JPH06320773A - Thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a thermal head having high performance and reliability by a method wherein characteristics, such as low heat conductivity and low heat capacity which are possessed by a heat-insulating layer consisting of a porous layer, are utilized effectively and a trouble due to the existence of numberless holes on the surface of the porous layer is eliminated. CONSTITUTION:In a thermal head, in which a heat-insulating layer (porous layer) 7 having pores is formed on a supporting substrate 1, a hole sealing layer 8 for sealing the pores is formed on the surface of the heat-insulating layer 7 while air in the pores is enclosed by the hole sealing layer 8 whereby the oxidization of heating resistors 3 and the like due to air in the pores can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used in a recording section of a facsimile machine, a printer machine, a copying machine or the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 6 is a vertical sectional view showing a conventional thermal head. In the figure, 201 is a support substrate formed of alumina having a relatively high thermal conductivity, and a heat insulating layer 202 made of glass having a relatively low thermal conductivity is formed in a convex shape on the support substrate 201. Has been done.

The heating resistor 2 is formed on the heat insulation layer 202.
03 and a pair of electrodes 204a and 204b respectively connected to the heating resistor 203. Protective layers 205 and 206 are formed on the heating resistor 203 and the electrodes 204a and 204b to prevent oxidation of the heating resistor 203 and to prevent abrasion due to contact with a thermal paper or an ink sheet. Has been done.

The heating resistor 203 is formed in a line in the direction perpendicular to the plane of the drawing, and the pair of electrodes 204a, 204a,
b are alternately arranged at a predetermined interval in the direction perpendicular to the plane of the drawing, whereby the heating resistor line is formed.

When recording is performed by using the thermal paper or the ink sheet with the thermal head having the above-mentioned structure, the thermal paper or the ink sheet is pressed against the front surface where the heating resistor 203 is located by a platen roller or the like. Electrode 2
Power is applied to the portion of the heating resistor 203 that is desired to generate heat via 04a and 204b. As a result, the heat-generating resistor 203 in the energized portion generates heat, and the heat-sensitive paper causes the heat-sensitive paper to develop color, or the ink of the ink sheet adheres to the recording paper to perform recording.

In the above conventional thermal head, the heating resistor 203 is formed of a thin film,
In order to improve the transfer efficiency, the heat retaining layer 202 on which the heating resistor 203 is located is shown to be convex. However, as shown in FIG. 7, when the heating resistor 203 is a thick film, the Since the heating element portion has a convex shape depending on the thickness, the heat insulating layer 2
There is also one in which 02 is formed flat.

By the way, in a thermal recording apparatus using such a thermal head, there is a demand for high-speed printing and low power consumption. To meet this demand, heat generation efficiency and thermal responsiveness of the thermal head are demanded. Both need to be improved.

In order to improve the above-mentioned heat generation efficiency, it is necessary that the heat of the heat generating resistor 203 is efficiently conducted to the thermal paper or the ink sheet side and the heat is not so much conducted to the opposite side. is there.

On the other hand, in order to improve the thermal responsiveness, it is necessary to increase the thermal efficiency and increase the rate of temperature rise, reduce the amount of heat stored in the vicinity of the heating resistor, and shorten the cooling time. It is necessary to reduce the heat capacity of the layer.

Here, if the above-mentioned heat retaining layer is made thicker, the heat escape is reduced, but the heat storage amount becomes large. Therefore, it is desirable to use a material having a small thermal conductivity and a small heat capacity for the heat retaining layer. For this reason, for example,
As disclosed in Japanese Patent Publication No. 18834 or Japanese Patent Publication No. 4-60025, a method of using a thin film of a resin such as polyimide having small thermal conductivity and heat resistance as a heat insulating layer, or containing air inside Has proposed a method using a porous glass that can significantly reduce the apparent thermal conductivity and heat capacity.

[0011]

However, the above polyimide resin is not sufficient in heat resistance, and the porous glass has the one using the phase separation method, the one obtained by sintering particles, and the hollow filler. It is known to use a foaming agent, a foaming agent, a spraying agent, or a sol-gel method, but each has the following drawbacks.

The phase separation method is a method in which a phase insoluble in acid and a phase soluble in acid are separated and then the phase soluble in acid is eluted to obtain a porous material. This phase separation method requires a high temperature for phase separation, and the residue of acid may erode the resistor and the electrode.

