Patent Publication Number: US-9898949-B2

Title: Electronic device for adjusting brightness of display screen of the electronic device and method using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 201410583857.0 filed on Oct. 27, 2014, the contents of which are incorporated by reference herein. 
     FIELD 
     The subject matter herein generally relates to a method of adjusting brightness of a display device. More particularly, the present disclosure relates to a method of self learning to adjust brightness of a display screen. 
     BACKGROUND 
     Electronic devices increasingly include display screens as part of user interfaces. Display screens may be employed in a wide array of devices, including desktop computer systems, notebook computers, and handheld computing devices, as well as various consumer products, such as cellular phones and portable media players. Electronic devices also may include backlights that illuminate the display screens. Ambient light may reflect off the surface of display screens and may reduce the display contrast, thereby making it difficult to view the display screens in high ambient light conditions. Accordingly, as ambient light conditions change, the brightness of a backlight also may be changed to provide sufficient contrast between the ambient light and the backlight. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a block diagram of one embodiment of an electronic device. 
         FIG. 2  is a block diagram of one embodiment of function modules of a screen brightness adjusting system. 
         FIG. 3  is a flowchart of one embodiment of a method for adjusting brightness of a display screen of an electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are given in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The word “module,” as used hereinafter, refers to logic embodied in hardware or firmware, or to a collection of software instructions, written in a programming language, such as, for example, Java, C, or assembly. One or more software instructions in the modules may be embedded in firmware. It will be appreciated that modules may comprise connected logic units, such as gates and flip-flops, and may comprise programmable units, such as programmable gate arrays or processors. The modules described herein may be implemented as either software and/or hardware modules and may be stored in any type of non-transitory computer-readable storage medium or other computer storage device. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. 
       FIG. 1  is a block diagram of one embodiment of an electronic device. The electronic device  1  may be, but is not limited to, a desktop computer, a notebook computer, and a handheld computing device, a cellular phone or a portable media player. The electronic device  1  can include a screen brightness adjusting system  2 . In addition, the electronic device  1  further includes, but is not limited to, a light sensor  10 , a filter  11 , at least one processor  12 , storage  13 , and a display screen  14 .  FIG. 1  illustrates only one example of the electronic device  1 , other examples can include more or fewer components than illustrated, or have a different configuration of the various components in other embodiments. 
     The screen brightness adjusting system  2  includes computerized codes that, when executed by the at least one processor  12 , can automatically adjust brightness of the display screen  14  when ambient light conditions change according to user preferences. The computerized codes of the screen brightness adjusting system  2  can be stored in the storage  13 . 
     The light sensor  10  is a mechanical or electronic device that detects ambient lights and acquires illumination values of the ambient lights. 
     The filter  11  can be used to denoise the illumination values of the ambient lights. The filter  11  can be a Kalman filter, also known as linear quadratic estimation (LQE), which is an algorithm that uses a series of measurements observed over time, containing noise and other inaccuracies, and produces estimates of unknown variables that tend to be more precise than those based on a single measurement alone. 
     The at least one processor  12  can be central processing unit (CPU), a microprocessor, or other data processor chip. 
     The storage  13  can include various types of non-transitory computer-readable storage mediums. For example, the storage device  11  can be an internal storage system, such as a flash memory, a random access memory (RAM) for temporary storage of information, and/or a read-only memory (ROM) for permanent storage of information. The storage  13  can also be an external storage system, such as a hard disk, a storage card, or a data storage medium. 
     In one embodiment, the storage  13  can store user data, such as a brightness/illumination relationship table. The brightness/illumination relationship table stores a relationship between brightness values of the display screen  14  and illumination values of the ambient lights. One example of the relationship between brightness values of the display screen  14  and illumination values of the ambient lights is shown below: 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
               
             
               
                   
               
             
            
               
                 Illumination values 
                 0 
                 10  
                 110 
                 280  
                 520 
                 1200 
                 3000 
                 5000 
                 8000 
                 11500 
                 15500 
               
               
                 brightness values 
                 0  
                 10  
                 20 
                 30 
                 40 
                 70 
                 100 
                 120 
                 190 
                 210 
                 240 
               
               
                   
               
            
           
         
       
     
