Patent Publication Number: US-11651746-B2

Title: Backlight driving device and operating method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 63/217,213, filed on Jun. 30, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND 
     Technical Field 
     The disclosure relates to a display device, and more particularly to a backlight driving device and an operating method thereof. 
     Description of Related Art 
     The variable refresh rate (VRR) refers to adjusting the frame rate of a display device to match the dynamic change of the refresh rate of an image source device. In the VRR mode, the frame rate of a display panel usually changes at any time and is affected by the image scene. The VRR mode may eliminate the phenomenon of intermittent delay and screen tearing, so as to generate smoother images. In addition, the response speed of liquid crystal of a liquid-crystal display (LCD) panel is too slow, which causes motion blur. Demotion blur is a technology developed for the motion blur of the display panel. Currently, the conventional backlight panel driving method cannot satisfy VRR and demotion blur at the same time. How to perform dimming on multiple backlight zones of the backlight panel to adapt to the VRR mode of the display panel and to have the demotion blur function is one of the many technical issues in the field of backlight technology. 
     SUMMARY 
     The disclosure provides a backlight driving device and an operating method thereof to drive multiple backlight zones of a backlight panel to provide backlight to different display regions of a display panel. 
     In an embodiment of the disclosure, the backlight driving device includes an interface circuit and a driving circuit. The interface circuit is adapted for receiving first main backlight data corresponding to a first backlight zone among the backlight zones from a former stage device. The driving circuit is adapted for driving the first backlight zone among the backlight zones according to a first main current level in a display refresh period of a first backlight frame period with respect to the first backlight zone, not driving the first backlight zone in a demotion blur period of the first backlight frame period which is prior to the display refresh period, and driving the first backlight zone according to a first compensation current level in a vertical blanking period of the first backlight frame period which succeeds the display refresh period of the first backlight frame period. The driving circuit determines the first main current level according to the first main backlight data, and the first compensation current level is lower than the first main current level. 
     In an embodiment of the disclosure, the operating method includes the following steps. First main backlight data corresponding to a first backlight zone among the backlight zones is received from a former stage device by an interface circuit of a backlight driving device. The first backlight zone among the backlight zones is driven by a driving circuit of the backlight driving device according to a first main current level in a display refresh period of a first backlight frame period with respect to the first backlight zone. The first backlight zone is not driven by the driving circuit in a demotion blur period of the first backlight frame period which is prior to the display refresh period. The first backlight zone is driven by the driving circuit according to a first compensation current level in a vertical blanking period of the first backlight frame period which succeeds the display refresh period of the first backlight frame period. The driving circuit determines the first main current level according to the first main backlight data, and the first compensation current level is lower than the first main current level. 
     Based on the above, the backlight panel according to the embodiments of the disclosure has multiple backlight zones, and different backlight zones correspond to different display regions of the display panel. For any backlight zone, the backlight frame period thereof corresponds to the display frame period of the display panel. Each backlight frame period includes the demotion blur period, the display refresh period, and the vertical blanking period. The driving circuit does not drive the backlight zone in the demotion blur period, that is, the backlight zone does not provide backlight to the corresponding display region of the display panel in the demotion blur period, so as to prevent a viewer from perceiving the motion blur of the display panel. In the display refresh period which succeeds the demotion blur period, the driving circuit drives the backlight zone with the main current level corresponding to the main backlight data, so as to provide brighter backlight to the corresponding display region of the display panel. In the vertical blanking period which succeeds the display refresh period, the driving circuit drives the backlight zone with the compensation current level lower than the main current level, so as to provide darker backlight to the corresponding display region of the display panel. Therefore, the dimming of the backlight zone may be adapted to the variable refresh rate (VRR) mode of the display panel. 
     In order for the features and advantages of the disclosure to be more comprehensible, the following specific embodiments are described in detail in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of a circuit block of a display device according to an embodiment of the disclosure. 
         FIG.  2    is a schematic diagram of an equivalent circuit of a backlight zone of a backlight panel and a schematic diagram of different dimming manners. 
         FIG.  3    is a timing schematic diagram of a driving manner (line-by-line scanning) of a display panel and a local dimming manner (zoned dimming) of a backlight panel according to an embodiment. 
         FIG.  4    is a schematic diagram of a waveform of a driving current of a backlight zone according to an embodiment of the disclosure. 
         FIG.  5    is a timing diagram of a driving manner (line-by-line scanning) of a display panel and a local dimming manner (zoned dimming) of a backlight panel according to another embodiment. 
         FIG.  6    is a schematic diagram of a waveform of a driving current of a backlight zone according to another embodiment of the disclosure. 
         FIG.  7    is a timing diagram of a driving manner (line-by-line scanning) of a display panel and a local dimming manner (zoned dimming) of a backlight panel according to yet another embodiment. 
         FIG.  8    is a schematic diagram of a waveform of a driving current of a backlight zone according to yet another embodiment of the disclosure. 
         FIG.  9    is a schematic flowchart of an operating method of a backlight driving device according to an embodiment of the disclosure. 
         FIG.  10    is a schematic diagram of a circuit block of a backlight driving device according to an embodiment of the disclosure. 
         FIG.  11    is a schematic diagram of a circuit block of a backlight driving device according to another embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     The term “coupling (or connection)” used in the entire specification (including the claims) of the disclosure may refer to any direct or indirect connection means. For example, if a first device is described as being coupled (or connected) to a second device, it should be interpreted that the first device may be directly connected to the second device or the first device may be indirectly connected to the second device through another device or certain connection means. Terms such as “first” and “second” mentioned in the entire specification (including the claims) of the disclosure are used to name the elements or to distinguish between different embodiments or ranges, but not to limit the upper limit or the lower limit of the number of elements or to limit the sequence of the elements. In addition, wherever possible, elements/components/steps using the same reference numerals in the drawings and embodiments represent the same or similar parts. Related descriptions of the elements/components/steps using the same reference numerals or using the same terminologies in different embodiments may be cross-referenced. 
       FIG.  1    is a schematic diagram of a circuit block of a display device  100  according to an embodiment of the disclosure. The display device  100  shown in  FIG.  1    includes a former stage device  110 , a backlight driving device  120 , a backlight panel  130 , and a display panel  140 . According to the actual design, in some embodiments, the former stage device  110  may include an image scaler IC or a timing controller for controlling the display panel  140 . The backlight driving device  120  may drive multiple backlight zones of the backlight panel  130  to provide backlight to different display regions of the display panel  140 . For example, the backlight driving device  120  may control the backlight panel  130  to perform global dimming (to perform the same dimming on different backlight zones) or local dimming (to perform different dimming on different backlight zones). 
     Any backlight zone of the backlight panel  130  may correspond to a corresponding display region of the display panel  140 . For example, it is assumed here that one backlight zone of the backlight panel  130  corresponds to pixels of N scan lines of the display panel  140 . A first backlight zone of the backlight panel  130  corresponds to pixels of the 1-st to N-th scan lines of the display panel  140 , a second backlight zone of the backlight panel  130  corresponds to pixels of the (N+1)-th to 2N-th scan lines of the display panel  140 , a third backlight zone of the backlight panel  130  corresponds to pixels of the (2N+1)-th to 3N-th scan lines of the display panel  140 , and a fourth backlight zone of the backlight panel  130  corresponds to pixels of the (3N+1)-th to 4N-th scan lines of the display panel  140 . 
     A certain backlight zone (herein referred to as a target backlight zone) of the backlight panel  130  may provide backlight to a certain corresponding display region (herein referred to as a target display region) of the display panel  140 . The former stage device  110  may calculate main backlight data of the target backlight zone according to multiple pixel data of the target display region, and provide the main backlight data to the backlight driving device  120 . The backlight driving device  120  may drive the target backlight zone of the backlight panel  130  based on the main backlight data, so as to provide backlight to the target display region of the display panel  140 . 
       FIG.  2    is a schematic diagram of an equivalent circuit of a backlight zone of the backlight panel  130  and a schematic diagram of different dimming manners. In the embodiment shown in  FIG.  2   , the backlight panel  130  may be a light-emitting diode (LED) backlight panel. The left part of  FIG.  2    shows the equivalent circuit of a certain backlight zone of the backlight panel  130 . In the embodiment shown in  FIG.  2   , the dimming manners of the backlight zone include pulse-width-modulated (PWM) dimming and analog dimming. The upper right part of  FIG.  2    shows a schematic diagram of a current waveform of PWM dimming, and the lower right part of  FIG.  2    shows a schematic diagram of a current waveform of analog dimming, where Frame 1 , Frame 2 , Frame 3 , and Frame 4  represent different backlight frame periods. 
