JPS63179763A - Thermal head - Google Patents

Abstract

PURPOSE:To enhance printing quality by obtaining constant developed color density in a printing dot by reducing the temp. irregularity of an inclined recording surface heated by a heat generating resistor part, by forming a heat generating part for preheating to the inclined recording surface part having a printing heat generating part arranged thereto of a substrate to preheat the recording surface part, especially, the thick part of the inclined high part thereof. CONSTITUTION:Corresponding to the inclined recording surface 1b1 of a substrate 1 on the side of the back surface 1b thereof, a printing heat generating part 2A is arranged to the surface of the relatively thin part on the side of the first half part thereof and a heat generating part 3A for preheating is arranged to the surface of the relatively thick part of the side of the latter half part thereof. By this constitution, the conduction of heat from the printing heat generating part 2A to the recording surface 1b1 becomes well. Since the surface of the thick part of the recording surface 1b1 can be preheated by the heat generating part 3A for preheating, the recording surface 1b1 does not generate temp. irregularity even when corresponds to the printing heat generating part 2A in an inclined state and is almost uniformly heated. Constant developed color density can be obtained with respect to the printing dot on thermal paper without raising the heat generating temp. of the printing heat generating part 2A and the efficiency of input power can be enhanced. Further, the dimensional restriction of the substrate 1 can be relaxed to a large extent and miniaturization can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head installed in facsimile machines, various printers, and the like.

[Summary of the invention]

The present invention provides a thermal head in which a plurality of heat-generating resistors and drive circuit parts are formed on a wear-resistant substrate, and which performs thermal recording by selectively generating heat in the heat-generating resistors, which is supported on the heat-generating resistor side of the substrate. A heat dissipation plate is bonded, and the surface corresponding to the heat generating resistor on the back side of this substrate is formed into a slope that slopes low toward one edge to form a recording surface on which thermal recording is performed. By forming a heat generating resistor for preheating separately from the heat generating resistor, the thick side of the recording surface is preheated prior to thermal recording, improving temperature unevenness on the recording surface and improving printing quality. It is something.

[Conventional technology]

Conventionally, in line type or serial type thermal heads, either a direct drive type or a diode matrix type has been mainly used as a driving method for a heating element. In this type of thermal head, semiconductor elements such as ICs and diodes constituting the drive circuit are directly mounted on the thermal head substrate to achieve miniaturization.

However, this type of thermal head has many limitations in terms of miniaturization, reliability, product price, etc., and improvements are desired.

That is, as shown in FIG. 3, the conventional thermal head includes a driving semiconductor element (101) mounted on a substrate (101).
102), this element (102) is molded with a sealant (103) and a sealing part cover (104) is attached.
It has a structure covered with.

In order to obtain good printing with this type of thermal head, it is essential to ensure the contact characteristics of the platen (105). That is, in this thermal head, the sealing part cover (104) is attached to the platen (
It was necessary to escape from the paper bus P from 105). In other words, from the heating resistor to the driving semiconductor element (1
Since the distance W1 to 02) is limited by the thickness t of the sealing part cover (104) and the external dimensions of the platen (105), there is a limit to miniaturization of the head. In addition, this restriction hinders the miniaturization of the substrate (101), and glaze ceramic (^h0
Since 3) is expensive, this improvement is desired also from the viewpoint of material cost.

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

However, since these oxidation-resistant layers and wear-resistant layers are laminated using thin film formation techniques such as sputtering, there are limits to making the wear-resistant layer a thick film structure and ensuring a long wear life. If you try to crotch more than 10μm,
It takes a long time to form this film, and cracks and the like occur due to film stress during film formation, reducing the reliability of the head.

Furthermore, in order to ensure the above-mentioned contact characteristics, the thickness of the electrode that feeds power to the heating resistor is limited to about 0.5 to 1.5 μm, which makes wire bonding work complicated and reduces the reliability of this connection. Problems remained in this regard.

[Problem that the invention seeks to solve]

In recent years, however, in the field of thermal recording, there has been a trend toward smaller thermal heads and higher reliability. It is rare.

Therefore, the other surface, that is, the back side, of the substrate on which the heat generating resistor and the driving circuit section having the semiconductor element are formed is the recording surface that the platen comes into contact with, and the portion of this recording surface that corresponds to the heat generating resistor. A thermal head formed on an inclined surface has been proposed in order to reduce the thickness of the plate.

In this configuration, the distance from the heat-generating resistor to the thermal recording paper on the recording surface is not constant, that is, the distance between the heat-generating resistor and the corresponding recording slope is different between the inner and outer regions. The temperature on the surface is also not constant between the heat generating resistor and the surface directly above it. Therefore, due to the temperature unevenness of the recording surface, color density unevenness tends to occur in printed dots on the thermal paper, resulting in problems such as deterioration of printing quality.

In view of the above, the present invention has been proposed, and provides a thermal head that can reduce the temperature unevenness of the inclined recording surface heated by the heating resistor, obtain a constant color density in the printed dots, and can be expected to provide excellent printing quality. The purpose is to provide

[Means for solving problems]

In order to solve the above-mentioned problems, the thermal head of the present invention includes a plurality of heat-generating resistors and drive circuit parts formed on a wear-resistant substrate, and selectively generates heat in the heat-generating resistors to perform thermal recording. At the head, the board is emitted! ! ) A support heat sink is bonded to the resistor side, and on the back side of the substrate, a part corresponding to the heat generating resistor part is formed into an inclined surface that slopes low toward one edge, and thermal recording is performed on this inclined surface. Is there a preheating generator separate from the heating resistor part corresponding to the recording surface of the board? ! It is characterized by forming a low resistance part.

[Effect]

The thermal head of the present invention has a structure in which thermal recording is performed on the back side of the surface on which the heating resistor section and drive circuit section of the substrate are formed.

In this way, by forming the heat generating resistor section and the drive circuit section such as the semiconductor element on a surface different from the thermosensitive recording surface, the heat generating resistor section can be freely arranged and formed on one end side of the substrate. In addition, due to the inclined surface that slopes low toward one edge on the back side of the substrate, the thickness of the portion corresponding to the heat generating resistor part becomes relatively thin, and the heat from the heat generating resistor part is easily transmitted to the recording surface side formed by the N4 slope. By forming a heating part for preheating separately from the heating resistor corresponding to this recording surface part, the thick part of the recording surface part can be preheated before recording, and the temperature unevenness of the recording surface part is reduced, so that it can be heated evenly on the thermal paper. The printed dots have a constant color density, and printing quality can be improved.

〔Example〕

Hereinafter, specific examples that make use of the present invention will be described.

As shown in FIGS. 1 and 2, the thermal head of this example has a heating resistor pattern (2) for printing formed near the front edge on one plane (1a) of the wear-resistant substrate +1. A heating resistor pattern (3) for preheating is formed inside the heating resistor pattern (2) for heating, and a divided electrode pattern (4) for each of the heating resistor patterns (2) and (3) is formed.
a), (4b) and (5a), (5b) are formed with 1% insulation (61) interposed between them, and the substrate (
At the rear end of one plane (1a) of 11 is a terminal t! A 1tWA pattern (7) is formed, and a common electrode pattern (8) is formed in the middle part. One plane (l) of this substrate (1)
a) is a drive circuit section, and in this example, a semiconductor element such as an IC (
(hereinafter referred to as drive IC) (9) is mounted, and these heating resistor patterns (21, (3) and drive I (j9) are mounted.
) side has a structure in which a support heat dissipation plate (12) is integrally bonded via an oxidation-resistant layer (10) and an adhesive layer (11). As the wear-resistant substrate (1), quartz, glass having no alkali component, or the like is used, and in this embodiment, borosilicate glass is used. In addition, as the oxidation-resistant layer (1o), S
i3N+ + 5i (h etc. is used, adhesive layer (11
), an insulating adhesive is used.

