Backscatter-type visibility detection
US5663710A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 18, 1995 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Jul 18, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A90/10
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved visibility detector and method emit infrared radiation away from an infrared emitter; detect an amount of infrared radiation backscattered by an airborne visibility impeding agent; and generate a backscatter signal in response to the amount detected. In one embodiment, the detector detects an amount of the infrared radiation that is not backscattered; generates a reference signal in response thereto; determines an actual amount of the infrared radiation backscattered; determines whether the actual amount exceeds a prescribed threshold; and generates an alarm signal in event the actual amount is determined to exceed the prescribed threshold. In other embodiments, the device employs a meniscus barrier between the emitter and the detector; another, lower, threshold in determining when to terminate the alarm signal; a second alarm signal to indicate that backscatter has increased above another, higher, threshold; a calibration scheme for calibrating the detector and/or a running average to avoid anomalous indications of low/high visibility.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.