JP2017136222A - sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the thickness of an object to be sewn.SOLUTION: A sewing machine includes: a light projection part 40 arranged upstream from a needle location in the feed direction of an object C to be sewn; and a camera 45 for taking an image of the object C to be sewn from a side opposite to the light projection part 40 while the object to be sewn is interposed therebetween. The thickness change of the object C to be sewn is detected from the brightness change of the image taken by the camera 45. In addition, in response to the detected thickness change of the object C to be sewn, control for changing the tension of the object to be sewn by a tension adjustment part 35 is performed, thereby reducing the occurrence of wrinkles caused by the thickness change.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sewing machine that detects a change in the thickness of a workpiece.

If the thickness of the workpiece is changed, the sewing quality may be affected.
For example, the sewing machine disclosed in Patent Document 1 is used to sew an elastic band-like material around an opening peripheral edge of a fabric such as pants.
In this sewing machine, the cylinder bed is inserted into the opening of the pants, the article to be sewn is sent along the opening, and the belt-like object in which the rubber string supplied from above is sewn is sewn along the opening. It was.

JP 2009-195578 A

In the case of clothing that wants to give stretchability to the opening of the pants as described above, in general, the belt-like material is sewn in a stretched state by applying tension before and after the needle drop position so that the opening of the fabric spreads. Do.
In the case of men's pants, generally, an opening is formed by a gap between overlapping portions by overlapping two cloths on the front side. The thickness of this overlapped portion is doubled, and if the belt is sewn with the same tension applied to the thick and thin portions, and the belt is sewn, the finished portion will be bent into a wave shape. There was a problem of being in a state.
For this reason, there has been a demand for detecting a change in the thickness of the sewing object before the needle drops.
The above prior art is an example of a request to detect the thickness of the sewing product, and the request to detect a change in the thickness of the sewing product is also present in sewing machines that perform different types of sewing. Yes.

  An object of the present invention is to provide a sewing machine capable of detecting a change in the thickness of a sewing product.

The invention according to claim 1 is a sewing machine,
A light projecting portion disposed upstream of the needle entry position in the feed direction of the sewing product;
A camera that images the sewing object from the opposite side of the light projecting unit across the sewing object;
And a thickness recognition processing unit that detects a change in the thickness of the sewing object from a change in brightness of a captured image captured by the camera.

The invention according to claim 2 is the sewing machine according to claim 1,
The sewing product includes an opening,
A roller that is inserted into the opening of the sewing product and supports the sewing product so as to be transportable in the feed direction, and a tension adjusting unit that adjusts the tension generated in the sewing product by changing the rotation state of the roller. A roller mechanism having
A tension control unit that performs control to change the tension of the sewing product by the tension adjusting unit according to the detected change in the thickness of the sewing product.

The invention according to claim 3 is the sewing machine according to claim 1 or 2,
And an end recognition processing unit that detects an end of the sewing product in a direction orthogonal to the feed direction from a change in brightness of a captured image captured by the camera.

The invention according to claim 4 is the sewing machine according to claim 3,
A lateral feed mechanism for moving the sewing product in a direction perpendicular to the feeding direction of the sewing product;
An end position control unit that controls the lateral feed mechanism according to a detection position of an end in a direction orthogonal to the feed direction of the sewing product is provided.

  In the present invention, the thickness recognition processing unit detects the change in the thickness of the sewing product from the change in the brightness of the captured image captured by the camera. Can be detected, and sewing corresponding to the change in thickness can be performed before the needle drops.

1 is a front view of a sewing machine according to an embodiment of the invention. It is a perspective view of a to-be-sewn product. It is explanatory drawing which showed the captured image of the part from which the thickness of a to-be-sewn material differs. It is the diagram which showed the change of the luminance value of the captured image by the change of the thickness of the to-be-sewn thing in the cloth feed direction. It is explanatory drawing which showed the captured image of the edge part of to-be-sewn material. It is a block diagram which shows the control system of a sewing machine. It is a flowchart which shows an example of the sewing control which a control apparatus performs. It is a control flowchart which shows control of the feed motor which a control apparatus performs during sewing.

