JPH0994988A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the manufacturing steps of a heat radiating plate by forming a swelled part provided at the end of a locking member and locked along the lengthwise direction on the upper surface of the plate and incorporating a groove formed narrower in the width of the opening than the lower part in the plate. SOLUTION: A heat radiating plate 5 supports a board 1 and a printed circuit board by its upper surface and conductively absorbs the part of the heat of the board 1 via the lower surface of the board 1 to effectively prevent the board 1 from becoming excessively high temperature by the heat generated from a heating element. The plate 5 is manufactured by drawing the metal of aluminum to be softened by heating to a high temperature through a predetermined die hole in a predetermined direction and cutting it in a predetermined length by a press and so on. A groove 5a formed in the opening to be narrow and wider at the lower part than the opening in the lengthwise direction is so provided on the upper surface of the plate 5 as to cross the upper surface of the plate 5, and a locking member 7 is locked in the groove 5a.

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 such as a word processor and a facsimile.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a thermal head incorporated as a printer mechanism such as a word processor has a heating element array 12 formed by linearly arranging a large number of heating elements on its upper surface, a silicone resin, etc. Sealing material 1
Substrate 11 made of alumina ceramics, to which a plurality of driver ICs covered by 3a are attached, respectively.
Is placed on the heat dissipation plate 14 made of aluminum or the like,
Further, the head cover 15 is attached so as to cover a part of the substrate 11, for example, a region where the driver IC is mounted or a region where the terminal portion of the wiring conductor is arranged.

Such a thermal head is a driver IC
When the heating element is driven, Joule heat is selectively generated, and the generated heat is conducted to the thermal recording medium to form a predetermined print image on the thermal recording medium, thereby functioning as a thermal head.

The head cover 15 is a driver I.
It protects C and the like from the application of external force due to sliding contact of the thermal recording medium, or guides the thermal recording medium onto the heating element array 12, for example, a predetermined screw 1
The head cover 15 was attached to the thermal head by screwing 6 through the through hole provided in the head cover 15 into the screw hole 14a on the upper surface of the heat dissipation plate.

[0005]

However, in this conventional thermal head, since the head cover 15 is attached to the heat dissipation plate 14 by the screw 16, the heat dissipation plate 1 is used.
A screw hole 14 a is formed in the thickness direction of No. 4. Further, this heat sink 14 is generally formed by a pultrusion method, in which aluminum or the like that has been heated to a high temperature and softened is pulled in a predetermined direction (the length direction of the heat sink 14) through a die hole and cut into a predetermined length. Since the heat dissipation plate 14 is formed by drawing, the screw holes 14a provided in the direction (thickness direction) orthogonal to the drawing direction cannot be formed at the same time. Therefore, before assembling the thermal head, a step of drilling a through hole at a predetermined position of the heat dissipation plate 14 using a drill or the like and separately forming a screw hole 14a by threading the through hole is required. Therefore, there is a drawback that the manufacturing process of the heat dissipation plate 14 becomes complicated.

[0006]

The present invention has been devised in view of the above-mentioned drawbacks, and a substrate having a heating element is placed on a rectangular radiator plate and a part of the surface of the substrate is covered. A thermal head comprising a head cover attached to a heat radiating plate via a locking member, wherein the heat radiating plate is provided with a bulging portion provided at the tip of the locking member along the length direction on the upper surface thereof. It is characterized in that it has a recessed groove formed so that the width of the opening is narrower than the width below the opening.

[0007]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view showing a thermal head of the present invention, and FIG. 2 is a side view of the thermal head of FIG. 1 assembled. 1 is a substrate, 2 is a heating element array, 3 is a driver IC, Reference numeral 4 is a printed wiring board, 5 is a heat dissipation plate, 5a is a groove, 6 is a head cover, and 7 is a locking member.

The substrate 1 is made of an electrically insulating material such as alumina ceramics, and has a heating element array 2 on the upper surface of which a plurality of heating elements are linearly arranged and a sealing material 3a such as a silicone resin. A plurality of driver ICs 3 which are commonly covered are respectively attached.

