Ambient light filter for infrared linked stereoscopic glasses
US5325192A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 24, 1992 |
| Grant date | Jun 28, 1994 |
| Priority date | — |
| Expiry date | Jul 24, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N13/341
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A stereoscopic imaging system (10) includes a display (14) and stereoscopic glasses (18) having right-and left-eye pieces (20 and 22). A photodetector (28) in the glasses receives electromagnetic radiation including IR pulses, having fast rise times, from a transmitter (26), and noise from ambient light and other electromagnetic radiation. An ambient light filter (34) filters out low frequency and low amplitude noise created by ambient light and other electromagnetic signals. The ambient light filter employs a high pass filter cancellation loop (42) that cancels low frequency components, a high frequency amplifier (50) that provides unity gain to low frequency components, and a high pass filter (C3 and R9). The ambient light filter also employs a threshold adjusting circuit (64) that temporarily adjusts the threshold voltage of a comparator (60) in response to reception of the IR pulses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.