阅读说明：本技术 上线检测装置 (On-line detection device ) 是由 高井凉介 根本越男 河野涉 中山元 于 2020-12-03 设计创作，主要内容包括：本发明高精度地对经过线轴壳体的表面的上线进行检测。上线检测装置应用于具有对线轴壳体进行配置的釜的缝纫机。上线检测装置具有：反射部件,其配置于釜的一侧；以及光传感器,其配置于釜的另一侧,对上线所经过的线轴壳体的表面照射检测光,对在线轴壳体的表面反射之后被反射部件反射出的检测光的反射光进行检测。线轴壳体的表面包含被照射检测光的平坦部。检测光的光轴相对于平坦部倾斜。(The invention detects the upper line passing through the surface of the bobbin shell with high precision. The thread-up detection device is applied to a sewing machine with a kettle for configuring a bobbin shell. The thread-up detection device comprises: a reflecting member disposed on one side of the tank; and an optical sensor disposed on the other side of the kettle, for irradiating the surface of the bobbin case through which the upper thread passes with the detection light, and detecting the reflected light of the detection light reflected by the reflecting member after being reflected on the surface of the bobbin case. The surface of the spool case includes a flat portion to which the detection light is irradiated. The optical axis of the detection light is inclined with respect to the flat portion.)

1. An upper thread detection device is applied to a sewing machine with a kettle for configuring a bobbin shell,

this detection device that reaches standard grade has:

a reflecting member disposed on one side of the tank; and

an optical sensor disposed on the other side of the kettle, for irradiating detection light on the surface of the bobbin case through which the upper thread passes, and detecting reflected light of the detection light reflected by the reflecting member after being reflected on the surface of the bobbin case,

the surface of the spool housing includes a flat portion to which the detection light is irradiated,

the optical axis of the detection light is inclined with respect to the flat portion.

2. The upline detection device of claim 1,

an angle formed by the optical axis of the detection light and the flat portion is greater than or equal to 5 ° and less than or equal to 50 °.

3. The inline detecting device according to claim 1 or 2,

an angle formed by the optical axis of the detection light and the flat portion is greater than or equal to 5 ° and less than or equal to 12 °.

4. The inline detecting device according to any one of claims 1 to 3,

the reflecting member reflects the detection light toward the flat portion,

the light sensor detects the detection light reflected by the flat portion.

5. The upline detection device of claim 4, wherein,

the reflecting member reflects the incident detection light.

6. The upline detection device of claim 4, wherein,

the reflective member has a flat reflective surface,

an angle formed by the optical axis of the detection light and the flat portion is the same as an angle formed by a reference line parallel to a normal line of the flat portion and the reflection surface.

7. The inline detecting device according to any one of claims 1 to 6,

the detection light includes laser light.

8. The inline detecting device according to any one of claims 1 to 6,

the detection light includes laser light of a plurality of wavelengths.

Technical Field

The invention relates to an online detection device.

Background

The sewing machine has a sewing needle and a kettle including an inner kettle and an outer kettle. The sewing machine needle moves up and down. The inner kettle holds the spool accommodated in the spool housing. The outer pot rotates along with the up-and-down movement of the sewing machine needle. The upper thread passes through a needle hole of a sewing machine needle. The lower wire is wound on the bobbin. When a sewing machine needle penetrating through a cloth is raised, a thread loop of a top thread is formed. The wire loop of the upper wire is hooked at the tip of the outer kettle which rotates. The wire loop of the upper wire hooked on the tip expands along with the rotation of the outer pot, passing through the surface of the bobbin case. If the loop of the upper thread is disengaged from the tip, the upper thread is pulled by the cloth and intertwines with the lower thread. The upper and lower threads are wound around each other, thereby forming a stitch on the cloth.

In the sewing of a sewing machine, there is a possibility that sewing problems such as stitch skipping, double hooking and thread breakage occur. The cause of the sewing problem is, for example, the inconsistency between the vertical movement of the sewing machine needle and the rotational movement of the outer pot, or the abnormality of the tension acting on the upper thread. As disclosed in patent document 1, it is studied to detect a sewing problem by detecting a top thread passing through the surface of a bobbin case.

In the jumper and disconnection detecting device described in patent document 2, a light emitting portion is disposed on one side of a pot, and a light receiving portion is disposed on the other side of the pot, so that the optical path of inspection light is perpendicular to the rotation axis of the pot at the end surface of the pot. The detection device detects the presence or absence of the passage of the upper line based on the amount of transmitted light when the upper line crosses the optical path of the inspection light.

Patent document 1: japanese laid-open patent publication No. 2000-197786

Patent document 2: japanese patent laid-open publication No. 2016-101183

In patent document 1, the photodetector is disposed at an angle of about 45 ° with respect to the rotation axis of the middle tank. Therefore, the time for the upper line to pass through the detection area of the photodetector is short. Therefore, when the sewing machine is driven at a high speed, the detection accuracy of the upper thread passing through the surface of the bobbin case may be insufficient.

