CN104301642B - LCD display contrast adjustment system and method - Google Patents
LCD display contrast adjustment system and method Download PDFInfo
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- CN104301642B CN104301642B CN201410448441.8A CN201410448441A CN104301642B CN 104301642 B CN104301642 B CN 104301642B CN 201410448441 A CN201410448441 A CN 201410448441A CN 104301642 B CN104301642 B CN 104301642B
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Abstract
The present invention relates to a kind of LCD display contrast adjustment system and method, regulating system includes pwm signal denoising module：The interference being subject to for the pwm signal for removing input in transmission process and spike burr；Pulsewidth gathers and adjustment parameter generation module：It completes the acquisition for the pwm signal positive pulse width that pwm signal denoising module is sent and the conversion of corresponding contrast value is carried out to the width of acquisition, obtain contrast adjustment coefficient；Video acquisition module：Externally input vision signal is gathered, and data synchronization is carried out using local clock；Contrast adjustment module：According to the parameter that pulsewidth acquisition and adjustment parameter generation module input, the video data of video acquisition module input is handled, changes the gray value of video, realizes contrast adjustment function.The present invention adjusts display contrast by PWM all the way, and PWM is sampled using FPGA and video data is handled, realizes contrast adjustment function.
Description
Technical field
The invention belongs to the gradation of image regulative modes in Computer Vision, and in particular to a kind of LCD display comparison
Spend regulating system and method.
Background technology
Contrast refer to light and shade region in piece image it is most bright it is white and most dark it is black between ratio, ratio bigger generation
Table contrast is higher, and ratio is smaller, and to represent contrast lower.Often there is " excessively bright ", " excessively dark " in LCD display displayed image
Special circumstances, at this time image display effect can become very poor.When picture contrast obtains improving, the quality of image will be changed
It is kind, obtain clearer image.So LCD display will carry out setting contrast as needed.
Conventional setting contrast mainly has：It is white to change by adjusting gamma voltage values using adjusting gamma voltages
Field and the brightness of black field achieve the purpose that adjust contrast；Using parallel interface, the bit data of the appropriate digit of parallel transmission are made
For the parameter of contrast adjustment, generally using 8bit；In the contrast adjustment mode of extraordinary display, both the above mode is all
There is the defects of certain.In order to realize modularized design, liquid crystal drive board and signal-processing board are typically all in extraordinary display
Separately design, between the two using plug-in unit hinge, facilitates repair and upgrade, as shown in Figure 1.Due to rgb video signal and control
Signal processed, power supply, low signal for being inserted into reduce signal interference etc., together, total signal wire quantity is these signals
Huge, the pin for causing the hinge plug-in unit of liquid crystal drive board and signal-processing board is also a huge number.In order to reduce
The number of pins of hinge plug-in unit increases effective usable floor area of plank it is necessary to control total number of signals to greatest extent.Contrast
Regulatory function is that an indispensable function, corresponding signal cannot be deleted in plug-in unit in display, so will
Reduce its quantity.Obviously be not suitable for by the way of panel data transmission, by the way of gamma voltages are controlled, although interface
Negligible amounts, but due to voltage to be changed, it is necessary to control gamma chips or power supply chip, hardware complexity will
Can be very big, and cost can also increase.
The content of the invention
For overcome the deficiencies in the prior art, the present invention provides a kind of LCD display contrast adjustment system and method, leads to
It crosses PWM all the way and adjusts display contrast, PWM is sampled using FPGA and video data is handled, realizes contrast adjustment
Function.
The technical scheme is that：A kind of LCD display contrast adjustment system, including pwm signal denoising module：With
In the interference that is subject in transmission process of pwm signal of removal input and spike burr；Pulsewidth gathers and adjustment parameter generation mould
Block：It completes the acquisition for the pwm signal positive pulse width that pwm signal denoising module is sent and phase is carried out to the width of acquisition
The conversion for the contrast value answered obtains contrast adjustment coefficient；Video acquisition module：Externally input vision signal is gathered, and
It is synchronous that data are carried out using local clock；Contrast adjustment module：It is inputted according to pulsewidth acquisition and adjustment parameter generation module
Parameter handles the video data of video acquisition module input, changes the gray value of video, realizes contrast adjustment work(
Energy.
