JPS6319270A - Thermal head and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a substrate provided with a heat-accumulating layer having a high heat-accumulating property and a smooth surface, by providing a porous insulator layer on a substrate formed of a metal, a ceramic or the like, heating a surface part of the insulator layer for a short time to render only the surface part non-porous and smooth, and providing an electrode layer, a heat generating resistor layer and a surface protective layer on the non-porous layer thus obtained. CONSTITUTION:A heat-accumulating layer comprises an insulating layer 2 provided on a substrate 1 formed of a metal, a ceramic or the like, and an electrode layer 3, a resistor layer 4 and a surface protective layer 5 which are provided on the insulating layer 2. The insulating layer 2 comprises a porous layer 2a near the substrate 1 and a non-porous dense layer 2b at a surface part of the layer 2. The insulating layer 2 is formed of a glass, a glass ceramic, a crystallized glass or the like. To provide the insulating layer, a substrate 17 provided with a porous insulating layer 16 prepared beforehand is placed on a substrate support 14, a vacuum is drawn in a vacuum chamber 10, and the temperature of a heater 13 is raised to a desired temperature through heating electrodes 11, 12. After energization, the substrate is horizontally moved at a fixed velocity by a support-driving mechanism 15 to sequentially heat uniformly the surface of the substrate 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal head used in a printer and a method for manufacturing the same, and more particularly to a compact thermal head with high thermal efficiency.

A conventional thermal head has a resistance heating element on an insulating substrate, and two types, thin film and thick film, have been developed as shown in FIGS. 5a and 5b.

FIG. 5a shows a thin film type, which consists of a glass glaze layer 51 on an alumina substrate 50, a resistor film 52 such as 5iTa on this layer, an electrode film 53 such as Cτ-Cu, and an oxidized film made of SiO2. Prevention film 54, crucible wear film 5 made of SiC, etc.
5, and all of them are formed by methods such as sputtering and vapor deposition. On the other hand, the thick film type is shown in FIG.
Heat generating resistor layer 63 made of 2RuO2/glass, S z
It is composed of a surface protective layer 64 made of O2, and both are formed by printing and firing a paste material. In addition to these two types, thick-film and thin-film combination types have also been devised.

By the way, in a thermal head, electricity is applied to a heating resistor through an electrode, and energy of 0.1 to 1 W is applied per dot, thereby causing the resistor to generate heat. This heat generation response and two-handed energy efficiency require high speed and high heat generation efficiency, but for this purpose, as described in FIGS. Efforts have been made to provide a glass glaze layer 51, 61 as a heat storage layer between the heating element and the heating element 51, 63 to increase the rate of temperature rise of the heating element as much as possible. Figure 6 shows the relationship between the thickness of a general alkali-free glass glaze layer and the rising speed.If the thickness of this layer is between 0 and 100 μm, a thick layer should be used. It can be seen that the heat storage effect becomes more pronounced as the temperature increases.

Thus, the glass glaze layer is required to have low thermal conductivity. On the other hand, the heating elements formed on the surface of this glaze layer need to have a resolution of 4 to 16 pieces/piece, and the surface of the glaze layer is also required to be smooth. Crystallized glass has low thermal conductivity, but if the degree of crystallization progresses too much, the surface smoothness will be lost. Until now, K, surface smoothness Ra (0,2
For the glaze layer with μm, its thermal conductivity is 0.7W
/mK is the minimum, and no glaze layer with a smooth surface has been obtained having a thermal conductivity lower than this value.

Thermal heads are becoming faster and more efficient year by year, and there is a need to develop substrates with even higher performance heat storage layers.

Problems to be Solved by the Invention In view of the above-mentioned circumstances, the present invention seeks to develop a substrate having a heat storage layer with a smooth surface and a higher heat storage ability, and which is capable of handling higher heat than before. The aim is to create a thermal head that is efficient and compatible with high-speed printing.

Means for Solving the Problems The present invention provides a porous insulator layer on a substrate such as metal or ceramic, and this layer on the porous insulator layer is integrated with the porous insulator layer,
The thermal head is composed of an insulating layer having a lower porosity than this layer, and a surface protective layer of the electrode 1 and heating resistor 2 facing each other on the insulating layer.

Furthermore, the present invention involves forming a porous insulating layer on a substrate such as metal or ceramic, and heating the surface of the porous insulating layer using radiant energy for a short period of time to a point close to the softening point or melting point of this layer. Then, only the surface portion is made non-porous and smooth, and then the electrode layer 2 heat-generating resistive layer is formed on this non-porous layer by a thick film printing method, vapor deposition, sputtering method, or the like.

This is the manufacturability of a thermal head characterized by forming a surface protective layer.

According to the present invention, a substrate is used which has a double layer of a non-porous insulating layer with a smooth and dense surface and a porous insulating layer below this layer on a base material such as metal or ceramic. Due to the air layer in this porous layer, the thermal conductivity of the insulating layer is significantly reduced, and the heat storage capacity of the heat generating resistor is increased. In addition, the surface of this insulating layer is smoothed by the surface heating method of the present invention, and in order to achieve Ra (0.2txo), a heating resistor layer and an electrode layer are formed thereon at a resolution of 6 to 16 lines/layer. It becomes possible to do so.

As described above, the surface smoothness of the substrate used in the thermal head of the present invention is close to that of a conventional glass glaze layer, and due to the low thermal conductivity caused by the porosity of this layer, a fine pattern can be formed on this substrate. To provide a thermal head which can be formed and has excellent heat generation efficiency.

EXAMPLES An overview and specific examples of the substrate used in the thermal head of the present invention and its manufacturing method will be explained with reference to the drawings. FIG. 1 is a diagram showing the basic configuration of the thermal head of the present invention. An insulating layer 2 on a substrate 1 such as metal or ceramic
and an electrode layer 3, a resistance layer 4, and a surface protection layer 5 on this layer. Among these, the insulating layer 2 is a porous layer 2a near the base 1, and the surface part is a non-porous dense layer 2b.
It has become.

The material of this insulating layer 2 is glass, glass ceramic, crystallized glass, etc., but in order to form this layer to have two layers as in the present invention, a porous insulating layer is first formed on the substrate. Then, only the surface portion of this insulating layer is heated for a short time at a temperature close to its softening point. The most effective method for this heating is radiant energy. FIG. 2 is an example of the apparatus for heating and melting the surface of a substrate according to the present invention. That is,
A device consisting of heating electrodes 11 and 12 in a vacuum chamber 10, a heater 13, a substrate pedestal 14, and a pedestal drive mechanism 15,
A substrate 1 having a previously prepared porous insulating layer 16 is placed on the substrate pedestal 14. After evacuating the vacuum chamber 10,
Electricity is applied to the heater 13 through the heating electrodes 11 and 12 to raise the temperature of the heater 13 to a desired temperature. This temperature is
Measurements are made using a pyrometer 19 through the viewing port 18. The heater 13 used here is made of graphite.

It is made of SiC, Ta, W, 'Mo, etc. into a rod or plate shape, and is kept at a distance of 0.1 to 10 mm from the substrate 17.

After energization, the substrate is moved horizontally at a constant speed by the gantry drive mechanism 16, and the surface of the substrate 17 is sequentially and uniformly heated. Specifically, the lower part of the graphite heater 2o with a diameter of 1 state is connected to the substrate in 1 state/
Move at the speed of crossing. In FIG. 2, numeral 21 indicates an arrow leading to the vacuum evacuation system. Also, due to the relative heat capacity relationship between the substrate and the heater, the preheating mechanism 25 is attached to the substrate mount 14.
It is also effective to provide a heater 13 and effectively utilize the radiant energy of the heater 13.

When an insulating layer such as glass is heated to its softening temperature or melting temperature, it softens and melts, and the porous layer becomes dense and the surface becomes smooth. If you try to soften and melt the porous insulating layer used in the present invention by placing the substrate in a normal melting furnace, the surface of the insulating layer will become smooth, but the entire depth of the insulating layer will become dense. In this case, no porous heat storage layer remains and the substrate having the structure of the present invention cannot be obtained. In addition, since stainless steel plates, alumina ceramic plates, etc. are used for the substrate, if these substrates are heated to the softening point or melting temperature of the surface insulating layer, the substrate itself may be transformed and destroyed, making it difficult to actually use it as a substrate. becomes difficult.

FIG. 3 is a schematic enlarged view of the insulating layer ((2) in FIG. 1) of the substrate of the present invention and the manufacturing process thereof.

That is, the porous insulating layer 3o obtained by the action of a foaming agent such as MqCo3 has a large surface roughness on its surface 31, and many air bubbles are present in the layer. When the apparatus shown in FIG. 2 is used, only the surface portion becomes dense and smooth, resulting in a porous insulating layer 301 divided into a surface layer 311 and a porous layer 312. The surface layer 3111 is smooth with Ra (0.2 μm, so 16
The wiring of this / chicken is now possible, and the porous layer 3 below this
Since the thermal conductivity of the porous layer 312 is significantly reduced by the action of the 12 air bubbles 313, high-speed printing and high energy efficiency as a thermal head are achieved.

