Patent Publication Number: US-10317692-B2

Title: Stereoscopic display for naked eyes

Description:
FIELD OF THE INVENTION 
     The present application relates to a display technology field, and more particularly to a stereoscopic display for naked eyes. 
     BACKGROUND OF THE INVENTION 
     A new dimension is introduced in the stereoscopic display technology in the basis of the flat panel display technology; the three-dimensional display is formed and closer to the real world perception and become the popular in the electronic display technology in recent years. 
     The current mainstream of the stereoscopic display for naked eyes is mainly based on a Liquid Crystal Display, LCD or an organic Light-Emitting Diode, OLED display, wherein the LCD display is mainly based on the polarized light control technology, and OLED display is for filtering the influence of the reflecting light from the ambient light through the backside electrode, a quarter-wave plate and a polarizer are placed on the display panel. So whether is the LCD or the OLED displays are based on the output of the linearly polarized light. The stereoscopic display technology for naked eyes are adapted and based on the vision cheating technology by the binocular parallax, the linearly polarized light emitting from the LCD or OLED display is split, to form a stereoscopic display effect. However, this stereoscopic display technology for naked eyes based on the linearly polarized light is easy to cause the human visual fatigue and visual disturbances, and affect people&#39;s visual health. 
     SUMMARY OF THE INVENTION 
     The present invention to solve the technical problem is to provide a stereoscopic display for naked eyes to relieve the visual fatigue and visual disturbances problems caused by the conventional linear polarized light of the stereoscopic display for naked eyes. 
     In order to solve the above technical problems, one technology approach of the present application is to provide a stereoscopic display for naked eyes, including: 
     a two-dimensional display panel, a stereoscopic module for the naked eyes and a light converting module, wherein the stereoscopic module for the naked eyes is deposited between the two-dimensional display panel and the light converting module; 
     the two-dimensional display panel is used to output a two-dimensional image based on the linearly polarized light; 
     the stereoscopic module for the naked eyes is used to output a three-dimensional image based on the linearly polarized light; and 
     the light converting module is used to convert the linearly polarized light to a circularly polarized light and output a three-dimensional image based on the circularly polarized light. 
     Wherein light converting module further including at least one quarter-wave plate, and the quarter-wave plate convert the linearly polarized light to a circularly polarized light. 
     Wherein the light converting module further including an adhesive layer, a first protective layer, a quarter-wave plate, a half-wave plate, and a second protective layer sequentially laminated. 
     Wherein the difference of the refractive index of the quarter-wave plate is positively correlated with the wavelength of the linearly polarized light. 
     Wherein the light converting module is a liquid crystal type circularly polarization controller and the liquid crystal type circularly polarization controller further including a voltage control circuit and a liquid crystal cell; 
     the voltage control circuit is modulated the voltage of the liquid crystal cell to convert the inputted linearly polarized light into a circularly polarized light by the liquid crystal cell. 
     Wherein light converting module is a slit, a cylindrical lens or a liquid crystal lens. 
     Wherein the two-dimensional display panel is a LCD display, and the LCD display including a backlight module, a first polarizer, a first substrate, a liquid crystal layer, a second substrate, a second polarizer; 
     The first polarizer is positioned between the backlight module and the first substrate; the second polarizer is located between the second substrate and the stereoscopic module for naked eyes; and the liquid crystal layer is filled between the first substrate and the second substrate. 
     Wherein the first substrate is a thin-film transistor, TFT array substrate and the second substrate a color filter substrate. 
     Wherein the two-dimensional display panel is an OLED display, a quarter-wave plate and a polarizer; 
     The quarter-wave plate is disposed between the OLED display and the polarizer; 
     Wherein the OLED display including a substrate, an anode, a conductive layer, an emission layer and a cathode stacked in this order. 