A kind of LCD display contrast adjustment method, includes the following steps：Step 1：Pwm signal denoising module receives outer
The pwm signal of portion's input, and pwm signal is filtered；Step 2：Pulsewidth gathers and adjustment parameter generation module is right first
The processed pwm signal of pwm signal denoising module filtered carries out pulse-width samples, obtains the corresponding Counter Value in high level part
Twidth, then according to obtained value TwidthIt tables look-up, draws contrast adjustment coefficient Gain；Step 3：Beyond video acquisition module
Portion's video data carries out data synchronization using local clock, realizes that asynchronous clock is synchronous with data as input；Step 4：It is right
Than the parameter that degree adjustment module is inputted according to pulsewidth acquisition and adjustment parameter generation module, to the video of video acquisition module input
Data are handled, and change the gray value of video, realize contrast adjustment function.The step 3 is：During using external pixels
Write clock of the clock as asynchronous FIFO, internal clocking as read clock, complete external input vision signal acquisition with it is synchronous.Institute
Stating step 4 is：Contrast adjustment module uses formula：PixelOutput=(PixelInput-PixelMin) * Gain+
PixelMin seeks the pixel of input that treated pixel value, wherein PixelOutput are output pixel after adjusting,
PixelInput be sampling module input original pixels, PixelMin be input a frame video pixel minimum, Gain
For the contrast adjustment coefficient of pulsewidth acquisition and the input of adjustment parameter generation module.The step 1 is：Using high frequency clock pair
High level part is counted, as the value T of counterhLess than the threshold value T of settinghminWhen, it is filtered out, exports low level
Signal；The low level interference generated between the high period of secured transmission of payload data, takes the low electricity judged between two rising edges
The flat duration, if corresponding Counter Value TlLess than threshold value Tlmin, export high level.
The present invention has following good effect：The 1st, contrast adjustment parameter is converted into the PWM ripples of duty ratio corresponding, passed through
PWM wave pulsewidth is sampled, realizes the purpose of contrast adjustment.
2nd, such mode adjust liquid crystal display contrast control interface it is simple, only pwm signal all the way is externally being cut with scissors
Using there is very big advantage in the case of chain interface pin anxiety.
3rd, realization methods of the FPGA compared with MCU, the precision of PWM wave sampling is high, and real-time is good.
4th, the logical resource number of occupancy FPGA is few, and cost of implementation is low.Using FPGA can improve sampled data precision and
The real-time of adjusting, while video processing function and contrast adjustment can be placed on a chips, it can greatly reduce power consumption
It is accumulated with PCB surface.
Description of the drawings
Fig. 1 is specific embodiment of the invention monitor signal part composition frame chart；
Fig. 2 is the comprising modules in the FPGA of specific embodiment of the invention contrast adjustment function；
Fig. 3 is effect after specific embodiment of the invention PWM interference signals and processing；
Fig. 4 is specific embodiment of the invention video acquisition and synchronization process block diagram；
Fig. 5 realizes RTL figures for specific embodiment of the invention contrast adjustment algorithm.
Specific embodiment
Below against attached drawing, by the description of the embodiment, each component that the specific embodiment of the present invention is for example involved
Shape, construction, the mutual alignment and connection relation between each several part, the effect of each several part and operation principle, manufacturing process and
Operate with method etc., is described in further detail, to help those skilled in the art to inventive concept of the invention, technology
Scheme has more complete, accurate and deep understanding.
Invention describes a kind of LCD display contrast adjustment system and methods, and contrast adjustment parameter is converted into
The PWM wave of duty ratio corresponding, then using this PWM wave as the input of FPGA.FPGA generates contrast by sampling PWM wave pulsewidth
Adjustment parameter reuses this parameter and the rgb signal of input is handled, realizes the purpose of contrast adjustment.Such mode tune
It is simple to save the control interface of liquid crystal display contrast, only pwm signal all the way, in the situation of external hinge interface pin anxiety
Lower use has very big advantage；Realization methods of the FPGA compared with MCU, the precision of PWM wave sampling is high, and real-time is good；Occupy FPGA
Logical resource number it is few, cost of implementation is low.
