Abstract:
A dual-side display including an OLED substrate, a package substrate located at opposite side of the OLED substrate and frit seal sandwiched between the OLED substrate and the package substrate, wherein, the package substrate is an electrophoresis membrane, the part of the electrophoresis membrane that does not cover the OLED substrate is configured to display at one surface of the dual-side display, the OLED substrate is configured to display at another surface opposite to the one surface of the dual-side display. According to the dual-side display of the application, the dual-side display can effectively increase the light emitting area of the OLED, as well as the aperture ration and the display luminance of the OLED display panel, and achieves dual-side display to satisfy different requirements. Besides, the OLED display of the present application can make full use of light-emitting pixel area and obtain better light emitting effect.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Chinese Patent Application No. 201410051852.3 filed on Feb. 14, 2014 in the State Intellectual Property Office of China, the application of which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present application relates in general to a dual-side display, a device for controlling the dual-side display and the method for manufacturing the same. 
       BACKGROUND ART 
       [0003]    OLED display is a solid-state device formed by thin organic molecule layers which can emit light after voltage is applied. OLED displays usually have a sandwich structure, that is, an organic layer is sandwiched between two electrodes. Electron hole and electron are injected from anode and cathode, respectively, transmit in an organic layer, meet each other, form exciton and emit light. The anode is a transparent electrode made of ITO (Indium Tin Oxide), so that it can transmit light. The cathode is usually made of low work function metal such as Magnesium (Mg) or Lithium (Li). OLED display can provide electronic device a brighter and clearer image, and it has lower power consumption than the conventional LED display screen. As a result, the OLED display has advantages as below: compared with crystal layers of the conventional LED or LCD display, the organic molecule layer of OLED is thinner, lighter and more flexible; the OLED display screen is made of self-emissive material instead of using a back light plate, and it has wide visual angle, uniform image quality, fast response speed, high colorize capability. Besides, it can emit light employing simple driving circuit, has simple manufacturing process, can be made of flexible panel and meets the requirement of being slim, thin, short and small. 
         [0004]      FIG. 1  is a schematic sectional diagram showing a conventional OLED display device  1 ′ which is a bottom emission type OLED display device. In  FIG. 1 , reference numeral  10 ′ represents an OLED substrate, OLED lighting devices and active matrix TFTs (thin film transistor) are disposed on the OLED substrate  10 ′. The OLED substrate  10 ′ is made of rigid or flexible material. Reference numeral  20 ′ represents a package substrate, the package substrate  20 ′ is usually made of rigid material such as glass, or flexible membrane package formed by organic membrane and inorganic membrane stacked on top of each other. Frit seal  30 ′ is disposed between the OLED substrate  10 ′ and the package substrate  20 ′ of the OLED display device  1 ′, the frit seal  30 ′ is used to fix and connect the OLED substrate  10 ′ and the package substrate  20 ′. The surface indicated by arrow in  FIG. 1  is the light emitting surface of the OLED display device  1 ′. 
         [0005]      FIG. 2  is a schematic diagram showing a pixel plane in the conventional OLED display device. In  FIG. 2 , three sub-pixels are shown. The area shown by reference numeral  21 ′ is a blank area, the area shown by reference numeral  22 ′ is actual pixel light-emitting area. As shown in  FIG. 2 , due to the affect of the OLED evaporation accuracy, the light-emitting area of the conventional OLED display device is very small, this results in low luminance of the product. 
         [0006]      FIG. 3  is a pixel circuit diagram of the conventional OLED display device. In  FIG. 3 , transistor T 1  is a switching TFT (thin film transistor), transistor T 2  is a driving TFT. The drain of transistor T 1  is connected to a data line Vdata, the gate thereof is connected to the first scan line Scan 1 , the source thereof is connected to an end of the storage capacitor and the gate of the second transistor T 2 . When transistor T 1  is open, data voltage Vdata is written in the gate of transistor T 2  and stored in the storage capacitor. Afterwards, transistor T 1  is closed; the gate of transistor T 2  is connected to the source of transistor T 1 , the drain of transistor T 2  is connected to power line VDD, the source of transistor T 2  is connected to the anode of OLED, the voltage applied across the storage capacitor controls the electric current flowing through the OLED, thereby controlling the light emitting intensity of the OLED. 
