Patent Publication Number: US-2015062185-A1

Title: Electronic apparatus and method for controlling brightness for a display

Description:
BACKGROUND 
     1. Technical Field 
     The invention relates to an electronic apparatus and a method for controlling brightness for a display. Particularly, the invention relates to a method for controlling brightness for a display according to an ambient brightness. 
     2. Related Art 
     A mobile phone has a characteristic of portability which allows a user to carry it around, so that a usage environment of the mobile phone includes a dark indoor environment and a bright outdoor environment. In case of the outdoor environment, a display image of the mobile phone probably cannot be clearly viewed due to the bright ambient environment. 
     Generally, the user can adjust a brightness of the display through an interface of the mobile phone, though power consumption of high brightness display is far greater than that of general brightness display, and the usage environment of the mobile phone is not always bright. When the user sets the display to a high brightness under the bright environment, and enters a dark environment later, the high brightness of the display may cause unnecessary power consumption, which shortens a usage time of the mobile phone. 
     SUMMARY 
     The invention is directed to an electronic apparatus and a method for controlling brightness for a display, by which image visibility and a power saving requirement of the electronic apparatus are both taken into consideration. 
     The invention provides an electronic apparatus including a display, a light sensor and a controller. The display displays an image. The light sensor measures an ambient brightness received by the display. The controller is coupled to the display and the light sensor. A hardware brightness range of the display is divided into a plurality of segments, where a first segment includes a hardware lowest brightness of the display, and a last segment includes a hardware highest brightness of the display. The controller limits a display brightness of the display to one of the segments according to the ambient brightness, and the controller allows a user of the electronic apparatus to set the display brightness only when the display brightness is limited to the first segment. 
     The invention provides a method for controlling brightness for a display, which is adapted to be executed by the aforementioned electronic apparatus, and the method includes following steps. An ambient brightness received by the display is measured, where a hardware brightness range of the display is divided into a plurality of segments, where a first segment includes a hardware lowest brightness of the display, and a last segment includes a hardware highest brightness of the display. A display brightness of the display is limited to one of the segments according to the ambient brightness, and a user of the electronic apparatus is allowed to set the display brightness only when the display brightness is limited to the first segment. 
     According to the above descriptions, according to the electronic apparatus and the method for controlling brightness of the display image, image visibility of the display is automatically improved in a high brightness environment, and the display brightness of the display is automatically decreased in a low brightness environment, so as to decrease the power consumption. 
     In order to make the aforementioned and other features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic diagram of an electronic apparatus according to an embodiment of the invention. 
         FIG. 2  is a flowchart illustrating a method for controlling brightness for a display according to an embodiment of the invention. 
         FIG. 3  is a schematic diagram of a hardware brightness range of a display according to an embodiment of the invention. 
         FIG. 4  is a schematic diagram of a hardware brightness range of a display according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
       FIG. 1  is a schematic diagram of an electronic apparatus  100  according to an embodiment of the invention. The electronic apparatus  100  can be any electronic apparatus including a display, for example, a smart phone, a personal digital assistant (PDA), a digital camera, a tablet PC, a notebook computer, a desktop computer, a computer display, a television, etc. The electronic apparatus  100  includes a display  110 , a light sensor  120  and a controller  130 . The display  110  is configured to display an image. The light sensor  120  is configured to measure an ambient brightness V AB  received by the display  110 . The controller  130  is coupled to the display  110  and the light sensor  120 . The controller  130  may adjust a display brightness V D  of the display  110  according to the ambient brightness V AB , and limit a range of the display brightness V D . 
       FIG. 2  is a flowchart illustrating a method for controlling brightness for a display according to an embodiment of the invention. The method of  FIG. 2  can be executed by the electronic apparatus  100 . In step  210 , the light sensor  120  measures the ambient brightness V AB  received by the display  110 . In step  220 , the controller  130  determines whether the ambient brightness V AB  is smaller than a predetermined value T 1 . When the ambient brightness V AB  is smaller than the predetermined value T 1 , in step  230 , the controller  130  limits the display brightness V D  of the display  110  within a low brightness segment. When the ambient brightness V AB  is greater than or equal to the predetermined value T 1 , in step  240 , the controller limits the display brightness V D  of the display  110  within a high brightness segment. 
