Patent ID: 6382758
Filing Date: 2002-05-07
Classification: B41J

Abstract:
A printhead temperature monitoring system, comprising:at least first and second printheads; at least first and second temperature sensitive resistors, each associated with a respective printhead; a capacitor with each of said temperature sensitive resistors selectively connectable in line with said capacitor for delivering charging energy to said capacitor; a voltage level detection circuit for monitoring a voltage level across said capacitor as it is charged; a counter associated with said voltage level detection circuit to maintain a running count as said capacitor is charged until said voltage level across said capacitor reaches a threshold level; a processor connected for reading a count value of said counter and operable to determine a printhead temperature based at least in part upon said count value; a timer circuit for providing signals to interrupt inputs of said processor; and an interrupt control circuit connected between said timer circuit and said processor for selectively controlling application of said timer circuit signals to an FIQ interrupt of said processor and an IRQ interrupt of said processor.