JPS62148275A - Thermal head - Google Patents

Abstract

PURPOSE:To restrain wiring conductors of a thermal head from being corroded or broken, even when the thermal head is touched by a human body in mounting the head to a thermal printer or in replacing the head or when the thermal head is used for a long period of time in a highly humid atmosphere or a salt- containing atmosphere, by forming the wiring conductors from an Al alloy containing V or Zr in a predetermined concentration. CONSTITUTION:A thermal head is produced by, for example, sequentially providing heat generating elements 41-4n, wiring conductors 10 and a protective film 12 on a substrate 2 having a partial glaze layer 14, by sputtering or the like. In many cases, the partial glaze layer 14 is provided beneath the heat generating elements 41-4n, for accumulating heat. The conductors 10 are formed from an Al alloy containing V or Zr in a concentration of not more than 3.0at%. With this construction, a remarkable effect on suppression of corrosion is obtained, and reliability in driving the thermal head on contact with a human body, in use with an ink ribbon, in use in a highly humid or salt-containing atmosphere or in other similar situations can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to, for example, a thermal head of a thermal printer that forms a thermal transfer record on a recording paper surface, and particularly to suppression of corrosion of its wiring conductor.

[Conventional technology]

FIG. 1 is a plan view showing a general thermal head disclosed in, for example, Japanese Unexamined Patent Publication No. 11B58-131077, and FIG. 2 is a cross-sectional view taken along the line -■ in FIG.

In these figures, (2) is an insulating substrate, and a thin film circuit is formed on this substrate. This thin film circuit is a common circuit that commonly connects one end of each of a plurality of heating elements (4,) to (4o) and -1 heating elements (41) to (4,) arranged linearly on a substrate (2). Terminal (6) and heating element (41
) to (4,,) are individually connected to drive signal input terminals (8□) to (8,,), and a wiring conductor (lO) made of an Al film or the like. This thin film circuit is covered with a protective film (12) as shown in FIG.

The conventional thermal head is configured as described above, and when printing on recording paper, this thermal head is
Through a transfer master material coated with heat-melting ink,
While in close contact with the recording paper surface, a drive signal current corresponding to the print information is selectively passed between the common terminal (6) and the drive signal input terminals (8,) to (8,), and the heating element (4 ,)~(
4o) is selectively heated, and the thermal head is moved in the direction indicated by the arrow, which is perpendicular to the arrangement direction of the heating elements (41) to (4□).

The heat-melting ink applied to the transfer master material is heated by a heating element (
4,) to (4o), the ink is partially melted in accordance with the print information, and the melted thermofusible ink is transferred onto the recording paper surface, forming a serial print record on the recording paper surface.

[Problem that the invention seeks to solve]

In the conventional thermal head as described above, the pinhole in the protective film (12) covering the substrate (2) may reach the lower wiring conductor (10), and the protective film (12) may reach the lower wiring conductor (10).
If you accidentally touch 2) with your hand, or if the ink from the ink ribbon comes into contact with the protective film (12), sweat, ink, etc. may form in the pinholes in the protective film (12). The sweat and ink seep into the wiring conductor (1
0), the resistance of the wiring conductor (10) increases during driving, and eventually the wiring conductor (10) is broken, resulting in a significant deterioration of printing quality.

Further, when such a thermal head or a thermal printer equipped with the thermal head is subjected to a moisture resistance test, the same phenomenon as described above occurs. Particularly in the vicinity of the coast (because of the environmental atmosphere rich in chlorine), the above-mentioned phenomenon occurs significantly, reducing the reliability of the equipment.

In the past, many thermal heads had the structure shown in Figure 3, in which a glaze layer (14) made of glass or the like was formed on the substrate (2) in a layer of 40 to 50 layers in the wiring conductor (10).
It was provided on the order of μm. In such a thermal head, no matter how rough the surface is, if the glaze layer (14) is formed, the surface of the glaze layer (14) is extremely smooth, so pinholes will be formed and the above problems will occur. That never happened. However, in recent years, a thermal head having a structure in which a glaze layer (14) is only partially provided on a part of a substrate (2), as shown in FIG. 4, has been mainly used. In this case, since the glaze layer (14) is hardly formed on the substrate (2) at the wiring conductor (10), the above-mentioned problem occurs.

This invention was made to solve such problems, and even if contact with the human body occurs during the installation and replacement work of the thermal head in the thermal printer, or in a humid atmosphere or a salt-containing atmosphere, We provide an extremely reliable thermal head that does not cause drive circuit failure due to disconnection of wiring conductors due to corrosion, even after long periods of use, and does not increase power consumption of thermal printers due to increased resistance of wiring conductors due to corrosion. The purpose is to

[Means for solving problems]

The thermal head according to the present invention includes an insulating substrate, a thin film circuit formed on the substrate, and a protective film covering the thin film circuit. In the thermal head, the wiring conductor is made of an A1 alloy containing V or Zr at a predetermined concentration.

[Effect]

In this invention, since the wiring conductor is formed of an Al' alloy containing a predetermined concentration of V or Z, even if the thermal head comes into contact with the human body during installation or replacement of the thermal head in a thermal printer, Further, even if the thermal head is used for a long period of time in a humid atmosphere or a salt-containing atmosphere, corrosion and disconnection of the wiring conductors are suppressed.

