JPS61211058A - Thermal printing head - Google Patents

Abstract

PURPOSE:To enable only an important printing dot section to heat to increase the heating efficiency by forming each terminal along the lateral direction of a resistance film and to such an extent that the terminals do not cross the lateral direction and also forming the continuous part of common terminals so that these overlap the resistance film each other. CONSTITUTION:Common terminals 3 and individual terminals 5 are formed along the lateral direction of a resistance film 2 and in such an extent that the former do not cross the direction. Besides, a continuous part 4 is allowed to overlap the film 2 partly or wholly. If an voltage is applied between the continuous part 4 and one of the selected individual terminals, an electric current runs mainly in the resistance film 2 which exists at a location where the selected individual terminals 5 and the common terminals at both sides of the individual terminals are opposed to each other, and the part where the current runs generates heat. The part where both terminals 3, 5 face each other represents only an intermediate section along the lateral direction of the resistance film 2, and almost no electric current runs in the neighborhood of both edges of the resistance film 2. This means that only the part where the film 2 faces thermosensitive paper becomes hot and the part where they do not face each other does not.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a thermal print head.

(Prior art) A thermal print head in which a plurality of individual terminals and a common terminal are alternately arranged in parallel on the surface of an insulating substrate, and a band-shaped resistive film is formed so as to overlap each terminal, has already been developed. well known. 3 and 4 show a conventional thermal print head of this kind, in which 1 is an insulating substrate made of ceramic or the like, 2 is a heat-generating resistive film formed in the form of a thick band on its surface, and 3 is a common terminal, 4
is a continuous portion of the common terminal 3, and 5 is an individual terminal. Individual terminals 5 and common terminals 3 are alternately formed on the surface of substrate 1, and resistive film 2 is formed to overlap each terminal. In reality, a protective film, a wear-resistant film, etc. are formed on these surfaces, but these are omitted in the figure.

According to this configuration, when a voltage is applied between the continuous portion 4 and one selected individual terminal 5, a current flows through the resistive film portion between both terminals, and the portion through which this current flows generates heat. do. When heat from this heat-generating portion is conducted to the thermal paper, the conductive portion develops color.

In this way, desired printing is performed.

By the way, since this kind of resistive film 2 is formed by screen printing, its cross-sectional shape in the width direction is high at the center and low at both edges like a hem, as shown in FIG. It is formed into a semicylindrical shape, so to speak. Therefore, during printing, the thermal paper does not come into contact with the entire surface of the resistive film 2, but only comes into contact with a part of the resistive film 2 near the center. Therefore, in general, the width direction dimension of this resistive film 2 is 30 to 30 mm with respect to the dimension of one printed dot.
It is made to be about 50% wider.

On the other hand, when voltage is applied between terminals 3 and 5 as described above,
The entire part of the resistive film that exists between the terminals generates heat6 However, as mentioned above, the part that is involved in printing is only around the center of the resistive film, and the area around the bottom is not involved at all.
Therefore, the heat generated near the hem is completely wasted. In other words, in such a conventional configuration, power loss is large and heat generation efficiency is extremely poor.

(Problems to be Solved by the Invention) An object of the present invention is to increase heat generation efficiency by generating heat only in the printed dot portions necessary for printing.

(Means for Solving the Problems) This invention allows each terminal to be connected along the width direction of the resistive film.
The common terminal is formed so as not to cross this, and the continuous portion of the common terminal is formed so as to overlap with the resistive film.

(Example) An embodiment of the invention will be described with reference to FIGS. 1 and 2.

Note that parts with the same reference numerals as in FIG. 3 and the like indicate the same or corresponding parts. In the present invention, the common terminal 3 and the individual terminals 5 are formed along the width direction of the resistive film 2 without crossing it.

Then, the continuous portion 4 is arranged so that a part or the whole (in the example shown in the figure, a part) overlaps with the resistive film 2.

In the above configuration, when a voltage is applied between the continuous portion 4 and one selected individual terminal 5, the selected individual terminal 5 and the common terminals 3 on both sides of the individual terminal face each other. Current mainly flows through the portion of the resistive film 2 that is present at the location, and the portion through which this current flows generates heat.

Although such an effect is the same as in the configuration shown in FIG. 3, in the configuration shown in FIG.
Only the intermediate portion along one width direction of the resistive film 2,
Almost no current flows near both side edges of the resistive film 2.

This means that only the portion of the resistive film 2 that faces the thermal paper generates heat, and the portion that does not face the resistive film 2 does not generate heat. Therefore, since there is almost no power loss in parts that are not involved in coloring the thermal paper, the heat generation efficiency is improved compared to the conventional configuration.

In the configuration shown in FIG. 1, a continuous portion 4 connecting adjacent common terminals 3
The side edges of are semicircular with a radius corresponding to the distance between the individual terminals 5 and the common terminal 3. According to this, in the resistive film part that forms one printed dot, both terminals 3 and 5
Since the distance between them is equal, the amount of heat generated is almost uniform, which is convenient.

However, in reality, the current concentrates at the tip of the individual terminal 5, which may cause the temperature near this tip to become high. Therefore, the position of the individual terminal 5 is changed appropriately depending on the degree of heat generation, and the amount of heat generated can be reduced. It is desirable to aim for uniformity.

In the illustrated embodiment, the terminals, continuous portions, etc. are formed on the surface of the substrate 1, but they may be formed on the surface of the resistive film 2 instead.

(Effects of the Invention) As described in detail above, according to the present invention, power consumption is reduced compared to the conventional configuration, and therefore the heat generation efficiency during this type of printing can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view thereof, FIG. 3 is a plan view of a conventional example, and FIG. 4 is a sectional view thereof. 1... Substrate, 2... Resistive film, 3... Common terminal, 4
・・・Continuous part, 5...Individual terminal, Fig. 3 4 Old diagram η

Claims (1)

[Claims] It includes a heat generating resistive film, individual terminals formed to overlap with the resistive film, and a common terminal connected by a continuous portion, and the terminals are alternately arranged in parallel, and the width of the resistive film is The thermal print head is formed by forming a continuous portion of the common terminal along the direction but not crossing the same, and further forming a continuous portion of the common terminal so as to overlap with the resistive film.