JPS6235860A - Thermal head - Google Patents

Abstract

PURPOSE:To enhance the heat efficiency of a resistor dot and to obtain a thermal head imparting good printing quality, by forming a rectangular clearance pattern having no electrode film on each electrode film to allow the same to position on the area of the electrode film separated by predetermined quantity from the boundary part with a resistor dot and forming each electrode film so that the expanse thereof is not broken. CONSTITUTION:A heat-insulating layer 2 composed of an insulating material and a resistor film 3 are successively laminated onto a substrate 1 and a pair of electrode films 4a, 4b are arranged on the resistor film 3 so as to leave a predetermined interval. The electrode films 4a, 4b are formed into a rectangular shape having a predetermined expanse, and rectangular clearance patterns 6, 7 are formed at positions slightly separated from the boundary parts with the resistor dot 3a so as not to breaks the expanses of the aforementioned electrode films 4a, 4b. Even if the heat generated in the resistor dot 3a passes through the electrode films 4a, 4b along the sub-scanning direction A and is apt to escape to both end sides of a thermal head, because the passages 10, 11 of escape ports are narrow, only slight heat escapes. Therefore, charged power is effectively used for the generation of heat.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an improvement of a thermal head in a thermal recording device such as a facsimile or a printer.

(Background of the Invention) A conventional thermal head basically has a large number of heating resistor dots lined up in a row in the main scanning direction, and a pair of electrodes connected to the resistor dots in order to generate heat by energizing the dots. A cross-sectional view of a conventional thermal head is shown in FIG.

In FIG. 5, 1 is a substrate, 2 is a heat insulating layer, and 3 is a resistive film. 4a and 4b are a pair of electrode films, and 5 is a protective film. The portion 3a of the resistive film 3 located between the pair of electrode films 4a and 4b serves as a resistor dot, and the resistor dot 1-3a is formed in a rectangular shape as shown in FIG. Note that the protective film 5 shown in FIG. 5 is omitted in FIG. 6.

Due to the above structure, when electricity is applied to the resistive film 3 through the pair of electrode films 4a and 4b, the resistor 3a generates heat, and the protective film covering the dot 3a as shown in FIG. The thermal recording paper (not shown) pressed against 1II5 develops color and prints are performed, but this thermal head had the following drawbacks. That is, each of the electrode films 4a described above
, 4b has good heat conductivity, so the resistor dot 3
Since the heat generated at point a escapes to both ends of the thermal head through each of the TL electrode films a and 4b along the sub-scanning direction shown by the arrow in FIG. 6, there is a drawback that thermal efficiency is poor. . Further, regarding the temperature distribution on the surface of the dot 3a, the temperature difference between the center and the periphery of the dot 3a decreases due to the above-mentioned defect. This has the disadvantage that it becomes large and has an adverse effect on print quality. Incidentally, FIG. 7 is a graph showing the temperature distribution in a cross section along the axis (■)--(2) along the sub-scanning direction in FIG. 6.

(Objective of the Invention) An object of the present invention is to solve the above-mentioned drawbacks, improve thermal efficiency, and obtain a thermal head with good printing quality.

(Summary of the Invention) In order to achieve the above object, the present invention includes a resistor dot that generates heat when energized; a pair of electrode films; a rectangular clearance pattern in which the electrode film does not exist is formed in each of the electrode films, and the clearance pattern is separated by a predetermined amount from the boundary with the resistor dot. A thermal head is provided, characterized in that it is located at the location of the electrode film and is formed so as not to divide the spread of each of the electrode films.

Embodiments of the present invention will be described below based on the drawings.

(First Embodiment) FIG. 1A is a plan view of a thermal head according to a first embodiment of the present invention. In FIG. 16, a cross-sectional view of the shaft 111++ is shown in FIG. 1B, and the shaft 111++ is shown in FIG. −■.

A sectional view of the protective film 5 is shown in FIG. 1C, and the protective film 5 shown in FIG. 1B and FIG. 1C is omitted in FIG. 1A.

In this first embodiment, the structure of the thermal head is such that a heat insulating layer 2 made of an insulating material and a resistive film 3 are sequentially laminated on a substrate 1, as shown in FIG. 1B. On the resistive film 3 described above, a pair of electrode films 4a and 4b are arranged at a predetermined interval.
is located.

The electrode films 4a, 4b are rectangular with a predetermined extent as shown in FIG. 1A, and the resistor II! exposed between the pair of electrode films 4a, 4b! The portion 3a of J3 becomes a resistor dot. Each of the electrode films 4a and 4b is provided with a resistor (Doff) 3.
A rectangular clearance pattern 6.7 is formed at a position slightly apart from the boundary with a, so as not to divide the spread of each of the electrode films 4a, 4b. Since the electrode film of the clearance pattern 6.7 has been removed, a portion 8.8 of the resistive film 3 is exposed. Finally the first
As shown in Figure B, a protective film 5 is applied.

With such a pattern configuration, the heat generated in the resistor dot 3a passes through each electrode film 4a, 4b along the sub-scanning direction A, as shown in FIG. 1A, and tries to escape to both ends of the thermal dot. However, as shown in FIGS. 1A and 1C, only a small amount of heat can escape because the escape passages 10.11 are narrow. Therefore, the input power is effectively used for generating heat.

