Abstract:
A display device includes a display panel including first to fourth pixels in a first direction, wherein each of the first to fourth pixels has a first width in the first direction and a length more than the width and in a second direction; and a backlight unit including first and second line light regions supplying light to the display panel to display three-dimensional images, wherein the first and second line light regions have a slanted angle with respect to the second direction, wherein light from the first line light region comes to right and left eyes of a viewer through the first and second pixels, respectively, and light from the second light region comes to the right and left eyes through the third and fourth pixels, respectively, wherein the display device has K view points.

Description:
CLAIM FOR PRIORITY 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2007-0066194, filed in Korea on Jul. 2, 2007, which is hereby incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a three-dimensional display device, and in particular, an integral photography type three-dimensional display device. 
         [0004]    2. Discussion of the Related Art 
         [0005]    A two-dimensional display device is generally used. Recently, because of wideband communication networks, a three-dimensional display device has been researched and developed. 
         [0006]    There are various types of three-dimensional image displays, for example, a holographic image type, a stereographic type, a volumetric type and the like. 
         [0007]    The holographic type is used for a holographic image using a laser or a white ray. 
         [0008]    The stereographic type display device displays a three-dimensional image using binocular parallax. The stereographic type display device includes a display device that uses specific glasses and a display device without glasses. The stereoscopic display devices without glasses are divided into a parallax barrier type, a lenticular type, and the like. 
         [0009]    The volumetric type is used for three-dimensional computer graphics or an I-MAX movie. Of volumetric types, an integral photography type has advantage of identically reproducing optical properties, such as light distribution and brightness, of a real three-dimensional object and displaying a three-dimensional image perceived as the real three-dimensional object. 
         [0010]      FIGS. 1A and 1B  are views illustrating a principle of displaying a three-dimensional image in an integral photography type three-dimensional display device. 
         [0011]    Referring to  FIG. 1A , when there is a real three-dimensional object  50 , the object  10  is perceived through rays  10   a  to  10   f  emitted from a surface of the object  10 . In other words, external rays reflecting on the object  10  or rays radiating at the object  10  itself are emitted as the rays  10   a  to  10   f  from the object  10 , and a viewer combines the rays  10   a  to  10   f  and perceives the object  10 . 
         [0012]    Referring to  FIG. 1B , if a three-dimensional display device emits rays  20   a  to  20   f  which have the same light distribution and brightness as the rays  10   a  to  10   f  emitted from the surface of the object  10 , the viewer combines the rays  20   a  to  20   f  from the display device and perceives a virtual object  20  as the object  10 . 
         [0013]      FIG. 2A  is a view illustrating an image-taking device, and  FIG. 2B  is a view illustrating an integral photography type three-dimensional display device according to the related art. 
         [0014]    Referring to  FIG. 2A , the image-taking device  60  includes an image-taking lens array  62  and an image-taking panel  64 . The image-taking lens array  62  includes a plurality of convex lens in a matrix form. The image-taking panel  64  has a plurality of pixels. The image-taking panel  64  uses a photograph for static images, and a CCD (charge-coupled device) for moving images. 
         [0015]    An object  50  emits a plurality of rays  50   a  toward the image-taking lens array  62 , and the rays  50   a  is condensed through the image-taking lens array  62  and recorded in the pixels of the image-taking panel  64 . 
         [0016]    The plurality of pixels of the image-taking panel  64  records a plurality of images  52  of the object viewed through the plurality of convex lens of the lens array  62 , respectively. Accordingly, the image-taking device  60  takes image data for the object  50  viewed in various directions in space. 
         [0017]    The image data are displayed by the integral photography type three-dimensional display device of  FIG. 2B  and combined by a viewer, and a three-dimensional image is perceived. 
         [0018]    Referring to  FIG. 2B , the integral photography type three-dimensional display device  70  includes a display panel  72  and a display lens array  74 . The display panel  72  includes a plurality of pixels. The display panel  72  uses a photograph for static images, and a flat display panel for moving images. The display lens array  74  includes a plurality of convex lens in a matrix form in similar to the image-taking lens array  62 . 
