Patent ID: 8125426

Claim:
An image displaying apparatus that spatially modulates light emitted from a light source based on information about an image to be displayed and projects out the modulated light onto a screen, the image displaying apparatus comprising: a detecting unit that detects a variation in the light quantity in a light path between the light source and the screen; and a controlling unit that controls a quantity of the light to be propagated to the screen, wherein the detecting unit includes a first detecting unit, positioned at a first location in the light path, that detects a quantity of the light propagating through the light path and outputs detected light quantity as a first quantity; a second detecting unit, positioned at a second location in the light path, that detects a quantity of the light propagating through the light path and outputs detected light quantity as a second quantity, the second location being closer to the screen than the first location; and a variation calculating unit that calculates the variation in the light quantity based on a difference between the first quantity and the second quantity, and wherein the control unit controls a quantity of the light if the second quantity decreases more than a predetermined value from the first quantity.