Automobile vehicle headlight safety control system - uses photo detector to sense oncoming lights and switch from full beam to dipped beam lights by two transistors and relays

摘要

The control system for the vehicle lights has a photoelectric detector (DL) facing the front exterior of the vehicle. A received light signal is compared with a predetermined threshold, controlling the switching from the main headlights (FR) to dipped headlights, or passing lights (FC), if the signal is greater than the threshold. The comparator may comprise a first transistor (T1) with a collector and base connected across the photodetector and a second transistor (T2) base connected to the first emitter, via a variable resistance (P1). This resistance may be adjusted for a threshold of about 0.5 lux. The second transistor collector load may be a relay (R1) coil (10). When de-energised its contact (2,15) supplies a second relay (R2) coil (16) with changeover contacts (18,20,22) supplying the lights. When de-energised, the contacts are connected to the passing lights. ADVANTAGE - Avoids dazzle and accidents, by automatically changing lights from main headlights to dipped or passing lights when vehicle driver forgets that main headlights are in operation. May have rear sensor.