WO2019056647A1 - 背光源驱动方法和装置 - Google Patents

背光源驱动方法和装置 Download PDF

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Publication number
WO2019056647A1
WO2019056647A1 PCT/CN2017/119917 CN2017119917W WO2019056647A1 WO 2019056647 A1 WO2019056647 A1 WO 2019056647A1 CN 2017119917 W CN2017119917 W CN 2017119917W WO 2019056647 A1 WO2019056647 A1 WO 2019056647A1
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Prior art keywords
control signal
pwm control
backlight
current amplitude
partition
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PCT/CN2017/119917
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English (en)
French (fr)
Inventor
张玉欣
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青岛海信电器股份有限公司
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Publication of WO2019056647A1 publication Critical patent/WO2019056647A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2077—Display of intermediate tones by a combination of two or more gradation control methods
    • G09G3/2081—Display of intermediate tones by a combination of two or more gradation control methods with combination of amplitude modulation and time modulation
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/04—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions
    • G09G3/16—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions by control of light from an independent source
    • G09G3/18—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions by control of light from an independent source using liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133601—Illuminating devices for spatial active dimming
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0264—Details of driving circuits
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/0633—Adjustment of display parameters for control of overall brightness by amplitude modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/064—Adjustment of display parameters for control of overall brightness by time modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/0646—Modulation of illumination source brightness and image signal correlated to each other
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/066—Adjustment of display parameters for control of contrast
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/16—Calculation or use of calculated indices related to luminance levels in display data

Definitions

  • the present application relates to the field of display technologies, and in particular, to a backlight driving method and apparatus.
  • HDR video images have become mainstream in the industry.
  • HDR video images have higher latitude and wider brightness range, especially in high light ratio conditions. Details, so compared to normal video, HDR video has a better picture layering and depth of field, more realistic display of the shooting scene.
  • an embodiment of the present application provides a backlight driving method, where the method includes:
  • PWM Pulse Width Modulation
  • the backlight illumination is driven according to the generated PWM control signal.
  • an embodiment of the present application provides a backlight driving method, including: determining, according to a maximum brightness parameter value of a pixel of each image partition in an input image frame, for controlling corresponding to each image partition. a pulse width modulation PWM control signal current amplitude of the backlight partition, wherein the image partition has a one-to-one correspondence with the backlight partition;
  • the backlight illumination of each backlight partition is driven according to the PWM control signals of the backlight partitions.
  • an embodiment of the present application provides a liquid crystal display terminal, where the terminal includes a backlight, a display panel, a memory, and at least one processor; the memory stores preset computer program code, and the processor is used by the processor. Reading a predetermined computer program code in the memory to perform:
  • the backlight illumination is driven according to the generated PWM control signal.
  • FIG. 1 is a flowchart of a backlight driving method provided by some embodiments of the present application.
  • FIG. 2 is a flow chart of another backlight driving method provided by some embodiments of the present application.
  • FIG. 3 is a schematic diagram of a PWM control signal generation process according to some embodiments of the present application.
  • FIG. 5 is a schematic diagram of another PWM control signal generation process provided by some embodiments of the present application.
  • FIG. 6 is a flow chart of another backlight driving method provided by some embodiments of the present application.
  • FIG. 7 is a schematic diagram of another PWM control signal generation process provided by some embodiments of the present application.
  • FIG. 8 is a flowchart of another backlight driving method provided by some embodiments of the present application.
  • 9A is a schematic diagram of a first backlight region division manner according to some embodiments of the present application.
  • 9B is a schematic diagram of a second backlight area division manner according to some embodiments of the present application.
  • FIG. 10 is a schematic structural diagram of a backlight driving device provided by some implementations of the present application.
  • FIG. 11 is a schematic structural diagram of another backlight driving device provided by some implementations of the present application.
  • FIG. 12 is a schematic structural diagram of another backlight driving device according to some implementations of the present application.
  • FIG. 13 is a schematic structural diagram of another backlight driving device according to some implementations of the present application.
  • FIG. 14 is a schematic structural diagram of another backlight driving device provided by some implementations of the present application.
  • FIG. 15 is a structural diagram of a liquid crystal display terminal according to some embodiments of the present application.
  • a backlight brightness control device disposed in a liquid crystal display device (such as a liquid crystal television, a liquid crystal display, or a tablet computer, etc.), which can be implemented by software and/or hardware.
  • the application adopts the PWM technology to control the backlight illumination, that is, by controlling the time when the backlight is turned on and off, switching between the on state of 100% brightness and the off state of 0% brightness on the basis of the backlight current, the PWM passes Controls each of the backlights to operate in their on state for a number of repetition periods.
  • the time period is sufficiently short (for example, 1 millisecond)
  • the human visual system does not detect that the backlight circulates between the on state and the off state, and the observer perceives only the average emitted light intensity, which is in an on state with the backlight.
  • the percentage of the PWM control period is proportional, which is referred to as the duty cycle of the PWM signal.
  • a light emitter driven by a PWM control signal having a 75% duty cycle is turned on at 75% of each PWM period and presents to the viewer as if it is stably emitting light with 75% brightness of its maximum brightness. .
  • determining the current amplitude and duty ratio of the PWM control signal is the key to driving the backlight illumination, and the backlight driving method of the common video in the related art, for example, only a small area in the overall dark picture in the video image
  • the duty cycle of the control signal is determined according to the grayscale mean value, it is obvious that the mean value of the image is very low, and at the same time, the current amplitude of the PWM control signal is preset, which may result in a highlight corresponding portion.
  • the backlight brightness is low, that is, the backlight brightness of a small area highlight scene cannot be improved, thereby affecting the display effect of the video.
  • the backlight driving method proposed in the present application can be directed to HDR video, and the specific steps are as follows.
  • FIG. 1 is a flowchart of a backlight driving method provided by some examples of the present application. As shown in FIG. 1 , the method includes the following steps:
  • Step S11 determining a current amplitude of a PWM control signal for controlling brightness of the backlight according to a maximum brightness parameter value of the pixel in the input image frame;
  • Step S12 generating a PWM control signal for controlling brightness of the backlight according to a current amplitude of the PWM control signal and a predetermined duty ratio of the PWM control signal;
  • Step S13 driving backlight illumination according to the generated PWM control signal.
  • the input image frame may be an HDR image frame.
  • other types of image frames may also be used.
  • the PWM control signal can be output by a chip. Since the output of the chip is a level signal, in some embodiments, the low level of the PWM control signal is 0. Therefore, the current amplitude of the PWM control signal can be understood as being electric. The corresponding value of the flat signal is high level. In some embodiments, the low level of the PWM control signal may not be 0, and the current amplitude of the PWM control signal refers to a high level state in the generated PWM control signal and The difference in amplitude between low states.
  • the method for determining the current amplitude of the PWM control signal for controlling the brightness of the backlight in step S11 may be determined according to a maximum brightness parameter value of the pixel in the image frame; or may be according to the image The maximum luminance parameter value of the pixel in the frame, and the pixel grayscale value of the image frame are determined.
  • the duty ratio of the predetermined PWM control signal in step S12 may be determined according to a pixel grayscale value of the image frame; or may be based on a pixel grayscale value of the image frame and The current amplitude of the PWM control signal is determined; or, it may be a preset fixed value.
  • the driving the backlight according to the PWM control signal may be specifically implemented by:
  • the PWM control When the backlight is driven to emit light by the PWM control signal, if the operating current value of the backlight is located between a rated current value and a maximum current value of the backlight exceeding a threshold, the PWM control is performed. The current amplitude of the signal is adjusted to a current amplitude corresponding to the rated current value of the backlight.
  • the current amplitude of the PWM control signal is determined according to the maximum brightness parameter value of the pixel in the input image frame, so that the PWM driving signal controls the backlight brightness peak of the backlight to match the maximum brightness of the pixel of the image frame, Solving the related backlight driving method can not improve the backlight brightness of small-area high-brightness images, and further improve the image quality.
  • the HDR video image is taken as an example, that is, the input image frame is an HDR image frame.
  • the backlight driving method provided by the embodiment of the present application is not limited to the HDR video image, and Backlight drive control for other types of video images.
  • FIG. 2 is a flowchart of a backlight driving method provided by some examples of the present application. As shown in FIG. 2, the method includes the following steps:
  • Step S101 When receiving the HDR image frame, determine a current amplitude of the PWM control signal for controlling the brightness of the backlight according to the maximum brightness parameter value of the pixel in the HDR image frame.
  • the backlight driving method provided by some embodiments of the present application may be directed to HDR video.
  • the mainstream standards of HDR video include HDR10, Dolby Vision, Technicolor/Philips HDR, BBC HDR, etc.
  • movie and streaming operators mostly support Dolby Vision and HDR10.
  • TV stations represented by BBC and NHK choose Technicolor/Philips HDR and BBC HDR.
  • the metadata In the HDR video production process, metadata for recording the production information is generated, and the metadata and the image data are transmitted as a whole, wherein the metadata generally includes a Maximum Content Light Level (MaxCLL) and a maximum frame average brightness (Maximum Frame- Average light level, MaxFALL), the image data includes the image content of each pixel, and the embodiment of the present application determines the current amplitude of the PWM control signal by using the maximum brightness of the content in the HDR image frame metadata (ie, the maximum brightness parameter value of the pixel). .
  • MaxCLL Maximum Content Light Level
  • MaxFALL Maximum Frame- Average light level
  • the HDR video signal is parsed to obtain encoded data of each frame of the HDR image, the encoded data includes image data and metadata, and the metadata includes a maximum brightness parameter value of the pixel of the HDR image frame, thereby obtaining the HDR image.
  • the pixel grayscale value and maximum luminance value of the frame are examples of the HDR video signal.
