JPH0345358A - Thermal head of heat pipe radiation type - Google Patents

Abstract

PURPOSE:To easily control the temperature of a substrate and to obtain a high-speed printer by a method wherein a planar substrate of a rectangular form, a box-form heat pipe, and heat radiating fins mounted on tube bodies are provided, and the heat generated in the substrate is radiated from the radiating this through the tube bodies. CONSTITUTION:One surface of a substrate 1 is brought into close contact with one surface of a rectangular box-form heat pipe 4 having a surface larger than that of the rectangular planar substrate 1 by adhesion or other method. In the longitudinal direction of the heat pipe 4 with a working liquid 6 sealed, good-heat conductive tube bodies 5a are symmetrically fixed. A plurality of planar heat radiating fins 5b are provided in parallel to each other in the vicinity of an end part of the tube body 5a opposite to the fixed end part thereof. In this manner, the working liquid 6 is sealed in the heat pipe 4, and the temp. of the substrate 1 is increased along a curve (b) by heating resistors in the substrate 1. When the temp. is increased to a vaporizing temp. t0 of the working liquid 6, the working liquid 6 is vaporized. However, since the heated gas in the tube body 5a is cooled by the fins 5b to be again liquefied, the temp. t0 is kept constant. A suitable material for the working liquid 6 is selected in accordance with the melting point of an ink ribbon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printer, and particularly to the structure of a thermal head of a printer.

[Conventional technology]

As shown in FIGS. 4 and 5, the printer's thermal spatula 1- usually has a structure in which a rectangular plate-like substrate 1 is bonded to a heat dissipating fin 2 having a comb-shaped cross section. The generated heat is transmitted to the radiation fins 2 and dissipated into the atmosphere, thereby cooling the substrate 1.

[Problem to be solved by the invention]

The temperature of the thermal head substrate 1 after the heating resistor starts generating heat exhibits a characteristic represented by the curve a in FIG. 3. In other words, the temperature gradually rises, and in extreme cases, if it exceeds the melting point of the board 1 or the inkliner, or exceeds the temperature sensitive to heat-sensitive paper, printing will occur even if the heating resistor is not energized, and the printer will no longer function as a printer. There are drawbacks to being lost.

[Means to solve the problem]

The present invention solves the above-mentioned drawbacks by replacing the radiation fins 2 shown in FIG. 4 with heat pipes 4 and radiating fins 5 not shown in FIG. Turned off.

[Effect]

A working liquid 6 is sealed inside the box-shaped heat pipe 4, as shown in the cross-sectional view of FIG. When the temperature rises and reaches the vaporization temperature to of the working liquid 6, the working liquid 6 is vaporized, but on the other hand, the heated gas in the tubular body 5a is cooled by the fins 5b and liquefied again, so that the temperature reaches t. is held constant as shown in FIG. A suitable material for the working liquid 6 is selected depending on the melting point of the ink ribbon.

As long as the working liquid 6 exists in this heat pipe 4, the substrate 1
It is the same as having an infinite heat capacity because it absorbs the heat generated from the gas as heat of vaporization.

[Example] To explain the thermal head of the heat pipe heat dissipation according to the present invention shown in FIGS. 1(A) and (B) and FIG. One surface of the substrate 1 is fully adhered to one surface of the heat pipe 4 by adhesive or the like. A thermally conductive tubular body 5a is symmetrically fixed in the longitudinal direction of the heat pipe 4 in which the working liquid 6 is sealed, and a plurality of plates are arranged near the end opposite to the fixed end of the tubular body 5a. Shape radiation fins 5b are provided in parallel. The tubular body 5a and the radiation fins 5b constitute a radiation fin assembly. Further, the tubular body 5a and the radiation fins 5b can be arranged in any combination in the longitudinal direction of the heat pipe or in a direction perpendicular thereto.

On the other hand, in another embodiment, the entire thermal head is formed as a heat pipe, and the bottom surface of the heat pipe becomes the working surface of the thermal head, so that the cooling effect becomes even more pronounced.

As for the actual method of manufacturing a heat pipe for this purpose, the entire heat pipe may be integrally formed with a thermal head material so as to have a rectangular cross section, as shown in Fig. 6 (A), or an alternative method may be used. As shown in Fig. 6(B), a cover member having a U-shaped cross section molded from the same kind of material or other suitable material is placed on the substrate of the thermal head and bonded by soldering or adhesive. It may also be a sealed heat pipe.

〔Effect of the invention〕

In a thermal head with the above structure, the third
Since the temperature characteristics shown by the 6 curves in the figure are shown, the substrate temperature is maintained at a constant vaporization temperature to, temperature control is extremely easy by selecting the working liquid, heat from the substrate is quickly removed, and the temperature This suppresses the increase in speed and allows the printer to operate at higher speeds.

[Brief explanation of drawings]

Figures 1 (A) and (B) are perspective views of a thermal head for heat pipe heat dissipation according to the present invention, and Figure 2 is II-I of Figure 1! 3 is a temperature characteristic diagram of the thermal head, 4 is a perspective view of a conventional thermal head, 5 is a sectional view taken along line V-V in 4, and 6 is (A> and (B)). is a sectional view of another embodiment. [Explanation of symbols] 1... Thermal head board, 3... Connector, 5... Radiation fin assembly, 5b... Radiation fin, 2... Radiation fin, 4... Heat pipe, 5a... Tubular body, 6... Working liquid.

Claims (2)

[Claims] (1) In a thermal head of a printer, a rectangular plate-shaped substrate, a rectangular box-shaped heat pipe that is in close contact with one side of the substrate, and a rectangular box-shaped heat pipe that is connected in any combination in the longitudinal direction of the heat pipe or in a direction perpendicular to this. 1. A thermal head for heat pipe heat radiation, comprising a heat radiation fin attached to at least one tubular body, the heat generated by the substrate being radiated from the radiation fin through the tubular body. (2) A thermal head for a printer according to claim (1), wherein the plate-like substrate forms one surface of a box-like heat pipe.