Patent ID: 6046856
Filing Date: 2000-04-04
Classification: H04N

Abstract:
An illumination device used for an image projector, the illumination device having a light source for generating an indefinitely polarized light beam, polarization separation means for separating the indefinitely polarized light beam into two differently and linearly polarized light beams of which polarized planes are perpendicular to each other, a 1/2.lambda. wave-plate for equalizing one of the polarized planes of the two differently and linearly polarized light beams to another polarized plane thereof, optical path alterring means for alterring a direction of principal ray of one of the two differently and linearly polarized light beams; and a superimposing lens for superimposing two equally and linearly polarized light beams obtained from the two differently and linearly polarized light beams, the illumination device comprising:a first microlens array provided between the light source and the polarization separation means, the first microlens array being composed of a plurality of microlens units;a second microlens array provided in a first optical path of one of the two equally and linearly polarized light beams between the polarization separation means and the superimposing lens, the second microlens array being composed of a plurality of microlens units;a third microlens array provided in a second optical path of another of the two equally and linearly polarized light beams between the polarization separation means and the superimposing lens, the third microlens array being composed of a plurality of microlens units, wherein the second microlens array in the first optical path and the third microlens array in the second optical path are placed to have an approximately same optical distance referred to a position of the first microlens array; andmeans for aligning principal rays of the two equally and linearly polarized light beams to be parallel to each other.