  • the metadata and the image data storage form are not limited in the application, which may be stored in the form of a record table, a record strip, etc., and may be a method in which metadata and video image brightness data are stored separately, and all video images are
  • the metadata storage of the frame is distinguished by a label, and the metadata and image data of each frame of the video image may be stored as a unit in units of video image frames.
  • the maximum brightness parameter value of the pixel records a maximum brightness value of the HDR image frame content, and the first mapping table records a pixel maximum brightness parameter value corresponding to a current amplitude of the PWM control signal.
  • the first mapping table is pre-set according to the image content brightness level and the backlight performance, wherein the maximum brightness parameter value is in one-to-one correspondence with the current amplitude of the PWM control signal.
  • the image content brightness of the HDR video is generally represented by a 10-bit information amount, that is, the brightness level range is [0, 1023], assuming that the PWM control signal current amplitude range of the backlight is [1A, 5A]. ], then [1A, 5A] can be equally divided into 1024 copies or non-uniformly divided into 1024 copies, corresponding to 1024 brightness levels in the range [0, 1023], respectively.
  • the PWM control signal current amplitude is positively correlated with the brightness level, that is, the maximum brightness parameter value corresponds to the maximum current amplitude.
  • the first mapping table is preset in consideration of a component performance index of the backlight, and the current amplitude of the PWM control signal in the table is between a minimum current amplitude and a maximum current amplitude, wherein the minimum current amplitude The value corresponds to the minimum current value of the backlight, and the maximum current amplitude corresponds to the maximum current value of the backlight, that is, the different current amplitudes of the PWM control signals respectively correspond to different current values of the backlight, for example, when the current amplitude of the PWM control signal is set For the minimum current amplitude, the current value of the backlight is the minimum current value.
  • Step S102 determining a duty ratio of the PWM control signal according to a pixel grayscale value of the HDR image frame.
  • the grayscale mean of the HDR image frame may be obtained by counting grayscale values of all pixels of the HDR image frame, and the image may be determined by the pixel maximum brightness parameter value and the frame average brightness in the metadata. Grayscale mean and maximum grayscale value.
  • the duty ratio of the PWM control signal is equal to the ratio of the grayscale mean of the HDR image frame to the maximum grayscale value of the HDR image frame, see equation (1):
  • D represents the duty cycle of the PWM control signal
  • G mean represents the grayscale mean of the HDR image frame
  • G max represents the maximum grayscale value of the HDR image frame
  • the duty cycle takes a value less than one.
  • the improvement can be made on the above formula (1).
  • the weight term can be further optimized, see equation (2):
  • the current amplitudes are matched to generate a PWM control signal to drive the backlight to the target brightness.
  • step S101 and step S102 may be two independent steps, which may be performed separately, without any order, by selecting a suitable PWM control signal current amplitude and duty ratio, which is step S103 backlight driving. The basis of good or bad results.
  • Step S103 driving backlight illumination according to the PWM control signal.
  • the backlight when the backlight is driven to emit light by the PWM control signal, if a working current value of the backlight is located between a rated current value and a maximum current value of the backlight, a threshold value is exceeded, Then, the current amplitude of the PWM control signal is adjusted to a current amplitude corresponding to the rated current value of the backlight, and the purpose thereof is to prevent the backlight from being damaged by operating the current exceeding the rated current value for a long time.
  • the threshold is set to 5 minutes, and if the operating current value of the backlight is located between the rated current value and the maximum current value of the backlight for more than 5 minutes, the current amplitude of the PWM control signal is used. To adjust the current amplitude corresponding to the rated current value of the backlight, the backlight is operated at a rated current value.
  • the current value of the backlight and the current amplitude of the PWM control signal are different concepts.
  • the current value of the backlight is a current value when the backlight is actually working, and the PWM control signal is usually a level signal.
  • the current amplitude of the PWM control signal is a PWM control signal.
  • the corresponding value of high level for example, see the rectangular wave in Figure 3.
  • the corresponding value at the highest point of the rectangular wave is the current amplitude of the PWM control signal; when the low level of the PWM control signal is not 0, PWM
  • the magnitude of the current of the control signal is the difference in amplitude between the high state and the low state in the generated PWM control signal.
  • the embodiment of the present application determines the pixel maximum brightness parameter value of the HDR image frame, and determines the PWM control signal according to the mapping relationship between the pixel maximum brightness parameter value of the HDR image frame and the PWM control signal current amplitude.
  • the control signal uses a fixed current amplitude, and the backlight brightness is greater than the threshold to adjust the current amplitude.
  • the implementation step is simple, and the backlight control efficiency can be improved;
  • the aspect determines the duty ratio of the PWM control signal by the grayscale value of the HDR image frame, and cooperates with the adjustment of the current amplitude of the PWM control signal, thereby solving the problem that the backlight brightness of the small-area highlight scene cannot be improved by the related technology, thereby improving the HDR.
  • the display of the video is simple, and the backlight control efficiency can be improved;
  • FIG. 3 is a schematic diagram of a PWM control signal generation process in some embodiments, which may correspond to the backlight driving method of FIG. 2 described above.
  • the current amplitude of the PWM control signal is determined by the maximum luminance parameter value of the pixel in the HDR video image frame, and the duty ratio is obtained by the gray scale data of the HDR video image frame, and the PWM control signal is obtained.
  • the current amplitude and duty cycle determine the PWM control signal to generate a rectangular wave as shown in Figure 3.
  • the horizontal axis of the waveform represents time t, and the ordinate represents the current amplitude y of the PWM control signal.
  • the amplitude is not The ratio of the time period of 0 to the whole period represents the backlight current duty ratio.
  • the duty ratio of the PWM control signal the backlight brightness can be varied in the range of 0% to 100% of the peak brightness corresponding to the current amplitude y.
  • the present application can break through the fixed current to achieve a fixed backlight brightness peak limit, so that the backlight brightness can match the pixel brightness of the video image, and better adapt to the HDR image characteristics. (For example, the contrast is large), in particular, it can enhance the backlight brightness of a small-area highlight scene and improve the display effect.
  • Some embodiments of the present application also provide a backlight driving method, which is specifically described below.
  • FIG. 4 Another backlight driving method proposed by some embodiments of the present application, the flowchart of the backlight driving method is shown in FIG. 4, and the specific steps of the method are as follows:
  • Step S201 when receiving the HDR image frame, determining a current amplitude of the PWM control signal for controlling the brightness of the backlight according to the maximum brightness parameter value of the pixel in the HDR image frame.
  • step S201 is similar to step S101 described above. Please refer to the above content, and the description is not repeated here.
  • Step S202 determining a duty ratio of the PWM control signal according to a pixel grayscale value of the HDR image frame and a current amplitude of the PWM control signal.
  • an average luminance value of the HDR image frame is determined according to a pixel grayscale value of the HDR image frame, as shown in equation (3):
  • Y represents the luminance value of a single pixel of the image frame
  • U represents the first chrominance signal of a single pixel
  • V represents the second chrominance signal of a single pixel
  • R represents the luminance value of the red sub-pixel in the pixel
  • G represents the luminance value of the green sub-pixel in the pixel
  • B represents the luminance value of the blue sub-pixel in the pixel.
  • the luminance value Y of each pixel in the image frame can be obtained, and then the luminances of all the pixels of the HDR image frame are averaged to obtain the average luminance value of the HDR image frame.
  • the backlight brightness peak of the backlight can be determined, and the duty ratio of the PWM control signal can be obtained according to formula (4):
  • D represents the PWM control signal duty cycle
  • f represents the mapping ratio
  • C represents the average luminance value of the HDR image frame
  • M represents the backlight luminance peak value of the backlight, which can be determined according to the current amplitude of the PWM control signal.
  • the mapping ratio f is a ratio of a backlight luminance range of the backlight and a luminance range of the HDR image, and is usually f ⁇ 1.
  • the average luminance value of the HDR image frame is 5000 nits
  • the current amplitude of the PWM control signal is 1 A
  • the backlight luminance peak of the corresponding backlight is 2000 nits
  • the luminance range of the HDR image is [0, 10000 ]
  • the backlight brightness range of the backlight is [0, 2000]
  • f is equal to 0.2
  • D is equal to 0.5
  • the duty ratio of the PWM control signal is 0.5.
  • Step S203 driving backlight illumination according to the PWM control signal.
  • FIG. 5 a schematic diagram of a PWM control signal generation process corresponding to the backlight driving method in FIG. 4 above may be referred to FIG. 5, and FIG. 5 and FIG. 3 are compared.
  • the difference between the steps of the two backlight driving methods is that the figure
  • the duty ratio of the PWM control signal in 3 is determined only based on the gray scale data of the HDR image frame
  • the duty ratio of the PWM control signal in FIG. 5 is a combination of the current amplitude of the PWM control signal and the HDR image frame. Grayscale data to determine.
  • step S201 is performed before step S202, because when the current amplitude of the PWM control signal changes, the peak backlight brightness of the backlight also changes, and the control signal is calculated on the basis of the factor.
  • the duty ratio enables the duty ratio to adaptively match the current amplitude of the PWM control signal, so that the matching effect between the HDR image brightness and the backlight brightness can be achieved, thereby solving the problem that the related art cannot improve the backlight brightness of the small-area highlight scene.
  • Some embodiments of the present application also provide a backlight driving method, as shown in FIG. 6, the specific steps are as follows:
  • Step S301 when receiving an HDR image frame, determining a current of a PWM control signal for controlling backlight brightness according to a maximum brightness parameter value of a pixel in the HDR image frame and a pixel grayscale value of the HDR image frame. Amplitude.
  • the current amplitude adjustment factor may be determined based on the maximum brightness parameter value of the pixel and the pixel grayscale value.
  • the pixel grayscale value of the HDR image frame may be counted and weighted averaged, and the average grayscale value of the HDR image frame is determined to obtain an average luminance value.
  • step S202 For discussion, for example, refer to formula (3), which will not be described in detail herein.
