Thread detection device for weaving machine

Abstract

This thread detection device for a weaving machine is used in a weaving machine (10) provided with a weft insertion device (13) that has a main nozzle (14) which inserts a weft (Y) into a warp (T) opening in the left-right direction of a machine base (11), and a plurality of sub nozzles (15) which are arranged along the left-right direction of the machine base (11) and which discharge air with respect to the inserted weft (Y), and a reed (16) that beats the inclined weft (Y) by rocking in the front-rear direction of the machine base (11). The thread detection device for a weaving machine comprises a camera (32) that images an entrance (Tb) or an exit (Tc) of the opening from an imaging direction (C) such that an inclination angle (θc) with respect to the left-right direction of the machine base (1) is 0° < θc < 90°, and a thread detection unit that detects the warp (T) and the weft (Y) from an image captured by the camera (32).

Description

TECHNICAL FIELD

[0001] This invention relates to a yarn detection system for a weaving machine.BACKGROUND ART

[0002] Patent Literature 1 mentions a weft detection device for a weaving machine that includes an image sensor disposed in the front portion of a loom frame of the weaving machine and configured to capture an image rearward. Patent Literature 2 mentions a monitoring device for a weaving machine that includes a camera disposed in the upper portion of a loom frame of the weaving machine and configured to capture an image downward. Patent Literature 3 mentions a defective shed detection device for a weaving machine that includes a camera disposed at one end of a loom frame of the weaving machine and configured to capture an image toward the other end of the loom frame in the right-left direction.CITATION LISTPatent Literature

[0003] Patent Literature 1: Japanese Patent No. 3094457 Patent Literature 2: Japanese Patent No. 6449879 Patent Literature 3: Japanese Patent Application Publication No. 2020-196972 SUMMARY OF INVENTIONTechnical Problem

[0004] Capturing an image from the front portion as in Patent Literature 1 or the upper portion of the loom frame as in Patent Literature 2 allows the travelling state of the weft yarn to be detected. However, the image captured from the front portion or upper portion of the loom frame does not allow the state of the shed of the warp yarns to be detected. In contrast, capturing an image along the right-left direction of the loom frame as in Patent Literature 3 allows the state of the shed of the warp yarns to be detected. However, the captured image shows the weft yarn being inserted in the depth direction of the captured image, so that the captured image does not allow the travelling state of the weft yarn to be detected.Solution to Problem

[0005] A yarn detection system for solving the above problem is used for a weaving machine, the weaving machine including: a weft insertion device that includes a main nozzle for inserting a weft yarn into a shed of warp yarns in a right-left direction of a loom frame and a plurality of sub-nozzles arranged in the right-left direction of the loom frame and configured to eject air onto the weft yarn in the shed of the warp yarns; and a reed configured to swing in a front-rear direction of the loom frame to beat the weft yarn inserted, and the yarn detection system comprises: a camera configured to capture an image of an entrance or an exit of the shed such that a capturing direction of the camera is inclined at an inclination angle represented by θc with respect to the right-left direction of the loom frame, where 0° < θc < 90°; and a yarn detection device configured to detect the warp yarns and the weft yarn in the image captured by the camera.

[0006] According to this configuration, the camera captures an image of the entrance or the exit of the shed such that the capturing direction of the camera is inclined at the inclination angle represented by θc with respect to the right-left direction of the loom frame, where 0° < θc < 90°. This allows the camera to capture both the state of the shed of the warp yarns and the travelling state of the weft yarn. The yarn detection device detects the warp yarns and the weft yarn in the image captured by the camera to detect the state of the shed of the warp yarns and the travelling state of the weft yarn.

[0007] In the yarn detection system for the weaving machine, the camera is located upstream of the reed in a weft insertion direction of the weft yarn, a position of the camera is defined as an origin, an x-axis passes through the origin and extends along the right-left direction of the loom frame, a y-axis passes through the origin and extends along the front-rear direction of the loom frame, a first line and the x-axis form an angle represented by α, wherein the first line passes through the origin and a tip of the main nozzle when the weft yarn inserted reaches a second sub-nozzle of the sub-nozzles from upstream in the weft insertion direction, a second line and the x-axis form an angle represented by β, wherein the second line passes through the origin and a tip of the second sub-nozzle when the weft yarn inserted reaches the second sub-nozzle, a third line and the x-axis form an angle represented by γ, wherein the third line passes through the origin and a corner of fabric woven by the weaving machine where a cloth fell of the fabric intersects an upstream end of the fabric located upstream in the weft insertion direction, a half of an angle of view of the camera is represented by Φ, and the camera is arranged such that α - Φ ≤ θc ≤ β + Φ and γ ≤ β.