       FIG. 3  and  FIG. 4  illustrate two examples of the step S 230  and the step  240 .  FIG. 3  is a schematic diagram of a hardware brightness range  300  of the display  110  according to an embodiment of the invention. The hardware brightness range  300  covers a lowest brightness and a highest brightness that can be reached by the hardware of the display. In the hardware brightness range  300 , the left side represents lower brightness, and the right side represents higher brightness, so that the leftmost part of the hardware brightness range  300  is the hardware lowest brightness of the display  110 , and the rightmost part of the hardware brightness range  300  is the hardware highest brightness of the display  110 . As that shown in  FIG. 3 , the hardware brightness range  300  of the display  110  includes two segments  310  and  320 . The segment  310  includes the hardware lowest brightness of the display  110 , and the segment  320  includes the hardware highest brightness of the display  110 . The brightness of the segment  320  is higher than that of the segment  310 . 
     When the ambient brightness V AB  is smaller than the predetermined value T 1 , the low brightness segment of the step  230  is the segment  310 . In this case, the controller  130  allows the user of the electronic apparatus  100  to set the display brightness V D  of the display  110  in the segment  310 , and the controller  130  limits the display brightness V D  within the segment  310 . Namely, the user cannot set the display brightness V D  beyond the segment  310 . 
     When the ambient brightness V AB  is greater than or equal to the predetermined value T 1 , the high brightness segment of the step  240  is the segment  320 . In this case, the controller  130  limits the display brightness V D  within the segment  320 , and the controller  130  does not allow the user of the electronic apparatus  100  to set the display brightness V D  of the display  110 . The controller  130  can set the display brightness V D  in the segment  320  according to the ambient brightness V AB , and the display brightness V D  is directly proportional to the ambient brightness V AB . 
     In overall, when the ambient brightness V AB  is relatively low, the user can arbitrarily set the display brightness V D  in the segment  310 , though the user cannot set the display brightness V D  to the segment  320  with higher brightness. Now, the display brightness V D  set by the user cannot reach the hardware highest brightness of the display  110 . When the ambient brightness V AB  is relatively high, the controller  130  releases the segment  320  with higher brightness. Now, the user is not allowed to set the display brightness V D , and the controller  130  automatically sets the display brightness V D  according to the ambient brightness V AB . Now, the display brightness V D  may the hardware highest brightness of the display  110 . 
       FIG. 4  is a schematic diagram of a hardware brightness range  400  of the display  110  according to another embodiment of the invention. In the hardware brightness range  400 , the left side represents lower brightness, and the right side represents higher brightness, so that the leftmost part of the hardware brightness range  400  is the hardware lowest brightness of the display  110 , and the rightmost part of the hardware brightness range  400  is the hardware highest brightness of the display  110 . The hardware brightness range  400  includes three segments  410 ,  422  and  424 . The segment  410  includes the hardware lowest brightness of the display  110 , and the segment  424  includes the hardware highest brightness of the display  110 . The brightness of the segment  422  is higher than that of the segment  410 . The brightness of the segment  424  is higher than that of the segment  422 . 
     When the ambient brightness V AB  is smaller than the predetermined value T 1 , the low brightness segment of the step  230  is the segment  410 . In this case, the controller  130  allows the user of the electronic apparatus  100  to set the display brightness V D  of the display  110  in the segment  410 , and the controller  130  limits the display brightness V D  within the segment  410 . Namely, the user cannot set the display brightness V D  beyond the segment  410 . 
     When the ambient brightness V AB  is greater than or equal to the predetermined value T 1  and is smaller than another predetermined value T 1.1 , the high brightness segment of the step  240  is the segment  422 . In this case, the controller  130  limits the display brightness V D  within the segment  422 , and the controller  130  does not allow the user of the electronic apparatus  100  to set the display brightness V D  of the display  110 . The controller  130  can set the display brightness V D  in the segment  422  according to the ambient brightness V AB , and the display brightness V D  is directly proportional to the ambient brightness V AB . 
     When the ambient brightness V AB  is greater than the predetermined value T 1.1 , the high brightness segment of the step  240  is the segment  424 . In this case, the controller  130  limits the display brightness V D  within the segment  424 , and the controller  130  does not allow the user of the electronic apparatus  100  to set the display brightness V D  of the display  110 . The controller  130  can set the display brightness V D  in the segment  424  according to the ambient brightness V AB , and the display brightness V D  is directly proportional to the ambient brightness V AB . 
