JPH06143770A - Thermal transfer recording method - Google Patents

Abstract

PURPOSE:To raise a transmission density on transparent image-receiving paper by a method wherein an ink film is formed by applying ink of the same color and a plurality of types in a face sequential manner, the ink differ in dye migration to an accepting layer or affinity for the accepting layer, the ink film is sequentially heated on the same image signal and an image is overlappedly recorded two or more times. CONSTITUTION:A required ink film 1 is formed by alternately applying sublimable dye ink layers 3, 4 on a base film 2 made of a PET or the like through introduction parts 5 in a face sequential manner. At this time, the ink layers 3, 4 are made of two types of dyes having different properties and the same color. The color of the ink is, for example, just a black. The black ink of two types differ in dye migration from the ink layers to an accepting layer. The first black ink 3 has a superior migration. The second black ink 4 has a standard migration. In an image recording, the ink film is sequentially heated on the same image signal, whereby an image is overlappedly recorded two or more times. In this manner, a transmission density is enhanced esp. on transparent image-receiving paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sublimation dye thermal transfer recording system for hard copying an input image from a video device or a computer.

[0002]

2. Description of the Related Art A thermal transfer recording system for recording an image by heating an ink film coated with a sublimation dye with a thermal head can achieve both high gradation and high resolution, and a high quality hard copy comparable to a photograph can be obtained. As a method, it is adopted in video printers and the like. Further, the application of this recording method to a printer that records the output from a computer or various image devices is being advanced.
There is also an increasing demand for image recording on a transparent image receiving paper by this method for HP or medical use such as X-ray photography.

In image recording using a transparent image receiving paper,
Similar to slide film, transmitted light transmittance (transmission density)
Image information is expressed by. However, in the conventional sublimation dye thermal transfer recording method, the transmission density cannot be increased because the dye dyeing amount on the transparent image receiving paper is insufficient, and the color when viewed with transmitted light is thin, and sufficient information and effect can be obtained. There is a problem that you can not.

As a method for increasing the transmission density on a transparent image receiving paper, conventionally, a plurality of surfaces of the same color of an ink film coated with a dye in a surface sequential manner are used to heat a plurality of times with the same image signal and record them in layers. The method of increasing the dyeing amount of the dye by doing so is used. However, the conventional dye has a slow migration and diffusion speed of the dye to the receiving layer, and the transparent image-receiving paper has a small cushioning property. There was a tendency that a non-colored portion or a low-density portion was easily formed between the dot and the dot. Further, since the dye is dyed only in a shallow area on the surface of the receiving layer, the dyeing density of the receiving layer becomes insufficient, and there is a drawback that the expected increase in transmission density cannot be obtained even when recording is repeated. Further, since the affinity between the dye and the receiving layer is limited, the dye on the surface of the receiving layer is saturated and it is difficult to increase the concentration above a certain value.

In order to increase the transmission density of the transparent image receiving paper, it is necessary to sublimate and dye a sufficient amount of the dye, diffuse it inside the receiving layer, and print at a high density so that the recording dots overlap. . For that purpose, it is necessary to reduce the recording pitch and transfer new ink over and over again, but it is inevitable that the printing time becomes long.
Further, the dye transfer rate is fast, that is, if a highly sensitive dye is used, the dyeing efficiency is increased and the heating time can be shortened, but the stability of the dye against temperature and light deteriorates, and the storability of recorded images deteriorates. Cheap.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a means for obtaining a high density in a sublimation thermal transfer system, especially a means for increasing the transmission density of a transparent image receiving paper.

[0007]

According to the recording method of the present invention, ink films coated with a plurality of dyes of the same color having different dye transferability to the receiving layer or affinity with the receiving layer are applied in the same manner. The image is sequentially heated by the image signal, and the image is recorded a plurality of times.

[0008]

In this method, since a plurality of dyes having different dyeing, diffusion speed or dyeing equilibrium state to the receiving layer are used, the dyeing range and the dyeing amount of the dye can be increased. The transmission density can be increased as compared with the conventional method in which the dyes are transferred in layers.

