JPH1120219A - Thermal recording printer - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a thermal recording type printing apparatus for recording on a recording material by applying a pulse current for thermal recording, the impedance of a power supply can be accurately measured with a simple configuration, and the power supply voltage fluctuates. Recording at a stable density. SOLUTION: At the start of printing, the input power supply voltage is measured when the motor is not operating and when the motor is operating, and the impedance of the power supply 2 is calculated from the difference between the measured input power supply voltages and the operating current value of the motor. At the time of printing, an applied current value is determined according to the number of dots to be printed.
The input power supply voltage during printing is calculated from the impedance of the print head and applied to the recording head with a pulse width corresponding to the input power supply voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording type printing apparatus which performs recording on a recording material by applying a pulse current for thermosensitive recording, and in particular, stabilizes the recording density with respect to fluctuations in power supply.

[0002]

2. Description of the Related Art Conventionally, in a thermal recording type printing apparatus, a pulse current is applied to a recording head by a voltage supplied from a power supply, and recording is performed on a recording material using Joule heat generated at that time. . The recording density is changed according to the magnitude of the heat energy.

At this time, since the voltage drop occurs due to the impedance of the power supply, it is necessary to know the input power supply voltage accurately. Therefore, conventionally, the following method is adopted.

(1) The input power supply voltage is measured before printing, and at the time of printing, the impedance of the power supply set in advance through experiments and the like and the current increase during printing are predicted, and the input power supply voltage supplied during printing is determined. Predict.

(2) At the time of printing, first, a pulse current for a short fixed time is applied, the input power supply voltage at that time is measured, and the subsequent pulse width is changed according to the voltage.

[0006]

However, the above-mentioned conventional methods (1) and (2) have the following problems.

In (1), when a plurality of power supplies having different impedances, such as a battery and a stabilized power supply, are used, a means must be provided for determining the connected power supply.

Since the impedance of a battery changes depending on the temperature and the number of charge / discharge cycles, it is difficult to set the impedance of the power supply in advance.

In the method (2), a high-speed voltage measurement unit and a high-speed control unit are required because the pulse width must be changed after the application of the heating pulse current.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can accurately measure the impedance of a power supply with a simple configuration, and can record data at a stable density with respect to a fluctuating power supply voltage. It is an object of the present invention to provide a thermosensitive printing device that can perform the printing.

[0011]

The thermal recording type printing apparatus of the present invention is constructed as follows.

(1) In a thermal recording type printing apparatus capable of changing the pulse width of a pulse current for thermal recording, a voltage measuring means for measuring an input power supply voltage, and a predetermined load to which operating power is supplied from the power supply. The input power supply voltage at the time of non-operation and at the time of operation of this load is measured, the impedance of the power supply is calculated using the measurement result, and the input supply power supply voltage at the time of printing is predicted from the impedance of the power supply, At the time of printing, a current having a pulse width corresponding to the predicted voltage is supplied.

(2) In the thermal recording printing apparatus of the above (1), the input power supply voltage at the time of printing predicts an applied current in accordance with the number of dots to be printed, and is calculated from the current value and the impedance of the power supply. I did it.

(3) The thermal recording printing apparatus according to the above (1) or (2), further comprising current measuring means for measuring the operating current of the load, and wherein the impedance of the power supply is determined when the load is not operating and when the load is operating. Is calculated from the difference between the input power supply voltages and the measured operating current value.

(4) In any one of the above-mentioned thermal recording printing apparatuses (1) to (3), the load is a driving motor used in the printing section.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a main part of a thermal recording paper type character device according to an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a printing unit that performs a printing operation, and 2 denotes a power supply that supplies power to the printing unit 1.

Reference numeral 3 denotes a control unit, which is a signal which designates head data (print data) 4 of a recording head (not shown) of the printing unit 1 and a pulse width (heat time) of a pulse current supplied to the recording head. Pulse 5, ON / OFF of power supply to motor for feeding paper (not shown) of print unit 1
A motor excitation control signal 6 for controlling OFF and a motor rotation control signal 7 for controlling the rotation of the motor are transmitted to the printing unit 1 to perform the above-described respective controls.

When printing is performed, the motor excitation control signal 6 is turned ON, the print data is transferred from the head data 4, and the head is energized (printed) with the pulse width of the heat pulse 5 as the heat time. Paper feed is performed using the control signal 7 as a timing pulse. Printing is performed by repeating these series of operations.

Reference numeral 8 denotes an AD converter (voltage measuring means) for measuring the voltage of the power supply 2, and a voltage value can be read by the control unit 3. Reference numeral 9 denotes a counter for counting the number of print data of the head data 4. The control unit 3 can clear the count and read the count.

