Patent ID: 7142302

Claim:
A method for determining a target spectrum for a light source to be used in a projection system in which light from the light source is: 1) split into sub-portions either spatially or in time, 2) the sub-portions are filtered through red, green, and blue filters, and 3) the filtered sub-portions are recombined as a colored image on a screen said method comprising: A) specifying desired color coordinates for red light, green light, and blue light; B) specifying desired color coordinates for white light produced by way of steps 1 to 3; C) specifying a set of filter characteristics for the red, green, and blue filters; and D) determining either i) a target spectrum for the light source or ii) a combination of a target spectrum for the light source and a revised set of filter characteristics for the red, green, and blue filters based on a combination of criteria which includes: a) reducing differences between calculated color coordinates for filtered red light, filtered green light and filtered blue light formed in step 2 and the specified desired color coordinates for those lights; b) reducing differences between calculated color coordinates for recombined white light formed in step 3 and the specified desired color coordinates for that light; and c) increasing calculated light transmission efficiency for the process of step 1 to 3.