Backlight driving method and display device

Abstract

The application provides a backlight driving method and a display device. The backlight driving method comprises the following steps: determining a first time length of a first effective pulse stage corresponding to a target frame of a display panel to be displayed in a backlight driving signal according to a target duty cycle and a first period corresponding to a target previous frame; determining a second time length according to a maximum period corresponding to a frame displayed by the display panel at a minimum refresh frequency and the first period; delaying a starting time of the first effective pulse stage according to the second time length, so that a duty cycle of a driving period of the backlight driving signal corresponding to the target frame is the same as the target duty cycle, thereby improving the problem of flicker of the backlight in the process of changing the refresh frequency. The display device comprises a display panel, a plurality of backlights and a control module. The plurality of backlights are configured to provide backlight for the display panel. The control module is configured to drive the plurality of backlights according to the backlight driving method.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically to a backlight driving method and display device. Background Technology

[0002] In existing display devices, variable refresh rate technology is often used to prevent screen tearing during gameplay. When variable refresh rate technology is enabled, the frequency of the vertical sync signal on the display panel dynamically changes within a certain operating range (e.g., 60Hz–120Hz). However, when the refresh rate changes, the backlight drive signal, which uses local dimming technology, cannot change instantaneously. It only obtains the period duration of the vertical sync signal corresponding to the previous frame when the rising edge of the vertical sync signal for the next frame arrives. This results in the duty cycle of the backlight drive signal being calculated and used within the phase corresponding to the next frame, causing a mismatch between the change in the backlight drive signal and the change in the refresh rate, thus leading to flickering. Summary of the Invention

[0003] This invention provides a backlight driving method and display device, which can improve the flickering problem caused by the backlight driving signal not matching the refresh frequency change when the refresh rate changes.

[0004] This invention provides a backlight driving method, comprising:

[0005] Based on the target duty cycle and the first period corresponding to the target previous frame, the first duration of the first effective pulse phase in the backlight driving signal corresponding to the target frame of the image to be displayed on the display panel is determined; wherein, the target previous frame is a frame located before the target frame, and the backlight driving signal is used to drive the backlight of the display panel.

[0006] A second duration is determined based on the maximum period corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period, so as to postpone the start time of the first effective pulse phase according to the second duration.

[0007] Optionally, in some embodiments of the present invention, the step of determining the second duration based on the maximum period corresponding to the frame displayed by the display panel at the lowest refresh rate and the first period, and delaying the start time of the first effective pulse phase based on the second duration, includes: determining the second duration based on the difference between the maximum period and the first period, and delaying the start time of the first effective pulse phase based on the second duration.

[0008] Optionally, in some embodiments of the present invention, the step of determining the first duration of the first effective pulse phase in the backlight driving signal corresponding to the target frame of the image to be displayed on the display panel based on the target duty cycle and the first period corresponding to the target previous frame includes: determining the first duration based on the product of the target duty cycle and the first period.

[0009] Optionally, in some embodiments of the present invention, before the step of determining the first duration of the first effective pulse phase in the backlight driving signal corresponding to the target frame of the display panel based on the target duty cycle and the first period corresponding to the target previous frame, the method includes: determining the first period in the field synchronization signal corresponding to the target previous frame based on the start time of the second effective pulse phase in the field synchronization signal corresponding to the target frame.

[0010] Optionally, in some embodiments of the present invention, the time difference between the start time of the first effective pulse phase and the end time of the second effective pulse phase is equal to the second duration.

[0011] Optionally, in some embodiments of the present invention, after the step of determining a second duration based on the maximum period corresponding to the frame displayed by the display panel at the lowest refresh rate and the first period, so as to postpone the start time of the first effective pulse phase according to the second duration, the method includes: determining a third duration corresponding to a first invalid phase in the backlight driving signal that corresponds to the target frame and is located before the first effective pulse phase, based on the refresh rate of the display panel.

[0012] Based on the third duration, the first duration, and the target duty cycle, the fourth duration corresponding to the second invalid phase in the backlight driving signal that corresponds to the target frame and is located after the first valid pulse phase is determined.

[0013] Optionally, in some embodiments of the present invention, the step of determining the third duration corresponding to the first invalid phase in the backlight driving signal that corresponds to the target frame and is located before the first valid pulse phase, based on the refresh frequency of the display panel, includes: determining the third duration based on the difference between the maximum period and the minimum period corresponding to the frame displayed by the display panel at the highest refresh frequency.

[0014] Optionally, in some embodiments of the present invention, the step of determining the fourth duration corresponding to the second invalid phase in the backlight driving signal that corresponds to the target frame and is located after the first valid pulse phase, based on the third duration, the first duration, and the target duty cycle, includes: determining the fourth duration by subtracting the ratio of the first duration and the target duty cycle from the sum of the third duration and the first duration.

[0015] Optionally, in some embodiments of the present invention, after the step of determining a second duration based on the maximum period corresponding to the frame displayed by the display panel at the lowest refresh rate and the first period, to postpone the start time of the first effective pulse phase according to the second duration, the method includes:

[0016] The duration of the invalid phase in the backlight driving signal that corresponds to the target frame and is located after the first effective pulse phase is determined by subtracting the ratio of the first duration to the target duty cycle from the first duration.

[0017] The present invention also provides a display device, including a display panel, a plurality of backlights, and a control module. The plurality of backlights are configured to provide backlight to the display panel, and the control module is configured to drive the plurality of backlights according to any of the aforementioned backlight driving methods.

[0018] This invention provides a backlight driving method and a display device. The method determines a first duration of a first effective pulse phase in the backlight driving signal corresponding to the target frame of the image to be displayed on the display panel based on a target duty cycle and a first period corresponding to the target previous frame. A second duration is determined based on the maximum period corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period. The start time of the first effective pulse phase is then delayed according to the second duration, so that the duty cycle of the driving cycle of the backlight driving signal corresponding to the target frame is the same as the target duty cycle, thereby improving the backlight flickering problem during refresh rate changes. The display device includes a display panel, multiple backlight sources, and a control module. The multiple backlight sources are configured to provide backlight to the display panel, and the control module is configured to drive the multiple backlight sources according to the backlight driving method. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figures 1A-1B This is a timing diagram of the backlight driving signal and field synchronization signal in the existing technology;

[0021] Figure 2 This is a flowchart of the backlight driving method provided in an embodiment of the present invention;

[0022] Figures 3A-3B This is a timing diagram of the backlight driving signal and the field synchronization signal provided in an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the structure of the display device provided in an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. In the present invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0025] Specifically, Figures 1A-1B This is a timing diagram of the backlight drive signal and field synchronization signal in existing technology. Local backlight adjustment is a backlight driving method that controls the backlight source in zones to match the backlight brightness with the image grayscale. By controlling the brightness of the backlight zones, the goal is to improve the dynamic contrast of the image and save energy. The effectiveness of matching the backlight brightness with the image grayscale depends on the synchronization of the backlight drive signal (LED Driver) and the field synchronization signal (Vsync). Figure 1A As shown, the period T1 of the field synchronization signal Vsync must be equal to the period T2 of the backlight driver signal LEDDriver. Backlight brightness can be controlled by changing the duty cycle. For example, if the grayscale range of the display panel is 0–255, and the grayscale of the currently displayed image is 128, then the duty cycle of the backlight driver signal LEDDriver corresponding to the current display frame's period Tn should be 128 / 255 = 50%. Correspondingly, the backlight driver chip needs to be controlled so that the high-level duration Dn of the backlight driver signal LEDDriver corresponding to the current display frame's period is 50% * Tn.

[0026] When the refresh rate of the display panel and the grayscale of the display screen remain unchanged, the high-level duration Dn in the period of the current display frame remains unchanged, and the duty cycle of the period Tn of the current display frame remains unchanged at 50%, so the backlight brightness will not flicker.

[0027] However, when the refresh rate of the display panel changes, the period corresponding to the vertical sync signal Vsync changes. The high-level duration of the corresponding backlight driver signal LED Driver needs to be determined at the rising edge of the vertical sync signal Vsync, which lags by one period, to know the magnitude of the period change in the vertical sync signal Vsync due to the refresh rate change, and thus, to obtain the high-level duration of the backlight driver signal LED Driver. Specifically, as... Figure 1B As shown, when the refresh rate of the display panel changes from 60Hz of Frame(n) to 75Hz of Frame(n+1), the period corresponding to the field synchronization signal Vsync changes from T(n) = 1 / 60 to T(n+1) = 1 / 75; the high-level duration of the backlight driver signal LED Driver corresponding to the period of Frame(n) is D(n), and correspondingly, the duty cycle is Duty(n) = D(n) / T(n) = D(n) * 60; however, since the high-level duration D(n+1) of the backlight driver signal LED Driver corresponding to the period of Frame(n+1) cannot change instantaneously, it only changes when the rising edge of the field synchronization signal Vsync corresponding to Frame(n+2) arrives, thus causing the backlight driver signal LED In the Driver, the high-level duration D(n+1) of the period corresponding to Frame(n+1) remains the same as D(n). Correspondingly, the duty cycle is Duty(n+1) = D(n+1) / T(n+1) = D(n) / T(n+1) = D(n)*75. Therefore, the Duty(n+1) of Frame(n+1) is greater than the Duty(n) of Frame(n), resulting in brighter backlight. In Frame(n+2), the display panel refresh rate remains at 75Hz, and the period corresponding to the field synchronization signal Vsync is T(n+2) = 1 / 75. Because the backlight driver signal LED Driver changes in response to the refresh rate when the rising edge of the field synchronization signal Vsync corresponding to Frame(n+2) arrives, the high-level duration of the period corresponding to Frame(n+2) in the backlight driver signal LED Driver, D(n+2) = D(n) / T(n)*T(n+2) = D(n)*60 / 75; correspondingly, the duty cycle is Duty(n+2) = D(n+2) / T(n+2) = D(n)*60. Therefore, the Duty(n+2) corresponding to Frame(n+2) is less than the Duty(n+1) corresponding to Frame(n+1), and the backlight brightness returns to normal. However, the change in backlight brightness is easily noticeable to the human eye, resulting in a flickering problem.

