the detecting devices 40, 60, the target position in each detection range is changed so that the target is gradually moved closer to the center position C as shown in (B) of Fig. 15. For example, when the detecting devices 40, 60 move by 1.0 [mm] per 10 [ms], the settings may be changed so that the target position in each detection range is moved closer to the center position C in increments of 0.1 [mm] per 1 [ms]. Accordingly, even during the movement of the detecting devices 40, 60, the cloth edges of the workpiece cloths can be detected with high accuracy.

[0145] The upper detection range adjusting mechanism 46 and the lower detection range adjusting mechanism 66 move the upper cloth detecting device 40 and the lower cloth detecting device 60 using a rack-pinion mechanism, however, but not limiting to this, a belt mechanism, a ball screw mechanism, a solenoid, a voice coil motor, a linear motor, etc., may be used to move the upper cloth detecting device 40 and the lower cloth detecting device 60.

[0146] In the first and second seam allowance adjusting controls, the above-described control device 13 determines a position separated by the target width W0 of the seam allowances from the stitch point N as the target position P0 in each detection range, and performs positioning control by using each detection range adjusting mechanism 46, 66 so that the target position P0 matches the center position C as a specified position of the detection range of the image sensor 45, 65, and in the case where the target width of the seam allowances is changed, when the new target position P1 is at a distance not more than the predetermined distance from the center position C as the specified position, without performing moving operations by the detection range adjusting mechanism 46, 66, the control device sets the target position P1 without change, and when the new target position P1 is at the predetermined distance or more from the center position C as the specified position, the control device performs positioning control by using each detection range adjusting mechanism 46, 66 so that the new target position P1 matches the center position C.

[0147] However, as described above, the setting of the target positions P0, P1 is not limited to the case where the specified position is the center position C.

[0148] For example, in a section of a predetermined number of stitches, when it is known in advance that the cloth edge shapes of the upper and lower cloths are curved, in the process of stitching, the upper and lower cloths easily deviate in the curving direction from the reference position (for example, when the cloth edge shapes curve leftward, the cloths easily deviate leftward), and in this case, it is preferable that to cope with occurrence of leftward deviation, by setting the specified position to a position offset rightward from the center position C instead of setting the specified position at the center position C, the detection range on the left side is secured to be wider than the detection range on the right side.

[0149] Therefore, it is also possible that the specified position can be arbitrarily set in advance by a setting means (e.g.,, the operation panel 17) and the set specified position is stored in a memory, etc., and in a curving section, etc., the detection range adjusting mechanisms 46, 66 are controlled so that the target positions P0, P1 match the set specified position in the detection ranges, or it is determined whether the detection range adjusting mechanisms 46, 66 are to be controlled depending on whether the target position is at the predetermined distance or more from the set specified position in the detection ranges.

Claims

1. A sewing machine (100) comprising:

a main feed mechanism (20) configured to feed a workpiece cloth (CU, CD) in a predetermined feeding direction (Y) along a horizontal plane;

a lateral feed mechanism (30, 50) configured to move the workpiece cloth (CU, CD) along a workpiece cloth width direction (X) parallel to the horizontal plane and orthogonal to the feeding direction (Y);

a cloth edge detecting device (40, 60) configured to detect a seam allowance from a cloth edge to a stitch point in the workpiece cloth width direction (X) of the workpiece cloth (CU, CD); and

a control section (13) configured to control the lateral feed mechanism (30, 50) based on the detection by the cloth edge detecting device (40, 60) such that the seam allowance of the workpiece cloth has a target width,

characterized in that the cloth edge detecting device (40, 60) comprises a light source (42, 62) for irradiating the cloth edge of the workpiece cloth (CU, CD) to be conveyed, and a detection section (45, 65) including a plurality of light receiving elements arranged along the workpiece cloth width direction (X) and configured to detect a position of the cloth edge of the workpiece cloth (CU, CD) in the workpiece cloth width direction (X) based on a difference in light amount of a portion of irradiation light blocked by the cloth edge of the workpiece cloth (CU, CD),

the sewing machine (100) further comprises an actuator (47, 67) configured to move the cloth edge detecting device (40, 60) along the workpiece cloth width direction (X), and

the control section (13) controls the actuator (47, 67) to move the cloth edge detecting device (40, 60) in accordance with a change in the target width (W0, W1) of the seam allowance.

2. The sewing machine (100) according to claim 1, wherein the control section (13) controls the actuator (47, 67) such that a target position (P0, P1) in a detection range of the cloth edge detecting device (40, 60) that corresponds to the target width (W0, W1) of the seam allowance matches a predetermined specified position in the detection range.

3. The sewing machine (100) according to claim 2, wherein the specified position is the center position (C) in the detection range.

4. The sewing machine (100) according to claim 2, further comprising a setting means (17) capable of setting the specified position to be an optional position in the detection range.

5. The sewing machine (100) according to any one of claims 2 to 4, wherein
the control section (13) is configured to:

set the target position (P1) in the detection range of the cloth edge detecting device (40, 60) that corresponds to a new target width (W1) of the seam allowance as a new target position (P1), when the target width (W0) of the seam allowance changes during sewing and when a distance (d1) from the target position (P1) in the detection range of the cloth edge detecting device (40, 60) that corresponds to the new target width (W1) of the seam allowance to the specified position is less than a predetermined distance, and

control the actuator (47, 67) such that the target position (P1) in the detection range of the cloth edge detecting device that corresponds to the new target width (W1) of the seam allowance matches the specified position, when the distance (d1) from the target position (P1) that corresponds to the new target width (W1) of the seam allowance to the specified position is equal to or more than the predetermined distance.

Drawing