Patent Publication Number: US-2009231307-A1

Title: Display apparatus for displaying still image with low power consumption and method of displaying still image using the display apparatus

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2008-0022594, filed Mar. 11, 2008 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Apparatuses and methods consistent with the present invention relate to a display apparatus, and more particularly, to a display apparatus which may display a still image with low power consumption. 
     2. Description of the Related Art 
     Recently, display apparatuses such as televisions (TV), monitors and the like have been flattened and enlarged by using a liquid crystal display (LCD) panel, an organic light emitting diode (OLED) panel, a plasma display panel (PDP) or the like. However, in related art display apparatuses, when an image is no longer displayed at a display panel, the display panel changes to a simple opaque black color. This state is maintained until a signal for displaying the images again is input. In this manner, the related art display apparatuses may degrade the aesthetic appearance of places where the related art display apparatuses are installed and decrease space usability. 
     SUMMARY OF THE INVENTION 
     The present invention provides a display apparatus which can display a still image when an image is no longer displayed at a display panel, and a method of displaying a still image by using the display apparatus. 
     According to an aspect of the present invention, there is provided a display apparatus including: a display panel including a picture plane on which an image is displayed; an e-paper which is spread to cover the picture plane of the display panel when the image is no longer displayed through the display panel; and a processor to apply an electric signal to display a still image on the e-paper. 
     The display apparatus may further include a pair of rollers which are spaced apart from each other across the display panel; a screen, both end portions of which are respectively supported by each of the rollers and including the e-paper in an area of the picture plane; and a driving means for driving the rollers, so that the e-paper covers the picture plane of the display panel when the image is no longer displayed through the display panel. 
     The picture plane may further include a window which is opened and corresponds to the size of the display panel in another area of the screen, and the driving means drives the rollers so as to expose the picture plane of the display panel through the window when the image is no longer displayed through the display panel. 
     According to another aspect of the present invention, there is provided a method of displaying a still image by using a display apparatus including a display panel having a picture plane on which an image is displayed and e-paper being spread so as to cover the picture plane of the display panel, the method including: spreading the e-paper to cover the picture plane of the display panel when the image is no longer displayed through the display panel; and displaying the still image through the e-paper. 
     The method of displaying the still image may further include removing the e-paper from the picture plane so as to expose the picture plane of the display panel when the image is displayed again through the display panel. 
     According to an aspect of the present invention, the displaying of the still image may include sequentially displaying a plurality of still images at predetermined intervals of time. 
     According to an aspect of the present invention, still image contents which can be displayed through the e-paper may be input to the display apparatus from another electronic device connected to the display apparatus. 
     According to an aspect of the present invention, still image contents which can be displayed through the e-paper may be input to the display apparatus through an Internet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  is a perspective view illustrating a display apparatus according to an exemplary embodiment of the present invention; 
         FIG. 2  is a schematic block diagram of a display apparatus according to an exemplary embodiment of the present invention; 
         FIG. 3  is a plan view illustrating a screen according to an exemplary embodiment of the present invention; 
         FIG. 4A  is a cross-sectional view illustrating a display apparatus according to an exemplary embodiment of the present invention, when a display panel is turned-on; and 
         FIG. 4B  is a cross-sectional view illustrating a display apparatus according to an exemplary embodiment of the present invention when a display panel is turned-off. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the invention will now be described more fully with reference to the accompanying drawings. 
     Referring to  FIG. 1 , a display apparatus  100  according to an exemplary embodiment of the present invention includes a housing including a rear case  101  and a front case  103  coupled with the rear case  101 , a supporter  105  which supports the housing, a display panel  110  including a picture plane  111  (see  FIG. 4A ) which displays an image and disposed in the housing, a first roller  115  and a second roller  117  which are disposed so as to be spaced from each other across the display panel  110 , and a screen  120 . First and second end portions  118  and  119  of the screen  120  are supported by the first and second rollers  115  and  117 . 