[Outline of Embodiments of the Invention]
Hereinafter, a sewing machine 10 according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a front view of the sewing machine 10 with a part of the configuration omitted.
The sewing machine 10 includes a needle bar 12 that holds a sewing needle 11 at the lower end, a needle bar vertical movement mechanism that moves the needle bar 12 up and down, and an upper thread that is passed through each sewing needle 11 to capture a lower thread. A hook mechanism that is entangled, a cloth presser 13 that presses the sewing product from above at the needle drop position, and a feed dog that protrudes and retracts from an opening formed in the throat plate at a constant feed pitch downstream of the sewing product in the feed direction. A feed mechanism that feeds the sewing product, a roller mechanism 30 that supports the sewing product so that it can be conveyed in the feed direction by first to fourth rollers 31 to 34 inserted into the opening of the sewing product, and sewing A lateral feed mechanism 60 that moves the sewing product in a direction perpendicular to the feed direction of the product, a light projecting unit 40 that projects light onto the sewing product on the upstream side in the feed direction from the needle drop position of the needle plate, Is it under the light projecting part 40 and opposite to the light projecting part (lower side) across the sewing product? A camera 45 for imaging the workpiece, the machine frame 14 for supporting or storing the respective configuration, and a control unit 90 for controlling the operation of each of the above structures.

The sewing machine frame 14 includes a sewing bed portion 141 located at a lower portion, a standing body portion 142 raised from the sewing bed portion 141, and a sewing machine extending from the upper end portion of the standing body portion 142 in parallel with the sewing bed portion 141. Arm portion 143.
In addition, the front end of the sewing machine bed 141 in the extending direction is provided with a cylindrical cylinder bed 144 that extends further in the extending direction. A needle plate (not shown) having a horizontal upper surface is provided on the upper portion of the cylinder bed 144, and the workpiece is conveyed along the upper surface of the needle plate, and sewing is performed on the needle plate.

  Hereinafter, the direction parallel to the upper surface of the needle plate and the workpiece to be conveyed is the X-axis direction, and the direction parallel to the upper surface of the needle plate and perpendicular to the X-axis direction is the Y-axis direction (on the paper surface of FIG. 1). A vertical vertical direction perpendicular to both the X-axis direction and the Y-axis direction is defined as a Z-axis direction. Also, the direction in which the workpiece is fed in the X-axis direction is “downstream in the feed direction”, and the opposite direction is “upstream in the feed direction”, and the left hand is in the Y-axis direction and faces the downstream in the feed direction. The left side is referred to as “left side”, and the right hand side is referred to as “right side”.

  The needle bar up-and-down moving mechanism converts a sewing machine motor 15 (see FIG. 6), an upper shaft along the Y-axis direction rotated by the sewing machine motor 15, and a rotational force of the upper shaft into a driving force for vertical movement. Since it is a well-known structure provided with the crank mechanism provided to the needle bar 12, detailed description is abbreviate | omitted.

The shuttle mechanism includes a lower shaft along the Y-axis direction through which torque is transmitted at a double speed of the upper shaft via a belt mechanism, and a shuttle that rotates by the lower shaft.
Since the shuttle mechanism is a well-known configuration, a detailed description thereof is omitted.

The cloth presser 13 is provided at the lower end portion of the presser bar 131 supported by the sewing machine arm part 143 so as to be movable up and down, and a pressing pressure is applied downward by a spring (not shown).
The cloth presser 13 is provided at a needle drop position on the needle plate, and an opening for allowing the sewing needle 11 to drop the needle is formed.

  The feed mechanism consists of a feed dog that protrudes and retracts from the needle hole of the needle plate, a feed base that holds the feed dog, and a horizontal feed mechanism that converts the rotation of the lower shaft into a reciprocating motion along the X-axis direction and transmits it to the feed base. And a vertical feed mechanism that converts the rotation of the lower shaft into a reciprocating motion along the Z-axis direction and transmits it to the feed base. Since these are well-known structures, detailed description is omitted.

