Browse Prior Art Database

Self Diagnostic Motor Overcurrent Protection for a Printer

IP.com Disclosure Number: IPCOM000050860D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Kelly, MJ: AUTHOR [+4]

Abstract

Printers are employing more DC motors and stepper motors for machine functions. These devices are conventionally controlled by driver cards including microprocessors. The motors which are controlled by the driver cards and microprocessors are normally protected from overcurrent by individual fuses or bulk power supply fuses. This growing number of fuses not only increases the manufacturing cost of the printer, but also increases the service cost because some diagnostic information is not made available to the machine operator.

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Self Diagnostic Motor Overcurrent Protection for a Printer

Printers are employing more DC motors and stepper motors for machine functions. These devices are conventionally controlled by driver cards including microprocessors. The motors which are controlled by the driver cards and microprocessors are normally protected from overcurrent by individual fuses or bulk power supply fuses. This growing number of fuses not only increases the manufacturing cost of the printer, but also increases the service cost because some diagnostic information is not made available to the machine operator.

Turning now to the drawing, if any one of the four motors 7 or driver cards 6 develops s short circuit, the resulting voltage drop across the sense resistor RS is detected by a voltage comparator 3. This low voltage detection signal (LVDT) is sent to the microprocessor 5 which in turn shuts off the series power transistor 2 to the power supply 1. The machine microprocessor 5 may determine which motor 7 was turned on when the LVTD occurred and display a problem code on the display 8. This problem code number may identify which motor/driver caused the fault. If one of the motors 7 should stall, it could draw enough current to overheat without being detected by the LVDT circuit. This problem may be detected by the motion detector or encoder 9 located on each motor shaft. When the microprocessor 5 turns a motor on and no motion is detected by the encoder 9, that motor driver may be turn...