Seal stitch cutter

Abstract

To provide an empty stitch cutter preventing an empty stitch such as a hollow ring from being erroneously cut.SOLUTION: An empty stitch cutter 30 for cutting an empty stitch 2 formed by a sewing machine 1 has a stationary blade 40, a movable blade 50 that moves so as to come close to or away from the stationary blade 40, a motor 90 that drives the movable blade 50 to move the movable blade 50, a foreign matter detector for detecting a foreign matter 3 existing on a track of the movable blade 50, and a controller 200 that stops the motor 90 when the foreign matter 3 is detected by the foreign material detector.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an air seam cutter that cuts a seam formed without being sewn to a workpiece to be sewn.

Background Art

[0002] Patent Document 1 discloses a sewing machine provided with an air ring cutter for cutting an air ring. This air ring cutter is provided within an opening formed in the needle plate of the sewing machine. An air ring refers to a seam formed without being sewn to a workpiece to be sewn at the start or end of a circular seam.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Foreign objects other than the air ring must not be accidentally cut by the air ring cutter. Therefore, an object of the present invention is to provide an air seam cutter that does not accidentally cut an air seam such as an air ring.

Means for Solving the Problems

[0005] According to a first aspect of the present invention, an air seam cutter for cutting an air seam formed by a sewing machine includes a fixed blade, a movable blade that moves so as to approach and separate from the fixed blade, a drive unit that drives the movable blade so as to move the movable blade, a foreign object detector that detects a foreign object present in the trajectory of the movable blade, and a control unit that stops the drive unit when the foreign object is detected by the foreign object detector. 、 The aforementioned foreign matter detector A probe is provided so as to be movable relative to the movable blade along the trajectory of the movable blade, and moves together with the movable blade so as to move toward the fixed blade in accordance with and ahead of the movable blade, and toward the fixed blade in accordance with and behind the movable blade, It includes a differential detector that detects the difference between the movable blade and the probe, When the differential detector detects the differential between the movable blade and the probe caused by the probe contacting the foreign object, the control unit stops the drive unit. The probe is configured as a cover that covers the cutting edge of the movable blade from the cutting edge to the vicinity of the cutting edge of the movable blade. According to a second aspect of the present invention, a non-seam cutter for cutting non-seams formed by a sewing machine comprises a fixed blade, a movable blade that moves toward and away from the fixed blade, a drive unit that drives the movable blade to move the movable blade, a foreign object detector that detects foreign objects present in the trajectory of the movable blade, and a control unit that stops the drive unit when the foreign object detector detects the foreign object. The aforementioned foreign matter detector A probe is provided so as to be movable relative to the movable blade along the trajectory of the movable blade, and moves together with the movable blade so as to move toward the fixed blade in accordance with and ahead of the movable blade, and toward the fixed blade in accordance with and behind the movable blade, It includes a differential detector that detects the difference between the movable blade and the probe, When the differential detector detects the differential between the movable blade and the probe caused by the probe contacting the foreign object, the control unit stops the drive unit. The differential detector includes a rotary encoder that detects the displacement or velocity of the probe.

[0006] This invention Third According to one aspect, a non-cutting stitch cutter for cutting non-cutting stitches formed by a sewing machine comprises a single-edged fixed blade having a first cutting edge, a first blade back, and a first cutting edge at the corner formed therefrom; a movable blade having a second cutting edge, a second blade back, and a second cutting edge at the corner formed therefrom, the second cutting edge being directed toward the first cutting edge and the second blade back being directed toward the first blade back and making contact with the first blade back, and moving toward and away from the fixed blade; and a movable cover provided to be movable relative to the movable blade along the trajectory of the movable blade, moving together with the movable blade so as to move toward the fixed blade in conjunction with and ahead of the movable blade, and moving toward and behind the fixed blade, wherein the movable cover covers the second cutting edge from the second cutting edge to the vicinity of the second cutting edge. [Effects of the Invention]

[0007] This invention 1st, 2nd According to this aspect, if a foreign object present in the trajectory of the movable blade is detected by the foreign object detector, the control unit stops the drive unit and the movable blade also stops, so that the foreign object is not accidentally cut by the movable blade. This invention Third According to this design, even if a foreign object comes into contact with the movable cover, it will not come into contact with the second cutting edge of the movable blade, thus preventing the foreign object from being accidentally cut by the movable blade. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front view of a sewing machine. [Figure 2]Figure 2 is a perspective view showing the lower part of the arm of the sewing machine. [Figure 3] Figure 3 is a perspective view showing the blind stitch cutter. [Figure 4] Figure 4 is a perspective view showing the movable blade, movable cover, first shaft and second shaft. [Figure 5] Figure 5 is a perspective view showing the fixed blade, fixed cover, movable blade and movable cover. [Figure 6] Figure 6 is a side view showing the fixed blade, fixed cover, movable blade and movable cover. [Figure 7] Figure 7 is a front view for explaining the movement of the movable blade and movable cover relative to the fixed blade. [Figure 8] Figure 8(a) is a front view for explaining the movement of the movable blade and movable cover relative to the fixed blade. Figure 8(b) is a side view for explaining the movement of the movable blade and movable cover relative to the fixed blade and fixed cover. [Figure 9] Figure 9 is a front view for explaining the movement of the movable blade and movable cover relative to the fixed blade. [Figure 10] Figure 10(a) is a front view for explaining the movement of the movable blade and movable cover relative to the fixed blade. Figure 10(b) is a side view for explaining the movement of the movable blade and movable cover relative to the fixed blade and fixed cover. [Figure 11] Figure 11(a) is a front view for explaining the movement of the movable blade and movable cover relative to the fixed blade. Figure 11(b) is a side view for explaining the movement of the movable blade and movable cover relative to the fixed blade and fixed cover.