The other side (back side) (lb) of the substrate (1) is a heat-sensitive recording surface, and this back side (1b) is the heating resistor part (hereinafter referred to as the heating heating part for printing) of the printing heating part resistance pattern (2). The inclined surface (lb
x) and a thermal recording paper p is formed on this inclined surface (lbt).
Thermal recording is carried out on the thermal recording paper p by slidingly contacting the recording paper p and holding it under pressure with the platen P.

The output side of the board (drive IC+9 mounted on 11) is one electrode pattern (
4a), on the input side, Au is applied to the terminal electrode pattern (7).
Conductive wires (13a) and (13b) are connected by means such as wire bonding to establish electrical continuity between the heating resistor pattern for printing (2) and the drive IC (9), and the terminal electrode pattern (7) A flexible printed circuit plate (14) for electrical connection with an external drive circuit is connected to the rear half thereof via an anisotropic conductive film (15). As shown in FIG. 2, an electrode pattern (4a
), (4b) and the common electrode pattern (8) serves as the above-mentioned printing heating section (2A), which generates heat and contributes to printing.

Therefore, the drive IC (9) is driven by the drive current supplied via the circuit plate (14), selectively generates heat in the printing heat generating part (2A), and Thermal recording is performed near the end of (lbx). Hereinafter, this inclined surface (ibr) will be referred to as a recording surface.

Furthermore, the preheating heat generating resistor pattern (3) is formed in the form of a horizontal band on the inner surface of the printing heat generating resistor pattern (2), that is, on the surface corresponding to the high part of the inclined recording surface (lbx) of the substrate (1). This heating resistor pattern for preheating (
One of the m-pole patterns (5a) in 3) is led out to the rear end side of the substrate (1) and externally? The other electrode pattern (5a) is connected to the a source conductor, and the other electrode pattern (5a) is also connected to the 11fl electrode pattern (8).
The preheating heat generating part (3A) of the preheating heat generating part anti-pattern (3) is configured to generate heat separately from the printing heat generating part (2^).

In this way, in the thermal head of this embodiment, since the back side (lb) of the substrate (1) is used as the recording surface, the contact characteristics of the platen P are good.

Also, since the surface on which the heating resistor pattern (21,' (3) and the drive circuit (drive IC (9)) are formed is on the front side (1a) and is different from the recording surface on the back side (1b), the platen
Drive IC without considering the paper bus from
You can freely set the placement space such as +91.

Therefore, the dimensional constraints on the substrate (1) are significantly relaxed, so
The substrate (1) can be made smaller.

In addition, the thickness of the substrate +1) can be freely set by adjusting the amount of grinding of the recording surface (lbl) on the back side (1b), which will be described later.
The drive IC (3) of the drive circuit formed in the head can be protected and the life of the head can be extended.

As the material for this substrate (11) is glass, quartz, etc., compared to conventionally expensive materials such as graze ceramic, it is possible to significantly reduce material costs in conjunction with the aforementioned miniaturization. Furthermore, since the substrate (1) is formed of a thin plate such as a wafer, it is possible to thicken the film without going through the conventional process with low work efficiency such as sputtering, which greatly improves productivity. This eliminates the need for expensive equipment.

Then, drive fc (9) and electrode pattern (4a)
.

The wire bonding portion with (7) is molded with a sealing material (16) such as silicone resin. This drive IC (9) and electrode patterns (4a), (4b)
, (7) The support heat dissipation plate (12), which is fixed and integrated through the oxidation-resistant layer (10) and the adhesive layer (11), has a substantially concave cutout in the part facing the drive IC (9). Notch (1
2a) is formed, the molded part made of the above-mentioned sealing material (16) is housed, and the drive IC (91, etc.) is protected by the support heat sink (12).In other words, the support heat sink (12) has a heat dissipation function. It also functions as a storage puff cage to protect the drive IC (91).

Here, the material of the support heat sink (12) is ^I2O3
Ceramics such as , Fe single-layer alloys, and metal materials with excellent thermal conductivity such as Pe and ^1 are used. In addition to adhesion, this support heat dissipation plate (12) has the function of a conventional glaze layer, and a low melting point glass layer is formed on the bonding surface side in order to provide appropriate thermal conductivity. is desirable.

