U.S. patent application number 09/734164 was filed with the patent office on 2001-05-31 for array lens, lighting optical system, optical unit and imaging apparatus.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Imahase, Taro, Maruyama, Takesuke, Miyoshi, Tomohiro, Ohuchi, Satoshi, Otsuka, Yasuo, Yatsu, Masahiko.
Application Number | 20010002154 09/734164 |
Document ID | / |
Family ID | 27321405 |
Filed Date | 2001-05-31 |
United States Patent
Application |
20010002154 |
Kind Code |
A1 |
Ohuchi, Satoshi ; et
al. |
May 31, 2001 |
Array lens, lighting optical system, optical unit and imaging
apparatus
Abstract
The present invention discloses the structure of the array lens
that at least any one of the diagonal size, vertical size and
lateral size of lens cell is set to almost 1/(4.5 or more) for each
corresponding size of the display elements, the structure that the
diagonal size of lens cell is set to almost 0.18 inch or less, the
structure that the total number of lens cells is set to almost 240
or more and the structure that the lens focal distance of lens cell
is set to almost 30 mm or less.
Inventors: |
Ohuchi, Satoshi;
(Kamakura-shi, JP) ; Yatsu, Masahiko;
(Fujisawa-shi, JP) ; Imahase, Taro; (Fujisawa-shi,
JP) ; Miyoshi, Tomohiro; (Fujisawa-shi, JP) ;
Otsuka, Yasuo; (Chigasaki-shi, JP) ; Maruyama,
Takesuke; (Yokohama-shi, JP) |
Correspondence
Address: |
MATTINGLY, STANGER & MALUR, P.C.
104 East Hume Avenue
Alexandria
VA
22301
US
|
Assignee: |
Hitachi, Ltd.
|
Family ID: |
27321405 |
Appl. No.: |
09/734164 |
Filed: |
December 12, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09734164 |
Dec 12, 2000 |
|
|
|
09327191 |
Jun 7, 1999 |
|
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Current U.S.
Class: |
359/621 ;
348/E9.027; 359/618; 359/619 |
Current CPC
Class: |
G02B 27/285 20130101;
H04N 9/3105 20130101; G02B 27/0961 20130101; G02B 3/005 20130101;
G02B 27/283 20130101; G02B 3/0075 20130101; G02B 3/0062 20130101;
G02B 27/0927 20130101; G02B 3/0056 20130101; H04N 9/3167 20130101;
G03B 21/208 20130101; H04N 9/3152 20130101 |
Class at
Publication: |
359/621 ;
359/619; 359/618 |
International
Class: |
G02B 027/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 8, 1998 |
JP |
10-158788 |
Jun 10, 1998 |
JP |
10-161789 |
Sep 29, 1998 |
JP |
10-275828 |
Claims
What is claimed is:
1. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light beam from
a lighting optical system, said lighting optical system comprising
an array lens in which the lens to condense the light beam from a
light source unit to form a plurality of light source images is
used and any one of the diagonal size, vertical size, lateral size
of lens cell is almost 1/(4.5 or more) for each corresponding size
of said display elements.
2. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light beam from
a lighting optical system, said lighting optical system comprising
an array lens in which a lens to condense the light beam from a
light source unit to form a plurality of light source images is
used and the diagonal size of lens cell is set to almost 0.18 inch
or less.
3. Imaging apparatus according to claim 2, wherein said light
source unit includes an electrode wire having the thickness of 0.6
mm or less in the single side of lamp electrode.
4. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising a
lens array in which a lens to condense the light from the light
source unit to form a plurality of light source images and the
total number of lens cells is set to almost 240 or more.
5. Imaging apparatus according to claim 4, wherein said light
source unit includes an electrode wire having the thickness of 0.6
mm or less in the single side of lamp electrode.
6. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens in which a lens to condense the light from the light
source unit to form a plurality of light source images and lens
focal distance of lens cell is set to almost 30 mm or less.
7. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and any one of diagonal size, vertical size, lateral
size of lens cell is set almost to 1/(4.5 or more) for each
corresponding size of said display elements and a processing
section for isolating the light from said light source unit or
array lens to the P-polarized light beam and S-polarized light beam
with an isolating means and then changing the polarizing direction
of any one of said both P- and S-polarized light beams with a
converting means, whereby the center axis of arrangement of said
isolating means is matched with the pitch in any one of vertical
and lateral arrangement directions of the lens optical axis of at
least said array lens.
8. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and the diagonal size of lens cell is set to almost
0.18 inch or less and a processing section for isolating the light
beam from said light source unit or said array lens to the
P-polarized light beam and S-polarized light beam with an isolating
means and converting the polarizing direction of any one of both
polarized light beams with a converting means, whereby the center
axis of arrangement of said isolating means is matched with the
pitch of any direction of the vertical and lateral arrangement
directions of the lens optical axis of at least said array
lens.
9. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and the total number of lens cells is set to almost
240 or more and a processing section for isolating the light from
said light source unit or said array lens to the P-polarized light
beam and S-polarized light source with an isolating means and
converting the polarizing direction of any one of said both
polarized light beams with a converting means, whereby the center
axis of arrangement of said isolating means is matched with the
pitch in any direction of the vertical and lateral arrangement
directions of lens optical axis of at least said array lens.
10. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and a lens focal distance of lens cell is set to
almost 30 mm or less and a processing section for isolating the
light from said light source unit or said array lens to the
P-polarized light beam and S-polarized light beam with an isolating
means and converting the polarizing direction of any one of both
polarized light beams with a converting means, whereby the center
axis of arrangement of said isolating means is matched with the
pitch in any arrangement direction of the vertical and lateral
directions of lens optical axis of at least said array lens.
11. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and any one of diagonal size, vertical size, lateral
size of lens cell is set to almost 1/(4.5 or more) for each
corresponding size of said display elements, an isolating section
for isolating the light from said light source unit or array lens
to the P-polarized light beam and S-polarized light beam, a light
shielding section located in the light incident side rather than
said isolating section to eliminate unwanted light beam and a
converting section for converting the polarizing direction of any
one of the P-polarized light beam and S-polarized light beam of the
light emitted from said isolating section, whereby the renter axis
of arrangement of said isolating section is matched with the pitch
in any arrangement direction of vertical and lateral directions of
lens optical axis of at least said array lens.
12. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and the diagonal size of lens cell is set to almost
0.18 inch or less, an isolating section for isolating the light
from said light source unit or array lens to the P-polarized light
beam and S-polarized light beam, a light shielding section located
in the light incident side rather than said isolating section to
eliminate unwanted light beam and a converting section for
converting the polarizing direction of any one of the P-polarized
light beam and S-polarized light beam of the light emitted from
said isolating section, whereby the center axis of arrangement of
said isolating section is matched with the pitch in any arrangement
direction of the vertical and lateral directions of the lens
optical axis of at least said array lens.
13. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and the total number of lens cells is set to almost
240 or more, an isolating section for isolating the light from said
light source unit or array lens to the P-polarized light beam and
S-polarized light beam, an light shielding section located at the
light incident side rather than said isolating section to eliminate
unwanted light beam and a converting section for converting the
polarizing direction of any one of the P-polarized light beam and
S-polarized light beam of the light emitted from said isolating
section, whereby the center axis of the arrangement of said
isolating section is matched with the pitch in any arrangement
direction of vertical and lateral directions of the lens optical
axis of at least said array lens.
14. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of optical source
images is used and a lens focal distance of lens cell is set to
almost 30 mm or less, an isolating section for isolating the light
from said light source unit or array lens to the P-polarized light
beam and S-polarized light beam, a light shielding section located
in the light incident side rather than said isolating section to
remove unwanted light beam and a converting section for converting
the polarizing direction of any one of the P-polarized light beam
and S-polarized light beam of the light emitted from said isolating
section, whereby the center axis of arrangement of said isolating
section is matched with the pitch in any arrangement direction of
the vertical and lateral directions of the lens optical axis of at
least said array lens.
15. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and at least any one of the diagonal size,
vertical size and lateral size of any one or both lens cells of
said first and second array lenses is set to almost 1/(4.5 or more)
for each corresponding size of said display elements, an isolating
section for isolating the light from said light source unit or
array lens to the P-polarized light beam and S-polarized light beam
and a converting section for converting the polarizing direction of
any one of the P-polarized light beam and S-polarized light beam of
the light emitted from said isolating section, whereby at least
said first, second array lenses, said isolating section and said
converting section are arranged in the manner that respective
optical axes thereof are almost matched with a line.
16. Imaging apparatus according to claim 15, wherein said isolating
section is a polarized beam splitter and said converting section is
a .lambda./2 phase difference plate.
17. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the diagonal size of the lens cell of any one
or both first and second array lenses is set to almost 0.18 inch or
less, a isolating section for isolating the light from said light
source unit or array lens to the P-polarized light beam and
S-polarized light beam and a converting section for converting the
polarizing direction of any P-polarized light beam and S-polarized
light beam of the light emitted from said isolating section,
whereby at least said first and second array lenses, said isolating
section and said converting section are arranged in the manner that
the respective optical axes thereof are almost matched with a
line.
18. Imaging apparatus according to claim 17, wherein said isolating
section is a polarized beam splitter and said converting section is
a .lambda./2 phase difference plate.
19. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the total number of any one or both lens
cells of said first and second array lenses is set to almost 240 or
more, an isolating section for isolating the light from said light
source unit or array lens to the P-polarized light beam and
S-polarized light beam and a converting section for converting the
polarizing direction of any one of the P-polarized light beam and
S-polarized light beam of the light emitted from said isolating
section, whereby at least said first and second array lenses, said
isolating section and said converting section are arranged in the
manner that the respective optical axes thereof are almost matched
with a line.
20. Imaging apparatus according to claim 19, wherein said isolating
section is a polarized beam splitter and said converting section is
a .lambda./2 phase difference plate.
21. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the lens focal distance of lens cell of said
first and second array lenses is set to almost 30 mm or less, an
isolating section for isolating the light from said light source
unit or array lens to the P-polarized light beam and S-polarized
light beam and a converting section for converting the polarizing
direction of any one of the P-polarized light beam and S-polarized
light beam of the light emitted from said isolating section,
whereby at least said first and second array lenses, said isolating
section and said converting section are arranged in the manner that
respective optical axes thereof are almost matched with a line.
22. Imaging apparatus according to claim 21, wherein said isolating
section is a polarized beam splitter and said converting section is
a .lambda./2 phase difference plate.
23. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and at least any one of the diagonal size,
vertical size and lateral size of any one or both lens cells of the
first and second array lenses is set to almost 1/(4.5 or more) for
each corresponding size of said display elements, an isolating
section for isolating the light from said light source unit or
array lens to the P-polarized light beam and S-polarized light beam
and a converting section for converting the polarizing direction of
any one of the P-polarized light beam and S-polarized light beam of
the light emitted from said isolating section, whereby at least
said array lens, said isolating section and said converting section
are arranged in the manner that respective optical axes thereof are
almost matched with a line and an external size of the apparatus as
a whole is set to the A4 file size or less.
24. Imaging apparatus to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the lens focal distance of lens cell of said
first and second array lenses is set to almost 30 mm or less, an
isolating section for isolating the light from said light source
unit or array lens to the P-polarized light beam and S-polarized
light beam and a converting section for converting the polarizing
direction of any one of the P-polarized light beam and S-polarized
light beam of the light emitted from said isolating section,
whereby at least said first and second array lenses, said isolating
section and said converting section are arranged in the manner that
respective optical axes thereof are almost matched with a line and
an external size of the apparatus as a whole is set to the A4 file
size or less.
25. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and at least any one of the diagonal size, vertical
size and lateral size of the lens cell is set to almost 1/(4.5 or
more) for corresponding each size of said display elements.
26. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and a plurality of lens cells having the diagonal
size of almost 0.18 inch or less are arranged within a plane.
27. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and the total number of lens cells arranged in a
plane is set to almost 240 or more.
28. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a lens to condense the light
from the light source unit to form a plurality of light source
images is used and a plurality of lens cells having the focal
distance of almost 30 mm or less are arranged in a plane.
29. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a fist array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and at least any one of the diagonal size,
vertical size and lateral size of any one or both lens cells of the
first and second array lenses is set to almost 1/(4.5 or more) for
each corresponding size of said display elements, an isolating
section for isolating the light from said light source unit or
array lens to the P-polarized light beam and S-polarized light beam
and a converting section for converting the polarizing direction of
any one of the P-polarized light beam and S-polarized light beam of
the light emitted from said isolating section, whereby at least
said first and second array lenses, said isolating section and said
converting section are arranged in the manner that respective
optical axes thereof are almost matched with a line.
30. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the diagonal size of the lens cell of any one
or both first and second array lenses is set to almost 0.18 inch or
less, a isolating section for isolating the light from said light
source unit or array lens to the P-polarized light beam and
S-polarized light beam and a converting section for converting the
polarizing direction of any P-polarized light beam and S-polarized
light beam of the light emitted from said isolating section,
whereby at least said first and second array lenses, said isolating
section and said converting section are arranged in the manner that
the respective optical axes thereof are almost matched with a
line.
31. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the total number of any one or both lens
cells of said first and second array lenses is set to almost 240 or
more, an isolating section for isolating the light from said light
source unit or array lens to the P-polarized light beam and
S-polarized light beam and a converting section for converting the
polarizing direction of any one of the P-polarized light beam and
S-polarized light beam of the light emitted from said isolating
section, whereby at least said first and second array lenses, said
isolating section and said converting section are arranged in the
manner that the respective optical axes thereof are almost matched
with a line.
32. Optical unit to form an optical image depending on a video
signal by irradiating the display elements with the light from the
lighting optical system, said lighting optical system comprising an
array lens having the structure that a first array lens to condense
the light from the light source unit to form a plurality of
secondary order light source images and a second array lens to
focus a lens image of said first array lens to said display
elements are used and the lens focal distance of lens cell of said
first and second array lenses is set to almost 30 mm or less, an
isolating section for isolating the light from said light source
unit or array lens to the P-polarized light beam and S-polarized
light beam and a converting section for converting the polarizing
direction of any one of the P-polarized light beam and S-polarized
light beam of the light emitted from said isolating section,
whereby at least said first and second array lenses, said isolating
section and said converting section are arranged in the manner that
respective optical axes thereof are almost matched with a line.
33. Lighting optical system for an imaging apparatus to form an
optical image depending on a video signal by irradiating the
display elements with the light from the light source unit,
comprising an array lens having the structure that a lens to
condense the light from said light source unit to form a plurality
of light source images is used and at least any one of the diagonal
size, vertical size and lateral size of the lens cells arranged in
a plane is set to almost 1/(4.5 or more) for corresponding each
size of said display elements.
34. Lighting optical system for an imaging apparatus to form an
optical image depending on a video signal by irradiating the
display elements with the light from the light source unit,
comprising an array lens having the structure that a lens to
condense the light from said light source unit to form a plurality
of light source images is used and a plurality of lens cells having
the diagonal size of 0.18 inch or less are arranged in a plane.
35. Lighting optical system for an imaging apparatus to form an
optical image depending on a video signal by irradiating the
display elements with the light from the light source unit,
comprising an array lens having the structure that a lens to
condense the light from said light source unit to form a plurality
of light source images is used and the lens cells in the total
number of almost 240 or more are arranged in a plane.
36. Lighting optical system for an imaging apparatus to form an
optical image depending on a video signal by irradiating the
display elements with the light from the light source unit,
comprising an array lens having the structure that a lens to
condense the light from said light source unit to form a plurality
of light source images is used and a plurality of lens cells having
the focal distance of almost 30 mm or less are arranged in a
plane.
37. Array lens having the structure that a plurality of lens cells
having the diagonal size of almost 0.18 inch or less are arranged
in a plane.
38. Array lens having the structure that lens cells in total number
of about 240 or more are arranged in a plane.
39. Array lens having the structure that a plurality of lens cells
having the focal distance of almost 30 mm or less are arranged in a
plane.
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] The present invention relates to a technique of an apparatus
for displaying images on a screen using a liquid crystal panel and
an other display elements, for example, a liquid crystal projector,
a reflection type image displaying projector, a liquid crystal
television and a projection type display apparatus.
[0003] A projection type imaging apparatus such as a liquid crystal
projector has been popular, in which the display element such as a
liquid crystal panel or the like is irradiated with the light beam
emitted from the light source and thereby an image on the display
element can be projected as the enlarged image.
[0004] In the imaging apparatus of this type, the light from the
light source is adjusted through conversion to gray scale of each
pixel with the display element and is then projected to the screen.
For example, in the case of the twisted nematic (TN) type liquid
crystal display element in which the display element is a typical
example of the liquid crystal display element, two sheets of
polarizing plates are arranged to result in difference of 90
degrees of polarizing directions before and after the liquid
crystal cell which is formed by supplying the liquid crystal to the
space between a couple of transparent substrates having the
transparent electrode films. In this case, amount of transmitting
light of the incident light beam is controlled to display the image
of information by combining the operations for rotating the
polarizing plane with the electro-optical effect of the liquid
crystal and selecting the polarizing element of the polarizing
plate. In recent years, such transmitting type or reflection type
display element has remarkably reduced in size of the element
itself and also has improved performance such as resolution,
etc.
[0005] Therefore, with advancement in size reduction and
performance of the apparatus utilizing the display element, a
projection type imaging apparatus has newly been proposed as the
apparatus not only for realizing image formation by video signal or
the like which has been done in the related art and but also for
use as an image output device of a personal computer. The
projection type imaging apparatus of this type is particularly
required to be small in size and to assure that bright image can be
obtained up to the corners of the display screen.
[0006] However, the projection type imaging apparatus of the
related art has problems that the apparatus size is large and
brightness and quality of image attained finally are
insufficient.
[0007] For example, in the case of liquid crystal display
apparatus, size reduction of the light bulb, namely liquid crystal
element itself is effective for size reduction of the apparatus as
a whole, but when the liquid crystal display element is reduced in
size, the area irradiated by the light of liquid crystal means
becomes small, raising a problem that a ratio in amount of light
flux on the liquid crystal display element for amount of total
light flux radiated by the light source (hereinafter, referred to
as light application efficiency) becomes lower and side area of
display screen becomes dark. Moreover, since the liquid crystal
display element can utilize the polarized light beam of only one
direction, about a half of the light beam emitted from the light
source which radiates the random polarized light beam is left
unused.
[0008] As a means for attaining the bright image at the four sides
of the display screen, an integrator optical system, for example,
has been proposed, in which a couple of lenses are used as
described in the Japanese Published Unexamined Patent Publication
No. HEI 3-111806. The integrator optical system divides the light
from the light source with a plurality of condenser lenses in the
shape of the rectangular opening forming a first array lens and
then focuses in overlapping the output light in the shape of
rectangular opening at the radiating surface (liquid crystal
display element) with a second array lens formed by the condenser
leans group corresponding to the condenser lenses in the shape of
rectangular opening. In this optical system, intensity distribution
of the light irradiating the liquid crystal display element can be
almost equalized. Meanwhile, as the optical system for irradiating
the liquid crystal display element with the light beam emitted from
the light source and arranged in one polarizing direction, a system
is disclosed in the Japanese Published Unexamined Patent
Publication No. HEI 4-63318, in which the light beam emitted from
the light source and is polarized at random is isolated to the
P-polarized light beam and S-polarized light beam using the
polarizing beam splitter and these are then combined with a
prism.
[0009] However, in the conventional integrator optical system,
since a diagonal size of one lens cell of array lens is 0.25 inch
or larger, an F value of the light system must be set to almost 2
or 3 in order to improve equality of brightness and quality of
image using the liquid crystal display element with a micro-lens.
