| 摘要 |
PROBLEM TO BE SOLVED: To provide an illuminating device capable of achieving long life without reducing optical output even when a usage time increases.SOLUTION: An illuminating device includes: a light-emitting element that comprises a chip, a phosphor-containing resin layer provided so as to cover the chip, and a reflection surface contacted with the phosphor-containing resin layer and reflecting light emitted from the chip, has such characteristics that the phosphor and the reflection surface deteriorate with lapse of an accumulated lighting time, and has such characteristics that a reduction rate of a light flux maintenance factor is increased and electro-optical conversion efficiency is decreased by increase in a calorific value and an operation temperature with increase in input power; a power supply part changing a power to be supplied to the light-emitting element; and a controller configured to suppress the input power to the light-emitting element initially, increase the input power over time, and when the accumulation lighting time passes a predetermined time, make the input power constant or reduce an increase rate of the input power. |
