JPH06115139A - Method of controlling thermal printer - Google Patents

Abstract

PURPOSE:To make it possible to shorten the time required for printing one dot line and moreover to prevent a power source from operating immoderately even when the time of electrification of heating resistors is long. CONSTITUTION:A drive period of a thermal head 1 is the sun of two times: the time which is determined by determining necessary impression energy for heating resistors of the thermal head 1 by using a drive voltage of the thermal head 1 measured by a voltage measuring circuit 2, the temperature of a base of the thermal head 1 measured by a temperature measuring circuit 3 and the number of electrified dots of the heating resistors counted by a counting circuit 4, by calculating the time of electrification for each drive by using the necessary impression energy; and the resting time aimed at recovering the capacity of electrification of a power source and the time of electrification in each discrete drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer control method and, more particularly, to a high speed printing of a thermal printer which prints on paper by a line dot type thermal head.

In recent years, thermal printers have been utilized in various fields because of their advantages such as quietness, high speed, and maintainability. Further, there is a strong demand for reduction in size and weight, and at present, products that can be driven by a battery have been commercialized. Further, it is also desired to speed up printing.

[0003]

2. Description of the Related Art In the above-mentioned battery-powered thermal printer, since the output voltage of the power source (battery) used is lower than that of the commercial power source, the thermal energy generated by the heating resistor of the thermal head is large. Can not. For this reason, one dot line of the thermal head is divided into a plurality of heating resistor blocks (hereinafter abbreviated as blocks), and printing of one dot line is performed repeatedly by energizing each block in sequence. The timing for driving this head is shown in the timing chart of FIG.

In FIG. 4, T1 is a driving cycle, T2 is a time for energizing the heating resistor, and T3 is a rest time.
The energization time T2 is a variable value that is changed according to the driving voltage of the thermal head, the ambient temperature, the number of energized dots, and the like in order to apply the required applied energy for making the print density appropriate to the heating resistor. The rest time T3 is the energization time T
It is the time provided to wait for the recovery of the energization capacity of the battery that has been reduced by the energization of No. 2, and the time required for the recovery is
It becomes longer as the energization time T2 becomes longer. Therefore, the driving cycle T1 is a time obtained by adding the maximum assumed value of the energization time T2 to the maximum assumed value of the rest time T3, and is the same fixed value in each block. Therefore, the time required to print one dot line is always constant.

Therefore, in order to increase the printing speed, only the paper feed during non-printing is driven at high speed.

[0006]

However, in the method of driving only the above-mentioned paper feed at high speed, the effect of speeding up is exhibited when the printing rate is relatively low, but the effectiveness is high when the printing rate is high. It is lost and the fruit of speedup does not go up. Therefore, in order to increase the speed even when the printing rate is high, the time required for printing one dot line may be shortened.

Further, since the driving cycle T1 of the thermal head is constant, the energization time T2 may be almost equal to the driving cycle when the power supply voltage is low or the ambient temperature is low, and the rest time T3 can be taken. It will run out of power as it runs out.

The present invention relates to a thermal printer which prints on paper by a line dot type thermal head.
Enables shortening of the time required to print dot lines,
It is an object of the present invention to provide a thermal printer control method that does not force the power supply even if the energization time to the heating resistor becomes long.

[0009]

FIG. 1 is a diagram for explaining the principle of the present invention. In order to achieve the above object, in the thermal printer control method according to the present invention, referring to FIG.
The drive cycle of the thermal head 1 is the drive voltage of the thermal head 1 measured by the voltage measurement circuit 2 and the temperature measurement circuit 3
Using the information of the substrate temperature of the thermal head 1 by the measurement of and the number of energized dots of the heating resistor of the thermal head 1 by the counting circuit 4, the required applied energy and the required applied energy to the heating resistor are calculated. It is characterized in that the energization time calculated for each drive is calculated, and the time is set to the energization time added to the energization time for each individual drive, which is a guideline for recovering the energizing ability of the power supply. In the figure, reference numeral 5 is a control circuit for driving the thermal head 1 by setting the energization time and the driving cycle as described above.