In the detection device described in patent document 2, the oscillation of the pot becomes a problem. Strictly speaking, the pot swings in the direction of the rotation axis by the amount of the gap due to the tension of the upper thread, the driving of the motor, or the like during the driving of the sewing machine. In this detection device, the light emitting portion and the light receiving portion are arranged so that the optical path of the inspection light coincides with the end face of the pot, and therefore there is a possibility that the inspection light is blocked by the pot due to the oscillation of the pot. Therefore, it is necessary to take additional measures such as correcting a change in the amount of light received when the inspection light is blocked by the kettle, or separating the optical path of the inspection light from the kettle so that the inspection light is not blocked even if the kettle swings, on the determination means side. However, even when this additional measure is taken, the amount of light received by the transmitted light is less likely to change for the thread of the fine yarn count, and it may be difficult to stably detect the presence or absence of the passage of the thread.

Disclosure of Invention

The purpose of the present invention is to detect an upper thread passing through the surface of a spool case with high accuracy.

According to the present invention, there is provided an needle threading detecting device applied to a sewing machine having a pot for disposing a bobbin case, the needle threading detecting device comprising: a reflecting member disposed on one side of the tank; and an optical sensor disposed on the other side of the kettle, for irradiating a detection light onto a surface of the spool housing through which the upper thread passes, and detecting a reflected light of the detection light reflected by the reflecting member after the reflected light is reflected by the surface of the spool housing, wherein the surface of the spool housing includes a flat portion onto which the detection light is irradiated, and an optical axis of the detection light is inclined with respect to the flat portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the invention, the upper line passing through the surface of the bobbin case can be detected with high precision.

Drawings

Fig. 1 is a view schematically showing a part of a sewing machine according to embodiment 1.

Fig. 2 is a view schematically showing the operation of the sewing machine according to embodiment 1.

Fig. 3 is a view schematically showing the operation of the sewing machine according to embodiment 1.

Fig. 4 is a view schematically showing the operation of the sewing machine according to embodiment 1.

Fig. 5 is a view schematically showing the operation of the sewing machine according to embodiment 1.

Fig. 6 is a view schematically showing the operation of the sewing machine according to embodiment 1.

Fig. 7 is a view schematically showing the operation of the sewing machine according to embodiment 1.

Fig. 8 is a diagram schematically showing an upper thread detecting device according to embodiment 1.

Fig. 9 is a schematic view showing a positional relationship between the detection light and the upper line in the flat portion according to embodiment 1.

Fig. 10 is an enlarged view of a part of fig. 9.

Fig. 11 is a view schematically showing the state of the detection light when the inner pot swings to one side of the rotation axis according to embodiment 1.

Fig. 12 is a view schematically showing the state of the detection light when the inner pot swings to the other side of the rotation axis according to embodiment 1.

Fig. 13 is a diagram schematically showing an upper thread detecting device according to embodiment 2.

Fig. 14 is a diagram schematically showing the operation of the upper line detection device according to embodiment 2.

Fig. 15 is a diagram schematically showing the operation of the upper line detection device according to embodiment 2.

Fig. 16 is a diagram schematically showing an upper thread detecting device according to embodiment 3.

Fig. 17 is a diagram schematically showing an upper thread detecting device according to embodiment 4.

Description of the reference numerals

1 … sewing machine, 2 … thread, 3 … thread, 4 … sewing machine needle, 4a … pinhole, 5 … presser foot, 5a … opening, 6 … kettle, 6a … inner kettle, 6B … outer kettle, 7 … bobbin housing, 7a … front end, 7B … rear end, 8 … tip, 9 … thread loop, 11a … thread detection device, 11B … thread detection device, 11C … thread detection device, 11D … thread detection device, 12 … reflection component, 12a … reflection plate, 12B … retro-reflection plate, 12C … angular prism reflector, 12R … reflection surface, 13 … optical sensor, 14 … judging part, 15 …, 21 … sensor amplifier part, 22 … control device, B … distance, C … cloth, C … distance, D … diameter, F …, rotating shaft …, L … contact, L …, … size detection light reflection light …, … size, r … radius, x … distance, θ … angle.

Detailed Description

Embodiments according to the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. The constituent elements of the embodiments described below can be combined as appropriate. In addition, some of the components may not be used.

In the embodiments, the positional relationship of each portion will be described using terms of left, right, front, rear, upper, and lower. These terms indicate relative positions or directions with respect to the center of the sewing machine.

[ embodiment 1 ]

< overview of Sewing machine >

Fig. 1 is a view schematically showing a part of a sewing machine 1 according to the present embodiment. The sewing machine 1 forms a stitch on the fabric C through the upper thread 2 and the lower thread 3. As shown in fig. 1, a sewing machine 1 includes: a sewing machine needle 4 having a needle hole 4 a; a presser foot 5 for pressing the fabric C; a kettle 6 configured with a spool case 7; and a needle thread detecting device 11A that detects the needle thread 2 passing on the surface of the bobbin case 7.