The method of sintering particles, using a hollow filler, a foaming agent, and spraying has a drawback in that the surface of the heat retaining layer is hard to be smooth, which deteriorates the printing quality.

The sol-gel method is a method for producing a glass oxide by subjecting a gel obtained by hydrolyzing a metal alkoxide to heat dehydration condensation. Several Å to several 1 in this manufacturing process
A dry porous gel having a uniform surface with fine pores such as 00Å and having a smooth surface is obtained, and if the final sintering is interrupted at an appropriate time, a porous oxide glass can be obtained. The sol-gel method generally has the advantage that the oxide glass can be produced at a lower temperature than the conventional melting method. However, when a heating resistor or an electrode is formed on the heat insulating layer of porous glass formed by this sol-gel method, the air existing inside the numerous holes existing on the surface of the heat insulating layer causes When the heat-generating resistor generates heat, it is oxidized to cause a change in resistance value, which has a drawback that print quality is deteriorated.

In view of the above circumstances, the present invention makes use of the characteristics such as low thermal conductivity and low heat capacity of the heat insulating layer made of a porous material layer, and that the surface of the porous material layer has innumerable pores. An object of the present invention is to provide a thermal head having high performance and high reliability by eliminating problems caused by it.

[0016]

In order to solve the above-mentioned problems, the thermal head of the present invention is a thermal head in which a porous body layer having fine holes is formed on a support substrate. It is characterized in that a sealing layer for sealing the fine pores is formed on the surface of the layer.

The method of manufacturing the thermal head of the present invention is characterized by including a step of forming a sealing layer by sputtering an insulating material on the surface of the porous body layer in a vacuum atmosphere.

The thermal head manufacturing method of the present invention comprises a step of forming a dry porous gel layer on a support substrate, a step of sintering the dry porous gel layer, and a step of forming this by sintering. And a step of applying boiling water or steam to the surface of the porous body layer to form a sealing layer on the surface of the porous body layer.

[0019]

According to the above-mentioned thermal head, the porous layer has the sealing layer formed on the surface thereof, and the air in the fine pores is confined in the pores by the sealing layer. Can be prevented from being oxidized by the air in the fine pores. Further, the sealing layer makes the surface of the porous body layer smooth and improves the printing quality.

Further, according to the first manufacturing method described above, since the pore-sealing layer is formed in a vacuum atmosphere, the inside of the fine pores sealed by the pore-sealing layer is in a vacuum, The thermal conductivity is further lower than that of the porous body layer in which air is present in the fine pores, and a thermal head having high thermal efficiency can be provided.

Further, according to the above second manufacturing method, the sealing layer formed on the surface of the porous body layer is formed by applying boiling water or steam, and the first manufacturing method described above. Since a sputtering process is not required unlike the method, the process can be simplified and the manufacturing time can be shortened.

[0022]

【Example】

(Embodiment 1) The present invention will be described below with reference to the drawings showing the embodiment.

FIG. 1 is a vertical sectional view of a thermal head according to the present invention. In the figure, 1 is a support substrate, and this support substrate 1 is made of a ceramic such as alumina having a relatively high thermal conductivity. A heat insulating layer 7 made of porous glass having innumerable fine pores is formed on the support substrate 1,
The sealing layer 8 is formed on the surface.

On the sealing layer 8, a thick film heating resistor 3 and a pair of electrodes 4 connected to the heating resistor 3, respectively.
a and 4b are formed. Then, on the heating resistor 3 and the electrodes 4a and 4b, an antioxidation layer 5 for preventing oxidation of the heating resistor 3 and a resistance for preventing abrasion due to contact with a thermal paper or an ink sheet. Wear layer 6
Is coated.

The heating resistor 3 is formed in a line in the direction perpendicular to the paper surface, and the pair of electrodes 4a and 4b are alternately arranged at a predetermined interval in the direction perpendicular to the paper surface. Lines are formed.

According to the above construction, the sealing layer 8 is formed on the surface of the heat insulating layer 7, and the air in the fine pores is confined in the pores by the sealing layer 8, so that the heating resistor 3 is finely divided. It is possible to prevent oxidation by the air in the holes. In addition, the sealing layer 8 makes the surface of the heat retaining layer 7 smooth and improves the printing quality.