Embodiments for Carrying out the Invention

[0009] Hereinafter, embodiments will be described with reference to the drawings. However, the scope of the present invention is not limited to the embodiments disclosed below. Since the drawings are provided for illustrative purposes only, the scope of the present invention is not limited to the illustrations in the drawings.

[0010] [1. Overview of Sewing Machines] The drawing shows arrows or symbols representing the height, depth, and width directions, which are perpendicular to each other. The height direction is also called the up-and-down direction, the depth direction is also called the front-to-back direction, and the width direction is also called the left-to-right direction. The height direction is not necessarily vertical, but when sewing machine 1 is placed on a horizontal surface, the height direction becomes vertical. The left and right orientations are determined when viewed from the front of sewing machine 1.

[0011] As shown in Figures 1 and 2, sewing machine 1 is a so-called overlock sewing machine that applies chain stitches, particularly double chain stitches, to a workpiece. In this specification, chain stitches include not only single chain stitches and double chain stitches, but also overlock stitches.

[0012] Sewing machine 1 comprises a sewing machine frame 10, a needle plate 16, a presser foot 18, a main motor 20, a feed dog 21, a needle bar 22, multiple sewing needles 23, a looper 25, and a non-seam cutter 30.

[0013] [2. Sewing machine frame] The sewing machine frame 10 is shaped like a U when viewed from the front. The sewing machine frame 10 has a vertical body section 11, an arm section 12, and a bed section 13.

[0014] The vertical cylinder section 11 forms the right side of the sewing machine frame 10. The vertical cylinder section 11 is erected to extend vertically. The arm section 12 forms the upper part of the sewing machine frame 10 and extends to the left from the upper part of the vertical cylinder section 11. The bed section 13 forms the lower part of the sewing machine frame 10 and extends to the left from the lower part of the vertical cylinder section 11. The bed section 13 has a flat bed surface 14 on its upper surface that extends in the front, back, left, and right directions. The workpiece is fed from front to back on this bed surface 14 during sewing. The workpiece refers to the object that is sewn by the sewing machine 1, for example, cloth.

[0015] [3. Sewing machine motor] The main motor 20 is located in the lower part of the vertical body 11. The main motor 20 outputs power to the feed transmission mechanism, the needle bar transmission mechanism, and the looper transmission mechanism, causing the needle bar 22 to move up and down, the feed teeth 21 to move in an elliptical or box motion, and the looper 25 to move in a circular or reciprocating motion.

[0016] [4. Needle plate, presser foot, and feed dog] The needle plate 16 is attached to the upper surface of the bed 13, and the upper surface of the needle plate 16 is flush with the bed surface 14. The needle plate 16 has multiple needle holes, and when the sewing needle 23 (described later) descends, the sewing needle 23 is inserted into the needle hole, and when the sewing needle 23 rises, the sewing needle 23 is removed from the needle hole.

[0017] The presser foot 18 hangs down from the bed 13 and is also provided to be vertically movable. When the presser foot 18 is lowered, it presses down on the workpiece on the needle plate 16. As a result, the workpiece is sandwiched between the presser foot 18 and the needle plate 16. When the presser foot 18 is raised and moves away from the workpiece, the workpiece is released.

[0018] The feed dogs 21 are positioned below the presser foot 18, inside the holes in the needle plate 16. The feed dogs 21 are connected to a feed transmission mechanism inside the bed section 13, and are configured to move in an elliptical or box-shaped motion by the feed transmission mechanism. The feed transmission mechanism is connected to the main motor 20, and the rotational motion of the main motor 20 is converted into the elliptical or box-shaped motion of the feed dogs by the feed transmission mechanism. As a result, the workpiece is fed from front to back by the feed dogs 21. Elliptical motion refers to the feed dogs 21 revolving along an elliptical trajectory that is long in the front-to-back direction and short in the up-and-down direction. Box-shaped motion refers to the feed dogs 21 revolving along a rectangular trajectory that is long in the front-to-back direction and short in the up-and-down direction.

[0019] [5. Needle bars, sewing needles, and loopers] The needle bar 22 extends downward from the inside to the outside of the arm section 12. The needle bar 22 is connected to a needle bar transmission mechanism, such as a crank mechanism, inside the arm section 12, and is provided to reciprocate up and down by the needle bar transmission mechanism. The needle bar transmission mechanism is connected to the main motor 20, and the rotational motion of the main motor 20 is converted into the up and down motion of the needle bar 22 by the needle bar transmission mechanism.

[0020] Multiple sewing needles 23 are attached to the lower end of the needle bar 22 and extend downward from the lower end of the needle bar 22. These sewing needles 23 are arranged at intervals in the left-right direction. Each thread 9 is guided from each spool to each sewing needle 23 and passed through the eye of each sewing needle. In Figure 1, there are two sewing needles 23, but there may be three or four.

[0021] The looper 25 is positioned below the needle bar 22 and inside the bed 13. The looper 25 is connected to a looper transmission mechanism inside the bed 13 and is provided by the looper transmission mechanism to be able to move in a circular or reciprocating motion. The looper transmission mechanism is connected to the main motor 20, and the rotational motion of the main motor 20 is converted into the circular or reciprocating motion of the looper 25 by the looper transmission mechanism.

