Display device and control method thereof

Abstract

The present application provides a display device and a control method thereof. The control method comprises: obtaining a duty cycle of a backlight control signal used to control a backlight source of the display device; and adjusting a starting time point of a pulse of the backlight control signal according to the duty cycle. The present application can automatically calculate the starting time point of the backlight to be turned on under different duty cycles of the backlight to obtain the best starting time point of the backlight, so that the preset position of the picture is the clearest, and the dynamic blur is reduced under various duty cycles of the backlight. The product functionality is improved without increasing the manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a display device and its control method. Background Technology

[0002] Liquid crystal displays (LCDs) are flat, thin display devices that use backlighting to display images. The liquid crystals require a certain amount of time to switch states. If the backlight is continuously provided, and the continuous image frame contains moving objects, the user will see the liquid crystal switching process, which may result in ghosting or motion blur, affecting the viewing quality. Therefore, improving the motion blur phenomenon in such display devices is one of the current industry research topics. Summary of the Invention

[0003] The purpose of this invention is to provide a display device and its control method, which can effectively improve the dynamic blurring phenomenon of images in the display device.

[0004] To achieve the above objectives, the present invention provides a control method for a display device, the control method comprising: acquiring a duty cycle of a backlight control signal, the backlight control signal being used to control the backlight of the display device; and adjusting the start time of a pulse of the backlight control signal at least according to the duty cycle.

[0005] Preferably, the start time of the pulse falls during the period when the display device updates the upper half of the screen.

[0006] Preferably, the pulse's activation period falls at least partially within the time frame during which the display device updates 1 / 4 to 1 / 2 of the screen.

[0007] Preferably, as the duty cycle increases, the start time of the pulse of the backlight control signal is advanced.

[0008] Preferably, when the duty cycle decreases, the start time of the pulse of the backlight control signal is delayed.

[0009] Preferably, the step "adjusting the start time of the pulse of the backlight control signal at least according to the duty cycle" includes: adjusting the start time of the pulse of the backlight control signal according to the duty cycle, the total number of pixel rows of the display device, the number of pixel rows of the front area of ​​the display device, and the number of pixel rows of the active area of ​​the display device.

[0010] Preferably, the control method further includes: generating a threshold value for the display device, wherein the threshold value = ((Vactive / 4+Vfront) / (Vtotal / 100)); Vactive is the number of pixel rows in the active area of ​​the display device; Vfront is the number of pixel rows in the front area of ​​the display device; and Vtotal is the number of pixel rows in the entire area of ​​the display device.

[0011] Preferably, the start time point = the threshold value – ((Y%*Vtotal-(Vactive / 4)) / (Vtotal / 100)); Y% is the duty cycle.

[0012] Ideally, when the start time is negative, the start time should be updated to 0.

[0013] Preferably, when the start time exceeds the threshold value, the start time is updated to the threshold value.

[0014] Based on the above control method, the present invention also provides a display device, the display device comprising: a backlight; and a controller coupled to the backlight, for acquiring the duty cycle of a backlight control signal, and adjusting the start time of the pulse of the backlight control signal at least according to the duty cycle; wherein the backlight control signal is used to control the backlight.

[0015] Preferably, the start time of the pulse falls during the period when the display device updates the upper half of the screen.

[0016] Preferably, as the duty cycle increases, the start time of the pulse of the backlight control signal will be advanced.

[0017] Preferably, when the duty cycle decreases, the start time of the pulse of the backlight control signal is delayed.

[0018] Preferably, the controller adjusts the start time of the pulse of the backlight control signal based on the duty cycle, the total number of pixel rows in the display device, the number of pixel rows in the front area of ​​the display device, and the number of pixel rows in the active area of ​​the display device.

