Liquid crystal cells – elements and systems – Liquid crystal system – Stereoscopic
Reexamination Certificate
2001-12-07
2004-10-05
Chowdhury, Tarifur R (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal system
Stereoscopic
C349S005000, C349S096000, C349S175000, C353S007000, C359S376000
Reexamination Certificate
active
06801263
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a liquid crystal display apparatus, liquid crystal device and liquid crystal display system with which a recorded picture having the stereoscopic information may be viewed as a three-dimensional picture, or a so-called stereo image, using a liquid crystal display. More particularly, it relates to a liquid crystal display apparatus, a liquid crystal device and a liquid crystal display system so designed that, even if the position of a viewer's head is varied, the stereo image can be appreciated satisfactorily.
BACKGROUND ART
Up to now, various techniques of representing an image three-dimensionally were developed, and the representing methods for three-dimensional images were researched and put to use in many fields, such as photography, cinema or television. The methods for demonstrating a three-dimensional image may be classified into a method employing glasses and a method not employing them.
Typical of the system employing glasses are an anaglyphic system in which a viewer wears so-called red glasses or blue glasses, and a system in which a viewer wears polarizing glasses. With these systems, an image presenting parallax is input to left and right eyes of a user whereby the viewer may see the image as a stereo image.
On the other hand, a 3D (three-dimensional) display apparatus of the lenticular system or the parallax barrier system is already in the stage of practical application. With these systems, an area that permits stereo vision is extremely narrow in the transverse direction and is ±several cm, so that limitations are perpetually imposed on user head positions.
So, such a back light splitting system, disclosed in the Japanese Laying-Open Patent Publication H-10-63199, has been proposed as a liquid crystal apparatus in which the stereo image is not impaired even if the user viewing position is slightly offset in the left and right directions with respect to a liquid crystal display screen, and in which the stereo image can be appreciated as the horizontal resolution proper to the liquid crystal display screen is maintained.
The back light splitting system is hereinafter explained. A back light of a routine liquid crystal device is arranged at back of the liquid crystal panel with planar illumination, having an equivalent area to the panel area, in intimate contact with the liquid crystal panel, so that non-directive light is incident on the user's left and right eyes. In the back light splitting system, as contrasted to this conventional system, two back lights, having an appreciably smaller area than a liquid crystal panel, are separately arranged for left and right eyes at the positions spaced apart from the liquid crystal panel a distance slightly larger than the focal length of a convex lens, having a diameter approximately equal to that of the liquid crystal display screen, to take advantage of the directivity of the convex lens.
FIG. 1
shows a display apparatus of a point light source system disclosed in U.S. Pat. No. 2,679,176. A light beam illuminated from a point light source
41
to traverse a convex lens
42
is refracted by the convex lens
42
and converged at a point corresponding to a light converging point
43
. If an eye is at the site of the light converging point
43
, the convex lens
42
in its entirety shines brightly so as to serve as a back light for a liquid crystal display screen
44
placed in a near-by position.
FIG. 2
is a plan view for a case where the point light source
41
is replaced by a light source for a right eye. In such case, the light beam emitted from a light source for the right eye
45
acts as if it is of the same component as the light beam emitted from the point light source
41
and lights the entire surface of the convex lens
42
to then fall on a right eye
46
. The spatial light source by the light source
45
for the right eye causes a light source image area for a right eye
48
to be presented ahead of the convex lens
42
. As long as the viewer's right eye is at this light source image area for a right eye
48
, the convex lens
42
is lighted brightly uniformly so as to serve as a back light for the liquid crystal display screen
44
placed thereat. If this is applied to left and right eyes, the light source image areas, optimized for a right eye
46
and a left eye
50
, that is a light source image area for a right eye
48
and a light source image area for a left eye
49
, by two light sources arranged with a center axis C of the convex lens
42
as the boundary, that is a by surface light source
45
for the right eye and by a surface light source
47
for the left eye, are formed, as shown in FIG.
3
.
FIGS. 4 and 5
schematically show the state in which the light emitted from the light source
45
for the right eye and by the light source
47
for the left eye, operating as back lights, is sorted by a line-based polarization filter
52
to fall on the right eye
46
and on the left eye
50
. In this case, the light illuminated from the surface light source
47
for the left eye having a leftward descending Brewster angle is first directed to the left eye
50
due to the directivity of a Fresnel lens
51
. Then, only the image information for the left eye of an even line
54
, having a coincident Brewster angle, falls on the left eye
50
by the line-based polarization filter
52
. The light illuminated from the surface light source
45
for the right eye having a rightward descending Brewster angle is first directed to the left eye
50
due to the directivity of the Fresnel lens
51
. Then, only the image information for the right eye of an odd line
53
, having a coincident Brewster angle, falls on the right eye
46
by the line-based polarization filter
52
.
So, the left and right parallax information, represented on the lines of the liquid crystal display screen
44
, corresponding to the even line
54
and the odd line
53
, fall on both eyes of a viewer
13
lying before the liquid crystal display screen
44
to become fused in the user's brain so as to be perceived as a stereo image.
In this case, however, there is presented a problem that, since the left and right parallax information are split at a center axis C, that is at the center of the screen, the same image is incident on both eyes if the viewer
13
moves his or her head in the left and right directions, so that the both eyes enter one area, with the result that the image becomes a two-dimensional image to render the stereo vision impossible
On the other hand, if a 3D display apparatus is formed by a liquid crystal display device made up of polarizing filters
55
,
56
, glass substrates
57
,
58
, a half-wave plate
59
, a color filter
60
, a liquid crystal display screen
61
, a protective film
62
and a transparent electrode
63
, that is in a system in which the polarizing filter
56
is formed on the glass substrate
58
on the light incident side of the surface light source, the image information on a line which inherently should not be visible is superposed as crosstalk on he inherent image information if the line of sight of the viewer
13
is in the direction indicated by a dotted line arrow in
FIG. 6
, thus producing a stereo image extremely difficult to view.
That is, if the viewer
13
raises or lowers his or her head, the light transmitted through the half-wave plate
59
of a preset line falls astride two lines of a color filter
60
and a liquid crystal display surface
61
, without coinciding with a line of the color filter
60
and the liquid crystal display surface
61
associated with this line. For example, the light which should fall on the right eye
46
also falls on the line for left eye of the color filter
60
and the liquid crystal display surface
61
to get to the left eye
50
to produce the crosstalk.
It should be noted that, since the vertical pitch of a 10.4-inch SVGA (600 by 800 pixels) is 0.264 mm, the light beam traversing a polarizing filter on a glass substrate 1 mm in thickness, if deviated ±15 degrees in t
Sato Seiji
Sekizawa Hidehiko
Chowdhury Tarifur R
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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