JP2568067Y2 - Thermal head - Google Patents

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 in a printer mechanism such as a word processor or a facsimile.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a thermal head incorporated in a printer mechanism such as a word processor is provided on an upper surface of a substrate 11 made of an electrically insulating material such as alumina.
A heating resistor 13 made of tantalum nitride or the like, and a pair of conductive layers 1 made of aluminum or the like and having a certain interval therebetween.
4a, 14b and a protective layer 15 made of silicon nitride or the like are sequentially applied to a heat sink 1 made of aluminum or the like.
6 has a structure in which it is placed and adhered to the upper surface of the heating resistor 6 via an adhesive tape 17, and a predetermined power is applied between the pair of conductive layers 14a and 14b to cause the heating area of the heating resistor 13 to generate Joule heat. At the same time, the generated heat is conducted to thermal paper or the like to form a printed image on the thermal paper or the like, thereby functioning as a thermal head.

In the thermal head having the above configuration, the substrate 11 on which the heating resistor 13 and the pair of conductive layers 14a and 14b are adhered to the upper surface of the heat radiating plate 16,
The thermal head is maintained at a predetermined temperature suitable for printing at the time of printing by transmitting and absorbing a part of the heat generated by the heat radiating plate 16.

[0004]

However, in this conventional thermal head, when the substrate 11 is bonded to the heat radiating plate 16 via the adhesive tape 17, the surface flatness of the heat radiating plate 16 is poor and the adhesive tape 17 Is trapped between the adhesive tape 17 and the heat radiating plate 16 to form an air pocket A, and the air pocket A impedes the conduction of heat from the substrate 11 to the heat radiating plate 16. As a result, a temperature variation occurs on the substrate 11, and as a result, the application of heat to the thermal paper or the like becomes non-uniform, and there is a drawback that uneven density of a printed image is generated on the thermal paper or the like.

[0005]

The thermal head according to the present invention comprises an electric insulating substrate having a heating resistor on the upper surface and a pair of conductive layers opposed to each other with a certain interval between the electric insulating substrate and an adhesive tape. A thermal head mounted and adhered to an upper surface, wherein the heat radiating plate is formed with a groove at a position 1.5 mm to 3.0 mm apart from opposing portions of a pair of conductive layers on the upper surface. And

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of the thermal head of the present invention, and FIG. 2 is a sectional view taken along line XX of FIG.
1 is a substrate, 3 is a heating resistor, 6 is a heat sink, and 7 is an adhesive tape.

The substrate 1 is made of an electrically insulating material such as alumina ceramics. A ceramic material powder such as alumina or silica is mixed with an appropriate organic solvent and solvent to form a slurry. A ceramic green sheet is formed by employing a method or the like, and then the ceramic green sheet is punched into a predetermined shape and fired at a high temperature (about 1600 ° C.).

On the upper surface of the substrate 1, a heat storage layer 2 made of glass or the like is adhered. The heat storage layer 2 accumulates and dissipates heat generated by a heating resistor 3, which will be described later. It acts to keep the response characteristics good.

The heat storage layer 2 is formed by applying a glass paste obtained by adding and mixing an appropriate organic solvent and a solvent to glass powder on the upper surface of the substrate 1 by employing a conventionally known screen printing method or the like. This is attached on the substrate 1 by baking it at a high temperature.

The heat storage layer 2 has a heating resistor 3 on its upper surface, and a pair of conductive layers 4a, 4
b are sequentially applied, and a predetermined power is applied between the pair of conductive layers 4a, 4b to form the two conductive layers 4a, 4a, 4b of the heating resistor 3.
The area between b, that is, the heat generating area of the heat generating resistor 3 functions as a thermal head by causing Joule heat to a temperature necessary for forming a print image on thermal paper or the like.

