Method and apparatus for varying the length or stitches sewn by a sewing machine in dependence upon sewing speed

A method for controlling seam lengths in a sewing machine having a material feed, a reciprocable needle for stitching seams in material and a microprocessor controller having a memory comprising the steps of:

• detecting a material discontinuity in advance of a seam;
• controlling the reciprocable needle to sew a variable number of stitches after detecting said material discontinuity;
• and
• adjusting said variable number of stitches to be sewn in dependence upon the sewing speed at the time said material discontinuity is detected.

In a sewing machine having a reciprocable needle for stitching seams in material, seam length control apparatus comprising:

• means for detecting a material discontinuity in advance of a seam;
• means for controlling the reciprocable needle to sew a variable number of stitches after said detecting means detects said material discontinuity;
• and
• means for adjusting said variable number of stitches to be sewn in dependence upon the sewing speed at the time of detection of said material discontinuity, said adjusting means comprising,
• means for determining the sewing speed at the time of detection of said material discontinuity;
• and
• means for comparing said sewing speed to a predetermined reference speed.

A method for controlling seam lengths in a sewing machine having a material feed, a reciprocable needle for stitching seams in material and a microprocessor controller having a memory comprising the steps of:

• detecting a material discontinuity in advance of a seam;
• controlling the reciprocable needle to sew a variable number of stitches after detecting said material discontinuity;
• and
• adjusting said variable number of stitches to be sewn in dependence upon the sewing speed at the time said material discontinuity is detected, said adjusting step comprising:
• determining the sewing speed at the time said material discontinuity is detected;
• comparing said sewing speed to a predetermined reference speed;
• and
• adjusting said stitches to be sewn by a factor equal to the ratio of said predetermined reference speed to said sewing speed.