-
The present invention relates to a weft yarn detection device for an air jet loom.
BACKGROUND ART
-
An air jet loom includes an optical weft yarn detection device to determine whether or not a weft yarn has been inserted appropriately. The weft yarn detection device is mounted on a sley, and includes a light projection unit that projects light toward the weft yarn inserted and a light receiving unit that receives light reflected by the weft yarn. In the weft yarn detection device, the light projection unit is a part formed of a light projection element, and the light receiving unit is a part formed of a light reception element.
-
When a weft yarn reaches a projection area to which light is projected by the light projection unit, the light receiving unit receives reflection light and converts the reflection light to an electrical signal, which is then sent to a controller of the air jet loom. On the other hand, when the weft yarn does not reach the projection area of the light projection unit, an electrical signal related to the reflection light from the weft yarn is not sent from the light receiving unit to the controller. In this case, the controller of the air jet loom determines that a weft insertion failure has occurred and stops operation of the air jet loom.
-
For example,
Japanese Patent Application Publication No. 2018-168490 discloses an air jet loom that is equipped with a contrast adjuster in order to improve the detection efficiency of the weft yarn detection device. The contrast adjuster is disposed between the reed dents adjacent to each other in the weft insertion direction. The contrast adjuster extends longitudinally in a longitudinal direction of the reed dents and has an inverted L-shape as viewed in the weft insertion direction.
-
In a weft yarn detection device, when reflected light is received from portions other than the weft yarn, and the amount of the reflected light varies depending on the reflecting portions, such variation may reduce the accuracy of weft yarn detection.
SUMMARY
-
In accordance with an aspect of the present invention , there is provided a weft yarn detection device for an air jet loom, the air jet loom including a reed in which a plurality of reed dents each having a guide recess is arranged in a row in a weft insertion direction, wherein a weft yarn is inserted through a reed passage formed by a plurality of the guide recesses by air injection. The weft yarn detection device includes a weft yarn sensor disposed so that a sensor end portion of the weft yarn sensor faces the reed passage, and including a light projection unit configured to project light toward the reed passage, and a light receiving unit configured to receive the light in the sensor end portion, and a reflective member disposed between the reed dents disposed side by side in the weft insertion direction at a position where the light is projected from the light projection unit though the reed passage, and having an arcuate surface reflecting the light toward the light receiving unit. The arcuate surface is recessed in a direction away from the light projection unit, as viewed in the weft insertion direction.
-
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention .
BRIEF DESCRIPTION OF THE DRAWINGS
-
The invention , together with objects and advantages thereof, may best be understood by reference to the following description of the embodiments together with the accompanying drawings in which:
- FIG. 1 is a schematic perspective view illustrating an air jet loom and a weft yarn detection device;
- FIG. 2 is an enlarged perspective view illustrating a reed, a vibration suppression member, and a reflective member;
- FIG. 3 is a cross-sectional view illustrating the reed and the weft yarn detection device;
- FIG. 4 is a perspective view illustrating the vibration suppression member and the reflective member;
- FIG. 5 is a partial side view illustrating the weft yarn detection device;
- FIG. 6 is an enlarged perspective view illustrating a reed, a vibration suppression member, and a reflective member according to a modification; and
- FIG. 7 is a partial side view illustrating a weft yarn detection device according to the modification.
DETAILED DESCRIPTION OF THE EMBODIMENTS
-
Hereinafter, an embodiment of a weft yarn detection device for an air jet loom will be described.
Overall view of air jet loom
-
As illustrated in FIG. 1, an air jet loom 10 includes a main nozzle 11, a plurality of sub-nozzles 12, a reed 13, a sley 14, and a vibration suppression member 20. The main nozzle 11, the sub-nozzles 12, and the reed 13 each are fixed to the sley 14. The vibration suppression member 20 is attached to the reed 13. The air jet loom 10 weaves fabric C using weft yarns Y and warp yarns T.
-
The main nozzle 11 is fixed to one end of the sley 14 in a longitudinal direction thereof. A weft yarn Y is ejected from the main nozzle 11 along the longitudinal direction of the sley 14. In the present embodiment, the weft yarn Y is a spun yarn. The weft yarn Y does not have to be a spun yarn.
