Abstract:
In a display apparatus having a display zone and a light-shielding zone, the light-shielding zone includes an electrically controlled material having a controllable light shielding rate and being controlled to change its light shielding rate in accordance with a control signal.

Description:
RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Taiwan Application Number 97150712 filed Dec. 25, 2008, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a method for reducing the light leakage transmitted from a light-shielding zone of a display apparatus. 
     2. Related Art 
     With the advancing development and the maturity of liquid crystal display (LCD) technology, it has gradually replaced traditional cathode ray tubes (CRT) in the display technology field and thereby has been applied to various electronic products. In more detail, the liquid crystal display panels can be classified into an in-plane-switching (IPS) type, a multi-domain-vertical-alignment (MVA) type, a twist-nematic (TN) type, a color-filter-on-array (COA) type, a transflective type and etc. Other type of display apparatus are not excluded. 
     As shown in  FIG. 1 , a known liquid crystal display apparatus  10  includes a backlight module  100  and a liquid crystal display panel  200  disposed at the light-emitting side of the backlight module  100 . The liquid crystal panel  200  includes an electrode substrate  210 , a color-filter-on-array substrate  220  and a liquid crystal layer  230 . The liquid crystal layer  230  is disposed between the electrode substrate  210  and the color-filter-on-array substrate  220 , and is sealed with a sealant  240 . In more detail, the electrode substrate  210  and the color-filter-on-array substrate  220  form a display zone Z 1  and a light-shielding zone Z 2 , and the light-shielding zone Z 2  is disposed around the display zone Z 1 . In addition, the electrode substrate  210  includes a transparent electrode layer  211 , and the color-filter-on-array substrate  220  includes a color filter layer  221  and a metal conduct line layer  222 . 
     However, as shown in  FIG. 1 , unexpected light emission from the light-shielding zone Z 2  frequently occurs undesirably in the known liquid crystal display apparatus  10 . This issue is also known as incomplete shield. Generally, the incomplete shield issue can be classified into two types: one is caused by the backlight leakage from the light-shielding zone Z 2  toward the display zone Z 1 , the other results from the backlight leakage from the light-shielding zone Z 2  directly to the viewer. 
     In order to prevent the backlight leakage from light-shielding zone Z 2 , two known improvement methods have been developed. The first one is to use the color filter layer  221  as a light-shielding layer, and the second one is to use a metal layer (not shown in figures) as the light-shielding layer. 
     However, the first improvement method still cannot address the light leakage issue. When the absorbance or the optical density (OD) of the color filter layer  221  is not sufficient, the backlight can still pass through the color filter layer  221  such that light leakage occurs in the light-shielding zone Z 2 . 
     The second improvement method easily causes component damages due to an electrostatic discharge effect. This effect is generated from an electrostatic discharge structure, also known as a capacitor structure, formed by the metal layer and the metal conduct line layer  222 . The component damages may be further resulted by the formation of an open circuit (OC) and generation of a huge capacitor as a physical phenomenon caused by two adjacent metal layers located too closely. Furthermore, it increases the resistance/capacity loads to delay and disturb the transmission of image signals. 
     Thus, there is a need for a display apparatus, a liquid crystal display apparatus, a liquid crystal display panel and a driving method that can prevent or at least minimize the aforementioned issues, as well as improve the light-shielding efficacy of the light-shielding zone. 
     SUMMARY 
     In one or more embodiments, a display apparatus includes a display zone and a light-shielding zone disposed adjacent to at least one side of the display zone. The light-shielding zone includes an electrically controlled material having a controllable light shielding rate. A driving method of the display apparatus includes the step of controlling the light shielding rate of the electrically controlled material in the light-shielding zone to shield light in accordance with a control signal. 
     In one or more embodiments, a display apparatus comprises a display zone, and a light-shielding zone disposed adjacent to at least one side of the display zone. The light-shielding zone comprises an electrically controlled material having a controllable light shielding rate. The apparatus also includes a control circuit for controlling the light shielding rate of said electrically controlled material in the light-shielding zone to shield light in accordance with a control signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A detailed description of several exemplary embodiments will be now given with reference to the accompanying drawings, which are given for illustration only, and thus are not limitative of the present disclosure, wherein the same references relate to the same elements and wherein: 
         FIG. 1  is a partial cross-sectional view of a known liquid crystal display apparatus; 
         FIG. 2A  is a top view of a liquid crystal display apparatus in accordance with a first embodiment; 
         FIG. 2B  is a partial cross-sectional view of the liquid crystal display apparatus shown in  FIG. 2A  taken along line A-A; 
         FIGS. 3 and 4  are flow charts for different driving methods in accordance with some embodiments; 
         FIGS. 5A and 5B  are circuit block diagrams of different arrangements for a light-shielding-zone signal control module in accordance with some embodiments; 
         FIG. 6  is a flow chart for another driving method in accordance with one or more embodiments; 
         FIG. 7  is a partial cross-sectional view of another configuration for the liquid crystal display apparatus in accordance with the first embodiment; and 
         FIG. 8  is a partial cross-sectional view of a liquid crystal display apparatus in accordance with a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
     As shown in  FIGS. 2A and 2B , a liquid crystal display apparatus  30  of the first embodiment includes a backlight module  100  and a liquid crystal display panel  300 . The backlight module  100  is, for example, a direct type backlight module or a side-edge type backlight module. In the illustrated embodiment, the direct type backlight module is used as an example of the backlight module  100 . Any other types of backlight module can be used and are within the scope of this disclosure. 
