Stitch length control for electronic sewing machine

Claim 1

A sewing machine with needle reciprocating means, needle bight actuating means and feed actuating means for use in forming a succession of stitches individually placed in a selected pattern, said sewing machine including: a. static memory means in which a multiplicity of separate digital code words for controlling the needle bight actuating means and feed actuating means are stored in a predetermined sequence; b. pattern controlling switch means accessible to a sewing machine operator and effective to impress on said static memory a signal identifying as a starting word in a pattern a specific one of said multiplicity of separate digital code words which correspond to individually placed stitches; c. means for producing timing pulses related to the operation of the needle reciprocating means; d. stitch lengthening switch means; e. an address counter coupled to the static memory and responsive to the timing pulses in one position of the switch means for successively addressing the digital code words in said memory in said predetermined sequence beginning with said starting word identified by the pattern controlling switch means and thereby causing the needle to assume a bight position and work to be fed according to the addressed code words such that stitches may be formed according to the selected pattern as the needle is moved into and out of the work by the reciprocating means; f. control circuitry connected to the address counter and responsive to said timing pulses in another position of the stitch lengthening switch means for limiting pulses controlling advances of the address counter to evenly spaced pulses separated by time intervals which are an integral multiple of the interval between the said timing pulses; g. latching means operatively connected to said control circuitry and effective with the stitch lengthening control switch means in said another position to prevent needle reciprocation except in response to the said evenly spaced pulses which cause stitches to be formed in work being sewn.