-
In the following, a direction in which the weft yarn Y travels by the main nozzle 11 will be referred to as a weft insertion direction X. In addition, in the weft insertion direction X, a side to which the weft yarn Y travels is referred to as a "downstream", and a side opposite to the downstream in the weft insertion direction X is referred to as an "upstream". That is, the weft insertion direction X is a direction from the upstream to the downstream. The weft insertion direction X coincides with the longitudinal direction of the sley 14. The weft yarn Y travels from the upstream to the downstream by the main nozzle 11.
-
The sub-nozzles 12 are arranged in a row in the weft insertion direction X on the sley 14. The sub-nozzles 12 each have a base end attached to the sley 14 so that its position in the weft insertion direction X can be adjusted. The sub-nozzles 12 each have an air discharge port (not illustrated) at its tip end. The sub-nozzles 12 are configured to discharge air from the air discharge port. The air is supplied to the sub-nozzles 12 through a pipe 12 a connected to the base ends of the sub-nozzles 12.
-
The reed 13 includes two holding members 13a and a plurality of reed dents 15. The two holding members 13a each have a columnar shape extending in the weft insertion direction X. The reed dents 15 are held by the two holding members 13a. The reed dents 15 each have a long plate shape. Opposite ends of each of the reed dents 15 in the longitudinal direction thereof are connected to the holding members 13a. In other words, the reed dents 15 are connected to the holding members 13a on the opposite ends in the longitudinal direction. That is, in the reed 13, the reed dents 15 are fixed to the holding members 13a so that the longitudinal direction of the reed dents 15 extends perpendicular to the weft insertion direction X. In the reed 13, the reed dents 15 are arranged in a row in the weft insertion direction X at regular intervals in a thickness direction of the reed dents 15. That is, the air jet loom 10 includes the reed 13 in which a plurality of reed dents 15 is arranged in a row in the weft insertion direction X. The reed dents 15 are disposed on the sley 14 with their thickness directions coinciding with the weft insertion direction X.
-
One of the two holding members 13a is disposed in a groove formed in the sley 14. The reed dents 15 stand upright on the sley 14. In the following, one of the opposite ends of each of the reed dents 15 in the longitudinal direction thereof closer to the sley 14 will be referred to as a base end, and the other end of each of the reed dents 15 opposite from the base end will be referred to as a tip end. That is, the reed dents 15 each have the base end connected to the sley 14 and the tip end opposite from the base end in the longitudinal direction.
-
As illustrated in FIGS. 2 and 3, the reed dents 15 each have a guide recess 15a. The reed dents 15 each are opened to an opening direction A at the guide recess 15a. In other words, the guide recess 15a is opened to the opening direction A. The opening direction A is perpendicular to the weft insertion direction X in a plan view from the weft insertion direction X and is a direction from the reed dents 15 toward the sub-nozzles 12 in FIG. 1.
-
In the present embodiment, the opening direction A is a direction perpendicular to the longitudinal direction and the thickness direction of the reed dents 15. It is noted that the opening direction A does not have to be perpendicular to the longitudinal direction of the reed dents 15. For example, the opening direction A may be a direction slightly inclined with respect to the longitudinal direction of the reed dents 15 and perpendicular to the thickness direction of the reed dents 15. The opening direction A may be any direction in which the guide recess 15a is opened so that air is discharged from the air discharge ports of the sub-nozzles 12 in FIG. 1 into a reed passage 13b, which will be described later.
-
The reed dents 15 each have a first passage forming surface 151, a second passage forming surface 152, and a third passage forming surface 153 as surfaces forming the guide recess 15a. The first passage forming surface 151 is a surface that extends in the longitudinal direction of each of the reed dents 15, of the surfaces forming the guide recess 15a. The first passage forming surface 151 faces the opening direction A of the guide recess 15a. The second passage forming surface 152 is a surface that is continuous with the first passage forming surface 151 and is closer to the tip end of each of the reed dents 15. The third passage forming surface 153 is a surface that is continuous with the first passage forming surface 151 and is closer to the base end of each of the reed dents 15. The second passage forming surface 152 faces the third passage forming surface 153 in the longitudinal direction of the reed dents 15.
