JPH06135030A - Thermal head - Google Patents

Abstract

PURPOSE:To allow high quality printing by pressing a protective layer, immediately above a heating part, well to a paper. CONSTITUTION:A protective layer 5, immediately above a heating part 3a provided on the top 2c of a heat storing layer 2, is set higher by 4-30mum than the protective layer 5 immediately above the highest part of electrodes 4a, 4b. In other words, the protective layer 5 immediately above the heating part 3a is protruded more than the protective layer 5 at other parts in order to increase contacting pressure with respect to a paper thus allowing high quality printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head mounted on a thermal printer for performing desired printing by selectively energizing and heating a heating element according to printing information. Regarding improvement.

[0002]

2. Description of the Related Art Generally, a thermal head mounted in a thermal printer has, for example, a plurality of heating elements linearly arranged on an insulating substrate and selects each heating element according to print information. By electrically heating
In a thermal printer, color recording is performed on a thermal recording paper, and in a thermal transfer printer, ink of an ink ribbon is melted and transferred and recorded on plain paper to perform printing.

FIG. 4 shows a conventional thermal head.

In FIG. 4, reference numeral 1 is a substrate made of an insulating material such as alumina, and a glaze layer 2 which is a heat storage layer made of glass is laminated on the substrate 1.
The glaze layer 2 has a flat upper surface,
In the region where the heating element 3 is to be formed on the upper surface of the glaze layer 2, a projection 2a having a substantially vertical trapezoidal cross section with the top 2c as a plane is integrally formed by photolithography.

On the glaze layer 2, the material of the heating element 3 made of Ta ₂ N, Ta-SiO ₂ or the like is laminated by sputtering or the like, and pattern-aligned by photolithography. Further, a plurality of heating elements 3 are formed so that the respective heating portions 3a are located on the protrusions 2a of the glaze layer 2.

On the heat generating elements 3 and the glaze layer 2, an electrode material such as A.sub.2 is laminated by sputtering or the like, and patterned by photolithography technique. Corresponding to, the common electrode 4a and the individual electrode 4b capable of selectively energizing each heating element 3 are formed on each heating element 3 on the plane portion 2b of the glaze layer 2.

Then, each heating element 3, common electrode 4a, individual electrode 4b and exposed glaze layer 2 are formed.
A protective layer 15 made of a material such as silicon nitride is laminated on the top by sputtering or the like.
The protective layer 5 has a single layer function of protecting the heat generating element 3 from deterioration due to oxidation and protecting the heat generating element 3 from abrasion due to contact with an ink ribbon or the like. 4b covers all the surface except the terminal portion.

In the thermal printer using the conventional thermal head described above, the thermal head is brought into pressure contact with the thermal paper, and the desired heat generating section 3 is generated based on predetermined print information.
By energizing the individual electrode 4b corresponding to a, the heat generating element 3 is caused to generate heat, and the heat generating portion 3a of the heat generating element 3 is caused to generate heat. Coloring is effected, and desired printing can be performed on the thermal paper.

[0009]

However, in the above-mentioned conventional thermal head, the height of the protective layer 5 immediately above the electrode 4 is the flat portion 2b which is the top of the glaze layer 2.
It is higher than the height of the upper heat generating portion 3a and is not so low as compared with the height of the protective layer 5 directly above the heat generating portion 3a on the plane portion 2b. The pressure contact with a large sheet is not so remarkable. Therefore, since the pressure contact pressure is small, the print quality is poor in both the thermal printer and the thermal transfer printer. In particular, in a thermal transfer printer, when printing is performed on rough paper having a rough surface, the print quality is significantly deteriorated.

The present invention provides a thermal head capable of overcoming the above-mentioned problems in the prior art and capable of printing a good quality by satisfactorily press-contacting a protective layer directly above a heat generating portion to a sheet. The purpose is to

[0011]

In order to achieve the above-mentioned object, the thermal head according to claim 1 of the present invention comprises a heat storage layer having partial projections laminated on a substrate, and the heat storage layer on the heat storage layer. A plurality of heating elements are formed so that each heating portion is located on the protrusion, and a common electrode and an individual electrode capable of selectively energizing each heating element are stacked, and the heat storage layer, each heating element and each In a thermal head in which an electrode is covered with a protective layer, the height of the protective layer directly above the heat generating portion on the top of the heat storage layer is increased by 4 to 30 μm from the height of the protective layer immediately above the electrode. It is characterized by having done.