[Roller mechanism]
The roller mechanism 30 includes four first to fourth rollers 31 to 34 that are inserted into the opening of the workpiece, and a feed motor 35 as a tension adjusting unit that drives the first roller 31 (see FIG. 6). And.
The first to fourth rollers 31 to 34 are all supported by the sewing machine bed portion 141 so as to be rotatable about the Y axis, and the first roller 31 is an adjustment variable portion that arbitrarily adjusts the rotation speed. The adjustment variable motor 35 is connected to the output shaft.
Further, the second to fourth rollers 32 to 34 are rollers that rotate in response to an external force.

The first and second rollers 31 and 32 are arranged on the upstream side and the downstream side in the feed direction of the sewing product with respect to the needle plate, and the upper ends thereof are arranged so as to be at the same height as the upper surface of the needle plate. ing.
The third roller 33 is disposed below the second roller 32, and the fourth roller 34 is disposed below the first roller 34.
And the outer peripheral surface of these 1st-4th rollers 31-34 is made into the raw material with a large frictional resistance.
Further, each of the rollers 31 to 34 is supported only by the right end portion, and the left end portion is a free end. Thereby, each roller 31-34 can be hold | maintained in the state inserted from the free end side with respect to the opening part of to-be-sewn material.
In addition, the third and fourth rollers 33 and 34 are more than the cylinder bed 144 so that tension is generated at the opening of the sewing product in a state where the rollers 31 to 34 are inserted into the opening of the sewing product. Located in the low position.
When these rollers 31 to 34 apply tension to the workpiece, the rollers 31 to 34 rotate in conjunction with each other.

The feed motor 35 has an output shaft connected to the first roller 31 via a tying belt. By rotating the first roller 31, the feed motor 35 is fed in the same direction as the feed direction of the sewing product by the feed mechanism. It is possible to transport the sewing product.
Further, the feed motor 35 rotationally drives the first roller 31 at a speed lower than the feed speed of the workpiece to be sewn by the feed mechanism, whereby the workpiece to be sewn between the first roller 31 and the cloth presser 13 is driven. It is possible to adjust the tension.
The driving speed of the feed motor 35 is controlled by the control device 90.

[Horizontal feed mechanism]
The lateral feed mechanism 60 includes a pair of upper and lower rollers 61 and 61 disposed so as to sandwich the sewing product from above and below between the light projecting unit 40 and the needle drop position, and the rollers 61 and 61 are arranged along the Y-axis direction. A lateral feed motor 62 (see FIG. 6).
The pair of rollers 61 and 61 are both supported by a base (not shown) so as to be rotatable around a support shaft along the Y-axis direction, and the two articles 61 and 61 gently hold the workpiece to be sewn. The driven rotation is performed in accordance with the workpiece to be conveyed. The rollers 61 and 61 are formed of a material having a large frictional resistance on the outer peripheral surface thereof.
The base supporting the pair of rollers 61 and 61 is supported so as to be movable along the Y-axis direction on the upper surface of the sewing machine bed portion 141, and can be arbitrarily positioned in the Y-axis direction by the lateral feed motor 62. Yes.
With the above configuration, the lateral feed mechanism 60 can arbitrarily adjust the position of the right end in the Y-axis direction of the workpiece to be conveyed.

[Projector and camera]
The light projecting unit 40 is for projecting illumination light from above the workpiece to be conveyed between the lateral feed mechanism 60 and the first roller 31. The light projecting unit 40 includes a light source 41 including light emitting elements (for example, LEDs) arranged downward along a plurality of rows along the Y-axis direction on the substrate, and irradiation light from each light emitting element. And a scattering plate 42 for making scattered light.

  The camera 45 is disposed below the light projecting unit 40 and captures an image of a sewing product that transmits light projected from the light projecting unit 40.

