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US 2004/0174595 A1Published application
Illumination optical system and projection display optical system
AssigneeCanon Kabushiki Kaisha
InventorJun Koide
Life of this patent
Estimating the term…
Abstract
An illumination optical system is disclosed, which provides a luminous flux with a small incident angle on an illumination surface in one axis direction on a section of the luminous flux. The illumination optical system can suppress a reduction in light amount by a mask provided for a polarization conversion element. The illumination optical system has a light source and an optical integrator. The optical integrator uses a lens array to perform splitting of a luminous flux from the light source. The illumination optical system has the polarization conversion element including a polarization beam splitter array, a plurality of ½ wave plates, and a mask. The light source is a discharge gas exciting arc tube of a DC drive type.
Claims14
An illumination optical system comprising:
- a light source;
- an optical integrator which uses a lens array to perform splitting of a luminous flux incident as a generally collimated luminous flux from the light source in a first axis direction in a two-dimensional section orthogonal to a traveling direction of the luminous flux;
- and
- a polarization conversion element which includes a polarization beam splitter array, a plurality of ½ wave plates, and a mask, the polarization beam splitter array having a plurality of polarization beam splitters arranged in multiple stages corresponding to a plurality of predetermined lens areas in the lens array, each of the ½ wave plates rotating a polarization direction of first polarized light substantially 90 degrees out of the first and second polarized light with polarization directions orthogonal to each other split by each of the polarization beam splitters, and the mask covering a plurality of areas out of incident surfaces of the polarization beam splitter array to prevent incident of the second polarized light on each of the ½ wave plates,
- wherein the light source is a discharge gas exciting arc tube of a DC drive type.
2 more elements
A projection display apparatus comprising:
- a light source which is a discharge gas exciting arc tube of a DC drive type;
- an optical integrator which uses a lens array to perform splitting of a luminous flux incident as a generally collimated luminous flux from the light source in a first axis direction in a two-dimensional section orthogonal to a traveling direction of the luminous flux;
- a polarization conversion element which includes a polarization beam splitter array, a plurality of ½ wave plates, and a mask, the polarization beam splitter array having a plurality of polarization beam splitters arranged in multiple stages corresponding to a plurality of predetermined lens areas in the lens array, each of the ½ wave plates rotating a polarization direction of first polarized light substantially 90 degrees out of the first and second polarized light with polarization directions orthogonal to each other split by each of the polarization beam splitters, and the mask covering a plurality of areas out of an incident surface of the polarization beam splitter array to prevent incident of the second polarized light on each of the ½ wave plates;
- a spatial light modulator which modulates a luminous flux emerging from the illumination optical system by a group of pixels arranged two-dimensionally;
- and
- a projection lens which projects the luminous flux modulated by the spatial light modulator onto a projection surface.
3 more elements
An illumination optical system comprising:
- a light source in which a cathode electrode and an anode electrode are provided, and by applying a DC voltage a discharge gas is excited and light is emitted from the vicinity of the cathode electrode;
- a lens array in which a plurality of lenses are arranged in a first direction substantially orthogonal to an illumination direction, each lens condensing a part of a luminous flux from the light source in the first direction;
- and
- a mask in which light-transmitting portions transmitting luminous fluxes condensed by the lenses and light-blocking portions blocking the luminous fluxes condensed by the lenses are arranged alternately in the first direction.
1 more element
A projection display apparatus comprising:
- a light source in which a cathode electrode and an anode electrode are provided, and by applying a DC voltage a discharge gas is excited and light is emitted from the vicinity of the cathode electrode;
- a lens array in which a plurality of lenses are arranged in a first direction substantially orthogonal to an illumination direction, each lens condensing a part of a luminous flux from the light source in the first direction;
- a mask in which light-transmitting portions transmitting luminous fluxes condensed by the lenses and light-blocking portions blocking the luminous fluxes condensed by the lenses are arranged alternately in the first direction;
- a polarization beam splitter array in which first polarization beam splitters and second polarization beam splitters are arranged alternately in the first direction, each first polarization beam splitter reflecting a first polarized light out of transmitted light through the light-transmitting portion and transmitting a second polarized light out of the transmitted light, the polarization direction of the second polarized light being rotated by substantially 90 degrees from the polarization direction of the first polarized light, each second polarization beam splitter reflecting the first polarized light reflected by the first polarization beam splitter in a direction substantially parallel to the transmitting direction of the second polarized light;
- wave plates which rotate the polarization direction of the first polarized light from the second polarization beam splitters substantially 90 degrees;
- a light modulator which modulates the second polarized light at a substantial rectangular area having a short side in the first direction;
- and
- a projection optical system which projects modulated light by the light modulator.
5 more elements
Dependencies are inferred from the claim text.