Patent ID: 8794765

Claim:
A projection apparatus comprising: a plurality of different types of semiconductor light emitting elements with different light emission wavelengths; an input unit configured to receive an input of an image signal; an optical image formation unit which forms an optical image according to the image signal input via the input unit using source light emitted by the semiconductor light emitting elements; a projection unit which projects the optical image formed by the optical image formation unit toward a projection target; a temperature detection unit which detects a temperature of each type of the semiconductor light emitting elements during light emission; a measurement unit which measures an intensity of light from each type of the semiconductor light emitting elements during light emission; and a light emission control unit configured (a) to correct a measurement result from the measurement unit using a detection result from the temperature detection unit and (b) to control the light emission intensity for each of the semiconductor light emitting elements based on the corrected measurement result; wherein the measurement unit measures the intensity of the light using reflected light that is not reflected toward the projection unit by the optical image formation unit; and wherein the optical image formation unit (a) uses (i) a period during which a single type of the semiconductor light emitting elements emit light and (ii) a period during which a plurality of different types of the semiconductor light emitting elements simultaneously emit light, and (b) in the measurement by the measurement unit, (i) forms an entirely black optical image during the period in which the single type of the semiconductor light emitting elements emit light and (ii) forms an optical image according to the image signal input by the input unit during the period in which the plurality of different types of the semiconductor light emitting elements simultaneously emit light.