Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Reexamination Certificate
1999-11-29
2001-06-12
Ben, Loha (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
C359S619000, C359S622000, C359S627000, C359S487030, C359S640000, C353S031000, C355S053000, C349S005000, C362S268000
Reexamination Certificate
active
06246526
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a light irradiating apparatus for use when an image display element is to be uniformly illuminated, and more particularly to an image displaying apparatus such as a liquid crystal projector using such light irradiating apparatus in an illuminating system.
2. Related Background Art
In a liquid crystal projector for enlarging and projecting an image displayed on a liquid crystal display element, use has heretofore been made of an illuminating system for condensing a light emitted from a white light source in a particular direction by a reflecting mirror, and uniformly illuminating the liquid crystal image display element by a fly-eye lens integrator. In this illuminating system, as proposed in Japanese Laid-Open Patent Application No. 8-304739, etc., use is made of a polarization converting element for aligning the direction of polarization of the illuminating light in accordance with the polarization characteristic of the liquid crystal display element.
FIG. 12
of the accompanying drawings shows the illuminating system (polarization converting system) proposed by the above-mentioned publication. As shown in this figure, when two fly-eye lens
101
and
102
and a polarization converting element
103
are to be combined together, the separation of polarization is such that non-polarized illuminating light is separated into P-polarized component and S-polarized component at the condensing position of the first fly-eye lens
101
formed near the second fly-eye lens
102
. That is, only the light transmitted through the area Fa of a half of the pitch of each lens constituting the second fly-eye lens
102
is polarization-converted.
In the construction as shown in
FIG. 12
, however, there is the problem that when the parallelism of the illuminating light incident on the first fly-eye lens
101
is bad (the illuminating angle &agr; is great), the condensed spot (point image) by the first fly-eye lens
101
becomes large and therefore, the light protrudes out of the range of the area Fa and the percentage of the quantity of light which can be used for polarization conversion is reduced. When use is made of a construction as proposed, for example, in Japanese Laid-Open Patent Application No. 10-133198 wherein an elliptical mirror and a concave lens are combined and illuminating light is compressed into a narrower area, action similar to that of a teleconverter comprising positive and negative lenses is provided by the positive power of the elliptical shape and the negative power of the concave lens, and in contrast with a construction for collecting light by a parabolic mirror, conversion is effected so that the parallelism of the illuminating light emerging from the concave lens may be aggravated (the illuminating angle may increase). Therefore, even if the polarization converting element proposed in Japanese Laid-Open Patent Application No. 8-304739 is used in it, the rate of the light transmitted through the area Fa of a half of the lens pitch of the second fly-eye lens is reduced and thus, a desired increase in the quantity of light cannot be expected.
Also, even when as proposed in Japanese Laid-Open Patent Application No. 10-133141, an elliptical mirror and a concave lens are combined and a polarization converting element is provided between fly-eye lenses, an area for aligning the direction of polarization (an area through which the light of P-polarized component is transmitted and an area through which the light of S-polarized component is transmitted) is provided near the second fly-eye lens correspondingly to the area of a half of the lens pitch of the second fly-eye lens and therefore likewise, a reduction in the percentage of the polarization-converted light occurs.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-noted problems.
According to a first aspect of the invention of the application, in a light irradiating apparatus for applying light from a light source to an object to be irradiated through a polarizing element array comprising a plurality of polarizing elements arranged, a divergent light is applied to a fly-eye lens (lens array), whereby a plurality of light source images having an arrangement period greater than the arrangement period of the lenses of the fly-eye lens are formed by the fly-eye lens, and light beams forming the plurality of light source images are directed to the polarizing element array of which the arrangement period of the polarizing elements is greater than the arrangement period of the lenses of the fly-eye lens.
Also, according to a second aspect of the invention of the application, in a light irradiating apparatus for applying light from a light source to an object to be irradiated through a polarizing element array comprising a plurality of polarizing elements arranged, a divergent light is applied to a first fly-eye lens, whereby a plurality of light source images having an arrangement period greater than the arrangement period of the lenses of the first fly-eye lens are formed by the first fly-eye lens, and light beams forming the plurality of light source images are directed to the polarizing element array of which the arrangement period of the polarizing elements is greater than the arrangement period of the lenses of the first fly-eye lens through a second fly-eye lens of which the arrangement period of the lenses is greater than the arrangement period of the lenses of the first fly-eye lens.
Also, according to a third aspect of the invention of the application, in a light apparatus for applying light from a light source to an object to be irradiated through a polarizing element array comprising a plurality of polarizing elements arranged, divergent light is applied to a first fly-eye lens, whereby a plurality of light source images of which the arrangement period is greater than the arrangement period of the lenses of the first fly-eye lens are formed by the first fly-eye lens, and light beams forming the plurality of light source images are converted into parallel lights, for example, by a collimator lens, and thereafter is directed to the polarizing element array of which the arrangement period of the polarizing elements is greater than the arrangement period of the lenses of the first fly-eye lens.
In the third aspect of the invention, provision may be made of a second fly-eye lens for receiving the light from the polarizing element array and of which the arrangement period of the lenses is greater than the arrangement period of the lenses of the first fly-eye lens.
Also, according to a fourth aspect of the invention of the application, in a light irradiating apparatus for applying light from a light source to an object to be irradiated through a polarizing element array comprising a plurality of polarizing elements arranged, a divergent light is applied to a first fly-eye lens, whereby a plurality of light source images of which the arrangement period is greater than the arrangement period of the lenses of the first fly-eye lens are formed by the first fly-eye lens, and after or before light beams forming the plurality of light source images are converted into parallel lights, for example, by a collimator lens, the light beams are directed to the polarizing element array of which the arrangement period of the polarizing elements is greater than the arrangement period of the lenses of the first fly-eye lens through a second fly-eye lens of which the arrangement period of the lenses is greater than the arrangement period of the lenses of the first fly-eye lens.
In the first to fourth aspects of the invention, at least one of polarization separating film and a half wavelength plate may be provided on each polarizing element.
According to a fifth aspect of the invention of the application, there are disposed, in succession from a light source side, a first fly-eye lens and a second fly-eye lens, and a first lens having negative refractive power is disposed between to the light source and the first fly-eye lens, and a
Ben Loha
Canon Kabushiki Kaisha
Morgan & Finnegan , LLP
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