JPS61227069A - Thermal head - Google Patents

Abstract

PURPOSE:To contrive higher printing quality, smaller power consumption and a higher printing efficiency, by disposing a heating resistor of a thermal head at a position proximate to a thermal recording paper. CONSTITUTION:In the thermal head 10, a pulse is impressed between a pair of electrodes 3A, 3B to cause the heating resistor to generate heat, thereby printing on a thermal recording paper. The electrode 3A is extended to a position opposed to a printing range L, and a mesa form insulating layer 4 is provided on the extension part 3A1. With this mesa construction, adhesion of the thermal recording paper 12 and the thermal head 10 is made favorable, and heat generated by the heating resistor 5 can be efficiently transmitted to the paper 12. Accordingly, favorable printing can be performed even where the head 10 is driven with small power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to the structure of a thermal head used for various types of heat-sensitive recording.

[Technical background of the invention and its problems]

Figure 4 shows a cross section of a conventional thin film thermal head.
In Figure 4, this thermal head includes, for example, an alumina ceramic substrate 20 and a glaze (
heat insulating layer) 21, a heating resistor 22 formed on this glaze 21, a pair of electrodes 23A and 23B formed spaced apart on this heating resistor 22, and this pair of electrodes 2
3A, 23B, and a wear-resistant layer 24 that protects the heating resistor 22.

In addition, a platen row 22 is provided opposite to this thermal head.
5 is arranged, and by applying pulses to the electrodes 23A and 23B, the heating resistor 22 is heated, and printing is performed on the thermosensitive brass paper 26 interposed between the platen row 225 and the thermal head. ing.

In such a thermal head, a pair of electrodes zs
h, zsser; the wear-resistant layer 24 of the part facing between
A recess 24A is formed in this case. For this reason, the efficiency of heat conduction from the first heating resistor 22 to the thermal recording paper 26 is poor, leading to an increase in power consumption and a risk of deterioration of print quality. According to.

An example of a thermal head in which the printing points are formed in a convex shape by overcoming the drawbacks of the conventional example described above is disclosed.
As shown in the figure, an insulator layer 30 is formed between the pair of electrodes 23A and 23B, and the thickness of this insulator layer 30 is set between the electrodes 23A and 23B.
, 23B, and this portion is made convex.

However, even with this configuration, there are drawbacks as shown below. That is, since the electrodes 23A and 23B are good conductors against heat, the heat generated by the single heating resistor 22 is absorbed by the electrodes 23A and 23B.

A temperature difference occurs between the center and the periphery of the printing point.

As a result, the temperature of the thermal recording paper 26 may not reach the color development temperature, resulting in poor printing.

[Purpose of the invention]

The present invention has been accomplished in light of the above-mentioned cost of $1.

The purpose of this is to provide a thermal head with a new structure to efficiently conduct heat from one heating resistor to thermal recording paper.

The purpose of this is to improve the printing quality, and also to make the temperature distribution uniform in the printing range so that good printing can be performed.

[Summary of the invention]

To achieve the above object, the present invention provides a thermal head that prints in a predetermined printing range on recording paper that is pressed by a platen.

an insulating substrate, a pair of electrodes formed on the substrate at a distance, an electrode layer in which one electrode extends to a position opposite to the printing range, and an extension portion of the one electrode. an insulating layer formed on the insulating layer, a pair of electrodes (a heating resistor formed on the insulating layer with the diagonal ends electrically connected to each other, and a wear-resistant layer formed on these) It is characterized by this.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a thermal head according to the present invention. ,
In Figure 1, this thermal head 10 is placed facing the platen row 211. Printing is sequentially performed in each printing range by selectively driving the thermal head 10 on the thermal recording paper 12, which is fed and moved in the direction of the arrow in the figure by the rotation of the platen roller 11.

In the figure, 1 is an alumina ceramic substrate, and a glaze (heat-retaining layer) 2 is formed on the upper layer. This glaze 2 is made of glass, epoxy resin, etc., for example. Note that this alumina ceramic substrate 1 and glaze 2 constitute an insulating substrate.

A pair of electrodes 3A is provided on the upper layer of the glaze 2.

An electrode layer 3 made of 3B is formed. One of the three electrodes of the pair of electrodes 3A and 3B is formed to extend to a position below the printing range, and this extending portion is designated as 3Al.

In addition, an insulating layer 4 is formed in the shape of a mena (plateau) on the extension portion 3A1 and above C2 to insulate the pair of electrodes 3A and 3B. This insulating layer 4 is formed of a member (5 in 2 or the like) that is not only electrically insulating but also thermally insulating.

