JPH04314553A - Production of thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head little affected by thermal stress and excellent in thermal responsiveness and printing performance by forming the heating body thin film divided into a plurality of dot areas on the end face of a base plate with a highly accurate shape characteristic and arranged structure. CONSTITUTION:After forming conductive copper patterns and thin copper films 20 and 30 for use on a common electrode on both the faces of an insulated base plate 10, a groove 12 is formed in the end face of the base plate, which is then divided into a plurality of dot areas 13. A heating body thin film 40 is deposited on the dot area 13 by sputtering. To form the heating body thin film 40 after the formation of the groove 12, this film 40 is so shaped as to conform exactly with the surface of the dot area 13 and each adjacent dot is separated by the groove. The adhesion to the end face of the base plate is also satisfactory. For this reason, a highly clear printed surface is obtained stably over an extended period of time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head for a thermal printer used in facsimiles, printers, various recording instruments, and the like.

0002

2. Description of the Related Art In a conventional thin film type thermal head, as shown in FIG. IC5 to
A predetermined portion of the thermal paper 53 supplied thereon is pressed against the ceramic substrate 51 by the platen 54, while heating printing is performed using a heating element. At this time, platen 5
A heating element 55 that receives the force from the ceramic substrate 51 and dissipates the heat generated in the ceramic substrate 51 is attached to the ceramic substrate 51.
It is attached to the back of the. Further, a collective board 57 that collects common signals for a plurality of ICs 52 and forms wiring to the socket 58 is arranged adjacent to the ceramic board 51. Note that the IC 52 is covered with a cover 56.

In order to maintain the high-speed printing performance of this type of thermal head, a tip type thermal head is used in which a narrow heating section is placed between the electrode films formed on the surface of the ceramic substrate as close as possible to the end surface of the substrate. Printer head is in use. However, in a method in which the flat surface of a ceramic substrate is used as a heat generating part and a platen is used to press thermal paper against the heat generating part, a space is required for pressing the platen, resulting in an overall large-sized product.

The ceramic substrate 51 is an effective material with excellent heat resistance because it is heated to a high temperature when forming conductive patterns and heating elements, and its working surface is exposed to a high temperature atmosphere when the thermal head is operated. It is. However, when a ceramic substrate is used, the heat capacity of the substrate is large and the thermal responsiveness is low. As a result, power consumption increases in order to raise the temperature of the action part to a predetermined temperature.

[0005] Furthermore, in order to eliminate the effects of warping of the substrate due to heat during operation and to perform even printing, it is necessary to press the platen 54 against the ceramic substrate 51 with a large force of, for example, more than 4 kg. Therefore, the heat sink 55 that acts as a reaction force receiver becomes even larger. Since the thermal paper 53 is fed between the platen 54 and the ceramic substrate 51 which are pressed with great force, a drive motor with high power is required for the paper feeder.

Furthermore, in order to collect signals for a plurality of ICs 52, an aggregate substrate separate from the ceramic substrate 51 is required. This increases the number of parts, complicates assembly work, and increases product costs.

[0007] As a solution to these drawbacks, FIG.
As shown in Japanese Patent Application No. 2-5460, a structure in which conductive patterns are formed on both sides of a resin substrate and a heating element is provided on the end face has been proposed.

The newly proposed thermal head has a copper pattern 62 as a conductor and a copper thin film 63 for a common electrode formed on both surfaces of the upper portion of a resin substrate 61, respectively. A heating element 64 is formed on the end surface of the resin substrate 61 in a state connected to the copper pattern 62 and the copper thin film 63. On the other hand, on both sides of the lower part of the resin substrate 61, a circuit section 65 that functions as a collective wiring is printed.
An IC 66 that connects the circuit section 65 and the heating element 64 is mounted on one side of the resin substrate 61.

Resin board 61 on the opposite side from the IC 66 mounting side
A heat sink 67 made of a metal with excellent thermal conductivity, such as aluminum, is attached to the surface. The copper thin film 63 formed on the surface of the resin substrate 61 on the heat sink 67 mounting side
By connecting the heat dissipating body 67 to the heat dissipating body 67, it functions as a heat dissipating path.

A socket 68 is provided at the bottom of the resin substrate 61 to connect the thermal head to a predetermined power supply and controller. Further, in order to prevent the heating element 64 from being worn out due to passage of a heat-sensitive material such as thermal paper or an ink film, a wear-resistant protective film 69 is laminated on the heating element 64.

As shown in FIG. 3, this type of thermal head is arranged at right angles to the running direction of the thermal paper 70, that is, so that the end surface of the resin substrate 61 faces the surface of the thermal paper 70. Then, printing is performed on the thermal paper 70 fed out from the paper feed roll 71 using a heating element 64 located on the end surface of the resin substrate 61. At this time, the heating element 64
The contact state between the heat-sensitive paper 70 and the heat-sensitive paper 70 is maintained by a slight force such that the heat-sensitive paper 70 is pressed against the heating element 64 by a brush 72 that also serves as an anti-static agent. The printed thermal paper 70 is sent out of the system by a feed roll 73.

