Optical: systems and elements – Polarization without modulation – Polarizarion by dichroism
Reexamination Certificate
1996-07-24
2001-05-08
Schuberg, Darren (Department: 2872)
Optical: systems and elements
Polarization without modulation
Polarizarion by dichroism
C359S490020, C349S096000
Reexamination Certificate
active
06229646
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plate-like polarizing element, a polarizing conversion unit provided with the element, and a projector provided with the unit.
2. Related Background Art
As an apparatus for converting non-polarized light having a random plane of polarization into polarized light, an apparatus described in Japanese Laid-Open Patent Application No. 61-90584 is shown in
FIG. 1
of the accompanying drawings.
In this projector, non-polarized parallel light emerging from a condenser lens
104
enters a polarizing beam splitter
111
, and P-polarized light L
P
is intactly transmitted through the acting surface (evaporated film formed on an inclined surface on which two rectangular prisms are adhesively secured to each other)
111
a
of the polarizing beam splitter
111
, while S-polarized light L
S
is upwardly reflected at a right angle and enters a total reflection prism
112
. The S-polarized light L
S
is rightwardly reflected at a right angle by the total reflection prism
112
, whereby it emerges from the total reflection prism
112
in the same direction as the P-polarized light L
P
transmitted through the polarizing beam splitter
111
. The S-polarized light L
S
refers to rectilinearly polarized light having a plane of polarization parallel to the acting surface
111
a
of the polarizing beam splitter
111
, and the P-polarized light L
P
refers to rectilinearly polarized light having a plane of polarization orthogonal to the S-polarized light L
S
. A half wavelength plate
113
is disposed on the emergence side of the total reflection prism
112
, and the S-polarized light L
S
which has emerged from the total reflection prism
112
is transmitted through the half wavelength plate
113
, whereby the plane of polarization thereof is rotated by 90° and the S-polarized light L
S
is converted into P-polarized light L
P
*. Also, wedge type lenses
114
and
115
for changing optical path are disposed on the emergence sides of the polarizing beam splitter
111
and the half wavelength plate
113
, respectively, and the P-polarized light L
P
transmitted through the polarizing beam splitter
111
and the P-polarized light L
P
* converted by the half wavelength plate
113
have their optical paths changed, and intersect each other at a point P
O
on the incidence side surface of a liquid crystal light bulb
117
and become combined light.
Accordingly, in this projector, the liquid crystal light bulb
117
can be illuminated by both of the S-polarized light L
S
and the P-polarized light L
P
separated by the polarizing beam splitter
111
. However, the above-described projector of Japanese Laid-Open Patent Application No. 61-90584 requires the large polarizing beam splitter
111
and total reflection prism
112
, and this leads to the disadvantage that the entire apparatus becomes bulky and heavy.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a plate-like polarizing element which can cause non-polarized light emitted from a light source to enter an image generator without any loss and can contribute to the compactness of a projector, a projector, a polarizing conversion unit provided with the element, and a projector provided with the unit.
The plate-like polarizing element of the present invention comprises a plurality of units each having a dividing portion for dividing incident light into reflected light and transmitted light whose planes of polarization are orthogonal to each other, a reflecting portion for reflecting one of said reflected light and said transmitted light and directing it substantially in the same direction as the direction of travel of the other, and a modulating portion for varying the plane of polarization of at least one of said reflected light and said transmitted light to thereby make the planes of polarization of the two coincident with each other, said units being juxtaposed.
The polarizing conversion unit of the present invention has the plate-like polarizing element of the present invention, and conversion means provided on the incidence side of the plate-like polarizing element for converting non-polarized light into non-polarized light of a fence-like pattern or converting non-polarized light into non-polarized light of a lattice-like pattern.
The projector of the present invention is such that the illuminating optical system thereof has the polarizing conversion unit of the present invention, or the image generator thereof has three generators for generating red, green and blue images, respectively, and the illuminating optical system has a color resolving system for resolving non-polarized light into red, green and blue non-polarized lights, and the polarizing conversion unit of the present invention provided in the optical path of the non-polarized light of each color.
Or the image generator has three generators for generating red, green and blue images, respectively, and the illuminating optical system has a color resolving system for resolving non-polarized light into red, green and blue non-polarized lights, and the polarizing conversion units of the present invention provided in the common optical path of two of non-polarized lights of three colors and the optical path of non-polarized light of the other color, respectively.
REFERENCES:
patent: 2748659 (1956-06-01), Geffeken et al.
patent: 2810324 (1957-10-01), Marks
patent: 4560999 (1985-12-01), Tokuhara
patent: 4850685 (1989-07-01), Kamakura et al.
patent: 4864390 (1989-09-01), McKechnie et al.
patent: 4989076 (1991-01-01), Owada et al.
patent: 5098184 (1992-03-01), van den Brandt
patent: 5264897 (1993-11-01), Shikama
patent: C935663 (1956-01-01), None
patent: 1372436 (1964-08-01), None
patent: 61-90584 (1986-05-01), None
patent: 61-102893 (1986-05-01), None
patent: 63-182987 (1988-07-01), None
patent: 3-114027 (1991-05-01), None
European Patent Office: Patent Abstracts of Japan, Publication #: JP62059919, Date: Mar. 16, 1987.
Kawasaki Shigeru
Kimura Kazumi
Mitsutake Hideaki
Mochizuki Noritaka
Shingaki Junko
Canon Kabushiki Kaisha
Morgan & Fineggan LLP
Schuberg Darren
LandOfFree
Plate-like polarizing element, a polarizing conversion unit... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Plate-like polarizing element, a polarizing conversion unit..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plate-like polarizing element, a polarizing conversion unit... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2526733