Further, in the thermal head according to the second aspect, a heat storage layer having partial protrusions is laminated on the substrate,
A plurality of heat generating elements are formed on the heat storage layer so that the respective heat generating portions are located on the protrusions, and a common electrode and an individual electrode capable of selectively energizing each heat generating element are stacked to form the heat storage layer, In a thermal head in which a heating element and each electrode are covered with a protective layer, the height of the protective layer directly above the heat generating portion on the top of the heat storage layer is set to be 4 times higher than the height of the protective layer immediately above the electrode. The feature is that the height is increased by about 30 μm.

Further, the thermal head according to claim 3 is the thermal head according to claim 1 or 2, wherein the protective layer is C
It is characterized by being formed of a material whose main component is a mixture of r ₂ O ₃ and CrN.

[0014]

According to the thermal head of the present invention, the height of the protective layer directly above the heat-generating portion on the top of the heat storage layer is set to be 4 to 30 higher than the height of the protective layer directly above the highest level of all electrodes or individual electrodes.
By increasing the thickness by μm, the protective layer directly above the heat generating part can be made to protrude more than the protective layers of other parts, and as a result, the pressure contact pressure with respect to the paper becomes large, and good quality printing can be performed. it can.

The protective layer is made of Cr ₂ O, which has good wear resistance.
By using a material containing a mixture of ₃ and CrN as a main component, abrasion of the protective layer can be reduced even when it comes into sliding contact with thermal paper, and therefore the life can be extended.

[0016]

The present invention will be described below with reference to the embodiments shown in the drawings. It should be noted that the same or corresponding configurations as those of the above-described conventional one will be described with the same reference numerals in the drawings. FIG. 1 shows a first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a substrate made of an insulating material such as alumina, and a glaze layer 2 which is a heat storage layer made of glass is laminated on the substrate 1.
The glaze layer 2 has a flat upper surface,
A projection 2a having a substantially isosceles trapezoidal vertical cross section with a top 2c as a plane is integrally formed in a region where the heating element 3 is to be formed on the upper surface of the glaze layer 2 by photolithography.

On the glaze layer 2, the material of the heating element 3 made of Ta ₂ N, Ta-SiO ₂ or the like is laminated by sputtering or the like, and patterned by photolithography technique to be aligned. Further, a plurality of heating elements 3 are formed so that the respective heating portions 3a are located on the tops 2c of the protrusions 2a of the glaze layer 2.

On the heating elements 3 and the glaze layer 2, an electrode material such as A.sub.2 is laminated by sputtering or the like, and patterning is performed by photolithography technique. Corresponding to, the common electrode 4a and the individual electrode 4b capable of selectively energizing each heating element 3 are formed on the projection 2a of the glaze layer 2 and each heating element 3 on the flat surface portion 2b.

Then, each heating element 3, common electrode 4a, individual electrode 4b and exposed glaze layer 2 are formed.
A protective layer 15 made of a material such as silicon nitride is laminated on the top by sputtering or the like.
The protective layer 5 has a single layer function of protecting the heat generating element 3 from deterioration due to oxidation and protecting the heat generating element 3 from abrasion due to contact with an ink ribbon or the like. 4b covers all the surface except the terminal portion.

By the way, in this embodiment, the height of the heat generating portion 3a of the heat generating element 3 located on the top 2c of the protrusion 2a of the glaze layer 2 is equal to the slope 2d of the protrusion 2a of the glaze layer 2.
The height is made "a" higher than the height of the protective layer 5 covering the end portions of the common electrode 4a and the individual electrode 4b located above. This “a” may be at least 0.

The height of the protective layer 5 covering the heat generating portion 3a of the heat generating element 3 is located on the slope 2d of the protrusion 2a of the glaze layer 2 and the common electrode 4a and the individual electrode 4b. Is higher than the height of the protective layer 5 which covers the end portions thereof by "b". This “b” is preferably between 4 and 30 μm. That is, this “b” is 30 μm
If you try to configure the thermal head to exceed
This is because the angle formed between the inclined surface 2d of the projection 2a of the glaze layer 2 and the flat surface portion 2b becomes too large, and the possibility of disconnection of the electrode 4 becomes too large near the intersection of the inclined surface 2d and the flat surface portion 2b. Further, if "b" is less than 4 μm, the pressure contact pressure of the protective layer 5 covering the heat-generating portion 3a of the heat-generating element 3 against the paper cannot be increased so much, which adversely affects the print quality. is there.