[0008] According to this configuration, the camera is located upstream of the reed in the weft insertion direction. The camera is arranged such that α - Φ ≤ θc ≤ β + Φ and γ ≤ β. According to this configuration, when the weft yarn reaches the second sub-nozzle from the upstream in the weft insertion direction, both the tip of the main nozzle and the tip of the second sub-nozzle are located within the field of view of the camera. This allows the camera to capture the travelling state of the weft yarn in the field of view between the tip of the main nozzle and the tip of the second sub-nozzle when the weft yarn reaches the second sub-nozzle.Advantageous Effects of Invention

[0009] The present invention allows both a state of a shed of warp yarns and a travelling state of a weft yarn to be captured.BRIEF DESCRIPTION OF DRAWINGS

[0010] [FIG. 1] FIG. 1 is a plan view of a weaving machine and a camera. [FIG. 2] FIG. 2 is a side view of the weaving machine. [FIG. 3] FIG. 3 is a block diagram of the weaving machine and a yarn detection system. [FIG. 4] FIG. 4 is a diagram showing the correlation between external input signals and trigger signals. [FIG. 5] FIG. 5 is a schematic diagram of a main nozzle and a sub-nozzle when a travelling state of a weft yarn is captured. [FIG. 6] FIG. 6 is a schematic diagram of the main nozzle and the sub-nozzle during beating. DESCRIPTION OF EMBODIMENTS

[0011] The following will describe an embodiment of a yarn detection system for a weaving machine with reference to FIGS. 1 through 6. The yarn detection system is used for a weaving machine. In the following description, the yarn detection system for a weaving machine is simply referred to as a yarn detection system. In the present embodiment, the weaving machine is an air jet loom.<Weaving machine>

[0012] FIG. 1 illustrates a weaving machine 10 that includes a loom frame 11. A plurality of warp yarns T are arranged in the right-left direction of the loom frame 11. The warp yarns T extend in the front-rear direction of the loom frame 11. The warp yarns T are drawn from a supply roll (not illustrated), which is disposed at the rear of the loom frame 11. The warp yarns T are woven into fabric W, and the fabric W is wound onto a take-up roll (not illustrated), which is disposed at the front of the loom frame 11. The warp yarns T move forward in the front-rear direction of the loom frame 11.

[0013] The loom frame 11 includes a harness 12 that is configured to separate the warp yarns T to create a shed. The harness 12 includes, for example, two heddle frames 12a, 12b. The two heddle frames 12a, 12b are arranged in the front-rear direction of the loom frame 11. Each of the heddle frames 12a, 12b includes a plurality of heddles. The heddles are arranged in the right-left direction of the loom frame 11. Of the warp yarns T arranged in the right-left direction of the loom frame 11, some of the warp yarns T are inserted into the heddles of the heddle frame 12a, and the remaining warp yarns T are inserted into the heddles of the heddle frame 12b. The heddle frames 12a, 12b move up and down in the up-down direction of the loom frame 11. When the heddle frame 12a moves upward, the heddle frame 12b moves downward. When the heddle frame 12a moves downward, the heddle frame 12b moves upward. Accordingly, the warp yarns T inserted into the heddles of the heddle frame 12a and the warp yarns T inserted into the heddles of the heddle frame 12b form a shed Ta (see FIG. 2). The shed Ta of the warp yarns T has an entrance Tb and an exit Tc. The entrance Tb is located at the left end of the shed Ta in the right-left direction of the loom frame 11. The exit Tc is located at the right end of the shed Ta in the right-left direction of the loom frame 11.

[0014] The loom frame 11 includes a weft insertion device 13. The weft insertion device 13 includes a main nozzle 14 and a plurality of sub-nozzles 15. The main nozzle 14 is disposed at the left end of the loom frame 11. The main nozzle 14 ejects air to insert a weft yarn Y into the shed Ta of the warp yarns T in the right-left direction of the loom frame 11. The weft yarn Y is inserted into the shed Ta from the entrance Tb. The weft yarn Y travels through the shed Ta in the right-left direction of the loom frame 11, and exits from the exit Tc of the shed Ta. A direction in which the weft yarn Y is inserted by the main nozzle 14 serves as the weft insertion direction. The weft insertion direction is a direction from the left to the right along the right-left direction of the loom frame 11. The sub-nozzles 15 are disposed in front of the harness 12 in the front-rear direction of the loom frame 11. The sub-nozzles 15 are disposed downstream of the main nozzle 14 in the weft insertion direction. The sub-nozzles 15 are arranged in the right-left direction of the loom frame 11. The sub-nozzles 15 eject air onto the weft yarn Y in the shed Ta of the warp yarns T.