     The backlight driving device  120  may control a switch SW 21  and a current source CS 21  of the backlight zone shown in  FIG.  2   . By changing the duty ratio of the conduction period of the switch SW 21  of the backlight zone, the average current (average brightness) of the LED may be adjusted. By changing the current magnitude of the current source CS 21  of the backlight zone, the driving current (brightness) of the LED may be adjusted. On the premise of supporting the variable refresh rate (VRR) technology, the analog dimming manner shown in the lower right part of  FIG.  2    may be used for the control of the backlight panel  130 . Compared with the analog dimming manner, the PWM dimming manner shown in the upper right part of  FIG.  2    may cause a screen to flicker when the display panel  140  performs a VRR operation. 
     A backlight driving manner of zoned scanning will be described below with reference to  FIG.  3    and  FIG.  4   .  FIG.  3    is a timing diagram of a driving manner (line-by-line scanning) of the display panel  140  and a local dimming manner (zoned dimming) of the backlight panel  130  according to an embodiment. The upper part of  FIG.  3    is a schematic diagram of a driving timing of the display panel  140 , and the lower part of  FIG.  3    is a schematic diagram of a driving timing of the backlight panel  130 , where Fd_A and Fd_A+1 represent different display frame periods. The display frame periods Fd_A and Fd_A+1 may be defined by a vertical synchronization signal Vsync. The display frame period Fd_A includes a scanning period (valid data period) and a vertical blanking period, and the display frame period Fd_A+1 includes another scanning period (valid data period) and another vertical blanking period. 
     In the embodiment shown in  FIG.  3   , assuming that the backlight panel  130  includes 4 backlight zones Z 1 , Z 2 , Z 3 , and Z 4 , any backlight zone of the backlight panel  130  is pixels corresponding to N scanning lines of the display panel  140 . That is, the backlight zone Z 1  of the backlight panel  130  corresponds to pixels of the 1-st to N-th scan lines of the display panel  140 , the backlight zone Z 2  of the backlight panel  130  corresponds to pixels of the (N+1)-th to 2N-th scan lines of the display panel  140 , the backlight zone Z 3  of the backlight panel  130  corresponds to pixels of the (2N+1)-th to 3N-th scan lines of the display panel  140 , and the backlight zone Z 4  of the backlight panel  130  corresponds to pixels of the (3N+1)-th to 4N-th scan lines of the display panel  140 . 
     The driving timing of the backlight panel  130  is shown in the lower part of  FIG.  3   . For any backlight zone of the backlight panel  130 , the backlight frame period thereof corresponds to the display frame period of the display panel  140 . Taking the backlight zone Z 1  as an example, a backlight frame period Fb_A of the backlight zone Z 1  corresponds to the display frame period Fd_A of the display panel  140 . The backlight zones Z 1  to Z 4  of the backlight panel  130  are sequentially delay-refreshed along the vertical direction, so as to be aligned (synchronized) with the scan driving timing of the display panel  140 . The driving manner of the backlight panel  130  shown in  FIG.  3    may solve the issue of flicker and blur caused by “the brightness refresh of the backlight panel  130  being not aligned with the scan timing of the display panel  140 ”. 
       FIG.  4    is a schematic diagram of a waveform of a driving current of a backlight zone Z 1  according to an embodiment of the disclosure. The upper part of  FIG.  4    shows the backlight frame period Fb_A of the backlight zone Z 1  and the display refresh period in the backlight frame period Fb_A. The lower part of  FIG.  4    shows a main current level I 41  used by the backlight driving device  120  to drive the backlight zone Z 1  in the display refresh period. Please refer to  FIG.  3    and  FIG.  4   . In the case where demotion blur is not performed, based on a dimming algorithm, the backlight driving device  120  may determine the main current level I 41  of the backlight zone Z 1  according to the main backlight data received from the former stage device. In the display refresh period, the backlight driving device  120  may drive the corresponding backlight zone Z 1  according to the main current level I 41 . 