     The liquid crystal display panel  300  is, for example, an in-plane-switching (IPS) type liquid crystal display panel, a twisted-nematic (TN) liquid crystal display panel, a color-filter-on-array (COA) type liquid crystal display panel or a transflective type liquid crystal display panel. The COA type liquid crystal panel described herein is used as an example. Any other types of liquid crystal display panel can be used and are within the scope of this disclosure. 
     The liquid crystal display panel  300  includes a first substrate  310 , a second substrate  320  and a liquid crystal layer  330 . The second substrate  320  is disposed opposite to the first substrate  310 . The liquid crystal layer  330  is disposed between the first substrate  310  and the second substrate  320 , and sealed with a sealant  340 . 
     The first substrate  310  includes a first electrode layer  311 . The first electrode layer  311  can be a transparent electrode layer, and its material is, for example, tin-doped indium oxide (ITO), indium zinc oxide (IZO) or aluminum zinc oxide (AZO). Other transparent and conductive materials are within the scope of this disclosure. 
     In addition, the first substrate  310  and the second substrate  320  are, for example, a combination of an electrode substrate and a color-filter-on-array substrate. Other arrangements are within the scope of this disclosure. 
     The first substrate  310  and the second substrate  320  together form a display zone Z 1  and a light-shielding zone Z 2 , and the light-shielding zone Z 2  is disposed around the display zone Z 1 , as best seen in  FIG. 2A . 
     In the light-shielding zone Z 2 , the second substrate  320  includes a first light-shielding layer  321  and a second light-shielding layer  322 . The first light-shielding layer  321  is illustrated in  FIG. 2B  to be a multi-layer structure as an example only, and can include one or more color filter layer(s) and/or one or more organic insulation layer(s). The second light-shielding layer  322  can be a second electrode layer or a metal layer. Other arrangements are within the scope of this disclosure. 
     If the second light-shielding layer  322  is a second electrode layer (which is also present in the display zone Z 1  for controlling the liquid crystal layer  330  together with the first electrode layer  311 ), it can be a transparent electrode layer as the first electrode layer  311 , and can be tin-doped indium oxide (ITO), indium zinc oxide (IZO) or aluminum zinc oxide (AZO). 
     If the second light-shielding layer  322  is a metal (non-transparent) layer (other than the second electrode layer), it is separated from a metal conduct line layer  323  on the second substrate  320  by the first light-shielding layer  321 . Therefore, the disposition of the first light-shielding layer  321  prevents a formation of an open signal circuit and an increasing of the resistance/capacity loads otherwise caused by an electrostatic discharge between the metal layer and the metal conduct line layer  323 . 
     In some embodiments, the formation processes of the first light-shielding layer  321  and the second light-shielding layer  322  of the light-shielding zone Z 2  can be integrated with the formation processes of the display zone Z 1 . Therefore, the manufacturing steps can be simplified through the integration of the formation processes. Consequentially, production costs can be reduced. 
     In addition, as shown in  FIGS. 2B and 3 , a driving method for driving the liquid crystal display panel  300 , in which the second light-shielding layer  322  is the second electrode layer, includes steps S 1000  and S 2000 . 
     The step S 1000  is to control the light shielding rate of the liquid crystal layer  330  in the display zone Z 1  in accordance with an image control signal. 
     The step S 2000  is to control the light shielding rate of the liquid crystal layer  330  in the light-shielding zone Z 2  to shield the light in accordance with an electric potential difference between the first substrate  310  and the second substrate  320 . 
     In more detail, the electric potential difference is that generated between the first electrode layer  311  on the first substrate  310  and the second electrode layer used as the second light-shielding layer  322  on the second substrate  320 . In some embodiments, the second electrode layer in the display zone Z 1  is electrically separated from the second light-shielding layer  322  in the light-shielding zone Z 2  (even though they might be still made of the same material to simplify the manufacturing process and reducing cost). In such embodiments, the image control signal in the display zone Z 1  will not be affected by the electric potential difference in the light-shielding zone Z 2 . 
