U.S. patent application number 12/340005 was filed with the patent office on 2018-08-09 for stereoscopic 3d display device.
This patent application is currently assigned to LG Display Co., Ltd.. The applicant listed for this patent is Sung-Min Jung, Hoon Kang, Seung-Chul Lee. Invention is credited to Sung-Min Jung, Hoon Kang, Seung-Chul Lee.
Application Number | 20180224664 12/340005 |
Document ID | / |
Family ID | 40230740 |
Filed Date | 2018-08-09 |
United States Patent
Application |
20180224664 |
Kind Code |
A9 |
Lee; Seung-Chul ; et
al. |
August 9, 2018 |
STEREOSCOPIC 3D DISPLAY DEVICE
Abstract
A stereoscopic image display device including: a main display
panel operable to alternately display a left image and a right
image; an auxiliary display panel including first and second
substrates having a pixel part corresponding to that of the main
display panel and a sub-liquid crystal layer formed between the
first and second substrates, and positioned in front of the main
display panel to change polarization information of an incident
left or right image; a plurality of first electrodes patterned on
the first substrate along the rows of pixels formed on the main
display panel; a second electrode formed on a front surface of the
pixel part of the second substrate; and a light source to supply
light to the rear side of the main display panel. Both a 3D
vertical viewing angle and 2D luminance in a glass-type 2D display
can be improved.
Inventors: |
Lee; Seung-Chul; (Paju Si,
KR) ; Kang; Hoon; (Namyangju Si, KR) ; Jung;
Sung-Min; (Incheon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lee; Seung-Chul
Kang; Hoon
Jung; Sung-Min |
Paju Si
Namyangju Si
Incheon |
|
KR
KR
KR |
|
|
Assignee: |
LG Display Co., Ltd.
Seoul
KR
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20100007716 A1 |
January 14, 2010 |
|
|
Family ID: |
40230740 |
Appl. No.: |
12/340005 |
Filed: |
December 19, 2008 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 13/341 20180501;
H04N 13/337 20180501; G02B 30/25 20200101 |
International
Class: |
G02B 27/26 20060101
G02B027/26; H04N 13/337 20180101 H04N013/337 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2008 |
KR |
10-2008-0066695 |
Claims
1. A stereoscopic image display device comprising: a main display
panel operable to alternately display a left image and a right
image; an auxiliary display panel that changes polarization
information of an incident left or right image, including first and
second substrates having a pixel part corresponding to that of the
main display panel and a sub-liquid crystal layer formed between
the first and second substrates, and positioned in front of the
main display panel; a plurality of first electrodes patterned on
the first substrate along the rows of pixels formed on the main
display panel; a second electrode on a front surface of the pixel
part of the second substrate; and a light source that supplies
light to the rear side of the main display panel.
2. The device of claim 1, wherein the second electrode is on the
entire surface of the pixel part of the second substrate without
any patterns.
3. The device of claim 1, wherein the first and second electrodes
are made of a transparent conductive material such as ITO.
4. The device of claim 1, wherein the height of the first electrode
corresponds to the height of a single pixel of the main display
panel, and the width of the first electrode corresponds to `n`
(n=1,2, . . . ) times the width of the pixel part.
5. The device of claim 1, wherein the auxiliary display panel is
driven in synchronization with one of the left and right
images.
6. The device of claim 1, wherein the sub-liquid crystal layer
includes a plurality of liquid crystal molecules, and when the
auxiliary display panel is driven, the liquid crystal molecules are
arranged to be substantially perpendicular to the first and second
substrates, and when the auxiliary display panel is not driven, the
liquid crystal molecules are arranged in a twisted nematic
structure.
7. The device of claim 1, wherein the sub-liquid crystal layer
includes a plurality of liquid crystal molecules, and when the
auxiliary display panel is driven, the liquid crystal molecules are
arranged to be substantially perpendicular to the first and second
substrates, and when the auxiliary display panel is not driven, the
liquid crystal molecules are arranged to be substantially parallel
to the first and second substrates.
8. The device of claim 1, wherein a polarization axis of the left
or right image made incident to the auxiliary display panel and a
rubbing direction of the auxiliary display panel are positioned
substantially at 45.degree..
9. The device of claim 4, wherein when the auxiliary display panel
is not driven, a polarization axis of the left or right image that
has passed through the auxiliary display panel is substantially
perpendicular to a polarization axis of the left or right image
made incident to the auxiliary display panel.
10. The device of claim 1, wherein the main display panel is driven
at 120 Hz or higher.
11. The device of claim 1, wherein the main display panel
comprises: an array substrate; a color filter substrate disposed to
face the array substrate; a main liquid crystal layer positioned
between the array substrate and the color filter substrate; a first
polarizer attached on an outer surface of the array substrate; and
a second polarizer attached on an outer surface of the color filter
substrate.
12. The device of claim 1, further comprising: a .lamda./4
retardation layer formed on the first substrate of the auxiliary
display panel that changes a linearly polarized left or right image
made incident to the auxiliary display panel into a left circularly
polarized (or right circularly polarized) state.
13. The device of claim 12, wherein the .lamda./4 retardation layer
in formed in an in-cell form on an upper surface of the first
substrate of the auxiliary display panel together with the first
substrate.
14. The device of claim 12, wherein the .lamda./4 retardation layer
is attached in a form of a film on a lower surface of the first
substrate of the auxiliary display panel.