Further, the protective layer 5 is formed of a material whose main component is a mixture of Cr ₂ O ₃ and CrN having good wear resistance.

Next, the operation of this embodiment having the above-mentioned structure will be described.

FIG. 2 shows a thermal transfer printer using the thermal head of the embodiment of FIG. 1. In this embodiment, the thermal head 10 is applied with a certain pressure contact pressure F to the platen via the ink ribbon 11 and the paper 12. When the thermal head 10 is moved in the direction of the thick arrow in FIG. 2 to perform printing while the carriage (not shown) is pressed against the thermal head 13, the thermal head 10 in FIG. The height of the protective layer 5 covering the heating portion 3a of the element 3 is determined by the slope 2d of the protrusion 2a of the glaze layer 2.
Since the height of the protective layer 5 covering the end portions of the common electrode 4a and the individual electrode 4b located above is increased by 4 to 30 μm, the ink ribbon 11 and the paper 12 are formed.
Is raised by several 100 μm on the individual electrode side of the thermal head 10 due to the pressure contact pressure F. As a result, the ink ribbon 11 is heated by the heat generating portion 3 of the heat generating element 3 of the thermal head 10.
The area in contact with the protective layer 5 on a is increased, and the heat transfer from the thermal head 10 to the ink ribbon 11 is improved. Therefore, good quality printing can be performed.

Further, since the protective layer 5 is formed of a material containing a mixture of Cr ₂ O ₃ and CrN, which has good abrasion resistance as a main component, the protective layer 5 is easily worn by a thermal printer. Even when the head is used, the protective layer 5 is less likely to wear, and therefore the life of the thermal head can be extended.

FIG. 3 shows a second embodiment of the thermal head of the present invention. In this embodiment, unlike the embodiment of FIG. 1, the above-mentioned dimension "a" is provided on the common electrode 4a side. , "B" are not satisfied, and only the individual electrode 4b side is satisfied with the above-described conditions of dimensions "a" and "b". This is because the ink ribbon 11 and the paper 12 do not tend to rise on the common electrode 4b, which is on the back side of the individual electrode 4b in the running direction of the thermal head 10 at the time of printing, so that the above-mentioned dimension "a", This is because it is not necessary to satisfy the condition “b”.

Also in such an embodiment, the above-mentioned first
The same effect as that of the embodiment can be obtained.

The present invention is not limited to the above-mentioned embodiment, but various modifications can be made if necessary.

[0030]

As described above, according to the thermal head of the present invention, it is possible to obtain excellent effects of maintaining good printing quality and prolonging the service life.

[Brief description of drawings]

FIG. 1 is a sectional view of a thermal head showing a first embodiment of the present invention.

2 is an enlarged cross-sectional view of a main part of a thermal transfer printer to which the thermal head of FIG. 1 is applied.

FIG. 3 is a sectional view of a thermal head showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional thermal head.

[Explanation of symbols]

 1 Substrate 2 Glaze Layer (Heat Storage Layer) 2a Protrusion 2b Plane 2c Top 2d Slope 3 Heater 3a Heater 4 Electrode (general) 4a Common Electrode 4b Individual Electrode 5 Protective Layer 10 Thermal Head 11 Ink Ribbon 12 Paper

Claims (3)

[Claims] 1. A heat storage layer having partial protrusions is laminated on a substrate, and a plurality of heat generating elements are formed on the heat storage layer so that respective heat generating portions are located on the protrusions. In a thermal head in which a common electrode and an individual electrode that can be selectively energized are laminated, and the heat storage layer, each heating element, and each electrode are covered with a protective layer, directly above the heating portion on the top of the heat storage layer. The thermal head is characterized in that the height of the protective layer is higher than the height of the protective layer directly above the highest electrode by 4 to 30 μm. 2. A heat storage layer having partial protrusions is laminated on a substrate, and a plurality of heat generating elements are formed on the heat storage layer so that respective heat generating portions are located on the protrusions. In a thermal head in which a common electrode and an individual electrode that can be selectively energized are laminated, and the heat storage layer, each heating element, and each electrode are covered with a protective layer, directly above the heating portion on the top of the heat storage layer. The thermal head is characterized in that the height of the protective layer is higher than the height of the protective layer directly above the highest electrode of the individual electrode by 4 to 30 μm. 3. The thermal head according to claim 1, wherein the protective layer is formed of a material whose main component is a mixture of Cr ₂ O ₃ and CrN.