Sewing machine

Abstract

To suppress reduction in productivity of sewing.SOLUTION: A sewing machine has a sewing needle, a feed dog, a linear image sensor, an imaging optical system, and a controller. The sewing needle has a hole through which a yarn is passed, and penetrates a sewn article by moving downward and comes out from the sewn article by moving upward. The feed dog feeds the sewn article backward by moving under the sewn article. The linear image sensor is disposed behind the sewing needle so as to be separated upward or downward from the sewn article. The imaging optical system is disposed between the sewn article and the linear image sensor. While the sewing needle is vertically moving and the feed dog is feeding, the controller activates the linear image sensor to perform a periodic imaging operation and determines normality of the seam on the basis of a linear image of the sewn article and the seam, which is periodically imaged by the linear image sensor.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a sewing machine. [Background technology]

[0002] Patent Document 1 discloses a seam inspection device that detects abnormalities in seams made by a sewing machine. Specifically, an imaging device of the seam inspection device captures an image of a sewn item such as cloth, and a processing device of the seam inspection device detects abnormalities in the seam based on the captured image. This imaging device employs an area image sensor of the rolling shutter type. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP2019-154936A Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, the feed speed of the sewing workpiece is slow so as not to cause blurring of the sewing workpiece captured by the imaging device. In particular, the feeding of the sewing workpiece is intermittent, and the images captured by the imaging device in synchronization with the intermittent stops of the feeding of the sewing workpiece are used for inspection. Therefore, if the technology disclosed in Patent Document 1 is used, sewing productivity is low. Therefore, the technique disclosed in this specification aims to suppress a decrease in sewing productivity. [Means for solving the problem]

[0005] This specification discloses a sewing machine. The sewing machine includes a sewing needle, a feed dog, a linear image sensor, an imaging optical system, and a controller. The sewing needle has a hole through which a thread passes, and penetrates the sewn object by descending, and comes out of the sewn object by ascending. The feed dog moves under the sewn object to feed the sewn object backward. The linear image sensor is disposed above or below the sewn object behind the sewing needle, and extends left and right. The imaging optical system is disposed between the sewn object and the linear image sensor, and images of the sewn object and the stitches formed thereon are formed on the linear image sensor. The controller causes the linear image sensor to periodically capture images while the sewing needle is ascending and descending and while the feed dog is feeding, and judges the normality of the stitches based on the linear images of the sewn object and the stitches periodically captured by the linear image sensor. Effect of the Invention

[0006] According to the technology disclosed in this specification, it is possible to suppress a decrease in sewing productivity. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a sewing machine. [Diagram 2] FIG. 2 is a diagram showing the arm and bed of the sewing machine as viewed from the left. [Diagram 3] FIG. 3 is a perspective view showing the linear image sensor, the imaging optical system, and the illuminator. [Figure 4] FIG. 4 is a block diagram showing the circuitry of the sewing machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described with reference to the drawings. The features and technical effects of the embodiments will be understood from the following detailed description and drawings. However, the scope of the present invention is not limited to the embodiments disclosed below. The drawings are provided for illustrative purposes only, and therefore the scope of the present invention is not limited to the illustrations in the drawings.

[0009] [1. Overview of the sewing machine] 1 to 3 show arrows representing the mutually orthogonal height, depth, and width directions. The height direction is also called the up-down direction, the depth direction is also called the front-rear direction, and the width direction is also called the left-right direction. The height direction is not necessarily vertical, but when the sewing machine 1 is placed on a horizontal surface, the height direction becomes the vertical direction. The directions of left and right are determined when viewed from the front of the sewing machine 1.

[0010] As shown in Fig. 1, a sewing machine 1 is a sewing machine that applies a stitch to a sewing object 99. The stitch may be either a chain stitch or a lock stitch.

