JPS61293871A - Thin film type thermal head - Google Patents

Abstract

PURPOSE:To uniformize temperature distribution in a heating part and print with high quality, by a construction wherein each printing dot comprises at least three rectangular resistors connected in parallel between two electrodes between which a voltage is impressed, and the width of both end ones of the resistors is set to be the width of the other resistors. CONSTITUTION:Each printing dot is constituted of parallel connection of at least three rectangular heating element 1' connected to the electrodes 2. The width (w) of both end ones of the rectangular resistors is set to be larger than the width (u) of the other resistors. Therefore, the resistance of the end rectangular resistors is lower, and the power consumption of the end resistor is larger than that of other resistor, which fact is equivalent to concentration of electric power on a peripheral part. Accordingly, the temperature distribution in the heating part can be made uniform, high printing quality can be obtained, the useful life of the resistor can be prolonged, and reliability can be enhanced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a thin side-type thermal head, and in particular to a thin-film type thermal head aimed at uniformizing the temperature distribution of the heat generating part and obtaining high quality printing. Regarding improvements.

[Conventional technology]

FIG. 2 shows the heat generating part of a conventionally used thin thermal head. In Fig. 2, an electrode 2 is connected to a rectangular resistor 1.
Power is supplied and printed through.

One printed dot corresponds to one rectangular resistor l.

[Problem that the invention seeks to solve]

FIG. 3(b) shows the temperature distribution in the X-axis direction when current is applied to the conventional rectangular resistor 1 in FIG. 3(a).

In FIGS. 3(a) and 3(b), the origin of the X-axis is the center of the rectangular resistor, and is the point P1. P2 is the end of the rectangular resistor.

As shown by curve C1, the temperature decreases as it approaches the periphery of the rectangular resistor, so if the power supplied is increased to increase the printing density in the periphery, the temperature decreases as shown by curve C as shown in Figure 3(b).
1 to curve C2, the temperature rises by T1 at the periphery, but the temperature rise T2 at the center is larger than T1. Therefore, if you increase the power supplied to prevent the printing density around one printing dot from becoming faint and deteriorating the quality, the temperature at the center of the rectangular resistor will rise further, and conversely the density at the center will decrease and become uniform. In addition to not being able to obtain a high printing density, there is a large temperature gradient from the center to the periphery, which shortens the life of the resistor.

[Means for solving problems]

The thin-film type thermahead of the present invention has a plurality of printed dots, in which each of the printed dots has three or more rectangular resistors connected in parallel between two electrodes to which a voltage is applied. The rectangular resistor is characterized in that the width of the rectangular resistor at both ends of the rectangular resistor is wider than the width of the rectangular resistor excluding both ends.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1(a) is a plan view of one embodiment of the present invention. In this embodiment, one printed dot is made up of three rectangular heating elements 1' connected in parallel to the electrode 2.

Note that the number of rectangular resistors 1' may be three or more.

The width of three or more rectangular resistors forming one printed dot is:
Since the width W of the rectangular resistor at both ends is wider than the width U of the rectangular resistor excluding both ends, the resistance value of the rectangular resistor at both ends becomes small, and when voltage is applied, the consumption in the same resistor decreases. The power consumption is greater than the power consumption in the rectangular resistors other than those at both ends. Therefore, compared to the conventional type shown in Fig. 3(a), the power is concentrated in the periphery, and the
The temperature distribution in the axial direction becomes nearly flat as shown in FIG. 1(b), and the printing density within one printing dot is made uniform.

Furthermore, there is also the effect that the temperature gradient within the plane of the heat generating part is small and the life of the resistor itself is extended.

〔Effect of the invention〕

As described above, the present invention is highly effective in making the temperature distribution of the heat generating part uniform, obtaining high quality printing, and extending the life of the resistor to improve reliability.

[Brief explanation of drawings]

FIG. 1(a) is a plan view of an embodiment of the present invention, and FIG. 1(b) is a plan view of an embodiment of the present invention.
) is a characteristic diagram of FIG. 1(a), FIGS. 2 and 3(a) are plan views of the conventional example, and FIG. 3(b) is a characteristic diagram of FIG. 3(a). 1.1'...Rectangular resistor, 2...1 pole, w, u...Width, C1, C2...Curve, Tl, T2. ,,,,,Temperature rise. f, f'... Da positive # armpit resistance book 2...
1 Hiyuman l Zuge 3 ward

Claims (1)

[Claims] In a thin film type thermal head having a plurality of printed dots, each of the printed dots has three or more rectangular resistors connected in parallel between two electrodes to which a voltage is applied, and the rectangular resistor A thin film thermal head characterized in that the width of the rectangular resistor at both ends is wider than the width of the rectangular resistor excluding both ends.