Electrostatic capacitor type sensing device

• US 4,943,889 A
• Filed: 08/18/1989
• Issued: 07/24/1990
• Est. Priority Date: 07/03/1989
• Status: Expired due to Term

• Current Assignee: Naoyuki Ohmatoi
• Original Assignee: Naoyuki Ohmatoi
• Inventors: Ohmatoi, Naoyuki
• Primary Examiner(s): Griffin, Donald A.
• Application Number:
  US07/396,248
• Time in Patent Office: 340 Days
• Field of Search: 361/280, 361/284
• US Class Current: 361/284
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01D 5/2405 by varying dielectric
• CPC Class Codes: G01F 23/263 by measuring variations in capacitance of capacitors
• CPC Class Codes: G01F 23/268 mounting arrangements of probes

Abstract

An electrostatic capacitance type detecting device which includes a first electrode placed in the proximity of an object to be measured, a second electrode placed in the proximity of the first electrode, a film like dielectric member interposed between the first and the second electrodes, a first resistor one end of which is connected to one end of the first electrode, a second resistor one end of which is connected to one end of the second electrode, an a. c. signal generator connected to the other ends of the first and the second resistors and to the ground and a phase difference detecting means connected to the first and the second electrodes.

Claims

1. An electrostatic capacitance type sensing device comprising:

a first electrode to be placed in the proximity of an object to be measured;

a second electrode placed in the proximity of said first electrode;

a film like dielectric spacer means interposed between said first and said second electrodes;

a first resistor, one end of which is connected to one end of said first electrode;

a second resistor, one end of which is connected to one end of said second electrode;

an a.c. signal generator connected to the other ends of said first and the second resistors and to the ground; and

a phase difference detecting means connected to said first and the second electrodes.

2. An electrostatic capacitance type sensing device as claimed in claim 1, wherein said film like dielectric means interposed between said first and second electrodes is made of glass cloth, epoxy substrate, Teflon or polyimide.

3. An electrostatic capacitance type sensing device as claimed in claim 1, wherein the thickness of said film like dielectric means is equal to or less than 2 mm.

4. An electrostatic capacitance type sensing device as claimed in claim 1, wherein the thickness of said film like dielectric means is in the order of 50μ

to 100μ

.

5. An electrostatic capacitance type sensing device as claimed in claim 1, wherein each of said first and said second electrodes is copper foil adhered closely to said film like dielectric means.

6. An electrostatic capacitance type sensing device as claimed in claim 1, wherein each of said first and said second electrodes and said film like dielectric means are fixed by a supporting means at the peripheral portions thereof to a hollow cylindrical casing and further said first electrode is arranged in the proximity of one end of said casing.