SEMICONDUCTOR LIGHT SOURCE DRIVING APPARATUS AND PROJECTION VIDEO DISPLAY APPARATUS

摘要

Prior to a rising timing of a switching signal, a second FET is turned ON for a predetermined period according to a voltage switching signal. This allows a sum of a supply voltage of a first switching power source and a supply voltage of a second switching power source to be applied to a series circuit of a semiconductor light source, a drain-source of a first FET, and a current detecting resistor for a predetermined period before and after the rising timing of the switching signal.

主权项

1. A semiconductor light source driving apparatus for driving a semiconductor light source, the apparatus comprising:
a current regulating circuit connected in series to the semiconductor light source; a first direct current power source that outputs a direct current voltage; a second direct current power source that is connected to the first direct current power source, and outputs a direct current voltage; a supply voltage selector that switches between a first supply voltage and a second supply voltage based on a voltage switching signal to selectively output one of the first and second supply voltages to a series circuit of the semiconductor light source and the current regulating circuit, the first supply voltage being a voltage obtained from an output of the first direct current power source, and the second supply voltage being a voltage obtained from a series circuit of the first direct current power source and the second direct current power source; a detector that detects a voltage at a connecting point of the semiconductor light source and the current regulating circuit; and a controller that controls the first supply voltage of the first direct current power source based on the voltage detected by the detector, and controls to increase or decrease a current value of the current regulating circuit based on a switching signal, wherein, prior to a timing at which the current value of the current regulating circuit is increased according to the switching signal, the supply voltage selector is switched according to the voltage switching signal to output the second supply voltage for a predetermined period.