     A backlight driving manner of demotion blur will be described below with reference to  FIG.  5    and  FIG.  6   .  FIG.  5    and  FIG.  6    may be analogized with reference to the relevant descriptions of  FIG.  3    and  FIG.  4   .  FIG.  5    is a timing diagram of a driving manner (line-by-line scanning) of the display panel  140  and a local dimming manner (zoned dimming) of the backlight panel  130  according to another embodiment. In the embodiment shown in  FIG.  5   , due to the slow inversion speed of pixel liquid crystal, the inversion process of the pixel liquid crystal (erroneous display) may be noticed by a user, which is the so-called motion blur. In order to remove motion blur, the driving device  120  may reduce the brightness of the corresponding backlight zone (or even turn off the corresponding backlight zone) in the inversion process of the pixel liquid crystal (that is, in the demotion blur period), as shown in  FIG.  5   . For example, the backlight driving device  120  does not drive the backlight zone of the backlight panel  130  in the demotion blur period. After the liquid crystal is inverted (that is, in the display refresh period), the driving device  120  may adjust the corresponding backlight zone back to normal brightness, as shown in  FIG.  5   . For example, the backlight driving device  120  drives the corresponding backlight zone according to the main current level in the display refresh period. Therefore, the demotion blur technology of backlight shown in  FIG.  5    may reduce the erroneous display in the inversion process of the liquid crystal. 
       FIG.  6    is a schematic diagram of a waveform of a driving current of the backlight zone Z 1  according to another embodiment of the disclosure. The upper part of  FIG.  6    shows the backlight frame period Fb_A of the backlight zone Z 1 , and the demotion blur period and the display refresh period in the backlight frame period Fb_A. The lower part of  FIG.  6    shows a main current level I 61  used by the backlight driving device  120  to drive the backlight zone Z 1  in the display refresh period. For the convenience of comparison, the main current level I 41  shown in  FIG.  4    is also shown in the lower part of  FIG.  6   . 
     Please refer to  FIG.  5    and  FIG.  6   . In the case where demotion blur is performed, the backlight driving device  120  does not drive the backlight zone Z 1  of the backlight panel  130  in the demotion blur period. Based on the dimming algorithm, the backlight driving device  120  may determine the main current level I 61  of the backlight zone Z 1  according to the main backlight data received from the former stage device. In the display refresh period, the backlight driving device  120  may drive the corresponding backlight zone Z 1  according to the main current level I 61 . 
     In order to remove motion blur, the driving device  120  may reduce the driving current of the backlight zone Z 1  (reduce the brightness of the backlight zone row) in the inversion process of the pixel liquid crystal (that is, in the demotion blur period), as shown in the lower part of  FIG.  6   . After the liquid crystal is inverted (that is, in the display refresh period), the driving device  120  may increase the driving current of the backlight zone Z 1  to the main current level I 61 . Since the backlight zone Z 1  does not emit light in the demotion blur period in the backlight frame period Fb_A (for example, ⅓ of the backlight frame period Fb_A), the main current level I 61  of the backlight zone Z 1  in the display refresh period of the backlight frame period Fb_A (for example, ⅔ of the backlight frame period Fb_A) must be greater than the main current level I 41  shown in  FIG.  4   , so that the average brightness of the backlight zone Z 1  in the backlight frame period Fb_A may be close to (or the same as) the average brightness of the backlight frame period Fb_A shown in  FIG.  4   . 
     In order to increase the brightness in the remaining time after deducting the demotion blur period, the driving current level (main current level I 61 ) of the backlight zone Z 1  is increased to be greater than the main current level I 41  shown in  FIG.  4   . For example, assuming that the main current level I 41  (the original driving current level calculated based on the dimming algorithm) shown in  FIG.  4    is I, and the demotion blur period and the display refresh period are respectively ⅓ of the backlight frame period Fb_A and ⅔ of the backlight frame period Fb_A, the driving current level (main current level I 61 ) of the backlight zone Z 1  may be increased to I*3/2 after the demotion blur period ends. 
     A backlight driving manner that combines the demotion blur function (as shown in the example shown in  FIG.  5    and  FIG.  6   ) and the mode supporting variable refresh rate (VRR) will be described below with reference to  FIG.  7    and  FIG.  8   .  FIG.  7    and  FIG.  8    may be analogized with reference to the relevant descriptions of  FIG.  5    and  FIG.  6   .  FIG.  7    is a timing diagram of a driving manner (line-by-line scanning) of the display panel  140  and a local dimming manner (zoned dimming) of the backlight panel  130  according to yet another embodiment. In the embodiment shown in  FIG.  7   , based on the VRR technology, the length of each display frame period may be dynamically adjusted, that is, the frame rate may be dynamically changed. When the frame rate changes, the length of the vertical blanking (V-blanking) period of each display frame period changes at any time. Taking the display frame periods Fd_A and Fd_A+1 shown in  FIG.  7    as an example, the vertical blanking period of the display frame period Fd_A is greater than the vertical blanking period of the display frame period Fd_A+1. 
