Abstract:
A method for controlling light-emitting diode (LED) backlight modules applied in an electronic device is provided. The electronic device includes a first display and a second display. The second display includes at least two display areas. Each display area corresponds to one LED backlight module, and each display area displays option icons of an option type. The method includes: determining the file type of a file currently displayed on the first display and determining which of the option types the determined file type corresponds to; determining which of the at least two LED backlight modules the at least one determine option type corresponds to; and outputting control signals to turn on at least one of the determined LED backlight modules. A related electronic device is also provided.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to electronic devices capable of controlling light-emitting diode (LED) backlight modules and methods thereof and, particularly, to an electronic device capable of selectively turning on/off its LED backlight modules and a method thereof. 
         [0003]    2. Description of Related Art 
         [0004]    Electronic devices including an LCD display and a touch-sensitive display are popular. The touch-sensitive display is relatively smaller than the LCD display, and the touch-sensitive display is usually used to display option icons to control contents currently displayed on the LCD display. Conventionally, when the touch-sensitive display is turned on, a backlight module is turned on to light the whole touch-sensitive display, thus all the option icons displayed on the touch-sensitive are highlighted. However, among the option icons some of which cannot be used to control currently displayed content. Therefore, lighting the whole touch-sensitive display to cause all the displayed option icons to be highlighted wastes power of the electronic device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The components of the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of an electronic device capable of controlling LED backlight modules and a method thereof. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views. 
           [0006]      FIG. 1  is a block diagram of an electronic device in accordance with an exemplary embodiment. 
           [0007]      FIG. 2  is a schematic view showing a file displayed on a first display and option icons displayed on a second display of the electronic device of  FIG. 1 . 
           [0008]      FIG. 3  is a circuit diagram of an LED driving circuit of the electronic device of  FIG. 1 . 
           [0009]      FIG. 4  is a flowchart of a method for controlling LED backlight modules of the electronic device of  FIG. 1  in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIGS. 1-2 , an electronic device  1  includes a first display  10  and a second display  20 . In this embodiment, the first display  10  is an LCD display and the second display  20  is a touch-sensitive display. The second display  20  displays selectable option icons for controlling files displayed on the first display  10 . The second display  20  includes at least two display areas and at least two LED backlight modules, and each of the displays areas corresponds to one of the LED backlight modules. That is, when one LED backlight module is turned on, the display area corresponding to the LED backlight module is lit. The option icons are classified into at least two option types, and the option icons of one option type are displayed in the same display area (as shown in  FIG. 2 ). In this embodiment, the second display  20  includes three display areas  22 ,  24 , and  26  respectively corresponding to three LED backlight modules  220 ,  240 , and  260 . The option icons are classified into a first option type, a second option type, and a third option type. In this embodiment the second display  20  may further display scroll bars employed to cause hidden option icons to be viewable. 
         [0011]    The electronic device  1  further includes a storage unit  30  configured for storing a file type-option type table (hereinafter table A) and an option type-LED backlight module table (hereinafter table B). In table A, each file type corresponds to at least one option type, that is, the option icons of at least one option type may control files of each file type. As shown below, a first file type, for example, a WORD type, corresponds to the first option type and the second option type, and a second file type, for example, a JPEG type, corresponds to the third option type. In table B, each option type corresponds to one LED backlight module. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE A 
               
               
                   
                   
               
               
                   
                 File type 
                 Option type 
               
               
                   
                   
               
             
             
               
                   
                 First file type 
                 First option type 
               
               
                   
                   
                 Second option type 
               
               
                   
                 Second file type 
                 Third option type 
               
               
                   
                 . . . 
                 . . . 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE B 
               
               
                   
                   
               
               
                   
                 Option type 
                 LED backlight module 
               
               
                   
                   
               
             
             
               
                   
                 First option type 
                 LED backlight module 220 
               
               
                   
                 Second option type 
                 LED backlight module 240 
               
               
                   
                 Third option type 
                 LED backlight module 260 
               
               
                   
                   
               
             
          
         
       
     
         [0012]    The electronic device  1  further includes a processor  40  and an LED driving circuit  50 . The processor  40  includes an option type determining module  41 , an LED determining module  42 , and an LED control module  43 . 
         [0013]    The option type determining module  41  is configured to determine the file type of a file currently displayed on the first display  10  and determine which of the option types the determined file type corresponds to according to the table A. 
         [0014]    The LED determining module  42  is configured to determine which LED backlight module each determined option type corresponds to according to the table B. 
         [0015]    The LED control module  43  is configured to output control signals to control the LED driving circuit  50  to turn on at least one determined LED backlight module. 
         [0016]    With such configuration, the electronic device  1  can selectively turn on one or more LED backlight modules to light one or more display areas where the option icons capable of controlling the currently displayed file are displayed, which conserves power. 
         [0017]    Referring to  FIG. 3 , the LED driving circuit  50  includes a power providing module  52 , a driving module  54 , and a first connector  56 . In this embodiment, the second display  20  includes a second connector  27  coupled to the first connector  56 , and the LED backlight modules  220 ,  240 , and  260  are electrically connected to the LED driving circuit  50  via the second connector  27  and the first connector  56 . In this embodiment, the LED backlight modules  220 ,  240 , and  260  are connected in parallel, and each LED backlight module includes three diodes. 
         [0018]    The power providing module  52  is configured to provide power to the LED driving circuit  50 . The power providing module  52  includes a power port  520  and a control chip  522 . The power port  520  can be connected to a power source, for example batteries. The control chip  522  includes a voltage input (hereinafter VIN) port, a ground (hereinafter GND) port, a feedback (hereinafter FB) port, and an output (hereinafter OUT) port. The VIN port is electrically connected to the power port  520 . The FB port is electrically connected to the driving module  54  via a resistor R 3 . The control chip  522  outputs a driving current via the OUT port for turning on one or more LED backlight modules, and the value of the driving current (hereinafter I) is obtained according to the value of the current of the FB port (hereinafter I FB ). In the embodiment, the voltage value of the FB port (hereinafter V FB ) is a constant. 
         [0019]    In this embodiment, the driving module  54  includes driving sub-modules  540 ,  542 , and  544 . The driving sub-modules  540 ,  542 , and  544  are respectively connected to the LED backlight modules  220 ,  240 , and  260 . Each driving sub-module includes two N-channel metal-oxide-semiconductor field-effect transistors (hereinafter NMOSFET) Q 1  and Q 2  and a resistor R 1  connected between the first connector  56  and the ground. The drain of each NMOSFET Q 1  is connected to the first connector  56 . The source of the NMOSFET Q 1  of each driving sub-module is connected to the drain of the NMOSFET Q 2  of the driving sub-module. The source of each NMOSFET Q 2  is connected to the ground via one resistor R 1 . The gates of the NMOSFETs Q 1  and Q 2  of each driving sub-module constitute a signal input port S. Each signal input port S is connected to the processor  40  to receive the control signals from the LED control module  43 . 
         [0020]    The node d 1  between the source of the NMOSFET Q 1  and the drain of the NMOSFET Q 2  of each driving sub-module is connected to the FB port via the resistor R 3 . Each driving sub-module further includes a resistor R 2  arranged between the gate of the NMOSFET Q 2  of each driving sub-module and the ground. In this embodiment, the resistance value of each resistor R 2  is greater than that of each resistor R 1 . 
         [0021]    When the LED control module  43  outputs the control signals to the signal input port S of at least one driving sub-module, the NMOSFETs Q 1  and Q 2  of the at least one driving sub-module are turned on, and the resistor R 1  of the at least one driving sub-module is connected in parallel between the resistor R 3  and the ground. As the resistance value of each resistor R 2  is greater than that of each resistor R 1 , the path including the resistor R 2  of the at least one driving sub-module is substantially an open path. That is, the value of the current of the path can be ignored, and the FB port, the resistor R 3 , the at least one resistor R 1  connected in parallel, and the ground constitute a path. As V FB  is a constant value, I FB  is thus V FB /(R 3 +R 1 /N). N is the number of the at least one resistor R 1  connected in parallel, that is, N is the number of the at least one driving sub-module whose signal input port S receives the control signals. As V FB  and the resistance value of the resistor R 3  and the resistor R 1  are constant, I FB  varies according to N. The control chip  522  outputs the driving current to the at least one LED backlight module connected to the at least one controlling sub-module via the OUT port. In this embodiment, the control chip  522  determines the number of the at least one resistor R 1  connected in parallel according to I FB , and obtains I by a formula NV FB /R 1 , and N is the number of the at least one resistor R 1  connected in parallel. When N is one, that is, the number of the at least one driving sub-module whose signal input port S receives the control signals is one, I is V FB /R 1 , and the value of the current of the LED backlight module connected to the one controlling sub-module is V FB /R 1 . When N is two, that is, the number of the at least one driving sub-module whose signal input port S receives the control signals are two, I is 2V FB /R 1 , and the value of the current of each LED backlight module connected to one of the two driving sub-modules is still V FB /R 1 . Therefore, no matter whether one or more driving sub-modules whose signal input ports S receive the control signals, the value of the current of each LED backlight module remains unchanged, thus each LED backlight module can be normally turned on. 
         [0022]      FIG. 4  is a flowchart of a method for controlling the LED backlight modules  220 ,  240 , and  260 . 
         [0023]    In step S 401 , the option type determining module  41  determines the file type of a currently displayed file and determines which of the option types the determined file type corresponds to according to the table A. 
         [0024]    In step S 402 , the LED determining module  42  determines which LED backlight module each of the at least one determined option type corresponds to according to the table B. 
         [0025]    In step S 403 , the LED control module  43  outputs the control signals to control the LED driving circuit  50  to turn on at least one determined LED backlight module. 
         [0026]    Although the present disclosure has been specifically described on the basis of the exemplary embodiment thereof, the disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment without departing from the scope and spirit of the disclosure.