Abstract:
A three dimensional image display device is disclosed. In one embodiment, the device includes: i) a display panel that configured to selectively display one of a left-eye image and a right-eye image, ii) a first polarizing plate positioned on the display panel, and iii) a first retarder positioned on the first polarizing plate. The device also includes a shutter unit opposite to the display unit and including i) shutter spectacles configured to selectively transmit one of the left-eye image and the right-eye image, ii) a second polarizing plate positioned on the shutter spectacles between the shutter spectacles and the display unit, and iii) a second retarder positioned on the second polarizing plate and opposite to the first retarder.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0074210 filed in the Korean Intellectual Property Office on Jul. 30, 2010, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The described technology generally relates to a three dimensional image display device, and more particularly, to a shutter unit including a shutter spectacles and a three dimensional image display device having the same. 
         [0004]    2. Description of the Related Technology 
         [0005]    A three dimensional (3D) image display device generally performs digital sampling and a series of signal processing on image signals transmitted from a video card to display the images. 
         [0006]    In the 3D display device, a video signal scanning method is largely classified into a progressive scanning method or an interlaced scanning method, etc. In the progressive scanning method, an image of one frame is formed of one sheet of field image, while in interlaced scan method, an image of one frame is generally formed of two sheet of field images. 
         [0007]    In addition, a 3D image technology generally uses binocular parallax to provide a sense of a stereoscopic effect of an object, wherein the binocular parallax is generally a major factor in recognizing a stereoscopic effect in a short range. A method of watching the 3D image is largely classified into a method of wearing spectacles (e.g., 3D viewing glasses) and an autostereoscopy method that does not wear spectacles. Among those, as the method of wearing spectacles, there are an anaglyph method of wearing color spectacles of blue and red on both eyes, a polarization method of wearing polarizing spectacles having different polarization directions, and a shutter unit method (or time-division method) of wearing spectacles mounted with including a liquid crystal shutter that periodically repeats a time divided screen and that is synchronized with the period. 
         [0008]    Among others, the shutter unit method implements the 3D image by allowing a display unit of an organic light emitting diode (OLED) display or a liquid crystal display (LCD) to alternately rapidly displaying a left-eye image and a right-eye image and by synchronizing a shutter unit with a display unit to open and close portions corresponding to a left eye or a right eye for a predetermined time. For example, according to the shutter unit method, the operation of opening the left-eye shutter of the shutter unit when the display unit displays the left-eye image and opening the right-eye shutter of the shutter unit when the display unit displays the right-eye image is very rapidly alternately repeated. 
         [0009]    Meanwhile, a polarizing plate is typically attached on the surface of the display unit of the 3D display device In order to receive light emitted from the display unit to the outside through the polarizing plate and forming an image, the polarizing plate is also attached to the surface of the shutter unit. In particular, when the display unit is the liquid crystal display (LCD), the polarizing plate having a linear optical axis is attached to the surface of the display unit in order to implement black and when the display unit is the organic light emitting diode display, the polarizing plate having the linear optical axis is attached to the surface of the display unit in order to minimize the external light reflection. As such, the polarizing plate having the linear optical axis is attached to the display unit and thus, the polarizing plate having the same linear optical axis as the polarizing plate attached to the display unit is also attached to the surface of the shutter unit. 
         [0010]    However, the above 3D device has a problem in causing the difference between the optical axis of light emitted from the display unit and the optical axis of the polarizing plate attached to the surface of the shutter since the light emitted from the display unit through the polarizing plate having the linear optical axis has the linear optical axis when the shutter unit is tilted based on the display unit. 
         [0011]    That is, luminance degrades due to the difference between the polarization direction of the incident light and the polarization direction of the polarizing plate attached to the surface of the shutter unit when the light emitted from the display unit is incident on the shutter unit, in the case where the shutter unit is tilted based on the display unit without being not positioned at the front of the display unit. 
         [0012]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0013]    One inventive aspect is a shutter unit having advantage of minimizing deterioration in luminance and a three dimensional image display device having the same. 
