Photoelectric switch

摘要

PCT No. PCT/GB93/02403 Sec. 371 Date May 22, 1995 Sec. 102(e) Date May 22, 1995 PCT Filed Nov. 23, 1993 PCT Pub. No. WO94/13063 PCT Pub. Date Jun. 9, 1994A novel semiconductor switching device for use in high voltage applications (typically ranging from 5 kV up to about 50 kV) makes use of the well-known effect of reverse conduction in silicon diodes when exposed to light. Hitherto, photodiodes have been commercial available for relatively low voltage applications. The device disclosed herein is implemented by a high voltage diode having a series of semiconductor junctions and a light emitting diode operable to irradiate the junctions to render the high voltage diode conducting in the reverse bias direction. The switching device finds application in electrostatic spraying devices where the current demands are relatively small, eg up to about 2 mu A.