JPS6282053A - Thermal head - Google Patents

Abstract

PURPOSE:To enable high speed recording imparting good image quality by reducing the heat accumulation quantity in the glaze layer provided beneath the under the heat generating resistor and enhancing the heat response of the heat generaiting resistor, by respectively setting the thickness of the glaze layer of a thermal head and the length of the heat generating part of the heat generating resistor in a sub-scanning direction to specific range values. CONSTITUTION:A glaze layer 2 is provided on a base plate 1 and a large number of heat generating resistors 3 are arranged on said glaze layer 2 in a main scanning direction so as to correspond to the number of picture elements of one line. A lead layer 4 supplies power to the heat generating resistors 3 and an abrasion resistant layer 5 is provided on the upper layers of the heat generating resistors 3. In order to prevent the heat capacity of the glaze layer 2 from becoming excessively large and the heat response of the heat generating resistors 3 becoming inferior and blotting from being generated in a recording dot to deteriorate image quality, the thickness of the glaze layer is set to 10-20mum. Further, in order to prevent the deterioration of image quality, the length of the heat generating part of each heat generating resistor in a sub-scanning direction is set to 100-130mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal head used for facsimile and the like, and particularly to a structure of a thermal head suitable for improving image quality during high-speed recording.

2. Description of the Related Art A conventional thermal conductor has a substrate 1 as shown in FIG.
A glaze layer 2 is provided on top, and heating resistors 3 corresponding to the number of recording pixels for one line in the main scanning direction are arranged on the surface of this glaze layer, and power is supplied to each of these heating resistors 3. A lead layer 4 is provided, and a wear-resistant layer 5 for preventing oxidation and wear of the heating resistor 3 is disposed on top of the lead layer 4.

Further, as shown in FIG. 4, the glaze layer 2 is connected to the heating resistor 3.
Some are partially installed only under the .

The dimensions of the heating part of the heating resistor 3 vary depending on the application, but in the case of a normal facsimile, a resolution of 8 lines/mrx in the main scanning direction and 7.7 lines/mrx in the sub-scanning direction is required. . If you simply calculate this, the main scanning direction is 125μm.
, the sub-scanning direction is 130 μm, but the normal factor S
The heating resistor of the thermal head for IJ has a main running direction of 1.
00~110μm, sub-scanning direction is 17C1~200μm
m. This is because, in the main scanning direction, it is necessary to separate the heating resistors 3 arranged in one row, so a gap must be provided between them. Therefore, the dimensions of the heating resistors 3 in the main scanning direction are Slightly shorter than 125μm1
It was 00 to 110 μm.

Regarding the sub-scanning direction, as shown in FIG. 5 (IL), the heating portion 3a of the heating resistor is usually rectangular;
As shown in Figure (b), the recorded Y'sotob becomes rounded. If the length of the heating portion 32L of the heating resistor 3 in the sub-scanning direction is set to the theoretically required length of 130, αm, there will be a gap at the corner between the recording dots, as shown in FIG. 5(C). occurs, degrading the image quality. Therefore, conventional measures have been taken to fill in the gaps by overlapping recording dots to some extent as shown in FIG. 5(d), and in this case the dimension in the sub-scanning direction was 170 to 200 μm.

On the other hand, the glaze layer also affects image quality. If the glaze layer is too thick, heat will be accumulated intensely and the thermal response of the heating resistor will be reduced, leading to deterioration in image quality such as trailing and blurring. However, conversely, as the glaze layer becomes thinner, the power efficiency during color development tends to deteriorate. Currently, the recording time is sms/mm.
Approximately 1ine, glaze layer thickness is 60~80μ
m was used.

Problems to be Solved by the Invention However, it has been found that the above-mentioned thermal head has a problem in that image quality deteriorates significantly when recording is performed at 2ms, 4ins, or at a higher speed.

The inventors of the present invention have investigated various reasons for the above-mentioned problems and have found the following. In other words, when the recording speed is increased, the period of pulses applied to the heating resistor becomes faster, and a thermal head with a glaze layer thickness of 60 to 8 Qμm can generate a recording speed of 2ms/l process n.
When e-recording is performed, the thermal response of the heating element cannot follow the applied pulse cycle, and the recorded dots smear. Also,
Heat accumulation is also intense, and so-called thermal history control, which controls applied power by referring to past recorded conditions, becomes complicated. However, the more complex the thermal history control is, the more time it takes to control it; on the contrary, the higher the speed of recording, the more it is necessary to shorten the control time, so this point also poses a new problem. Become.

In addition, the time for the thermal recording paper to actually develop color, the so-called effective color development time, is constant, and the ratio of the effective color development time to the recording time of one line is small for sms/1ine recording, but for 2 mg/1ine recording or When the speed is higher than that, this ratio becomes large, and as a result, the recording dots extend in the sub-scanning direction, which causes deterioration in image quality.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a thermal head that can perform recording at 2 ms/1ine recording speed or higher speed without deteriorating image quality.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a glaze layer provided on a substrate, a glaze layer arranged on the glaze layer in the main scanning direction, and a number of recording pixels for one line. The glaze layer has a large number of corresponding heating resistors, a lead layer for supplying power to the heating resistors, and a wear-resistant layer provided on the heating resistor. is 10 μm or more, 2
0 μm or less, and the heat generating resistor provides a thermal head in which the heat generating portion in the sub-scanning direction is 100 μm or more and 130 μm or less.

According to the above-described structure, the present invention reduces the amount of heat stored in the glaze layer on the lower surface of the heating resistor, improves the thermal responsiveness of the heating resistor, prevents smearing of recorded dots, and reduces the size of the heating portion of the heating resistor. Since the value is also set to an appropriate value, high-speed recording with good image quality is possible. That is, it is possible to record with a resolution of 7 lines/feather in the sub-scanning direction and a recording time of 2 ms/1 inch or less.

