Abstract:
An exemplary transflective display ( 100 ) has a first substrate ( 110 ); a second substrate ( 120 ); and a plurality of pixels defined between the first substrate and the second substrate. Each pixel has an organic light emitting diode (OLED) region and a liquid crystal display (LCD) region adjacent to the OLED region.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to displays, and more particularly to a transflective display having an OLED region and an LCD region.  
         [0003]     2. General Background  
         [0004]     Recently, LCDs that are light and thin and have low power consumption characteristics have been widely used in office automation equipment, video units and the like. Among LCD products, there have been the following three types of LCD devices commercially available: a reflection type LCD device utilizing ambient light, a transmission type LCD device utilizing backlight, and a transflective type LCD device equipped with a half mirror and a backlight.  
         [0005]     With a reflection type LCD device, a display becomes less visible in a poorly lit environment. In contrast, a display of a transmission type LCD device appears hazy in strong ambient light (e.g., outdoor sunlight). Thus researchers sought to provide an LCD device capable of functioning in both modes so as to yield a satisfactory display in any environment. In due course, a transflective type LCD device was developed. In general, an LCD can&#39;t self emit light beams, which needs a surface light source to provide even light for a clear display. However, the surface light source is weighty, which influences an inconvenience of installing or conveyance. The question becomes serious especially for a large-screen LCD display.  
         [0006]     Organic light emitting diodes (OLEDs) are electronic devices that emit light in response to an applied potential.  FIG. 4  illustrates a typical OLED. The OLED has a substrate  10 , a metallic anode layer  11 , a hole-injecting layer  12 , a hole-transmitting layer  13 , a light emitting layer  14 , an electron-transporting layer  15 , an electron-injecting layer  16 , and a metallic cathode layer  17 , which are formed in that order from bottom to top. In operation, a potential is provided on the metallic anode layer  11  and the metallic cathode layer  17 , which makes the hole-injecting layer  12  and the electron-injecting layer  16  respectively to produce a plurality of holes and electrons. The holes and the electrons recombine in the light emitting layer  14 , and make the organic material of the light emitting layer  14  release the photons. Thus, a display is attained.  
         [0007]     When the OLED  1  is provided in a poorly lit environment, a display of the OLED is good having a high contrast. However, when the OLED  1  is used in strong ambient light (e.g., outdoor sunlight), a display of the transmission OLED  1  appears hazy.  
         [0008]     A new display which overcomes the above-mentioned disadvantages is desired. In particular, what is needed is a display having optical characteristics both in a poorly lit environment and in strong ambient light.  
       SUMMARY  
       [0009]     An exemplary transflective display has a first substrate; a second substrate; and a plurality of pixels defined between the first substrate and the second substrate. Each pixel has an organic light emitting diode (OLED) region and a liquid crystal display (LCD) region adjacent to the OLED region.  
         [0010]     An exemplary display has a first substrate; a second substrate; and a plurality of pixels defined between the first substrate and the second substrate. Each pixel has an organic light emitting diode (OLED) region and a liquid crystal display (LCD) region adjacent to the OLED region.  
         [0011]     Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, all the views are schematic. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a schematic view of a pixel of a transflective display according to a first embodiment of the present invention.  
         [0013]      FIG. 2  is a schematic view of a pixel of a transflective display according to a second embodiment of the present invention.  
         [0014]      FIG. 3  is a schematic view of a pixel of a transflective display according to a third embodiment of the present invention.  
         [0015]      FIG. 4  is a schematic view of a conventional OLED. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0016]     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
         [0017]     Referring to  FIG. 1 , a transflective display  100  according to a first embodiment of the present invention is shown. The transflective display  100  has a plurality of pixels, in each pixel, which has a first substrate  110 , a second substrate  120  opposite to the first substrate  110 , a first electrode layer  111  disposed in an inner surface (not labeled) of the first substrate  110 , a second electrode layer  117  formed at an inner surface (not labeled) of the second substrate  120 , opposite to the first electrode layer  111 , a polarizer  140  adhered on an outer surface (not labeled) of the first substrate  110 .  