         [0007]    From the description above, as limited by the evaporation accuracy of OLED display device, the conventional OLED display device has small actual light emitting area and low aperture ratio, most pixel areas are not used. In the conventional OLED display device, the aperture ratio is less than 20%. As a result, the conventional OLED display device has low luminance, and it cannot satisfy the requirements of the user in some cases. 
         [0008]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the application 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 OF DISCLOSURE 
     Problem to be Solved 
       [0009]    In the application, to prevent the problems in the conventional technology, the application discloses a dual-side OLED display which not only uses the display area effectively but also achieves dual-side display effect. The application also discloses a controlling device for controlling the dual-side display and a method for manufacturing the dual-side display. 
       Technical Solution 
       [0010]    A technical solution of the application discloses a dual-side display, including an OLED substrate, a package substrate located at opposite side of the OLED substrate and frit seal sandwiched between the OLED substrate and the package substrate. In the dual-side display, the package substrate is an electrophoresis membrane, the light-emitting area of the OLED device achieves OLED display, and the area that the OLED does not emit light achieves electrophoresis membrane display. The OLED emits light from bottom, the electrophoresis membrane displays from the top, the OLED and the electrophoresis membrane can display at the same time or separately. 
         [0011]    OLED light emitting devices and active matrix TFTs are disposed at the OLED substrate. 
         [0012]    The OLED substrate is made of rigid or flexible material. 
         [0013]    The electrophoresis membrane is capable of achieving flexible display. 
         [0014]    The disclosure further discloses a controlling device for controlling the dual-side display, including a first switching TFT (T 1 ), a driving TFT (T 2 ), a drain of the first switching TFT (T 1 ) being connected to a data line, a gate of the first switching TFT (T 1 ) is connected to a first scan line, a source of the first switching TFT (T 1 ) is connected to an end of a storage capacitor and a gate of the driving TFT (T 2 ), wherein, the controlling device further comprises a second switching TFT (T 3 ), a drain of the second switching TFT (T 3 ) is connected to the data line, a gate of the second switching TFT (T 3 ) is connected to a second scan line, the source of the second switching TFT (T 3 ) is connected to an electrode of the electrophoresis membrane, 
         [0015]    The gate (T 2 ) of the driving TFT is connected to the source of the first switching TFT (T 1 ), the drain of the driving TFT is connected to the power line, the source of the driving TFT is connected to an anode of the OLED substrate. 
         [0016]    When the first switching TFT (T 1 ) is turned on, the voltage is written to the storage capacitor via the first switching TFT (T 1 ). When the driving TFT (T 2 ) is turned on, the electric current input by the power line flows through the OLED substrate to make the OLED substrate display. Namely, when only OLED display is needed, T 1  is turned on first, voltage is written to the storage capacitor via the first switching TFT (T 1 ), and then TFT T 1  is turned off, and then TFT T 2  is turned on, the OLED begins to emit light. 
         [0017]    The electric current flowing through the OLED substrate is controlled by the data voltage. 
         [0018]    When the first switching TFT (T 1 ) is turned off and the second switching TFT (T 3 ) is turned on, only the electrophoresis membrane displays, when the first switching TFT (T 1 ) and the second switching TFT (T 3 ) are turned on at the same time, the OLED substrate and the electrophoresis membrane display at the same time. 
         [0019]    The first switching TFT (T 1 ) and the second switching TFT (T 3 ) shares a data line. 
         [0020]    The disclosure further discloses method for manufacturing the dual-side display, wherein the method comprises the steps of: depositing a semi-conductor layer at a transparent substrate and patterning the semi-conductor layer; depositing a first insulating layer and a first metal layer on the patterned semi-conductor layer and patterning the first metal layer; depositing a second insulating layer on the patterned metal layer, and patterning the second insulating layer; then depositing the second metal layer and patterning the second metal layer; forming a flat layer at the surface of the patterned second metal layer and patterning the flat layer; depositing a pixel electrode layer at the surface of the flat layer, a first part of the pixel electrode layer is connected to a source of a driving TFT, and used as the anode of the OLED substrate, the second part of the pixel electrode layer is connected to a pixel electrode of the electrophoresis membrane and controls the display of the electrophoresis membrane; evaporating the OLED light emitting material and cathode material in sequence above the OLED substrate to form the OLED device; and packaging the OLED device with the electrophoresis membrane. 
         [0021]    The substrate is a transparent rigid substrate or a transparent flexible substrate. 
         [0022]    The semi-conductor layer is a A-Si (Amorphous Silicon), LTPS (Low Temperature Poly Silicon) or oxide. 
         [0023]    The flat layer is formed by spin coating. 
         [0024]    The first part of the pixel electrode layer and the second part of the pixel electrode layer are independent. 
       Beneficial Effect 
       [0025]    The dual-side display according to the application can effectively increase the light emitting area of the OLED, as well as the aperture ration and the display luminance of the OLED display panel, and achieves dual-side display to satisfy different requirements. Besides, in the application, the OLED display can be complementary with the electrophoresis membrane, therefore, it can make full use of light-emitting pixel area and obtain better light emitting effect. 
         [0026]    It should be understood that, the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide further explanation of the claimed disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The foregoing and other features and advantages of the disclosure will be apparent to those skilled in the art in view of the following detailed description, taken in conjunction with the accompanying drawings, in which. 
           [0028]      FIG. 1  is a schematic sectional diagram showing a conventional OLED display device. 
           [0029]      FIG. 2  is a schematic diagram showing a pixel plane in the conventional OLED display device in  FIG. 1 . 
           [0030]      FIG. 3  is a pixel circuit diagram of the conventional OLED display device. 
           [0031]      FIG. 4  is a schematic sectional diagram showing an OLED display device according to an embodiment of the application. 
           [0032]      FIG. 5  is a schematic diagram showing a pixel plane in the OLED display device according to an embodiment of the application. 
           [0033]      FIG. 6  is a pixel circuit diagram of the OLED display device according to an embodiment of the application. 
           [0034]      FIG. 7  is a pixel sectional diagram showing the OLED display device according to an embodiment of the application. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Exemplary embodiments of the application will now be described more fully with reference to the accompanying drawings. 
         [0036]      FIG. 4  is a schematic sectional diagram showing an OLED display device  1  according to an embodiment of the disclosure. As shown in  FIG. 4 , the OLED display device  1  according to an embodiment of the disclosure includes an OLED substrate  10 , OLED light emitting devices and active matrix TFTs (thin film transistors) are disposed on the OLED substrate  10 . The OLED substrate  10  can be made of rigid material or flexible material. The opposite side of the OLED substrate  10  is a package substrate, the package substrate according to an embodiment of the disclosure may be electrophoresis membrane  20 . Frit seal  30  is disposed between the OLED substrate  10  and the electrophoresis membrane  20 . The frit seal  30  is used to bond the OLED substrate  10  and the electrophoresis membrane  20  together. 
         [0037]    The electrophoresis membrane  20  in the disclosure can not only be used as package material for packing the OLED substrate  10 , but also achieves flexible display. The electrophoresis membrane  20  itself can display images, when voltage is applied across two ends of the electrophoresis membrane  20 , positive charges and negative charges in the electrophoresis membrane capsule inside the electrophoresis membrane  20  move towards two directions, respectively, so as to achieve the function for displaying. The electrophoresis membrane  20  has bi-stable state which is an outstanding characteristic thereof. The electrophoresis membrane  20  may still display images even when the applied electric field is removed. In one case in practical application, when only displaying dynamic color image is needed, the OLED display is switched to, and when only displaying black-white image is needed, the electrophoresis membrane display is used only to save power. As a result, according to the application, the part of the electrophoresis membrane  20  that is located at the OLED display area is taken as packaging material, and the part of the electrophoresis membrane  20  that does not cover the OLED display area may be used as electrophoresis membrane display after voltage is applied across two ends thereof. As shown in the arrow in  FIG. 4 , according to an embodiment of the disclosure, the OLED display device may emit light from the bottom, namely the bottom surface of the OLED display device is a light-emitting surface, and the electrophoresis membrane  20  upon the OLED display device can also be used for display, therefore the dual-side display is achieved. For example, if only character display is needed, or only black-white image display is needed, the electrophoresis membrane  20  may be used to save power. 
         [0038]      FIG. 5  is diagram schematic diagram showing a pixel plane in the OLED display device according to an embodiment of the disclosure. According to the OLED display device of the disclosure, a pixel layer  23  is added at the blank area  21 , compared with the pixel plane diagram showing the conventional OLED display device in  FIG. 2 , the OLED display device in the disclosure makes full use of the pixel layer, and turns the area in the OLED display which cannot emit light to a pixel electrode layer of the electrophoresis membrane, the electrophoresis membrane display function is added on the basis that the OLED light emitting area is not reduced. 
         [0039]      FIG. 6  is a pixel circuit diagram of the OLED display device according to an embodiment of the disclosure. Compared with the pixel circuit diagram in the conventional OLED display device in  FIG. 3 , the pixel circuit in the disclosure adds a switching TFT T 3 . The drain of the TFT T 1  is connected to the data line Vdata, the gate of the TFT T 1  is connected to the first scan line Scan 1 , and the source of the TFT T 1  is connected to the gate of TFT T 2 . The gate of the TFT T 2  is connected to the source of the TFT T 1 , the drain of the TFT T 2  is connected to the power line VDD, the source of the TFT T 2  is connected to the anode of the OLED. The drain of TFT T 3  is connected to data line Vdata, the gate of TFT T 3  is connected to the second scan line Scan 2 , the source of TFT T 3  is connected to the electrode of electrophoresis membrane. When only OLED display is used, TFT T 1  is on, the data voltage Vdata is written to the storage capacitor via the TFT T 1 . An end of the storage capacitor is connected to the gate of TFT T 2 , and the other end is connected to the power line VDD. When T 2  is open, electric current inputted by the power line VDD flows through the OLED to make the OLED emit light, the electric current magnitude flowing through the OLED is determined by the magnitude of data line Vdata. Namely, only when OLED display is used, TFT T 1  is on first, voltage is written to the storage capacitor via the first switching TFT (T 1 ), and then T 1  is off, and then TFT T 2  is on, the OLED begins to emit light. When only the electrophoresis membrane display is used, the TFT T 1  is in an off state, TFT T 3  is on. When dual-side display is needed, both TFT T 1  and TFT T 3  are on, the OLED and electrophoresis membrane display at the same time. 
         [0040]      FIG. 7  is a pixel sectional diagram showing the OLED display device according to an embodiment of the disclosure. According to the embodiment, the OLED display device in the disclosure is manufactured in the following processes: 
         [0041]    First, depositing a semi-conductor layer  41  on a glass substrate  40  and patterning the semi-conductor layer  41 . To make the OLED emit light from the bottom, the substrate  40  may also be made of other transparent materials. The semi-conductor layer  41  maybe Amorphous Silicon (A-Si), low temperature poly-silicon (LTPS), oxide and so on. Afterwards, depositing a first insulating layer  42  and a first metal layer  43  in sequence on the patterned semi-conductor layer  41 , and patterning the first metal layer  43 , the first part  43   a  of the patterned first metal layer corresponds to the gate of TFT T 2  in  FIG. 6 , the second part  43   b  of the patterned first metal layer corresponds to the gate of TFT T 1  in  FIG. 6 , the third part  43   c  of the patterned first metal layer corresponds to the gate of the TFT T 3  in  FIG. 6 . The gate of the first part  43   a  of the patterned first metal layer is connected to the source  45   c  of the TFT T 1 . 
