Integral ambient light and occupancy sensor having a linear array of

Abstract

A sensor implemented with a single light sensing device detects ambient light levels and object motion. The sensor comprises an optical component assembly composed of a linear array of light sensitive elements, preferably photodiodes, positioned downstream of a segmented slit aperture device comprising a single, segmented slit, the slit length of which is oriented perpendicular to the length of the linear array. The individual photodiodes of the array provide motion detection capability in a direction perpendicular to the slit length. The slit aperture is segmented along the slit length to form multiple zones of sensor light responsivity that provide motion detection capability in a direction parallel to the slit length. An object moving in a direction parallel to the multiple slit aperture passes through one or more zones of sensor responsivity and thereby produces from the photodiodes a varying electrical signal from which object motion can be detected. A processor in a first mode detects an ambient light level and in a second mode detects object motion. In the first mode, the processor determines the average amount of light received by the entire photodiode array by computing an average of light signal data values derived from the photodiodes in response to the quantities of light they receive during an exposure time. In the second mode, the processor compares light signal data values acquired at different times for corresponding photodiodes to detect differences in light intensities of adjacent zones of sensor responsivity to detect object motion. The processor is capable of concurrently performing the first and second modes.