JPH03136873A - Thermal head and electronic equipment - Google Patents

Abstract

PURPOSE:To obtain a thermal head capable of giving high print quality even on rough paper by forming a tapered surface toward the tip of a substrate only on either of the front or the rear of the end of the substrate. CONSTITUTION:A substrate Ji consisting mainly of alumina has a flat surface on the 11A side and a tapered surface 11C on the 11B side so that the plate thickness including the 11A decreases at the end. In addition, the 11B has a curve so that the radius of a curvature at the tip is 0.1 to 0.5mm. A glass glazed layer 12 is formed from the end to the 11A side of the lateral face where no processing has been performed. When a thermal element 13 is provided on the glass glaze on the lateral face, and an electrode film 14 is laid on both ends of the thermal element 13 with a protecting film 15 formed on the film 14. Consequently, the contact area of a head with paper reduces significantly and at the same time, a pressing force increases remarkably. Therefore, if an image is printed on a rough paper using a thermal transfer technique, molten transfer ink can be caused to permeate deep into the voids of paper fiber. Thus sharp print can be obtained even on a rough paper as can be done on a plain paper.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal head useful in thermal transfer recording systems.

Conventional heat-sensitive recording methods are easy to maintain, produce low-noise images, and produce high-quality images, so they are used as print recording units in many electronic devices such as facsimile machines, word processors, and printers for personal computers. In addition, the development of edge-type thermal heads has made it possible to save space and realize compact printers, and the degree of freedom in printing has increased, making it possible to print on items other than the paper area.

An example of the conventional thermal head mentioned above will be described below with reference to the drawings. FIG. 2 shows a cross-sectional structural diagram of a conventional end-face type thermal head (Japanese Patent Laid-open No. 6
0-19558).

In FIG. 2, 21 is a substrate mainly composed of alumina;
22 is a glass glaze layer, 23 is a heating element film, 24 is an electrode film, and 26 is a protective film.

The operation of the thermal head configured as described above will be explained below. In Fig. 2, the heat generating part is
It is constructed on a substrate 21 on which a glass glaze layer 22 is formed. Printing is performed by applying a printing pulse to the heating element film 23 to generate heat and simultaneously moving the transfer paper and the ink ribbon.

Problems to be Solved by the Invention In conventional edge-type thermal heads, the thickness of the substrate 1 is approximately 2 mm thick in order to prevent warping, etc. The radius of curvature of the section was approximately 11 II m. Therefore, compared to a flat thermal head, the contact area of the head with the paper is smaller, so the pressing pressure is increased accordingly, and the quality of printing on rough paper is improved. However, even in this case, the print quality was still not sufficient when compared to the case where ordinary paper was used.

The present invention is intended to solve the above problems, and aims to provide a thermal head that can obtain high printing quality even on rough paper while maintaining the strength of the substrate.

Means for Solving the Problems To achieve this object, the thermal head of the present invention has the following features:
A tapered surface is formed only on either the front side or the back side of the edge of the board so that the thickness between the front and back sides of the board gradually becomes thinner toward the tip of the board (hereinafter referred to as this step). It has a configuration in which a glass glaze layer is provided on the tip, a heat generating portion is provided on the glass glaze layer, and a protective film is provided on the heat generating portion.

Effect: With this configuration, the radius of curvature of the end face is small.
The contact area of the thermal head with the paper becomes smaller, and at the same time the pressing pressure increases.

As a result, it is possible to print on rough paper as sharply as on regular paper. In addition, the thickness of the board other than the part where the chamfering is done can be the same as that of the conventional edge-type thermal head, so there is almost no problem in terms of strength such as warping. can be used.

Embodiments Embodiment 1 Hereinafter, a thermal head according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional structural diagram of a thermal head in an embodiment of the present invention. In Figure 1, 11 is a substrate whose main component is alumina, the 11A side is left flat, and the 11B side has a 1.
Tapered surface 11C where the plate thickness with 1A gradually becomes thinner
The radius of curvature at the tip is 0.1~
0.5. The curved surface has been processed so that it becomes .

Reference numeral 12 denotes a glass glaze layer, which is formed on the 11A side of the side surface that is not processed from the end face portion. A heating element 13 was provided on the glass glaze corresponding to this end face portion, electrode films 14 were provided on both sides of the heating element 13, and a protective film 15 was provided on these.

Glass glaze layer 12 of the thermal head; heating element film 13. Electrode film 14. The protective film 15 can be formed in exactly the same way as the conventional head. In order to reduce the radius of curvature of the tip, it can be formed by polishing both the 11A side and 11B side of the substrate 11, but as in this example, one side (11A side) is left as it is on a straight line. This is due to the following reasons. In other words, since the tapered surface is formed only on one side (the 11B side), it is easier to work with than forming it on both sides.The electrode pattern is easy to form because it is flat near the tip, and the side surface is sharp relative to the tip. This is because it is advantageous for peeling off the ink ribbon because it stands up.

Differences in printing characteristics will be explained using the thermal head configured as described above (FIG. 1) and the conventional head (FIG. 2). In the conventional head, the substrate thickness is approximately 211I.
! 11, so the radius of curvature of the tip is 11111
It will be about 1. On the other hand, in the thermal head of this embodiment, even if the substrate thickness is 2-2, by chamfering, the radius of curvature of the tip can be set to 0.1 to 0.611II11. For this reason, the contact area of the head with the paper is significantly reduced compared to the conventional one, and inversely proportional to this, the pressing pressure is significantly increased. As a result, when printing on rough paper using the thermal transfer method, the head of this method can push the molten transfer ink deep into the gaps between the fibers of the paper, making it possible to print as clearly as on regular paper. It can be carried out. In addition, because this head has a small radius of curvature at the tip, the heating element protrudes from the paper more than the conventional one, and the pressing contributes to increasing the pressure. Adhesion to paper is improved and heat conduction efficiency is improved.

