JP2002002005A - Thick film type thermal printing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high-speed printing by reducing adhesion/piling of paper dust in a thermal head printing head in which many first electrode patterns 3 extending like teeth of a comb from a common electrode 2 and second electrode patterns 5 extending from many discrete electrodes 4 are formed to a head substrate 1 to bring one electrode patterns of both electrode patterns into between the other electrode patterns, and at the same time a heating resistor 6 is formed in a thick film to linearly extend to traverse each of the electrode patterns 3 and 5. SOLUTION: A distance S between one edge 6a of the heating resistor 6 to one edge 2a of the common electrode 2 is set smaller than conventionally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film type thermal print head in which a heating resistor for printing is formed to be a thick film in a thermal print head.

[0002]

2. Description of the Related Art In general, a thick film type thermal print head of this type has been well known in the related art, and has been disclosed in FIGS.
As shown in FIG. 1, on the surface of the insulating head substrate 11, a common electrode 12, a large number of first electrode patterns 13 extending in a comb-like shape from the common electrode 12, and a large number of individual electrodes 1
4 and a second electrode pattern 15 extending narrowly from each individual electrode 14 by the first and second electrode patterns 13 and 1.
5 is formed of gold so that one electrode pattern is inserted between the other electrode patterns so as to have a thickness of 1 μm or less, and the first electrode pattern 13 and the second electrode pattern 15 are both formed. The heating resistor 16 extending in a line so as to cross it is formed as a thick film by screen printing or the like. Note that reference numeral 17
Is a protective film that covers the entire common electrode 12, the electrode patterns 12, 15 and the individual electrodes 14.

In the thermal print head of this configuration, since the common electrode 12 is formed of gold, the resistance in this longitudinal direction (that is, the longitudinal direction of the linear heating resistor 16) is large. Conventionally, the conductive film 18 made of silver having good conductivity is formed on the capacitor electrode 12 made of gold because unevenness occurs.
The resistance value of the common electrode 12 along the longitudinal direction is reduced by stacking and forming a thick film by screen printing or the like, but a conductor of a silver thick film is formed on the common electrode 12 of gold. When the films 18 are formed in layers, the portion of the conductor film 18 projects considerably from the surface of the head substrate 11.

For this reason, when the printing paper A 'is pressed against the heating resistor 16 on the surface of the head substrate 11 by the platen roller B', the surface of the head substrate 11 is moved from the surface of the head substrate 11 as described above. There is a case where the printing paper A 'comes into contact with the portion of the conductor film 18 which is considerably protruded.

Therefore, conventionally, in order to completely avoid this contact, the distance S 'from one end 16a of the heating resistor 16 to one end 12a of the common electrode 12 made of gold is increased. Since the common electrode 12 made of gold is configured to be as far as possible from the heating resistor 16, there are problems as described below.

[0006]

By the way, the heat generated in the heating resistor at the time of printing is directly transmitted to the head substrate and is dissipated, and in addition to being transmitted through the first electrode pattern and the common electrode. Is dissipated by the heat transfer to the head substrate and the heat transfer to the head substrate through the second electrode pattern and the individual electrodes.

In this case, the distance S 'from one edge of the heating resistor to one edge of the common electrode is represented by:
As described above, when the size is increased, the first
As the length of the electrode pattern increases, the heat transfer through the first electrode pattern decreases, and the amount of heat radiation from the first electrode pattern and the common electrode decreases. The temperature distribution in the direction becomes a gentle curve such that the temperature gradually decreases.

On the other hand, the printing paper A 'pressed against the heating resistor by the platen roller B' moves in the direction of the common electrode as indicated by an arrow C 'as printing proceeds. Therefore, if the curve of the temperature distribution in the direction from the heating resistor to the common electrode is gentle such that the temperature gradually decreases, the time for the printing paper A 'to contact a high-temperature location increases. Therefore, there is frequent occurrence of the problem that paper cake is generated and the paper cake adheres and accumulates on the thermal print head side, and the phenomenon that the paper cake adheres and accumulates is caused by the printing length per unit time. That is, there is a problem that the printing speed increases in proportion to the printing speed.

Incidentally, in the conventional thermal print head, the distance S 'from the heating resistor 6 to the common electrode 2 is about 200 to 300 microns.
The printing speed is limited to 3 inches / second, and the printing speed cannot be further increased.

It is a technical object of the present invention to provide a thermal print head which solves this problem.