     Based on the demotion blur technology, the demotion blur period (the backlight zone not emitting light) occupies a part of each backlight frame period. In order to compensate for the period without light emission, the brightness of the backlight zone is increased in the display refresh period of the backlight frame period. In the VRR mode, however, the length of each vertical blanking period changes over time. If the brightness of the backlight zone in the vertical blanking period is the same as the increased brightness in the display refresh period, it is conceivable that the average brightness of different backlight frame periods cannot be kept consistent due to different lengths of the vertical blanking periods. The backlight driving device  120  may reduce the brightness of each backlight zone of the backlight panel  130  in the vertical blanking period, so that the average brightness of two adjacent backlight frame periods can be kept as consistent as possible. 
       FIG.  8    is a schematic diagram of a waveform of a driving current of the backlight zone Z 1  according to yet another embodiment of the disclosure. The upper part of  FIG.  8    shows the backlight frame period Fb_A of the backlight zone Z 1 , and the demotion blur period, the display refresh period, and the vertical blanking period in the backlight frame period Fb_A. The lower part of  FIG.  8    shows a schematic diagram of a waveform of the driving current of the backlight zone Z 1  in the backlight frame period Fb_A in the case where demotion blur is performed. The backlight driving device  120  drives the backlight zone Z 1  according to a main current level I 81  in the display refresh period, and drives the backlight zone Z 1  according to a compensation current level I 82  in the vertical blanking period. 
     In order to compensate for the demotion blur period without light emission, the brightness of the backlight zone Z 1  is increased in the display refresh period of the backlight frame period Fb_A. Based on the dimming algorithm, the backlight driving device  120  may determine the main current level I 81  of the backlight zone Z 1  according to the main backlight data received from the former stage device. In the display refresh period, the backlight driving device  120  may drive the corresponding backlight zone Z 1  according to the main current level I 81 . For the convenience of comparison, the main current level I 41  shown in  FIG.  4    is also shown in the lower part of  FIG.  8   . In the VRR mode, however, the length of each vertical blanking period changes over time. If the brightness of the backlight zone Z 1  in the vertical blanking period is the same as the increased brightness in the display refresh period, it is conceivable that the average brightness of different backlight frame periods cannot be kept consistent due to different lengths of the vertical blanking periods. The backlight driving device  120  may reduce the brightness of the backlight zone Z 1  of the backlight panel  130  in the vertical blanking period, so that the average brightness of two adjacent backlight frame periods can be kept as consistent as possible. 
       FIG.  9    is a schematic flowchart of an operating method of a backlight driving device according to an embodiment of the disclosure. Please refer to  FIG.  1    and  FIG.  9   . The backlight driving device  120  includes an interface circuit  121  and a driving circuit  122 . In Step S 910 , the interface circuit  121  may receive multiple main backlight data corresponding to multiple backlight zones (for example, the backlight zones Z 1  to Z 4  shown in  FIG.  7   ) of the backlight panel  130  from the former stage device  110 . For the convenience of illustration, the backlight zone Z 1  is used as an illustrative example below. Other backlight zones of the backlight panel  130  may be analogized with reference to the relevant description of the backlight zone Z 1 . 
     Please refer to  FIG.  1   ,  FIG.  8   , and  FIG.  9   . In Step S 920 , the driving circuit  122  may not drive the backlight zone Z 1  of the backlight panel  130  in the demotion blur period which is prior to the display refresh period. The driving circuit  122  may determine the main current level  181  according to the main backlight data provided by the interface circuit  121 . In Step S 930 , the driving circuit  122  may drive the backlight zone Z 1  of the backlight panel  130  according to the main current level I 81  in the display refresh period of the backlight frame period Fb_A with respect to the backlight zone Z 1 . For example, assuming that the main current level I 41  shown in  FIG.  4    (the original driving current level calculated based on the dimming algorithm) is I, the demotion blur period shown in  FIG.  8    is ⅓ of the valid data period (the scanning period in one display frame period of the display panel  140 ), and the display refresh period shown in  FIG.  8    is ⅔ of the valid data period. The driving circuit  122  may adjust the driving current of the backlight zone Z 1  to 0 in the demotion blur period, and increase the driving current of the backlight zone Z 1  to I*3/2 (main current level I 81 ) in the display refresh period, so as to maintain the average brightness in the valid data period at the target brightness. 