The heating element is made of, for example, tantalum nitride or ruthenium oxide and has a predetermined electric resistance value. When it is applied through the heat-sensitive recording medium, Joule heat is generated at a temperature necessary for forming a printed image on the thermosensitive recording medium, for example, a temperature of 250 to 400 ° C.

The driver IC 3 is arranged substantially parallel to the direction of the heating element array 2 and selectively controls the heating elements by controlling on / off of a current flowing through the heating elements based on a print signal from the outside. It has the effect of causing Joule heat.

The heating element is adhered to a predetermined pattern and a predetermined thickness on the upper surface of the substrate 1 by using a thin film method such as a sputtering method and a photolithography technique, and the driver IC 3 is formed by wire bonding, for example. It is mounted at a predetermined position on the substrate 1 by, for example, face down bonding.

On the upper surface of the substrate 1, a plurality of wiring conductors (not shown) connected to the heating element and the driver IC 3 are provided.
Is attached, and the wiring conductor is led out to the end of the substrate 1 and electrically connected to the wiring of the printed wiring board 4 at the lead-out portion.

As the printed wiring board 4, for example, a flexible printed wiring board or the like is used, and has a function of electrically connecting the thermal head to the printer main body through a connector 8 attached to one end thereof.

Then, the substrate 1 and the printed wiring board 4
Are mounted on a rectangular radiator plate 5 made of aluminum or the like in a state of being connected to each other, and a part of the surface is covered by a head cover 6 arranged above them.

The head cover 6 is a driver IC 3
It is also for protecting the connection between the substrate 1 and the printed wiring board 4 from the application of external force, or for guiding the thermal recording medium onto the heating element array 2 during printing, and is to be described later. It is attached to the heat dissipation plate 5 via the member 7.

The head cover 6 is made of a metal such as aluminum or an ABS resin. For example, when the head cover 6 is formed of aluminum, an aluminum plate having a predetermined size is formed into a predetermined shape by using a conventionally known press forming method. It is produced by doing.

On the other hand, the heat radiating plate 5 supports the substrate 1 and the printed wiring board 4 on the upper surface thereof, and at the same time, a part of the heat of the substrate 1 is conducted and absorbed through the lower surface of the substrate 1 so that the substrate 1 is This is for effectively preventing the temperature from becoming excessively high due to the heat generated by the heating element, and it is a conventionally known pultrusion method, specifically, a metal such as aluminum softened by being heated to a high temperature is prescribed. It is manufactured by pulling in a predetermined direction (lengthwise direction A of the heat dissipation plate 5) through the mold hole and cutting it with a predetermined length by a press or the like. In addition, the heat dissipation plate 5 manufactured in this way
The surfaces formed by cutting (side surfaces located at both ends in the length direction) are relatively rough surfaces, but the surfaces formed by sliding contact with the mold cavity (upper surface, lower surface, etc.) are substantially flat surfaces. Therefore, when the substrate 1 is placed on the upper surface of the heat dissipation plate 5, the adhesion between the two becomes good. At this time, if a glass epoxy plate 8 having a thickness substantially equal to that of the substrate 1 is interposed between the printed wiring board 4 and the heat dissipation plate 5, the substrate 1
Also, the printed wiring board 4 can be supported on the heat dissipation plate 5 in a stable state.

On the upper surface of the heat dissipation plate 5, a recessed groove 5a having a narrow opening and a wider lower part than the opening is formed across the upper surface of the heat dissipation plate 5. The locking member 7 is locked in the groove 5a.

As a concrete sectional shape of the concave groove 5a, for example, a trapezoidal shape as shown in FIG. 2 is applied.

Further, the locking member 7 has a bulging portion Y provided at the tip thereof which is bulged in the concave groove 5a of the heat sink 5 larger than the width of the opening of the concave groove 5a.
It is adapted to be locked to the inner wall B of the above, and as such a locking member 7, for example, a push rivet as shown in FIGS. 3 (a) and 3 (b) is used.