The driving cycle of the thermal head 1 is characterized in that the cycle of the maximum response frequency of the stepping motor for feeding the paper is set to be the shortest, and is different from the cycle of the resonance frequency of the stepping motor. It has a feature.

[0011]

In the prior art, the driving cycle of the thermal head 1 is set to the time obtained by adding the maximum expected value of the energization time to the maximum expected value of the energization time, as described in the above-mentioned drive cycle T1. The time required for printing is always constant. By the way, looking at the actual energization time and rest time in this drive cycle, the energization time is mostly shorter than the maximum expected value of the above energization time, and accordingly, the rest time is further deducted from the maximum expected value of the above rest time. It becomes longer and there is a great waste of the required downtime.

The present invention focuses on this point. That is, the energization time and the rest time according to the present invention are the actual energization time and the required rest time, and the driving cycle of the present invention according to the energization time and the rest time is a variation value according to the energization time for each thermal head drive. Thus, the driving cycle becomes shorter than the conventional driving cycle, and the time required for printing one dot line is shortened.
Even so, even if the energization time is long, the required downtime is secured, so that the power source will not be forced. The ambient temperature for changing the energization time is represented by the head substrate temperature.

The present invention, which shortens the time required for printing as described above, is extremely effective in increasing the printing speed.

[0014]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 2 is a block diagram showing the configuration of the embodiment, and FIG. 3 is a head drive timing chart of the embodiment. FIG. 3 corresponds to FIG. 4 described above.

In FIG. 2, the drawing mainly shows the thermal head drive circuit in the thermal printer. Reference numeral 11 is a main MPU that is in charge of the main control of the printer, 12 is a sub MPU that determines the energization time and drive cycle of the thermal head drive and counts the number of energized dots, and 13 is an A / D converter Yes For measuring drive voltage and substrate temperature of thermal head,
Reference numeral 14 is an interface circuit for inputting data and commands from the host, 15 is a RAM for temporary work memory such as a buffer for print data, 16 is an RO
M is a unit for storing program codes and parameters for controlling the MPUs 11 and 12, 17 is a line dot type thermal head, and 18 is a stepping motor for feeding paper. By contrast with FIG. 1 described above,
The MPUs 11 and 12 correspond to the counting circuit 4 and the control circuit 5,
The A / D converter 13 corresponds to the voltage measuring circuit 2 and the temperature measuring circuit 3, and the thermal head 18 corresponds to the thermal head 1. The temperature detecting element for measuring the head substrate temperature is a thermistor.

In this embodiment, a print command is first transferred from the host to the main MPU 11 via the interface circuit 14. In the main MPU 11, the reference applied energy determined by the type of the thermal paper to be used is written in the common access area on the RAM 15, the print data for one dot line is expanded and written in the common access area on the RAM 15, and then the sub MPU 12 is executed. To the heating resistor of the first block of the thermal head 17 to which current is to be applied. RAM in sub MPU12
The print data of one dot line developed on 15 is read out, transferred to the line shift register in the thermal head 17, the number of energized dots of the print data is counted for each block, and temporarily saved in the RAM 15.

After transferring data for one dot line,
The sub MPU energizes the heating resistor of the block. At this time, the temperature measurement A / D converter 13 is operated to measure the substrate temperature of the thermal head 17, and the measurement result is stored in the RAM 15
Evacuate to the top. A / D converter 13 for voltage measurement after energization
Is operated to measure the applied voltage during energization. The measurement result and the temperature information and the energization dot number information saved in the RAM 15 are taken in to obtain the thermal work generated by the heating resistor of the thermal head at present, and the reference application written in the common access area on the RAM 15 is applied. The energization time T5 of FIG. 3 is determined from the energy.

