Capacitive transistorized signaling device
US3958239A · kind A · utility
Inventor
Key dates
| Filing date | Sep 27, 1973 |
| Grant date | May 18, 1976 |
| Priority date | — |
| Expiry date | Sep 27, 1993 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/98
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An electronic device incorporating a circuit for providing a signal with respect to an on or off mode dependent upon the degree of capacitance. The invention comprises a first and basic embodiment utilizing a signal source having a slope of a step function or specifically one having a fast rise time initiated for example by a clock element. The operative signal criteria demands that the length and slope thereof respectively have an effective amplitude and an effective frequency compatible with the circuit components. The signal source is fed to a transistor or suitable amplifier having its base connected to a capacitance sensing means. Resistors are provided for appropriate biasing, current limiting and drain functions as well as capacitors for capacitance balancing purposes. The capacitance sensing means can comprise a touch switch which when touched has its capacitance increased causing the device to function. The transistor or amplifier is connected to a load so that when a change of capacitance is sensed, the change will be registered. Other embodiments can incorporate differential amplification means and means to drive the active components with the voltage of the signal sourc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.