EP2570542A1

EP2570542A1 - Sewing machine

Info

Publication number: EP2570542A1
Application number: EP12184525A
Authority: EP
Inventors: Mitsuhiro Yoshihira
Original assignee: Juki Corp
Current assignee: Juki Corp
Priority date: 2011-09-15
Filing date: 2012-09-14
Publication date: 2013-03-20
Anticipated expiration: 2032-09-14
Also published as: CN102995309A; JP2013059577A; EP2570542B1; JP5925451B2; CN102995309B

Abstract

A sewing machine (100) includes a cloth feeding mechanism (20) configured to feed a workpiece (CU, CD) in a cloth feeding direction, a lateral-feeding mechanism (30, 36) configured to move the workpiece (CU, CD) in a seam allowance direction (X), cloth edge detection means (40, 60) for detecting a side edge portion of the workpiece (CU, CD) along the cloth feeding direction (Y), a controller (13) configured to control the lateral-feeding mechanism (30, 36) to control a seam allowance of the workpiece (CU, CD). The cloth edge detection means (40, 60) includes a light source (431, 631) for irradiating a reflector plate (12), a detector (45, 65) having a plurality of light receiving devices arranged along the seam allowance direction (X) to receive the light reflected by the reflector plate (12) and optical means (44, 64, 632) for collimating the light emitted by the light source (431, 631) and for directing the collimated light in a direction orthogonal to the seam allowance direction (X) and inclined with respect to the cloth feeding direction (Y) toward the reflector plate (12) to irradiate the reflector plate (12) over a range along the seam allowance direction (X).

Description

The present invention relates to a sewing machine configured to detect a position of a side edge portion of a workpiece and to control a seam allowance of the workpiece.
A related sewing machine, as disclosed in JP11-033255A for example, is configured to feed upper and lower cloths such that the respective edges on one side along the cloth feeding direction are aligned with each other to sew the cloths together by forming a seam with a certain distance (seam allowances) from the aligned edges of the cloths. Fig. 18 illustrates such a conventional sewing machine 100 configured to sew an upper cloth U and a lower cloth D together such that the seam allowances of the respective cloths are the same. The sewing machine 100 includes a feed dog and a presser foot 105 that cooperate to feed the upper cloth U and the lower cloth D along a cloth feeding direction F, upper and lower lateral-feeding mechanisms 102 (only the upper mechanism is illustrated) for feeding, on the upstream of a sewing needle 101 in the cloth feeding direction F, the upper cloth U and the lower cloth D individually in a direction orthogonal to the cloth feeding direction F by rollers 104 that rotate around their respective axes along the cloth feeding direction F, and cloth detecting units 110 (only the upper unit is illustrated) for detecting the positions of the side edge portions G along the cloth feeding direction F of the upper cloth U and the lower cloth D, respectively, between the feed dog and the lateral-feeding mechanisms 102. Based on the detected positions of the side edge portions G, the upper and lower lateral-feeding mechanisms 102 moves the upper and lower cloths U, D individually in the X direction so that the side edge portions G of the upper and lower cloth U, D are aligned with each other during the sewing operation. In the drawings, the Y-axis direction is a horizontal and parallel to the cloth feeding direction F, the X-axis direction is horizontal and orthogonal to the Y-axis direction, and the Z-axis direction is the vertical direction.
As disclosed in JP06-335582A , some sewing machines use line sensors (image sensors) as cloth detecting units. For example, as shown in Fig. 19, an example of the cloth detecting unit 110 includes a reflector plate 103 on which an edge portion of an upper cloth U is placed, a light source 111 that irradiates the reflector plate 103 with detection light, a lens 112 that forms the detection light into a slit light along a direction (the X-axis direction) orthogonal to the cloth feeding direction F, a line sensor 113 (an image sensor) that receives the detection light reflected by the reflector plate 103 or by the upper cloth U, and a lens 114 that forms an image of the reflected detection light on the line sensor 113.
As shown in Fig. 20, the line sensor 113 includes a plurality of light receiving devices arranged in a row along the X-axis direction, and detects the position of the side edge portion of the upper cloth U based on changes in intensity of light received by each of the light receiving devices. The changes are caused when the detection light toward the reflector plate 103 is blocked by the side edge portion of the upper cloth U.
The cloth detecting unit for the lower cloth D has a similar configuration as the cloth detecting unit for the upper cloth U.
When the positions of the side edge portions of the upper cloth U and the lower cloth D detected by the cloth detecting units 110 are not aligned with each other, the lateral-feeding mechanisms 102 are controlled such that the side edge portions are aligned with each other.
However, according to the cloth detecting units 110 of the sewing machine 100 described above, the light source 111 emits diffusion light, which may cause following problems.
As shown in Fig. 20, when the upper cloth U floats from the reflector plate 103 or when the upper cloth U is thick, the upper surface of the upper cloth U is displaced upward from the reflector plate 103. Accordingly, an incident angle (or an incident position) on the reflector plate 103 with regard to a light ray emitted by the light source 111 and touching the upper edge of the side edge portion G of the upper cloth U changes (see the dotted line in Fig. 20), whereby a detection position P12 on the line sensor 113 is detected as being corresponding to the position of the side edge portion G of the upper cloth U with respect to the X-axis direction. However, this detection position P12 is different from the detection position P11 that corresponds to the actual position of the side edge portion G of the upper cloth U with respect to the X-axis direction. Therefore, the position of the side edge portion G with respect the X-axis direction cannot be detected accurately. Similarly, with the cloth detecting unit 120 for the lower cloth D, when the lower cloth D is displaced upward from the lower cloth detection surface 104, a detection position P22 on the line sensor 123 is detected, and this position P22 is different from the detection position P21 that corresponds to the actual position of the side edge portion G of the lower cloth D with respect to the X-axis direction. Thus, the position of the side edge portion G with respect the X-axis direction cannot be detected accurately.
Further, the cloth detecting units 110, 120 for the upper and lower cloths U, D are configured such that the optical axes of the respective light sources 111, 121 are oriented primarily in the up-down direction, so that it is structurally difficult to reduce the size of the cloth detecting unit 110, 120 in the up-down direction. The cloth detecting unit 110 for the upper cloth U is disposed in a narrow space between the lateral-feeding mechanism 102 and the cloth presser, so it is desirable to downsize the cloth detecting unit 110 in the up-down direction. The cloth detecting unit 120 for the lower cloth D, on the other hand, is disposed in a space below the throat plate such that the upper surface of the throat plate and the lower cloth detection surface 104 are in the same level and, below the throat plate, a feed dog mechanism and a thread cutting mechanism, etc., are provided compactly. Therefore, also for the cloth detecting unit 120, it is desirable to downsize in the up-down direction.
An object of the present invention is to accurately detect a position of a side edge portions of a workpiece and/or to downsize a cloth detecting unit in the up-down direction.
According to an aspect of the present invention, a sewing machine comprises a cloth feeding mechanism configured to feed a workpiece in a cloth feeding direction along a horizontal plane, a lateral-feeding mechanism configured to move the workpiece in a seam allowance direction parallel to the horizontal plane and orthogonal to the cloth feeding direction, cloth edge detection means for detecting a side edge portion of the workpiece, the side edge portion extending along the cloth feeding direction, and a controller configured to control the lateral-feeding mechanism based on the detection by the cloth edge detection means to control a seam allowance of the workpiece. The cloth edge detection means comprises a reflector plate disposed to overlap, in the vertical direction orthogonal to the horizontal plane, with the side edge portion of the workpiece that is being fed in the cloth feeding direction, a light source configured to emit light to irradiate the reflector plate and the side edge portion of the workpiece that is being fed in the cloth feeding direction, and a detector including a plurality of light receiving devices arranged along the seam allowance direction to receive the light reflected by the reflector plate. The cloth edge detection means further includes optical means for collimating the light emitted by the light source and for directing the collimated light in a direction orthogonal to the seam allowance direction and inclined with respect to the cloth feeding direction toward the reflector plate to irradiate the reflector plate and the side edge portion of the workpiece over a range along the seam allowance direction.
According to another aspect of the present invention, the optical means includes a first optical element configured to collimate the light emitted by the light source, and a second optical element configured to direct the collimated light in the direction orthogonal to the seam allowance direction.
According to another aspect of the present invention, the light source and the first optical element are arranged in the seam allowance direction, and the second optical element is configured to reflect the light from the first optical element toward the reflector plate.
According to another aspect of the present invention, the cloth edge detection means further includes a slit extending along the seam allowance direction, wherein the light passes through the slit to irradiate the reflector plate and the side edge portion of the workpiece.
According to another aspect of the present invention, the light source and the first optical element form a light source unit, and are disposed to output the collimated light in a direction inclined with respect to all of the vertical direction, the cloth feeding direction and the seam allowance direction. The second optical element has a reflecting surface that reflects the collimated light toward the reflector plate, wherein the reflecting surface is inclined with respect to all of the vertical direction, the cloth feeding direction and the seam allowance direction.
According to another aspect of the present invention, the direction in which the reflecting surface of the second optical element reflects the collimated light is inclined with respect to the vertical direction.
According to one or more aspects of the present invention, as a result of the irradiation of the reflecting surface with the collimated light (parallel light) in the direction described above, even when an irradiated surface of the workpiece is displaced away from the reflecting surface of the reflector due to the thickness of the workpiece or a gap between the workpiece and the reflecting surface, the side edge portion of the workpiece does not interfere with the required reflected light.
Therefore, the position of the side edge portion of the workpiece with respect to the seam allowance direction can be accurately obtained, so that the side edge portion of the workpiece can be accurately controlled to be at a target position, whereby sewing quality is improved.
According to one or more aspects of the present invention, the limitation on the arrangement of the light source and the first and second optical elements can be eliminated, so that they can be arranged in a direction that is advantageous for downsizing the cloth detecting unit in the up-down direction. Therefore, the thickness of the cloth detecting unit in the up-down direction can be reduced, so that the cloth detecting unit can be easily arranged in a narrow space below the throat plate or a narrow space between the lateral-feeding mechanism and the needle bar, whereby the cloth detecting unit can be easily installed, and the sewing machine can be downsized.
As the lateral-feeding mechanism becomes to closer to a stitching point, the seam allowance can be controlled more accurately to have a target width. By downsizing the cloth edge detecting unit in the vertical direction as described above, it becomes easier to arrange the lateral-feeding mechanism at a position closer to the stitching point, whereby the seam allowance can be adjusted with improved accuracy to provide improved sewing quality.
According to one or more aspects of the present invention, the cloth edge detecting unit can be downsized in the cloth feeding direction as well as in the up-down direction, which makes it possible to arrange the lateral-feeding mechanism at a position even closer to the stitching point, whereby the seam allowance can be adjusted with further improved accuracy to provide improved sewing quality.
According to one or more aspects of the present invention, irradiation light for irradiating the workpiece is in a form of a slit along the seam allowance direction, so that the position of the side edge portion of the workpiece can be easily and accurately obtained from a change in length of reflected irradiation light.
Other aspects and advantages of the present invention will be apparent from the following description, drawings, and the claims.
The following description of embodiments of the present invention describes the present invention in greater detail with reference to the drawings including:

Fig. 1:: a perspective view of a portion of an upper and lower feed sewing machine according to a first embodiment of the present invention;
Fig. 2:: a diagram illustrating a configuration of a portion of the upper and lower feed sewing machine viewed from the front side of the upper and lower feed sewing machine;
Fig. 3:: a perspective view of an upper detecting unit and a lower detecting unit;
Fig. 4:: a bottom perspective view of the lower detecting unit obliquely from below;
Fig 5:: a top perspective view of the lower detecting unit obliquely from above;
Fig. 6:: a plan view of the lower detecting unit;
Fig. 7:: a sectional view taken along the line V-V in Fig. 6;
Fig. 8:: a sectional view taken along the line U-U in Fig. 3;
Fig. 9:: a sectional view taken along the line T-T in Fig. 3;
Fig. 10:: a sectional view showing an internal structure of a light source unit;
Fig. 11:: a diagram illustrating an inclination angle of a reflecting surface of a reflector;
Fig. 12A:: a diagram illustrating an incident angle of irradiation light irradiating the reflector plate as viewed from the Y-axis direction;
Fig. 12B:: a diagram illustrating an incident angle of the irradiation light irradiating the reflector plate as viewed from the X-axis direction;

Fig. 13:: a top perspective view of the upper detecting unit;
Fig. 14:: a bottom perspective view of the upper detecting unit;
Fig. 15:: a block diagram illustrating a control system of the upper and lower feed sewing machine;
Fig. 16:: a sectional view taken along the Y-Z plane, illustrating upper and lower detecting units according to a second embodiment of the present invention;
Fig. 17:: a sectional view taken along the Y-Z plane, illustrating upper and lower detecting units according to a third embodiment of the present invention;
Fig. 18:: a plan view of a portion of a conventional sewing machine;
Fig. 19:: a sectional view of a conventional cloth detecting unit taken along the line W-W in Fig. 18;
Fig. 20:: a diagram illustrating the conventional cloth detecting unit as viewed from the downstream side in the cloth feeding direction;
Fig. 21A:: a perspective view of the reflector according to the first embodiment; and
Fig. 21B:: another perspective view of the reflector according to the first embodiment.

