U.S. patent application number 12/631151 was filed with the patent office on 2010-12-02 for stereoscopic image display device.
Invention is credited to Sungmin JUNG.
Application Number | 20100302634 12/631151 |
Document ID | / |
Family ID | 41717052 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100302634 |
Kind Code |
A1 |
JUNG; Sungmin |
December 2, 2010 |
STEREOSCOPIC IMAGE DISPLAY DEVICE
Abstract
This document discloses a stereoscopic image display device. In
the image display device, a display device displays a first image
data and a second image data in a time-dividing manner. A
switchable retarder panel is configured to control light emitted
from the display device and is made of electrically controlled
birefringence (ECB) liquid crystals. Polarization glasses polarize
the light emitted from the switchable retarder panel. The
polarization glasses comprise a left eyeglass comprising a
polarizer having a tilt of 45.degree. about a light absorbing axis,
and a right eyeglass comprising a polarizer having a tilt of
135.degree. about the light absorbing axis.
Inventors: |
JUNG; Sungmin; (Incheon,
KR) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Family ID: |
41717052 |
Appl. No.: |
12/631151 |
Filed: |
December 4, 2009 |
Current U.S.
Class: |
359/465 ;
349/15 |
Current CPC
Class: |
H04N 13/398 20180501;
H04N 13/337 20180501; G02B 30/25 20200101; G09G 3/3614 20130101;
G02B 30/24 20200101; G02B 30/36 20200101; H04N 13/359 20180501;
H04N 13/341 20180501 |
Class at
Publication: |
359/465 ;
349/15 |
International
Class: |
G02B 27/26 20060101
G02B027/26 |
Foreign Application Data
Date |
Code |
Application Number |
May 29, 2009 |
KR |
10-2009-0047680 |
Claims
1. A stereoscopic image display device, comprising: a display
device configured to display a first image data and a second image
data in a time-dividing manner; a switchable retarder panel
configured to convert light emitted from the display device into a
polarized light and made of electrically controlled birefringence
(ECB) liquid crystals; and polarization glasses configured to
polarize the light emitted from the switchable retarder panel,
wherein the polarization glasses comprise: a left eyeglass
comprising a polarizer having a tilt of 45.degree. about a light
absorbing axis; and a right eyeglass comprising a polarizer having
a tilt of 135.degree. about the light absorbing axis.
2. The stereoscopic image display device of claim 1, wherein the
display device emits linearly polarized light.
3. A stereoscopic image display device, comprising: a display
device configured to display a first image data and a second image
data in a time-dividing manner; a switchable retarder panel
configured to control light emitted from the display device and
made of ECB liquid crystals; and polarization glasses configured to
polarize the light emitted from the switchable retarder panel,
wherein the polarization glasses comprise: a left eyeglass
comprising a half-wave plate which faces the switchable retarder
panel and has a tilt of 0.degree. about a slow phase axis, and a
polarizer having a tilt of 135.degree. about a light absorbing
axis; and a right eyeglass comprising a polarizer having a tilt of
135.degree. about the light absorbing axis.
4. The stereoscopic image display device of claim 3, wherein the
display device emits linearly polarized light.
5. The stereoscopic image display device of claim 3, wherein the
right eyeglass further comprises a compensation plate placed on the
polarizer and configured to have a tilt of 0.degree. about the slow
phase axis.
6. A stereoscopic image display device, comprising: a display
device configured to display a first image data and a second image
data in a time-dividing manner; a switchable retarder panel
configured to control light emitted from the display device and
made of ECB liquid crystals; and polarization glasses configured to
polarize the light emitted from the switchable retarder panel,
wherein the polarization glasses comprise: a left eyeglass
comprising a quarter-wave plate having a tilt of 0.degree. about a
slow phase axis and a polarizer having a tilt of 135.degree. about
a light absorbing axis; and a right eyeglass comprising a
quarter-wave plate having a tilt of 0.degree. about the slow phase
axis and a polarizer having a tilt of 45.degree. about the light
absorbing axis.
7. The stereoscopic image display device of claim 6, wherein the
display device emits circularly polarized light.
8. The stereoscopic image display device of claim 6, wherein the
switchable retarder panel comprises a quarter-wave plate attached
in a direction where the light is emitted.
9. The stereoscopic image display device of claim 6, wherein the
right eyeglass further comprises a compensation plate placed
between the quarter-wave plate and the polarizer and configured to
have a tilt of 0.degree. about the slow phase axis.
10. A stereoscopic image display device, comprising: a display
device configured to display a first image data and a second image
data in a time-dividing manner; a switchable retarder panel
configured to control light emitted from the display device and
made of ECB liquid crystals; and polarization glasses configured to
polarize the light emitted from the switchable retarder panel,
wherein the polarization glasses comprise: a left eyeglass
comprising a quarter-wave plate having a tilt of 0.degree. about a
slow phase axis and a polarizer having a tilt of 135.degree. about
a light absorbing axis; and a right eyeglass comprising a
quarter-wave plate having a tilt of 90.degree. about the slow phase
axis and a polarizer having a tilt of 135.degree. about the light
absorbing axis.
11. The stereoscopic image display device of claim 10, wherein the
display device emits circularly polarized light.
12. The stereoscopic image display device of claim 10, wherein a
quarter-wave plate is attached to the switchable retarder panel to
face the polarization glasses in a direction where the light is
emitted.
13. The stereoscopic image display device of claim 10, wherein the
right eyeglass further comprises a compensation plate placed
between the quarter-wave plate and the polarizer and configured to
have a tilt of 0.degree. about the slow phase axis.
