Patent ID: 6875976
Filing Date: 2005-04-05
Classification: B60J,G01S

Abstract:
1. A system for detecting the presence of an object in an aperture, comprising: electromagnetic wave emitting means for emitting modulated electromagnetic waves and directing the modulated electromagnetic waves from at least one edge of a frame defining the aperture; receiving means for receiving reflected electromagnetic waves; and measuring means for measuring a reference phase change between the modulated electromagnetic waves and the reflected electromagnetic waves, when it is known no object is present in the aperture and for measuring an operative phase change when an object is potentially present in the aperture at a different time than when the reference phase change is measured; the operative phase change being compared to the reference phase change to determine whether there is a difference between the operative phase change and the reference phase change, whereby a difference between the reference phase change and the operative phase change is indicative of the presence of an object in the aperture.