JPS62171378A - Gradational recording method in thermal transfer - Google Patents

Abstract

PURPOSE:To perform gradational recording by using a conventional thermal head as it is by using couples of adjacent resistor elements and driving every other couple of resistor elements on the last line and current line. CONSTITUTION:Resistor elements 31-3n forming respective elements of a thermal head 1 are driven alternately. For example, one picture element is recorded with X of the last line and Y of the current line. Thus, every two couple of adjacent resistor elements are driven to record data. so that one picture element of an output image is recorded at two places obtained by dividing one picture element of an output image into four. Energy applied to resistor elements of a thermal head is easily controlled by modulating the force by a voltage or pulse width.

Description

Detailed Description of the Invention 3. Particular Description of the Invention (Technical Field of the Invention) This invention relates to a gradation recording method in a thermal converter using a thermal head.

(Technical Priority of the Invention and Its Problems) Thermal transfer recording has come to be used as the first stage of color hard copy, but it is difficult to record one stroke with one resistor element of the thermal head. In such cases, there is a drawback that it is difficult to produce density gradations in recorded images. Characteristics in Figure 1■
shows the characteristic of the recorded image IffD with respect to the applied energy J in such a case, and as is clear from this characteristic I, in thermal transfer recording using a conventional thermal head, gradation recording is performed on the output image. It was extremely difficult.

([Object 1] of the invention) This invention was made based on the circumstances mentioned above, and the purpose of this IJ1 is to use the conventional thermal head as it is and record fine gradation. It is an object of the present invention to provide a gradation recording method that achieves the desired gradation.

(Summary of the Invention) This invention relates to a gradation recording method in thermal transfer, in which two adjacent pairs of resistor elements f of a thermal head are used.
- When one pixel section of the l line is recorded by driving one of the resistor elements r-, the two resistor elements r The drive is switched to alternating and q so that 4J child areas can record one pixel.

(Embodiment of the invention) Figure 2 shows the method of this invention, in which the thermal head l
The resistive elements 31 to 3n forming each pixel are driven alternately, and the driving of the resistive elements 31 to 3n is performed by (A) showing the recording of the previous line and (B) showing the recording of the current line. The position is switched to copulation, and one pixel section of one line is recorded using two adjacent pairs of resistor elements 31 to 3n. For example, one pixel section is recorded between Make sure to record. That is, in FIG. 2, the shaded area represents the resistor 2 that is driven through current.
= 7-, and blank areas indicate resistor elements that are not driven. In (A) showing the recording of the previous line, the resistor element f31 is driven, and the adjacent resistor element -32
is not driven but indicates the recording of the primary current line (B
), the resistor element 7-31 is not driven and the resistor element T
32 is being driven.

In this way, by recording the driving of two pairs of adjacent resistor elements by alternating 1L and yJ, the results shown in Fig. 3(A) are obtained.
One pixel of the output image as shown is divided into 4 by the diagonal l-; 1
Recording can be done at two locations. Then, if the applied energy for thermal transfer is gradually increased, the same figure (
B), (C).

As shown in (D), the density area gradually increases, thereby making it possible to perform gradation recording of a thermal transfer recorded image. The characteristic n in FIG. 1 is the density of the output image with respect to the applied energy J in this case. Note that the energy applied to the resistor element of the thermal head can be easily controlled by modulating the voltage or pulse width.

FIG. 4 is a diagram showing a control system of a thermal head l that implements the method of the present invention, in which an n-bit shift register 4 and n drivers 5 are provided for n resistor elements 31 to 3n. The data i on the shift register 4 is transmitted in synchronization with the clock pulse GK, and is latched by the latch circuit in the driver 5 by the latch pulse LP. And the current flowing through the resistor element 7-3 is:

Dry/Turn on/in response to data launched at -5
It will be turned off.

FIG. 5 shows the details of the driver 5 for each pixel, and the bit output of the shift register 41 is sent to the latch circuit 51.
The output of the latch circuit 51 is input together with the strobe pulse LP to a NAND circuit 52, and the resistor element 31 is connected between the NAND circuit 52 and the power supply Vl+. Therefore, when the strobe pulse LP becomes "H", if the output of the latch circuit 51 is "H", the output of the NAND circuit 52 becomes "L", so the resistor element f- 31, the 'tun gas' flows and generates heat.

FIG. 6 shows a timing chart of one cycle, and its operation will be explained. The transfer numbers i=1 to 8 correspond to the C-degree slice levels i=1 to 8 in FIG. 4, and correspond to the pixel numbers of X=1 to n) and the resistor element numbers. There is. Then, when one transfer is completed and the data in the shift register 4 is latched into the latch circuit in the driver 5, the bit output of the latch circuit is sent only to the resistor element that is "H" as described in 1t1. , radio waves flow and generate heat. During this time, the next transfer is performed, and the radio wave is controlled again in response to the bit output by the first latch.For example, when be. On the other hand, when X=n-1, bits are output all eight times, so the pulse width is eight transfer times, and the heat generation amount increases accordingly. In this way, it is possible to control the current flowing through the resistor element T- with a pulse width corresponding to the C degree bell of one image. Note that 1 after each transfer time of each data i
In this case, the resistor elements -31 to 3n are driven as "L". Hereinafter, L corresponds to 4 elements r to 1 pixel, and 2. Although the method of using Ar for printing has been described, the input energy to the two elements f is not limited to being equal. Considering gradation, it is also possible to create a difference in size at a certain ratio.

Furthermore, it is possible to allocate two pieces of image information, one for each of the two elements that generate heat. In this case, the image data is a single point on the grid tilted at 45 degrees! -, and the output image is equivalent to the 45° s 14-point image 71) often used in printing.

(Effects of the Invention) As described above, according to the gradation recording method of the present invention, gradation recording can be performed using a conventional thermal head as is, and a head with crystal dot density is not required like dot matrix. There is an advantage to not doing so. In addition, there is no need to have a complicated pattern such as dither, and it is possible to
There is an advantage that gradation recording can be performed only by alternating νJ bit by bit.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between the energy applied to the thermal head and the density of the recorded image, Fig. 2 is a diagram for explaining the operating principle of the method of this invention, and Figs. 4 and 5 are circuit configuration diagrams showing an example of the position of a device that realizes this method, and FIG. 6 is a timing chart showing an example of its operation. It is. DESCRIPTION OF SYMBOLS 1... Thermal head, 31-3n... Resistor element, 4... Shift register, 5... Driver. Applicant's agent Yuzo Yasugata 1st (AI FB) (C) CD) Haya 3 Figure $ 4 Figure

Claims (1)

[Claims] Driving one of two adjacent pairs of resistor elements of the thermal head to record one pixel section of one line, and recording the one pixel section on the previous line and the current line. A gradation recording method in thermal transfer, characterized in that driving of each pair of resistor elements is alternately switched so that a four-element area corresponds to recording of one pixel.