JPH0557934A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a thermal head wherein occurrence of degradation of yield in manufacturing can be prevented even when high recording density is required, and the number of components can be reduced so as to make a structure small in size. CONSTITUTION:When light is emitted to a heat generating means 20, it is emitted to a photosensitive layer 14 through a transparent substrate 12 and a transparent electrode layer 13. Resistivity of a light receiving part 26 of the photosensitive layer 14 lowers, electric current 31 flows in the photosensitive layer 14 and a heat generating resistor layer 15 equivalent to the light receiving part 26, so that thermal printing is performed on a thermosensible paper 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head suitable for use in a facsimile communication device, a printing device of a word processor, a copying device for copying an original image or the like.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view of a conventional thermal head 1. Insulating substrate 2 made of electrically insulating material
A plurality of heat generating elements 3 are arranged on a straight line to form a heat generating element line 4. One common side of each heating element 3 is commonly connected to the common electrode line 5, and the other side of each heating element 3 is an individual electrode 6 formed for each heating element 3.
Is connected to a plurality of drive circuit elements 7 via. The common electrode line 5 and the individual electrode 6 are formed by patterning a metal thin film such as aluminum by a photolithographic technique.

The common electrode line 5 is formed on the insulating substrate 2
Is formed along the outer periphery of the. A signal line 8 for selectively energizing the heating element 3 to generate heat is connected to each drive circuit element 7, and each signal line 8 is connected to the external wiring board 9.
Connected to. The insulating substrate 2 having such a configuration is
Heat sink 1 made of a metal material such as aluminum
It is attached to 0.

[0004]

In such a conventional thermal head 1, as shown in FIG. 5, the heating elements 3 are arranged at the same density as the recording density of the thermal recording paper, for example.
Since the terminals of each drive circuit element 7 correspond to the individual electrodes 1 to 1, a large number of drive circuit elements 7 are required. Therefore, for example, when the recording density is 16 dots / mm or more, extremely high positioning accuracy is required for manufacturing the heating element 3 and the individual electrode 6, and there is a problem that the manufacturing yield is reduced. In addition, a large number of drive circuit elements 7 are required, the number of parts is increased, the cost is increased, and the configuration is enlarged.

The object of the present invention is to solve the above-mentioned technical problems, to prevent the production yield from decreasing even when high recording density is required, and to reduce the number of parts. An object of the present invention is to provide a thermal head that can be downsized.

[0006]

According to the present invention, a transparent electrode layer is provided on an electrically insulating transparent substrate, and a photosensitive layer made of a material whose specific resistance decreases during exposure is provided on the transparent electrode layer. And a heat generating means in which a heat generating resistor layer and an electrode layer are sequentially provided, and the transparent insulating substrate is selectively irradiated with light to partially lower the specific resistance of the photosensitive layer, thereby forming a transparent electrode layer and an electrode. The thermal head is characterized in that a heat-sensitive printing is performed by selectively energizing with a layer.

[0007]

In the thermal head according to the present invention, a transparent electrode layer is provided on a transparent substrate having electrical insulation properties, and a photosensitive layer made of a material whose specific resistance decreases during exposure is provided on the transparent electrode layer.
A heat generating means is provided in which a heat generating resistor layer and an electrode layer are sequentially provided on the photosensitive layer. The transparent insulating substrate is selectively irradiated with light to partially reduce the specific resistance of the photosensitive layer, and a current is selectively applied between the transparent electrode layer and the electrode layer to perform thermal printing.

Therefore, it is possible to eliminate the need to form the heating elements, which have the arrangement density corresponding to the recording density and are separated from each other, and the individual electrodes that define the heating elements with high precision, and to significantly improve the manufacturing yield. You can Further, a drive circuit element to which a predetermined number of heating elements separated from each other is connected is unnecessary, and the number of parts can be greatly reduced and the configuration can be downsized.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a thermal head 1 according to an embodiment of the present invention.
1 is a system diagram showing the configuration of FIG. 1, and FIG. 2 is a thermal head 1
It is sectional drawing of 1. The thermal head 11 of this embodiment is
For example, a transparent substrate 1 made of glass and having an electrical insulation property.
2, a transparent electrode layer 13 made of a transparent conductive material such as ITO (indium tin oxide) is formed on the entire surface of the transparent substrate 12.

On the transparent electrode layer 13, when a predetermined amount of light is received, the specific resistance of the light receiving portion is lowered. For example, a semiconductor such as alumophus silicon, a selenium-based inorganic semiconductor material, or an organic semiconductor material such as lophthalocyanine. A photosensitive layer 14 made of a material is formed on the entire surface. A heating resistor layer 15 made of tantalum nitride Ta ₃ N ₄ or the like is formed on the entire surface of the photosensitive layer 14, and a common electrode layer made of a metal material such as aluminum, copper, or gold is formed on the heating resistor layer 15. 16 is formed on the entire surface. The common electrode layer 16 is covered by forming a protective layer 17 made of an electrically insulating material such as SiN by a vacuum film forming method such as sputtering. The thermal paper 19 is pressed against the protective layer 17 by the platen roller 18, and thermal printing is performed as described later.

Such a transparent substrate 12 or protective layer 17
In order to form an optical image which is heat-sensitively printed on the transparent substrate 12 of the heat generating means 20 composed of the laminated body of the laser light generator 2
1 and a reflecting mirror 22 that reflects the laser light 30 from the laser light generator 21 to scan the transparent substrate 12 in the arrow A1 direction. The reflecting mirror 22 is rotationally driven by the driving device 23 in synchronization with the oscillation operation of the laser light generating device 21, and scans the transparent substrate 12, specifically, the photosensitive layer 14. At this time, the light spot 24 by the laser light on the photosensitive layer 14
The diameter d1 can be adjusted in accordance with a desired recording density by an optical system including the reflecting mirror 22 and the like.
For example, the diameter d1 is selected to be about 100 μm. A power supply 25 is connected to the transparent electrode layer 13 and a common electrode layer 16
Is connected to ground potential, for example.

For the photosensitive layer 14, a material is selected which has a characteristic that the specific resistance rapidly decreases when the radiant energy level such as the amount of light increases beyond the threshold value E0 as shown by the line L1 in FIG. The steeper the degree of decrease in the specific resistance is, and the smaller the threshold E0 is as small as possible in terms of energy efficiency.

The operation of this embodiment will be described below.
The laser light from the laser light generator 21 is reflected by the reflecting mirror 22 which is rotationally driven by the driving device 23, and the light spot 24 is formed on the photosensitive layer 14 via the transparent substrate 12 and the transparent electrode layer 13. At this time, as described above, the photosensitive layer 14
The specific resistance of the light receiving portion 26 of the light receiving portion 26 decreases, and the light receiving portion 26 passes through the photosensitive layer 14 and the heating resistor layer 15 corresponding to
A current 31 flows between the transparent electrode layer 13 and the common electrode layer 16. As a result, the heat-generating resistor layer 15 generates heat, and the heat-generating portion 32 performs heat-sensitive printing on the heat-sensitive paper 19.

In such an embodiment, as described in the conventional example, the heating element 3 which is separated from each other and independent of each other and the individual electrode 6 which defines the heating element 3 are formed by a highly accurate photolithographic technique. The need is eliminated and the manufacturing yield is greatly improved. Further, in the conventional example, the need to use the drive circuit elements 7 to which the predetermined number of individual electrodes 6 are connected is eliminated, the number of parts can be reduced and the cost can be reduced, and the drive circuit elements 7 need to be used. Is eliminated, the thermal head 11 can be remarkably downsized.

FIG. 4 is a system diagram showing the configuration of another embodiment of the present invention. This embodiment is similar to the above-mentioned embodiment, and corresponding parts are designated by the same reference numerals. The point to be noted in this embodiment is that the fluorescent layer 27 is formed on the light receiving side of the heat generating means 20, and the fluorescent layer 27 is scanned with the electron beam 29 from the electron gun 28 used in the television receiver. As a result, the fluorescent layer 27 emits light in a state corresponding to the electron beam 29, and the fluorescent light causes the heat generating means 20 to perform the heat-sensitive printing operation as described above.

Also in such an embodiment, the same effect as the effect described in the above embodiment can be obtained.

As another modification of the present invention, the means for supplying the optical image to the heat generating means 20 shown in FIG. 1 is not limited to the above-mentioned embodiment, and the optical image may be transmitted by an optical fiber, for example. Alternatively, a plane image may be directly formed on the photosensitive layer 14 in FIG. 1 by an optical image projection device. Alternatively, a light emitting diode array may be used.

[0018]

As described above, in the thermal head according to the present invention, the transparent electrode layer is provided on the transparent insulating substrate, and the photosensitive layer made of a material whose specific resistance decreases during exposure is provided on the transparent electrode layer. A heating means having a heating resistor layer and an electrode layer sequentially provided thereon is provided. Therefore, it is possible to eliminate the need to form with high precision the heating elements that are separated from each other and have the array density corresponding to the recording density, and the individual electrodes that define the heating elements, and it is possible to significantly improve the manufacturing yield. In addition, a drive circuit element to which a predetermined number of heating elements separated from each other are connected is not required, and the number of parts can be significantly reduced and the configuration can be downsized.

[Brief description of drawings]

FIG. 1 is a system diagram of a thermal head 11 according to an embodiment of the present invention.

FIG. 2 is a sectional view of a thermal head 11.

FIG. 3 is a graph illustrating characteristics of a photosensitive layer 14.

FIG. 4 is a system diagram showing a configuration of another embodiment of the present invention.

FIG. 5 is a perspective view of a conventional thermal head 1.

[Explanation of symbols]

 11 Thermal Head 12 Transparent Substrate 13 Transparent Electrode Layer 14 Photosensitive Layer 15 Heating Resistor Layer 16 Common Electrode Layer 20 Heating Unit 21 Laser Light Generator 22 Reflector 25 Power Supply 27 Fluorescent Layer 28 Electron Gun

Claims (1)

[Claims] 1. A transparent electrode layer is provided on an electrically insulating transparent substrate, a photosensitive layer made of a material whose specific resistance decreases during exposure is provided on the transparent electrode layer, and a heating resistor layer and an electrode layer are provided on the photosensitive layer. The transparent insulating substrate is selectively irradiated with light to partially lower the specific resistance of the photosensitive layer and selectively between the transparent electrode layer and the electrode layer. A thermal head characterized by being energized for thermal printing.