Patent ID: 9210756
Filing Date: 2015-12-08
Classification: H05B,Y02B

Abstract:
1. A power supply device comprising: a direct-current-output generating circuit configured to generate a direct-current output for lighting a light-emitting element; a constant-current control circuit configured to control an electric current flowing to the light-emitting element to be constant; a load control circuit configured to control one of a load voltage applied to the light-emitting element and load power input to the light-emitting element to be constant; and a control circuit configured to receive a dimming signal having an arbitrary dimming degree from a dimming circuit, subject the light-emitting element to constant current control with the constant-current control circuit in a dimming degree region shallower than a dimming degree set in advance, control the light-emitting element according to one of constant voltage control and constant power control with the load control circuit in a dimming degree region deeper than the dimming degree set in advance, and, when a dimming signal having a deepest dimming degree equivalent to extinguishing the light-emitting element is input when the light-emitting element is in a lit state, smoothly fade out an optical output of the light-emitting element from an immediately preceding dimming degree to extinguish the light-emitting element, wherein the dimming degree region deeper than the dimming degree set in advance includes at least one dimming degree where the light-emitting element is lit.