JPS6248572A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head having a high response speed, having two or one heat point in each print dot and free of irregularities in printed density, by providing a resistor having a cross-sectional shape of a part of a circle and provided on an insulating substrate, and electrode conductors provided in the shape of comb teeth extending on the substrate across the resistor. CONSTITUTION:A resistor 3 is provided on the insulating substrate 1 in the shape of a part of a cylinder, and the electrode conductors 2a, 2b are provided by applying an inorganic gold paste by printing, followed by firing. With a voltage impressed between the conductors 2a, 2b, a larger quantity of recording current flows through the resistor 3 at a part near the surface thereof, resulting in a rapid rise in the surface temperature and a high response speed. Host points 3c at which the head makes contact with a thermal recording paper are two points at a top part 3a of the resistor 3 on both sides of the conductor 2b. The signal current flows in the maximum quantity to the hot points 3c, so that the hot point parts are rapidly heated to a temperature according to the gradation of the printed density, without generating irregularities in temperature of the hot points 3c. Accordingly, a printing suitable for recording gradations can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thick film thermal head, and more particularly to a structure for improving the translatability of a thermal head.

[Conventional technology]

FIG. 3(IL) is a partially enlarged plan view of a conventional thick-film thermal head, and FIG. 3(b) is a sectional view taken along line bb--b of FIG. In the figure, (1) is an insulating substrate made of alumina ceramic, etc. (2a) and (2b) are electrode conductors that alternately intersect in a comb shape from both sides. 1) Repeat the steps of screen printing and firing 2 to 3 times to form a thin gold film with a thickness of about 3 μm. (3) is a resistor; a resistor paste containing μ-thenium oxide, etc. is printed in a narrow width in the direction orthogonal to the electrode conductors (2m) and (2b) by screen printing, and baked to produce an io/! As shown in Figure (b), the cross-sectional shape consists of two embankments (3a) at both ends formed by the gold paste and a concave part (3b) in the center. and has.

Although not shown, a wear-resistant layer is provided to cover the resistor (3).

The thermal head configured in this way has an electrode conductor (2
When a voltage is applied between a) and the selected electrode conductor (2b), a signal current flows between both electrodes, heat is generated and the surface temperature is heated to about 250 to 600°C,
As shown in FIG. 4, thermal paper (4), which is pressed by a defennment (not shown) and fed in the direction of arrow A, is colored to record information such as characters. In this case, the resistor (3
) The signal current flowing through the electrode conductors (2a) and (2b)
Since most of the flow is near the area, the temperature distribution is 1 in Figure 4.
In the order shown by the dot-dashed line and the double-dot-dashed line, the lower part, the embankment part (
When 3a) is brought into contact with thermal paper (4) and colored, it becomes one point (3C) and is formed on both sides of the electrode conductor (2b) to which a voltage is applied, as shown in Figure 3(a). It was configured to print one dot using four hot points (3C).

[Problems to be solved by the invention] In the cross-sectional shape of the resistor (3) formed by the conventional screen printing method of a thermal head, four heat points (3c) are formed. The temperature of heat point) (3e) increases due to heat conduction, so
Since the response speed is slow and it is important to keep the cross-sectional shape of the resistor (3) constant, four heat points (
3C) temperature unevenness occurs. This resulted in uneven color density at the four heat points (3C), which was an obstacle to gradation recording in which printing was done by controlling the amount of recording current so that the printing density was in several levels. .

The present invention was made with the aim of solving this problem, and has a high response speed, and has two or one printing dots.

The purpose is to obtain a thermal head with uniform print density.

[Means for solving problems]

The present invention includes a resistor having a semicylindrical cross section formed on an insulating substrate, and an electrode conductor formed in a comb shape extending across the resistor and onto the insulating substrate. It is a thermal head equipped with

[Effect]

When electrodes and other bodies are formed on the resistor, a large amount of signal current flows through a portion close to the surface of the resistor, and the surface of the resistor can be heated to the highest temperature, resulting in faster response speed.

In addition, if the cross-sectional shape of the resistor is formed into a kamabot shape, the number of points per point will be two when it comes into contact with thermal paper, or one point if the electrode conductor is sufficiently thin), and the above response speed will be faster. Combined with this, it is possible to print without uneven density.

[Embodiments of the invention]

FIG. 1(a) is a partially enlarged perspective view of an embodiment of the present invention;
Figure Φ) is a partially enlarged cross-sectional view along the extending direction of the resistor, and Figure (0) is a partially enlarged cross-sectional view along the extending direction of the electrode conductor.

In the figure, a resistor (3) is placed on an insulating substrate (1).
The resistor paste having a semicylindrical cross-sectional shape can be formed by a coating method in which the resistor paste is drawn using a dispenser. The polarized conductors (2a) and (2b) are formed by printing with an inorganic gold paste (for example, by Engelhallin printing method) and firing to form a diameter of about 3 μm.

Selected electrode conductors (2
When a voltage is applied between b) and (2a).

Most of the recording current flows near the surface of the resistor (3),
Since the surface temperature rises quickly, the response speed becomes faster. Further, the hot points (3c) with which the thermal paper comes into contact are two points at the tops (3a) of the resistors (3) on both sides of the electrode conductor (2b), as shown in FIG. 1(a). As mentioned above, this hot point (3c) is also the part where the largest amount of current flows in signal 1, so there is no temperature unevenness between the two hot points (3c), and the amount of signal current is Since it is quickly heated to a temperature that corresponds to the change in the printing density and the gradation of the printing density, printing suitable for gradation recording can be performed.

FIG. 2(a) is a partially enlarged sectional view of another embodiment of the present invention, and FIG. 2(b) is a partially enlarged sectional view along the extending direction of the resistor.

Organic gold paste (9b) is printed on the surfaces of the resistor (3) and the insulating substrate (1) and fired to a thickness of 0. A gold thin film of 15 to 0.6 μm was formed, and then electrode conductors (2a) and (2b) were formed by photoetching.

In this example, as in the previous example, each selected portion is placed on the top (3) of the resistor (3) on both sides of the polar conductor (2b).
In a), two and one point inds (3c) are formed, but since the polar conductor (2b) is made of organic gold paste and is thin, the temperature rises quickly due to heat conduction, and one and one point ind (3d) are formed. ) to heat the thermal paper and print. Therefore, printing can be performed without unevenness in print density, with a fast response speed, and more suitable for gradation recording.

In the above example, a gold thin film was formed using an organic gold paste, and D'F [polar conductor (
Although an example of forming 2a) and (2b) has been described, it goes without saying that the invention is not limited to this example.

〔Effect of the invention〕

Since the thermal head is equipped with a t-pole body that is formed to extend over a transparent substrate, the response speed is fast, and there are two or one heat points to print without uneven density. be able to.

[Brief explanation of the drawing]

FIG. 1(a) is a partially enlarged perspective view of an embodiment of the present invention;
FIG. 5B is a partially enlarged sectional view along the extending direction of the resistor of the example, FIG. Figure (IL) is a partially enlarged perspective view of another embodiment of the present invention, Figure Φ) is a partially enlarged sectional view along the extending direction of the resistor according to this other embodiment, and Figure 3 (a) is a partially enlarged plan view of a conventional thick-film thermal head; FIG.
This figure is a sectional view showing the state of contact with the thermal paper in the conventional example of FIG. 3. (1)...Insulating substrate% (2a), (2b)...
・Electrode conductor, (3)...Resistor % (30), (3
d)...hot point. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) an insulating substrate, a resistor formed on the insulating substrate with a semicylindrical cross section, and a resistor extending across the resistor onto the insulating substrate; A thermal head with electrode conductors formed in a comb-like shape alternately from both sides of the head. (2) The thermal head according to claim 1, wherein the electrode conductor is a thin gold film formed by printing and firing an inorganic gold paste. (3) The thermal head according to claim 1, wherein the electrode conductor is formed by a photo-etching method from a gold thin film formed by coating and baking an organic gold paste.