JPH0239955A - Thermal head - Google Patents

Abstract

PURPOSE:To make a printing dot sharp by equalizing the electric line-of-force distribution between electrodes and uniformizing the generation of heat of a heating resistor by arranging a lead electrode constituted of a common electrode and individual electrodes so as to set the opposed gap between the common electrode and each of the individual electrodes to a definite value. CONSTITUTION:An insulating substrate 1 is composed of ceramic and a glaze layer 2 is constituted of a glass material. A lead electrode is constituted of a comb tooth-shape common electrode 31a and a large number of individual electrodes 31b and arranged so that each of the gaps between the common electrode 31a and the individual electrodes 31b, that is, each of the orthogonal distances between the surface of the common electrode 31a and the surfaces of the individual electrodes opposed thereto is set to a definite value. Therefore, when voltage is applied between the electrodes 31a, 31b, the distribution of an electric line of force becomes equal and the heating resistor 41 in contact with the lead electrode 31 generates heat uniformly. It is unnecessary to necessarily form the lead electrode 31 into a horseshoe shape and any shape making the lead electrode gap (g) constant may be employed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal head used in recording devices such as facsimiles and printers, and particularly relates to a thermal head in which heating resistors are linearly arranged on an insulating substrate, This invention relates to a heat-generating substrate of a thermal head, which records by selectively heating a heat-generating resistor by bringing a heat-sensitive recording paper into contact with the upper surface of the heat-sensitive recording paper.

[Conventional technology]

4 and 5 are diagrams showing a heat generating substrate of a conventional thermal head disclosed in, for example, Japanese Patent Application Laid-Open No. 54-110848, with FIG. 4 showing a sectional view and FIG. 5 showing a partial plan view.

In the figure, (1) is an insulating substrate such as ceramic, (2
1 is a glaze layer, and (3) is a lead electrode, which is constructed by alternately arranging a plurality of comb-like common electrodes (3a) and linear individual electrodes (3b) facing each other. (
4) is a heating resistor, and (5) is a protective film glass.

Next, the manufacturing method and operation of this heat generating board will be explained. 4 and 5, a glaze layer (2) made of a glass material or the like is printed on an insulating substrate (1), and a conductor such as Au (gold) is printed on this brace m (21). The paste is printed and fired to form lead electrodes (3).

Next, a resistance paste mainly composed of Ru02 (ruthenium oxide) or the like is printed and fired to form a heating resistor (4). Next hp20. , Sin, etc. is printed and fired to cover the heating resistor (41) to form a protective film glass (5).

The heat-sensitive substrate of the thermal head manufactured as described above is prepared by applying a voltage to the common electrode (3a) and applying a voltage to the individual electrodes (3a).
b) is selectively turned ON and OFF, the heat generating resistor (4) is turned on, for example, by turning off the heat generating element (4a) shown in the shaded area in FIG.
) generates heat. The heat generated by the heating element (4a) is transferred to the upper protective film glass (5) and is partially heated.

Due to this heat, the thermal paper (not shown) between the platen roller (not shown) and the protective film glass (5) develops color, forming dots.

Figure 6 shows the dots (
This is an example of 6), in which after the printing of the first line is completed, the thermal paper steps one line and printing of the second line is performed.

[Problem to be solved by the invention]

Since the conventional thermal head is configured as described above, it has the following problems.

In other words, it is composed of a plurality of interdigitated common electrodes (3a) and linear individual electrodes (3b) that are alternately arranged facing each other, but when a voltage is applied to these electrodes (3m) (3b), , the gap between the lead electrodes, that is, the electrodes facing each other (
Since the perpendicular distance between the planes 3a and 3b is not constant, the distribution of electric lines of force ■ is not uniform as shown in Fig. Temperature unevenness occurs. This is remarkable in the sub-scanning direction of the dots. Therefore, there is a problem that the printed dots on the thermal paper become unclear.

This invention was made in order to solve the above-mentioned problems, and the gap between the common electrode and the individual electrodes forming the lead electrodes is arranged at a constant value to equalize the distribution of electric lines of force. It equalizes heat generation and makes printed dots clearer.

[Means to solve the problem]

The thermal head according to the present invention includes an insulating substrate, a heating resistor formed on the insulating substrate, and a lead electrode made of a common electrode and individual electrodes for applying a voltage to the heating resistor, and the lead electrode The gap between the opposing sides is set to a constant value.

[Effect]

In the thermal head of this invention, the facing gap between the lead electrodes, which are composed of a common electrode and individual electrodes, is arranged at a constant value, so that the distribution of electric lines of force between the electrodes is equalized, and the heat generated by the heating resistor is uniform. The printed dots become clearer.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3. FIG. 1 is a plan view showing a part of the heat generating substrate, and FIG. 2 is a detailed view of the lead electrode (2).

In FIG. 1, (1) is an insulating substrate made of ceramic or the like, (2) is a glaze layer made of glass material, 01
) is a lead electrode composed of a comb-like common electrode (31a) and a plurality of individual electrodes (31b), and the gap (g) between the lead electrodes shown in FIG. 2 is kept at a constant value. It is arranged in a horseshoe shape. (b) is a heating resistor, (5) is k1203. It is a protective film glass whose main component is SiO□.

As shown in FIGS. 1 and 2 above, the basic configurations of the insulating substrate (1), glaze layer (2), heating resistor (2), and protective film glass (6) of the present invention are the same as those of the conventional example. However, the shape and arrangement of the lead swan are different from the conventional example.

That is, unlike the conventional example shown in FIG. As shown in FIG. 2, the gap (g) between the common electrode (31a) and the individual electrode (31b), that is, the opposing electrode (3
These electrodes (31m) (1a) (31m) (
31b), the distribution of the lines of electric force becomes uniform as shown in FIG. 3, and the heating resistor (6) in contact with the lead electrode 6 is heated evenly.

In the above embodiment, the shape of the lead electrode 8iiC3υ is shown as a horseshoe shape, but it is not necessarily necessary to be a horseshoe shape, and any shape that allows the lead electrode gap (g) to be constant may be used.

〔Effect of the invention〕

As described above, the present invention includes a resistor and a lead electrode for applying a voltage to the heating resistor, and the gap between the opposing lead electrodes, that is, the perpendicular distance between the opposing lead electrode surfaces is Since they are arranged at a constant value, when a voltage is applied to the lead electrode, the distribution of electric lines of force becomes uniform, and the heat generation of the heating resistor in contact with the lead electrode becomes uniform.

[Brief explanation of the drawing]

1 to 3 are diagrams of a thermal head device according to an embodiment of the present invention, in which FIG. 1 is a plan view showing a part of a heat generating board, FIG. 2 is a diagram of lead electrodes, and FIG. 3 is a diagram showing electric power. An explanatory diagram showing the line distribution, Fig. 4 is a cross-sectional view of a conventional thermal head heating board, Fig. 5 is an exemplary diagram showing the heating state of the heating resistor, Fig. 6 is an explanatory diagram of printed dots, and Fig. 7 is a conventional diagram. FIG. 2 is an explanatory diagram showing the electric force line distribution of (1) is an insulating substrate, C11l is a lead electrode, (31a)
is a common electrode, (31b) is an individual electrode, and the curve is a heating resistor.
The phrase is the heat generating substrate, and (g) is the gap. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] An insulating substrate, a heating resistor formed on the insulating substrate, a common electrode and individual electrodes for applying a voltage to the heating resistor, and the opposing gaps between the common electrode and the individual electrodes are arranged at a constant value. A thermal head characterized by: