JPH07329330A - Thermal print head and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a thermal head in which high flatness is obtained on the surface of the head and various type cards, an optical disk, a cartridge, etc., having rigidity can be printed by high quality by forming the head via surface processing steps of flattening the surface of the head in contact with the surface side to be printed. CONSTITUTION:A thermal print head is composed by sequentially forming as thin films a glazed layer 2 coated and baked on a base material 1, a heat generating resistor 3, an electrode 4, a resistor protective layer 5 and a wear- resistant layer 6 on the layer 2. In this case, a surface processing step for flattening the surfaces is provided in the steps after the step of forming the layer. As a result, since the head having excellent flatness can be obtained, even when a matter to be printed with high hardness and rigidity (e.g. a credit card, a compact disk) is printed, the head is brought into contact with the matter to be printed in completely equal contact pressure, thereby printing with high quality level without unevenness in its printing density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal print head used in a thermal transfer printer.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing the general structure of a thermal print head used in a conventional thermal transfer printer. In FIG. 3, this thermal head is
It has a structure in which a ceramic substrate 1, a glaze layer 2, a heating resistor 3, an electrode 4, a resistor protection layer 5, and an abrasion resistant layer 6 are laminated in this order.

Of these, the ceramic substrate 1 is the base material of the thermal print head, and alumina ceramic Al ₂ O ₃ is often used as the material. The glaze layer 2 functions as a heat resistance layer for heat flow from the heating resistor 3 to the ceramic substrate 1, and glass (soda lime glass) is often used as the material. The heating resistor 3 is a heat generation source of the thermal print head, and the material thereof is Ta ₂ N, TaN, SiTa, TaS.
iO ₂ etc. are often used. The electrode 4 applies a current to the heating resistor 3, and gold Au is often used as the material.
The resistor protection layer 5 is for preventing the heating resistor 3 from being oxidized, and SiO ₂ or the like is often used as a material. Wear resistant layer 6
Is to withstand sliding friction during printing, and Ta ₂ O ₃ or SiC is used as the material.

FIG. 4 shows an example of a general manufacturing method for the thermal print head. The manufacturing method will be described with reference to FIG. 4. First, molten glass is applied onto the ceramic substrate 1 and Is baked to obtain the glaze layer 2 having a thickness of about 40 μm to 80 μm (see step a). Next, on the glaze layer 2, a heating resistor 3 (thickness of about 0.1 to 0.5 μm) and an electrode 4 (about 1 to 5 μm) are sequentially formed.
Thickness), the resistor protective layer 5 (about 2 μm thick), and the abrasion resistant layer 6 (about 4 to 10 μm thick) are formed by vacuum deposition or sputtering (see step b).

[0005]

As described above, in the thermal print head having this structure, the surface of the completed thermal print head, that is, the head surface may have an uneven portion. Then, when examining the cause of the non-flat portion, first, the formation layer after the heating resistor 3 formed on the glaze layer 2 is a thin film, which is formed by the vacuum deposition method or the sputtering method. Even if the method described above is used, uneven thickness is unlikely to occur. Therefore, if there is a non-smooth portion on the surface of the completed thermal print head, it is considered that it is in accordance with the surface condition of the glaze layer 2. Moreover, the glaze layer 2
Since baking is performed, it is generally difficult to obtain sufficient flatness on the surface.

Therefore, by using the thermal print head completed with the non-flat portion on the surface as described above, the thermal print head has high hardness and is rigid.
For example, when printing is performed on a plastic card such as a credit card or a prepaid card, an optical disk for recording information such as a compact disc, or a cartridge or a case of a magnetic recording medium such as a magnetic tape, the thermal print head and the object to be printed are completely There is a part that does not come into contact with, or the contact pressure varies even if it comes into contact. Then, there is a problem that the print density becomes low in the non-contact portion and the portion where the contact pressure becomes small, and as a result, print unevenness occurs and the print quality is deteriorated. In reality, when a head having a width of about 9 mm has a dent of about 2 μm or more, print unevenness occurs.