Description
BACKGROUND
[0001] 1. Field of the Disclosure
[0002] The present invention relates to a stereoscopic 3D
(Three-Dimensional) display device and, more particularly, to a
stereoscopic 3D display device allowing viewing of a stereoscopic
image by using polarization glasses.
[0003] 2. Description of the Related Art
[0004] A 3D display may be briefly defined as `the sum of a system
artificially reproducing a 3D screen image`.
[0005] Here, the system includes a software technique for
displaying an image three-dimensionally and hardware implementing
contents created by the software technique as an actual 3D image.
The reason of including the software region is because, for 3D
display hardware, contents created by a software-wise method are
separately required for each stereoscopic implementing method.
[0006] Also, a virtual 3D display is literally the sum of a system
providing a virtual 3D effect with planar display hardware by
using, among various factors providing stereoscopy, binocular
disparity, caused by the fact that users' eyes are separated from
each other by about 65 mm in a horizontal direction. In other
words, when a user looks at an object, the user's eyes see slightly
different images (strictly speaking, sharing left and right spatial
information) of the object because of the binocular disparity, and
when the two images are transferred to the brain of the user via
the retina, the brain accurately combines them to allow the user to
feel the 3D effect of the image. Based on this, a 2D display device
simultaneously displays the two left and right images and sends
them to the user's respective eyes to create virtual stereoscopy,
which is the so-called virtual 3D display.
[0007] In such a virtual 3D display hardware device, in order to
display images of two channels on the single screen, in most cases,
the channels are outputted by changing lines, namely, one line at a
time, in one of horizontal or vertical directions on the single
screen. When the images of the two channels are simultaneously
outputted on the single display device, due to the hardware
structure, in case of an autostereoscopic scheme, the right image
is transferred to the right eye and the left image is only
transferred to the left eye In case of the method using (wearing)
glasses, special glasses suitable to each method is used such that
the left eye is covered so that it cannot see the right screen
image and the right eye is covered so that it cannot see the left
screen image.
[0008] Although the channels are outputted by changing lines one by
one, because the thickness of the lines and the interval between
lines are about 0.1 mm to 0.5 mm, too fine for the user's eyes to
recognize, the user's eyes recognize the two images of the
respective channels as a single screen. However, compared with the
case where 2D screen is used, the amount of information reaching
the user's eyes from the screen of the same size is halved per
channel, so the resolution and a sensible brightness are reduced to
about one half as well.
[0009] The stereoscopic image display method includes a method for
wearing glasses and an autostereoscopic method in which glasses are
not used.
[0010] A typical method that does not use glasses (in which the
user does not wear glasses) includes a lenticular method and a
parallax barrier method.
[0011] In the lenticular method, a lenticular lens plate on which
cylindrical lenses are vertically arranged is installed in front of
a display panel.
[0012] In the parallax barrier method, two left and right screens
are alternately disposed at certain interval therebetween behind a
slit-shaped opening called a parallax barrier, so that the two left
and right images can be separately viewed through the opening at a
particular point of time. That is, the parallax barrier method
simply discriminates the left and right channels by blocking them
with a wall, rather than using an optical technique such as a
polarization method.
[0013] FIG. 1 is a schematic view showing the configuration of a
stereoscopic image display device employing parallelax barrier
method according to the related art, in which a stereoscopic image
and a planar image are selectively switched.
[0014] As shown, a stereoscopic image display device 1 includes a
backlight light source 40, a display panel 30, and a switching
panel 20.
[0015] The switching panel 20 includes an opaque slit portion and a
transparent slit portion, which have a certain width and are
alternately disposed. When an electrical signal is applied to the
switching panel, the opaque slit portion becomes opaque and the
transparent slit portion becomes transparent.
[0016] An observer 10 looks at the display panel 30 via the
transparent slit portion of the switching panel 20, and in this
case, the observer's left eye (L) sees a left eye region Lp of the
display panel 30 via the transparent slit portion of the switching
panel 20 and the observer's right eye (R) sees a right eye region
Rp of the display panel 30 via the transparent slit portion.
[0017] In this manner, the observer's left eye (L) and right eye
(R) see different regions of the display panel 30, and at this
time, the display panel 30 displays images corresponding to the
left and right eyes on the left eye region Lp and the right eye
region Rp. Accordingly, the observer can feel a three-dimensional
effect according to the binocular disparity (binocular
parallax).
[0018] However, because the parallax barrier method discriminates
images with the structure of simply covering the visual field, not
using any particular optical technique, if the observer is not at
the position intended initially at the designing, the observer's
eyes are not within the corresponding range and the images are seen
broken. The restricted positions include left/right positions and
front/rear positions.
[0019] In addition, in the 2D mode, the barrier degrades the
brightness of screen image, and a certain user (observer) may feel
that the barrier is unpleasant to his eyes.
BRIEF SUMMARY
[0020] A stereoscopic image display device includes a main display
panel operable to alternately display a left image and a right
image; an auxiliary display panel including first and second
substrates having a pixel part corresponding to that of the main
display panel and a sub-liquid crystal layer formed between the
first and second substrates, and positioned in front of the main
display panel to change polarization information of an incident
left or right image; a plurality of first electrodes patterned on
the first substrate along the rows of pixels formed on the main
display panel; a second electrode formed on a front surface of the
pixel part of the second substrate; and a light source to supply
light to the rear side of the main display panel.