Next, specific examples of the present invention will be described.

[Example 1] A glass frit having a composition of SiO2, B2o32MqO and MqCO3 are pulverized and mixed, and then classified into particle sizes of 10 μm to 30 μm. This was dispersed in isopropyl alcohol and a trace amount of water was added. Using the obtained slurry, an electrodeposition layer of the frit and MqCO3 is formed on a stainless steel plate by an electrodeposition method. A porous hollow layer is formed on the stainless steel plate by firing at 900°C (thickness 1.
5 μm, porosity 50%).

Subsequently, the surface of this hollow layer is heated using the apparatus shown in FIG. A graphite rod was used as the heater, and the temperature was raised to 91,400°C using a thermometer, and the distance between the heater hollow surface was 1.
0 fence. The moving speed of the substrate was 1 w/SeC, and the degree of vacuum in the room was 1 O-6 Torr.

On the substrate thus obtained, a gold electrode layer 40, a RuO2/glass resistance layer 41°, and a glass surface protective layer 42 were formed by thick film printing to form a thermal head (12/-) (Fig. 4). . 43 is a stainless steel plate, 44 is a porous hollow layer, and 45 is a smooth hollow layer on the surface of this layer.

[Example 2] Example-
A glass frit having the composition No. 1 is printed and fired at 900°C. Heating the surface of the glass layer in the same manner as in Example-1,
Furthermore, the same electrode as in Example-1.

[Comparative Example 1] After obtaining the porous glass layer in Example-1, electrode layers and the like were directly formed without going through the surface heating process. 2] A thermal head using a conventional hollow substrate with a surface roughness of 0.1.

[Comparative Example 3] A thermal head using a conventional glazed alumina ceramic substrate with a surface roughness of 0.05.

A comparison of the characteristics of the thermal head and the substrate described above is shown in the table below. Effects of the Invention As described above, the thermal head of the present invention uses a substrate with an integrated double layer structure that has a smooth surface and a porous layer inside. Therefore, it has high resolution and excellent heat storage properties, and has high performance that can meet the demands for high speed printing and high thermal efficiency.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional configuration diagram of a thermal head according to an embodiment of the present invention, Fig. 2 is a configuration diagram of a manufacturing apparatus for a substrate used in the thermal head, and Fig. 3 is a content of an insulating layer of a substrate used in the thermal head. FIG. 4 is a cross-sectional configuration diagram of a thermal head according to another embodiment of the present invention, FIG. 5 is a cross-sectional configuration diagram of a conventional thermal head, and FIG. 6 is a glass glaze layer of the same thermal head. FIG. 3 is a diagram showing the relationship between the thickness of the resistor and the resistance temperature rise performance. 1...Base body, 2...Insulating layer, 2a...
...Porous layer, 2b...Non-porous layer, 3.
...Electrode layer, 4...Resistance layer, 6...
...Surface protective layer. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 2 Figure 3, 71/ Figure 5 Figure 6 Time (msec)

Claims (6)

[Claims] (1) A porous insulator layer on a substrate such as metal or ceramic, and a second insulator layer formed on the porous insulator layer and made of a material with lower porosity than the porous insulator layer. ,
A thermal head comprising opposing electrodes and a heating resistor formed on the second insulating layer, and a surface protective layer covering the surface of the forming layer. (2) The porous insulating layer and the insulating layer with low porosity are made of glass, crystallized glass, glass ceramic, etc. whose composition is at least one of B, Si, P, and Pb and an alkaline earth metal element. A thermal head according to claim 1, characterized in that the thermal head comprises: (3) The surface roughness Ra of the insulating layer with low porosity is 0.2 μm
The thermal head according to claim 1, characterized in that: (4) A porous insulating layer is formed on a substrate such as metal or ceramic, and the surface of this porous insulating layer is heated for a short time using radiant energy to the softening point or close to the melting point of this layer. The non-porous layer is smoothed to make it more non-porous, and then an electrode layer, a heating resistor layer, and a surface protective layer are formed on the non-porous layer by a thick film printing method or a vapor deposition/sputtering method. Thermal head manufacturing method. (5) Claims characterized in that the porous insulating layer is formed by supporting a mixture of glass frit, metal carbonate, organic foam material, fly mash, etc. on a substrate and firing it. 4. The method for manufacturing a thermal head according to item 4. (6) Heating by radiant energy in vacuum, inert gas, or air, carbon, SiC, SiMo,
5. The method of manufacturing a thermal head according to claim 4, wherein the porous layer is heated by heating one of the heaters made of Ta, and the porous layer is scanned and heated.