JPH07323591A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent the disconnection of the wiring conductor of a printed wiring board at the time of incorporation by covering the region positioned above the printed wiring board of a connector with a connector cover and fixing the connector cover to a radiation plate. CONSTITUTION:A connector cover 8 having a flat surface and composed of a material having viscoelasticity is arranged on a connector 7 in contact with the upper surface of a printed wiring board 5 on both sides of an attaching region and connected to a radiation plate 6 by an engaging member 9. Therefore, even when large external force is applied to the connector 7 when the connector 7 is inserted in the connector 10 on the side of a printer, the printed wiring board 5 is strongly fixed to the radiation plate 6 on both sides of the connector 7 in the form held between the connector cover 8 and the engaging member 9 and prevented from largely bending. Therefore, the disconnection of a wiring conductor caused by the bending of the printed wiring board 5 is not generated.

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 for word processors, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a thermal head incorporated as a printer mechanism for a word processor or the like has a plurality of heating resistors 12 made of tantalum nitride or the like and a conductive layer 13 made of aluminum deposited on its upper surface. For driving the heating resistor 12 to selectively generate heat.
An electrically insulating substrate 11 made of alumina ceramics on which C14 is mounted, a printed wiring board 15 having a wiring conductor connected to the conductive layer 13, and a glass epoxy resin supporting the printed wiring board 15 on its upper surface. A backing plate 16, a heat radiating plate 17 for supporting the electrically insulating substrate 11 and the backing plate 16 on the upper surface, and a connector 15b attached to the printed wiring board 15 so as to penetrate the printed wiring board 15. The driving IC
The conductive layer 13 comprises a head cover 18 for protecting the thermal paper 14 from sliding contact with the thermal paper and the like and preventing the thermal paper from being damaged by the contact with the connector 15b.
A predetermined electric power based on a print signal input from the printer device to selectively heat the heating resistor 12 by Joule heat and conduct the generated heat to a thermal paper or the like,
It functions as a thermal head by forming a predetermined print image on thermal paper or the like.

The printed wiring board 15 is for connecting the thermal head to an external electric circuit (not shown), and is mounted on the backing board 16 with a silicone adhesive or the like.

The connector 15b is a printed wiring board 15
Is connected to the wiring conductor of
By inserting a portion located below the printed wiring board 15 into the connector 17 on the printer device side, the electric circuit of the thermal head is electrically connected to the electric circuit in the printer device.

[0005]

However, in this conventional thermal head, the connector 15b is supported in an extremely unstable state because it is directly attached to the thin printed wiring board 15. Therefore, when the connector 15b is inserted into the connector 17 on the printer device side when the thermal head is incorporated into the printer device or the like, a large external force is applied to the connector 15b, and the printed wiring board 15 to which the connector 15b is attached is the backing plate. There is a defect that the wiring conductor of the printed wiring board 15 is broken as a result of peeling from 16 and bending.

Further, in the conventional thermal head, in order to protect the driving IC 14 on the electrically insulating substrate 11 from sliding contact of thermal paper or the like and to prevent the thermal paper or the like from being damaged by the contact of the connector 15b, the electric Insulating substrate 11
Area for mounting the driving IC 14 and the printed wiring board 1
A large head cover that can cover the upper surface of 5 at a time is attached. Therefore, the large head cover increases the size of the thermal head, and the thermal head as a product becomes expensive. ing.

[0007]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to make it possible to effectively prevent the wiring conductors of a printed wiring board from breaking when incorporated into a printer or the like. And to provide an inexpensive thermal head.

[0008]

SUMMARY OF THE INVENTION A thermal head according to the present invention has an upper surface on which a plurality of heating resistors and conductive layers and a driving IC covered with a resin sealing material are adhered. Board, a printed wiring board having a wiring conductor connected to the conductive layer, a heat dissipation plate supporting the electrically insulating substrate and the printed wiring board on the upper surface, and a state of penetrating the printed wiring board in the thickness direction. In a thermal head having a connector adapted to connect a portion located below the printed wiring board to an external electric circuit, the portion of the connector located above the printed wiring board being covered with a connector cover. In addition, the connector cover is fixed to the heat dissipation plate.

[0009]

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

FIG. 1 is a perspective view showing an embodiment of a thermal head of the present invention, FIG. 2 is an enlarged view of an X portion of FIG. 1, FIG. 3 is an exploded perspective view of the thermal head shown in FIG. Insulating substrate, 2 heating resistors, 3 conductive layer, 4 driving I
C, 4a are resin sealing materials, 5 is a printed wiring board, 5a is a wiring conductor, 6 is a heat dissipation plate, 7 is a connector, 8 is a connector cover, and 9 is a latching member.