  • the current amplitude adjustment coefficient is calculated according to the average luminance value of the HDR image frame and the maximum luminance parameter value of the pixel in the HDR image frame, and can be referred to formula (5):
  • h represents a current amplitude adjustment coefficient
  • m 1 , m 2 , m 3 represents an adjustment factor
  • Y mean represents an average luminance value of an HDR image frame
  • Y max represents a maximum luminance parameter value of a pixel in an HDR image frame.
  • the current amplitude of the PWM control signal determined according to the maximum brightness parameter value may be used as the initial current amplitude.
  • the initial current amplitude is adjusted (or corrected) to obtain the adjusted current amplitude, and then the adjusted current amplitude is used as the current amplitude of the PWM control signal, and the backlight is The source is driven for control.
  • the initial current amplitude and the current amplitude adjustment factor are multiplied to obtain the current amplitude of the PWM control signal.
  • the adjusted current amplitude is used as a basis for the subsequent steps, that is, the adjusted current amplitude can be used instead.
  • the magnitude of the current in subsequent steps is used instead.
  • Step S302 driving backlight illumination according to the PWM control signal, wherein a duty ratio of the PWM control signal is fixed.
  • the duty cycle of the PWM control signal can be set to one.
  • the process of generating the PWM control signal corresponding to the backlight driving method in FIG. 6 above may refer to FIG. 7.
  • the duty ratio of the PWM control signal is a fixed value, according to the maximum pixel in the HDR image frame.
  • the brightness parameter value and the pixel grayscale value of the HDR image frame are used to determine a current amplitude adjustment coefficient for adjusting the current amplitude of the PWM control signal, such that the control signal drives the backlight to achieve backlight brightness and can be correlated with the pixel brightness of the HDR image frame.
  • Matching which is beneficial to improve the contrast of the displayed image, especially to improve the backlight brightness of small-area highlight scenes.
  • FIG. 8 is a flowchart of another method for driving a backlight according to some examples of the present application. As shown in FIG. 8 , the method can be used for partition backlight control, and specifically includes the following steps:
  • Step S21 determining, according to a maximum brightness parameter value of a pixel of each image partition in the input image frame, a current amplitude of a PWM control signal for controlling a backlight partition corresponding to each image partition, wherein the image partition One-to-one correspondence with the backlight partition.
  • the input image frame may be an HDR image frame, and of course, may be an image frame of other formats, which is not limited by the embodiment of the present application.
  • the backlight area may be divided into a plurality of backlight partitions in advance, and the image frame is divided into image partitions having the same number of the backlight partitions, and each of the backlight partitions respectively corresponds to one image partition.
  • FIG. 9A and 9B illustrate two ways of dividing the backlight region.
  • the backlight region 20 is divided into six strip sub-regions.
  • the backlight region 20 is divided into nine block sub-regions, similarly
  • the above is a uniform partition, and of course, it can also be a non-uniform partition.
  • the manner of partitioning the video image frame and the backlight area is not limited.
  • determining a current amplitude of a PWM control signal for controlling brightness of a backlight partition corresponding to each image partition according to a maximum brightness parameter value of a pixel of each image partition in the input image frame.
  • the backlight driving process can be simplified, and the efficiency of driving the backlight backlight adjustment can be improved.
  • Step S22 Generate PWM control signals of each backlight partition according to the current amplitude of the PWM control signal of each backlight partition and the predetermined duty ratio of the PWM control signals of each backlight partition.
  • the current amplitude can be adjusted as follows:
  • operation S22 is performed based on the adjusted current amplitude. That is, the PWM control signal of each backlight partition is generated according to the adjusted current amplitude of the PWM control signal of each backlight partition and the predetermined duty ratio of the PWM control signal of each backlight partition.
  • the pixel average grayscale value of the image partition corresponding to the backlight partition may be determined by weighted average calculation of the pixel grayscale values of the image partition. After determining the pixel average grayscale value of the image partition, the image partition average luminance value can be obtained.
  • the method for calculating the average brightness value is similar to the method discussed in the above embodiments, and details are not described herein again.
  • the current amplitude adjustment coefficient can be determined, as shown in the following formula:
  • h' represents the current amplitude adjustment coefficient
  • m' 1 , m' 2 , m' 3 represents the adjustment factor
  • Y' mean represents the average brightness value of the image partition
  • Y' max represents the pixel maximum brightness parameter value of the image partition.
  • the current amplitude is adjusted according to the current amplitude adjustment coefficient, and the current amplitude and the current amplitude adjustment coefficient may be multiplied to obtain a brightness for controlling the backlight partition.
  • the current amplitude of the PWM control signal may be adjusted according to the current amplitude adjustment coefficient, and the current amplitude and the current amplitude adjustment coefficient may be multiplied to obtain a brightness for controlling the backlight partition.
  • the predetermined duty cycle of the PWM control signal for controlling the backlight partition corresponding to the image partition may be determined based on the pixel grayscale value of the image partition.
  • the ratio of the grayscale mean of the image partition to the maximum grayscale value of the image partition may be taken as the duty cycle of the PWM control signal used to control the brightness of the backlight partition.
  • the grayscale mean value of the backlight partition 201 is 60, and the maximum grayscale value is 100. Then, by calculating the grayscale mean value and the maximum grayscale value of the backlight partition 201, the PWM control signal corresponding to the backlight partition 201 is obtained.
  • the duty cycle is 0.6.
  • the duty cycle of the PWM control signal of the backlight partition can also be determined by the following formula:
  • D' represents the duty cycle of the PWM control signal of the backlight partition
  • k' 1 , k' 2 is the weight term
  • k' 1 + k' 2 1
  • the PWM control of the backlight partition is obtained by adjusting the weight term
  • the duty cycle of the signal is such that the duty cycle can match the current amplitude of the PWM control signal in step S21 to generate a PWM control signal to drive the backlight of the backlight partition to achieve the target brightness.
  • the predetermined duty cycle of the PWM control signal for controlling the backlight partition may be a pixel grayscale value of the image partition corresponding to the backlight partition and a current amplitude of the PWM control signal of the backlight partition. Determined, the specific process is as follows:
  • Step A determining an average luminance value according to a pixel grayscale value of the image partition corresponding to the backlight partition, and specifically determining the luminance value of each pixel in the image partition by referring to formula (3) above, but in this case, the formula The Y in (3) will represent the luminance value of each pixel in the image partition, and then the luminance of all the pixels in the image partition will be averaged to obtain an average luminance value.
  • Step B determining a backlight brightness peak of the backlight of the backlight partition according to a current amplitude of the PWM control signal of the backlight partition.
  • Step C determining a duty ratio of the PWM control signal of the backlight partition according to the image partition average brightness value and a backlight brightness peak value of the backlight of the backlight partition, which may be specifically determined by the following formula:
  • D' represents the PWM control signal duty cycle
  • f' represents the mapping ratio
  • C' represents the average luminance value of the image partition
  • M' represents the backlight luminance peak of the backlight of the backlight partition.
  • the mapping ratio f' is the ratio of the backlight luminance range of the backlight of the backlight partition to the luminance range of the image partition, and is usually f' ⁇ 1.
  • the predetermined duty cycle of the PWM control signal for controlling the backlight partition is a preset fixed value.
  • the predetermined duty cycle of the PWM control signal for controlling the backlight partition is one.
  • Step S23 driving backlight illumination of each backlight partition according to the PWM control signals of the backlight partitions.
  • the backlight illumination is driven according to the PWM control signal, which can be specifically implemented as follows:
  • the threshold value adjusts a current amplitude of the PWM control signal of the backlight partition to a current amplitude corresponding to a rated current value of the backlight of the backlight partition.
  • a PWM control signal for controlling the backlight partition can be determined, thereby driving the backlight according to a PWM control signal corresponding to the backlight partition.
  • the backlight of the partition glows.
  • the embodiment of the present application provides a backlight driving device corresponding to each method described above, which is specifically as follows, in accordance with the method of the present invention.
  • FIG. 10 is a structural block diagram of a backlight driving apparatus according to some embodiments of the present disclosure, which specifically includes:
  • a memory 91 configured to store preset computer program code
  • At least one processor 92 is configured to read the preset computer program code in the memory 91 to perform:
  • the backlight illumination is driven according to the generated PWM control signal.
  • the input image frame is an HDR image frame.
  • the at least one processor 92 is further configured to read a predetermined computer program code in the memory 91 to perform:
  • the first mapping table records a correspondence between a maximum brightness parameter value and a current amplitude of the PWM control signal.
  • the at least one processor 92 is further used after determining a current magnitude of a pulse width modulated PWM control signal for controlling backlight brightness based on a maximum brightness parameter value of a pixel in the input image frame.
  • the preset computer program code in the memory 91 is read to execute:
  • the current amplitude is adjusted according to the current amplitude adjustment coefficient to obtain an adjusted current amplitude.
  • the at least one processor 92 is further configured to read a preset computer program code in the memory 91 to perform:
  • the predetermined duty cycle of the PWM control signal is determined based on a grayscale value of a pixel in the image frame.
  • the duty cycle of the PWM control signal is determined according to a grayscale value of a pixel in the image frame, the following formula is determined:
  • D represents the duty cycle of the PWM control signal
  • G mean represents the grayscale mean of the image frame
  • Gmax represents the maximum grayscale value of the image frame
  • the duty cycle takes a value less than one.
  • the duty cycle of the PWM control signal is determined based on grayscale values of pixels in the image frame, the following formula is determined:
  • D represents the duty cycle of the PWM control signal
  • k 1 , k 2 are weight terms
  • k 1 + k 2 1.
  • the predetermined duty cycle of the PWM control signal is determined according to a grayscale value of a pixel in the image frame and a current amplitude of the PWM control signal.
  • the predetermined duty cycle of the PWM control signal is a fixed value.