Here, the sewing product C will be described. FIG. 2 is an explanatory view showing the structure of the sewing product C. FIG. As shown in the drawing, the article C to be sewn is a pant for men, and is mainly composed of a left cloth C1, a right cloth C2, and a belt-like object C3 in which a rubber string is sewn.
The left cloth C1 and the right cloth C2 are sewn on the front side and the rear side, and the front side part is sewn so that the end of the left cloth C1 overlaps the end of the right cloth C2, and leads to the inside. A gap-shaped opening is formed.
Further, the left cloth C1 and the right cloth C2 are sewn together in a substantially cylindrical shape, the upper end portion is wide open, and the lower end portion is bifurcated.
And the strip | belt-shaped object C3 is sewn so that it may make a round along the edge part of the opening part C11 of an upper end part.

The sewing machine 10 can perform sewing and sewing with the belt-like object C3 on the upper end opening C11 of the left cloth C1 and the right cloth C2 that have already been sewn together.
The sewing machine 10 is set on the sewing machine 10 with the upper end opening C11 of the sewing product C facing right and the rollers 31 to 34 of the roller mechanism 30 and the cylinder bed 144 inserted into the upper end opening C11. The belt-like object C3 is sewn along the opening C11.

The light projecting unit 40 projects light from above on the workpiece C to be conveyed, and the camera 45 captures an image of the sewing product from below so that the amount of light transmitted by the light projecting unit 40 is projected. Therefore, it is possible to detect a thick portion of the cloth C in the sewing product C, that is, an overlapping portion C12 of the left cloth C1 and the right cloth C2.
FIG. 3 shows a part of an image taken by the camera 45, and more specifically shows a boundary between the left cloth C1 and the overlapping portion C12.
FIG. 4 is a diagram showing changes in luminance values of pixels for one column along the X-axis direction in the imaging range of FIG.
In FIG. 4, a pixel position of approximately 200 pixels is a position that becomes a boundary between the left cloth C1 and the overlapping portion C12. As illustrated, the left cloth C1 portion has a high luminance value of about 150 to 200, and the luminance value decreases to about 5 to 10 in the overlapping portion C12 from the boundary position.
Therefore, the position that becomes the boundary between the left cloth C1 and the overlapping portion C12 can be obtained from the position in the captured image where the luminance value changes in the X-axis direction. Further, the position that becomes the boundary between the right cloth C2 and the overlapping portion C12 can be similarly obtained.

Further, the right end of the sewing product C in the Y-axis direction can be obtained from the image captured by the camera 45.
FIG. 5 shows a part of an image captured by the camera 45, and more specifically shows the boundary between the right end of the sewing product C and the background H. As shown in the drawing, it can be seen that the brightness value of the sewing product C is clearly lower than that of the background H.
Therefore, the change in the luminance value of the pixels for one column along the Y-axis direction in the imaging range is obtained, and the Y of the sewing object C is determined from the position in the imaging range where the luminance value suddenly decreases from right to left. The right end in the axial direction can be determined.
In the sewing of the sewing product C, the set value of the distance from the right end of the sewing product C in the Y-axis direction to the needle drop position is recorded in the control device 90, and the sewing product C in the Y-axis direction is recorded. When the position of the right end is acquired, the lateral feed mechanism 60 is controlled to maintain the set value.

[Sewing machine control system]
As shown in FIG. 6, the control device 90 includes a display panel 94 that displays various settings relating to sewing and the current state of the sewing machine, and screen selections and commands for performing various settings provided in the display panel 94. A setting switch 95 as setting input means for inputting various setting values and a start switch 98 for inputting the start of sewing are connected via an input / output circuit (not shown).

  The start switch 98 is means for inputting a drive command for a sewing operation to the control device 90 by an input operation. That is, when the start switch 98 is input, the control device 90 performs operation control for starting sewing.