     The display panel  110  may be a flat display panel, such as an LCD panel, a PDP, a field emission display (FED) panel, or an OLED panel. However, the present invention is not limited thereto. A window  104 , which is open to expose the picture plane  111  of the display panel  110 , is formed in the front case  103 . 
     Referring to  FIG. 3 , the screen  120  includes an e-paper  122  formed in a first area  123  of the screen  120  to correspond to a size of the picture plane  111 , and a window  124  formed in a second area  125  of the screen  120  to be opened and correspond to the size of the picture plane  111 . The e-paper  122  has a reaction speed which is slower than that of the flat display panel, such as the LCD panel, the PDP, the OLED panel, or the FED panel, and thus is insufficient to display a moving image. However, the e-paper  122  is inexpensive and simple, and may be folded or rolled. The e-paper  122  consumes power only when an image displayed on the e-paper  122  is changed, and does not consume power while a still image is being maintained. Therefore, the e-paper  122  may display the still image with low power consumption as compared to when the still image is displayed through the flat display panels, such as an LCD panel, a PDP, an OLED panel, or a FED panel. 
     The display apparatus  100  includes a driving unit  133  for driving the rollers  115  and  117 . Referring to  FIGS. 1 and 2 , the driving unit  133  includes a first roller driving motor  136  which provides driving power to the first roller  115 , a second roller driving motor  137  provides driving power to the second roller  117 , and a controller  135  controls the first and second roller driving motors  136  and  137 . Although not shown in the drawing, gears may be formed in an end portion of the first and second rollers  115  and  117  to receive power from the first and second roller driving motors  136  and  137 . 
     When an image is no longer displayed through the display panel  110 , the controller  135  controls transmission of revolving power of the first roller driving motor  136  to the first roller  115 , and thus the first roller  115  revolves clockwise in a first direction  139 . The controller  135  controls separation of the second roller  117  from the second roller driving motor  137 , and thus the second roller  117  enters an idle state. The screen  120  is rolled onto the first roller  115 , and as a result, the e-paper  122  is overlapped with the picture plane  111  as shown in  FIG. 4B . When the picture plane  111  is covered by the e-paper  122 , the controller  135  controls the first roller driving motor  136  to stop, and the screen  120  is pulled to maintain a proper tension. 
     When an image is displayed again through the display panel  110 , the controller  135  controls transmission of revolving power of the second roller driving motor  137  to the second roller  117 , and the separation of the first roller  115  from the first roller driving motor  136 . The second roller  117  revolves counterclockwise in a second direction  141 , while the first roller  115  enters an idle state. The screen  120  is rolled into the second roller  117 , and the window  124  of the screen  120  is overlapped with the picture plane  111  as shown in  FIG. 4A . When the picture plane  111  is exposed by the window  124 , the controller  135  controls the second roller driving motor  137  to stop. The screen  120  is pulled to maintain a proper tension. However, the described driving means  133  is an example of a driving means for driving the rollers  135  and  137 . For example, the rollers  135  and  137  may be driven by only one driving motor or any other appropriate means. 
     The display apparatus  100  includes a processor  131  which applies proper electric signals to display images on the display panel  110  and the e-paper  122 , a memory  132  which stores software and data which are used in a processing operation for displaying an image, a command input unit  140  which inputs various user commands including the performing of ON/OFF operations of the display panel  110 , and an input/output (I/O) interface  138  which connects the display apparatus  100  to other electronic devices, such as a portable memory card. The processor  131 , the memory  132 , the controller  135 , the command input unit  140 , and the I/O interface  138  may be realized via various electronic devices mounted on a circuit board  130  (see  FIGS. 4A and 4B ) in the housing and a circuit pattern formed on the circuit board  130 . 
     Hereinafter, a method of displaying a still image by using the display apparatus  100  will be described. When a command for an image display is input to the processor  131  from the command input unit  140 , the processor  131  applies an appropriate electric signal to the display panel  110  to display an image on the picture plane  111  of the display panel  110 . At this point, as shown in  FIG. 4A , the window  124  of the screen  120  is overlapped with the picture plane  111 , thereby exposing the picture plane  111 . When a user inputs a command to stop the image being displayed by operating the command input unit  140 , the controller  135  controls the second roller  117  to enter an idle state and the first roller  115  to revolve clockwise in the first direction  139  so that the e-paper  122  of the screen  120  is overlapped with the picture plane  111  and covers the picture plane  111 . Since revolution of the first roller  115  and movement of the screen  120  are performed as described above, a repeated description thereof will be omitted. 
     When the command, received from the command input unit  140 , to stop the image display is transmitted to the processor  131 , the processor  131  stops applying an electric signal to the display panel  110  and applies an electric signal corresponding to a still image to the e-paper  122 . Thus, the still image, which can be seen by a user, is displayed on the e-paper  122 , as shown in  FIG. 1 . 
     The electric signal for displaying the still image on the e-paper  122  is only applied once after the e-paper  122  is spread, and the electric signal is not applied to the e-paper  122  while the same still image is maintained. However, a plurality of still images may be sequentially displayed on the e-paper  122 , which is spread in front of the display panel  110 , at predetermined intervals of time. In this case, whenever the still image is changed, an electric signal corresponding to a still image is applied to the e-paper  122 , and an electric signal is not applied to the e-paper  122  while the particular still image is maintained. 
     When a user inputs a command to restart an image display by operating the command input unit  140 , the first roller  115  enters an idle state and the second roller  117  revolves counterclockwise in the second direction  141  under the control of the controller  135  so that the window  124  of the screen  120  is overlapped with the picture plane  111  to expose the picture plane  111 , as shown in  FIG. 4A . Since revolution of the second roller  117  and movement of the screen  120  are performed as described above, a repeated description thereof will be omitted. 
     When command to restart the image display through the command input unit  140  is transmitted to the processor  131 , the processor  131  applies an electric signal for an image display to the display panel  110 . Accordingly, the image is displayed on the picture plane  111  of the display panel  110 . 
     Stopping display of an image through the display panel  110  is not performed only according to a command received by the command input unit  140 . The image display may be stopped by directly inputting a command to stop an image being displayed to the display panel  110  or by stopping the application of an electric signal to the display panel  110  according to a determination that the electric signal applied to the display panel  110  does not flow smoothly. In accord with an exemplary embodiment, when the image is no longer displayed through the display panel  110  due to various reasons, the processor  131  applies an electric signal corresponding to a still image to the e-paper  122  and controls the display apparatus  100  to display the still image as described above. 
     Still image contents which can be displayed on the e-paper  122 , may be input to the memory  132  from another electronic device connected via an I/O interface  138  and stored in the memory  132 . Also, the still image contents may be consciously or unconsciously input and stored in the memory  132  through the Internet via an Internet server  10 . For example, a user may consciously download the still image contents stored in an Internet server  10  to the display apparatus  100  by accessing a website, or the still image contents and Internet protocol TV contents may be automatically input together in the display apparatus  100  while the user is watching the Internet protocol television (IPTV) through the display apparatus  100 . For example, contents, such as an advertisement or a notification, may include still image contents which are automatically input together with the IPTV contents. 
     When an image is no longer displayed through the display panel  110 , the still image contents stored in the memory  132  may be sequentially displayed on the e-paper  122 , according to a predetermined order and intervals of time by a default setting determined by software installed in the display apparatus  100 . On the other hand, a user may display only desired still image contents on the e-paper  122  or may filter undesired still image contents, so that the undesired still image contents are not displayed, by canceling the default setting of the software and changing the default setting by himself/herself. 
     According to a display apparatus and a method of displaying a still image using the display apparatus of the exemplary embodiments, even when an image is no longer displayed through a display panel, the still image may be displayed in the same area of the screen, and thus, the display apparatus can improve the beauty of places where the display apparatus is installed and increase space usability. 
     Also, e-paper needs power only when an image displayed is changed, and extra power is unnecessary while the same still image is maintained. Thus, the display apparatus may display a still image with lower power consumption compared to when the still image is displayed through a display panel. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.