JPH0584222B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head in which a heating resistor is formed in the direction of the end surface of a substrate.

[Conventional technology]

Conventionally, a thermal head in which a heat generating resistor is formed at the edge of a substrate has been developed by the present applicant in Japanese Patent Application No.
There is a device that has already been filed as No. 213116.
FIG. 5 is a block diagram showing an outline of this thermal head. The thermal head shown in the figure has a first electrode layer 2, a glass layer 3 serving as an electrical insulating layer and a heat resistance layer, a second electrode layer 4, and a protective glass layer 5 stacked one after another on one surface of a substrate 1. Along with forming;
Each layer including the substrate 1 is cut in a straight line, and a heating resistor layer 6 is formed on the exposed end surface of each electrode layer 2, 4. In addition, the heating resistor layer 6
are separated into a plurality of parts according to the shape of the first electrode layer 2 constituting the selection electrode.

In the thermal head formed in this manner, the heat generating resistor layer 6 (heat generating portion) comes into reliable contact with the recording paper, etc., so that a thermal head with good thermal efficiency can be obtained. In addition, since the edges of the substrate 1 are easier to process to be flat than the flat parts,
A plurality of heat generating parts can be brought into even contact with recording paper, etc., and high printing quality can be obtained. Furthermore, since the length of the heat generating part in the heat generating resistor layer 6 is determined by the thickness of the glass layer 3 formed between the electrode layers, the length of the heat generating part can be freely controlled by adjusting this thickness. , a high-resolution thermal head can be realized without affecting the strength of the substrate 1.

[Problem that the invention seeks to solve]

However, in such a thermal head, as the glass layer 3 formed between the first and second electrode layers 2 and 4, a high melting point glass fired at a temperature of 1200° C. or higher is used. For this reason, it is not possible to use metal materials with low melting points for the first electrode layer 2 formed under the glass layer 3, and common gold (Au), silver (Ag), copper ( Cu), aluminum (Al), etc. can no longer be used.

The present invention eliminates the above-mentioned drawbacks of the conventional device, improves the heat generation characteristics by forming the heat generating part on the glass layer, and provides a thermal head that does not require a high melting point material for the electrode material. The purpose is to realize this with a simple configuration.

[Means for solving problems]

The thermal head of the present invention has a glazed substrate in which a glass layer is fired on one side of the substrate portion and the thickness of the substrate portion is equal to or less than the thickness of the glass layer. 2
A heat generating resistor layer is formed on the end face where the first and second electrode layers are exposed by cutting or polishing the end face of the substrate including the respective layers, and at least the above electrode layer is formed in the heat generating resistor layer. The heating resistor layer portion located on the glass layer is divided into a plurality of parts depending on the number of electrodes of the first or second electrode layer.

[Effect]

In this way, by forming a heat generating resistor layer on the end face of the glazed substrate and separating it to form multiple heat generating parts, it is possible to form the heat generating parts only on the glass layer through a simple process. It is possible to improve the heat generation characteristics of the thermal head. In addition, since the first and second electrode layers are formed on the glass layer that has already been fired, they are not exposed to high temperatures after they are formed, and can be made of common metal materials with relatively low melting points. be able to.

〔Example〕

Hereinafter, the thermal head of the present invention will be explained using the drawings. In the figure, the same parts as in FIG. 5 are designated by the same reference numerals.

FIG. 1 is a block diagram showing an embodiment of the thermal head of the present invention. In the figure, 10 is a glazed substrate in which a glass layer 12 is baked on one side of a substrate portion 11 made of, for example, alumina. Note that the substrate portion 11 in the glazed substrate 10
For example, by spreading a liquid raw material thinly on a flat surface,
This is formed thinly by a manufacturing method such as drying and sintering, and the plate thickness is equal to or less than the thickness of the glass layer 12 (50 μm to 200 μm) (30 μm to 200 μm). It is.

First, in the glazed substrate 10, a first electrode layer 2, which becomes, for example, a selection electrode, is formed on the surface on the glass layer 12 side, and a second electrode layer 4, which becomes, for example, a common electrode, is formed on the other surface. be done. This first
The second electrode layers 2 and 4 are formed by printing and firing a thick film conductive paste of gold, silver palladium, platinum, copper, etc., and etching it into an arbitrary pattern. Note that fine patterns are processed by etching when obtaining an electrode density of 10 electrodes/mm or more, and when the density is relatively low,
It is also possible to directly form a desired electrode pattern by printing. Further, the film thickness of the first and second electrode layers 2 and 4 is generally about 3 to 5 μm.

A protective glass layer 5 is printed and fired on the first and second electrode layers 2, 4 in order to protect these electrode layers 2, 4. For example, thick film crystallized glass is used for this protective glass layer 5, and its melting point is relatively low. The protective glass layer 5 is provided to prevent the first and second electrode layers 2 and 4 from peeling off during cutting of the edge of the substrate as described below. Furthermore, it is also effective to add, for example, aluminum oxide (Al ₂ O ₈ ) powder to the protective glass layer 5 in consideration of wear resistance, thermal conductivity, and the like.

Next, the ends of the glazed substrate 10 to which the first and second electrode layers 2 and 4 are attached as described above are cut to form an end surface to which the heating resistor layer 6 is to be attached. . FIG. 2 shows the state of the end face. As shown in the figure, the first and second electrode layers 2 and 4 are exposed on the end face.
Note that if the surface roughness of the end face after cutting is lower than a predetermined standard, polishing or grinding is performed to finish the surface flat.

A resistive material such as tantalum nitride (Ta ₂ N) or nichrome (Ni-Cr) is deposited on the end face thus formed by sputtering or vapor deposition to form the heating resistor layer 6. The thickness of the heating resistor layer 6 in this case is determined in relation to its resistance value, and is approximately 0.1 μm.

Now, as described above, after the heat generating resistor layer 6 is formed on the end surface of the glazed substrate 10, at least the portion of the heat generating resistor layer 6 located on the glass layer 12 is covered with the first electrode layer. 2 shape (number of electrodes)
It is separated into a plurality of heat generating parts to correspond to the
Laser cutting, photolithography, etc. are used for this separation.

FIG. 3 is a sectional view showing the state of the heat generating section formed in this manner. Here, the heating resistor layer 6
is formed astride the substrate portion 11 and the glass layer 12, but since the thermal conductivity of the substrate portion 11 is about 10 times higher than that of the glass layer 12 and is thinner, the heating resistor layer 6, the surface temperature rises only in the portion substantially located on the glass layer 12 when electricity is applied. Therefore, a plurality of heat generating parts can be formed on the end surface of the glazed substrate 10 through a simple process. At this time, if the thickness of the substrate portion 11 is too thick, the amount of heat escaping from the substrate portion 11 will increase and the heat generation efficiency of the head will decrease. Equal or lower is desirable. In addition, in the figure, 7 is a protective and wear-resistant layer, and insulating layers such as silicon oxide (SiO ₂ ), tantalum pentoxide (Ta ₂ O ₅ ), boron nitride (BN), and silicon carbide (SiC) are sputtered or It is vapor deposited. Furthermore, in consideration of thermal conductivity, a wear-resistant metal layer may be applied by dispersion plating after insulating with silicon oxide or the like. In this case, nickel is mainly used for the metal film, and by adding aluminum oxide, boron nitride, diamond, etc. as a dispersant, thermal conductivity and wear resistance can be improved.

Further, FIG. 4 shows a state in which a reinforcing plate 8 such as an aluminum plate or a ceramic plate is bonded to the side surface of the glazed substrate 10. In this way, by bonding the reinforcing plate 8 to one or both sides of the glazed substrate 10, it is possible to supplement the mechanical strength of the thinly formed glazed substrate 10 (substrate portion 11) and to correct the warpage of the substrate. can.

The thermal head of the present invention is formed through the steps described above, and in such a thermal head, the heating portion of the heating resistor layer 6 is connected to the glass layer 1.
Since it is located above 2, it provides adequate heat retention,
Good heat generation characteristics can be obtained. Also, the first
Since the electrode layer 2 is formed on the already fired glass layer 12, it is not exposed to high temperatures after its formation, and general metal materials with relatively low melting points can be used as the electrode material. can.

In addition, in the above description, the case where the second electrode layer 4 is directly deposited on the surface of the glazed substrate 10 is illustrated, but depending on the smoothness of the surface of the glazed substrate 10, the glazed substrate 10 and the second
A glass layer may be provided between the electrode layer 4 and the second electrode layer 4 to smooth the base of the second electrode layer 4. Further, the step of separating the heating resistor layer 6 formed on the end surface of the glazed substrate 10 may be stopped halfway up the end surface, as shown in FIG.
It may be completely separated until the second electrode layer 4 is reached. By the way, in a case like Figure 1,
The unseparated heating resistor layer 6 on the second electrode layer 4 side is
It acts as a part of the second electrode layer 4 (common electrode) and does not adversely affect the selective driving of the heat generating section.

〔Effect of the invention〕

As explained above, the thermal head of the present invention uses a glazed substrate in which a glass layer is fired on one side of the substrate part and the thickness of the substrate part is equal to or less than the thickness of the glass layer. First and second electrode layers are provided on both surfaces, and a heat generating resistor layer is formed on the end face where the first and second electrode layers are exposed by cutting or polishing the end face of the substrate including each layer, and the heat generating resistor layer is formed on the end face where the first and second electrode layers are exposed. Since the heat generating resistor layer portion of the body layer located at least on the glass layer is separated into a plurality of parts according to the number of electrodes of the first or second electrode layer, heat generation can be achieved through a simple process. The thermal head can be formed only on the glass layer, and a thermal head with good heat generation characteristics can be obtained. In addition, since the first or second electrode layer is formed on the already fired glass layer, it is not exposed to high temperatures after its formation, and a metal material with a relatively low melting point is used as the electrode material. can do.

[Brief explanation of the drawing]

1 to 4 are block diagrams showing an embodiment of the thermal head of the present invention, and FIG. 5 is a block diagram showing an example of a conventional thermal head. DESCRIPTION OF SYMBOLS 1... Substrate, 2, 4... Electrode layer, 3... Glass layer, 5... Protective glass layer, 6... Heat generating resistor layer,
7... Protective layer, 8... Reinforcement plate, 10... Glazed substrate, 11... Substrate portion, 12... Glass layer.

Claims (1)

[Claims] 1. A glazed substrate in which a glass layer is fired on one side of the substrate portion and the thickness of the substrate portion is equal to or less than the thickness of the glass layer, and a first glazed substrate provided on both sides of the glazed substrate.
and a second electrode layer, and a protective glass layer formed on the first and second electrode layers, respectively;
The first and second electrode layers are formed on the exposed end surface by cutting or polishing the end surface of the substrate including each layer, and at least the layer portion located on the glass layer is formed on the first or second electrode layer. A thermal head comprising: a heating resistor layer divided into a plurality of layers according to the number of electrodes; and a reinforcing plate bonded to a side surface of the glazed substrate via the protective glass layer.