[0022] [6. Formation of seams and open seams] When the main motor 20 drives the feed dogs 21, needle bar 22, and looper 25, the sewing needle 23 moves up and down, the looper 25 moves in a circular or reciprocating motion, and the feed dogs 21 moves in an elliptical or box motion. The workpiece is fed by the elliptical or box motion of the feed dogs 21. The sewing needle 23 and looper 25 cooperate with each other as the workpiece is fed to create a chain stitch, especially a double chain stitch, on the workpiece. Specifically, each time the sewing needle 23 penetrates the workpiece downwards, the looper 25 captures each thread 9 from each sewing needle 23, forming a loop of each thread 9, and intertwines these loops with the loops from the previous downward movement of the sewing needle 23. A double chain stitch is a series of these loops.

[0023] Double ring stitches are formed not only when sewn to the workpiece, but also when not sewn to the workpiece. That is, at the beginning or end of sewing, or both, when the workpiece is not below the needle bar 22, the sewing needle 23 and the looper 25 cooperate to form a double ring stitch without the sewing needle 23 penetrating the workpiece. A double ring stitch formed without being sewn to the workpiece is called a "dry stitch," and is abbreviated as "dry ring." Before or after the formation of the dry ring, or both, a double ring stitch connected to the dry ring is sewn to the workpiece by the sewing needle 23 and the looper 25.

[0024] The open stitch is cut by the open stitch cutter 30. The open stitch cutter 30 will be described in detail below.

[0025] [7. Seal stitch cutter] Figure 3 is a perspective view showing the empty stitch cutter 30. Figure 4 is a perspective view showing the movable blade 50, movable cover 70, and shafts 34 and 36 of the empty stitch cutter 30. Figure 5 is a perspective view showing the fixed blade 40, movable blade 50, fixed cover 60, and movable cover 70 of the empty stitch cutter 30. Figure 6 is a side view showing the fixed blade 40, movable blade 50, fixed cover 60, and movable cover 70 of the empty stitch cutter 30.

[0026] The empty stitch cutter 30 is a cutter with a safety mechanism designed based on a fail-safe design philosophy. The empty stitch cutter 30 comprises brackets 31-33, a first shaft 34, a coil spring 35, a second shaft 36, a torsion spring 37, a fixed blade 40, a movable blade 50, a fixed cover 60, a movable cover 70, a standby station 80, a motor 90, a transmission mechanism 100, a displacement detector 150, a control unit 200 (see Figure 1), and an operation button 210 (see Figure 1). Here, the foreign object detector has the movable cover 70, the second shaft 36, and the displacement detector 150. This foreign object detector detects foreign objects present in the trajectory of the movable blade 50 above the bed surface 14. Foreign objects refer to anything other than thin or thin flexible materials such as threads and empty rings.

[0027] [7-1. Bracket] As shown in Figure 3, brackets 31 to 33 are attached to the bed portion 13 inside the bed portion 13. The first bracket 31 is positioned below the rear of the needle plate 16 so as to extend in the width direction. The second bracket 32 ​​is provided integrally with the first bracket 31 behind the first bracket 31 and extends rearward from the first bracket 31. The third bracket 33 is positioned below and to the right of the rear of the second bracket 32.

[0028] [7-2. Shafts, coil springs, and torsion springs] As shown in Figures 3 and 4, the first shaft 34 is cylindrical. The first shaft 34 is attached to the second bracket 32 ​​so as to extend in the depth direction inside the bed portion 13. The first shaft 34 is located below and behind the needle plate 16.

[0029] The radial load of the first shaft 34 is supported by the second bracket 32, and the first shaft 34 is supported by the second bracket 32 ​​so as to be rotatable around its central axis. The first central axis extends in the front-rear direction. Hereinafter, the direction parallel to the central axis of the first shaft 34 will be called the axial direction, the direction perpendicular to the central axis of the first shaft 34 will be called the radial direction, and the direction around the central axis of the first shaft 34 will be called the circumferential direction. The axial direction is parallel to the depth direction.

[0030] The first shaft 34 is connected to the transmission mechanism 100, which will be described later, and the power from the motor 90 is transmitted to the first shaft 34 by the transmission mechanism 100. As a result, the first shaft 34 rotates.

[0031] The coil spring 35 is wound around the first shaft 34. The coil spring 35 takes reaction force from the second bracket 32 ​​and biases the first shaft 34 forward. As a result, the movable blade 50, described later, is pressed against the fixed blade 40 from behind.

[0032] The second shaft 36 is provided with a ring-shaped portion and a semi-cylindrical portion. The second shaft 36 is mounted on the first shaft 34 inside the bed portion 13 so as to be coaxial with the first shaft 34. The radial load of the second shaft 36 is borne by the first shaft 34, and the second shaft 36 is supported by the first shaft 34 so as to be rotatable in the circumferential direction relative to the first shaft 34.

[0033] The torsion spring 37 is wound around the first shaft 34. One end of the torsion spring 37 is attached to the first shaft 34, and the other end is attached to the second shaft 36. The torque of the first shaft 34 is transmitted to the second shaft 36 by the torsion spring 37, causing the second shaft 36 to rotate together with the first shaft 34. However, if a resistive force is applied to the second shaft 36 while the first shaft 34 is rotating, the second shaft 36 will stop or its rotational speed will decrease, causing the torsion spring 37 to twist.

[0034] The second shaft 36 is connected to a displacement detector 150, which will be described later. The displacement and rotational speed of the second shaft 36 are detected by the displacement detector 150, and the difference between the first shaft 34 and the second shaft 36 is also detected by the displacement detector 150. The difference between the first shaft 34 and the second shaft 36 refers to the difference between the rotational speed of the first shaft 34 and the rotational speed of the second shaft 36, or the difference between the displacement of the first shaft 34 and the displacement of the second shaft 36. Normally, since the second shaft 36 rotates together with the first shaft 34, the difference between the first shaft 34 and the second shaft 36 is zero. However, if a resistance force is applied to the second shaft 36 while the first shaft 34 is rotating, the difference between the first shaft 34 and the second shaft 36 will exceed zero.

