JPS6034803B2 - Thermal head for thermal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head used in a thermal recording device that enables high-speed recording.

Thermal recording methods have attracted attention from various quarters in recent years due to their noiseless, maintenance-free, low cost, and excellent printing quality, and research and development is progressing.

However, compared to methods such as electrostatic recording or current recording,
The recording speed is low, and further speeding up is required for use in facsimiles, computer printers, etc.

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

Until now, the relationship between the durability of the thermal head and the properties of the glaze layer glass was not clear, but as a result of various studies, in order to improve the durability of the thermal head at high temperatures, it is necessary to improve the heating resistor as well as to improve the thermal head's durability at high temperatures. It has been found that it is important to improve the substrate on which the heating resistor is formed.

The present invention was made in view of these points, and by increasing the melting point of the glass of the coated glaze layer,
The present invention provides a thermal head that is more durable at temperatures than conventional ones.

In the present invention, as the substrate to be glazed has good thermal conductivity, a substrate mainly composed of oxides such as alumina, beryllia, and magnesia is used. In addition, as heating resistors, shelved zirconium or other shelved heating resistors are stable over time, and their resistance values can be adjusted.In particular, high specific resistance values can be set, so they can be used on substrates with good heat resistance. used in combination with

FIG. 1 is a cross-sectional view of a thermal head according to the present invention, in which a heating resistor 2, electrical conductors 3, 4 are coated on a substrate 1 made of glass coated on alumina, and protective layers 5, 6 are coated thereon. .

That is, the thermal head for a heat-sensitive recording device includes a substrate made of a material with good thermal conductivity and coated with a low-alkali glass layer, and a heating resistor, an electric wiring section, and an insulating protective film attached to the substrate. The present invention provides the above-mentioned glass layer whose composition has K20 and Na20≦1.0% by weight, and whose softening temperature is 745%.
00 or more.

If this glass layer is too thick, heat will accumulate, which is unfavorable for high-speed recording.On the other hand, if it is too thin, power consumption will have to be set high due to heat loss due to heat conduction to the substrate side, and the burden on the heating resistor will increase. Life expectancy will be shortened. Therefore, the thickness range is 10 to 90 mm, and a particularly preferable range is 25 to 60 mm. The embodiments of the present invention will be explained below using examples.

Examples 1 to 7 Glazed ceramics were prepared by coating approximately 50 layers of glass of various compositions on a polished 0.63 willow alumina substrate.

The analytical values (weight %) of those glass layers are shown in Table-1. Table I (Note) Ts in Table I is the glass softening point.

Approximately 60% of
A zirconium shelf (ZrB2) of 00A was deposited, and Ti and Au were evaporated to a thickness of 50△ and lr by an electron beam method. This was patterned into a thermal head heating resistor and an electric conductor using a selective etching method.

On top of this, 1.5 mounds of tantalum oxide (Ta20) was applied using argon medium high frequency sputtering method.
5) was attached as a 5-mount skin protective layer. The resolution of the thermal head made in this way was 4 lines/willow. In addition, this thermal head is operated at 650 Hz at a cycle of 50 Hz.
Table 2 shows the rate of change in resistance of the heating resistor when a power of 3.2 W per dot was applied for 1 hour during the pulse of s.

Table-2 (note) Railing chest trunk.

Willow R.

:Resistance value before test R:Resistance value after test Note that a practical printing density was obtained with the above applied power.

As shown in Table 2, it was found that the softening point of the glass layer and the content of alkaline components (K20 + Na20) have a significant effect on the durability of the thermal head at high temperatures. ．． 0%, softening point 745oo
Good results were obtained with the above. No. in Table-2. When the thermal head No. 6 was subjected to a durability test for 50 hours under the above conditions, the change in resistance value was 3.5% or less.

If the resistance change rate exceeds 10%, it is determined that the life has come to an end. No. 6 thermal head has a lifespan of more than 500 hours and does not fall under the scope of the present invention. The lifespan of samples 1, 2, and 5 was within 1 hour. Examples 8 to 15 Next, instead of the heating resistor of the zirconium shelf,
Thermal heads using other shelved heating resistors are also demonstrated.

The glass layer at this time was No. 1 in Table-1. 4 was used. The rest of the structure is the same as that of the zirconium compound thermal head. For this thermal head, 50H
Z cycle, 650 s during pulse, 3.2 per dot
Table 3 shows the resistance change rate after applying W power for 1 hour. Again, the effect of the glass layer according to the present invention was recognized. Table 3 Also, when the heating resistor is made of nichrome or tantalum nitride (TaN), K20 + Na20≦1.0%, TSZ74
The effect was recognized at 500.

In the thermal head according to the present invention having the wiring diagram shown in Fig. 2, m = 24, n = 64, and the heating resistor (R, . - Rmn) has 192 needles and 153 needles during the effective recording of A4 size.
were arranged in a line.

For example, when printing from the left using a facsimile thermal head with a resolution of 8 main scan lines/side, the upper common electrode A and the lower common electrode are energized and printed according to the recording signal, and sequentially from A2 to A2 to Am. energize and print the lower common electrode,
When printing on the 192 side during A4 size valid recording, further feeding the paper with a pulse motor, and repeating the above printing to record A4 size recording length 30 ratios at a resolution of 8 sub-scans / 80 W / boiling. It takes about 1 minute to print an A4 size sheet with a print pulse of 650 French seconds and a paper feed distance of 1 minute.

In other words, in a thermal recording facsimile device, a one-minute machine can be realized with a resolution of 8 sub-scanning lines per side, and the thermal head provided by the present invention is extremely useful in increasing the speed of thermal recording devices. It is something.

In addition, the signal distribution is divided into two systems using the above-mentioned thermal head,
For example, A, ~A, . If designed to record in combination with A,2 to A24, the recording speed will be approximately doubled, and A4 size can be recorded by 3 times.
It is also possible to print with inkstone sand.

The present invention is not limited to the above embodiments, but IA
Instead of I203, ceramics such as beryllia and sapphire, and metals with high thermal conductivity may be used.

2 Protective layer is Si02, Ta205, N203, Mg0
, Z2, etc. or SIC may be used.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of a thermal head according to the present invention, and FIG. 2 is a wiring diagram when using the thermal head according to the present invention. 1...Substrate coated with glass, 2...
Heat generating resistor, 3, 4... Electric conductor, 5, 6... Protective layer,
A, ~Am... Upper common lead part, {R, . ~
R, n, R2, ~R2n, Rm, ~Rmn}...
... Heating resistor (m x n pieces), Y ... Separation diode, B - Bn ... Lower common lead part. Figure 1 Figure 2

Claims (1)

[Claims] 1. A substrate made of a material with good thermal conductivity, which is coated on the substrate and has a softening point of 745°C or higher, and contains a total amount of sodium oxide and potassium oxide of 1.0% by weight. 1. A thermal head for a thermal recording device, comprising the following low alkali glass layer and a heating resistor disposed on the low alkali glass layer. 2. The thermal head according to claim 1, wherein the low alkali glass layer has a thickness of 10 to 90 μm. 3. The thermal head according to claims 1 and 2, wherein the heating resistor is zirconium boride.