JPS6163493A - Thermal transfer medium - Google Patents

Abstract

PURPOSE:To permit tonal display to be made by using a heat-meltable ink layer by a method in which a thermal transfer material is coated in spots or linearly on a substrate by making the size of the spot smaller than the size of the heating section of a thermal head and also by making the width of line smaller than the diameter or one side length of the heating section. CONSTITUTION:A thermal transfer material 2 is coated in spots or linearly on a substrate 1 by making the size of spot smaller than the size of the heating section of a thermal head and also by making the width of line smaller than the diameter or one side length of the heating section for forming a thermal transfer medium. A picture-receiving paper 3 is lapped on the coated face of the ink sheet and heated by the thermal head 4, whereupon ink 2 is transferred onto the paper 3 to form a thermal transfer medium 5 so transferred. In this case, when the temperature of the thermal head 4 is made higher and the pressing force is increased, the thermal transfer material (ink) transferred onto the paper 3 is flowed and the area of covering the paper by one spot is increased. The color tone of the portion can be more increased than the portion of transferred picture.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a thermal transfer medium, particularly a thermal transfer medium with excellent gradation, which can be used in video printers, personal computer terminal lines,
It is used in printers for electronic cameras.

(Thermal transfer media include a transfer sheet with a heat-melting ink layer on a support or a transfer sheet with a heat-sublimable dye layer on a support, which can be used to form an image on an image-receiving sheet by thermal printing. There are known ways to do this.

However, those using a heat-melting ink layer have excellent heat sensitivity and storage stability, but cannot express gradations, and those using heat-sublimable dyes have excellent gradation expression, but have poor heat sensitivity. There was a problem that the image quality was low and the storage stability of the image was poor.

Purpose This invention aims to provide a thermal transfer medium (thermal ink sheet) that uses a heat-melting ink layer and is capable of expressing gradation. has the following configuration. That is, in a thermal transfer medium used in a method of transferring an image to an image receiving member by melting a thermal transfer material coated on a base material by a heating member such as a thermal head heated according to image information, the thermal transfer material is It is applied dotted or linearly on the base material, and
The size of the dot is smaller than the size of the heat generating part of the thermal head, and the width of the line is smaller than the diameter or length of one side of the heat sensitive transfer medium.

An example of the structure of the present invention will be specifically described with reference to the drawings. FIG. 1 shows an example in which the heat-sensitive transfer material is applied in dots, and the heat-sensitive transfer material (ink) 2 is coated on one side of the support 1. It is a transfer medium (ink sheet) coated in dots.

When an image receiving paper 3 is placed on the coated surface of this ink sheet and a thermal head 4 is pressed from the back side of the ink sheet, the ink 2 is heated by the thermal head 4 from the back side of the support 1 and is pressed against the image receiving paper 3. is transferred to the image receiving paper 3 to form a transferred thermal transfer material 5. An image can be formed on the image receiving paper 3 by controlling the position at which the thermal head 4 is pressed using an image signal.

By the way, if the temperature or pressing force of the thermal head 4 is changed according to the gradation of the original image, for example, if the temperature of the thermal head is increased or the pressing force is increased in areas where the original image has a dark tone, the result will be as shown in Figure 2. The thermal transfer material (ink) transferred to the image receiving paper 3 flows and the area covered by one dot increases, so the color tone of this part becomes darker than that of the transferred image shown in FIG. In this way, the 11 degree gradation of the original image can be expressed by the energy or pressure input to the thermal head 4.

On the other hand, in the conventional ink sheet, as shown in FIG. 3, the thermal ink 7 is coated on the support 1 in a layered manner, so that the ink heated and transferred by the thermal head 4 is transferred to the image receiving paper 3.
Since the image is transferred in a solid layer, the transferred image is always drawn at maximum density, and cannot express the density gradation as when using the transfer medium of the present invention.

The characteristics of the heat-sensitive ink sheet of the present invention described above can be applied to full-color images using not only ordinary black coloring material but also many coloring materials. In addition, when a heat-sublimable dye is used as a heat-sensitive transfer material, a color developer is further applied to the surface of the image receiving paper 3, and a color developer is used on the ink sheet to create a transfer reaction type that develops color after transfer. It can also be applied to thermal transfer media used in transfer methods.

Hereinafter, the present invention will be specifically explained with reference to Examples. In addition, all amounts (parts) of each component during the implementation are parts by weight.

Examples The following composition was used as a raw material for a thermal transfer material.

Carbon black 15 parts Paraffin 20 parts Carnauba wax
65 parts A mixture having the above composition was kneaded using three rolls heated to 90°C, and carbon black was dispersed in carnauba wax to prepare an ink.

This ink is coated in a layer on the support 1 as shown in Figure 3, and the ink is applied in a layer through a heat-resistant screen to form dots of ink on a 15 μm square with a pitch of 15 μm as shown in Figure 1. I made a sheet.

The thermal head is a normal head (125μm/dot,
The relationship between the energy input to the thermal head (II+J) and the density of the image is shown in Figure 4, using a dot of 8 dots/ml). As shown in , the image density rapidly increases from a certain value of the energy input to the thermal head until it reaches the maximum density. As shown by the solid line 10, the density of the image gradually increases in accordance with the input energy of the thermal head, so it is possible to form a transferred image having the density gradation of the original image.

Even when using a transfer sheet with ink applied to the lines.
- It is possible to produce 1 q of transferred images with excellent density gradation as in the case of using a transfer sheet coated in a dotted manner.

Effects As explained above, by using the transfer medium of the present invention, a thermal transfer image with excellent gradation can be formed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the transfer process when transferring with the thermal transfer medium of the present invention, FIG. 2 is an explanatory diagram showing the gradation change of the transferred image when the heating energy of the thermal head is increased, and FIG. The figure is an explanatory diagram of the transfer process when transferring with a conventional thermal transfer medium, and Figure 4 shows the gradation of a transferred image when using a conventional thermal transfer medium and when using the thermal transfer medium of the present invention. Graph for comparison. 1... Support 2... Dotted thermal transfer material 3... Image receiving paper 4... Thermal head 5.6.8... Transferred thermal transfer material 7... Layered thermal transfer material 9. . . . Line 10 indicating the gradation of the transferred image by the conventional transfer medium . . . Line 10 indicating the gradation of the transferred image by the transfer medium of the present invention.

Claims (1)

[Claims] A method of transferring an image to an image receiving member by melting a thermal transfer material coated on a substrate by a heating member such as a thermal head heated in accordance with image information. In a thermal transfer medium, a thermal transfer material is applied on a base material in dots or lines, and the size of the dots is smaller than the size of the heat generating part of the thermal head, and the width of the line is the diameter of the heat generating part or A thermal transfer medium characterized by being smaller than the length of one side.