The sub MPU 12 monitors the elapsed time of energization, and when the energization time T5 is reached, energization to the block is stopped and an energization completion notice is sent to the main MPU 11. When the main MPU 11 receives this energization completion notification, the rest time T6 of FIG. 3 is set based on the recovery of the energization capability of the power source after energization, and after the rest time T6 has elapsed, the stepping motor 18 is driven and An energization execution instruction of the block of is given to the sub MPU 12. The pause time T6 set here corresponds to the current capacity of the power supply, and therefore may be 0 if the current capacity is sufficiently large. The period from the start of the energization time T5 to the end of the rest time T6 following the energization time T5 is the drive cycle T4 of FIG. 3, and the same processing is sequentially executed thereafter.

The thermal work and the energization time T5 may be determined by an algorithm according to the processing capacity of the sub MPU 12 or may be developed as a parameter on the ROM 16 and obtained by a table lookup method.

In FIG. 3, the driving cycle T4 and the energization time T
5, the rest time T6 is the drive cycle T of FIG. 4 described above.
1, the energization time T2, and the rest time T3. However, as can be understood from the above description, the dwell time T6 becomes shorter than the conventional dwell time T3, and the difference becomes larger as the energization time T5 becomes shorter. Therefore, the driving cycle T4 is set every time the block is driven. While varying, in most cases of each drive, it becomes shorter than the conventional drive cycle T1. Therefore, the time required for printing one dot line in the embodiment is shorter than the same time as the conventional one. Then, this speeds up printing.

The power supply voltage may be low or the ambient temperature may be low, so that the energization time T5 may be long, but even in that case, the required rest time T6 can be secured, so that the power supply is not overpowered. .

By the way, the driving cycle T4 may be shorter than the cycle of the maximum response frequency of the stepping motor 18. In that case, in order to secure the normal sheet feeding, the drive period T is increased by increasing the pause time T6.
4 should not be shorter than the cycle of the maximum response frequency.

Similarly, the driving cycle T4 may coincide with the cycle of the resonance frequency of the stepping motor 18.
In that case, in order to suppress the noise of the motor 18, it is preferable that the drive period T4 is made different from the period of the resonance frequency by adjusting the pause time T6.

Although the respective constituent elements are independent in FIG. 2, a part or all of them may be integrated as a control LSI.

[0025]

As described above, according to the present invention, a thermal printer for printing on a paper by a line dot type thermal head makes it possible to shorten the time required for printing one dot line and still generate heat. A thermal printer control method is provided that does not force the power supply even if the energization time to the resistor becomes long, and it has the effect of enabling high-speed printing while corresponding to the current capacity of the power supply. .

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a block diagram showing the configuration of the embodiment.

FIG. 3 is a head drive timing chart of the embodiment.

FIG. 4 is a conventional head drive timing chart.

[Explanation of symbols]

 1 Thermal Head 2 Voltage Measuring Circuit 3 Temperature Measuring Circuit 4 Counting Circuit 5 Control Circuit 11 Main MPU 12 Sub MPU 13 A / D Converter 14 Interface Circuit 15 RAM 16 ROM 17 Thermal Head 18 Stepping Motor

Claims (3)

[Claims] 1. A method for controlling a thermal printer that prints on paper by a line dot type thermal head, wherein a driving cycle of the thermal head is a driving voltage of the thermal head measured by a voltage measuring circuit, and a temperature measurement. Using the information of the substrate temperature of the thermal head measured by the circuit and the number of energized dots of the heating resistor of the thermal head measured by the counting circuit, the required applied energy and the required applied energy to the heating resistor are calculated. The thermal printer is characterized in that the energization time calculated for each drive is obtained, and the energization time is added to the energization time for each individual drive and a rest time based on the recovery of the energization capability of the power source is added. Control method. 2. The thermal printer control method according to claim 1, wherein the driving cycle of the thermal head is such that the cycle of the maximum response frequency of the stepping motor for feeding the paper is set to the shortest. 3. The thermal printer control method according to claim 1, wherein a driving cycle of the thermal head is different from a cycle of a resonance frequency of a stepping motor for feeding a sheet.