CN1828698B - Flat panel display and driving method thereof - Google Patents

Abstract

Wherein, the drive method comprises: comparing the difference of pixel gray value of Mth and the (M-1)th frame video data, accounting the opposite pixel number N(M), then computing to output the luminous duty cycle D and amplitude A of the back light source; when N(M) = 0, displaying static picture and setting D to 1 to avoid picture blinking; or else, displaying dynamic picture and setting D less than 1 to drive the back light with impulse light and show clear picture. This invention can obtain supper display performance.

Description

Flat panel display and driving method thereof

(1) Technical field

The present invention relates to a display device and its driving method, in particular to a flat panel display and its driving method.

(2) Background technology

Due to the advent of the information society, the demand for displays as an information transmission medium is also increasing day by day, so the industry is fully committed to the development of related displays. Among them, the cathode ray tube (Cathode Ray Tube, CRT) display has been monopolizing the display market for many years because of its good display quality and technological maturity. However, in recent years, high-tech products have gradually tended to be thinner and smaller. Therefore, flat-panel displays with superior characteristics such as high image quality, good space utilization efficiency, low power consumption, and no radiation, such as Liquid Crystal Displays (LCDs), have become popular. Gradually replace the cathode ray tube display, and become the mainstream of the current display market.

Both of the above two displays have their advantages and disadvantages. In terms of display quality, the cathode ray tube display uses electron beams and is driven by impulse type (impulse type) to emit light, that is to say, within one frame time (about 16.7ms) , the pixel brightness amplitude of the cathode ray tube display changes with time, so it can have better display quality when displaying dynamic images. However, when a static picture is displayed with pulsed light, the problem of picture flickering is likely to occur, so that the viewer's eyes are prone to feel tired and uncomfortable after watching the static picture for a long time.

In liquid crystal displays, at present, most of them use a hold type to drive light emission. In other words, within each frame time of the liquid crystal display, the luminous amplitude of the backlight is constant. Therefore, when the liquid crystal display displays a static picture, the problem of picture flickering does not occur, which can make the viewer's eyes more comfortable when watching the static picture. However, if the backlight of the liquid crystal display is used to display dynamic pictures, the problem of picture blurring (blurring) will occur due to the characteristics of human vision.

In order to enable the liquid crystal display to have better display quality when displaying dynamic images, the prior art uses a pulsed backlight so that the liquid crystal display can have the same display quality as a cathode ray tube display when displaying dynamic images. However, this approach will cause the liquid crystal display to have the shortcomings of the cathode ray tube display when displaying static images, thus losing its original advantages.

(3) Contents of the invention

The object of the present invention is to solve the above problems and provide a driving method of a flat panel display, which is suitable for the flat panel display to select an appropriate driving method to drive the backlight source according to the picture properties.

Another object of the present invention is to provide a flat panel display that can display both dynamic and static images with better display quality.

The purpose of the present invention is achieved in that a driving method of a flat panel display is suitable for driving a flat panel display with I×J pixels. Wherein, the flat-panel display includes a backlight source, and at least one frame of image data has been stored in the flat-panel display. This driving method is to compare the grayscale difference between the pixels of the Mth frame of image data and the M-1th frame of image data stored in the flat panel display when inputting an Mth frame of image data to the flat panel display, and then Output the pixel image data of the Mth frame. Then count the number N(M) of pixels with a grayscale difference between the Mth frame image data and the M-1th frame image data, and then calculate and output the luminous duty ratio (Duty ratio) D and amplitude A of the backlight , to drive the backlight. Wherein, the brightness output by the backlight is the product of the luminous duty ratio D and the amplitude A, and the brightness of the backlight is a constant.

According to the embodiment of the present invention, the duty ratio D of the light emission of the backlight is, for example, a function D[N(M)] of the number of pixels N(M), and the amplitude A of the backlight is, for example, the number of pixels N(M) ) function A[N(M)].

