JPS63224970A - Substrate for thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve thermal isolation between dots by permitting about 60-95 weight percent of porous glass powder to be added to a glazed layer and thereby enabling printing with insignificant power supply and allowing a thin glazed layer to sufficiently meet printing requirements when it is performed with the same power supply. CONSTITUTION:A glass paste layer containing about 60-95 weight percent of porous glass powder is formed on a ceramic substrate (alumina substrate) 11. Next, a thermal head substrate with a glazed layer 12 containing about 60-95 weight percent of glass powder 13 formed on the alumina substrate with the capability of generating high-temperature heat at insignificant power supply application is obtained by baking the ceramic substrate 11. If the substrate for a thermal head manufactured in the above-mentioned manner is used, printing can be performed with an insignificant power supply, and even a thin glazed layer 12 may meet printing requirements with the same power supply, thus realizing satisfactory heat isolation between dots and reducing lingering adverse thermal effect.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a substrate for a thermal head and a method thereof.

[Conventional technology]

As shown in FIG. 2, an example of a conventional substrate for a thermal head is one in which a glaze layer is provided as a heat insulating layer 2 on an alumina ceramic substrate 1, and the heat insulating layer is made of glass.

[Problems that the invention attempts to solve]

However, recently there has been a demand for thermal heads to have the ability to print with higher precision, faster speeds, and with less power. There was a limit due to the problem.

That is, in order to reduce the power, it is necessary to make the heat insulating layer 2 thicker, but if this is done, the temperature will not decrease sufficiently quickly when the power to the heat generating section is turned off. Thermal separation also worsens. On the other hand, if the heat insulating layer 2 is made thinner, high-speed printing becomes possible, but printing requires a large amount of power.

In order to solve these problems, we need a thermal head structure that stores enough heat on the board when the heat-generating part is energized, and that when the heat is turned off, the heat is absorbed quickly enough. Become.

In order to solve this problem,
As disclosed in the publication, a substrate to which porous glass is bonded has been devised, but it has drawbacks such as the inability to make the glass layer thin and the manufacturing difficulties leading to high costs.

An object of the present invention is to eliminate the drawbacks of the conventional thermal head substrates described above, and to provide a thermal head substrate with excellent heat retention and good thermal isolation.

[Means for solving problems]

The thermal head substrate of the present invention has a glaze layer of approximately 60%
It is characterized by containing ~95 wt% of porous glass powder as a main component. The method of manufacturing a substrate for a thermal head according to the present invention is characterized by forming a layer of glass paste containing about 60 to 95 wt% of porous glass powder on a ceramic substrate and firing the layer.

[Effect]

Thermal head substrates with a glaze layer as described above enable printing with less power, and with the same power, a thinner glaze layer is required compared to conventional methods, resulting in better thermal isolation between dots and less heat. Reduces trailing. That is, the temperature decreases quickly when the applied power is turned off.

〔Example〕

FIG. 1 is a sectional view showing a thermal head substrate according to an embodiment of the present invention. This thermal head substrate includes a glaze layer 1 containing porous glass powder 13 on an alumina substrate 11.
Frit glass is present as a binder between the particles of the glaze layer 12 and to bond the glaze layer 12 and the substrate 11 together.

The raw material porous glass used in the following description of an example of the manufacturing method for this substrate had a pore size of 1100 nm, and was crushed and sieved to an average particle size of 0.5 μm.

Although the average particle size may be about 1.0 μm, it is preferably about 1.0 μm or less in order to obtain a smooth surface. Further, it is desirable to use a material having an average pore diameter of 4Q nm to 200 nm, which can be stably manufactured at present.

To this porous glass powder, 3 to 50 wt % of frit glass (Kohling Co., Ltd., 7063) powder having a softening point of 635° C. was similarly ground to give an average particle size of 0.5 μm. A paste was prepared by adding methyl cellulose as an organic binder and terpineol as a solvent. Next, this was applied onto an alumina substrate by a thick film printing method, dried, and fired at 680° C. to produce a substrate.