[0009]

Embodiments of the present invention will be described below with reference to FIGS.

1A and 1B are views showing an ink film used in the sublimation heat transfer system of the present invention. FIG. 1A is a plan view and FIG. 1B is a sectional view.

In FIG. 1, an ink film 1 is formed by coating sublimation dye ink layers 3 and 4 having a thickness of about 1 μm on a base film 2 made of PET having a thickness of about 5 μm, for example. Here, the ink layers 3 and 4 have different properties 2
The same type of dye is used, and the color of the ink is, for example, all black. Reference numeral 3 is a first black ink layer, and 4 is a second black ink layer, and the respective inks are alternately applied in a frame order. Reference numeral 5 denotes an introduction portion, which is provided on the boundary of each ink and is not coated with ink, and is used for the purpose of detecting the head of each ink. The introduction part 5 does not necessarily have to be provided. The two types of black inks have different migrating properties of the dye from the ink layer to the receiving layer. The first black ink 3 is an ink having excellent migrating property, and the second black dye ink 4 is a standard. It is an ink that has excellent transferability. Here, the dye transferability refers to an ink having a high speed of dyeing and diffusion on an image receiving paper by heating, that is, a high sensitivity.

FIG. 2 is a side view showing a sublimation thermal transfer printing method of the present invention using the ink film shown in FIG. In the following figures, the same components are designated by the same reference numerals.

In FIG. 2, 6 is an ink film supply reel around which the ink film 1 is wound, and 7 is the same take-up reel. At the time of printing, the ink film 1 is synchronized with the rotation of the platen 8 at the same speed as the image receiving paper 9 at the same speed. It is transported in the indicated direction. The image receiving paper 9 comprises a transparent base material 10 and a transparent receiving layer 11 provided on the surface thereof. In the sublimation thermal transfer recording method of the present invention, first, the first black ink layer 3 on the ink film 1 is brought into close contact with the image receiving paper 9, and the heating element 13 of the thermal head 12 is pressed to heat the dye to receive the dye image. Transfer to paper. The transfer amount of the dye is controlled by causing each heating element 13 of the thermal head 12 to generate heat for a time corresponding to the image signal. First black ink layer 3
When the transfer is completed, the ink film 1 and the image receiving paper 9 are once peeled off, and the ink film 1 is sent to the start portion of the second black ink layer 4 through the introduction portion 5, while the image receiving paper 9 is returned to the recording start position again and again. The ink film 1 and the image receiving paper 9 are brought into close contact with each other. Subsequently, the second black ink layer 4 is heated by the same image signal, and recording is performed by superimposing it on the image receiving paper recorded with the first black ink.

Next, the dyeing and diffusing state of the dye on the image receiving paper by the thermal transfer recording system of the present invention using the ink film shown in FIG. 1 will be described in comparison with the conventional system.

FIG. 3 shows the dyeing state of the dye ink on the receiving layer 11 on the image receiving paper 9 in the double-layer transfer according to the conventional method. The dye 14 is applied to the portion corresponding to the heating element of the thermal head. The state in which the recording dots 15 are formed by dyeing is shown in an enlarged manner. Since the transfer and diffusion speed of the dye is slow, transfer occurs only in the part corresponding to the high temperature part (central part) of the heating element, and there is a low density part 16 in which the dye is hardly dyed between the dots, and Diffusion of the dye in the depth direction of the layer 11 is small. The amount of dye adhering and the diffusion into the receiving layer can be increased to some extent by reducing the recording pitch so that the dots overlap and heating for a longer time to transfer a new dye, but the printing time increases. Is inevitable.

