JPH022031A - Thermal head circuit - Google Patents

Abstract

PURPOSE:To perform good printing by applying the generation quantity of heat corresponding to the heat accumulation state of an indivisual heat generating resistor by providing a gate circuit, which changes the current supply time of the indivisual heat generating resistor to control the generation quantity of heat, between a shift registor and a heat generating resistor driver. CONSTITUTION:Printing data, wherein the generation quantity of heat of an indivisual heat generating resistor is set as a four-figure binary number, is read in a shift register 15 in synchronous relation to a data shift clock 1 to be inputted to a gate circuit 11 on the basis of data load 12. The gate circuit 11 includes four circuits of gate functions each counting and controlling a gate time with respect to the four-figure binary data and four sets of inputted gate time data are counted when a count pulse 13 is inputted and the output signals (G0-G3) of the gate circuit 11 are respectively outputted for the times correspond ing to the gate time data. The output signals (G0-G3) are connected to all of heat generating resistor drivers 10 but only heat generating resistors 14 to which printing strobes 0-3 are inputted are driven.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head circuit of a thermal recording type printing device used as a character/graphic output device.

[Summary of the invention]

The present invention comprises a thermal head circuit including a heating resistor, a heating resistor driver, a shift register, and a gate circuit,
Data corresponding to the amount of heat generated by each heating resistor is received from the outside for each heating resistor, and using a gate circuit, the data is converted into the energization time of the heating resistor, and the heating resistor is driven. , the amount of heat generated is controlled.

[Conventional technology]

Conventionally, as shown in FIG. 3, a heating resistor 14, a heating resistor driver 10, a register 9, and a shift register 8 are included. The operation will be explained according to FIG.

Print data 2 is the heating resistor 14, (R15 to RO)
It is a signal that indicates whether to energize or not (if the heating resistor is to be energized in the future, it will be written as on, if not, it will be written as off), and it corresponds to the heating resistor 14 (R15 to RO). will be sent sequentially. The print data 2 is read into the shift register 8 in synchronization with the data shift clock 1. In the conventional example shown in Fig. 3, four 4-bit shift registers are connected, and 16 heating resistors (R15
RO).

These connections are known as thermal head circuits regardless of the number of heating resistors. When the print data 2 is read, the data latch 3 is controlled and the read print data 2 is transferred to the register 9. At this point, the print data to be printed next to the print data 2 read just starts to be read. This operation is shown in FIG. 1 during period T2.

During the period, the heating resistor driver 10 controls the printing strobes 0 to 3, and according to the printing data transferred to the register 9, the heating resistor driver 10 controls the corresponding 1 heating resistor, 14 (R15 to RO).
Turn on and off. In FIG. 4, the printing strokes 1 to lobes O to 3 are controlled to overlap in time. This is caused by controlling all the heating resistors 14 (R15 to RO) at the same time. This is to avoid concentration of current.

[Invention or problem to be solved]

Conventional thermal head circuits use only printed data that does not give meaning to the energization of individual heating resistors as information for driving the heating resistors. Therefore, the amount of heat generated by the heating resistors that are driven at the same time is the same. there were. For this reason, due to the heat accumulation phenomenon of the thermal head, even if the heat accumulation state of each heating resistor differs depending on past printing data, it is not possible to individually control the amount of heat generated in response to these conditions, resulting in good printing operation. It was difficult to do so. In addition, when printing a connected gradation image by controlling the coloring state by the amount of heat generated using sublimable dyes, etc., conventional technology requires complicated printing data processing and it is difficult to achieve good printing characteristics. There were many cases.

[Means to solve the problem]

In order to solve the conventional problems, the present invention provides a heating resistor,
It consists of a heating resistor driver, a gate circuit, and a shift register.

[Effect]

Print data weighted to correspond to the amount of heat generated by one heating resistor is read into the shift register. The read print data is serial-parallel converted,
It is input to the gate circuit and held internally by the data rope signal. The gate circuit counts the input count pulses for the held print data and compares them with the input data. When the count pulse number reaches the held data, the counting operation is stopped. During this time, a gate signal is output. The gate signal is input to a heating resistor driver, and the heating resistor driver circuit drives the heating resistor according to the gate signal.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, shift register 15 is a 16-bit serial input, parallel, serial output shift register. Print data 2 is read into the shift register 15 in synchronization with the data shift clock 1, with the amount of heat generated by each heat generating resistor as a 4-digit binary number. The read print data is serial-parallel converted and sent to each heating resistor.
The data is outputted as 4-bit gate time data and inputted to the gate circuit 11 through a data load 12. 'The gate circuit 11 has four built-in gate functions for counting and controlling gate time for four-digit binary data.

