Patent ID: 8648790

Claim:
A light source driving apparatus for driving a light source, the apparatus comprising: a switching driver which outputs a first current toward the light source; and a current bypasser which bypasses at least a portion of the first current so that a second current branched from the first current flows in the light source, the at least a portion of the first current corresponding to a difference between the first current and a target value corresponding to an input voltage of the switching driver; wherein a magnitude of the at least a portion of the first current is set to make the second current reach the target value; the light source driving apparatus characterized in that: the current bypasser comprises: a resistor which is connected in series with the light source; a transistor which is connected in parallel with the series connection of the light source and resistor; a differential amplifier which detects a voltage difference across the resistor and outputs the voltage difference as a first voltage; and a transistor controller receiving the first voltage and controlling the transistor to operate in a forward active region so that the at least a portion of the first current flows in the transistor to thereby decrease a difference between the first voltage and the input voltage of the switching driver, so as to drive the second current toward the target value.