Error-Detection Circuit for Drive Circuit for Stepper Motor
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
An error-detection circuit detects a high current in the drive circuit for a stepper motor used, for example, in a printer and, on detection of the high current, switches off the drivers in the drive circuit and carries out reliability and servicing (RAS) tests. The error-detection circuit also senses when the current in one phase of the motor has reached a steady state during RAS tests and during slewing of the motor. The figure illustrates half of the drive circuit of a stepping motor incorporating the error-detection circuit. When drivers T1 and T2 are switched on, the current builds up exponentially through coil L1 until the voltage across R5 is equal to VREF1. This causes the output of the comparator C1 to reset latch LH1 and shut off driver T1.