[0028] Figure 2 This is a flowchart of a backlight driving method provided in an embodiment of the present invention. The present invention provides a backlight driving method, comprising:

[0029] Based on the target duty cycle (Duty_tar) and the first period corresponding to the target preceding frame, the first duration of the first effective pulse phase in the backlight driving signal LEDDriver corresponding to the target frame of the image to be displayed on the display panel is determined. The target preceding frame is the frame located before the target frame, and the backlight driving signal LEDDriver is used to drive the backlight of the display panel.

[0030] A second duration is determined based on the maximum period Tmax corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period, so as to postpone the start time of the first effective pulse phase according to the second duration.

[0031] Optionally, the target duty cycle (Duty_tar) in the backlight driving signal LEDDriver corresponding to the target frame can be determined based on the grayscale corresponding to the target frame. Optionally, existing calculation methods can be used to calculate the target duty cycle (Duty_tar) that matches the grayscale corresponding to the target frame.

[0032] Optionally, the target frame may refer to a single frame or multiple frames with the same grayscale; the refresh frequency of the previous frame is different from the refresh frequency of the target frame.

[0033] Optionally, the maximum period Tmax is the period in the field synchronization signal Vsync that corresponds to the frame displayed on the display panel at the lowest refresh rate; alternatively, the first period is the period in the field synchronization signal Vsync that corresponds to the previous frame, so as to realize the synchronization design of the field synchronization signal Vsync and the backlight driving signal LEDDriver.

[0034] Optionally, the first period corresponding to the target previous frame in the field synchronization signal Vsync can be determined based on the second effective pulse phase in the field synchronization signal Vsync corresponding to the target frame. Accordingly, before the step of determining the first duration of the first effective pulse phase in the backlight drive signal corresponding to the target frame of the display panel based on the target duty cycle Duty_tar and the first period corresponding to the target previous frame, the method includes: determining the first period in the field synchronization signal Vsync corresponding to the target previous frame based on the start time of the second effective pulse phase in the field synchronization signal Vsync corresponding to the target frame. That is, the time difference between the start time of the first effective pulse phase and the start time of the second effective pulse phase is the first period.

[0035] Optionally, the time difference between the end time of the first effective pulse phase and the end time of the second effective pulse phase is the first period.

[0036] Optionally, the time difference between the start time of the first effective pulse phase and the end time of the second effective pulse phase is equal to the second duration, thereby making the backlight driving signal LED Driver different from the prior art (in the prior art, the start time of the first effective pulse phase of the backlight driving signal corresponding to the target frame is the same as the end time of the second effective pulse phase of the field synchronization signal corresponding to the target frame), and making the start time of the first effective pulse phase no earlier than the end time of the second effective pulse phase, so as to achieve the synchronous design of the field synchronization signal Vsync and the backlight driving signal LED Driver, while adjusting the duty cycle of the second cycle in the backlight driving signal LED Driver corresponding to the target frame, thereby improving the backlight flicker problem during the refresh frequency change.

[0037] Optionally, multiple backlight sources can be driven by a control module according to the backlight driving method.

[0038] Optionally, the target duty cycle (Duty_tar), the first duration, the second duration, and the first period can be determined by the controller in the control module. The controller outputs a control signal to the backlight driver chip so that the backlight driver chip generates the backlight driver signal (LED Driver) according to the control signal. The duty cycle of the backlight driver signal (LED Driver) and the second period corresponding to the target frame is the target duty cycle (Duty_tar), thereby improving the backlight flickering problem during refresh frequency changes.

[0039] Figures 3A-3B This is a timing diagram of the backlight driving signal and field synchronization signal provided in an embodiment of the present invention; the explanation is based on the example that when the refresh frequency of the display panel changes, the grayscale corresponding to the target frame of the image to be displayed on the display panel needs to be matched with a backlight with a duty cycle of 50%.

[0040] Optionally, the target frame may include the nth frame (Frame(n), the (n+1)th frame (Frame(n+1), the (n+2)th frame (Frame(n+2), and the (n+3)th frame (Frame(n+3)). The nth frame (Frame(n)) is the target preceding frame of the (n+1)th frame (Frame(n+1), the (n+1)th frame (Frame(n+1)) is the target preceding frame of the (n+2)th frame (Frame(n+2), and the (n+2)th frame (Frame(n+2)) is the target preceding frame of the (n+3)th frame (Frame(n+3)).

[0041] The nth frame (n), the (n+1)th frame (n+1), the (n+2)th frame (n+2), and the (n+3)th frame (n+3) all need to be matched with a backlight with a duty cycle of 50%. Accordingly, the target duty cycle Duty_tar in the second cycle of the backlight driving signal LED Driver corresponding to the target frame is 50%.

