JPS6387255A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head strong against heat shock and having good heat conductivity, by forming an abrasion resistant layer from an oxygen deficient film and a thermally oxidized film. CONSTITUTION:A glazed glass layer 2, a heat generating resistor layer 3, a current supply conductor layer 4 and an oxidation preventing layer 5 are formed on an insulating substrate 1 and an abrasion resistant layer 6 consisting of an oxygen deficient TaOx (x<2.5) film 6a and the thermally oxidized film 6b formed to the surface thereof is formed on the oxidation preventing layer 5. When voltage is repeatedly applied to a thermal head, the heat generating temp. of a heat generating dot part changes but, herein, a time td required for the temp. of the dot part to exceed peak temp. TA and fall by 30% is set as the basis of heat response. This thermal head is shortened by about 10% in td and enhanced in heat response as compared with a conventional one of which the abrasion resistant layer is constituted only of the oxygen deficient TaOx (x<2.5) film. Since td is kept almost constant regardless of the magnitude of the peak temp. TA, heat response is kept even when TA is changed in order to change the printing condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal binder used in a thermal printer or a thermal transfer printer, and is particularly concerned with improving the wear-resistant layer thereof.

"Prior art and its problems" Thermal heads installed in thermal printers or thermal transfer printers, etc., have, for example, a plurality of heating resistive elements linearly arranged on the same substrate, and the heating resistive elements are heated with electricity according to information, and the thermal head is It is used for color recording on recording paper or for transfer recording on plain paper via an ink ribbon.

Conventionally, a general thermal head is made of Ta, N, Ta-W-N, etc., on an insulating substrate 1 made of alumina or the like, on which a glass glaze layer 2 is partially formed, as shown in FIG. 3, for example. Heat generating resistor layer 3, power supply conductor layer 4 made of AI etc., oxidation prevention layer 5 made of 5i02 etc., Ta2
It was constructed by sequentially laminating wear-resistant layers 6 made of O, etc. In this case, the power supply conductor layer 4 is patterned into a plurality of individual electrodes and a common electrode, and the heat generating portion A
is configured.

In this way, in conventional thermal heads, Ta205 is often used as the wear-resistant layer 6;
Since O, is susceptible to thermal shock, its life tends to be somewhat shortened, and its sputtering film formation rate is slow, resulting in a reduction in production efficiency.

On the other hand, as the wear-resistant layer 6, oxygen-deficient TaOx (x<
It is known that using 2.5) is more resistant to thermal shock than Ta205 film and helps extend the life of the thermal head, and the sputtering film formation rate is faster than Ta205H, improving souvenir efficiency. ing.

However, oxygen-deficient TaOx has poor thermal conductivity compared to Ta205, so it has poor thermal response.
Another disadvantage is that the temperature distribution in the heat generating part is wide. Therefore, the wear-resistant layer 6 is made of oxygen-deficient TaOx.
When using , there were problems with high-speed printing and print quality.

OBJECT OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a thermal head that is resistant to thermal shock and has good thermal conductivity.

"Structure of the Invention" The thermal head of the present invention includes at least a heating resistor layer, a power supply conductor layer, an oxidation prevention layer, and an abrasion resistant layer on an insulating substrate, and the abrasion resistant layer is an oxygen deficient layer. TaOx(x
<2.5) It is characterized by consisting of a film and a thermal oxide film formed on its surface layer.

In this way, in the present invention, the wear-resistant layer is made of oxygen-deficient T.
Since it is composed of an aOx (x<2.5) film and a thermal oxide film, it is strong against thermal shock and has good thermal conductivity.

Therefore, a thermal head with a long life and excellent thermal responsiveness can be obtained.

In the present invention, the above-mentioned wear-resistant layer can be formed by forming an oxygen-deficient TaOx film by sputtering, and then heat-treating the film to further oxidize its surface layer. In this case, the heat treatment is performed, for example, for 50 minutes in air.
This can be done by heating at 0° C. for about 1 hour, or by heating the heating dots by applying electricity.

In addition, when using a conventional thermal head, the heating dot part is heated by electricity, but in this case, it comes into contact with thermal recording paper or ink ribbon, so the surface layer of the wear-resistant layer is coated with those materials. was deposited, and thermal oxidation was not performed sufficiently, making it impossible to obtain the effects of the present invention.

"Embodiment of the Invention" FIG. 1 shows an embodiment of a thermal head according to the present invention.

