JPS60208260A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent the difference in printing density even when printing is performed in both directions, by a method wherein a glass glaze layer having a strip shaped projection and a flat surface part extending along the single side thereof is provided to one main surface of a ceramic substrate and a resistance heat generator is provided on said projection while a part of the common electrode connected to said resistance heat generator is provided to the flat surface part. CONSTITUTION:A glass glaze layer having a projection 2a and a flat surface part 2b is formed to an alumina substrate 1 and a plurality of resistance heat generators 3 are arranged on said projection 2a while the electrodes 4a respectively connected to one terminals of the resistance heat generator 3 are provided so as to extend to the substrate 1 through one oblique surface of the projection 2a and the upper surface of the flat surface part 2b and individual electrodes 4b connected to the other terminals of the resistance heat generators 3 are provided so as to extend to the substrate 1 through the other oblique surface of the projection 2a. By this method, the flat surface part 2b of the glass glaze layer coming to a heat accumulation layer is provided to prevent the diffusion of heat from the common electrodes 4a and the temp. distributions in the common electrode side and individual electrode side of the heat generation part are made equal. As a result, the difference in printing density is not generated even when printing is performed in both directions.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal recorder for heat-sensitive recording used in calculators, personal computers, measurement, analysis, medical equipment, and the like.

(Structure of conventional example and its problems) As shown in FIGS. 1 to 3, one of the thermal heads that has been put to practical use in the past is a projection 2 made of a glass glaze layer on an insulating substrate 1. There is one in which a resistance heating element 3 is formed on the protrusion 2, and a common electrode 4a and individual electrodes 4b are provided on both sides thereof. Note that 5 is a lead wire connection portion, and 6 is a wear-resistant film. This protrusion 2 is a heating element 3
It improves the adhesion between the paper and the thermal paper, and also acts as a heat storage layer to efficiently transfer heat to the thermal paper, improving printing quality and reducing energy consumption.

However, when this thermal head performs left and right printing (bidirectional printing), there may be a difference in printing density. Possible reasons for this are as follows. First, since the main component of the electrode of the heating element is Cu or Au and has good thermal conductivity, a part of the heat generated in the heating element is diffused toward the substrate through the electrode. In this case, the force on the side of the common electrode 4a, which has a larger electrode area, diffuses a large amount of heat from the side of the individual electrodes 4b, resulting in a lower temperature. In other words, the center and bottom of the temperature distribution of the heating element section is biased toward the individual electrode side. Furthermore, in the case of bidirectional printing, as shown in FIGS. 4(a) and 4(b), in the moving direction of the head (arrows A and B) K, the contact part with the thermal paper 7 is at the center of the protrusion. Since it is shifted from the axis Y-Y' toward the common electrode 48 or the individual electrode 4b, there is a difference in print density. To solve this problem,
In FIG. 1, it is possible to make the notch C of the common electrode 4a deeper, but the area of the common electrode must be increased accordingly, which has the disadvantage of increasing the shape of the head.

(Objective of the Invention) The present invention eliminates such conventional drawbacks, and provides a thermal head that has no difference in printing density even when performing bidirectional printing and can be miniaturized.

(Structure of the Invention) The thermal head of the present invention includes a band-shaped protrusion on one main surface of a ceramic substrate and a glass glaze layer covering a flat surface on one side of the band-shaped protrusion, and a resistive heating element disposed on the protrusion. By providing a part of the common electrode connected to this resistance heating element on a flat surface, the temperature distribution on the common terminal side and the individual electrode side of the heating element part is made to be equal.

(Description of Embodiment) An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 5, a glass glaze layer 2a (width 700 microns) and 2b (width 500 microns) with a thickness of 60 microns are formed on an alumina substrate j.

form). Next, only the glass glaze layer in the 2b part was etched to a thickness of about 40 microns to make it thinner.
Protrusions 2a and flat portions 2b of the glass glaze layer as shown in the figure are formed. Furthermore, a plurality of resistance heating elements 3 are arranged on this protrusion 2a, and this A fN II! Individual electrodes 4b each connected to one end of the K body 3 and each end of the common portion are extended to the substrate 1 via the slope of the projection 2a. In this way, the glass glaze flat part 2b serving as a heat storage layer is provided to completely prevent the diffusion of heat from the common electrode 4a, and to equalize the temperature distribution on the common electrode side and the individual electrode side of the heat generating part. .

(Effects of the Invention) As described above, in the thermal head of the present invention, a band-shaped protrusion and a glass glaze layer having a flat surface on one side are provided, and a resistive heating element and a part of the common electrode are provided on this. Therefore, the center of the temperature distribution of the heating element portion substantially coincides with the center of the pattern, and therefore, even when bidirectional printing is performed, there is no difference in printing density, and furthermore, miniaturization is possible.

[Brief explanation of drawings]

Fig. 1 is a plan view of a conventional thermal head, and Fig. 2 is a plan view of a conventional thermal head.
The same side view and FIG. 3 are the x-x' sectional view of FIG.
Figures (a) and (b) are diagrams showing the contact state between the head and the thermal paper in the case of bidirectional printing, Figure 5 is a flat view ii of an embodiment of the present invention, and Figure 6 is a side view of the same side. FIG. 7 is a sectional view of the same. ]・Alumina substrate, 2a...Glass glaze protrusion, 2
b... Glass glaze flat part, 3... Resistance heating element,
4a・Common electrode, 4b・Individual electrode, 5・Lead wire connection part, 6・Abrasion resistant film, 7：Thermosensitive paper. Figure 1 Figure 2 Figure 3 Figure 4 (a) (b) A B

Claims (1)

[Claims] A glass glaze layer having a band-shaped protrusion and a flat part extending from a part of the protrusion is provided on the whole surface of the ceramic substrate,
A plurality of resistance heating elements are disposed on the protrusion, and a common electrode connected to one end of each of the resistance heating elements is connected to the ceramic substrate through one slope of the protrusion and the flat surface. The thermal device is characterized in that individual electrodes connected to each other end of the resistive heating element are extended onto the ceramic substrate through the other slope of the projection.