[0011] As shown in Figs. 1 to 4, the sewing machine 1 includes a sewing machine frame 10, a needle plate 16, a presser foot 18, a motor 20, a feed dog 21, a needle bar 22, a sewing needle 23, a transparent plate 40, a linear image sensor 45, an imaging optical system 50, an illuminator 60, a controller 70, a motor driver 72, an illumination driver 74, a drive circuit 76, and an image processing circuit 78. When the sewing machine 1 forms a chain stitch on a sewing object 99, the sewing machine 1 includes a looper. When the sewing machine 1 forms a lock stitch on a sewing object 99, the sewing machine 1 includes a shuttle. The combination of the linear image sensor 45, the imaging optical system 50, and the illuminator 60 is called a CIS (Contact Image Sensor). Hereinafter, the looper and the shuttle are collectively referred to as a thread processing mechanism.

[0012] [2. Sewing machine frame] The sewing machine frame 10 is U-shaped when viewed from the front. The sewing machine frame 10 has a vertical body portion, an arm portion 12 and a bed portion 13.

[0013] The arm portion 12 forms the upper portion of the sewing machine frame 10, and extends leftward from the upper portion of the vertical body portion which is the right portion of the sewing machine frame 10. The bed portion 13 forms the lower portion of the sewing machine frame 10, and extends leftward from the lower portion of the vertical body portion. The bed portion 13 has, on its upper surface, a flat bed surface 14 which extends in all directions. The bed surface 14 supports the sewing object 99 from below the sewing object 99. The sewing object 99 is fed from front to back on this bed surface 14 during sewing. The sewing object 99 refers to an object to be sewn by the sewing machine 1, such as cloth.

[0014] [3. Motor] The motor 20 is provided on the right side of the inside of the arm portion 12. The motor 20 outputs power to the feed transmission mechanism, the needle bar transmission mechanism, and the lower transmission mechanism, thereby moving the needle bar 22 up and down, moving the feed dog 21 in an elliptical motion or box motion, and moving the thread processing mechanism.

[0015] [4. Throat plate, presser foot and feed dog] The needle plate 16 is attached to the upper surface of the bed portion 13, and the upper surface of the needle plate 16 is flush with the bed surface 14. The needle plate 16 supports the workpiece 99 from below. The needle plate 16 has a needle hole, and when a sewing needle 23, which will be described later, descends, the sewing needle 23 penetrates the workpiece 99 and is inserted into the needle hole, and when the sewing needle 23 ascends, the sewing needle 23 comes out of the needle hole and the workpiece 99.

[0016] The presser foot 18 hangs down from the bed portion 13 and is provided so as to be capable of being raised and lowered. The presser foot 18 is lowered to press the workpiece 99 from above the needle plate 16. As a result, the workpiece 99 is sandwiched between the presser foot 18 and the needle plate 16, and is also sandwiched between the presser foot 18 and the feed dog 21. When the presser foot 18 is raised and separated from the workpiece 99, the workpiece 99 is released.

[0017] The feed dog 21 is disposed inside the hole of the needle plate 16 below the presser foot 18. The feed dog 21 is connected to a feed transmission mechanism inside the bed portion 13, and is provided so that the feed transmission mechanism can perform elliptical or box motion. The feed transmission mechanism is connected to a motor 20, and the rotational motion of the motor 20 is converted into elliptical or box motion of the feed dog by the feed transmission mechanism. As a result, the sewing workpiece 99 is fed from front to rear by the feed dog 21. Note that the elliptical motion means that the feed dog 21 revolves along an elliptical locus that is long front to back and short up to down. The box motion means that the feed dog 21 revolves along a rectangular locus that is long front to back and short up to down.

[0018] [5. Needle bar, sewing needle and thread handling mechanism] Needle bar 22 extends downward from the inside to the outside of arm portion 12. Needle bar 22 is connected to a needle bar transmission mechanism, such as a crank mechanism, inside arm portion 12, and is provided so that it can reciprocate up and down by the needle bar transmission mechanism. The needle bar transmission mechanism is connected to motor 20, and the rotational motion of motor 20 is converted into the vertical motion of needle bar 22 by the needle bar transmission mechanism.