[0019] Compared with the prior art, the display device and control method provided by the present invention can automatically calculate the start time of backlight activation under different backlight duty cycles to obtain the optimal backlight activation area, making the preset position of the screen clearest, achieving the effect of reducing motion blur under various backlight duty cycles, and improving product functionality without increasing manufacturing costs. Attached Figure Description

[0020] Figure 1 A block diagram of a display system provided in an embodiment of the present invention;

[0021] Figure 2 for Figure 1 A schematic diagram of the screen displayed on the central display panel;

[0022] Figure 3 A schematic diagram of liquid crystal transition superposition of image signals;

[0023] Figure 4 for Figure 1 A flowchart of the control method for the display device;

[0024] Figure 5 for Figure 4 Flowchart of step S404;

[0025] Figure 6 for Figure 1 A signal waveform diagram of a display device with a duty cycle of 10%;

[0026] Figure 7 for Figure 1 Another signal waveform diagram with a duty cycle of 22% for the display device;

[0027] Figure 8 for Figure 1 Another signal waveform diagram with a duty cycle of 49% for the display device. Detailed Implementation

[0028] To provide a further understanding of the purpose, structure, features and functions of the present invention, detailed descriptions are provided below with reference to embodiments.

[0029] Certain terms are used in the specification and claims to refer to specific elements. It will be understood by those skilled in the art that manufacturers may use different names to refer to the same element. This specification and claims do not distinguish elements by differences in name, but rather by differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to".

[0030] Figure 1 This is a block diagram of a display system 1 according to an embodiment of the present invention. The display device 10 in the display system 1 can automatically calculate the backlight activation time under different backlight duty cycles to obtain the optimal backlight activation area, so that the preset position of the image, such as the center of the image, is the clearest. It achieves the effect of reducing motion blur under various backlight duty cycles, realizing automation and diverse brightness adjustment, and improving product functionality without increasing manufacturing costs.

[0031] Display system 1 includes a display device 10 and an input device 12. The display device 10 includes a display panel 102, a backlight 104, and a controller 106. The display panel 102 may be disposed above the backlight 104. In some embodiments, other optical elements, such as light guide plates, diffusers, brightness enhancement films, polarizers, etc., may be disposed between the display panel 102 and the backlight 104. The controller 106 may be coupled to the input device 12, the display panel 102, and the backlight 104.

[0032] The controller 106 can be a microcontroller or other control circuit. The controller 106 can receive image frame signals and synchronization signals from the display card or other image source, and transmit the image frame signal VD to the display panel 102 and the backlight control signal BL to the backlight source 104. The synchronization signal can be a vertical synchronization signal. The display panel 102 can update the image line by line from top to bottom according to the image frame signal VD, and the backlight source 104 can emit light under the control of the backlight control signal BL, illuminating the display panel 102 to display the image. The brightness of the backlight source 104 can be controlled by pulse width modulation, i.e., by the duty cycle of the backlight control signal BL. The user can input or change the duty cycle of the backlight control signal BL via the input device 12. The input device 12 can be implemented by a combination of software, firmware, and hardware, and can be integrated into the display device 10 or separated from the display device 10. In some embodiments, the input device 12 may be a touch screen, keyboard, mouse, button, or other input device. The user can use the input device 12 to select the number of backlight segments or adjust the backlight control slider to adjust the duty cycle of the backlight control signal BL. The duty cycle of the backlight control signal BL may be stored in memory internal or external to the controller 106. The controller 106 can obtain the duty cycle of the backlight control signal BL from its internal or external memory and adjust the start time of the pulse of the backlight control signal BL based at least on the duty cycle to reduce motion blur.

[0033] Figure 2 This is a schematic diagram of screen 20 on display panel 102. Screen 20 may have dimensions W x H, where W is the screen width and H is the screen height. The screen width W and screen height H can be represented in pixels, for example, 1920x1080 means the screen width W is 1920 pixels and the screen height H is 1080 pixels. Screen 20 may be divided into portions A to C, located at the top, middle, and bottom of the screen, respectively. Portion A may be located from the first row to 1 / 4 of the screen, portion B may be located from 1 / 4 to 3 / 4 of the screen, and portion C may be located from 3 / 4 of the screen to the last row. The image frame signal VD may be the frame data of screen 20, sequentially including the data falling in portions A to C.