The upper thread 2 passes through a needle hole 4a of the sewing machine needle 4. The lower wire 3 is wound around a bobbin (not shown). The spool is housed in the spool case 7.

The sewing needle 4 is moved up and down by power generated by a driving device (not shown). The sewing needle 4 moves up and down so as to change from one of a state of penetrating the fabric C and a state of being disposed above the fabric C to the other in a state where the upper thread 2 passes through the needle hole 4 a.

The presser foot 5 presses the fabric C from above around a needle drop position directly below the sewing machine needle 4. The cloth C is supported by a needle plate (not shown). The presser foot 5 presses the cloth C so as to sandwich the cloth C between the presser foot and the needle plate. The presser foot 5 is a plate-like member. The presser foot 5 has an opening 5a through which the sewing needle 4 can pass.

The kettle 6 is arranged below the cloth C. The reactor 6 includes an inner reactor 6A and an outer reactor 6B. The inner pot 6A holds the bobbin accommodated in the bobbin case 7. The lower thread 3 is fed from the bobbin case 7. The outer vessel 6B is disposed around the inner vessel 6A. The outer tub 6B rotates with the vertical movement of the sewing needle 4. The outer vessel 6B performs a rotational motion about the rotational axis F. The rotation axis F extends in the left-right direction. The pot 6 is a vertical pot in which the rotation axis F and the moving direction of the sewing needle 4 are substantially orthogonal to each other. The outer pot 6B performs 2 times of rotational movement while the sewing machine needle 4 performs 1 time of up-and-down movement. The spool is housed in the spool case 7 so that the center axis of the spool coincides with the center axis of the spool case 7. The bobbin case 7 is housed in the inner pot 6A so that the central axis of the bobbin case coincides with the rotation axis F. Outer vessel 6B has a tip 8. The upper thread 2 is hooked on the tip 8 by the rotation of the outer pot 6B.

The needle thread detecting device 11A is applied to the sewing machine 1. The upper thread detecting device 11A optically detects the upper thread 2 passing through the surface of the bobbin case 7 in the formation of the stitches. The needle thread detection device 11A includes: a reflecting member 12 disposed on one side (rear side) of the kettle 6; and an optical sensor 13 disposed on the other side (front side) of the tank 6. The optical sensor 13 irradiates the detection light L1 on the surface of the bobbin case 7, and detects the upper thread 2 passing through the surface of the bobbin case 7. The surface of the bobbin case 7 includes a flat portion 15 irradiated with the detection light L1 from the photosensor 13. The flat portion 15 has a rectangular shape elongated in the front-rear direction.

< action of sewing machine >

Fig. 2 to 7 are views each schematically showing an operation of the sewing machine 1 according to the present embodiment. In fig. 2 to 7, the upper line detection device 11A is not shown.

As shown in fig. 2, if the sewing needle 4 disposed above the fabric C moves downward, the sewing needle 4 penetrates the fabric C together with the upper thread 2. The sewing needle 4 penetrating the cloth C together with the upper thread 2 reaches the bottom dead center. When the sewing needle 4 reaching the bottom dead center is raised, the thread loop 9 of the upper thread 2 is formed. The outer tub 6B rotates with the vertical movement of the sewing needle 4. The thread loop 9 of the upper thread 2 is hooked on the tip 8 of the outer vessel 6B which performs a rotational motion.

As shown in fig. 3, the thread loop 9 of the upper thread 2 hooked on the tip 8 is extended to the lower side of the bobbin case 7 in accordance with the rotational movement of the outer vessel 6B.

As shown in fig. 4, if the outer vessel 6B further rotates, the loop 9 of the upper thread 2 extending to the lower side of the bobbin case 7 is hooked on the lower thread 3 supplied from the bobbin case 7.

As shown in fig. 5, if the outer vessel 6B further performs the rotational movement, the thread ring 9 of the upper thread 2 hooked on the lower thread 3 moves so as to pass the bobbin case 7. At least a portion of the upper thread 2 passes through the surface of the spool housing 7. The upper cord 2 moves in the front-rear direction in the surface of the bobbin case 7. The upper thread 2 passes through the surface of the bobbin case 7 from the front end portion 7a toward the rear end portion 7b of the surface of the bobbin case 7.

As shown in fig. 6, if the outer pot 6B further performs a rotational motion, the wire loop 9 of the upper thread 2, which is moved in such a manner that the bobbin case 7 passes through, is disengaged from the tip 8. When the loop 9 of the upper thread 2 is disengaged from the tip 8, the upper thread 2 is pulled by the fabric C by the upward movement of the sewing needle 4, and is entangled with the lower thread 3 supplied from the bobbin case 7.

As shown in fig. 7, the upper thread 2 and the lower thread 3 supplied from the bobbin case 7 are entangled with each other, thereby forming a stitch on the cloth C.

By performing the operation of the sewing machine 1 described with reference to fig. 2 to 7, 1 stitch is formed on the fabric C. The operation of the sewing machine 1 described with reference to fig. 2 to 7 is repeated, thereby forming a plurality of stitches on the fabric C.

< on-line detection device >

As described above, at the time of the track formation, the upper thread 2 passes the surface of the bobbin case 7 by the rotational movement of the outer pot 6B. The upper thread detecting device 11A detects the upper thread 2 passing through the surface of the bobbin case 7. The presence or absence of the passage of the upper thread 2 on the surface of the bobbin case 7 is detected, thereby detecting the presence or absence of sewing problems such as a skip stitch, double hooking, and thread breakage. Further, the cause of the sewing problem is, for example, the inconsistency between the vertical movement of the sewing needle 4 and the rotational movement of the outer tub 6B, or the abnormality of the tension acting on the upper thread 2. The needle thread detecting device 11A detects the needle thread 2 passing through the surface of the bobbin case 7 when 1 stitch is formed, thereby detecting a sewing problem.

Fig. 8 is a diagram schematically showing the upper thread detecting device 11A according to the present embodiment. As shown in fig. 8, the upper line detecting device 11A includes: a reflecting member 12 disposed on one side (rear side) of the kettle 6; an optical sensor 13 disposed on the other side (front side) of the tank 6; a sensor amplifier unit 21 including the determination unit 14; and a control device 22. The surface of the spool housing 7 through which the upper thread 2 passes comprises a flat 15.

The optical sensor 13 includes: an emission unit that emits detection light L1; and a light detection unit for detecting a reflected light L2 of the detection light L1 reflected by the reflecting member 12. The detection light L1 emitted from the emitting portion of the photosensor 13 includes laser light. The emitting portion includes a laser light source. The emission portion may include a light emitting element such as a light emitting diode. The light detection unit includes a light receiving element such as a photodiode.

The reflecting member 12 reflects the detection light L1 from the emitting portion of the optical sensor 13. The reflecting member 12 includes a reflecting plate 12A, and the reflecting plate 12A has a flat reflecting surface 12 r. The reflection surface 12r of the reflection plate 12A reflects the detection light L1. As a material of the reflecting member 12, a methacrylic resin or an acrylic resin is exemplified.

The optical sensor 13 irradiates the detection light L1 on the surface of the bobbin case 7 through which the upper thread 2 passes, and detects the reflected light L2 of the detection light L1 reflected by the reflection plate 12A after being reflected on the surface of the bobbin case 7. The emission portion of the optical sensor 13 irradiates the detection light L1 on the flat portion 15 of the surface of the bobbin case 7. The light detection unit of the photosensor 13 detects the reflected light L2 of the detection light L1 reflected by the flat portion 15 and reflected by the reflecting plate 12A.

The flat portion 15 reflects the detection light L1 from the emission portion of the photosensor 13. The flat portion 15 includes a flat surface. The flat portion 15 may include a gently curved surface. The surface of the bobbin case 7 around the flat portion 15 may be a flat surface or a curved surface.

The upper thread 2 passes through the surface of the bobbin case 7 from the front end portion 7a toward the rear end portion 7b of the surface of the bobbin case 7. At least a portion of the upper thread 2 passes through the flat 15. The flat portion 15 has a rectangular shape elongated in the front-rear direction. The moving direction of the upper wire 2 in the surface of the spool case 7 and the longitudinal direction of the flat portion 15 are each the front-rear direction. That is, the moving direction of the upper thread 2 in the surface of the bobbin case 7 coincides with the longitudinal direction of the flat portion 15.

The reflection plate 12A is disposed on one side (rear side) of the bobbin case 7. The optical sensor 13 is disposed on the other side (front side) of the bobbin case 7. The upper thread 2 passes through the surface of the bobbin case 7 from the front end portion 7a toward the rear end portion 7b of the surface of the bobbin case 7. One side of the spool case 7 includes a rear end portion 7b side where the upper thread 2 is retreated from the surface of the spool case 7. The other side of the bobbin case 7 includes a front end portion 7a side where the upper thread 2 enters toward the surface of the bobbin case 7.

The reflection plate 12A is disposed at a position separated rearward from the spool case 7 (kettle 6). The optical sensor 13 is disposed at a position separated forward from the spool case 7 (kettle 6). The bobbin case 7 is disposed between the reflection plate 12A and the optical sensor 13 in the front-rear direction. The reflection plate 12A is disposed on the side of the bobbin case 7 so as to be parallel to the reflection surface 12r and the normal line of the flat portion 15. The optical sensor 13 is disposed on the other side of the bobbin case 7, and at least a part of the optical sensor 13 is opposed to the reflection plate 12A.

The emission unit of the optical sensor 13 emits the detection light L1 so as to irradiate the detection light L1 to the flat portion 15 of the bobbin case 7. The optical axis of the detection light L1 emitted from the emitting portion of the photosensor 13 is inclined with respect to the flat portion 15. The optical axis of the detection light L1 represents the optical path of the detection light L1.

An angle θ formed by the optical axis of the detection light L1 and the flat portion 15 of the bobbin case 7 is equal to or greater than 5 ° and equal to or less than 50 °. The angle θ formed by the optical axis of the detection light L1 and the flat portion 15 of the bobbin case 7 is preferably equal to or greater than 5 ° and equal to or less than 12 °.

The sensor amplifier unit 21 receives a detection signal from the light detection unit of the optical sensor 13. The light detection unit outputs a detection signal based on the light intensity of the detected reflected light L2.

The sensor amplifier unit 21 includes a determination unit 14. The determination section 14 determines whether or not the upper wire 2 passes through the surface of the bobbin case 7 based on a detection signal from the light detection section. That is, the determination unit 14 determines the presence or absence of the passage of the upper wire 2 on the surface of the bobbin case 7 based on the detection signal from the light detection unit.

The control device 22 controls the sewing machine 1 based on the determination of the presence or absence of the passing of the upper thread 2 by the determination section 14. The control device 22 comprises a computer system. The control device 22 includes, for example, a PLC (Programmable Logic Controller).

The control device 22 may also have a function of the determination unit 14 that determines whether or not the wire 2 has passed.

< actions of Online detecting device >

When the upper wire 2 does not pass through the surface of the spool case 7, the detection light L1 emitted from the emission part to the flat part 15 is reflected by the flat part 15, then enters the reflection surface 12r of the reflection plate 12A, and is reflected by the reflection surface 12 r. At least a part of the reflected light L2 of the detection light L1 reflected by the reflection surface 12r returns to the optical sensor 13 and is detected by the light detection unit.

When the upper thread 2 passes through the surface of the bobbin case 7, at least a part of the detection light L1 emitted from the emitting portion is absorbed or scattered by the upper thread 2. At least a part of the detection light L1 emitted from the emitting portion is reflected by the flat portion 15, enters the reflection surface 12r of the reflection plate 12A, and is reflected by the reflection surface 12 r. At least a part of the reflected light L2 of the detection light L1 reflected by the reflection surface 12r returns to the optical sensor 13 and is detected by the light detection unit.

The light detection unit detects the light intensity of the reflected light L2 from the reflection plate 12A and outputs a detection signal to the sensor amplifier unit 21. The determination section 14 of the sensor amplifier section 21 determines the presence or absence of the passage of the upper wire 2 on the surface of the bobbin case 7 based on the detection signal from the light detection section. When the upper thread 2 passes through the surface of the bobbin case 7, at least a part of the detection light L1 emitted from the emitting portion is absorbed or scattered by the upper thread 2. Therefore, the light intensity of the reflected light L2 detected by the light detector when the upper line 2 passes through the surface of the spool case 7 is weaker than the light intensity of the reflected light L2 detected by the light detector when the upper line 2 does not pass through the surface of the spool case 7. Therefore, the determination unit 14 can determine the presence or absence of the passage of the upper wire 2 on the surface of the bobbin case 7 based on the detection signal from the light detection unit.

The determination unit 14 compares a predetermined threshold value for light intensity with light intensity detected by the light detection signal. When the light intensity of the reflected light L2 is determined to be equal to or less than the threshold value when 1 trace is formed, the determination unit 14 determines that the upper thread 2 passes through the surface of the bobbin case 7. When the light intensity of the reflected light L2 is determined to be not less than or equal to the threshold value when 1 trace is formed, the determination unit 14 determines that the upper thread 2 does not pass through the surface of the bobbin case 7.

When the upper thread 2 is judged not to pass through the surface of the bobbin case 7, the control device 22 decelerates or stops the driving device of the sewing needle 4. Further, when it is determined that the needle thread 2 does not pass through the surface of the bobbin case 7, the control device 22 may operate a notification device including a display or a speaker to notify that there is a possibility of a sewing problem.

< Angle >

Next, an angle θ formed by the optical axis of the detection light L1 and the flat portion 15 of the bobbin case 7 will be described. The usual shortest input time in the control device 22 is 2.5[ mu ] s or more and 50[ mu ] s or less. On the other hand, the response time of the light detection unit mounted on the optical sensor 13 is usually about 80[ μ s ]. Therefore, even when the sensor amplifier section 21 has the determination section 14 or when the control device 22 has the function of the determination section 14, the time required for the detection of the upper thread 2 in the upper thread detecting device 11A depends on the response time of the optical sensor 13.

