JPS6129559A - Driving device for printing in heat-transfer recording device - Google Patents

Abstract

PURPOSE:To reduce the capacity of a power supply by detecting the maximum rated temperature of a radiator plate in the power supply and mounting the power supply inhibiting charging to an output capacitor and a printing control section varying the period of printing in response to the detection of return voltage. CONSTITUTION:When the temperature of a radiator plate for a driving power supply 4 is detected and exceeds a rated temperature, a charging current value to an output capacitor for the power supply is lowered, and a charging time to the capacitor is retarded. In a printing control section 1, on the other hand, the volage of the power supply 4 is monitored, and the operation of printing is enabled instantaneously when driving voltage reaches to a printable level immediately before printing. When voltage does not reach to the printable level, however, the next driving of printing is delayed for a uniform and fixed time, mean power on printing is lowered, an excess over a rated value of a temperature in the power supply is prevented, and the operation of printing is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an input/output device for an information processing terminal, and particularly to a print drive device in a thermal transfer recording device.

(Prior art) At present, efforts are being made to improve the printing quality and printing performance of thermal transfer recording devices that use conventional line-type heads. The trend is toward density, and the printing speed is 6 to 7 pages/minute on A4 paper, and the printing cycle is 5 to 6 m.
The speed is increasing around the s/dot line.

(Problems to be Solved by the Invention) Along with this, the capacity of the power supply that drives the thermal head has increased, and for example, at 240 dots/inch, the resistance of the thermal head is 500Ω/total, and the total number of dots in one line has increased. 2432
(B4 size), apply 20V voltage, and print data.
The current and power of the driving power supply when the tee has a period of 6 ms and a driving width of 1 ms are as follows.

Io=201500-2342-1/6=16(A)
−・−・−=−(1) Po=20X16 = 32
0 (W:] -... (2) However, equations (1) and (2) apply when the print data is all black dots.

Furthermore, the ratio of black dots printed in actual practical work is about 30% compared to the case of all black dots.

The current and power of the drive power supply at this time are as follows.

Ishi=16・0.3=4.8 (A)
・・・・・・・・・(3) Pshi=20・4.8=96[
W] ・・・・・・・・・(4) Therefore 9
Although the 6W rating would be almost too much, considering print quality and performance, the capacity was set at around 320W, which was necessary to ensure even when the black rate was high.

With the demand for compact, lightweight, and low-priced thermal heads for use in business machines, lower capacity, smaller size, and lower prices have become an issue by reducing the power consumption of thermal heads and improving the efficiency of use of the drive power source. .

An object of the present invention is to provide an efficient, compact, and low-cost thermal transfer recording device that significantly reduces the drive power capacity of a thermal head without significantly degrading printing quality or printing performance.

(Means for Solving the Problems) The present invention includes a power source 4 that detects the maximum rated temperature of a heat sink inside a power source of a thermal transfer recording device and suppresses charging current to an output capacitor by detecting the temperature; The apparatus includes a print control section 1 that detects the state of the return voltage of the output voltage and arbitrarily changes the printing cycle according to the detection of the return voltage.

(Function) When the temperature of the heat sink inside the power supply is detected and exceeds the rated temperature,
Decrease the charging current value to the output capacitor of the power supply and delay the charging time to the capacitor.

On the other hand, the print control unit 1 monitors the power supply voltage, and if the drive voltage reaches a printable level immediately before printing, immediate printing drive operation is possible, and if the voltage has not reached the printable level, then , the next printing drive is uniformly delayed for a fixed period of time, the average power during printing is reduced, and the printing operation is performed while taking into account that the temperature inside the power supply does not exceed the rated value.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

In this example, a line type thermal head with 240 dots/inch was used, and the total number of dots was 2432 dots) (B4 size)
To print one dot line, 1216 dots are printed twice each.

The drive power supply 4 is designed to have a capacity that satisfies the black dot rate at a practical level, and in the case of a printing date with a black dot rate exceeding the set and rated capacity, the temperature of the heat sink inside the power supply should be adjusted. When detected and the permissible temperature is exceeded, the charging current to the output capacitor of the power supply is reduced by an arbitrary amount to delay the time it takes to reach the rated voltage value, thereby preventing thermal breakdown of the power supply.

The printing operation under the above conditions will be explained.

Referring to the block diagram of FIG. 1, when the print control section 1 receives print information from a higher level, it first stores print data in the thermal head 2 serially. Thereafter, when the print control section 1 sends a drive signal to the print drive section 3- which supplies power to the thermal head 2, the drive power source 4 is transmitted twice during an arbitrary time period t via the print drive section 3. The thermal heads are energized separately and the printing operation for one dot line is completed.

Waveforms A and B in FIG. 2 are output voltage waveforms of the print drive unit 3. Further, the charging/discharging waveform of the terminal voltage of the output capacitor of the drive power source 4 at the time of printing is waveform C.

Normally, when continuous operation is performed at a black dot rate of 30 inches or less, the voltage of the output capacitor of the drive power supply 4 does not have the waveform of the solid line a, and the printable voltage level is reached in a shorter time than the regular printing cycle T. Since the return can be completed up to S, the printing operation continues at all times with the printing cycle T.

Next, when the printing operation with a black dot rate exceeding 30% continues and the internal heat sink temperature of the drive power supply 4 reaches the maximum allowable temperature, the output capacitor of the power supply is automatically charged. The time is delayed by ΔT from the time it was previously operating within the permissible temperature range, and continues until the temperature of the power supply internal heat sink drops to the permissible range.

The waveform will already appear. Then, after the time T has elapsed after printing and immediately before starting the next printing operation, the print control unit 1 detects whether the output voltage of the drive power source is at a printable voltage level,
If the level has not yet been reached, the next printing start time is uniformly delayed by ΔT, and then the printing operation is started.

Therefore, if the rated capacity of the drive power source 4 is exceeded, continuous operation will be performed at a printing cycle of T'. However, when printing at T', the printing density will be slightly lighter than that at cycle 1, so
It is necessary to correct the drive pulse width slightly wider.

In addition, since the black dot rate in normal printing is around 30%, the printing performance is not degraded, and even when the black dot rate is high, the printing operation is made possible by delaying the cycle. It is.

(Effects of the Invention) As described above, according to the present invention, the power supply capacity can be reduced by 70 chips compared to the conventional method, and printing with a high black dot rate can be performed, and printing quality and printing speed can be minimized in practical terms. This has the effect of realizing lower capacity, lower cost, and smaller size than conventional devices without any disadvantages.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a print control system showing one embodiment of the present invention, and FIG. 2 is a voltage waveform diagram of each part of the print control system. DESCRIPTION OF SYMBOLS 1... Print control section, 2... Thermal head, 3... Print drive section, 4... Drive power supply. ° ni no Figure 2

Claims (1)

[Claims] (1) Detecting the maximum rated temperature of the heat sink inside the power source of the thermal transfer recording device, and detecting the state of the power source that suppresses the charging current to the output capacitor and the return voltage of the output voltage of the power source by detecting the temperature; 1. A print drive device for a thermal transfer recording device, comprising a print control section that arbitrarily changes a print cycle in accordance with detection of the return voltage.