-
The reed dents 15 each have a first connecting surface 154 that connects the first passage forming surface 151 to the second passage forming surface 152. The first connecting surface 154 is curved and connects the first passage forming surface 151 to the second passage forming surface 152. The reed dents 15 each have a second connecting surface 155 that connects the first passage forming surface 151 to the third passage forming surface 153. The second connecting surface 155 is curved and connects the first passage forming surface 151 to the third passage forming surface 153. As described above, the guide recess 15a is a portion of each of the reed dents 15, the portion being formed by the first passage forming surface 151, the second passage forming surface 152, the third passage forming surface 153, the first connecting surface 154, and the second connecting surface 155.
-
The reed 13 has the reed passage 13b. The reed passage 13b is formed by arranging a plurality of guide recesses 15a in the weft insertion direction X. In other words, the reed passage 13b is formed by the plurality of guide recesses 15a. Therefore, it can be said that the first passage forming surface 151, the second passage forming surface 152, the third passage forming surface 153, the first connecting surface 154, and the second connecting surface 155 of each of the reed dents 15 form the reed passage 13b. In the reed 13, the guide recesses 15a are arranged in a row such that the direction in which the reed passage 13b is opened corresponds to the opening direction A, as viewed in the weft insertion direction X. In other words, it can be said that the reed passage 13b is opened in the opening direction A of the guide recesses 15a.
-
The reed 13 and the sub-nozzles 12 are arranged in the opening direction A. The sub-nozzles 12 are disposed at positions where air is dischargeable from tip portions of the sub-nozzles 12 toward the reed passage 13b.
-
As illustrated in FIGS. 1 and 3, in the air jet loom 10, a plurality of warp yarns T passes through gaps formed by two adjacent reed dents 15 of the reed 13. When passing through the reed 13, the warp yarns T are divided into warp yarns T that pass through portions of the reed dents 15 closer to the tip ends thereof than the weft yarn Y, and warp yarns T that pass through portions of the reed dents 15 closer to the base ends thereof than the weft yarn Y.
-
As illustrated in FIGS. 2 and 3, the vibration suppression member 20 is disposed in a downstream portion of the reed 13. The vibration suppression member 20 has a long plate shape extending in the longitudinal direction of the reed dents 15. The vibration suppression member 20 has a hook portion 21 at one end of the vibration suppression member 20, which is hooked onto the other of the holding members 13a that is disposed adjacent to the tip ends of the reed dents 15. The vibration suppression member 20 is fixed to the reed 13 by fixing the hook portion 21 to the holding members 13a with bolts 22.
-
The vibration suppression member 20 has a vibration damping member 23 at a portion of the vibration suppression member 20, the portion being close to the other end opposite from the hook portion 21. The vibration damping member 23 is an elastic member. The vibration damping member 23 has a long plate shape extending in a longitudinal direction of the vibration suppression member 20. The vibration suppression member 20 presses the vibration damping member 23 against the reed dents 15. The vibration suppression member 20 presses the vibration damping member 23 against the reed dents 15 from a side of the reed 13 that does not face the sub-nozzles 12. A reflective member 40, which will be described later, is attached to the vibration suppression member 20. The reflective member 40 is attached to the vibration damping member 23.
-
As illustrated in FIG. 1, the air jet loom 10 causes the main nozzle 11 to discharge a weft yarn Y toward the reed passage 13b. The discharged weft yarn Y travels in the weft insertion direction X through the reed passage 13b by relay air injection from the sub-nozzles 12. The air jet loom 10 performs weft insertion of the weft yarn Y through the reed passage 13b by air injection. After the weft yarn Y travels through the reed passage 13b, the air jet loom 10 causes the sley 14 to swing to beat the weft yarn Y. Accordingly, the air jet loom 10 weaves a woven fabric C with the weft yarns Y and the warp yarns T. Vibration of the reed dents 15 during beating is absorbed by the vibration damping member 23.
Weft yarn detection device
-
As illustrated in FIG. 1, the air jet loom 10 includes a weft yarn detection device 30. As illustrated in FIGS. 3 and 5, the weft yarn detection device 30 includes a weft yarn sensor 31 and the reflective member 40.
-
As illustrated in FIGS. 1 and 3, the weft yarn sensor 31 is fixed to the sley 14. The weft yarn sensor 31 is disposed in a downstream portion of the sley 14 and aligned with the plurality of sub-nozzles 12 in the weft insertion direction X. The weft yarn sensor 31 is disposed so as to face the vibration damping member 23 across the reed 13. In other words, the reed 13 is disposed between the weft yarn sensor 31 and the vibration damping member 23. The weft yarn sensor 31 is an optical sensor. The weft yarn sensor 31 is provided at a position where the warp yarns T are outside the detection range in the weft insertion direction X.