The module composition frame chart of realization of the contrast adjustment mode of the present invention in FPGA, as shown in Figure 2.In FPGA
Mainly include pwm signal denoising module, pulsewidth acquisition and adjustment parameter generation module, video acquisition module and contrast adjustment mould
Block.
The function that the completion of pwm signal denoising module is filtered the pwm signal of input, removes what is be subject in transmission process
Interference and spike burr sample correct pulsewidth for rear stage and are ready, its output is gathered as pulsewidth and adjustment parameter
The input signal of generation module.
Pulsewidth gather and adjustment parameter generation module first to the processed pwm signal of pwm signal denoising module filtered into
Row pulse-width samples obtain the corresponding Counter Value in high level part, the value T that then will be obtainedwidthGood as spoken for reserved, etc in advance looks into
The input of table is looked for, draws contrast adjustment coefficient Gain.The look-up table used is previously according to PWM cycle TperiodValue is set
, it is stored in the ROM of FPGA.Obtained contrast value spends the data input of adjustment module as a comparison.
Pulsewidth gathers and adjustment parameter generation module is respectively completed the acquisition to pwm signal positive pulse width and to adopting
The width of collection carries out the conversion of corresponding contrast value.Contrast adjustment coefficient Gain is obtained after conversion, obtained contrast system
Number spends the data input of adjustment module as a comparison.
By sampling pulsewidths of the PWM than the high level of signal of input, to determine the contrast rating of input.Input
The cycle of PWM wave is fixed, that is, when PWM wave is 100% duty cycle, obtained contrast adjustment coefficient is maximum, on the contrary
It is minimum.The corresponding contrast rating relation of intermediate PWM duty cycle is stored in the ROM, and is obtained by searching for table mode.
Video acquisition module completes the acquisition of external input vision signal and carries out data synchronization using local clock.
Video data after synchronization spends the video input of adjustment module as a comparison.Video acquisition module is using external video data as defeated
Enter, data synchronization is carried out using local clock, realizes that asynchronous clock numeric field data is synchronous.Implementation method is as shown in Figure 4.Using outside
Write clock of the pixel clock as asynchronous FIFO, internal clocking as read clock, complete external input vision signal acquisition and
It is synchronous.Video data after synchronization spends the video input of adjustment module as a comparison.
Contrast adjustment module uses contrast adjustment algorithm, is inputted according to pulsewidth acquisition and adjustment parameter generation module
Parameter handles the video data of video acquisition module input, changes the gray value of video, realizes contrast adjustment work(
Energy.And the data after adjusting are output on LCD and are shown.
Contrast adjustment module uses formula：
PixelOutput=(PixelInput-PixelMin) * Gain+PixelMin, after asking processing to the pixel of input
Pixel value, wherein PixelOutput for adjust after output pixel, PixelInput be sampling module input original pixels,
PixelMin is the pixel minimum of a frame video of input, and Gain is pair that pulsewidth gathers and adjustment parameter generation module inputs
Than degree adjustment factor.The RTL figures of the FPGA of algorithm, as shown in Figure 5.
The present invention is exemplarily described above in conjunction with attached drawing, it is clear that the present invention implements and from aforesaid way
Limitation, for example, this patent description contrast adjustment system be verified on an lcd display, it can also be applied to
His types of display.As long as employ the inventive concept and technical scheme of the present invention progress various unsubstantialities improvement or
It is not improved by the present invention design and technical solution directly apply to other occasions, protection scope of the present invention it
It is interior.