         [0019]    The display panel  72  is supplied with the image data recorded by the image-taking device  60 . The plurality of pixels of the display panel  72  display the plurality of images  52  of the object  50 , respectively, using the image data. A plurality of rays  74  emitted from the plurality of pixels of the display panel  72  are condensed through the plurality of convex lens of the display lens array  74 . The condensed plurality of rays  80   a  form a plurality of voxels (volume pixels). A plurality of partial images displayed at the plurality of voxels are integrated at a point and form an image  80  corresponding to the object  50  at a certain position in space. 
         [0020]    Through these processes, the integral photography type three-dimensional display device  70  displays the three-dimensional image  80  identical to the object  50 , and the viewer perceives as if the object  50  existed. 
         [0021]    Because the integral photography type three-dimensional display device forms three-dimensional images in space, the integral photography type three-dimensional display device supplies continuous horizontal and vertical parallax, and single or multiple viewers view the three-dimensional images without specific glasses. However, because position of the voxels formed in space through the lens array is fixed, a depth range given to the displayed image is limited. This limitation is because the lens array of a passive lens type is used. 
         [0022]    In other words, the lens array is fixed in the related art integral photography type three-dimensional display device, and position and property of the convex lens of the lens array is fixed. Accordingly, condensing direction and condensed position by the lens array is not actively control, and thus the depth range given to the displayed image is limited. 
       SUMMARY 
       [0023]    An integral photography type three-dimensional display device is disclosed that includes a brightness control panel including a plurality of brightness pixels, wherein each of the plurality of brightness pixels control a brightness of a ray incident thereon; and a path control panel including a plurality of path pixels, wherein each of the plurality of path pixels control a path of the ray leaving each of the plurality of brightness pixels. 
         [0024]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
           [0026]      FIGS. 1A and 1B  are views illustrating a principle of displaying a three-dimensional image in an integral photography type three-dimensional display device; 
           [0027]      FIG. 2A  is a view illustrating an image-taking device; 
           [0028]      FIG. 2B  is a view illustrating an integral photography type three-dimensional display device according to the related art; 
           [0029]      FIG. 3  is a view illustrating an integral photography type three-dimensional display device according to a first embodiment of the disclosure; 
           [0030]      FIG. 4  is a view illustrating parts of a brightness control panel and a path control panel of an integral photography type three-dimensional display device according to the first embodiment of the present disclosure; 
           [0031]      FIG. 5A  is a perspective view illustrating a part of a path control panel of an integral photography type three-dimensional display device according to the first embodiment of the present disclosure; 
           [0032]      FIG. 5B  is a cross-sectional view taken along a line V-V of  FIG. 5A ; 
           [0033]      FIG. 6A  is a perspective view illustrating a path control panel of an integral photography type three-dimensional display device according to a second embodiment of the present disclosure; and 
           [0034]      FIG. 6B  is a cross-sectional view taken along a line VI-VI of  FIG. 6A . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0035]    Reference will now be made in detail to the illustrated embodiments of the present invention, which are illustrated in the accompanying drawings. 
         [0036]      FIG. 3  is a view illustrating an integral photography type three-dimensional display device according to a first embodiment of the disclosure. 
         [0037]    Referring to  FIG. 3 , the integral photography type display device  100  includes a brightness control panel  110  and a path control panel  120 . The brightness control panel  110  may include a backlight unit  110   a  and a liquid crystal panel  110   b  including a plurality of pixels in a matrix form. 
         [0038]    The brightness control panel  110  control brightness of a ray passing through each pixel. 
         [0039]    To prevent interference by adjacent pixels, the backlight unit  110   a  has a high-condensing property so that a plurality of first rays  112  is emitted from the backlight unit  110   a  within about a 10 degree angle with respect to a perpendicular line to a plane of the liquid crystal panel  120   a . Accordingly, the first rays  112  have uniform brightness and are incident on the liquid crystal panel  110   b.    