-
As illustrated in FIG. 3, the weft yarn sensor 31 has a base end fixed to the sley 14 and a tip end facing the reed 13. Hereinafter, the tip end of the weft yarn sensor 31 will be referred to as a sensor end portion 32. The sensor end portion 32 is located at a position facing the vibration suppression member 20 across the reed 13.
-
The weft yarn sensor 31 has a sensor body 33 having a columnar shape and extending from the base end to the sensor end portion 32. A base end and a tip end of the sensor body 33 correspond to the base end and the sensor end portion 32 of the weft yarn sensor 31, respectively. Thus, the tip end of the sensor body 33 will also be referred to as the sensor end portion 32.
Light projection unit and light receiving unit
-
As illustrated in FIGS. 1 and 3, the sensor body 33 includes a light projection unit 32a and a light receiving unit 32b. The light projection unit 32a and the light receiving unit 32b are disposed in the sensor end portion 32. That is, the weft yarn sensor 31 includes the light projection unit 32a and the light receiving unit 32b in the sensor end portion 32. The light projection unit 32a and the light receiving unit 32b are arranged side by side in the weft insertion direction X in the sensor end portion 32. A cable 32c is connected to the base end of the sensor body 33. The cable 32c connects the weft yarn sensor 31 to a control device (not illustrated).
-
As illustrated in FIGS. 3 and 5, the weft yarn sensor 31 has the light projection unit 32a facing a portion of the reed passage 13b, the portion being close to the base ends of the reed dents 15. More specifically, when an imaginary line starting from a point on the light projection unit 32a is drawn in a direction in which an optical axis of the light projection unit 32a extends, the imaginary line passes through the portion of the reed passage 13b, the portion being close to the base ends of the reed dents 15. Thus, it can be said that the weft yarn sensor 31 is disposed so that the light projection unit 32a faces the reed passage 13b. It also can be said that, when the imaginary line starting from the point on the light projection unit 32a is drawn in the direction in which the optical axis of the light projection unit 32a extends, the weft yarn sensor 31 is disposed on the sley 14 so that the imaginary line passes through the reed passage 13b.
-
The light projection unit 32a is formed of a light-emitting diode. The light projection unit 32a is electrically connected to the control device (not illustrated). The light projection unit 32a is configured to emit light under the control of the control device.
-
As illustrated in FIG. 5, the light projection unit 32a projects light toward the reed passage 13b. More specifically, the weft yarn sensor 31 has the light projection unit 32a in the sensor end portion 32 so that the optical axis extending from the light projection unit 32a passes through the reed passage 13b. In the following, a point where a surface of the light projection unit 32a intersects with the optical axis will be referred to as a center of the light projection unit 32a.
-
Light projected from the light projection unit 32a and having traveled to a location away from the light projection unit 32a illuminates a wider range as compared to a location close to the light projection unit 32a. In other words, the range illuminated by the light projected from the light projection unit 32a increases as a distance from the light projection unit 32a increases. In this way, the light projected from the light projection unit 32a toward the reed passage 13b diffuses as a distance from the light projection unit 32a increases.
-
In FIG. 5, a range indicated by two dash-dot lines corresponds to twice the full width at half maximum angle of the light-emitting diode of the light projection unit 32a. In a case where an amount of light projected from light projection unit 32a is measured at a fixed distance from the light projection unit 32a, the amount of light becomes maximum when measured at a position directly facing the light projection unit 32a. An angle at which each of the dash-dot lines in FIG. 5 is inclined with respect to the optical axis of the light projection unit 32a corresponds to the full width at half maximum angle related to the amount of light projected by the light projection unit 32a.
-
In the following description, the range where light is projected by the light projection unit 32a is defined as a range defined by the two dash-dot lines shown in FIG. 5. That is, in the following, the range over which the light projection unit 32a projects light is within the full width at half maximum angle of the light-emitting diode of the light projection unit 32a.