         [0014]    Another aspect is a three dimensional image display device, including: a display unit including a display panel that selectively displays one of a left-eye image and a right-eye image, a first polarizing plate positioned on the display panel, and a first retarder positioned on the first polarizing plate; and a shutter unit opposite to the display unit and including shutter spectacles selectively transmitting one of the left-eye image and the right-eye image, a second polarizing plate positioned on the shutter spectacles between the shutter spectacles and the display unit, and a second retarder positioned on the second polarizing plate and opposite to the first retarder. 
         [0015]    The first retarder and the second retarder may be a ¼ wavelength plate. 
         [0016]    The optical axes of the first polarizing plate and the second polarizing plate may be the same. 
         [0017]    The display panel may include a liquid crystal. 
         [0018]    The display panel may include an organic light emitting diode. 
         [0019]    The display unit may further include a third retarder positioned between the display panel and the first polarizing plate. 
         [0020]    The shutter spectacles may include a first substrate, a second substrate facing the first substrate, and a liquid crystal layer positioned between the first substrate and the second substrate. 
         [0021]    Another aspect is a shutter unit used for a display unit selectively displaying one of a left-eye image and a right-eye image, including: shutter spectacles opposite to the display unit and selectively transmitting only one of the left-eye image and the right-eye image; a polarizing plate positioned on the shutter spectacles between the shutter spectacles and the display unit; and a retarder positioned on the polarizing plate and opposite to the display unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a diagram showing a three dimensional image display device according to a first embodiment. 
           [0023]      FIG. 2  is a block diagram showing the three dimensional image display device according to the first embodiment. 
           [0024]      FIG. 3  is a cross-sectional view showing the three dimensional image display device according to the first embodiment. 
           [0025]      FIG. 4  is a diagram showing a path through which light emitted from a display unit of the three dimensional image display device according to the first embodiment is incident on a shutter unit. 
           [0026]      FIG. 5  is a diagram for explaining an effect of the three dimensional image display device according to the first embodiment. 
           [0027]      FIG. 6  is a diagram showing a three dimensional image display device according to a second embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Embodiments will be described more fully hereinafter with reference to the accompanying drawings. As those skilled in the art would realize, the described embodiments may be modified in various different ways. 
         [0029]    The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
         [0030]    In addition, in describing a second embodiment, components different from the first embodiment will be mainly described. 
         [0031]    In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for understanding and ease of description, but are not considered limiting. 
         [0032]    In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. 
         [0033]    In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. In addition, “˜on” is neither positioned on or below a portion of a target nor positioned on the upper side based on a gravity direction, throughout the specification. 
         [0034]    Hereinafter, a 3D image display device according to a first embodiment will be described with reference to  FIGS. 1 to 5 . 
         [0035]      FIG. 1  is a diagram showing a 3D image display device according to the first embodiment. 
         [0036]    As shown in  FIG. 1 , a 3D image display device  1000  includes a display unit  100  and a shutter unit  200 . 
         [0037]    The display unit  100  may be a liquid crystal display (LCD) and displays a 3D image in an interlaced scanning method. In this case, the interlaced scan method implies a method that divides a 3D image of one frame into a left-eye image and a right-eye image and time-divides a left-eye image and a right-eye image to periodically repeat them. 
         [0038]    The shutter unit  200  has a type of spectacles and is synchronized with the display unit  100  to open and closes portions (a left spectacle lens or a right spectacle lens) corresponding a left eye or a right eye for a predetermined time when the display unit  100  displays the 3D image by time-dividing a left-eye image and a right-eye image. For example, the shutter unit  200  opens a left-eye shutter when the display unit  100  displays a left-eye image and opens a right-eye shutter when the display unit  100  displays a right-eye image. The shutter unit  200  very rapidly alternately repeats the operation. 
         [0039]      FIG. 2  is a block diagram showing the 3D image display device according to the first embodiment.  FIG. 2  is a block diagram showing a configuration of the display unit  100  and the shutter unit  200 . 
         [0040]    As shown in  FIG. 2 , the display unit  100  includes a controller  101  and the shutter unit  200  includes a shutter driver  201 , a left-eye shutter  202 , and a right-eye shutter  203 . 
         [0041]    The controller  101  transmits synchronization signals such as a vertical synchronization signal or a horizontal synchronization signal of a 3D image displayed in the display unit  100  to the shutter driver  201  of the shutter unit  200 . In this case, the synchronization signal may be transmitted and received in wire or wireless. 
