JPS62133857A - Thermal head driving system - Google Patents

Abstract

PURPOSE:To improve dot area of each level and density reproduction, to simplify the device and to make simple data processing possible by driving heat generating elements of the same level simultaneously dividing them for each level. CONSTITUTION:Sent image data for one line are portioned out every level 1-3 by a data portioning and zero detecting section 10 and stored in corresponding level buffer 111-113. At the same time, levels 1-3 are detected as '1', and level '0' is detected as '0' by a dot presence/absence detecting section 12 and stored in a buffer 13 and transferred to a front line buffer 14. The contents of buffers 111-113 are inputted to a shift register 16 of a comparator section 15, and those of a buffer 14 are inputted to a register 17, and the comparator section 15 makes weighting for each level by an encoder 18. Then, an impression pulse of width corresponding to the weight is prepared by a pulse width converting section 19 for each level and impressed to each heat generating element of a thermal head in order of levels 1-3.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a thermal head driving method for performing multi-stage modulation recording of dots in a thermal or thermal transfer recording device using a line type thermal head, and relates to a thermal head driving method for performing multi-step modulation recording of dots in a thermal or thermal transfer recording device using a line type thermal head. This can be applied to printers, faxes, copiers, etc.

BACKGROUND ART Conventionally, as a driving method for a line-type thermal head, as disclosed in Japanese Patent Application Laid-Open No. 57-34986, when the same heat generating element is continuously driven, There is a known method for making the printing density uniform by shortening the width of the applied pulse for this and also for the heating element adjacent to the heating element immediately after being driven, in order to make the printing density uniform. Not suitable for modulation.

In addition, the level data for the heat generating element that is currently being driven and the heat generating elements adjacent to it on both sides, as well as the level data of the previous line for these heat generating elements, are detected, and the density correction is weighted according to those level data. A method has also been proposed in which the printing density is automatically adjusted by controlling the application time or peak value of the electric power applied to the heating element according to the weight. However, in this method, not only the apparatus for implementing the method has a complicated configuration, but also the data processing is complicated.

Purpose An object of the present invention is to provide a thermal head driving method that can simplify the density control circuit and improve control characteristics (higher precision).

Structure In order to achieve this object, in the present invention, level data having a plurality of weights is distributed for each weight for one line, and two heating elements of the same level are simultaneously driven separately for each level.

Examples of the present invention will be described in detail below.

In the Honkaku1I11 method, one image data has four weights: level O, level 1, level 2, and level 3. Figure 1 is a block diagram of the electrical circuit that implements this. Image data for one line sent from the host machine is divided into levels 1, 2, and 3 by the data distribution and 0 detection unit (10). When it is distributed and there is level data for each level, rr 1 u,
If not, it is stored in the corresponding level buffer (11,), (11,), ml) as a binary code of II 07+. At the same time, if the dot presence/absence detection unit (12) is at level 1, level 2, or level 3, it is "1".
, if the level is 0, it is detected as "0", stored in the current line buffer (13), and then transferred to the previous line buffer (14) when data for the next line is input.

Figure 2 shows the weight of the input image data, the data distribution section (10), the level distribution mode, the weight of the image data one line before, and the dot presence/absence detection section regarding it. The relationship between detection modes in (12) is shown.

Each level buffer (11,)・(11,)・(11,)
The contents of are sequentially input to the shift 1 register (16) of the comparator (15), and at the same time, the contents of the previous line buffer (14) are also sequentially input to the register (17) of the comparator (15). For each level, the comparison section (15) refers to the binary code for the heating elements A-B adjacent to the heating element X and the dot presence/absence code of the dot data C one line before the heating element. Weighting is performed by an encoder (18).

Its weight is 11! ! The details are shown in the left column in the 3rd @. Thereafter, for each level, the pulse width converter (19) generates an application pulse with a width corresponding to the weight, and level 1. level 2,
The voltage is applied to each heating element of the thermal head in the order of level 3. The width of the applied pulse is set in four stages as shown in Figure 4 and 2.11.14, and the difference is Ta, T.
According to the reference times b, Tc, Td, (t, = T
a), (t, = Ta + Tb), (t, = Ta + Tb
+Tc), (t,,=Ta+Tb+Tc+Td
). This reference time differs depending on the level, and has a relationship as shown in FIG. 5, for example.

Fig. 6 shows the main flow of the above-mentioned operation, and Fig. 7 shows the main flow of the operation described above.
The flow of specific transcription operations at each level is shown.

As described above, according to the present invention, the heating element is
Since the same level is simultaneously driven separately for each level, the reproduction of the dot area and density of each level is improved.
Moreover, the apparatus can be simplified and data processing can also be simplified.

In addition, weighting is performed by referring to the dot presence/absence data of the previous line for the heat generating element and the level data of both adjacent heat generating elements, and the width of the pulse applied to the heat generating element is adjusted according to the weight. This allows you to obtain high-quality records with even density.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an electric circuit implementing the drive method of the present invention, Fig. 2 is a diagram explaining data processing aspects, and Fig. 3 shows weighting for controlling heat generating elements and corresponding applied pulse widths. 4 is a diagram explaining the width of the applied pulse, FIG. 5 is a diagram explaining that the application time of the heating element differs depending on the level, and FIG. 6 is a flowchart explaining the outline of the overall operation. FIG. 7 is a flowchart specifically explaining the transfer operation.

Claims (1)

[Claims] 1. In a thermal head driving method in which a heat generating element of a line type thermal head is driven according to level data having a plurality of weights, the level data is distributed for each line according to the weight, and the heat generating element is , a thermal head drive method that is characterized in that objects of the same level are simultaneously driven separately for each level. 2. Weighting is performed by referring to the dot presence/absence data of the previous line for the heating element and the level data of the current line for both adjacent heating elements, and the width of the pulse applied to the heating element is adjusted according to the weight. The thermal head driving method according to claim 1, wherein the thermal head driving method is adjusted.