  From the setting switch 95, the feed pitch for obtaining the feed speed by the feed mechanism, the set value from the right end of the sewing product C to the needle drop position, the X axis direction from the camera 45 to the needle drop position, and the Y axis The distance in the direction, the threshold value of the luminance value for determining the boundary between the left cloth C1 or the right cloth C2 of the sewing product C and the overlapping portion C12, the threshold value of the luminance value for determining the boundary between the sewing object C and the background H Etc. are input.

Further, the control device 90 includes a sewing machine motor 15, a feed motor 35, a transverse feed motor 62, an LED of the light source 41 of the light projecting unit 40, and a camera 45, which are to be controlled, respectively, as drive circuits 15 a, 35 a, 62 a, 41 a. , 45a.
The control device 90 is connected to an image processing unit 46 for processing captured image data of the camera 45.
Furthermore, the upper shaft is equipped with an encoder 151 that detects the shaft angle, and the encoder 151 is connected to the control device 90.
The encoder 151, the drive circuits 15a, 35a, 62a, 41a, 45a and the image processing unit 46 are connected to the control device 90 via an interface (not shown).
Further, the control device 90 includes a CPU 91 that performs various controls, and a memory 92 in which a control program that executes operation control of the sewing machine 10 is written.

[Feed control of sewing product]
The feed control of the sewing product C performed by the control device 90 will be described based on the flowcharts of FIGS.
When the start switch 98 is pressed, the CPU 91 of the control device 90 starts driving the sewing machine motor 15 and executes the processing shown in the flowchart of FIG. Further, independent of the processing of FIG. 7, the control of the feed motor shown in the flowchart of FIG.

First, as shown in FIG. 7, the CPU 91 images the sewing object C by the camera 45 while projecting light from the light projecting unit 40 (step S <b> 1), and the start end of the overlapping portion C <b> 12 exists in the captured image. It is determined whether or not to perform (step S3).
The start end of the overlap portion C12 overlaps the downstream end portion in the X-axis direction of the overlap portion C12 of the sewing product C, that is, the right cloth C2 on the straight line along the X-axis direction passing through the needle drop position. This is the boundary position with the part C12.
The captured image signal of the camera 45 is A / D converted by the image processing unit 46 and converted to captured image data indicating luminance values in all pixels within the imaging range. Further, the image processing unit 46, in the captured image data, for a plurality of pixels arranged on a straight line along the X-axis direction passing through the needle drop position, a difference value of luminance values between adjacent pixels. Is calculated.
Then, the CPU 91 determines whether there is a difference value between adjacent pixels that shows a decrease that is greater than or equal to a threshold value.

If there is a difference that is lower than the threshold value among the difference values between adjacent pixels, it is determined that the start end of the overlapping portion C12 exists in the captured image (step S3: YES), and is equal to or higher than the threshold value. Is recognized as the start end of the overlapping portion C12.
Thereby, the CPU 91 of the control device 90 functions as a “thickness recognition processing unit that detects a change in the thickness of the sewing object from a change in the brightness of the captured image captured by the camera”.

Since the overlapping portion C12 of the sewing product C is overlapped with two pieces of fabric, when the belt-like product C3 is sewn while applying tension to the opening C11 of the sewing product C, the overlapping portion C12 other than the overlapping portion C12 is used. The amount of extension due to tension is smaller than that of the portion, and after the belt-like object C3 is sewn, the overlapping portion C12 is wavy or wrinkled due to the contraction force of the belt-like object C3. In order to avoid this, the CPU 91 increases the tension applied to the sewing product C while the overlapping portion C12 passes the needle drop position so that the overlapping portion C12 extends to the same extent as the other portions. The roller mechanism 30 is controlled.
Therefore, when the start end of the overlapping portion C12 is detected, the CPU 91 starts counting of a tension adjustment start timer for measuring the timing at which the start end of the overlapping portion C12 reaches the needle drop position (step S5).
Since the distance in the X-axis direction from the camera 45 to the needle drop position is input by the setting switch 95 and the imaging range of the camera 45 is already known, the CPU 91 handles between the two pixel positions that have fallen above the threshold. The distance from the position on the workpiece to be stitched to the needle drop position can be calculated. Moreover, since the rotation speed of the sewing machine motor 15 can be acquired from the output of the encoder 151 and the feed pitch is known, the average feed speed of the sewing product C can be obtained. Thus, it is possible to calculate the time from imaging until the start end of the overlapping portion C12 reaches the needle drop position, and the calculation time is counted by the tension adjustment start timer.

