JPH0829595B2 - Thermal head - Google Patents

Description

The present invention relates to a thermal head mounted in a facsimile, various printers and the like.

[Outline of Invention]

The present invention is a thermal head in which a plurality of heating resistors and a drive circuit unit are formed on a substrate, and the heating resistors are selectively heated to perform heat-sensitive recording. In the thermal head, the substrate is a transparent or semitransparent wear-resistant material. Is formed by bonding the support heat dissipation plate to the heating resistor side of the substrate and grinding at least a part of the back surface side of the substrate to perform heat-sensitive recording on this ground surface. It is possible to obtain a highly reliable thermal head by accurately controlling the position of the heating resistor pattern in bonding and setting the thickness of the recording surface of the substrate.

[Conventional technology]

Conventionally, in a line type or serial type thermal head, either a direct drive system or a diode matrix system has been mainly adopted as a drive system of a heating resistor. In such a type of thermal head, semiconductor device pellets such as ICs and diodes that constitute the drive circuit section and the like are directly mounted on the thermal head substrate to reduce the size.

However, in this type of thermal head,
There are many restrictions in terms of downsizing, reliability, product price, etc., and improvements are desired.

That is, as shown in FIG. 8, a conventional thermal head has a driving semiconductor element (1) mounted on a substrate (101).
02) to protect the device (102) with a sealant (10).
The structure is such that it is molded in 3) and then covered with the sealing part cover (104).

In order to obtain good printing with this type of thermal head, it is essential to secure the contact characteristics of the platen (105). That is, in this thermal head, the sealing portion cover (104) has the platen (10
It was necessary to escape from the paper path P from 5). In other words, from the heating resistor to the driving semiconductor element (102)
Since the distance W _{1 to} is limited by the thickness t of the sealing portion cover (104) and the outer dimensions of the platen (105), there is a limit to downsizing the head. In addition, this constraint is
This is an obstacle to the miniaturization of 1), and since glaze ceramic (Al ₂ O ₃ ) that has been widely used as a substrate material is expensive, it is desired to improve the material cost.

On the other hand, in the conventional thermal head, a wear resistant layer is formed on the heating resistor via the oxidation resistant layer to protect the heating resistor from the platen (105).

However, since the oxidation resistant layer and the wear resistant layer are laminated by a thin film forming technique such as spattering, there is a limit in ensuring the wear life by making the wear resistant layer a thick film structure.
For example, if you try to apply a wear resistant layer of 10 μm or more,
This film deposition requires a long time, and the film stress at the time of film formation causes cracks and the like, which lowers the reliability of the head.

Furthermore, in order to secure the above-mentioned hitting characteristic, the film thickness of the electrode for supplying power to the heating resistor is limited to about 0.5 to 1.5 μm, which makes the wire bonding work complicated and
There was a problem with the reliability of this connection.

[Problems to be solved by the invention]

By the way, in recent years, in the field of thermal recording, there is a trend toward miniaturization and high reliability of thermal heads, and as described above, conventional thermal heads cannot sufficiently satisfy these demands, and improvement thereof is desired. ing.

Therefore, a thermal head has been proposed in which the other surface of the substrate, on which the drive circuit having the heating resistor and the semiconductor element is formed on one surface, that is, the back surface side, is used as the recording surface with which the platen is brought into contact.

However, in this thermal head, the heating resistor is located inside the recording surface of the substrate and cannot be seen from the outside. It is difficult to accurately correspond to a predetermined position on the plate, and it is also difficult to adjust the thickness of the recording surface with respect to the heating resistor to a predetermined thickness. Therefore, variations in the cutting position of the substrate and the plate thickness are suppressed. Therefore, the substrate must be formed with high precision, which is a problem in manufacturing.

Under such circumstances, the present invention has been proposed, and the position of the heating resistor formed on the substrate is accurately regulated with respect to the support plate, and the recording surface is also formed to have a predetermined thickness, so that the platen hits well. It is an object of the present invention to provide a thermal head that can obtain excellent print quality.