〔Example〕

The basic structure of the thermal head according to the present invention is substantially the same as that described in the prior art. The present invention is characterized in that the wiring conductor for supplying power to the heating elements (41) to (4,) is made of (1) or an A1 alloy containing 30 atomic percent or less of Zr.

This thermal head includes, for example, a partial glaze layer (14
) on the substrate (2) with heating elements (41) to (4o),
It is manufactured by sequentially forming a wiring conductor (10) and a protective film (12) by a method such as vacuum evaporation or sputtering. A glaze layer (14) is often formed partially under the heating elements (4,) to (4n) to store heat.
. A heating element (4) is placed between the substrate (2) and the wiring conductor (10).
, ) to (4,) are not formed. Substrate (2
) Materials include alumina, AI'N, Be01S i
CXS i3N, Z r O, etc. are used.

The film thickness of the wiring conductor (10) on the substrate (2) is usually 0.5~
The thickness of the protective film (I2) thereon is about 2μ, and the thickness of the protective film (I2) thereon is 5 to 10μ. In such a structure, the roughness of the surface of the substrate (2) has a large effect on the generation of pinholes in the protective film (12). If the protective film (12) is made thicker, the number of pinholes will be reduced, but this will increase the cost and further deteriorate the thermal conductivity, which is not desirable in terms of the functionality of the thermal head.

In the thermal head configured as described above, the wiring conductor that supplies power to the heating elements (41) to (4,) is
■ or A4 alloy containing Zr, especially ■ or Zr 3
By forming with A1 alloy containing 0 at% or less,
It has the effect of significantly reducing corrosion, and can improve the driving reliability of the thermal head in situations such as contact with the human body, use of ink ribbons, high humidity, and chlorine-containing atmospheres.

Experimental Example 1 Samples of several thermal heads in which the V content of the wiring conductor was successively changed were immersed in artificial sweat having the composition shown in Table 1, then pulled out and placed in an atmosphere at 40°C and 90% relative humidity. After leaving it for 48 hours, the incidence of defects due to disconnection of the wiring conductor was determined. In addition, artificial seawater having the composition shown in Table 2 was prepared, and the samples were immersed and withdrawn, and the same tests as above were conducted. The results of these tests are shown in Table 3. From this result, the wiring conductor contains ① or Zr. 11 alloy, especially an Al alloy containing 3.0 atomic % or less of V or Zr, is found to be effective in significantly reducing corrosion.

In addition, in these samples, the wiring conductor of Al-V alloy was prepared by heating the alumina substrate in advance and
The target was formed by overlapping a small amount of V with a small amount of V, and was formed by sputtering in an argon gas atmosphere. The thickness of the heating element was approximately 1000 to 2000, the thickness of the wiring conductor was approximately 1.5 to 1.6 μm, and the thickness of the protective film was approximately 6 to 8 μm.

Table 1 Table 2 Table 3 Experimental Example 2 Reliability tests were conducted under the same conditions as Experimental Example 1 for several thermal head samples in which the Zr content of the wiring conductor was sequentially changed. The results are as shown.

Table 4 Experimental Example 3 For the thermal heads under conditions 1 and 4 in Table 3, we investigated the printing power per dot required to generate the minimum required peak heat generation temperature. The power output under Condition 1 was 1.4 W, and the power under Condition 4 was 1.2 W.

In this way, since an alloy with excellent corrosion resistance is used as the material for the wiring conductor of the thermal head, an increase in the resistance of the wiring conductor due to corrosion is suppressed, and an increase in power consumption is suppressed.
As a result, it was possible to extend the operating life of a portable printer using a battery or the like.

〔Effect of the invention〕

As explained above, this invention uses an alloy with excellent corrosion resistance as the wiring conductor of the thermal head, so even if it comes into contact with the human body or ink when installing or replacing the thermal head in a thermal printer, Even if they are used for long periods of time in humid or salt-containing atmospheres, the power consumption of thermal printers will not increase due to increased resistance of the wiring conductors due to corrosion, and the drive circuit will not malfunction due to disconnection of the wiring conductors due to corrosion. This has the effect of preventing the above problems and maintaining high reliability of the thermal printer over a long period of time.

4. Brief explanation of surfaces Figure 1 is a plan view of a general thermal head, Figure 2 (f) is a cross-sectional view taken along the [-11] arrow in Figure 1, and Figures 3 and 4 are views of other thermal heads. FIG.

In the figure, (2) is the board, (4,) to (4,,) are heating elements, (6) is a common terminal, (81) to (8,,) are drive signal input terminals, and (10) is wiring. A conductor, (12) a protective film, and (14) a glaze layer.

Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) Consisting of an insulating substrate, a thin film circuit formed on this substrate, and a protective film covering this thin film circuit, this thin film circuit has multiple heating elements that selectively generate heat, and 1. A thermal head comprising a wiring conductor for supplying power to a body, the wiring conductor being formed of an Al alloy containing V or Zr at a predetermined concentration. (2) The concentration of V or Zr in the Al alloy is 3.0 at%
A thermal head according to claim 1, characterized in that: