Patent ID: 8496332

Claim:
An illumination system adapted to illuminate a light valve of a projection apparatus, the illumination system comprising: a light source module, wherein the light source module emits a light beam during an on-state of the light source module and does not emit the light beam during an off-state of the light source module; a light color modulating module comprising a plurality of light color modulating units and disposed in a transmission path of the light beam, wherein any two adjacent light color modulating units are capable of modulating the color of the light beam into two different colors, and the light color modulating module is capable of moving so that the light color modulating units are moved into an illumination region of the light beam in sequence; and a control unit electrically connected to the light source module and the light color modulating module, wherein the control unit determines a relative position of the light color modulating module with respect to the light beam based on a signal sent from the light color modulating module, the control unit switches the light source module to the off-state when the control unit determines that a boundary of any two adjacent light color modulating units has moved into the illumination region of the light beam, and the control unit switches the light source module to the on-state when the control unit determines that the boundary of any two adjacent light color modulating units has moved away from the illumination region of the light beam, wherein a response time of the light source module switching from the on-state to the off-state, added to a response time of the light source module switching from the off-state to the on-state, is less than a time passed while the boundary of any two adjacent light color modulating units moved into and then away from the illumination region of the light beam.