Patent ID: 7388560

Claim:
A power supply apparatus comprising: a common boosting circuit which boosts power supply voltage and outputs a preliminary boosted voltage which is shared for driving a light-emitting element and a liquid crystal panel; a light-emitting element drive circuit which supplies a light-emitting element drive voltage based on the preliminary boosted voltage; and a liquid crystal panel drive circuit which boosts or steps down the preliminary boosted voltage so as to supply a liquid crystal panel drive voltage, and wherein the apparatus is so configured as to switch over between a parallel connection type in which a plurality of light-emitting elements are connected in parallel and a series connection type in which a plurality of light-emitting elements are connected in series, and wherein when the parallel connection type is selected, said common boosting circuit generates a low voltage boosted preliminarily for driving the light-emitting elements connected in parallel, and said liquid crystal panel drive circuit boosts the low voltage to the liquid crystal panel drive voltage, and wherein when the series connection type is selected, said common boosting circuit generates a high voltage boosted preliminarily for driving the light-emitting elements connected in series, and said liquid crystal panel drive circuit steps down the high voltage to the liquid crystal panel drive voltage.