     Comparing to conventional technology, the advantage of the present application of the stereoscopic display for naked eyes includes a two-dimensional display panel, a stereoscopic module for the naked eyes and a light converting module. The stereoscopic module for the naked eyes is deposited between the two-dimensional display panel and the light converting module. The two-dimensional display panel is used to output a two-dimensional image based on the linearly polarized light; the stereoscopic module for the naked eyes is used to output a three-dimensional image based on the linearly polarized light. The light converting module is used to convert the linearly polarized light to a circularly polarized light and output a three-dimensional image based on the circularly polarized light. By the process mentioned above to add the light converting module added to the base of the conventional stereoscopic display for the naked eyes. The linearly polarized light output from the conventional stereoscopic display for the naked eyes is changed into circularly polarized light to simulate natural light with completely unpolarized state, thus alleviating the human visual fatigue and visual disturbances and achieve a healthy eye. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly illustrate the embodiments of the present application or prior art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present application, those of ordinary skill in this field can obtain other figures according to these figures without paying the premise. 
         FIG. 1  is a schematic view of the structure of the stereoscopic display for naked eyes according to the first embodiment of the present application; 
         FIG. 2  is a principle diagram illustrated the slits of the stereoscopic display for naked eyes according to the first embodiment of the present application; 
         FIG. 3  is a principle diagram illustrated the cylindrical lens of the stereoscopic display for naked eyes according to the first embodiment of the present application; 
         FIG. 4  is a principle diagram illustrated the stereoscopic module for the naked eyes of the stereoscopic display for naked eyes according to the first embodiment of the present application; 
         FIG. 5  is a dispersion characteristic diagram of the quarter-wave plate of the stereoscopic display for naked eyes according to the first embodiment of the present application; 
         FIG. 6  is a schematic view of the structure of the stereoscopic display for naked eyes according to the second embodiment of the present application; and 
         FIG. 7  is a schematic view of the structure of the stereoscopic display for naked eyes according to the third embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Embodiments of the present application are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. It is clear that the described embodiments are part of embodiments of the present application, but not all embodiments. Based on the embodiments of the present application, all other embodiments to those of ordinary skill in the premise of no creative efforts obtained should be considered within the scope of protection of the present application. 
     Specifically, the terminologies in the embodiments of the present application are merely for describing the purpose of the certain embodiment, but not to limit the invention. Examples and the claims be implemented in the present application requires the use of the singular form of the book “an”, “the” and “the” are intend to include most forms unless the context clearly dictates otherwise. It should also be understood that the terminology used herein that “and/or” means and includes any or all possible combinations of one or more of the associated listed items. 
     Referring to  FIG. 1 , the structure of the stereoscopic display for naked eyes according to the first embodiment of the present application includes: 
     A two-dimensional display panel  11 , a stereoscopic module for the naked eyes  12  and a light converting module  13 , the stereoscopic module for the naked eyes  12  is deposited between the two-dimensional display panel  11  and the light converting module  13 . 
     The two-dimensional display panel  11  is used for outputting two-dimensional image based on the linear polarized light; the stereoscopic module for the naked eyes  12  is for outputting a three-dimensional image based on the linearly polarized light; the light converting module  13  is for converting the linearly polarized light into a circularly polarized light and to output a three-dimensional image based on the circularly polarized light. 
     In particular, the current mainstream of the two-dimensional display panel  11  is LCD display or OLED display. The LCD display is based on polarized light control technology, the light emitted from the backlight module is filtered by a polarizer and into the liquid crystal layer. The polarization of the light is selectively converted by the liquid crystal layer according to the image content, the converted light is further transmitted or obscured by the filter of the polarizer, the transmitted light passed into the stereoscopic module for the naked eyes  12 . From this, the light entered into the stereoscopic module for the naked eyes  12  is linearly polarized light. The OLED display is a self light-emitting organic electroluminescent device, the light emitted from the OLED display is not a polarized light which is closer to a natural light. But in order to filter the impact of reflected light from the ambient light through the cathode of the OLED display (also known as the back electrode), a polarizer is usually required and placed on top of the OLED display. The light emitted by the OLED display, pass the polarizer and output a linearly polarized light, so the light enters the stereoscopic module for the naked eyes  12  is remains a linearly polarized light. 
     The stereoscopic module for the naked eyes  12  is a slit, a cylindrical lens or a liquid crystal lens, by splitting the linearly polarized light outputted by the two-dimensional display panel  11  to achieve a three-dimensional image output of the left and right eye, the light passing the stereoscopic module for the naked eyes  12  is still a linearly polarized light. 
     Wherein, as shown in  FIG. 2 , the stereoscopic module for the naked eyes  12  is a slit  121 , the split process is as followed: a slit  121  with a suitable parameter is placed in front of the two-dimensional display panel  11 . The two dimensional image content with a specific parallax occlusion and output from the two-dimensional display panel  11  is selectively sheltered. After a certain distance, the light reaches the human eye can be separated. The eyes receive two images with parallax, and the three-dimensional effect is produced. 
     As shown in  FIG. 3 , the stereoscopic module for the naked eyes  12  is a cylindrical lens  122 , the split process is as followed: The principle of the cylindrical lens  122  is similar to the slit  121 . By the light refraction of the cylindrical lens  122 , the two dimensional image content with a specific parallax occlusion and outputted from the two-dimensional display panel  11  is refracted to different place in the air, the image content reaches the human eye is separated. The eyes receive two images with parallax, and the three-dimensional effect is produced. 
     The liquid crystal lens is based on the single optical axis and the birefringent properties of the liquid crystal to produce. The liquid crystal lens is controlled by the electric signal. By controlling the input of the voltage to the liquid crystal lens or not, two-dimensional/three-dimensional state transition can be achieved. 
     Therefore, the linear polarized light output from the two-dimensional display panel  11  passes the slit, the cylindrical lens or the liquid crystal lens to achieve split light and make the left eye and the right eye to receive two images with parallax, No light is phase transformed or other process, so the light passed the stereoscopic module for the naked eyes  12  is still a linearly polarized light. 
     In other embodiments, the stereoscopic module for the naked eyes  12  can also use other implementation structure and implementation, in order to achieve the transition of the two-dimensional to the three-dimensional image, and is not limit to the above-mentioned three kinds of the stereoscopic module for the naked eyes  12 , and the stereoscopic module for the naked eyes  12  can also include some auxiliary elements. 
     One important direction of the display technology is reproducing the way that human cognitive the world. In general, the human eye perceives information mainly through the natural light with completely non-polarization light. The more the light is close to the natural light, the less damage to the human eye. Within the polarization light, the polarization property of the circularly polarized light is closest to the natural light. 
     In the conventional stereoscopic display for naked eyes, after the two-dimensional image through the conversion of the stereoscopic module for naked eyes to a three-dimensional image, the image is direct outputting to reach the human eye. The three-dimensional image based on the linearly polarized light is perceived by the human eye. The relevant objective and subjective experiments have revealed an impact of the linearly polarized light to the human visual fatigue and visual impairment. Therefore, if the three-dimensional image of linearly polarized light is changed into circularly polarized light, and the circularly polarized light is directly perceived by the human eye, the visual fatigue caused by light will be greatly eased, and is conducive to visual health. 
     In this embodiment, a light conversion module  13  is added basing on the conventional stereoscopic display for naked eyes. The light conversion module  13  converts the linearly polarized light into the circularly polarized light to output a three-dimensional image based on the circularly polarized light. 
     At least one quarter-wave plate  131  is selected as a light conversion module  13 . As shown in  FIG. 4 , when the linearly polarized light perpendicular incident into the quarter-wave plate  131 , and the angleθbetween the polarization direction of the light (as the direction along the OA direction shown in  FIG. 4 ) and the optical axis direction of the quarter-wave plate  131  (as the direction along the OA2 direction shown in  FIG. 4 ) is 45°, the outputting light is a circularly polarized light. In this embodiment, the quarter-wave plate satisfies the phase delay formula: 
     
       
         
           
             
               
                 
                   
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     Where λ is the wavelength of the linearly polarized light, Δn is the difference of the refractive index, d is the thickness of the quarter-wave plate. 
     In order to achieve the conversion of the linear polarized light in all wavelength range into a nearly ideal circularly polarized light, the difference of the refractive index of the quarter-wave plate is positively correlated with the wavelength. With the increasing of the wavelength, it will have the dispersion characteristics of the reverse wavelength, as shown in  FIG. 5 . 
     In can be understood that, the two-dimensional image based on the linearly polarized light is outputted by the two-dimensional display panel  11  of the stereoscopic display for naked eyes in the first embodiment of the present invention, and by pass the stereoscopic module for the naked eyes  12  to output the three-dimensional image based on the linearly polarized light. The linearly polarized light is further pass the light conversion module  13  to output the three-dimensional image based on the circularly polarized light. In this way, the human eye direct perception of circularly polarized light close to natural light, to alleviate the human visual fatigue and visual disturbances, achieve a healthy eye. 
     Referring to  FIG. 6 , is a stereoscopic display for naked eyes according to the second embodiment of the present application including a two-dimensional display panel  21 , a stereoscopic module for naked eyes  22  and a light conversion module  23 . 
     In particular, in this embodiment, the two-dimensional display panel  21  is a LCD display  21 . The LCD display  21  includes a backlight module  201 , a first polarizer  202 , a first substrate  203 , a liquid crystal layer  204 , a second substrate  205 , a second polarizer  206 . 
     The first polarizer  202  is positioned between the backlight module  201  and the first substrate  203 . The second polarizer  206  is located between the second substrate  205  and the stereoscopic module for naked eyes  22 . The liquid crystal layer  204  is filled between the first substrate  203  and the second substrate  205 . The first polarizer  202  and the second polarizer  206  control the backlight module  201  and the liquid crystal layer  204  to output the polarized light, wherein the first substrate  203  is selected as a thin-film transistor, TFT array substrate  203  and the second substrate  205  is selected as a color filter substrate  205 . 
     The Light emitted from the backlight module  201  is passing through the first polarizer  202  and enters into the liquid crystal layer  204 . The liquid crystal layer  204  is located between the TFT substrate  203  and the CF substrate  205 . By the driving of the electric field, the liquid crystal molecules are twisted nematic in order to achieve the control of the polarization state of light, these light is filter by the CF substrate  205 , and then through the second polarizer  206  and injected outward, thus forming a two-dimensional image. For example, in the absence of the electric field, the light emitted from the backlight module  201  passing through the first polarizer  202  and passes the liquid crystal layer  204 . Under the action of the liquid crystal layer  204 , the light is rotated by a certain angle, when leaving the liquid crystal layer  204 , the polarization direction of the light is the same with the direction of the second polarizer  206  and the light is smoothly passing through. The passed light is the linearly polarized light after being polarized. When the electric field is applied, the liquid crystal layer  204  lost its rotatory capability, after the light emitted by the backlight module  201  through the first polarizer  202 , the polarization direction of the light is perpendicular to the second polarizer  206  and cannot be passed, and having an image with the variation of the dark or light by by controlling the switches of the electric field. Thus, LCD displays  21  output of the two-dimensional image based on the linearly polarized light. 
     The light emitted from the second polarizer  206  is splitting by the stereoscopic module for naked eyes  22  and output of the three-dimensional image based on linearly polarized light. The Light conversion module  23  includes an adhesive layer  207 , a first protective layer  208 , a quarter-wave plate  209 , a half-wave plate  210 , and a second protective layer  211  sequentially laminated. Wherein the quarter-wave plate  209  and the half-wave plate  210  are interposed between the first protective layer  208  and the second protective layer  211  to have a protective effect. The material of the first protective layer  208  and the second protective layer  211  can be optionally the same or different materials. The quarter-wave plate  209  can realize converting the linearly polarized light into the circularly polarized light. The half-wave plate  210  is used as a wide view angle compensating plate. An optional the adhesive layer  207  can be selected for the adhesion of the first protective layer  208  and the stereoscopic module for naked eyes  22 . 
     In can be understood that the stereoscopic display for naked eyes in the second embodiment of the present invention is take the two-dimensional display panel  21  as the LCD display  21  an example. The LCD display  21  outputs a two-dimensional image based on linearly polarized light. After the splitting of the stereoscopic module for the naked eyes  12  to output the three-dimensional image based on the linearly polarized light. By the quarter-wave plate  209  in the light conversion module  23  to achieve the conversion to the circularly polarized light. The human eye direct perception of circularly polarized light close to natural light, to alleviate the human visual fatigue and visual disturbances, achieve a healthy eye. 