[0042] When the target frame is the (n+1)th frame, the second period is the period LT(n+1) in the backlight driving signal LEDDriver corresponding to the (n+1)th frame; the first period is the period T(n) in the field synchronization signal Vsync corresponding to the nth frame; the second duration is the duration t(n+1) from the start time of the first effective pulse phase in the period LT(n+1) in the backlight driving signal LEDDriver corresponding to the (n+1)th frame to the falling edge time of the second effective pulse phase in the field synchronization signal Vsync corresponding to the (n+1)th frame; the first duration is the duration D(n+1) of the first effective pulse phase in the period LT(n+1) in the backlight driving signal LEDDriver corresponding to the (n+1)th frame.

[0043] When the target frame is the (n+2)th frame, the second period is the period LT(n+2) in the backlight driving signal LEDDriver corresponding to the (n+2)th frame; the first period is the period T(n+1) in the field synchronization signal Vsync corresponding to the (n+1)th frame; the second duration is the duration t(n+2) from the start time of the first effective pulse phase in the period LT(n+2) in the backlight driving signal LEDDriver corresponding to the (n+2)th frame to the falling edge time of the second effective pulse phase in the field synchronization signal Vsync corresponding to the (n+2)th frame; the first duration is the duration D(n+2) in the period LT(n+2) in the backlight driving signal LEDDriver corresponding to the (n+2)th frame.

[0044] When the target frame is the (n+3)th frame, the second period is the period LT(n+3) in the backlight driver signal LEDDriver corresponding to the (n+3)th frame; the first period is the period T(n+2) in the field synchronization signal Vsync corresponding to the (n+2)th frame; the second duration is the duration t(n+3) between the start time of the first effective pulse phase in the period LT(n+3) in the backlight driver signal LEDDriver corresponding to the (n+3)th frame and the falling edge time of the second effective pulse phase in the field synchronization signal Vsync corresponding to the (n+3)th frame; the first duration is the duration D(n+3) in the period LT(n+3) in the backlight driver signal LEDDriver corresponding to the (n+3)th frame.

[0045] When the target frame is the nth frame (Frame(n)), the second period is the period LT(n) in the backlight driving signal LEDDriver corresponding to the nth frame (Frame(n)); the second duration is the duration t(n) between the start time of the first effective pulse phase and the falling edge time of the second effective pulse phase in the field synchronization signal Vsync corresponding to the nth frame (Frame(n)) in the period LT(n) in the backlight driving signal LEDDriver corresponding to the nth frame (Frame(n)); the first duration is the duration D(n) corresponding to the first effective pulse phase in the period LT(n) in the backlight driving signal LEDDriver corresponding to the nth frame (Frame(n)).

[0046] Optionally, the step of determining the first duration of the first effective pulse phase in the backlight driving signal LED Driver corresponding to the target frame of the image to be displayed on the display panel based on the target duty cycle Duty_tar and the first period corresponding to the target previous frame includes: determining the first duration based on the product of the target duty cycle Duty_tar and the first period.

[0047] Optionally, the step of determining the second duration based on the maximum period Tmax corresponding to the frame displayed by the display panel at the lowest refresh rate and the first period, and delaying the start time of the first effective pulse phase based on the second duration, includes: determining the second duration based on the difference between the maximum period Tmax and the first period, and delaying the start time of the first effective pulse phase based on the second duration.

[0048] Specifically, the period is represented by n*t to facilitate the calculation of the duty cycle. Please continue reading. Figures 3A-3BAssuming the maximum period Tmax in the field synchronization signal Vsync corresponding to the frame displayed on the display panel at the lowest refresh rate is 100t, and taking T(n) = 80t, T(n+1) = 100t, T(n+2) = 80t, and T(n+2) = 80t as examples.

[0049] When the target frame is the (n+1)th frame Frame(n+1), the second duration t(n+1) = Tmax - T(n) = 100t - 80t = 20t; the first duration D(n+1) = Duty_tar * T(n) = 50% * 80t = 40t.

[0050] When the target frame is the (n+2)th frame, the second duration t(n+2) = Tmax - T(n+1) = 100t - 100t = 0t; the first duration D(n+2) = Duty_tar * T(n+1) = 50% * 100t = 50t.

[0051] When the target frame is the (n+3)th frame, the second duration t(n+3) = Tmax - T(n+2) = 100t - 80t = 20t; the first duration D(n+3) = Duty_tar * T(n) = 50% * 80t = 40t.

[0052] Optionally, the control module determines the target duty cycle (Duty_tar), the second duration, the first duration, and the duration of the invalid phase in the second period corresponding to the target frame during the high-level active phase of the field synchronization signal Vsync corresponding to the target frame. For example, during the second active pulse phase corresponding to the (n+1)th frame Frame(n+1) of the field synchronization signal Vsync, the control module determines the target duty cycle (Duty_tar), the second duration, the first duration, and the duration of the invalid phase in the second period corresponding to the (n+1)th frame Frame(n+1).

[0053] Optionally, to maintain alignment between the backlight driving signal LED Driver and the field synchronization signal Vsync, the invalid phase of the second period of the target frame corresponding to the backlight driving signal LED Driver may be partially located before the first valid pulse phase.