As a result, distance between the first and second array lenses
becomes not shorter than 31 mm, disabling reduction in size of the
optical system. Therefore, it has been difficult for the projection
type liquid crystal apparatus of the related art to reduce the size
of apparatus exceeding the size of the A4 file size. Moreover, even
in the optical system utilizing the polarizing beam splitter, it is
difficult to realize matching in accuracy in the array lens and
therefore size reduction has also been difficult. As a result, it
has been difficult to simultaneously realize reduction in size of
the apparatus as a whole and improvement in performance such as
brightness. In addition, in the case of the projection type liquid
crystal apparatus, it has also been difficult, even when only the
lighting means is improved, to attain the display apparatus which
is small in size and assures good display image quality because the
image quality depends on various factors, in addition to such
lighting means, such as optical characteristic of objection leans
and optical characteristic of liquid crystal element.
[0010] Moreover, it has been required to use a larger array lens in
order to improve brightness in the integrator optical system of the
related art and when the projection type liquid crystal apparatus
is reduced in size, brightness has been lowered. In addition, this
phenomenon can also be observed when size reduction is conducted in
the optical system using the polarizing beam splitter. As a result,
it has been difficult to simultaneously realize size reduction of
the apparatus as a whole and improvement in performance such as
brightness. Moreover, when a polarized beam combining means is
used, performance deterioration due to unwanted light beam, namely
the P-polarized light beam entering the S light path has also been
observed.
SUMMARY OF THE INVENTION
[0011] It is therefore an object of the present invention to
improve disadvantages of the related art explained above, assure
sufficient brightness and good image quality and provide the image
display technique which enables higher accuracy and sufficient
reduction in size of apparatus.
[0012] In order to attain the objects explained above, the present
invention provides the structure that:
[0013] (1) an array lens is provided, in which at least any one of
the diagonal size, vertical size and lateral size of lens cell is
equal to almost 1/(4.5 or more) for each corresponding size of a
display element which is irradiated by a lighting optical
system;
[0014] (2) an array leans is provided, in which a diagonal size of
lens cell is almost 0.18 inch or less;
[0015] (3) an array lens is provided, in which the total number of
lens cells is almost 240 or more;
[0016] (4) an array lens is provided, in which the lens focal
distance of lens cell is 30 mm or less;
[0017] (5) a light shielding means is provided to eliminate
unwanted light beam to the light incident side than the light
source unit or light isolating means for isolating the light
emitted from the array lens to the P-polarized light beam and
S-polarized light beam; and
[0018] (6) a first array lens for condensing the light from the
light source unit to form a plurality of secondary light source
image, a second array lens for focusing a lens image of the first
lens array lens to the display element, an isolating means for
isolating the light beam emitted from the light source unit or from
the array lens into the P-polarized light beam and S-polarized
light beam, and a converting means for changing any one beam of the
P-polarized light beam and S-polarized light beam of the output
light beam emitted from the isolating means are arranged almost on
the same optical axis like the linear line.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a diagram illustrating a preferred embodiment of
the present invention.
[0020] FIG. 2 is a diagram illustrating a structure of the
apparatus as a preferred embodiment of the present invention.
[0021] FIG. 3 is a diagram explaining the effect of a preferred
embodiment of the present invention.
[0022] FIG. 4 is a diagram illustrating a preferred embodiment of
the present invention.
[0023] FIG. 5 is a diagram illustrating the other preferred
embodiment of the present invention.
[0024] FIG. 6 is a diagram illustrating the other preferred
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] The preferred embodiments of the present invention will be
explained with reference to the accompanying drawings.
[0026] FIG. 1 illustrates a first preferred embodiment of the
projection type liquid crystal display apparatus of the present
invention. In FIG. 1, the projection type liquid crystal display
apparatus is provided with a light source 1. This light source 1 is
formed of a super-high pressure mercury lamp, metal halide lamp,
xenon lamp, mercury xenon lamp and a white lamp such as halogen
lamp. The light source 1 has at least one reflecting mirror 5
having a circular or polygonal light emitting aperture and an
electrode wire 28 having the diameter, for example, of 0.6 mm or
less provided at one side of the lamp electrode in the reflecting
mirror and the light beam emitted from this light source 1 travels
toward a projection lens 3 passing through a liquid crystal display
element 2 as a light bulb element and is then projected to a screen
4.
[0027] The light beam radiated from a bulb of the light source 1 is
condensed by a reflector 5 having the elliptical surface, parabolic
surface or non-spherical surface and then enters a first array lens
6. After passing the first array lens 6, the light beam passes a
second array lens 7 and then enters a polarized beam splitter 8.
This incident light beam is isolated, as the transmitting light
beam, to the P-polarized light beam and S-polarized light beam by
the polarized beam splitter 8, and the P-polarized light beam is
rotated by 90 degrees in the polarizing direction by a .lambda./2
phase difference plate 9 arranged at the light emitting side
surface of the polarized beam splitter 8 to become the S-polarized
light beam and is then incident to a condenser lens 10. Moreover,
the S-polarized light beam repeats reflection and is then emitted
from the light emitting surface of the neighboring polarized beam
splitter 8 and then enters the condenser lens 10. The condenser
lens 10 is formed of at least one or more sheet of lens having the
positive index of refraction and has a function to further condense
the S-polarized light beam. The light beam having passed the
condenser lens 10 irradiates the liquid crystal display element 2.
At the incident side of this liquid crystal display element 2, an
incident light polarizing plate 11 transmitting the S-polarized
light beam is arranged.
[0028] In the projection type liquid crystal display apparatus of
the related art, the polarized light beam of only one direction is
transmitted through combination of the incident light polarizing
plate 11, liquid crystal display element 2 and light emitting side
polarizing plate 12 and thereby amount of light to be transmitted
has been reduced to almost a half. However, since the polarized
light beam splitter 8 is used in the preferred embodiment, the
polarizing directions of the randomly polarized light beams emitted
from the light source 1 are equalized in one polarizing direction
and this light beam is then input to the liquid crystal display
element 2. Ideally, the brightness two times that of the projection
type liquid crystal display apparatus of the related art can be
attained.
[0029] Moreover, in this embodiment, the first array lens 6 and
second array lens 7 of the present invention are same in the type
thereof and lateral size of one lens cell has the ratio of almost
1/5.3 against the lateral size of the liquid crystal display
element. For example, when the diagonal size of rectangular image
display means of the liquid crystal display element 2 is 0.9 inch,
the diagonal size of rectangular shape of one lens cell is almost
0.17 inch, the total number of lens cells forming the first array
lens 6 and second array lens 7 is 240 or more and the focal
distance of one lens cell is 30 mm or less, thereby realizing
reduction in size of optical system. Moreover, individual images of
almost 240 or more cells are overlapped on the liquid crystal
display element 2 to obtain more uniform image quality than that of
the apparatus of related art. In addition, since the cell size is
0.17 inch, even when the shadow of electrode wire 28 crosses the
cell, image quality may be equalized because the number of cells is
240 or larger (almost 16.times.15 cells). Accordingly, the
projection type liquid crystal display apparatus can realize
simultaneously size reduction of the apparatus as a whole and
improvement of brightness.