14. A stereoscopic image display device, comprising: a display
device configured to display a first image data and a second image
data in a time-dividing manner; a switchable retarder panel
configured to control light emitted from the display device and
made of ECB liquid crystals; and polarization glasses configured to
polarize the light emitted from the switchable retarder panel,
wherein the polarization glasses comprise: a left eyeglass
comprising a quarter-wave plate having a tilt of 90.degree. about a
slow phase axis and a polarizer having a tilt of 45.degree. about a
light absorbing axis; and a right eyeglass comprising a
quarter-wave plate having a tilt of 90.degree. about the slow phase
axis and a polarizer having a tilt of 135.degree. about the light
absorbing axis.
15. The stereoscopic image display device of claim 14, wherein the
display device emits circularly polarized light.
16. The stereoscopic image display device of claim 14, wherein a
quarter-wave plate is attached to the switchable retarder panel to
face the polarization glasses in a direction where the light is
emitted.
17. The stereoscopic image display device of claim 14, wherein the
right eyeglass further comprises a compensation plate placed
between the quarter-wave plate and the polarizer and configured to
have a tilt of 0.degree. about the slow phase axis.
18. A stereoscopic image display device, comprising: a display
device configured to display a first image data and a second image
data in a time-dividing manner; a switchable retarder panel
configured to control light emitted from the display device and
made of ECB liquid crystals; and polarization glasses configured to
polarize the light emitted from the switchable retarder panel,
wherein the polarization glasses comprise: a left eyeglass
comprising a quarter-wave plate having a tilt of 90.degree. about a
slow phase axis, a half-wave plate having a tilt of 0.degree. about
the slow phase axis, and a polarizer having a tilt of 135.degree.
about a light absorbing axis; and a right eyeglass comprising a
quarter-wave plate having a tilt of 90.degree. about the slow phase
axis and a polarizer having a tilt of 135.degree. about the light
absorbing axis.
19. The stereoscopic image display device of claim 18, wherein the
display device emits circularly polarized light.
20. The stereoscopic image display device of claim 18, wherein a
quarter-wave plate is attached to the switchable retarder panel to
face the polarization glasses in a direction where the light is
emitted.
21. The stereoscopic image display device of claim 18, wherein the
right eyeglass further comprises a compensation plate placed
between the quarter-wave plate and the polarizer and configured to
have a tilt of 0.degree. about the slow phase axis.
22. The stereoscopic image display device of claim 18, wherein the
left eyeglass further comprises a half-wave plate placed between
the quarter-wave plate and the polarizer and configured to have a
tilt of 0.degree. about the slow phase axis.
Description
[0001] This application claims the benefit of Korean Patent
Application No. 10-2009-0047680 filed on May 29, 2009, which is
hereby incorporated by reference.
BACKGROUND
[0002] 1. Field
[0003] This document relates to a stereoscopic image display
device.
[0004] 2. Related Art
[0005] Techniques for stereoscopic image display devices are
classified into a stereoscopic technique and an autostereoscopic
technique.
[0006] The stereoscopic technique uses parallax images of the left
and right eyes having a high three-dimensional effect and comprises
a stereoscopic method and an autostereoscopic method both of which
are being put to practical use. The stereoscopic method is used to
display the left and right parallax images on a direct-view display
device or a projector in a time-division manner or by changing the
polarization directions of the left and right parallax images and
to implement a stereoscopic image using the polarization glasses or
the liquid crystal shutter glasses. In the autostereoscopic method,
in general, a polarizing plate, such as a parallax barrier for
separating the optical axes of the left and right parallax images,
is placed in front or at the rear of a display screen.
[0007] In the stereoscopic method, a switchable retarder panel for
converting the light which is incident on the polarization glasses
into a polarized light, can be placed over the display device. The
stereoscopic method is used to alternately display a left-eye image
and a right-eye image on the display device and to convert the
light which is incident on the polarization glasses into a
polarized light, using the switchable retarder panel. Accordingly,
the stereoscopic method can implement a stereoscopic image without
a reduction in resolution by time-dividing the left-eye image and
the right-eye image. A conventional 3-D image display device using
the stereoscopic method is, however, problematic in that it has
residual retardation when converting the emitted light to a
polarized light using the switchable retarder panel. Accordingly,
there is a need for improvements of the conventional 3-D image
display device because such residual retardation causes leakage of
light in one of the polarization glasses.
SUMMARY
[0008] An aspect of this document is to provide a stereoscopic
image display device, comprising a display device configured to
display a first image data and a second image data in a
time-dividing manner, a switchable retarder panel configured to
control light emitted from the display device and made of
electrically controlled birefringence (ECB) liquid crystals, and
polarization glasses configured to polarize the light emitted from
the switchable retarder panel. The polarization glasses comprise a
left eyeglass comprising a polarizer having a tilt of 45.degree.
about a light absorbing axis, and a right eyeglass comprising a
polarizer having a tilt of 135.degree. about the light absorbing
axis.
[0009] Another aspect of this document is to provide a stereoscopic
image display device, comprising a display device configured to
display a first image data and a second image data in a
time-dividing manner, a switchable retarder panel configured to
control light emitted from the display device and made of ECB
liquid crystals, and polarization glasses configured to polarize
the light emitted from the switchable retarder panel. The
polarization glasses comprise a left eyeglass comprising a
half-wave plate having a tilt of 0.degree. about a slow phase axis
and a polarizer having a tilt of 135.degree. about a light
absorbing axis, and a right eyeglass comprising a polarizer having
a tilt of 135.degree. about the light absorbing axis.