  • the at least one processor 92 is further configured to read a predetermined computer program code in the memory 91 to perform:
  • the PWM control When the backlight is driven to emit light by the PWM control signal, if the operating current value of the backlight is located between a rated current value and a maximum current value of the backlight exceeding a threshold, the PWM control is performed. The current amplitude of the signal is adjusted to a current amplitude corresponding to the rated current value of the backlight.
  • FIG. 11 is a structural block diagram of a backlight driving apparatus according to some embodiments of the present disclosure, which specifically includes:
  • the memory 110 is configured to store preset computer program code
  • the at least one processor 120 is configured to read the preset computer program code in the memory 110 to perform:
  • the backlight illumination of each backlight partition is driven according to the PWM control signals of the backlight partitions.
  • the at least one processor 120 is further configured to read a preset computer program code in the memory 110 to perform: a maximum brightness parameter value and a second mapping according to pixels of each image partition a table, determining a current amplitude of a PWM control signal corresponding to the maximum brightness parameter value of each pixel;
  • the second mapping table records the correspondence between the maximum brightness parameter value and the current amplitude of the PWM control signal.
  • the at least one processor 120 is further configured to read the preset computer program code in the memory 110 to perform:
  • the at least one processor 120 is further configured to read a preset computer program code in the memory 110 to perform:
  • a PWM control signal of each backlight partition is generated according to the adjusted current amplitude of the PWM control signal of each backlight partition and the predetermined duty ratio of the PWM control signal of each backlight partition.
  • the predetermined duty cycle of the PWM control signals of each backlight partition is determined according to pixel grayscale values of image partitions corresponding to respective backlight partitions.
  • the predetermined duty ratio of the PWM control signals of each backlight partition is determined according to a pixel grayscale value of an image partition corresponding to each backlight partition and a current amplitude of a PWM control signal of each backlight partition. of.
  • the predetermined duty cycle of the PWM control signals of each backlight partition is a fixed value.
  • the at least one processor 120 is further configured to read the preset computer program code in the memory 110 to perform:
  • the backlight of each backlight partition is driven by the PWM control signal of each backlight partition, if the operating current value of the backlight of any backlight partition is between the rated current value and the maximum current value of the backlight exceeds a threshold, Then, the current amplitude of the PWM control signal of the backlight partition is adjusted to a current amplitude corresponding to the rated current value of the backlight of the backlight partition.
  • FIG. 12 is a schematic structural diagram of another backlight driving device according to some embodiments of the present application. As shown in FIG. 10, the device includes:
  • the current amplitude determining unit 801 of the PWM control signal is configured to determine a current amplitude of the PWM control signal used to control the brightness of the backlight according to the maximum brightness parameter value of the pixel in the HDR image frame when the HDR image frame is received. ;
  • determining a current amplitude of the PWM control signal corresponding to a maximum brightness parameter value of the HDR image frame content according to a maximum brightness parameter value of a pixel in the HDR image frame and a first mapping table;
  • the maximum brightness parameter value records a maximum brightness parameter value of the HDR image frame content
  • the first mapping table records a maximum brightness parameter value corresponding to a current amplitude value of the PWM control signal.
  • the backlight when the backlight is driven to emit light by the PWM control signal, if a working current value of the backlight is located between a rated current value and a maximum current value of the backlight, a threshold value is exceeded, Then, the current amplitude of the PWM control signal is adjusted to a current amplitude corresponding to the rated current value of the backlight.
  • the duty ratio determining unit 802 of the PWM control signal determines a duty ratio of the PWM control signal according to a pixel grayscale value of the HDR image frame;
  • the backlight driving unit 803 is configured to drive backlight illumination according to the PWM control signal.
  • FIG. 13 is a schematic structural diagram of another backlight driving device according to some embodiments of the present disclosure. As shown in FIG. 13, the device includes:
  • the current amplitude determining unit 901 of the PWM control signal is configured to determine, according to the maximum brightness parameter value of the pixel in the HDR image frame, a current amplitude of the PWM control signal used to control the brightness of the backlight when the HDR image frame is received. ;
  • the duty ratio determining unit 902 of the PWM control signal is configured to determine a duty ratio of the PWM control signal according to a pixel grayscale value of the HDR image frame and a current amplitude of the PWM control signal;
  • the backlight driving unit 903 is configured to drive backlight illumination according to the PWM control signal.