In the following description, a Y-axis direction is a direction along the horizontal plane, an X-axis direction is a direction orthogonal to the Y-axis direction and parallel to the horizontal plane, and a Z-axis direction is a vertical direction orthogonal to the Y-axis and X-axis directions.
With regard to the Y-axis and X-axis directions, the signs "+" and "-" shown in the respective drawings denote "forward" and "backward", respectively. For example, lateral-feeding mechanisms 30, 36, which will be described later, can move an upper cloth CU and a lower cloth CD forward and backward in the X-axis direction. In Fig. 1, for example, the X-axis forward direction is a direction toward the right and the X-axis backward direction is a direction toward the left.
First Embodiment
An upper and lower feed sewing machine 100 (an example of a sewing machine) according to a first embodiment performs sewing control to sew an upper cloth CU and a lower cloth CD together so that the side edge portions (the right edge portions in Fig. 1) of the upper cloth CU and the lower cloth CD are aligned with each other and seam allowances are provided to have target widths while feeding the upper cloth CU and the lower cloth CD placed on a throat plate 14 to overlap each other in the Y-axis direction (cloth feeding direction).
As shown in Fig. 1 and Fig. 2, the upper and lower feed sewing machine 100 includes a needle bar mechanism that moves up and down a needle bar (not illustrated) holding a sewing needle N by a known configuration, a cloth feeding mechanism 20 that feeds the upper cloth CU and the lower cloth CD in the cloth feeding direction (Y-axis forward direction) at the time of sewing, an upper lateral-feeding mechanism 30 that is positioned on the upstream side in the cloth feeding direction with respect to the up-down moving position of the sewing needle N, and moves the upper cloth CU forward and backward in a seam allowance direction (X-axis direction), a lower lateral-feeding mechanism 36 that is disposed below the upper lateral-feeding mechanism 30 across a cloth feeding path and moves the lower cloth CD forward and backward in the seam allowance direction (X-axis direction), a partition plate 11 that separates the upper cloth CU and the lower cloth CD to prevent these from interfering with each other during the lateral feeding operations, cloth detecting units 40, 60 provided between the up-down movement position of the sewing needle N and the upper lateral-feeding mechanism 30 and the lower lateral-feeding mechanism 36, a known shuttle mechanism not illustrated that forms a seam in cooperation with the sewing needle N below the throat plate 14, and a controller 13 that controls these components. The upper lateral-feeding mechanism 30 and the lower lateral-feeding mechanism 36 form a lateral-feeding mechanism.
Cloth Feeding Mechanism
As shown in Fig. 2, the cloth feeding mechanism 20 includes a feed dog 21 that is provided below the throat plate 114 and makes elliptic motion counterclockwise in Fig. 2 along the Y-axis direction to come out from and sink into the opening of the throat plate 14, a feed foot 22 that is provided above the throat plate 14 and makes elliptic motion clockwise in Fig. 2 along the Y-axis direction, and an operation transmission mechanism not illustrated that applies up-down movement or elliptic motion to the feed dog 21 and the feed foot 22.
Both of the feed dog 21 and the feed foot 22 obtain power from the sewing machine main shaft (not illustrated) that is driven by a sewing machine motor 15 (refer to Fig. 15) as a driving source of a needle bar up-down movement mechanism and the shuttle mechanism.
Specifically, to the feed dog 21, up-down and back-and-forth reciprocating movements are applied synchronously by a transmission mechanism that converts rotation of the sewing machine main shaft according to the sewing machine motor 15 into up-down reciprocating movement and back-and-forth reciprocating movement, and accordingly, the feed dog 21 can be caused to make elliptic motion counterclockwise in Fig. 2.
On the other hand, to the feed foot 22, up-down and back-and-forth reciprocating movements are applied synchronously by the transmission mechanism that converts rotation of the sewing machine main shaft into up-down reciprocating movement and back-and-forth reciprocating movement, and accordingly, the feed foot 22 is caused to make elliptic motion clockwise in Fig. 2.
The elliptic motions of the feed dog 21 and the feed foot 22 become movements relative to each other so that the feed foot 22 is in a moving-down section when the feed dog 21 is in a moving-up section. Therefore, the feed dog 21 and the feed foot 22 perform a cloth feeding operation toward the downstream side in the cloth feeding direction (Y-axis forward direction) in a section in which they sandwich the upper cloth CU and the lower cloth CD on the throat plate 14 during their elliptic motions.
Cloth Presser
The cloth presser 23 is supported on a sewing machine arm portion frame AF movably up and down, and supported on the lower end of a presser bar (not illustrated) to which a downward elastic force is always applied. To this presser bar, the rotation of the sewing machine main shaft is converted into up-down movement and transmitted, and the presser bar rises against the elastic force in an operation section in which the feed foot 22 and the feed dog 21 perform a cloth feeding operation, and lowers in an operation section in which a cloth feeding operation is not performed and moves up and down so as to come into pressure contact with the upper surface of the throat plate 14 by the elastic force.
Instead of the type described above that moves up and down in synchronization with the sewing machine main shaft, the cloth presser 23 may be a normal type that is supported on the frame AF of the head portion of the sewing machine movably up and down so as to face the upper side of the feed dog 21 and presses the upper cloth CU and the lower cloth CD against the throat plate 14 by the elastic force.
Partition Plate
The partition plate 11 is a flat plate long in the X-axis direction, and is supported in a cantilevered manner by a sewing machine bed portion BF at an end portion in the X-axis forward direction.
The partition plate 11 is disposed to separate from the sewing machine bed portion BF and the upper surface of the throat plate 14 so as to allow the lower cloth CD to pass through, and makes the upper cloth CU and the lower cloth CD pass through above and below the partition plate.
Upper Lateral-Feeding Mechanism
The upper lateral-feeding mechanism 30 includes an arm 32 supported by a base 35 so as to oscillate in the up-down direction around the base end, an upper roller 31 that is supported by the distal end of the arm 32 rotatably around an axis along the cloth feeding direction, and comes into contact with the upper surface of an upper cloth CU on the partition plate 11 and moves the upper cloth in the X-axis direction, an upper solenoid 33 (see Fig. 15) that oscillates the arm 32 to adjust a force of pressure contact of the upper roller 31 with the upper cloth CU, and an upper pulse motor 34 (see Fig. 15) that applies forward/reverse rotation to the upper roller 31 by a driving belt disposed on the inner side of the arm 32.
The base 35 is supported on the upper surface of the sewing machine bed portion BF. The arm 32 extends toward the distal end of the sewing machine bed portion BF (X-axis backward direction) from the base 35 whose position is adjustable along the X-axis direction.
The upper solenoid 33 moves up and down the upper roller 31 on the distal end side by turning the arm 32 by electric current control. Then, by moving down the upper roller 31, the upper solenoid makes the upper roller come into pressure contact with the upper cloth CU on the partition plate 11, and further, by rotating the upper roller 31 by the upper pulse motor 34, moves the upper cloth CU forward and backward in the X-axis direction (lateral feeding direction). By this lateral feeding operation, the size of the seam allowance corresponding to the distance from a side edge portion (an edge portion in the X-axis forward direction) along the cloth feeding direction of the upper cloth CU to the stitching point can be changed optionally.
By positional adjustment in the up-down direction of the upper roller 31 by the upper solenoid 33, the force of pressure contact of the upper roller 31 with the upper cloth CU can be properly adjusted according to the cloth thickness.
Lower Lateral-Feeding Mechanism