[0054] Optionally, when the invalid phase portion of the second period of the backlight driving signal LED Driver corresponding to the target frame is located before the first valid pulse phase, the duration corresponding to the invalid phase can be determined based on the refresh frequency of the display panel, the first duration, and the target duty cycle Duty_tar. Accordingly, after the step of determining the second duration based on the maximum period Tmax corresponding to the frame displayed by the display panel at the lowest refresh frequency and the first period, and delaying the start time of the first valid pulse phase based on the second duration, the method includes: determining a third duration corresponding to the first invalid phase in the backlight driving signal LED Driver that corresponds to the target frame and is located before the first valid pulse phase, based on the refresh frequency of the display panel; and determining a fourth duration corresponding to the second invalid phase in the backlight driving signal LED Driver that corresponds to the target frame and is located after the first valid pulse phase, based on the third duration, the first duration, and the target duty cycle Duty_tar.

[0055] Optionally, the third duration can be determined based on the maximum value of the second duration to achieve alignment between the backlight driving signal LED Driver and the field synchronization signal Vsync.

[0056] Optionally, the third duration is less than or equal to the maximum value of the second duration to maintain the alignment of the backlight driving signal LED Driver with the field synchronization signal Vsync.

[0057] Optionally, the maximum value of the second duration can be determined based on the difference between the maximum period Tmax and the minimum period Tmin in the field synchronization signal Vsync that corresponds to the frame displayed on the display panel at the highest refresh rate.

[0058] Optionally, the step of determining the third duration of the first invalid phase in the backlight driving signal LEDDriver corresponding to the target frame and located before the first valid pulse phase according to the refresh frequency of the display panel includes: determining the third duration based on the difference between the maximum period Tmax and the minimum period Tmin in the field synchronization signal Vsync corresponding to the frame displayed by the display panel at the highest refresh frequency.

[0059] For details, please continue reading Figure 3AThe maximum period Tmax of the field synchronization signal Vsync corresponding to the frame displayed on the display panel at the lowest refresh rate is 100t, and the minimum period Tmin of the field synchronization signal Vsync corresponding to the frame displayed on the display panel at the highest refresh rate is 80t. Therefore, the difference between the maximum period Tmax and the minimum period Tmin of the field synchronization signal Vsync is: Tmax-Tmin=100t-80t=20t.

[0060] When the target frame is the (n+1)th frame Frame(n+1), the third duration is the duration t31 in the period LT(n+1) that is located before the start time of the first effective pulse phase and whose length is the difference between the maximum period Tmax and the minimum period Tmin.

[0061] When the target frame is the (n+2)th frame Frame(n+2), the third duration is the duration t32 in the period LT(n+2) that is located before the start time of the first effective pulse phase and whose length is the difference between the maximum period Tmax and the minimum period Tmin.

[0062] When the target frame is the (n+3)th frame, the third duration is the duration t33 in the period LT(n+3) that is located before the start time of the first effective pulse phase and whose length is the difference between the maximum period Tmax and the minimum period Tmin.

[0063] When the target frame is the nth frame Frame(n), the third duration is the duration t30 in the period LT(n) that is located before the start time of the first effective pulse phase and whose length is the difference between the maximum period Tmax and the minimum period Tmin.

[0064] That is, regardless of whether it is period LT(n), period LT(n+1), period LT(n+2) or period LT(n+3), it includes an invalid phase of third duration before the first effective pulse phase.

[0065] Understandably, if the nth frame (Frame(n)) is the first frame among multiple frames with the same target duty cycle, then the difference between the start time of the effective pulse phase corresponding to the nth frame (Frame(n)) in the backlight driving signal LED Driver and the end time of the effective pulse phase corresponding to the nth frame (Frame(n)) in the field synchronization signal Vsync (i.e., t(n)) can be equal to the third duration t30, so as to achieve alignment between the backlight driving signal LED Driver and the field synchronization signal Vsync. The third duration t30 can also be less than t(n), and correspondingly, the third duration t30 is less than the difference between the maximum period Tmax and the minimum period Tmin.

[0066] Understandably, the change in the start time of the second cycle will cause the corresponding change in the end time of the second cycle to ensure that the duty cycle of the second cycle is the target duty cycle. Therefore, when the third duration t30 corresponding to the nth frame (n) in the LED driver backlight drive signal changes, the third duration t31 corresponding to the (n+1)th frame (n+1), the third duration t32 corresponding to the (n+2)th frame (n+2), and the third duration t33 corresponding to the (n+3)th frame (n+3) in the LED driver backlight drive signal will also change accordingly. Therefore, the third duration t31 corresponding to the (n+1)th frame Frame(n+1) in the backlight driving signal LED Driver, the third duration t32 corresponding to the (n+2)th frame Frame(n+2) in the backlight driving signal LED Driver, and the third duration t33 corresponding to the (n+3)th frame Frame(n+3) in the backlight driving signal LED Driver can also be less than the difference between the maximum period Tmax and the minimum period Tmin (i.e., less than the maximum value of the second duration), respectively.

[0067] Optionally, after the display device, including the display panel, is manufactured, the maximum refresh rate and minimum refresh rate of the display panel are determined, and correspondingly, the difference between the maximum period Tmax and the minimum period Tmin of the field synchronization signal Vsync is also determined. To facilitate the invocation of the backlight driving method, the difference between the maximum period Tmax and the minimum period Tmin of the field synchronization signal Vsync can be stored in a memory.