[0030] Furthermore, the present invention provides the effect that
the unwanted light beam is cut by the polarized beam splitter 8
formed by adding the light shielding plate 11 to the optical axis
incident surface of the reflection prism of the S-polarized light
beam located at the center of the pitch of the optical axis of the
first array lens 6 and/or second array lens 7, namely at the
surface in the side of the first array lens 6 and/or second array
lens 7 and when unwanted light beam is absorbed and cut by the
incident light polarizing plate 11, heat radiation occurring when
the light beam is converted to heat through energy conversion can
be prevented. Moreover, color irregularity generated when unwanted
light beam enters the liquid crystal display element 2 can also be
reduced.
[0031] Moreover, the polarized beam splitter 8 of the present
invention 8 is formed thinner in the optical axis direction then
the second array lens 7 to realize shortening of the total length
of optical system, light weight of the optical unit and increase of
F value of the lighting system. Thereby, since small size and light
weight can be realized and moreover F value of the projecting lens
3 can also be increased in connection with the lighting system, the
projecting-lens 3 can also be reduced in size and weight.
[0032] The light beam having passed the liquid crystal display
element 2 reaches the display screen 4 passing the projecting means
3 such as, for example, a zoom lens. An image formed on the liquid
crystal display element 2 by the projecting means 3 is projected on
the screen as the enlarged image by the function of the display
apparatus.
[0033] Next, a practical embodiment of the present invention will
be explained.
[0034] FIG. 2 is a schematic diagram illustrating the structure of
the projection type liquid crystal display apparatus of the present
invention. The embodiment of FIG. 2 is a 3-plate type projection
display apparatus using three transmitting type liquid crystal
display elements 2 as the liquid crystal light bulbs corresponding
to so-called three primary colors of R(Red), G(Green) and B(Blue).
In this embodiment, the light beam emitted from the lamp 13 such
as, for example, super-high pressure mercury lamp as the light
source is once reflected by a parabolic reflection mirror type
reflector 5 and is thereafter incident to the first array lens 6
which is formed by a plurality of condenser lenses provided at the
rectangular frame almost in the same size as the light emitting
aperture of such parabolic reflection mirror type reflector 5 to
condense the light emitted from the lamp unit 14 and form a
plurality of secondary light source images and then passes the
second array lens 7 which is formed by a plurality of condenser
lenses and located at the area near a plurality of secondary light
source images to focus individual lens images of the first array
lens 5 to the liquid crystal display element 2. This light beam
emitted from the second array lens 7 is incident to a line of
rhombus prisms almost in the 1/2 size of width of each lens
arranged in such a manner as fitting to the pitch in the lateral
direction of the optical axis of lens of the second array lens 7. A
film of the polarized beam splitter 8 is formed on the surface of
this prism and therefore the incident light beam is isolated to the
P-polarized light beam and S-polarized light beam by the polarized
beam splitter 8. The P-polarized light beam travels in straight in
the polarized beam splitter 8, it is then rotated by 90 degrees in
the polarizing direction by the .lambda./2 phase difference plate 9
provided at the light emitting surface of the prism and is then
emitted after it is converted to the S-polarized light beam.
Meanwhile, the S-polarized light beam is reflected by the polarized
beam splitter 8, it is then reflected again in the intrinsic
optical axis direction within the neighboring rhombus prism and it
is emitted as the S-polarized light beam. Of course, the polarized
beam splitter 8 of the present invention adds a light shielding
member 27 (see FIG. 4A and FIG. 4B) to the optical axis incident
surface of the reflection prism of the S-polarized light beam
located at the center of the pitch of the optical axis of each lens
of the second array lens 7, namely to the surface in the side of
the second array lens 7. Thereafter, light beam is condensed to the
liquid crystal display element 2 by the condenser lens 10. In the
course of this process, the light beam emitted from the polarized
beam splitter 8 is bent in its optical path by 90 degrees with a
total reflection mirror 15 and a B(Blue), G(Green) reflection
dichroic mirror 16 allows the R (Red) color light beam to pass and
reflects the B, G lights. The R light beam having passed the
dichroic mirror is bent in its optical path by 90 degrees with the
total reflection mirror 17 for R light beam, passes through the
condenser lens 18 and incident polarizing plate 11 provided before
the liquid crystal display element, is incident to the liquid
crystal display element 2 formed of an opposing electrode and
liquid crystal or the like and then passes through the polarizing
plate 12 provided in the light emitting side of the liquid crystal
display element 2.
[0035] The liquid crystal display element 2 is provided with the
liquid crystal display areas in such number (for example, 800
pixels in lateral direction.times.600 pixels in vertical direction
for each color of three colors) corresponding to the display
pixels. Depending on the signal driven from the external side,
polarizing angle of each pixel of the liquid crystal display
element 2 changes and finally the light in the direction matched
with the polarizing direction of the polarizing plate 12 is emitted
and the light in the orthogonal direction is absorbed by the
polarizing plate 12. The light polarized by the intermediate angle
determines amount of light beam passing through the polarizing
plate and amount of light beam absorbed by the polarizing plate in
relation to the polarizing angle of the polarizing plate 12. As
explained above, an image is projected conforming to the external
input signal.
[0036] The R light beam emitted from the polarizing plate 12 is
reflected by the dichroic prism 19 having the function to reflect
the R light beam, then enters the projecting means 3 such as a zoom
lens and is then projected to the display screen.
[0037] On the other hand, the B light beam and G light beam having
passed the B, G transmitting dichroic prism 19 enter a G-reflection
dichroic mirror 20. This mirror 20 reflects the G light beam. The
reflected G light beam then passes through the condenser lens 18
and incident polarizing plate 11 provided before the liquid crystal
display element 2 and then enters the liquid crystal display
element 2 and passes through the polarizing plate 12 provided in
the light emitting side of the liquid crystal display element 2.
The G light beam emitted from the polarizing plate 12 passes
through the dichroic prism 19 having the function to transmit the G
light beam, enters the projection lens 3 and is then projected to
the display screen.
[0038] Meanwhile, the B light beam transmitted through the G
reflection dichroic mirror 20 passes through a relay lens 21, it is
then bend in the optical path by 90 degrees with a total reflection
mirror 22 to pass through the relay lens 21, thereafter it is then
bent again in its optical path by 90 degrees with a total
reflection mirror 23 to pass through the condenser lens 18 and
incident polarizing plate 11 provided before the liquid crystal
display element, it enters the liquid crystal display element 2 and
finally passes through the polarizing plate 12 provided in the
light emitting side of the liquid crystal display element. The B
light beam emitted from the polarizing plate 12 is reflected by the
dichroic prism 19 having the function to reflect the B light beam
and thereafter enters the projection lens 3 for projection to the
display screen.
