Optical: systems and elements – Polarization without modulation – Polarizarion by dichroism
Reexamination Certificate
2000-10-18
2002-02-05
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Polarization without modulation
Polarizarion by dichroism
C359S485050, C349S009000, C362S019000, C353S020000
Reexamination Certificate
active
06344927
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a polarization luminaire for uniformly illuminating a rectangular illumination area or the like with polarized light waves in which the polarization direction thereof is made to be uniform. Further, the present invention relates to a projection display for modulating polarized light, which has been emitted from this polarization luminaire, by means of a light valve and for enlarging an image and displaying the image on a screen.
2. Description of Related Art
Hitherto, a system of the optical integrator using two lens plates has been known as an optical system for uniformly illuminating a rectangular illumination area of a liquid crystal light valve or the like. The system of the optical integrator is disclosed in, for example, Japanese Patent Public Disclosure No. 3-11806/1991 Official Gazette and has already been put to practical use.
SUMMARY OF THE INVENTION
Ordinary projection displays, which use liquid crystal light valves of the type adapted to modulate polarized light, can utilize only single kind of polarized light. It is, therefore, important for obtaining a light projected image to enhance the utilization efficiency of light.
An object of the present invention is to propose a luminaire suitable for using in a projection display or the like, which uses a liquid crystal light valve of the type adapted to modulate polarized light, as an illuminating system.
More particularly, the object of the present invention is to propose a polarization luminaire that is provided with a system of the optical integrator and a polarization conversion system and can efficiently utilize polarized light and further can achieve uniform illumination. Furthermore, another object of the present invention is to propose a projection display provided with this newly proposed polarization luminaire.
A polarization luminaire of the present invention has: a light source for emitting polarized lights whose polarization directions are random; and a system of the optical integrator that is provided with a first lens plate consisting of a plurality of lenses and with a second lens plate consisting of a plurality of lenses. The polarized light radiated from the light source is projected on the entrance plane of each of the lenses of the second lens plate through the first lens plate in such a manner as to form a secondary light source image thereon. Further, an object is radiated with light emitted from the second lens plate. This polarization luminaire of the present invention further has: polarized light splitting means for splitting a light emitted from the light source into two kinds of polarized lights whose polarization directions are perpendicular to each other and whose traveling directions are apart from each other by an angle of less than 90 degrees; and polarization conversion means for causing the two kinds of polarized lights to have the same polarization direction. Moreover, this polarization luminaire of the present invention employs a configuration in which the polarized light splitting means is placed on one of an entrance side and an exit side of the first lens plate of the system of the optical integrator.
Here, note that in the case where a region illuminated with polarized light emitted from the system of the optical integrator is oblong in the same manner as a rectangle or the like, it is preferable that a splitting direction, in which two lights split by the polarized light splitting means are separated from each other, is the direction of the length of the region.
Further, it is desirable that the shape of each of the lenses composing the second lens plate of the system of the optical integrator is similar to that of each of the lenses composing the first lens plate.
An element having a structure (namely, a liquid crystal structure), in which a liquid crystal layer is sandwiched between a prism substrate and a glass substrate and an interface between the liquid crystal layer and the prism substrate is formed as a multistage surface inclined at an angle of less than 90 degrees to the optical axis of the means, may be employed as the polarized light splitting means.
A prism beam splitter, which is provided with a polarized light splitting film constituted by a dielectric multi-layer film and is adapted to split a polarized light emitted from the light source, whose polarization direction is random, into two kinds of polarized lights, whose polarization directions are perpendicular to each other, and is further adapted to emit the two kinds of polarized lights respectively in directions forming a deviation angle of less than 90 degrees, may be employed, instead of this element using a liquid crystal, as the polarized light splitting means.
The following configurations can be employed as that of the prism beam splitter.
(1) A prism beam splitter having the following configuration can be employed. This prism beam splitter has a flat quadrangular prism and a triangular prism whose inclined surface portion is joined to one of opposed side surface portions of the quadrangular prism. In a joint portion between the quadrangular prism and the triangular prism, the polarized light splitting film is formed. A reflection film for reflecting single kind of polarized lights, which is transmitted by the polarized light splitting film, in a predetermined direction is formed on the other of the opposed side surface portions of the quadrangular prism.
As the aforementioned triangular prism, a triangular prism containing liquid can be employed.
(2) A prism beam splitter having the following configuration can be employed. This prism beam splitter has a first flat quadrangular prism and a second flat quadrangular prism whose side surface portion is joined to one of opposed side surface portions of the first quadrangular prism. In a joint portion between the first and second quadrangular prisms, the polarized light splitting film is formed. A reflection film for reflecting single kind of polarized lights, which is transmitted by the polarized light splitting film, in a predetermined direction is formed on the other of the opposed side surface portions of the first quadrangular prism.
(3) A prism beam splitter having the following configuration can be employed. This prism beam splitter has a flat quadrangular prism and a plurality of triangular prisms whose inclined surface portions are joined to one of opposed side surface portions of the quadrangular prism. In a joint portion between the quadrangular prism and the triangular prisms, the polarized light splitting film is formed. A reflection film for reflecting single kind of polarized lights, which is transmitted by the polarized light splitting film, in a predetermined direction is formed on the other of the opposed side surface portions of the quadrangular prism.
As the triangular prism described hereinabove, a triangular prism containing liquid can be employed.
(4) A prism beam splitter having the following configuration can be employed. This prism beam splitter has a first triangular prism, on the inclined surface of which the polarized light splitting film is formed, and a second triangular prism, on the inclined surface of which a reflection film for reflecting single kind of polarized lights, which is transmitted by the polarized light splitting film, in a predetermined direction is formed. While the first and second triangular prisms are in a state in which the space therebetween is filled with liquid, the first and second triangular prisms are formed in such a manner as to be integral with each other.
(5) A prism beam splitter having the following configuration can be employed. This prism beam splitter has a plurality of quadrangular-prism-like prism composite elements, each of which has: a flat quadrangular prism; a first triangular prism whose inclined surface portion is joined to one of opposed side surface portions of the quadrangular prism; and a second triangular prism whose inclined surface portion is joined to the other of the opposed side surface portio
Itoh Yoshitaka
Nakamura Jun-ichi
Nakayama Tadaaki
Yoneno Kunio
Jr. John Juba
Oliff & Berridg,e PLC
Seiko Epson Corporation
Spyrou Cassandra
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