After the substrate (11) and the support heat sink (12) are fixed in this manner, the front side of the back surface (lb) of the substrate (11) is ground into a low slope in the direction of the front edge, as described above, to form an inclined surface. That is, a recording surface (lbl) is formed.As mentioned above, this recording surface (lbl) is an inclined surface with a predetermined angle, and this inclination angle is 5°.
A range of ~45° is preferable; if it is less than 5°, the material strength is weak, and if it is more than 45°, it is too thick and good quality printing cannot be obtained. The printing heating section (2^) corresponds to the lower side of the recording surface (lbx), and the preheating heating section (3^) corresponds to the higher side.

In this way, according to this embodiment, the back surface (1b) of the substrate (1)
A heat generating part for printing (static) is arranged on a relatively thin part on the front half side corresponding to the inclined recording surface (lbl) on the side, and a heat generating part for preheating is arranged on a relatively thick part on the rear flat part side. By arranging the heat generating part (3^), the recording surface (Ibx) from the heat generating part for printing (2A)
In addition to improving heat conduction to the recording surface (lbx), the thick part of the recording surface (lbx) can be preheated by the preheating heating section (3^), so the recording surface (lbr) can be heated by the heating section for printing (3^). 2
^) Even if it corresponds to the thermal paper in an inclined manner, the temperature will be almost uniformly heated without any unevenness, and the printed dots on the thermal paper will be heated without increasing the heat generation temperature of the printing heat generating part (28). It is possible to obtain a constant color density, and the efficiency of human power is also improved.

In addition, even if the recording surface (lbt) of the substrate (1) is tapered and thinned, the other surfaces, that is, the surface where the drive circuit section is formed, are maintained at a predetermined thickness, so the mounting is carried out on this surface. The drive IC (91) that will be used will be fully protected.

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

For example, the heating pattern for preheating (3) may not be formed in a horizontally continuous band shape, but may be formed corresponding to the heating pattern for printing (2), and each electrode pattern is not limited to the embodiment shown in the drawings. As described above, any configuration may be used as long as the heating section for printing and the heating section for preheating generate heat to a desired state.

〔Effect of the invention〕

As is clear from the above description, the thermal head of the present invention forms a heating part for preheating on the inclined recording surface part on which the heating part for printing of the substrate is disposed, and heats up the recording surface part, especially the thick part of the inclined high part. By preheating, when the printing heat generating section generates heat, p! 4. The diagonal recording surface is heated almost uniformly to the required temperature with almost no temperature unevenness, and a constant clear color density can be obtained in the printed dots on the thermal paper, improving printing quality.

In addition, since the heat generation temperature of the heat generating part for printing to obtain a constant color density can be lowered, the efficiency of input power is improved, and deterioration of the heat generating part can be suppressed, so that the life of the head can be extended.

As described above, according to the present invention, a compact and highly reliable thermal head for various thermal printers can be provided at low cost.

[Brief explanation of the drawing]

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 viewed from the inner side, and Fig. 3 is a schematic diagram of a conventional thermal head. FIG. In the figure, (1) is the substrate, (lbx) is the inclined surface as the recording surface, (2) is the heating part resistance pattern for printing, (2A) is the heating part for printing, (3) is the heating resistor pattern for preheating, ( 3^) is the preheating heat generating part, (4a), (4b), (5
a>, (5b). (7) is an electrode pattern, (9) is a drive IC1 as a drive circuit section (10) is an oxidation-resistant layer, and (12) is a support heat sink.

Claims (1)

[Scope of Claims] A thermal head in which a plurality of heat-generating resistors and a drive circuit are formed on a wear-resistant substrate, and performs thermal recording by selectively generating heat in the heat-generating resistors, wherein the heat-generating resistor of the substrate A support heat dissipation plate is bonded to the side, and the back side of the substrate has a portion corresponding to the heating resistor portion formed into an inclined surface that slopes low toward the edge, and the inclined surface is used for recording thermal recording. 1. A thermal head comprising: a heating resistor for preheating; and a heating resistor for preheating is formed separately from the heating resistor in correspondence with the recording surface of the substrate.