Abstract:
The present invention relates to a structure of the liquid crystal display comprises a back light unit, a main display panel formed in the side of the back light unit and a sub display panel formed in the other side of the back light unit and a diffused film formed between the main display panel and the sub display panel. The diffused film is able to be passed by one polarized light which has the specific direction and reflex the other polarized light which is vertical with the specific direction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a structure of a dual-display LCD, and more particularly, to a structure of a dual-display LCD to prevent a shadow of a main display panel.  
         [0003]     2. Description of the Prior Art  
         [0004]     The LCD is a thin and save electricity flat display, it uses the different liquid crystal revolving angles and the polarized light layer beside the liquid crystal to control the transmittance. The brightness is controlled by the transmittance. When the color is constant, the liquid crystal is steadfast, that is why the LCD has stable appearance and no twinkle. Because of the above-mentioned advantages, the LCD applies in popularly scope i.e., the mobile phone, PDA, notebook and the digital camera. Owing to new products enter the market fast, the technology of the LCD improves. The least fashion is dual-display LCD applies in various products.  
         [0005]     For example, many displays shell type mobile phones are dual-display with liquid crystal displays. The dual-display LCD has a main display panel and a sub display panel. The sub display panel emits light from a rear cover of the mobile phone, shows a simple words or an images, and the uses will realize the base information form the sub display panel before they answer the phone. Besides, the main display panel positions in the mobile phone to show a main and complex words and image.  
         [0006]     Please refer to  FIG. 1 ,  FIG. 1  is a liquid crystal display  100  has a single light guide plate  102  according to the prior art. The liquid crystal display  100  has one light guide plate  102  applies for a dual display mobile phone. A light path is beginning from the light guide plate  102  and divides into two paths, one is toward a main display panel  114 , the other one is toward a sub display panel  134 .  
         [0007]     When a light is shot from a light source into a light guide plate  102 , the light guide plate  102  will guide the light to divide into the above-mention two paths into the main display panel  114  and the sub display panel  134 . In  FIG. 1 , only drawing paths I and II illustrate. As  FIG. 1  shown, the paths I and II are shot toward the main display panel  114  and the sub display panel  134  individually. In path II, the light is shot into light guide plate  102  and sequentially gets into a diffuser  112 , a horizontal prism sheet  114 , a vertical prism sheet  116 , and the light without a frame  116  and a shade tape  131  covers is able to reach the sub display plane  134 . The sub display plane  134  comprises a first polarized light layer  133 , a second polarized light layer (not shown), two base plates (not shown) and liquid crystal (not shown). Besides, the first polarized light layer  133  divides the light into a P polarized light and a S polarized light, absorbs one of the P polarized light and the S polarized light. In  FIG. 1 , the S polarized light is absorbed and only the P polarized light gets into the sub display panel  134 .  
         [0008]     According to path I, the light is shot into light guide plate  102  and sequentially gets into the diffuser  122 , the horizontal prism sheet  124 , the vertical prism sheet  126 , and the light is reflected by the frame  128 , the light shoots into the diffuser  104 , the horizontal prism sheet  106 , the vertical prism sheet  108 , the diffuser  110 , and the light without the shade tape  112  covers is able to reach the main display plane  114 , finally, the light is filter by the polarized light layer  113  and shoot from the main display panel  114 .  
         [0009]     Because the liquid crystal display  100  has single light guide plate, the main display panel  114  and the display panel  134  use the same light guide plate  102  and light source, the light into the light guide plate  102  needs to divide to the main display panel  114  and the sub display panel  134 , that is why the main display panel  114  has less light source and get shadow, and how to decrease the shadow of the main display panel  114  happen is important issue in the dual display LCD manufacturer.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention relates to a structure of a dual-display LCD has a film to solve the above-mention shadow of the main display panel.  
         [0011]     The embodiment of the present invention relates to a structure of the liquid crystal display. It comprises a back light unit, a main display panel formed in the side of the back light unit and a sub display panel formed in the other side of the back light unit and a diffused film formed between the main display panel and the sub display panel. The diffused film is able to be passed by one polarized light which has the specific direction and reflex the other polarized light which is vertical with the specific direction.  
         [0012]     The LCD of the present invention has the film and the main display panel has more polarized light reflects from the film. The present invention decreases the shadow happening of the main display panel and the main and sub display panel both have enough light.  
         [0013]     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a liquid crystal display has a single light guide plate according to the prior art.  
