JPS62135382A - Driving system for thermal head - Google Patents

Abstract

PURPOSE:To reduce consumption of electric power at the time of thermal recording, by applying printing pulses with lower printing energy at the times other than the time of printing an image signal. CONSTITUTION:A thermal head performs a preheating driving 22 when an all-black signal 21 is inputted. Thereafter, when image signals 23, 24 for the first and second lines are inputted, printing in the first and second lines is conducted. When a period of time not shorter than the printing time for one line is present before an image signal 27 for the n-th line is inputted, an all- black signal 25 is inputted to again perform a preheating driving 26. At the time of the preheating driving, printing pulses with such printing energy as not to develop the color of a thermal recording paper are inputted to the thermal head, whereby the head is maintained at a fixed temperature. Therefore, when an image signal is inputted, the head instantaneously generates heat, whereby thermal recording can be performed with lower printing energy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] The present invention relates to a method for driving a thermal head in a thermal recording device.

[Technical Background of the Invention] Conventionally, in this type of device, when a printing pulse having printing energy is applied to the thermal head during double-signal printing, the thermal head inputs an image signal and prints the input image. A method was used in which each heating element was turned off based on a signal, and the heat generated caused the thermal recording paper to develop color to perform thermal recording.

[Problem with the long-awaited technology 1. However, in the above method, when printing image signals, the printing energy is suddenly increased to raise the temperature of the heating element, resulting in high power consumption. There were problems that hindered electrification.

[Object of the Invention] The present invention was developed in view of the above-mentioned problems, and the object thereof is to provide a method for driving a thermal head that can perform thermal recording with small printing energy.

[Placement type at the north gate] The present invention controls the temperature of the thermal head to be maintained at a temperature at which the thermal recording paper does not develop color by applying a small printing pulse of printing at the time other than the old paper where the image No. 8 is printed. This achieves the above objectives.

[Example 1 of North Gate Fruit of the present invention/8! An example will be explained in detail based on the drawings of FIGS. 1 to 5.

FIG. 1 is a block diagram of one embodiment of the present invention, 11
1 is an image signal generation circuit, and when the crest 8 is inputted from the input terminal 12, the image signal generation circuit 11 generates an image signal to be output to the thermal head 13. The thermal head 13 has a heating element circuit 14 and a nermistor 15, and the nermistor 15 outputs the thirst status information of the thermal head 13 to a timing pulse generating circuit 16. In the timing pulse generation circuit 16, when information such as 4131j of the thermal head is input, it outputs various timing pulses (wrap pulse, printing pulse, etc.) for driving the thermal head 13, and the thermal head 13 inputs 5 and 5 to these timing pulses. Then, the photothermal circuit 14 is driven to print an image signal on the thermosensitive recording paper. NaJ5.1
7 is a clock generation circuit that supplies clock signals to the image signal generation circuit 11, the thermal head 13, and the timing pulse generation circuit 16, and 1B is a power supply circuit that supplies power to each circuit.

FIG. 2 is a diagram showing an example of an image signal input sequence to the thermal head. First, when a print start signal @20 is input, the image signal generation circuit 11 outputs a black signal 21. When the thermal head 13 inputs an all-black signal, it performs a preheating drive 22 and heats the thermal body circuit 1/l to a temperature at which the thermal recording paper does not develop color.
is held, and its ((image signal 2 of the first and second line
When 3.2/l is input, the first and second lines are printed.

Next, when there is a time longer than the printing time of one line until both signals 27 at the n-line port are input, the thermal head 13 inputs the all-black signal 25 and performs preheating 1126 again.

Also, when there is a time longer than the printing time of one line between the image signal 27 at the beginning of the n line and the image signal 30 at the (1+1)th line, the all-black signal 28 is input as described above, and the preheating drive!
Perform J29. Then, when the printing end 1Δ bow 31 is input, the thermal head ends printing.

FIG. 3 is a diagram showing the driving circuit of the thermal head, and FIG. 4 is a diagram showing the operation of the thermal head in a time chart p-h.

