JPS5831779A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head having excellent heat response characteristic by forming a conductor layer serving as a heat transmission layer on an alumina base plate provided with graze and also an oxide film serving as a heat-shock resistant layer on the surface of the conductor layer. CONSTITUTION:Ta, Ti, Hf, Zr, etc., are adhered onto an alumina base plate 21 provided with a graze 1 by sputtering, vapor deposition, etc., and then an oxide film 3 is formed on the surface of the thin film of Ta, etc., by a heat oxidation or anodic oxidation method, etc. The oxide film 3 plays a role of a heat shock- resistant layer to protect the heat storage layer when patterning and etching a heating material. A metal layer 6 staying without being oxidized below the oxide film 3 has a function as a heat transmission layer by which the cooling effect of the heating material is raised and also the distribution of heat is equalized. On the oxide film 3, a heating resistor layer 4, an electrode conductor layer, and a wear-resistant layer 5 are formed.

Description

[Detailed description of the invention] The present invention relates to a thermal head.

With the advancement of the information society, facsimiles are rapidly becoming popular for speeding up information transmission, saving labor, and rationalizing office operations, and the market size is growing at an annual rate of more than 20%.

7Axi IK is electrostatic recording, electrolytic recording, discharge breakdown arrangement,
Various methods such as inkjet recording, thermal recording, and laser recording are in use, and each has advantages and disadvantages. Among these, thermal recording is suitable for general-purpose facsimile machines because it is instantaneous because it does not require in-house fixing, has a simple mechanism, is highly reliable, and is easy to maintain.

Up until now, high-end machines with high resolution and high-speed drive,
An electrostatic recording method was used, but a thermal recording method is also beginning to be applied to this type of device. Moreover, the thin film type thermosensitive recording method is suitable for achieving high speed, low power consumption, and high quality recording, and for obtaining recording comparable to the electrostatic recording method.

Conventionally, an example of the cross-sectional structure of a thermal head used in this type of thin film type thermal recording system is as shown in FIG.

On an alumina ceramic substrate 11 coated with a glaze 1 having a thickness of about 80 μm, a heat-resistant resistant layer 2 made of Si2° is disposed.
An etching-resistant layer 3 made of and TJIIOI is laminated. This heat-resistant aluminum layer 2 alleviates direct transmission of thermal shock during operation of the heating element to the thermally weak glaze layer through the 810° film. For example, 8 dots/! on the substrate. Ta- with linear density of oI
An 8I-based heating resistor layer 4 is formed, and a wear-resistant layer 5 is formed by laminating Sing, which also serves as oxidation protection, and 8iC.

In conventional thermal heads, when driven at high speed, most of the heat generated by the heating element is accumulated in the heat storage glaze layer 1, which has low thermal conductivity, and is not conducted to the substrate 11. A considerable temperature rise occurs in the body, causing a phenomenon that requires a long time to cool down, that is, a trailing phenomenon, which causes the degree of decomposition of the printed part of the thermal paper to be recorded to change, and the image quality is impaired due to density unevenness, etc. be exposed. Therefore, the driving conditions were limited to a pulse width of 2 m5 ec and a cycle of 10 m5 ec. Therefore, an object of the present invention is to provide a heat-sensitive device that enables higher-speed driving and realizes high-speed facsimile.

In the present invention, a thin conductor layer is directly deposited on the entire surface of a glass V-shaped layer formed on an alumina ceramic substrate by means such as sputtering or vapor deposition, and then the conductor is deposited by a method such as thermal oxidation or anodic oxidation. By forming an oxide film on the surface of the layer, the oxide film doubles as a heat-resistant seal layer, and at the same time, the underlying conductor layer functions as a heat transfer layer, increasing the cooling efficiency of the heating element and ensuring uniform heat distribution. It is characterized by improved thermal response characteristics.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the cross-sectional structure of a thermal head according to the present invention. Approximately 1,000 ATa is deposited on the alumina substrate 21 on which the brace 1 with a thickness of approximately 8 μm has been applied by sputtering, vapor deposition, etc. Next, thermal oxidation is performed at 500C for 11 hours in the air to obtain approximately 500 to 700
A Ta,01 film 3 of A is formed. This oxide film is used to protect the vapor layer during patterning and heating of the heating element.
Acts as a heat-resistant thick layer. The lower Ta layer 6 that remains unoxidized by the thermal oxidation functions as a heat conductive layer of the seed coat, and immediately lowers the residual temperature that occurs when the heating element is driven. Improve the thermal response characteristics by making the temperature uniform.