Since the heating element 64 formed on the end surface of the substrate 61 comes into contact with the thermal paper 70 in this way, the thermal capacity of the substrate 61 can be made extremely small, and the power consumption required for printing the print can be reduced to a small amount. . In addition, since the end face with small thermal deformation is used as the active surface, even if the board is made of a material with low heat resistance such as resin, the deflection of the board 61 is suppressed, and the contact between the heating element 64 and the thermal paper 70 is suppressed. Since the condition is maintained well, a clear printed surface can be obtained. Moreover, it is no longer necessary to press the thermal paper with a large force using a platen, which is required in conventional thermal printers, and the apparatus can be made more compact.

[0013]

The heating element 64 is made up of a large number of dots in order to perform predetermined printing on the thermal paper 70. Then, the dots of the heating element 64 corresponding to the area to be printed are energized to raise the temperature, and the thermal paper 70 is colored according to a predetermined pattern. This coloring or thermal transfer when printing on plain paper using an ink ribbon is affected by the shape and arrangement of the dots, and affects the clarity of the printed surface.

In this regard, forming the heating element 64 consisting of a plurality of dots on the end surface of the substrate 61 requires some ingenuity. For example, when forming a heating element on the surface of a conventional substrate, dots are formed in a predetermined pattern by sputtering a resistive material after applying appropriate masking. By sputtering, the distance between adjacent dots is set to 15
It is possible to reduce the thickness to about μm. However, the spacing between adjacent conductive patterns is limited to about 35 μm. Therefore, heat transfer from the conductive copper pattern to the dots becomes non-uniform, and the amount of heat tends to be distributed on both sides of each dot. Furthermore, the dot spacing tends to be irregular, resulting in a printed surface with poor clarity.

The present invention was devised to solve these problems, and by adding innovations to the heating element thin film forming process and the dot forming process, a heating element consisting of a plurality of dots can be insulated. The purpose is to provide them in an accurate shape and arrangement on the end face of the substrate.

[0016]

[Means for Solving the Problems] In order to achieve the object, the manufacturing method of the present invention involves forming a conductive copper pattern and a common electrode copper thin film on both sides of an insulating substrate, and then forming a conductive copper pattern and a common electrode copper thin film on both sides of an insulating substrate. The method is characterized in that a plurality of grooves are carved at a pitch, and then a heating element thin film is provided on the end face of the insulating substrate.

[0017] Here, the grooves separating adjacent dots can be formed by cutting the end portion of the insulating substrate with a laser or the like. After the grooves are carved, T
By sputtering a resistive material such as a mixture, a heating element consisting of a plurality of dots is formed. Alternatively, slit processing can be performed after sputtering the resistive material constituting the heating element thin film.

[0018]

[Operation] In the present invention, a heating element thin film is formed on the end surface of the substrate after the grooves have been carved. When applying resistance material to this grooved end surface by sputtering, etc.,
In the formed heating element thin film, adjacent dots are separated from each other by grooves. That is, since the heating element thin film is formed on the end surface in which the grooves have been previously carved, a plurality of dots with good shape characteristics and arrangement form can be obtained corresponding to the sections of the end surface partitioned into a plurality of sections by the grooves. Moreover, the formed heating element thin film has a uniform thickness with substantially no thickness variation at the center and edges of each end face section. Further, since it is not necessary to make a slit in the end face of the substrate after forming the heat generating thin film, the heat generating thin film does not peel off from the end face of the substrate.

[0019]

[Examples] The present invention will be specifically explained below by way of examples with reference to the drawings. In this example, a plate material made of polyimide resin with good insulation properties and having a thickness of 75 μm was used as the substrate material. After metalizing both sides of the resin substrate 10 along a predetermined pattern, as shown in FIG.
As shown in FIG. 1, a thin copper film 20 serving as a conductive copper pattern was formed on one surface of a resin substrate 10 by electroplating. The copper thin film 20 has a film thickness of approximately 25 μm, and is attached to the resin substrate 1.
From the continuous parts 21 connected to each other near the end face 11 of 0,
Branch portion 2 divided into a plurality of conductive paths toward the center of the board 10
2. Further, on the opposite surface of the resin substrate 10, a copper thin film 30, which will become a copper thin film for a common electrode, was similarly formed by electroplating.

Next, the end portion of the resin substrate 10 on which the copper thin films 20 and 30 have been formed is cut with a laser to make a slit with a width of 15
μm, depth 1.5mm groove 12 with pitch 0.125mm
It was engraved with. The continuous part 21 of the copper thin film 20 is separated by the groove 12, and each branch part 2 is separated as shown in FIG. 4(b).
Each second becomes a mutually independent current-carrying section 23. Further, the width of the current-carrying portion 23 is determined by the width of each dot section 1 separated by the groove 12.
It has the same width as 3.

