Apparatus and circuit for use with capacitive presence detection systems
US7193522B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 2, 2001 |
| Grant date | Mar 20, 2007 |
| Priority date | — |
| Expiry date | Nov 3, 2022 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE05Y2400/822
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A capacitance presence sensing apparatus (10) having a fail-safe circuit (13) and modular units (100). The fail-safe circuit (13) includes delivering a low voltage (FIG. 5) to a sensor and connecting voltage through a resistor to an oscillator (18). An opener ground in the circuit changes frequency of the oscillator (18) to indicate a problem With the fail-safe circuit (13). The apparatus also contains a number of inductance coils (28) which may be selected to tune the frequency of the system. Circuitry is provided in cards which may be combined together with receiver transmitter cards (106) and to easily facilitate the use of the system for desired applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.