     Referring to  FIG. 7 , is a stereoscopic display for naked eyes according to the third embodiment of the present application including a two-dimensional display panel  31 , a stereoscopic module for naked eyes  32  and a light conversion module  33 . 
     In particular, in this embodiment, the two-dimensional display panel  31  is an OLED display  300 , a quarter-wave plate  306  and a polarizer  307 . The quarter-wave plate  306  is disposed between the OLED display  300  and the polarizer  307 . 
     Wherein, the OLED display  300  includes a substrate  301 , an anode  302 , a conductive layer  303 , an emission layer  304  and a cathode  305  stacked in this order. The voltage is applied between the cathode  302  and the anode  300  of the OLED display  305 . The electrons is flow from the cathode  305  to the anode  302 . The electrons and holes are combined in the junction of the conductive layer  303  and the emitter layer  304 . The electrons release energy in the form of photons and OLED display  300  emits light. Therefore, the OLED display  300  is a self-luminous organic electroluminescent device, which emitted not polarized light, but relatively close to natural light. 
     In the OLED display  300 , the cathode  305  is typically made of a metal material of aluminum, having a high reflection characteristic. A reflection is formed after the entering of the ambient light, and interference the image signal. Therefore, in order to filter the influence of the reflected ambient light by the cathode  305  of the OLED display  300  and to improve the image quality. The quarter-wave plate  306  and the polarizer  307  is disposed on the OLED display  300  sequentially. The ambient light passes the polarizing plate  307  and forms the polarized light, and then pass through the quarter-wave plate  306  and becomes a right-handed circularly polarized light or a left-handed circularly polarized light. The circularly polarized light is reflected by the surface of the cathode  305  and convert into another circularly polarized light and pass the quarter-wave plate  306  again and form a perpendicular polarized light, and cannot pass the polarizing plate  307 . After the reflection of the ambient light, no light is outputted, and thus will not affect the image quality. 
     By disposing the quarter-wave plate  306  and the polarizer  307  on the OLED display  300 , since the light emitted from the OLED display is close to the natural light, and will not change after passing the quarter-wave plate  306 . Then the light pass through the polarizer  307  and form the linearly polarized light, and finally output the two-dimensional image based on the linearly polarized light. 
     The light is splitting by the stereoscopic module for naked eyes  32 , form a three-dimensional effect and output of the three-dimensional image based on linearly polarized light. 
     The Light conversion module  33  includes a liquid crystal type circularly polarization controller  33 . The liquid crystal type circularly polarization controller  33  includes a voltage control circuit  309  and a liquid crystal cell  308 . 
     The liquid crystal material has electrically controlled birefringence property. The modulation of the voltage of the liquid crystal cell  308  is controlled by the voltage control circuit  309 . As the voltage changes from small to large, the birefringence Δn1 will have a monotonic changing curve. Assuming that the wavelength of the incident light is λ1, the thickness of the liquid crystal cell is d1. By the controlling of the AC voltage outputted from the voltage control circuit  309  and after the incident light pass through the liquid crystal cell  308 , the phase difference is generated as δ=2πd1Δn1/λ1. Modulating the AC voltage to make the δ is π/2. The incident light pass through the liquid crystal cell  308  and its phase difference will be π/2. In this embodiment, the incident light is the linearly polarized light output form the stereoscopic module for naked eyes  32 , the linearly polarized light pass the liquid crystal cell  308  and output a circularly polarized light and finally output the three-dimensional image based on circularly polarized light. 
     In can be understood that the stereoscopic display for naked eyes in the third embodiment of the present invention is by the self emitting light from the OLED device  300 , the self emitting light pass the quarter-wave plate  306  and the polarizer  307  then output a two-dimensional image based on linearly polarized light. After the splitting of the stereoscopic module for the naked eyes  32  to achieve the three-dimensional image based on the linearly polarized light. The light is further converted by the liquid crystal type circularly polarization controller  33  and output a three-dimensional image based on the circularly polarized light. The human eye direct perception of circularly polarized light, to alleviate the human visual fatigue and visual disturbances, achieve a healthy eye. 
     Above are embodiments of the present application, which does not limit the scope of the present application. Any modifications, equivalent replacements or improvements within the spirit and principles of the embodiment described above should be covered by the protected scope of the invention.