Motion-detector circuitry with adjustable background lighting level
US6225748A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 30, 1999 |
| Grant date | May 1, 2001 |
| Priority date | — |
| Expiry date | Dec 30, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/40
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circuit arrangement according to the invention is intended to be used in a PIR motion-activated lighting fixture of the type that includes a triac for energizing the light from the AC power mains and a triac firing circuit for firing the triac in response to motion. To provide the accent lighting level and to control the magnitude of that level, the circuitry includes a window comparator, in which the thresholds are set to defining a dimming window, and a filter circuit responsive to the AC power line and providing an input signal to the window comparator. The filter circuit includes a circuit arrangement for shifting the phase of the input signal with respect to the AC power line signal and for contemporaneously scaling the amplitude of the input signal with respect to the AC power line signal such that the peak amplitude of the input signal diminishes as the phase shift of the input signal increases. That is to say, the amplitude and the phase shift of input signal to the window comparator are scaled together. The magnitude of the phase shift and concomitant amplitude scaling may be set by the user. The circuitry further triggers the triac firing circuit in the absence of motio…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.