JPS5889380A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a highly accurate thermal head easily by reducing the number of fine positioning times by a method in which a heating resistor film and a conductor film are formed on the surface of a columnar insulating base and a spiral groove to divide these films is formed. CONSTITUTION:A Ni-Cr alloy film is deposited on the peripheral surface of a 3mm.-diameter alumina insulating base 10 to form a heating resistor film 11, and a conductor, e.g., Au, etc., is deposited on the heating resistor film 11 by a vapor diposition method to form a conductor film 12. Then, the heating resistor film 11 and the conductor film 12 are scraped away by means of a disc blade cutter or laser beams to form a spiral groove 13. The conductor film 12 is then removed by etching to a dot width in the parallel direction to the shaft of the insulating base 10 to form a heating dot section 11a. Then, the insulating base 10 on the back of the heating dot section 11a is scraped down, a wear-resistant film is formed on the dot section 11a, and a lead wire is connected to conductors 12a on both sides of the dot section 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print head for a thermal printer, and particularly to a thermal head having a structure in which several heat-generating dots are arranged in a row on one plate.

Conventional printheads include flat and cylindrical printheads.

The flat plate type has a structure as shown in FIG.

This flat thermal head has a protrusion formed on an insulating substrate 1, a heating resistor film 2 such as NiCr formed on the surface by vacuum evaporation, and a conductor film 3 such as Au formed on the surface. After forming a pattern by photolithography, a wear-resistant film 4 such as tantalum oxide is formed thereon by sputtering. When in use, a voltage is applied to both ends of the conductor film 3 to cause the heating element dots 2a to generate heat, and the thermal paper 6 slides on the abrasion resistant film 4.
It produces color. However, with this structure, in order to obtain sufficient pressing pressure against the paper, it is necessary to bulge the substrate only at the heating dots of the thermal head during manufacturing, which complicates the process and increases the manufacturing cost.

The cylindrical shape is as shown in FIG. 2, and the structure of the membrane is the same as that of the flat plate shape. That is, a heat generating resistor film 7 is formed on a cylindrical insulating base 6, a conductor film 8 is formed thereon, and an abrasion resistant film 9 is further formed thereon. 7a is a heating element dot portion. Since this cylindrical thermal head utilizes a circumferentially curved surface, contact with the paper 6 is ensured as it is, and there is no need to raise only the dot portions, so it is advantageous over the flat plate type. However, forming the pattern of the heating element3
Since photolithography must be performed on a curved surface when preparing a sample, it is technically difficult and requires a lot of man-hours.

Furthermore, when manufacturing the conventional thermal head, fine alignment must be performed three times during etching of the conductor pattern, etching of the heating element, and three times when attaching the lead wires (in the case of a flat plate type, the dots are further raised). (Adding time alignment), it took a lot of man-hours.

Furthermore, conventionally, the resistance value of the heating element generally cannot be changed for each thermal head because the dot size cannot be changed for each thermal head.
It is uniquely determined at the time of thin film formation, and variations in resistance value during thin film formation have a large negative effect on the overall yield during manufacturing.

In view of the above points, it is an object of the present invention to provide a thermal head that utilizes the advantages of the cylindrical shape while solving the manufacturing difficulties.

To achieve this object, the present invention provides a spiral structure that rotates around the axis of an insulating substrate on which a heating resistor film and a conductor film are formed, and separates the heating resistor film and the conductor film into a plurality of regions. This groove has been formed.

The structure and manufacturing method of one embodiment of the present invention will be described below with reference to FIGS. 3 and 4. In the figure, 1o is an insulating substrate made of alumina and having a diameter of 3 mm. A NiCx alloy is deposited on the circumferential surface of the insulating substrate 100 to form a heating resistor film, and Au is deposited as a conductive material on the heating resistor film 11 to form a conductor film 12. In this way, the heating resistor film 11 is formed on the insulating substrate 10. After the conductive film 12 is formed, a groove is cut to a depth such that a portion of the insulating substrate 10 is scraped using a cutter blade of a disk blade or a laser beam, thereby forming a spiral groove 13.