[0021] The foregoing and other features and aspects of the present
invention will become more apparent from the following detailed
description of the present invention when taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a view schematically showing the configuration of
a stereoscopic image display device according to a related art
parallax barrier method;
[0023] FIG. 2 is a sectional view showing the structure of a
stereoscopic image display device according to a first embodiment
of the present invention;
[0024] FIGS. 3A and 3B are plan views schematically showing the
structure of lower and upper substrates of an auxiliary display
panel of the stereoscopic image display device;
[0025] FIGS. 4A and 4B are sectional views taken along lines A-A'
and B-B' of the upper substrate of the auxiliary display panel in
FIG. 3A;
[0026] FIG. 5 is a view for explaining operational characteristics
of an auxiliary display panel having a sub-liquid crystal layer of
a TN mode;
[0027] FIG. 6 is a view for explaining operational characteristics
of an auxiliary display panel having a homogenous sub-liquid
crystal layer;
[0028] FIG. 7 is a view showing a rubbing direction of the
auxiliary display panel having the homogenous sub-liquid crystal
layer;
[0029] FIG. 8 is a sectional view schematically showing the
structure of a stereoscopic image display device according to a
second embodiment of the present invention;
[0030] FIG. 9 is a view for explaining operational characteristics
of an auxiliary display panel of the stereoscopic image display
device in FIG. 8;
[0031] FIG. 10 is a sectional view schematically showing the
structure of a stereoscopic image display device according to a
third embodiment of the present invention;
[0032] FIG. 11 is a view for explaining operational characteristics
of an auxiliary display panel of the stereoscopic image display
device in FIG. 10; and
[0033] FIG. 12 is an exemplary view for explaining a driving
principle of the stereoscopic image display device according to the
present invention.
DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED
EMBODIMENTS
[0034] As the main stream of display devices is shifted from CRTs
(Cathode Ray Tubes) to flat panel displays such as LCDs (Liquid
Crystal Displays), research and the practical use of a glass type
virtual 3D display scheme are shifting from the scheme optimized
for the CRTs to a scheme optimized for the flat panel displays.
[0035] A polarization method is to separate images of left and
right eyes by using a light blocking effect according to
combination of perpendicular polarization elements. In a
polarization mode display device, when two images are
simultaneously outputted, right and left images are displayed on
the entire screen by turns one line at a time. The two
simultaneously outputted images are seen by the observer's eyes, so
the images should be filtered through polarization glasses. Namely,
the images are filtered such that the left image is not seen to the
right eye and the right image is not seen to the left eye through
the glasses.
[0036] A polarization filter used in the polarization method refers
to a filter that allows light vibrating in a particular direction,
among light diffused in various directions, to pass therethrough
and absolve light vibrating in the other remaining directions.
[0037] The process in which the respective images are seen to the
both eyes by using the polarization filter in the polarization
method will be described as follows.
[0038] First, in the display device, the left and right images are
allowed to pass through the polarization filter in different
directions so as to turn into light vibrating in different
directions. Thereafter, when the light is filtered through the
polarization glasses, each side of the glasses has polarization
filters of the same directions as those of the respective left and
right images so as to prevent the opposite images from being seen.
For example, if a left image is polarized to include only light
vibrating at -45.degree. and a right image is polarized to include
only light vibrating at 45.degree. and the left polarization glass
is made to include -45.degree. polarization filter and the right
polarization glass is made to include 45.degree. polarization
filter, the left image including light vibrating at -45.degree.
would not pass through the right glass of 45.degree., and vice
versa, resulting in that only one image suitable for each eye is
recognized.
[0039] The polarization method may have a considerably wide viewing
angle in horizontal or vertical direction according to the
direction in which images of two channels are divided. In general,
in consideration of situations where many people watch the screen,
left/right images are divided in a horizontal direction to secure a
left/right (horizontal) viewing angle. The polarization method can
obtain nearly a 180.degree. horizontal viewing angle, so it can be
suitable for a screen where many people are watching at the same
time. In this case, when the horizontal viewing angle is secured,
an up/down (vertical) viewing angle is compromised, and in this
case a pseudoscopic phenomenon, in which the polarization states of
the left image and the right image are interchanged in the
direction of the vertical viewing angle so that the left-eye image
is seen to the right eye and the right-eye image is seen to the
left eye, occurs.
[0040] FIG. 2 is a sectional view schematically showing the
structure of a stereoscopic image display device according to a
first embodiment of the present invention.
[0041] As shown, the stereoscopic image display device 100
according to the first embodiment of the present invention includes
a main display panel 110 that displays a left image and a right
image in turns, an auxiliary display panel 120 positioned in front
of the main display panel 110, a light source 130 that supplies
light to the rear side of the main display panel 110, and
polarization glasses 140 that selectively transmit a left or right
image outputted from the auxiliary display panel 120 according to a
polarization state to implement a stereoscopic image.
[0042] The main display panel 110 displays a left image to be made
incident to the left eye of a viewer (user) and a right image to be
made incident to the right eye of the viewer in turns in order to
implement a stereoscopic image.
[0043] The main display panel 110 according to the first embodiment
of the present invention may be a liquid crystal panel. If a liquid
crystal panel according to the related art is driven at 60 Hz, the
main display panel 110 is preferably driven at 120 Hz. This aims to
display the left and right images in turns while securing a
stereoscopic picture quality of above a certain level.
[0044] The main display panel 110 has the same structure as the
liquid crystal panel according to the related art, except for a
driving principle to be hereinafter described.
[0045] Where the main display panel 110 is a liquid crystal panel,
the main display panel 110 includes a thin film transistor (TFT)
array substrate 111, a color filter substrate 112 disposed facing
the array substrate 111, a main liquid crystal layer 113 positioned
between the array substrate 111 and the color filter substrate 112,
first and second polarizers 114 and 115 attached on outer surfaces
of the array substrate 111 and the color filter substrate 112.
Here, the first and second polarizers 114 and 115 are disposed such
that their polarization axes are substantially perpendicular to
each other.
[0046] Meanwhile, in addition to a liquid crystal panel, the main
display may be a flat display panel such as a plasma display panel
(PDP), an organic light emitting diode (OLED), or the like.
[0047] As described above, the auxiliary display panel 120
according to the first embodiment of the present invention is
positioned in front of the main display panel 110. The auxiliary
display panel 120 is driven in synchronization with one of left and
right images of the main display panel 110 and serves to change
polarization information of incident left or right image. In this
case, the auxiliary display panel includes a first substrate 121
and a second substrate 122 that face each other, and a sub-liquid
crystal layer 123 positioned between the first and second
substrates 121 and 122.
[0048] First and second electrodes (not shown) and an alignment
film (not shown) for controlling an arrangement of the sub-liquid
crystal layer 123 are provided on the first and second substrates
121 and 122.
[0049] FIGS. 3A and 3B are plan views schematically showing the
structure of lower and upper substrates of the auxiliary display
panel of the stereoscopic image display device. FIGS. 4A and 4B are
sectional views taken along lines A-A' and B-B' of the upper
substrate of the auxiliary display panel in FIG. 3A.
[0050] First, as shown in FIG. 3A (see, FIGS. 4A and 4B), first
electrodes 128 made of a transparent conductive material such as
indium tin oxide (ITO) are patterned along lines (rows) of pixels
of the main display panel on the first substrate 121, the lower
substrate of the auxiliary display panel 120.
[0051] The height (h) of the first electrode 128 corresponds to the
height of a single pixel of the main display panel, and the width
(w) of the first electrode 128 corresponds to `n` (n=1, 2, . . . )
times the width of a pixel part 125.
[0052] Reference numerals 126 and 127 denote a driver IC
(Integrated Circuit) for applying signals and signal wirings for
connecting the driver IC and the first electrodes 128. The signal
wirings 127 are made of a conductive material such as copper or
molybdenum.
[0053] As shown in FIG. 3B (see, FIGS. 4A and 4B), a second
electrode 128 made of the same material as the first electrode 128
is wholly formed, without any patterns, on the entire surface of
the pixel part 125 of the second substrate 122, the upper substrate
of the auxiliary display panel 120.
[0054] Alignment films 124a and 124b for aligning the sub-liquid
crystal layer 123 are positioned on the facing surfaces of the
first and second substrates 121 and 122, respectively.
[0055] The auxiliary display panel 120 may include different types
of sub-liquid crystal layers 123.
[0056] FIG. 5 is a view for explaining operational characteristics
of the auxiliary display panel having a sub-liquid crystal layer of
a TN mode.
[0057] As illustrated, when the auxiliary display panel 120 is
turned off, a plurality of liquid crystal molecules 123a
constituting the sub-liquid crystal layer 123 are twisted at
90.degree. (TN structure) or 240.degree. (STN structure) and
arranged between the first and second substrates 121 and 122 along
a rubbing direction of the alignment films (not shown) of the first
and second substrates 121 and 122. When the auxiliary display panel
120 is turned on, the liquid crystal molecules 123a are vertically
arranged between the first and second substrates 121 and 122 due to
an electric field formed between the first and second substrates
121 and 122.
[0058] Accordingly, if the auxiliary display panel 120 is in an OFF
state, when the left or right image passes the auxiliary display
panel 120, their polarization axis is rotated by 90.degree..
Namely, if the auxiliary display panel 120 is not driven, the
polarization axis of the left or right image which has passed
through the auxiliary display panel 120 is changed to be
substantially perpendicular to the polarization axis of the left or
right image made incident to the auxiliary display panel 120.
[0059] The reason of the change in the polarization axis of the
left or right image is because of a refractive index anisotropy
(.DELTA.n) of the sub-liquid crystal layer 123. The longer axis and
the shorter axis of the liquid crystal molecules 123a have
different refractive indexes, which is called a refractive index
anisotropy (.DELTA.n). The refractive index anisotropy (.DELTA.n)
is defined by a value obtained by subtracting a refractive index of
the shorter axis direction from that of the longer axis direction.
As shown, the liquid crystal molecules 123a are arranged after
being twisted by 90.degree. or 240.degree., and incident light
proceeds according to the refractive index anisotropy (.DELTA.n) of
the sub-liquid crystal layer 123, changing the polarization state
or polarization information of the incident light as described
above.
[0060] When the auxiliary display panel 120 is in an ON state, the
polarization axis of the left or right image that has passed
through the auxiliary display panel 120 does not change. This is
because as the liquid crystal molecules are arranged to be
perpendicular to the first and second substrates 121 and 122, light
passes through the sub-liquid crystal layer 123 only with the
refractive index in the shorter axis direction, not the refractive
index anisotropy (.DELTA.n). Therefore, the polarization state or
polarization information is not changed.