The electrically insulative substrate 1 is made of electrically insulative material such as alumina. Ceramic material powder such as alumina, silica, magnesia, etc. is mixed with an appropriate organic solvent and solvent to form a sludge shape. A ceramic green sheet is formed by adopting the conventionally known doctor blade method, and thereafter, 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 electrically insulating substrate 1, a heat storage layer 1a made of glass, polyimide resin or the like is applied. The heat storage layer 1a accumulates and dissipates heat generated by a heat generating resistor 2 described later, and serves to improve the thermal response characteristic of the thermal head.

When the heat storage layer 1a is made of glass, a glass paste obtained by adding and mixing an appropriate organic solvent and a solvent to glass powder is adopted by a conventionally well-known screen printing method or the like to provide an electrically insulating substrate. 1 is applied in the form of a strip on the upper surface of 1 and is then baked at a high temperature to be applied on the upper surface of the electrically insulating substrate 1.

A large number of heating resistors 2 made of tantalum nitride or the like are deposited on the upper surface of the heat storage layer 1a.
Since the heat generating resistor 2 itself has a predetermined electric resistivity, it generates Joule heat when a predetermined power is applied, and the temperature required to form a printed image, for example, 300.
It exotherms to a temperature of ~ 450 ° C.

A heating resistor 2 made of tantalum nitride or the like.
Is deposited on the heat storage layer 1a by adopting the conventionally known sputtering method and photolithography technique.

Further, a pair of conductive layers 3 is deposited on the upper surface of the heating resistor 2, and the pair of conductive layers 3 apply a predetermined electric power to the heating resistor 2 located between them to generate the heating resistance. It acts to cause Joule heat generation in the body 2.

The pair of conductive layers 3 are made of a metal such as aluminum, and are deposited on the heating resistor 2 by using a conventionally known sputtering method or photolithography technique.

The surfaces of the heating resistor 2 and the conductive layer 3 are also covered with a protective film made of silicon nitride or the like,
The protective film has a function of protecting the heat generating resistor 2 and the pair of conductive layers 3 from oxidative corrosion due to contact with moisture in the atmosphere and abrasion due to sliding contact of the heat sensitive recording paper.

The protective film made of silicon nitride or the like is applied to the surfaces of the heating resistor 2 and the conductive layer 3 with a predetermined thickness by adopting a conventionally known sputtering method or the like.

A plurality of linearly arranged driving ICs 4 are attached to the upper surface of the electrically insulating substrate 1 in a state of being connected to one of the conductive layers 3, and the driving ICs are attached.
Reference numeral 4 denotes an action of selectively causing the plurality of heating resistors 2 to generate Joule heat in response to an external electric signal, specifically, turning on the power applied to each heating resistor 2 through a pair of conductive layers 3. It acts to control off.

The connection between the driving IC 4 and the conductive layer 3 is
For example, face down bonding method, specifically,
For example, a driving IC 4 having a solder bump is placed on the upper surface of the electrically insulating substrate 1 to which the conductive layer 3 and the like are adhered so that the solder bump abuts on the conductive layer 3 by using a die mounter or the like. After that, this is heated and melted at a predetermined temperature, and the driving IC 4 and the conductive layer 3 are bonded to each other via solder bumps.

The plurality of driving ICs 4 are also commonly covered with a belt-shaped resin sealing material 4a made of epoxy resin or the like, and the driving ICs 4a are covered by the resin sealing material 4a.
Is protected from abrasion due to sliding contact of thermal paper and the like, and is shielded from the atmosphere, so that moisture or the like contained in the atmosphere comes into contact with the driving IC 4 and corrosion occurs in the electrodes or the like of the driving IC 4. Can be effectively prevented.

The resin sealing material 4a is applied, for example, in the form of a strip of epoxy resin varnish on the upper surface of the electrically insulating substrate 1 where a plurality of driving ICs 4 are attached by a dispenser or the like. Together with this 120-1
By heat curing at a temperature of 50 ° C., a plurality of driving ICs 4 are deposited so as to cover them in common.

A printed wiring board 5 having a plurality of wiring conductors 5a electrically connects the conductive layer 3 and the wiring conductors 5a to the electrically insulating substrate 1 having the heating resistors 2 and the like on the upper surface. It is attached in the state.