In the above embodiment, the thermal head in which the heat retaining layer 7 is made flat by using the thick film heating resistor 3 is shown. However, as shown in FIG. Even in a thermal head having a convex layer 7, by forming the sealing layer 8 on the convex heat insulating layer 7, it is possible to prevent the heating resistor 3 from being oxidized, as in the above-described embodiment.

Next, a method of manufacturing the thermal head will be described.

(First Manufacturing Method) When the heat insulating layer 7 made of a porous material layer is manufactured by the sol-gel method, first, a coating solution used in this sol-gel method is manufactured. In the present embodiment, silicon methoxide [S
i (OCH ₃ ) ₄ ]. The coating solution is produced by diluting the above Si (OCH ₃ ) ₄ with methanol, adding water and stirring the mixture to promote hydrolysis. That is, Si (OH) _x (OCH ₃ ) produced by this hydrolysis
_4-x repeats the dehydration condensation reaction to develop chain-like or three-dimensional siloxane bonds (Si-O-Si), and become a polymer solution.

Then, as shown in FIG. 3A, the coating solution 107 generated as described above and having an appropriate viscosity is coated on the support substrate 1 in a convex shape.

Next, as shown in FIG. 3B, the support substrate 1 is dried together, and the dehydration condensation reaction is further promoted to form a fine and relatively uniform porous gel 108 of several 10 Å. When the dehydration condensation is sufficiently performed, the shrinkage of the porous gel 108 hardly occurs.

Thereafter, as shown in FIG. 3C, the temperature is further raised to 500 to 600 ° C. to sinter the porous gel 108, vitrify it, and form a convex porous glass (porous material layer). ) 109 is obtained.

At this time, if the temperature is raised too high,
Since the fine pores of the porous glass 109 are eliminated by sintering, the temperature is controlled so that the temperature is at a level at which the required porosity is obtained.

After that, a cooling process is performed, but at this time, the temperature is slowly lowered so that there is no difference in contraction speed between the support substrate 1 and the porous glass 109. It is also important to select these materials so that the thermal expansion coefficients of the support substrate 1 and the porous glass are as equal as possible.

When the cooling process is completed, the porous glass 10
Apply boiling water or spray water vapor on the surface of 9.

As a result, as shown in FIG. 6D, the hydrolysis occurs again only on the surface of the porous glass 109, and the product at this time forms the pore-sealing layer 103, and the porous glass 109 has a porous layer. The fine holes are sealed.

After that, the heating resistor 3, the electrodes 4a and 4b, the oxidation protection layer 5, and the abrasion resistant layer 6 are formed by a known method.

According to the above manufacturing method, the sealing layer 103 (8) formed on the surface of the heat insulating layer 7 is formed by applying boiling water or steam, and the sealing layer is formed. Therefore, unlike the second manufacturing method described later, a sputtering step is not required, so that the steps are simplified and the manufacturing time can be shortened.

(Second Manufacturing Method) The second manufacturing method will be described below.

Similar to the first manufacturing method, FIG.
As shown in (c), a convex porous glass (porous layer) 109 to be the protective layer 7 is obtained on the support substrate 1.

Next, although not shown, an insulating material such as ceramics is sputtered on the surface of the heat insulating layer 7 in a vacuum atmosphere to form a sealing layer 8. After that, the heating resistor 3, the electrodes 4a and 4b, the antioxidation layer 5, and the abrasion resistant layer 6 are formed by a known method by sputtering or vapor deposition.

In the thermal head formed by the above method, the inside of the fine holes of the heat retaining layer 7 becomes a vacuum, and the thermal conductivity becomes much lower than that of the heat retaining layer in which air is present in the fine holes. The head can be manufactured.

(Embodiment 2) Another embodiment of the present invention will be described below.

As shown in FIG. 4, the thermal head of the present embodiment has a heat insulating layer 10 made of a heat resistant resin such as polyimide on a support substrate 1 made of a metal such as stainless steel. The heating resistor 3, the electrodes 4a and 4b, the oxidation preventing layer 5, and the abrasion resistant layer 6 are provided on the heat insulating layer 10.