[0019] The sewing needle 23 is attached to the lower end of the needle bar 22 and extends downward from the lower end of the needle bar 22. A thread is guided from the spool to the sewing needle 23 and passed through an eye of the sewing needle 23.

[0020] The thread processing mechanism is disposed inside the bed portion 13 below the needle bar 22. The thread processing mechanism is connected to a lower transmission mechanism inside the bed portion 13. The lower transmission mechanism is connected to a motor 20, and the rotational motion of the motor 20 is converted into an orbital motion or a reciprocating motion of the thread processing mechanism by the lower transmission mechanism.

[0021] When the motor 20 drives the feed dog 21, the needle bar 22, and the thread handling mechanism, the sewing needle 23 moves up and down, the thread handling mechanism moves in a circle or reciprocating motion, and the feed dog 21 moves in an elliptical or box motion. The sewn workpiece 99 is fed backward by the elliptical or box motion of the feed dog 21. The sewing needle 23 cooperates with the thread handling mechanism to stitch the workpiece 99 while feeding the workpiece 99. If the thread handling mechanism is a looper, the looper captures the thread from the sewing needle 23 every time the sewing needle 23 penetrates the workpiece 99 downward, forming a loop of the thread, and entangles this loop with the loop made when the sewing needle 23 descended the previous time. If the thread handling mechanism is a shuttle, the shuttle captures the thread from the sewing needle 23 every time the sewing needle 23 penetrates the workpiece 99 downward, forming a loop of the thread, and entangles the lower thread drawn from a bobbin case in the shuttle with the loop.

[0022] [6. Transparent plate, linear image sensor, imaging optical system and illuminator] 1 and 2, a rectangular slot 15 is formed in the bed surface 14 of the bed portion 13 along the rear end of the needle plate 16 behind the needle hole of the needle plate 16, and a rectangular transparent plate 40 is fitted into the slot 15. The long sides of the slot 15 and the transparent plate 40 run along the left-right direction, and the short sides of the slot 15 and the transparent plate 40 run along the front-rear direction. The transparent plate 40 is made of a transparent glass plate or resin plate that transmits light. The workpiece 99 and the stitches sewn thereon pass rearward over the transparent plate 40.

[0023] As shown in FIGS. 2 and 3, the linear image sensor 45, the imaging optical system 50 and the illuminator 60 are disposed inside the bed portion 13 facing the elongated hole 15. The linear image sensor 45 faces the transparent plate 40, separated downward from the sewing workpiece 99 and the transparent plate 40 thereunder. The linear image sensor 45 is housed inside the bed portion 13. A part or the whole of the linear image sensor 45 may be housed in the long hole 15. The linear image sensor 45 extends left and right. The linear image sensor 45 has photoelectric conversion elements arranged in the left and right direction as subpixels for each color, for example, RGB. Here, a combination of R (red), G (green) and B (blue) subpixels is a pixel. The number of pixels of the linear image sensor 45 in the front-rear direction is 1 or 2 or more, and the number of pixels of the linear image sensor 45 in the main left-right direction is sufficiently greater than the number of pixels of the linear image sensor 45 in the front-rear direction. The linear image sensor 45 captures the linear images of the sewing workpiece 99 and the stitching formed by the imaging optical system 50. A linear image refers to an image that is long in the left-right direction, and the number of pixels of a linear image in the left-right direction is sufficiently greater than the number of pixels of a linear image in the front-back direction.

[0024] The imaging optical system 50 is disposed between the transparent plate 40 and the linear image sensor 45. The imaging optical system 50 forms an upright image of the sewing workpiece 99 and the stitches on the transparent plate 40 on the linear image sensor 45 at life-size. The imaging optical system 50 is a rod lens array consisting of a plurality of rod lenses arranged in the left-right direction. One end face of each of these rod lenses faces the transparent plate 40, and the other end face of each of these rod lenses faces the linear image sensor on the transparent plate 40. The rod lens is a refractive index distribution lens, and the refractive index of the rod lens decreases from the central axis of the rod lens toward the outer circumferential surface of the rod lens.

[0025] The illuminator 60 is provided below the transparent plate 40 along the linear image sensor 45 and the imaging optical system 50. The illuminator 60 irradiates light toward the transparent plate 40 and the sewing object 99 to form a bright portion on the sewing object 99. The bright portion extends left and right and is long in the left and right directions. The light emitted by the illuminator 60 is white, but may be any other color. The illuminator 60 may be a color-variable illuminator that can change the light emitted color.

[0026] For example, the illuminator 60 includes a red diode 61, a green diode 62, a blue diode 63, and a light guide 64. The red diode 61, the green diode 62, and the blue diode 63 may be replaced with white diodes.

[0027] The light guide 64 is provided long and horizontally along the linear image sensor 45 and the imaging optical system 50. The incident surface of the light guide 64 faces right or left, and the diodes 61, 62, 63 are disposed opposite the incident surface. The exit surface of the light guide 64 faces the transparent plate 40 and the workpiece 99 above. The light guide 64 takes in the light emitted from the diodes 61, 62, 63 at the incident surface, spreads the light to the left and right, and emits it from the exit surface to the transparent plate 40 and the workpiece 99.

[0028] The light sources of the illuminator 60 are the red diode 61, the green diode 62, and the blue diode 63, but the light sources of the illuminator 60 may be an organic EL element, an inorganic EL element, a discharge tube, or a filament. The optical element of the illuminator 60 is the light guide 64, but the optical element of the illuminator 60 may be a reflector or a lens.

[0029] [7. Controllers, motor drivers, lighting drivers, control circuits and image processing circuits] As shown in FIG. 4, the driver 72 drives the motor 20 according to the command of the controller 70 and adjusts the speed of the motor 20 according to the command of the controller 70 .

[0030] The lighting driver 74 drives the illuminator 60, particularly the diodes 61, 62, 63, as instructed by the controller 70, and adjusts the lighting intensity of the illuminator 60 as instructed by the controller 70. The lighting intensity is a function of the speed of the motor 20, such that the faster the motor 20 speed, the greater the lighting intensity of the illuminator 60.

[0031] The drive circuit 76 drives the linear image sensor 45 in accordance with a command from the controller 70, and causes the linear image sensor 45 to perform an imaging operation at a sampling period in accordance with a command from the controller 70. The sampling period here refers to a period during which the linear image sensor 45 captures one linear image by performing one imaging operation. The sampling period depends on the speed of the motor 20, and the sampling period becomes shorter as the speed of the motor 20 increases. In other words, the sampling period becomes shorter as the feed speed of the sewing workpiece 99 increases.

[0032] The image processing circuit 78 includes, for example, a sample and hold circuit, a black level correction circuit, a multiplex circuit, an amplifier circuit, an AD converter, a digital processing circuit, etc. The image processing circuit 78 performs analog processing and digital processing on the signal of the linear image input from the linear image sensor 45, and outputs the processed digital signal of the linear image to the controller 70.

[0033] The controller 70 includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a memory, and a storage.

[0034] When the controller 70 receives a sewing start command from an input device such as a switch, a push button, a foot switch, or a touch sensor, the controller 70 controls the motor driver 72, which in turn drives the motor 20. As a result, the motor 20 drives the feed dog 21, the needle bar 22, and the thread handling mechanism, and while the workpiece 99 is fed backward by the feed dog 21, a stitch is formed on the workpiece 99 by the sewing needle 23 and the thread handling mechanism.

[0035] During the operation of the motor 20, the controller 70 controls the motor driver 72 and the drive circuit 76 to synchronize the operation of the motor driver 72 with the operation of the drive circuit 76, whereby the drive circuit 76 causes the linear image sensor 45 to perform an image capturing operation at a sampling period corresponding to the speed of the motor 20 during operation, and the controller 70 acquires a linear image captured by the linear image sensor 45 and processed by the image processing circuit 78. During the operation of the motor 20, each time the controller 70 acquires a certain number of linear images from the image processing circuit 78, the controller 70 synthesizes these linear images to generate a planar image. The certain number here means an amount equivalent to one stitch pitch or more, and the planar image includes an image of one stitch pitch or more. One pitch means the distance the sewing workpiece 99 is fed until the sewing needle 23 descends from the uppermost position and returns to the uppermost position. Each time the controller 70 generates a planar image, the controller 70 executes image processing, feature extraction processing, and judgment processing. In the image processing, the controller 70 removes noise from the planar image and removes the background of the planar image to extract the image of the stitching. In the feature extraction processing, the controller 70 extracts feature amounts from the extracted image of the stitching. In the determination processing, the controller 70 calculates a likelihood by comparing the feature amounts of the image of the stitching with the feature amounts of the sample image, and determines whether the image of the stitching matches the sample image based on the likelihood. The sample image refers to an image of a normal stitching that has been prepared in advance. The feature amounts of the sample image are stored in advance in the storage of the controller 70.

[0036] A determination that the stitch image matches the sample image corresponds to a normal determination that the stitch is normal. Such a normal determination causes the controller 70 to continue driving the motor 20 by the motor driver 72. This causes the sewing operation of the sewing machine 1 to continue. On the other hand, a determination that the stitch image does not match the sample image corresponds to an abnormal determination that the stitch is abnormal. Such an abnormal determination causes the controller 70 to stop the operation of the motor driver 72 and the motor 20. This causes the sewing operation of the sewing machine 1 to stop.

[0037] 8. Advantageous Technical Effects (1) The linear image sensor 45 has a small number of pixels in the front-to-rear direction, so the sampling period of the linear image sensor 45 is short. Therefore, even if the linear image sensor 45 captures an image while the sewing workpiece 99 is being fed, and especially if the feeding speed of the sewing workpiece 99 is high, there is little blurring of the subject, and the sewing workpiece 99 and the stitches are clearly captured in the linear image. This allows the normality of the stitches to be inspected appropriately. Since the normality of the stitches is inspected while the sewing workpiece 99 is being fed, i.e., while the sewing workpiece is being sewn, a decrease in sewing productivity can be suppressed.

[0038] (2) The diodes 61, 62, and 63 are used as the light sources of the illuminator 60, so the illuminator 60 is compact. The light guide 64 is used as the optical element of the illuminator 60, so the illuminator 60 is compact. Therefore, the illuminator 60 can be disposed close to the workpiece 99. The proximity of the illuminator 60 to the workpiece 99 contributes to brightly illuminating the workpiece 99, which in turn contributes to shortening the sampling period of the linear image sensor 45. The shorter sampling period of the linear image sensor 45 contributes to increasing the feed speed of the workpiece 99. For these reasons, the illuminator 60 contributes to preventing a decrease in sewing productivity.

[0039] (3) Since the focal length of the imaging optical system 50 is short, the imaging optical system 50 and the linear image sensor 45 can be disposed close to the workpiece 99. In other words, the CIS is compact. Therefore, the CIS does not interfere with the installation of components inside the bed 13.

[0040] (4) When an abnormality occurs in a stitch, the stitch looks almost the same as a normal stitch when viewed above the sewn object 99, but looks very different from a normal stitch when viewed below the sewn object 99. Since the CIS is positioned below the sewn object 99, stitch abnormalities are easily detected. Examples of stitch abnormalities include skipped stitches and lantern stitching. Lantern stitching refers to large loops of thread remaining on the surface of the sewn object 99.

[0041] (5) Since the linear image sensor 45, the imaging optical system 50 and the illuminator 60 are installed inside the bed portion 13, the linear image sensor 45, the imaging optical system 50 and the illuminator 60 do not interfere with the feeding of the sewing workpiece 99.