         [0040]    The liquid crystal panel  110   b  controls transmissivity of each pixel according to a corresponding first partial image data having brightness information. The first partial image data is supplied from an external driving circuit to the corresponding pixel. Accordingly, the plurality of pixels displays a plurality of partial images, respectively, having different brightness. In other words, the first ray  112  passes through the corresponding pixel of the liquid crystal panel  110   b  and becomes a second ray  114  corresponding to the partial image of the corresponding pixel. 
         [0041]    In the first embodiment, the brightness control panel  110  includes the high-condensing backlight unit  110   a  and the liquid crystal panel  110   b . Alternatively, other type of a bright control panel may be employed if it controls brightness of a ray at each pixel and the controlled ray is substantially perpendicularly incident on the path control panel  120 . For example, a projector may be used as the brightness control panel. 
         [0042]    The second ray  114  substantially perpendicularly leaving the corresponding pixel of the brightness control panel  110  may be substantially perpendicularly incident on the path control panel  120 . 
         [0043]    The path control panel  120  may include a plurality of pixels corresponding to the plurality of pixels of the brightness control panel  110 , respectively. Accordingly, the second ray  114  of the partial image of the corresponding pixel of the brightness control panel  110  is incident on the corresponding pixel of the path control panel  120 . 
         [0044]    Because the partial images are incident on the corresponding pixels of the path control panel  120 , interference by adjacent partial images may be prevented. 
         [0045]    The path control panel  120  controls a path of the second ray  114  through the corresponding pixel according to a second partial image data. The second partial image data is supplied from an external driving circuit to the corresponding pixel. Accordingly, the plurality of pixels displays the plurality of partial images, respectively, having different paths. In other words, the path of the second ray  114  changes through the corresponding pixel of the path control panel  120 , and the second ray  114  becomes a third ray  122  having the controlled brightness and path. 
         [0046]    The third rays  122  having the brightnesses and paths corresponding to the partial images are condensed at certain points and form a plurality of voxels  130 . 
         [0047]    Because the pixels of the path control panel  120  control the paths of the third rays  122  according to the second partial image data corresponding to a real object, the plurality of voxels are formed at various depths of space, and a viewer perceives a three-dimensional image having natural depth information through the voxels  130  having the same optical property as the real object. 
         [0048]    In other words, the plurality of third rays  122  forming the plurality of voxels  130  are transmitted to the viewer as a plurality of fourth rays  132  identical to rays of the real object, and the viewer perceives the three-dimensional image identical to the real object through the fourth rays  132 . 
         [0049]      FIG. 4  is a view illustrating parts of a brightness control panel and a path control panel of an integral photography type three-dimensional display device according to the first embodiment of the present disclosure. 
         [0050]    Referring to  FIG. 4 , in the integral photography type three-dimensional display device, a liquid crystal panel  110   b  includes first and second brightness pixels Pa 1  and Pa 2 , and a path control panel  120  includes first and second path pixels Pb 1  and Pb 2 . The liquid crystal panel  110   b  includes first and second substrates  116  and  117  and a first liquid crystal layer  118  between the first and second substrates  116  and  117 . 
         [0051]    In order that a ray passing through the first brightness pixel Pa 1  is incident on the first path pixel Pb 1  and a ray passing through the second brightness pixel Pa 2  is incident on the second path pixel Pb 2 , the first and second brightness pixels Pa 1  and Pa 2  correspond to the first and second path pixels Pb 1  and Pb 2 , respectively. 
         [0052]    The rays emitted from a backlight unit ( 110   a  of  FIG. 3 ) pass through the first and second brightness pixels Pa 1  and Pa 2  and leave the liquid crystal panel  110   b  with separately controlled brightnesses according to corresponding partial images. Then, the rays pass through the first and second path pixels Pb 1  and Pb 2  and leave the path control panel  120  with separately controlled paths according to the corresponding partial images. 
         [0053]    The integral photography type three-dimensional display device controls the rays passing through the corresponding pixels to have brightnesses and paths corresponding to the real object. To do this, partial image data having brightness information are supplied to the corresponding pixels of the brightness control panel ( 110  of  FIG. 3 ), and partial image data having path information are supplied to the corresponding pixels of the path control panel  120 . 