[0061] FIG. 6 is a view for explaining operational characteristics
of an auxiliary display panel having a homogenous sub-liquid
crystal layer. FIG. 7 is a view showing a rubbing direction of the
auxiliary display panel having the homogenous sub-liquid crystal
layer.
[0062] As illustrated, if the auxiliary display panel 120 includes
a homogenous sub-liquid crystal layer 123', when the auxiliary
display panel 120 is turned off, the liquid crystal molecules 123a'
are arranged to be substantially parallel to the first and second
substrates 121 and 122. A rubbing direction of the auxiliary
display panel 120 is substantially at 45.degree. with respect to
the polarization axis of the left or right image made incident to
the auxiliary display panel 120.
[0063] Thus, if the auxiliary display panel 120 is not driven, the
liquid crystal molecules 123a' are arranged to be parallel to the
first and second substrates 121 and 122 in a direction inclined at
45.degree. from the polarization axis of the incident left or right
image. When the auxiliary display panel 120 is turned on, the
liquid crystal molecules 123a' are arranged to be substantially
perpendicular to the first and second substrates 121 and 122.
[0064] In this case, where the sub-liquid crystal layer 123' has a
homogenous arrangement, the sub-liquid crystal layer 123' may
preferably satisfy an equation .DELTA.n.times.d=.lamda./2. Here,
`d` is a cell gap of the sub-liquid crystal layer 123', .DELTA.n
indicates a refractive index anisotropy of the sub-liquid crystal
layer 123', and .lamda. indicates wavelength of light that has
passed through the sub-liquid crystal layer 123'.
[0065] The reason for the sub-liquid crystal layer 123' preferably
satisfying the equation .DELTA.n.times.d=.lamda./2 is to change the
phase of incident left or right image by 180.degree.. Accordingly,
as shown in FIG. 6, when the auxiliary display panel 120 is in an
OFF state, the left or right image that passes through the
auxiliary display panel 120 has a polarization axis substantially
perpendicular to that of the left or right image made incident on
the auxiliary display panel 120, and is outputted to outside the
auxiliary display panel 120.
[0066] Meanwhile, when the auxiliary display panel 120 is in an ON
state, the polarization axis of the left or right image that has
passed through the auxiliary display panel 120 is not changed. This
is because as the liquid crystal molecules 123a' are arranged to be
perpendicular to the first and second substrates 121 and 122, light
passes through the sub-liquid crystal layer 123' only with the
refractive index in the shorter axis direction, not the refractive
index anisotropy (.DELTA.n). Therefore, the polarization state or
polarization information is not changed.
[0067] As described above, in the first embodiment of the present
invention, the first and second electrodes are formed on the first
and second substrates of the auxiliary display panel such that they
correspond to the rows of the pixels and the pixel part of the main
display panel, and driving is performed at 120 Hz to apply signals
to the corresponding first and second electrodes of the auxiliary
display panel according to a signal addressing of the main display
panel to change the polarization state according to left or right
image displayed on each subframe, thereby improving both the 3D
vertical viewing angle and the 2D luminance.
[0068] FIG. 8 is a sectional view schematically showing the
structure of a stereoscopic image display device according to a
second embodiment of the present invention, in which the structure
is substantially the same as that of the stereoscopic image display
device according to the first embodiment of the present invention
except that a .lamda./4 retardation layer is inserted to the lower
substrate of the auxiliary display panel.
[0069] As illustrated, the stereoscopic image display device 200
according to the second embodiment of the present invention
includes a main display panel 210 that displays a left image and a
right image in turns, an auxiliary display panel 220 positioned in
front of the main display panel 210, a light source 230 that
supplies light to the rear side of the main display panel 210, and
polarization glasses 240 that selectively transmit a left or right
image outputted from the auxiliary display panel 220 according to a
polarization state to implement a stereoscopic image.
[0070] The light source 230 is positioned at a rear side of the
main display panel 210 and emits light to the main display panel
210. Here, the light source 230 may be a direct type light source
or an edge type light source. As the light source 230, a cold
cathode fluorescent lamp (CCFL) may be used, and an external
electrode fluorescent lamp (EEFL) that has characteristics of high
luminance, low cost and low power consumption and that can drive a
light source by using a single inverter may be also used. And a
light emitting diode (LED) having good luminance and color
reproduction can be also used as a light source.
[0071] The polarization glasses 240 are to view a stereoscopic
image by dividing left and right images according to a polarization
state of the left or right image outputted from the auxiliary
display panel 220. The polarization glasses 240 include a left
polarization lens and a right polarization lens, and a polarization
axis of the left polarization lens is substantially perpendicular
to that of the right polarization lens. The polarization axis of
the left polarization lens is the same as the polarization axis of
one of the left and right images outputted from the auxiliary
display panel 220, and the polarization axis of the right
polarization lens is the same as the polarization axis of another
of the left and right images outputted from the auxiliary display
panel 220. Accordingly, the left and right images outputted from
the auxiliary display panel 220 are discriminated according to the
polarization state of the left and right images by the polarization
glasses 240 and made incident to the viewer's (user's) left and
right eyes, and thus the user can view a stereoscopic image.
[0072] In order to implement the stereoscopic image, the main
display panel 210 alternately displays the left image to be made
incident to the user's left eye and the right image to be made
incident to the user's right eye.