[Means for solving problems]

In order to achieve the above-mentioned object, the thermal head of the present invention is a thermal head in which a plurality of heating resistors and a drive circuit are formed on a substrate, and the heating resistors are selectively heated to perform thermal recording. The substrate is formed of a transparent or semi-transparent wear-resistant material, the support heat radiating plate is joined to the heating resistor side of this substrate, and the part surface corresponding to the heating resistor position on the back side of this substrate is ground. The heat-sensitive recording is performed on this ground surface.

[Action]

The thermal head of the present invention has a structure in which thermal recording is performed on the other surface of the substrate on which the heating resistor and the driving circuit are formed on one surface, that is, on the back surface side. Although it is located on the inner side with respect to the contact surface (heat-sensitive recording surface), since the substrate is made of a transparent or semi-transparent wear-resistant material, the heating resistors, etc. must be recognized from the outer side. Since it is possible to accurately control the position of the heat generating resistor with respect to the support heat radiating plate, and the thickness of the recording surface with respect to the heat generating resistor can be accurately set by adjusting the grinding process, excellent print quality can be obtained. The reliability of can be improved.

〔Example〕

Specific examples to which the present invention is applied will be described below.

As shown in FIGS. 1 and 2, the thermal head of this example has a heating resistance pattern divided into a first half and a second half on one plane (1a) of a transparent or semitransparent abrasion resistant substrate (1). (2a), (2b) and a drive circuit section (semiconductor element such as IC in this embodiment) (3) are formed, and these heating resistance patterns (2a), (2b) and semiconductor element (hereinafter referred to as drive IC) It has a structure in which the support heat radiating plate (10) is joined and integrated on the (3) side through the oxidation resistant layer (8) and the adhesive layer (9). Quartz, glass having no alkali component, or the like is used as the abrasion resistant substrate (1), and borosilicate glass is used in this example.

The other surface (back surface side) (1b) of the substrate (1) is a thermal recording surface, and this back surface side (1b) is a portion that opposes the heating portion (2A) of one heating resistance pattern (2a). The surface is thick,
In this example, the inclined surface (1b ₁ ) is formed on the inclined surface (1b ₁ ).
Is adapted to perform heat-sensitive recording on the heat-sensitive recording paper p by slidingly contacting the heat-sensitive recording paper p and pressing and holding it by the platen P.

Heat resistance pattern (2a), (2b) and drive IC (3)
Is connected to the conducting wires (5a) and (5b) of Au or the like by means of wire bonding or the like through the electrode patterns (4a), (4b) and (4c) for electrical continuity. Then, the electrode pattern (4
The area between (a) and (4b) serves as the above-mentioned heat generating section (2A), which generates heat and contributes to printing, and the latter half of the electrode pattern (4b) has the other heat generating resistance pattern (2b). The drive IC (3) is mounted on the common electrode pattern (4B) formed on the first half through the oxidation resistant layer (8).

The electrode pattern (4c), which is formed as an external terminal on the latter half of the other heating resistance pattern (2b), has a flexible printed circuit plate (7) for conducting the external drive circuit in the latter half of the electrode pattern (4c). Anisotropic conductive film (11)
Connected through.

Therefore, in the thermal head of the present embodiment, the drive 1C (8) is driven by the drive current supplied through the circuit plate (7), and the heating portion (2A) of one heating resistance pattern (2a) is selected. Substrate (1)
The heat-sensitive recording is performed on the back surface side, that is, near the end of the inclined surface (1b ₁ ). The other heating resistance pattern (2b) not directly involved in the thermal recording does not have to be formed, but in the present embodiment, in order to make the front surface side (1a) of the substrate (1) flush, It is formed in order to improve the adhesion of the oxidation resistant layer (8) to the substrate (1).