-
The light receiving unit 32b is formed of a photodiode. The light receiving unit 32b is electrically connected to the control device. The light receiving unit 32b is configured to receive light. When receiving light, the light receiving unit 32b outputs an electrical signal according to the amount of light. The electrical signal is input to the control device via the cable 32c. The stronger the light received by the light receiving unit 32b, the larger the magnitude of the electrical signal output by the light receiving unit 32b. In other words, the light receiving unit 32b outputs a larger electrical signal when receiving stronger light.
-
A range indicated by two double dash-dot lines in FIG. 5 corresponds to twice the full width at half maximum angle of the photodiode of the light receiving unit 32b. The light receiving unit 32b outputs the largest electrical signal to the control device when the light receiving unit 32b receives light along a central axis extending from the light receiving unit 32b. The angle at which each of the two double dash-dot lines shown in FIG. 5 is inclined with respect to the central axis is the full width at half maximum angle related to an electric current output by the light receiving unit 32b when receiving light.
-
Of the light projected by the light projection unit 32a to the reed passage 13b, the light receiving unit 32b receives light reflected inside the reed passage 13b. Then, the light receiving unit 32b outputs an electrical signal to the control device according to the amount of light. When the weft yarn Y enters a range detectable by the weft yarn sensor 31, the light receiving unit 32b receives the light that is projected from the light projection unit 32a and then reflected by the weft yarn Y. As a result, the light receiving unit 32b outputs an electrical signal corresponding to the reflected light from the weft yarn Y to the control device. The weft yarn sensor 31 informs the control device that the weft yarn Y is travelling within the detection range with such an electrical signal. That is, the weft yarn sensor 31 can detect the weft yarn Y in the range indicated by the two double dash-dot lines in FIG. 5.
Reflective member
-
As illustrated in FIG. 4, the reflective member 40 has a plate shape. The reflective member 40 is attached to the vibration suppression member 20. More specifically, as illustrated in FIGS. 2 and 3, the reflective member 40 is disposed on a surface of the vibration damping member 23 facing the reed 13, in a portion of the surface, which is not in contact with the reed dents 15. The reflective member 40 extends upright from the vibration damping member 23. A thickness direction of the reflective member 40 extends perpendicularly to both of the longitudinal direction of the vibration suppression member 20 and the thickness direction of the vibration damping member 23.
-
As illustrated in FIG. 3, the reflective member 40 is attached to the air jet loom 10 by the vibration suppression member 20. As illustrated in FIG. 2, the vibration suppression member 20 presses the vibration damping member 23 against the reed 13 from behind the reed 13, while inserting the reflective member 40 into a gap formed by two of the reed dents 15 facing the vibration damping member 23. The reflective member 40 is in contact with the two reed dents 15 adjacent to each other and is inserted into the gap defined by the such two reed dents 15 in the reed 13. In other words, the reflective member 40 is disposed between the reed dents 15 adjacent to each other in the weft insertion direction X. Therefore, the thickness direction of the reflective member 40 coincides with the weft insertion direction X.
-
As illustrated in FIG. 3, the reflective member 40, the reed passage 13b and the weft yarn sensor 31 are arranged in the opening direction A. More specifically, the reflective member 40 is aligned with the sensor end portion 32 across the reed passage 13b in the direction in which the light projection unit 32a projects light. In other words, the reflective member 40 is disposed in the downstream portion of the sley 14. In other words, the weft yarn detection device 30 is disposed in the downstream portion of the sley 14 in the weft insertion direction X.
-
The reflective member 40 has a front surface 41. The front surface 41 is the surface of the reflective member 40, which faces the weft yarn sensor 31. The front surface 41 extends in the longitudinal direction of the reed dents 15. The front surface 41 faces in the opening direction A. In the longitudinal direction of the reed dents 15, the front surface 41 has a greater length than the opening width of the guide recess 15a. The front surface 41 and the first passage forming surface 151 are arranged side by side in a direction perpendicular to the longitudinal direction and the thickness direction of the reed dents 15. In other words, the front surface 41 is aligned with the first passage forming surface 151 in the opening direction A of the guide recess 15a.
-
As illustrated in FIGS. 3 and 5, the reflective member 40 has an arcuate surface 45. The arcuate surface 45 forms a portion of the front surface 41. The arcuate surface 45 is a portion of the front surface 41, which is curved as viewed in the weft insertion direction X. As viewed in the weft insertion direction X, the arcuate surface 45 is recessed in a direction away from the light projection unit 32a.