[0034] Display panel 102 can be a liquid crystal panel with a slow liquid crystal rotation, such as an in-plane-switching panel or a vertical alignment panel. Because the liquid crystal in display panel 102 rotates slowly, all liquid crystals may be rotating when the image 20 is updated, and data from portion C of the previous image 20 may be superimposed onto the current image 20 due to overdrive liquid crystal rotation, causing dynamic blurring of portion C of the previous image 20 and portion A of the current image 20. For example, the overdrive liquid crystal rotation may require 2 milliseconds (ms), the total number of pixel rows in the display device 10 may be 1215, the refresh rate may be 240Hz, and the length of the overdrive liquid crystal rotation may be 583 lines (=0.002 / (240*1215)). -1 Therefore, the last row of part C in the previous frame 20 will be superimposed on part A in the current frame 20. Figure 3This diagram illustrates the liquid crystal overlay of image signals, sequentially including frame data A1 to C1, the vertical front porch (VFP) period, the vertical synchronization (VSYNC) period, the vertical back porch (VBP) period, and frame data A2 to C2. Frame data A1 to C1 can be referred to as effective image frames VA1, and can correspond to the top, center, and bottom of screen 20, respectively. The VFP period, VSYNC period, and VBP period can be referred to as blanking periods VB. Frame data A2 to C2 can be referred to as effective image frames VA2, and can correspond to the top, center, and bottom of screen 20, respectively. Effective image frames VA1 and VA2 can be used to generate two consecutive frames. The thick triangular frame 30 displays the frame data C1 of the effective image frame VA1, which is superimposed on the frame data A2 of VFP, VSYNC, VBP, and the effective image frame VA2. This causes motion blur in portions C and A of the image 20 corresponding to frame data C1 and A2. In some embodiments, portion C corresponding to frame data C1 is more blurred than portion A corresponding to frame data A1. The display device 10 does not illuminate the backlight 104 in portions C and / or A where motion blur occurs, thereby reducing ghosting and enhancing the clarity of the image animation for the user. Since the portion of the image is clearest after the backlight 104 is illuminated, to reduce or avoid motion blur in portions A and C, the controller 106 can adjust the start time of the pulse of the backlight control signal BL so that the backlight 104 is turned on during the upper-middle period when the display panel 102 updates the image 20, for example, when the display panel 102 begins updating frame data B1 and B2, so that portion B of the image 20 is clearest. In some embodiments, the start time of the backlight control signal BL pulse may fall within the time period of the upper half of the screen, and the on-time of the backlight control signal BL pulse may at least partially fall within the time period when the display panel 102 updates 1 / 4 to 1 / 2 of the screen, so that portion B is the clearest. In other embodiments, the start time and on-time of the backlight control signal BL pulse may fall within the time period when the display panel 102 updates 1 / 4 to 1 / 2 of the screen, so that portions A and C have similar levels of blur and portion B is clear.

[0035] Figure 4 This is a flowchart of a control method 400 for a display device 10. Control method 400 includes steps S402 and S404, which cause the controller 106 to adjust the start time of the pulse of the backlight control signal BL. Any reasonable technical modifications or adjustments to the steps are within the scope of this invention. Steps S402 and S404 are described below:

[0036] Step S402: Obtain the duty cycle of the backlight control signal BL;

[0037] Step S404: Adjust the start time of the pulse of the backlight control signal BL at least according to the duty cycle.

[0038] In step 404, when the duty cycle increases, the controller 106 can advance the start time of the backlight control signal BL pulse; when the duty cycle decreases, the controller 106 can delay the start time of the backlight control signal BL pulse. For example, if the duty cycle is 25% and the total number of pixel rows is 1215, the start time of the backlight control signal BL pulse can fall at the time when the display device 10 updates 24.2% of the total number of pixel rows, and the backlight 104 can be turned on when the display panel 102 updates the 294th row (=1215*0.242). If the duty cycle increases to 30%, the start time of the backlight control signal BL pulse can fall at the time when the display device 10 updates 19.2% of the total number of pixel rows, and the backlight 104 can be turned on when the display panel 102 updates the 233rd row (=1215*0.192). If the duty cycle is reduced to 22%, the start time of the pulse of the backlight control signal BL can fall when the display device 10 updates 27% of the total number of pixel rows, and the backlight 104 can be turned on when the display panel 102 updates the 328th row (=1215*0.27). Therefore, when the duty cycle increases from 25% to 30%, the start time of the pulse of the backlight control signal BL can be advanced from the 294th row to the 233rd row; when the duty cycle decreases from 25% to 22%, the start time of the pulse of the backlight control signal BL can be delayed from the 294th row to the 328th row. In some embodiments, the controller 106 can adjust the start time of the pulse of the backlight control signal BL according to the duty cycle, the total number of pixel rows of the display device 10, the number of pixel rows in the front area of ​​the display device 10, and the number of pixel rows in the active area of ​​the display device 10. Specific implementations may be as follows: Figure 5 As shown.

[0039] Figure 5 The flowchart for step S404 of control method 400 includes steps S502 to S514, which are used to generate the start time of the pulse of the backlight control signal BL. Any reasonable technical changes or adjustments to the steps are within the scope of this invention. Steps S502 to S514 are described below:

[0040] Step S502: Generate the threshold value Th of the display device 10;

[0041] Step S504: Adjust the start time Ts of the backlight control signal BL pulse based on the duty cycle Y%, Vtotal, Vfront, and Vactive;

[0042] Step S506: Determine if the start time Ts is less than 0. If yes, continue to step S508; otherwise, skip to...

[0043] Step S510;

[0044] Step S508: Update the start time point Ts to 0; end step S404.

[0045] Step S510: Determine if the start time Ts is greater than the threshold value Th? If yes, continue to step S512; if...

[0046] No, then step S404 ends.

[0047] Step S512: Update the start time point Ts to the threshold value Th; end step S404.

[0048] In step 502, the controller 106 generates the threshold value Th of the display device 10 according to formula (1), as shown below:

[0049] Th = ((Vactive / 4+ Vfront) / ( Vtotal / 100)) Formula (1)

[0050] Where Th is the threshold value;

[0051] Vactive is the number of active area pixel rows of the display device 10;

[0052] Vfront is the number of pixel rows in the front area of ​​the display device 10; and

[0053] Vtotal is the total number of pixel rows in the entire display device 10.

[0054] For example, the number of pixel rows in the active region, Vactive, can be 1080, the number of pixel rows in the front region, Vfront, can be 57, the number of pixel rows in the entire region, Vtotal, can be 1215, and the threshold value Th can be approximately 27 (=1080 / 4+57) / (1215 / 100)).

[0055] In step 504, the controller 106 generates the start time point Ts of the display device 10 according to formula (2), as shown below:

[0056] Ts = Th – ((Y%* Vtotal -(Vactive / 4)) / ( Vtotal / 100)) Formula (2)

[0057] Where Ts is the start time of the pulse of the backlight control signal BL;

[0058] Th is the threshold value;

[0059] Y% represents the duty cycle;

[0060] Vtotal is the total number of pixel rows in the entire display device 10; and

[0061] Vactive is the number of active area pixel rows of the display device 10.

[0062] For example, the threshold value Th can be 27, the duty cycle can be 25%, the number of active region pixel rows Vactive can be 1080, the number of front region pixel rows Vfront can be 57, the number of total region pixel rows Vtotal can be 1215, and the start time Ts of the backlight control signal BL pulse can be 24.2 (=27-((0.25*1215-1080 / 4) / (1215 / 100))). Table 1 shows the duty cycle Y% and the start time Ts of the backlight control signal BL pulse calculated according to formula (2). The start time Ts is expressed as a percentage of the total number of region pixel rows. For example, when the duty cycle Y% is 25%, the start time Ts is the 294th row of the total region pixel rows (=1215*0.242).

[0063] Table 1

[0064] Y(％) Th Ts(%) Updated Ts 65 27 -10.8 0 56 27 -6.8 0 49 27 0 0 40 27 9.2 9.2 30 27 19.2 19.2 25 27 24.2 24.2 22 27 27.2 27 10 27 39.2 27 5 27 44.2 27

[0065] In step 506, if the start time point Ts is less than 0, it means that the pulse of the backlight control signal BL should start from the previous frame 20. Since the pulse of the backlight control signal BL can only start from the current frame 20 at the earliest, if the start time point Ts is less than 0, the controller 106 updates the start time point Ts to 0 (step 508) so that the pulse of the backlight control signal BL starts from the first row of all pixel rows, and step S404 ends. For example, in Table 1, when the duty cycle Y% is 56%, the start time point Ts is less than 0 (-6.8<0), so the controller 106 updates the start time point Ts to 0. If the start time point Ts is greater than 0, it means that the pulse of the backlight control signal BL will be delayed until the start time point Ts.

