Abstract:
An Active Matrix Organic Light Emitting Diode (AMOLED) display panel is disclosed. The display panel includes first and second substrates, and a glass frit layer bonding the first and the second substrates in an edge encapsulation area of the AMOLED display panel. The second substrate includes an electrode overlapped with the glass frit layer, and the electrode is connected to a heat conduction component.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Chinese patent application No. 201210546837.7 filed on Dec. 14, 2012 and titled “AMOLED DISPLAY PANEL AND AMOLED DISPLAY DEVICE”, the contents of which is incorporated herein by reference in its entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to the field of displays, and in particular to an AMOLED display panel and an AMOLED display device. 
       BACKGROUND OF THE INVENTION 
       [0003]    With the booming development of flat panel display technology, an AMOLED (Active Matrix Organic Light Emitting Diode) display, compared with traditional liquid crystal displays (LCD), has excellent features, such as being self-luminous so that a backlight is not needed, low power consumption, no visual angle restriction, and high response rate. In addition, AMOLED displays have lighter weight and thinner thickness. As a result, the AMOLED display is expected to dominate in the next generation of flat panel display technology and to be used more widely. 
         [0004]    Currently AMOLED display panels comprise an upper substrate and a lower substrate, where the upper substrate and the lower substrate are bonded together by a glass frit layer on the edge encapsulation areas of the substrates. A visible test, i.e. VT test, is typically carried out after the panel is manufactured. During this VT test, the picture luminance is increased in the display area of the display panel, and the luminance is achieved generally by increasing the current of the circuit of the display panel. It is quite difficult to change the resistance of the circuit of the display panel, since the display panel has been properly manufactured. As a result, increasing the picture luminance is achieved generally by increasing the input voltage. But when the VT test is performed, heat is generated in some elements or devices in the circuit of the display panel if the input voltage is increased, and in particular, more heat is generated in an electrode with relatively small cross-sectional area and relatively large resistance. Some of the electrodes partially overlap with the glass frit layer in the encapsulation area, so that heat is transmitted to the glass frit layer by the heated electrode, and the glass frit layer may be seared. This may affect the encapsulation efficacy and the performance of the display during the VT test. 
       SUMMARY OF THE INVENTION 
       [0005]    One inventive aspect is an Active Matrix Organic Light Emitting Diode (AMOLED) display panel. The display panel includes first and second substrates, and a glass frit layer bonding the first and the second substrates in an edge encapsulation area of the AMOLED display panel. The second substrate includes an electrode overlapped with the glass frit layer, and the electrode is connected to a heat conduction component. 
         [0006]    Another inventive aspect is an Active Matrix Organic Light Emitting Diode (AMOLED) display device. The display device includes an AMOLED display panel, which includes first and second substrates, and a glass frit layer bonding the first and second substrates in an edge encapsulation area of the AMOLED display panel. The second substrate includes an electrode overlapped with the glass frit layer, and the electrode is connected to a heat conduction component. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1A  is a plan view of the local structure of an AMOLED display panel the according to an embodiment of the invention; 
           [0008]      FIG. 1B  is a cross-sectional schematic diagram of the partial structure in  FIG. 1A ; 
           [0009]      FIG.2A  is a cross-sectional schematic diagram of a U-shaped metal pad connected to the electrode of the AMOLED display panel by a via hole according to an embodiment of the invention; 
           [0010]      FIG. 2B  is another cross-sectional schematic diagram of a U-shaped metal pad connected to the electrode by a via hole according to an embodiment of the invention; 
           [0011]      FIG. 3A  is a local cross-sectional schematic diagram of the display area of the AMOLED display panel comprising a thin film transistor according to an embodiment of the invention; 
           [0012]      FIG. 3B  is another local cross-sectional schematic diagram of the AMOLED display panel according to an embodiment of the invention; 
           [0013]      FIG. 4A  is another plan schematic diagram of the AMOLED display panel according to an embodiment of the invention; 
           [0014]      FIG. 4B  is a plan schematic diagram showing that PVEE and the U-shaped metal pad are extended to form an overlapping area according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0015]    According to some embodiments, an AMOLED display panel includes an electrode overlapped with a glass frit layer and that is connected to a heat conduction component, such that heat from the electrode is conducted away to avoid excessive heat on the electrode. 
