JPS60196062A - Driver of thermal head - Google Patents

Abstract

PURPOSE:To increase a printing speed by supplying an analog signal synchronizing with a line to an analog shift register by a clock pulse signal of a prescribed frequency to convert it into a parallel signal, and supplying the signal fed from a memory storing the parallel signal to a thermal head resistor. CONSTITUTION:The video signal supplied to a gate circuit 2 is sampled by the pulse signal produced from a clock pulse generator CPG3 as shown in a figure (B) and for a supply period of a gate pulse shown in a figure(D). These sampled video signals are supplied in series to an analog shift register CCD4 in the form of the data signals shown in a figure (A) which indicate the coloring concentration corresponding to a line of a group of thermal heads equivalent to the number of (n) units of thermal head resistors. These data signals are stored to a memory 6 in a close period of the CCD4 as shown in a figure (C). The output of the memory 6 is supplied to n-stage drivers 7 of the same number as thermal head resistors and then to (n) units of thermal head resistors 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal head drive device, and more particularly to a thermal head drive device that achieves high printing speed.

(Prior Art) Conventionally, thermal transfer printers have been widely used as devices for recording image information such as Combi Coater Graphics because of their simple mechanism, high recording speed, and easy handling. It is well known that

This type of thermal transfer printer is configured to perform transfer recording by pressing recording paper through a transfer paper (ink sheet) between a cylindrical platen that is rotationally driven by a pulse motor, etc., and a thermal head. ing. The thermal head is a line type, and consists of a group of heating elements arranged in a row in the width direction of the platen and the recording paper.The current flowing through each heating element is appropriately controlled, and the points on one line are After printing, the platen is rotated to print the next line, and this process is sequentially repeated to print 7J-1 monitor image information, etc. consisting of desired characters and figures on the recording paper.

In addition, as a method of driving a thermal head, the printing temperature during transfer is changed by pulse width modulation of a pulse applied to the thermal head. This requires a relatively long pulse application width, and the 1I11 degree of the printed point is determined by the area of the ink dissolved by the thermal head, that is, the area of the transferred ink.
When a constant voltage is applied to the thermal head, the application time of the electric current and the electric current at any point are approximately proportional to each other. Therefore, when printing using this conventional method, the pulse period must be equal to or longer than the time required for printing at the maximum capacity.
Therefore, a relatively long pulse application width is required, and the driving time of the thermal head becomes considerably long.

Therefore, for example, when printing a screen consisting of 1024 lines with 4TlIS/line, 4X1024-/1096
This contradicts the time required in ([5)].

Therefore, generally yellow (Y), magenta (M).

If you try to transfer the four colors of cyan (C) and black (B) in an overlapping manner, it will take four times as long to transfer the four colors, 16, /Is.
(seconds) of time would be wasted by simply applying the pulse (1,:()). Actually, in addition to this, recording paper J3 J:
It is used for transferring paper and transfer paper. ] Since this method requires a time comparable to the transfer time described in Section 2, it has drawbacks such as the fact that it is extremely difficult to increase the speed of printing.

(Objective of the Invention) The present invention has been made in view of the above-mentioned drawbacks of the conventional technology, and the object of the present invention is to control the printing temperature by changing the pulse width applied to the thermal head for a short fixed period of time and changing the voltage value. The purpose is to speed up printing by changing the speed.

(Structure of the Invention) In order to achieve the above object, the present invention provides means for supplying an analog one-cog signal synchronized with a line to an analog shift register using a clock pulse signal of a predetermined frequency and converting it into a parallel signal; The present invention provides a thermal head driving device characterized by comprising a memory for storing the parallel signal and means for applying the signal from the memory to a redundant head resistor.

(Example) FIG. 1 is a block tie gellumn of a thermal head driving device according to the present invention, and FIG. 2 is an explanatory diagram of its operation.

In both figures, one input terminal 1 of the gate circuit (G1) 2 is supplied with an analog signal such as a video signal, and the other input terminal is supplied with the output of a clock pulse generator (CPG) 3. ing.

The video signal entering the circuits 1 to 2 is generated by a clock pulse generator (CPG) 3 during the arrival period of the gate pulse as shown in FIG. 2(D). Limbed by the acceptance pulse signal, n
An analog data signal (not shown in the figure (Δ)) indicating the color density corresponding to one line of a thermal head group consisting of a number corresponding to the number of thermal head resistors Serially supplied to shift 1 register (COD)'l.

The video signal for one line supplied to the CCD/I is stored in it, and then transferred to the memory 6 via the switch circuit (SW) 5, as shown in FIG. is memorized.

The output of the memory 6 is supplied to a driver 7 having the same number of stages as the number of thermal head resistors, and then to a normal head resistor 8 consisting of n pieces.

A signal for one pixel supplied from COD'1 is supplied to a driver 7 via a matching circuit including a switch 5 and a memory 6 as described below.

The signal for one pixel supplied from C0D4 is supplied to the input terminal 9 of FET + as shown in Fig. 3, and after that, when the signal of CON1-1 is applied to the gate of E-1 , FET+ is closed (ON>) and the number 1 for one pixel is stored (memory) in the content-C. After being amplified by the amplifier 10, it is connected to the multi-head resistor via the driver 8. Furthermore, when the other FET2 is in the open (ON> state) due to the signal of C0NT2, the content-C is grounded and no signal is output.

Here, during the high level period of the pulse shown in FIG. Correspondingly, with the circuit configuration shown in FIG. 3, a predetermined voltage is applied to the thermal head resistors 8 connected to each, and the thermal head resistors 8 are heated in accordance with this voltage.

Since the relationship between the voltage applied to the thermal head resistor 8 and the print density is as shown in FIG. 4, the above application type j]
The print density will be controlled according to -.

In this way, the time for applying voltage to the thermal head resistor 8 is kept approximately constant, and the applied voltage is changed according to the data, thereby controlling the printing density, so that the time required for printing is is shortened, making it possible to speed up printing.

Note that FIG. 2 ([) shows the state of movement of the ink sheet and recording paper, and it is understood that at a high level, these move, and at a low level, they are stationary.

As described above, in the thermal head driving device according to the present invention, the printing 8 degrees is controlled by controlling the magnitude of the voltage applied to the thermal head, so that a predetermined printing density can be achieved. It has the advantage of saving the time required to cover the paper and making it possible to speed up printing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the thermal head drive 1 PII device according to the present invention, and FIG. 2 (A) to (
F) is an explanatory diagram of the operation, FIG. 3 is a diagram showing an embodiment of the circuit used in the present invention, and FIG. 4 is a print density-applied voltage characteristic diagram. 3... Ri1 Kotsuku pulse generator, 4... Analog shift 1 to register, 5... Switch circuit, 6...
・Memory, 7...driver, 8...thermal head resistor. Patent Applicant Victor Company of Japan Co., Ltd. Figure 2 CC) UW Figure 8 0 [1110% honey□

Claims (1)

[Claims] means for supplying an analog signal synchronized with the line to an analog shift register using a clock pulse signal of a predetermined frequency and converting it into a parallel signal; a memory for storing the parallel signal; and a thermal head resistor for transmitting the signal from the memory. A driving device for a thermal head, comprising means for applying an electric current to the thermal head.