As described above, according to this embodiment, the edge of the board is chamfered diagonally from one side, and the radius of curvature of the end face is set to 0.1 to 0.5.
-, and by forming a heat generating part in this part, it is possible to obtain a thermal head that can print clearly even on rough paper.

Furthermore, by forming the curvature radius of the tip of the thermal head of this method to be small and smooth, the glaze m12 at the lower part of the heating element can be formed thin and uniformly. This improves heat dissipation, and therefore it is possible to realize a thermal hat that can be driven at high speed while being compatible with rough paper.

For comparison, a planar head compatible with rough paper is shown in FIG. After forming the glass glaze 32B on the substrate 31 and further forming the partial glaze 32A on this, the heating element film 33. Electrode film 34. It has a structure in which a protective film 36 is formed. By raising the glaze layer of the heat generating part in two stages in this way, the pressure of the heat generating part being pressed against the paper is increased.

However, this method has the problem that the glaze thickness is larger than necessary, which reduces heat dissipation and deteriorates thermal response characteristics, making high-speed driving difficult.

In this method, 1. The tip of the thermal head as claimed in the claims is formed smoothly, and the glaze layer is formed thinly (about 10 to 2 offim) using low viscosity glass. This enables high-quality printing and high-speed drive.

Example 2 In thermal transfer printing, print quality can be improved by making the length of the heating element longer than the length of the part where the head and ink ribbon are in contact with the head of this system.

FIG. 5 shows the printing state (ink transfer process) when using the thermal head of this method.

In FIG. 5, 61 is transfer paper, 62 is ink, 53 is an ink ribbon base film (52, !: 53 are collectively referred to as ink ribbon), 64 is a heat generating part of a head, 5
6 is a non-heat generating part. When using this type of thermal head, since the radius of curvature of the tip is small, the heat generating section 64 can be formed to extend from the tip of the substrate to near the front and back surfaces without changing the length of the heating element much. Therefore, the length of the heat generating portion can be made longer than the length of the portion where the ink ribbon and the head are in contact. Therefore, it is possible to easily realize a configuration in which the transfer paper 61 and the ink ribbon are peeled off while the ink ribbon is in contact with the heat generating portion 54 and the ink 62 is melted. In thermal transfer printing, when the ink ribbon and transfer paper are peeled off,
Ink transfer is better when the ink is molten. Therefore, by using the head of this system, the transfer paper and the ink ribbon are peeled off during heating, and no ink remains on the base film, so that good printing quality can be obtained.

For comparison, the printing state when a conventional head is used will be explained using FIG. In FIG. 4, 41 is a transfer paper, 42 is an ink, 43 is a base film of an ink ribbon, 44 is a heat generating part of a head, and 46 is a non-heat generating part. Since the radius of curvature of the tip of this conventional ink ribbon is large, the ink ribbon comes into contact with the heat generating part 44 and the ink 42 is melted, and then comes into contact with the non-heat generating part 46 and the ink is cooled and solidified again. Therefore, by the time the transfer paper 41 and the ink ribbon are peeled off, the ink has already solidified, so some of the ink may remain on the base film 43, resulting in deterioration of print quality. In order to prevent this, the length of the heating element may be increased to allow the transfer paper and ink ribbon to be peeled off during heating. However, in the conventional head, since the radius of curvature of the end face portion is large, in order to adopt this configuration, the length of the heating element must be made much larger than its optimum value, which is practically impossible. Another possible method for improving this is to reduce the ζ peeling angle, but this is not a very desirable method since it imposes a large restriction on the arrangement of the ink ribbon.

Therefore, as described above, by configuring the heat generating part of the claimed thermal head to extend from the tip to near the front and back sides, it is possible to create an ink base film that is difficult to achieve with conventional heads. It is possible to easily prevent deterioration of print quality due to re-adhesion to the surface.

Effects of the Invention As described above, the present invention provides a method in which the thickness between the front and back surfaces of the substrate gradually becomes thinner only on either the front side or the back side of the end portion of the substrate toward the tip side of the substrate. By forming such a tapered surface, it is possible to realize an excellent thermal head that can print on rough paper as clearly as on regular paper.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a thermal head according to an embodiment of the present invention, FIGS. 2 and 3 are sectional views of a conventional thermal head, and FIG. 4 is an ink transfer mechanism when using a conventional head. FIG. 6 is a block diagram of an ink transfer mechanism when the thermal head of the present invention is used. 11...Substrate, 11C...One surface of Teno, 12...Glass glaze layer, 13...
... Heating element, 14... Electrode film, 16...
··Protective film.

Claims (3)

[Claims] (1) A tapered surface is formed only on either the front side or the back side of the edge of the board so that the thickness between the front and back sides of the board gradually becomes thinner toward the tip of the board. , a thermal head in which a glass glaze layer is provided on the tip, a heating element is provided on the glass glaze layer, and a protective film is provided on the heating element. (2) An electronic device according to claim 1, which uses a thermal head in its printing section. (3) In the printing section, an ink film is provided between the heating element and the recording paper, and the heating element is extended to a part of the substrate corresponding to the downstream side of the part where the ink film is peeled off from the recording paper. Electronic equipment according to scope 2.