Obstacle detection sensor using synchronous detection
US6693271B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 5, 2002 |
| Grant date | Feb 17, 2004 |
| Priority date | — |
| Expiry date | Aug 5, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V8/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An object detection system employs a photo-emitter and photo-detector for synchronously detecting and processing an optical signal reflected from an object in a pinch zone of a window or door opening. A photo-emitter light signal is modulated by a modulation signal having an active phase and an inactive phase. The optical detector provides an optical detector signal that is a function of the intensity of the received light. The detected light signal is synchronously detected using a switching amplifier that multiplies the reflected modulated light signal by a first gain during the active phase and by a second gain during the inactive phase. The duration of the active and inactive phases and the first and second gains are selected such that the system gain will average to zero for ambient light when integrated over a predetermined measurement period. The synchronously detected signal is subtracted from a predetermined offset voltage, and this difference is then integrated over the measurement period. The output of the integrator is then compared to a predetermined threshold value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.