[0015] The loom frame 11 includes a reed 16 for beating the weft yarn Y in the shed Ta of the warp yarns T. The reed 16 is disposed between the harness 12 and the sub-nozzles 15 in the front-rear direction of the loom frame 11. The reed 16 is disposed downstream of the main nozzle 14 in the weft insertion direction.

[0016] As illustrated in FIG. 2, the reed 16 includes a plurality of reed dents 17. The reed dents 17 are arranged in the right-left direction of the loom frame 11. Each of the warp yarns T passes a space between the reed dents 17 adjacent to each other in the right-left direction of the loom frame 11. Each of the reed dents 17 has a recess 17a in the front surface of the reed dent 17. The recesses 17a of the reed dents 17 are arranged in the right-left direction of the loom frame 11 to cooperate to form a weft path 16a of the reed 16. When the weft yarn Y is inserted, the weft path 16a is located between the warp yarns T forming the shed Ta. In other words, the weft path 16a is located in the shed Ta of the warp yarns T. The weft yarn Y inserted in the shed Ta of the warp yarns T travels through the weft path 16a.

[0017] The reed 16 is fixed to a sley 18 that is configured to swing back and forth in the front-rear direction of the loom frame 11. Thus, the reed 16 swings back and forth with the sley 18 in the front-rear direction of the loom frame 11. The reed 16 moves to the front side of the loom frame 11 to beat the weft yarn Y in the shed Ta of the warp yarns T. The sley 18 is fixed to the main nozzle 14 and the sub-nozzles 15. That is, when the sley 18 and the reed 16 swing in the front-rear direction of the loom frame 11, the main nozzle 14 and the sub-nozzles 15 also swing in the front-rear direction of the loom frame 11.

[0018] In order to perform weaving, the weaving machine 10 repeatedly performs the shedding operation of the warp yarns T with the harness 12, the weft insertion of the weft yarn Y with the weft insertion device 13, and beating with the reed 16, while moving the warp yarns T forward in the front-rear direction of the loom frame 11.

[0019] As illustrated in FIG. 3, the weaving machine 10 includes a main shaft 19. The main shaft 19 is disposed in the loom frame 11. The main shaft 19 is rotationally driven by a main motor (not illustrated).

[0020] The timing of the weft insertion of the weft yarn Y by the main nozzle 14 corresponds to a rotation angle θ of the main shaft 19. Specifically, the main nozzle 14 ejects the weft yarn Y at a timing when the main shaft 19 rotates by a predetermined angle from a specific angle. In the following description, the specific angle of the main shaft 19 is referred to as a reference angle θ0. An angle delayed from the reference angle θ0 is referred to as a delay angle.

[0021] The weaving machine 10 includes an angle detection device 21 and a signal output device 22. The angle detection device 21 is configured to detect the rotation angle θ of the main shaft 19. The angle detection device 21 is, for example, a rotary encoder. The angle detection device 21 is connected to the signal output device 22. The angle detection device 21 transmits the detected rotation angle θ of the main shaft 19 to the signal output device 22. The signal output device 22 transmits a signal to a yarn detection system 30 every time the rotation angle θ of the main shaft 19 detected by the angle detection device 21 corresponds to the reference angle θ0.<Yarn detection system>

[0022] The yarn detection system 30 includes an imaging device 31. The imaging device 31 includes a camera 32, a light emitting device 33, an input device 34, and a control device 35.

[0023] The camera 32 includes an image sensor. The light emitting device 33 is designed to illuminate a field of view of the camera 32. The light emitting device 33 is, for example, an LED light. The input device 34 is a device operated by a user of the yarn detection system 30 to input to the imaging device 31. The user operates the input device 34 to set a delay angle for capturing. The delay angle for capturing specifies the timing when the camera 32 captures an image.

[0024] The control device 35 includes a processor 35a and a storage unit 35b. Examples of the processor 35a include a central processing unit (CPU), a graphics processing unit (GPU), and a digital signal processor (DSP). Examples of the storage unit 35b include random access memory (RAM) and read only memory (ROM). The storage unit 35b stores program code or instructions for causing the processor 35a to execute the processing. The storage unit 35b, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The control device 35 may include a hardware circuit, such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The control device 35, which is a processing circuit, may include one or more processors operating in accordance with a computer program, one or more hardware circuits, such as ASICs and FPGAs, or combinations thereof.

[0025] The control device 35 is connected to the camera 32. The control device 35 is configured to control the timing at which the camera 32 captures an image. Specifically, the control device 35 outputs a trigger signal to the camera 32. The camera 32 captures an image upon receiving the trigger signal from the control device 35. Thus, the trigger signal is a signal that causes the camera 32 to capture an image.

[0026] The control device 35 is connected to the light emitting device 33. The control device 35 is configured to control the timing at which the light emitting device 33 emits light. Specifically, the control device 35 outputs a trigger signal to the light emitting device 33. The light emitting device 33 emits light upon receiving the trigger signal from the control device 35. Thus, the trigger signal is a signal that causes the light emitting device 33 to emit light. The control device 35 outputs the trigger signal to the light emitting device 33 at the same time the control device 35 outputs the trigger signal to the camera 32. Accordingly, the light emitting device 33 emits light at the same time the camera 32 captures an image.

[0027] The control device 35 is connected to the input device 34. The control device 35 obtains the delay angle for capturing set by the user operating the input device 34.

[0028] The control device 35 is connected to the signal output device 22 of the weaving machine 10. The signal output device 22 outputs a signal, which serves an external input signal, to the control device 35. In this way, the control device 35 detects the timing at which the rotation angle θ of the main shaft 19 corresponds to the reference angle θ0.

[0029] The control device 35 outputs the trigger signals to the camera 32 and the light emitting device 33 based on the external input signal from the signal output device 22 of the weaving machine 10 and the delay angle for capturing from the input device 34. Specifically, the control device 35 outputs the trigger signals to the camera 32 and the light emitting device 33 at the timing when the main shaft 19 rotates by the delay angle for capturing from the reference angle θ0. Accordingly, the camera 32 captures an image at the timing when the main shaft 19 rotates by the delay angle for capturing from the reference angle θ0. The light emitting device 33 emits light at the timing when the main shaft 19 rotates by the delay angle for capturing from the reference angle θ0.

[0030] As illustrated in FIG. 1, the camera 32 is disposed at one end of the loom frame 11 in the right-left direction. The camera 32 is located forward of the main nozzle 14 in the front-rear direction of the loom frame 11. The camera 32 is located at the same height as the weft path 16a in the up-down direction of the loom frame 11. The camera 32 is arranged such that a capturing direction C is inclined with respect to the right-left direction of the loom frame 11. The capturing direction C of the camera 32 is the direction in which the optical axis of the camera 32 extends. The camera 32 captures an image of the entrance Tb of the shed Ta such that the capturing direction C of the camera 32 is inclined at an inclination angle θc with respect to the right-left direction of the loom frame 11, where 0° < θc < 90°. The camera 32 captures an image of the entrance Tb of the shed Ta from one side to the other side along the right-left direction of the loom frame 11 and rearward along the front-rear direction of the loom frame 11. The camera 32 captures a state of the shed of the warp yarns T and a travelling state of the weft yarn Y.

[0031] As illustrated in FIG. 3, the yarn detection system 30 includes a yarn detection device 36. The yarn detection device 36 includes a processor 36a and a storage unit 36b. Examples of the processor 36a include a central processing unit (CPU), a graphics processing unit (GPU), and a digital signal processor (DSP). Examples of the storage unit 36b include random access memory (RAM) and read only memory (ROM). The storage unit 36b stores program code or instructions for causing the processor 36a to execute the processing. The storage unit 36b, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The yarn detection device 36 may include a hardware circuit, such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The yarn detection device 36, which is a processing circuit, may include one or more processors operating in accordance with a computer program, one or more hardware circuits, such as ASICs and FPGAs, or combinations thereof.

[0032] The yarn detection device 36 is connected to the camera 32 of the imaging device 31. The yarn detection device 36 acquires the image captured by the camera 32. The yarn detection device 36 detects the warp yarns T and the weft yarn Y in the acquired image. As described above, the camera 32 captures both the state of the shed of the warp yarns T and the travelling state of the weft yarn Y. Accordingly, the yarn detection device 36 is configured to detect the warp yarns T and the weft yarn Y in the image captured by the camera 32 to detect the state of the shed of the warp yarns T and the travelling state of the weft yarn Y.<Examples of yarn detection system>

[0033] According to the present embodiment, the yarn detection system 30 detects the state of the shed of the warp yarns T before the insertion of the weft yarn Y. Then, it is detected whether the shed of the warp yarns T is defective based on the state of the shed of the warp yarns T detected by the yarn detection system 30. The defective shed of the warp yarns T means that some of the warp yarns T are located in the weft path 16a. The defective shed of the warp yarns T may cause the inserted weft yarn Y to interfere with the warp yarns T located in the weft path 16a, and therefore may cause a weft insertion failure.

[0034] According to the present embodiment, the yarn detection system 30 detects the travelling state of the weft yarn Y when the weft yarn Y reaches a second sub-nozzle 152 of the sub-nozzles 15, which are arranged in the weft insertion direction, from the upstream in the weft insertion direction. Based on the travelling state of the weft yarn Y detected by the yarn detection system 30, the shape of the leading end of the weft yarn Y and the position of the weft yarn Y relative to the weft path 16a are inspected. If the leading end of the weft yarn Y is extremely bent or if the weft yarn Y is out of the weft path 16a, a weft insertion failure is likely to occur. Accordingly, it is inspected to ensure that the leading end of the weft yarn Y is not extremely bent and that the weft yarn Y is in the weft path 16a.