The push rivet is made of an elastic material such as ABS resin, and a plurality of legs 7c are integrally formed on a doughnut-shaped engaging portion 7d having a diameter larger than the through hole of the head cover 6. In addition, it has a structure in which the shaft body 7a is attached so as to penetrate through the hollow portion of the engaging portion 7d, and the portions of the plurality of legs 7c function as the bulging portion Y.

To explain the operation of such a push rivet, a plurality of legs 7c are simultaneously opened and locked by applying pressure from above to the head portion 7b of the shaft body 7a, and the head portion 7a is screwed. The lock is released by rotating the shaft 7a by a predetermined angle using
Is moved upward, and at the same time, the foot 7c is closed. At this time, the size w1 of the bulging portion Y with the foot 7c closed is slightly smaller than the width of the opening of the groove 5a, and the size w2 of the bulging portion Y with the foot 7c opened is concave. It is set to be larger than the width of the opening of the groove 5a, so that the push rivet 7 with the foot 7c closed is radiated through the through holes of the head cover 6, the printed wiring board 4, and the support plate 8. It is inserted into the groove 5a of the plate 5, and then the head 7b
By pressing to open the foot 7c, the engaging portion 7d of the engaging member 7 is engaged with the head cover 6 and the bulging portion Y of the engaging member 7 is inflated to engage with the inner wall B of the groove 5a. Therefore, the head cover 6 and the like can be firmly attached to the heat dissipation plate 5.

As described above, in the thermal head of the present invention, the concave groove 5a is formed in the lengthwise direction A of the upper surface of the heat radiating plate 5 so that the width of the opening is narrower than the width below the concave groove 5a. Since the locking member 7 engaged with the head cover 6 is locked to the 5a, the head cover 6 can be firmly and satisfactorily attached to the heat dissipation plate 5 by a simple mechanism. Moreover, since the recessed groove 5a provided on the upper surface of the heat sink 5 can be formed at the same time when the heat sink 5 is drawn and molded, the heat sink 5 can be manufactured easily and the thermal head can be manufactured at low cost. It becomes possible to do.

Thus, the thermal head of the present invention selectively causes the heating element to generate Joule heat as the driver IC is driven, and transfers the generated heat to the thermal recording medium to form a predetermined print image on the thermal recording medium. When formed, it functions as a thermal head.

The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the head cover is used. However, instead of this, the head cover 6'and the locking member 7'may be integrally formed by using a resin material or the like, as shown in FIG. In this case, the tip of the locking member 7'is made slightly larger than the width of the opening of the groove and a predetermined notch C is formed in the tip so that the tip of the locking member 7'is The size can be easily changed.

In the above-described embodiment, the concave groove provided on the upper surface of the heat dissipation plate 5 has a trapezoidal sectional shape, but the shape is not limited to such a shape, and the upper surface of the heat dissipation plate 5 may be formed. The cross-sectional shape of the groove provided may be any shape as long as the opening is narrow and the bottom is wide.

[0028]

According to the thermal head of the present invention, the head cover can be attached to the radiator plate by a simple mechanism and the manufacturing process of the radiator plate is simplified, so that the thermal head can be manufactured at low cost. be able to.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a thermal head of the present invention.

FIG. 2 is a side view of the thermal head of the present invention.

FIG. 3 is a perspective view showing the operation of the push rivet.

FIG. 4 is a partially enlarged sectional view showing a modified example of the thermal head of the present invention.

FIG. 5 is an exploded perspective view of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Heating element array 3 ... Driver IC 4 ... Printed wiring board 5 ... Heat dissipation plate 5a ... Recessed groove 6 ... Head cover 7 ... Push rivet (locking) Element)

Claims (1)

[Claims] 1. A thermal head in which a substrate having a heating element is placed on a rectangular radiator plate, and a head cover covering a part of the surface of the substrate is attached to the radiator plate via a locking member. The radiating plate has a recess formed in the upper surface thereof along the lengthwise direction in which a bulging portion provided at the tip of the locking member is locked and the width of the opening is narrower than the lower part thereof. A thermal head having a groove.