JPS63104850A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent accumulation of heat in a head and to improve the printing density or printing speed, by providing a carbon film containing a diamond structure having good thermal conductivity and a substrate below a heating member. CONSTITUTION:An aluminum substrate 1 having good thermal conductivity and a carbon film 2 having a diamond structure formed through vapor phase synthesis are provided below a heating section. Current is fed through an aluminum electrode 5 to a heating element 4 so as to produce heat. Thus produced heat is suppressed of its transmission to the underside by means of a glass layer 3 located immediately below, and transmitted in lateral direction and the direction of a protection film 6 which prevents abrasion of the heating element through contact with an upper side paper. Since it contributes as print energy in the upper direction while the carbon film 2 having good thermal conductivity and the substrate 1 arranged below contribute to quick radiation of heat in the lateral direction, heat is scarcely accumulated in the head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head of a recording device that prints by generating heat.

[Summary of the invention]

The present invention describes a thermal head capable of high printing speed and high density.

In order to achieve high speed and high density, a material with good thermal conductivity is used for the thermal head substrate to prevent heat accumulation and create a head with high thermal efficiency.

[Conventional technology]

Regarding the printing performance of the thermal head, see the literature (Uenishi, Murasugi, Shibata; Journal of the Institute of Image Electronics Engineers, Vol. 9.N.

1.1980. It is detailed in P9～).

[Problem that the invention seeks to solve]

Among various recording devices, thermal heads are superior in terms of low cost and compactness because of their simple structure for printing.

However, it cannot be denied that this method is inferior to other printing methods in terms of dot clarity and printing speed.

In particular, the sharpness of the dots is not inferior to other printing methods if paper specifically designed for thermal heads is used, but when printing on plain paper similar to other printing methods, the sharpness of the dots is significantly reduced due to the roughness of the paper surface. The main reason for this is that the number of dots per unit length is small, so if paper with a rough surface is used, the sharpness decreases. Furthermore, the printing speed cannot be improved unless the number of colored dots developed per unit time is increased.

In order for each dot to develop color to a predetermined density, it is necessary for the heating element to generate a predetermined amount of energy.

FIG. 2 shows the waveform of one pulse applied to the do-nod, with time on the horizontal axis and voltage on the vertical axis. That is, in order to increase the number of dots per unit time and unit length, it is necessary to shorten the pulse time without changing the energy of one pulse from the solid line waveform in FIG. 2 as shown by the broken line.

However, with the structure and materials of conventional thermal heads, shortening the pulse time and increasing the voltage causes heat to accumulate in the thermal head, leading to smearing of prints and head destruction.
It was difficult to make it shorter than 2 m5ec.

[Means for solving problems]

In order to solve this problem, the present invention provides a carbon film containing a diamond structure with good thermal conductivity and a substrate under the heating element, thereby reducing unnecessary extra heat generated by the heating element during printing. It is now possible to quickly dissipate heat to the outside and prevent heat from accumulating in the head. As a result, we were able to improve printing density and printing speed compared to conventional thermal printers.

[Effect]

Directly below the heating element, there is a thermally insulating material, such as glass, so the generated heat spreads upward and laterally of the heating element.In the upward direction, it is transmitted to the paper and the energy for coloring is transferred to the paper. However, since the heat in the lateral direction cannot be dissipated, this becomes the cause of head M heat. Here, in the present invention, since a carbon film containing a diamond structure and a substrate with good thermal conductivity are used, heat in the lateral direction can be quickly dissipated from the carbon film to the substrate, so that almost no heat is accumulated in the head.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view of the thermal head of the present invention. An aluminum substrate 1 as a substrate with good thermal conductivity and a carbon film 2 having a diamond structure formed by a vapor phase synthesis method are constructed below a heat generating part disposed thereon. Electricity is supplied to the heating element 4 through the aluminum electrode 5, which generates heat.The generated heat is suppressed from moving downward by the glass layer 3 directly below it, and the contact with the paper on the upper side prevents wear of the heating element. It spreads in the direction and lateral direction of the protective film 6.

The upward direction contributes as energy for printing.

In the lateral direction, heat dissipates quickly because there is a carbon film and a substrate with good thermal conductivity underneath.

FIG. 2 is a diagram showing pulse waveforms applied to dots, where the solid line shows the pulse waveform applied to the conventional thermal head, and the broken line shows the pulse waveform applicable to the thermal head of the present invention.

That is, it is shown that the present invention can be implemented using a pulse waveform with a shorter pulse time and higher voltage than the pulse waveform applied to conventional thermal heads.

FIG. 3 shows the results of measuring the temperature rise of the substrate 1 of a conventional thermal head and a thermal head of the present invention. From this, it can be seen that the thermal head of the present invention does not accumulate heat compared to the conventional one.

〔Effect of the invention〕

The thermal head of the present invention can increase printing speed by five times and print density by twice as much as conventional thermal heads. Therefore, a printing device with unprecedented high speed and high definition can be manufactured at low cost.

[Brief explanation of the drawing]

Fig. 1 is an embodiment of a cross-sectional view of the thermal head of the present invention, Fig. 2 shows one pulse when applying voltage to the dots of the thermal head, and Fig. 3 shows the printing of the thermal head substrate. This figure compares the temperature rise inside the conventional product and the product of the present invention. 1 ・ ・ ・ Base 1 anti 2... Carbon film 4... Heating element 5... Electrode or more

Claims (1)

[Claims] In the thermal head of a recording device that generates heat to print, the heat generating part that generates heat to print and a carbon film with a diamond structure and a substrate made of a material with good thermal conductivity are constructed below the heat generating part. Features a thermal head.