  • FIG. 14 is a schematic structural diagram of another light source driving device provided by some embodiments of the present application. As shown in FIG. 14 , the device includes:
  • the current amplitude determining unit 100 of the PWM control signal is configured to determine, according to the maximum brightness parameter value of the pixel in the HDR image frame and the pixel grayscale value of the HDR image frame, when the HDR image frame is received, a current amplitude of a PWM control signal that controls the brightness of the backlight;
  • the backlight driving unit 200 is configured to drive backlight illumination according to the PWM control signal, wherein a duty ratio of the PWM control signal is fixed.
  • FIG. 15 is a structural diagram of a liquid crystal display terminal according to some embodiments of the present disclosure. As shown in FIG. 15, the terminal includes:
  • the video decoding device m21 is connected to the timing control device m22 and the backlight driving device m23, and the video can obtain gradation data, metadata, and the like of the HDR video image frame through the video decoding device m21.
  • the timing control device m22 is connected to the display panel m24.
  • the output signals of the timing control device can be input to the display panel m24 through the connector to control the synchronous display of the image and the audio, wherein the output signal can include a differential data signal and a line field. Scanning signal, liquid crystal panel digital voltage, liquid crystal panel analog voltage, liquid crystal panel VGH voltage, liquid crystal panel GAMMA voltage, liquid crystal panel VGL voltage, liquid crystal panel VCOM voltage, and auxiliary voltage.
  • the backlight driving device m23 is connected to the backlight m25, and the HDR video screen display effect can be improved by the backlight driving device.
  • the specific steps and functions thereof have been described in detail in the above embodiments, and are not described herein again.
  • the backlight m25 is connected to the display panel m24, and the display panel displays the image by using the backlight to emit light.
  • the backlight may include a direct-lighting type backlight and a side-lighting type backlight.
  • the backlight of the mode provides a plurality of screen format area backlight units, each backlight unit provides a light source for the mapped area thereof, and the side edge type light source type backlight is disposed on a side of the liquid crystal display panel, for example, may be an LED light.
  • the display panel m24 includes a plurality of display areas, each display area is composed of a plurality of display pixels, and each pixel is composed of a red pixel unit R, a green pixel unit G, and a blue pixel unit B, for example, 1080P liquid crystal.
  • the display screen includes 1080*1920 pixels, each pixel includes three pixel units of R, G, and B, and the total is 1080*1920*3 pixel units, and the liquid crystal display can be divided into 20 display areas.
  • the liquid crystal display terminal further includes a memory and at least one processor, wherein the memory stores preset computer program code, and the at least one processor is configured to read a preset computer in the memory.
  • the program code is used to perform the operations in any of the foregoing method embodiments, and details are not described herein again.

Abstract

本申请公开了一种背光源驱动方法和装置，属于显示技术领域。所述方法包括：根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值；根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；根据所述生成的PWM控制信号驱动背光源发光。

Description

背光源驱动方法和装置
本申请要求在2017年9月20日提交中国专利局、申请号为201710854545.2、发明名称为“背光源驱动方法和装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及显示技术领域，特别涉及一种背光源驱动方法和装置。
背景技术
目前，高动态范围(High-Dynamic Range，HDR)视频图像在业界已经成为主流，HDR视频图像具有更高的宽容度、更宽的亮度范围，尤其在高光比条件下也能呈现更多的亮部细节，因此与普通视频相比，HDR视频具有更好的画面层次感及景深，更能逼真展现拍摄场景。
对于亮度范围很大，对比度也很高的图像帧，相关产品中的显示效果仍需要进一步改进。
发明内容
第一方面，本申请实施例提供了一种背光源驱动方法，该方法包括：
根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制(Pulse Width Modulation,PWM)PWM控制信号的电流幅值；
根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；
根据所述生成的PWM控制信号驱动背光源发光。
第二方面，本申请实施例提供了一种背光源驱动方法，该方法包括：根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的脉冲宽度调制PWM控制信号的电流幅值，其中，所述图像分区与所述背光分区一一对应；
根据各背光分区的PWM控制信号的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号；
根据所述各背光分区的PWM控制信号驱动各背光分区的背光源发光。
第三方面，本申请实施例提供了一种液晶显示终端，所述终端包括背光源、显示面板，存储器以及至少一个处理器；所述存储器存储有预设的计算机程序代码，所述处理器用于读取所述存储器中的预设的计算机程序代码，以执行：
根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制PWM控制信号的电流幅值；
根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；
根据所述生成的PWM控制信号驱动背光源发光。
附图说明
为了更清楚地说明本申请实施方式，下面将对实施方式描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请一些实施例提供的一种背光源驱动方法流程图；
图2是本申请一些实施例提供的另一种背光源驱动方法流程图；
图3是本申请一些实施例提供的一种的PWM控制信号生成过程示意图；
图4是本申请一些实施例提供的另一种的背光源驱动方法流程图；
图5是本申请一些实施例提供的另一种的PWM控制信号生成过程示意图；
图6是本申请一些实施例提供的另一种背光源驱动方法流程图；
图7是本申请一些实施例提供的另一种的PWM控制信号生成过程示意图；
图8是本申请一些实施例提供的另一种的背光源驱动方法流程图；
图9A是本申请一些实施例的第一种背光区域划分方式示意图；
图9B是本申请一些实施例的第二种背光区域划分方式示意图；
图10是本申请一些实施提供的一种背光源驱动装置结构示意图；
图11是本申请一些实施提供的另一种背光源驱动装置结构示意图；
图12是本申请一些实施提供的另一种背光源驱动装置结构示意图；
图13是本申请一些实施提供的另一种背光源驱动装置结构示意图；
图14是本申请一些实施提供的另一种背光源驱动装置结构示意图；
图15是本申请一些实施例提供的一种的液晶显示终端结构图。
具体实施方式
为使本申请所属的技术领域中技术人员能够更清楚地理解本申请，下面结合附图，通过具体实施例对本申请实施例中的技术方案作进一步地详细描述，以下实施例的执行主体可以为配置在液晶显示设备(例如液晶电视、液晶显示器或者平板电脑等)中的背光源亮度控制装置，该装置可以通过软件和/或硬件实现。
对于亮度范围很大，对比度也很高的图像帧，就可能存在整体较暗的画面中仅有小面积高亮的场景，例如黑夜里一轮很亮的月亮。对于这类亮度范围较大的视频图像，相关产品中的显示效果仍需要进一步改进。
本申请采用PWM技术控制背光源发光，即通过控制背光源接通和断开的时间，在背光电流基础上实现100％亮度的接通状态与0％亮度的断开状态之间切换，PWM通过控制在若干百分比的重复时间段，使各个背光源在其接通状态下工作。当时间段充分短(例如1毫秒)，人类视觉系统检测不到背光源在接通状态与断开状态之间循环，观察者仅感知到平均发射光强度，其与背光源处于接通状态的PWM控制时间段的百分比成比例，该百分比被称为PWM信号的占空比。例如，由具有75％占空比的PWM控制信号驱动的光发射器在每个PWM时间段的75％被接通，并且呈现给观察者好像稳定地发射具有其最大亮度的75％亮度的光。
因此，确定PWM控制信号的电流幅值和占空比是驱动背光源发光的关键，相关技术中的普通视频的背光驱动方法，示例性的，视频图像中整体较暗的画面中仅有小面积高亮的场景下，由于其控制信号的占空比是根据灰阶均值确定，显然该图像的均值很低，同时，PWM控制信号的电流幅值是预设的，因而可能导致高亮部分对应的背光亮度较低，即无法提升小面积高亮场景的背光亮度，从而影响视频的显示效果。本申请提出的背光源驱动方法可以针对HDR视频，具体步骤如下。
图1为本申请一些实例提供的一种背光源驱动方法流程图，如图1所示，该方法包括以下步骤：
步骤S11：根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值；
步骤S12：根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；
步骤S13：根据所述生成的PWM控制信号驱动背光源发光。
在一些实施例中，上述输入的图像帧可以为HDR图像帧，当然，也可以为其它类型的图像帧，本申请实施例对此不做限定。
上述PWM控制信号可以由一芯片输出，由于芯片输出的为电平信号，在一些实施例中，PWM控制信号的低电平为0，因此上述PWM控制信号的电流幅值，可以理解为是电平信号为高电平时对应的数值，在一些实施例中，PWM控制信号的低电平可以不为0，PWM控制信号的电流幅值是指在生成的PWM控制信号中的高电平状态和低电平状态之间的幅值差值。
在一些实施例中，步骤S11中确定用于控制背光源亮度的PWM控制信号的电流幅值的方法，可以是根据所述图像帧中像素的最大亮度参数值确定；也可以是根据所述图像帧中像素的最大亮度参数值，以及所述图像帧的像素灰阶值确定。
在一些实施例中，步骤S12中预先确定的PWM控制信号的占空比可以是根据所述图像帧的像素灰阶值确定的；或者，可以是根据所述图像帧的像素灰阶值及所述PWM控制信号的电流幅值确定的；或者，可以为一预设的固定值。
在一些实施例中，所述根据所述PWM控制信号驱动所述背光源发光，具体可以通过以下方式实现：
当通过所述PWM控制信号驱动所述背光源发光时，若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过阈值，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值。
本申请实施例，根据输入的图像帧中像素的最大亮度参数值确定PWM控制信号的电流幅值，使得PWM驱动信号控制背光源的背光亮度峰值与所述图像帧的像素最大亮度相匹配，可以解决相关背光驱动方法无法提升小面积高亮图像的背光亮度问题，进一步提高画质效果。
以下结合具体实施例对本申请的方案进行详细说明。在下列实施例中，以HDR视频图像为例进行说明，即输入的图像帧为HDR图像帧，应当理解的是，本申请实施例提供的背光源驱动方法并不限于HDR视频图像，其还可以针对其他类型的视频图像进行背光源驱动控制。
图2是本申请一些实例提供的一种背光源驱动方法流程图，如图2所示，该方法包括以下步骤：
步骤S101：当接收到HDR图像帧时，根据所述HDR图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值。
本申请一些实施例提供的背光源驱动方法可以针对HDR视频，目前HDR视频的主流标准包括HDR10、Dolby Vision、Technicolor/Philips HDR、BBC HDR等，通常电影和流媒体运营商大多支持Dolby Vision与HDR10，而以BBC、NHK为代表的电视台则选择 Technicolor/Philips HDR、BBC HDR。HDR视频制作过程中生成记录其制作信息的元数据，元数据与图像数据作为一个整体进行传输，其中元数据通常包括内容最大亮度(Maximum Content Light Level，MaxCLL)、最大帧平均亮度(Maximum Frame-average Light Level，MaxFALL)等参数，图像数据包括各像素点的图像内容，本申请实施例利用HDR图像帧元数据中的内容最大亮度(即像素最大亮度参数值)确定PWM控制信号的电流幅值。
例如，对HDR视频信号进行解析，得到每一帧HDR图像的编码数据，该编码数据包括图像数据和元数据，元数据中包含该HDR图像帧的像素的最大亮度参数值，从而得到该HDR图像帧的像素灰阶值和最大亮度值。
在一些实施例中，对于元数据与图像数据存储形式本申请不做限定，其可以是以记录表、记录条等形式存储，可以是元数据与视频图像亮度数据分开存储方式，将全部视频图像帧的元数据存储，通过标号进行区分，也可以是以视频图像帧为单位，将每一帧视频图像的元数据和图像数据作为整体进行存储等。
在一些实施例中，根据所述HDR图像帧中像素的最大亮度参数值和第一映射表，确定所述HDR图像帧中像素的最大亮度参数值对应的所述PWM控制信号的电流幅值；其中，所述像素的最大亮度参数值记录所述HDR图像帧内容的最大亮度值，所述第一映射表记录像素最大亮度参数值与所述PWM控制信号的电流幅值对应关系。
在一些实施例中，第一映射表是根据图像内容亮度等级和背光源性能预先设定的，其中，最大亮度参数值与PWM控制信号的电流幅值是一一对应的。
在一些实施例中，HDR视频的图像内容亮度一般用10bit信息量来表示，也就是亮度等级范围是[0,1023]，假设背光源的PWM控制信号电流幅值取值范围是[1A,5A]，那么可以将[1A,5A]平均分成1024份或者是非均匀分成1024份，分别对应于[0,1023]范围内的1024个亮度等级。其中，PWM控制信号电流幅值与亮度等级呈正相关，即最大亮度参数值对应最大的电流幅值，通过查找第一映射表来设定PWM控制信号的电流幅值，可以简化背光源驱动过程，提高驱动背光源背光调整的效率。
在一些实施例中，考虑背光源的元器件性能指标来预设第一映射表，该表中的PWM控制信号的电流幅值位于最小电流幅值和最大电流幅值之间，其中最小电流幅值对应背光源的最小电流值，最大电流幅值对应背光源的最大电流值，即PWM控制信号的不同电流幅值分别对应背光源的不同电流值，例如，当PWM控制信号的电流幅值设置为最小电流幅值时，背光源的电流值为最小电流值。
步骤S102，根据所述HDR图像帧的像素灰阶值，确定所述PWM控制信号的占空比。
在一些实施例中，可以通过统计HDR图像帧的所有像素的灰阶值，求该HDR图像帧 的灰阶均值，也可以通过元数据中的像素最大亮度参数值和帧平均亮度来确定图像的灰阶均值和最大灰阶值。
那么，PWM控制信号的占空比等于HDR图像帧的灰阶均值与HDR图像帧的最大灰阶值的比值，见公式(1)：
Figure PCTCN2017119917-appb-000001
其中，D表示PWM控制信号的占空比，G mean表示HDR图像帧的灰阶均值，G max表示HDR图像帧的最大灰阶值，且占空比取值小于1。
在一些实施例中，可以在上述公式(1)上进行改进，在计算PWM控制信号占空比时，可设置权值项进一步优化，见公式(2)：
Figure PCTCN2017119917-appb-000002
其中，k 1,k 2为权值项，k 1+k 2＝1，通过调节权值项，得到PWM控制信号的占空比，使得该占空比能够与步骤S101中确定的PWM控制信号的电流幅值相匹配，生成PWM控制信号以驱动背光源达到目标亮度。
在一些实施例中，步骤S101与步骤S102可以是两个独立的步骤，两者可以分开进行不分先后，通过选择合适的PWM控制信号的电流幅值和占空比，是步骤S103背光源驱动效果好坏的基础。
步骤S103，根据所述PWM控制信号驱动背光源发光。
在一些实施例中，当通过所述PWM控制信号驱动所述背光源发光时，若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过阈值，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值，其目的是为了防止背光源长时间以超过额定电流值的电流工作而损坏。例如，将阈值设置为5分钟，若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过5分钟，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值，从而使所述背光源以额定电流值工作。
需要说明的是，背光源的电流值和PWM控制信号的电流幅值是不同的概念。其中，背光源的电流值为背光源实际工作时的电流值，而PWM控制信号通常为电平信号，当PWM控制信号的低电平为0时，PWM控制信号的电流幅值为PWM控制信号为高电平时对应的数值，例如可参见图3中矩形波，矩形波的最高点处对应的数值即为PWM控制信号的电流幅值；当PWM控制信号的低电平不为0时，PWM控制信号的电流幅值是指在 生成的PWM控制信号中的高电平状态和低电平状态之间的幅值差值。
本申请实施例当接收到HDR图像帧时，确定HDR图像帧的像素最大亮度参数值，并根据HDR图像帧的像素最大亮度参数值与PWM控制信号电流幅值的映射关系，确定该PWM控制信号的电流幅值，较相关背光驱动方法控制信号采用固定电流幅值，判断背光亮度大于阈值才调整该电流幅值相比，本申请实施例一方面实现步骤简单，可以提高背光控制效率；另一方面通过HDR图像帧的灰阶值确定PWM控制信号的占空比，来配合PWM控制信号电流幅值的调整，能够解决采用相关技术无法提升小面积高亮场景的背光亮度的问题，从而提升HDR视频的显示效果。
图3是一些实施例中的PWM控制信号生成过程示意图，其可以对应上述图2中的背光源驱动方法。如图3所示，PWM控制信号的电流幅值是由HDR视频图像帧中像素的最大亮度参数值决定的，占空比是由HDR视频图像帧的灰阶数据求得的，通过PWM控制信号的电流幅值和占空比确定PWM控制信号，生成如图3所示的矩形波，该波形横坐标代表时间t，纵坐标代表PWM控制信号电流幅值y，每个周期内幅值不为0的时间段占整个周期的比值代表背光电流占空比，通过调节PWM控制信号的占空比，可以实现背光亮度在电流幅值y对应的峰值亮度的0％～100％范围变化。
与相关技术中PWM控制信号采用固定电流幅值相比，本申请可以突破固定电流能达到固定的背光亮度峰值局限性，使得背光源亮度能够匹配视频图像的像素亮度，更好的适应HDR图像特点(例如对比度大)，尤其能够提升小面积高亮场景的背光亮度，提升显示效果。
本申请一些实施例还提出一种背光源驱动方法，具体介绍如下。
本申请一些实施例提出的另一种背光源驱动方法，该背光源驱动方法流程图如图4所示，该方法的具体步骤如下：
步骤S201，当接收到HDR图像帧时，根据所述HDR图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值。
在一些实施例中，步骤S201与上述步骤S101类似，请参考上述内容，这里不再重复说明。
步骤S202，根据所述HDR图像帧的像素灰阶值及所述PWM控制信号的电流幅值，确定所述PWM控制信号的占空比。
在一些实施例中，根据所述HDR图像帧的像素灰阶值确定HDR图像帧的平均亮度值，如公式(3)所示：
Figure PCTCN2017119917-appb-000003
其中，Y表示图像帧单个像素点的亮度值，U表示单个像素点的第一色度信号，V表示单个像素点的第二色度信号，R表示该像素点中红色子像素的亮度值，G表示该像素点中绿色子像素的亮度值，B表示该像素点中蓝色子像素的亮度值。
根据上述公式(3)可以得到图像帧中每个像素点的亮度值Y，然后对HDR图像帧所有像素点的亮度取平均得到HDR图像帧的平均亮度值。而根据PWM控制信号的电流幅值可以确定背光源的背光亮度峰值，根据公式(4)可以求的PWM控制信号的占空比：
Figure PCTCN2017119917-appb-000004
其中，D表示PWM控制信号占空比，f表示映射比例，C表示HDR图像帧的平均亮度值，M表示背光源的背光亮度峰值，其可以根据PWM控制信号的电流幅值来确定。
其中，映射比例f是背光源的背光亮度范围和HDR图像的亮度范围的比值，通常f<1。
在一些实施例中，HDR图像帧的平均亮度值是5000nits，而PWM控制信号的电流幅值是1A，其对应的背光源的背光亮度峰值是2000nits，且HDR图像的亮度范围是[0,10000]，背光源的背光亮度范围是[0,2000]，因此f等于0.2，D等于0.5，即PWM控制信号的占空比是0.5。
步骤S203，根据所述PWM控制信号驱动背光源发光。
在一些实施例中，与上述图4中的背光源驱动方法对应PWM控制信号生成过程示意图可以参考图5，比较图5与图3，两种背光源驱动方法的步骤存在的差别点在于，图3中的PWM控制信号的占空比是仅根据HDR图像帧的灰阶数据来确定，而图5中的PWM控制信号的占空比是综合考虑PWM控制信号的电流幅值和HDR图像帧的灰阶数据来确定的。
在一些实施例中，上述步骤S201在步骤S202之前执行，原因是当PWM控制信号的电流幅值发生改变，其背光源的峰值背光亮度也随之改变，考虑该因素的基础上来计算控制信号的占空比，使占空比能够自适应匹配PWM控制信号的电流幅值，这样可以达到HDR图像亮度与背光亮度的匹配效果，从而解决相关技术无法提升小面积高亮场景的背光亮度的问题。
本申请一些实施例还提供了一种背光源驱动方法，如图6所示，具体步骤如下：
步骤S301，当接收到HDR图像帧时，根据所述HDR图像帧中像素的最大亮度参数 值，以及所述HDR图像帧的像素灰阶值，确定用于控制背光源亮度的PWM控制信号的电流幅值。
在一些实施例中，可以根据所述像素的最大亮度参数值和所述像素灰阶值，确定电流幅值调整系数。
