×

Sensing the temperature of a printhead in an ink jet printer

  • US 5,881,451 A
  • Filed: 06/21/1996
  • Issued: 03/16/1999
  • Est. Priority Date: 06/21/1996
  • Status: Expired due to Term
First Claim
Patent Images

1. A method for improving the accuracy of a temperature sensing thermistor integrated into a substrate comprising the steps of:

  • forming a temperature sensing thermistor on the substrate;

    the thermistor forming one leg of a bridge circuit and having a resistance R1 =Rt =ro (1+aΔ

    T) where a is the temperature coefficient of resistance (TCR);

    ro is the resistance at a set point temperature To and Δ

    T is the difference in temperature between the temperature T to be measured and the set point temperature To,forming a plurality of fractional thermistors adjacent the temperature sensing thermistor such that their TCR values are substantially identical to that of the temperature sensing thermistor, and having a combined resistance of fR1 where f=1-B/a, where B is a preselected minimum TCR value, andincluding the fractional thermistors and an external resistance Rx =ro (1-f) in a leg of the bridge circuit which is adjacent to the R1 leg which contains the temperature sensing thermistor.

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×