         [0016]    Detailed description is made below of certain implementation modes of the AMOLED display panel and the AMOLED display device according to various embodiments of the invention. Reference is made to the drawings, in which the sizes and shapes of various features are not reflected on a real scale, but which aims to illustrate certain aspects of the invention. 
         [0017]      FIG. 1A  is a plan view of a local structure of the AMOLED display panel according to an embodiment of the present invention. The AMOLED display panel shown includes a first substrate  1  and a second substrate  2  (not shown in  FIG. 1A ), a glass frit layer  3  bonding the first substrate  1  and the second substrate  2  along the edge of the encapsulation area of the AMOLED display panel. The second substrate  2  includes an electrode  4  overlapped with the glass frit layer  3 , and the electrode  4  is connected to a heat conduction component  5 .  FIG. 1B  is a cross-sectional schematic diagram of the embodiment shown in figure in  FIG. 1A  taken along A-A′. The location of the heat conduction component  5  and the connection to the electrode  4  are not limited to the embodiment shown in  FIG. 1B . The heat conduction component  5  may be any heat conduction component which has the function of heat conduction and does not cause a short circuit after being connected to the electrode  4 . In some embodiments, the heat conduction component is placed on the AMOLED display panel in order to simplify the manufacturing process without damaging the layered structure of the AMOLED display panel. 
         [0018]    In the embodiment shown, the electrode  4  overlapped with the glass frit layer  3  is connected to a heat conduction component  5 , which conducts heat from the electrode  4  to avoid excessive heat on the electrode  4 . In addition, the original heat conduction component in the AMOLED display panel can be used without adding another heat conduction component. 
         [0019]    In another embodiment of the present invention, the heat conduction component  5  may be a U-shaped metal pad  51  located under the glass frit layer  3 . In some embodiments, the heat conduction component  5  may also be a metal layer which has substantially no electrical function for the electronic circuit, e.g. a metal component in a panel code printing area. 
         [0020]    Specifically, the U-shaped metal pad  51  in the shown embodiment may be connected to the electrode  4  by a first via hole  52 . In the display panel, circuit metal wiring may be set at one side of the substrate. In the shown embodiment of the invention, the electrode  4  is located on a first side (the side of A-A′ in  FIG. 1A ) of the second substrate  2 . The first side (the side of A-A′ in  FIG. 1A ) comprises a relatively large amount of circuit metal wiring, and the U-shaped metal pad  51  is located along the other three sides of the second substrate. The other three sides comprise a relatively small amount of circuit metal wiring.  FIG. 2A  is a cross-sectional schematic diagram of the U-shaped metal pad  51  connected to the electrode  4  by the first via hole  52  in the A-A′ portion of  FIG. 1A . 
         [0021]    It can be seen from  FIG. 2A  that, in this embodiment of the invention, the U-shaped metal pad  51  is located along the other three sides which are different from the side having the access terminal of the electrode  4 . As shown, there is no overlapping part between the U-shaped metal pad  51  and the electrode  4  on that side. As shown, the first via hole  52  is inclined. At least because the process of making the first via hole is relatively complex, in some embodiments, the U-shaped metal pad  51  or/and the electrode  4  extend to form extending parts respectively. An example in which both the U-shaped metal pad  51  and the electrode  4  are extended is shown in  FIG. 2B . As shown, the extending parts form overlapping part  53 . In some embodiments, the first via hole  52  is in the overlapping part  53 , so that the U-shaped metal pad  51  is connected to the electrode  4  in the overlapping part  53  by the first via hole, as shown in  FIG. 2B . 
         [0022]    In the shown embodiment of the invention, the U-shaped metal pad  51  is located along the other three sides which are different from the side having the access terminal of the electrode  4 . This avoids a possible short circuit caused by the U-shaped metal pad  51  touching other circuit metal wirings. The U-shaped metal pad  51  is connected to the electrode  4  in the shown embodiment of the invention such that the electrode  4  is connected to the two ends of the U-shaped metal pad  51  respectively to achieve better heat dissipating function. In addition, the U-shaped metal pad  51  and the electrode  4  respectively have extending parts overlapped with each other in the shown embodiment of the invention, and the first via hole is set in the overlapping part at least to further simplify the manufacturing process. 