     The relationship between the brightness values and illumination values can be determined according to user preferences, or can be computed by self-learning the user preferences. In one embodiment, the manual adjustment by a user of the brightness value of the display screen  14  in a particular ambient light condition can be considered as a user preference. 
     The display screen  14  is a user interface. The display screen  14  can be illuminated by backlights emitted by the electronic device  1  for clear presentation of information visually. In another embodiment, the pixels of the display screen  14  are capable of emitting light and therefore the display screen  14  does not need backlights. 
       FIG. 2  is a block diagram of one embodiment of function modules of the screen brightness adjusting system. In one embodiment, the function modules of the screen brightness adjusting system  2  can include a detection module  120 , an acquiring module  121 , a processing module  122 , an analyzing module  123 , and an updating module  124 . 
     The detection module  130  can detect activation of the display screen  14  of the electronic device  1 , and enable the light sensor  10  after detecting the display screen  14  is activated. In one embodiment, when a predetermined key is pressed, the detection module  13  can determine the display screen  14  is activated, then, the light sensor  10  is enabled to detect ambient lights and acquire a current illumination value of the ambient lights. 
     The acquiring module  121  can acquire a current brightness value of the display screen  14  and further acquire the current illumination value of the ambient lights. In one embodiment, the current brightness value and the current illumination value can constitute a feature value F=(l, b), where l is the current illumination value, and b is the current brightness value. 
     The processing module  122  can denoise the current illumination value, and normalize the current brightness value and the current illumination value. In one embodiment, the processing module  122  denoises the current illumination value for deleting shadow phenomenon in the ambient lights. In one embodiment, the processing module  122  normalizes the current brightness value and the current illumination value using the following formulas: 
     
       
         
           
             
               
                 l 
                 norm 
               
               = 
               
                 
                   
                     log 
                     10 
                   
                   ⁢ 
                   l 
                 
                 
                   
                     log 
                     10 
                   
                   ⁢ 
                   
                     l 
                     max 
                   
                 
               
             
             ; 
           
         
       
       
         
           
             
               b 
               norm 
             
             = 
             
               
                 b 
                 
                   b 
                   max 
                 
               
               . 
             
           
         
       
     
     Where l max  and b max  are preset constants, for example, l max =15500 and b max =255. After normalizing, the feature value is updated to be F=(l norm , b norm ). 
     The analyzing module  123  can adjust the current brightness value according to the current illumination value and the brightness/illumination relationship table stored in the storage  13 . In one embodiment, the analyzing module  123  adjusts the current brightness value by self-learning the user preferences as follows. 
     The analyzing module  123  generates a node group which includes a plurality of nodes according to the brightness/illumination relationship table. The node group can be N=[node 1 ,Λnode i ,Λnode n ], where node i =[b i ,l i ], i and n are integers, l i+1 &gt;l i , and b i+1 &gt;b i . For example, referring to the brightness/illumination relationship table above, node 1 =[0, 0], node 2 =[10, 10], node 1 =[20, 110], Λ node n =[240, 15500]. The updated feature value F=(l norm , b norm ) can be considered as a temporary node node c =[l c ,b c ]. In one embodiment, the analyzing module  123  searches node i  and node i+1 , where i≦c≦i+1. Furthermore, the analyzing module  123  computes a differential ΔD of an intersection point node x  of node c  and [node i , node i+1 ], where: 
     
       
         
           
             
               
                 node 
                 x 
               
               = 
               
                 
                   [ 
                   
                     
                       l 
                       x 
                     
                     , 
                     
                       b 
                       x 
                     
                   
                   ] 
                 
                 = 
                 
                   [ 
                   
                     
                       l 
                       c 
                     
                     , 
                     
                       
                         b 
                         i 
                       
                       + 
                       
                         
                           
                             
                               b 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             - 
                             
                               b 
                               i 
                             
                           
                           
                             
                               l 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             + 
                             
                               l 
                               i 
                             
                           
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               l 
                               c 
                             
                             - 
                             
                               l 
                               i 
                             
                           
                           ) 
                         
                       
                     
                   
                   ] 
                 
               
             
             ; 
             and 
           
         
       
       
         
           
             
               Δ 
               ⁢ 
               
                   
               
               ⁢ 
               D 
             
             = 
             
               
                 
                   b 
                   c 
                 
                 - 
                 
                   b 
                   x 
                 
               
               = 
               
                 
                   b 
                   c 
                 
                 - 
                 
                   
                     [ 
                     
                       
                         b 
                         i 
                       
                       + 
                       
                         
                           
                             
                               b 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             - 
                             
                               b 
                               i 
                             
                           
                           
                             
                               l 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             + 
                             
                               l 
                               i 
                             
                           
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               l 
                               c 
                             
                             - 
                             
                               l 
                               i 
                             
                           
                           ) 
                         
                       
                     
                     ] 
                   
                   . 
                 
