Automatic buttonhole apparatus for use with sewing machine

In a sewing machine having a frame having a bed,

• a needle mounted on said frame for endwise reciprocation and sidewise movement to form zig-zag stitches of variable bight, bight stitch forming instrumentalities operatively connected to said needle, a work feeding mechanism, a main drive shaft, a motor connected to said drive shaft, static memory means for storing feed information and bight information for successive stitches, pulse generating means operatively connected to said main shaft for generating timing pulses in synchronism with the rotation of the main shaft, counter means responsive to said pulse generating means for counting said timing pulses for successively addressing said static memory means, means connected to said static memory means for reading feed information and bight information from said addressed static memory means for controlling said bight stitch forming instrumentalities and said work feed mechanism, a presser bar and presser foot for holding work on said machine bed, a shoe mounted on said presser foot so as to be slidable in a work feed direction, first means operatively connected to said shoe for generating an analog voltage signal related to the extent of movement of the shoe, second means for generating an analog voltage signal related to the extent of the size of the buttonhole to be stitched, and means responsive to said first and second means for acting on said static memory means when said analog voltage signals coincide with each other for varying the sequence of information stored in the static memory.