JP2948972B2 - 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 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 or the like has a heat storage layer 12 made of glass or the like on the surface thereof. Heating resistor consisting of 13
And a pair of conductive layers 14 made of a metal material such as aluminum.
a, 14b and a protective layer 15 made of silicon nitride or the like are sequentially applied by a sputtering method or the like, and the electrode 16a of the driving IC 16 is connected to the one conductive layer 14a by a face-down bonding method, a wire bonding method, or the like. A predetermined power is applied between the pair of conductive layers 14a and 14b in accordance with the driving of the driving IC 16, and the heating resistor 13 is selectively caused to generate Joule heat. The generated heat is conducted to a thermal paper or the like, and a print image is formed on a recording member such as the thermal paper to function as a thermal head.

[0003]

However, in this conventional thermal head, the electrode 16a of the driving IC 16 is connected to the conductive layer 14a by employing a face-down bonding method or a wire bonding method. When the electrode 16a of the driving IC 16 is directly connected to the conductive layer 14a made of aluminum via a brazing material made of solder, the solder has a poor bonding property with the aluminum forming the conductive layer 14a and is firmly bonded. Therefore, in order to firmly join the two, a metal having good solder bonding properties, such as nickel or gold, must be previously applied to the surface of the conductive layer 14a.
The step of depositing nickel, gold, or the like on the surface of the 14a is separately required, so that the number of manufacturing steps of the thermal head is large, which has the disadvantage of complicating the process.

Further, the electrode 16a of the driving IC 16 and the conductive layer 14
When a is connected by a wire bonding method, the number of electrodes of one driving IC 16 is as many as 108, and each of them is connected to a conductive layer.
It takes a long time to connect to 4a via a wire, which has the disadvantage that the mass productivity of the thermal head is greatly reduced.

Further, in a conventional thermal head, a heating resistor 13 and the heating resistor are provided on the upper surface side of the electrically insulating substrate 11.
Both of the driving ICs 16 for selectively generating Joule heat are mounted and mounted, and the height of the driving IC 16 is determined by the heating resistor.
When the recording member is sequentially fed onto the heating resistor 13 to form a printed image because the recording member is extremely higher than the upper surface of the recording member 12, the recording member is curved to effectively prevent the feeding from being impeded by the driving IC 16 The recording member must be fed onto the heating resistor 13 and is difficult to be curved. For example, a recording member made of a hard material such as plastic hits the driving IC 16 to accurately form a desired print image. Had the disadvantage of not being able to do so.

Further, in this conventional thermal head, since the driving IC 16 is mounted on the upper surface side of the electrically insulating substrate 11 in a protruding state, the overall shape of the thermal head becomes a complicated three-dimensional shape. When mounting the thermal head on a printer mechanism such as a word processor,
It also has the disadvantage that its implementation is greatly restricted.

[0007]

According to the present invention, there is provided a thermal head in which a recess is formed on one main surface of an electrically insulating substrate on which a heating resistor and a pair of conductive layers are applied, and the heating resistor is formed in the recess. A drive IC for selectively causing the body to generate Joule heat is embedded so that an upper surface thereof is substantially flush with one main surface of the electrically insulating substrate, and one of the conductive layers is formed of the drive IC. It extends to the upper surface and is directly connected to the electrode of the driving IC, and furthermore, the area from the heating resistor to the driving IC is continuously covered with a protective layer.

[0008]

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

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line XX of FIG. 1, 1 is an electrically insulating substrate, 3 is a heating resistor, and 4a and 4b are a pair. Is a driving IC.

The electrically insulating substrate 1 is made of an electrically insulating material such as alumina ceramics, and is made of alumina, silica,
An appropriate organic solvent and a solvent are added to and mixed with a ceramic material powder such as magnesia to form a slurry, and a ceramic green sheet is formed by employing a conventionally known doctor blade method. Is punched into a predetermined shape, a plurality of sheets are laminated, and fired at a high temperature (about 1600 ° C.).

A heat storage layer 2 made of glass or the like is adhered on the upper surface of the electrically insulating substrate 1, and the heat storage layer 2 accumulates and dissipates heat generated by a heat generating resistor 3, which will be described later. It works to keep the thermal response characteristics of the head 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 electrically insulating substrate 1 by employing conventionally known screen printing or the like. Thereafter, it is attached to the upper surface of the electrically insulating substrate 1 by baking it at a high temperature.