[0073] The main display panel 210 according to the second
embodiment of the present invention may be the same liquid crystal
panel as that of the first embodiment of the present invention, and
when the liquid crystal panel according to related art is driven at
60 Hz, the main display panel 210 may be driven at 120 Hz.
[0074] The main display panel 210 includes a thin film transistor
(TFT) array substrate 211, a color filter substrate 212 disposed to
face the array substrate 211, a main liquid crystal layer 213
positioned between the array substrate 211 and the color filter
substrate 212, first and second polarizers 214 and 215 attached on
outer surfaces of the array substrate 211 and the color filter
substrate 212. Here, the first and second polarizers 214 and 215
are disposed such that their polarization axes are substantially
perpendicular to each other.
[0075] As described above, the auxiliary display panel 220
according to the second embodiment of the present invention is
positioned in front of the main display panel 210. The auxiliary
display panel 220 is driven in synchronization with one of left and
right images of the main display panel 210 and serves to change
polarization information of incident left or right image. In this
case, the auxiliary display panel includes a first substrate 221
and a second substrate 222 that face each other, and a sub-liquid
crystal layer 223 positioned between the first and second
substrates 221 and 222.
[0076] First and second electrodes (not shown) and an alignment
film (not shown) for controlling an arrangement of the sub-liquid
crystal layer 223 are provided on the first and second substrates
221 and 222.
[0077] The first electrodes made of a transparent conductive
material such as indium tin oxide (ITO) are patterned along lines
(rows) of pixels of the main display panel on the first substrate
221, the lower substrate of the auxiliary display panel 220. The
height of the first electrode corresponds to the height of a single
pixel of the main display panel, and the width of the first
electrode corresponds to `n` (n=1, 2, . . . ) times the width of a
pixel part.
[0078] The second electrode made of the same material as the first
electrode is wholly formed, without any patterns, on the entire
surface of the pixel part of the second substrate 222, the upper
substrate of the auxiliary display panel 220.
[0079] Alignment films for aligning the sub-liquid crystal layer
223 are positioned on the facing surfaces of the first and second
substrates 221 and 222, respectively.
[0080] The stereoscopic image display device according to the
second embodiment of the present invention includes a .lamda./4
retardation layer 250 formed on an upper surface of the first
substrate 221 of the auxiliary display panel 220 to change a linear
polarization made incident from the main display panel 210 to a
circular polarization.
[0081] The .lamda./4 retardation layer 250 according to the second
embodiment of the present invention is formed in an in-cell form
together with the first substrate 221.
[0082] FIG. 9 is a view for explaining operational characteristics
of the auxiliary display panel of the stereoscopic image display
device in FIG. 8, in which the auxiliary display panel has a
homogenous sub-liquid crystal layer.
[0083] As illustrated, when the auxiliary display panel 220 has the
homogenous sub-liquid crystal layer 223, if the auxiliary display
panel 220 is turned off, liquid crystal molecules 223a are arranged
to be substantially parallel to the first and second substrates 221
and 222. A rubbing direction of the auxiliary display panel 220 and
an optical axis of the .lamda./4 retardation layer 250 are
substantially at 45.degree. with respect to the polarization axis
of the left or right image made incident to the auxiliary display
panel 220.
[0084] Accordingly, if the auxiliary display panel 220 is not
driven, the liquid crystal molecules 223a are arranged to be
parallel to the first and second substrates 221 and 222 in a
45.degree.-inclined direction with respect to the polarization axis
of the incident left or right image. When the auxiliary display
panel 220 is turned on, the liquid crystal molecules 223a are
arranged to be substantially perpendicular to the first and second
substrates 221 and 222.
[0085] In this case, as described above, because the sub-liquid
crystal layer 223 has the homogenous arrangement, the sub-liquid
crystal layer 223 may satisfy an equation
.DELTA.n.times.d=.lamda./2.
[0086] Thus, as shown, if the auxiliary display panel 220 is in an
OFF state, the linearly polarized left or right image made incident
to the auxiliary display panel 220 passes through the first
substrate 221 of the auxiliary display panel 220 so as to be
changed in its state to a left circular polarization (or right
circular polarization), which then passes through the sub-liquid
crystal layer 223. At this time, a left circularly polarized (or
right circularly polarized) left or right image made incident to
the sub-liquid crystal layer 223 passes through the sub-liquid
crystal layer 223 so as to be changed in its state to a right
circular polarization (or left circular polarization), which is
then outputted to outside of the auxiliary display panel 220.
[0087] If the auxiliary display panel 220 is in an ON state, the
left circularly polarized (or right circularly polarized) left or
right image which has passed through the auxiliary display panel
220 is outputted to the outside of the auxiliary display panel 220,
with its polarization state unchanged. This is because as the
liquid crystal molecules 223A are arranged to be perpendicular to
the first and second substrates 221 and 222, light passes through
the sub-liquid crystal layer 223 only with the refractive index in
the shorter axis direction, not the refractive index anisotropy
(.DELTA.n). Therefore, the polarization state or polarization
information is not changed.
[0088] FIG. 10 is a sectional view schematically showing the
structure of a stereoscopic image display device according to a
third embodiment of the present invention, in which the structure
is substantially the same as that of the stereoscopic image display
device according to the second embodiment of the present invention
except that .lamda./4 retardation layer is attached to a rear
surface of the lower substrate of the auxiliary display panel.