In addition, in sewing the fabric C, the normal rotation speed of the sewing machine 1 is greater than or equal to 1000[ rpm ] and 3000[ rpm ]. The higher the rotation speed of the sewing machine 1 is, the higher the possibility of the sewing problems such as the needle skipping, the double hooking and the thread breakage is. Therefore, when a sewing problem occurs, the rotational speed of the sewing machine 1 needs to be reduced. In the case where the rotational speed of the sewing machine 1 is 1000 rpm, the time required for 1 rotation is about 0.06 s. In the case where the rotational speed of the sewing machine 1 is 3000 rpm, the time required for 1 rotation is about 0.02 s. In addition, in the case where the rotational speed of the sewing machine 1 is 1000[ rpm ], the moving speed of the upper thread 2 is about 14000[ mm/s ]. In the case where the rotational speed of the sewing machine 1 is 3000 rpm, the moving speed of the upper thread 2 is about 42000 mm/s.

The size R of the detection area of the upper line 2 is calculated by the product of the response time of the optical sensor 13 and the moving speed of the upper line 2. The detection region of the upper line 2 is an irradiation region of the detection light L1 in the flat portion 15. In the case where the response time of the photosensor 13 is 80[ mu ] s and the rotational speed of the sewing machine 1 is 1000[ rpm ], the size R of the detection area of the upper thread 2 is about 1.12[ mm ]. In the case where the response time of the photosensor 13 is 80[ mu ] s and the rotational speed of the sewing machine 1 is 3000[ rpm ], the size R of the detection area of the upper thread 2 is about 3.36[ mm ].

Under the above conditions, the angle θ formed by the optical axis of the detection light L1 and the flat portion 15 of the axis housing 7 is preferably set within a certain range.

Fig. 9 is a schematic view showing a positional relationship between the detection light L1 and the upper line 2 in the flat portion 15 according to the present embodiment. Fig. 10 is an enlarged view of a part of fig. 9. In the example shown in fig. 9 and 10, the diameter D of the detection light L1 and the radius r of the upper thread 2 are defined. The reflection position p of the detection light L1 in the flat portion 15 is separated from the outer edge of the detection light L1 by a distance x. A hanging point of the contact point f between the upper line 2 and the detection light L1 in the flat portion 15 is separated from the outer edge of the detection light L1 by a distance b. The contact f between the upper wire 2 and the detection light L1 is separated from the flat portion 15 by a distance c.

In the example shown in fig. 9 and 10, the size R of the detection region of the upper line 2 is represented by [ R ═ 2 x-2 b ]. In deriving the distance x, a relational expression of [ x ═ D/2sin θ ] can be used. When deriving the distance b, 2 relations of [ b ═ c/tan θ ] and [ c ═ r + rcos θ ] can be used.

The radius r of the upper wire 2 is set to 0.065[ mm ], and the diameter D of the detection light L1 is set to 1[ mm ]. The upper limit value of the dimension R of the detection region of the upper line 2 is the dimension in the longitudinal direction of the flat portion 15. The flat portion 15 formed in the conventional sewing machine 1 has a dimension in the longitudinal direction of about 9[ mm ]. Therefore, the upper limit value of the size R of the detection region of the upper line 2 is 9[ mm ]. When the upper limit value of the size R of the detection region is set to 9 mm, the angle theta is about 5 DEG according to the above equation.

The lower limit value of the size R of the detection region is about 1.12[ mm ] when the rotational speed of the sewing machine 1 is 1000[ rpm ], and about 3.36[ mm ] when the rotational speed of the sewing machine 1 is 3000[ rpm ]. In the case where the dimension R of the detection region is 1.12[ mm ], the angle θ is about 50[ ° ]. In the case where the dimension R of the detection region is 3.36[ mm ], the angle θ is about 12[ ° ].

Therefore, in the case where the rotational speed of the sewing machine 1 is 1000[ rpm ], the angle θ is preferably greater than or equal to 5[ ° ] and less than or equal to 50[ ° ]. When the rotational speed of the sewing machine 1 is 3000[ rpm ], the angle θ is preferably 5 ° or more and 12 ° or less.

< Effect >

As described above, according to the present embodiment, the detection light L1 emitted from the emitting portion of the photosensor 13 is irradiated to the surface of the bobbin case 7. The detection light L1 reflected by the surface of the spool case 7 is irradiated to the reflection plate 12A. The reflected light L2 of the detection light L1 reflected by the reflection plate 12A is detected by the light detection unit of the photosensor 13. Further, the optical axis of the detection light L1 is inclined with respect to the flat portion 15 of the bobbin case 7. Thereby, a time for the upper line 2 to pass through the detection area of the photosensor 13 is sufficiently secured. Therefore, regardless of the type of thread, the presence or absence of the thread 2 can be detected with high accuracy even when the sewing machine 1 is driven at high speed.

Fig. 11 is a diagram schematically showing a state of the detection light L1 when the inner pot 6A according to the present embodiment swings to the side of the rotation axis F. Fig. 12 is a diagram schematically showing a state of the detection light L1 when the inner pot 6A swings to the other side of the rotation axis F according to the present embodiment.

