Pattern stitching speed control system for electronic sewing machines

Abstract

A drive motor drives a reciprocating sewing needle. A static memory has lateral-control-signal outputs at which it furnishes signals indicating how much the needle should be laterally shifted for each stitch in a selected pattern, and feed-control-signal outputs at which it furnishes signals indicating how much a work feeding device should feed the work for each stitch of the pattern. An addressing circuit response to a pattern selector applies to the static memory a repeated sequence of address signals, causing the memory to produce repeated sequences of lateral-control and feed-control signals at its outputs. The first address signal in any of the repeated sequences of address signals causes the static memory to produce at its output a first lateral-control signal constituting a maximum-speed-establishment signal, and a first feed-control signal constituting a maximum-permissible-speed signal. A latch receives the feed-control signals but does not in general register them, except when activated. A detector receives the lateral-control signals, and in response to the maximum-speed-establishment signal activates the latch which then registers the maximum-permissible-speed signal. A motor speed limiter limits the speed of the drive motor in dependence upon the signal registered by the latch.