[0066] In step 510, if the start time point Ts is greater than the threshold value Th, it means that the pulse of the backlight control signal BL should start after the 1 / 4 screen. However, the optimal start time point of the backlight control signal BL pulse falls at the 1 / 4 screen position. Therefore, the controller 106 updates the start time point Ts to the threshold value Th (step 512) so that the pulse of the backlight control signal BL starts at the 1 / 4 screen position. For example, in Table 1, when the duty cycle Y% is 10%, the start time point Ts is greater than the threshold value Th (39.2 < 27). Therefore, the controller 106 updates the start time point Ts to 27. And step S404 ends. If the start time point Ts is less than the threshold value Th, the optimal start time point of the backlight control signal BL pulse falls during the period when the display panel 102 updates the 1 / 4 screen, and step S404 ends. For example, in Table 1, when the duty cycle Y% is 25%, the start time point Ts is less than the threshold value Th (24.2 < 27), so the start time point Ts is maintained at 24.2.

[0067] In some embodiments, the positions of steps S506 and S508 and steps S510 and S512 may be swapped so that the comparison between the start time point Ts and the threshold value Th is performed first, and then the comparison between the start time point Ts and 0 is performed.

[0068] Figure 6 This is a signal waveform diagram of the display device 10 with a duty cycle of 10%, which sequentially includes a blank period VB1, an active image frame VA1, a blank period VB2, and VA2. The active image frame VA1 sequentially includes frame data A1 to C1, and the active image frame VA2 sequentially includes frame data A2 to C2. According to Table 1, when the duty cycle Y% is 10%, the updated start time point Ts is 27%.

[0069] At time t1, the image frame signal VD is disabled, and the blank period VB1 begins. Between times t2 and t3, the controller 106 receives the synchronization signal VSYNC. The period between times t1 and t2 is called the VFP period. The start time Ts is calculated from the end of the pulse of the synchronization signal VSYNC (t3). At time t4, the image frame signal VD is enabled, and the active image frame VA1 begins. The period between times t3 and t4 is called the VBP period. At time t5, the display panel 102 updates to 27% of the total number of pixel rows, and the pulse of the backlight control signal BL begins. At time t6, the display panel 102 updates to 37% of the total number of pixel rows, and the pulse of the backlight control signal BL ends. The period between times t5 and t6 is called the on-time Ton of the backlight control signal BL pulse. At time t7, the frame data B1 ends. At time t8, the active image frame VA1 ends. At time t9, the effective image frame VA2 begins, and at time t10, the pulse of the backlight control signal BL begins again. The period between times t6 and t10 is called the cutoff period Toff of the backlight control signal BL pulse.

[0070] Since the pulse of the backlight control signal BL starts at the 1 / 4 position of the screen and ends before the 1 / 2 position, the blur levels of parts A and C in screen 20 are similar, while part B is clear, thus achieving the effect of reducing motion blur.

[0071] Figure 7 Another signal waveform diagram for display device 10 with a duty cycle of 22%. According to Table 1, when the duty cycle Y% is 22%, the updated start time point Ts is 27%. Display device 10 at... Figure 7 The operation mode from time t1 to t5 and from t7 to t10 and Figure 6 The times t1 to t5 and t7 to t10 are the same, and will not be described again here. At time t6, the display panel 102 updates to 49% of the total number of pixel rows, and the pulse of the backlight control signal BL ends. Since the pulse of the backlight control signal BL starts at the 1 / 4 position and ends at the 1 / 2 position, the blur levels of parts A and C of the image 20 are similar, while part B is clear, thus achieving the effect of reducing motion blur.

[0072] Figure 8 This is another signal waveform diagram for display device 10 with a duty cycle of 49%. According to Table 1, when the duty cycle Y% is 49%, the updated start time point Ts is 0%. Display device 10 at... Figure 8 The operation mode from time t1 to t2 and from t6 to t10 and Figure 6The times t1 to t2 and t6 to t10 are the same and will not be repeated here. At time t3, the display panel 102 begins updating to the first row of all pixel rows, and the pulse of the backlight control signal BL begins. At time t4, the effective image frame VA1 begins. At time t5, the display panel 102 updates to 49% of the total number of pixel rows, and the pulse of the backlight control signal BL ends. The period between t3 and t5 is called the on-time period Ton of the backlight control signal BL pulse. At time t6, the frame data B1 ends. At time t7, the effective image frame VA1 ends. At time t8, the pulse of the backlight control signal BL begins again. The period between t5 and t8 is called the off-time period Toff of the backlight control signal BL pulse. At time t9, the effective image frame VA2 begins.

