Capacitance sensor

• US 5,719,740 A
• Filed: 02/01/1996
• Issued: 02/17/1998
• Est. Priority Date: 12/07/1993
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hirao, Takashi, Hayashi, Shigenori, Kamada, Takeshi, Torii, Hideo
• Primary Examiner(s): Ledynh, Bot L.
• Application Number:
  US08/595,240
• Time in Patent Office: 747 Days
• Field of Search: 361/283.1, 361/283.2, 361/283.3, 361/283.4, 73/718, 73/724
• US Class Current: 361/283.4
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: Y10T 29/43 Electric condenser making

Abstract

A small and highly sensitive capacitance type pressure sensor is obtained by filling an alkali halide material such as KBr into a through-hole, forming a conductive thin film on the surface, and dissolving and removing the alkali halide material. An insulating plate disposed with a through-hole in the thickness direction is filled with a molten alkali halide material such as KBr. After forming a conductive thin film on the surface of the alkali halide material filled into the through-hole and the vicinity thereof, the alkali halide material is dissolved by water and removed. In this way, a diaphragm is made of the through-hole and the conductive thin film. A curve of the diaphragm caused by a pressure difference between the both faces of the conductive thin film is detected as a capacitance change between the conductive thin film and the electrode layer.

Claims

1. A capacitance sensor comprising an insulating plate having a through-hole in the thickness direction, a conductive thin film disposed on a top surface of the insulating plate covering the through-hole, an electrode layer disposed on a bottom surface of the insulating plate covering at least the through-hole, and a base material which holds the insulating plate together with the electrode layer, wherein said conductive thin film has a thickness of 10 nm or more and 5 μ

m or less.

2. The capacitance sensor as in claim 1, wherein said electrode layer is formed on a top surface of the base material, and that said electrode layer is adhered mechanically to a bottom surface of the insulating plate.

3. The capacitance sensor as in claim 1, wherein said electrode layer is formed on a top surface of the base material, and that said electrode layer is adhered to a bottom surface of the insulating plate by an adhesive.

4. The capacitance sensor as in claim 1, wherein said capacitance sensor comprises a capacitance pressure sensor.

5. The capacitance sensor as in claim 1, wherein said capacitance sensor comprises a capacitance acceleration sensor formed by disposing a dead weight on a top surface of the conductive thin film on the side opposite the through-hole.