在一些实施例中，可以统计HDR图像帧的像素灰阶值，并对其进行加权平均计算，确定HDR图像帧的平均灰阶值，得到其平均亮度值，具体步骤可参照上述步骤S202部分的论述，例如参照公式(3)，这里不再详细说明。
根据HDR图像帧的平均亮度值以及HDR图像帧中像素的最大亮度参数值，从而计算电流幅值调整系数，可以参照公式(5)：
Figure PCTCN2017119917-appb-000005
其中，h代表电流幅值调整系数，m 1,m 2,m 3代表调节因子，Y mean代表HDR图像帧的平均亮度值，Y max代表HDR图像帧中像素的最大亮度参数值。
在一些实施例中，可以将根据该最大亮度参数值确定的PWM控制信号的电流幅值作为初始电流幅值，具体可参照上述步骤S101和步骤S201，这里不再介绍。然后，根据上述确定的电流幅值调整系数对初始电流幅值进行调整(或修正)，得到调整后的电流幅值，进而将调整后的电流幅值作为PWM控制信号的电流幅值，对背光源进行驱动控制。
在一些实施例中，将初始电流幅值和电流幅值调整系数相乘，可得到PWM控制信号的电流幅值。
在一些实施例中，如果对电流幅值进行了调整，并生成了调整后的电流幅值，则将调整后的电流幅值作为基础进行后续的步骤，即可以用调整后的电流幅值替代后续步骤中的所述电流幅值。
步骤S302，根据所述PWM控制信号驱动背光源发光，其中所述PWM控制信号的占空比固定。
在一些实施例中，所述PWM控制信号的占空比可以设置为1。
在一些实施例中，与上述图6中的背光源驱动方法对应的PWM控制信号的生成过程可以参考图7，在PWM控制信号占空比为固定值情况下，根据HDR图像帧中像素的最大亮度参数值和HDR图像帧的像素灰阶值来确定电流幅值调整系数，用以调整PWM控制信号的电流幅值，使得该控制信号驱动背光源达到背光亮度能够与HDR图像帧的像素亮度相匹配，从而有益于提高显示图像的对比度，尤其能够提升小面积高亮场景的背光亮度。
图8为本申请一些实例提供的另一种背光源驱动方法流程图，如图8所示，该方法可 以用于分区背光控制，具体包括以下步骤：
步骤S21：根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的PWM控制信号的电流幅值，其中，所述图像分区与所述背光分区一一对应。
在一些实施例中，所述输入的图像帧可以为HDR图像帧，当然，也可以为其它格式的图像帧，本申请实施例对此不作限定。
在一些实施例中，可以预先将背光区域划分为多个背光分区，同时将图像帧划分为与所述背光分区个数相同的图像分区，每一背光分区分别对应一个图像分区。
图9A和图9B列举了两种背光区域划分方式，如图9A所示，背光区域20分成6个条形子区域，如图9B所示，背光区域20分成9个块状子区域，类似的，以上是均匀分区，当然也可以非均匀分区，这里对视频图像帧和背光区域分区的方式不做限定。
在一些实施例中，根据所述输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的亮度的PWM控制信号的电流幅值时，具体可以采用如下方式：
根据所述各图像分区的像素的最大亮度参数值和第二映射表，确定与所述各最大亮度参数值对应的PWM控制信号的电流幅值；其中，所述第二映射表记录最大亮度参数值与PWM控制信号的电流幅值对应关系。
通过查找第二映射表来确定与背光分区对应的PWM控制信号的电流幅值，可以简化背光源驱动过程，提高驱动背光源背光调整的效率。
步骤S22：根据各背光分区的PWM控制信号的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号。
在一些实施例中，在根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的PWM控制信号的电流幅值之后，还可以对各电流幅值进行调整，具体如下：
根据与各背光分区对应的图像分区的像素的最大亮度参数值，以及与各背光分区对应的图像分区的像素平均灰阶值，确定各背光分区的PWM控制信号的电流幅值调整系数；
根据所述电流幅值调整系数对所述电流幅值进行调整，得到各背光分区的PWM控制信号的调整后的电流幅值。
若采用上述方法对各背光分区的PWM控制信号的电流幅值进行了调整，则基于调整后的电流幅值执行操作S22。也就是，根据各背光分区的PWM控制信号的调整后的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制 信号。
在一些实施例中，背光分区对应的图像分区的像素平均灰阶值可以是通过对该图像分区的像素灰阶值进行加权平均计算确定。当确定图像分区的像素平均灰阶值后，可以得出该图像分区平均亮度值。计算平均亮度值的方法，与上述实施例中论述的方法类似，在此不再赘述。
根据图像分区的平均亮度值以及图像分区中像素的最大亮度参数值，进而可以确定电流幅值调整系数，具体参见如下公式：
Figure PCTCN2017119917-appb-000006
其中，h’代表电流幅值调整系数，m’ 1,m’ 2,m’ 3代表调节因子，Y’ mean代表图像分区的平均亮度值，Y’ max代表图像分区的像素最大亮度参数值。
在一些实施例中，根据所述电流幅值调整系数对所述电流幅值进行调整，可以是将所述电流幅值和电流幅值调整系数相乘，得到用于控制所述背光分区亮度的PWM控制信号的电流幅值。
在一些实施例中，预先确定的用于控制与图像分区所对应的背光分区的PWM控制信号的占空比可以是根据该图像分区的像素灰阶值确定的。
在一些实施例中，可以将图像分区的灰阶均值与图像分区的最大灰阶值的比值作为用于控制背光分区的亮度的PWM控制信号的占空比。
例如，以图9A为例，背光分区201的灰阶均值是60，最大灰阶值是100，那么通过计算背光分区201的灰阶均值与最大灰阶值，得到背光分区201对应的PWM控制信号的占空比是0.6。
在一些实施例中，还可以通过如下公式确定背光分区的PWM控制信号的占空比：
Figure PCTCN2017119917-appb-000007
其中，D’表示背光分区的PWM控制信号的占空比，k’ 1,k’ 2为权值项，k’ 1+k’ 2＝1，通过调节权值项，得到背光分区的PWM控制信号的占空比，使得该占空比能够与步骤S21中的PWM控制信号的电流幅值相匹配，生成PWM控制信号以驱动背光分区的背光源达到目标亮度。
在一些实施例中，预先确定的用于控制背光分区的PWM控制信号的占空比可以是根据与该背光分区对应的图像分区的像素灰阶值及该背光分区的PWM控制信号的电流幅值确定的，具体过程如下：
步骤A：根据与该背光分区对应的图像分区的像素灰阶值确定平均亮度值，具体可参照上文中的公式(3)确定图像分区中每个像素点的亮度值，但在该情况下公式(3)中的Y将表示图像分区中每个像素点的亮度值，然后对该图像分区中所有像素点的亮度取平均得到平均亮度值。
步骤B：根据该背光分区的PWM控制信号的电流幅值确定该背光分区的背光源的背光亮度峰值。
步骤C：根据所述图像分区平均亮度值以及该背光分区的背光源的背光亮度峰值，确定该背光分区的PWM控制信号的占空比，具体可通过以下公式确定：
Figure PCTCN2017119917-appb-000008
其中，D’表示PWM控制信号占空比，f’表示映射比例，C’表示图像分区的平均亮度值，M’表示背光分区的背光源的背光亮度峰值。
其中，映射比例f’是背光分区的背光源的背光亮度范围和图像分区的亮度范围的比值，通常f’<1。
在一些实施例中，所述预先确定的用于控制背光分区的PWM控制信号的占空比为预设的固定值。
在一些实施例中，所述预先确定的用于控制背光分区的PWM控制信号的占空比为1。
步骤S23：根据所述各背光分区的PWM控制信号驱动各背光分区的背光源发光。
在一些实施例中，根据所述PWM控制信号驱动所述背光源发光，具体可通过如下方式实现：
当通过与各背光分区对应的PWM控制信号驱动各背光分区的背光源发光时，若任一背光分区的背光源的工作电流值位于该背光源的额定电流值和最大电流值之间的时间超过阈值，则将该背光分区的PWM控制信号的电流幅值为调整为与该背光分区的背光源的额定电流值对应的电流幅值。
通过上述方法，可以实现对不同背光分区的独立控制，即对于每一背光分区，均可以确定出用于控制该背光分区的PWM控制信号，从而根据与该背光分区对应的PWM控制信号驱动该背光分区的背光源发光。
基于同于方面构思，与上述各实施例提出的方法对应，本申请实施例提供了与上述各方法对应的背光源驱动装置，具体如下。
图10为本申请一些实施例提供的一种背光源驱动装置的结构框图，具体包括：
存储器91，用于存储预设计算机程序代码；
至少一个处理器92，用于读取所述存储器91中的预设计算机程序代码，以执行：
根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制PWM控制信号的电流幅值；
根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；
根据所述生成的PWM控制信号驱动背光源发光。
其中，在图10中，以一个处理器为例进行说明。
在一些实施例中，所述输入的图像帧为HDR图像帧。
在一些实施例中，所述至少一个处理器92还用于读取所述存储器91中的预设计算机程序代码，以执行：
根据所述图像帧中像素的最大亮度参数值和第一映射表，确定与所述图像帧中像素的最大亮度参数值对应的所述PWM控制信号的电流幅值；
其中，所述第一映射表记录最大亮度参数值与PWM控制信号的电流幅值对应关系。
在一些实施例中，在根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制PWM控制信号的电流幅值之后，所述至少一个处理器92还用于读取所述存储器91中的预设计算机程序代码，以执行：
根据所述图像帧中像素的最大亮度参数值，以及图像帧的像素平均灰阶值，确定所述PWM控制信号的电流幅值调整系数；
根据所述电流幅值调整系数对所述电流幅值进行调整，得到调整后的电流幅值。
所述至少一个处理器92还用于读取所述存储器91中的预设计算机程序代码，以执行：
根据所述PWM控制信号的所述调整后的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号。
在一些实施例中，所述预先确定的所述PWM控制信号的占空比是根据所述图像帧中像素的灰阶值确定的。
在一些实施例中，当根据所述图像帧中像素的灰阶值确定所述PWM控制信号的占空比时，采用如下公式确定：
Figure PCTCN2017119917-appb-000009
其中，D表示PWM控制信号的占空比，G mean表示所述图像帧的灰阶均值，G max表示所述图像帧的最大灰阶值，且所述占空比取值小于1。
在一些实施例中，当根据所述图像帧中像素的灰阶值确定所述PWM控制信号的占空 比时，采用如下公式确定：
Figure PCTCN2017119917-appb-000010
其中，D表示PWM控制信号的占空比，k 1,k 2为权值项，且k 1+k 2＝1。
在一些实施例中，所述预先确定的所述PWM控制信号的占空比是根据所述图像帧中像素的灰阶值及所述PWM控制信号的电流幅值确定的。
在一些实施例中，所述预先确定的所述PWM控制信号的占空比为固定值。
在一些实施例中，所述至少一个处理器92还用于读取所述存储器91中的预设计算机程序代码，以执行：
当通过所述PWM控制信号驱动所述背光源发光时，若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过阈值，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值。
图11为本申请一些实施例提供的一种背光源驱动装置的结构框图，具体包括：
存储器110，用于存储预设计算机程序代码；
至少一个处理器120，用于读取所述存储器110中的预设计算机程序代码，以执行：
根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的脉冲宽度调制PWM控制信号的电流幅值，其中，所述图像分区与所述背光分区一一对应；
根据各背光分区的PWM控制信号的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号；
根据所述各背光分区的PWM控制信号驱动各背光分区的背光源发光。
在一些实施例中，所述至少一个处理器120还用于读取所述存储器110中的预设计算机程序代码，以执行：根据所述各图像分区的像素的最大亮度参数值和第二映射表，确定与所述各像素最大亮度参数值对应的PWM控制信号的电流幅值；
其中，所述第二映射表记录最大亮度参数值与PWM控制信号的电流幅值对应关系。
在一些实施例中，在根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的PWM控制信号的电流幅值之后，所述至少一个处理器120还用于读取所述存储器110中的预设计算机程序代码，以执行：
根据与各背光分区对应的图像分区的像素的最大亮度参数值，以及与各背光分区对应的图像分区的像素平均灰阶值，确定各背光分区的PWM控制信号的电流幅值调整系数；
根据所述电流幅值调整系数对所述电流幅值进行调整，得到各背光分区的PWM控制 信号的调整后的电流幅值；
所述至少一个处理器120还用于读取所述存储器110中的预设计算机程序代码，以执行：
根据各背光分区的PWM控制信号的调整后的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号。