[0010] Yet another aspect of this document is to provide a
stereoscopic image display device, comprising a display device
configured to display a first image data and a second image data in
a time-dividing manner, a switchable retarder panel configured to
control light emitted from the display device and made of ECB
liquid crystals, and polarization glasses configured to polarize
the light emitted from the switchable retarder panel. The
polarization glasses comprise a left eyeglass comprising a
quarter-wave plate having a tilt of 0.degree. about a slow phase
axis and a polarizer having a tilt of 135.degree. about a light
absorbing axis, and a right eyeglass comprising a quarter-wave
plate having a tilt of 0.degree. about the slow phase axis and a
polarizer having a tilt of 45.degree. about the light absorbing
axis.
[0011] Yet another aspect of this document is to provide a
stereoscopic image display device, comprising a display device
configured to display a first image data and a second image data in
a time-dividing manner, a switchable retarder panel configured to
control light emitted from the display device and made of ECB
liquid crystals, and polarization glasses configured to polarize
the light emitted from the switchable retarder panel. The
polarization glasses comprise a left eyeglass comprising a
quarter-wave plate having a tilt of 0.degree. about a slow phase
axis and a polarizer having a tilt of 135.degree. about a light
absorbing axis, and a right eyeglass comprising a quarter-wave
plate having a tilt of 90.degree. about the slow phase axis and a
polarizer having a tilt of 135.degree. about the light absorbing
axis.
[0012] Yet another aspect of this document is to provide a
stereoscopic image display device, comprising a display device
configured to display a first image data and a second image data in
a time-dividing manner, a switchable retarder panel configured to
control light emitted from the display device and made of ECB
liquid crystals, and polarization glasses configured to polarize
the light emitted from the switchable retarder panel. The
polarization glasses comprise a left eyeglass comprising a
quarter-wave plate having a tilt of 90.degree. about a slow phase
axis and a polarizer having a tilt of 45.degree. about a light
absorbing axis, and a right eyeglass comprising a quarter-wave
plate having a tilt of 90.degree. about the slow phase axis and a
polarizer having a tilt of 135.degree. about the light absorbing
axis.
[0013] Yet another aspect of this document is to provide a
stereoscopic image display device, comprising a display device
configured to display a first image data and a second image data in
a time-dividing manner, a switchable retarder panel configured to
control light emitted from the display device and made of ECB
liquid crystals, and polarization glasses configured to polarize
the light emitted from the switchable retarder panel. The
polarization glasses comprise a left eyeglass comprising a
quarter-wave plate having a tilt of 90.degree. about a slow phase
axis, a half-wave plate having a tilt of 0.degree. about the slow
phase axis, and a polarizer having a tilt of 135.degree. about a
light absorbing axis, and a right eyeglass comprising a
quarter-wave plate having a tilt of 90.degree. about the slow phase
axis and a polarizer having a tilt of 135.degree. about the light
absorbing axis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompany drawings, which are included to provide a
further understanding of this document and are incorporated on and
constitute a part of this specification illustrate embodiments of
this document and together with the description serve to explain
the principles of this document.
[0015] FIG. 1 shows a schematic configuration of a stereoscopic
image display device according to an exemplary embodiment of this
document;
[0016] FIG. 2 is a diagram showing the subpixels of a display
device shown in FIG. 1;
[0017] FIG. 3 is a diagram showing the electrodes of a switchable
retarder panel shown in FIG. 1;
[0018] FIG. 4 is a diagram showing examples of 3-D mode operations
of the stereoscopic image display device according to an exemplary
embodiment of this document;
[0019] FIGS. 5 and 6 are diagrams illustrating a scanning method
using the display device and the switchable retarder panel;
[0020] FIG. 7 is a table showing changes in the logical values of a
control signal for controlling voltages which are supplied to the
scan lines of the switchable retarder panel;
[0021] FIG. 8 is a diagram showing voltages which are supplied to
the scan lines of the switchable retarder panel in response to left
and right-eye images displayed on the display device;
[0022] FIG. 9 is a graph illustrating changes in transmittance
versus response time of a conventional switchable retarder panel
and of the switchable retarder panel according to the exemplary
embodiment of this document;
[0023] FIG. 10 is a diagram illustrating that residual retardation
is generated in a switchable retarder panel made of electrically
controlled birefringence (ECB) liquid crystals;
[0024] FIG. 11 is a diagram illustrating the polarization direction
of light which is emitted from the switchable retarder panel when
the display device emits linearly polarized light;
[0025] FIG. 12 is a diagram showing the structure of polarization
glasses according to a first exemplary embodiment of this
document;
[0026] FIG. 13 is a diagram shown to help understanding of the
absorbing axis and the transmissive axis of a polarizer and the
slow phase axis and the high-speed axis of a uniaxial film;
[0027] FIGS. 14 and 15 are diagrams showing a construction of
polarization glasses according to a second exemplary embodiment of
this document;
[0028] FIG. 16 is a diagram illustrating the polarization direction
of light which is emitted from the switchable retarder panel when
the display device emits circularly polarized light;
[0029] FIGS. 17 to 20 are diagrams showing a construction of
polarization glasses according to a third exemplary embodiment of
this document;
[0030] FIGS. 21 and 22 are diagrams showing a construction of
polarization glasses according to a fourth exemplary embodiment of
this document; and
[0031] FIGS. 23 and 24 are diagrams showing a construction of
polarization glasses according to a fifth exemplary embodiment of
this document.
DETAILED DESCRIPTION
[0032] Reference will now be made in detail to embodiments of this
document examples of which are illustrated in the accompanying
drawings.
[0033] Hereinafter, one or more implementations of this document
are described in detail.
[0034] Referring to FIGS. 1 to 3, a stereoscopic image display
device according to an exemplary embodiment of this document
comprises an image supply unit 110, a control unit 120, a first
driving unit 130, a second driving unit 135, a display device 150,
a switchable retarder panel 160, and polarization glasses 170.