The printed wiring board 5 has a structure in which a plurality of wiring conductors 5a made of a metal material such as copper are adhered to a resin film made of polyimide or the like and having a thickness of about 50 μm. The side is joined to the conductive layer 3 on the upper surface of the electrically insulating substrate 1 through a brazing material such as solder to connect the conductive layer 3 to the electric circuit of the printer.

The electrically insulative substrate 1 and the printed wiring board 4 are placed on a heat dissipation plate 6 made of a metal material such as aluminum, whereby the electrically insulative substrate 1 and the printed wiring board 5 are dissipated. Supported by.

The heat radiating plate 6 has a thickness of, for example, 1 to 3 mm and conducts and absorbs a part of the heat of the electrically insulating substrate 1 to excessively heat the electrically insulating substrate 1 by the heat generated by the heating resistor 2. It effectively prevents the temperature from becoming high.

The heat dissipation plate 6 is manufactured by forming an ingot (lump) made of aluminum or the like into a predetermined shape by using a conventionally known metal working method.

A plurality of straight connectors 7 made by plating phosphor bronze with tin are attached to one end of the printed wiring board 5 in a state of penetrating the printed wiring board 5.

The connector 7 has its upper end connected to the wiring conductor 5a of the printed wiring board 5 through a brazing material such as solder, and the portion located below the printed wiring board 5 is made of polyester or the like. Is stored inside the
Connect the connector 7 in the case to the connector 1 of the printer device.
By inserting it into 0, the electric circuit of the thermal head is connected to the electric circuit in the printer.

The connector 7 is formed by inserting the connector 7 into a through hole formed in the printed wiring board 5 in advance.
The upper end of the connector 7 is held at a predetermined position, and in this state, the upper end of the connector 7 is attached to the wiring conductor 5a of the printed wiring board 5 by a brazing material such as solder, so that the printed wiring board 5 is attached.

On the connector 7, a connector cover 8 made of a material having a flat surface and viscoelasticity (nylon, polyester, ABS resin, etc.) is further provided on both sides of the area where the connector 7 is attached. It is arranged so as to be in contact with the upper surface of 5 and is fixed to the heat dissipation plate 6 by a locking member 9.

Therefore, when the thermal head is incorporated into the printer device, when the connector 7 is inserted into the connector 10 on the printer device side, the connector 7 is accompanied by the insertion.
Even when a large external force is applied to the printed wiring board 5, the printed wiring board 5 is clamped between the connector cover 8 and the locking member 9 on both sides of the connector 7, and is firmly fixed to the heat dissipation plate 6 and is largely bent. There is nothing that would end up. As a result, the wiring conductor 5a of the printed wiring board 5 is never broken due to the bending of the printed wiring board 5.

Further, since the connector cover 8 made of a material having a flat surface and viscoelasticity is arranged on the connector 7, thermal paper or the like contacts the connector 7 or the connector cover 8 during printing. It does not cause scratches and can always form a good printed image on thermal paper or the like.

Further, as described above, the driving IC 4 on the electrically insulating substrate 1 is covered with the resin sealing material 4a which protects the IC 4 from sliding contact such as thermal paper, and the connector 7 is provided on the connector 7. Since the cover 8 is arranged,
A large head cover that can cover a part of the electrically insulating substrate 1 and the printed wiring board 5 is not necessary at all, and the thermal head can be downsized and the thermal head as a product can be made inexpensive. Will also be possible.

The connector cover 8 has a groove on the back surface for accommodating the connector 7. Nylon, polyester, ABS resin or the like is adopted by well-known injection molding, and the connector cover 8 is It is manufactured by integrally molding.

The connector cover 8 is attached to the heat dissipation plate 6 by inserting a locking member 9 having a slightly larger front end into a through hole formed in the printed wiring board 5 and the heat dissipation plate 6 in advance. This is done by locking the tip of the locking member 9 to the lower surface of the heat dissipation plate 6. In this case, since the locking member 9 made of a material having viscoelasticity allows a slight deformation due to the application of an external force, the tip of the locking member 9 is formed from the through hole of the printed wiring board 5 or the heat dissipation plate 6. If the tip portion of the locking member 9 passes through the through hole, the tip portion is slightly deformed by the pressure from the inner circumference of the through hole, and if the tip portion of the engaging member 9 passes through the through hole, the tip portion of the engaging member 9 penetrates after passing through the through hole. It is released from the pressure from the inner circumference of the hole, returns to its original shape, and is locked to the lower surface of the heat dissipation plate 6.