               
             
           
         
       
     
     The analyzing module  123  can adjust the temporary node to generate a new node node k , where node k =[l k ,b k ]=[l c ,ΔD·α·η+b c ], where α [0, 1], which is a learning rate, and 
               η   =     exp   (     -         (       l   c     -     l   n       )     2       2   ⁢     σ   2           )       ,         
which is a proximate function of the Normal distribution, where σ is a standard deviation. In one embodiment, the analyzing module further compares the new node node k  with the node group N=[node 1 ,Λ node i ,Λ node n ], and further adjusts that
 
               b   k     =     {             b     k   +   1       ,       b   k     &lt;     b     k   -   1                       b   k     ,       b   k     ≥     b     k   -   1                         
when l k &gt;l k−1 . In one embodiment, the analyzing module  123  can adjust the current brightness value of the display screen  14  to be b k .
 
     The updating module  124  can update the brightness/illumination relationship table by inserting the new node node k . In other embodiments, the updating module  124  can also update the brightness/illumination relationship table according to manual adjustments of the brightness value of the display screen  14  in a particular ambient light condition. 
       FIG. 3  is a flowchart of one embodiment of a method for adjusting brightness of a display screen of an electronic device. 
     Referring to  FIG. 3 , a flowchart is presented in accordance with an example embodiment illustrated. The example method  300  is provided by way of example, as there are a variety of ways to carry out the method. The method  300  described below can be carried out using the configurations illustrated in  FIGS. 1 and 2 , for example, and various elements of these figures are referenced in explaining example method  300 . Each block shown in  FIG. 3  represents one or more processes, methods, or subroutines carried out in the exemplary method  300 . Furthermore, the illustrated order of blocks is by example only and the order of the blocks can change. Additional blocks may be added or fewer blocks may be utilized, without departing from this disclosure. The exemplary method  300  can begin at block  301 . 
     At block  301 , a detection module enables a light sensor after detecting that a display screen of an electronic device is activated. In one embodiment, when detecting a predetermined key is pressed, the detection module can determine the display screen is activated, then, enable the light sensor to detect ambient lights and acquire a current illumination value of the ambient lights. 
     At block  302 , an acquiring module acquires a current brightness value of the display screen and further acquires the current illumination value of the ambient lights. In one embodiment, the current brightness value and the current illumination value can constitute a feature value F=(l, b), where l is the current illumination value, and b is the current brightness value. 
     At block  303 , a processing module denoises the current illumination value, and normalizes the current brightness value and the current illumination value. In one embodiment, the processing module denoises the current illumination value for deleting shadow phenomenon in the ambient lights. In one embodiment, the processing module normalizes the current brightness value and the current illumination value using the following formulas: 
     
       
         
           
             
               
                 l 
                 norm 
               
               = 
               
                 
                   
                     log 
                     10 
                   
                   ⁢ 
                   l 
                 
                 
                   
                     log 
                     10 
                   
                   ⁢ 
                   
                     l 
                     max 
                   
                 
               
             
             ; 
           
         
       
       
         
           
             
               b 
               norm 
             
             = 
             
               
                 b 
                 
                   b 
                   max 
                 
               
               . 
             
