Patent ID: 7359026
Filing Date: 2008-04-15
Classification: G09G

Abstract:
1. A liquid crystal projector having controllable brightness adapted for use in an MRI environment, comprising: first, second and third liquid crystal panels having a stabilized image thereon wherein an image is completely written to each said panel; an individual generated red light source emitting at a stable color temperature, an individual generated green light source emitting at a stable color temperature, and an individual generated blue light source emitting at a stable color temperature, wherein said red light source causes a red beam to be directed to said first liquid crystal panel to produce a red image display, said green light source causes a green beam to be directed to said second liquid crystal panel to produce a green image display, and said blue light source causes a blue beam to be directed to said third liquid crystal panel to produce a blue image display; a dichroic prism for superimposing said red, green and blue image displays; a projection lens for projecting a full-color image beam formed by said dichroic prism; a pulse modulating means coupled to each of said individual generated red light source, green light source, and blue light source, said pulse modulating means operable to independently switch each of said light sources between an on state and an off state at a selectable repetition rate, said stabilized image being a visible image in said on state; and processor means coupled to said pulse modulating means, wherein said processor means is operable to control said selectable repetition rates whereby the relative brightness of each of said red, green and blue light sources can be independently and selectively varied while maintaining said stable color temperature, as well as enable and disable the pulse width modulators; whereby said projection lens transmits said stabilized image visually as said full color image precisely and immediately at said selectable repetition rate of said on state.