FIG. 4 shows an example of the dyeing state of the image-receiving paper receiving layer by the thermal transfer recording system of the present invention using two kinds of dye inks having different dye transferability to the receiving layer, that is, dyeing and diffusion rates. FIG. FIG. 4A shows a state in which the first black ink is transferred, and FIG. 4B shows a state in which the second black ink is superposed and transferred thereon. First black ink 1
7 (indicated by a white circle) is a highly sensitive dye having good transferability to the receiving layer 11, and therefore transfer occurs not only in the central portion of the heating element of the thermal head but also in almost the entire element, so that the dyeing area is large. Therefore, there is no low-density portion between the dots, and the dots are connected to each other. A second black ink 18 (indicated by a black circle) having a standard migration property is transferred onto this by heating to dye the second ink 18 on the surface of the receiving layer 11, and the first ink is heated by heating. 17 is diffused inside the receiving layer. Generally, a dye having a high transferability to the receptive layer and a high sensitivity has poor storage stability, but when a dye having a high sensitivity is used as the first ink, an annealing effect is caused by heating during transfer of the second ink. Is obtained, and there is an advantage that stability is increased. On the other hand, the second ink 18 is the first ink 17
Compared with, the dyeing area is smaller, but the stability is good, and the dyeing density is increased in the dyeing part where two layers overlap. Due to the properties of these two types of ink, the dyeing density in the area direction as well as the depth direction of the receiving layer increases, and the transmission density can be increased without deteriorating the storage stability.

FIG. 5 is a plan view showing another embodiment of the ink film used in the sublimation heat transfer method of the present invention. Figure 5
In, the configuration of the ink film 19 is the same as that of the ink film 1 shown in FIG.
A sublimation dye ink layer 20, 21 having a thickness of about 1 micron is applied on a base film made of T. Here, the ink layers 20 and 21 are two kinds of dyes of the same color having different properties, and the color of the ink is, for example, only black. 20
Is a first black ink layer, and 21 is a second black ink layer, and the respective inks are alternately applied in a face-sequential manner. Reference numeral 22 is an introduction portion provided on the boundary of each ink and not coated with ink. The introduction part 22 does not necessarily have to be provided. First black ink 20 and second black ink 21
Are dyes having different affinities with the receiving layer. Here, the dyes having different affinities mean that the physicochemical equilibrium state between the dye and the receiving layer, that is, the saturation state is different.

Using the ink film coated with the two types of dye ink shown in FIG. 5, double transfer is performed in the same manner as shown in FIG.

FIG. 6 is a diagram showing an example of a dyeing state on the image receiving paper receiving layer by the thermal transfer recording system of the present invention using the two kinds of dye inks shown in FIG. FIG. 6A shows a state in which the first black ink 20 is transferred, and FIG. 6B shows a state in which the second black ink 21 is transferred and superposed thereon.
Reference numerals 3 (indicated by white circles) and 24 (indicated by black circles) represent the transferred first and second dye inks, respectively. Since the first ink 23 and the second ink 24 have different physicochemical equilibrium states with the receiving layer, even if the receiving layer is dyed by the first ink to a state close to saturation, the second ink is further Can be dyed into it, so that the dye density in the receiving layer can be increased and the transmission density can be increased. According to this method, it is possible to improve the drawback that the surface of the receiving layer becomes almost saturated and the transmission density does not rise above a certain level in the conventional two-time overlapping transfer with the same ink.

In the above-mentioned two embodiments, the former method is shown to increase the dyeing range of the dye and the latter method is to increase the dye density to increase the transmission density. Can be used to obtain a greater effect. The ink types are not limited to two types as long as the printing time is allowed.

In the above embodiment, the color of the dye ink has been described as a single black color, but the recording system of the present invention has three colors or four colors.
It can also be applied to full-color printing using color inks. An example thereof is shown in FIGS.

