Printer having energizing pulse width calculating means
First Claim
1. A thermal printer driven by a power supply having an internal resistance which varies depending upon a temperature thereof and having a plurality of heater elements arranged in a thermal head for effecting a print operation by supplying an energizing pulse in accordance with a print signal to respective heater elements, comprising:
- power supply temperature measuring means for measuring a temperature of the power supply;
storing means for storing a table showing a relationship between the temperature of the power supply and the internal resistance of the power supply; and
pulse width calculating means for acquiring, by referring to the table stored in the storing means, a corresponding resistance on the basis of the temperature measured by the temperature measuring means, and calculating a pulse width of an energizing pulse taking the resistance into consideration.
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Accused Products
Abstract
A thermal printer is provided in which unevenness of printing due to temperature changes of a power source, can be prevented from occurring as well as prevented useless power consumption with a simple configuration. The temperature of a cell is measured with a cell temperature measuring section, and by referring to a table showing a relationship between the temperature and the internal resistance of the cell, which is stored in ROM, corresponding resistance is acquired. An energizing pulse width for energizing each heater element of a thermal head is calculated while the above-mentioned resistance is taking into consideration, to thereby energize and drive the above each heater element.
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Citations
15 Claims
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1. A thermal printer driven by a power supply having an internal resistance which varies depending upon a temperature thereof and having a plurality of heater elements arranged in a thermal head for effecting a print operation by supplying an energizing pulse in accordance with a print signal to respective heater elements, comprising:
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power supply temperature measuring means for measuring a temperature of the power supply;
storing means for storing a table showing a relationship between the temperature of the power supply and the internal resistance of the power supply; and
pulse width calculating means for acquiring, by referring to the table stored in the storing means, a corresponding resistance on the basis of the temperature measured by the temperature measuring means, and calculating a pulse width of an energizing pulse taking the resistance into consideration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A printer comprising:
- a print head having a plurality of printing elements for performing a printing operation in response to the application of an energizing pulse to the printing elements;
a drive mechanism for causing relative movement between a paper and the print head so that the print head can print on the paper;
a power supply having an internal resistance which varies depending upon a temperature;
power supply temperature measuring means for measuring a temperature of the power supply;
a memory for storing a table containing a relationship between the temperature of the power supply and the internal resistance of the power supply; and
pulse width calculating means for determining the internal resistance of the power supply with reference to the table according to the temperature of the power supply measured by the temperature measuring means and calculating a pulse width of the energizing pulse taking the internal resistance into consideration. - View Dependent Claims (10, 11, 12)
- a print head having a plurality of printing elements for performing a printing operation in response to the application of an energizing pulse to the printing elements;
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13. A method for limiting the number of printing elements that can be simultaneously energized to conduct a printing operation in a print head having a plurality of printing elements of a battery-powered printer so that a predetermined maximum consumed current value is not exceeded during the printing operation, comprising the steps of:
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measuring a voltage and an internal resistance of the battery;
calculating a consumed current in a printing operation to be performed based on the measured voltage and internal resistance of the battery; and
calculating the maximum number of printing elements that can be simultaneously energized during the printing operation based on the calculated consumed current. - View Dependent Claims (14, 15)
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Specification