The heat storage layer 2 has a heating resistor on its upper surface.
3, and a pair of conductive layers 4a, 4b with a certain distance therebetween are sequentially applied, and a predetermined power is applied between the pair of conductive layers 4a, 4b to form both conductive layers of the heating resistor 3. The region sandwiched between 4a and 4b, that is, the heat generating region of the heat generating resistor 3 functions as a thermal head by causing Joule heat to a temperature required 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, the heating resistor 3 has a pair of conductive layers 4a and 4b. When electric power is applied through the device, Joule heat is generated, and the temperature required to form a printed image, for example, 20
Heat is generated to a temperature of 0 ° C 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.

The pair of conductive layers 4a and 4b provided on the heating resistor 3 are made of aluminum, silver, or the like.
The conductive layers 4a and 4b function to apply a predetermined electric power necessary for causing the heating resistor 3 to generate Joule heat.

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

Further, on the upper surfaces of the heating resistor 3 and the pair of conductive layers 4a and 4b, a protective layer 5 made of silicon nitride or the like is applied.

The protective layer 5 is used to protect the heating resistor 3 and the pair of conductive layers 4a and 4b from abrasion due to sliding with heat-sensitive paper or the like, moisture in the atmosphere, contamination of chlorine ions or sodium ions contained in the heat-sensitive paper or the like. It acts to protect against corrosion by the substance, whereby the heating resistor 3 can generate Joule heat to a predetermined temperature for a long period of time.

The protective layer 5 made of silicon nitride or the like is applied so as to cover the heating resistor 3 and the like by using a conventionally known sputtering method or the like.

On the other hand, the heating resistor 3 and a pair of conductive layers
A concave portion 1a is formed on the upper surface of the electrically insulating substrate 1 on which 4a and 4b are attached.
A driving IC 6 is buried in the concave portion 1 a so that the upper surface thereof is substantially flush with the upper surface of the electrically insulating substrate 1.

The driving IC 6 functions to cause the heating resistor 3 to selectively generate Joule heat in response to an external electric signal;
Specifically, it acts to control on / off of the power applied to the heating resistor 3 via the pair of conductive layers 4a and 4b, and the electrode 6a of the driving IC 6 is provided on the electrically insulating substrate 1. Is connected directly by extending a part of the conductive layer 4a.

Incidentally, the electrically insulating substrate 1 of the driving IC 6
In order to bury the inside of the drive IC 6, first, for example, a well-known drilling process is performed on the upper surface of the electrically insulating substrate 1, for example, on a ceramic green sheet serving as the electrically insulating substrate 1 to form a hole. Recess 1a slightly larger than dimensions
Then, the driving IC 6 is fixed in the concave portion 1a with an adhesive made of polyimide or the like.

Each electrode 6a of the driving IC 6 and a conductive layer
4a, first, a driving IC 6 is buried in the concave portion 1a of the electrically insulating substrate 1 with its electrode 6a facing upward, and then, a metal such as aluminum, silver, or the like is formed on the upper surface of the electrically insulating substrate 1. One end of the conductive layer 4a made of
The deposition is performed by employing a conventionally known sputtering method and photolithography technique so that the other end is in contact with the electrode 6a of the driving IC 6.

In this case, since the driving IC 6 is embedded so that the upper surface thereof is substantially flush with the upper surface of the electrically insulating substrate 1, the conductive layer 4a is formed on the upper surface of the electrically insulating substrate 1. When the heating resistor 3 and the electrode 6a of the driving IC 6 are attached so as to be connected to each other, there is no disconnection or the like due to a step in the conductive layer 4a, and the heating resistor 3 is connected to the heating resistor 3 via the conductive layer 4a. It is possible to reliably connect the electrode 6a of the driving IC 6 with the electrode 6a.

The driving IC 6 has an upper surface substantially flush with the upper surface of the electrically insulating substrate 1, and the driving IC 6 has an electrode 6a on the upper surface thereof. When the layer 4a is applied in a predetermined pattern on the electrically insulating substrate 1 by a sputtering method, a photolithography technique, or the like, the connection between each electrode 6a of the driving IC 6 and the conductive layer 4a can be performed simultaneously and at the same time, As a result, the manufacturing process of the thermal head is greatly simplified, and mass productivity is greatly improved.