(Second Embodiment) FIG. 2A is a plan view of a thermal head according to a second embodiment of the present invention. In this FIG. 2A, axis r.

The cross-sectional view of -Is is the same as that in Figure 1B, and the axis ■.

A cross-sectional view of 'am is shown in FIG. 2B, and the protective film 5 shown in FIG. 2B is omitted in FIG. 2A.

In this second embodiment, the structure of the thermal head is the same as that in the first embodiment, but like the second AIM, the clearance patterns 12 and 13 are formed in elongated rectangular shapes without electrode films. , each of the above electrode films 4a
, 4b are lined up in the main scanning direction so as not to divide the spread.

With such a pattern configuration, even if the heat generated in the resistor dots 3a passes through each electrode film 4a, 4b along the sub-scanning direction A and tries to escape to both ends of the thermal head, as shown in FIG. 2A, As shown in FIGS. 2A and 2B, since the escape passages 14, 15 are narrow, the same results as in the first embodiment can be obtained.

(Third Embodiment) FIG. 3A is a plan view of a thermal head according to a third embodiment of the present invention. In this FIG. 3A, the axis l1l-! The cross-sectional view of , is similar to that in Figure 1B, and the axis ■.

A cross-sectional view of -■ is shown in FIG. 3B, and the protective film 5 shown in FIG. 3B is omitted in FIG. 3A.

In this third embodiment, the structure of the thermal head is the same as in the first and second embodiments, and as shown in FIG. 3A, the clearance patterns 16 and 17 are different from those in the second embodiment. Similarly, it is formed into an elongated rectangle,
A plurality of electrodes are lined up in the main scanning direction, but each electrode 11 in the sub-scanning direction! The clearance pattern is not formed in the central portions 18 and 19 of J4a and 4b.

With such a pattern configuration, the heat generated in the central part of the resistor dot 3a is transferred to the central part 18, 19 of each of the electrodes 1114a, 4b (as shown in FIG. 3B), as shown by the arrow B in FIG. (see also).

On the other hand, each central portion 18. of the electrode films 4a, 4b.
It becomes difficult for the heat generated by the resistor dot 3a to escape on each side of the pattern 19 (the peripheral portions of the patterns 16 and 17). Therefore, the main scanning direction of the resistor (t) 3a is the arrow C in Fig. 38).
The temperature distribution can be flattened.

(Fourth Embodiment) FIG. 4A is a plan view of a thermal head according to a fourth embodiment of the present invention. In this Figure 4A, axis ■.

A cross-sectional view of IV, is shown in FIG. 4B, with axis TV, -IV.

A cross-sectional view of is shown in FIG. 4C. The protection [5] shown in FIGS. 4B and 4C is omitted in FIG. 4A.

In this fourth embodiment, regarding the structure of the thermal conductor, as shown in FIG. 4B, the length of the resistive film 3! are shortened so that a portion of each electrode film 4a, 4b overlaps both ends of the resistive film 3, and the remaining part of each electrode film 4a, 4b is laminated on the heat insulating layer 2, as shown in FIG. 4A. A portion 22.23 of the insulation N2 is exposed in each clearance pattern 20.21 formed on the electrode films 4a, 4b. Others are the first embodiment (
1A and 1B).

A similar effect can be expected even if a circular or oval pattern (not shown) is used as the clearance pattern, but a rectangular pattern is more effective because it can lengthen the narrow path through which heat escapes.

(Effects of the Invention) As described above, according to the present invention, the thermal efficiency of the resistor dots can be improved and a thermal head with good printing quality can be obtained. In addition, in the third embodiment (see Fig. 3A), if the pattern is configured in this way, the temperature distribution of the resistor dots in the main scanning direction can be flattened, so that faithful printing can be performed. I can do it.

[Brief explanation of the drawing]

FIG. 18 is a plan view of a thermal head according to a first embodiment of the present invention. FIG. 1B is a sectional view of the axis Is L in FIG. 1A. FIG. 1C is a sectional view taken along the axis IC-1° in FIG. 1A. FIG. 2A is a plan view of a thermal head according to a second embodiment of the present invention. FIG. 2B is a sectional view taken along the axis Us-■ in FIG. 2A. FIG. 3A is a plan view of a thermal head according to a third embodiment of the present invention. FIG. 3B is a sectional view of axis II [1 min] in FIG. 3A. FIG. 4A is a plan view of a thermal head according to a fourth embodiment of the present invention. FIG. 4B is a sectional view of the axis rVa TVI in FIG. 4A. FIG. 4C is a sectional view of the axis IVc rVc in FIG. 4A. FIG. 5 is a sectional view of a conventional thermal head. FIG. 6 is a plan view of a conventional thermal head. FIG. 7 is a graph showing the temperature distribution of the resistor dot 3a in a cross section taken along the axis V-V along the sub-scanning direction in FIG. [Explanation of symbols of main parts] 3---Resistive film 3a--Resistor donode 4a, 4b--Electrode film

Claims (1)

[Scope of Claims] A resistor dot that generates heat when energized; and a pair of electrode films having a predetermined spread and connected to the resistor dot for energizing the resistor dot. , a rectangular clearance pattern in which the electrode film does not exist is formed on each of the electrode films, and the clearance pattern is located at a part of the electrode film that is a predetermined amount away from the boundary with the resistor dot, and A thermal head characterized in that it is formed so as not to divide the spread of each electrode film.