[0035] In particular, it is known that more air leaks forward along the weft path 16a in the vicinity of the second sub-nozzle 152 than in the vicinity of a first sub-nozzle 15 from the upstream in the weft insertion direction. Accordingly, the travelling state of the weft yarn Y may become unstable in the vicinity of the second sub-nozzle 152 from the upstream in the weft insertion direction. In the present embodiment, the shape of the leading end of the weft yarn Y and the position of the weft yarn Y relative to the weft path 16a are therefore inspected based on the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152.

[0036] In order for the yarn detection system 30 to detect the state of the shed of the warp yarns T before the insertion of the weft yarn Y, the camera 32 needs to capture the state of the shed of the warp yarns T before the insertion of the weft yarn Y. In order for the yarn detection system 30 to detect the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152, the camera 32 needs to capture an image of the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152.

[0037] The user sets the delay angle for capturing so that the camera 32 captures the state of the shed of the warp yarns T before the insertion of the weft yarn Y and the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152. The timing of the insertion of the weft yarn Y is different from the timing at which the weft yarn Y reaches the second sub-nozzle 152. Accordingly, the user sets delay angles for capturing: a delay angle θt for capturing the state of the shed of the warp yarns T before the insertion of the weft yarn Y; and a delay angle θy for capturing the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152.

[0038] The main nozzle 14 inserts the weft yarn Y at the timing when the main shaft 19 rotates by a first delay angle θ1 from the reference angle θ0. The inserted weft yarn Y reaches the most upstream warp yarn T of the warp yarns T arranged in the weft insertion direction at the timing when the main shaft 19 rotates by a second delay angle θ2 from the reference angle θ0. The reed 16 performs beating at the timing when the main shaft 19 rotates by a third delay angle θ3 from the reference angle θ0.

[0039] The delay angle θt for capturing the warp yarns is set to an angle smaller than the first delay angle θ1. The delay angle θt for capturing the warp yarns is set, for example, to an angle obtained by subtracting a predetermined angle θa from the second delay angle θ2.

[0040] As illustrated in FIG. 4, the control device 35 outputs a trigger signal to the camera 32 at the timing when the main shaft 19 rotates by the delay angle θt for capturing the image of the warp yarns from the reference angle θ0. This allows the camera 32 to capture an image of the shed before the insertion of the weft yarn Y.

[0041] The delay angle θy for capturing the image of the weft yarn is set to an angle greater than the second delay angle θ2. The delay angle θy for capturing the image of the weft yarn is set, for example, to an angle obtained by adding a predetermined angle θb to the second delay angle θ2. The delay angle θy for capturing the image of the weft yarn is smaller than the third delay angle θ3.

[0042] The control device 35 outputs a trigger signal to the camera 32 at the timing when the main shaft 19 rotates by the delay angle θy for capturing the image of the weft yarn from the reference angle θ0. This allows the camera 32 to capture an image of the weft yarn Y at the timing when the weft yarn Y reaches the second sub-nozzle 152.

[0043] The camera 32 is arranged on the loom frame 11 so that the camera 32 captures the state of the shed of the warp yarns T before the insertion of the weft yarn Y and the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152. Specifically, the camera 32 is disposed at the end of the loom frame 11 adjacent to the main nozzle 14 in the right-left direction, i.e., the left end of the loom frame 11. The camera 32 is located upstream of the reed 16 in the weft insertion direction. The camera 32 captures an image of the entrance Tb of the shed Ta such that the capturing direction C of the camera 32 is inclined at the inclination angle θc with respect to the right-left direction of the loom frame 11, where 0° < θc < 90°. The camera 32 captures an image of the entrance Tb of the shed Ta downstream along the weft insertion direction and rearward along the front-rear direction of the loom frame 11.

[0044] When the camera 32 captures the state of the shed of the warp yarns T before the weft insertion, a tip 14a of the main nozzle 14 needs to be located within the field of view of the camera 32. When the camera 32 captures the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152, the tip 14a of the main nozzle 14 and a tip 152a of the second sub-nozzle 152 need to be located within the field of view of the camera 32.

[0045] FIG. 5 is a plan view showing the positions of the main nozzle 14 and the second sub-nozzle 152 when the travelling state of the weft yarn Y is captured, i.e., when the inserted weft yarn Y reaches the second sub-nozzle 152. FIG. 6 is a plan view showing the positions of the main nozzle 14 and the second sub-nozzle 152 during beating. In FIGS. 5 and 6, the position of the camera 32 is defined as the origin O. The x-axis passes through the origin O and extends along the right-left direction of the loom frame 11. The direction from left to right of the loom frame 11 corresponds to the positive direction of the x-axis. The y-axis passes through the origin O and extends along the front-rear direction of the loom frame 11. The direction from front to rear of the loom frame 11 corresponds to the positive direction of the y-axis.