Here, a method of measuring the impedance of the power supply 2 before starting printing will be described. The measurement of the impedance may be performed when the power is turned on or when a print start command is received.

An input unit not shown in FIG.
When the print start command comes to the control unit 3, the control unit 3 reads the voltage V 0 of the power supply 2 by the AD converter 8. Next, the voltage V1 is similarly read in a state where power is supplied to the motor with the motor excitation control signal 6 turned ON.

The relationship between the voltage V1 and the current Im flowing when the motor excitation control signal 6 is turned ON is determined in advance by an experiment.

FIG. 2 is a waveform diagram showing changes in voltage and current supplied from the power supply 2 with respect to the motor excitation control signal 6 at this time.

As shown in FIG. 2, the motor excitation control signal 6
Turns on, the current Im increases, and a voltage drop [V0-V1] occurs in the power supply voltage due to the impedance of the power supply 2. Thereby, the impedance Z of the power supply 2 is obtained by the following equation: Z = (V0−V1) / Im

Next, the operation at the time of printing will be described.

First, the voltage Va of the power supply 2 before printing is measured by the AD converter 8. Before starting printing,
It may be performed at such a frequency that the power supply voltage does not greatly change, for example, between lines where no printing is performed.

Next, the counter 9 is cleared, and the print data is transferred to the print unit 1 by the head data 4. At the end of the data transfer, the count value N of the counter 9 is read.

Next, when the current I that increases due to heat is predicted from the count value N, the known head resistance value R, and the power supply voltage Vb during printing, I = N × Vb / R.

Further, based on the impedance Z obtained before the start of printing and the voltage Va before printing, the power supply voltage Vb during printing is expressed as follows: Vb = Va−Z × I∴Vb = Va × R / (R + Z × N) You can ask.

The control unit 3 sets a heat pulse width corresponding to a printable voltage in advance, selects a heat pulse width corresponding to the obtained power supply voltage Vb during printing, and prints a heat pulse 5. This is output to the unit 1 for printing.

As described above, in the present embodiment, at the start of printing, the input power supply voltage when power is not supplied to the motor as a load and the input power supply voltage when power is supplied are measured by the AD converter 8. The impedance of the power supply 2 is calculated from the voltage difference and the value of the current flowing through the load, which can be known from the input power supply voltage at the time of supply. The power supply voltage supplied during printing is predicted by the voltage drop generated by the power supply impedance, and the pulse width according to the voltage is applied, so the power supply impedance can be accurately measured with a simple configuration. In addition, printing can be performed with stable recording density for power supplies having different impedances.

[0032]

As described above, according to the present invention,
In a thermal recording printing apparatus capable of changing a pulse width of a pulse current for thermal recording, a voltage measuring means for measuring an input power supply voltage and a predetermined load supplied with operating power from the power supply are provided. The input power supply voltage during non-operation and during operation is measured, the impedance of the power supply is calculated using the measurement results, and the input power supply voltage during printing is predicted from the impedance of the power supply. Since a current having a pulse width is supplied, the impedance of the power supply can be accurately measured with a simple configuration, and there is an effect that printing can be performed at a stable density for power supplies having different impedances.

Further, since the voltage measurement may be performed before the start of the measurement printing or between lines, there is an effect that a high-speed AD converter or the like is not required.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of a thermal recording type printing apparatus according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing changes in voltage and current supplied when a motor excitation signal is turned on.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printing part 2 Power supply 3 Control part 4 Head data 5 Heat pulse 6 Motor excitation control signal 7 Motor rotation control signal 8 AD converter (voltage measuring means) 9 Counter

Claims (4)

[Claims] In a thermal recording printing apparatus capable of changing a pulse width of a pulse current for thermal recording, a voltage measuring means for measuring an input power supply voltage and a predetermined load supplied with operating power from the power supply are provided. Measures the input power supply voltage when this load is not operating and when it is operating, calculates the impedance of the power supply using the measurement results, predicts the input supply power supply voltage at the time of printing from the impedance of the power supply, and prints A thermal recording type printing apparatus characterized in that a current having a pulse width corresponding to the predicted voltage is sometimes supplied. 2. The thermal recording method according to claim 1, wherein the input supply power supply voltage at the time of printing predicts an applied current in accordance with the number of dots to be printed, and is calculated from the current value and the impedance of the power supply. Printing device. And a current measuring means for measuring an operation current of the load, wherein an impedance of the power supply is calculated from a difference between an input power supply voltage when the load is not operated and an input power supply voltage when the load is operated, and a measured operation current value. The thermosensitive recording type printing apparatus according to claim 1 or 2, wherein: 4. The thermal recording paper type printing apparatus according to claim 1, wherein the load is a driving motor used in a printing unit.