Thermal imager
US4383271A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 12, 1981 |
| Grant date | May 10, 1983 |
| Priority date | — |
| Expiry date | May 12, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/23
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A thermal imager comprises a scanner (13), detector (14) with mount (14A) cooled substantially below ambient temperature, and which via a reflector (16) on the locus (15) along which an image of the detector (14) is effectively scanned provides a characteristic radiation feature to the detector (14) in superimposition with the scanned radiation from the scanner (13). The scanner (13) operates with less than 50% efficiency so that in the detector output signal the scene-derived waveform has a duration T.sub.1 <50%T, where T is the period of the detector output signal. The characteristic radiation feature gives rise to a sync signal at the detector output and is located prior to and closely adjacent the scene-derived waveform at a time interval T.sub.2 prior to the end thereof. This sync signal is detected by a recognition circuit (20) and activates a monostable forming part of a clock circuit (22) for a duration T.sub.3 such that T.sub.2 <T.sub.3 <50%T. The clock circuit (22) controls the timing of signal processing circuitry (24) and a video output device (25) connected to the output of the detector (14).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.