Thus, the above-mentioned thermal head applies a predetermined electric power between the pair of conductive layers 3 based on the print signal,
In addition to selectively causing the heating resistor 2 to generate Joule heat,
The generated heat is conducted to the thermosensitive recording paper to form a predetermined printed image on the thermosensitive recording paper, thereby functioning as a thermal head.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. For example, in the above-mentioned embodiments, the connector cover and Although the locking member is formed integrally, instead of this, as shown in FIGS. 4 (a) and 4 (b),
The connector cover 8a is formed of a viscoelastic polyester or the like into a plate shape, and a rivet formed of steel or the like is used as the locking member 9a. A polyester film 21 (thickness: about 0.
1 mm) may be attached. In this case, in addition to obtaining the same effect as that of the above-described embodiment, during printing, the thermal paper or the like is guided along the surface of the film 21 onto the heating resistor 2 and is caught by the resin sealing material 4a. Therefore, the thermal paper or the like can be stably transported onto the heating resistor 2. Therefore, it is preferable to attach the polyester film 21 from the joint between the printed wiring board 5 and the electrically insulating substrate 1 to the top of the resin sealing material 4a.

Further, as shown in FIGS. 5 (a) and 5 (b), the connector cover 8b may be formed in a plate shape with viscoelastic polyester or the like, and a clip formed of steel or the like may be used as the locking member 9b. Well, in this case, in addition to the effect similar to that of the above-described embodiment, it is not necessary to previously form holes or the like for penetrating the locking member in the printed wiring board 5 and the heat dissipation plate 6, and the printing can be performed. Wiring board 5
There is no restriction on the arrangement of the wiring conductor 5a above. Therefore, it is preferable to use a clip formed of steel or the like as the locking member 9b.

[0041]

In the thermal head of the present invention, the portion of the connector located above the printed wiring board is covered with the connector cover, and the connector cover is fixed to the heat dissipation plate, so that the thermal head is incorporated into the printer device. When inserting the connector into the connector on the printer device side, even if a large external force is applied to the connector due to the insertion, the printed wiring board is clamped between the connector cover and the locking member on both sides of the connector. It is firmly fixed to the heat sink and does not bend significantly. As a result, the wiring conductor of the printed wiring board is never broken due to the bending of the printed wiring board.

In the thermal head of the present invention,
Since the connector cover is arranged on the connector, the thermal paper or the like does not come into contact with the connector and is not damaged during printing, and a good printed image can always be formed on the thermal paper or the like.

Further, in the thermal head of the present invention,
Since the driving IC on the electrically insulating substrate is a resin sealing material and the connector on the printed wiring board is covered with a connector cover, it is possible to cover a part of the electrically insulating substrate and the printed wiring board. The large-sized head cover and the like that can be performed are not necessary at all, and the thermal head can be downsized, and the thermal head as a product can be inexpensive.

[Brief description of drawings]

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

FIG. 2 is a side view of the thermal head shown in FIG. 1 viewed from the direction A.

FIG. 3 is an exploded perspective view of the thermal head shown in FIG.

FIG. 4A is a side view showing another embodiment of the thermal head of the present invention, and FIG. 4B is a side view of FIG.

5A is a side view showing another embodiment of the thermal head of the present invention, and FIG. 5B is a side view of FIG. 5A viewed from the direction C.

FIG. 6 is a side view of a conventional thermal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrically insulating substrate 2 ... Heating resistor 3 ... Conductive layer 4 ... Driving IC 4a ... Resin sealing material 5 ... Printed wiring board 5a ... Wiring conductor 6 ... Heat sink 7 ... Connector 8 ... Connector cover 9 ... Hooking member 10 ... Connector on printer side

Claims (1)

[Claims] 1. An electrically insulating substrate having an upper surface on which a plurality of heating resistors and a conductive layer and a driving IC covered with a resin encapsulant are adhered, and connected to the conductive layer. A printed wiring board having a wiring conductor, a heat dissipation plate supporting the electrically insulating substrate and the printed wiring board on the upper surface, and attached in a state of penetrating the printed wiring board in the thickness direction,
In a thermal head having a connector adapted to connect a portion located below the printed wiring board to an external electric circuit, a portion of the connector located above the printed wiring board is covered with a connector cover, and the connector A thermal head with a cover fixed to a heat sink.