On the other hand, a heat insulating layer 7'of porous glass is provided on the support substrate 1 on the back side, that is, on the side opposite to the side on which the heating resistors 3 and the like are formed. A sealing layer 8 made of a heat-resistant resin or the like having a low thermal conductivity such as polyimide is formed on the surface of the heat insulating layer 7'of the high quality glass by coating.

Here, in the thermal head, when a pulsed voltage is applied to the electrodes 4a and 4b at the time of recording, the heating resistor 3 in the portion between the electrodes generates heat, and the heat energy is generated by the antioxidation layer 5. Recording is performed by conducting to the recording medium through the abrasion resistant layer 6 and at this time, the generated thermal energy is also conducted to the heat retaining layer 10 side of the heat resistant resin, and the heat retaining layer 10 and It is also conducted to the heat insulating layer 7'side through the support substrate 1.

When a pulsed voltage is repeatedly applied to the electrodes 4a and 4b, the temperature of the support substrate 1 becomes high through the heat-resistant resin heat insulating layer 10, and heat from the back side of the support substrate 1 is absorbed. The escape increases and the thermal efficiency of the thermal head decreases. However, in the thermal head of the present embodiment, as described above, since the heat retaining layer 7'and the sealing layer 8 are formed on the back surface of the support substrate 1, the thermal energy generated in the heating resistor 3 is Of these, the amount of heat that escapes to the back side of the thermal head through the support substrate 1 decreases,
Since more heat is transmitted to the recording surface side, the thermal efficiency of the thermal head is improved.

As shown in FIG. 5, in order to prevent the support substrate 1 and the like from becoming excessively high in temperature and to improve the strength of the thermal head, heat radiation of aluminum or the like is provided on the back surface side of the support substrate 1. There is a thermal head having a structure in which the plate 9 is provided. Even in the thermal head having such a structure, even if the heat retaining layer 7 ′ and the sealing layer 8 are formed between the heat dissipation plate 9 and the support substrate 1. Good. With this configuration,
It is possible to further improve the heat retaining property by the heat retaining layer 7 ', and at the same time, it is possible to prevent the excessive temperature of the support substrate 1 and the like.

[0049]

As described above, according to the present invention, since the sealing layer is formed on the printing side surface of the porous body layer, the printing quality is improved by the smoothing of the surface and the heating resistor is oxidized. The reliability can be improved by prevention, and the thermal conductivity of the heat insulating layer can be further reduced. Further, according to the method of forming the sealing layer by sputtering, the inside of the fine pores can be evacuated, whereby the thermal conductivity of the porous body layer can be further reduced. Furthermore, the formation of the sealing layer by applying water vapor or boiling water eliminates the need for the sputtering step, and has the effect of simplifying the step.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a thermal head of the present invention.

FIG. 2 is a vertical cross-sectional view showing a thermal head having a heat insulating layer of the present invention formed in a convex shape.

FIG. 3 is a vertical cross-sectional view showing, in the order of steps, steps up to forming a dry porous gel layer on a support substrate in the method of manufacturing the thermal head of FIG.

FIG. 4 is a vertical cross-sectional view showing a thermal head having a protective layer and a sealing layer of the present invention formed on the back side of a support substrate.

FIG. 5 is a vertical cross-sectional view showing a thermal head in which a protective layer and a sealing layer of the present invention are formed on the back side of a support substrate and a heat dissipation plate is formed.

FIG. 6 is a vertical sectional view showing a conventional thermal head.

FIG. 7 is a vertical cross-sectional view showing another conventional thermal head.

[Explanation of symbols]

 1 Support Substrate 3 Heating Resistor 5 Antioxidant Layer 6 Abrasion Resistant Layer 7 Heat Retaining Layer (Porous Body Layer) 8 Sealing Layer

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art FIG. 6 is a vertical sectional view showing a conventional partial glaze type thermal head. In the figure, 201 is a support substrate formed of alumina having a relatively high thermal conductivity, and a heat insulating layer 202 made of glass having a relatively low thermal conductivity is formed in a convex shape on the support substrate 201. Has been done.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

The heating resistor 203 and the pair of electrodes 204a, 204b are arranged at a predetermined interval in the direction perpendicular to the plane of the drawing, whereby a heating resistor line is formed.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

