JPH03158253A - Thick film type thermal head - Google Patents

Abstract

PURPOSE:To prevent skipping of a head-sensitive paper from happening by forming a smooth recessed part on a glaze layer directly under a heating element. CONSTITUTION:On a insulating substrate 2, a glass paste is printed, excepting an area 2a which is directly under a heating element 6; and a glass glaze layer 3-1 is formed by baking it. When a glass glaze layer 3-2 is formed by printing a glass paste further and baking it, a glass glaze layer 3 which has a smooth curvature is formed because a paste which contains amorphous glass is used. On the glass glaze layer 3, a gold paste is printed, and common electrodes 4 and individual electrodes 5 are formed by baking it. In addition, on a recessed part 3a on the glass glaze layer 3, a ruthenium paste is printed, and a heating resisting element 6 is formed by baking it. On the insulating substrate 2, a glass paste is printed further, and a protective glass layer 7 is formed by baking it. By this method, the surface temperature distribution is improved, and the printing grade can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a thick-film thermal head, and more specifically, to improvement of its temperature change distribution.

(b) Prior Art FIG. 3 shows an example of a conventional thermal head of a thickness of 112 mm. Reference numeral 12 denotes an insulating substrate made of a material such as alumina ceramic, on the surface of which an amorphous glass glaze layer 13 is formed as a heat storage layer. A common electrode 14 and individual electrodes 15 are formed on the glass glaze layer 13, and the common electrodes 14 and the individual electrodes 15 are interlocked in a comb-teeth shape.

On the common electrode 14 and the individual electrodes 15, there is a band-shaped thermal resistance t.
'iT body 16 is formed. A portion of this heating resistor 16 sandwiched between adjacent 1iTl electrodes 14 and 14 corresponds to one dot. Furthermore, a protective glass layer 17 is formed on the insulating substrate 12L, and the heat generating resistor 1G and both 1ifl
The electrodes 14 and the individual electrodes 15 are coated and protected from abrasion caused by contact with the thermal recording paper.

(C) Problem to be solved by the invention J In the above conventional thick film type thermal head, the heating resistor 16
Since the thickness of the protective glass layer 17 is as large as, for example, 10 μm, the layer thickness of the protective glass layer 17 directly thereon becomes small.

Therefore, the temperature change distribution on the surface of the protective glass layer 17 during heat generation is
As shown in FIG. 3(a), the temperature is concentrated in the center of the heating resistor 16, and there is a portion where the temperature exceeds 400'C.

When the surface 11rA degree is locally high as described above, if the torque for feeding the thermal recording paper is weak, the surface layer of the thermal recording paper will stick to the high quality portion of the surface of the thermal head. If the thermal recording paper is further fed in this state, the thermal recording paper may skip and a white line portion may appear where no printing is performed (in a direction perpendicular to the feeding of the thermal recording paper), resulting in a decrease in print quality.

This invention was made in view of the above, and the surface 41? It is intended to be used as a support for thick-film thermal heads that improve distribution and print quality.

(d) Division! ? l! The structure of the thick film thermal head of the present invention will be explained with reference to FIG. 1, which corresponds to an embodiment. 3 and this glaze T
I! electrodes 4.5 formed on these electrodes 4.43;
A heating resistor 6 formed on the glaze layer 3 so as to extend over the electrode 4.5, and a wear-resistant layer 7 covering the electrode 4.5 and the heating resistor 6, A gentle recess 3 is formed in the glaze layer 3 directly under the heating resistor 6.
It is characterized by forming a.

Therefore, the amount of protrusion of the heating resistor 6 from the glaze layer surface 3b is reduced, and the wear resistance w47 directly above the heating resistor 6 is reduced.
The layer thickness can be made larger than before, and local increases in surface temperature can be prevented. Further, since the protrusion qF of the heating resistor 6 is reduced, the amount of protrusion of the wear-resistant layer 7 is also reduced, and the feeding of the thermal recording paper becomes smooth. From these two points, it is possible to prevent the surface layer of the heat-sensitive recording paper from sticking to the thermal head, and to improve the printing quality.

(E) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 et al.) are longitudinal cross-sectional views of essential parts of the membrane type thermal head according to the embodiment. 2 is an insulating substrate made of a material such as alumina ceramic, and an amorphous glass glaze 13 is formed on the surface thereof. A recess 3a is formed on the surface 3b of the glass glaze layer 3. The depth of the recess 3a is, for example, 10 .mu.m, and the width thereof is the same as the width of the heating resistor 6, which will be described later, and is usually 100 to 400 .mu.m.

An example of a method for forming the glass glaze layer 3 having the recesses 3a will be described with reference to the second section.

First, vI! , a glass paste is printed on the edge substrate 2-A except for the portion 2a immediately below the heating resistor 6, and this is fired to form the first glass glaze layer 3-6 (see FIG. 2).
a) Reference f1. ().Furthermore, a glass paste is printed and fired to form the second glass glaze layer 34 [see Fig. 2(b) a]. Since a paste containing crystalline glass is used, gold (
Au) paste is printed and baked to form #thin electrode 4
and individual electrodes 5 are formed. Furthermore, a ruthenium (Ru)-based paste is printed in the recesses 3a on the glass glaze layer 3, and is fired to form the heating resistor 6. Since the heating resistor 6 is formed in the recess 3a, the amount of protrusion of the heating resistor 6 from the surface 3b of the glass glaze layer can be made smaller than in the conventional case.

Insulation 7. A glass paste is further printed on the C temporary 2, and this is fired to form the protective glass layer 7.

In the portion 7a of the protective glass layer 7 directly above the heat generating resistor 6, the protrusion V of the heat generating resistor 6 is small, so that the layer thickness is not reduced as in the conventional case. Also, the protrusion of this portion 7a is 1tA.
31 tm or less, and the surface of the protective glass layer 7 also becomes flat.

FIG. 1 (a3) shows the temperature distribution on the surface (the surface of the protective glass layer 7) of the thick-film thermal head of the example.Since the layer thickness of the portion 7a of the protective glass layer 7 is ensured,
There is no localized high temperature area (400"C or higher), which prevents the thermal recording paper surface layer from sticking to the area 7a. Furthermore, since the surface of the protective glass layer 7 is flat, the thermal recording paper surface layer can be prevented from sticking to the area 7a. Paper feeding also becomes smoother.Therefore, it is possible to prevent the thermal recording paper from skipping and to prevent the occurrence of horizontal white lines.

(f) Effects of the Invention As explained above, the thick-film thermal head of the present invention is characterized by the formation of a recessed portion in the glaze layer directly under the heating resistor. Since there is no localized high temperature area and the number-maru head damage surface becomes flat 1B, it is possible to prevent the heat-sensitive recording paper from skipping and to prevent the occurrence of white cotton areas.

[Brief explanation of the drawing]

7A1 (a) shows I'ZI according to an embodiment of the present invention.
A diagram explaining the surface l and l12 degree distribution of the Ii7 type thermal head. Figure 1 (b) is a vertical cross-sectional view of the main part of the same thick film type thermal head. Figures 2 (a) and 2 (b) are , same thickness ■
Figure 3(a) is a diagram illustrating the glass glaze layer formation process of a conventional thick-film type thermal head; Figure 3(b) is a diagram illustrating the gable distribution of a conventional thick-film type thermal head; FIG. 2 is a vertical cross-sectional view of a main part of a thick-film thermal head. 2: wtA monolayer, 3; glass glaze layer, 3
a: recess, 4: common electrode, 5: individual electrode, 6: heating resistor, 7: protective glass layer. 2nd (a) 2nd (b) a Figure <8) Figure (a) Plow Figure 3 (b)

Claims (1)

[Claims] (1) An insulating substrate, a glaze layer formed on the insulating substrate, an electrode formed on the glaze layer, and a heating resistor formed on the glaze layer so as to straddle the electrode. and a wear-resistant layer covering the electrode and the heating resistor, the thick film thermal head comprising: a wear-resistant layer covering the electrode and the heating resistor, wherein a gentle recess is formed in the glaze layer directly under the heating resistor. type thermal head.