Embodiment The embodiment of the present invention will be described below with reference to the drawings. 1st
The figures schematically show the configuration of a thermal head according to an embodiment of the present invention, in which (a) is a diagram showing the shape and dimensions of a heat generating portion 3a of a heating resistor, and (b) is a sectional view of the thermal head. 1 is a substrate; 2 is a glaze layer provided on the substrate; 3 is a large number of heating resistors arranged in the main scanning direction on the glaze layer and provided corresponding to the number of recording pixels for one line;
Reference numeral 4 designates a lead layer for supplying power to the heat generating resistor, and reference numeral 5 designates a wear-resistant layer provided on the upper layer of the heat generating resistor.

A recording test was conducted with respect to an example in which the materials, dimensions, physical properties, etc. of each of these layers were set as follows.

Here, a ceramic such as alumina is suitable for the substrate. The glaze layer has insulation, heat insulation, and heat resistance properties, and glass is usually used. For the heating resistor, a cermet-based resistance material, 5i-Ta, or the like is used. The lead layer is composed of a metal layer, and Gu is usually used. Furthermore, as a wear-resistant layer, 1iIl whose main component is SiC is used.
t wear material was used.

(1) Substrate material Person 1□03 Thickness 0.64m Shoulder thermal conductivity 0.04C Otsu1/α・East ・°C (2)
Glaze layer material Glass composition 5i02 53% Ba0 21% CaO14% Human 1205 6% Others 6% Thickness 15μm Heat transfer coefficient 0.002 cal/n -5eC, 6c
, (3) Heating resistor material Cermet-based resistor material Thickness 0.1 μm Total heating part dimensions 100 μm (main scanning direction) 130 μm (W
'J scanning direction) (4) Lead layer material: Cu Thickness: 0.6 μm (@ Wear-resistant layer material: Wear-resistant material mainly composed of SiC Thickness: 4 μm For comparison, all glaze layers were made of the same material as in Example 1j above. The thickness is 60 μm, the heating resistor is made of the same material, and the total heating part dimensions are 10 μm (main scanning direction) x 17
A recording test was conducted using a conventional thermal head with a diameter of 0 μm (in the sub-scanning direction).

When we compared the image quality when recording was performed at a speed of 2ms/1ine and 1ms/1ine, we found that the image quality with the thermal head of this embodiment was superior to that of the conventional one in both cases. Ta. In addition, with the thermal head according to this embodiment, sufficient image quality was obtained without performing any thermal history control.

In the above embodiments, the glaze layer 2 is provided on the entire surface of the substrate, but the present invention is not limited to this structure, and the glaze layer 2 is provided only on the lower part of the heating resistor 3 as shown in FIG. Good too. The glaze layer thickness in this case indicates the distance from the substrate 1 to the top of the glaze layer 2.

Here, if the thickness of the glaze layer is reduced to 10 μm, the thermal insulation will be insufficient and the power efficiency during coloring will be significantly reduced.
However, if the glaze layer thickness is 0 μm, almost no color will develop.

Furthermore, it is difficult to uniformly form a glaze layer thinner than 10 μm in terms of manufacturing. On the other hand, if the thickness of the glaze layer is increased to 20 μm, the heat capacity of the glaze layer becomes too small and the thermal response of the heating resistor deteriorates, causing bleeding in the recorded dots and deteriorating the image quality.

Therefore, in the present invention, the glaze layer thickness is set to 10-. 20μm
has been selected. Furthermore, if the dimension of the heating part of the heating resistor in the sub-scanning direction is shorter than 100 μm, gaps will be created between recording dots, and conversely, if it is longer than 130 ttrn,
When a recording dot extends too long to record a white spot, the white spot is crushed by adjacent recording dots in the sub-scanning direction, and in either case, the image quality deteriorates. Therefore, in the present invention, the length of the heat generating part of the heat generating resistor in the sub-scanning direction is set to 130 to 130 mm.
It has been selected to be μm.

Effects of the Invention As is clear from the above explanation, the present invention has a thermal head with a glaze layer of 10 μm or more and 2011 m or less,
By setting the length of the heating part of the heating resistor in the sub-scanning direction to 100 μm or more and 130 μm or less, it is possible to perform recording even when the resolution in the sub-scanning direction is Otsu 7*/gate and the recording time is 2 ms/linθ or less. This has the effect that high image quality can be obtained.

[Brief explanation of drawings]

FIG. 1 shows a thermal head according to an embodiment of the present invention, in which (a) is a plan view of the heat generating part of the heating resistor, (b) is a schematic view from one side, and FIG. 3 and 4 are schematic side views showing the embodiment of the conventional thermal head, and FIG. FIG. 3 is a plan view of the recording dots of FIG. DESCRIPTION OF SYMBOLS 1 - Substrate, 2... Glaze layer, 3... Heating resistor, 4... Lead layer, 5... Wear-resistant layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 7-8 Figure 2-1 Goods layer J-11 Body Figure 2 Figure 3 Figure 5) (b) (C) (da)

Claims (1)

[Claims] A glaze layer provided on the substrate, a large number of heating resistors arranged in the main scanning direction on the glaze layer corresponding to the number of recording pixels for one line, and power to the heating resistors. The glaze layer has a lead layer for supplying the lead layer and a wear-resistant layer provided on the upper layer of the heating resistor, and the glaze layer has a thickness of 1.
0 μm or more and 20 μm or less, and the heating resistor has a heat generating portion in the sub-scanning direction of 100 μm or more and 130 μm or less.