The end surface 11 of the insulating substrate 10 was divided into a plurality of dot sections 13 separated by grooves 12. A tantalum mixture was sputtered onto the surfaces of these dot sections 13 to form a heating element thin film 40 having a thickness of 0.2 μm. In the heating element thin film 40, adjacent dot sections 13 are separated by grooves 12, and current-carrying parts 2
It had the same width as 3. Further, the thickness of the heating element thin film 40 was substantially unchanged at the center and edges of the dot section 13, and was within ±10% of the target film thickness of 0.2 μm. Therefore, the current supplied from the current-carrying section 23 to the heating element thin film 40 is made uniform, and the heating element thin film 40 formed on each dot section 13 is heated with a uniform temperature distribution in the width direction for each dot section 13. did.

In another embodiment, a similar heat generating thin film 40 is formed over the entire end surface 11 of the insulating substrate 10 by sputtering, and then the grooves 12 are formed.
The copper thin film together with the heating element thin film 40 was cut into dot sections 13 to form current-carrying parts 23. In this case as well, a heating element thin film 40 having the same shape and thickness and regularly partitioned was obtained.

After the heating element thin film 40 consisting of a plurality of dots is formed on the end face in this way, the circuit section 65, IC 66, socket 68, heat radiator 68, heat radiator, etc. are mounted on the resin substrate 10 as in FIG. It was installed as a thermal head. In addition,
In order to prevent the heating element thin film 40 from being worn out by the passage of a heat-sensitive body such as thermal paper or ink ribbon, Ta2O5
A wear-resistant protective thin film containing as a main component was laminated on the surface of the heating element thin film 40.

The fabricated thermal head was arranged at right angles to the running direction of the thermal paper 70, that is, so that the end surface of the resin substrate 10 faced the surface of the thermal paper 70, as in the case described with reference to FIG. . Then, printing was performed on the thermal paper 70 fed out from the paper feed roller. The resulting printed surface remained very clear for a long time.

In the above embodiments, polyimide resin was used as the insulating substrate material. However, the present invention is not limited to this, and other heat-resistant resins such as Teflon, ceramic sheets, insulated thin metal plates, etc. can also be used. Moreover, as the conductive thin films 20 and 30,
It can be formed by an appropriate method such as CVD or PVD without electroplating, and tin or gold can be used as the thin film forming material in addition to copper. In addition, the heating element thin film 4
Even if it is zero, it can be formed from a metallic resistance material such as a Cr-Ni alloy, an inorganic resistance material, etc. by an appropriate method such as sputtering, CVD, vapor deposition, or plating.

After forming the conductive thin films 20 and 30, the substrate 1
The means for carving a groove on the end of the 0 is not limited to the above-mentioned laser cutting, but a mechanical method using a grinding wheel, a knife, etc. can also be adopted.

[0027]

As explained above, in the present invention, the end face is divided into a plurality of sections by carving grooves in the end of the insulating substrate after forming the copper thin film, and then the heating element thin film is formed. is laminated on the end surface. Therefore, the formed heating element thin film has an accurate shape and arrangement, and has a uniform film thickness. Furthermore, since the heating element thin film is not divided into a plurality of dot sections after being formed, manufacturing is not only facilitated, but also the adhesion of the heating element thin film to the end surface of the substrate is improved. When printing is performed using the thermal head produced in this way, the amount of heat applied to the heat sensitive body etc. is averaged over the dot surface, and a printed surface with high clarity can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows a thermal printer incorporating a conventional thermal head.

FIG. 2 shows a thermal head in which a heating element is provided on the end surface of a substrate, which was previously proposed by the present inventors.

FIG. 3 shows a state in which printing is performed on thermal paper using the thermal head of the previous application.

FIG. 4 is a diagram for explaining the manufacturing process of the thermal head according to the present invention.

[Explanation of symbols]

10 Resin board 11 Board end 12 Groove 13 Dot division 20 Copper thin film (
21 Continuous part 22 Branch part 23 Current-carrying part 30 Copper thin film (for common electrode)
40 Heating element thin film

Claims (4)

[Claims] 1. After forming a conductive copper pattern and a common electrode copper thin film on both sides of an insulating substrate, a plurality of grooves are carved at a predetermined pitch on the edge of the insulating substrate, and then a heat generating layer is formed on the end surface of the insulating substrate. A method for manufacturing a thermal head, characterized by providing a thin body film. 2. After forming a conductive copper pattern and a common electrode copper thin film on both sides of an insulating substrate, a heating element thin film is provided on the edge of the insulating substrate, and then a plurality of heating element thin films are formed on the edge of the insulating substrate at a predetermined pitch. A method for manufacturing a thermal head characterized by carving grooves. 3. A method for manufacturing a thermal head, wherein the groove according to claim 1 or 2 is formed by cutting an end portion of the insulating substrate with a laser. 4. The heating element thin film according to claim 1 or 2,
A method for manufacturing a thermal head, characterized in that it is formed on an end surface of an insulating substrate by sputtering.