[0035] The image supply unit 110 is configured to supply the
control unit 120 with image data having a two-dimensional (2-D)
format in the 2-D mode and right and left image data having a
three-dimensional (3-D) format in the 3-D mode. Further, the image
supply unit 110 is configured to supply the control unit 120 with
timing signals, such as a vertical sync signal Vsync, a horizontal
sync signal Hsync, a data enable signal DE, a main clock, and a low
voltage GND. The image supply unit 110 selects the 2-D mode or the
3-D mode according to user choice through a user interface. The
user interface may comprise user input means, such as an on-screen
display (OSD), a remote controller, a keyboard, or a mouse. The
image supply unit 110 may divide the image data into right-eye
image data and left-eye image data, which have the 3-D format,
according to a left-eye image and a right-eye image which are
displayed in the display device 150 and may encode the divided
image data.
[0036] The control unit 120 is configured to supply the display
device 150 with first image data and second image data. The first
image data may be selected as left-eye image data, and the second
image data may be selected as right-eye image data. The control
unit 120 is configured to supply the first driving unit 130 with
the image data which is received from the image supply unit 110 in
the form of a frame frequency of 60.times.n (where n is a positive
integer of 2 or more) Hz. In the 3-D mode, the control unit 120
alternately supplies the first driving unit 130 with the left-eye
image data and the right-eye image data. The control unit 120
multiplies the frame frequency of an input image n times in order
to increase the frequency of a timing control signal for
controlling the operating timings of the first and second driving
units 130 and 135. Further, the control unit 120 controls the
second driving unit 135 such that voltages of scan lines 164 formed
in the switchable retarder panel 160 change from a first driving
voltage to a second driving voltage according to a line at which a
left-eye image and a right-eye image are changed in the display
device 150.
[0037] The first driving unit 130 comprises a data driving circuit
connected to data lines Dn, . . . , Dn+2 and a gate driving circuit
connected to gate lines Gm and Gm+1. The data driving circuit
converts digital video data which is received from the control unit
120 into positive/negative polarity analog video data voltages and
supplies the converted voltages to the data lines Dn, . . . , Dn+2,
under the control of the control unit 120. The gate driving circuit
sequentially supplies a gate pulse (or a scan pulse) to the gate
lines Gm and Gm+1 under the control of the control unit 120.
[0038] The second driving unit 135 shifts a switching voltage Von
or Voff which is supplied to the scan lines 164 according to the
boundary of the left-eye image data and the right-eye image data in
the display device 150. The second driving unit 135 may be
implemented using a multiplexer array for selecting the switching
voltage Voff which is synchronized with the left-eye image data
displayed in the display device 150 and positive/negative polarity
voltages +Von/-Von which are synchronized with the right-eye image
data displayed in the display device 150 under the control of the
control unit 120. Alternatively, the second driving unit 135 may be
implemented using a shift register, a level shifter for shifting
the output of the shift register to the switching voltage Voff and
the positive/negative polarity voltages +Von/-Von, and so on.
Alternatively, the second driving unit 135 may be implemented using
any kind of an analog to digital circuit which is able to
sequentially supply the switching voltage Voff and the
positive/negative polarity voltages +Von/-Von to the scan lines 164
of the switchable retarder panel 160.
[0039] The display device 150 displays the first image data during
an N.sup.th (where) N is a positive integer) frame period and the
second image data during an (N+1).sup.th frame period. The display
device 150 may be implemented using a liquid crystal display (LCD).
The display device 150 comprises a thin film transistor
(hereinafter referred to as a `TFT`) substrate and a color filter
substrate. A liquid crystal layer is formed between the TFT
substrate and the color filter substrate. The data lines Dn, . . .
, Dn+2 and the gate lines Gm and Gm+1 are formed on the rear glass
substrate of the TFT substrate so that they are orthogonal to each
other. Further, subpixels SPr, SPg, and SPb which are defined by
the data lines Dn, . . . , Dn+2 and the gate lines Gm and Gm+1 are
formed in a matrix form on the rear glass substrate. A TFT is
formed at the intersection of each of the data lines Dn, . . . ,
Dn+2 and the gate lines Gm and Gm+1 supplies the pixel electrode of
a liquid crystal cell with a data voltage that is supplied via the
data lines Dn, . . . , Dn+2 in response to the scan pulse received
from the gate line Gm. To this end, the gate electrode of the TFT
is connected to the gate line Gm, and the source electrode of the
TFT is connected to the data line Dn. The drain electrode of the
TFT is connected to the pixel electrode of the liquid crystal cell.
A common voltage is supplied to a common electrode that is opposite
to the pixel electrode. The color filter substrate comprises black
matrices and a color filter which are formed on the front glass
substrate of the TFT. The common electrode is formed on the front
glass substrate in a vertical electric field driving method, such
as a twisted nematic (TN) mode and a vertical alignment (VA) mode,
and is formed on the rear glass substrate along with the pixel
electrode in a horizontal electric field driving method, such as an
in-plane switching (IPS) mode and a fringe field switching (FFS)
mode. Polarizing plates 154 and 156 are attached to the front and
rear glass substrates of the display device 150, respectively. An
orientation film for determining a pre-tilt angle of a liquid
crystal is formed in each of the polarizing plates 154 and 156 of
the display device 150. The front polarizing plate 156 has a light
absorbing axis, which is equal to the light absorbing axis of the
left-eye polarizing filter of the polarization glasses 170, and
determines the polarization characteristic of light which is
incident on the switchable retarder panel 160 along the light
absorbing axis. The rear polarizing plate 154 determines the
polarization characteristic of light which is incident on the
display device 150. Spacers for maintaining the cell gap of the
liquid crystal layer are formed between the front glass substrate
and the rear glass substrate of the display device 150. The liquid
crystal mode of the display device 150 may comprise any kind of a
liquid crystal mode as well as the TN mode, the VA mode, the IPS
mode, or the FFS mode. Further, the display device 150 may be
implemented using any kind of a liquid crystal display device, such
as a transmissive liquid crystal display device, a
semi-transmissive liquid crystal display device, or a reflective
liquid crystal display device. The transmissive liquid crystal
display device and the semi-transmissive liquid crystal display
device require a backlight unit 151, as shown in FIG. 1. The
above-described display device 150 is configured to output linearly
polarized light or circularly polarized light.