On the other hand, if there is no difference value between adjacent pixels that shows a decrease greater than or equal to the threshold value, it is determined that the start end of the overlapping portion C12 does not exist in the captured image (step S3: NO), and imaging is performed. It is determined whether or not the end of the overlapping portion C12 exists in the image (step S7).
The end of the overlap portion C12 overlaps the end portion on the upstream side in the X axis direction of the overlap portion C12 of the sewing product C, that is, the left cloth C1 on the straight line along the X axis direction passing through the needle drop position. This is the boundary position with the part C12.

Therefore, the CPU 91 determines that the difference value of the luminance value between the adjacent pixels and the pixels is equal to or greater than the threshold value among the plurality of pixels arranged on the straight line along the X-axis direction passing through the needle drop position of the captured image data. It is determined whether or not there is an indication of an increase.
If there is a difference value between adjacent pixels that indicates an increase above the threshold value, it is determined that the end of the overlapping portion C12 exists in the captured image (step S7: YES), and the difference value is equal to or greater than the threshold value. Is recognized as the end of the overlapping portion C12.

When the start end of the overlapping portion C12 is detected and the control for increasing the tension to be applied to the sewing product C is performed, when the end end of the overlapping portion C12 reaches the needle drop position, it is applied to the sewing product C. It is necessary to return the tension to be returned to the normal value.
Therefore, when the end of the overlapping portion C12 is detected, the CPU 91 starts counting a tension adjustment end timer for measuring the timing at which the end of the overlapping portion C12 reaches the needle drop position (step S9).
Since the distance in the X-axis direction from the camera 45 to the needle drop position is input by the setting switch 95, and the imaging range of the camera 45 is known, the CPU 91 handles between two pixel positions that have risen above the threshold. The distance from the position on the workpiece to be stitched to the needle drop position can be calculated, and as described above, the average feed speed of the workpiece C can also be obtained. The time until the end of C12 reaches the needle drop position is calculated, and the calculated time is counted by the tension adjustment end timer.

  After starting the count of the tension adjustment start timer (step S5), after starting the count of the tension adjustment end timer (step S9), or when it is determined that the end of the overlapping portion C12 does not exist in the captured image (step S7: NO). The CPU 91 detects the position in the Y-axis direction of the right end of the sewing product C in the captured image (step S11).

That is, the CPU 91 sets the adjacent pixels and pixels from left to right among a plurality of pixels arranged on a straight line along the Y-axis direction passing through the center of the imaging range of the captured image data. The thing which shows the difference value of a luminance value showing the raise beyond a threshold value is specified.
Then, the position between the two adjacent pixels showing the difference value rising above the threshold value is recognized as the position in the Y-axis direction of the right end of the sewing product C.
Since the distance in the Y-axis direction from the camera 45 to the needle drop position is input by the setting switch 95 and the imaging range of the camera 45 is known, the CPU 91 determines the right side of the sewing product C from the needle drop position in the Y-axis direction. The distance to the end can be calculated.
Accordingly, the CPU 91 functions as “an end recognition processing unit that detects an end of the sewing product in a direction orthogonal to the feeding direction from a change in brightness of a captured image captured by the camera”.

