Thermal head

• US 4,786,916 A
• Filed: 12/02/1986
• Issued: 11/22/1988
• Est. Priority Date: 12/25/1985
• Status: Expired due to Fees

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Kato, Masakazu
• Primary Examiner(s): Goldberg, E. A.
• Assistant Examiner(s): PRESTON, GERALD
• Application Number:
  US06/936,795
• Time in Patent Office: 721 Days
• Field of Search: 346/76 PH, 219/216, 400/120, 338/308, 427/58, 427/96, 427/103, 427/402, 427/311, 427/315, 427/325, 428/615, 428/621, 428/627, 428/629
• US Class Current: 347/200
• CPC Class Codes: B41J 2/3353 Protective layers
• CPC Class Codes: B41J 2/33545 characterised by dimensions
• CPC Class Codes: B41J 2/3355 characterised by materials
• CPC Class Codes: B41J 2/3357 Surface type resistors
• CPC Class Codes: Y10T 428/12493 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
• CPC Class Codes: Y10T 428/12576 Boride, carbide or nitride component
• CPC Class Codes: Y10T 428/1259 Oxide

Abstract

A thermal head in which a glazed layer, an improved undercoat layer, a heat generating resistor layer, an electrical power supply conductor layer and a protection layer are successively laminated to the surface of an insulating substrate, in which the undercoat layer is composed of an aluminum nitride (AlN) film. The method of manufacturing the thermal head comprises forming the aluminum nitride (AlN) film by sputtering an Al target in a gas mixture of argon and nitrogen and forming the heat generating resistor layer and the electrical power supply conductor layer, that is, three layers in total successively formed by sputtering. Because of the good heat conductivity of aluminum nitride film, the temperature distribution in the heat generating portion is made uniform and localized heat generation can be avoided, as it also prevents the destruction of the heat generating resistor layer or the protection layer due to the temperature difference upon heat generation. The temperature distribution in the heat generating portion is made uniform to eliminate the heat generation dots destructed at an applied low electric power, thereby significantly improving the reliability of the thermal head. Further, by the method of manufacturing the thermal head according to this invention, the continuity between each of the layers is favorable and a thermal head of a high reliability can be obtained.

Claims

1. A thermal head in which a glaze layer, an undercoat layer, a heat generating resistor layer, an electric power supply conductor layer and a protection layer are successively laminated in series on the surface of an insulating substrate, wherein said undercoat layer is made of an aluminum nitride (AlN) film having high bonding strength to the glaze layer and the heat generating resistor layer and a good thermal conductivity characteristic so as to evenly distribute heat generated by said heat generating resistor layer and reduce thermal stress, and wherein said protection layer is made of a silicon dioxide (SiO₂) film.

2. A thermal head as defined in claim 1, wherein the film thickness of the alumimum nitride film is set to between 500 Å

and 5000 Å

.