Therefore, it has the advantage that the heat-resistant shock layer 2, which reduces the amount of s required in conventional thermal heads, can be omitted. The subsequent formation of the heat generating resistor layer 4, electrode conductor layer, and abrasion resistant layer 5 is performed by the same process as that of a conventional thermal head.

The thermal head according to the present invention described above has the effects described below. A high density facsimile machine can be achieved by shortening both the pulse width and period, but this means that a higher applied power is required to obtain the same color density as the pulse width becomes shorter. means. Moreover, most of the heat generated by the heating element is accumulated in the heat storage glaze layer 1 and is not conducted to the substrate side, so in the conventional thermal head structure, the residual temperature increases considerably and becomes non-uniform, which makes it difficult to increase the speed. It was a hindrance.

FIG. 3 shows qualitative temperature characteristics when a bus width tpt' power is applied to the heating element. Transient heating element temperature TACIs peak temperature TP due to the influence of pulse period
Depending on the pulse period, the surface temperature of the heating element is transient at the time of the next applied pulse, and the remaining residual temperature TAC is a typical temperature level.The dotted line in the figure is the temperature characteristic of the conventional thermal head structure.

According to the thermal head structure of the present invention, the heat generated by the heating element diffuses through the Ta layer at a higher speed and over a wider area.
Moreover, the residual temperature becomes uniform. Therefore, the reliability of the heating resistor is affected by the increase in applied power due to high-speed driving, and the image quality recorded as density unevenness due to the influence of residual temperature is not affected, for example, the pulse width is 1. m
sec, and high-speed printing with a pulse period of 5 ms@c is now possible. The solid line in FIG. 3 shows the temperature characteristics of the thermal head according to the present invention, and it can be seen that the thermal response characteristics are improved compared to the conventional thermal head.

The embodiments described above are only examples of materials; for example, the Ta thin film cited in the present invention may be replaced with other thin films having similar properties, such as Ti, Hf, Nb.

Compounds between Zr or armpit metals, wrinkled metals and nitrogen, oxygen,
It goes without saying that it may be a compound with other elements such as silicon or aluminum, and the deposition method may include vacuum evaporation, active sputtering, etc., and is not particularly limited. Methods for forming oxide layers consisting of these thin films include not only thermal oxidation methods, but also
It goes without saying that an anodic oxidation method and a plasma oxidation method may be used. The substrate to which the thin film is to be attached is not particularly limited, and one person deposits KSIC, Ta2 on an alumina substrate at a rate of 1.0. It goes without saying that the effects of the present invention will not be particularly impaired even if there is no cough insulation layer.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional heat sensitive device. FIG. 2 is a sectional view showing a thermal head according to an embodiment of the present invention. FIG. 3 shows examples of temperature characteristics of the conventional thermal head and the present invention. In the figure, l is the glaze, 2 is the heat-resistant layer 1,
3 is an etching-resistant layer, 4 is a heating resistor layer, 5 is a wear-resistant layer, 6 is a tantalum layer, 11 is an alumina ceramic substrate, 2
1 is an alumina substrate.

Claims (1)

[Scope of Claims] An insulating substrate, a thin film containing a releasable metal such as tomo tantalum, titanium, honeycomb, and zirconium attached to the substrate, and an oxide layer laminated on the thin film. , and a heating resistor laminated on the oxide layer. Do.