[0073] Since the pulse of the backlight control signal BL starts at the first row of all pixel rows and ends at the position of 1 / 2 of the screen, parts A and C of the screen 20 are blurred while part B is clear, thus achieving the effect of reducing motion blur.

[0074] Although the optimal backlight activation time in this embodiment is set during the period when the upper half of the screen is being updated, those skilled in this art can also set the backlight activation time during the period when other areas of the screen are being updated, based on the duty cycle of the backlight control signal BL, to make the desired preset position as clear as possible.

[0075] This invention provides a display device and its control method, which can automatically calculate the start time of backlight activation under different backlight duty cycles to obtain the optimal backlight activation area, making the preset position of the image clearest, achieving the effect of reducing motion blur under various backlight duty cycles, and improving product functionality without increasing manufacturing costs.

[0076] The present invention has been described in the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. It must be noted that the disclosed embodiments do not limit the scope of the present invention. Conversely, any modifications and refinements made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. A control method of a display device, characterized by, The control method comprises: acquiring a duty cycle of a backlight control signal, the backlight control signal being used to control a backlight of the display device; and adjusting a starting time point of a pulse of the backlight control signal according to the duty cycle, a total number of pixel rows of the display device, a front number of pixel rows of the display device, and an active number of pixel rows of the display device; wherein the adjusting the starting time point of the pulse of the backlight control signal specifically comprises: generating a threshold value of the display device, the threshold value = ((Vactive / 4+Vfront) / (Vtotal / 100)); and generating the starting time point, the starting time point = the threshold value - ((Y%*Vtotal-(Vactive / 4)) / (Vtotal / 100)); wherein Vactive is the active number of pixel rows of the display device; Vfront is the front number of pixel rows of the display device; Vtotal is the total number of pixel rows of the display device; and Y% is the duty cycle.

2. The control method according to claim 1, characterized by, The starting time point of the pulse falls in a period in which the display device updates an upper half of a picture.

3. The control method according to claim 1, characterized by, An opening period of the pulse at least partially falls in a period in which the display device updates 1 / 4 to 1 / 2 of a picture.

4. The control method according to claim 1, characterized by, When the duty cycle increases, the starting time point of the pulse of the backlight control signal is advanced.

5. The control method according to claim 1, characterized by, When the duty cycle decreases, the starting time point of the pulse of the backlight control signal is delayed.

6. The control method according to claim 1, characterized by, When the starting time point is negative, the starting time point is updated to 0.

7. The control method according to claim 1, wherein When the starting time point exceeds the threshold value, the starting time point is updated to the threshold value.

8. A display device, characterized by comprising: The display device comprises: a backlight; and a controller coupled to the backlight, used to acquire a duty cycle of a backlight control signal, and adjust a starting time point of a pulse of the backlight control signal according to the duty cycle, a total number of pixel rows of the display device, a front number of pixel rows of the display device, and an active number of pixel rows of the display device; wherein the backlight control signal is used to control the backlight; wherein the adjusting the starting time point of the pulse of the backlight control signal specifically comprises: generating a threshold value of the display device, the threshold value = ((Vactive / 4+Vfront) / (Vtotal / 100)); and generating the starting time point, the starting time point = the threshold value - ((Y%*Vtotal-(Vactive / 4)) / (Vtotal / 100)); wherein Vactive is the active number of pixel rows of the display device; Vfront is the front number of pixel rows of the display device; Vtotal is the total number of pixel rows of the display device; and Y% is the duty cycle.

9. The display device of claim 8, wherein, The starting time point of the pulse falls in a period in which the display device updates an upper half of a picture.

10. The display device of claim 8, wherein, When the duty cycle increases, the starting time point of the pulse of the backlight control signal is advanced.

11. The display device of claim 8, wherein, When the duty cycle decreases, the starting time point of the pulse of the backlight control signal is delayed.

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