[0046] As illustrated in FIG. 5, the coordinates of the tip 14a of the main nozzle 14 when the travelling state of the weft yarn Y is captured are represented as (x1, y1). The coordinates of the tip 152a of the second sub-nozzle 152 when the travelling state of the weft yarn Y is captured are represented as (x2, y2). The coordinates of a corner Wa of the fabric W where a cloth fell W1 of the fabric W intersects an upstream end W2 of the fabric W located upstream in the weft insertion direction are represented as (x3, y3).

[0047] Due to the structure of the weaving machine 10, the upstream end W2 of the fabric W is located downstream of the tip 14a of the main nozzle 14 in the weft insertion direction. The tip 152a of the second sub-nozzle 152 is located downstream of the upstream end W2 of the fabric W in the weft insertion direction. Accordingly, the positional relationship of the tip 14a of the main nozzle 14, the tip 152a of the second sub-nozzle 152, and the corner Wa of the fabric W in the x-axis direction satisfies x1 < x3 < x2.

[0048] Due to the structure of the weaving machine 10, the tip 152a of the second sub-nozzle 152 is located forward of the main nozzle 14 in the front-rear direction of the loom frame 11. When the travelling state of the weft yarn Y is captured, the cloth fell W1 of the fabric W is located forward of the second sub-nozzle 152 in the front-rear direction of the loom frame 11. Accordingly, the positional relationship of the tip 14a of the main nozzle 14, the tip 152a of the second sub-nozzle 152, and the corner Wa of the fabric W in the y-axis direction satisfies y3 < y2 < y1.

[0049] A first line L1, which passes through the origin O and the tip 14a of the main nozzle 14 when the travelling state of the weft yarn Y is captured, and the x-axis form an angle represented by α. It is expressed by α = tan -1< (y1 / x1). A second line L2, which passes through the origin O and the tip 152a of the second sub-nozzle 152 when the travelling state of the weft yarn Y is captured, and the x-axis form an angle represented by β. It is expressed by β = tan -1< (y2 / x2). A third line L3, which passes through the origin O and the corner Wa of the fabric W, and the x-axis form an angle represented by γ. It is expressed by γ = tan -1< (y3 / x3).

[0050] The half of the angle of view of the camera 32 is represented by Φ. In other words, the angle of view of the camera 32 is represented by 2Φ. As previously mentioned, the capturing direction C of the camera 32 is inclined with respect to the right-left direction of the loom frame 11, i.e., the x-axis. The capturing direction C of the camera 32 is inclined at the inclination angle θc with respect to the x-axis.

[0051] When α ≤ θc + Φ is satisfied, the tip 14a of the main nozzle 14 is located within the field of view of the camera 32. When θc - Φ ≤ β is satisfied, the tip 152a of the second sub-nozzle 152 is located within the field of view of the camera 32. Accordingly, when α - Φ ≤ θc ≤ β + Φ is satisfied, both the tip 14a of the main nozzle 14 and the tip 152a of the second sub-nozzle 152 are located within the field of view of the camera 32. When γ ≤ β is satisfied, the tip 152a of the second sub-nozzle 152 is not hidden by the fabric W.

[0052] Based on the above description, the camera 32 according to the present embodiment is arranged such that α - Φ ≤ θc ≤ β + Φ and γ ≤ β. This allows the camera 32 to capture the travelling state of the weft yarn Y in a field of view between the tip 14a of the main nozzle 14 and the tip 152a of the second sub-nozzle 152 when the weft yarn Y reaches the second sub-nozzle 152.

[0053] The position of the main nozzle 14 before the insertion of the weft yarn Y is further forward in the front-rear direction of the loom frame 11 than the position of the main nozzle 14 when the weft yarn Y reaches the second sub-nozzle 152. This allows the camera 32 to capture the image of the tip 14a of the main nozzle 14 when the camera 32 captures the state of the shed of the warp yarns T before the weft insertion.

[0054] As illustrated in FIG. 6, the coordinates of the tip 14a of the main nozzle 14 during beating are represented as (x10, y10). The coordinates of the tip 152a of the second sub-nozzle 152 during beating are represented as (x20, y20). Since the position of the fabric W remains unchanged, the coordinates of the corner Wa of the fabric W during beating are (x3, y3), which are the same as the coordinates of the corner Wa of the fabric W when the travelling state of the weft yarn Y is captured.

