JPH0331564Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head driving circuit, and more particularly to a thermal head high speed driving circuit.

In general, writing is performed on recording paper by arranging a plurality of heating elements, for example 1280 dot heating elements, in a line and selectively generating heat from these dot heating elements, and then by connecting the dot heating elements and the recording paper. Thermal heads, which similarly write data on recording paper by shifting their relative positions, have been widely used as one of the conventional thermal printer systems. In such a conventional thermal printer system, a large number of 1280 dot heating elements arranged in a line are divided into several blocks, and the dot heating elements belonging to each block selectively generate heat. However, since the conventional thermal head drive circuit divided the dot heating element into blocks, the data to be processed could only be processed for each block, and it took a long time for the thermal head to generate heat. .
Furthermore, in a thermal head having a shift register, data input is only in one place, so the thermal head cannot be driven until all dots have been input, and data input takes time.

An object of the present invention is to provide a thermal head drive circuit that can drive a thermal head having such a shift register at high speed.

According to the present invention, a plurality of heating elements arranged in a line and a shift register corresponding to each of the heating elements are provided, and the heating element is caused to generate heat based on data input to the shift register. In a thermal head drive circuit that performs recording, there is a second shift register group divided into a plurality of blocks, and a second shift register group provided corresponding to each register of the second shift register group and connected in series to a data input. , a first shift register group consisting of a plurality of shift registers driven at a higher speed than the second shift register group, and an output of each shift register of the first shift register group to each shift register of the second shift register group. A thermal head drive circuit is proposed which is characterized by providing a group of gate circuits to which gate control signals are input in parallel.

Embodiments of the thermal head drive circuit according to the present invention will be described in detail below with reference to the drawings.

Figure 1 shows a conventional thermal head drive circuit.
Give an example. In FIG. 1, input data is applied to a shift register 1, and when the input of data to the shift register 1 is completed, the data is transferred to each dot heating element 2a, 2b, . . . 2 of a thermal headblock 2.
Heat is generated by flowing through the n, and writing is performed on the recording paper by the heat generated. The thermal head block 2 is selected and written to by strobing the transistor 3 commonly connected thereto with a strobe pulse. In the circuit shown in FIG. 1, the shift register 1 is generally formed by a CMOS integrated circuit, but the shift register 1 is formed by dot heating elements 2a, 2b, . . . , 2n.
Transistors are used because they require sufficient current to generate heat.

Since the thermal head drive circuit formed as shown in Figure 1 inputs data to only one place, the thermal head cannot be driven until all data is input, and furthermore, it takes a long time for the dot heating elements to generate heat. was. FIG. 2 shows a thermal head drive circuit according to the present invention to solve this problem.

FIG. 2 shows a driving circuit for a thermal head according to the present invention, in which the thermal head and shift register are divided as shown in the figure.
Shift register 12a of shift register group 12,
12b,..., 12n and the second shift register group 13
shift registers 13a, 13b,..., 13n
and gate circuits 14a, 14 connected between the first shift register group and the second shift register group.
It is constituted by a gate circuit group 14 consisting of gate circuits b, . . . , 14n. In FIG. 2, registers 12a, 12b, .
The respective outputs of gate circuits 14a, 14b, . . . , 12n are applied to first input terminals of gate circuits 14a, 14b, . As a result, the gate circuits 14a, 14b,...,
The outputs of 14n are sent to shift registers 13a and 14n, respectively.
13b, . . . , 13n are sequentially input from the least significant digit to the most significant digit. Thereafter, a strobe signal is applied to the transistor 15, and the outputs of the shift registers 13a, 13b, . . . , 13n are applied to the thermal heads 11a, 11b, . . In other words, the shift registers 12a to 12a-1 are
Data is previously set in the shift registers 13a to 13d via the register 2d.

The operation of the drive circuit shown in FIG. 2 will be explained with reference to the waveform diagram shown in FIG. First, shift registers 12a, 12
Since high-speed shift registers are used in the shift registers 12a, 12b, . This time is shown in Figure 3a. If the thermal head is divided into four parts as shown in Figure 2,
The input data of 1280 dots is sent to each shift register 12.
320 dots are accommodated in a, 12b, ..., 12n. Each first shift register 12a, 12b,
..., 12n, the outputs of the gate circuits 14a, 14b, ..., 14n are controlled by the gate control signal shown in FIG.
are sent in parallel to each shift register 13a, 13b, . . . , 13n of the second shift register group. Shift registers 13a, 13b,..., 13n
are normally output transistors that supply heating current to the dot heating elements of a thermal head, and are allowed to be driven at low speed.
The data shown in e is printed at a very low speed, for example within about 4000 .mu.s, by the strobe signal shown in FIG. 3g.

As explained in detail above, in the present invention, the thermal head is divided into n parts, and a buffer for holding the data for each dot heating element of the divided thermal head is configured by a shift register, and this shift register is also divided into n parts. Data is written at a speed n times faster than a conventional thermal head drive circuit by dividing the data into n parts, the same number as n, and inputting data in parallel from a group of high-speed shift registers connected in series to this shift register. Therefore, the effect of the present invention is extremely large in high-speed driving.

[Brief explanation of the drawing]

Figure 1 shows a conventional thermal head drive circuit.
For example, FIG. 2 shows an embodiment of a thermal head drive circuit according to the present invention, and FIG. 3 shows an operation time chart of the circuit shown in FIG. In FIG. 2, 11a, 11b,..., 11n
are thermal head groups, 12a, 12b,..., 12
n is a high-speed shift register, 13a, 13b,...,
13n is a low-speed shift register.

Claims (1)

[Scope of utility model registration request] A thermal head that includes a plurality of heating elements arranged in a line and a shift register corresponding to each of the heating elements, and performs recording by causing the heating elements to generate heat based on data input to the shift register. In the drive circuit, a second shift register group 13 divided into a plurality of blocks is provided corresponding to each register of the second shift register group 13, and is connected in series with the data input, and the second shift register group 13 is divided into a plurality of blocks. A first shift register group 12 consisting of a plurality of shift registers driven at a higher speed than the second shift register group 13; 1. A thermal head drive circuit comprising a gate circuit group 14 for applying gate control signals to be input in parallel to a register.