Further, a heating resistor 5 is formed on the mesa-shaped insulating layer 4, with both ends electrically connected to the pair of electrodes 3A and 3B.

A wear-resistant trowel 116 is formed to protect the heating resistor 5, electrode layer 3, etc. In this way, the thermal head 10 having a convex cross-sectional structure is constructed.

The operation of the thermal head 100 configured as above will be explained. By applying a pulse to the pair of electrodes 3A and 3B, the heating resistor is made to generate heat, and printing is performed on the thermal recording paper.

At this time, the portion of the thermal head 10 around the printing range is formed in a convex shape. That is, three electrodes are formed extending to positions facing each other in the printing range.

A mesa-shaped insulating layer 4 is formed on this extended portion 3Al, and a heat generating resistor 5. A wear-resistant layer 6 is formed. As described above, by adopting the mesa structure, the adhesion between the thermal recording paper 12 and the thermal spatula FIO is good, and the heat generated by the single heating resistor 4 can be efficiently transmitted to the thermal recording paper 12. As a result, good printing can be performed even if the thermal head IO is driven with small power consumption.

Further, due to this mesa structure, a portion where one heating resistor 4 is connected to a pair of electrodes 3A and 3B (this portion is
Heat escapes through A and 3B, resulting in a low-temperature area) that is outside the printing range and is kept away from the contact surface with the thermal recording paper 12. Therefore, the temperature distribution in the printing range Lf) is improved, and the coloring temperature can be maintained over the entire area, resulting in improved printing quality.

Moreover, since the heating resistor 4 is placed closer to the thermal recording paper 12 (conventionally, it is generally provided below the electrodes) compared to the conventional example, the heating resistor 4 The heat transfer coefficient to the print head is further improved, and lower power consumption and printing efficiency are significantly achieved.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the gist of the present invention. With the structure according to the present invention, the material of each layer does not matter, and the insulating layer 4
As such, it is essential that it is electrically insulating (
(because it is formed on an electrode), it is optionally also thermally insulating.

This is because the heat retention effect is achieved by Glaze 2 and the like.

Further, as an effective structure for improving the temperature distribution in the printing area, the structure shown in FIG. 2, 'IA3' may be used. The structure of the thermal head 10 shown in FIG. 2 is different from the above embodiment, as shown in an enlarged view in FIG.
This is made thinner than the layer thickness t2 of the heating resistor 4 formed on the upper surface of the insulating layer 4. As a result, the portion of one layer thickness t1 becomes a high resistance portion, and the amount of heat generated here increases. Therefore,
The temperature difference between the peripheral area of the printing area and the center 111m is reduced.

It becomes easy to ensure the coloring temperature throughout the entire printing range. This improvement in temperature distribution significantly improves printing quality.

〔Effect of the invention〕

As explained above, according to the present invention, the heating resistor efficiently conducts heat to the thermal recording paper to improve printing quality, and furthermore, it is a novel technology that can easily achieve uniform temperature distribution over the entire printing range. It is possible to provide a thermal head with a unique structure.

Furthermore, in the present invention, since the electrode extends to the bottom of the insulating layer, the insulating layer can be made thinner by the thickness of the electrode when obtaining the same height. Since the step of forming the insulating layer by sputtering occupies a large proportion of the time to the entire process, the present invention not only saves the material of the insulating material, but also significantly shortens the time required to form the insulating layer.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a thermal head that is an embodiment of the present invention, the WIZ drawing is a cross-sectional view showing a modification of the thermal head, Fig. 3 is an enlarged view of @2 diagram A, Fig. 4, @ 5 is a sectional view showing the structure of a conventional thermal head. 1.2... Insulating substrate, 3... Electrode layer, 3A
, 3B...pair of electrodes, 3A1...extension part, 4.
...Insulating layer. 5... Heat generating resistor, 6... Wear resistant layer, 11
...Platen, 12...Recording paper, L...
Printing range. Figure 1 Figure 2■ Figure 3

Claims (2)

[Claims] (1) A thermal head that prints in a predetermined printing range on recording paper that is pressed by a platen, comprising an insulating substrate and a pair of electrodes formed spaced apart on this substrate, An electrode layer formed by extending one electrode to a position opposite to the printing range, an insulating layer formed on the extended portion of the one electrode, and both ends electrically connected to the pair of electrodes. 1. A thermal head comprising a heating resistor formed on an insulating layer and a wear-resistant layer formed on top of the heating resistor. (2) The thermal head according to claim 1, wherein the heat generating resistor formed in the peripheral portion on the insulating layer is made thinner to form a high resistance portion.