[0055] During beating, the main nozzle 14 and the second sub-nozzle 152 move in the front-rear direction of the loom frame 11, but do not move in the right-left direction of the loom frame 11. Accordingly, in the x-axis direction, the positions of the tip 14a of the main nozzle 14 and the tip 152a of the second sub-nozzle 152 during beating are the same as the positions of the tip 14a of the main nozzle 14 and the tip 152a of the second sub-nozzle 152 when the travelling state of the weft yarn Y is captured, respectively. Accordingly, x1 is equal to x10, and x2 is equal to x20. During beating, the positional relationship of the tip 14a of the main nozzle 14, the tip 152a of the second sub-nozzle 152, and the corner Wa of the fabric W in the x-axis direction satisfies x10 < x3 < x20.

[0056] During beating, the main nozzle 14 and the second sub-nozzle 152 move forward in the front-rear direction of the loom frame 11. The tip 14a of the main nozzle 14 is located forward of the cloth fell W1 of the fabric W in the front-rear direction of the loom frame 11. As previously mentioned, due to the structure of the weaving machine 10, the tip 152a of the second sub-nozzle 152 is located forward of the tip 14a of the main nozzle 14 in the front-rear direction of the loom frame 11. Accordingly, during beating, the positional relationship of the tip 14a of the main nozzle 14, the tip 152a of the second sub-nozzle 152, and the corner Wa of the fabric W in the y-axis direction satisfies y20 < y10 < y3.

[0057] A part 20 attached to the main nozzle 14 swings with the main nozzle 14 in the front-rear direction of the loom frame 11. The position of a front end 20a of the part 20 in the y-axis direction is represented by D. The position D needs to satisfy D > 0 to prevent the part 20 from interfering with the camera 32 during beating.[Operation and effects of embodiment]

[0058] The following will describe the operation and effects of the present embodiment. (1) The yarn detection system 30 includes the camera 32 and the yarn detection device 36. The camera 32 captures an image of the entrance Tb of the shed Ta such that the capturing direction C of the camera 32 is inclined at the inclination angle represented by θc with respect to the right-left direction of the loom frame 11, where 0° < θc < 90°. This allows the camera 32 to capture both the state of the shed of the warp yarns T and the travelling state of the weft yarn Y. The yarn detection device 36 detects the warp yarns T and the weft yarn Y in the image captured by the camera 32 to detect the state of the shed of the warp yarns T and the travelling state of the weft yarn Y. (2) The camera 32 according to the present embodiment is located upstream of the reed 16 in the weft insertion direction. The camera 32 is arranged such that α - Φ ≤ θc ≤ β + Φ and γ ≤ β. According to this configuration, when the weft yarn Y reaches the second sub-nozzle 152 from the upstream in the weft insertion direction, both the tip 14a of the main nozzle 14 and the tip 152a of the second sub-nozzle 152 are located within the field of view of the camera 32. This allows the camera 32 to capture the travelling state of the weft yarn Y in the field of view between the tip 14a of the main nozzle 14 and the tip 152a of the second sub-nozzle 152 when the weft yarn Y reaches the second sub-nozzle 152. The position of the main nozzle 14 before the insertion of the weft yarn Y is further forward in the front-rear direction of the loom frame 11 than the position of the main nozzle 14 when the weft yarn Y reaches the second sub-nozzle 152. This allows the camera 32 to capture the image of the tip 14a of the main nozzle 14 when the camera 32 captures the state of the shed of the warp yarns T before the weft insertion. (3) For example, when the camera 32 captures an image along the right-left direction of the loom frame 11, the state of the shed of the warp yarns T is detected based on the captured image. However, the image shows the warp yarns T arranged in the depth direction of the image, so that it is difficult to detect the position of defective shed of the warp yarns T, which may occur, in the right-left direction of the loom frame 11. In contrast, according to the present embodiment, the camera 32 is arranged such that the capturing direction C is inclined with respect to the right-left direction of the loom frame 11. This not only allows the state of the shed of the warp yarns T to be detected based on the captured image, but also allows the position of defective shed of the warp yarns T, which may occur, in the right-left direction of the loom frame 11 to be detected. [Modification example]

[0059] The embodiment of the present invention may be modified in various manners, as exemplified below. The present embodiment and the following modification examples may be combined within the scope of the present invention. o The imaging device 31 may not necessarily include the light emitting device 33. o The imaging device 31 may not necessarily include the input device 34. For example, the user may use a communication device, which is configured to communicate with the imaging device 31, to set the delay angle for capturing in the imaging device 31. o According to the present embodiment, the yarn detection system 30 detects the state of the shed of the warp yarns T before the insertion of the weft yarn Y and the travelling state of the weft yarn Y when the weft yarn Y reaches the second sub-nozzle 152, but the present invention is not limited thereto. The yarn detection system 30 may, for example, detect the state of the shed of the warp yarns T and the travelling state of the weft yarn Y when the leading end of the weft yarn Y has finished passing through the shed Ta of the weft yarns T.