[0039] Moreover, the B light beam transmitted through the G
reflection dichroic mirror 20 passes through the relay lens 21, it
is then bent in its optical path by 90 degrees with the total
reflection mirror 22 to pass the relay lens 21, thereafter it is
bent again in its optical path by 90 degrees with the total
reflection mirror 23 to pass the condenser lens 18 and incident
polarizing plate 11 provided before the liquid crystal display
element, it enters the liquid crystal display element 11 to pass
through the polarizing plate 12 provided in the light emitting side
of the liquid crystal display element 2. The B light beam emitted
from the polarizing plate 12 is reflected by the dichroic prism 19
having the function to reflect the B light beam and enters the
projection lens 3 for projection to the display screen.
[0040] As explained above, the light beams respectively
corresponding to R, G, B are isolated and combined by the color
isolating means and color combining means and the images of
respective colors are combined on the screen to attain the enlarged
image by enlarging the image on the liquid display element
respectively corresponding to R, G, B with the projection lens 3.
In the same figure, the power supply circuit 24 and image signal
circuit 25 are arranged as illustrated in the figure and heat
generated by the light source 1 is guided to the external side with
a blowing fan 26. Moreover, in this embodiment, the light beams
emitted randomly from the light source are aligned in one direction
and therefore less amount of heat is generated from the incident
polarizing plate.
[0041] Moreover, the light source and projecting means are arrange
in such a manner that the optical axes thereof are orthogonal with
each other and in addition, the apparatus as a whole can be reduced
in size by arranging the power supply circuit 24 and image signal
circuit 25 as illustrated in the figure via the color isolating and
combining unit consisting of the color isolating means and liquid
crystal display element and color combining means.
[0042] In addition, in this embodiment, the first array lens 6 and
the second array lens 7 used in the present invention are formed in
the same shape, the lateral size of one lens cell has a ratio of
about 1/5.3 of the lateral size of the liquid crystal display
element 2. For instance, when the diagonal size of rectangular
shape of the image display area of the liquid crystal display
element 2 is 0.9 inch, the diagonal size of rectangular shape of
one lens cell of the fist array lens 6 and second array lens 7 is
about 0.17 inch, the diagonal size of rectangular shape of one lens
cell of the first array lens 6 and second array lens 7 is about
0.17 inch, the total number of lens cells forming the first array
lens 6 and second array lens 7 is about 240 or more and the focal
distance of one lens cell of the first array lens 6 and second
array lens 7 is 30 mm or less. As a result, size reduction of the
optical system can be attained. Moreover, individual images of
almost 240 or more cells are overlapped on the liquid crystal
display element 2 and thereby more homogeneous image than that of
the apparatus of related art can be obtained.
[0043] In addition, even if the shadow of the electrode wire 28 is
crossing the cell because the cell size is 0.17 inch, when the
number of cells exceeds about 240 cells (almost 15.times.15 cells),
image quality can be more equalized. Therefore, size reduction and
improvement of brightness of the apparatus as a whole can be
realized simultaneously in the projection type liquid crystal
display apparatus.
[0044] Moreover, when it is required to improve brightness and
homogeneity of image using the liquid crystal display element with
micro-lens or the like, the F value of the lighting system must be
set to about 2 to 3. Even in this case, an interval of the first
array lens and second array lens of the present invention can be
reduced to the distance of 30 mm or less and as a result the size
reduction of optical system can be realized.
[0045] Furthermore, in the present invention, since a polarizing
and combining means (in some cases, a light shielding member is
added) is combined and the polarized beam splitter 8 as the
polarizing and combining means is formed thinner than the second
array lens 7 (namely, the polarizing beam splitter 8 is set to 2 mm
or less when the second array lens 7 is about 2.5.+-.0.5 mm),
length of optical path can be shortened and the total reflection
mirror 15 can be arranged closely, thereby resulting in size
reduction of the set.
[0046] In the embodiment of the present invention illustrated in
FIG. 2, the lighting and optical system comprises a lamp unit 14, a
first array lens 6, a second array lens 7, a polarized beam
splitter 8, a .lambda./2 phase difference plate 9, a condenser lens
10 and a total reflection mirror 15 and establishes the optical
path until the part for isolating the light beam emitted from the
lamp 13 to the R, G, B light beams. Moreover, the optical unit
includes the lighting and optical system to define the process up
to the isolation of the light beam emitted from the lighting and
optical system to the R, G, B light beams respectively using the B
(Blue), G(Green) reflection dichroic mirror 16 and G reflection
dichroic mirror 20 or the like and also to define the optical path
up to the projecting means 3 via the dichroic prism 19 which allows
application of the isolated R, G, B light beams to the respective
liquid crystal display element 2, reflects the R light beam and B
light beam and transmits the G light beam.
[0047] FIG. 3 is a diagram illustrating a part of effect of the
first embodiment of the present invention.
[0048] FIG. 3 illustrates the lighting and optical system of the
projection type liquid crystal display apparatus. The light source
1 has a circular reflecting mirror 5 and an electrode wire 28
having the diameter of almost 0.6 mm or less provided at the single
side of the lamp electrode within the reflecting mirror 5.
[0049] The light beam radiated from a bulb of the light source 1 is
condensed by an elliptical surface or parabolic surface or
non-spherical surface reflector 5 and is then incident to the first
array lens 6. After passing the first array lens 6, the light beam
passes the second array lens 7 and then enters the polarized beam
splitter 8. The transmitted light of this incident light beam is
isolated to the P-polarized light beam, while the reflected light
thereof is isolated to the S-polarized light beam respectively by
the polarized beam splitter 8. The P-polarized light beam is
rotated by 90 degrees in its polarizing direction by the .lambda./2
phase difference plate 9 provided at the light emitting side
surface of the polarized beam splitter 8 to become the S-polarized
light beam and enters the condenser lens 10. Moreover, the
S-polarized light beam is repeatedly reflected and is then emitted
from the light emitting surface of the neighboring polarized beam
splitter 8 to enter the condenser lens 10. The condenser lens 10 is
formed of at least a sheet of lens or more lenses having the
positive index of refraction having the function to further
condense the S-polarized light beam. The light beam having passed
the condenser lens 10 irradiates the liquid crystal display element
2.