The four sets of input gate time data are counted when the count pulse 13 is input, and the output signals (G, to G,) of the gate circuit 11 are output for a time corresponding to each gate time data. The output signals (G, ~Gi) are connected to all the heat generating resistor drivers 10, but only those to which print strobes 0 to 3 are input drive the heat generating resistors. The operation will be described in detail below according to FIGS. 1 and 2.

The print data 2 and the print data r3 above are generated by the heating resistor 1 in synchronization with the data shift clocks to, tl, R2, and t3.
4 bits are read into the shift register 15 as the heat generation amount of R3 at 4.

Similarly, the heat generation amount corresponding to R2, R1, and RO in the heat generating resistor 14 is sequentially changed to the data shift clock, t4 to t1.
All are loaded in sync with 5.

In this way, when the calorific value data corresponding to the four pieces R3-R4 is read, the data load signal tL is output.
The data is serial-parallel converted and sent to gate circuit 1.
It is input to the input terminal Do-=D3 of No. 1 and is held internally. In addition to reading the data corresponding to R3, R2, R1, and RO in the heating resistor 14, the operations performed during the 73rd period include reading data corresponding to R7 in the heating resistor 14, which is immediately read into the gate circuit 11. , R6, R5, and R3, but in this operation, R3, R2, R1, and R
A case will be described in which the data read into O is output as a gate signal during the T4 period.

Data load 12) When the load signal tL (start of T4 period) is output, the gate circuit 11 outputs T
The counter gate output in the four periods is output to each heating resistor, the counter gate output G3 is output to R3, and similarly, G2 is output to R2, G1 is output to R1, and Go is output to RO. be done.

When the load signal tL is output to the data load 12, pulses for counting (tco, tcl~) are output on the count pulse 13 in accordance with the above operation, and the gate circuit 11 counts the count pulses 13. The generation of gate signals by these counting operations is not based on the thermal head drive circuit of the present invention, but is a well-known means for generating timing pulses in general. Therefore, the details of the counting operations will not be described, and FIG. explain.

When tc5 is output on count pulse 13, (R
Regarding 3), the counter gate G3 is no longer output, but this is because the value read as data of R3 in the heating resistor 14 matches the count number. Similarly, the counter gate output G2 stops outputting at the count pulse tc, G1 stops outputting at tcll, and GO stops outputting the output at tc13. As a result, the output time of the counter gate output signal is determined in accordance with the print data read corresponding to each heating resistor.

Counter gate outputs GO to G3 are input to four heating resistor drivers 10. These heating resistor drivers 10 drive the heating resistors 14 only when print strobes 0, -3, 4 to 7 are output, and T
During the fourth period, only the print strobe of 0.4 is output, and ROlRl, R2, and R3 in the heating resistor 14 are driven.

During the T4 period, not only the counter gate output control described above but also the print data r15, rl4, r
Read l3 and rl2.

These operations include print data, r3, r2, rl, ro
As explained above.

As described above, the print data is sequentially read and the heating resistor 14 is driven.

In this embodiment, the shift register shown in FIG.
The number of digits is in bits, but the number of digits can be increased or decreased as necessary. The gate circuit 11 counts pulses for a four-digit binary number, but the number of digits and data expression may be changed as necessary.The gate circuit outputs a counter circuit and a gate signal. It may be composed of a logic circuit.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the amount of heat generated is controlled by giving different energization times to each heating resistor, and the amount of heat generated according to the heat storage state of each heating resistor is given, resulting in a good result. 6 having the feature of printing

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention.
FIG. 3 is a block diagram showing a conventional example, and FIG. 4 is a timing diagram showing a conventional example. 8.15...Shift 1 to register 9...Register 10...Heating resistor driver 11...Gate circuit

Claims (1)

[Claims] a heat generating resistor; a shift register that outputs energization information to the heat generating resistor; and a heat generating device that is located between the heat generating resistor and the shift register and selectively drives the heat generating resistor in response to an output from the shift register. In the heating drive circuit for a thermal head having a resistor driver, a gate circuit is provided between the shift register and the heating resistor driver to change the energization time of each heating resistor and control the amount of heat generated by the heating resistor. A thermal head circuit characterized by the provision of a thermal head circuit.