Patent ID: 6225748
Filing Date: 2001-05-01
Classification: H05B,Y02B

Abstract:
In a circuit arrangement for use in a PIR motion-activated light, said circuit arrangement including a PIR motion detector for energizing said light at a nominal full-brightness illumination level in response to motion and further including a dimming circuit for energizing said light at an intermediate background illumination level in the absence of motion, the improvement comprising:circuit means, including a continuously variable circuit element adjustable by an end user, for adjusting said intermediate background illumination level, whereby the end user is enabled to set a desired intermediate background illumination level from a continuous range of levels, said circuit means comprising:a window comparator defining a dimming window;a filter circuit responsive to an AC power line and providing an input signal to said window comparator,wherein said continuously variable circuit element is arranged in said filter circuit for shifting the phase of said input signal with respect to said AC power line and for contemporaneously scaling the amplitude of said input signal with respect to said AC power line wherein the peak amplitude of said input signal diminishes as the phase shift of said input signal increases,wherein said intermediate background illumination level is determined by the phase shift at which said input signal exceeds said dimming window.