JPS6137471A - Heat transfer ink sheet - Google Patents

Abstract

PURPOSE:To perform clear dot transfer without generation of chipping or missing print by making the moving direction length of a white or clear ink-applied portion an integer time the image-forming ink applied portion and the former's thickness equal to or larger than the latter's. CONSTITUTION:An ink layer 2 is provided on a sheet base 1 and each image- forming ink layer Y, M, C has a certain length (l). In the meantime, a white or clear ink layer W has an integer time the length lXN. A sensor mark 3 is provided in the boundary of each ink layer. A required plate surface (l) is repeatedly lapped and transferred according to the surface roughness of a paper to be transferred. The thickness of the layer W to be coated should be larger than those of the other color ink layers and the thickness and length of the layer W are properly combined. Thus the smoothing effect can be achieved by applying ink solidly even to paper having an extensive rough surface.

Description

[Detailed Description of the Invention] Technical Field This invention relates to various devices that utilize thermal transfer ink sheets,
For example, it is used in printers, copying machines, facsimile machines, and the like.

Prior Art In the conventional dot-type thermal transfer method using an ink sheet,
Due to the unevenness of the surface of the transfer paper, the dots cannot be accurately transferred, and the dots may be chipped or unhandled, which causes a reduction in the quality of the transferred image.

In order to solve these problems and improve the quality of transferred dots, the conventional methods were: 1) Increase the thickness of the ink layer applied to the ink sheet base.

2) Specially processed paper with a smooth surface is used as the transfer paper.

methods were used.

However, in method 1), the light transmittance of the ink deteriorates due to the increased thickness of the ink layer, and for example, in the case of a subtractive color mixing method in which colors are expressed by overlapping dots, saturation may decrease. is the problem. Also, method 2) uses special addition 1
The problem was that it was expensive because paper was used.

OBJECTIVE OF THE INVENTION It is an object of the present invention to provide a thermal transfer ink sheet that can perform clear dot transfer without causing chipping or handling of transfer dots even when using transfer paper whose surface is not particularly smooth. Aimed at - Structure The structure of the present invention to achieve the above object is to provide a J5 thermal transfer ink sheet used in a thermal transfer type color or monochrome printer, and white or transparent ink is used for image formation in the same sheet. This is a thermal transfer ink sheet in which the length of the white or transparent ink application area in the sheet movement direction is set to be an integral multiple of the ink spreading area for image formation. The thermal transfer ink sheet further has a thickness of the white or transparent ink layer that is equal to or larger than 17 of the image forming ink layer.

The operation will be explained with reference to Figure 3 of the attached drawings.
Taking the average surface roughness of the transfer paper on the horizontal axis and the dot area on the vertical axis, we can see that when transfer printing is performed on plain paper, commercially available coated paper, and plain paper coated with white solid paper to a thickness of 5 μm or more, respectively. The image is represented by the range indicated by points and lines P1, Q, and R, respectively.

From this result, it can be seen that the quality of the transferred dots (measured by the transfer area) improves as the paper surface becomes smoother.

The transparent or white ink used in this invention has the same composition as the image-forming ink, except for the pigment or colorant (eg, binder wax, oil, etc.). This invention uses these to fill in the unevenness of the paper surface, improve the smoothness of the transfer paper by the filling effect, and improve the contact probability of the dots to be transferred, thereby performing uniform dot transfer. I can do it. Furthermore, since the above-mentioned ink having approximately the same composition as the ink for the transfer dots is used as a filler,
In terms of both wetting and affinity, since the surface energy is dominant, the adhesive force is maximized, and reliable transfer is performed. Another effect is that by using white ink as a filler in color ink transfer, it is possible to set the white density using white ink, which would normally be the white density of the paper surface, and it is possible to widen the chromaticity range. Can be expanded.

In order to express colors using the subtractive color mixing method by overlapping three primary color inks, if the thickness of the three color inks is not carefully controlled as much as possible, the color will become desaturated due to the decrease in transparency due to the binder such as wax. . Usually polyester base.

The ink layer was coated on the material so that the thickness of the ink layer was 2.5 μm. Therefore, assuming that the thickness of the white or transparent ink layer for sealing is the same as the thickness of the color ink layer for image formation, one layer of white or transparent ink for sealing will be applied once on the surface of plain paper with an average surface roughness of 4 μm. It is not possible to completely fill in the unevenness with the application of . Therefore, the length of the white or transparent ink layer must be an integral multiple of the length p of the image forming ink.

The specific details of the ink sheet for thermal transfer according to the present invention will be explained with reference to the drawings. FIG. In the figure, the colors are arranged in the order of yellow (Y), magenta (M), cyan (C), and white or transparent (W) from the leading edge in the sheet travel direction. Each of the color ink layers Y, M, and C for image formation has a fixed length, whereas the white or transparent ink layer W has a length that is an integral multiple of that length. There is a sensor mark 3 on the border.

This ink sheet can be used to repeatedly transfer the required plate surface (λ) depending on the surface roughness of the transfer paper (usually m>) and set the coating thickness. For example, if the surface is 4μ
For paper with a roughness of 5 μm, the roughness may be struck twice, and for paper with a roughness of 5 μm, it may be struck three times.

FIG. 2 is a sectional view of a thermal transfer ink sheet in which a white or transparent ink layer W is applied thicker than other color ink layers. In this ink sheet, by appropriately combining the thickness and length of the W layer, it is possible to achieve a smoothing effect by solid coating even on paper having a wide range of surface roughness.

The above explanation uses a color ink sheet as an example, but it can also be used for monochrome sheets, line print method,
It can be used in any serial printing method.

Figure 4 shows the thermal transfer ink sheet of this invention.

FIG. 2 is a schematic diagram showing the configuration of a thermal transfer printer suitable for use, in which when an ink sheet SI to be supplied and a transfer paper S are overlapped on the surface of a platen 7, they are heated and transferred by a heat element 5 provided in a thermal head 4. Ru.

6 is a discrimination sensor.

Effects As explained above, by using the thermal transfer ink sheet of the present invention, it is possible to obtain a high-quality, clear-colored transferred image even when using paper with a low surface smoothness.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a specific example of the ink sheet for thermal transfer of the present invention, FIG. 2 is a sectional view showing the relationship between the thickness of the ink layer of another specific example of the ink sheet, and FIG. FIG. 4 is a graph showing the relationship between paper surface grain and dot area variation in a copied image. FIG. 4 is a schematic side view showing an example of the configuration of a thermal transfer printer using the ink sheet of the present invention. DESCRIPTION OF SYMBOLS 1... Sheet base, 2... Ink layer, 3... Color determination sensor mark, Y... Yellow ink layer, M... Magenta ink layer, C... Cyan ink layer, Bu...・Length of image forming ink layer, W...White or transparent ink layer, ℃...Thickness of image forming ink layer, T...Thickness of white or transparent ink layer, P...・Dot area range of plain paper, Q...Dot area range of commercially available coated paper, R...Dot area range of 5 μm solid white paper on plain paper, SI...supply ink sheet, S...covering Transfer paper, 4.
...Thermal head, 5...Heat element, 6...Discrimination sensor, C
...Nof 7' 70 Patent applicant Rico Co., Ltd. - Agent Patent attorney Hide Komatsu Agent Patent attorney Kosai Asahi Figure 1

Claims (2)

[Claims] (1) In thermal transfer ink sheets used in thermal transfer type color or monochrome printers, white or transparent ink is regularly and repeatedly applied on the same sheet together with image forming ink, and this white or transparent ink An ink sheet for thermal transfer, characterized in that the length of the application section in the sheet movement direction is set to an integral multiple of the length of the image forming ink application section. (2) The ink sheet for thermal transfer according to claim (1), wherein the thickness of the ink layer in the white or transparent ink application area is equal to or greater than the thickness of the image forming ink layer.