[0035] [7-3. Fixed blade] As shown in Figure 6, the single-edged fixed blade 40 has a blade front 41, a blade back 42, a ridge 43, a cutting edge 44, a cutting tip 45, and a spine 46. The blade front 41 is the front side of the fixed blade 40, and the blade back 42 is the back side of the fixed blade 40. The cutting edge 44 is sharpened from the ridge 43 to the cutting tip 45 so as to be inclined with respect to the blade front 41 at the tip side of the blade front 41. The cutting edge 44 is also called the blade surface. The cutting tip 45 is the acute angle formed by the cutting edge 44 and the blade back 42.

[0036] As shown in Figures 3, 5, and 6, the fixed blade 40 is mounted on the first bracket 31 within the bed 13 and positioned below the rear end of the needle plate 16. In the position of the fixed blade 40 when mounted on the first bracket 31, the cutting edge 45 is pointed upward, the ridge 46 is pointed downward, the blade surface 41 is pointed forward, the blade back 42 is pointed backward, and the cutting edge 45 extends in the width direction and the radial direction.

[0037] As shown in Figure 2, a slit 14a is formed in the bed surface 14 of the bed portion 13 along the rear end of the needle plate 16, and the fixed blade 40 is positioned below the slit 14a along the rear end of the needle plate 16.

[0038] [7-4. Fixing Cover] As shown in Figures 3, 5, and 6, the fixed cover 60 is attached to the first bracket 31 and the fixed blade 40 within the bed section 13. The fixed cover 60 is positioned below the rear end of the needle plate 16 and in front of the fixed blade 40. The fixed cover 60 covers the blade surface 41 and the cutting edge 44 of the fixed blade 40 from the blade surface 41 to the vicinity of the cutting edge 45. The fixed cover 60 protrudes above the cutting edge 45 of the fixed blade 40, and the upper and rear edge 61 of the fixed cover 60 follows the cutting edge 45 of the fixed blade 40. The edge 61 of the fixed cover 60 is located above the cutting edge 45 of the fixed blade 40 and slightly in front of the cutting edge 45 and the back of the blade 42 of the fixed blade 40. The fixed cover 60 is also slightly in front of the raceway surface of the movable blade 50. The raceway surface of the movable blade 50 refers to the surface traced by the cutting edge 55 of the movable blade 50 as the movable blade 50 rotates.

[0039] [7-5. Movable blade] As shown in Figure 6, the single-edged movable blade 50 has a blade front 51, a blade back 52, a ridge 53, a cutting edge 54, a cutting tip 55, and a spine 56. The blade front 51 is the front side of the movable blade 50, and the blade back 52 is the back side of the movable blade 50. The cutting edge 54 is sharpened from the ridge 53 to the cutting tip 55 so as to be inclined with respect to the blade front 51 on the cutting tip side of the blade front 51. The cutting edge 54 is also called the blade surface. The cutting tip 55 is the acute angle formed by the cutting edge 54 and the blade back 52.

[0040] As shown in Figures 3, 5, and 6, the movable blade 50 is positioned behind the fixed blade 40, close to the back surface 42 of the fixed blade 40. The movable blade 50 is attached to the second bracket 32 ​​via the first shaft 34 within the bed section 13 and is circumferentially rotatable. Specifically, as shown in Figures 3 and 4, the movable blade 50 is fixed to the front end of the first shaft 34, and the movable blade 50 rotates circumferentially due to the relative rotation of the first shaft 34 with respect to the second bracket 32. The movable blade 50 is provided radially outward from the front end of the first shaft 34.

[0041] As shown in Figures 3, 5, and 6, in the position of the movable blade 50 when it is pivotably mounted to the second bracket 32 ​​via the first shaft 34, the blade front 51 faces rearward, the blade back 52 faces forward, the blade tip 55 is directed towards the blade tip 45 of the fixed blade 40 in the circumferential direction, and the blade tip 55 extends radially. The blade back 52 of the movable blade 50 and the blade back 42 of the fixed blade 40 face each other in the axial direction, and the blade back 52 of the movable blade 50 is pressed against the blade back 42 of the fixed blade 40 by the elastic force of the coil spring 35.

[0042] Since the movable blade 50 is rotatable relative to the fixed blade 40 so as to move toward and away from the fixed blade 40, the movable blade 50 and the fixed blade 40 can be opened and closed. Specifically, the movable blade 50 and the fixed blade 40 are closed when the movable blade 50 is swung down toward the fixed blade 40. The movable blade 50 and the fixed blade 40 are opened when the movable blade 50 is swung up toward the fixed blade 40.

[0043] When the movable blade 50 and the fixed blade 40 are open, as shown in Figure 2, the movable blade 50 protrudes upward from the slit 14a, and this position of the movable blade 50 is the standby position and initial position. When the movable blade 50 and the fixed blade 40 are closed, the movable blade 50 enters the slit 14a.

[0044] As shown in Figure 6, the raceway surface of the movable blade 50 is set back from the fixed cover 60. In other words, the raceway surface of the movable blade 50 is set back from the upper and rear edge 61 of the fixed cover 60. Therefore, even when the movable blade 50 is swung to the left so as to swing down toward the fixed blade 40, the movable blade 50 does not come into contact with the fixed cover 60.

