JPS59179363A - Color thermal transfer recording method - Google Patents

Abstract

PURPOSE:To make full-color recording stably without lowering the applied electric power of tonal recording by using a thermal head having a heating resistor tray of an oblong slit form. CONSTITUTION:Heating resistors 6 are aligned at an one-row pitch P1 in the main scanning direction, and the width in the sub-scanning direction of the heating resistor is smaller than the pitch P1, or P2/4 for example. If the size of unit picture element for representing the tone is taken to be P1XP2, electric current is supplied to the heating resistor 6 and thermal transfer of solid ink is made from an ink sheet to an usual paper, whereupon a fine picture element of a slit form is formed by only one transfer. When the same operations are repeated while moving the usual paper at P2/4 pitch each, a multi-tonal picture element having varied transfer area ratios can be formed. The sending amount P/m in the sub-scanning direction and the width in the sub-scanning direction of the heating resistor of the thermal head to form fine picture elements are selected to given values in order to form unit picture elements having many tones.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color thermal transfer recording method used in a thermal transfer color printer or the like using a thermal head having a slit-shaped heating resistor.

FIG. 1 shows the basic configuration of conventional ink thermal transfer recording.

Here, (1) is a base film such as capacitor paper, (
2) is a solid ink layer consisting of a wax or organic resin binder and a coloring material, and the ink sheet (3) is made up of both. Ink sheet (3)
A thermal head (5) is disposed on the base paper (1) side, and a plain paper (4) and a rubber roller (7) are disposed on the entire solid ink layer (2) side.

Now, when the heating resistor (6) of the thermal head (5) is energized to generate heat, the solid ink layer (2) is heated and melted through the entire base paper (11) of the ink sheet (3), and the melted portion (2a) is Transferred onto plain paper (4). Heating resistor (
6) If either the applied power (W/dot) or the pulse width is changed, the amount of the solid ink layer (2a) to be melted and transferred changes in principle, and it appears that gradation recording is possible.

In Figure 2, the size of the heating resistor is 80 x 200 (μm) 2
The relationship between applied power and optical reflection density (01) during recording with a thermal head for high-speed facsimile is measured. The figure also shows the range of variation in data measured at 10 different locations.

Note that the heating current pulse width was 2 m5ec.

From the results shown in Figure 2, it can be seen that when medium density is recorded using a conventional ink sheet, the OD variation is extremely large. For this reason, ink sheets that perform melt transfer have the disadvantage that they cannot stably record gradation images that change the density of pixels.

The present invention was made to eliminate the above-mentioned drawbacks of the conventional method, and an object of the present invention is to provide a color thermal transfer recording method using a thermal head having an array of heating resistors in the form of elongated slits.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 8) In FIG. 0 showing an example of the structure of the heat generating resistor portion of the thermal head used in the present invention, (6) indicates the heat generating resistors which are arranged in a line in the main scanning direction at a pitch P1. In this example, the width of the heating resistor (6) in the sub-scanning direction is selected to be P2/4, which is smaller than the pitch P1.

P2 is the pitch in the sub-scanning direction of unit pixels expressing gradation. Generally, P1=1)2 is selected, and the heating resistor (6
) has a width of P27m (m>2). (8) is a common electrode, and (9) is an individual electrode for supplying current to each heating resistor (6).

FIG. 4 shows the basic principle of gradation recording for colorization according to the present invention. Assuming that the size of a unit pixel for expressing a gradation is P, Figure 4 (1
) A slit-shaped micropixel as shown in () is formed.

While reading and moving the plain paper by P2/4 pitch,
If you repeat the same action three times, three times, and four times, Figure 4 (2)
, (a), and (4), multi-gradation pixels with varying transfer area ratios can be formed. In this example, a total of 5 gradations including O are obtained, but the feed amount in the sub-scanning direction is P.
By selecting /m and the width in the sub-scanning direction of the heating resistor of the thermal head shown in FIG. 8 that forms the micropixel to predetermined values, it is possible to form a unit pixel having even more gradations.

