Claims
- 1. In an apparatus for detecting an improper stitch used in conjunction with a chainstitch sewing machine, said machine including:
- an axially reciprocal needle adapted to receive at least one needle thread and form a succession of stitches, said needle being movable along a longitudinal needle axis;
- a reciprocal needle thread take-up lever;
- a drive motor having an output shaft, and means associated with said shaft for driving said needle through at least one reciprocal motion per stitch; and
- a looper thread assembly including looper means for incorporating a looper thread to said needle thread when forming said stitches during one stitch cycle, and a looper thread tension assembly and associated delivery means for delivering said looper thread to said looper means, said looper thread being disposed in part along a looper thread axis extending between said looper thread tension assembly and said looper means; the improvement in the apparatus comprising:
- a) looper thread detection means for detecting looper thread movement along said looper thread axis between said looper thread tension assembly and said looper means during a predetermined portion of said stitch cycle;
- b) shaft rotation detecting means for detecting rotations of said output shaft; and
- c) first signal generating means responsive to said looper thread detection means and said shaft rotation detector means for generating a first stitch signal corresponding to detection of substantially no looper thread movement during said predetermined portion of said stitch cycle, said first stitch signal being indicative of formation of an improper stitch.
- 2. The improvement according to claim 1 wherein said looper thread detection means comprising:
- i) a detector housing having a channel extending therethrough along a channel axis for receiving said looper thread between said looper thread tension assembly and said looper means, wherein, in said channel, said looper thread axis is substantially aligned with said channel axis;
- ii) beam generating means positioned on one side of said channel for generating an optical beam of predetermined width transverse to said channel axis and intersecting at least a portion of said channel; and
- iii) means for controlling a position of said looper thread in said channel so that said thread passes through at least a portion of said beam,
- iv) beam detection means positioned on a side of said channel opposite said beam generating means for detecting said optical beam;
- whereby movement of said looper thread through said optical beam is detected due to differences in thread characteristics along a length of said thread.
- 3. The improvement according to claim 2 wherein said channel is of sufficient size to substantially constrain movement of said looper thread within a predetermined region, said region being determined by said predetermined width of said beam.
- 4. The improvement according to claim 3 further comprising means for storing predetermined values corresponding to thread movement during said predetermined portion of said stitch cycle.
- 5. The improvement according to claim 4 further comprising means for comparing said stored values with thread movement during said predetermined portion of said stitch cycle.
- 6. The improvement according to claim 3 further comprising means for generating an output signal representative of said first stitch signal.
- 7. The improvement according to claim 1 further comprising:
- d) needle thread detection means for detecting needle thread movement along said needle thread axis between said take-up lever and said needle during a second predetermined portion of said stitch cycle;
- e) second signal generating means responsive to said needle thread detection means for generating a second stitch signal corresponding to detection at substantially no needle thread movement during said second predetermined portion of said stitch cycle, said second stitch signal being indicative of formation of an improper stitch.
- 8. The improvement according to claim 7 wherein said needle thread detection means further comprising:
- a) a detector housing having a channel extending therethrough along a channel axis for receiving said needle thread between said take-up lever and said needle, wherein, in said channel, said needle thread axis is substantially aligned with said channel axis;
- b) beam generating means positioned on one side of said channel for generating an optical beam of predetermined width and transverse to said channel axis and intersecting at least a portion of said channel;
- c) means for controlling a position of said needle thread in said channel so that said thread passes through at least a portion of said beam; and
- d) beam detection means positioned on a side of said channel opposite said beam generating means for detecting said optical beam;
- whereby movement of said needle thread through said optical beam is detected due to differences in thread characteristics along a length of said thread.
- 9. The improvement according to claim 8 wherein said channel is of sufficient size to substantially constrain movement of said looper thread within a predetermined region, said region being determined by said predetermined width of said beam.
- 10. The improvement according to claim 9 further comprising means for storing predetermined values corresponding to thread movement during said predetermined portion of said stitch cycle.
- 11. The improvement according to claim 10 further comprising means for comparing said stored values with actual thread movement during said predetermined portion of said stitch cycle.
- 12. The improvement according to claim 9 further comprising means for generating an output signal representation of said second stitch signal.
