Liquid crystal cells – elements and systems – Liquid crystal system – Liquid crystal eyewear
Reexamination Certificate
1997-04-25
2001-05-22
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal system
Liquid crystal eyewear
C349S180000, C359S630000
Reexamination Certificate
active
06236438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
In general, the present invention relates to an optical visualizing apparatus attached to the head of equipment such as an HMD (head mounted display) apparatus for viewing an image in front of a face. In particular, the present invention relates to an optical visualizing apparatus wherein a liquid crystal employed therein has the contrast of the visual-field angle thereof with an improved characteristic.
2. Description of the Related Art
FIG. 1
is a diagram showing an optical visualizing apparatus
50
used as an HMD (head mounted display) apparatus for viewing an image displayed by a liquid crystal in front of the eyes of an image viewer. As shown in the figure, the optical visualizing apparatus
50
comprises a head mounting unit
51
for supporting a display unit
58
in front of the eyes of an image viewer, the display unit
58
mounted in front of the eyes of an image viewer, standing face to face with the eyes of an image viewer, for projecting an image on both eyes of an image viewer and a linking unit
60
for linking the display unit
58
to the head mounting unit
51
and holding the display unit
58
in front of the eyes of an image viewer.
The head mounting unit
51
comprises a head supporting member
53
for supporting a forehead pad
52
brought into contact with the forehead, a pair of side cabinets
55
linked with the head supporting member
53
through hinges
54
at the ends of the head supporting member
53
, a head-circumference adjustable belt
56
adjustably connected to ends of the side cabinets
55
and a hair band
57
adjustably supported by the side cabinets
55
and provided on the head. Linked to one end of the linking unit
60
, the head mounting unit
51
has a curved shape approximately resembling the circumference of the head.
The display unit
58
comprises a cabinet with a shape approximately resembling goggles serving as a cover veiling the front face and a display body
59
protected by this cover.
FIG. 2
is a diagram showing the display body
59
. As shown in the figure, the display body
59
comprises a cabinet
61
, a liquid-crystal display element
62
for displaying an image inside the cabinet
61
, a light-source unit
63
for supplying light to the liquid-crystal display element
62
, a half mirror
64
capable of changing the optical path of an image from the liquid-crystal display element
62
and passing on the optical path and a concave mirror
65
for observing and enlarging the virtual image of a light beam with the optical path thereof changed by the half mirror
64
.
FIG. 6
is a diagram showing the liquid-crystal display element
62
. As shown in the figure, the liquid-crystal display element
62
comprises a liquid-crystal board
66
with a square shape for generating an image, a first polarizing board
68
provided above the liquid-crystal board
66
and a second polarizing board
69
placed beneath the liquid-crystal board
66
. The liquid-crystal board
66
is thus sandwiched by the first and second polarizing boards
68
and
69
. The first polarizing board
68
is used for polarizing a light in the longitudinal direction (or the vertical direction) with respect to the visual-field angle &thgr; of the eyeball
67
of an image viewer. On the other hand, the second polarizing board
69
is used for polarizing the light in the transverse direction (or the horizontal direction) with respect to the visual-field angle &thgr; of the eyeball
67
of an image viewer.
FIGS. 7A
to
7
C are explanatory diagrams showing the liquid-crystal board
66
as well as the first and second polarizing boards
68
and
69
. As shown in
FIG. 7B
, the liquid-crystal board
66
has a visual-field angle of about 90 degrees in twist orientations with respect to the vertical and horizontal directions as seen from the front thereof. As shown in
FIG. 7A
, the first polarizing board
68
has a vertical polarizing direction as seen from the front thereof. As shown in
FIG. 7C
, the second polarizing board
69
has a horizontal polarizing direction as seen from the front thereof.
By placing the display body
59
equipped with the liquid-crystal display element
62
with such a configuration at a location close to both eyes
67
of an image viewer, the contrast characteristics of an image displayed from the liquid-crystal display element
62
are improved in the directions of the visual-field angle &thgr; of the eyeball
67
of an image viewer. To be more specific, the contrast characteristic in the vertical direction with respect to the liquid-crystal board
66
is improved by the first polarizing board
68
. On the other hand, the contrast characteristic in the horizontal direction is improved by the second polarizing board
69
. As a result, an image displayed from the liquid-crystal board
66
has improved contrast characteristics in the vertical and horizontal directions. That is to say, the so-called optical transmittance is improved in both the vertical and horizontal directions.
However,a liquid-crystal display element that improves the characteristics of the contrast in the vertical and horizontal directions with respect to the directions of the visual-field angle of the liquid-crystal display element provided by the conventional technology described above has a poor contrast characteristic of a visual-field angle from a slanting direction. In order to correct the poor contrast characteristic, the amplitude is increased. When the amplitude is increased, however, part of the screen is inadvertently inverted, giving rise to a problem that a sharp contrast can not be obtained and it is thus impossible to improve the quality of the screen.
In order to solve this problem, the contrast in the horizontal direction with respect to the direction of the visual-field angle is changed. When the contrast is changed in this way, however, the contrast of an image on the right or left side is inadvertently changed in dependence upon the width of the eye, making the eyes of an image viewer become tired easily.
SUMMARY OF THE INVENTION
The present invention addresses the problems described above. It is thus an object of the present invention to provide a liquid-crystal display element having improved contrast characteristics of in the vertical and horizontal directions with respect to the direction of the visual-field angle of the eyeballs of an image viewer wherein changes in contrast in the vertical direction are improved in particular.
In order to achieve the object described above, according to one aspect of the present invention, there is provided an optical visualizing apparatus comprising:
a liquid-crystal display element having contrast characteristics of a visual-field angle in the horizontal and vertical directions;
a half mirror for splitting an optical path from the liquid-crystal display element; and
a concave mirror for enlarging and viewing an image based on the optical path from the half mirror as a virtual image,
wherein the contrast characteristics of the visual-field angle in the horizontal and vertical directions are changed in accordance with an electrical signal amplified to create a sawtooth waveform and generated in synchronization with a vertical synchronization signal of an input video signal.
According to another aspect of the present invention, there is provided an optical visualizing apparatus comprising:
a liquid-crystal display element having a contrast characteristic of a visual-field angle in the horizontal and vertical directions;
a half mirror for splitting an optical path from the liquid-crystal display element; and
a concave mirror for enlarging and viewing an image based on the optical path from the half mirror as an virtual image,
wherein the liquid-crystal display element makes the contrast characteristic of the visual-field angle in the horizontal direction fixed but changes the contrast characteristic of the visual-field angle in the vertical direction.
In this way, by improving the contrast characteristic of the visual-field angle in the vertical direction in w
Sawachika Isao
Yagi Tetsuya
Kananen Ronald P.
Nguyen Dung
Rader Fishman & Grauer
Sikes William L.
Sony Corporation
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