According to the embodiments of the present invention, the method for counting the number of pixels N(M) includes making

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; J</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>$

Wherein, when the grayscale difference between the (i, j)th pixel of the Mth frame image data and the (i, j)th pixel of the M-1th frame image data is greater than the critical grayscale difference, Z(M )(i,j)=1. Conversely, when the grayscale difference between the (i, j)th pixel of the Mth frame of image data and the (i, j)th pixel of the M-1th frame of image data is less than the critical grayscale difference, Z(M )(i,j)=0. Embodiments of the present invention, for example, determine the critical gray scale difference according to the size of the noise. For example, if the noise is larger, a higher critical gray scale difference can be set to avoid noise affecting the calculation of the present invention. result in undue influence. In an embodiment of driving 8-bit image data, the critical grayscale difference is, for example, 8, and in an embodiment of driving 6-bit image data, the critical grayscale difference is, for example, 2.

According to the embodiments of the present invention, the luminous duty ratio of the backlight source is

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; limit</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Wherein, D _limit is the critical duty ratio (critical duty) of the backlight source, and N _max is the critical number of pixels, wherein when the number of pixels N(M) is greater than the critical number of pixels N _max , that is, the number of pixels N(M) is equal to the critical number of pixels N _max . In one embodiment, the minimum value of the critical duty ratio D _limit is 25%, and the maximum value of the critical pixel number N _max is 0.1×I×J.

According to the embodiment of the present invention, the above-mentioned flat panel display further stores a 1xR array S, and the array S has elements S[1], S[2], S[3], . . . , S[R], The initial values of these elements are, for example, zero. In other words, S[1]=S[2]=...=S[R]=0. After counting the number of pixels N(M), it further includes storing the number of pixels N(M) in the array S, so that the array S=[N(M), N(M-1), N (M-2),...,N(M-(R-1))]. In other words, it is for example storing N(M) in element S[1] of array S, N(M-1) in S[2], ..., N(M-(R-1)) in S[R].

According to the embodiment of the present invention, before calculating and outputting the luminous duty ratio D and the amplitude A of the backlight, an average number of pixels is calculated according to S[1] to S[R], and preferably is to calculate a weighted average number of pixels N'(M). In an example, the weighted average number of pixels N'(M) is, for example,

${\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}$

Wherein, S[r] is an element of the array S, r is 1, 2, ..., R, and a _r is the weighted index of S[r], and in one embodiment, the weighted index a _r ≥ a _{r +1} ≥ 0. In addition, the duty ratio D of the light emission of the backlight is, for example, a function D[N'(M)] of the weighted average number of pixels N'(M), and the amplitude A of the backlight is, for example, the weighted average number of pixels N'(M) ) function A[N′(M)].

According to the embodiments of the present invention, the luminous working ratio of the backlight is, for example,

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; limit</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

In the above formula, D _limit is the critical duty of the backlight source, and N _max is the critical number of pixels. In one embodiment, the minimum value of the critical duty ratio D _limit is 25%, and the maximum value of the critical pixel number N _max is 0.1×I×J.

The invention also proposes a flat panel display, which is mainly composed of a display panel, a backlight source and a data control circuit. Wherein, the backlight is arranged under the display panel, and the data control circuit is connected to the display panel and the backlight, and the data control circuit is mainly composed of a comparison unit, a frame image data storage unit and a light source control unit.

As mentioned above, the comparison unit is used to accept and compare an Mth frame of image data and the M-1th frame of image data, and the frame image data storage unit is connected to the comparison unit for storing the The image data of the Mth frame is output to the comparing unit. In addition, the light source control unit is connected to the backlight for controlling the driving of the backlight.

According to the embodiment of the present invention, the above-mentioned data control circuit further includes a frame image weight filter (frame image weight filter), which is connected to the comparison unit for receiving the comparison result output by the comparison unit and calculating the comparison result weight distribution. In one embodiment, the frame image weighting filter further includes an array, and the array is used to store the comparison result received by the frame image weighting filter.

According to the embodiment of the present invention, the light source control unit is composed of, for example, a backlight duty controller (duty controller) and a backlight amplitude controller (amplitude controller), and the luminous duty ratio of the backlight is controlled by the backlight The duty ratio controller is used to control, while the luminous amplitude of the backlight is controlled by the backlight amplitude controller.

According to the embodiment of the present invention, the flat panel display is a liquid crystal display.