The present invention has been made in view of the above problems, and an object thereof is to obtain high flatness on the head surface and to improve rigidity on various rigid cards, optical disks, cartridges and the like. It is an object of the present invention to provide a thermal print head capable of performing quality printing and a manufacturing method thereof. Furthermore, other purposes will be clarified one after another in the content described below.

[0008]

This object is achieved in the present invention by performing a surface processing step for flattening the head surface which is brought into contact with the printing surface side. It

[0009]

According to this, the head surface abutting on the surface to be printed is further smoothed, and a thermal print head having a good flatness can be obtained. Therefore, since the head surface is flat, the material to be printed has high hardness and rigidity, such as a plastic card such as a credit card or a prepaid card, an information recording optical disk such as a compact disk, or a magnetic tape. Even when printing is performed on the cartridge or case of the magnetic recording medium, the thermal print head and the printing object come into contact with each other at substantially the same contact pressure.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a cross-sectional view of essential parts of a thermal print head used in a thermal transfer printer shown as an embodiment of the present invention. In FIG. 1, the same reference numerals as those in FIG. 3 correspond to the members in FIG.

In FIG. 2, the thermal print head comprises a ceramic substrate 1, a glaze layer 2, a heating resistor 3, an electrode 4, a resistor protective layer 5 and an abrasion resistant layer 6 which are sequentially laminated. The structure is the same as the conventional structure shown in FIG.

Further, (1) the ceramic substrate 1 is a base material of a thermal print head, and alumina ceramic Al ₂ O ₃ is used as a material, and (2) glaze layer 2
Serves as a thermal resistance layer for the heat flow from the heating resistor 3 to the ceramic substrate 1, and glass (soda lime glass) is used as the material. (3) The heating resistor 3 is a thermal print head. Heat source, Ta ₂ N as material
The point that TaN, SiTa, TaSiO ₂ etc. are used. (4) The electrode 4 gives a current to the heating resistor 3, and the material is gold.
Au is used, (5) The resistor protective layer 5 is for preventing the heating resistor 3 from being oxidized, and SiO ₂ or the like is used as a material. (6) The abrasion resistant layer 6 is used for printing. This is also the same as the conventional head structure shown in FIG. 3 in that it can withstand the sliding friction and is made of Ta ₂ O ₃ , SiC or the like. A major difference from the structure of the conventional thermal print head is that the structure of the present embodiment has an extremely smooth surface of the abrasion resistant layer 6 as compared with the structure of the related art. Further, the thermal print head having the abrasion resistant layer 6 having a high smoothness on the surface can be achieved by the following method.

FIG. 1 is a process diagram for manufacturing the thermal print head, and an example of the manufacturing method will be described below using the process. First, molten glass is applied on the ceramic substrate 1 and baked to obtain a glaze layer 2 having a thickness of about 40 μm to 80 μm (step A).
reference). Next, the glaze layer surface processing is performed to make the glaze layer 2 smooth and straight (see step B). Then, on the surface-processed glaze layer 2, a heating resistor 3 (about 0.1 to 0.5 μm thick), an electrode 4 (about 1
.About.5 .mu.m thick), the resistor protective layer 5 (about 2 .mu.m thick), and the abrasion resistant layer 6 (about 4 to 10 .mu.m thick) are formed by vacuum deposition or sputtering (see step C). As a result, the thermal print head shown in FIG. 2 in which the surface of the abrasion resistant layer 6 is extremely smooth is formed.