This groove cutting can be easily performed by keeping the blade fixed and feeding the insulating base 1o in the axial direction while rotating it. The pitch of the feeder is the dot pitch of the heating element 0.36
■It is.

Next, as shown in FIG. 4, in order to create the heating element dot portion 11a, dots with a width of 0 are made in a direction parallel to the axis of the insulating base 10.
．． 3. The conductive film 12 is removed by etching 511.-7'. Further, the insulating base 10 on the back side of the heating element dot portion 11a is rubbed off together with the heating resistor film 11 and the conductor film 12.

Next, a wear-resistant film of Ta2O6 is formed on the heating element dot portion 11a by sputtering. Furthermore, heating element dot part 1
Lead wires for voltage application are connected to each end of the conductive portion 12a at both ends of 1a. The thermal head of this embodiment is manufactured as described above. In the thermal head of this embodiment, fine positioning only needs to be performed once when attaching the lead wires. In other words, the etching of the conductor pattern (formation of the heating element dots 11 & , it is possible to easily achieve accurate pitch dimensions.

In addition, by measuring the surface resistance value of each element after forming the heating resistor film 11, and after classifying the elements into ranks, the etching width of the conductor film 12 is changed according to each rank, so that the final resistance value can be easily maintained at a constant value. - The manufacturing yield can be greatly improved.

Also, since part of the insulating base 10 is removed when cutting the groove,
Thermal separation between dots is also good, and printing smearing is improved.

Note that the materials of each member may not be those listed in the examples; for example, for the insulating base 1,
In addition to alumina, various other materials such as oxides such as 7-orsterite and various types of glasses such as silica can be used, and as the resistance heating element film 11, there are many other materials such as Ta, TaN, and W in addition to NiCr. The same applies to the conductor film 12. In addition, since the outer periphery of the insulating substrate 1° only needs to have a cylindrical shape when grooves are cut, it is convenient when forming the resistance heating element film 11, for example.
Even if there is a hole inside, the effect will not be affected. Furthermore, the resistance heating element film 11 and the conductor film 12 do not need to be formed over the entire circumference of the insulating base;
It is sufficient if the resistive heating element film 11 is located at the location where the etching is performed. In this case, as shown in FIG.
0 remains cylindrical.

As for the groove cutting method, the spiral cutting method shown in Figure 6 is the easiest cutting method considering the mechanical movement.
It is also an effective method for cutting at a high speed.

On the other hand, if the groove 13' is repeatedly cut in a direction perpendicular to the cylinder axis as shown in FIG. Therefore, the effect is halved.

Since the thermal head of the present invention is configured as described above,
Only one fine alignment is required, making it easy and inexpensive to manufacture.Also, by changing the etching width of the conductor film, the final resistance value can be easily adjusted to a constant value, greatly improving manufacturing yield. It can be used as dust, and its industrial value is high.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of a conventional thermal head;
3 and 4 are perspective views of the manufacturing process of a thermal head according to an embodiment of the present invention, and FIGS.
The figure is an explanatory diagram of the groove cutting method. 1o...Insulating base, 11...Resistive heating element film, 11a...Heating element dot portion, 12...
... Conductor film, 12a... Conductive part, 13...
···groove. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 3 Figure 4 O Figure 5 f, 1 6V4 f3'

Claims (1)

[Claims] A heating resistor film formed on the surface of a cylindrical or approximately cylindrical insulating substrate, a conductor film formed on the heating resistor film, and the conductor film being removed in a direction parallel to the axis of the insulating substrate to remove the heating element. The resistor film is exposed and the heat generating portion is formed on the surface, and a spiral groove is formed to rotate around the axis of the insulating base and to separate the heat generating resistor film and the conductor film into a plurality of regions. It will form ~ Maru Head.