Electronic proximity detector used in control of e.g. taps on wash basins - has signal processor, oscillator and printed circuit incorporating metallised shaped as parabola and antenna

摘要

The detector has a printed circuit with metallised zones on its upper surface (122) and reverse surface (150) (160) (170). The metallised zone on the upper surface (122) has an edge (124) shaped as a parabola and another metallised zone (170) on the reverse side constitutes an antenna. A transistor and three resistances are added to the printed circuit and these combine with capacitances and an inductance arising from the shape of the metallised zones to produce an oscillator. Signals from the oscillator are interpreted by a remote processor to detect an approaching object. ADVANTAGE - Detector is very reliable, compact and senses objects within one metre.