Patent Publication Number: US-11393390-B2

Title: Electronic device and brightness adjustment method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan Application Serial No. 110103720, filed on Feb. 1, 2021, and U.S. provisional application Ser. No. 63/017,135, filed on Apr. 29, 2020. The entirety of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of the specification. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The disclosure is related to an electronic device and a brightness adjustment method thereof. 
     Description of the Related Art 
     To highlight the contrast, an existing high-dynamic-range imaging (HDR) display enhances the contrast by using a local dimming technology. A backlight module lights up a display region according to requirements. Although the local dimming enhances the contrast, for the same display position, the brightness thereof changes as the display region as well as a quantity of light-emitting regions becomes larger. Therefore, the brightness of the display increases as the display region becomes larger. Consequently, the brightness of the display is inconsistent when the display displays images, which brings poor user experiences. 
     BRIEF SUMMARY OF THE INVENTION 
     According to first aspect of the disclosure, an electronic device is provided. The electronic device includes a display panel and a processor. The processor is electrically connected to the display panel, wherein the processor receives image data and calculates a display area that occupied by the image data on the display panel according to the image data, and the processor adjusts a backlight current value of the display panel according to the display area and an area-current relationship, to adjust the brightness of the display panel. 
     According to second aspect of the disclosure, a brightness adjustment method configures for adjusting the brightness of a display panel is provided. The brightness adjustment method comprises: receiving image data; calculating a display area occupied by the image data on the display panel according to the image data; and adjusting a backlight current value of the display panel according to the display area and an area-current relationship, to adjust the brightness of the display panel. 
     Based on the above, in the disclosure, a display area is determined according to image data and a backlight current value is adjusted according to different display areas, thus to dynamically adjust the brightness of the display panel. In this way, the brightness of the display panel is consistent when the display panel displays images at different areas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram of an electronic device according to an embodiment of the disclosure. 
         FIG. 2  is a schematic flowchart of a brightness adjustment method according to an embodiment of the disclosure. 
         FIG. 3  is a schematic flowchart of a brightness adjustment method according to another embodiment of the disclosure. 
         FIG. 4  is a schematic flowchart of a brightness adjustment method according to still another embodiment of the disclosure. 
         FIG. 5  is a schematic flowchart of a brightness adjustment method according to yet another embodiment of the disclosure. 
         FIG. 6A  is a schematic curve diagram of a fixed backlight current value over different display areas according to an embodiment of the disclosure. 
         FIG. 6B  is a schematic curve diagram of brightness changing over different display areas according to an embodiment of the disclosure. 
         FIG. 7A  is a schematic curve diagram of backlight current value changing over different display areas according to an embodiment of the disclosure. 
         FIG. 7B  is a schematic curve diagram of brightness maintaining consistent over different display areas according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1 , an electronic device  10  includes a display panel  12  and a processor  14 . The processor  14  is electrically connected to the display panel  12 . In this way, the processor  14  operates according to the received image data, to adjust the brightness of the display panel  12  according to the image data. In an embodiment, the processor  14  is an image processor. 
     In an embodiment, the electronic device  10  is a LED display, a notebook computer, a tablet computer, a mobile phone, or the like. 
     Referring to both  FIG. 1  and  FIG. 2 , in the electronic device  10 , the processor  14  configures to perform a brightness adjustment method. The brightness adjustment method includes the following steps: in step S 10 , the processor  14  receives image data. Next, in step S 12 , the processor  14  calculates a display area occupied by the image data on the display panel  12  according to the received image data. In step S 14 , the processor  14  adjusts a backlight current value of the display panel  12  according to the display area and an area-current relationship, and the backlight current value is adjusted as r*I 0 . I 0  is an original backlight current value, and the adjustment parameter r≤1. In this way, the brightness of the display panel  12  is changed by adjusting the backlight current value. Specifically, because the brightness of the display panel  12  increases as the display area becomes larger, and the brightness of the display panel is proportional to the backlight current value, the processor  14  selects an adjustment parameter r according to the display area, and then calculates a current backlight current value at present according to the area-current relationship (r*I 0 ). That is, when different image data is to be displayed, the display panel  12  dynamically adjusts the backlight current value according to display areas of the different image data, to maintain the brightness at the same position consistent. 
     In an embodiment, referring to  FIG. 1  to  FIG. 3 , step S 14  of adjusting the backlight current value of the display panel  12  according to the display range and the area-current relationship further includes step S 141  and step S 142 . In step S 141 , the processor  14  calculates the backlight current value according to the display range and the area-current relationship; and in step S 142 , the processor  14  sets the display panel  12  according to the backlight current value, to correspondingly adjust the brightness of the display panel  12 . 
     Specifically, as shown in  FIG. 1 , when the display area calculated by the processor  14  increases, the processor  14  reduces the backlight current value of the display panel  12  according to the display area and the area-current relationship (r decreases), to prevent the brightness of the display panel  12  to increase along with the display area. In this way, the brightness of the display panel  12  is turned down by reducing the backlight current value, to keep the current overall brightness consistent with the brightness of a previous display image. Conversely, when the display area calculated by the processor  14  decreases, the processor  14  increases the backlight current value of the display panel  12  according to the display area and the area-current relationship (r increases, and the largest backlight current value is the original backlight current value), to prevent the brightness of the display panel  12  to decrease along with the display area. In this way, the brightness of the display panel  12  is turned up through a higher backlight current value, to keep the current overall brightness consistent with the brightness of a previous display image. 