Effect of the present invention:

The flat-panel display and its driving method of the present invention can make the flat-panel display have the advantages of the pulse type backlight and the holding type backlight at the same time, and get rid of the shortcomings of the pulse type backlight and the holding type backlight, and then make the flat-panel display display dynamic pictures Or static picture, can have better display quality.

In order to further illustrate the above purpose, structural features and effects of the present invention, the present invention will be described in detail below in conjunction with the accompanying drawings.

(4) Description of drawings

FIG. 1 is a flow chart showing the steps of the driving method in the first embodiment of the present invention.

FIG. 2A is a schematic diagram of a driving voltage curve of a backlight source when a liquid crystal display according to an embodiment of the present invention displays a static image.

FIG. 2B is a schematic diagram of the driving voltage curve of the backlight source when the liquid crystal display according to an embodiment of the present invention displays dynamic images.

FIG. 3 is a flow chart showing the steps of the driving method according to the second embodiment of the present invention.

FIG. 4 is a schematic circuit block diagram of a liquid crystal display according to an embodiment of the present invention.

Explanation of symbols of main components and steps in the accompanying drawings:

S100: Input the Mth frame image data to the liquid crystal display

S102: Compare the grayscale difference between the pixels of the Mth frame of image data and the M-1th frame of image data

S104: Output the pixels of the Mth frame of image data

S106: Count the number N(M) of pixels with grayscale differences between the Mth frame image data and the M-1th frame image data

S108: Calculate and output the luminous duty ratio D[N(M)] and amplitude A[N(M)] of the backlight source of the liquid crystal display

S300: Store the number of pixels N(M) in the array S, so that the array S=[N(M), N(M-1), N(M-2), ..., N(M- (R-1))]

S302: Calculate the weighted average number of pixels N'(M)

S304: Calculate and output the luminous duty ratio D[N′(M)] and amplitude A[N′(M)] of the backlight source of the liquid crystal display

400: liquid crystal display

410: display panel

420: Backlight

430: data control circuit

432: Comparison unit

434: frame image data storage unit

436: Frame image weight filter

438: Light source control unit

438a: Backlight Duty Ratio Controller

438b: Backlight Amplitude Controller

(5) specific implementation

Hereinafter, embodiments of the flat panel display and its driving method of the present invention will be described in detail according to the accompanying drawings. The present invention first judges that the picture to be displayed by the liquid crystal display is a static or dynamic picture, and then selects a more appropriate driving mode to drive the backlight source according to the judgment result, so as to improve the display quality of the liquid crystal display. The present invention will be illustrated below by way of examples.

The driving method of this embodiment is suitable for driving a flat panel display with I×J pixels, such as a liquid crystal display. Wherein, the liquid crystal display includes a backlight source, and at least one frame of image data has been stored in the liquid crystal display, and FIG. 1 is a flow chart showing the steps of the driving method in the first embodiment of the present invention.

Please refer to Figure 1.

First, step S100 is performed to input an Mth frame of image data to the liquid crystal display.

Next, step S102 is performed to compare the grayscale difference between the pixels of the frame of image data and the M−1th frame of image data stored in the liquid crystal display.

Then, as described in step S104, the pixel image data of the Mth frame of image data is output, so that the liquid crystal display displays the frame of image.

Afterwards, as described in step S106 , the number N(M) of pixels having a grayscale difference between the Mth frame of image data and the M−1th frame of image data is counted. In particular, in order to avoid the statistical results inconsistent with the actual situation in step S106 due to noise interference, this embodiment defines a critical gray scale difference, and this embodiment is to drive 8 bits (bits) Image data is taken as an example to set the minimum value of the critical gray scale difference as 8, but it is not used to limit the critical gray scale difference of the present invention. Those skilled in the art can determine the size of the critical gray scale difference according to the actual situation, and The formula for calculating the number of pixels N(M) is, for example,

$\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; J</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Wherein, when the grayscale difference between the (i, j)th pixel of the Mth frame image data and the (i, j)th pixel of the M-1th frame image data is greater than the above critical grayscale difference, Z (M)(i,j)=1. Conversely, when the grayscale difference between the (i, j)th pixel of the Mth frame of image data and the (i, j)th pixel of the M-1th frame of image data is smaller than the above critical grayscale difference, Z (M)(i,j)=0.