By using the unit pixels with gradation formed as described above, the basic principle of conventional thermal transfer recording shown in FIG.
For each screen of yellow (Y), magenta (M), and cyan (q), it is possible to form a nearly full-color image with gradation by sequentially thermally transferring the 8-degree plane. With this method, Unlike the conventional method, there is no need to lower the recording power of the thermal head to record halftones, and the advantage is that the image quality obtained is uniform because it is always operated under high power conditions. Many variations in implementation are possible, including:

FIG. 5 shows an example in which a 1/4 tone pattern is recorded by changing the coordinates of minute pixels within a unit pixel. Here, (a) I
(b) shows a case in which all the small pixels of the ti-1 first scale appear at the same position, and (b) shows a case in which adjacent small pixels in the main scanning direction are shifted by PV/2 in the sub-scanning direction.

As in this example, in the method of the present invention having long sleeves in the main scanning direction, it is important to prevent the minute pixels from lining up in a line in the main scanning direction.

In order to further increase the number of gradations in an image, a pseudo gradation expression method such as a dither method or a density pattern method is also used. Now% Considering the case where MxN unit pixels are used as a new gradation expression unit, if the unit pixel has a density level of (m+1) values, it should have the gradation expression ability of (mXMXN+1) gradations. Can be done.

In addition, in the above embodiments, only the ink sheets coated with the eight primary colors of Y, M, and C were explained, but it is also possible to use ink sheets of four colors including black, as is conventionally done in printing etc. can be similarly applied.

It can also be used for gradation recording using a single color ink sheet. Furthermore, the number of gradations that can be obtained can be further increased by applying solid ink of a single color or a number of colors of the same tone with different density levels in advance and changing the density of the ink sheet used depending on the gradation level. can.

As described above in detail, the method of the present invention has the advantage that gradation recording can be performed without reducing the recording power, and full-color recording can be performed stably.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the basic configuration of conventional ink thermal transfer recording, Figure 2 is a graph showing the relationship between applied power and optical density in the conventional method, and Figure 8 is the heat generated by the thermal head used in this invention. FIG. 4 is an explanatory diagram showing an example of the structure of a resistor section, FIG. 4 is an explanatory diagram showing the basic principle of gradation recording for colorization according to the present invention, and FIG. FIG. (1) Base film, (2) Solid ink layer, (3) Ink sheet, (4) In paper,
(5+...Thermal head, (6)...Heating resistor, (7)...Rubber roller, (8)...Common electrode, (
9)...Individual electrode. In addition, the same reference numerals in the drawings indicate the between- and Osho parts, respectively. Agent Makoto Kuzuno - Fig. 3 1 Run ゑ direction Shunkin No. 41 (0) Nogane 4 77 ko Kuchi 2 ko [Z ko [2771 kuchi lko 口 = ko □ 4 koro 242 I2721 Mouth=

Claims (3)

[Claims] (1) A heating resistor row consisting of a plurality of heating resistors arranged on an insulating substrate is provided, and the shape of the central effective heating part of the heating resistor is ) direction perpendicular to the main scanning direction (sub-scanning direction)
Using a thermal head with a heating resistor width of 17'n (n > 2) or less, a solid ink M or a thermally transferable solid ink containing at least three primary colors of yellow, magenta, and magenta is applied surface-sequentially onto the base film. In a device that thermally transfers a color ink sheet coated with solid ink layers of a single color or multiple colors with different density levels onto a recording medium in time sequence, approximately ( Pl)x-・P2) minute pixels are thermally transferred, and the maximum (m+1) unit pixel of P1×P2 is expressed by the thermal transfer area of the solid ink layer.
Color thermal transfer recording method to have a density level of value (2) Coordinates in the sub-scanning direction at which micropixels in adjacent unit pixels in the main-scanning direction that express the same gradation appear are selected to be different. Color thermal transfer recording method. (3) The first aspect of the present invention is characterized in that NXM unit pixels are used as a unit for expressing all new intermediate tones, and have a gradation expressive power of a maximum of (mX n XM+1) gradations. The color thermal transfer recording method according to item 1 or 2.