The heating resistor 3 is made of, for example, tantalum nitride. Since the heating resistor 3 made of tantalum nitride or the like itself has a predetermined electric resistivity, a pair of conductive layers 4a and 4b are formed. When electric power is applied via this, Joule heat is generated, and heat is generated to a temperature required for forming a printed image, for example, a temperature of 200 to 350 ° C.

The heating resistor 3 is attached on the heat storage layer 2 by employing a conventionally known sputtering method and photolithography technique.

A pair of conductive layers 4a and 4b provided on the heating resistor 3 are made of a metal such as aluminum or silver, and the conductive layers 4a and 4b generate Joule heat in the heating resistor 3. It acts to apply a predetermined electric power necessary for the operation.

The pair of conductive layers 4a and 4b are formed in a predetermined pattern on the heating resistor 3 by employing a conventionally known sputtering method and photolithography technique.

Further, a protective layer 5 made of silicon nitride or the like is formed on the upper surfaces of the heating resistor 3 and the pair of conductive layers 4a and 4b.
The protective layer 5 is formed by abrasion of the heating resistor 3 and the pair of conductive layers 4a and 4b by sliding with thermal paper or the like, moisture in the atmosphere, chlorine ion or sodium contained in the thermal paper or the like. It acts to protect against corrosion due to contaminants such as ions, which makes it possible to cause the heating resistor 3 to generate Joule heat at a predetermined temperature for a long period of time.

The protective layer 5 made of silicon nitride or the like is formed so as to cover the heating resistor 3 and the like on the upper surfaces of the heating resistor 3 and the pair of conductive layers 4a and 4b by employing a conventionally known sputtering method or the like. Is adhered to.

The substrate 1 on which the heating resistor 3 and the like are attached is also attached via an adhesive tape 7 to the upper surface of a heat radiating plate 6 made of aluminum or the like. Absorbs a part of the heat generated by the thermal head and maintains the thermal head at a predetermined temperature suitable for printing.

The heat radiating plate 6 has a groove 6a formed on the upper surface thereof and at a distance of 1.5 mm to 3.0 mm from opposite ends of the pair of conductive layers 4a and 4b.

The groove 6a formed in the heat radiating plate 6 functions to satisfactorily discharge air interposed between the heat radiating plate 6 and the adhesive tape 7 to the outside, and adheres the substrate 1 to the upper surface of the heat radiating plate 6. At the time of bonding via the tape 7, the air interposed between the heat radiating plate 6 and the adhesive tape 7 is satisfactorily released to the outside through the groove 6a.
Can be closely attached without forming an air pocket therebetween. Therefore, according to this thermal head, since the adhesive tape 7 is in close contact with the heat radiating plate 6, part of the heat generated by the heating resistor 3 is evenly conducted to the heat radiating plate 6 via the substrate 1, and And the temperature becomes uniform, and it is possible to form an extremely high-quality printed image without unevenness of density on thermal paper or the like.

When the groove 6a on the upper surface of the heat radiating plate 6 is formed at a position separated from the opposite ends of the pair of conductive layers 4a and 4b by not less than 3.0 mm, the heat radiating plate 6 is formed.
The air interposed between the adhesive tape 7 and the adhesive tape 7 is not completely discharged to the outside through the groove 6a, and an air pocket is formed between the heat radiating plate 6 and the adhesive tape 7 to cause unevenness in density of a printed image. If it is formed at a close position within 1.5 mm, the heat generated by the heating resistor 3 will not be well absorbed by the heat radiating plate 6 by the air in the groove 6a, and the substrate 1 will be in a temperature state suitable for printing. Can not be maintained. Therefore, the groove 6a formed on the upper surface of the heat radiating plate 6 needs to be formed at a position 1.5 mm to 3.0 mm away from the opposing portions of the pair of conductive layers 4a and 4b.

When the groove 6a has a width of less than 0.5 mm and a depth of less than 0.5 mm, when the substrate 1 is adhered to the upper surface of the heat radiating plate 6 with the adhesive tape 7, one of the adhesive tapes 7 is used. Portion enters the groove 6a and closes, making it difficult to satisfactorily discharge air interposed between the heat radiating plate 6 and the adhesive tape 7 to the outside, and having a width exceeding 1.5 mm and a depth of 1. If it exceeds 5 mm, the heat radiation effect of the heat radiating plate 6 is reduced, and the heat generated by the heat generating resistor 3 is accumulated in the heat radiating plate 6 and the printing quality tends to be deteriorated. Therefore, the width of the groove 6a formed in the heat radiating plate 6 is 0.5 mm to 1.
Preferably, the depth is 5 mm and the depth is 0.5 mm to 1.5 mm.

The heat radiating plate 6 having the groove 6a is manufactured by forming a groove 6a on a plate made of aluminum or the like by, for example, performing a conventionally known drawing process.

The adhesive tape 7 interposed between the substrate 1 and the heat radiating plate 6 is made of, for example, an acrylic adhesive.
As the adhesive tape 7, for example, a product number 468 manufactured by Sumitomo 3M Limited is suitably used.

The adhesive tape 7 adheres the substrate 1 to the heat radiating plate 6 and adheres the heat radiating plate 6 to the lower surface of the substrate 1.
The heat radiation plate 6 functions to stably conduct and absorb the heat of the substrate 1.

The substrate 1 is provided with an adhesive tape 7 adhered to the upper surface of the heat radiating plate 6 and thereafter, the substrate 1 is placed on the upper surface of the heat radiating plate 6 to which the adhesive tape 7 is adhered while pressing the substrate 1. Is bonded to the heat sink 6. In this case, since the groove 6a is formed on the upper surface of the heat radiating plate 6, the air interposed between the heat radiating plate 6 and the adhesive tape 7 is satisfactorily discharged to the outside through the groove 6a. 6. Adhering without forming an air pocket on 6.

Thus, the above-described thermal head of the present invention applies a predetermined power corresponding to an external electric signal between the pair of conductive layers 4a and 4b to bring the heating resistor 3 to a predetermined temperature required for printing. Joule heat is generated, and the generated heat is conducted to thermal paper or the like to form a print image on the thermal paper or the like, thereby functioning as a thermal head.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements can be made without departing from the scope of the present invention. If a large number are formed at short intervals over the entire upper surface of the heat radiating plate 6, the air pool is formed by the adhesive tape 7 and the heat radiating plate 6.
, And the paper contact with a platen roller (not shown) at the time of printing becomes extremely good. Therefore, it is preferable to form a large number of grooves 6a on the upper surface of the heat radiating plate 6 at short intervals over the entire upper surface of the heat radiating plate 6.

[0029]

According to the thermal head of the present invention, the grooves are formed on the upper surface of the heat radiating plate and 1.5 mm to 3.0 mm apart from the opposing ends of the pair of conductive layers. When the substrate is adhered to the upper surface of the plate, air interposed between the heat sink and the adhesive tape is satisfactorily discharged to the outside through the groove, and as a result, the substrate forms an air pocket on the heat sink. It can be adhered without.
Therefore, according to this thermal head, part of the heat generated by the heat generating resistor is evenly transmitted to the heat radiating plate via the substrate, and the temperature of the substrate in the heat generating region becomes uniform, so that there is no unevenness in the density of the thermal paper. It is possible to form a high quality printed image.

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 3 ... Heating resistor 6 ... Heat sink 6a ... Groove part 7 ... Adhesive tape

Claims (1)

(57) [Scope of request for utility model registration] 1. A thermal head in which an electrically insulating substrate having a heating resistor and a pair of conductive layers opposed to each other with a certain interval between the heating resistor and the electrically insulating substrate is mounted and adhered to the upper surface of a heat radiating plate by an adhesive tape. Wherein the heat sink is on its upper surface,
A thermal head characterized in that a groove is formed at a position 1.5 mm to 3.0 mm away from opposite ends of a pair of conductive layers.