[0045] [7-6. Movable cover] As shown in Figures 3 and 4, the movable cover 70 and the second shaft 36 are integrally formed, and the movable cover 70 is provided radially outward from the front end of the second shaft 36. Since the second shaft 36 is circumferentially rotatable relative to the first shaft 34, the movable cover 70 is circumferentially pivotable relative to the movable blade 50. The pivot trajectory of the movable cover 70 follows the pivot trajectory of the movable blade 50. Since the torque of the first shaft 34 is transmitted to the second shaft 36 by the torsion spring 37, the movable cover 70 pivots together with the movable blade 50. Specifically, when the movable blade 50 pivots to the left so that it is swung up toward the fixed blade 40, the movable cover 70 follows and precedes the movable blade 50 and is swung down together with the movable blade 50. When the movable blade 50 pivots to the right so that it is swung up toward the fixed blade 40, the movable cover 70 follows and lags behind the movable blade 50 and is swung up together with the movable blade 50. However, if a resisting force is applied to the movable cover 70 while the movable blade 50 is rotating, the movable cover 70 will stop or its rotational speed will decrease, and the torsion spring 37 will twist. When the resisting force is released, the twisting of the torsion spring 37 will be released.

[0046] When the movable blade 50 and the fixed blade 40 are open, the movable cover 70 protrudes upward from the slit 14a as shown in Figure 2, and this position of the movable cover 70 is the standby position and initial position. When the movable blade 50 and the fixed blade 40 are open, the movable cover 70 enters the slit 14a.

[0047] As shown in Figures 4 to 6, the movable cover 70 is positioned behind the movable blade 50 and covers the blade surface 51 and cutting edge 54 of the movable blade 50 from the blade surface 51 to the vicinity of the cutting edge 55. In the circumferential direction, the movable cover 70 protrudes from the cutting edge 55 of the movable blade 50 toward the fixed blade 40. The edge 71 of the movable cover 70 closer to the fixed blade 40 and fixed cover 60 (this edge 71 is also the front edge of the movable cover 70) is set away from the cutting edge 55 of the movable blade 50 toward the fixed blade 40. The raceway surface of the movable cover 70 is set slightly behind the raceway surface of the movable blade 50. The raceway surface of the movable cover 70 refers to the surface traced by the edge 71 of the movable cover 70 as the movable cover 70 rotates.

[0048] The raceway surface of the movable cover 70 is slightly separated from the cutting edge 45 of the fixed blade 40 and the rear edge 61 of the fixed cover 60. Therefore, even when the movable cover 70 rotates to the left to approach the fixed blade 40 and fixed cover 60, the movable cover 70 does not come into contact with the fixed blade 40 and fixed cover 60.

[0049] The movable cover 70 is a probe that searches for foreign objects present in the trajectory of the movable blade 50 above the bed surface 14. The probe is also called a detection member or probe.

[0050] [7-7. Waiting Station] The standby station 80 is provided on the bed section 13 so as to protrude upward from the bed surface 14 of the bed section 13. The standby station 80 covers the right side of the slit 14a from above. The standby station 80 is provided in a box shape with a hollow interior, and the bottom of its hollow interior is connected to the right side of the slit 14a. The standby station 80 has a slit 81 on its left side, and this slit 81 is connected to the hollow interior of the standby station 80.

[0051] When the movable blade 50 and the fixed blade 40 are open, the movable blade 50 and the movable cover 70 enter the hollow space of the standby station 80 from the right side of the slit 14a, and the position of the movable blade 50 and the movable cover 70 at that time is the standby position and initial position. When the movable blade 50 and the movable cover 70 rotate toward the fixed blade 40 from that state, the movable blade 50 and the movable cover 70 move out of the standby station 80 through the slit 81.

[0052] [7-8. Motor] The motor 90, which acts as the drive unit, is mounted on the third bracket 33. The motor 90 has a pinion on its output shaft. The motor 90 is connected to the transmission mechanism 100 via an output gear and outputs torque to the transmission mechanism 100.

[0053] The motor 90 is controlled by the control unit 200.

[0054] [7-9. Transmission Mechanisms] The transmission mechanism 100 is a reduction gear that transmits the torque of the motor 90 to the first shaft 34, converting the rotational motion of the motor 90 into the rotational motion of the first shaft 34. In other words, the transmission mechanism 100 reduces the rotational speed of the motor 90 and outputs it to the first shaft 34, while also increasing the torque of the motor 90 and outputting it to the first shaft 34.

[0055] The transmission mechanism 100 includes a first double gear 110, a second double gear 120, a third double gear 130, and a gear 140. The double gears 110, 120, and 130 are rotatably supported on a third bracket 33 such that their axes of rotation are parallel to each other.

[0056] The first double gear 110 has a large gear 111 and a small gear 112 that are coaxial with each other. The second double gear 120 has a large gear 121 and a small gear 122 that are coaxial with each other. The third double gear 130 has a large sector gear 131 and a small sector gear 132 that are coaxial with each other. The large gear 111 of the first double gear 110 meshes with the output gear of the motor 90. The small gear 112 of the first double gear 110 meshes with the large gear 121 of the second double gear 120. The small gear 122 of the second double gear 120 meshes with the large sector gear 131 of the third double gear 130. The small sector gear 132 of the third double gear 130 meshes with gear 140. Gear 140 is mounted on the first shaft 34 so as to be coaxial with the first shaft 34.

[0057] [7-10. Displacement Detector] The displacement detector 150 detects the displacement of the second shaft 36. In other words, the displacement detector 150 detects the displacement of the movable cover 70. The displacement detector 150 also functions as a speed detector, detecting the rotational speed of the second shaft 36 and the swivel speed of the movable cover 70.

