Patent ID: 7683857

Claim:
An illuminator used to illuminate a light modulation device of a projection display device, comprising: a light source; a light control device that adjusts an amount of a light flux of the light source on the basis of image information and usage information, the light control device including a light flux setting device that sets the amount of light flux of the light source on the basis of image information and a dimming-range setting device that sets a dimming range in which dimming is allowed on the basis of the usage information; and an image-signal expanding device that expands an image signal on the basis of a dimming amount of the light source, wherein the light control device adjusts the amount of light flux of the light source on the basis of the amount of light flux set by the light flux setting device within the dimming range, and the light flux setting device temporarily sets a temporary amount of the light flux, when a dimming amount of the temporary amount of the light flux is within the dimming range, the image-signal expanding device expands the image signal by an expansion coefficient that is a reciprocal of the temporary amount of light flux, whereas when the dimming amount of the temporary amount of light flux is out of the dimming range, the image-signal expanding device expands the image signal by an expansion amount larger than the reciprocal.