Stepper Motor Phase Protection Circuit
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2005-Feb-16
In a printer having a motor driven carriage, the circuit which controls the motor driver is designed to permit half-stepping of the stepper motor. The microcontroller that permits the half- stepping has four output phases: A, A not, B, and B not. These outputs are transmitted to the inputs of the driver circuit which controls the stepper motor. The protection circuit disclosed is inserted between the microcontroller and driver circuit, and it prevents the driver circuit from simultaneously receiving both the A and A not phases or both the B and B not phases. Receipt of a signal plus its inverse could damage the driver circuit as well as the stepper motor. The protection circuit consists of two open-collector TTL buffers.