In the above-mentioned conventional thermal head, the heat retaining layer 202 on which the heating resistor 203 is located has a convex shape in order to improve the transfer efficiency. However, as shown in FIG. There is also an all-glaze type thermal head in which the heat retaining layer 202 is formed flat.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

However, the above polyimide resin is not sufficient in heat resistance, and the porous glass has the one using the phase separation method, the one obtained by sintering particles, and the hollow filler. It is known to use a foaming agent or a sol-gel method, but they have the following drawbacks.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

The method of sintering particles or using a hollow filler or a foaming agent has a drawback that the surface of the heat retaining layer is hard to be smooth, which deteriorates the printing quality.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

The sol-gel method is a method of producing glass by hydrolyzing and condensing a gel obtained by hydrolyzing a metal alkoxide. Several Å to several hundred in this manufacturing process
A dry porous gel having a uniform surface with fine pores such as Å and having a smooth surface can be obtained. If the final sintering is interrupted at an appropriate point, a porous glass can be obtained. The sol-gel method generally has the advantage that glass can be produced at a lower temperature than the conventional melting method. However, when a heating resistor or an electrode is formed on the heat insulating layer of porous glass formed by this sol-gel method, the air existing inside the numerous holes existing on the surface of the heat insulating layer causes When the heat-generating resistor generates heat, it is oxidized to cause a change in resistance value, which has a drawback that print quality is deteriorated.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

A thin film heating resistor 3 and a pair of electrodes 4 connected to the heating resistor 3 are formed on the sealing layer 8.
a and 4b are formed. Then, on the heating resistor 3 and the electrodes 4a and 4b, an antioxidation layer 5 for preventing oxidation of the heating resistor 3 and a resistance for preventing abrasion due to contact with a thermal paper or an ink sheet. Wear layer 6
Is coated.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

The heating resistor 3 and the pair of electrodes 4
a and 4b are arranged at a predetermined interval in the direction perpendicular to the plane of the drawing, and thereby a heating resistor line is formed.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

In the above-mentioned embodiment, the whole-glaze type thermal head is shown. However, as shown in FIG. 2, the convex heat insulating layer 7 and the sealing layer 8 are provided immediately below the heat generating portion of the heat generating resistor 3. Even in the formed partial glaze type thermal head, it is possible to prevent the heating resistor 3 from being oxidized, as in the above embodiment.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Then, as shown in FIG. 3A, the coating solution 107 generated as described above and having an appropriate viscosity is coated on the support substrate 101 in a convex shape.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

Next, as shown in FIG. 6B, the support substrate 101 is dried together, and the dehydration condensation reaction is further promoted.
A porous gel 108 having fine and relatively uniform pores of Å is formed. When the dehydration condensation is sufficiently performed, the porous gel 1
Almost no 08 contraction occurs.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

After that, a cooling process is performed, but at this time, the temperature is slowly lowered so that there is no difference in contraction speed between the support substrate 101 and the porous glass 109. It is also important to select these materials so that the thermal expansion coefficients of the support substrate 101 and the porous glass are as equal as possible.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

After that, according to a known method, as shown in FIGS.
The heating resistor 3, the electrodes 4a and 4b, the oxidation protection layer 5, and the abrasion resistant layer 6 are formed as shown in FIG.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

According to the above-mentioned manufacturing method, the sealing layer 8 formed on the surface of the heat insulating layer 7 is formed by applying boiling water or steam, and the formation of this sealing layer will be described later. As in the second manufacturing method described above, the step of sputtering is required, which is simplified and the manufacturing time can be shortened.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

Similar to the first manufacturing method, FIG.
As shown in (c), a convex porous glass (porous body layer) 109 which will become the heat retaining layer 7 is obtained on the support substrate 101.

Front Page Continuation (72) Inventor Satoshi Kuwahara 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A thermal head in which a porous body layer having fine pores is formed on a support substrate, and a sealing layer for sealing the fine pores is formed on the surface of the porous body layer. The thermal head. 2. A method of manufacturing a thermal head, comprising the step of forming a sealing layer by sputtering an insulating material on the surface of a porous body layer in a vacuum atmosphere. 3. A step of forming a dry porous gel layer on a support substrate, and a step of sintering the dry porous gel layer.
And a step of applying boiling water or steam to the surface of the porous body layer formed by this sintering to form a sealing layer on the surface of the porous body layer. .