         [0018]     In each pixel, the transflective display  100  defines an OLED region and an LCD region adjacent to the OLED region. In the OLED region, the transflective display  100  further includes a hole-injecting layer  112 , a hole-transmitting layer  113 , a light emitting layer  114 , an electron-transporting layer  115 , and an electron-injecting layer  116 , which are formed in that order from the first electrode layer  111  to the second electrode layer  117 . In the LCD region, the transflective display  100  further includes a liquid crystal layer  130  disposed between the first electrode layer  111  and the second electrode layer  117 . In addition, a reflective film  131  is provided between the liquid crystal layer  130  and the second electrode layer  117 .  
         [0019]     The reflective film  131  is made from a reflective material, such as silver or aluminum, which has a plurality of bumps at an inner surface (not labeled) facing the liquid crystal layer  130 . The first electrode layer  111  is made of transparent material, such as indium tin oxide (ITO) or indium zinc oxide (IZO).  
         [0020]     In operation, when the second electrode layer  112  is electrically biased to a negative potential with respect to the first electrode layer  111 , holes are injected into the hole-injecting layer  112  at its interface with the first electrode layer  111  and transported across the hole-transporting layer  113  to the light emitting layer  114 . Concurrently electrons are injected into the electron-injecting layer  116  at its interface with the second electrode layer  120 , and the injected electrons are transported across the electron-transporting layer  117 , toward the light emitting layer  114 . Recombination of the holes and electrons results in electroluminescence. The light emitted can leave the OLED device in any direction. An image display can be realized. At the same time, when the potential is provided to the first and the second electrode layers  111 ,  112 , ambient light beams from the first substrate  110  is utilized in the LCD region by the cooperaion of reflector  131  and the liquid crystal layer  130 . The LCD region can realize the image display through controlling the transmittance ratio of the ambient light beams.  
         [0021]     Therefore, when the transflective display  100  is provided in a poorly lit environment, a display of the transflective display  100  is good, having a high luminance and a high contrast by the utilization of the transmitting OLED region. When the transflective display  100  is used in strong ambient light (e.g., outdoor sunlight), a display of the transflective display  100  also has a good display characteristics by the operation of the reflective LCD region.  
         [0022]     In addition, the transflective display  100  can attain a better display efficiency by adjusting the area ratio of the OLED region and the LCD region according to the environment in common use. In the first embodiment, the area ratio of the OLED region to a pixel can be controlled from 10% to 90%.  
         [0023]     Referring to  FIG. 2 , a transflective display  200  according to a second embodiment of the present invention is shown. The transflective display  200  has a similar structure to the transflective display  100  except that a transflective film  231  replaces the reflective film  131  of the transflective display  100 . The transflective film  231  is disposed between a liquid crystal layer  230  and a second electrode layer  217 , which is made from a metallic film having a thickness less than 100 nm. The second electrode layer  217  is made from a transparent material. The transflective film  231  reflects the ambient light beams from a first substrate  210 .  
         [0024]     Referring to the  FIG. 3 , a transflective display  300  according to a third embodiment of the present invention is shown. The transflective display  300  has a similar structure to the transflective display  100  except that a reflective film  331  has a plurality micro holes  332  formed thereon. A second electrode layer  317  is made from transparent material.  
         [0025]     When the transflective display  100 ,  200 ,  300  is provided in a poorly lit environment, a display of the transflective display  100 ,  200 ,  300  is good having a high luminance and a high contrast by the utilization of the transmittance OLED region. When the transflective display  100 ,  200 ,  300  is used in strong ambient light (e.g., outdoor sunlight), a display of the transflective display  100 ,  200 ,  300  also has a good display characteristics by the operation of the reflective LCD region.  
         [0026]     It is to be further understood that even though numerous characteristics and advantages of various embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.