Patent ID: 6404208
Filing Date: 2002-06-11
Classification: B41J,G01R

Abstract:
A resistance data measure device for a thermal head, said thermal head having plural heating elements arranged along a line and connected in parallel with one another, a respective one of said heating elements being connected to one of plural heat control switches, said heat control switches being selectively turned on/off for driving said heating elements individually by applying electrical energy to generate heat, said resistance data measure device comprising:a capacitor connected in parallel with said plural heating elements; a charging switch for charging said capacitor; a voltage detector for detecting a capacitor voltage across said capacitor; a reference resistor connected in parallel with said plural heating elements and said capacitor; an additional switch connected to said reference resistor; a control circuit for controlling said heat control switches, said charging switch and said additional switch; said control circuit initially turning on said charging switch to charge said capacitor; turning off said charging switch to stop charging said capacitor upon an increase of said capacitor voltage to a predetermined high voltage; and thereafter turning on one selected from a group including said additional switch and said plural heat control switches, to discharge said capacitor via said reference resistor or one of said heating elements in association with said selected one being turned on; a timer for measuring discharging time elapsed in a decrease of said capacitor voltage from said predetermined high voltage to a predetermined low voltage while said capacitor is discharged, in association respectively with said reference resistor and said heating elements; and a resistance data determiner for determining resistance data of said heating elements in accordance with said discharging time respectively of said heating elements with reference to said discharging time of said reference resistor.