Then, the calculated value of the distance from the right end of the sewing product C to the needle drop position is compared with the set value from the right end of the sewing product C to the needle drop position. Is larger, the difference value between the calculated value and the set value is obtained, and the transverse feed motor 62 of the transverse feed mechanism 60 is driven to move the workpiece to the left by a distance corresponding to the difference value. .
Further, when the calculated value is smaller than the set value, the difference value between the calculated value and the set value is obtained, and the lateral feed motor 62 of the lateral feed mechanism 60 is driven, and the distance corresponding to the difference between the sewing product and the sewing product is obtained. Move to the right by the amount (step S13). Thus, the CPU 91 functions as an “end position control unit”.
When the end of sewing is input by the start switch 98 (step S15: YES), the drive of the sewing machine motor 15 is stopped (step S17), the process is ended, and if the sewing is continued (step S15: NO), Returning to step S1, the process is repeated.

Further, the CPU 91 periodically executes the process of FIG. 8 independently of the process of FIG. That is, with reference to the count value of the tension adjustment start timer described above, the time from the imaging calculated in the latest processing of step S5 in FIG. 7 until the start end of the overlapping portion C12 reaches the needle drop position is counted up. It is determined whether or not (step S31).
If the count is incremented (step S31: YES), control is performed to decelerate the feed motor 35 of the feed mechanism 30 to a predetermined low speed (step S33). When the feed motor 35 decelerates, the tension with respect to the sewing product C increases between the feed dog and the first roller 31, and the extension amount of the overlapping portion C12 can be increased. Thus, the CPU 91 functions as a “tension control unit that performs control to change the tension of the sewing product”.
The feed motor 35 of the feed mechanism 30 may be arbitrarily set from the setting switch 95 at a predetermined low speed.
Then, the process ends.

Further, when the CPU 91 determines that the tension adjustment start timer has not been counted up (step S31: NO), the CPU 91 refers to the count value of the tension adjustment end timer described above, and immediately performs the process of step S9 in FIG. It is determined whether or not the time from the imaging calculated in step S <b> 12 until the end of the overlapping portion C <b> 12 reaches the needle drop position is counted up (step S <b> 35).
And when it counts up (step S35: YES), control which makes the feed motor 35 of the feed mechanism 30 normal rotation speed is performed (step S37). When the feed motor 35 rotates normally, the tension on the workpiece C between the feed dog and the first roller 31 becomes a normal value. Then, the process ends.
Further, even when the tension adjustment end timer has not been counted up (step S35: NO), the process is ended, and when a certain time has elapsed, the process is newly started from step S31.

[Technical effects of the embodiment]
As described above, the sewing machine 10 is sewn from the side opposite to the light projecting unit 40 with the light projecting unit 40 disposed on the upstream side of the sewing position from the needle drop position and the product C to be sewn. A camera 45 that captures an image of the object C, and the CPU 91 of the control device 90 functions as a thickness recognition processing unit that detects a change in the thickness of the sewing object from a change in the brightness of the captured image captured by the camera 45. Therefore, it is possible to detect the position where the thickness changes due to the overlapping portion C12 of the conveyed sewing product C, and it is possible to perform sewing corresponding to the change in thickness.
In addition, by using the fact that the stepped portion appears dark in the transmitted illumination by the light projecting unit 40, image processing is performed on the designated region of the image captured by the camera 45, and a portion where the change in brightness is large is detected as the stepped portion. Accordingly, it is possible to detect the stepped portion even in the case of a patterned pattern or a dark-colored workpiece.

  Further, the sewing machine 10 is inserted into the opening C11 of the sewing product C, and changes the rotation state of the first roller 31 and the plurality of rollers 31 to 34 that support the sewing product C so as to be transportable in the feed direction. The roller mechanism 30 having the feed motor 35 as a tension adjusting unit that adjusts the tension generated in the sewing product C, and the CPU 91 of the control device 90 detects the sewing product detected by the change in the luminance value of the captured image. Since the feed motor 35 controls the tension of the sewing product C to be changed in accordance with the change in the thickness of the belt, the occurrence of wavy bending and wrinkles occurring at the sewing position of the strip C3 with respect to the overlapping portion C12 is reduced. Therefore, it is possible to improve the sewing quality corresponding to the change in the thickness of the workpiece C.

