JPS6072751A - Thermal head - Google Patents

Abstract

PURPOSE:To enable the adhesion of a heat generating resistor to a recording medium though preparing a thin film by providing a hump part on an insulation substrate to form a heat generating resistor made of a thin film thereon while an electrode conductor is made of a thick film. CONSTITUTION:A conductor layer 8 is formed on an insulation layer 7a partially protruding conically made of an insulating material with a low heat conductivity provided on an insulation substrate 1. Then, the conductor layer is etched to partially remove it on the insulation layer 7a humped conically and electrode patterns 81 and 82 are formed. If necessary, a thick film multi-layer circuit is formed on the electrode conductors 81 and 82. Then, a resistor is sputtered by several thousands A. The resistor layer thus obtained is etched to form a heat generating resistor 9a leaving it between electrodes 81... and 82... and then, a protective layer 10 is formed. Thus, the protruded part provided on the substrate ensures an accurate adhesion of the protective layer on the heat generating section to a recording medium thereby enabling a high-speed printing. This also permits the use of a thin film as heat generating resistor to reduce the cost by constructing the electrode conductor of copper in a thick film.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] Printers include electrostatic or electrophotographic printers that form an electrostatic latent image on a photosensitive drum, develop it, and transfer it to a printing medium, such as a laser printer. There are two types: one is an impact type, which prints by selectively applying pressure to the printing medium with a wire from above the ink ribbon, and the other is a thermal transfer type, which selectively heats the thermal transfer ribbon with a thermal head to melt the ink and transfer it. Alternatively, there is a thermal printer that selectively heats thermal paper with a thermal head to develop color. The present invention is directed to thermal transfer by selectively heating a thermal transfer ribbon for thermal transfer, or thermal printing by selectively heating thermal paper. Regarding ′.

[Technology background]

FIG. 1 is a front view of a thermal head for a serial printer, and FIG. 2 is a sectional view taken along line nn in FIG.

1 is a substrate made of sintered alumina, on which TaN (
A heat generating resistive film 2 is formed by sprocketing a resistor made of tantalum nitride. Then, on both sides of the resistive film 2, N
jCr, Au+Cr are sequentially deposited, and patterning is performed using a photolithography technique to form individual electrodes 31...
and a common electrode 32 is formed. FIG. 3 is a perspective view of the substrate 1'' in which the individual electrodes 31... and the common electrode 32 are provided on both sides of the resistive film 2 in this manner. As is clear from this figure, the resistive films 2 each having individual electrodes 31 and a common electrode 32 on both sides are arranged in one row.

Then, by applying current between the individual electrodes 31... and the common electrode 32 to generate heat in the desired resistance film 2, the platen 5
The thermal paper 6 wound around the paper is selectively heated to produce color and record.

Taz05 is placed on the plurality of resistive films 2..., individual electrodes 31... and common electrode 32 as shown in FIGS. 1 and 3.
A protective layer 4 having excellent abrasion resistance is formed by sputtering tantalum oxide (tantalum oxide) or the like to prevent abrasion caused by sliding with thermal paper or thermal transfer ribbon.

[Prior art and its problems]

However, as shown in FIG. 2, while the heat generating resistor 2 is formed of a thin film, the electrode conductors 31 and 32 are formed of thick films. However, the protective layer 4 is depressed, and the adhesion between the important heat-generating portion and the recording medium, ie, the thermal paper 6, deteriorates, resulting in a decrease in print quality.

If the heat-generating resistor is made of a thick film, it is possible to prevent the protective layer 4 from denting, but thick-film resistors can be mass-produced with inexpensive equipment and can be easily wired in multiple levels. accuracy is poor. On the other hand, in the case of a thin film type, it is difficult to obtain a fine and highly accurate heating resistor, it requires expensive equipment such as a vacuum device, and multilayer wiring is difficult. Therefore, it is effective to form the electrode conductor with an inexpensive thick film and to form the heat generating resistor with a thin film with high precision, but if this is done, the adhesion between the heat generating part and the recording medium will deteriorate as described above.

The thin film heating resistor 2 usually has a thickness of 1 μm or less, and the width of the thin film portion is about 150 to 200 μm, whereas the thickness of the thick film electrode conductor 31 and 32 is several tens of μm or more. It is. Therefore, it is extremely difficult to eliminate the recess on the two sides of the heating resistor.

Furthermore, in conventional thick-film thermal heads, electrode conductors are formed by printing gold paste over the mask or printing it all over the mask using potlithography, but since gold is used as the main conductor, the cost is high. It becomes. It is possible to replace gold with other inexpensive materials, but if silver-palladium is used instead of gold, silver-palladium has a high resistivity and cannot conduct a large current. It is also difficult to use thick film copper. That is, baking copper must be done in a nitrogen atmosphere to prevent oxidation, but there is no high-precision thick film resistor that can be baked in a nitrogen atmosphere. Therefore, if the heating resistor can be made of a thin film, there is also the advantage that the electrode conductor can be made of inexpensive copper.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such problems in conventional thermal heads, and to enable close contact with a recording medium even if the heat generating resistor is formed of a thin film that is easy to achieve accuracy.

[Structure of the invention]

The technical means according to the present invention taken to achieve this object is that an insulating substrate is provided with a heat generating resistor, an electrode conductor for supplying current to the heat generating resistor, and a heat generating resistor provided on the heat generating resistor. In a thermal head having a protective layer, an insulating substrate is provided with a raised part made of an insulating material with low thermal conductivity, a thin film heat generating resistor is formed on the upper side of the raised part, and the electrode conductor is formed of a thick film. are taken.

[Embodiments of the invention]

Next, examples will be used to explain how the thermal head according to the present invention is actually implemented. FIG. 4 is a sectional view and a plan view showing the manufacturing process and structure of the thermal head according to the present invention. First, as shown in (A), a glass paste 7 is applied in a band shape onto a substrate 1 made of a material with excellent mechanical strength and insulation properties, such as alumina. When fired, the glass paste 7 melts and flows, deforming into a mountain shape as shown in (b). Next is the copper paste on top of the mountain-shaped insulating layer 7a?・Coat No. 8 on the entire surface and bake in a nitrogen atmosphere to form a conductor layer. Next, the conductor layer is etched to remove the upper part of the insulating layer 7a which is ridged as shown in (d), and the electrode pattern 81.
Form 82. Then, if necessary, this electrode conductor 81
．． A thick film multilayer circuit is formed on top of 82. Next, as a resistor, for example, Ta-N-Al2O3 is sputtered several thousand times. This resistor is obtained by sputtering a target containing a mixture of ^1203 and Ta in the presence of nitrogen. Then, this resistor layer is etched, leaving only the space between each electrode conductor 81... and 82... as shown in (f), and after forming the heat generating resistor 961a, as shown in (1). Glass is applied thereon and fired in a nitrogen atmosphere to form the protective layer 10. During this firing, the ends of the electrode conductors 81.82 are softened, so that the level difference between the electrode conductors 81.82 and the raised layer 7a disappears. In order to prevent oxidation of the copper paste, a material that can be fired in a nitrogen atmosphere or the like is used for the protection N10.

Note that it is better for the raised layer 7a to be thicker in order to increase the adhesion with the recording medium, but if this is done, the raised layer 7a has low thermal conductivity and poor heat dissipation.

Therefore, when printing at high speed, the heating resistor and the protective layer become hot, which not only makes it impossible to obtain good printing, but also accelerates the deterioration of the thermal head. Therefore, the thickness of the raised layer 7a is preferably 50 μm or less, preferably about 30 to 40 μm.

〔Effect of the invention〕

As described above, according to the present invention, a raised part made of an insulating material with low thermal conductivity is provided on an insulating substrate, and a thin film heat generating resistor is formed on the upper side of the raised part, and the raised part is formed on the upper side of the raised part, and the raised part is formed on the raised part made of an insulating material with low thermal conductivity. I make sure that the parts that touch do not get depressed. Therefore, the protective layer on the heat generating part of the heat generating resistor comes into close contact with the recording medium, and the recording medium can be efficiently heated. In addition, since the raised part is made of a material with low thermal conductivity such as glass, the heat generated by the heating resistor will not escape to other places and will not reach the specified temperature. High-speed printing is possible. Furthermore, since a thin film can be used as the heating resistor, the electrode conductor can be made of a thick copper film, eliminating the need to use gold as in the past, and reducing the cost of materials.

[Brief explanation of drawings]

Fig. 1 is a front view showing the entire structure of a thermal heel 1 for use in a serial printer, Fig. 2 is a sectional view taken along line nn in Fig. 1, Fig. 3 is a perspective view of the electrode section, and Fig. 4 is a thermal heel according to the present invention. FIG. 1 is a cross-sectional view and a plan view illustrating the manufacturing process and the completed state. In the figure, 1 is a substrate, 2 is a heating resistor, 31 is an individual electrode, 32 is a common electrode, 4.10 is a protective layer, 6 is a recording medium, 7a is a raised layer, 81.82 is an electrode conductor, and 9a is Each heat generating resistor is shown. Patent Applicant Fujitsu Limited Agent Patent Attorney Minoru Aoyagi 9- Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] On an insulating substrate, a heat generating resistor, a temporary electrode conductor for energizing the heat generating resistor, and a heat generating resistor installed on the heat generating resistor.
In a thermal head having a protective layer, a raised part made of insulation + A material with low thermal conductivity is provided on an insulating substrate, a thin film heat generating resistor is formed on the upper side, and the electrode conductor is formed of a thick film. A thermal head characterized by: