Browse Prior Art Database

Failure Detector for Fuser Temperature Sensors

IP.com Disclosure Number: IPCOM000051039D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Korsch, RF: AUTHOR [+2]

Abstract

Output levels from both the temperature sensor for a fuser hot roll and the thermal overtemperature fuse associated with that roll are compared to indicate proper operation prior to use in a copier.

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Failure Detector for Fuser Temperature Sensors

Output levels from both the temperature sensor for a fuser hot roll and the thermal overtemperature fuse associated with that roll are compared to indicate proper operation prior to use in a copier.

Fuser 10 has a thermal overtemperature fuse component 11 which engages the sensor strip surface of roll 10, as does thermistor element 12. Both components 11 and 12 are typically encapsulated in graphite as shoes for engaging the surface of roll 10. Lead 14 for thermistor 12 is typically coupled to the input of a temperature control logic circuit. The outputs of elements 11 and 12 are coupled by leads 15 and 16 into respective buffer amplifiers 20 and 21. The normal, quiescent operation of elements 11 and 12 in a usual application produces a difference voltage of 100 MV or less between leads 15 and 16. The remaining circuitry serves to detect whether the assembly of shoes 11 and 12 on roll 10 is likely to produce a proper output prior to powering the copier in which roll 10 and elements 11 and 12 are mounted. An indication by thermistor 12, by fuse shoe assembly 11 or by the combination of shoes 11 and 12 and hot roll 10 (high resistance) falsely suggesting a high temperature produces a response by the machine controls to remove power from the machine. Contamination or improper adjustments produce improper or erroneous outputs from thermistor 12 and shoe 11.

Buffer amplifiers 20 and 21 handle a wide range of input impedan...