     Thus, the liquid crystal layer  330  in the light-shielding zone Z 2  also has the light-shielding function and thereby improves the light-shielding efficacy of the light-shielding zone Z 2  by increasing the light shielding rate of the liquid crystal layer  330  in the light-shielding zone Z 2 . Moreover, this driving method is beneficial to reducing power consumption. When the display zone Z 1  displays a brighter image, human eyes barely sense the light leakage transmitted from the light-shielding zone Z 2 . Therefore, for reducing power consumption, the light-shielding efficacy of the liquid crystal layer in the light-shielding zone Z 2  can be relatively suppressed. By contrast, when the display zone Z 1  displays a darker image, human eyes can easily sense the light leakage transmitted from the light-shielding zone Z 2 , and thereby the light-shielding efficacy of the liquid crystal layer  330  in the light-shielding zone Z 2  should be increased, correspondingly. 
     As shown in  FIGS. 2B and 4 , another driving method for driving the liquid crystal display panel  300 , in which the second light-shielding layer  322  is a metal (non-transparent) layer other than the second electrode layer, includes a step S 3000 . 
     The step S 3000  is to control the light shielding rate of the liquid crystal layer  330  in the light-shielding zone Z 2  to shield the light in accordance with a control signal applied between the first electrode layer  311  and the second light-shielding layer  322 . 
     In more detail, the control signal can be generated by an integrated circuit (IC) in accordance with the light shielding rate of the liquid crystal layer  330  in the display zone Z 1  (i.e., in accordance with the image control signal) to improve light-shielding efficacy while reducing power consumption as disclosed above. Alternatively, the control signal can be, for example, the image control signal itself or a light-shielding-zone control signal as will be discussed below. In addition, the display zone Z 1  and the light-shielding zone Z 2  correspond to a portion of the liquid crystal layer  330  in the display zone Z 1  and another portion of the liquid crystal layer  330  in the light-shielding zone Z 2 , respectively. 
     As shown in  FIG. 5A , the liquid crystal display panel  300  in some embodiments further includes a light-shielding-zone signal control module  350 . The light-shielding-zone signal control module  350  is to receive a covering-zone operating signal  351  inputted by a user through an on screen display (OSD)  360  or generated by a timing controller  370 . In the specifically illustrated embodiment, a multiplexer  380  receives a user-inputted signal (via OSD  360 ) and a system-inputted signal (via timing controller  370 ) then selects only one signal to be the covering-zone operating signal  351  and forwards the selected signal to the light-shielding-zone signal control module  350 . After the light-shielding-zone signal control module  350  receives the covering-zone operating signal  351 , it outputs a light-shielding-zone control adjustment signal  352  to the liquid crystal layer  330  in the light-shielding zone Z 2  (i.e., between the first electrode layer  311  and second light-shielding layer  322 ) to control the light shielding rate of the liquid crystal layer  330  in the light-shielding zone Z 2 . In more detail, the covering-zone operating signal  351  can be a liquid-crystal shielding-angle signal. The liquid-crystal shielding-angle signal can be used to adjust the liquid-crystal rotating angle of liquid crystal molecules in the liquid crystal layer  330  to improve the light shielding performance of the light-shielding zone Z 2  in accordance with the need of the user (via OSD  360 ) or the system (via timing controller  370 ). 
       FIG. 5B  is another circuit block diagram of an alternative arrangement of the light-shielding zone signal control module  350 . As shown in  FIG. 5B , the light-shielding zone signal control module  350  can receive an on-screen-display-generated covering-zone operating signal  353  inputted through the on screen display  360  and a timing-controller-generated covering-zone operating signal  354  outputted from the timing controller  370 , and then output the light-shielding-zone control adjustment signal  352  to the liquid crystal layer  330  in the light-shielding zone Z 2  for controlling its light shielding rate. Since the light-shielding zone signal control module  350  in  FIG. 5B  is responsive to both the on-screen-display-generated covering-zone operating signal  353  (i.e., a user-inputted signal) and the timing-controller-generated covering-zone operating signal  354  (i.e., a system-inputted signal), it provides more precise control than the light-shielding zone signal control module  350  in  FIG. 5A  which is responsive to only one covering-zone operating signal  351  received either from the OSD  360  (i.e., a user-inputted signal) or from the timing controller  370  (i.e., a system-inputted signal). 
     As shown in  FIGS. 2B and 6 , another driving method for driving the liquid crystal display panel  300  includes a step S 4000 . 
     The step S 4000  is to control the light shielding rate of the liquid crystal layer  330  in the light-shielding zone Z 2  to shield the light by controlling the electric potential difference between the first substrate  310  and the second substrate  320  in accordance with the image control signal. 
     In more detail, the image control signal controls the electric potential difference between the first electrode layer  311  of the first substrate  310  and the second electrode layer used as the second light-shielding layer  322  of the second substrate  320 . Thus, it can provide the liquid crystal layer  330  with the light-shielding function and thereby improve the light-shielding efficacy of the light-shielding zone Z 2  by increasing the light shielding rate of the liquid crystal layer  330  in the light-shielding zone Z 2 . 
     In the aforementioned embodiments, the driving methods used to reduce light leakage are exemplarily applied to the color-filter-on-array type liquid crystal display panel; however, the driving methods can also be applied to other types of liquid crystal display panels, including, for example, but not limited to, an in-plane-switching (IPS) type liquid crystal display panel, a multi-domain-vertical-alignment (MVA) type liquid crystal display panel, a twist-nematic (TN) type liquid crystal display panel and a transflective type liquid crystal display panel etc. 
     As shown in  FIG. 7 , a liquid crystal display panel  400  of a liquid crystal display apparatus  40  includes a first substrate  410 , a second substrate  420  and a liquid crystal layer  430 . The liquid crystal display panel  400  is, for example, a multi-domain-vertical-alignment (MVA) type liquid crystal display panel. Thus, a plurality of contact holes  472  can be disposed in the second electrode layer used as a second light-shielding layer  422  in the light-shielding zone Z 2  so that it increase the reaction rate of the liquid crystal layer  430 . 
     Second Embodiment 
     As shown in  FIG. 8 , a difference between a liquid crystal display panel  500  of a liquid crystal display apparatus  50  in accordance with the second embodiment and the liquid crystal display panel  300  in accordance with the first embodiment is that the first substrate  510  and the second substrate  520  (of the liquid crystal display panel  500 ) are, for example, a combination of a color filter substrate and a thin film transistor substrate. In the illustrated embodiment, the first substrate  510  is the thin film transistor substrate and the second substrate  520  is the color filter substrate, for example only. 
     Similar to the first embodiment, the second substrate  520  includes a first light-shielding layer  521  and a second light-shielding layer  522 . The first light-shielding layer  521  is, for example, one or more color filter layer(s) and/or one or more organic insulation layer(s), and the second light-shielding layer  522  is, for example, a second electrode (transparent) layer or a metal (non-transparent) layer. 
     Therefore, similarly to the first embodiment, the first light-shielding layer  521  and the second light-shielding layer  522  can be integrated into the formation processes of the display zone Z 1  for simplifying the manufacturing steps of the liquid crystal display panel  500 , and, consequentially, it benefits in reducing the production costs. Moreover, if the second light-shielding layer  522  is a second electrode layer, the driving method can provide the liquid crystal layer  530  with the light-shielding function and thereby improve the light-shielding efficacy of the light-shielding zone Z 2  by increasing the light shielding rate of the liquid crystal layer  530  in the light-shielding zone Z 2  in accordance with the electric potential difference between the first electrode layer  511  and the second electrode layer  522 . 
     In summary, the first light-shielding layer and the second light-shielding layer are both disposed in the light-shielding zones of a liquid crystal display apparatus and the liquid crystal display panel in accordance with the disclosed embodiments. Thus, the light incompletely shielded by the first light-shielding layer can be further shielded by the second light-shielding layer so as to improve the light-shielding efficacy of the light-shielding zone. 
     The driving method for the liquid crystal display panel in some embodiments drives the liquid crystal layer in the light-shielding zone to increase its light shielding rate by the electric potential difference between the first substrate and the second substrate. It not only provides the liquid crystal layer with the light-shielding function but also further improves the light-shielding efficacy of the light-shielding zone. 
     Another driving method for the liquid crystal display panel controls the light shielding rate of the liquid crystal layer in the light-shielding zone by controlling the electric potential difference across the liquid crystal layer in the light-shielding zone in accordance with the image control signal of the display zone. Thus, it is possible to improve the light-shielding efficacy of the light-shielding zone relative to the display zone. 
     Additionally, a further driving method for the liquid crystal display panel can further control the light shielding rate of the liquid crystal layer in the light-shielding zone in accordance with a control signal. Thus, it is possible to improve the light-shielding efficacy of the light-shielding zone relative to the display zone. 
     Moreover, when the display zone displays a brighter image, human eyes barely sense the light leakage transmitted from the light-shielding zone. Therefore, for reducing power consumption, the light-shielding efficacy of the liquid crystal layer in the light-shielding zone can be relatively suppressed. By contrast, when the display zone displays a darker image, human eyes can easily sense the light leakage transmitted from the light-shielding zone, and thereby the light-shielding efficacy of the liquid crystal layer in the light-shielding zone should be increased, correspondingly. 
     As is understood by a person skilled in the art, the foregoing embodiments are illustrative rather than limiting. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure.