Optical unit and projection type projector apparatus using the same
View Patent ↗By making the beam polarization state in a cross prism having a dichroic function for an incident beam on a reflection type liquid crystal panel the same as that for a reflected ON beam, a small-sized, low cost projection type projector apparatus is provided. A Faraday rotator having a Faraday rotation angle of 45 degrees is disposed on an optical path between a PBS and a cross prism. A half-wave plate having such a polarization axis as to rotate a polarization angle of linearly polarized light by 45 or 135 degrees is disposed on an optical immediately before or behind the Faraday rotator.
1. An optical unit comprising:
a light source;
a polarization beam splitter;
a color separation and synthesis unit having a dichroic function;
reflection type liquid crystal panels;
wherein said optical unit further includes a first optical element in an optical path between said beam splitter and said color separation and synthesis unit for rotating polarization direction of light flux to a first predetermined angle toward traveling direction of the light; and
a second optical element for rotating said polarization direction of said light flux to a second predetermined angle independent of said traveling direction of the light.
2. An optical unit according to claim 1 ;
wherein said second optical element comprises a Faraday rotator and said color separation and synthesis unit comprises a cross dichroic prism.
3. An optical unit according to claim 1 ;
wherein said first optical element comprises a polarization direction rotating optical element having a function equivalent to a half-wave plate or quarter-wave plates, and said second optical element is a Faraday rotator.
4. An optical unit according to claim 1 ;
wherein said first optical element is disposed in an optical path between said second optical element and said color separation synthesis unit.
5. An optical unit according to claim 1 ;
wherein said second optical element is disposed in an optical path between said first optical element and said color separation synthesis unit.
6. An optical unit according to claim 1 ;
wherein said first and second predetermined angle are substantially the same angle.
7. An optical unit according to claim 6 ;
wherein said first and second predetermined angle is substantially 45 degrees or 135 degrees.
8. A projection type display apparatus comprising:
alight source;
a polarization beam splitter;
a color separation and synthesis unit having a dichroic function;
reflection type liquid crystal panels;
a first optical element in an optical path between said beam splitter and said color separation and synthesis unit for rotating polarization direction of light flux to a first predetermined angle toward traveling direction of the light;
a second optical element for rotating said polarization direction of said light flux to a second predetermined angle independent of said traveling direction of the light;
a drive circuit for driving said reflection type liquid crystal panel in accordance with an image signal; and
a projection lens for extending projecting optical image from said reflection type liquid crystal panel inputted through said polarizing beam splitter.
9. An optical unit according to claim 8 ;
wherein said first optical element comprises a polarization direction rotating optical element having a function equivalent to a half-wave plate or quarter-wave plates, and said second optical element is a Faraday rotator.
10. An optical unit according to claim 8 ;
wherein said first and second predetermined angle are substantially the same angle.
11. An optical unit according to claim 6 ;
wherein said first and second predetermined angle is substantially 45 degrees or 135 degrees.