In the drive circuit shown in FIG. 3, for example, the high level j%A is the clock B1. :J-S-! The signals are sequentially taken into a shift register 35 consisting of flip-flops. When the image number Ij taken into the shift register 35 corresponds to one line, the all-black image signal in the shift register 35 is transferred to the shoe 1 circuit 36 by the latch pulse C. Next, the all-black signal is input to each photothermal body 38 for each n block through the gate circuit 37 by printing pulses D1 to Dn of 1+nicles with a lower pulse width. Each photothermal body 3
No. 8 shows that the thermosensitive recording paper does not develop color due to the all-black No. 1 g manually applied paper (heated with light to a temperature of 7 degrees and preheated). Further, if the printing pulses D1 to Do with the pulse width T are inputted after T2 time has elapsed since the printing pulse is inputted, it is possible to carry out the preheating drive in two cycles. Therefore, until both signals for printing one line are taken into the shift register 35, the temperature of the thermal head is kept at a predetermined temperature at which the thermal recording paper does not develop color by repeating this cycle of preheating drive1. It becomes possible to hold the

Next, the image signals to be printed are sequentially fetched into the shift register 35 at clock B, and when the signal for one line is reached, both signals of the shift register 35 are transferred to the latch circuit 36 by the latch pulse C. Then, the image signal has a pulse width T
3, printing pulses D1 to D with small printing energy, to J
: is input to each photothermal body 38 through the gate circuit 37. Since each heating element 38 is maintained at a constant humidity, it instantaneously generates heat according to the input stroke No. 3, and prints data on the thermal recording paper.

By the way, the pulse widths of the printing pulses 01 to D are used to determine the energization time of the heating element 38, and are determined by the nermistor 15 provided on the thermal head (see FIG. 1).

The heating element 38 by the mark J+n of these printing pulses D1 to D
The thermal response waveform of is shown in FIG. 5(a).

In this waveform, if K'C is the coloring temperature of the thermosensitive recording paper, then T1 in (b) is the applied pulse width during preheating drive.

Note that the pulse period king can be treated as a fixed value, but in order to obtain a better effect, the temperature of the thermal head 13 is detected by the thermistor 15 provided in the thermal head 13, and the pulse period of T2 is controlled by that value. It is also possible to do so.

[Effect of the Invention 1 As explained above, the present invention provides an II system that avoids printing image signals.
(Thermal recording paper does not develop color at times other than between j) By appropriately inputting printing pulses with a printing energy of 1 degree, the thermal head can be maintained at a predetermined temperature 1y, so the printing energy is smaller than before. Thermosensitive recording can be performed with .

[Brief explanation of drawings]

Fig. 1 is a 10-step diagram of an embodiment of the present invention, Fig. 2 is a drawing showing an example of the sequence of inserting an image into a thermal head, and Fig. 3 is a diagram showing an example of the sequence of inserting an image into a thermal head. jl [x of the initial circuit, Figure 4 t shows the initial f1 of Figure 3, J time chart 1~, Figure 5 shows the thermal response waveform of the photothermal body for determining the pulse width T1. There is a diagram C. A...Both signals, B...Clock, C...Rudge pulse, D1-Dn...Print pulse, 11...Both signals f [forming circuit, 13...Thermal head, 14... Photothermal circuit, 15... Thermistor. Agent: Attorney Takahisa Kimura
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Claims (2)

[Claims] (1) In a thermal head drive method that prints image signals on thermal recording paper using input printing pulses, printing with a printing energy so small that it does not cause the thermal paper to develop color, other than the time during which the image signals are printed, is performed. A method for driving a thermal head, characterized in that the temperature of the thermal head is maintained at a temperature at which the thermal recording paper does not develop color by applying pulses. (2) When inputting a printing pulse with printing energy that does not color the thermal recording paper, the temperature of the thermal head is detected, and the pulse width or pulse period of the printing pulse is determined based on the detected temperature. The method of driving a thermal head according to claim 1, wherein the thermal head is controlled to be maintained at a predetermined temperature.