Proximity sensing based on antenna impedance variation
US7113087B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 8, 2003 |
| Grant date | Sep 26, 2006 |
| Priority date | — |
| Expiry date | Feb 17, 2025 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D10/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Proximity of a user body part can be detected by measuring the effects such proximity has on antenna impedance mismatches. The amount of mismatch affects the amount of RF signal energy reflected back into a transmission line connecting the antenna to a RF signal source. A directional coupler has a main line electrically connected to the transmission line, as well as a coupled line. The directional coupler produces a signal on its coupled line in relation to the magnitude of reflected energy on the transmission line; the amount of reflected energy varies in response to how well the antenna impedance matches the transmission line impedance. A signal detector is electrically connected to the coupled line, and responds to signals produced in the coupled line by the main line. The signal detector output is then used to determine whether a body part is in proximity. Other aspects the invention include an adaptive algorithm to adjust a threshold for proximity determination.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.