JPS61102289A - Thermal transfer recording sheet and thermal transfer recording method using the same - Google Patents

Abstract

PURPOSE:To obtain higher image quality as compared with conventional images through using an improved thermal transfer recording sheet, by a method wherein matrices in which the size of dots and arrangement of dots are appropriately determined are provided side by side on a base sheet by using a dye ink, and a heat-fusible transparent wax ink layer is provided so as to cover the dye ink. CONSTITUTION:A film or the like is used as the base sheet 1, and an oil-soluble metal complex salt dye or a water-soluble basic dye is used for dye ink 2. The heat-fusible transparent wax ink layer 3 is formed by using carnauba wax. The matrices each of which comprises a set to dots of the dye ink 2 are provided side by side on the base sheet 1. The pitch is substantially equal to the dot size on a thermal head of a printer used for density gradation method, and is ordinarily 200-150upsilonm. In consideration of density adjustment through dissolution of the dye ink into the wax layer by impressed energy, the dot size is appropriately controlled in accordance with the total density of printed images to be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal transfer recording sheet and a thermal transfer recording method using the thermal transfer recording sheet.

Thermal transfer recording technology using a thermal transfer recording sheet has a simple mechanism, high reliability, and excellent maintainability, so it is widely applied to facsimile machines and low-end printers.

With the improvement of thermal head performance and the development of heat control technology for the head, it is widely used as a printer for word processors and office computers, and is also capable of color recording, so it is currently being used as the best choice for color CRT hard copy technology 44i. Development is progressing, and the main direction of development is the development of thermal recording technology to obtain high image quality.

[Object of the present invention]

In thermal transfer recording technology using a thermal transfer recording sheet, the factors that affect image quality include the individual characteristics of the thermal transfer recording sheet, the thermal head, the recording paper, etc., as well as their mutual characteristics, but the purpose of the present invention is primarily to improve them. The aim is to obtain higher image quality than before using a heat-sensitive transfer recording sheet.

[Prior art and its problems]

When using a conventional general thermal transfer recording sheet,
Recording is performed dot by dot, and each dot takes a binary value of "recorded" or "not recorded".

Due to the integral effect of the human eye, even with this 2(i! expression), the overall screen feels like a halftone. However, the size of these basic pixels, dots, is limited and cannot be fixed. Therefore, there are limits to the resolution or gradation characteristics of recorded images.

[Technical means to try to solve the problem]

The present inventor sought to create a thermal transfer recording sheet and a thermal transfer recording method that can further improve the characteristics of the conventional methods, and as a result of various research studies, the present invention was completed. It is.

That is, in the present invention, a matrix in which the size and arrangement of halftone dots are appropriately determined is formed with dye ink adjacent to each other in parallel on a base sheet, and a layer of heat-melting transparent wax ink is further applied to cover the dye ink. A heat-sensitive transfer recording sheet and a heat-sensitive transfer recording method using the same are provided.

The present invention will be explained in more detail below.

First, the thermal transfer sheet according to the present invention will be explained.

First, as the base sheet 1-1, paper, film, etc., which are normally used for heat-sensitive transfer recording sheets, are used. The dye ink 2 uses any one of a sublimable disperse dye, an oil-soluble metal complex dye, and a water-soluble basic dye. However, in consideration of the storage stability of the ink sheet and the fixability of transferred images, it is preferable to use oil-soluble metal complex dyes and water-soluble basic dyes. For the heat-melting transparent wax ink layer 3, carnauba wax, amide wax, etc. can be used, but carnauba wax is preferably used in consideration of melting of the dye. The dye ink 2 is formed in the form of halftone dots. The pitch of this halftone dot.

The size and the like are appropriately selected as described later.

A matrix consisting of a plurality of sets of halftone dots is formed adjacent to each other and in parallel on the base sheet 1.

First, the pitch is preferably approximately the same as the dot size of a thermal head of a printer used in the density gradation method. That is, the pitch is usually about 200 μm to 150 μm. It is not necessarily necessary to synchronize with the pitch of the dots, but special effects can be obtained if they are synchronized. In other words, it is possible to have a one-to-one correspondence between a matrix made up of a collection of dots and a matrix made up of halftone dots, so it is easy to refer to the dither matrix created by the conventional dither method when determining the size and arrangement of halftone dots, and the dither matrix It is also possible to functionally convert the size and arrangement of halftone dots.

The size of the halftone dots is appropriately adjusted depending on the overall density of the print screen to be obtained, taking into consideration density adjustment by dissolving the dye ink into the wax layer by applied energy.

That is, when statistically processed, the overall concentration is 70% ~ 9
It is preferable to set it to 0%, but it can also be lower than 10%.
If it is less than 0%, it may be more than that.

The structure of the matrix consisting of halftone dots is selected based on the effect of the print screen to be obtained. Here, an example of a halftone dot matrix will be explained with reference to a conventional dither matrix. The dither matrix shown in Figure 3 is
This is called a concentrated type, and the dots are easily concentrated, resulting in image quality with excellent gradation characteristics. The halftone dot matrix shown in FIG. 1 has a similar effect. Dye ink 2 is printed at each halftone dot position with a so-called halftone dot density of 70% to 100%. In another example, the dither matrix shown in FIG. 4 is of the so-called dispersion type, in which the dot area is easily dispersed and image quality with poor resolution can be obtained. The halftone dot matrix shown in Fig. 2 was aimed at achieving a similar effect, and as in the previous example, each halftone
It is printed using.

Of course, other examples than the above two examples can also be applied. A single matrix may be repeated, but it is also possible to repeat a certain type of submatrix by inverting, rotating, etc.
More than one type of matrix may be used repeatedly in an appropriate arrangement.

Formation of the above halftone dots can be realized by ordinary plate making and printing processes.

The heat-melting transparent wax ink layer 3 is preferably formed to cover the dye ink 2 with a thickness in the range of 1 μm to 5 μm. This is because if the heat-melting transparent wax ink layer 3 exceeds 5 μm, cohesive failure will occur during transfer and separation will occur between the layers, and if it becomes too thin, the dye ink will not dissolve sufficiently, resulting in a high concentration. This is because it becomes difficult to reproduce.

Next, a thermal transfer recording method using the thermal transfer recording sheet described above will be explained.

The thermal transfer recording sheet according to the present invention can be used in a printer equipped with a normal thermal head, and it distinguishes the regularly read image and prints dye ink according to the amount of energy applied according to the density of each of the seven trisols. The amount of dye ink dissolved into the transparent wax ink layer 3 is adjusted, and as a result, the size of the halftone dots of the dye ink is quantitatively adjusted in advance, resulting in density gradation method and area gradation method. Since gradation can be expressed by combining methods, originals can be reproduced more faithfully than in the past.

Note that even when the thermal transfer recording sheet according to the present invention is used only in the area gradation method, the same effect as when processed by the teaser method can be obtained. Alternatively, further effects can be expected from a processing method in which a dither matrix is interposed and printed after the read image is discriminated.

c Effects of the Present Invention Since the present invention is a heat-sensitive transfer recording sheet and a heat-sensitive transfer recording method as described above, it has the following effects. That is, the heat-sensitive transfer recording sheet according to the present invention provides a heat-melting transparent wax ink layer to cover dye ink, and adjusts the amount of dye ink dissolved in the heat-melting transparent wax ink layer by the amount of applied energy. The size of the dye ink dots can be adjusted. Therefore, it is possible to express gradations by combining the density gradation method and the area gradation method, so it is possible to improve the gradation characteristics of image quality and increase resolution by thermal transfer recording, which was previously insufficient. I can do it. Furthermore, by applying a so-called dithering method to the halftone dots forming the submatrix, it is possible to compensate for the characteristics lacking in the original dithering method, or to further emphasize the characteristics of the dithering method. Therefore, the present invention can be expected to be widely used in the future.

[Brief explanation of the drawing]

FIGS. 1 and 2 each schematically show an embodiment of a matrix consisting of halftone dots according to the present invention. Also, Figures 3 and 4
The figures each show a conventional dither matrix. Figure 5 shows
A cross-sectional view of a thermal transfer recording sheet is shown.

Claims (4)

[Claims] (1) On the base sheet, a matrix in which the size and arrangement of halftone dots are appropriately determined is formed with dye ink adjacent to each other in parallel, and then a heat-melting transparent wax ink layer is formed to cover this dye ink. A heat-sensitive transfer recording sheet characterized by: (2) The thermal transfer sheet according to claim (1), wherein the pitch of the halftone dots is approximately the same as the dot pitch of a thermal head of a printer. (3) On the base sheet, a matrix in which the size and arrangement of halftone dots are determined as appropriate is formed with dye ink adjacent to each other in parallel, and then a heat-melting transparent wax ink layer is formed to cover this dye ink. 1. A thermal transfer recording method, characterized in that thermal transfer recording is carried out by a density gradation method and an area gradation method using a heat-sensitive transfer recording sheet that has been prepared. (4) The thermal transfer recording method according to claim (3), characterized in that a thermal transfer sheet is used in which the pitch of halftone dots is approximately the same as the dot pitch of a thermal head of a printer.