After counting the number N(M) of pixels, then as described in step S108 , calculate and output the luminous duty ratio D and amplitude A of the backlight source of the liquid crystal display to drive the backlight source. In this embodiment, the luminous duty ratio D of the backlight is, for example, a function D[N(M)] of the number of pixels N(M), and the luminous amplitude A of the backlight is, for example, a function of the number of pixels N(M). A[N(M)]. Wherein, the formula for calculating the luminous duty ratio D[N(M)] of the backlight is, for example,

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; limit</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

in

D _limit : the critical duty ratio of the luminescence of the backlight

N _max : the number of critical pixels

It should be noted that since the brightness Y of the light emitted by the backlight of the present invention is a certain value, and the brightness Y of the light is the ratio of the luminous duty D[N(M)] of the backlight to the luminous amplitude A[N(M) of the backlight )], so if the working ratio of the backlight is too small, a larger amplitude A[N(M)] is required to maintain a certain brightness of the light. Considering that the animation quality of a CRT display must be close to that of a CRT display when viewing dynamic images, a reasonable critical duty ratio D _limit of the backlight is set so that D1imit does not approach zero and the amplitude A is approximately infinite. In this embodiment, the minimum value of D _limit is, for example, 25%.

Considering that it is not the difference N=1xJ between the whole picture data and the previous picture data, it is called a dynamic picture, but when a part of the proportion data in the picture is different, the human eyes feel that this is an animation, so a reasonable value is set. The number of grayscale differences Nmax, where the maximum value of _Nmax is, for example, 0.1×I×J, which is 10% of the resolution of the display. Moreover, when the number of pixels N is greater than the critical number of pixels N _max , in this embodiment, for example, the number of pixels N is set to be equal to the critical number of pixels N _max .

It can be known from formula (1) and formula (2) that when the liquid crystal display displays a static picture, there may be a gap between the Mth frame image data input in step S100 and the M-1th frame image data stored in the liquid crystal display The only grayscale difference is the grayscale difference caused by noise. Therefore, the number of pixels N(M) obtained by the formula (1) will be equal to zero, while the duty ratio D[N(M)] of the light emission of the backlight obtained by the formula (2) is 1, as shown in Figure 2A shown. In other words, when the liquid crystal display displays a static picture, the present invention drives the backlight in a hold mode so that the picture does not flicker and is more comfortable for human eyes to watch.

On the other hand, when the liquid crystal display displays a dynamic picture, then it can be obtained from the formula (1) that there is a gray space between the Mth frame image data input in step S100 and the M-1th frame image data stored in the liquid crystal display. Then use the formula (2) to calculate the duty ratio D[N(M)] of the light emission of the backlight. At this time, D[N(M)] is less than 1, as shown in FIG. 2B. It can be seen that, when the liquid crystal display displays a dynamic picture, the present invention drives the backlight source in a pulse mode to make the dynamic picture clearer.

It should be noted that the brightness Y of the light emitted by the backlight is equal to the luminous duty ratio of the backlight multiplied by the luminous amplitude of the backlight, and the brightness Y of the light is constant. That is to say, in FIG. 2B, the product of the luminous duty ratio and the luminous amplitude of the backlight is equal to the product of the luminous duty ratio and the luminous amplitude of the backlight of FIG. 2A, so

Y=D[N(M)]xA[N(M)]=D[N(K)]xA[N(K)]

Where M and K are positive integers, and M is not equal to K.

For example, the luminous duty ratio D[N(M)] shown in FIG. 2A is 1, and the luminous amplitude A[N(M)] is equal to A. Therefore, when the luminous duty ratio D[N(K)] of FIG. 2B When it is 50%, its luminous amplitude A[N(K)] is equal to 2A. Here, those skilled in the art can determine the luminance Y output by the backlight according to the actual situation, which is not limited by the present invention.

Although in the above embodiment, only the Mth frame of image data inputted in step S100 is compared with the M−1th frame of image data stored in the liquid crystal display, it is not intended to limit the present invention. Hereinafter, another embodiment will be used to illustrate the driving method of the present invention.

