Forms Pedestal Switching Testing
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
There is described herein a circuit for diagnostically testing an open-loop forms feed motor system by checking the pedestal switching time. The forms drive in some printers may be an open-loop stepper motor driven system where the major components are the motor, driver board, and predriver card. The predriver card is essentially a memory device that translates input commands, such as stop or run, into motor commands and causes the correct switching of the appropriate stepper motor coils. In addition to this open-loop function, there exists a closed-loop function that operates the pedestal portion of the driver circuit. The pedestal feedback method allows coil current to be sensed and compared to a predetermined reference. When peak current is reached, the comparator fires, switching off the pedestal function.