In the driving of the sewing machine 1, the pot 6 may swing in the left-right direction parallel to the rotation axis F by a gap amount due to the tension of the upper thread 2, the driving of the motor, or the like. In the present embodiment, the optical axis of the detection light L1 is inclined with respect to the flat portion 15 of the bobbin case 7. Therefore, when the spool case 7 is displaced toward the photosensor 13 due to the oscillation of the kettle 6, as shown in fig. 11, the reflection position of the detection light L1 on the flat portion 15 may be slightly displaced toward the photosensor 13. However, the optical path of the detection light L1 is not blocked by the kettle 6 or the spool case 7. Similarly, when the spool case 7 is displaced to the opposite side of the optical sensor 13 by the oscillation of the kettle 6, as shown in fig. 12, the reflection position of the detection light L1 in the flat portion 15 may be slightly displaced toward the reflection member 12. However, the optical path of the detection light L1 is not blocked by the kettle 6 or the spool case 7. Therefore, the detection of the upper thread 2 can be stably performed without being affected by the oscillation of the pot 6.

In the present embodiment, the angle θ formed by the optical axis of the detection light L1 and the flat portion 15 of the bobbin case is equal to or greater than 5 ° and equal to or less than 50 °. In this case, when the normal rotation speed of the sewing machine 1 is greater than or equal to 1000[ rpm ] and less than or equal to 3000[ rpm ], the presence or absence of the upper thread 2 passing through the surface of the bobbin case 7 can be detected with high accuracy.

In the present embodiment, the angle θ formed by the optical axis of the detection light L1 and the flat portion 15 of the bobbin case 7 may be equal to or greater than 5 ° and equal to or less than 12 °. In this case, when the rotational speed of the sewing machine 1 is high, about 3000 rpm, the presence or absence of the passage of the upper thread 2 on the surface of the bobbin case 7 can be detected with high accuracy.

[ 2 nd embodiment ]

Embodiment 2 will be explained. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Fig. 13 is a diagram schematically showing the upper thread detecting device 11B according to the present embodiment. As shown in fig. 13, the upper thread detecting device 11B includes: a reflecting member 12 disposed on one side (rear side) of the kettle 6; an optical sensor 13 disposed on the other side (front side) of the tank 6 and emitting detection light L1; a sensor amplifier section 21; and a control device 22 including the determination unit 14. The surface of the spool housing 7 through which the upper thread 2 passes comprises a flat 15.

In the present embodiment, the reflecting member 12 reflects the detection light L1 toward the flat portion 15. The light detection unit of the photosensor 13 detects the detection light L1 reflected by the flat portion 15, i.e., the reflected light L2.

In the present embodiment, the reflecting member 12 includes a retroreflective sheet 12B that retroreflects the incident detection light L1. Retro-reflection refers to the reflection of incident light in a manner that follows the path of the incident light. The retroreflective sheet 12B is an optical member that reflects the detection light L1 along the optical path of the detection light L1 incident on the retroreflective sheet 12B. As shown in fig. 13, the retroreflective plate 12B reflects the detection light L1 so that the optical path of the detection light L1 incident on the retroreflective plate 12B and the optical path of the reflected light L2 of the detection light L1 reflected by the retroreflective plate 12B coincide with each other.

The detection light L1 emitted from the emitting portion of the photosensor 13 is irradiated to the flat portion 15. The detection light L1 reflected by the flat portion 15 is incident on the retroreflective sheet 12B. The retroreflective sheet 12B reflects the detection light L1. The flat portion 15 is irradiated with the reflected light L2 of the detection light L1 reflected by the retroreflective sheet 12B. The reflected light L2 reflected by the flat portion 15 is detected by the light detection portion of the optical sensor 13.

Fig. 14 is a diagram schematically showing the operation of the upper line detection device 11B according to the present embodiment. As shown in fig. 14, the optical path (optical axis) of the detection light L1 directed from the emission part of the optical sensor 13 to the retroreflective sheet 12B via the flat part 15 and the optical path (optical axis) of the reflection light L2 directed from the retroreflective sheet 12B to the light detection part of the optical sensor 13 via the flat part 15 substantially coincide with each other. Therefore, the upper wire 2 passing through the surface of the bobbin case 7 passes through the optical path of the detection light L1 and the optical path of the reflected light L2, respectively. That is, the upper thread detecting device 11B can detect the upper thread 2 using both the detection light L1 and the reflected light L2. Since there is a timing of detecting the upper thread 2a plurality of times (at least 2 times), the detection accuracy of the upper thread 2 by the upper thread detecting device 11B is improved.

Fig. 15 is a diagram schematically showing the operation of the upper line detection device 11B according to the present embodiment. As shown in fig. 15, for example, the orientation of the flat portion 15 may be changed by the vibration of the sewing machine 1. Fig. 15(a) shows a state in which flat portion 15 is inclined rightward toward the front. Fig. 15(B) shows a state in which flat portion 15 is inclined rightward toward the rear. The orientation of the flat portion 15 is not limited to the state shown in fig. 15(a) and 15 (B).

