JPS62286373A - Thermal head driving method - Google Patents

Abstract

PURPOSE:To reproduce a proper density and to obtain uniform dot area by generating two correction data for Odd and Even is reyard to an attended picture element by refering to the data longitudinally and vertically separated from an attended picture element by prescribed number of dot lines and driving a head in accordance with the resulting data. CONSTITUTION:At time of printing, signals for the registers A-G in a 3-bit shift register group 22 for dot data reference come to be valid, and the following data are inputted to a thermal control ROM 23: dot data D and E in the right- side and left-side neighborhoods of the attended dot data X, the dot data A before the data X by one line and the dot data F and G in the both side neighborhoods of the data A, dot data B before by two lines, and dot data C before by three lines. The data X is converted by referring to the dot data in its surroundings thus inputted, and stored in an eight division line buffer 24. The buffer 24 includes two sets A and B which execute reading and writing alternately. The read out data are decoded by a pulse width conversion part 25, so that an Odd-Even separating part 26 sends either of the Odd and Even dot data in accordance with a signal from a system controller.

Description

Detailed Description of the Invention Technical Field The present invention relates to a thermal printer or facsimile machine that records characters, images, etc. by heating thermal paper or an ink sheet using heat generated by an element of a thermal head.
The present invention relates to a thermal head driving method for driving the element.

Previously, the elements were divided into ○dd dots and Ev8n dots and driven, but because the thermal correction was not sufficient, the trailing dots were affected by the leading dots, resulting in insufficient dot area. It was uniform.

Purpose It is an object of the present invention to provide a method for driving a thermal head that allows appropriate density to be reproduced and a uniform dot area to be obtained.

Structure: In order to perform appropriate thermal correction, the present invention creates two correction data, one for odd and one for even, for the pixel of interest by referring to data before a predetermined dot line, data after a predetermined dot line, and data next to a predetermined dot from the pixel of interest. create,
The feature is that the thermal head is driven according to the data.

Next, the embodiment will be described in detail.

FIG. 1 shows an overall outline of a color thermal printer whose thermal head is driven by the method of the present invention. In the figure, the system control (10) is the CPU
, and performs overall sequence control according to operations on the operation panel (11). The mechanism section (12) includes a stepping motor, a cutter motor, a sensor, and the like. The data source (13) is the part that becomes the host machine, and contains image data.

Generates character data, print commands, etc. The power supply voltage controller (14) corrects the power supply voltage of the thermal head (15) according to the environmental temperature.

The character generator (CG) & printer controller (16) compiles commands sent from the data source (13) and converts character codes into image data. The data converter (17) converts this image data into data suitable for the thermal head (15), and also performs thermal correction as described below.

FIG. 2 shows the specific configuration of the data converter (17). This data converter (17) includes a format converter (
18), an n-1 line storage register (19), an n-2 line storage register (20), and an n-3 line storage register (19), which have storage sections for MSB and LSB, respectively.
21), a 3-bit shift register group for dot data reference (22), a thermal control ROM (23), an 8-division line buffer (24), a pulse width converter (25),
It consists of a dd-even distribution section (26).

Normally, when printing an image, the character signal from the CG & printer controller (16) is
It is HJ level. At this time, dot data reference 3
A-B-C- in bit shift register group (22)
The signals in the D-E-F-G registers become valid, and the dot data D and E adjacent to the dot data X of interest and the dot data A one line before.

The adjacent dot data FG, the 2-line previous dot data B, and the 3rd line previous dot data C are stored in the thermal control ROM (2
3) is input.

After conversion is performed with reference to the dot data of interest or the peripheral dot data input in this way, it is stored in the 8-divided line buffer (24). The storing order is shown in FIG. FIG. 4 shows how dots are referenced on an actual printed surface. Dots X-A to G in the same figure
correspond to shift registers X-A to G in FIG.

There are two sets of 8-divided line buffers (24), A and B, and as soon as one line of data becomes full in A, reading of data begins in B. When A becomes full, the data is decoded by the pulse width converter (25), and then the 5th As shown in the figure, either odd dot data or even dot data is sent to the thermal head (15).

FIG. 6 shows the address decoding method in the thermal converter ROM (23). Notice the upper 4 bits of the ROM.The converted value when dot X is Even.The lower 4 bits.

The converted values when the dot
The ven switching circuit (27) outputs the dots X of interest separately depending on whether they are odd dots or even dots.

In addition, the data decoding method in the pulse width converter (25) is shown in FIG. 7, its timing, and the thermal head (15).
) is shown in Fig. 8.

effect According to the present invention, appropriate concentrations can be reproduced.

A uniform dot area can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an overall outline of a color thermal printer to which the method of the present invention is applied, and FIG. 2 is a block diagram showing the specific configuration of its data conversion section. Also,
Figure 3 shows the storing order of the 8-divided line buffer in the data converter, Figure 4 shows how dots are referenced on the actual print surface, and Figure 5 shows the ○dd dot data and even data.
FIG. 6 is an explanatory diagram showing the distribution of dot data, the address decoding method in the thermal conversion ROM, and the data decoding method in the pulse width conversion section. Further, FIG. 8 is a timing chart showing the decoding timing and the timing of energizing the thermal head.

Claims (1)

[Claims] Odd dots and even elements of the thermal head
In a thermal head driving method that generates heat alternately with dots, by referring to data a predetermined dot line before a pixel of interest, data after a predetermined dot line, and data next to a predetermined dot, two types of odd and even data are generated for the pixel of interest. 1. A method for driving a thermal head, comprising: generating two correction data, and driving the thermal head according to the data.