Abstract:
A method for adjusting backlight brightness of a screen, including the following steps of: detecting a brightness of ambient light; collecting the ambient light; adjusting a proportional ratio between collected light and light emitted from an internal light source according to the brightness of the ambient light; coupling the collected light with the light emitted from the internal light source according to the proportional ratio. An electronic device using the method is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to a method for adjusting backlight brightness of a screen and an electronic device using the method. 
         [0003]    2. Description of Related Art 
         [0004]    In various electronic devices, such as cellular phones, personal digital assistants, and audio/video players, screens are utilized to display information. 
         [0005]    Light-emitting diodes (LEDs) are usually used as backlight sources for the screens of the electronic devices. Since the brightness of the LEDs is limited, when the screens are exposed under strong light, such as strong sunlight, the screens would not be able to provide enough brightness in contrast with the strong light. Thereby, information displayed on the screens is difficult to recognize. 
         [0006]    Therefore, a method for adjusting the backlight brightness of the screen so that the displayed information can be recognized even in bright sunlight, and an electronic device using the method are needed in the industry. 
       SUMMARY OF THE INVENTION 
       [0007]    A method for adjusting backlight brightness of a screen, including the following steps of: detecting a brightness of ambient light; collecting the ambient light; adjusting a proportional ratio between collected light and light emitted from an internal light source according to the brightness of the ambient light; coupling collected light with light emitted from the internal light source according to the proportional ratio. 
         [0008]    An electronic device includes a screen for displaying information, the screen including a display panel and a backlight system including an internal light source for providing a part of the backlight and a collector unit for collecting ambient light, the collected light and the internal light provided by the internal light source being coupled for providing the backlight for the display panel; a detector for detecting a brightness of the ambient light, and generating a brightness signal; and a controller for generating a control signal according to the brightness signal, the backlight system adjusts a proportional ratio between the collected light and the internal light according to the control signal. 
         [0009]    Other systems, methods, features, and advantages of the present method and electronic device will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present system and method, and be protected by the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Many aspects of the present method and electronic device can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the inventive system and method. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0011]      FIG. 1  is a block diagram of an electronic device in accordance with an exemplary embodiment; 
           [0012]      FIG. 2  is a detailed structure of the screen in  FIG. 1 ; 
           [0013]      FIG. 3  is a block diagram of the processor in  FIG. 1 ; 
           [0014]      FIG. 4  is a schematic diagram of a relationship between the brightness of the ambient light and the percentage of the internal light; 
           [0015]      FIG. 5  is a flowchart of a method for controlling backlight brightness of a screen. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Reference will now be made to the drawings to describe exemplary and preferred embodiments of the present electronic device and method. 
         [0017]    Referring to  FIG. 1 , an electronic device  100  includes a screen  102 , a driver  104 , a detector  106 , a processor  108 , and a controller  110 . 
         [0018]    The screen  102  is used for displaying information, the information including texts, images, audio/video contents, and so on. The screen  102  includes a display panel  122  and a backlight module  124 . Pixels of the display panel  122  can be controlled to allow or disallow backlight through. 
         [0019]    The backlight module  124  includes a collector unit  132  and an internal light source  134 . The internal light source  134  is used for emitting light as a first light source of the backlight. The collector unit  132  is used for collecting ambient light as a second light source of the backlight. The ambient light that is collected by the collector unit  132  (hereinafter referring as “collected light”) acts as a supplement for the light emitted from the internal light source  134  (hereinafter referring as “internal light”). The collected light and internal light are coupled, to provide sufficient backlight for the display panel  122 . 
         [0020]    The driver  104  is used for generating the drive signal according to the information that is to be displayed on the screen  102 , thus controlling the pixels of the screen  102 . 
         [0021]    The detector  106  is used for performing a brightness detection of the ambient light. The detector  106  generates a brightness signal based on the brightness detected, and sends the brightness signal to the processor  108 . 
         [0022]    The processor  108  receives the brightness signal, and performs a light compensation calculation according to the brightness signal to determine a proportion of the collected light as a percentage of the backlight. The processor  108  is also used for providing the information that is to be displayed on the screen  102  to the driver  104 . 
         [0023]    After the processor  108  performs the light compensation calculation, the processor  108  sends compensation instructions to the controller  110 . The controller  110  receives the compensation instructions, and sends a control signal to the backlight system  124 . The backlight system  124  adjusts the proportional ratio of the collected light in the backlight according to the control signal. 
         [0024]    Preferably, the backlight system  124  adjusts the proportional ratio by modulating the internal light source  134 . As presented in Table 1, the brightness of the collected light (hereinafter refers as “external brightness”), the brightness of the internal light (hereinafter refers as “internal brightness”), the brightness of the backlight that is a combination of the collected light and the internal light (hereinafter refers as “the backlight brightness”), and the percentage of the internal light in the backlight are illustrated. 
         [0000]                                TABLE 1                   External Brightness (lumen)   500   2000   10000       Internal Brightness (lumen)   300   200   100       Backlight Brightness (lumen)   800   2200   10100       Percentage of the internal brightness (%)   37.5   9.1   1.0                    
As shown in Table 1, as the external brightness increases, the internal brightness is decreased, thus the percentage of the internal light in the backlight is reduced. At the same time, the backlight brightness gets higher with an increase in the external brightness.
 
         [0025]    Alternatively, in another exemplary embodiment, the backlight system  124  adjusts the proportional ratio by tuning an amount of the collected light that is coupled with the internal light. The backlight system  124  may include an element which is used for allowing a controllable amount of the collected light to pass. Preferably, the element is a grating or a liquid crystal device. The collected light that passes the element is coupled with the internal light. The proportional ratio of the collected light in the backlight can be controlled by utilizing the element. 
         [0026]    The electronic device  100  adds the collected light to the internal light, this ensures that the backlight brightness is always higher than the external brightness, in spite of the increase of the external brightness. Therefore, the displayed information of the screen  102  can be recognized in various environments, even under strong sunlight. 
         [0027]    Referring to  FIG. 2 , a detailed structure of the screen  102  is illustrated. The backlight system  124  includes the internal light source  134 , a collector lens  524 , a light-guide plate  526 , and a diffusion plate  528 . 
         [0028]    The internal light source  134  is used for providing a part of the backlight for the display panel  132 . Preferably, the internal light source  134  is a cold cathode fluorescent lamp (CCFL), or a light emitting diode (LED). 
         [0029]    The collector lens  524  is used for collecting the ambient light. The collected light is coupled with the internal light emitted from the internal light source  134 , thus providing the backlight for the display panel  122 . The collector lens  524  can be a preferred example for the collector unit  132  as shown in the  FIG. 1 . 
         [0030]    The light-guide plate  526  guides the backlight, which is generated by coupling the collected light with the internal light, to spread uniformly to the entire area behind the display panel. Thus the backlight is distributed on a surface also known as surface light. The surface light is projected to the diffusion plate  528 . 
         [0031]    The diffusion plate  528  is used for diffusing the surface light, and uniformly emitting diffused light to the display panel  122 . The diffused light has generally uniform brightness within the area behind the display panel  122 . 
         [0032]    Referring to  FIG. 3 , the processor  108  includes an image unit  210  and a compensation unit  220 . The image unit  210  is used for providing the information for the driver  104 . The compensation unit  220  is used for providing the compensation instruction for the controller  110  according to the brightness signal. 
         [0033]    The image unit  210  includes an information generator module  212  and an information transmitter module  214 . The information generator module  212  generates the information that is to be displayed to the users, and sends the information to the information transmitter module  214 . The transmitter module  214  is used for transmitting the information to the driver  104 . The driver  104  then generates the drive signal according to the information. 
         [0034]    The compensation unit  220  includes a signal receiver module  222 , a database  224 , a query module  226 , and an instruction transmitter module  228 . 