There are various possible surface treatments for making the surface (head surface) of the glaze layer 2 smooth and straight, for example, a method of lapping or polishing. Here, when the surface processing of the glaze layer 2 is performed by the lapping method, attention must be paid to the following points (1) to (4). (1) Glass is used as the material for the glaze layer 2, which is a brittle material, and chipping (chipping) easily occurs during processing. Therefore, the surface plate (lap surface plate) used for lapping is preferably made of a soft material. (2) In addition, if the lapping surface of the lapping plate is not smooth and has high straightness, the smoothness and straightness of the surface of the glaze layer 2 will be affected. You need to use one. (3) Next, in the case of lapping, the lapping agent is thinly applied on a precisely finished lapping plate, and the surface (head surface) side of the glaze layer 2 is applied to the lapping plate coated with the lapping agent. And wrap it. Further, it is desirable not to use a lapping agent having a very high hardness so as not to cause chipping on the surface of the glaze layer 2 during lapping. Furthermore, it is advisable to dissolve the wrapping agent with a small amount of oil or water to form a paste, and apply it thinly on the flat surface of the lap platen for lapping. To (4) In addition, since the flatness of the lapping plate directly influences the finishing accuracy of the flatness of the surface of the glaze layer 2, if the flatness goes wrong during lapping, the flatness is finished again. It is better to always maintain the flatness of the lapping plate. By doing so, it is possible to obtain the glaze layer 2 having good surface flatness by the lapping method.

In the above embodiment, a surface processing step for improving smoothness and straightness is applied after the glaze layer 2 is applied. However, during or after the glaze layer 2 is applied, a thin film forming step or a thin film forming step is performed. A surface processing step for smoothing the surface and improving the straightness may be added later. That is, surface processing may be performed at least once somewhere during the manufacturing process of the thermal print head so as to smooth the printing surface side of the thermal print head and improve straightness. However, if the surface treatment is performed before the abrasion resistant layer 6 and the thin film of another layer is further formed thereon, the surface roughness will be slightly improved.

[0016]

As described above, according to the present invention,
Since a thermal print head with good flatness can be obtained, it has a high hardness and a high rigidity, such as a printed material such as a plastic card such as a credit card or a prepaid card, an optical disk for recording information such as a compact disk, and a magnetic tape. Even when printing is performed on the cartridge or case of the magnetic recording medium, the thermal print head and the printing object come into contact with each other at substantially the same contact pressure. Therefore, it is possible to perform high-quality printing with uniform print density. Further, even when printing is performed on a general paper medium that can be printed by the conventional thermal transfer printing, clearer printing can be performed as compared with the case where the conventional thermal print head is used. In particular, the printing method using the sublimation thermal transfer printing method has less uneven color,
It enables very high quality color printing.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a manufacturing method of the present invention.

FIG. 2 is a cross-sectional view of essential parts of a thermal print head manufactured by the method of this embodiment.

FIG. 3 is a cross-sectional view of essential parts of a thermal print head manufactured by a conventional method.

FIG. 4 is a diagram for explaining a conventional manufacturing method.

[Explanation of symbols]

 1 Ceramic Substrate 2 Glaze Layer 3 Heating Resistor 4 Electrode 5 Resistor Protective Layer 6 Abrasion Resistant Layer

Claims (5)

[Claims] 1. A method for manufacturing a thermal print head, characterized in that the thermal print head is manufactured through a surface processing step for flattening a head surface which is brought into contact with a printing surface side. 2. A method of manufacturing a thermal print head comprising a glaze layer coated and fired on a base material, and a heating resistor, an electrode, a resistor protection layer, and a wear-resistant layer, which are sequentially formed on the glaze layer as thin films. In the method, a surface processing step for flattening the surface of the glaze layer is provided during the step of forming the glaze layer and thereafter, and a method for manufacturing a thermal print head. 3. The surface processing step is provided immediately after the step of forming the glaze layer, and the heating resistor, the electrode, the resistor protective layer and the abrasion resistant layer are formed as a thin film by a vacuum deposition method or a sputtering method. The method for manufacturing a thermal print head according to claim 1, wherein 4. A thermal print head manufactured through a surface processing step for flattening a head surface abutting on a printed surface side. 5. A thermal print head comprising: a glaze layer coated and fired on a substrate; and a heating resistor, an electrode, a resistor protection layer, and a wear-resistant layer, which are sequentially formed on the glaze layer as thin films. A thermal print head characterized by being subjected to a surface treatment for flattening the surface when forming the glaze layer and thereafter.