[0089] As illustrated, the stereoscopic image display device 300
according to the third embodiment of the present invention includes
a main display panel 310 that displays a left image and a right
image in turns, an auxiliary display panel 320 positioned in front
of the main display panel 310, a light source 330 that supplies
light to the rear side of the main display panel 310, and
polarization glasses 340 that selectively transmit a left or right
image outputted from the auxiliary display panel 320 according to a
polarization state to implement a stereoscopic image.
[0090] The light source 330 is positioned at a rear side of the
main display panel 310 and emits light to the main display panel
310. The polarization glasses 340 include left and right
polarization lenses, and a polarization axis of the left
polarization lens is substantially perpendicular to that of the
right polarization lens. The polarization axis of the left
polarization lens is the same as the polarization axis of one of
the left and right images outputted from the auxiliary display
panel 320, and the polarization axis of the right polarization lens
is the same as the polarization axis of another of the left and
right images outputted from the auxiliary display panel 320.
Accordingly, the left and right images outputted from the auxiliary
display panel 320 are discriminated according to the polarization
state of the left and right images by the polarization glasses 340
and made incident to the viewer's (user's) left and right eyes,
whereby the user can view a stereoscopic image.
[0091] In order to implement the stereoscopic image, the main
display panel 310 alternately displays the left image to be made
incident to the user's left eye and the right image to be made
incident to the user's right eye.
[0092] The main display panel 310 according to the third embodiment
of the present invention may be the same liquid crystal panel as
those in the first and second embodiments of the present invention,
and where the liquid crystal panel according to related art is
driven at 60 Hz, the main display panel 210 may be driven at 120
Hz.
[0093] The main display panel 310 includes a thin film transistor
(TFT) array substrate 311, a color filter substrate 312 disposed to
face the array substrate 311, a main liquid crystal layer 313
positioned between the array substrate 311 and the color filter
substrate 312, first and second polarizers 314 and 315 attached on
outer surfaces of the array substrate 311 and the color filter
substrate 312. Here, the first and second polarizers 314 and 315
are disposed such that their polarization axes are substantially
perpendicular to each other.
[0094] As described above, the auxiliary display panel 320
according to the third embodiment of the present invention is
positioned in front of the main display panel 310. The auxiliary
display panel 320 is driven in synchronization with one of left and
right images of the main display panel 310 and serves to change
polarization information of incident left or right image. In this
case, the auxiliary display panel includes a first substrate 321
and a second substrate 322 that face each other, and a sub-liquid
crystal layer 323 positioned between the first and second
substrates 321 and 322.
[0095] First and second electrodes (not shown) and an alignment
film (not shown) for controlling an arrangement of the sub-liquid
crystal layer 323 are provided on the first and second substrates
321 and 322.
[0096] The first electrodes made of a transparent conductive
material such as indium tin oxide (ITO) are patterned along lines
(rows) of pixels of the main display panel on the first substrate
321, the lower substrate of the auxiliary display panel 320. The
height of the first electrode corresponds to the height of a single
pixel of the main display panel, and the width of the first
electrode corresponds to `n` (n=1, 2, . . . ) times the width of a
pixel part.
[0097] The second electrode made of the same material as the first
electrode is wholly formed without a pattern on the entire surface
of the pixel part of the second substrate 322, the upper substrate
of the auxiliary display panel 320.
[0098] Alignment films for aligning the sub-liquid crystal layer
323 are positioned on the facing surfaces of the first and second
substrates 321 and 322, respectively.
[0099] The stereoscopic image display device according to the third
embodiment of the present invention includes a .lamda./4
retardation layer 350 formed on a lower surface, namely, a rear
surface, of the first substrate 321 of the auxiliary display panel
320 to change a linear polarization made incident from the main
display panel 310 to a circular polarization. In addition, the
.lamda./4 retardation layer 350 according to the third embodiment
of the present invention may be attached in the form of a film on
the rear surface of the first substrate 321.
[0100] FIG. 11 is a view for explaining operational characteristics
of the auxiliary display panel of the stereoscopic image display
device in FIG. 10, in which the auxiliary display panel has a
homogenous sub-liquid crystal layer.
[0101] As illustrated, when the auxiliary display panel 320 has the
homogenous sub-liquid crystal layer 323, if the auxiliary display
panel 320 is turned off, liquid crystal molecules 323a are arranged
to be substantially parallel to the first and second substrates 321
and 322. A rubbing direction of the auxiliary display panel 320 and
an optical axis of the .lamda./4 retardation layer 350 are
substantially at 45.degree. with respect to the polarization axis
of the left or right image made incident to the auxiliary display
panel 320.
[0102] Accordingly, if the auxiliary display panel 320 is not
driven, the liquid crystal molecules 323a are arranged to be
parallel to the first and second substrates 321 and 322 in a
45.degree.-inclined direction with respect to the polarization axis
of the incident left or right image. When the auxiliary display
panel 320 is turned on, the liquid crystal molecules 323a are
arranged to be substantially perpendicular to the first and second
substrates 321 and 322.
[0103] In this case, as described above, because the sub-liquid
crystal layer 223 has the homogenous arrangement, the sub-liquid
crystal layer 323 may satisfy an equation
.DELTA.n.times.d=.lamda./2.
[0104] Thus, as shown, if the auxiliary display panel 320 is in an
OFF state, the linearly polarized left or right image made incident
to the auxiliary display panel 320 passes through the first
substrate 321 of the auxiliary display panel 320 so as to be
changed in its state to a left circular polarization (or right
circular polarization), which then passes through the sub-liquid
crystal layer 323. At this time, a left circularly polarized (or
right circularly polarized) left or right image made incident to
the sub-liquid crystal layer 323 passes through the sub-liquid
crystal layer 323 so as to be changed in its state to a right
circular polarization (or left circular polarization), which is
then outputted to outside of the auxiliary display panel 320.