The softening point of the glass powder as the binder glass added here needs to be below the heat resistance temperature of the porous glass.
In addition, due to the characteristics required for a thermal head substrate,
It is desirable that the temperature is above ℃. Further, it is desirable that this glass powder also has a particle size of about 1 μm or less.

In addition, the organic binder added here is not limited to the above-mentioned methylcellulose, but also polyethylene glycol, etc.
Any solvent suitable for making a paste may be selected, and an appropriate solvent such as a fatty acid ester may be selected accordingly. Coating methods for this paste include thick film printing,
A suitable method can be selected, such as a method using a bar coater, a spray coating method, or a dip coating method. The firing temperature may be higher than the softening point of the binder glass and lower than the heat resistance point of the porous glass under appropriate conditions.

As an example, each binder glass is 3°5.1
A substrate was made using a material containing 0, 20, 30, 40, 5 Qwt% and the remainder being porous glass, but when 3wt% of binder glass was added, the adhesion of the porous glass powder layer was insufficient. Therefore, it was not good as a substrate for a thermal head, but the adhesion was good at 5 wt% or more. Furthermore, as the amount added increased, the surface of the glaze layer became smoother. Next, in order to compare the performance of the thermal head substrate produced in this example with the performance of a conventional substrate, the substrate with a glaze layer containing 5wt% to 5Qwt% of binder glass of this example and the substrate for comparison. A thermal head was constructed using each of the glazed alumina substrates manufactured by Nippon Tokushu Dogyo Co., Ltd., and the relationship between the applied power and the peak humidity of the heating element was measured. The results are shown in FIG. The glaze layer thickness of all the substrates used was 40
μm, and the heating element V size of the thermal head is 50X7
It was made into a rectangular shape of 5 μm. Further, the peak temperature was determined by measuring the peak temperature at the center of the heating element using an infrared thermometer when this thermal head was driven with a pulse having a pulse width of 0.8 mS and a repetition period of 5 ms. As can be seen from the results, the thermal head using the substrate of the present invention has a
It is possible to generate high temperatures with less applied power.

However, as the amount of frit glass added increases, the effect decreases, and when the addition amount is 50 wt %, the difference from the conventional substrate becomes very small.

From this, the amount of frit glass to add is 5~4Qw
It was found that the porous glass powder is preferably contained in the glaze layer in an amount of 60 to 95 wt%.

〔Effect of the invention〕

If the thermal head substrate of the present invention is used in this way,
It is possible to configure a thermal head that can print with less power than conventional substrates, and if the same power is used for printing, a thinner glaze layer is required than in the past, resulting in better thermal isolation between dots. As a result, thermal tailing is reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a thermal head substrate according to an embodiment of the present invention, FIG. 2 is a sectional view showing a conventional thermal head substrate, and FIG. 3 is a diagram showing the relationship between applied power and peak temperature. be. 11... Alumina substrate, 12... Glaze layer 13.
...Porous glass powder. Embodiment 1 g Figure 2 of a conventional example

Claims (1)

[Claims] 1. A thermal head comprising a substrate and a glaze layer formed on the substrate, the glaze layer containing about 60 to 95 wt% porous glass powder. substrate. 2. The substrate for a thermal head according to claim 1, wherein the porous glass powder has an average particle size of about 1 μm or less. 3. The porous glass powder has an average pore diameter of about 40 to 20
The thermal head substrate according to claim 1, wherein the thermal head substrate has a thickness of 0 nm. 4. A method for manufacturing a substrate for a thermal head, which comprises forming a layer of glass paste containing about 60 to 95 wt% of porous glass powder on a ceramic substrate and firing the layer. 5. The method according to claim 4, wherein the porous glass powder has an average particle size of about 1 μm or less. 6. The above porous glass powder has an average pore diameter of about 40 to 20
5. The method according to claim 4, wherein the particle size is 0 nm. 7. Claims characterized in that the glass paste includes frit glass, and the firing temperature is below the maximum heat resistance temperature of the porous glass and above the softening point of the frit glass in the glass paste. The method described in Section 4.