FIG. 3 is a flow chart showing the steps of the driving method according to the second embodiment of the present invention. In this embodiment, the liquid crystal display is, for example, an array S storing a 1×R, that is, the array S has elements S[1], S[2], S[3], ..., S[R ]. Wherein, the initial values of these elements are, for example, zero. In other words, before the liquid crystal display is driven, S[1]=S[2]=...=S[R]=0.

Please refer to Figure 3.

After performing step S100 to step S106 according to the method described in the first embodiment, then proceed to step S300 to store the counted pixel number N(M) in the array S, and then make S=[N( M), N(M-1), N(M-2), ..., N(M-(R-1))]. In other words, N(M) is for example stored in element S[1], N(M-1) is for example stored in element S[2], ..., N(M-(R-1)) is for example Stored in element S[R].

Afterwards, step S302 is performed to calculate an average number of pixels according to the number of pixels stored in the array S. In an embodiment of the present invention, the method for calculating the average number of pixels is, for example, to perform a weighted average calculation on these pixel numbers to obtain a weighted average number of pixels N'(M), and the calculation formula is, for example,

${\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In formula (3), a _r is the weighted index of the number of pixels in the element S[r]. Moreover, the weighting index a _r is, for example, greater than or equal to a _r+1 . In other words, the closer to the Mth frame in time sequence, the greater the weight it occupies. It is worth mentioning that the present invention does not limit the value of the weighting index a _r , and those skilled in the art can decide by themselves according to the actual situation.

After calculating the weighted average number of pixels N′(M), proceed to step S304 , which is to calculate and output the luminous duty ratio D and amplitude A of the backlight source of the liquid crystal display to drive the backlight source. Wherein, the duty ratio D of the backlight source is, for example, a function D[N'(M)] of the weighted average number of pixels N'(M), and its calculation formula is, for example,

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; limit</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The amplitude A is also a function A[N'(M)] of the weighted average number of pixels N'(M), and it is, for example, equal to the brightness Y of the light emitted by the backlight divided by the duty ratio D[N' of the backlight (M)].

It can be seen from formula (4) that in this embodiment, the formula for calculating the luminous duty ratio D[N'(M)] of the backlight is, for example, similar to the formula (2) of the previous embodiment, and the only difference is that The number of pixels N'(M) in this embodiment is obtained by weighting and averaging multiple numbers of pixels.

Similarly, it can be known from formula (3) and formula (4), that this embodiment can also select an appropriate backlight driving method according to the dynamic picture or the static picture, so as to achieve the same effect as the previous embodiment.

In order to implement the driving methods described in the above two embodiments, the following specific embodiments are used to illustrate the flat panel display of the present invention, but they are not intended to limit the present invention.

FIG. 4 is a schematic circuit block diagram of a flat panel display according to an embodiment of the present invention. Referring to FIG. 4 , the flat panel display is, for example, a liquid crystal display 400 , which is mainly composed of a display panel 410 , a backlight 420 and a data control circuit 430 . Wherein, the backlight 420 is disposed under the display panel 410 to provide a backlight for the display panel 410 . The data control circuit 430 is connected to the display panel 410 and the backlight 420 , and in particular, the data control circuit 430 is mainly composed of a comparison unit 432 , a frame image data storage unit 434 and a light source control unit 438 .

As mentioned above, the comparison unit 432 is used to receive the M-th frame image data frame(m-1) and the M-th frame image data frame(m) input in step S100 in the previous embodiment, and compare The pixel grayscale difference between the M-th frame of image data frame(m) and the M-1-th frame of image data frame(m-1), and then output the M-th frame of image data frame(m) to the display panel 410 . Wherein, the M−1th frame image data frame(m−1) is, for example, stored in the frame image data storage unit 434 connected to the comparison unit 432 . Moreover, when the Mth frame image data frame(m) is input to the comparison unit 432, it will also be input and stored in the frame image data storage unit 434 at the same time, so as to compare with the next frame image data within the next frame time. Compare.

It should be noted that, in order to include pixels of a plurality of previous frame image data as a reference (calculation method described in the second embodiment), the data control circuit of the present invention may further include a frame image weight filter 436, which is coupled to To the comparison unit 432, for receiving multiple comparison results output by the comparison unit 432 (for example, the number of pixels N(M), N(M-1), . . . , N(M-1) in the second embodiment (R-1)) etc.). Moreover, the frame image weight filter 436 further includes a 1xR array S, and the array S is composed of elements S[1], S[2], S[3], . . . , S[R], and these elements The initial value of is, for example, zero. In other words, in the initial state, S[1]=S[2]=...=S[R]=0. Wherein, R is the number of frames that the user wants to refer to. The number of pixels received by the frame image weight filter 436 from the comparison unit 432 is stored in the array S, so that the array S=[N(M), N(M-1), N(M-2), ..., N(M-(R-1))]. In other words, for example, N(M) is stored in element S[1] of array S, N(M-1) is stored in element S[2], ..., N(M-(R-1)) then is stored in the element S[R]. And calculate the weight distribution of the comparison result, and then output the calculation result (for example, the weighted average number of pixels N′(M) in the second embodiment) to the light source control unit 438 . Wherein, the light source control unit 438 is composed of, for example, a backlight duty ratio controller 438a and a backlight amplitude controller 438b.

As mentioned above, when the light source control unit 438 receives the calculation result output by the frame image weight filter 436, the light source control unit 438 outputs an appropriate driving voltage to the backlight source 420 according to the calculation result to drive the backlight source 420 , further enabling the liquid crystal display 400 to display images according to the frame image data input to the display panel 410 . Wherein, the luminous working ratio and the amplitude of the backlight are respectively controlled by the backlight working ratio controller 438a and the backlight amplitude controller 438b, so that the product of the luminous working ratio and the amplitude of the backlight is uniform in each frame time. equal, so that the brightness of the backlight can be maintained the same.

In the present invention, after inputting a frame of image data to the liquid crystal display, count the number of pixels with a grayscale difference between the frame of image data and the previous frame of image data, so as to generate N(M) to judge the display value of the liquid crystal display. If the picture is a dynamic picture or a static picture, then the luminous working ratio of the backlight is determined according to the statistical results. For example, when the statistical results show that the number of pixels with grayscale differences is not zero, it means that the picture displayed by the liquid crystal display is a dynamic picture, and at this time, the backlight source is driven with a pulsed voltage (as shown in Figure 2B) to make the dynamic picture clearer.

Conversely, when the statistical results show that the number of pixels with grayscale difference is zero, it means that the picture displayed by the liquid crystal display is a static picture, and at this time, the backlight is driven with a hold voltage (as shown in Figure 2A), so as to avoid This static image produces flickering problems.

To sum up, the present invention selects pulse-type driving or holding-type driving according to the nature of the display screen in the flat-panel display. In other words, the present invention can make the flat panel display have the advantages of pulse driving and holding driving at the same time, and get rid of the shortcomings of pulse driving and holding driving, so that the flat panel display can have better performance whether it is displaying dynamic pictures or static pictures. display quality.

Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention, rather than as a limitation to the present invention, as long as within the scope of the spirit of the present invention, the above-described embodiments Changes and modifications will fall within the scope of the claims of the present invention.

Claims (19)

1. A driving method of a flat panel display, suitable for driving a flat panel display with I×J pixels, wherein the flat panel display includes a backlight source, and at least one frame of image data has been stored in the flat panel display , it is characterized in that described driving method comprises: Input an Mth frame of image data; Comparing the grayscale value between the pixels of the Mth frame of image data and the pixels of an M-1th frame of image data, so as to obtain the grayscale difference; Outputting the pixel image data of the Mth frame of image data; Counting the number N(M) of pixels with a grayscale difference between the Mth frame of image data and the M-1th frame of image data; and Calculate and output the luminous duty ratio D and amplitude A of the backlight according to the number of pixels N(M) to drive the backlight, wherein the brightness of the light emitted by the backlight is a constant. 2. the driving method of flat panel display as claimed in claim 1 is characterized in that the method of described pixel number N (M) comprises making

When the grayscale difference between the (i, j)th pixel of the Mth frame of image data and the (i, j)th pixel of the M-1th frame of image data is greater than a critical grayscale difference , Z(M)(i, j)=1, and when the (i, j)th pixel of the Mth frame image data and the (ith)th pixel of the M-1th frame image data , when the gray level difference of j) pixels is smaller than the critical gray level difference, Z(M)(i, j)=0. 3. The driving method of a flat panel display according to claim 2, characterized in that the minimum value of the critical gray scale difference is 2. 4. The driving method of a flat panel display as claimed in claim 1, wherein the luminous duty ratio D of the backlight source is a function D[N(M)] of the number of pixels N(M), and The luminous amplitude A of the backlight source is a function A[N(M)] of the number of pixels N(M). 5. The driving method of a flat panel display as claimed in claim 4, characterized in that the luminous duty ratio of the backlight source

And D _limit is a critical duty ratio of the backlight source, and N _max is a critical pixel number. 6. the driving method of flat panel display as claimed in claim 5 is characterized in that when described pixel number N (M) is greater than described critical pixel number N _max , make this pixel number N (M) be equal to The critical number of pixels N _max . 7. The driving method of a flat panel display according to claim 5, wherein the minimum value of the critical duty ratio D _limit is 25%. 8. The driving method of a flat panel display as claimed in claim 5, wherein the maximum value of the critical pixel number N _max is 0.1×I×J. 9. The driving method of a flat-panel display as claimed in claim 1, wherein said flat-panel display further stores an array S of 1*R, and after counting said number of pixels N (M), further includes Store the number of pixels N(M) in the array S, so that the array S=[N(M), N(M-1), N(M-2),. .., N(M-(R-1))], where R is the number of frames that the user wants to refer to. 10. The driving method of a flat-panel display according to claim 9, characterized in that before calculating and outputting the luminous duty ratio D and the amplitude A of the backlight source, it further includes elements S[ 1] to S[R] to calculate an average number of pixels. 11. The driving method of a flat panel display as claimed in claim 10, wherein the method for calculating the average number of pixels comprises calculating a weighted average number of pixels

Wherein S[r] is the element of the array S, r is 1, 2, ..., R, and a _r is a weighted index of S[r], and the luminous duty ratio of the backlight source is D is the function D[N'(M)] of the weighted average pixel number N'(M), and the amplitude A of the backlight is a function of the weighted average pixel number N'(M) A[N'(M)]. 12. The driving method of a flat panel display according to claim 11, characterized in that said weighting index a _r ≥ _{a r+1} . 13. The driving method of a flat panel display as claimed in claim 11, characterized in that the luminous duty ratio of the backlight source is

And D _limit is a critical duty ratio of the backlight source, and N _max is a critical pixel number. 14. The driving method of a flat panel display according to claim 13, wherein the maximum value of the critical number of pixels N _max is 0.1×I×J. 15. The driving method of a flat panel display according to claim 13, wherein the minimum value of the critical duty ratio D _limit is 25%. 16. A flat panel display, characterized in that it comprises: a display panel; A backlight source arranged under the display panel; A data control circuit, connected to the display panel and the backlight, and the data control circuit includes: A comparison unit, used to receive and compare an Mth frame of image data with an M-1th frame of image data; A frame of image data storage unit connected to the comparison unit for outputting the M-th frames of image data stored therein to the comparison unit; and A light source control unit connected to the backlight to control the drive of the backlight; wherein the light source control unit includes a duty ratio controller and an amplitude controller, and the backlight The luminous duty ratio of the source is controlled by the duty ratio controller, and the luminous amplitude of the backlight source is controlled by the amplitude controller. 17. The flat-panel display as claimed in claim 16, wherein the data control circuit further comprises a frame image weighting filter coupled to the comparison unit for receiving an output from the comparison unit. The comparison results are compared, and the weight distribution of the comparison results is calculated. 18. The flat panel display as claimed in claim 17, wherein the frame image weighting filter further comprises an array suitable for storing the comparison result output by the comparison unit. 19. The flat panel display according to claim 16, 17 or 18, characterized in that said flat panel display is a liquid crystal display.

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