         [0054]    In other words, the first brightness pixel Pa 1  and the first path pixel Pb 1  are supplied with partial image data having brightness information and path information, respectively, corresponding to one partial image. The second brightness pixel Pa 2  and the second path pixel Pb 2  are supplied with partial image data having brightness information and path information, respectively, corresponding to another partial image. 
         [0055]    If a ray passing through the first brightness pixel Pa 1  passes through the second path pixel Pb 2  or a ray passing through the second brightness pixel Pa 2  passes through the first path pixel Pb 1 , the ray does not have brightness and path corresponding to the real object. This causes a noise defect in a three-dimensional image displayed by the integral photography type three-dimensional display device. 
         [0056]    This concern may be removed by making light substantially perpendicularly leave the liquid crystal panel  110   b  using the high-condensing backlight unit. Further, to further remove this concern and take a margin of condensation of the backlight unit, the liquid crystal panel  110   b  and the path control panel  120  include first and second blocking portions  119  and  129 , respectively. In  FIG. 4 , the first blocking portion  119  is located at the second substrate  117 . Alternatively, the first blocking portion  119  may be located at the first substrate  116 . 
         [0057]    When the first and second blocking portions  119  and  129  are spaced apart with a distance D 1  and have the same width D 2 , it is desirable that a ray passing through the first brightness pixel Pa 1  at an edge of the first brightness pixel Pa 1  does not pass through the second path pixel Pb 2 . To do this, a leaving angle of the ray from the liquid crystal panel  110   b  or a incident angle of the ray on the path control panel  129  may be within an angle following an expression, θ=arctan(D 2 /D 1 ). For example, when the backlight unit has condensing property for a maximum angle of light emitted from the backlight unit to be about a 10 degree angle, a relationship of the distance D 1  and the width D 2  may be determined according to an expression, (D 2 /D 1 )=tan(10°). According to this expression, the arrangement of the first and second blocking portions  119  and  129  and the condensing property of the backlight unit may be appropriately adjusted. 
         [0058]      FIG. 5A  is a perspective view illustrating a part of a path control panel of an integral photography type three-dimensional display device according to the first embodiment of the present disclosure, and  FIG. 5B  is a cross-sectional view taken along a line V-V of  FIG. 5A . 
         [0059]    Referring to  FIGS. 5A and 5B , the path control panel  120  may use liquid crystal material. The path control panel  120  includes third and fourth substrates  140  and  142  and a second liquid crystal layer  144  between the third and fourth substrates  140  and  142 . The path control panel  120  includes first and second path pixels Pb 1  and Pb 2  corresponding to the first and second brightness pixels (Pa 1  and Pa 2  of  FIG. 4 ), respectively. 
         [0060]    Each of the first and second path pixels Pb 1  and Pb 2  includes a plurality of first electrodes  146  on an inner surface of the third substrate  140 . A second blocking portion  129  may be located at a boundary portion between the first and second path pixels Pb 1  and Pb 2 . The second blocking portion  129  may be located on the first electrodes  146 . 
         [0061]    Even though not shown in the drawings, the first electrodes  146  of each of the first and second path pixels Pb 1  and Pb 2  are connected to a switching element such as a thin film transistor. A voltage applied to the first electrodes  146  is controlled according to operation of the switching element. A first insulating layer may be located between the first electrodes  146  and the second blocking portion  129 . Further, a second insulating layer may be located between the second blocking portion  129  and the second liquid crystal layer  144 . A first alignment layer contacting the second liquid crystal layer  144  may be located on the inner surface of the third substrate  140 . Further, a second alignment layer contacting the second liquid crystal layer  144  may be located on an inner surface of the fourth substrate  142 . The first and second alignment layers may be initially align liquid crystal molecules  144   a  of the second liquid crystal layer  144  substantially in parallel with a plane of the third and fourth substrates  140  and  142 . 