[0040] The switchable retarder panel 160 is configured to convert
light which is received from the display device 150 into first
polarized light in response to the first driving voltage during the
N.sup.th frame period and to convert light which is received from
the display device 150 into second polarized light in response to
the second driving voltage during the (N+1).sup.th frame period. To
this end, the switchable retarder panel 160 comprises a front glass
substrate (or a transparent substrate) and a rear glass substrate
(or a transparent substrate) which are opposite to each other with
the liquid crystal layer intervened therebetween. The common
electrode 168 is formed in the front glass substrate, and the scan
lines 164 classified into a plurality of groups are formed in the
rear glass substrate in a traverse stripe pattern. The scan lines
164 formed in the switchable retarder panel 160 are classified into
some groups and arranged in the same direction so that they have a
correspondence relation of 1:N stages (where N is an even number)
for the gate lines Gm and Gm+1 which are formed in the display
device 150. For example, assuming that the number of gate lines Gm
and Gm+1 of the display device 150 is 1080 and the number of scan
lines 164 of the switchable retarder panel 160 is 90, one scan line
is formed to correspond to twelve gate lines. The liquid crystal
layer formed between the rear glass substrate and the front glass
substrate is made of electrically controlled birefringence (ECB)
liquid crystals which have a half-wave plate (.lamda./2) optical
axis characteristic when the scan lines 164 are in an off state. A
common voltage, having an equipotential as the common voltage which
is supplied to the common electrode of the display device 150, is
supplied to the common electrode 168. The switching voltage Voff,
having an equipotential as the common voltage supplied to the
common electrode 168, is supplied to the scan lines 164 before (or
after) the right-eye image (or the left-eye image) is displayed in
lines of the display device 150 which are opposite to the scan
lines 164. The positive/negative polarity voltages +Von/-Von,
having a potential difference with the common voltage supplied to
the common electrode 168, are alternately supplied to the scan
lines 164 before (or after) the right-eye image (or the left-eye
image) is displayed in lines of the display device 150 which are
opposite to the scan lines 164. Accordingly, the switching on or
off voltage having a three-step voltage level is supplied to the
scan lines 164 such that an observer can see the right and left-eye
images displayed in the display device 150 through the polarization
glasses 170. The positive/negative polarity voltages +Von/-Von
which are generated on the basis of the common voltage function to
prevent the liquid crystals from being deteriorated because of a DC
voltage. The common voltage supplied to the common electrode of the
display device 150 and the common voltage Vcom or the switching
voltage Voff which is supplied to the common electrode 168 and the
scan lines 164 of the switchable retarder panel 160 may be set to
7.5 V, the positive polarity voltage +Von supplied to the scan
lines 164 of the switchable retarder panel 160 may be set to 15 V,
and the negative polarity voltage -Von supplied to the scan lines
164 of the switchable retarder panel 160 may be set to 0 V.
[0041] The polarization glasses 170 comprise a left eyeglass and a
right eyeglass having different light absorbing axes such that the
polarization characteristic of the left eye differ from the
polarization characteristic of the right eye. The polarization
glasses 170 may have a one-layer structure comprising only a
polarizer, a two-layer structure comprising a compensation plate
(the compensation plate represents A-Plate) and a polarizer, a
two-layer structure comprising a wave plate and a polarizer, or a
three-layer structure comprising wavelength plates and a polarizer
according to the structure of the display device 150 and the
switchable retarder panel 160.
[0042] Hereinafter, an exemplary operation of the stereoscopic
image display device and scanning methods using the display device
and the switchable retarder panel are schematically described, and
the polarization glasses are then described in more detail.
[0043] FIG. 4 is a diagram showing, on a frame basis (first to
third frames), how the left and right-eye images which have passed
through the display device 150 and the switchable retarder panel
160 can be seen through the polarization glasses 170. The display
device 150 alternately displays the left and right-eye images in
the 3-D mode and transmits light of the left and right-eye images
via the front polarizing plate 156 as left polarized light. When
the switching voltage Voff is supplied to the scan lines 164, the
switchable retarder panel 160 delays the phase of the left
polarized light which is received from the display device 150 by
90.degree. and transmits right polarized light toward the
polarization glasses 170. When the positive/negative polarity
voltages +Von/-Von are supplied to the scan lines 164, the
switchable retarder panel 160 transmits the left polarized light
which is received from the display device 150 without phase delay.
Accordingly, assuming that the display device 150 and the
switchable retarder panel 160 are driven at the frame frequency of
120 Hz, the left-eye image is displayed in the display device 150
during odd-numbered frame periods and the right-eye image is
displayed in the display device 150 during even-numbered frame
periods. Thus, an observer who wears the polarization glasses 170
can see the left-eye image through his left eye during odd-numbered
frame periods and the right-eye image through his right eye during
even-numbered frame periods. The above left polarized light may be
any one of vertical linearly polarized light (or a horizontal
linearly polarized light) and left circularly polarized light (or
right circularly polarized light) or may be any one of horizontal
linearly polarized light (or vertical linearly polarized light) and
right circularly polarized light (or horizontal linearly polarized
light) which have an optical axis intersecting the optical axis of
right polarized light. Meanwhile, the display device 150 displays
an image of a 2-D format in the 2-D mode. When the display device
150 displays an image of a 2-D format, an observer can see the 2-D
image by taking off the polarization glasses 170.
[0044] Referring to FIGS. 5 and 6, the display device 150
sequentially writes the data of the left-eye image on a line basis
in the 3-D mode. Here, the display device 150 sequentially writes
the data of the right-eye image on a line basis in a next frame
period. Before the writing of the left-eye image (or the right-eye
image), the liquid crystal cells maintain the data of the right-eye
image (or the left-eye image) which has been charged in a previous
frame period.
[0045] The second driving unit 135 controls voltages which are
supplied to the scan lines 164 of the switchable retarder panel 160
under the control of the first control unit 120, as in the logic
table shown in FIG. 7. In FIG. 7, `0` indicates the switching
voltage Voff which is supplied to the scan lines 164 in
synchronization with a data scan time of the left-eye image that is
written into the display device 150. `1` indicates the
positive/negative polarity voltages +Von/-Von which are supplied to
the scan lines 164 in synchronization with a data scan time of the
right-eye image that is written into the display device 150.
[0046] In FIG. 7, the lines of the table correspond to the
respective scan lines 164 of the switchable retarder panel 160, and
`t=0, . . . , 2TF , , , ` at the top of the table indicate the
lapse of time. In FIG. 7, at `1Tf`, the switching voltage Voff is
supplied to all the scan lines 164, comprising the first scan line
at the top of the table and the last scan line at the bottom of the
table. If the right-eye image is scanned into the display device
150 starting from the first scan line, the positive/negative
polarity voltages +Von/-Von start being supplied to the scan lines
164 line by line in the scan direction. Accordingly, the voltages
supplied to the scan lines 164 change from the switching voltage
Voff to the positive/negative polarity voltages +Von/-Von along a
line at which an image displayed in the display device 150 changes
from a left-eye image to a right-eye image. Further, the voltages
supplied to the scan lines 164 change from the positive/negative
polarity voltages +Von/-Von to the switching voltage Voff along a
line at which an image displayed in the display device 150 changes
from a right-eye image to a left-eye image. A case where data of
the left-eye image is first displayed is taken as an example in the
above description. It is, however, to be noted that, if data of the
right-eye image is first displayed, the voltages supplied to the
scan lines 164 may differ from those of the above example.
[0047] In FIG. 8, `Von/Voff (SR)` indicates polarized switching
voltage which is supplied to turn on or off the scan lines 164 of
the switchable retarder panel 160. As in FIG. 8, in order to
convert the light which is generated by the left-eye image
displayed in the display device 150 into a polarized light, the
switching voltage Voff is supplied to the scan lines 164 of the
switchable retarder panel 160. On the other hand, in order to
convert the light which is generated by the right-eye image
displayed in the display device 150 into a polarized light, the
positive/negative polarity voltages +Von/-Von are supplied to the
scan lines 164 of the switchable retarder panel 160. Thus, an
observer may feel ortho-stereoscopy resulting from binocular
disparity through the polarization glasses 170 because of such an
operating characteristic of the display device 150 and the
switchable retarder panel 160.
[0048] As described above, the stereoscopic image display device
according to the exemplary embodiment of this document comprises
the display device 150 implemented using a liquid crystal display
(LCD), the switchable retarder panel 160 made of ECB liquid
crystals and configured to control light emitted from the display
device 150, and the polarization glasses 170 configured to polarize
the light emitted from the switchable retarder panel 160. Here, the
switchable retarder panel 160, as described above, is made of ECB
liquid crystals.
[0049] Referring to FIG. 9, it can be seen that the switchable
retarder panel 160 made of ECB liquid crystals as in the exemplary
embodiment does not have response time delay upon turn-off as
compared with a conventional switchable retarder panel made of TN
liquid crystals. Accordingly, the exemplary embodiment can improve
the response time because it uses the switchable retarder panel 160
made of ECB liquid crystals. However, the switchable retarder panel
160 made of ECB liquid crystals may also have residual retardation
in an on state. This is described below with reference to the
drawings.
[0050] Referring to FIG. 10, the liquid crystal layer 165 placed
within the switchable retarder panel 160 made of ECB liquid
crystals is turned on or off while being rotated in response to
voltages applied to the scan lines and the common electrode. In an
on state, the switchable retarder panel 160 has residual
retardation because liquid crystals is located at the position of
"RR1" and "RR2" Where liquid crystals are not easy to be moved
corresponding the direction of the driving voltage. Here, the
reason why the liquid crystals causing such residual retardation
are generated is that, when the liquid crystals are formed, a small
number of the liquid crystals are adjacent to an orientation film
having the property of catching the liquid crystals. The liquid
crystals may exist in places other than the position of "RR1" and
"RR2." If such residual retardation occurs, leakage of light is
caused in one of the polarization glasses 170. Accordingly, the
exemplary embodiment sets up the polarization glasses 170 having
the following structure on the basis of the structural conditions
of the display device 150 and the switchable retarder panel 160 in
order to deal with the leakage of light caused by the residual
retardation.
First Exemplary Embodiment
[0051] Referring to FIG. 11, the first exemplary embodiment of this
document has set up a condition of the polarization glasses 170 in
the case where the display device 150 is configured to output
linearly polarized light and the switchable retarder panel 160 is
made of ECB liquid crystals.