- 13. In an apparatus for detecting an improper stitch used in conjunction with a chainstitch sewing machine, said machine including:
- an axially reciprocal needle adapted to receive at least one needle thread and form a succession of stitches, said needle being movable along a longitudinal needle axis;
- a reciprocal needle thread take-up lever;
- a drive motor having an output shaft, and means associated with said shaft for driving said needle through at least one reciprocal motion per stitch;
- a looper thread assembly including looper means for incorporating a looper thread to said needle thread when forming said stitches during one stitch cycle, and a looper thread tension assembly and associated delivery means for delivering said looper thread to said looper means, said looper thread being disposed in part along a looper thread axis extending between said looper thread tension assembly and said looper means the improvement in the apparatus comprising:
- a) needle thread detection means for detecting needle thread movement along said needle thread axis between said take-up lever and said needle during a predetermined portion of said stitch cycle;
- b) shaft rotation detecting means for detecting rotations of said output shaft; and
- c) signal generating means responsive to said needle thread detection means and said shaft rotation means for generating a stitch signal corresponding to detection of substantially no needle thread movement during said predetermined portion of said stitch cycle, said stitch signal being indicative of formation of an improper stitch.
- 14. The improvement according to claim 13 wherein said needle thread detection means further comprising:
- i) a detector housing having a channel extending therethrough along a channel axis for receiving said needle thread between said take-up lever and said needle, wherein, in said channel, said needle thread axis is substantially aligned with said channel axis;
- ii) beam generating means positioned on one side of said channel for generating an optical beam of predetermined width transverse to said channel axis and intersecting at least a portion of said channel;
- iii) means for controlling a position of said needle thread in said channel so that said thread passes through at least a portion of said beam; and
- iv) beam detection means positioned on a side of said channel opposite said beam generating means for detecting said optical beam;
- whereby movement of said needle thread through said optical beam is detected due to differences in thread characteristics along a length of said thread.
- 15. The improvement according to claim 14 wherein said channel is of sufficient size to substantially constrain movement of said looper thread within a predetermined region, said region begin determined by said predetermined width of said beam.
- 16. The improvement according to claim 15 further comprising means for storing predetermined values corresponding to thread movement during said predetermined portion of said stitch cycle.
- 17. The improvement according to claim 16 further comprising means for comparing said stored values with thread movement during said predetermined portion of said stitch cycle.
- 18. The improvement according to claim 15 further comprising means for generating an output signal representation of said stitch signal.
- 19. A method for detecting a needle loop skip during chainstitch formation using a chainstitch sewing machine, said machine including:
- an axially reciprocal needle adapted to receive at least one needle thread and form a succession of stitches where each stitch is formed during a stitch cycle, said needle being movable along a longitudinal needle axis;
- a reciprocal needle thread take-up lever;
- a drive motor having an output shaft, and means associated with said shaft for driving said needle through at least one reciprocal motion per stitch;
- a looper thread assembly including looper means for incorporating a looper thread to said needle thread when forming said stitches during one stitch cycle, and a looper thread tension assembly and associated delivery means for delivering said looper thread to said looper means, said looper thread being disposed in part along a looper thread axis extending between said looper thread tension assembly and said looper means; said method comprising the steps of:
- a) detecting needle thread movement along a portion of a needle thread axis extending between said needle and said take-up lever during a predetermined portion of each stitch cycle;
- b) detecting each shaft rotation during each said stitch cycle;
- c) correlating said needle thread movement and said shaft rotation during said stitch cycle to identify instances of substantially no needle thread movement; and
- d) generating a signal representative of said instances of substantially no needle thread movement, said signal being indicative of a needle loop skip.
- 20. The method of claim 19 wherein said step of detecting said needle thread movement further comprises the step of detecting differences in thread surface characteristics as at least a portion of said needle thread passes through an optical beam,
- whereby said optical beam is generated by a beam generator, passes through a beam channel that is at least partially transverse to a thread channel through which said needle thread passes, and is detected by a beam detector means opposite said beam generator.
- 21. A method for detecting a triangle loop skip during chainstitch formation using a chainstitch machine, said machine including:
- an axially reciprocal needle adapted to receive at least one needle thread and form a succession of stitches where each stitch is formed during a stitch cycle, said needle being movable along a longitudinal needle axis;
- a reciprocal needle thread take-up lever;
- a drive motor having an output shaft, and means associated with said shaft for driving said needle through at least one reciprocal motion per stitch;
- a looper thread assembly including looper means for incorporating a looper thread to said needle thread when forming said stitches during one stitch cycle, and a looper thread tension assembly and associated delivery means for delivering said looper thread to said looper means, said looper thread being disposed in part along a looper thread axis extending between said looper thread tension assembly and said looper means;
- said method comprising the steps of:
- a) detecting looper thread movement along a portion of a looper thread axis extending between said looper thread tension assembly and said looper means during a predetermined portion of each stitch cycle;
- b) detecting each shaft rotation during each said stitch cycle;
- c) correlating said looper thread movement and said shaft rotation during said stitch cycle to identify instances of substantially no looper thread movement; and
- d) generating a signal representative of said instances of substantially no looper thread movement, said signal being indicative of a triangle loop skip.
