Automatic vehicle headlamp dimming control

摘要

An automatic vehicle headlamp dimming control is the type having an operator controlled first voltage divider across a power supply, a light sensitive resistance connected in electrical series with an electrically controlled variable resistance in a second voltage divider across the output of the first voltage divider, an energizing circuit adapted to energize the headlamp system from the power supply at high or low intensity in response to the output of the second voltage divider compared to a fixed reference voltage and first electric feedback means from the energizing circuit to the electrically controlled variable resistance for producing hysteresis feedback. The invention adds to this control a resistance between the output of the first voltage divider and the second divider to decouple the same, a capacitor in series with the second voltage divider and supply voltage, and second electric feedback means from the energizing circuit to the junction of the capacitor and second voltage divider for causing charging and discharging of the capacitor with switching between high and low headlamp intensity to produce a gradual change in the output of the second voltage divider counter to the hysteresis feedback. The circuit helps reduce the undesirable sensitivity effects of hysteresis feedback, photocell memory and misaligned sensors or headlamps.