[0068] When the first duration, the third duration, and the target duty cycle (Duty_tar) are all known, the fourth duration can be calculated using the first duration, the third duration, and the target duty cycle (Duty_tar). Accordingly, the step of determining the fourth duration corresponding to the second invalid phase in the backlight driving signal LED Driver, which corresponds to the target frame and is located after the effective pulse phase, based on the third duration, the first duration, and the target duty cycle (Duty_tar), includes: determining the fourth duration by subtracting the ratio of the first duration and the target duty cycle (Duty_tar) from the sum of the third duration and the first duration, thereby obtaining the second period with a duty cycle equal to the target duty cycle (Duty_tar).

[0069] For details, please continue reading Figure 3AWhen the target frame is the (n+1)th frame, the fourth duration is the duration D(n+1)_off within the period LT(n+1) that is located after the start time of the first effective pulse phase and has a length of D(n+1) / Duty_tar - (t31 + D(n+1)). That is, D(n+1)_off = D(n+1) / Duty_tar - (t31 + D(n+1)) = 40t / 50% - (20t + 40t) = 20t.

[0070] When the target frame is the (n+2)th frame, the fourth duration is the duration D(n+2)_off within the period LT(n+2) that is located after the start time of the first effective pulse phase and has a length of D(n+2) / Duty_tar - (t32 + D(n+2)). That is, D(n+2)_off = D(n+2) / Duty_tar - (t32 + D(n+2)) = 50t / 50% - (20t + 50t) = 30t.

[0071] When the target frame is the (n+3)th frame, the fourth duration is the duration D(n+3)_off within the period LT(n+3) that is located after the start time of the first effective pulse phase and has a length of D(n+3) / Duty_tar - (t33 + D(n+3)). That is, D(n+3)_off = D(n+3) / Duty_tar - (t33 + D(n+3)) = 40t / 50% - (20t + 40t) = 20t.

[0072] When the target frame is the nth frame Frame(n), the fourth duration is the duration D(n)_off in the period LT(n) after the start time of the first effective pulse phase.

[0073] Accordingly, based on the first duration, the second duration, and the fourth duration, the duty cycle of the second period corresponding to the target frame in the backlight driving signal LED Driver is equal to the target duty cycle Duty_tar, thereby improving the flickering problem caused by the backlight driving signal not matching the refresh frequency change when the refresh rate changes.

[0074] For details, please continue reading Figure 3AWhen the target frame is the (n+1)th frame Frame(n+1), the second period LT(n+1) is the sum of the first duration D(n+1), the third duration t31, and the fourth duration D(n+1)_off, i.e., LT(n+1) = D(n+1) + t31 + D(n+1)_off = 40t + 20t + 20t = 80t. Correspondingly, the duty cycle Duty(n+1) = D(n+1) / LT(n+1) * 100% = 40t / 80t * 100% = 50%, thus making the duty cycle Duty(n+1) of the second period LT(n+1) equal to the target duty cycle Duty_tar.

[0075] When the target frame is the (n+2)th frame, the second period LT(n+2) is the sum of the first duration D(n+2), the third duration t32, and the fourth duration D(n+2)_off, i.e., LT(n+2) = D(n+2) + t32 + D(n+2)_off = 50t + 20t + 30t = 100t. Correspondingly, the duty cycle Duty(n+2) = D(n+2) / LT(n+2) * 100% = 50t / 100t * 100% = 50%, thus making the duty cycle Duty(n+2) of the second period LT(n+2) equal to the target duty cycle Duty_tar.

[0076] When the target frame is the (n+3)th frame, the second period LT(n+3) is the sum of the first duration D(n+3), the third duration t33, and the fourth duration D(n+3)_off, i.e., LT(n+3) = D(n+3) + t33 + D(n+3)_off = 40t + 20t + 20t = 80t. Correspondingly, the duty cycle Duty(n+3) = D(n+3) / LT(n+3) * 100% = 40t / 80t * 100% = 50%, thus making the duty cycle Duty(n+3) of the second period LT(n+3) equal to the target duty cycle Duty_tar.

[0077] When the target frame is the nth frame Frame(n), the second period LT(n) is the sum of the first duration D(n), the second duration t30, and the fourth duration D(n)_off.

[0078] Optionally, the invalid phase of the second period of the target frame corresponding to the backlight driving signal LED Driver may also be located after the first valid pulse phase (i.e., the case where the third duration is equal to 0).

[0079] Optionally, when the invalid phase of the second period of the backlight driving signal LED Driver corresponding to the target frame is located after the effective pulse phase, the duration corresponding to the invalid phase after the effective pulse phase in the second period can be determined according to the first duration and the target duty cycle Duty_tar. Accordingly, after the step of determining the second duration based on the maximum period Tmax corresponding to the frame displayed by the display panel at the lowest refresh rate and the first period, and delaying the start time of the first effective pulse phase according to the second duration, the method includes: determining the duration corresponding to the invalid phase in the backlight driving signal LED Driver that corresponds to the target frame and is located after the first effective pulse phase by subtracting the first duration from the ratio of the first duration and the target duty cycle Duty_tar, thereby making the duty cycle of the second period in the backlight driving signal LED Driver corresponding to the target frame the target duty cycle Duty_tar. This improves the flickering problem caused by the backlight driving signal's inability to match the refresh rate change when the backlight driving signal LED Driver drives the backlight in the second period to provide light for the display panel displaying the target frame.

[0080] For details, please continue reading Figure 3B When the target frame is the (n+1)th frame, the duration of the invalid phase is the duration D(n+1)_of of the period LT(n+1) after the start time of the first valid pulse phase, with a length of D(n+1) / Duty_tar - D(n+1). That is, D(n+1)_of = D(n+1) / Duty_tar - D(n+1) = 40t / 50% - 40t = 40t.

[0081] When the target frame is the (n+2)th frame, the duration of the invalid phase is the duration D(n+2)_of within the period LT(n+2) that is located after the start time of the first valid pulse phase and has a length of D(n+2) / Duty_tar - D(n+2). That is, D(n+2)_of = D(n+1) / Duty_tar - D(n+2) = 50t / 50% - 50t = 50t.

[0082] When the target frame is the (n+3)th frame, the duration of the invalid phase is the duration D(n+3)_of within the period LT(n+3) that is located after the start time of the first valid pulse phase and has a length of D(n+3) / Duty_tar - D(n+3). That is, D(n+3)_of = D(n+3) / Duty_tar - D(n+3) = 40t / 50% - 40t = 40t.

[0083] When the target frame is the nth frame Frame(n), the duration of the invalid phase is the duration D(n)_of in the period LT(n) after the start time of the first valid pulse phase.

[0084] Accordingly, based on the first duration and the duration of the invalid phase, a second period that satisfies the duty cycle of the target duty cycle Duty_tar can be obtained to improve the flickering problem caused by the backlight drive signal change not matching the refresh frequency change.

[0085] For details, please continue reading Figure 3B When the target frame is the (n+1)th frame, the second period LT(n+1) is the sum of the first duration D(n+1) and the duration D(n+1)_of, i.e., LT(n+1) = D(n+1) + D(n+1)_of = 40t + 40t = 80t. Correspondingly, the duty cycle Duty(n+1) = D(n+1) / LT(n+1) * 100% = 40t / 80t * 100% = 50%, thus ensuring that the duty cycle Duty(n+1) of the second period LT(n+1) in the backlight driving signal LEDDriver corresponding to the target frame is equal to the target duty cycle Duty_tar.

[0086] When the target frame is the (n+2)th frame, the second period LT(n+2) is the sum of the first duration D(n+2) and the duration D(n+2)_of, i.e., LT(n+2) = D(n+2) + D(n+2)_of = 50t + 50t = 100t. Correspondingly, the duty cycle Duty(n+2) = D(n+2) / LT(n+2) * 100% = 50t / 100t * 100% = 50%, thus ensuring that the duty cycle Duty(n+2) of the second period LT(n+2) in the backlight driver signal LED Driver corresponding to the target frame is equal to the target duty cycle Duty_tar.

[0087] When the target frame is the (n+3)th frame, the second period LT(n+3) is the sum of the first duration D(n+3) and the duration D(n+3)_of, i.e., LT(n+3) = D(n+3) + D(n+3)_of = 40t + 40t = 80t. Correspondingly, the duty cycle Duty(n+3) = D(n+3) / LT(n+3) * 100% = 40t / 80t * 100% = 50%, thus ensuring that the duty cycle Duty(n+3) of the second period LT(n+3) in the backlight driving signal LED Driver corresponding to the target frame is equal to the target duty cycle Duty_tar.

[0088] When the target frame is the nth frame Frame(n), the second period LT(n) in the backlight driving signal LED Driver corresponding to the target frame is the sum of the first duration D(n) and the duration D(n)_of.

[0089] like Figures 3A-3B Within the periods LT(n+1), LT(n+2), and LT(n+3) of the refresh rate change of the display panel, the average duty cycle Duty_ave can be obtained, which is also the target duty cycle Duty_tar. Wherein, Duty_ave = (D(n+1) + D(n+2) + D(n+3)) / (LT(n+1) + LT(n+2) + LT(n+3)) * 100% = (40t + 50t + 40t) / (80t + 100t + 80t) * 100% = 130t / 260t * 100% = 50%.

[0090] Therefore, the backlight driving method can redistribute the driving cycle of the backlight driving signal LED Driver by delaying the start time of the first effective pulse phase according to the second duration, so that the duty cycle of the corresponding periods LT(n+1), LT(n+2), and LT(n+3) is kept equal to the target duty cycle Duty_tar within the periods LT(n+1), LT(n+2), and LT(n+3), thereby improving the problem of backlight flickering during refresh frequency changes.

[0091] Understandably, the backlight brightness will vary depending on the grayscale of the displayed image. Therefore, the backlight driving method described above can be used to drive the backlight source during these grayscale changes to improve the display effect.