[0060] In this case, the camera 32 is disposed at the other end of the loom frame 11 distant from the main nozzle 14 in the right-left direction with the reed 16 disposed between both ends of the loom frame 11, i.e., the right end of the loom frame 11. The camera 32 is disposed downstream of the reed 16 in the weft insertion direction. The camera 32 captures an image of the exit Tc of the shed Ta such that the capturing direction C of the camera 32 is inclined at the inclination angle represented by θc with respect to the right-left direction of the loom frame 11, where 0° < θc < 90°. The camera 32 captures an image of the exit Tc of the shed Ta upstream along the weft insertion direction and rearward along the front-rear direction of the loom frame 11.

[0061] The leading end of the weft yarn Y finishes passing through the shed Ta of the warp yarns T at the timing when the main shaft 19 rotates by a fourth delay angle θ4 from the reference angle θ0. The user sets the fourth delay angle θ4 as the delay angle for capturing. The camera 32 captures an image at the timing when the leading end of the weft yarn Y has finished passing through the shed Ta of the warp yarns T.

[0062] The camera 32 is arranged and the delay angle for capturing is set as previously mentioned, and the camera 32 captures both the state of the shed of the warp yarns T and the travelling state of the weft yarn Y when the leading end of the weft yarn Y has finished passing through the shed Ta of the warp yarns T. The yarn detection device 36 detects the warp yarns T and the weft yarn Y in the image captured by the camera 32 to detect the state of the shed of the warp yarns T and the travelling state of the weft yarn Y when the leading end of the weft yarn Y has finished passing through the shed Ta of the warp yarns T.

[0063] Based on the state of the shed of the warp yarns T when the leading end of the weft yarn Y has finished passing through the shed Ta of the warp yarns T, it is inspected whether the shed Ta of the warp yarns T is not closed before the leading end of the weft yarn Y has finished passing through the shed Ta of the warp yarns T. Based on the travelling state of the weft yarn Y when the leading end of the weft yarn Y has finished passing through the shed Ta of the warp yarns T, the shape of the leading end of the weft yarn Y and the position of the weft yarn Y relative to the weft path 16a are inspected.REFERENCE SIGNS LIST

[0064] 10 weaving machine 11 loom frame 13 weft insertion device 14 main nozzle 14a tip 15 sub-nozzle 152 second sub-nozzle 152a tip 16 reed 30 yarn detection system for weaving machine 32 camera 36 yarn detection device C capturing direction L1 first line L2 second line L3 third line O origin T warp yarn Ta shed Tb entrance Tc exit W fabric W1 cloth fell W2 upstream end Wa corner Y weft yarn θc inclination angle

Claims

1. A yarn detection system for a weaving machine, the weaving machine including: a weft insertion device that includes a main nozzle for inserting a weft yarn into a shed of warp yarns in a right-left direction of a loom frame and a plurality of sub-nozzles arranged in the right-left direction of the loom frame and configured to eject air onto the weft yarn in the shed of the warp yarns; and a reed configured to swing in a front-rear direction of the loom frame to beat the weft yarn inserted, the yarn detection system comprising: a camera configured to capture an image of an entrance or an exit of the shed such that a capturing direction of the camera is inclined at an inclination angle represented by θc with respect to the right-left direction of the loom frame, where 0° < θc < 90°; and a yarn detection device configured to detect the warp yarns and the weft yarn in the image captured by the camera.

2. The yarn detection system for the weaving machine according to claim 1, characterized in that the camera is located upstream of the reed in a weft insertion direction of the weft yarn, a position of the camera is defined as an origin, an x-axis passes through the origin and extends along the right-left direction of the loom frame, a y-axis passes through the origin and extends along the front-rear direction of the loom frame, a first line and the x-axis form an angle represented by α, wherein the first line passes through the origin and a tip of the main nozzle when the weft yarn inserted reaches a second sub-nozzle of the sub-nozzles from upstream in the weft insertion direction, a second line and the x-axis form an angle represented by β, wherein the second line passes through the origin and a tip of the second sub-nozzle when the weft yarn inserted reaches the second sub-nozzle, a third line and the x-axis form an angle represented by γ, wherein the third line passes through the origin and a corner of fabric woven by the weaving machine where a cloth fell of the fabric intersects an upstream end of the fabric located upstream in the weft insertion direction, a half of an angle of view of the camera is represented by Φ, and the camera is arranged such that α - Φ ≤ θc ≤ β + Φ and γ ≤ β.

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