As shown in fig. 15, the detection light L1 is reflected back by the retroreflective plate 12B, and thus the reflected light L2 can enter the light detection section of the optical sensor 13 even if the orientation of the flat section 15 is changed. Therefore, the detection accuracy of the needle thread 2 by the needle thread detecting device 11B is improved.

As described above, according to the present embodiment, the reflecting member 12 irradiates the reflected light L2 to the flat portion 15. The light detection unit of the optical sensor 13 detects the reflected light L2 from the flat portion 15. The upper thread 2 passing through the surface of the bobbin case 7 passes through the optical path of the detection light L1 and the optical path of the reflected light L2, respectively. The upper thread detecting device 11B detects the upper thread 2 by using both the detection light L1 and the reflected light L2, and therefore the detection accuracy of the upper thread 2 is improved.

[ embodiment 3 ]

Embodiment 3 will be explained. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Fig. 16 is a diagram schematically showing the upper thread detecting device 11C according to the present embodiment. As shown in fig. 16, the upper thread detecting device 11C includes: a reflecting member 12 disposed on one side (rear side) of the kettle 6; an optical sensor 13 disposed on the other side (front side) of the tank 6 and emitting detection light L1; a sensor amplifier unit 21 including the determination unit 14; and a control device 22. The surface of the spool housing 7 through which the upper thread 2 passes comprises a flat 15.

The reflecting member 12 irradiates the reflected light L2 to the flat portion 15. The light detection unit of the optical sensor 13 detects the reflected light L2 from the flat portion 15.

In the present embodiment, the reflecting member 12 includes an angular prism reflector 12C. The angular prism reflector 12C can retroreflect the incident detection light L1. As shown in fig. 16, the angular prism reflector 12C can reflect the detection light L1 so that the optical path of the detection light L1 entering the angular prism reflector 12C and the optical path of the reflected light L2 of the detection light L1 reflected by the angular prism reflector 12C coincide with each other.

As described above, in the present embodiment, the upper thread 2 passing through the surface of the bobbin case 7 also passes through the optical path of the detection light L1 and the optical path of the reflected light L2, respectively. Therefore, the detection accuracy of the upper line 2 is improved.

[ 4 th embodiment ]

Embodiment 4 will be explained. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Fig. 17 is a diagram schematically showing the upper thread detecting device 11D according to the present embodiment. As shown in fig. 17, the upper thread detecting device 11D includes: a reflecting member 12 disposed on one side (rear side) of the kettle 6; an optical sensor 13 disposed on the other side (front side) of the tank 6 and emitting detection light L1; a sensor amplifier unit 21 including the determination unit 14; and a control device 22. The surface of the spool housing 7 through which the upper thread 2 passes comprises a flat 15.

The reflecting member 12 irradiates the reflected light L2 to the flat portion 15. The light detection unit of the optical sensor 13 detects the reflected light L2 from the flat portion 15.

In the present embodiment, the reflecting member 12 includes a reflecting plate 12A having a flat reflecting surface 12r as described in embodiment 1.

In the present embodiment, the angle θ formed by the optical axis of the detection light L1 and the flat portion 15 is the same as the angle γ formed by the reference line parallel to the normal line of the flat portion 15 and the reflection surface 12 r.

The angle γ is adjusted so as to coincide with the angle θ, whereby the reflection plate 12A can retroreflect the detection light L1.

As described above, in the present embodiment, the upper thread 2 passing through the surface of the bobbin case 7 also passes through the optical path of the detection light L1 and the optical path of the reflected light L2, respectively. Therefore, the detection accuracy of the upper line 2 is improved.

[ other embodiments ]

In the above-described embodiment, the detection light L1 may be a laser light of a plurality of wavelengths. That is, the emission unit may include a superimposed laser light source of different wavelengths. The detection light L1 includes laser light of a plurality of wavelengths, and thus detects the upper thread 2 passing through the surface of the bobbin case 7 with high accuracy even if the characteristics (thickness, color, transmittance) of the upper thread 2 change. For example, in the case of using the upper line 2 which hardly absorbs the laser light of the 1 st wavelength but easily absorbs the laser light of the 2 nd wavelength, the laser light of the 2 nd wavelength is irradiated to the upper line 2, thereby detecting the upper line 2 with high accuracy.

In the above-described embodiment, the reflecting member 12 may be disposed on the other side of the kettle 6, and the optical sensor 13 may be disposed on one side of the kettle 6. Further, an actuator capable of adjusting the position or posture of the optical sensor 13 may be provided, and the angle θ formed by the optical axis of the detection light L1 and the flat portion 15 may be changed.

In the above embodiment, the tank 6 is a vertical tank. Kettle 6 may also be a horizontal kettle.