[0092] Figure 4 This is a schematic diagram of the structure of a display device provided in an embodiment of the present invention. The present invention also provides a display device, including a display panel 401, a plurality of backlights 402, and a control module 403.

[0093] Optionally, the display panel 401 may include a passive light-emitting display panel (such as a liquid crystal display panel, etc.).

[0094] Multiple backlights 402 are configured to provide backlighting to the display panel. Optionally, the backlight 402 includes light-emitting diodes (LEDs). Optionally, the LEDs include sub-millimeter LEDs, micro LEDs, organic light-emitting diodes, etc.

[0095] The control module 403 is configured to drive a plurality of backlight sources 402 according to the backlight driving method to provide backlight for the display panel 401.

[0096] Optionally, the control module 403 includes a controller and a backlight driver chip.

[0097] The controller is configured to determine the target duty cycle (Duty_tar), the second duration, and the first duration to generate a control signal.

[0098] Optionally, the controller may include a main control chip, a timing controller, a memory, etc. Optionally, the memory may include non-volatile memory, etc.

[0099] The backlight driver chip is configured to generate the backlight driver signal LEDDriver according to the control signal, so that the start time of the first effective pulse phase corresponding to the target frame in the backlight driver signal LEDDriver can be delayed according to the second duration, thereby improving the problem of backlight flickering during refresh rate changes when multiple backlights 402 are used to provide backlight to the display panel 401.

[0100] Understandably, the display device includes portable display devices (such as laptops, mobile phones, etc.), fixed terminals (such as desktop computers, televisions, etc.), measuring devices (such as fitness trackers, thermometers, etc.), etc.

[0101] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A backlight driving method, characterized in that, include: Based on the target duty cycle and the first period corresponding to the target previous frame, the first duration of the first effective pulse phase in the backlight driving signal corresponding to the target frame of the image to be displayed on the display panel is determined; wherein, the target previous frame is a frame located before the target frame, and the backlight driving signal is used to drive the backlight of the display panel. A second duration is determined based on the maximum period corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period, so as to postpone the start time of the first effective pulse phase according to the second duration; The step of determining the second duration based on the maximum period corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period, and then delaying the start time of the first effective pulse phase according to the second duration, includes: The second duration is determined based on the difference between the maximum period and the first period, so as to postpone the start time of the first effective pulse phase based on the second duration.

2. The backlight driving method according to claim 1, characterized in that, The step of determining the first duration of the first effective pulse phase in the backlight driving signal corresponding to the target frame of the image to be displayed on the display panel, based on the target duty cycle and the first period corresponding to the previous frame of the target, includes: The first duration is determined by multiplying the target duty cycle by the first period.

3. The backlight driving method according to claim 1, characterized in that, Before the step of determining the first duration of the first effective pulse phase in the backlight driving signal corresponding to the target frame of the image to be displayed on the display panel based on the target duty cycle and the first period corresponding to the target previous frame, the following steps are included: The first period corresponding to the previous frame of the target in the field synchronization signal is determined based on the start time of the second effective pulse phase in the field synchronization signal corresponding to the target frame.

4. The backlight driving method according to claim 3, characterized in that, The time difference between the start time of the first effective pulse phase and the end time of the second effective pulse phase is equal to the second duration.

5. The backlight driving method according to claim 1, characterized in that, After the step of determining a second duration based on the maximum period corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period, to postpone the start time of the first effective pulse phase according to the second duration, the method includes: Based on the refresh rate of the display panel, determine the third duration corresponding to the first invalid phase in the backlight driving signal that corresponds to the target frame and is located before the first valid pulse phase; Based on the third duration, the first duration, and the target duty cycle, the fourth duration corresponding to the second invalid phase in the backlight driving signal that corresponds to the target frame and is located after the first valid pulse phase is determined.

6. The backlight driving method according to claim 5, characterized in that, The step of determining the third duration corresponding to the first invalid phase in the backlight driving signal that corresponds to the target frame and is located before the first valid pulse phase, based on the refresh rate of the display panel, includes: The third duration is determined based on the difference between the maximum period and the minimum period corresponding to the frame displayed on the display panel at the highest refresh rate.

7. The backlight driving method according to claim 5, characterized in that, The step of determining the fourth duration corresponding to the second invalid phase in the backlight driving signal that corresponds to the target frame and is located after the first valid pulse phase, based on the third duration, the first duration, and the target duty cycle, includes: The fourth duration is determined by subtracting the ratio of the first duration to the target duty cycle from the sum of the third duration and the first duration.

8. The backlight driving method according to claim 1, characterized in that, After the step of determining a second duration based on the maximum period corresponding to the frame displayed on the display panel at the lowest refresh rate and the first period, to postpone the start time of the first effective pulse phase according to the second duration, the method includes: The duration of the invalid phase in the backlight driving signal that corresponds to the target frame and is located after the first effective pulse phase is determined by subtracting the ratio of the first duration to the target duty cycle from the first duration.

9. A display device, characterized in that, include: Display panel; Multiple backlights are configured to provide backlighting to the display panel; as well as The control module is configured to drive a plurality of the backlight sources according to any one of claims 1 to 8.

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