-
As viewed in the weft insertion direction X, the arcuate surface 45 has an arc shape with the light projection unit 32a as its center. More specifically, as viewed in the weft insertion direction X, the arcuate surface 45 has an arc shape with one point in the light projection unit 32a as its center. In the present embodiment, the one point is the center of the light projection unit 32a. The one point is preferably a point on the optical axis of the light projection unit 32a.
-
As illustrated in FIG. 5, the reflective member 40 has the arcuate surface 45 over the entire surface where the light is projected from the light projection unit 32a through the reed passage 13b. In other words, the reflective member 40 has the arcuate surface 45 at a position where the light is projected from the light projection unit 32a through the reed passage 13b. In the present embodiment, the reflective member 40 has the arcuate surface 45 also in a portion of the front surface 41 where light not having passed through the reed passage 13b, of the light projected from the light projection unit 32a, reaches.
-
The arcuate surface 45 has a portion closer to the tip ends of the reed dents 15 than the second passage forming surface 152 in the longitudinal direction of the reed dents 15, and a portion closer to the base ends of the reed dents 15 than the second passage forming surface 152. In other words, the reflective member 40 has the arcuate surface 45 in a portion of the reflective member 40, the portion being closer to the tip ends of the reed dents 15 than the guide recesses 15a in the longitudinal direction of the reed 15.
-
A portion where the portion of the arcuate surface 45 closer to the tip ends of the reed dents 15 than the second passage forming surface 152 and the portion of the arcuate surface 45 closer to the base ends of the reed dents 15 than the second passage forming surface 152 are connected is aligned with the first connecting surface 154 as viewed in the weft insertion direction X. In other words, that portion of the arcuate surface 45 is flush with the first connecting surface 154. In other words, the reflective member 40 has a portion in the arcuate surface 45, which is flush with the surfaces of the reed dents 15 adjacent to the reflective member 40, the surfaces forming the reed passage 13b.
-
The reflective member 40 is provided at a position that does not overlap with the reed passage 13b as viewed in the weft insertion direction X. In other words, the reflective member 40 is provided in the reed 13 so as not to intersect with a surface that defines the reed passage 13b as viewed in the weft insertion direction X.
-
The arcuate surface 45 reflects the light projected from the light projection unit 32a through the reed passage 13b toward the light receiving unit 32b. More specifically, when the weft yarn Y travels through the reed passage 13b, light that is not reflected by the weft yarn Y reaches the arcuate surface 45 after passing through the reed passage 13b. The light having reached the arcuate surface 45 is reflected by the arcuate surface 45, and then passes through the reed passage 13b again and travels toward an outside of the reed 13. Of the light reflected by the arcuate surface 45, light, in a travelling direction of which the light receiving unit 32b is present in front, is received by the light receiving unit 32b.
Operation of present embodiment
-
The following will describe operation of the present embodiment.
-
The air jet loom 10 inserts the weft yarn Y through the reed passage 13b formed in the reed 13 by air injection. The weft yarn sensor 31 of the weft yarn detection device 30 projects light from the light projection unit 32a toward the reed passage 13b. The light projected by the light projection unit 32a is reflected in the reed passage 13b and then received by the light receiving unit 32b. When the weft yarn Y travels within the range where the light is projected by the light projection unit 32a and within the range where the light receiving unit 32b can detect light, the weft yarn sensor 31 receives the light reflected by the weft yarn Y with the light receiving unit 32b. Accordingly, the weft yarn sensor 31 detects the weft yarn Y.
-
The reflective member 40 of the weft yarn detection device 30 has the arcuate surface 45 at the position where the light is projected from the light projection unit 32a through the reed passage 13b. The arcuate surface 45 reflects the light projected from the light projection unit 32a toward the light receiving unit 32b.
Effects of present embodiment
-
The following will describe effects of the present embodiment.
- (1) The light projected from the light projection unit 32a passes through the reed passage 13b, and is then reflected by the arcuate surface 45 in a direction toward the light receiving unit 32b. The light reflected by the arcuate surface 45 passes through the reed passage 13b again and is then detected by the light receiving unit 32b. The amount of reflected light received by the light receiving unit 32b of the weft yarn detection device 30 increases, for example, as compared with a case where a surface of the reflective member 40 formed in a position where light is projected from the light projection unit 32a through the reed passage 13b is formed of a flat surface.