FIG. 7 is a plan view showing an embodiment of an ink film for full color printing according to the present invention. In the ink film 25 shown in FIG. 7, yellow 1 (Y1) and magenta 1 (M
1) and three colors of cyan 1 (C1) are yellow 2 (Y2) and magenta 2 shown as 27 as the second ink.
An ink film is used in which three color inks (M2) and cyan 2 (C2) are applied in a frame sequential manner. First ink 26
And the second ink 27 have different dye transferability to the receiving layer or affinity with the receiving layer. By transferring three colors of the second ink 27 again onto the image receiving paper on which the three colors of the first ink 26 have been transferred by the image signal of each color, a high density full color print can be obtained. It should be noted that, as shown in FIG. 8, the first and second inks are arranged such that inks of the same color are adjacent to each other, and image data corresponding to each color is printed on two sides of each ink.
Color transfer may be performed.

FIG. 9 is a plan view showing another embodiment of the ink film for full color printing according to the present invention. In the ink film 28 shown in FIG. 9, yellow 1 (Y1) and magenta 1 (M
1), cyan 1 (C1), and black 1 (K1), four colors of ink are yellow 2 shown as 30 as the second ink.
An ink film is used in which four color inks (Y2), magenta 2 (M2), cyan 2 (C2), and black 2 (K2) are applied in sequence. The first ink 29 and the second ink 30 have different dye transferability to the receiving layer or affinity with the receiving layer. By transferring the four colors of the second ink 30 again onto the image receiving paper on which the four colors of the first ink 29 have been transferred by the image signal of each color, it is possible to increase the density of black, especially in a print with characters, and to increase the density You can get a full color print. As the first and second inks, inks of the same color may be arranged adjacent to each other as shown in FIG. 10, and four colors of two surfaces may be transferred by image signals corresponding to the respective colors.

The recording method of the present invention is particularly effective for increasing the transmission density on transparent image receiving paper, but it can also be applied for the purpose of increasing the reflection density on ordinary non-transparent image receiving paper.

[0025]

As described above, according to the present invention, the ink film coated with plural kinds of dyes having different dyeing, diffusion speed or dyeing equilibrium state to the receiving layer is transferred.
As a result, the dyeing range and dyeing amount of the dye on the image receiving paper can be increased compared to the conventional method in which the same type of dye is transferred and transferred, and the transmission density can be increased without sacrificing the printing time and storage stability. Can be higher.

[Brief description of drawings]

FIG. 1 is a diagram showing an ink film used in a sublimation thermal transfer system of the present invention.

FIG. 2 is a side view showing a sublimation thermal transfer printing method of the present invention using the ink film shown in FIG.

FIG. 3 is a diagram showing a dyeing state of a dye ink on a receiving layer on an image receiving paper according to a conventional method.

FIG. 4 is a diagram showing an example of a dyed state of an image receiving paper receiving layer according to the thermal transfer recording system of the present invention.

FIG. 5 is a plan view showing another embodiment of the ink film used in the sublimation thermal transfer system of the present invention.

6 is a diagram showing an example of a dyeing state on an image receiving paper receiving layer by the thermal transfer recording system of the present invention using the ink film shown in FIG.

FIG. 7 is a plan view showing an example of an ink film for full-color printing according to the present invention.

FIG. 8 is a plan view showing another embodiment of the ink film for full-color printing according to the present invention.

FIG. 9 is a plan view showing another embodiment of the present invention.

FIG. 10 is a plan view showing another embodiment of the present invention.

[Explanation of symbols]

 1, 19, 25, 28 ... Ink film, 3, 20, 26, 29 ... First ink layer, 4, 21, 27, 30 ... Second ink layer, 9 ... Image receiving paper, 11 ... Receiving layer.

Claims (2)

[Claims] 1. A thermal transfer recording system in which an ink film coated with a sublimation dye is heated by a thermal head so that the dye is dyed on a receiving layer provided on an image receiving paper to record an image. A thermal transfer recording method characterized in that an ink film coated with a plurality of dyes of the same color having different affinities with layers in a face-sequential manner is sequentially heated by the same image signal and an image is recorded by superimposing a plurality of times. 2. An ink film for thermal transfer recording characterized in that a plurality of dyes of the same color having different dye transferability to a receiving layer or affinity with the receiving layer provided on an image receiving paper are applied in a frame-sequential manner. .