         [0015]      FIG. 2  is a liquid crystal display has a single light guide plate according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Please refer to  FIG. 2 ,  FIG. 2  is a liquid crystal display  200  has a single light guide plate  202  according to the present invention. The liquid crystal display  200  has one light guide plate  202  applies for a dual display mobile phone. The liquid crystal display  200  comprises a main display panel  214  on the side of a backlight module  236 , a shade tape  212 , a backlight module  236 , a frame  228 , a film  230 , a shade tape  232 , and a sub display panel  234  on a side of the backlight module  236  without the main display panel  214 . The backlight module  236  comprises a light source, a light guide plate  202 , diffusers  210 ,  222 ,  204 ,  222 , and a prism sheets  208 ,  206 ,  224 ,  226 . The light guide plate  202  is made from propylene and has functions of guiding light and controlling light uniform. The diffusers  210 ,  222 ,  204 ,  222  has scatter particles are able to diffuse the light. Furthermore, the prism sheet  208 ,  224 ,  226  are made form poly carbonic ester and are able to condense the light to increase brightness. Moreover, the film  230  could use 3M&#39;s reflective dual brightness enhancement film (DBEF) and Nitto&#39;s polarization conversion film (PCF) or any new material to achieve the same function of polarizing and reflecting the light.  
         [0017]     A light path is beginning from the light guide plate  202  and divides into two paths, one is toward a main display panel  214 , the other is toward a sub display panel  234 . A multi-layer structure between the main display panel  214  and the sub display panel  234  is backlight module in  FIG. 2 .  
         [0018]     When a light is shot from a light source into a light guide plate  202 , the light guide plate  202  will guide the light to divide into the above-mention two paths into the main display panel  214  and the sub display panel  234 . In  FIG. 2 , only drawing paths I′ and II′ illustrate. In path I′, the light is shot into light guide plate  202  and sequentially gets into a diffuser  222 , a horizontal prism sheet  224 , a vertical prism sheet  226 , and the light reflects from a frame  228  into the light guide plate  202 , the light gets into the diffuser  204 , a horizontal prism sheet  206 , a vertical prism sheet  208 , a diffuser  210 , finally, the light without a shade tape  232  covers is able to reach the main display plane  214  and gets out form the main display plane  214 .  
         [0019]     In Fig. II′, the light is shot into light guide plate  202  and sequentially gets into a diffuser  222 , a horizontal prism sheet  224 , a vertical prism sheet  226 , and the light without a frame  228  cover will get into the opening  229  and a film  230 . The film  230  is an optics film has function of polarizing and reflecting the light. When the light gets into the film  230 , the film  230  will permit a specific direction polarized light pass and reflect a vertical specific direction polarized light. As  FIG. 2  shown, the film  230  divides the light into a P polarized light and a S polarized light, the P polarized light will pass the film and keep going, but the S polarized light will be reflected. The P polarized light without the shade tape  232  cover will shoot into the sub display panel  234 . The transmit axle of the polarized light layer  232  is parallel with the P polarized light, that causes the P polarized light could pass through the polarized light layer  232  into a liquid crystal of the sub display panel  234  to show an image. In the other words, the S polarized light is reflected into the light guide plate  202  as path III′ of  FIG. 2  shown. Because a transmit axle of the polarized light layer  213  of the main display panel  214  is vertical with a transmit axle of the polarized light layer  233  of the sub display panel  234 , the S polarized light is reflected into the main display panel  214  to produce image.  
         [0020]     Deserving to mention is the light source of the present invention could change amount and position according to the demands. The light source is made from the cold cathode fluorescent (CCFL) and LED. Moreover, the prism sheets  206 ,  208 ,  224  and  226  are composed by a section of the parallel sheet and the vertical sheet to condense the light and increase brightness. Except the embodiment mentioned prism sheet, the lecticular sheet could achieve the same effect. Furthermore, the liquid crystal display  200  according to the present invention could change a material and a sequence of the backlight module.  
         [0021]     Because the liquid crystal display  200  has the single light guide plate according to the present invention comprises the film  230 , the main display panel  214  has the path I′ light and the path III′ light. Comparing to the prior art, the main display panel  114  of the prior art only has the path I light. The present invention could give the main display panel  214  enough light source and the shadow is not produce easily. Besides, the sub display panel  234  of the present invention could use the path II′ light as the prior art does, so the present invention prevent the shadow to happen and give enough light to the main display panel  214  and the sub display panel  234 .  
         [0022]     In the short words, the present invention sets the film before the light go through the sub display panel, the polarized light could not pass through the first polarized light layer of the sub display panel will reflect to the light guide plate. The first transmit axle of the main display panel is vertical with the first transmit axle of the sub display panel, the polarized light could get into the main display panel. Comparing to the prior art, the present invention increases the brightness of main display panel and decreases the shadow happen. In the same time, the light guide plate and the backlight module are not responsible to improve the problem of the shadow of the main display panel.  
         [0023]     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.