As shown in Fig. 2, the lower lateral-feeding mechanism 36 is disposed inside the sewing machine bed portion BF, and includes a lower roller 37 that comes into contact with the lower surface of the lower cloth CD to be conveyed by the cloth feeding mechanism 20 on the upper surface of the sewing machine bed portion BF and moves the lower cloth in the X-axis direction.
Similar to the upper lateral-feeding mechanism 30, the lower lateral-feeding mechanism 36 includes an arm (not illustrated) that supports the lower roller 37 by the distal end portion, a lower solenoid 38 that adjusts the force of pressure contact of the lower roller 37 with the lower cloth CD by oscillating the arm, and a lower pulse motor 39 that applies forward/reverse rotation to the lower roller 37.
When the lower roller 37 comes into pressure contact with the lower cloth CD passing through the side below the partition plate 11 from below and rotates forward/reverse, the lower cloth CD can be moved forward and backward in the X-axis direction. The force of pressure contact of the lower roller 37 with the lower cloth CD is properly adjustable according to the cloth thickness. To enable the lower roller 37 to come into contact with the lower cloth CD from the lower side of the sewing machine bed portion BF, a through-hole not shown is formed in the sewing machine bed portion BF.
Cloth Detecting Unit
The cloth detecting unit is formed by integrally coupling an upper detecting unit 40, a lower detecting unit 60, and a reflector plate 12 formed of a thin metal plate whose both upper and lower surfaces are lustrous, and is fixed to the sewing machine bed portion BF.
Each of the upper detecting unit 40 and the lower detecting unit 60 includes a cloth edge detection means that detects a side edge portion along the cloth feeding direction of the upper cloth CU or lower cloth CD, and a cloth presence detection means that detects whether the upper cloth CU or lower cloth CD is present at a detection position of the cloth edge detection means.
Further, each of the upper detecting unit 40 and the lower detecting unit 60 includes a base 41, 61 as a housing that supports the cloth edge detection means and the cloth presence detection means inside, and a cover 42, 62 that covers the upper surface or lower surface of the base 41, 61.
The upper detecting unit 40 including the cover 42 fixed to the upper portion of the base 41 and the lower detecting unit 60 including the cover 62 fixed to the lower portion of the base 61 are fixed so as to overlap in the up-down direction across the reflector plate 12. The upper detecting unit 40 and the lower detecting unit 60 have end portions in the X-axis backward direction that are opened in a U shape in a state where these detecting units are coupled, and in this opening, the reflector plate 12 is sandwiched in a state where its reflecting surfaces on the surface side and the back surface side are along the X-Y plane.
The base 61 has a substantially rectangular parallelepiped shape along the X-axis direction as a whole, and in a base end portion in the X-axis forward direction thereof, an attaching hole 611 for screwing to the frame of the sewing machine bed portion BF is formed to perforate through the base end portion in the up-down direction, and on the distal end portion in the X-axis backward direction, a stepped portion 612 lower than the base end portion upper surface is formed. The upper surface of this stepped portion 612 is parallel to the X-Y plane, and is a predetermined distance below the lower reflecting surface of the reflector plate 12 and faces the lower reflecting surface when the base is assembled.
The base 41 includes a stepped portion 412 that is a predetermined distance above the upper reflecting surface of the reflector plate 12 and faces the upper reflecting surface, and the base 41 is fixed and supported onto the base 61 by a screw not illustrated.
The lower cloth edge detection means provided in the lower detecting unit 60 includes a light source unit 63 configured to emit collimated irradiation light, a reflector 64 serving as a second optical element (an example of optical means) that reflects the irradiation light from the light source unit 63 toward the lower reflecting surface of the reflector plate 12, and a linear sensor 65 as a detector that receives a reflected image on the reflector plate 12 based on the irradiation light from the light source unit 63.
The light source unit 63 includes a light emitting diode (LED) 631 serving as a light source that emits light (diffusion light) for irradiating a side edge portion of the lower cloth CD (workpiece) being fed in the cloth feeding direction and the reflecting surface of the reflector plate 12, a biconvex lens 632 serving as a first optical element (an example of optical means) configured to collimate diffusion light emitted by the LED 631 to obtain parallel light, and a casing 633 that holds these components.
The LED 631 is an infrared LED, and irradiates infrared rays.
The casing 633 holds the LED 631 and the lens 632 so that the LED 631 is positioned on the optical axis of the lens 632 and the distance between these components enables conversion of diffusion light from the LED 631 into parallel light.
The first optical element may not necessarily be a biconvex lens, in so far as it can collimate the diffusion light to obtain parallel light.
The light source unit 63 is inserted and held in a fitting recess 61 formed by notching the upper surface of the intermediate portion of the base 61 so that the entire light source unit sinks into the fitting recess.
The light source unit 63 is disposed so that the parallel light irradiation direction is inclined at an angle θ1 clockwise, that is, toward the downstream side in the cloth feeding direction (Y-axis forward direction side) with respect to the seam allowance direction (X-axis direction) in a plan view, and inclined at an angle θ2 (acute angle) clockwise, that is, by directing the X-axis backward direction side downward in a side view from the downstream side in the cloth feeding direction as shown in Fig. 7.
The angle θ1 enables arrangement of the light source unit 63 and the reflector 64 along the diagonal line of a rectangular shape that is the housing shape of the lower detecting unit 60 in a plan view, and accordingly, it becomes possible to reduce the size in the width direction (Y-axis direction) of the casing (the base 61 and the cover 62) of the lower detecting unit 60 and downsize the device.
The angle θ2 enables arrangement of the light source unit 63 and the reflector 64 along the diagonal line of the rectangular shape that is the casing shape of the lower detecting unit 60 in a side view, and accordingly, it becomes possible to reduce the size in the up-down direction (Z-axis direction) of the casing (the base 61 and the cover 62) of the lower detecting unit 60 and downsize the device.
A space is formed between the lower surface of the stepped portion 612 of the base 61 and the cover 62, and this space serves as a space for holding the reflector 64 and the linear sensor 65. In a standing portion 61a of the base 61 positioned between the recess 613 and the stepped portion 612, a vertically-long slit (light guiding portion) 615 through which parallel light irradiated by the light source unit 63 passes through is formed, and in the upper surface of the stepped portion 612, a horizontally-long slit (light transmitting portion) 616 is formed along the seam allowance direction (X-axis direction) continuously from the slit 615. The slit 615 is formed along a straight line inclined to widen downward at an angle θ3 toward the Y-axis forward direction side with respect to the Z-axis direction as shown in Fig. 8, and the slit 616 is formed on the same straight line.
As shown in Fig. 4, the reflector 64 and the linear sensor 65 are fixed to the lower surface of the stepped portion 612. On the stepped portion 612, the reflector 64 is positioned on the downstream side in the cloth feeding direction of the linear sensor 65.
The reflector 64 is disposed so that the reflecting surface 641 as a mirror surface which is three-dimensionally inclined is directed toward the light source unit 63 as shown in Figs. 21A and 21B.
As shown in Fig. 8, the reflector 64 reflects parallel light from the light source unit 63 so that the parallel light is made incident on the lower reflecting surface of the reflector plate 12 from below at an angle θ3 inclined toward the Y-axis forward direction side with respect to the Z-axis direction.
The lower reflecting surface of the reflector plate 12 reflects the irradiation light (parallel light) reflected by the reflector 64 at an angle θ3 inclined toward the Y-axis backward direction side with respect to the Z-axis direction by regular reflection so that the irradiation light is received by the linear sensor 65 positioned below.
