Pressure responsive potentiometer

• US 5,036,306 A
• Filed: 07/07/1989
• Issued: 07/30/1991
• Est. Priority Date: 11/20/1987
• Status: Expired due to Fees

• Current Assignee: Labino Patent AB
• Original Assignee: Labino Patent AB
• Inventors: Bergkvist, Lars A.
• Primary Examiner(s): Lateef, Marvin M.
• Application Number:
  US07/381,669
• Time in Patent Office: 753 Days
• Field of Search: 338/99, 338/114, 338/47, 252/510, 252/511, 73/862.64, 73/862.62
• US Class Current: 338/114
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: H01C 10/106 on resistive material dispersed in an elastic material H01C10/103 and H01C10/12 take precedence; for electric switches H01H1/029

Abstract

A pressure responsive potentiometer, including an elastic body which includes a silicone mass mixed with a carbon fraction in a quantity such that the electrical resistance across the body is changed when a force is applied to the body, which body has electrically conductive contact tabs or plates or like elements connected thereto in mutually spaced relationship. The invention is characterized in that the body (1) is composed of a mixture including a silicone mass, silicone oil and carbon grains, where the weight ratio of silicone mass to silicone oil is about 1:0.3 to 1:0.5, preferably about 1:0.4, and where the carbon grains have a size which is greater than a size corresponding to a 50 mesh sieve (50 meshes per inch) and a size which is smaller than the smallest dimension of the body (1).

Claims

1. A pressure responsive potentiometer including an elastic body which comprises silicone mass mixed with a carbon fraction in such quantities that the electrical resistance across the body is changed in response to a force applied to the body, and which body has electrically conductive contact elements connected thereto in mutually spaced relationship, characterized in that the body is produced from a mixture comprising silicone mass, silicone oil and carbon grains in which the weight ratio of silicone mass to silicone oil is in the range of from about 1:

0.3 to 1;

0.5, and in which each of the carbon grains has a size which is in the size range which corresponds to the sieve size range which is from a 50 mesh sieve to a 10 mesh sieve.

2. A potentiometer according to claim 1, characterized in that the weight of the carbon grains is approximately equal to or greater than the weight of the silicone mass.

3. A potentiometer according to claim 1, characterized in that each of the carbon grains has a size which is smaller than a size corresponding to a 10 mesh sieve.

4. A potentiometer according to claim 1, characterized in that each of the carbon grains has a size corresponding to a size which ranges from a 28 mesh sieve to a 20 mesh sieve.

5. A potentiometer according to claim 1, characterized in that the body is constructed to a vertical height extension during manufacture of about 5 mm to 20 mm.

6. A potentiometer according to claim 1, characterized in that the silicone oil has a viscosity in the order of 200 centistokes.

7. A potentiometer according to claim 1, characterized in that the carbon grains are graphite grains.

8. A potentiometer according to claim 1, characterized in that carbon powder, the particles of which have a size smaller than a size corresponding to a 80 mesh to a 50 mesh sieve, is admixed prior to casting the body in an amount corresponding to about 5-15% of the weight of the carbon grains.

9. A potentiometer according to claim 1, wherein said carbon grains each have a size which is greater than a size corresponding to a 50 mesh screen.

10. A potentiometer according to claim 1, wherein said weight ratio of silicone mass to silicone oil is 1:

0.4.