US 5,852,369 A · Thermal printer and resistance data measuring device for thermal head of the same

Abstract

A thermal head of a thermal printer has plural heating elements arranged along a line and connected in parallel with one another. A respective one of the heating elements is connected to one of plural heat control switches, which are selectively turned on/off for driving the heating elements individually by applying electrical energy to generate heat. To measure resistance data of at least one of the heating elements, a capacitor is connected in parallel with the plural heating elements. A reference resistor is connected in parallel with the plural heating elements and the capacitor. The capacitor is charged, and then discharged via the reference resistor or the one of the heating elements. A voltage across the capacitor is detected. An amount of discharging time required to decrease the capacitor voltage from a predetermined high voltage to a predetermined low voltage is measured while the capacitor is discharged, in association respectively with the reference resistor and the heating elements. Resistance data for the heating elements is determined in accordance with the discharging time of the heating elements, respectively, with reference to the discharging time of the reference resistor.

Claims16

Dependent claims

A resistance data measuring method for a thermal head having plural heating elements arranged along a line and connected in parallel with one another, said heating elements each 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 measuring method comprising:

charging a capacitor connected in parallel with said plural heating elements to a predetermined high voltage;
after charging said capacitor, discharging said capacitor via one of a reference resistor and one of said heating elements, said reference resistor being connected in parallel with said plural heating elements and said capacitor;
measuring an amount of time that elapses while a capacitor voltage measured across said capacitor decreases from said predetermined high voltage that is lower than a source voltage to a predetermined low voltage, said amount of time being based on a resistance of said one of said reference resistor and said one heating element;
and
determining resistance data for said one heating element based on said amount of time measured.

2 more elements

A resistance data measuring method, comprising:

charging a capacitor to a first predetermined voltage;
discharging charge stored in the capacitor using a selected one of plural heating elements positioned in parallel with the capacitor;
measuring a first amount of time that elapses when a voltage of the capacitor is decreased from the first predetermined voltage to a second predetermined voltage based on the selected heating element, where the first predetermined voltage is lower than a supply voltage and the second predetermined voltage is lower than the first predetermined voltage;
and
calculating resistance data related to the selected heating element based on the first amount of time measured.

2 more elements

Dependencies are inferred from the claim text.

Thermal printer and resistance data measuring device for thermal head of the same

Life of this patent

Thermal printer and resistance data measuring device for thermal head of the same

Life of this patent

Abstract

Claims16