[0105] If the auxiliary display panel 320 is in an ON state, the
left circularly polarized (or right circularly polarized) left or
right image which has passed through the auxiliary display panel
320 is outputted to the outside of the auxiliary display panel 320,
with its polarization state unchanged. This is because as the
liquid crystal molecules 323A are arranged to be perpendicular to
the first and second substrates 321 and 322, light passes through
the sub-liquid crystal layer 323 only with the refractive index in
the shorter axis direction, not the refractive index anisotropy
(.DELTA.n). Therefore, the polarization state or polarization
information is not changed.
[0106] A driving principle of the stereoscopic image display device
according to the present invention will now be described in detail
with reference to FIG. 12.
[0107] FIG. 12 is an exemplary view for explaining a driving
principle of the stereoscopic image display device according to the
present invention.
[0108] In order to drive the main display panel according to the
present invention, as described above, the TFTs connected to the
gate lines are switched twice as fast and data signals are applied
to the data lines also twice as fast. Here, as for the data
signals, left eye data signals and right eye data signals are
applied to the data lines in turns according to a switching speed
of the TFTs.
[0109] In detail, as shown, the main display panel is driven to
have 60 frames, and each frame includes a first subframe displaying
the left image and a second subframe displaying the right
image.
[0110] In this case, for example, the main display panel may be
driven to display the left image on the first subframe during
0.about.8 seconds, and the main display panel may be driven to
display the right image on the second subframe during 8.about.16
seconds. And, the main display panel may be driven to display the
left image on the first subframe during 16.about.24 seconds, and
the main display panel may be driven to display the right image
during the second subframe during 24.about.32 seconds.
[0111] In this manner, the 60 frames are sequentially driven so
that the main display panel can display the left and right images
in turns to implement a stereoscopic image.
[0112] As mentioned above, each frame includes the first subframe
for displaying the left image and the second subframe for
displaying the right image.
[0113] The auxiliary display panel is provided to be turned on in
synchronization with the left image of the main display panel, and
is not driven, for example, while the main display panel is
displaying the right image. However, the present invention is not
limited thereto, and the auxiliary display panel according to the
present invention may be turned on in synchronization with the
right image and may not be driven while the main display panel is
displaying the left image.
[0114] When the auxiliary display panel is turned on, it outputs
polarization information of the left image outputted from the main
display panel without changing it, and when the auxiliary display
panel is turned off, it changes the polarization information of the
right image outputted from the main display panel, and outputs the
image.
[0115] In detail, light emitted from a light source is made
incident to the auxiliary display panel after passing through the
main display panel. Here, the first and second polarizers of the
main display panel are perpendicular to each other. In this case,
for light directed to the main display panel form the light source,
only a portion of the light in the same polarization state as the
polarization axis of the second polarizer can pass through the main
display panel.
[0116] The auxiliary display panel is maintained in an OFF state
during the first subframe (0.about.8 seconds) of the first frame,
so the polarization state of the light that passes through the
auxiliary display panel is changed. Namely, the auxiliary display
panel rotates the polarization axis of the incident left image by
90.degree. and outputs it. As a result, the polarization state of
the outputted left image is the same as that of light that has
passed through the first polarizer.
[0117] The first embodiment of the present invention in which the
.lamda./4 retardation layer is not applied is shown as an example.
However, the present invention is not limited thereto. That is, the
present invention can also be applicable to the case where light is
outputted with the .lamda./4 retardation layer applied and thus is
polarized to a left circular polarization or a right circular
polarization.
[0118] During the second subframe (8.about.16 seconds) of the first
frame, the auxiliary display panel is turned on, so polarization
state of light that has passed through the auxiliary display panel
is not changed. Namely, the auxiliary display panel outputs the
right image having the same polarization axis as that of the
incident right image.
[0119] Accordingly, because the polarization axis of the left
polarization lens of the polarization glasses is identical to that
of the left image, the outputted left image is made incident to the
left eye of the viewer, and because the polarization axis of the
right image is perpendicular to the polarization axis of the left
polarization lens, the outputted right image is not made incident
to the viewer's left eye. Also, because the polarization axis of
the right polarization lens of the polarization glasses is
identical to that of the right image, the outputted right image is
made incident to the right eye of the viewer, and because the
polarization axis of the left image is perpendicular to the
polarization axis of the right polarization lens, the outputted
right image is not made incident to the viewer's right eye.
[0120] In this manner, the left and right images, each having a
different polarization axis, are formed with a time difference, and
a polarization state of one of the left and right images is changed
and outputted to the viewer. Thus, the viewer can discriminately
view the left and right images according to their polarization
state by using the polarization glasses, and thus, the viewer can
view a stereoscopic image.
[0121] As the present invention may be embodied in several forms
without departing from the characteristics thereof, it should also
be understood that the above-described embodiments are not limited
by any of the details of the foregoing description, unless
otherwise specified, but rather should be construed broadly within
its scope as defined in the appended claims, and therefore all
changes and modifications that fall within the metes and bounds of
the claims, or equivalents of such metes and bounds are therefore
intended to be embraced by the appended claims.
* * * * *