This thermal head has a glass glaze layer 2 of approximately 4 mm on an insulating substrate 1 made of alumina with a thickness of 0.635 mm.
It is formed to have a thickness of 0 um and to partially protrude. On the insulating substrate 1 and glass glaze layer 2, T
The heating resistor layer 3 made of a-W-N has a thickness of about 0.05u.
It is formed by m. In order to prevent the glass glaze layer from being corroded by the hydrofluoric acid etching solution, an undercoat layer (not shown) is provided between the glass glaze layer 2 and the heating resistor layer 3. 3, there is a power supply conductor layer 4 made of an AI film with a thickness of 1.5 um.
is formed. The power feeding conductor layer 4 is patterned into individual electrodes and a common electrode, and a heat generating portion A consisting only of the heat generating resistor layer 3 is formed in the gap between the individual electrodes and the common electrode.

On the power supply conductor layer 4, an anti-oxidation layer 5 made of SiO□ and having a thickness of 2 um is formed. Each of these layers is formed by sputtering or vacuum deposition. Then, on the antioxidant layer 5, oxygen-deficient TaOx
A wear-resistant layer 6 is formed of a (x<2.5) film 6a and a thermal oxide film 6b formed on its surface. This wear-resistant layer 6 was formed on the entire thermal head after sputtering an oxygen-deficient TaOx (x<2.5) film with a thickness of 5 um. A thermal oxide film was formed on the surface layer by heat treatment at 500° C. for 1 hour in the atmosphere.

FIG. 2 shows another embodiment of the thermal head according to the invention. Note that in the drawings, parts that are substantially the same as those in FIG.

In this thermal head, the thermal oxide film 6b of the wear-resistant layer 6 is formed only on the heat generating portion A. That is, after forming an oxygen-deficient TaOx (x<2.5) film with a thickness of 5 um, a voltage is applied to the power supply conductor layer 4, and the heat-generating dots are heated by electricity, and only the heat-generating part A is heated. A thermal oxide film 61 is formed.

FIG. 4 shows the change in the heat generation temperature of the heating dot portion when a pulse voltage is repeatedly applied in a general thermal head. Here, the peak temperature ■A is passed and the temperature decreases by 30% (i.e., 0.7XTA
The time (td) until the temperature reaches 30% is called the 30% cooling time and is used as a measure of thermal response.

FIG. 5 shows the thermal head of the embodiment shown in FIG. FIG. 4 is a diagram similar to FIG. 4 showing responsiveness. In FIG. 5, a indicates the thermal head of the embodiment, and 5 indicates the conventional thermal head.

As described above, it can be seen that the temperature of the thermal head of the example is particularly faster than that of the conventional thermal head.

FIG. 6 shows how the thermal head of the embodiment shown in FIG. The data shows the actual measurement of darkness td when the temperature drops by 30% by changing the temperature TA. As described above, the thermal head of the embodiment has a td of about 10 compared to the conventional thermal head.
It can be seen that the thermal response is improved. Also,
Since td is kept approximately constant regardless of the size of the peak temperature ■^, it can be seen that the thermal responsiveness is maintained even if TA is changed to change the printing conditions.

Note that the thermal response of the thermal head of the example shown in FIG. 2 was similar to that of the thermal head of the example shown in FIG.

"Effects of the Invention" As explained above, according to the present invention, the wear-resistant layer is composed of an oxygen-deficient TaOx (x<2.5) film and a thermal oxide film formed on the surface layer. Therefore, it becomes resistant to thermal shock and has a longer lifespan, and also has improved thermal conductivity and good thermal response. Furthermore, since the temperature distribution of the heat generating portion is improved, high-speed printing and high printing quality can be achieved. Another advantage is that the above effects can be obtained simply by performing a relatively simple heat treatment.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing one embodiment of the thermal head according to the present invention, Fig. 2 is a cross-sectional view showing another embodiment of the thermal head according to the present invention, and Fig. 3 is a cross-sectional view showing an example of a conventional thermal head. Figure 4 is a chart showing the change in heat generation temperature of the heating dot part when a pulse voltage is repeatedly applied in a general thermal head, and Figure 5 is a graph showing the temperature difference between the thermal head of the embodiment and the conventional thermal head. A chart similar to Fig. 4 showing a comparison of responsiveness, and Fig. 6 shows the results of actually measuring the 30% cooling time td by changing the peak temperature TA for the thermal head of the embodiment and the thermal head of the conventional example. This is a diagram. In the figure, 1 is an isolated substrate, 2 is a glass glaze layer, 3 is a heating resistor layer, 4 is a power supply conductor layer, 5 is an antioxidant layer, 6 is a wear-resistant layer, 6a is an oxygen-deficient TaOx ( x<2.5)
The film 6b is a thermal oxide film.

Claims (1)

[Claims] In a thermal head comprising at least a heating resistor layer, a power supply conductor layer, an antioxidant layer, and an abrasion resistant layer on an insulating substrate, the abrasion resistant layer is made of oxygen-deficient TaO_x(x
<2.5) A thermal head comprising a film and a thermal oxide film formed on the surface layer of the film.