JPH02286260A - Thermal printing head - Google Patents

Abstract

PURPOSE:To allow a printing head to be positional in a widely tilted angle with an adequate current capacity maintained on a shared electrode by chamfering the shared electrode formation side of a heat-resistant insulating substrate starting with an area near a part-glazed glass, and forming part of the shared electrode on the chamfered part. CONSTITUTION:A glazed glass 2 is formed on a heat-resistant insulating sub strate 1, and further, a thermal element 3 is formed on the glazed glass 2. The substrate 1 is chamfered starting with the end of the glass 2, and a shared electrode 4 is formed under the glass 2. This shared electrode 4 is connected to a top film as a shared electrode 5 in A section. In this case, a V groove 9 is formed on the green sheet of an alumina insulating substrate 1 using a die, then the groove 9 is baked or the groove 9 is formed using dicing saw after the baking of the green sheet. Next, a metallic paste of Au or Ag/Pt type is applied using a silk screen printing technique in such a manner that the paste covers part of the V groove 9. The glazed glass 2 is baked at a slight ly lower temperature than when the metallic paste is baked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal print head used in a thermal printer or facsimile.

[Conventional technology]

In recent thermal print heads, regardless of whether they are serial or line types, a partial glaze glass on which a heating element is arranged is placed on the end surface of the head substrate in order to improve print quality. This means that by tilting the head at a certain angle with respect to the paper surface, the ink ribbon peeling angle can be made larger, and by concentrating the force on one point when pressing the head, printing quality can be improved. This is because I have come to understand. Therefore, conventional thermal print heads have structures as shown in FIGS. 3(a) and 3(b). That is, by disposing a heating element on the partially glazed glass 2 and making the B part of the common electrode 5 as small as possible,
In order to ensure the current capacity of the common electrode 8, which has become smaller as shown in FIG. 3(b), a method was adopted in which the back surface of the substrate 1 was used.

Recently, a head with a structure as shown in FIG. 4 has been proposed, which attempts to increase the current capacity of the common electrode 4 by disposing the common electrode 4 under the glaze glass 2. It is something.

[Problem to be solved by the invention]

However, by arranging the glaze glass 2 on the edge of the substrate in this way, the heating element 3 is inevitably brought closer to the edge of the substrate, resulting in a narrower space for securing the common electrode, leading to problems such as those listed below. I ended up having to hold it.

(1) Common? When the current capacity of the four electrodes becomes small and multiple dots are energized simultaneously, a voltage drop phenomenon occurs and the print density decreases.

(2) As shown in FIG. 3(b), if the end surface and the back surface are used as a common electrode, the manufacturing cost of the head will be significantly increased.

(3) In both FIG. 3(a) and FIG. 3(b), the distance between the end face of the head substrate and the end face of the glaze glass is 200~
300 μm is required, and the more dots the head has, the more
It becomes difficult to bring the glaze glass close to the edge.

As a way to solve these problems, patent application 60-1
Methods such as No. 32580 have been proposed.

FIG. 4 is a cross-sectional view thereof, and the problems (1) to (3) above have been significantly improved. However, the glaze glass 2
The distance from the end surface of the substrate 1 to the end surface of the substrate 1 is 50 to 100 μm.
Therefore, in order to obtain a larger inclination angle of the head and a larger peeling angle of the ink ribbon, it is necessary to make this part smaller.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional problems and provide a thermal print head that has a sufficient current capacity while allowing the head inclination to be larger than the angle and the ink ribbon peeling angle.

[Means to solve the problem]

The thermal print head of the present invention has a partially glazed glass disposed on a heat-resistant insulating substrate, and is composed of at least a heating element, a common electrode, an individual electrode, and a lK film, and the heating element is provided on the partially glazed glass, A part of the common electrode is formed by chamfering the common electrode formation side of the heat-resistant insulating substrate near the partial glaze glass in a thermal head disposed under the partial glaze glass, and attaching a part of the common electrode to the chamfered portion. It is characterized by forming a part.
Embodiment] FIG. 1 shows an example of a cross-sectional view of the vicinity of a heating element of a thermal print head according to the present invention. 3 is formed. The heat-resistant insulating substrate 1 is chamfered from the end face of the glaze glass 2, and the common electrode 4 is formed under the glaze glass 2, and is connected to the upper thin film common electrode 5 at part A.

This thermal print head is manufactured through the following steps. First, V-shaped grooves 9 are formed in a green sheet of an insulating substrate such as alumina using a mold and then fired, or after the green sheet is fired, the V-shaped grooves 9 are formed using a dicing saw or the like. This V-groove 9 becomes a chamfered part forming a common electrode. The metal paste of the system is printed by screen printing. It is better for this metal paste to be fired at as high a temperature as possible, and one of the reasons why this type of method has been proposed so far but has not been put into practical use is because the firing temperature of the glaze glass is higher than the firing temperature of the metal paste. In the present invention, an Au paste with a firing temperature of 870 to 880°C was used. The design values of the width and thickness of the common electrode 4 need to be changed depending on the dot density of the thermal print head and the number of dots printed simultaneously.

Glaze glass 2 was fired at a temperature of 850°C±10°C, which is slightly lower than the firing temperature of the metal paste. A heating element layer and an electrode layer are formed on the substrate 1 thus completed using a vacuum thin film apparatus such as sputtering. Afterwards, using general photolithography technology, the heating element is formed.
Electrodes are formed, and finally a protective film is formed using a vacuum thin film device.

Printing experiments were conducted using the thermal print head manufactured in this way. 960 dots, 300d for experiment
The inclination of a head without a 0-chamfer using a pi standard head is limited to 10 degrees in some corners, and the inclination of a head with a chamfer is set to approximately 20 degrees. XEROX 4024
Table 1 below shows the results of a comparison of printing quality using paper generally called rough paper such as , Lancaster bond, etc.

Table 1 Comparison of print quality We are now able to supply thermal print heads that can provide a wide range of print quality comparisons. As a result, when multiple dots are energized at the same time, it is possible to eliminate the decrease in print quality due to the voltage drop phenomenon and to ensure print quality on rough paper.

O...Good △...Slightly good ×...Bad As shown in Table 1, there was a clear difference in print quality, and it was recognized that it was effective for printing on rough paper.

〔Effect of the invention〕

As explained above, according to the present invention, the tilt of the head can be adjusted while maintaining sufficient current capacity of the common electrode.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the vicinity of the heating element of the thermal print head according to the present invention, and FIG. 2 is a diagram after firing the glaze glass according to the present invention. Figures 3(a) and 3(b) are cross-sectional views of the vicinity of the heating element of a conventional thermal print head.
The figure is a sectional view of a conventional improved head. 1... Heat-resistant insulating substrate 2... Glaze glass 3... Heating element 4... Thick film common electrode 5... Thin film common electrode 6... Individual electrode 7... Protective film 8...・Common electrode and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki 1 person Figure 2

Claims (1)

[Claims] Partially glazed glass is disposed on a heat-resistant insulating substrate, and is composed of at least a heating element, a common electrode, an individual electrode, and a protective film, the heating element is provided on the partially glazed glass, and a part of the common electrode is In the thermal head disposed under the glaze glass, the common electrode forming side of the heat-resistant insulating substrate is chamfered from the vicinity of the partial glaze glass, and a part of the common electrode is formed in the chamfered portion. thermal print head.