Patent ID: 9618833
Date: 2017-04-11
CPC Classifications: G02B,G03B,H04N

Claim:
1. An image projection apparatus, comprising: a light source; a projector to project light from the light source; a dust-proof member to protect the projector from outside dust while transmitting the light from the light source through the dust-proof member; a light detector provided at an end surface of the dust-proof member to detect reflected light of light projected from the projector, the reflected light being internally reflected light trapped within the dust-proof member; and a controller that executes a protective action when the amount of internally reflected light detected by the light detector meets or exceeds a predetermined threshold value, wherein the controller changes the predetermined threshold value based on at least one of (1) a length of a one-time continuous use of the light source and (2) a power level being used by the light source.