[0052] In FIG. 11, when the switchable retarder panel 160 is in an
on state, light emitted from the switchable retarder panel 160 is
polarized in the direction of a left polarized-light axis. When the
switchable retarder panel 160 is in an off state, light emitted
from the switchable retarder panel 160 is polarized in the
direction of a right polarized-light axis. Here, reference numeral
165 indicates the rubbing direction of the ECB liquid crystals
formed in the switchable retarder panel 160. In the case where the
direction of final light emitted from the switchable retarder panel
160 is set up as described above, a left eyeglass 170L and a right
eyeglass 170R constituting the polarization glasses 170 may be
configured as follows.
[0053] The polarization glasses 170, as shown in FIG. 12, comprises
the left eyeglass 170L comprising a polarizer POL1 having a tilt of
45.degree. about a light absorbing axis and the right eyeglass 170R
comprising a polarizer POL2 having a tilt of 135.degree. about the
light absorbing axis.
[0054] FIG. 13 shows the absorbing axis and the transmissive axis
of a polarizer and the slow phase axis and the high-speed axis of a
uniaxial film. The polarizer is a device for converting unpolarized
light or arbitrarily polarized light into light of a single
polarization state. Here, the absorbing axis of the polarizer
functions to absorb incident light so that the incident light does
not pass through the polarizer, and the transmissive axis of the
polarizer functions to transmit incident light. The uniaxial film
has an optical axis in one direction and converts linearly
polarized light into circularly polarized light. Here, the slow
phase axis of the uniaxial film is vertical to the direction of
liquid crystals, and the high-speed axis of the uniaxial film is
orthogonal to the slow phase axis.
Second Exemplary Embodiment
[0055] Referring to FIGS. 14 and 15, the second exemplary
embodiment of this document may have, for example, a condition in
which, as in the first exemplary embodiment, the display device 150
is configured to emit linearly polarized light and the switchable
retarder panel 160 is made of ECB liquid crystals.
[0056] The polarization glasses 170, as shown in FIG. 14, may
comprise the left eyeglass 170L configured to comprise a half-wave
plate HWP having a tilt of 0.degree. about a slow phase axis and a
polarizer POL1 having a tilt of 135.degree. about a light absorbing
axis and the right eyeglass 170R configured to comprise a polarizer
POL2 having a tilt of 135.degree. about the light absorbing axis.
Here, the reason why the half-wave plate HWP written into the left
eyeglass 170L is to set up the slow phase axis of the half-wave
plate HWP so that it is orthogonal to the polarized light in an off
state of the switchable retarder panel 160. In more detail, leakage
of light is generated due to a wavelength dispersion property
because the liquid crystals of the switchable retarder panel 160
are aligned in a vertical direction. In order to compensate for the
leakage of light, the slow phase axis of the half-wave plate HWP is
set up in such a way as to be orthogonal to an off state of the
switchable retarder panel 160.
[0057] In an alternative embodiment, the polarization glasses 170,
as shown in FIG. 15, may comprise the left eyeglass 170L configured
to comprise a polarizer POL1 having a tilt of 135.degree. about a
light absorbing axis and a half-wave plate HWP on the polarizer
POL1 having a tilt of 0.degree. about a slow phase axis, and the
right eyeglass 170R configured to comprise a polarizer POL2 having
a tilt of 135.degree. about the light absorbing axis and a
compensation plate APLT on the polarizer POL2 having a tilt of
0.degree. about the slow phase axis.
Third Exemplary Embodiment
[0058] Referring to FIG. 16, the third exemplary embodiment has set
up a condition of the polarization glasses 170 in the case where
the display device 150 is configured to emit circularly polarized
light and the switchable retarder panel 160 is made of ECB liquid
crystals. In the case where light emitted from the display device
150 has a circularly polarized light condition, a quarter-wave
plate 166 is attached in a direction where the switchable retarder
panel 160 emits light.
[0059] In FIG. 16, when the switchable retarder panel 160 is in an
on state, light emitted from the switchable retarder panel 160 is
polarized in the direction of left polarized light. When the
switchable retarder panel 160 is in an off state, light emitted
from the switchable retarder panel 160 is polarized in the
direction of right polarized light. Here, reference numeral 165
indicates the rubbing direction of the ECB liquid crystals which
are formed in the switchable retarder panel 160. If the direction
of final light emitted from the switchable retarder panel 160 is
set up as described above, the left eyeglass 170L and the right
eyeglass 170R constituting the polarization glasses 170 may be
configured as follows.
[0060] The polarization glasses 170, as shown in FIG. 16, may
comprise the left eyeglass 170L configured to comprise a
quarter-wave plate QWP1 having a tilt of 0.degree. about a slow
phase axis and a polarizer POL1 having a tilt of 135.degree. about
a light absorbing axis and the right eyeglass 170R configured to
comprise a quarter-wave plate QWP2 having a tilt of 0.degree. about
the slow phase axis, a compensation plate APLT having a tilt of
0.degree. about the slow phase axis, and a polarizer POL2 having a
tilt of 45.degree. about the light absorbing axis.
[0061] In an alternative embodiment, the polarization glasses 170,
as shown in FIG. 18, may comprise the right eyeglass 170R,
comprising a quarter-wave plate QWP2 having a tilt of 0.degree.
about the slow phase axis and a polarizer POL2 having a tilt of
45.degree. about the light absorbing axis, in the state in which
the left eyeglass 170L has the same construction as FIG. 17.
[0062] In another alternative embodiment, the polarization glasses
170, as shown in FIG. 19, may comprise the right eyeglass 170R,
comprising a quarter-wave plate QWP2 having a tilt of 90.degree.
about the slow phase axis, a compensation plate APLT having a tilt
of 0.degree. about the slow phase axis, and a polarizer POL2 having
a tilt of 135.degree. about the light absorbing axis, in the state
in which the left eyeglass 170L has the same construction as FIG.
17.
