Thermal printer and device and method for measuring resistance of heating element of thermal head of thermal printer
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Mar 11, 2003
Grant Date -
May 3, 2001
app pub date -
Dec 6, 2000
filing date -
Dec 7, 1999
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A thermal head of a thermal printer is provided with an array of parallel connected heating elements and transistors connected in series to the heating elements in one to one relation. In a resistance measuring mode, one of the transistors connected to one heating element whose resistance is to measure is turned on, and other transistors are turned off. In this condition, a capacitor connected in parallel to the heating element is charged up to a predetermined voltage, and then discharged. A counter circuit starts time-counting by a short unit time t0 when a predetermined delay time T min has passed since the start of discharging, and outputs a count Q when the charged voltage goes down to a predetermined level. Based on a discharge time T=T min+t0.multidot.Q, the resistance of the heating element is calculated.
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