POLARIZATION ILLUMINATION DEVICE AND PROJECTION DISPLAY DEVICE

Japanese Patent JP3757938

B2

PROBLEM TO BE SOLVED: To provide a polarization illumination device which is suitable to be utilized as an illumination device for a projection display device or the like whose temperature change is violent. SOLUTION: A polarization illumination device (400) has a light source (401), an integrator optical system (403), a polarization separation means (402) which separates the light outgoing from the light source into 2 polarized lights (S and P) whose polarization direction cross at right angles, and a polarization transforming means (446) which make the polarization direction of the two polarized lights match. The polarization separation means (402) is placed either at an entrance side or at an outgoing side of a first lens plate(441) of an integrator optical system. As a polarization separation means (402), a prism beam splitter which has a polarization separation membrane (426) consists of a thermally stabilized dielectric multilayer membrane is adopted. By matching the polarization direction of the polarized light, most of it can be used and a polarized light whose brightness is even can be outgone, so this is suitable to be used as an illumination device for a projection display device with a liquid crystal light valve.