JPH0197667A - Method of driving thermal head - Google Patents

Abstract

PURPOSE:To provide a quality image having no division line by changing the positions of block division each color or each line during printing. CONSTITUTION:The division block of a thermal head is changed each line by control by data from a block selection ROM 7 when a strobe signal is delivered to a head driving circuit 4. This control is performed only by the on/off operation of a gate. That is, a counter 24 under timing control by a control section 5 keeps on incrementing the input address of the block selection ROM 7 to change the position of division by each line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a head driving method for a thermal transfer recording device that performs multicolor recording using a thermal head.

[Prior Art] Generally, the printing characteristics of thermal transfer recording devices (thermal printers) are easily affected by the head temperature, so conventionally the thermal head is divided into a plurality of blocks and driven in segments to prevent a sudden temperature rise.

The aim of this is that even when a large number of heat generating elements are used, by split driving, it can be used with a small capacity power supply.

[Problems to be Solved by the Invention] However, when such conventional divisional driving is performed, there is a problem in that a so-called division line, a portion of low print density, occurs at the boundary of each block. Ta. This is because the dividing boundary portion is always in contact with the end of the energized heating element, which causes a temperature drop due to heat radiation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for driving a thermal head that eliminates the problems of the conventional driving method, minimizes the above-mentioned drawbacks, and provides a high-quality image without dividing lines.

Means for Solving Problem E] In order to achieve the above object, the present invention divides the thermal head into a plurality of blocks and drives them separately, and performs multicolor recording by overprinting a plurality of times using ink sheets of a plurality of colors. The multicolor thermal transfer recording apparatus is characterized in that the blocks are transferred at different division positions for each color or for each line.

[Function] According to the present invention, the blocks are transferred at different division positions for each color or for each line.

Therefore, since the division boundary portion is not fixed at a specific position and always moves, the temperature does not drop only at the specific position.

Therefore, a high-quality image can be obtained without the occurrence of so-called dividing lines.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

1 and 2 are block diagrams of devices for carrying out the present invention, and in the figures, 1 indicates red (R), green (G).
, blue (B) another color image input terminal, 2 is a color conversion circuit, 3
1 is a halftone control circuit that controls the energy applied to the thermal head 8 to produce halftones of a color image, 4 is a head drive circuit, and 5 is a control unit that controls the entire thermal printer, and is composed of a microprocessor and the like. be done.

6 is a temperature compensation ROM that stores data for determining a predetermined gradation level corresponding to each color of the ink sheet and the temperature around the head; 7 is data for specifying a block to be driven by the thermal head; 8 is a thermal head, 9 is a temperature detection element for detecting head temperature, 10 is a color detection element for detecting the color of an ink sheet, 11 is an ink sheet, 12 is a receiving paper, 13 is a platen roller, 23, and gate, 24
is a counter for sequentially advancing the input address of the block selection ROM 7 (see FIG. 2).

FIG. 3 schematically shows a thermal head 8 and its drive circuit 4, which have been conventionally used and are also used in this embodiment.

In the figure, 14 is a heating resistance element, 15 is an AND gate between a strobe signal and a data signal, and 16 is a latch.
7 is a shift register for converting serial data into parallel data, 18 is a common electrode, 19 is a strobe signal input terminal for each block, 20 is a latch signal input terminal, 21 is a data signal input terminal, and 22 is a clock signal input terminal.

The operation will be explained below.

B, G, and R signals corresponding to yellow (Y), magenta (M), and cyan (C) prints are sequentially inputted from an image input terminal 1 from a color image memory (not shown). Then, in the color conversion circuit 2, Y, M, C
converted into a signal.

From the color conversion circuit 2, #J& data is transferred to the halftone control circuit 3 for each printing line, and 1
Data for several gradations is transferred to the data signal input terminal 21 of the head drive circuit 4 for each pixel. The amount of energy given to the head heating resistive element 14 is controlled according to the data in the temperature compensation ROM 6, and a corresponding strobe signal is transferred to the strobe signal input terminal 19 of the head drive circuit 4.

In this embodiment, in order to make the divided blocks of the thermal head different for each line, when the strobe signal is transferred to the head drive circuit 4, it is controlled by data from the block selection ROM 7. This control is performed by controlling only the on/off of the gate. In other words, as shown in FIG. 2, the counter 24 whose timing is controlled by the control section 5
The input address of the block selection ROM 7 is sequentially advanced, and the dividing position is switched line by line. In this embodiment, six blocks are divided into two, so there are three sets of output calculations in which the number of division positions is two or less as shown in FIG. :Kode6 (m Xi33
! The reason why it is u is that the blocks divided into 2/2υ are driven alternately. Therefore, the address must be specified twice while printing one line.

As a result, the same strobe signal is transferred from the halftone control section 3 twice, and the data signal is also transferred twice, so that data for one line is divided into two times and input to the heating resistor element 14 manually.

Thermal energy of the heating resistive element 14 sublimates or melts the sublimable ink or meltable ink applied to the ink sheet 11, and is received by the receiving paper 12 to form an image.

Also, the input address of block selection ROM7 is M
The starting address was changed for each of the three MC colors.

That is, when the first line of Y starts at address l, M starts at address 3 and C starts at address 5, so that the division positions of each line are different for the three colors.

As another embodiment of the present invention, the input address of the block selection ROM 7 is switched by the counter 24 whose timing is controlled by the control unit 5 in FIG.
The division 1 position is kept constant, and the upper 2 bits are sent to the control unit 5.
The division position may also be changed by specifying the color using .

That is, by this operation, the division position is changed for each color of MMC and the strobe signal is transferred to the head drive circuit 4. A predetermined heating resistor element 14 is heated by the logical sum of the strobe signal and the data signal, and this thermal energy sublimates or melts the sublimable ink or meltable ink applied to the ink sheet 11 and is received on the receiving paper 12. An image is formed.

[Effects of the Invention] As is clear from the above description, according to the present invention, by changing the dividing position of a multicolor thermal recording device that performs dividing drive for each line or for each color, high-quality printing without dividing lines can be achieved. An image is obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing an example of a thermal transfer recording device implementing the present invention, FIG. 2 is a block diagram showing a block selection circuit, FIG. 3 is a circuit diagram showing a thermal head and a head drive circuit, and FIG. 4 2 is a table diagram showing an example of the output of the block selection circuit. FIG. 1...Color image input terminal, 4...Head drive circuit, 7...Block selection ROM. 8... Thermal head, 10... Color detection element, 11... Ink sheet, 12... Receiving paper, 13... Platen roller, 14... Heating resistor element, 19... Strobe signal input end. This invention and the 3rd transcription recording arrangement which constitutes 70 blocks are shown in Fig.1. Table diagram No. 4
figure

Claims (1)

[Claims] In a multicolor thermal transfer recording device that divides the thermal head into multiple blocks and drives them separately, and performs multicolor recording by overlapping printing multiple times using multiple color ink sheets, the dividing position of the block is determined for each color or for each line. A method for driving a thermal head, characterized in that the thermal head is transferred in different ways.