[0050] Referring to FIG. 3, the first array lens 6 and second array
lens 7 of the present invention are formed in the same shape. The
lateral size of one lens cell has a ratio of almost 1/5.3 of the
lateral size of the liquid crystal display element 2. For example,
when the diagonal size of rectangular shape of the image display
area of the liquid crystal display element 2 is 0.9 inch, the
diagonal size of rectangular shape of one lens cell of the first
array lens 6 and second array lens 7 is almost equal to the size of
0.17 inch, the total number of lens cells forming the first array
lens 6 and second array lens 7 is 240 or more and the lens focal
length of one lens cell of the first array lens 6 and second lens
array 7 (FIG. 3 is a schematic diagram) is 30 mm or less.
Accordingly, size reduction of optical system can be attained.
Moreover, as indicated by dotted line of FIG. 3, individual images
of 240 cells or more are overlapped on the liquid crystal display
element 2 and more homogeneous image quality than that of the
related art can be obtained. In addition, since the cell size is
0.17 inch, even if the shadow of the electrode wire 28 crosses the
cell, when the number of cells is about 240 (almost 16.times.15
cells) or more, seven (7) to eight (8) lines are arranged in the
single side. When the cell size is 0.17 inch, six lines of belt
type shadow having the width of almost 0.6 mm are arranged in one
cell size. Therefore, when at least six lines are arranged in the
single side of cell, dark area resulting from shadow of the
electrode wire 28 on the liquid crystal display element can be
freed and resultant color irregularity can also be eliminated and
homogeneous image quality can be attained. In this case, since the
electrode wire exists in the single side of the right and left
sides of the optical axis center, when one to two lines are
provided as the allowance of the vertical or horizontal arrangement
of array lens, 14 to 16 lines in minimum are required. Accordingly,
when the number of cells is about 240 or more, shadow of the
electrode wire of almost 0.6 mm or less is reflected equally like
the diagonal line of the figure on the liquid crystal display
element. Thereby, image quality assuring equal brightness and no
color irregularity can be attained.
[0051] Therefore, the projection type liquid crystal display
apparatus can simultaneously realize reduction in size and
improvement in brightness of the apparatus as a whole. Moreover,
since the first array lens 6 and second array lens 7 are formed in
the same shape, only one type is used and cost reduction can also
be attained.
[0052] FIG. 4 is a diagram illustrating the second embodiment of
the present invention.
[0053] The polarized beam splitter 8 illustrated in FIG. 4A and
FIG. 4B is provided with a polarized beam splitter film at the
glass plate thereof for isolating the P-polarized light beam and
S-polarized light beam. After this film is laminated using a
bonding agent, the glass plate is sliced in the angle of 45
degrees. Therefore, as illustrated in FIG. 4, there is provided a
flat plate structure wherein a plurality of longitudinally
elongated rhombus prisms are arranged. Such filming may be attained
by conducting the mirror evaporation of aluminum or silver or the
like in every other surface. However, since this mirror section has
a role of reflecting the S-polarized light beam, it is required to
provide a certain means for not allowing the light beam to enter
the light path of the prism.
[0054] Therefore, the polarized beam splitter 8 of the present
invention adds a light shielding member 27 to the optical axis
incident surface of the S-polarized light beam reflection prism
located at the center of the pitch of the optical axis of each lens
of the second array leans 7, namely to the surface in the side of
the second array lens 7 to provide the effect that unwanted light
beams can be cut and when the light beam is absorbed and cut by the
incident polarizing plate 11, the heat generated through energy
conversion from the light beam to heat energy can be prevented.
This light shielding member 27 is formed of slit type reflection
films, or ground glass type dispersion films, or metal seal for
light shieldings, or heat-proof seals, or slitted metal plates, or
metal plating, or the like in every other one formed with silver or
aluminum evaporation film.
[0055] In the flat plate structure where a plurality of polarized
beam splitters 8 are arranged as explained above, they are bonded
in every other line, it is also possible that the isolated
P-polarized light beam is converted to the S-polarized light beam,
the light beam emitted from the polarized beam splitter 8 is
totally set to the S-polarized light beam, or after the isolated
S-polarized light beam is emitted by reflection from the prism
adjacent to the incident prism, the light beam emitted from the
polarized beam splitter 8 is totally set to the P-polarized light
beam with the .lambda./2 phase difference plates 9.
[0056] When a plurality of rhombus prisms of the flat type
polarized beam splitter 8 explained above are arranged conforming
to the pitch, in the lateral arrangement direction, of the lens
optical axis of the second array lens 7 and one polarized beam
splitter 8 and the other polarized beam splitter 8 are bonded
symmetrically in the right and left sides of the center under the
condition rotated each other by 180 degrees in such a manner that
the second array lens 7 is divided respectively to half areas in
the right and left or upper and lower sections keeping a clearance,
for example, h equal to 1/2 of the width of the optical axis pitch
at the center of the second array lens 7, the light shielding
member 27 provided in the second array lens 7 can be matched in
higher accuracy with the pitch in the lateral arrangement direction
of the polarized beam splitter 8 and thereby highly accurate
bonding among the second array lens 7, light shielding member 27
and polarized beam splitter 8 which has been considered difficult
in manufacturing process can be realized.
[0057] In the structure of the related art, since the light
transmitting efficiency is lowered even when interface is formed of
reflection-proof film in such a case that the flat type polarized
beam splitter 8 formed symmetrically in the right and left
direction as illustrated in FIG. 4A or FIG. 4B and interface
between optical parts such as this polarized beam splitter 8 and
second array lens 7 is formed of the layer of air, this polarized
beam splitter 8 and the second array lens 7 are bonded conforming
to the pitch in the lateral arrangement direction of the lens
optical axis and the polarized beam splitter 8. In this case, the
slit type light shielding plate to cut the unwanted light beam is
arranged before the second array lens 7, namely in the side of
light source in view of shielding the unwanted light element,
namely the hatched element in the FIG. 4B before the light beam
enters the polarized beam splitter 8. However, in this case, the
light shielding member 27 is formed of a member such as metal plate
having a slit and therefore it must be supported independent of the
optical axis.
[0058] For this reason, the required light beam also has been
shielded due to part accuracy error or assembling accuracy error of
the light shielding member 27 and the number of parts has also been
increased even in the case of assembling, resulting in increase of
processing cost.
[0059] However, in the present invention, since the polarized beam
splitter 8 is bonded symmetrically in the right and left direction
in both sides of the center to the second array lens 7 providing
the light shielding member 27 and the light shielding member 27 is
formed of an evaporation film or the like, the light incident
surface of the prism in the S light path can be shielded almost
without any error and the number of parts can also be reduced to
improve the assembling efficiency.
[0060] Moreover, in the present invention, the process of the
second stage that the flat type polarized beam splitter 8 which is
symmetrical in the right and left direction is produced by a maker
and is then bonded to the second array lens 7 like the prior art is
eliminated but a couple of polarized beam splitters 8 are bonded to
the second array lens 7 in the process of the first stage. As a
result, processing cost can be lowered.