         [0042]    In the 3D image display device  1000  according to the first embodiment, the controller  101  may be included in the display unit  100  or in the 3D image display device according to another embodiment, the controller may be positioned at the outside of the display unit  100 . 
         [0043]    The shutter driver  201  receives the synchronization signal of the 3D image from the controller  101  and supplies driving signals to the left-eye shutter  202  and right-eye shutter  203  of the shutter unit  200  to be synchronized with a boundary between the left-eye image and the right-eye image of the 3D image according to the synchronization signal. 
         [0044]    The left-eye shutter  202  and the right-eye shutter  203  of the shutter unit  200  may be opened or closed by the driving signal supplied from the shutter driver  201  and in particular, may be sequentially opened or closes to be synchronized with the boundary between the left-eye image and the right-eye image of the 3D image according to the synchronization signal of the shutter driver  201 . 
         [0045]    Hereinafter, components configuring the display unit  100  and the shutter unit  200 , respectively, will be described in detail with reference to  FIG. 3 . 
         [0046]      FIG. 3  is a cross-sectional view showing the 3D image display device according to a first embodiment. 
         [0047]    As shown in  FIG. 3 , a display unit  100  includes a display panel  110 , a first polarizing plate  120 , a first retarder  130 , a first rear polarizing plate  140  and a light source  150 . 
         [0048]    The display panel  110  selectively displays one of the left-eye image and the right-eye image and includes a first display substrate  111 , a second display substrate  112 , and a first liquid crystal layer  113  positioned between the first display substrate  111  and the second display substrate  112 . 
         [0049]    At least one of the first and second display substrates  111  and  112  may include a substrate made of glass, plastic, or metal, ore the like, a metal pattern formed on the substrate to be used as an electrode, and a color filter, or the like. Longitudinal or transverse electric field is formed in a space between the first display substrate  111  and the second display substrate  112  and the liquid crystal included in the first liquid crystal layer  113  serves as a shutter according to the longitudinal or the transverse electric field. 
         [0050]    The first polarizing plate  120  is positioned between the display panel  110  and the first retarder  130  and has a linear optical axis extending in a first direction. The first polarizing plate  120  serves to pass only light having the linear optical axis extending in the first direction and the light passing through the first polarizing plate  120  has the linear optical axis extending in the first direction. That is, the light emitted to the outside through the display panel  110  is linearly polarized while passing through the first polarizing plate  120 . 
         [0051]    The first retarder  130  is disposed on the first polarizing plate  120  and is a ¼ wavelength plate. The optical axis of the first retarder  130  is tilted by about 45° with respect to the optical axis of the first polarizing plate  120  and the light linearly polarized by passing through the first polarizing plate  120  is circularly polarized by passing through the first retarder  130 . That is, the light sequentially passing through the display panel  110 , the first polarizing plate  120 , and the first retarder  130  is circularly polarized and the 3D image displayed in the display unit  100  is implemented by the circularly polarized light. 
         [0052]    The first rear polarizing plate  140  faces the first polarizing plate  120 , interposing the display panel  110  therebetween and has a linear optical axis extending in the second direction orthogonal to the first direction. The first rear polarizing plate  140  serves to pass only the light having the linear optical axis extending in the second direction and the light passing through the first rear polarizing plate  140  has the linear optical axis extending in the second direction. That is, light emitted from the light source  150  and input to the display panel  110  through the first rear polarizing plate  140  has the linear optical axis extending in the second direction substantially orthogonal to the first direction, while passing through the first rear polarizing plate  140  and when the first liquid crystal layer  113  of the display panel  110  is completely opened, that is, electric field is not generated in the display panel  110 , the light from the light source  150  is absorbed in the first polarizing plate  120  such that the display panel  110  displays black. 
         [0053]    As such, the light emitted from the display unit  100  is circularly polarized, thereby implementing the 3D image. 
         [0054]    The shutter unit  200  may be used as the spectacle form when watching the 3D image implemented from the display unit  100  by using the shutter unit  200  and includes a shutter spectacles  210 , a second polarizing plate  220 , a second retarder  230 , and a second rear polarizing plate  240 . 
