Electric field proximity keyboards and detection systems
US7145552B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 22, 2003 |
| Grant date | Dec 5, 2006 |
| Priority date | — |
| Expiry date | Dec 15, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K2017/9604
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The invention is related to an electric field proximity detection system suitable for use as a touch sensitive keyboard or to be used in close proximity without direct contact. In an embodiment of a circuit useful in the system, an AC signal is coupled to a single electrode functioning as an antenna radiating an electric field through a high impedance circuit. A conductive object in close proximity disturbs the field causing a voltage change across nodes of the high impedance circuit that is compared by a detector circuit that generates a DC output indicating an object is close to the electrode. In another embodiment, the circuit couples to an analog multiplexer to control a plurality of electrodes. In another embodiment, a row and column address scheme couples a plurality of electrodes and increases resolution without substantially increasing complexity. The circuits may be integrated in a semiconductor to reduce size and cost. The electric field proximity detection system extends to applications related to object detection such as remote sensing, motion detection and remote controls.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.