     In overall, when the ambient brightness V AB  is relatively low, the user can arbitrarily set the display brightness V D  in the segment  410 , though the user cannot set the display brightness V D  to the segments  422  and  424  with higher brightness. Now, the display brightness V D  set by the user cannot reach the hardware highest brightness of the display  110 . When the ambient brightness V AB  is relatively high, the controller  130  releases the segment  422  and/or the segment  424  with higher brightness. Now, the user is not allowed to set the display brightness V D , and the controller  130  automatically sets the display brightness V D  according to the ambient brightness V AB . Now, the display brightness V D  may the hardware highest brightness of the display  110 . Namely, the controller  130  allows the user to set the display brightness V D  only when the display brightness V D  is limited to the segment  410 , and the user is not allowed to set the display brightness V D , when the display brightness V D  is in other segments. 
     In the embodiment of  FIG. 3 , there is only one high brightness segment  320 , and in the embodiment of  FIG. 4 , there are two high brightness segments  422  and  424 . The number of the high brightness segments is not limited by the invention, and in other embodiments, there can be more high brightness segments. 
     Referring back to  FIG. 2 , after the steps  230  and  240  are completed, in step  245 , the controller  130  determines whether the ambient brightness V AB  is greater than another predetermined value T 2 . If the ambient brightness V AB  is smaller than or equal to the predetermined value T 2 , the method flow is ended. If the ambient brightness V AB  is greater than the predetermined value T 2 , in step  250 , the controller  130  adjusts at least one characteristic parameter of an image displayed by the display  110  according to the ambient brightness V AB , so as to improve image visibility of the display  110 . The at least one characteristic parameter may include one or more of brightness, contrast, saturation, clarity and sharpness of the aforementioned image. Each of the aforementioned characteristic parameters can be set to be directly proportional to the ambient brightness V AB . Since the relationship between each characteristic parameter and the ambient brightness V AB  can be defined in advance, the controller  130  may obtain the value of each characteristic parameter according to the ambient brightness V AB  through calculation or a lookup table. 
     The predetermined value T 2  can be one of the predetermined values used for dividing the display brightness segments, or another independent predetermined value. For example, in the embodiment of  FIG. 3 , the predetermined value T 2  can be equal to the predetermined value T 1 , or smaller than the predetermined value T 1 , or greater than the predetermined value T 1 . 
     Similarly, in the embodiment of  FIG. 4 , predetermined value T 2  can be equal to the predetermined value T 1  or T 1.1 , or smaller than the predetermined value T 1  or between T 1  and T 1.1 , or greater than the predetermined value T 1,1 . If the predetermined value T 2  is set to T 1 , adjustment of the at least one characteristic parameter is activated only when the display brightness V D  of the display  110  enters the segment  422 . If the predetermined value T 2  is set to T 1.1 , adjustment of the at least one characteristic parameter is activated only when the display brightness V D  of the display  110  enters the segment  424 . If the predetermined value T 2  is set to be smaller than the predetermined value T 1 , when the ambient brightness V AB  is increased, adjustment of the at least one characteristic parameter is first activated, and then the high brightness segment  422  or/and segment  424  is/are released. If the predetermined value T 2  is set to be between the predetermined values T 1  and T 1.1 , when the ambient brightness V AB  is increased, the high brightness segment  422  is first released, and then adjustment of the at least one characteristic parameter is activated. If the predetermined value T 2  is set to be greater than the predetermined value T 1.1 , when the ambient brightness V AB  is increased, the high brightness segment  422  is first released, and then the high brightness segment  424  is released, and then adjustment of the at least one characteristic parameter is activated. 
     In the method flow of  FIG. 2 , the controller  130  first executes the steps  210 - 240 , and then executes the steps  245 - 250 . Namely, the controller first determines the brightness segment to which the display brightness V D  is limited, and then determines whether to adjust the aforementioned at least one characteristic parameter. In another embodiment, an execution sequence of the steps  210 - 240  and the steps  245 - 250  can also be exchanged. Namely, the controller  130  may first determine whether or not to adjust the aforementioned at least one characteristic parameter, and then determines the brightness segment to which the display brightness V D  is limited. Alternatively, in another embodiment, the steps  245  and  250  can be omitted. 
     In summary, according to the electronic apparatus and the method for controlling brightness for the display, the brightness of the display can be automatically adjusted according to the ambient brightness. In the low brightness environment, an upper limit of the brightness of the display can be automatically limited to avoid the user excessively increasing the brightness of the display to cause unnecessary power consumption. In the high brightness environment, the higher brightness range of the display is automatically released, and the display brightness of the display is automatically increased. In addition, the characteristic parameters of the image can be automatically adjusted to improve image visibility of the display of the electronic apparatus. Therefore, in the invention, image visibility of the display of the electronic apparatus and the power saving requirement of the electronic apparatus can be both taken into consideration. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.