In addition, the arcuate surface 45 is recessed in a direction away from the light projection unit 32a as viewed in the weft insertion direction X, so that diffusion of the light reflected by the arcuate surface 45 due to the reflection may be suppressed. That is, since the reflective member 40 has the arcuate surface 45, a difference in the amount of light received by the light receiving unit 32b depending on a location where the light is reflected may be reduced. As a result, the weft yarn detection device 30 can suppress the reduction in detection performance for the weft yarn Y depending on a position where the weft yarn Y travels within the reed passage 13b. As a result, the weft yarn detection device 30 of the air jet loom 10 can improve the detection performance for the weft yarn Y. - (2) The reflective member 40 reflects light that passes through the portion of the reed passage 13b close to the tip ends of the reed dents 15. The portion of the reed passage 13b closer to the tip ends of the reed dents 15 is farther away from the light projection unit 32a than other portions of the reed passage 13b. That is, the configuration in which the reflective member 40 has the arcuate surface 45 near the tip ends of the reed dents 15 suppresses decrease in the amount of reflected light even in a location farther away from the light projection unit 32a. As a result, the weft yarn detection device 30 of the air jet loom 10 can improve the detection performance for the weft yarn Y in the portion of the reed passage 13b where detecting the weft yarn Y is relatively difficult
- (3) As viewed in the weft insertion direction X, the arcuate surface 45 has an arc shape having its center at the light projection unit 32a. This configuration suppresses deviation of the light projected from the light projection unit 32a and reflected by the arcuate surface 45, from a path through which the light passes when entering the arcuate surface 45, as viewed in the weft insertion direction X. Therefore, the reflective member 40 can prevent the light projected from the light projection unit 32a from reaching a location other than the light receiving unit 32b by reflecting the light at the arcuate surface 45. Thus, the weft yarn detection device 30 of the air jet loom 10 suppresses the difference in the amount of light received by the light receiving unit 32b depending on a location where the light is reflected. As a result, the weft yarn detection device 30 suppresses decrease in the detection performance for the weft yarn Y even in a case where the weft yarn Y travels at a location farther away from the light projection unit 32a in the reed passage 13b. Accordingly, the weft yarn detection device 30 of the air jet loom 10 can improve the detection performance for the weft yarn Y in the reed passage 13b.
- (4) Compared to a case where the reflective member 40 has the arcuate surface 45 only in a portion of the surface where light is projected from the light projection unit 32a through the reed passage 13b, the reflective member 40 can reduce the difference in the amount of light received by the light receiving unit 32b depending on a location where the light is reflected. As a result, the weft yarn detection device 30 of the air jet loom 10 can improve the detection performance for the weft yarn Y, in front of the weft yarn detection device 30, over the entire reed passage 13b.
- (5) The reflective member 40 is disposed between the reed dents 15 so as not to overlap with the reed passage 13b in the weft insertion direction X while shortening the distance to the light projection unit 32a by having a portion flush with the surfaces of the reed dents 15 forming the reed passage 13b. In other words, the reflective member 40 allows a path of light from the light projection unit 32a to the light receiving unit 32b via the arcuate surface 45 to be shortened without interfering with the travelling of the weft yarn Y in the reed passage 13b. In other words, the weft yarn detection device 30 of the airjet loom 10 can improve the detection performance for the weft yarn Y in the reed passage 13b without interfering with the weft insertion of the weft yarn Y.
Modification
-
The above embodiment may be modified as follows. The above embodiment and the following modification may be combined with each other as long as they do not technically contradict each other.
-
The reflective member 40 does not need to have the arcuate surface 45 over the entire surface where the light is projected from the light projection unit 32a through the reed passage 13b. In other words, the reflective member 40 may have the arcuate surface 45 in a portion of the surface where the light is projected from the light projection unit 32a through the reed passage 13b.
-
As illustrated in FIGS. 6 and 7, for example, the reflective member 40 may have a straight surface 46 extending in the longitudinal direction of the reed dents 15 which forms a portion closer to the base ends of the reed dents 15 than the arcuate surface 45 in the longitudinal direction of the reed dents 15. In this case, the front surface 41 of the reflective member 40 has the arcuate surface 45 and the straight surface 46. In addition, a surface of the reflective member 40 where light is projected from the light projection unit 32a through the reed passage 13b is formed by the arcuate surface 45 and the straight surface 46.