     In an embodiment, the display panel  12  further includes a backlight module  121 . Therefore, the processor  14  adjusts the brightness of the backlight module  121  according to the backlight current value. The backlight module  121  is limited to a smallest lighted region. In an embodiment, the backlight module is divided into only 1000 regions for lighting, but the resolution of the display panel  12  is far greater than 2000 regions. In this case, the display area does not completely coincide with a lighted area of the backlight module  121 . Therefore, the lighted area is further taken into consideration while adjusting the brightness of the display panel  12 . Referring to both  FIG. 1  and  FIG. 4 , in step S 20 , the processor  14  receives image data. In step S 22 , the processor  14  calculates a display area occupied by the image data on the display panel  12  according to the image data. Subsequently, in step S 24 , the processor  14  further calculates a lighted area of the backlight module  121  corresponding to the display area according to the display area. In step S 26 , the processor  14  adjusts a backlight current value of the backlight module  121  of the display panel  12  according to the lighted area corresponding to the display area and an area-current relationship, and the backlight current value is adjusted as r*I 0 . The adjustment parameter r≤1. I 0  is an original backlight current value. In this way, the brightness of the backlight module  121  is changed according to the adjusted the backlight current value, to make the brightness corresponding to different display areas (lighted areas) at the same position nearly consistent. 
     In an embodiment, referring to  FIG. 1 ,  FIG. 4 , and  FIG. 5 , step S 26  of adjusting the backlight current value of the display panel  12  according to the lighted area corresponding to the display area and the area-current relationship further includes step S 261  and step S 262 . In step S 261 , the processor  14  calculates the backlight current value according to the lighted area corresponding to the display area and the area-current relationship; and in step S 262 , the processor  14  sets the backlight module  121  of the display panel  12  according to the backlight current value. In this way, the backlight module  121  is lighted through the adjusted backlight current value, to correspondingly adjust the brightness of the display panel  12 . 
     Specifically, as shown in  FIG. 1 , when the display area increases, the corresponding lighted area also increases. To prevent the brightness of the display panel  12  from increasing along with the lighted area, the processor  14  reduces the backlight current value of the display panel  12  according to the lighted area and the area-current relationship (r decreases). In this way, the brightness of the display panel  12  is turned down by reducing the backlight current value, to keep the current overall brightness consistent with the brightness of a previous display image. Conversely, when the display area decreases, the corresponding lighted area also decreases. To prevent the brightness of the display panel  12  from decreasing along with the lighted area, the processor  14  increases the backlight current value of the display panel  12  according to the lighted area and the area-current relationship (r increases, and the largest backlight current value is the original backlight current value). In this way, the brightness of the display panel  12  is turned up through a higher backlight current value, to keep the current overall brightness consistent with the brightness of a previous display image. 
     In an embodiment, the backlight module  121  further includes a plurality of light emitting diodes (not shown in the figure), and the lighted area of the backlight module  121  corresponds to a quantity of lighted light emitting diodes in the plurality of light emitting diodes. The lighted area is not only relevant to the quantity of the lighted light emitting diodes, but also is determined by a quantity of local dimming regions. 
     In an embodiment, referring to  FIG. 1 ,  FIG. 2 , and  FIG. 4 , there are two manners for adjusting the backlight current value of the display panel  12  shown in step S 14  and step S 26 . One manner is that the processor  14  directly changes a current value to adjust the backlight current value. In an embodiment, the backlight current value is directly reduced from 10 A to 8 A. The other adjustment manner is that the processor  14  adjusts the backlight current value by changing a pulse-width modulation (PWM) setting. In an embodiment, an original setting that a backlight current value of 10 A is outputted at each time point in a specific time interval is adjusted to a setting that a backlight current value of 10 A is outputted at a half of time points in the specific time interval. 
     In an embodiment, the area-current relationship is pre-set. Referring to  FIG. 1 , in a product development stage, a fixed original backlight current value I 0  is set by the processor  14 , as shown in  FIG. 6A . A curve of a relationship between different display areas and corresponding brightness is obtained by measuring the brightness corresponding to the different display areas at the same point on the display panel  12 , as shown in  FIG. 6B . Generally, the brightness of the display panel  12  increases as the display area becomes larger. In addition, Since the brightness of the display panel  12  is proportional to the backlight current value lighting the backlight module  121 , several groups of backlight current values corresponding to different display areas are pre-set, and then other backlight current values corresponding to other display areas are calculated by using a linear interpolation method. The backlight current values corresponding to the display areas are separated into a plurality of segments, and there is a linear relationship between the segments, as shown in  FIG. 7A . That is, the relationship curve diagram shows a curve with N slope changes (N≥2). Herein, an example in which the curve has 3 slope changes is used. The area-current relationship is defined according to a curve drawn based on the foregoing linear interpolation result, and a backlight current value corresponding to each display area is adjusted to r*I 0  according to the area-current relationship. In this way, the brightness corresponding to different display areas of the same color image at the same position is consistent, as shown in  FIG. 7B . 
     Based on the above, in the disclosure, a display area is determined according to image data and a backlight current value is adjusted according to different display areas, to dynamically adjust the brightness of the display panel. In this way, the brightness of the display panel is consistent when the display panel displays images of different areas, to avoid the problem that a user is discomfort when watching the images caused by the inconsistency of the brightness of display images. 
     The embodiments described above are only used for explaining the technical ideas and characteristics of the disclosure to enable a person skilled in the art to understand and implement the content of the disclosure, and are not intended to limit the patent scope of the disclosure. That is, any equivalent change or modification made according to the spirit disclosed in the disclosure shall still fall within the patent scope of the disclosure.