Solid state capacitive switch
US5973623A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1997 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Oct 21, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/962
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A fingertip-operated solid state capacitance switch detects a capacity change that is induced by the physical contact of an ungrounded fingertip to an external dielectric surface of the solid state switch. The input and output of a solid state signal-inverting amplifier are respectively connected to two relatively large and ungrounded capacitor plates that are associated with, but electrically isolated from, the switch's external dielectric surface. An ungrounded fingertip forms a third capacitor plate on the switch's external surface. The solid state amplifier detects the presence of a fingertip on the switch's external surface by way of a change in capacitance within a compound, three plate, capacitor that includes the two ungrounded capacitor plates and the ungrounded fingertip that is resident on the switch's external surface. An automatic gain control circuit is provided to adjust the value of an amplifier reference voltage when the solid state switch is not operating, thereby allowing the solid state switch to adapt to changeable ambient conditions. A momentary switch and a toggle flip-flop latched switch are provided. A linear switch array having a movable control knob and a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.