Thermal head having wear-resistant protective film

• US 20030035044A1
• Filed: 09/30/2002
• Published: 02/20/2003
• Est. Priority Date: 11/12/1992
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Endo, Tsukimi, Nakayama, Masatoshi, Nakano, Masahiro
• Granted Patent: US 7,106,356 B2
• Time in Patent Office: Days
• US Class Current: 347/203
• CPC Class Codes: B41J 2/345 characterised by the arrangement of resistors or conductors

Abstract

A method of producing a wear-resistant protective film for a thermal head comprises depositing a wear-resistant protective film by sputtering on a thermal head which includes a substrate, and a heat-developing layer and a pair of electrodes formed on either the substrate or a heat-regenerative layer formed thereon. A layer of the wear resistant protective film is formed under a RF larger bias and another layer without a bias or with a smaller bias. Good step coverage is obtained by the RF sputter layer of the wear-resistant and the protective film prevents the intrusion of water that can cause cracking, and the layer formed under no or smaller bias reduces internal stresses and inhibits the development of cracks due to internal stresses as well as the cracking by RF sputtering.

Claims

1. A wear-resistant protective film for a thermal head formed by sputtering in a sputtering gas, consisting essentially of a wear-resistant material selected from metal oxides, metal nitrides and a mixture thereof, characterized in that the wear-resistant protective film has a varying concentration of said sputtering gas in the direction of thickness.

2. A wear-resistant protective film for a thermal head according to claim 1, wherein at least one layer has a concentration of the sputtering gas of 0-3 at %.

3. A wear-resistant protective film for a thermal head according to claim 2, wherein at least another layer other than said at least one layer has a concentration of the sputtering gas of 2-10 at %.

4. A wear-resistant protective film for a thermal head according to claim 1, wherein the concentration of said sputtering gas varies continuously in the direction of the thickness and said at least one part of the film has a concentration of the gas between 0-3 at % and said at least another part has a concentration of the gas between 2-10 at % but greater than said at least one part.

5. A method of producing a wear-resistant protective film for a thermal head comprised of a substrate, a heat generating layer on the substrate and pair of electrodes on said heat generating layer, which comprises depositing, by sputtering, a wear-resistant protective film on said thermal head in a sputtering gas, characterized in that the wear-resistant protective film is formed by sputtering at least one part under a larger bias and at least another part without a bias or under a smaller bias.

6. A method of producing a wear-resistant protective film for a thermal head according to claim 5, wherein said at least one layer formed under no bias or the smaller bias has a concentration of the sputtering gas of 0-3 at %.

7. A method of producing a wear-resistant protective film for a thermal head according to claim 6, wherein said at least another layer formed under the larger bias has a concentration of the sputtering gas of 2-10 at % but larger than that in said at least one layer formed under no or smaller bias.

8. A method of producing a wear-resistant protective film for a thermal head according to claim 7, wherein said at least another layer formed under the larger bias has a thickness of 0.1-5 μ

m.

9. A method of producing a wear-resistant protective film for a thermal head according to claim 5, wherein said larger bias is in the range between −

50V and −

200V and the smaller bias is between 0 and ⅔

times as large the voltage of the larger bias.

10. A method of producing a wear-resistant protective film for a thermal head according to claim 5, wherein said larger bias is in the range between −

60V and −

120V and the smaller bias is between {fraction (1/10)}-½

times the voltage of the larger bias.

11. A method of producing a wear-resistant protective film for a thermal head according to claim 5, wherein the magnitude of said bias is continuously varied during the sputtering.