[0058] The displacement detector 150 includes gears 151 and 152 and a rotary encoder 153. Gear 151 is mounted on the second shaft 36 so as to be coaxial with the second shaft 36. Gear 152 meshes with gear 151. Gear 152 is rotatably mounted on the third bracket 33. The rotary encoder 153 is connected to gear 152. When gear 152 rotates, the rotary encoder 153 outputs a pulse signal to the control unit 200, thereby allowing the displacement or rotation speed of the movable cover 70 to be detected by the displacement detector 150 and recognized by the control unit 200.

[0059] [7-11. Operation Buttons] The operation button 210 is provided on the sewing machine frame 10, specifically on the outer surface of the sewing machine frame 10, and more specifically on the front surface of the vertical body section 11. The operation button 210 can be a tactile switch, momentary switch, dome switch, membrane switch, pressure-sensitive switch, touch sensor, touch panel, or electrostatic sensor. When the user presses or touches the operation button 210, an operation signal to that effect is output to the control unit 200 by the operation button 210.

[0060] [7-12. Control Unit] The control unit 200 includes a CPU, RAM, ROM, a signal processing circuit, and a motor driver. The CPU uses the RAM as a working area and executes processing according to the program recorded in the ROM, controlling the signal processing circuit and the motor driver according to the program. The signal processing circuit processes the output signal of the rotary encoder 153. The motor driver drives the motor 90.

[0061] The control unit 200 monitors the displacement or velocity detected by the displacement detector 150, that is, the pulse signal which is the output signal of the rotary encoder 153. Here, since the control unit 200 controls the motor 90 in an open-loop or closed-loop manner, the control unit 200 recognizes the displacement or rotational speed of the motor 90, that is, the displacement or rotational speed of the movable blade 50. Therefore, when the control unit 200 receives a pulse signal from the rotary encoder 153, the difference between the movable blade 50 and the movable cover 70 is detected by the displacement detector 150 and recognized by the control unit 200. Thus, the displacement detector 150 is also a differential detector that detects the difference between the movable blade 50 and the movable cover 70. The difference between the movable blade 50 and the movable cover 70 refers to the difference between the rotational speed of the movable blade 50 and the rotational speed of the movable cover 70, or the difference between the displacement of the movable blade 50 and the displacement of the movable cover 70.

[0062] When the control unit 200 receives an operation signal from the operation button 210, it controls the motor 90. Specifically, when the control unit 200 rotates the motor 90 forward at a predetermined rotational speed, the movable blade 50 rotates to the left so that it is swung down toward the fixed blade 40 by the power of the motor 90. Subsequently, when the control unit 200 rotates the motor 90 in the reverse direction at a predetermined rotational speed, the movable blade 50 rotates to the right so that it is swung up toward the fixed blade 40 by the power of the motor 90. The operation of the sewn stitch cutter 30 when the control unit 200 controls the motor 90 in this manner will be explained in detail below.

[0063] [7-13. Operation of the Seal Stitch Cutter] (1) Wait Before the user operates the operation button 210, as shown in Figure 7, the movable blade 50 and movable cover 70 are inserted into the hollow of the standby station 80 from the right side of the slit 14a. At this time, the control unit 200 monitors the signal transmitted from the operation button 210.

[0064] (2) Normal operation The user sets the empty stitch 2 on the bed surface 14 of the bed section 13 so that the empty stitch 2 crosses the slit 14a in the depth direction. When the user presses or touches the operation button 210, the control unit 200 detects the input of an operation signal from the operation button 210. Such detection triggers the control unit 200 to start driving the motor 90, so the control unit 200 rotates the motor 90 in the forward direction at a predetermined rotational speed.

[0065] As a result, as shown in Figures 7, 8, 9, and 10 in that order, the movable blade 50 rotates to the left so that it is swung down toward the fixed blade 40 by the power of the motor 90, and the movable cover 70 is swung down toward the fixed blade 40 in conjunction with and ahead of the movable blade 50. While the motor 90 is rotating forward, the control unit 200 monitors the pulse signal of the rotary encoder 153, that is, the differential detected by the displacement detector 150. Specifically, the control unit 200 compares the differential detected by the displacement detector 150 with a predetermined threshold. The differential detected by the displacement detector 150 represents the difference between the displacement of the movable blade 50 and the displacement of the movable cover 70, the difference between the rotation speed of the movable blade 50 and the rotation speed of the movable cover 70, the displacement of the movable cover 70, and the rotation speed of the movable cover 70.

[0066] As shown in Figures 7 and 8, until the movable cover 70 contacts the empty stitch 2 during the downward swing of the movable blade 50 and the movable cover 70, the movable blade 50 and the movable cover 70 rotate at the same rotational speed, and the differential between the movable blade 50 and the movable cover 70 is zero. Therefore, the control unit 200 determines that the differential detected by the displacement detector 150 is less than a predetermined threshold.

[0067] After the movable cover 70 comes into contact with the empty stitch 2 and enters the slit 14a as shown in Figure 9, the movable cover 70 receives resistance from the empty stitch 2, causing the rotational speed of the movable cover 70 to become smaller than the rotational speed of the movable blade 50, and the differential between the movable blade 50 and the movable cover 70 to become greater than zero. However, after the movable cover 70 enters the slit 14a, the control unit 200 stops monitoring the differential detected by the displacement detector 150. Therefore, after the movable cover 70 enters the slit 14a, the control unit 200 does not stop the motor 90, and the downward swing of the movable blade 50 and the movable cover 70 continues.

[0068] As shown in Figure 10, when the movable blade 50 enters the slit 14a together with the movable cover 70, the movable blade 50 and the fixed blade 40 close together, and the movable blade 50 and the fixed blade 40 cut the empty stitch 2 by shearing.

[0069] Then, the control unit 200 stops the motor 90, and the movable blade 50 and the movable cover 70 stop with the movable blade 50 and the fixed blade 40 closed.

[0070] Subsequently, the control unit 200 reverses the motor 90 to a predetermined rotational speed. As a result, the movable blade 50 rotates to the right so that it is swung up from the fixed blade 40 by the power of the motor 90, and the movable cover 70 is swung up from the fixed blade 40 in a delayed and follow motion with the movable blade 50. When the movable blade 50 and the movable cover 70 exit the slit 14a and enter the inside of the standby station 80, the control unit 200 stops the motor 90. Therefore, the movable blade 50 and the movable cover 70 stop with the movable blade 50 and the fixed blade 40 in the open position.

[0071] (3) Action when foreign object is detected As shown in Figure 11, the case where foreign matter 3 is in the trajectory of the movable blade 50 will be described. When the user presses or touches the operation button 210, the control unit 200 rotates the motor 90 forward at a predetermined rotational speed. The movable blade 50 rotates to the left so that it is swung down toward the fixed blade 40 by the power of the motor 90, and the movable cover 70 is swung down toward the fixed blade 40 in conjunction with and preceding the movable blade 50. While the motor 90 is rotating forward, the control unit 200 compares the differential detected by the displacement detector 150 with a predetermined threshold.

[0072] When the movable cover 70 strikes the foreign object 3, the movable blade 50 continues to rotate, while the movable cover 70 stops or its rotational speed decreases significantly. As a result, the difference between the movable blade 50 and the movable cover 70 increases and exceeds a predetermined threshold. This corresponds to the foreign object detector detecting the foreign object 3.

[0073] When the differential between the movable blade 50 and the movable cover 70 exceeds a predetermined threshold, the control unit 200 determines that the differential detected by the displacement detector 150 is above the predetermined threshold. As a result, the control unit 200 stops the motor 90. Therefore, the movable blade 50, especially its cutting edge 55, stops without contacting the foreign object 3. Thus, damage to the foreign object 3 can be prevented.

[0074] Immediately after the motor 90 stops, the control unit 200 reverses the motor 90 to a predetermined rotational speed. As a result, the movable blade 50 rotates toward the standby station 80 by the power of the motor 90, and the movable cover 70 rotates toward the standby station 80 in a lagging manner behind the movable blade 50. When the movable blade 50 and the movable cover 70 enter the inside of the standby station 80, the control unit 200 stops the motor 90. Therefore, the movable blade 50 and the movable cover 70 stop with the movable blade 50 and the fixed blade 40 in the open position.

[0075] (4) Failsafe For some reason, such as a malfunction or failure of the control unit 200 or the rotary encoder 153, the motor 90 may not stop even if the movable cover 70 hits the foreign object 3. In such a case, the movable cover 70 hits the foreign object 3, so the cutting edge 55 of the movable blade 50 does not hit the foreign object 3. After the movable cover 70 hits the foreign object 3, a resistance force acts from the foreign object 3 through the movable cover 70 to the movable blade 50, so even if the motor 90 is energized, the motor 90 is forcibly stopped. Even if the resistance force is small and the foreign object 3 is pushed toward the fixed blade 40 by the power of the motor 90, the foreign object 3 hits the fixed cover 60 and does not hit the cutting edge 45 of the fixed blade 40. Therefore, the foreign object 3 is not accidentally cut.

[0076] [8. Advantageous technical effects] (1) If the foreign object 3 is detected by the foreign object detector while the motor 90 is rotating forward, that is, if the movable cover 70 comes into contact with the foreign object and a differential occurs between the movable blade 50 and the movable cover 70, and this differential is detected by the rotary encoder 153, the control unit 200 stops the motor 90 and reverses the motor 90. As a result, the movable blade 50, especially its cutting edge 55, does not come into contact with the foreign object 3, and the foreign object 3 is not accidentally cut by the movable blade 50.

[0077] (2) The movable cover 70 is swung down in conjunction with and ahead of the movable blade 50. Therefore, even if the foreign object 3 is in the trajectory of the movable blade 50 and the movable cover 70, only the movable cover 70 will come into contact with the foreign object 3, and the cutting edge 55 of the movable blade 50 will not come into contact with the foreign object 3. Thus, the foreign object 3 will not be accidentally cut by the movable blade 50.

[0078] (3) Even if foreign matter 3 accidentally enters the slit 14a, foreign matter 3 will only come into contact with the fixed cover 60 and will not come into contact with the cutting edge 45 of the fixed blade 40. Therefore, foreign matter 3 will not be accidentally cut by the fixed blade 40.

[0079] (4) Fail-safe functionality is achieved. In other words, even if the motor 90 malfunctions and operates without the user pressing the operation button 210, and even if the foreign object 3 is not mistakenly detected due to a malfunction or failure of the control unit 200 or rotary encoder 153 while the motor 90 is rotating forward, the movable cover 70 will come into contact with the foreign object 3, so the foreign object 3 will not be mistakenly cut by the movable blade 50.

[0080] (5) When in standby mode, the movable blade 50 is hidden inside the standby station 80, so foreign objects, threads, and empty stitches are not accidentally damaged by the movable blade 50.

[0081] (6) Since the fixed blade 40 is positioned below the slit 14a, foreign objects, threads, and empty stitches are not accidentally damaged by the fixed blade 40.

[0082] [9. Variations] However, the present invention is not limited to the embodiments described above. The above embodiments may be modified, for example, as follows.