     However, different frame periods have vertical blanking periods with different lengths. In the case where the driving current is still maintained at I*3/2 (main current level I 81 ) in the vertical blanking period after the valid data period ends, it is conceivable that the average brightness of such a backlight is erroneous. In Step S 940 , the driving circuit  122  may drive the backlight zone Z 1  of the backlight panel  130  according to the compensation current level I 82  in the vertical blanking period which succeeds the display refresh period. The compensation current level I 82  is lower than the main current level I 81 . For example (but not limited to), the compensation current level I 82  may be the same as the main current level I 41  (the original driving current level calculated based on the dimming algorithm) shown in  FIG.  4   . 
     According to the relevant description of the backlight zone Z 1 , the driving circuit  122  may perform similar operations on other backlight zones of the backlight panel  130  by analogy, as shown in  FIG.  7   . The driving circuit  122  may not drive the backlight zone Z 4  in the demotion blur period of a backlight frame period Fb_A′ which is prior to the display refresh period of the backlight frame period Fb_A′. The driving circuit determines the main current level of the backlight zone Z 4  according to the main backlight data corresponding to the backlight zone Z 4 . The driving circuit  122  may drive the backlight zone Z 4  according to the main current level in the display refresh period of the backlight frame period Fb_A′ with respect to the backlight zone Z 4 . The driving circuit  122  may drive the backlight zone Z 4  according to the compensation current level of the backlight zone Z 4  in the vertical blanking period of the backlight frame period Fb_A′ which succeeds the display refresh period of the backlight frame period Fb_A′. The compensation current level of the backlight zone Z 4  is lower than the main current level of the backlight zone Z 4 . 
     The backlight zone Z 1  of the backlight panel  130  may be used as a backlight source of a first display region of the display panel  140 . After the first display region of the display panel  140  refreshes display data, a second display region of the display panel  140  refreshes display data. Therefore, after the backlight frame period of the backlight zone Z 1  starts, the backlight frame period of the backlight zone Z 2  starts. The backlight zone Z 2  of the backlight panel  130  may be used as a backlight source of the second display region of the display panel  140 . After the second display region of the display panel  140  refreshes the display data, a third display region of the display panel  140  refreshes display data. Therefore, after the backlight frame period of the backlight zone Z 2  starts, the backlight frame period of the backlight zone Z 3  starts. The backlight zone Z 3  of the backlight panel  130  may be used as a backlight source of the third display region of the display panel  140 . After the third display region of the display panel  140  refreshes the display data, a fourth display region of the display panel  140  refreshes display data. Therefore, after the backlight frame period of the backlight zone Z 3  starts, the backlight frame period of the backlight zone Z 4  starts. The backlight zone Z 4  of the backlight panel  130  may be used as a backlight source of the fourth display region of the display panel  140 . 
     The embodiment does not limit the determining manner of the compensation current level. For example, in some embodiments, the driving circuit  122  may obtain backlight compensation data according to a certain ratio and the main backlight data provided by the former stage device  110 , and then determine the compensation current level I 82  according to the backlight compensation data. The determination of the ratio is based on the length of the display refresh period of the backlight frame period Fb_A and the length of the demotion blur period of the backlight frame period Fb_A. 
       FIG.  10    is a schematic diagram of a circuit block of the backlight driving device  120  according to an embodiment of the disclosure. The backlight driving device  120  shown in  FIG.  10    may output multiple driving currents ILED_ 1 , ILED_ 2 , . . . , ILED_N to different backlight zones of the backlight panel  130  shown in  FIG.  1    based on the main backlight data provided by the former stage device  110 , so as to drive the backlight zones of the backlight panel  130  to provide backlight to different display regions of the display panel  140 . For example, the backlight driving device  120  may output the driving current ILED_ 1  to the backlight zone Z 1  of the backlight panel  130 , so as to drive the backlight zone Z 1  to provide backlight to the corresponding display region of the display panel  140 . The following content will describe an example of the generation of the driving current ILED_ 1 . The other driving currents ILED_ 2  to ILED_N may be analogized with reference to the relevant description of the driving current ILED_ 1 , so there will be no repetition. 
