JPH10181057A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent peeling of a protective film from occurring in the neighborhood of both end parts of a glaze layer even under the condition that a heat sensitive recording medium or the like is repeatedly and slidingly brought into contact with the surface of the protective film by a method wherein a reinforcing layer extending from both end parts of the glaze layer to the top surface of an insulating board is provided between the glaze layer and the protective film and between the insulating board and the protective film. SOLUTION: Heating resistors 3 and an electrically conductive layer 4a are coveringly formed on the top surface of an insulating board 1, on which a glaze layer is formed. Further, by continuously coating the top surface of the glaze layer and the insulating board 1 with a protective film 5, the heating resistors, the electrically conductive layer 4a and the like are covered with the protective film. Further, a reinforcing layer 6 extending from both the end parts of the glaze layer to the top surface of the insulating board 1 is provided between the protective film 5 and the glaze layer and between the protective film 5 and the insulating board 1. Thus, even when a heat sensitive recording medium P or the like is repeatedly and slidingly brought into contact with the surface of the protective film 5, the protective film 5 does not easily peel in the neighborhood or both end parts of the glaze layer and the favorable covering of the heating resistors 3 and the like with the protective film 5 can be maintained over a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a thermal head incorporated as a printer mechanism of a word processor, a facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, a thermal head incorporated as a printer mechanism of a word processor or the like has a glaze layer formed on an insulating substrate made of, for example, alumina ceramics in a strip shape, and a plurality of heating resistors formed on the glaze layer. A heat-sensitive recording medium having a structure in which a heat-generating resistor and a conductive layer are covered with a protective film that is applied from the upper surface of the glaze layer to the upper surface of the insulating substrate. Is sequentially applied onto the heating resistor using a platen roller or the like, while applying external power to the heating resistor to selectively cause the heating resistors to individually generate Joule heat, and dissipating the generated heat. Conduction to the heat-sensitive recording medium and formation of a predetermined print on the heat-sensitive recording medium function as a thermal head.

The glaze layer is for accumulating heat generated by a heating resistor attached to the upper surface of the glaze layer to an appropriate temperature to maintain good thermal response characteristics of the thermal head. When it is made of glass, it is formed by printing and applying a predetermined glass paste on the upper surface of the insulating substrate by screen printing or the like in the related art, and baking it at a high temperature.

The protective film is for protecting the heating resistor and the conductive layer from contact with moisture and the like contained in the air, sliding contact of the heat-sensitive recording medium, etc., for example, silicon nitride or silicon oxide. Are formed to a predetermined thickness by a conventionally known sputtering method or the like.

[0005]

However, in this conventional thermal head, when the glaze layer is formed by a thick film technique such as screen printing, the end of the glaze layer rises sharply as shown in FIG. When the protective film 15 is applied by sputtering or the like on the insulating substrate 11 on which the glaze layer 12 is applied, the protective film 15 applied near both ends of the glaze layer 12 is formed. Large internal stress occurs inside. For this reason, if the thermal recording medium P is repeatedly slid on the surface of the protective film 15 at the time of printing, the protective film 15 is damaged near both ends of the glaze layer 12 and easily peels off. As a result, the heating resistor 13 and the like cannot be covered well with the protective film 15, and the function as the protective film is lost in a short period of time.

[0006]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks. A belt-like glaze layer is provided on the upper surface of an insulating substrate, and a plurality of heating resistors and conductive materials are formed on the glaze layer. A thermal head, wherein the heating resistor and the conductive layer are covered with a protective film to be applied from the upper surface of the glaze layer to the upper surface of the insulating substrate, wherein the glaze layer and the insulating substrate, A reinforcing layer extending from both ends of the glaze layer to the upper surface of the insulating substrate.

The thermal head according to the present invention is characterized in that the reinforcing layer is made of the same material as the conductive layer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a plan view showing one embodiment of the thermal head of the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, FIG. 3 is a sectional view taken along line XX of FIG. 2, 1 is an insulating substrate, and 2 is a glaze. The layers 3, 3 are heating resistors, 4a to 4c are conductive layers, 5 is a protective film, and 6 is a reinforcing layer.

The insulating substrate 1 is formed of an electrically insulating material such as alumina ceramics, and has an upper surface that functions to support the glaze layer 2, the heating resistor 3, the conductive layers 4a to 4c, the protective film 5, and the like. .

When the insulating substrate 1 is made of alumina ceramics, a ceramic material powder such as alumina, silica, magnesia or the like is mixed with an appropriate organic solvent and a solvent to form a slurry, which is formed into a slurry by a conventionally known doctor blade method. A ceramic green sheet is formed by adopting a calender roll method or the like, and then the ceramic green sheet is punched into a predetermined rectangular shape and fired at a high temperature.

The glaze layer 2 applied on the upper surface of the insulating substrate 1 is made of a material having low thermal conductivity such as glass or polyimide resin.
It is attached in a belt shape with a thickness of 0 to 60 μm.

The glaze layer 2 has a plurality of heating resistors 3 disposed thereon projecting upward to effectively increase the pressing force (printing pressure) on the thermosensitive recording medium P, and to increase the heating resistors 3. The heat generated by the thermal head accumulates and dissipates to an appropriate temperature and acts as a heat storage layer for maintaining good thermal response characteristics of the thermal head.

The glaze layer 2 is formed by adding a suitable organic solvent, an organic solvent and the like to a predetermined glass powder and mixing the glass paste to form a strip on the upper surface of the insulating substrate 1 by a conventionally known screen printing method or the like. It is formed by printing and coating and baking it at a high temperature. At this time, the outer shape of the glaze layer 2 has a sharply rising shape at both ends.

The plurality of heating resistors 3 arranged on the partial glaze layer 2 have a predetermined pitch, for example, 62.5 mm.
high density at a pitch of μm are deposited and arrangements, since each is formed by an electrical resistance material such as TaSiO ₂ or TiSiO _2, TiCSiO _2, conductive layer 4a connected to both ends thereof, 4b, etc. When electric power is applied from the outside via the device, Joule heat is generated, and the heat is generated to a temperature necessary for forming a print on the thermosensitive recording medium P.

The conductive layers 4a and 4b connected to both ends of the heating resistor 3 are formed on the partial glaze layer 2 and on the insulating substrate 1.
Is attached in a predetermined pattern on the upper surface of
And a metal such as Cu, Ni or the like having a thickness of 0.7 to 1.2 μm, and functions as a power supply conductor for applying power from an external power supply to the heating resistor 3.

The heating resistor 3 and the conductive layers 4a, 4a
b, for example, a TaSiO ₂ film and an Al film are sequentially deposited on the upper surface of the insulating substrate 1 on which the partial glaze layer 2 is formed by a conventionally known thin film method (sputtering method or the like), and these are formed into a predetermined pattern by photolithography technology. It is formed by processing. At this time, the conductive layer 4a is commonly connected to one end of the heating resistor 3 on one long side of the insulating substrate 1 and led out to the other long side of the insulating substrate 1, and the conductive layer 4b is formed on the partial glaze layer 2 It is individually connected to the other ends of the heating resistors 3 and led out to the vicinity of a driver IC 5 arranged on the upper surface of the insulating substrate 1.

A protective film 5 is continuously applied on the upper surface of the glaze layer 2 on which the plurality of heating resistors 3 and the conductive layers 4a and 4b are applied and on the upper surface of the insulating substrate. The protective film 5 allows the heating resistor 3 and the conductive layer 4a,
4b and the like.

The protective film 5 is for protecting the heating resistor 3 and the conductive layers 4a and 4b from contact with moisture and the like contained in the air, sliding contact of the thermal recording medium P, and the like. It is made of silicon, silicon oxide, or the like, and is deposited and formed by employing a conventionally known sputtering method or the like.

A reinforcing layer 6 extending from both ends of the glaze layer 2 to the upper surface of the insulating substrate 1 is provided between the protective film 5 and the above-mentioned glaze layer 2 and insulating substrate 1.