在一些实施例中，所述预先确定的各背光分区的PWM控制信号的占空比是根据与各背光分区对应的图像分区的像素灰阶值确定的。
在一些实施例中，所述预先确定的各背光分区的PWM控制信号的占空比是根据与各背光分区对应的图像分区的像素灰阶值及各背光分区的PWM控制信号的电流幅值确定的。
在一些实施例中，所述预先确定的各背光分区的PWM控制信号的占空比为固定值。
在一些实施例中，所述至少一个处理器120还用于读取所述存储器110中的预设计算机程序代码，以执行：
当通过各背光分区的PWM控制信号驱动各背光分区的背光源发光时，若任一背光分区的背光源的工作电流值位于该背光源的额定电流值和最大电流值之间的时间超过阈值，则将该背光分区的PWM控制信号的电流幅值为调整为与该背光分区的背光源的额定电流值对应的电流幅值。
图12是本申请一些实施例提供的另一种背光源驱动装置结构示意图，如图10所示，该装置包括：
PWM控制信号的电流幅值确定单元801，用于当接收到HDR图像帧时，根据所述HDR图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值；
在一些实施例中，根据所述HDR图像帧中像素的最大亮度参数值和第一映射表，确定所述HDR图像帧内容的最大亮度参数值对应的所述PWM控制信号的电流幅值；其中，所述最大亮度参数值记录所述HDR图像帧内容的最大亮度参数值，所述第一映射表记录最大亮度参数值与PWM控制信号的电流幅值对应关系。
在一些实施例中，当通过所述PWM控制信号驱动所述背光源发光时，若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过阈值，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值。
PWM控制信号的占空比确定单元802，根据所述HDR图像帧的像素灰阶值，确定所述PWM控制信号的占空比；
背光驱动单元803，用于根据所述PWM控制信号驱动背光源发光。
图13是本申请一些实施例提供的另一种背光源驱动装置结构示意图，如图13所示，该装置包括：
PWM控制信号的电流幅值确定单元901，用于当接收到HDR图像帧时，根据所述HDR图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值；
PWM控制信号的占空比确定单元902，用于根据所述HDR图像帧的像素灰阶值及所述PWM控制信号的电流幅值，确定所述PWM控制信号的占空比；
背光驱动单元903，用于根据所述PWM控制信号驱动背光源发光。
图14是本申请一些实施例提供的背另一种光源驱动装置结构示意图，如图14所示，该装置包括：
PWM控制信号的电流幅值确定单元100，用于当接收到HDR图像帧时，根据所述HDR图像帧中像素的最大亮度参数值，以及所述HDR图像帧的像素灰阶值，确定用于控制背光源亮度的PWM控制信号的电流幅值；
背光驱动单元200，用于根据所述PWM控制信号驱动背光源发光，其中所述PWM控制信号的占空比固定。
图15是本申请一些实施例提供的一种液晶显示终端结构图，如图15所示，所述终端包括：
视频解码装置m21，该装置与时序控制装置m22及背光源驱动装置m23相连，视频通过视频解码装置m21可以得到HDR视频图像帧的灰度数据、元数据等。
时序控制装置m22，该装置显示面板m24相连，通过连接器可以将时序控制装置中的各个输出信号输入到显示面板m24，控制图像和音频的同步显示，其中输出信号可以包括差分数据信号、行场扫描信号、液晶面板数字电压、液晶面板模拟电压、液晶面板VGH电压、液晶面板GAMMA电压、液晶面板VGL电压、液晶面板VCOM电压以及辅助电压等。
背光源驱动装置m23与背光源m25相连，通过背光源驱动装置，能够提升HDR视频画面显示效果，其具体步骤和功能在上述实施例中已经详细介绍，这里不再赘述。
背光源m25与显示面板m24相连，显示面板借助背光源发光来显示图像，其中，背光源可以包括直下式入光方式的背光源和侧边式入光方式的背光源，其中，直下式入光方式的背光源提供多个网格式区域背光源单元，每个背光源单元为其映射的区域提供光源，侧边式入光方式的背光源设置在液晶显示面板的侧边上，例如可以为LED灯。
显示面板m24，包括多个显示区域，每个显示区域有多个显示像素点构成，每个像素点又由红色像素单元R、绿色像素单元G、蓝色像素单元B组成，例如，1080P的液晶显 示屏，包括1080*1920个像素点，每个像素点包括R、G、B三个像素单元，共计1080*1920*3个像素单元，可以将液晶显示屏划分为20个显示区域。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的装置和单元的具体工作过程，可以参考前述方法实施方式中的映射过程，在此不再赘述。
在一些实施例中，上述液晶显示终端还包括存储器以及至少一个处理器，所述存储器中存储有预设的计算机程序代码，所述至少一个处理器用于读取所述存储器中的预设的计算机程序代码，以执行上述任一方法实施例中的操作，在此不再赘述。
以上所述仅为本申请的一些实施方式，并不用以限制本申请，凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (20)

  1. 一种背光源驱动方法，其特征在于，所述方法包括：
    根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制PWM控制信号的电流幅值；
    根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；
    根据所述生成的PWM控制信号驱动背光源发光。
  2. 根据权利要求1所述的方法，其特征在于，所述根据所述输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的PWM控制信号的电流幅值，具体包括：
    根据所述图像帧中像素的最大亮度参数值和第一映射表，确定与所述图像帧中像素的最大亮度参数值对应的所述PWM控制信号的电流幅值；
    其中，所述第一映射表记录最大亮度参数值与PWM控制信号的电流幅值对应关系。
  3. 根据权利要求1所述的方法，其特征在于，在根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制PWM控制信号的电流幅值之后，该方法还包括：
    根据所述图像帧中像素的最大亮度参数值，以及图像帧的像素平均灰阶值，确定所述PWM控制信号的电流幅值调整系数；
    根据所述电流幅值调整系数对所述电流幅值进行调整，得到调整后的电流幅值；
    所述根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号包括：
    根据所述PWM控制信号的所述调整后的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号。
  4. 根据权利要求1所述的方法，其特征在于，所述预先确定的所述PWM控制信号的占空比是根据所述图像帧中像素的灰阶值确定的。
  5. 根据权利要求1所述的方法，其特征在于，所述预先确定的所述PWM控制信号的占空比是根据所述图像帧中像素的灰阶值及所述PWM控制信号的电流幅值确定的。
  6. 根据权利要求1所述的方法，其特征在于，所述预先确定的所述PWM控制信号的占空比为固定值。
  7. 根据权利要求1所述的方法，其特征在于，所述根据所述PWM控制信号驱动所述背光源发光，具体包括：
    若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过阈值，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值。
  8. 根据权利要求1-7任一权项所述的方法，其特征在于，所述图像帧为高动态范围HDR图像帧。
  9. 一种背光源驱动方法，其特征在于，所述方法包括：
    根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的脉冲宽度调制PWM控制信号的电流幅值，其中，所述图像分区与所述背光分区一一对应；
    根据各背光分区的PWM控制信号的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号；
    根据所述各背光分区的PWM控制信号驱动各背光分区的背光源发光。
  10. 根据权利要求9所述的方法，其特征在于，所述根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的PWM控制信号的电流幅值，具体包括：
    根据所述各图像分区的像素的最大亮度参数值和第二映射表，确定与所述各像素最大亮度参数值对应的PWM控制信号的电流幅值；
    其中，所述第二映射表记录最大亮度参数值与PWM控制信号的电流幅值对应关系。
  11. 根据权利要求9所述的方法，其特征在于，该方法还包括：在根据输入的图像帧中各图像分区的像素的最大亮度参数值，确定用于控制与所述各图像分区所对应的背光分区的PWM控制信号的电流幅值之后，该方法还包括：
    根据与各背光分区对应的图像分区的像素的最大亮度参数值，以及与各背光分区对应的图像分区的像素平均灰阶值，确定各背光分区的PWM控制信号的电流幅值调整系数；
    根据所述电流幅值调整系数对所述电流幅值进行调整，得到各背光分区的PWM控制信号的调整后的电流幅值；
    所述根据各背光分区的PWM控制信号的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号，包括：
    根据各背光分区的PWM控制信号的调整后的电流幅值和预先确定的各背光分区的PWM控制信号的占空比，生成各背光分区的PWM控制信号。
  12. 根据权利要求9所述的方法，其特征在于，所述预先确定的各背光分区的PWM控制信号的占空比是根据与各背光分区对应的图像分区的像素灰阶值确定的；或者，
    所述预先确定的各背光分区的PWM控制信号的占空比是根据与各背光分区对应的图像分区的像素灰阶值及各背光分区的PWM控制信号的电流幅值确定的；或者，
    所述预先确定的各背光分区的PWM控制信号的占空比为固定值。
  13. 根据权利要求9所述的方法，其特征在于，所述各背光分区的PWM控制信号驱动各背光分区的背光源发光，具体包括：
    当通过各背光分区的PWM控制信号驱动各背光分区的背光源发光时，若任一背光分区的背光源的工作电流值位于该背光源的额定电流值和最大电流值之间的时间超过阈值，则将该背光分区的PWM控制信号的电流幅值为调整为与该背光分区的背光源的额定电流值对应的电流幅值。
  14. 根据权利要求9-13任一权项所述的方法，其特征在于，所述图像帧为高动态范围HDR图像帧。
  15. 一种液晶显示终端，所述终端包括背光源、显示面板，其特征在于，所述终端还包括存储器以及至少一个处理器；所述存储器存储有预设的计算机程序代码，所述处理器用于读取所述存储器中的预设的计算机程序代码，以执行：
    根据输入的图像帧中像素的最大亮度参数值，确定用于控制背光源亮度的脉冲宽度调制PWM控制信号的电流幅值；
    根据所述PWM控制信号的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号；
    根据所述生成的PWM控制信号驱动背光源发光。
  16. 根据权利要求15所述的液晶显示终端，其特征在于，所述至少一个处理器还用于读取所述存储器中的预设的计算机程序代码，以执行：
    根据所述图像帧中像素的最大亮度参数值和第一映射表，确定与所述图像帧中的像素最大亮度参数值对应的所述PWM控制信号的电流幅值；
    其中，所述第一映射表记录像素最大亮度参数值与PWM控制信号的电流幅值对应关系。
  17. 根据权利要求15所述的液晶显示终端，其特征在于，所述至少一个处理器还用于读取所述存储器中的预设的计算机程序代码，以执行：
    根据所述图像帧中像素的最大亮度参数值，以及图像帧的像素平均灰阶值，确定所述PWM控制信号的电流幅值调整系数；
    根据所述电流幅值调整系数对所述电流幅值进行调整，得到调整后的电流幅值；
    所述至少一个处理器还用于读取所述存储器中的预设的计算机程序代码，以执行：
    根据所述PWM控制信号的所述调整后的电流幅值和预先确定的所述PWM控制信号的占空比，生成用于控制背光源亮度的PWM控制信号。
  18. 根据权利要求15所述的液晶显示终端，其特征在于，所述预先确定的所述PWM控制信号的占空比是根据所述图像帧中像素的灰阶值确定的；或者，
    所述预先确定的所述PWM控制信号的占空比是根据所述图像帧中像素的灰阶值及所述PWM控制信号的电流幅值确定的；或者，
    所述预先确定的所述PWM控制信号的占空比为固定值。
  19. 根据权利要求15所述的液晶显示终端，其特征在于，所述至少一个处理器还用于读取所述存储器中的预设的计算机程序代码，以执行：
    若所述背光源的工作电流值位于所述背光源的额定电流值和最大电流值之间的时间超过阈值，则将所述PWM控制信号的电流幅值为调整为与所述背光源的额定电流值对应的电流幅值。
  20. 根据权利要求15-19任一权项所述的液晶显示终端，其特征在于，所述图像帧为高动态范围HDR图像帧。
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