Position adjusting drive unit

A position adjusting drive unit for a rotary shaft of a machine, particularly a sewing machine, comprising a driving electrical motor having an adjustable rotary speed;

• an electrical speed regulating circuit for said motor;
• an electrical angular position adjusting circuit for the rotary shaft of the machine;
• said circuits including means for generating signals corresponding to desired values of the rotary speed and of the angular position and to actual values of the rotary speed and of the angular position;
• a common circuit board detachably connected to the motor, said board supporting and interconnecting the electrical and mechanical component parts of said circuits;
• said means for generating electrical signals including a plurality of light barriers controlled by a stop plate having stop apertures arranged according to a code for generating a digital code of the desired value signals;
• and electrooptical signal generating-and-receiving means arranged in a modular unit;
• said modular unit including a plurality of light-emitting diodes arranged at different levels in a pack, a corresponding plurality of photo-transistors arranged at corresponding levels and at a spaced relationship from said light-emitting diodes, an intermediate partition extending in a part of the space between said diodes and phototransistors and having a free edge stepped according to the levels of said diodes, a stop plate slidable in the remaining interspace between said diodes and said phototransistors and having one edge thereof stepped in a complementary fashion relative to the stepped edge of said intermediate partition to provide adjustable stop apertures, and further including fixed stop apertures arranged at the level of respective steps;
• and said means for generating the desired value electrical signals including at least one light barrier controlled by a stop plate.