         [0055]    The shutter spectacles  210  face the display unit  100  and selectively transmit only one image of the left-eye image and the right-eye image displayed by the display unit  100  to the left eye or the right eye of the user and includes a first spectacles substrate  211 , a second spectacles substrate  212 , and a second liquid crystal layer  213  positioned between the first spectacles substrate  211  and the second spectacles substrate  212 . 
         [0056]    At least one of the first and second spectacles substrates  211  and  212  includes a substrate made of glass or plastic, etc., and a metal pattern formed on the substrate to be used as an electrode and the like. A longitudinal or transverse electric field is formed in a space between the first spectacles substrate  211  and the second spectacles substrate  212  and the liquid crystal included in the second liquid crystal layer  213  serves as the shutter along the longitudinal or transverse electric field. 
         [0057]    The second polarizing plate  220  is disposed on the shutter spectacles  210  and in particular, disposed between shutter spectacles  210  and a second retarder  230 . The second polarizing plate  220  has the linear optical axis extending in the first direction, similar to the first polarizing plate  120 . The second polarizing plate  220  serves to pass only the light having the linear optical axis extending in the first direction and the light passing through the second polarizing plate  220  has the linear optical axis extending in the first direction. That is, the light emitted to the outside through the display panel  110  is linearly polarized, while passing through the second polarizing plate  220 . 
         [0058]    The second retarder  230  is disposed on the second polarizing plate  220  and faces the first retarder  130 . The second retarder  230  is a ¼ wavelength plate, similar to the first retarder  130 . The optical axis of the second retarder  230  is tilted by about 45° with respect to the optical axis of the second polarizing plate  220  and the light emitted and circularly polarized from the display unit  100  is linearly polarized, passing through the second retarder  230 . That is, the light circularly polarized and emitted sequentially passing through the display panel  110 , the first polarizing plate  120 , and the first retarder  130  is again linearly polarized while passing through the second retarder  230 , wherein the linearly polarized light is incident on the shutter spectacles  210  through the second polarizing plate  220 . 
         [0059]    As described above, the circularly polarized light forming the 3D image implemented by the display unit  100  is linearly polarized passing through the second retarder  230  and the linearly polarized light is incident on the shutter spectacles  210  through the second polarizing plate  220 . Thereby, the circularly light emitted from the first display unit  100  and forming the 3D image is incident on the shutter spectacles  210  without deteriorating the luminance. 
         [0060]    The second rear polarizing plate  240  faces the second polarizing plate  220 , interposing the shutter spectacles  210  therebetween and has the linear optical axis extending in the second direction orthogonal to the first direction. The second rear polarizing plate  240  serves to pass only the light having the linear optical axis extending in the second direction and the light passing through the second rear polarizing plate  240  has the linear optical axis extending in the second direction. That is, the light emitted from the display unit  100  and input to the shutter spectacles  210  through the second retarder  230  and the second polarizing plate  220  has the linear optical axis extending in the first direction and when the second liquid crystal layer  213  of the shutter spectacles  210  is completely opened, that is, when the electric field is not generated in the shutter spectacles  210 , the light from the display unit  100  is absorbed in the second rear polarizing plate  240  to display black. 
         [0061]    As such, the circularly polarized light emitted from the display unit  100  is selectively incident on the shutter unit  200  and the user using the shutter unit  200  recognizes the 3D image. 
         [0062]    Hereinafter, the path of light from the above-mentioned display panel  110  to the shutter spectacles  210  will be described in detail with reference to  FIG. 4 . 
         [0063]      FIG. 4  is a diagram showing a path through which light emitted from a display unit of the 3D image display device according to the first embodiment is incident on a shutter unit. 
         [0064]    As shown in  FIG. 4 , the light (L) passing through the display panel  110  is linearly polarized in the first direction that is the optical axis direction of the first polarizing plate  120 , while passing through the first polarizing plate  120 . The linearly polarized light is changed into the circular polarization while passing through the first retarder  130  that is a ¼ wavelength plate to display the 3D image. That is, the display unit  100  emits the circularly polarized light to display the 3D image. 
         [0065]    The circularly polarized light is linearly polarized in the first direction, while passing through the second retarder  230  of the shutter unit  200 . The linearly polarized light is incident on the shutter spectacles  210  while passing through second polarizing plate  220  having the optical axis of the first direction. 