[0011]

In order to achieve this technical object, the present invention provides a method of forming a plurality of first electrode patterns extending in a comb-like manner from a common electrode on a surface of a head substrate. A second electrode pattern extending from the electrode is formed such that one of the two electrode patterns enters between the other electrode patterns,
In a thermal print head formed by forming a thick-film heating resistor extending linearly across these electrode patterns, the distance from one edge of the heating resistor to one edge of the common electrode is set to be longer than before. It is characterized by being made smaller. Is the thing.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In this figure, reference numeral 1 denotes a head substrate made of an insulator such as ceramic. A common electrode 2 extending in the longitudinal direction is provided on the surface of the head substrate 1 and a comb-like shape is formed from the common electrode 2. The first and second electrode patterns 3, a large number of individual electrodes 4, and the second electrode patterns 5, which extend narrowly from the individual electrodes 4, are formed by the first and second electrodes.
One of the electrode patterns 3 and 5 is formed of gold with a thickness of 1 μm or less so as to enter between the other electrode patterns. A heating resistor 6 extending linearly across both of the patterns 5 is formed as a thick film by screen printing or the like.

On the common electrode 2, a conductive film 8 made of a metal material having good conductivity, for example, silver, is formed in a thickness of about 10 to 15 μm by screen printing or the like so as to be overlapped. I have.

Further, on the surface of the head substrate 1,
The common electrode 2, each first electrode pattern 3, each individual electrode 4, each second electrode pattern 5, heating resistor 6, and conductor film 8
A protective film 7 made of glass or the like is formed so as to cover the entire surface.

The distance S from one end 6a of the heating resistor 6 to one end 2a of the common electrode 2 is made smaller than a conventional value (for example, about 200 to 300 microns), while the common electrode 2 is made smaller. The conductor film 8 formed so as to be overlapped with the heating resistor 6 is configured to be separated from the heat generating resistor 6 by at least the distance S smaller than that in the related art.

As described above, since the distance S from the one end 6a of the heating resistor 6 to the one end 2a of the common electrode 2 is reduced, the length of each first electrode pattern 3 is shortened. The heat transfer through the first electrode pattern 3 is increased, and thus the first electrode pattern 3
And the heat radiation from the common electrode 2 increases,
As shown by the curve D in FIG. 3, the temperature distribution in the direction from the heating resistor 8 toward the common electrode 2 is such that the temperature drops more sharply than the conventional temperature distribution curve D '(shown by a two-dot chain line). It becomes such a curve.

Thus, when the printing paper A pressed against the heating resistor 2 by the platen roller B is moved in the direction of arrow C while printing, the printing paper A
Therefore, the time for contacting a place with a high temperature is shortened, and the generation of paper lees, and further, the adhesion and deposition of paper lees can be surely reduced.

On the other hand, the conductive film 8 formed on the common electrode 2 is separated from the heat generating resistor 6 by at least the distance S smaller than that of the conventional one, so that the common electrode 2 generates heat. By approaching the resistor 2, it is possible to reliably prevent the printing paper A from coming into contact with the portion of the conductor film 8 formed on the common electrode 2.

In particular, according to experiments by the present inventors, the distance S from one end 6a of the heating resistor 6 to one end 2a of the common electrode 2 is set to, for example, 200 mm in the width W of the heating resistor 6. If it is micron,
When the width W of the heating resistor 6 is set to 0.25 to 0.75 so that the width of the heating resistor 6 is set to 50 to 150 microns, the width of the heating resistor 6 in the direction from the one edge 6a toward the common electrode 2 is reduced. Since the temperature at the location of 100 microns is much lower than the conventional one, the printing length per unit time, that is, the printing speed, is 5 to 6 inches /
It could be faster than a second.

[0021]

Therefore, according to the present invention, the adhesion of paper lees
In addition to being able to perform high-speed printing by reducing the amount of deposition, there is an effect that printing paper can be prevented from contacting the conductive film and printing speed can be greatly increased.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a main part of a thermal print head according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a diagram showing a temperature distribution.

FIG. 4 is an enlarged view showing a main part of a conventional thermal print head.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head board 2 Common electrode 2a One edge of common electrode 3 First electrode pattern 4 Individual electrode 5 Second electrode pattern 6 Heating resistor 6a One edge of heating resistor 7 Protective film 8 Conductive film

Claims (4)

[Claims] A first electrode pattern extending in a comb-like shape from a common electrode and a second electrode pattern extending from a large number of individual electrodes on the surface of the head substrate; A thermal print head comprising: an electrode pattern formed between the other electrode patterns, and a thick-film heating resistor extending in a line extending across each of the electrode patterns; A thick-film type thermal print head, wherein the distance from one edge of the body to one edge of the common electrode is smaller than that in the related art. 2. The conductor film according to claim 1, wherein the conductor film formed on the common electrode has at least a distance from one end of the heating resistor to one end of the common electrode smaller than that of the conventional art. A thick-film thermal printhead characterized by being kept away from the heating resistor. 3. The heating resistor according to claim 1, wherein a distance from one edge of the heating resistor to one edge of the common electrode is set to a width of 0.25 to 0.75 of the heating resistor. A thick-film thermal printhead characterized by: 4. A thick film type thermal print head according to claim 3, wherein the printing speed of said thermal print head is 5 to 6 inches / second or more.