Control system for providing stitch length control of a sewing machine

A seam length control apparatus for use with a sewing machine having a reciprocable needle and a reversing mechanism comprising:

• means for detecting the edge of the material being sewn in advance of the seam;
• means for controlling the reciprocable needle to sew a variable number of stitches after said detecting means detects the edge of the material;
• means for determining the length of the stitch being sewn at the time of detection of the edge of the material;
• and
• means responsive to said determining means for operating the reverse mechanism of the sewing machine in a limited manner such that the length of only the last stitch sewn in the seam is less than the length of the remainder of the stithces in the seam.

The method of operating a sewing machine having a reciprocable needle for stitching seams in material, comprising:

• detecting a material discontinuity in advance of a seam;
• controlling the reciprocable needle to sew a variable number of stitches after said material discontinuity is detected;
• and
• varying the length of only the last seam stitch by a variable amount in response to the detection of said material discontinuity.

The method of operating a sewing machine having a reciprocable needle comprising:

• detecting the edge of the material being sewn in advance of the seam being sewn;
• detecting the amount of completion of the stitch being sewn at the time of detection of the edge of the material;
• and
• varying the amount of completion of only the last stitch sewn in the seam by a variable amount in response to the detected amount of completion of the stitch.

The method of controlling seam length with a sewing machine having a reciprocable needle and a reversing mechanism comprising:

• detecting the edge of the material being sewn in advance of the seam;
• controlling the reciprocable needle to sew a variable number of stitches after the edge of the material is detected;
• determining the length of the stitch being sewn at the time of detection of the edge of the material;
• and
• responsive to said determining, operating the reverse mechanism of the sewing machine in a limited manner such that only the last stitch sewn in the seam is less than the length of the remainder of the stitches in the seam.