Claims (3)
- A kind of 1. LCD display contrast adjustment method, it is characterised in that：LCD display contrast adjustment system is believed including PWM Number denoising module：The interference being subject to for the pwm signal for removing input in transmission process and spike burr；Pulsewidth is gathered and adjusted Save parameter generation module：Complete the acquisition for the pwm signal positive pulse width that pwm signal denoising module is sent and to acquisition Width carry out the conversion of corresponding contrast value, obtain contrast adjustment coefficient；Video acquisition module：It gathers externally input Vision signal, and data synchronization is carried out using local clock；Contrast adjustment module：According to pulsewidth acquisition and adjustment parameter generation The parameter of module input handles the video data of video acquisition module input, changes the gray value of video, realizes comparison Spend regulatory function；The LCD display contrast adjustment method, includes the following steps：Step 1：Pwm signal denoising module connects It is filtered by externally input pwm signal, and to pwm signal；Step 2：Pulsewidth acquisition and adjustment parameter generation module are first Pulse-width samples are carried out to the processed pwm signal of pwm signal denoising module filtered, obtain the corresponding Counter Value in high level part Then Twidth tables look-up according to obtained value Twidth, draws contrast adjustment coefficient Gain；Step 3：Video acquisition module Using external video data as input, data synchronization is carried out using local clock, realizes that asynchronous clock is synchronous with data；Step 3 For：Using write clock of the external pixels clock as asynchronous FIFO, internal clocking completes external input video letter as clock is read Number acquisition with it is synchronous；Step 4：The parameter that contrast adjustment module is gathered according to pulsewidth and adjustment parameter generation module inputs, The video data of video acquisition module input is handled, changes the gray value of video, realizes contrast adjustment function.
- 2. LCD display contrast adjustment method according to claim 1, it is characterised in that：The step 4 is：Comparison It spends adjustment module and uses formula：PixelOultput=(PixelInpult-PixelMin) * Gain+PixelMinAsk the pixel of input that treated pixel value, output pixel after wherein PixelOutput is adjusted for t, PixelInput For the original pixels of sampling module input, PixelMin is the pixel minimum of a frame video of input, and Gain gathers for pulsewidth And the contrast adjustment coefficient of adjustment parameter generation module input.
- 3. LCD display contrast adjustment method according to claim 1, it is characterised in that：The step 1 is：Using High frequency clock counts high level part, and when the value Th of counter is less than the threshold value Thmin set, it is filtered It removes, exports low level signal；The low level interference generated between the high period of secured transmission of payload data, takes and judges two risings The low level duration between if corresponding Counter Value Tl is less than threshold value Tlmin, exports high level.
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| CN107769756B (en) * | 2017-10-26 | 2022-01-21 | 广州视源电子科技股份有限公司 | Control method and device for narrow pulse filtering, storage equipment and filtering equipment |
| CN108449567B (en) * | 2018-03-23 | 2019-03-19 | 广州市奥威亚电子科技有限公司 | A kind of method and device being used for transmission digital video |
| CN113381898B (en) * | 2021-08-16 | 2021-11-09 | 深圳市聚视智能系统有限公司 | Display module interference removing method and device, computer equipment and storage medium |
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| CN101030362A (en) * | 2005-10-20 | 2007-09-05 | 三星电子株式会社 | Display apparatus and control method thereof |
| CN101202017A (en) * | 2006-12-13 | 2008-06-18 | 恩益禧电子股份有限公司 | Backlight brightness control for liquid crystal display panel |
| CN101414439A (en) * | 2007-10-16 | 2009-04-22 | 索尼株式会社 | Display apparatus, quantity-of-light adjusting method for display apparatus and electronic equipment |
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| CN1126406A (en) * | 1993-11-23 | 1996-07-10 | 德克萨斯仪器股份有限公司 | Brightness and contrast control for a digital pulse-width modulated display system |
| CN1410964A (en) * | 2001-09-28 | 2003-04-16 | 义隆电子股份有限公司 | Pulse Width Modulation Device for Adjusting the Bright Contrast of Liquid Crystal Displays |
| CN1450801A (en) * | 2002-04-05 | 2003-10-22 | 株式会社日立制作所 | Contrast adjusting circuit and video display apparatus using same |
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