[0042] (6) Since the upper surface of the transparent plate 40 is flush with the bed surface 14 of the bed portion 13, the transparent plate 40 does not interfere with the feeding of the workpiece 99.

[0043] (7) Since the oblong hole 15 is covered by the transparent plate 40, dust and lint cannot get inside the bed portion 13. The dust and lint are not captured by the linear image sensor 45, and the stitches are not mistakenly determined to be abnormal.

[0044] 9. Variations The present invention is not limited to the above-described embodiment, and may be modified as follows.

[0045] (1) In the above embodiment, the linear image sensor 45, the imaging optical system 50, and the illuminator 60 are disposed below the bed surface 14. Alternatively, the linear image sensor 45, the imaging optical system 50, and the illuminator 60 may be disposed above the bed surface 14. For example, the linear image sensor 45, the imaging optical system 50, and the illuminator 60 are attached to the arm portion 12. The linear image sensor 45 is disposed behind the needle bar 22 and the presser foot 18 and above the bed surface 14. The imaging optical system 50 is disposed behind the needle bar 22 and the presser foot 18 and above the bed surface 14. The imaging optical system 50 is disposed between the bed surface 14 and the linear image sensor 45. The illuminator 60 is provided along the linear image sensor 45 and the imaging optical system 50 below the upper part of the bed surface 14. The illuminator 60 irradiates light toward the bed surface 14 and the sewing object 99 to form a bright portion on the sewing object 99. The workpiece 99 and the stitches applied thereto pass backward between the imaging optical system 50 and the bed surface 14 .

[0046] (2) A trained model that has been deep-learned in advance using training data consisting of a large number of normal sample images may be installed in the controller 70. In this case, the controller 70 inputs a planar image to the trained model, and outputs a determination result from the trained model as to whether or not the image of the stitching shown in the planar image matches the sample image. [Explanation of symbols]

[0047] 1. Sewing machine 21 Feed dog 23 Sewing Needle 40 Transparent plate 45 Linear Image Sensor 50 Imaging Optical System 60 Illumination Equipment 70 Controller

Claims

1. a sewing needle having a hole through which a thread is passed, which passes through the workpiece by descending and comes out of the workpiece by ascending; a feed dog that moves under the workpiece to feed the workpiece backward; a linear image sensor disposed above or below the sewing material behind the sewing needle and extending left and right; an imaging optical system disposed between the workpiece and the linear image sensor for forming an image of the workpiece and a stitch formed thereon on the linear image sensor; a controller that causes the linear image sensor to periodically capture images while the sewing needle is being raised and lowered and while the feed dog is being fed, and that determines the normality of the stitching based on the linear images of the workpiece and the stitching captured periodically by the linear image sensor; A sewing machine equipped with:

2. The controller generates a planar image by synthesizing linear images of the workpiece and the seam periodically captured by the linear image sensor, and judges the normality of the seam based on the planar image.

2. The sewing machine according to claim 1.

3. an illuminator provided along the linear image sensor for illuminating the sewing material and the seam; The sewing machine according to claim 1 or 2, further comprising:

4. a bed portion that supports the sewing workpiece from below, A hole is formed in the bed portion behind the sewing needle, The linear image sensor, the imaging optical system, and the illuminator are disposed inside the bed portion facing the hole.

4. The sewing machine according to claim 3.

5. a bed portion that supports the sewing workpiece from below, A hole is formed in the bed portion behind the sewing needle, The linear image sensor and the imaging optical system are disposed inside the bed portion facing the hole.

3. The sewing machine according to claim 1 or 2.

6. A transparent plate is provided in the hole.

5. The sewing machine according to claim 4.

7. The controller, image processing for removing the background of the planar image and extracting the image of the stitching; a feature extraction process for extracting a feature of the stitch image extracted by the image processing; a determination process for determining whether the stitching image matches a sample image by comparing a feature amount of the stitching image with a feature amount of a normal sample image; Run 3. The sewing machine according to claim 2.

Images