[0063] In yet another alternative embodiment, the polarization
glasses 170, as shown in FIG. 20, may comprise the right eyeglass
170R, comprising a quarter-wave plate QWP2 having a tilt of
90.degree. about the slow phase axis and a polarizer POL2 having a
tilt of 135.degree. about the light absorbing axis, in the state in
which the left eyeglass 170L has the same construction as FIG.
17.
Fourth Exemplary Embodiment
[0064] Referring to FIGS. 21 and 22, the fourth exemplary
embodiment of this document illustrates a case where, as in the
third exemplary embodiment, the display device 150 is configured to
emit circularly polarized light and the switchable retarder panel
160 is made of ECB liquid crystals. In the case where the direction
of final light emitted from the switchable retarder panel 160 is
set up as described above, the left eyeglass 170L and the right
eyeglass 170R constituting the polarization glasses 170 may be
configured as follows.
[0065] The polarization glasses 170, as shown in FIG. 21, may
comprise the left eyeglass 170L configured to comprise a
quarter-wave plate QWP1 having a tilt of 90.degree. about a slow
phase axis and a polarizer POL1 having a tilt of 45.degree. about a
light absorbing axis and the right eyeglass 170R configured to
comprise a quarter-wave plate QWP2 having a tilt of 90.degree.
about the slow phase axis, a compensation plate APLT having a tilt
of 0.degree. about the slow phase axis, and a polarizer POL2 having
a tilt of 135.degree. about the light absorbing axis.
[0066] In an alternative embodiment, the polarization glasses 170,
as shown in FIG. 22, may comprise the right eyeglass 170R,
comprising a quarter-wave plate QWP2 having a tilt of 90.degree.
about the slow phase axis and a polarizer POL2 having a tilt of
135.degree. about the light absorbing axis in the state in which
the left eyeglass 170L has the same construction as FIG. 21.
Fifth Exemplary Embodiment
[0067] Referring to FIGS. 23 and 24, the fifth exemplary embodiment
of this document illustrates a case where, as in the third
exemplary embodiment, the display device 150 is configured to emit
circularly polarized light and the switchable retarder panel 160 is
made of ECB liquid crystals. In the case where the direction of
final light emitted from the switchable retarder panel 160 is set
up as described above, the left eyeglass 170L and the right
eyeglass 170R constituting the polarization glasses 170 are
configured as follows.
[0068] The polarization glasses 170, as shown in FIG. 23, may
comprise the left eyeglass 170L configured to comprise a
quarter-wave plate QWP1 having a tilt of 90.degree. about a slow
phase axis, a half-wave plate HWP having a tilt of 0.degree. about
the slow phase axis, and a polarizer POL1 having a tilt of
135.degree. about a light absorbing axis and the right eyeglass
170R configured to comprise a quarter-wave plate QWP2 having a tilt
of 90.degree. about the slow phase axis, a compensation plate APLT
having a tilt of 0.degree. about the slow phase axis, and a
polarizer POL2 a tilt of 135.degree. about the light absorbing
axis.
[0069] In an alternative embodiment, the polarization glasses 170,
as shown in FIG. 24, may comprise the right eyeglass 170R,
comprising a quarter-wave plate QWP2 having a tilt of 90.degree.
about the slow phase axis and a polarizer POL2 having a tilt of
135.degree. about the light absorbing axis, in the state in which
the left eyeglass 170L has the same construction as FIG. 23.
[0070] The structure of the polarization glasses 170 which has been
configured as described above so that it can deal with leakage of
light resulting from residual retardation can be represented by the
following table. In Table 1, a symbol "-" means that there is no
layer.
TABLE-US-00001 TABLE 1 CONDITION OF POLARIZATION GLASSES (SHEET
CONSTRUCTION) Layer 1 Layer 2 POL 1, 2 (about slow (about slow
(about light Embodiment Condition Glasses phase axis) phase axis)
absorbing axis) First linearly left -- -- 45.degree. embodiment
polarized eyeglass light right -- -- 135.degree. eyeglass Second
linearly left HWP(0.degree.) -- 135.degree. embodiment polarized
eyeglass light right -- -- 135.degree. eyeglass APLT(0.degree.) --
135.degree. Third circularly left QWP1(0.degree.) -- 135.degree.
embodiment polarized eyeglass light right QWP2(0.degree.)
APLT(0.degree.) 45.degree. eyeglass QWP2(0.degree.) -- 45.degree.
QWP2(90.degree.) APLT(0.degree.) 135.degree. QWP2(90.degree.) --
135.degree. Fourth circularly left QWP1(90.degree.) -- 45.degree.
embodiment polarized eyeglass light right QWP2(90.degree.)
APLT(0.degree.) 135.degree. eyeglass QWP2(90.degree.) --
135.degree. Fifth circularly left QWP2(90.degree.) HWP(0.degree.)
135.degree. embodiment polarized eyeglass light right
QWP2(90.degree.) APLT(0.degree.) 135.degree. eyeglass
QWP2(90.degree.) -- 135.degree.
[0071] This document has an advantage in that it can provide the
stereoscopic image display device capable of preventing leakage of
light which is generated in one of polarization glasses due to
residual retardation of light emitted through the switchable
retarder panel. Further, this document is advantageous in that it
can provide the stereoscopic image display device capable of
reducing a crosstalk level, occurring when displaying a 3-D image,
through the improvements of the response time using the switchable
retarder panel made of ECB liquid crystals.
[0072] The foregoing embodiments and advantages are merely
exemplary and are not to be construed as limiting this document.
The present teaching can be readily applied to other types of
apparatuses. The description of the foregoing embodiments is
intended to be illustrative, and not to limit the scope of the
claims. Many alternatives, modifications, and variations will be
apparent to those skilled in the art. In the claims,
means-plus-function clauses are intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures.
* * * * *