Further, the driving IC 6 is an electrically insulating substrate 1
The upper surface of the electrically insulating substrate 1 on which the heating resistor 3 is attached is embedded in the concave portion 1a provided on the upper surface so that the upper surface thereof is substantially flush with the upper surface of the electrically insulating substrate 1. Becomes substantially flat.As a result, when the recording member is fed onto the heating resistor 3 to form a printed image, the recording member does not hit the driving IC 6 and the printing is not hindered.
As a result, it is possible to form a good printed image even if the recording member is made of a hard material such as plastic.

Further, the drive IC 6 is embedded in the electrically insulating substrate 1 so that the overall shape of the thermal head becomes simple. As a result, when the thermal head is mounted on a printer mechanism such as a word processor, the drive IC 6 has a simple structure. There are no major restrictions on the implementation.

Further, in this case, as shown in FIGS. 1 and 2, the protective layer 5 is continuously applied to the area from the heating resistor 3 to the driving IC 6, and the conductive layer 5 layer
4a and the driving IC 6 are well coated. Therefore, even when printing on a hard recording member such as plastic which is difficult to bend, the recording member is in direct sliding contact with the electronic circuit pattern on the upper surface of the driving IC or the connection portion between the driving IC 6 and the conductive layer 4a. It is possible to effectively prevent damage to these parts, improve the reliability of the thermal head, and stably run the recording member along the surface of the thermal head in a flat state. Can be.

Thus, in the thermal head of the present invention, a predetermined power corresponding to an external electric signal is applied between the pair of conductive layers 4a and 4b in accordance with the driving of the driving IC 6, and the heating resistor 3 is selected. Joule heat is generated, and the generated heat is conducted to a recording member such as thermal paper to form a printed image on the recording member, thereby functioning as a thermal head.

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.

[0032]

According to the thermal head of the present invention, the upper surface of the drive IC is substantially flush with one principal surface of the electrically insulating substrate, and the upper surface of the drive IC is provided with an electrode. Therefore, when the conductive layer is applied in a predetermined pattern on the electrically insulating substrate by a sputtering method, a photolithography technique, or the like, the connection of each electrode of the driving IC and the conductive layer is performed simultaneously and at once. As a result, the manufacturing process of the thermal head is greatly simplified, and the mass productivity is greatly improved.

According to the thermal head of the present invention, the driving IC is embedded in the recess provided in the electrically insulating substrate such that the upper surface thereof is substantially flush with one main surface of the electrically insulating substrate. Therefore, one main surface of the electrically insulating substrate on which the heating resistor is attached is substantially flat, and as a result, the recording member is driven when the recording member is fed onto the heating resistor to form a printed image. Printing is not hindered by the IC for use, and as a result, a good printed image can be formed even if the recording member is made of a hard material such as plastic.

Further, according to the thermal head of the present invention, the driving IC is buried in the electrically insulating substrate so that the overall shape of the thermal head becomes simple, and as a result, the thermal head is connected to a printer mechanism such as a word processor. When implemented on a PC, there are no major restrictions on the implementation.

Further, according to the thermal head of the present invention, the driving IC is embedded so that its upper surface is substantially flush with one principal surface of the electrically insulating substrate. Heating resistor and drive I
When the electrode is attached so as to be connected to the electrode C, there is no disconnection or the like due to a step in the conductive layer, and the heating resistor and the electrode of the driving IC are securely connected via the conductive layer. It becomes possible.

Further, according to the thermal head of the present invention, since the area from the heating resistor to the driving IC is continuously covered with the protective layer, the hard recording such as plastic which is difficult to bend. Even when printing on a member, the recording member is not slid directly in contact with the electronic circuit pattern on the upper surface of the driving IC or the connection between the driving IC and the conductive layer. Thus, the reliability of the thermal head can be improved, and the recording member can be stably run along the surface of the thermal head in a flat state.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of 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]

1 ... electrical insulating substrate, 3 ... heating resistor, 4a, 4b
... A pair of conductive layers, 6 ... Drive IC, 6a ... Drive IC electrode

Claims (1)

(57) [Claims] 1. A driving device for forming a concave portion on one main surface of an electrical insulating substrate on which a heating resistor and a pair of conductive layers are applied, and selectively causing the heating resistor to generate Joule heat in the concave portion. the IC, embedded so that its upper surface is one main surface substantially flush electrically insulating substrate, and extending out not by driving IC to the upper surface of the drive IC of one of the conductive layer
Directly connected to the electrodes, and drive from above the heating resistor.
A thermal head, wherein a region up to an IC is continuously covered with a protective layer .