         [0062]    In  FIG. 5A , the second blocking portion  129  is located between the first electrodes  146  and the second liquid crystal layer  144 . Alternatively, the second blocking portion  129  may be located between the third substrate  140  and the first electrodes  146  or at the same layer as the first electrodes  146 . 
         [0063]    The first electrodes  146  may have a rod shape and be parallel. Distances between adjacent two first electrodes  146  may not be the same but different. For example, the distances may increase or decrease in a direction of one side portion to an opposing side portion of the path pixels Pb 1  and Pb 2 . 
         [0064]    A second electrode  148  as a common electrode may be located on an entire surface of the fourth substrate  142 . 
         [0065]    Voltages are supplied to the first electrodes  146  and the second electrode  148 , and an electric field is induced and operates the second liquid crystal layer  144 . The electric field changes according to arrangement of the first electrodes  146 , and thus alignment of the liquid crystal molecules  144   a  of the second liquid crystal layer  144  changes. 
         [0066]    For example, when comparing a first region where the distance between adjacent two first electrodes  146  is large and a second region where the distance between adjacent two first electrodes  146  is small, the electric field at the second region has a component perpendicular to the plane of the substrates  140  and  142  and an intensity more than those of the electric field at the first region. Based upon this, the electric field is varied according to positions, and thus alignment of the liquid crystal molecules  144   a  is varied according to positions. Accordingly, retardation of the second liquid crystal layer  144  is also varied according to positions. This variation of the retardation may cause a retardation plane  144   b  in the second liquid crystal layer  144 . 
         [0067]    In other words, when a ray passes through the second liquid crystal layer  144 , a phase of the ray changes. Further, when the retardation of the second liquid crystal layer  144  is varied according to positions, not only the phase change but also a path change occurs. This path change is similar to refraction at a boundary of two media having different refraction index. Accordingly, the second liquid crystal layer  144  having variation of the retardation may be considered as a lens where the retardation plane  144   b  is a medium boundary. 
         [0068]    Referring to  FIG. 5B , by appropriately arranging the first electrodes  146 , the retardation plane  144   b  may be an oblique line with respect to the plane of the third and fourth substrates  140  and  142 . Accordingly, a ray incident on the path control panel  120  refracts through the retardation plane  144   b.    
         [0069]    Because an oblique angle of the retardation plane  144   b  with respect to the plane of the third and fourth substrates  140  and  142  changes according to the voltage applied to the first electrodes  146 , a refraction angle of the path control panel  120  and the path of the ray passing through the path control panel  120  can be controlled. 
         [0070]    Further, because different voltages can be applied to the first electrodes  146  of the first and second path pixels Pb 1  and Pb 2 , paths of the rays incident on the path control panel  120  can be controlled separately through the corresponding pixels. For example, when a first voltage is applied to the first electrodes  146  of the first path pixel Pb 1  and a second voltage is applied to the first electrodes  146  of the second path pixel Pb 2 , rays perpendicularly incident on the first and second path pixels Pb 1  and Pb 2 , respectively, refract toward the boundary of the first and second path pixels Pb 1  and Pb 2  and are condensed at a point to form a voxel. 
         [0071]      FIG. 6A  is a perspective view illustrating a path control panel of an integral photography type three-dimensional display device according to a second embodiment of the present invention, and  FIG. 6B  is a cross-sectional view taken along a line VI-VI of  FIG. 6A . 
         [0072]    Referring to  FIGS. 6A and 6B , the path control panel  220  may have a different structure from the path control panel of  FIGS. 5A and 5B . The integral photography type three-dimensional display device of the second embodiment may be similar to that of the first embodiment except for the path control panel. 
         [0073]    The path control panel  220  may include third and fourth substrates  240  and  242  and a second liquid crystal layer  244  between the third and fourth substrates  240  and  242 . The path control panel  220  includes first and second path pixels Pb 1  and Pb 2  corresponding to the first and second brightness pixels (Pa 1  and Pa 2  of  FIG. 4 ), respectively. 