         [0066]    That is, the linearly polarized light passing through the first polarizing plate  120  is again circularly polarized and then linearly polarized again, passing through the first retarder  130  and the second retarder  230  and the linearly polarized light is incident on shutter spectacles  210  through the second polarizing plate  220 , thereby not deteriorating the luminance until the linearly polarized light passing through the first polarizing plate  120  of the first display unit  100  passes through the second polarizing plate  220  of the shutter unit  200 . 
         [0067]      FIG. 5  is a diagram for explaining an effect of the 3D image display device according to the first embodiment. 
         [0068]    In addition, even in the state where the shutter unit  200  is face to face with the display unit  100  shown in  FIG. 5A  and in the state where the shutter unit  200  is tilted with respect the display unit  100  shown in  FIG. 5B , the light emitted from the display unit  100  is circularly polarized and the circularly polarized light is incident on the shutter unit  200  in the circularly polarized state, such that the difference between the optical axis of light emitted from the display unit  100  and the optical axis of the second polarizing plate  220  attached to the surface of the shutter unit  200  does not occur. In other words, the light linearly polarized passing through the first polarizing plate  120  of the first display unit  100  is circularly polarized, passing through the first retarder  130  and is input to the shutter unit  200  and the circularly polarized light incident on the shutter unit  200  is again linearly polarized, passing through the second retarder  230  and is input to the shutter spectacles  210  through the second polarizing plate  220 , thereby not deteriorating the luminance until the light emitted from the display unit  100  is incident on the shutter unit  200 . 
         [0069]    As described above, in the 3D image display device  1000  according to the first embodiment, the display unit  100  has the first polarizing plate  120  having the linear optical axis, the shutter unit  200  has the second polarizing plate  220  having the linear optical axis, and the deterioration of the luminance is minimized when the light emitted from the display unit  100  is incident on the shutter unit  200  even though the shutter unit  200  is tilted to the display unit  100 . 
         [0070]    Hereinafter, 3D image display device  1002  according to a second embodiment will be described with reference to  FIG. 6 . 
         [0071]      FIG. 6  is a diagram showing a 3D image display device according to a second embodiment. 
         [0072]    As shown in  FIG. 6 , the display unit  100  includes an organic light emitting diode (OLED) display, includes a display panel  110 , a first polarizing plate  120 , a first retarder  130 , and a third retarder  160 . 
         [0073]    The display panel  110  includes the first display substrate  111 , the second display substrate  112  and the organic light emitting diode  114  positioned between the first display substrate  111  and the second display substrate  112 . The organic light emitting diode  114  is a self-light emitting element and light-emits the organic light emitting layer included in the organic light emitting diode  114  to display the 3D image. 
         [0074]    The third retarder  160  is positioned between the display panel  110  and the first polarizing plate  120  and is the ¼ wavelength plate. The optical axis of the third retarder  160  is further tilted by 45° with respect to the optical axis of the first polarizing plate  120  and the light linearly polarized passing through the first polarizing plate  120  from the outside is circularly polarized, passing through the third retarder  160 . As such, the external light is linearly polarized in the polarization direction of the first polarizing plate  120 , passing through the first polarizing plate  120  and the linearly polarized light is again circularly polarized, passing through the third retarder  160  that is a ¼ wavelength plate. As an example, when the circular polarization is the left circular polarization, the left circular polarized light is reflected by the electrodes configuring the organic light emitting diode  114  in the display panel  110 , such that the phase of the left circular polarized light is changed by 180° into the right circular polarized light. The light changed into the right circular polarization is linearly polarized again passing through the third retarder  160  and the axial direction of the linearly polarized light is a direction opposite to the optical axis direction of the first polarizing plate  120 , which is absorbed in the first polarizing plate  120  as it is. 
         [0075]    That is, the third retarder  160  is disposed between the display panel  110  and the first polarizing plate  120  to minimize the external light reflection due to the display panel  110 , thereby suppressing the deterioration of the image quality of the 3D image display device  1002 . 
         [0076]    At least one of the disclosed embodiments minimizes luminance deterioration in displaying 3D images. 
         [0077]    The disclosed embodiments are not considered limiting and are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.