         [0023]    Another embodiment of the present invention includes an AMOLED display panel, which, in addition to structures discussed above, includes a thin film transistor (TFT) located in the display area of the AMOLED display panel, as shown in  FIG. 3A , which is a cross-sectional schematic diagram of the display area of an AMOLED display panel according to an the embodiment of the invention. 
         [0024]    In  FIG. 3A , a buffer layer  6 , an active layer  7 , a gate insulating layer  8 , a gate  9 , a medium isolating layer  10 , source/drain  11  and an insulating layer  12  are sequentially formed on the second substrate  2 . The medium isolating layer  10  is used for isolating the gate  9  from the source/drain  11 , the gate insulating layer  8  isolates the gate  9  from the active layer  7 . To simplify the manufacturing process and achieve good operability in the etching process, the medium isolating layer  10  located between the U-shaped metal pad  51  and the electrode  4 , at the side frame of the display panel may be not etched off, that is, the medium isolating layer  10  may be included between the U-shaped metal pad  51  and the electrode  4  in some embodiments of the invention. The medium isolating layer between the U-shaped metal pad  51  and the electrode  4  may be somewhat different based upon a different TFT structure, and this discussion is not to be considered as being limitative. 
         [0025]    Further, the U-shaped metal pad  51  in some embodiments of the invention may be made of the same material as the source/drain  11  of the thin film transistor TFT in the AMOLED display panel. For example, the material may include Ti/Al/Ti. The electrode  4  may be made of the same material as the gate  9  of the thin film transistor TFT, and the material may include Mo. In order to simplify the manufacturing process, the U-shaped metal pad  51  and the source/drain  11  may be formed simultaneously by an etching process. Additionally or alternatively, the electrode  4  and the gate  9  may be formed simultaneously by an etching process. 
         [0026]      FIG. 3B , a cross-sectional schematic diagram taken along B-B′ of the AMOLED display panel of  FIG. 1A . As shown, the U-shaped metal pad  51  is located on the same layer as the source/drain, and the electrode  4  is located on the same layer as the gate  9 . Accordingly, the respective pairs of layers may be formed simultaneously. 
         [0027]    The location of the heat conduction component connected to the electrode  4  has an influence on the heat conduction time. That is, the closer the conduction component is to the electrode  4 , the quicker that he will be conducted away. In order to conduct the heat from the overlapping part of the glass frit layer  3  and the electrode  4  as quickly as possible, the overlapping part of the electrode  4  and the glass frit layer  3  may be extended to obtain an extending part of the electrode  4 , the end of the U-shaped metal pad  51  is then extended to obtain an extending part of the U-shaped metal pad  51 , the two extending parts form an overlapping area in which the electrode  4  is connected to the U-shaped metal pad  51  by the first via hole such as that shown in  FIG. 2B . 
         [0028]    The AMOLED display panel according to this embodiment of the invention, includes no additional heat conduction component because the electrode is connected to the U-shaped metal pad by the via hole. In some embodiments, a different connection is used, for example, based upon a different TFT structure of the display panel. In some embodiments, heat from the electrode is effectively conducted out without changing the original layered structure of the display panel, thus preventing the glass frit layer from being seared due to excessive heat gathered from the electrode during the VT test. 
         [0029]    During the VT test, the voltage input is PVDD and PVEE, and the current flowing through the AMOLED display panel are calculated using the formulas as follow: 
         [0000]        I   OLED   =m* [½*μ*Cox* W/L *( V   PVDD   −V   Data   −V   th ) 2 ]; (when there is no threshold voltage compensation circuit) and
 
         [0000]        I   OLED   =m*[ ½*μ*Cox* W/L *( VPVDD   −V   Data ) 2 ]; (when there is a threshold voltage compensation circuit).
 
         [0000]    I OLED  represents current flowing through the AMOLED display panel, m represents the number of pixels, μ represents transistor mobility, Cox represents memory capacitance, W/L represents transistor channel width/length ratio, V PVDD  represents the input voltage of the PVDD, V Data  represents the voltage of a Data wire, and V th  represents the starting threshold voltage of a transistor. 
         [0030]    It can be seen from the formulas above that I OLED  is mainly under the influence of V PVDD . V PVDD  is, therefore, increased to increase I OLED  during the VT test. That is, when the voltage input to the PVDD is increased, the current flowing through the access terminal of the PVDD is also increased. However, at the access terminal of the PVDD the wiring may be quite thin, and the resistance of the PVDD may be correspondingly quite large. Accordingly, there may be much heat generated at the access terminal of PVDD due to the large current and the large resistance. 
         [0031]    It is quite clear from the above analysis that, much heat will likewise be generated on excess terminal of PVEE. The glass frit layer for encapsulating the first substrate and the second substrate is located above the PVDD and the PVEE. Thus, a Frit material may be seared, for example, when the current flowing through the PVDD or the PVEE is great than 0.4 A. Accordingly, the PVDD electrode and the PVEE electrode are used as examples for description in the discussion herein. 
         [0032]      FIG. 4A  is a plan schematic diagram of a display panel according to an embodiment. As shown in  FIG. 4A , the access terminal of PVDD  13  and the access terminal of the PVEE  14  are overlapped with the glass frit layer  3 . If a high enough voltage is used, enough heat will be generated on PVDD  13  and PVEE  14  that the glass frit layer  3 , overlapped with PVDD  13  and 
         [0033]    PVEE  14 , may be seared. In some embodiments, PVDD  13  or PVEE  14  are connected to the heat conduction component according to one or more of the embodiments discussed herein. In some embodiments, PVDD  13  or the PVEE  14  are connected to a U-shaped metal pad according to one or more of the embodiments discussed herein. It can be seen from  FIG. 4A  that the access terminal of PVDD and the access terminal of PVEE are overlapped with the glass frit layer to form overlapping parts  15 . Such a configuration may cause the glass frit layer to be seared. Therefore, preferably in some embodiments of the invention, the access terminal of the PVDD and the access terminal of the PVEE overlapped with the glass frit layer are extended and the end of the U-shaped metal pad is also extended. Thus, the two extending parts are overlapped to form an overlapping area in which one of the access terminals is connected to the U-shaped metal pad by a second via hole (not shown in the drawing). 
         [0034]    The heat conduction component connected to PVDD  13  or PVEE  14  may also be another metal layer which has no electrical function for the circuit, e.g. a two-dimensional code square area may be used. In the description the U-shaped metal pad is discussed as an example, and is not to be regarded as being limitative. 
         [0035]    In some embodiments, PVDD  13  and PVEE  14  each have two access terminals. In such embodiments, the two access terminals of each electrode may be extended respectively for connecting to the U-shaped metal pad, or just one of the two access terminals could be extended. In some embodiments, the access terminals of PVDD or PVEE form extending parts, which are overlapped with the extending part at the end of the U-shaped metal pad to form an overlapping area in which the access terminals are connected to the U-shaped metal pad by the via hole, as shown in  FIG. 4B . In  FIG. 4B , the extending part  1011  of the first access terminal  101  of PVEE is connected to the extending part  501  at the first end of the U-shaped metal pad  51 , and the extending part  1012  of the second access terminal  102  of PVEE is connected to the extending part  502  at the second end of the U-shaped metal pad  51 , so that heat at the overlapping part of PVEE and the glass frit layer is conducted out more quickly. 
         [0036]    Further, a short circuit would be caused by simultaneous connection of PVDD and PVEE to the U-shaped metal pad, so in this embodiment of the invention, just PVDD or PVEE is connected to the U-shaped metal pad by the second via hole. 
         [0037]    In some embodiments of the invention, the end of PVDD or the end of PVEE is connected to the U-shaped metal pad. On one hand, it guarantees a flexible connection mode, and on the other hand, it realizes quick heat dissipation on PVDD and PVEE to further prevent the glass frit layer overlapped with PVDD and PVEE from being seared. 
         [0038]    Some embodiments of the present invention provide an AMOLED display device, which comprises an embodiment of an AMOLED display panel having one or more aspects described herein. 
         [0039]    A connection similar to the connection of the electrode to the heat conduction component may be used to connect PVDD or PVEE to the U-shaped metal pad. Alternatively, another connection may be used. 
         [0040]    Various modifications and variations of the present invention can be made by those skilled in the art without departing from the spirit and scope of the present invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the invention and equivalent technologies thereof, the invention is intended to encompass the modifications and variations.