     In the embodiment shown in  FIG.  10   , the backlight driving device  120  further includes a variable refresh rate (VRR) compensation circuit  1020 , a latch  1030 , a latch  1040 , and a multiplexer (MUX)  1050 . For a driving circuit  122 _ 1  shown in  FIG.  10   , reference may be made to the relevant description of the driving circuit  122  shown in  FIG.  1   . An input terminal of the latch  1030  is coupled to the interface circuit  121  to receive and store the main backlight data corresponding to the backlight zone Z 1  of the backlight panel  130 . 
     Please refer to  FIG.  1   ,  FIG.  8   , and  FIG.  10   . An input terminal of the variable refresh rate compensation circuit  1020  is coupled to the interface circuit  121  to receive the main backlight data of the backlight zones (for example, the backlight zones Z 1  to Z 4  shown in  FIG.  7   ) of the backlight panel  130 . The variable refresh rate compensation circuit  1020  generates multiple backlight compensation data of the backlight zones according to the main backlight data. For example, the variable refresh rate compensation circuit  1020  may calculate D*m/(n+m) to generate the backlight compensation data corresponding to the backlight zone Z 1 , where D represents the main backlight data corresponding to the backlight zone Z 1 , m represents the length of the display refresh period of the backlight frame period Fb_A, and n represents the length of the demotion blur period of the backlight frame period Fb_A. 
     An input terminal of the latch  1040  is coupled to an output terminal of the variable refresh rate compensation circuit  1020  to receive and store the backlight compensation data corresponding to the backlight zone Z 1  of the backlight panel  130 . A first input terminal of the multiplexer  1050  is coupled to an output terminal of the latch  1030  to receive the main backlight data corresponding to the backlight zone Z 1 . A second input terminal of the multiplexer  1050  is coupled to an output terminal of the latch  1040  to receive the backlight compensation data corresponding to the backlight zone Z 1 . An output terminal of the multiplexer  1050  is coupled to an input terminal of the driving circuit  122 _ 1 . When the multiplexer  1050  transmits the main backlight data corresponding to the backlight zone Z 1  to the driving circuit  122 _ 1 , the driving circuit  122 _ 1  may determine the driving current ILED_ 1  to be the main current level I 81  according to the main backlight data in the display refresh period. When the multiplexer  1050  transmits the backlight compensation data corresponding to the backlight zone Z 1  to the driving circuit  122 _ 1 , the driving circuit  122 _ 1  may determine the driving current ILED_ 1  to be the compensation current level I 82  according to the backlight compensation data. 
     Except for the embodiment shown in  FIG.  10   , the determining manner of the compensation current level may be implemented according to other practical designs. For example, in other embodiments, the backlight driving device  120  may receive the main backlight data and the backlight compensation data corresponding to the backlight frame period Fb_A shown in  FIG.  8    from the former stage device  110 . The driving circuit  122  may determine the main current level I 81  in the display refresh period of the backlight frame period Fb_A according to the main backlight data, and determine the compensation current level I 82  in the vertical blanking period of the backlight frame period Fb_A according to the backlight compensation data. 
       FIG.  11    is a schematic diagram of a circuit block of the backlight driving device  120  according to another embodiment of the disclosure. The backlight driving device  120  shown in  FIG.  11    may output multiple driving currents ILED_ 1 , ILED_ 2 , . . . , ILED_N to different backlight zones of the backlight panel  130  shown in  FIG.  1    based on the main backlight data provided by the former stage device  110 , so as to drive the backlight zones of the backlight panel  130  to provide backlight to different display regions of the display panel  140 . For the backlight driving device  120  and the driving currents ILED_ 1  to ILED_N shown in  FIG.  11   , reference may be made to the relevant descriptions of the backlight driving device  120  and the driving currents ILED_ 1  to ILED_N shown in  FIG.  10   , so there will be no repetition. The following content will describe an example of the generation of the driving current ILED_ 1 . The other driving currents ILED_ 2  to ILED_N may be analogized with reference to the relevant description of the driving current ILED_ 1 , so there will be no repetition. 
     The former stage device  110  may calculate multiple main backlight data of different backlight zones according to multiple pixel data of different display regions, and provide the main backlight data of the backlight zones to the backlight driving device  120 . The former stage device  110  may also generate multiple backlight compensation data of different backlight zones according to the main backlight data. For example, taking the backlight frame period Fb_A shown in  FIG.  8    as an example, the former stage device  110  may calculate D*m/(n+m) to generate the backlight compensation data corresponding to the backlight zone Z 1 , where D represents the main backlight data corresponding to the backlight zone Z 1 , m represents the length of the display refresh period of the backlight frame period Fb_A, and n represents the length of the demotion blur period of the backlight frame period Fb_A. The interface circuit  121  of the backlight driving device  120  may receive the main backlight data and the backlight compensation data corresponding to the backlight frame period Fb_A shown in  FIG.  8    from the former stage device  110 . 
     In the embodiment shown in  FIG.  11   , the backlight driving device  120  further includes a latch  1130 , a latch  1140 , and a multiplexer (MUX)  1150 . For a driving circuit  122 _ 2  shown in  FIG.  11   , reference may be made to the relevant description of the driving circuit  122  shown in  FIG.  1   . An input terminal of the latch  1130  is coupled to the interface circuit  121  to receive and store the main backlight data corresponding to the backlight zone Z 1  of the backlight panel  130 . An input terminal of the latch  1140  is coupled to the interface circuit  121  to receive and store the backlight compensation data corresponding to the backlight zone Z 1  of the backlight panel  130 . A first input terminal of the multiplexer  1150  is coupled to an output terminal of the latch  1130  to receive the main backlight data corresponding to the backlight zone Z 1 . A second input terminal of the multiplexer  1150  is coupled to an output terminal of the latch  1140  to receive the backlight compensation data corresponding to the backlight zone Z 1 . An output terminal of the multiplexer  1150  is coupled to an input terminal of the driving circuit  122 _ 2 . When the multiplexer  1150  transmits the main backlight data corresponding to the backlight zone Z 1  to the driving circuit  122 _ 2 , the driving circuit  122 _ 2  may determine the driving current ILED_ 1  to be the main current level I 81  according to the main backlight data in the display refresh period. When the multiplexer  1150  transmits the backlight compensation data corresponding to the backlight zone Z 1  to the driving circuit  122 _ 2 , the driving circuit  122 _ 2  may determine the driving current ILED_ 1  to be the compensation current level I 82  according to the backlight compensation data. 
     In summary, the backlight panel  130  of the foregoing embodiments has multiple backlight zones, such as the backlight zones Z 1  to Z 4  shown in  FIG.  7   . Different backlight zones correspond to different display regions of the display panel. For any backlight zone, the backlight frame period thereof corresponds to the display frame period of the display panel. Each backlight frame period includes the demotion blur period, the display refresh period, and the vertical blanking period. The driving circuit  122 - 2  may not drive the backlight zone in the demotion blur period, that is, the backlight zone does not provide backlight to the corresponding display region of the display panel  140  in the demotion blur period, so as to prevent the viewer from perceiving the motion blur of the display panel. In the display refresh period which succeeds the demotion blur period, the driving circuit  122 - 2  drives the backlight zone of the backlight panel  130  with the main current level (for example, the main current level I 81  shown in  FIG.  8   ) corresponding to the main backlight data, so as to provide brighter backlight to the corresponding display region of the display panel. In the vertical blanking period which succeeds the display refresh period, the driving circuit  122 - 2  drives the backlight zone of the backlight panel  130  with the compensation current level (for example, the compensation current level I 82  shown in  FIG.  8   , that is, the original driving current level calculated based on the dimming algorithm) lower than the main current level, so as to provide the original backlight brightness calculated based on the dimming algorithm to the corresponding display region of the display panel  140 . Therefore, the dimming of the backlight zone may be adapted to the variable refresh rate (VRR) mode of the display panel  140 . 
     Although the disclosure has been disclosed in the above embodiments, the embodiments are not intended to limit the disclosure. Persons skilled in the art may make some changes and modifications without departing from the spirit and scope of the disclosure. Therefore, the protection scope of the disclosure shall be defined by the appended claims.