Optical: systems and elements – Extended spacing structure for optical elements – Extension of tubular element adjustable
Patent
1997-02-06
2000-11-14
Spyrou, Cassandra
Optical: systems and elements
Extended spacing structure for optical elements
Extension of tubular element adjustable
359494, 359495, 359496, 349 5, 349 9, 349194, 353 20, G02B 530
Patent
active
061478024
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
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.
BACKGROUND 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.
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.
DISCLOSURE OF THE INVENTION
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 multi-stage surface inclined at an angle of less than
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van den Brandt et al., "New Plusfactors in an LCD-Projector", IEEE 1991, San Diego, CA, pp. 151-154.
Imai et al., "A Novel Polarization Converter for High-Brightness Liquid Crystal Light Valve Projector", Eurodisplay 1992, pp. 257-260.
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Itoh Yoshitaka
Nakamura Jun-ichi
Nakayama Tadaaki
Yoneno Kunio
Jr. John Juba
Seiko Epson Corporation
Spyrou Cassandra
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