-
The straight surface 46 extends in the longitudinal direction of the reed dents 15 and is parallel to the first passage forming surface 151. The reflective member 40 is disposed in the reed 13 such that the arcuate surface 45 is positioned closer to the tip ends of the reed dents 15 than the second passage forming surface 152, and the straight surface 46 overlaps with the first passage forming surface 151, as viewed in the weft insertion direction X. In other words, the straight surface 46 is flush with the first passage forming surface 151, as viewed in the weft insertion direction X. Accordingly, the reflective member 40 is provided at a position where the surfaces of the reed dents 15 adjacent to the reflective member 40, which face the opening directions of the guide recesses 15a while defining the reed passage 13b, and the straight surface 46 are flush with each other.
-
For example, in a case where the reflective member 40 is provided at a position away from the reed passage 13b, the reflective member 40 and the reed dents 15 disposed adjacent to the reflective member 40 cooperate to form a groove in communication with the reed passage 13b. More specifically, in a case where the reflective member 40 is provided in the reed 13 such that the straight surface 46 is positioned away from the first passage forming surface 151, the reflective member 40 and two reed dents 15 form the groove. In the air jet loom 10, cotton fly generated from the weft yarn Y, which is a spun yarn, may be captured by the groove. In the weft yarn detection device 30, when the reflective member 40 is provided in the reed 13 such that the straight surface 46 is flush with the first passage forming surface 151, it is possible to suppress cotton fly clogging caused by the groove formed by the reflective member 40 and the two reed dents 15. In other words, the weft yarn detection device 30 can prevent the surface of the reflective member 40 where the light is projected from the light projection unit 32a from being covered with cotton fly. Accordingly, the weft yarn detection device 30 of the air jet loom 10 suppresses a decrease in the detection performance for the weft yarn Y due to the cotton fly.
-
The reflective member 40 does not need to have a portion in the arcuate surface 45, the portion being flush with the surfaces of the reed dents 15 adjacent to the reflective member 40, the surfaces forming the reed passage 13b.
-
The reflective member 40 may be disposed at a position overlapping with the reed passage 13b as viewed in the weft insertion direction X. The reflective member 40 may be positioned at any position as long as it does not hinder the travelling of the weft yarn Y in the reed passage 13b.
-
The weft yarn sensor 31 does not necessarily have to have the light projection unit 32a facing the portion of the reed passage 13b close to the base ends of the reed dents 15. For example, the weft yarn sensor 31 may have the light projection unit 32a facing the centers of the reed dents 15 in the longitudinal direction of the reed passage 13b. In short, the weft yarn sensor 31 only needs to have the light projection unit 32a at a position where the light projection unit 32a can project light onto the reed passage 13b.
-
The arcuate surface 45 does not have to have an arc shape having its center at the light projection unit 32a as viewed in the weft insertion direction X. For example, the arcuate surface 45 does not have to have an arc shape having its center at the light receiving unit 32b. Furthermore, the arcuate surface 45 may have an arc shape having a center in a portion of the sensor end portion 32 where the light projection unit 32a and the light receiving unit 32b are not provided.
-
The arcuate surface 45 does not have to have an arc shape as viewed in the weft insertion direction X. In this case, the arcuate surface 45 may be formed of a plurality of curves each having a different curvature as viewed in the weft insertion direction X.
-
The weft yarn detection device 30 does not necessarily have to be provided in the downstream portion of the sley 14 in the weft insertion direction X. The weft yarn detection device 30 is preferably provided downstream of an end of the woven fabric C woven by the air jet loom 10 that is located on the downstream side in the weft insertion direction X.
-
The reflective member 40 does not have to be attached to the air jet loom 10 by the vibration suppression member 20. For example, the reflective member 40 may be inserted between and held by the two adjacent reed dents 15. For example, the reflective member 40 may be inserted between and adhered to the two adjacent reed dents 15.
-
The weft yarn detection device 30 may have a plurality of reflective members 40. In this case, the plurality of reflective members 40 may be attached to the vibration suppression member 20. Furthermore, a plurality of vibration suppression members 20 may be attached to the air jet loom 10, and each of the vibration suppression members 20 may be provided with the reflective member 40.