As described above, in the thermal head of this embodiment, since the back surface side (1b) of the substrate (1) is used as the recording surface, the contact characteristics of the platen P are good. In addition, the heating resistance patterns (2a), (2b) and the drive circuit (drive IC
The formation surface of (3)) is different on the front side (1a) and the recording surface on the back side (1b), so the drive IC (3) etc. can be arranged freely without considering the paper path from the platen P. Can be set to. Therefore, the dimensional restrictions of the substrate (1) are greatly relaxed, and the substrate (1) can be downsized.

In addition, the thickness of the substrate (1) can be freely set by adjusting the grinding amount of the recording surface on the back side (1b), which will be described later, and the thickness can be increased to about 10 to 20 μm, which improves wear resistance. In addition, the drive IC (3) of the drive circuit formed on the surface side (1a) of the head can be protected and the life of the head can be extended.

As the material of this substrate (1), glass or quartz is used as compared with the conventional expensive materials such as glazed ceramics, so the material cost can be greatly reduced in combination with the above-mentioned miniaturization. Becomes Furthermore, a thin plate such as a Si wafer can be used as the substrate (1). The heating resistance pattern (2a) is formed on the front surface side of the substrate (1),
Since it is the surface opposite to the contact surface with the thermal recording paper, it is no longer necessary to form a thick wear-resistant layer on the heating resistance pattern as in the conventional case. Therefore, the process of forming a wear-resistant layer by sputtering, which has a low production work efficiency, is unnecessary, and the productivity is improved. When the heating resistance pattern (2a), the electrode patterns (4a), (4b), etc. are formed by a thick film, it can be manufactured without using an expensive device such as a sputtering device.

The drive IC (3) and the wire bonding portion between the drive IC (3) and the electrode patterns (4b) and (4c) are molded with a sealing material (12) such as silicone resin. This drive IC (3) and electrode patterns (4a), (4b), (4c)
The support heat radiating plate (10) fixed and integrated with the oxidation resistant layer (8) and the adhesive layer (9) on top has a substantially concave notch (10a) at a portion facing the drive IC (3). ) Is formed and the mold portion formed by the sealing material (12) described above is housed, and the drive IC (3) and the like are protected by the support heat dissipation plate (10). That is, the support heat radiating plate (10) has both a heat radiating function and a function as a storage package for protecting the drive IC (3).

When the substrate (1) and the supporting heat radiation plate (10) are bonded and fixed to each other, as described above, the substrate (1) is made of a transparent or semi-transparent wear resistant material such as glass, so that the heating resistance pattern (2a), (2b) can be easily seen and recognized from the back surface (1b) which is the recording surface, and even if a cutting deviation a occurs in the cutting of the substrate (1) as shown in FIG. 3A, as shown in FIG. 3B. The position of the heat generation resistance patterns (2a) and (2b) with respect to the support heat dissipation plate (10) can be accurately adjusted, and the adhesive layer (9) for adhering the substrate (1) and the support heat dissipation plate (10) is Since an ultraviolet-curable adhesive can be used and the substrate (1) and the like can be bonded without being adversely affected by heating, the substrate (1) and the supporting heat dissipation plate (10) can be bonded more reliably.

Here, as the material of the support heat dissipation plate (10), ceramics such as Al ₂ O ₃ or the like, Fe—Ni alloys, metallic materials such as Fe and Al having excellent thermal conductivity are used. The support heat dissipation plate (10) has an adhesion function as well as a conventional glaze layer function, and a low melting point glass layer (13) is provided on the bonding surface side in order to provide appropriate heat conductivity. Has been formed.

After fixing to the substrate (1) and the supporting heat dissipation plate (10) in this way, the back surface (1b) side of the substrate (1) is adjusted so that the thickness on the heat generating portion (2A) becomes a predetermined thickness. The recording surface (1b ₁ ) is formed by grinding in an inclined shape.

In the grinding of this substrate (1), as shown in FIG. 4, the pattern of the heating resistances (2a) and (2b) is viewed through from the backside (1b) side by using a microscope monitor (20). Adjust to a point that produces a clear image, and adjust the machining reference surface S of the machining table (21) with this as the reference, and in this state, the recording surface (1b ₁ ) is specified by the vertical or horizontal axis surface grinding mechanism. Grind to thickness. The recording surface (1b ₁ ) is an inclined surface having a predetermined angle as described above, and the inclination angle is preferably in the range of 5 ° to 45 °, the material strength is weak at 5 ° or less, and too thick if 45 ° or more. Cannot be printed.

The microscope monitor (20) described above determines the total magnification according to the required accuracy. The practical example uses 400 times. The glass used as the substrate is generally 5 to 100 μm.
If the m-position is 5 μm or less, the glass strength cannot be maintained. In addition, the surface roughness is about 0.1 to 3 μmRa with a # 400 grindstone. Is obtained, which is practically sufficient.

As described above, according to this embodiment, the substrate (1) is downsized,
That is, since the contact surface of the platen can be narrowed,
A so-called vertical type thermal head is also possible. Therefore, a one-platen multi-head color printer or the like can be manufactured at a small size and at low cost.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and it goes without saying that various structures can be adopted without departing from the spirit of the present invention.

In particular, if the drive circuit unit is made thin (for example, a thin film transistor) and all the other components are directly formed on the substrate, a smaller thermal head is completed.

〔The invention's effect〕

As is clear from the above description, the thermal head of the present invention is provided with the heating resistance pattern and the drive circuit portion on one plane of the substrate, and the thermal recording is performed on the back side of this one plane. Without considering the path
In addition, the arrangement space of the heating resistance pattern and the drive circuit section can be freely set, and the dimensional constraints of the substrate are relaxed. Therefore, miniaturization of the head can be easily realized. Further, since the back surface, which is the sliding contact surface of the platen, has a flat structure such as an inclined surface, the contact property of the thermal recording paper or the platen is significantly improved, and excellent print quality can be obtained.

In addition, since the substrate is made of a transparent or semi-transparent wear resistant material, the heat generation resistance pattern can be directly recognized from the back surface, that is, the recording surface side, which facilitates alignment during manufacturing and adjustment of the recording surface thickness. , Automation of processing is possible and mass production can be achieved.

As described above, according to the present invention, it is possible to inexpensively provide a compact and highly reliable thermal head for various thermal printers.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a thermal head to which the present invention is applied, FIG. 2 is a plan view of the substrate portion of the thermal head as seen from the inner surface side, and FIG. 3 is an explanation of the bonding state of the substrates. 4 and 5 are explanatory views of the grinding process of the substrate, and FIG. 5 is a side view schematically showing a conventional thermal head. In the figure, (1) is the substrate, (1b ₁ ) is the inclined surface as the recording surface,
(2a) and (2b) are heating resistance patterns, (2A) is a heating part,
(3) is a drive IC as a semiconductor device, (4a), (4
b) and (4c) are electrode patterns, (5a) and (5b) are conductors,
(8) is an oxidation resistant layer, (10) is a support heat sink, and (20) is a microscope monitor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Osamu Ishikawa 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Magne Products Co., Ltd. (72) Satoru Kikuchi 6 Kita-Shinagawa, Shinagawa-ku, Tokyo 5th-6th, Sony Magne Products Co., Ltd.

Claims (1)

[Claims] 1. A thermal head in which a plurality of heating resistors and a drive circuit section are formed on a substrate and the heating resistors are selectively heated to perform thermal recording, wherein the substrate is transparent or semi-transparent wear-resistant. And a support heat radiating plate is joined to the heating resistor side of the substrate, and a part surface corresponding to the position of the heating resistor on the back side of the substrate is ground. The thermal head is characterized by performing.