         [0074]    Each of the first and second path pixels Pb 1  and Pb 2  includes a first electrode  246  on an inner surface of the third substrate  240 . A second blocking portion  229  may be located at a boundary portion between the first and second path pixels Pb 1  and Pb 2 . The second blocking portion  229  may be located at the same layer as the first electrode  246 . 
         [0075]    Even though not shown in the drawings, the first electrode  246  of each of the first and second path pixels Pb 1  and Pb 2  is connected to a switching element such as a thin film transistor. A voltage applied to the first electrode  246  is controlled according to operation of the switching element. An insulating layer may be located between the second liquid crystal layer  244 , and the first electrode  246  and the second blocking portion  229 . 
         [0076]    In  FIGS. 6A and 6B , the second blocking portion  229  is located at the same layer as the first electrode  246 . Alternatively, the second blocking portion  229  may be located between the third substrate  240  and the first electrode  246  or on the first electrode  246 . 
         [0077]    A prism  250  may be located between the first electrode  246  and the second liquid crystal layer  244 . The prism  250  may have a material having a first refraction index. The prism  250  may have a trigonal shape on the first and second path pixels Pb 1  and Pb 2 . Upper surfaces of the prism  250  are oblique with respect to a plane of the third and fourth substrates  240  and  242 . 
         [0078]    A second electrode  248  as a common electrode may be located on an entire surface of the fourth substrate  242 . 
         [0079]    A first alignment layer contacting the second liquid crystal layer  244  may be located on the upper surfaces of the prism  250 . Further, a second alignment layer contacting the second liquid crystal layer  244  may be located on an inner surface of the fourth substrate  242 . 
         [0080]    Voltages are supplied to the first electrode  246  and the second electrode  248 , and an electric field is induced and operates the second liquid crystal layer  244 . The prism  250  and the second liquid crystal layer  244  refracts a ray according to a refraction index difference between the prism  250  and the second liquid crystal layer  244 . Because a refraction index of the second liquid crystal layer  244  is varied according to the induced electric field, a path of the ray is controlled according to the voltage applied to the first electrode  246 . 
         [0081]    For example, referring to  FIG. 6B , when a first voltage is applied to the first electrode  246  of the first path pixel Pb 1  and the second liquid crystal layer  244  on the first path pixel Pb 1  has a second refraction index different from the first refraction index, a ray perpendicularly incident on the first path pixel Pb 1  of the path control panel  220  refracts and leaves the path control panel  220  obliquely. The path of the ray leaving the path control panel  220  depends on amplitude of the first voltage. 
         [0082]    When a second voltage is applied to the first electrode  246  of the second path pixel Pb 2  and the second liquid crystal layer  244  on the second path pixel Pb 2  has a third refraction index identical to the first refraction index, a ray perpendicularly incident on the second path pixel Pb 2  of the path control panel  220  does not refract and leaves the path control panel  220  perpendicularly. 
         [0083]    The rays passing through the first and second path pixels Pb 1  and Pb 2  are condensed at a point to form a voxel. 
         [0084]    As described above, the refraction index of the second liquid crystal layer  244  is varied according to amplitude of the voltage applied to the first electrode  246  of each path pixel, and the path of the ray incident on each pixel of the path control panel  220  is controlled according to the voltage of each pixel. 
         [0085]    Because different voltages can be applied to the first electrodes  246  of the first and second path pixels Pb 1  and Pb 2 , paths of rays incident on the path control panel  120  can be controlled separately through the corresponding pixels. 
         [0086]    In the embodiments of the present invention, the integral photography type three dimensional display device includes the brightness control panel controlling the brightnesses the incident rays and the path control panel controlling the paths of the incident rays. Accordingly, the three-dimensional image consisting of the partial images integrated can be given sufficient depth range, and thus the three-dimensional image having natural depth information can be displayed. 
         [0087]    It will be apparent to those skilled in the art that various modifications and variations can be made in the display device and a method of displaying an image of embodiments of the invention without departing from the spirit or scope of the invention. Thus, it is intended that embodiments of the invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.