[0061] In addition, since the polarized beam splitter 8 of the
related art is integrated in the right and left sides, the bonding
accuracy is overlapped from the left end to the right end and
therefore when the beam splitter 8 is bonded to the second array
lens 7, it is shared at the center to the right and left side,
certainly resulting in the bonding accuracy error in the right and
left sides, for example, the error of .+-.0.25 in both right and
left sides.
[0062] However, in the present invention, since the polarized beam
splitter 8 is bonded to the second array lens 7 providing
individual light shielding members 27 in the right and left sides,
the accuracy error from the center is never accumulated and
therefore since the left polarized beam splitter 8 can define the
left center thereof or the lens optical axis of the left half on
the second array lens 7 in a large amount of light beam as the
center for accuracy sharing, the accuracy error can be controlled
to .+-.0.125 in the numerical value. When the right side polarized
beam splitter 8 is bonded to the second array lens 7 in the same
manner, the effect to reduce the bonding accuracy error can also be
attained as in the case of the left side. Thereby, positional
displacement of the optical axis due to the bonding error of the
polarized beam splitter 8 in the half width of the lens optical
axis pitch of the second array lens 7 can be reduced and amount of
incident light beam from the second array lens 7 to be reflected by
the polarized beam splitter 8 can also be reduced. Accordingly, the
light transmitting efficiency can be improved to realize
improvement in brightness. The polarized beam splitter 8 is
naturally formed thinner than the first or second array lens 7 and
when it is required to shield the light beam with an evaporation
film, the evaporation system is different from that when the
polarized beam splitter 8 formed thicker than the ordinary second
array lens 7 is used. Namely, it is necessary for not cutting the
light beam to be used to set the area of the light shielding means
to realize light shielding for rather narrower area by considering
the bonding accuracy error rather than the P-polarized light beam
aperture or S-polarized light beam aperture of the polarized beam
splitter 8 for light shielding.
[0063] Such accuracy of light shielding means, for example, an idea
for making the width of light shielding film a little smaller than
the pitch width of the polarized beam splitter 8 is effective for
improvement of light efficiency when a larger number of cells are
used for the polarized beam splitter 8 which is thinner than the
second lens array 7 and the second lens array 7. Moreover, in some
cases, it is also effective that many reference positions are
prepared and the polarized beam splitter 8 is divided for the
bonding as will be explained later considering the bonding
accuracy.
[0064] FIG. 5 is a diagram illustrating the external view of the
third embodiment of the present invention. In the present
invention, the first array lens 6 or second lens array 7 is
provided with a first positioning section 27 as the positioning
reference of each lens and the polarized beam splitter 8 is also
provided a second positioning section 28 as the positioning
reference. This first positioning section 27 and the second
positioning section 28 are respectively formed by the engraving
(illustrated in FIG. 5), recessed area, projected area, end
surface, cutout area, stepped area or marking or the like and the
absolute positioning of the first array lens 6 or second array lens
7 can be performed by aligning the first positioning section 27 to
the positioning area (not illustrated) provided to the structure
member for supporting and fixing the first array lens 6 or second
array lens 7. In the same manner, the absolute positioning of the
polarized beam splitter 8 can also be performed by aligning the
second positioning section 28 of the polarized beam splitter 8 to
the positioning area (not illustrated) provided to the structure
member for supporting and fixing the polarized beam splitter 8.
[0065] According to the present invention, respective reference
positioning can be made easily when assembling the first array lens
6, second array lens 7 and polarized beam splitter 8 to the optical
part supporting structure member and relative lens optical axes of
the first array lens 6 and array lens 7 may be matched at the
design position and arrangement of polarized beam splitter 8 can be
located at the position resulting in the maximum light application
efficiency conforming to the lateral arrangement pitch of the lens
optical axis explained above. Thereby, optical performance can be
improved and the assembling work of these optical parts can be
simplified to improve the working efficiency.
[0066] In addition, as illustrated in FIG. 5, the polarized beam
splitter 8 can be arranged to the optimum position for each lens
optical axis of the second array lens 7 by providing the first
positioning section 27 of the second array lens 7 and the second
positioning section 28 of the polarized beam splitter 8 to the
positions to be matched and then matching these positioning
sections at the time of assembling. Thereby, matching can be made
to the position providing the maximum light application efficiency
in view of improving the optical performance.
[0067] FIG. 6 is a diagram illustrating the external appearance of
the fourth embodiment of the present invention. In the present
invention, the first array lens 6 or second array lens 7 is
provided with the first positioning section 27 as the positioning
reference of each leans and the polarized beam splitter 8 is
provided with the second positioning section 28 as the positioning
reference. These first positioning section 27 and second
positioning section 28 are formed as the recessed area and
projected area as illustrated in FIG. 6A. These first and second
positioning sections 27, 28 are combined to match the projected
area and recessed area for the positioning so that the polarized
beam splitter 8 is located at the optimum position for the lens
optical axis of each lens of the first array lens 6 or second array
lens 7 and thereafter the polarized beam splitter 8 can be bonded
to the first array lens 6 or the second array lens 7. Accordingly,
matching can be made to the position providing the maximum
application efficiency of the light and bonding explained above
assures reduction in amount of light reflected at the interface of
the optical elements and improvement in the optical
performance.
[0068] In addition, the first positioning section 27 and second
positioning section 28 are not limited to the recessed area and
projected area and these may be FIG. 6B in which end faces of each
part are positioned so as to coincidence with optical axes as
illustrated, or FIG. 6C the first positioning section 27 is
positioned in the second positioning section 28 as illustrated, or
FIG. 6D the type where entire part of one positioning frame is
engaged with the other frame as illustrated, or FIG. 6E the type
where both sections are positioned and bonded via a third member
such as the positioning jig 31 or the like as illustrated.
Moreover, it is also possible to improve accuracy by designing the
sizes, considering the accumulated element accuracy error, so that
the polarized beam splitter 8 is located to the optimum position
for each lens optical axis of the array lens.
[0069] According to the present invention, length of optical path
can be shortened and the apparatus can be reduced in size.
Brightness can also be improved. Moreover, image quality
improvement such as equalization of image quality can also be
realized. In addition, generation of heat due to unwanted light
beam can also be prevented.
[0070] The present invention allows any modification of the
embodiment explained above without departing from the spirit and
scope of the principal characteristics thereof. The embodiment
explained above is therefore only an example of the present
invention and should not be limited thereto. The scope of the
present invention is limited only by the appended claims. Moreover,
any modifications and changes in regard to the appended claims
should be within the scope of the present invention.
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