JPS6034802B2 - Thermal head for thermal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate on which a heating resistor is formed and a thermal head in which a shelved zirconium heating resistor is formed on the substrate when manufacturing a thermal head used in a thermal recording device. It is.

Thermal recording methods are noiseless, maintenance-free, low cost, and have excellent printing quality, so they have attracted attention from various quarters in recent years and have been researched and developed. However, the recording speed is lower than that of electrostatic recording or current recording, and further speeding up is desired for use in facsimiles, computer printers, and the like.

In order to increase the speed of thermal recording, it is necessary to improve wiring methods, electric circuits, etc., as well as improve the durability of the heating resistance of the thermal head when used at high temperatures.

Conventionally, substrates for thermal heads (hereinafter referred to as thin-film thermal heads) manufactured using thin-film manufacturing technology have the following characteristics: 1. The surface is extremely smooth. 2. The heat generated by the heat-generating resistor is efficiently transferred to the thermal paper, and the heat generated by the heating resistor is efficiently transferred to the thermal paper. 3. Low rise in substrate temperature 3. Good flatness with no warping or twisting (because photo-etch technology is used to produce fine patterns for resistors, electrodes, etc.) 4. Low alkali ions that can cause deterioration of heating resistors etc. are required.

Due to these conditions, glazed ceramics made of alumina coated with a glass layer are generally preferred.

Additionally, the glass layer of glazed ceramics requires the following:

1. The coefficient of thermal expansion is similar to that of alumina (to achieve flatness). 2. Good adhesion to alumina. 3. A smooth glazed surface can be obtained. Glazed ceramic glaze layer that satisfies these conditions. Currently, it is difficult to obtain a material with a high softening temperature, and the maximum use temperature is currently limited.

On the other hand, due to the demand for faster thermal recording, thermal head heating resistors are required to be more durable at high temperatures than ever before.

As a result of various studies on the above points, it has been found that in order to improve the durability of the thermal head at high temperatures, it is necessary to improve the heating resistor as well as the substrate on which the heating resistor is formed.

The present invention has been made in view of the above points, and by interposing quartz (Si02) between the glass layer on the glazed ceramics and the heating resistor, the heat resistance of the glass layer is improved without impairing the features of the glazed ceramics. By improving the drawback of low performance, the present invention provides a thermal head that can withstand use at high temperatures and is useful for increasing the speed of thermal recording.

In the present invention, as a material having good thermal conductivity for the substrate that is glazed, a material composed mainly of oxides such as alumina, beryllia, and magnesia and bonded together is used. or,
As a heating resistor, shelved zirconium or other shelved heating resistors are stable over time, and their resistance value can be adjusted.
In particular, since it is possible to set a high specific resistance value, it is used in combination with a substrate with good heat resistance.

Figure 1 shows an example of a conventional thermal head, in which a heating resistor 2, lead-out conductors 3 and 4 are placed on a glazed ceramic substrate 1.
, and protective layers 5 and 6 are formed thereon.

FIG. 2 shows a thermal head according to the present invention, which is characterized in that a quartz thin film 7 is coated on glazed ceramics.

The rest is the same as in FIG. The present invention will be illustrated below with examples.

Example 0.63 side alumina plate was covered with 50 μm of K20 and Na2.
Using a quartz (Si02) plate target on glazed ceramics coated with a glass layer with a softening point of 0.9% and a softening point of 620 oo, thin films of four different thicknesses of quartz were formed by high-frequency sputtering in an argon atmosphere. Ta.

On this substrate, a shelved zirconium target with a thickness of 800 angstroms (A
) was attached, and then Ti and Au were deposited using electron beam evaporation to form thin films of 50Δ and 1.5mm, respectively. Next, a heating resistor and lead-out conductor were fabricated by selective photoetching.

Subsequently, quartz and tantalum oxide were deposited by high-speed sputtering with 2 sputters and 8 sputters, respectively. One rectangular electrical pulse of the thermal head produced by these steps is applied at a cycle of 50Hz, IW for 2.8hs during the pulse per one heating resistor, and 1.5Hz during the pulse. Table 1 shows the rate of change in the resistance value of the heating resistor after applying a pulse of 2.4 W for 1 hour.

Table 1 *Resistance value change %=Three voices X・oo Resistance value before Ro test R Resistance value after test} The recorded density at this time was measured with a microdensitometer and was 0.6 or more.

In Table 1, tl} to {small are based on the present invention, and Comparative Example m has a heating resistor directly attached to the glazed ceramics, and the other manufacturing conditions are the same.

Furthermore, when the thermal head of Example 1 was subjected to a long-term test at lmS and 2.4W for 50 cycles, the resistance value change rate was 12.8%, indicating that its lifespan was over 500 hours. In the same test, the wire of the comparative example broke after 5 field hours, demonstrating the effectiveness of the present invention.

Next, as Examples 5 to 12, examples will be shown in which the shelved zirconium heating resistor is replaced with another shelved zirconium heating resistor. The thickness of the quartz layer of this thermal head was 2 mm, so the other configurations were the same as in Example 1. In addition, as Comparative Examples 2 to 9,
The structures of Examples 5 to 12 except that the quartz layer was removed were prepared. A rectangular electric pulse is applied to the above thermal head at a cycle of 50Hz, with 1 pulse per heating resistor.
．． Table 2 shows the rate of change in resistance after applying 2.4 W at 2 hs for 1 hour. As shown in Table 2, by coating glazed ceramics with a quartz thin film, it is possible to improve the drawback of low maximum operating temperature without sacrificing the advantages of glazed ceramics such as surface smoothness and thermal conductivity. Therefore, the present invention is extremely useful in increasing the speed of thermal recording devices.

Note that the present invention is not limited to the above-mentioned embodiments. For example, the substrate coated with glass can be selected from materials with high thermal conductivity such as beryllia, sapphire, or metal, and the method for forming the quartz thin film is high-speed sputtering. , electron beam evaporation, ion plating, or C.I. V. It is possible to use a chemical method such as D.

If the quartz layer is too thin, it will be easily influenced by the underlying material and will have little effect; if it is too thick, the production cost will increase and the thermal head will generate heat, making it undesirable for high-speed recording.

Therefore, a preferable range of the thickness of the quartz layer is 0.2 to 50 am, and a particularly preferable range is 0.5 to loAm. Furthermore, it can also be used for heat generating resistors such as nichrome alloys and tantalum nitride; for thermal heads and substrates for hybrid integrated circuits, which are highly recommended.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view of a conventional thermal head, and FIG. 2 is an explanatory sectional view of a thermal head according to the present invention. 1... Glazed ceramics substrate, 2...
・Heating resistor, 3, 4... Output conductor, 5, 6...
...Protective layer, 7...Quartz thin film. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A glazed substrate made of a material with good thermal conductivity coated with a glass layer, a quartz layer coated on the glazed substrate, and a heating resistor disposed on the quartz layer. Thermal head for thermal recording devices with special features. 2. The thermal head according to claim 1, wherein the quartz layer has a thickness of 0.2 to 50 μm. 3. The thermal head according to claims 1 and 2, wherein the heating resistor is zirconium boride.