[0083] (1) In the above embodiment, the fixed cover 60 covers the cutting edge 44 of the fixed blade 40 from the cutting edge 44 to the vicinity of the cutting edge 45. Alternatively, the fixed blade 40 may be positioned below the needle plate 16, and instead of the fixed cover 60, the needle plate 16 may cover the cutting edge 44 of the fixed blade 40 from the cutting edge 44 to the vicinity of the cutting edge 45. In this case, the rear edge of the needle plate 16 forms the edge of the slit 14a, and that edge is aligned with the cutting edge 45 of the fixed blade 40. The rear edge of the needle plate 16 is located above the cutting edge 45 of the fixed blade 40, and is located slightly in front of the cutting edge 45 and the back of the blade 42 of the fixed blade 40.

[0084] (2) In the above embodiment, the movable blade 50 is provided so as to be rotatable, but the movable blade 50 may also be provided so as to be able to move linearly in the height direction by a guide. In this case, the movable cover 70 is attached to the movable blade 50 so as to be able to move linearly in the height direction relative to the movable blade 50, and is pressed upward against a stopper by a spring or the like. When the movable blade 50 is driven downward by a drive unit such as a motor and an electromagnetic solenoid, the movable cover 70 moves in accordance with and ahead of the movable blade 50. If the movable cover 70 comes into contact with foreign matter, the cutting edge 55 of the movable blade 50 will not come into contact with the foreign matter. Furthermore, a differential occurs between the movable cover 70 and the movable blade 50, and this differential is detected by the differential detector, causing the control unit 200 to stop the drive unit and to reverse the operation of the drive unit, so that the movable blade 50 moves upward away from the foreign matter. If the movable cover 70 does not come into contact with foreign matter, the empty stitch is cut by the fixed blade 40 and the movable blade 50.

[0085] (3) In the above embodiment, the foreign object detector uses the movable cover 70 and the rotary encoder 153, but the foreign object detector may use a reflective or transmissive type light sensor. In this case, the light sensor projects light onto the movable blade 50 along its trajectory, and if a foreign object is present in the trajectory of the movable blade 50, the light emitted from the light sensor is blocked by the foreign object, and the foreign object is detected by the light sensor. [Explanation of symbols]

[0086] 1 Sewing machine 30 Seal Stitch Cutter 40 Fixed blade 42. Back of the blade (back of the first blade) 44 Cutting edge (1st cutting edge) 45. Cutting edge (first cutting edge) 50 movable blade 52. Back of the blade (back of the second blade) 54 Cutting edge (second cutting edge) 55 Cutting edge (second cutting edge) 60 Fixed cover 70. Movable cover (probe) 90 Motor (drive unit) 150 Displacement detector (differential detector) 153 Rotary Encoder 200 Control Unit

Claims

1. A non-seam cutter for cutting non-seams formed by a sewing machine, Fixed blade and A movable blade that moves toward and away from the fixed blade, A drive unit that drives the movable blade to move the movable blade, A foreign object detector for detecting foreign objects present in the trajectory of the movable blade, The system includes a control unit that stops the drive unit when the foreign object is detected by the foreign object detector, The aforementioned foreign matter detector A probe is provided so as to be movable relative to the movable blade along the trajectory of the movable blade, and moves together with the movable blade so as to move toward the fixed blade in accordance with and ahead of the movable blade, and toward the fixed blade in accordance with and behind the movable blade, It includes a differential detector that detects the difference between the movable blade and the probe, When the differential detector detects the differential between the movable blade and the probe caused by the probe contacting the foreign object, the control unit stops the drive unit. The probe is a cover that covers the cutting edge of the movable blade from the cutting edge to the vicinity of the cutting edge of the movable blade. A cutter for creating empty stitches, characterized by its features.

2. A non-seam cutter for cutting non-seams formed by a sewing machine, Fixed blade and A movable blade that moves toward and away from the fixed blade, A drive unit that drives the movable blade to move the movable blade, A foreign object detector for detecting foreign objects present in the trajectory of the movable blade, The system includes a control unit that stops the drive unit when the foreign object is detected by the foreign object detector, The aforementioned foreign matter detector A probe is provided so as to be movable relative to the movable blade along the trajectory of the movable blade, and moves together with the movable blade so as to move toward the fixed blade in accordance with and ahead of the movable blade, and toward the fixed blade in accordance with and behind the movable blade, It includes a differential detector that detects the difference between the movable blade and the probe, When the differential detector detects the differential between the movable blade and the probe caused by the probe contacting the foreign object, the control unit stops the drive unit. The differential detector has a rotary encoder that detects the displacement or velocity of the probe. A cutter for creating empty stitches, characterized by its features.

3. A non-seam cutter for cutting non-seams formed by a sewing machine, A single-edged fixed blade having a first cutting edge, a first back of the blade, and a first cutting edge at the angle formed by them, A movable blade having a second cutting edge, a second back of the blade, and a second cutting edge at the angle formed by them, wherein the second cutting edge is directed toward the first cutting edge, and the second back of the blade is directed toward the back of the first blade and makes contact with the back of the first blade, and moves toward and away from the fixed blade, The system includes a movable cover that is provided so as to be movable relative to the movable blade along the trajectory of the movable blade, moves together with the movable blade so as to move toward the fixed blade in accordance with and ahead of the movable blade, and moves toward the fixed blade in accordance with and behind the movable blade, The movable cover covers the second cutting edge from the second cutting edge to the vicinity of the second cutting edge. A cutter for creating empty stitches, characterized by its features.

4. The dry stitch cutter according to claim 3, further characterized by comprising a fixed cover that covers the first cutting blade from the first cutting blade to the vicinity of the first cutting edge.

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