- 22. The method of claim 21 wherein said step of detecting said looper thread movement further comprises the step of detecting differences in thread surface characteristics as at least a portion of said looper thread passes through an optical beam,
- whereby said optical beam is generated by a beam generator, passes through a beam channel that is at least partially transverse to a thread channel through which said looper thread passes, and is detected by a beam detector means opposite said beam generator.
- 23. The improvement according to claims 1 or 7 or 13 wherein said looper thread detection means comprising:
- i) thread positioning means for establishing an elongated region extending along a thread feed axis and adapted to position said thread with a thread principal axis substantially parallel to said feed axis with a lateral surface of said thread adjacent to a lateral boundary of said region at a reference point on said lateral boundary,
- ii) a beam guide including a block member having a lateral surface substantially tangent to said lateral boundary of said region near said reference point, said block member including an open-sided channel in said lateral surface and passing through said reference point, said channel extending along a linear channel axis, said channel axis being other than parallel to said feed axis,
- iii) a beam generator disposed at one end of said channel and including means for transmitting an optical beam in a direction parallel to said channel axis toward another end of said channel, said beam having a cross-section, and
- iv) a beam detector disposed at the other end of said channel and including means for detecting portions of said beam incident thereon from said channel and regions adjacent thereto, and including means responsive to said detection for generating a signal representation of the intensity of the optical beam incident on said detecting means, said signal being representative of the variation in the lateral surface of thread passing through said region in the direction of said feed axis.
- 24. The improvement of claim 23 wherein said lateral surface of said block member is convex about a block axis extending in a direction other than parallel to said feed axis.
- 25. The improvement of claim 24 wherein said block axis extends in a direction substantially perpendicular to said feed axis.
- 26. The improvement of claim 25 wherein said thread positioning means includes means for defining said feed axis to curve around said convex lateral surface of said block member.
- 27. The improvement of claim 23 wherein said thread positioning means includes an arm having a pressure surface on a side of said region opposite said reference point, and includes means for biasing said pressure surface toward said reference point.
- 28. Apparatus for detecting motion of a thread in a direction of a thread principal axis, said thread having an irregular lateral surface, comprising:
- a) thread positioning means for establishing an elongated region extending along a thread feed axis and adapted to position said thread with a thread principal axis substantially parallel to said feed axis with a lateral surface of said thread adjacent to a lateral boundary of said region at a reference point on said lateral boundary,
- b) a beam guide including a block member having a lateral surface substantially tangent to said lateral boundary of said region near said reference point, said block member including an open-sided channel in said lateral surface and passing through said reference point, said channel extending along a linear channel axis, said channel axis being other than parallel to said feed axis,
- c) beam generator disposed at one end of said channel and including means for transmitting an optical beam in a direction parallel to said channel axis toward another end of said channel, said beam having a cross-section including the portion of said region adjacent to said channel, and
- d) beam detector disposed at the other end of said channel and including means for detecting portions of said beam incident thereon from said channel and regions adjacent thereto, and including means responsive to said detection for generating a signal representation of the intensity of the optical beam incident on said detecting means, said signal being representative of the variation in the lateral surface of thread passing through said region in the direction of said feed axis.
- 29. The apparatus of claim 28 wherein said lateral surface of said block member is convex about a block axis extending in a direction other than parallel to said feed axis.
- 30. The apparatus of claim 29 wherein said block axis extends in a direction substantially perpendicularly to said feed axis. PG,48
- 31. The apparatus of claim 30 wherein said thread positioning means includes means for defining said feed axis to curve around said convex lateral surface of said block member.
- 32. The apparatus of claim 28 wherein said thread positioning means includes an arm having a presser surface on a side of said region opposite said reference point, and includes means for biasing said presser surface toward said reference point.
CROSS-REFERENCE TO THE RELATED APPLICATION
This is a continuation-in-part application of U.S. patent application Ser. No. 577,852 filed on Sep, 7, 1990, entitled "Apparatus for Detecting Skipped Stitches", now U.S. Pat. No. 5,140,920.
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DEX |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
577852 |
Sep 1990 |
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