           
         
       
     
     Where l max  and b max  are preset constants, for example, l max =15500 and b max =255. After normalizing, the feature value can be updated to be F=(l norm , b norm ). 
     At block  304 , an analyzing module adjusts the current brightness value according to the current illumination value and a brightness/illumination relationship table stored in a storage device. The brightness/illumination relationship table stores a relationship between brightness values of display screen and illumination values of the ambient lights. One example of the relationship between brightness values of the display screen and illumination values of the ambient lights is showed below: 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
               
             
               
                   
               
             
            
               
                 Illumination values 
                 0 
                 10 
                 110 
                 280 
                 520 
                 1200  
                 3000 
                 5000 
                 8000 
                 11500  
                 15500 
               
               
                 brightness values 
                 0 
                 10 
                 20 
                 30 
                 40 
                 70 
                 100 
                 120 
                 190 
                 210 
                 240 
               
               
                   
               
            
           
         
       
     
     The relationship between the brightness values and illumination values can be determined according to user preferences, or can be computed by self-learning the user preferences. In one embodiment, the manual adjustment of the brightness value of the display screen in a particular ambient light condition can be considered as a user preference. 
     In one embodiment, the analyzing module  123  adjusts the current brightness value by self-learning the user preferences as follows. 
     The analyzing module generates a node group which includes a plurality of nodes according to the brightness/illumination relationship table. The node group can be N=[node 1 ,Λnode 1 ,Λnode n ], where node i =[b i ,l i ], i and n are integers, l i+1 &gt;l i , and b i+1 &gt;b i . For example, referring to the brightness/illumination relationship table above, node 1 =[0, 0], node 2 =[10, 10], node 1 =[20, 110], Λ node n =[240, 15500]. The updated feature value F=(l norm , b norm ) can be considered as a temporary node node c =[l c ,b c ]. In one embodiment, the analyzing module searches node i  and node i+1 , where i≦c≦i+1. Furthermore, the analyzing module computes a differential ΔD of an intersection point node x  of node c  and [node i , node i+1 ], where: 
     
       
         
           
             
               
                 node 
                 x 
               
               = 
               
                 
                   [ 
                   
                     
                       l 
                       x 
                     
                     , 
                     
                       b 
                       x 
                     
                   
                   ] 
                 
                 = 
                 
                   [ 
                   
                     
                       l 
                       c 
                     
                     , 
                     
                       
                         b 
                         i 
                       
                       + 
                       
                         
                           
                             
                               b 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             - 
                             
                               b 
                               i 
                             
                           
                           
                             
                               l 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             + 
                             
                               l 
                               i 
                             
                           
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               l 
                               c 
                             
                             - 
                             
                               l 
                               i 
                             
                           
                           ) 
                         
                       
                     
                   
                   ] 
                 
               
             
             ; 
             and 
           
         
       
       
         
           
             
               Δ 
               ⁢ 
               
                   
               
               ⁢ 
               D 
             
             = 
             
               
                 
                   b 
                   c 
                 
                 - 
                 
                   b 
                   x 
                 
               
               = 
               
                 
                   b 
                   c 
                 
                 - 
                 
                   
                     [ 
                     
                       
                         b 
                         i 
                       
                       + 
                       
                         
                           
                             
                               b 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             - 
                             
                               b 
                               i 
                             
                           
                           
                             
                               l 
                               
                                 i 
                                 + 
                                 1 
                               
                             
                             + 
                             
                               l 
                               i 
                             
                           
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               l 
                               c 
                             
                             - 
                             
                               l 
                               i 
                             
                           
                           ) 
                         
                       
                     
                     ] 
                   
                   . 
                 
               
             
           
         
       
     
     The analyzing module further adjusts the temporary node to generate a new node node k , where node k =[l k ,b k ]=[l c ,ΔD·α·η+b c ], wherein α [0, 1], which is a learning rate, and 
               η   =     exp   (     -         (       l   c     -     l   n       )     2       2   ⁢     σ   2           )       ,         
which is a proximate function of the Normal distribution, where σ is a standard deviation. In one embodiment, the analyzing module further compares the new node node k  with the node group N=[node 1 ,Λ node i ,Λ node n ], and further adjusts that
 
               b   k     =     {             b     k   +   1       ,       b   k     &lt;     b     k   -   1                       b   k     ,       b   k     ≥     b     k   -   1                         
when l k &gt;l k−1 . In one embodiment, the analyzing module adjusts the current brightness value of the display screen  14  to be b k .
 
     At block  305 , an updating module  124  updates the brightness/illumination relationship table by inserting the new node node k . 
     The embodiments shown and described above are only examples. Many details are often found in the art. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.