The reinforcing layer 6 is made of the same material (metal such as Al, Cu, Ni, etc.) as the conductive layers 4a and 4b, and is formed with the same thickness (0.7 to 1.2 μm). 5
And the compatibility with the glaze layer 2 and the insulating substrate 1 are all good, so that the protective film 5 can be firmly adhered to the glaze layer 2 and the insulating substrate 1 near both ends of the glaze layer 2, Even when the thermal recording medium P is repeatedly slid on the surface of the protective film 5 during printing, the protective film 5
The film does not easily peel off near both ends. As a result, the heating resistor 3 and the like can be satisfactorily covered with the protective film 5 for a long period of time, and the reliability of the thermal head is significantly improved.

Further, the reinforcing layer 6 is formed of the conductive layers 4a and 4b.
Are formed of the same material as that of the conductive layers 4a to 4a.
When the 4d is formed by a sputtering method or a photolithography technique, the reinforcing layer 6 can be formed simultaneously only by changing the pattern of the photomask.
There is no need for a separate film formation step or the like for the formation of the film.

On the upper surface of the insulating substrate 1, a plurality of driver ICs 5 are arranged and mounted substantially in parallel with the arrangement of the heating resistors 3 described above.

The driver IC 5 has a plurality of terminal electrodes electrically connected to the above-described conductive layer 4b and the like on the lower surface thereof, and has therein an electric circuit such as a shift register, a latch circuit, and a switching transistor. Therefore, when an external printing control signal or the like is supplied through the conductive layer 4c, the heating resistor 3 is connected to the conductive layer 4b
, A predetermined output is generated, and the heating resistors 3 can be individually and selectively caused to generate Joule heat.

The conductive layer 4c is for supplying a print control signal or the like from the outside to the driver IC 5, and is made of the same material and the same forming method as the conductive layers 4a and 4b. Driver IC5 from the long side
Is formed so as to be led out to the vicinity of.

Thus, in the above-described thermal head, a predetermined power is applied between the conductive layers 4a and 4b as the driver IC 5 is driven while the thermal recording medium P is conveyed onto the heating resistor 3, and the heating resistor 3 is turned on. Joule heat is selectively generated individually, and the generated heat is conducted to the heat-sensitive recording medium P to form a predetermined print on the heat-sensitive recording medium P, thereby functioning as a thermal head.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the conductive layer 4a and the reinforcement The layers 6 are provided separately and independently. Instead, as shown in FIG. 4, a part of the conductive layer 4a (common electrode) on the insulating substrate 1 is formed on both ends of the glaze layer 2. It may be extended to this, and this extended part may be used as a reinforcement layer.

[0027]

According to the thermal head of the present invention, since the reinforcing layer firmly adheres the protective film to the glaze layer and the insulating substrate, the thermal recording medium is repeatedly slid on the surface of the protective film during printing. Even if it does, the protective film does not easily peel off near the both ends of the glaze layer. As a result, the heating resistor and the like can be favorably covered with the protective film for a long period of time, and the reliability of the thermal head is significantly improved. Moreover, if the reinforcing layer is formed of the same material as the conductive layer, the reinforcing layer can be formed at the same time when the conductive layer is formed by a sputtering method or a photolithography technique, and separately formed for forming the reinforcing layer. No film process is required.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a thermal head according to the present invention.

FIG. 2 is an enlarged plan view of a main part of FIG.

FIG. 3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is a plan view showing a modified example of the thermal head of the present invention.

FIG. 5 is an enlarged sectional view of a main part of a conventional thermal head.

[Explanation of symbols]

 1 ····· Insulating substrate 2 ····· Glaze layer 3 ····· Heating resistor 4a-4c ··· Conductive layer 6 ····· Reinforcing layer

Claims (2)

[Claims] 1. A belt-like glaze layer is deposited on an upper surface of an insulating substrate, a plurality of heating resistors and a conductive layer are deposited on the glaze layer, and the heating resistor and the conductive layer are bonded to the glaze layer. A thermal head, which is covered with a protective film to be applied from the upper surface of the glaze layer to the upper surface of the insulating substrate; A thermal head comprising a layer. 2. The thermal head according to claim 1, wherein the reinforcing layer is made of the same material as the conductive layer.