         [0042]    Afterwards, depositing a second insulating layer  44  at the patterned metal layer  43 , and patterning the second insulating layer  44 . The purpose of patterning the second insulating layer  44  is to form contact holes on the surface of the semi-conductor layer  41  and the surface of the first metal layer  43 . The purpose of forming the contact hole is to achieve electric contact between the semi-conductor layer  41  and the second metal layer  45 , and between the first metal layer  43  and the second metal layer  45 . Afterwards, depositing the second metal layer  45  and patterning the second metal layer  45 , the fourth part  45   d  of the patterned second metal layer corresponds to the data line Vdata in  FIG. 6 , TFT T 1  and TFT T 3  share a data line Vdata. The first part  45   a  of the patterned second metal layer corresponds to the source of the TFT T 2  in  FIG. 6 , namely the anode of the OLED. The source of T 2  is connected to the pixel electrode  47   a  of OLED, the second part  45   b  of the patterned second metal layer corresponds to the power line VDD in  FIG. 6 , and the third part  45   c  of the patterned second metal layer corresponds to the source of TFT T 1  in  FIG. 6 , the source  45   c  of T 1  is connected to the gate of TFT T 2 , the fifth part  45   e  of the pattered second metal layer corresponds to the source of TFT T 3  in  FIG. 6 , namely connected to the pixel electrode  47   a  of the electrophoresis membrane. The surface of the patterned second metal layer  45  is formed with a flat layer  46  with spin coating method and the flat layer  46  is patterned, the flat layer may be used as an OC layer for flatting. A pixel electrode layer  47  is deposited on the surface of the flat layer  46 , the first part  47   a  of the pixel electrode layer is connected to the source of the TFT T 2  and used as the anode of the OLED, the second part  47   b  of the pixel electrode layer is connected to the pixel electrode of the electrophoresis membrane, namely the source of the TFT T 3 , the first part  47   a  of the pixel electrode layer is independent with the second part  47   b  of the pixel electrode layer. Afterwards, an OLED light emitting material and cathode material are deposited on the OLED, and the OLED device is formed. Afterwards the OLED device is packaged with electrophoresis membrane, employing the pixel electrode namely the second part  47   b  of the pixel electrode layer to control the display of the electrophoresis membrane. 
         [0043]    TFT T 1  and TFT T 3  share a data line  45   d.  When the gate  43   c  of the TFT T 3  is applied with voltage, TFT T 3  is conducted, and electric current flows through the channel, data line voltage Vdata is written to the pixel electrode  47   b  to generate voltage difference between two sides of the electrophoresis membrane  50 . Under the effect of the voltage difference, the positive particle capsule and negative particle capsule of the electrophoresis membrane  50  move towards opposite direction to achieve electrophoresis membrane display. The source  45   c  of TFT T 1  is connected to the gate  43   a  of the TFT T 2  (not shown), and when the TFT T 1  is conducted, the voltage of the data line  45   d  is written to the gate of the TFT T 2  and stored in the capacitor (not shown) between the gate  43   a  in  FIG. 4  and of the power line VDD (reference numeral  45   b  in  FIG. 7 ), the magnitude of voltage stored in the capacitor controls the on/off state of TFT T 2 , when the TFT T 2  is on, the electric current path is from the power line VDD (reference numeral  45   b  in  FIG. 7 ) to the source  45   a,  and then pass the OLED device to achieve OLED displaying. The magnitude of the electric current is relative to the voltage stored in the capacitor, and the luminance of the OLED material  48  is relative to the electric current flowing through the OLED device. When the TFT T 1  and TFT T 3  are on at the same time, the electrophoresis membrane and the OLED display at the same time. 
         [0044]    The operating process of the dual-side display in the embodiment shown in  FIG. 7  is described hereinbelow: when only OLED displays, the TFT T 1  is turned on first, the voltage is written to the storage capacitor via the TFT T 1 , then T 1  is turned off, and TFT T 2  is turned on, the light emitted by the OLED is from the bottom of the transparent substrate. When only the electrophoresis membrane displays, TFT T 1  is in an off state, TFT T 3  is on, the electrophoresis membrane at the above is used to display. When dual side display is needed, TFT T 1  and TFT T 3  are in an on state at the same time, as a result, the electrophoresis membrane and the OLED display at the same time. 
         [0045]    According to the OLED display device in the disclosure, since the electrophoresis membrane is used as the package substrate, the OLED display device not only achieves dual display, but also adds a pixel layer due to the electrophoresis membrane, which increases the aperture area as well as the display luminance of the OLED. 
         [0046]    Exemplary embodiments have been specifically shown and described as above. It will be appreciated by those skilled in the art that the application is not limited the disclosed embodiments; rather, all suitable modifications and equivalent which come within the spirit and scope of the appended claims are intended to fall within the scope of the application.