In the sewing machine 10, the CPU 91 detects a Y-axis direction end (right end) orthogonal to the feed direction of the sewing object C from a change in brightness of a captured image captured by the camera 45. Therefore, it is possible to detect a change in the distance in the Y-axis direction from the right end of the sewing product C to the needle drop position.
Furthermore, since the CPU 91 controls the lateral feed mechanism 60 according to the detection position of the right end of the sewing product C, the CPU 91 moves in the Y-axis direction from the right end of the sewing product C to the needle drop position. The distance can be maintained at the set value, the needle can be moved to an appropriate position with respect to the sewing object C, and the sewing quality can be improved.

[Others]
The sewing machine 10 uses the transmitted light from the light projecting unit 40 and the camera 45 in order to reduce the occurrence of wavy bending and wrinkles caused by the thickness change due to the overlapping portion C12 in the sewing product C. Although the thickness of C is detected, the purpose of use of the thickness detection is not limited to the reduction of the occurrence of wavy deflection and wrinkles.
For example, an intermediate presser that moves up and down at the same cycle as the sewing needle is provided to smoothly pull out the sewing needle from the sewing product, and the height of the bottom dead center can be arbitrarily adjusted by motor control. In the case of a sewing machine, there is a possibility that sewing may not be performed properly due to a change in the thickness of the fabric, which may cause the intermediate presser to come into contact and hinder the movement of the sewing product or cause wrinkles.
Even in such a sewing machine, a light projecting unit that projects light on the sewing product and a camera that images the sewing product from the opposite side of the light projecting unit through the sewing product are provided, and a needle drop in the sewing product is provided. Control may be performed in which the thickness of the upstream portion in the cloth feeding direction with respect to the position is detected, and the bottom dead center height of the intermediate presser is changed and adjusted according to the thickness. Accordingly, it is possible to avoid the interference between the intermediate presser and the workpiece and improve the sewing quality.
Further, the arrangement of the light projecting unit 40 and the camera 45 may be upside down.

DESCRIPTION OF SYMBOLS 10 Sewing machine 30 Roller mechanism 31-34 1st-4th roller 35 Adjustment variable motor (Tension adjustment part)
40 Light Emitting Unit 41 Light Source 42 Scattering Plate 45 Camera 46 Image Processing Unit 60 Horizontal Feed Mechanism 62 Horizontal Feed Motor 90 Controller 91 CPU (Thickness Recognition Processing Unit, Tension Control Unit, End Part Recognition Processing Unit, End Position Control Unit )
C to-be-sewn product C1 left cloth C2 right cloth C3 strip C11 opening C12 overlap part

Claims (4)

A light projecting portion disposed upstream of the needle entry position in the feed direction of the sewing product;
A camera that images the sewing object from the opposite side of the light projecting unit across the sewing object;
A sewing machine comprising: a thickness recognition processing unit configured to detect a change in thickness of the sewing product from a change in brightness of a captured image captured by the camera. The sewing product includes an opening,
A roller that is inserted into the opening of the sewing product and supports the sewing product so as to be transportable in the feed direction, and a tension adjusting unit that adjusts the tension generated in the sewing product by changing the rotation state of the roller. A roller mechanism having
The tension control part which performs control which changes the tension | tensile_strength of the said to-be-sewn thing by the said tension adjustment part according to the change of the thickness of the said to-be-sewn thing detected is provided. sewing machine.   3. An end recognition processing unit that detects an end of the sewing product in a direction orthogonal to the feeding direction from a change in brightness of a captured image captured by the camera. The described sewing machine. A lateral feed mechanism for moving the sewing product in a direction perpendicular to the feeding direction of the sewing product;
The sewing machine according to claim 3, further comprising an end position control unit that controls the lateral feed mechanism in accordance with a detection position of an end in a direction orthogonal to the feed direction of the sewing product.