         [0035]    The signal receiver module  222  is used for receiving the brightness signal from the detector  106 , and forwarding the brightness signal to the query module  226 . 
         [0036]    The database  224  stores a plurality of brightness values and a plurality of proportional ratio values. Each proportional ratio value is corresponding to one of the brightness values. 
         [0037]    The query module  226  is used for generating a query instruction according to the brightness signal, and sending the query instruction to the database  224 . 
         [0038]    In response to the query instruction that is sent from the query module  226 , the database  224  provides a query result. The query result includes a proportional ratio value corresponding to the external brightness. 
         [0039]    On receiving the query result that is provided by the database  224 , the query module  226  generates a compensation instruction. The compensation instruction determines whether the collected light is going to be coupled in the backlight, and the proportional ratio that the collected light is coupled with the internal light. The compensation instruction is sent to the instruction transmitter module  228 . 
         [0040]    The instruction transmitter module  228  is used for transmitting the compensation instruction to the controller  110 . The controller  110  receives the compensation instruction, and generates a control signal accordingly, and sends the control signal to the backlight system  124 . 
         [0041]    Referring to  FIG. 4 , a schematic diagram of a relationship between the external brightness and the percentage of the internal light in the backlight is illustrated. The percentage of the internal light decreases as the external brightness increases, thus the percentage of the collected light in the backlight increases. 
         [0042]    When the external brightness is rather high, the internal brightness is far less than the external brightness. Thus, the backlight is mainly provided by the collected light, and the internal light accounts a rather small part of the backlight. When the external brightness is high enough, it is possible that the backlight is provided entirely by the collected light. 
         [0043]    When the external brightness is rather low, the internal brightness could be equivalent to the external brightness. In such situations, it is necessary to increase the percentage of the internal light in the backlight. When the environment is approximately dark, the backlight could be only provided by the internal light, for there is little collected light. 
         [0044]    Referring to  FIG. 5 , a flowchart of a method for controlling the backlight brightness of the screen is illustrated. The electronic device as shown in the  FIGS. 1 and 3  is described as a reference. 
         [0045]    Step  402 , after the electronic device  100  is initialized, the controller  110  sends an initial control signal to the backlight system  124 , for setting an initial backlight brightness. 
         [0046]    Step  404 , the detector  106  detects the external brightness, and generates the brightness signal according to the detection. The brightness signal is transmitted to the signal receiver module  222  of the processor  108 . 
         [0047]    Step  406 , the signal receiver module  222  receives the brightness signal, and transmits the brightness signal to the query module  226 . 
         [0048]    Step  408 , the query module  226  generates the query instruction according to the brightness signal, and sends the query instruction to the database  224 . 
         [0049]    Step  410 , the database  224  provides the query result for the query module  226  in response to the query instruction. The query result includes the proportional ratio value corresponding to the external brightness. 
         [0050]    Step  412 , the query module  226  generates the compensation instruction according to the query result. The compensation instruction is sent to the instruction transmitter module  228 . 
         [0051]    Step  414 , the instruction transmitter module  228  transmits the compensation instruction to the controller  110 . 
         [0052]    Step  416 , the controller  110  generates the control signal according to the compensation instruction. The control signal is sent to the backlight system  124 . 
         [0053]    Step  418 , the collector unit  132  of the backlight system  124  collects ambient light. The collector unit  132  may be a collector lens  524  as shown in  FIG. 2 . 
         [0054]    Step  420 , the backlight system  124  adjusts the proportional ratio of the collected light and the internal light in the backlight according to the control signal, and couples the collected light and the internal light emitted from the internal light source  134 , for providing the backlight for the display panel  122 . 
         [0055]    The electronic device  100  and the method utilizes the collected light as a supplement for the internal light, and couples the collected light and the internal light to provide the backlight for the display panel  122 . The backlight brightness is higher than the external brightness in any circumstance, even in bright sunlight. The internal brightness can be adjusted according to the external brightness. This avoids lightening the screen with a constant power, thus power consumption of the screen is lowered.