The inclination angle around the X axis of the light guiding portion 615 is adjusted so that, when the parallel light of the light source unit 63 passes through the light guiding portion 615 and is reflected by the reflecting surface 641 described later of the reflector 64 and projected as slit light on the lower reflecting surface of the reflector plate 12, the longitudinal direction of the slit light becomes parallel to the X-axis direction.
The reflecting surface 641 of the reflector 64 is described with reference to Fig. 11.
The lower detecting unit 60 is designed to accurately detect a position in the X-axis direction of the side edge portion in the X-axis forward direction of the lower cloth CD even when the lower cloth CD is thick in thickness or a clearance occurs between the reflector plate 12 and the lower cloth CD.
If the lower surface of the lower cloth CD is different in height from the lower reflecting surface of the reflector plate 12, in a conventional sewing machine, a part of the reflected light reflected by the lower reflecting surface that indicates the position in the X-axis direction of the side edge portion of the lower cloth CD is blocked by the lower cloth CD, and this causes an error of the position in the X-axis direction of the side edge portion of the lower cloth CD. On the other hand, in the lower detecting unit 60, even when the lower surface of the lower cloth CD is different in height from the lower reflecting surface of the reflector plate 12, by irradiating parallel light from a direction in which reflected light reflected by the lower reflecting surface is not blocked by the lower cloth CD, the problem is solved.
Specifically, the direction of irradiation of the parallel light on the reflector plate 12 is parallel to the Y-Z plane. In this case, the parallel light to be irradiated may be inclined around the X axis.
On the other hand, as shown in Figs. 6 and 7, the light source unit 63 has an optical axis (parallel light advancing direction) that is inclined at an angle θ1 around the Z axis and at an angle θ2 around the Y axis with respect to the X-axis backward direction. The light reflected by the reflecting surface 641 of the reflector 64 is made incident on the lower reflecting surface of the reflector plate 12 from below at an angle inclined at θ3 around the X axis with respect to the Z-axis direction.
Therefore, the reflecting surface 641 of the reflector 64 is designed to be a three-dimensionally inclined surface determined by the inclination angles θ1, θ2, and θ3 such that the parallel light is directed in a direction parallel to the Y-Z plane and inclined at the angle θ3 with respect to the Z-axis direction at any position along the seam allowance direction (X-axis direction) to irradiate the reflecting surface of the reflector plate 12. Specifically, the reflecting surface 641 of the reflector 64 is inclined with respect to all of the X-axis direction, the Y-axis direction, and the Z-axis direction.
In Fig. 11, the position of the light source unit 63 is defined as point A, the position on which parallel light from the light source unit 63 is irradiated on the flat surface of the reflecting surface 641 of the reflector 64 is defined as point B, and the position on which reflected light from the reflecting surface 641 is irradiated on the lower reflecting surface of the reflector plate 12 is defined as point C.
The unit direction vector of the line segment BA can be obtained from the above-described inclination angles θ1 and θ2.
The unit direction vector of the line segment BC can be obtained based on the above-described inclination angle θ3 and the fact that this unit direction vector is parallel to the Y-Z plane.
A plane whose normal is the direction vector B obtained by synthesizing the unit direction vector of the line segment BA and the unit direction vector of the line segment BC is the reflecting surface 641.
Parallel light output from the light source unit 63 is projected as slit light along the X-axis direction on the lower reflecting surface of the reflector plate 12 at an intermediate position in the Y-axis direction of the base 61 by being reflected by the reflecting surface 641 set at the inclination angle. The parallel light is irradiated in a direction parallel to the Y-Z plane, that is, orthogonal to the X-axis direction (the seam allowance direction), and inclined with respect to the Y-axis direction (the cloth feeding direction) toward the reflector plate 12, and is made incident on the lower reflecting surface of the reflector plate 12 in a direction inclined at the angle θ3 around the X-axis direction (clockwise as viewed in the X-axis forward direction) with respect to the vertical direction and over a certain range along the X-axis direction (the seam allowance direction).
When the parallel light irradiating the reflector plate 12 is parallel to the Y-Z plane, as shown in Fig. 12A, the position E in the X-axis direction of the side edge portion of the lower cloth CD projected on the lower reflecting surface of the reflector plate 12 does not deviate. Specifically, the lower detecting unit 60 can accurately detect the position in the X-axis direction of the side edge portion of the lower cloth CD. The same also applies to the case where the lower cloth CD is thick in thickness or the lower cloth CD separates from the lower reflecting surface.
The parallel light irradiated on the lower cloth CD and the reflector plate 12 is inclined at the angle θ3 around the X axis as shown in Fig. 12B, however, this does not influence the position E in the X-axis direction of the side edge portion of the lower cloth CD projected on the lower reflecting surface of the reflector plate 12.
A linear sensor 65 is provided at the end in the advancing direction of reflected light of the parallel light to be irradiated on the lower reflecting surface of the reflector plate 12. Specifically, at the end in a direction inclined at θ3 around the X axis (counterclockwise as viewed in the X-axis forward direction) with respect to the vertical downward direction parallel to the Y-Z plane from the irradiation position of the parallel light on the lower reflecting surface, the linear sensor 65 is disposed.
The linear sensor 65 is attached to the stepped portion 612 of the base 61 in a state where the linear sensor is inclined so that a light receiving surface of the linear sensor becomes orthogonal to the advancing direction of reflected light from the lower reflecting surface of the reflector plate 12.
The light receiving surface of the linear sensor 65 is a rectangular plane whose longitudinal direction is in the X-axis direction, and includes a plurality of light receiving devices arranged along the X-axis direction and spread to be planate to cover the light receiving surface.
On the light receiving surface of the linear sensor 65, a visible light cut filter is provided to block reception of visible light, etc., other than infrared rays.
Slit-like parallel light along the X-axis direction, irradiated on the lower reflecting surface of the reflector plate 12, is reflected and projected in a slit-like shape along the X-axis direction on the light receiving surface of the linear sensor 65.
For example, the lower cloth CD is present below the reflector plate 12, a part in the X-axis direction of the parallel light irradiated on the lower reflecting surface of the reflector plate 12 is blocked by the side edge portion of the lower cloth CD, so that the slit-like reflected light differs in light intensity at a position corresponding to the side edge portion of the lower cloth CD in the longitudinal direction of the reflected light. The linear sensor 65 is formed by arranging light receiving devices along the X-axis direction, so that based on a difference in light intensity detected by each light receiving device, the position corresponding to the side edge portion of the lower cloth CD can be identified, and accordingly, the position in the X-axis direction of the side edge portion of the lower cloth CD can be obtained.
The cloth presence detection means that detects an edge portion in the cloth feeding direction of the lower cloth CD includes an LED 66 serving as a light source for light irradiation for detecting whether the lower cloth CD is present, and a light receiving LED 67 that receives reflected light reflected by the reflector plate 12 based on irradiation light from the LED 66.
As shown in Figs. 6, 7 and 9, the LED 66 for detecting whether the lower cloth CD is present and the light receiving LED 67 that receives reflected light from the LED are held between the stepped portion 612 of the base 61 and the cover 62 similar to the above-described reflector 64 and a linear sensor 65.
The LED 66 and the light receiving LED 67 are disposed closer to the X-axis backward direction side than the reflector 64 and the linear sensor 65. Specifically, these are provided near the outside of the U-shaped opening on the X-axis backward direction side formed by the upper detecting unit 40 and the lower detecting unit 60. These LEDs are used to detect that the distal end edge of the lower cloth CD conveyed by the cloth feeding mechanism 20 when starting sewing has reached a position between the reflector plate 12 and the stepped portion 612, and detect that the terminal end of the lower cloth CD has passed through the portion between the reflector plate 12 and the stepped portion 612 when the conveyance is ended.
As shown in Fig. 9, the LED 66 is disposed so as to be parallel to the Y-Z plane and inclined at θ3 clockwise around the X axis as viewed in the X-axis forward direction with respect to the vertical upward direction.
The light receiving LED 67 is disposed so as to be parallel to the Y-Z plane and inclined at θ3 counterclockwise around the X axis as viewed in the X-axis forward direction with respect to the vertical upward direction.
Irradiation light from the LED 66 is reflected on an intermediate position in the Y-axis direction of the base 61 on the lower reflecting surface of the reflector plate 12, and the reflected light is received by the light receiving LED 67.
The LED 66 is a point light source that emits diffusion light, and the LED 66 is disposed behind a light transmitting portion 618 formed by penetrating through the stepped portion 612 in the up-down direction, so that the light transmitting portion 618 serves as a diaphragm, and similarly, the light receiving LED 67 is disposed behind an incidence hole 619 formed by perforating through the stepped portion 612 in the up-down direction, and the incidence hole 619 serves as a diaphragm, so that the irradiation light from the LED 66 is not directly received by the light receiving LED 67.
As shown in Figs. 3, 8, 9, 13 and 14, the upper detecting unit 40 is substantially equal to a state where the lower detecting unit 60 is turned upside down by being rotated 180 degrees around the X axis, and includes the base 41, the cover 42, the light source unit 43, the reflector 44, the linear sensor 45, the LED 46, and the light receiving LED 47 that have substantially the same structures as those of the lower detecting unit 60. Thus, the upper detecting unit 40 is substantially the same as the lower detecting unit 60 except that only the orientation is different, so that only the difference is described.
The base 41 includes, similar to the base 61, a stepped portion 412, a fitting recess 413, a light guiding portion 415, light transmitting portions 416 and 418, and incidence holes 417 and 419, however, unlike the base 61, on the bottom surface portion of the base 41, a rectangular recess 414 (see Fig. 14) in which the reflector plate 12 fits is formed. The upper detecting unit 40 is supported on the sewing machine frame integrally with the lower detecting unit 60, so that unlike the base 61, the attaching hole 611 is not provided.
The upper detecting unit 40 is supported on the sewing machine frame in a state where it is reversed 180 degrees around the X axis and turned downward, so that when it is viewed in the X-axis direction as shown in Fig. 8, the upper detecting unit has a positional relationship in which the reflector 44 and the linear sensor 45 of the upper detecting unit 40 become symmetrical to the reflector 64 and the linear sensor 65 of the lower detecting unit 60 about the center point C between them. The center point C indicates a center position in the Y-axis direction and the Z-axis direction in a state where the upper detecting unit 40 and the lower detecting unit 60 are joined integrally.
With the above-described configuration, the upper detecting unit 40 detects the position in the X-axis direction of the side edge portion of the upper cloth CU and detects whether the upper cloth CU is present in the same manner as the lower detecting unit 60.
Controller
As shown in Fig. 15, the controller 13 includes a CPU 131 that performs various arithmetic processings, a ROM 132 in which programs relating to operation controls of the above-described components are stored, a RAM 133 for storing various data relating to processing of the CPU 131 in a work area, and an EEPROM 134 as a storage section that records various setting data and accumulated data, etc.
To the controller 13, the sewing machine motor 15 for moving up and down the sewing needle, upper and lower pulse motors 34, 39, and upper and lower solenoids 33, 38 are connected via drive circuits 15a, 33a, 39a, 34a, 38a, respectively.
Further, to the controller 13, the lower detecting unit 60 and the upper detecting unit 40 are connected via interfaces 60a, 40a, respectively. The linear sensors 65 and 45 output detection signals in analog form, so that each of the interfaces 60a, 40a of the detecting units 60, 40 includes an A/D converter, and the controller 13 can obtain digitized detection data.
The sewing machine main shaft not illustrated to be driven to rotate by the sewing machine motor 15 is provided with an encoder 16 that detects a shaft angle thereof, and outputs a detected shaft angle to the controller 13 via the interface 16a.
Further, the upper and lower feed sewing machine 100 includes an operation panel 17 for inputting various settings and displaying various information, and this operation panel 17 is also connected to the controller 13 via an interface 17a.
Sewing Control
The controller 13 controls sewing operation of the upper and lower feed sewing machine 100 according to a control program. In sewing control for the upper cloth CU and the lower cloth CD, common description is omitted, and here, control for the lower cloth CD is mainly described.
First, the controller 13 turns the LEDs 631, 66 on when sewing. Accordingly, slit-like parallel light is output from the light source unit 63 and reflected by the reflecting surface 641 of the reflector 64 to irradiate the lower reflecting surface of the reflector plate 12. Then, the parallel light is reflected by the lower reflecting surface and received by the linear sensor 65.
The irradiation light from the LED 66 is directly reflected by the lower reflecting surface of the reflector plate 12 and received by the light receiving LED 67.
In this state, the controller 13 starts driving of the sewing machine motor 15 to start conveyance of the lower cloth CD and the upper cloth CU.
Accordingly, the upper cloth CU and the lower cloth CD are separated up and down by the partition plate 11 and conveyed, and the leading portion of the lower cloth CD enters the portion between the lower detecting unit 60 and the reflector plate 12.
Accordingly, when the light intensity of the reflected light detected by the light receiving LED 67 decreases, the controller 13 recognizes the arrival of the lower cloth CD and starts to read an output of the linear sensor 65.
Then, as a detection output of the linear sensor 65, when the position in the X-axis direction of the side edge portion of the lower cloth CD is biased toward the X-axis forward direction side with respect to a preset regulated position, the controller 13 controls the lower solenoid 38 to bring the lower roller 37 into contact with the lower cloth CD with a predetermined pressure, and drives the lower pulse motor 39 to move the lower cloth CD in the X-axis backward direction. When the detected position of the side edge portion of the lower cloth CD is biased toward the X-axis backward direction side, the controller moves the lower cloth CD in the X-axis forward direction.
By successively performing the position detection and movement control of the lower cloth CD in short-time cycles, the side edge portion of the lower cloth CD is conveyed to a stitching point of the sewing needle while keeping the regulated position, and therefore, sewing is performed so that the seam allowance of the lower cloth CD becomes a preset value.
The position detection and movement control of the upper cloth CU are also performed in the same manner as those of the lower cloth CD.
As described above, in the upper and lower feed sewing machine 100, the cloth detecting units 40, 60 for the upper cloth CU and the lower cloth CD have reflectors 44, 64 configured to collimate irradiation lights from the LEDs of the light source units 43, 63 to obtain parallel lights to irradiate the reflecting surfaces of the reflector plate 12 with the parallel lights in directions inclined around the X axis extending along the seam allowance direction with respect to the vertical direction.
As a result of irradiation of the irradiation lights being parallel lights on the reflecting surfaces of the reflector plate 12 from the above-described directions by the reflectors 44, 64, even when the irradiated surfaces of the upper cloth CU and the lower cloth CD separate from the reflecting surfaces due to their thicknesses or occurrence of clearances between these and the reflecting surfaces, the side edge portions of the upper cloth CU and the lower cloth CD do not block the reflected lights.
Therefore, in the seam allowance direction (direction orthogonal to the cloth feeding direction), the positions of the side edge portions of the upper cloth CU and the lower cloth CD can be accurately obtained, and the side edge portions of the upper cloth CU and the lower cloth CD can be accurately controlled to target positions, so that the sewing quality can be improved.
The seam allowances of the upper cloth CU and the lower cloth CD are adjustable individually, so that the positions of the side edge portions of the upper cloth CU and the lower cloth CD can be aligned more accurately, and therefore, when sewing the upper cloth CU and the lower cloth CD together, the sewing quality can be further improved.
In the upper and lower feed sewing machine 100, the cloth detecting units 40, 60 include the reflectors 44, 64 that reflect irradiation lights from the light source units 43, 63 to the reflector plate 12 sides.
If the devices do not include the reflectors 44, 64, the LEDs of the light source units 43, 63 and lenses must be arranged along the irradiation direction at an inclination angle θ3 with respect to the reflector plate 12, and the cloth detecting units 40, 60 inevitably become large in size in the up-down direction.
However, the cloth detecting units 40, 60 include reflectors 44, 64, so that the constraint that the LEDs of the light source units 43, 63 and lenses are arranged in the up-down direction can be eliminated, and the cloth detecting units 40, 60 can be arranged in the longitudinal direction of the housing. Therefore, the thicknesses of the cloth detecting units 40, 60 can be reduced in the up-down direction, and they can be easily disposed in narrow spaces below the throat plate or narrow spaces between the lateral-feeding mechanisms and the needle bar, so that the cloth detecting units can be easily installed, and eventually, the sewing machine can be downsized.
In the cloth detecting units 40, 60, the LEDs of the light source units 43, 63 and the lenses are arranged substantially along the X-axis direction, so that the cloth detecting units 40, 60 can be downsized in the Y-axis direction as well, and accordingly, the upper and lower lateral-feeding mechanisms 30 and 36 can be disposed closer to the stitching point, so that the seam allowances can be more accurately adjusted and the sewing quality can be further improved.
Further, the cloth detecting units 40, 60 irradiate slit-like parallel lights along the X-axis direction onto the reflector plate 12, so that from changes in length of reflected lights of the parallel lights, the positions in the X-axis direction of the side edge portions of the upper cloth CU and the lower cloth CD can be easily and accurately obtained.
The upper detecting unit 40 and the lower detecting unit 60 are disposed so that the arrangement of the reflector 44 and the linear sensor 45 and the arrangement of the reflector 64 and the linear sensor 65 are reverse to each other as viewed from the X-axis direction. This is for avoiding interference between the light source units 43, 63 because the light source unit 43 and the light source unit 63 are attached to slightly project to the outside from the bases 41, 61.
Therefore, when the light source unit 43 and the light source unit 63 do not project from the bases 41, 61, the arrangement of the reflector 44 and the linear sensor 45 and the arrangement of the reflector 64 and the linear sensor 65 may be the same as viewed from the X-axis direction.
Second Embodiment
An upper detecting unit 40A as a second embodiment is described with reference to Fig. 16. The same components in the upper detecting unit 40A as those in the upper detecting unit 40 are provided with the same reference symbols, and overlapping description is omitted.
In the first embodiment, the upper detecting unit 40 and the lower detecting unit 60 include reflectors 44, 64, respectively, however, for example, when the sewing machine has enough installation space for the upper detecting unit, the upper detecting unit may not be provided with the reflector 44.
For example, parallel light may be directly irradiated from the light source unit 43 on the reflector plate 12 without the reflector 44 by attaching the light source unit 43 to the base 41A so that the optical axis of the light source unit 43 is oriented in the direction of irradiation on the upper reflecting surface of the reflector plate 12 (direction inclined at the angle θ3 counterclockwise with respect to the vertical downward direction as viewed in the X-axis forward direction), arranging the LED and the lens (optical means) provided inside in the direction of irradiation on the upper reflecting surface, and forming a slit-like light guiding portion 415A at the front side in the direction of irradiation of the light source unit 43.
In this case, as compared with the upper detecting unit 40, although the upper detecting unit 40A becomes larger in the up-down direction, the reflector 44 can be made unnecessary and the configuration can be simplified.
In the upper detecting unit 40A, the light source unit 43 is disposed on the Y-axis forward direction side and the linear sensor 45 is disposed on the Y-axis backward direction side, however, they may be disposed reversely.
When the sewing machine has enough installation space for the lower detecting unit, it is also possible that the upper detecting unit 40 includes the reflector 44 and the lower detecting unit is not provided with the reflector 64. In this case, the light source unit of the lower detecting unit is attached in the same manner as the light source unit 43 of the upper detecting unit 40A.
Third Embodiment
An upper detecting unit 40A and a lower detecting unit 60A as a third embodiment are described with reference to Fig. 17. The same components in the lower detecting unit 60A as those in the lower detecting unit 60 are provided with the same reference symbols, and overlapping description is omitted.
In the first embodiment, the upper detecting unit 40 and the lower detecting unit 60 include the reflectors 44, 64, respectively, however, for example, when the sewing machine has enough installation space for the upper detecting unit and the lower detecting unit, the upper detecting unit 40A without the reflector 44 and the lower detecting unit 6A without the reflector 64 may be installed in the sewing machine 100.
The upper detecting unit 40A is the same as the upper detecting unit 40A of the second embodiment.
In the lower detecting unit 60A, parallel light may be directly irradiated on the reflector plate 12 from the light source unit 63 without the reflector 64 by attaching the light source unit 63 to the base 61A so that the optical axis of the light source unit 63 is oriented in the direction of irradiation on the lower reflecting surface of the reflector plate 12 (direction inclined at the angle θ3 clockwise with respect to the vertical upward direction as viewed in the X-axis forward direction), arranging the LED 631 and the lens 632 (an example of optical means) provided inside in the direction of irradiation on the lower reflecting surface, and forming the slit-like light guiding portion 615A at the front side in the irradiation direction of the light source unit 63.
In this case, as compared with the upper detecting unit 40 and the lower detecting unit 60, although the upper detecting unit 40A and the lower detecting unit 60A become larger in the up-down direction, the reflectors 44, 64 can be made unnecessary and the configuration can be simplified.
In the lower detecting unit 60A, the light source unit 63 is disposed on the Y-axis forward direction side and the linear sensor 65 is disposed on the Y-axis backward direction side in the same manner as described above, however, a reverse arrangement of these is also possible. The arrangement of the light source unit and the linear sensor in the upper detecting unit 40A and the arrangement of these in the lower detecting unit 60A may be reverse to each other.

Claims

A sewing machine (100) comprising:
a cloth feeding mechanism (20) configured to feed a workpiece (CU, CD) in a cloth feeding direction (Y) along a horizontal plane;

a lateral-feeding mechanism (30, 36) configured to move the workpiece (CU, CD) in a seam allowance direction (X) parallel to the horizontal plane and orthogonal to the cloth feeding direction (Y);

cloth edge detection means (12, 40, 60, 40A, 60A) for detecting a side edge portion of the workpiece (CU, CD), the side edge portion extending along the cloth feeding direction (Y); and

a controller (13) configured to control the lateral-feeding mechanism (30, 36) based on the detection by the cloth edge detection means (12, 40, 60) to control a seam allowance of the workpiece (CU, CD),

wherein the cloth edge detection means (12, 40, 60, 40A, 60A) comprises:
a reflector plate (12) disposed to overlap, in the vertical direction (Z) orthogonal to the horizontal plane, with the side edge portion of the workpiece (CU, CD) that is being fed in the cloth feeding direction (Y);

a light source (431, 631) configured to emit light to irradiate the reflector plate (12) and the side edge portion of the workpiece (CU, CD) that is being fed in the cloth feeding direction (Y); and

a detector (45, 65) including a plurality of light receiving devices arranged along the seam allowance direction (X) to receive the light reflected by the reflector plate (12),

characterized in that

the cloth edge detection means (12, 40, 60, 40A, 60A) further comprises optical means (44, 64, 632) for collimating the light emitted by the light source (431, 631) and for directing the collimated light in a direction orthogonal to the seam allowance direction (X) and inclined with respect to the cloth feeding direction (Y) toward the reflector plate (12) to irradiate the reflector plate (12) and the side edge portion of the workpiece (CU, CD) over a range along the seam allowance direction (X).
The sewing machine (100) according to claim 1, wherein the optical means (64, 632) comprises a first optical element (632) configured to collimate the light emitted by the light source (631), and a second optical element (64) configured to direct the collimated light in the direction orthogonal to the seam allowance direction (X).
The sewing machine (100) according to claim 2, wherein the light source (631) and the first optical element (632) are arranged in the seam allowance direction (X), and the second optical element (64) is configured to reflect the light from the first optical element (632) toward the reflector plate (12).
The sewing machine (100) according to claim 1 or 2, wherein the cloth edge detection means (12, 40, 60, 40A, 60A) further comprises a slit (416, 616, 415A, 615A) extending along the seam allowance direction (X), wherein the light passes through the slit (416, 616, 415A, 615A) to irradiate the reflector plate (12) and the side edge portion of the workpiece (CU, CD).
The sewing machine (100) according to claim 2, wherein the light source (631) and the first optical element (632) form a light source unit (63), and are disposed to output the collimated light in a direction inclined with respect to all of the vertical direction (Z), the cloth feeding direction (Y) and the seam allowance direction (X), and
the second optical element (64) has a reflecting surface (641) that reflects the collimated light toward the reflector plate (12), wherein the reflecting surface (641) is inclined with respect to all of the vertical direction (Z), the cloth feeding direction (Y) and the seam allowance direction (X).
The sewing machine (100) according to claim 5, wherein the direction in which the reflecting surface (641) of the second optical element (64) reflects the collimated light is inclined with respect to the vertical direction (Z).