CN100589166C - Driving device and driving method for liquid crystal display - Google Patents

Abstract

The invention discloses a driving device and a driving method for rapidly driving an image signal in a liquid crystal display. The driving device of the liquid crystal display of the invention, is used for reducing the noise produced because of overdriving, receive a video signal, this video signal is formed by consecutive picture, this driving device includes: a brightness weight value processing unit, which calculates a brightness weight value according to the brightness value of the current picture and the brightness value of the previous picture of the image signal; an overdrive value generating unit for generating an overdrive value according to the image data of the current frame and the image data of the previous frame of the image signal; an overdrive weighted value generating unit for generating an overdrive weighted value according to the brightness weighted value and the overdrive value; and an image signal output unit, which applies the overdrive weighted value and the overdrive value to the current frame of the image signal. The driving device can reduce the noise generated by over-driving.

Description

Liquid crystal display driving device and driving method thereof

technical field

The invention relates to the field of picture processing of liquid crystal displays. In particular, it relates to a driving circuit and a driving method thereof for excessively driving an image signal in a liquid crystal display, which can greatly eliminate afterimages,

Background technique

Electronic devices often display the processed information through a display, and users can interact with the electronic device through the displayed information to achieve the purpose of effectively using the electronic device to process information. Computers belong to this type of electronic device.

Liquid crystal displays are currently the most popular displays due to their small size and light weight. The pixels of a liquid crystal display device are composed of liquid crystal molecules arranged vertically and horizontally in a matrix. Each pixel is equipped with an electrode for applying a voltage to the liquid crystal. Using the electrodes of each pixel to apply a voltage to the liquid crystal can change the alignment direction of the liquid crystal, and the liquid crystal The alignment direction of the liquid crystal determines the amount of light passing through the liquid crystal, so the purpose of displaying images can be achieved by controlling the alignment direction of the liquid crystal.

As shown in FIG. 1 , it is a timing diagram of pixel voltage and light transmittance in a conventional liquid crystal display device, wherein the pixel voltage is marked by a solid line, and the light transmittance is marked by a dotted line L. When the voltage of a pixel in the liquid crystal display device is switched from V1 to V2, there will be a delay time due to the characteristics of the liquid crystal molecules, so that the liquid crystal molecules cannot be deflected to the predetermined direction within a frame period (T) to achieve the predetermined Light transmittance, however, such a delay will cause image sticking in the liquid crystal display device. In order to improve this phenomenon, an accelerated liquid crystal driving method is used in a liquid crystal display device, as shown in FIG. 2 , which is a timing diagram of pixel voltage and light transmittance when using an accelerated liquid crystal driving method. When the pixel voltage in the liquid crystal display device is switched from V1 to V2, the twisting speed of the liquid crystal molecules is accelerated by increasing the voltage to V3, so that the liquid crystal molecules can be deflected to a predetermined direction within one frame period (T), and then reach the predetermined direction. light transmittance. The twisting speed of the liquid crystal molecules can be represented by the response time of the liquid crystal display device, and the faster the twisting speed of the liquid crystal molecules, the shorter the response time required for switching states.

However, this compensation technique still has its disadvantages. For example, when the picture is switched from one low luminance value to the next high luminance value (which is considerably higher), the overdrive signal amount provided by overdriving the picture signal is bound to be quite large, so that the noise will also follow. is amplified, and noise will degrade the image quality, so this compensation technology still needs to be improved.

Due to the above deficiency, it is indeed necessary to improve the overdrive technology of the picture color signal in the liquid crystal display.

Contents of the invention

The technical problem to be solved by the present invention is to propose a driving circuit for overdriving image signals in a liquid crystal display, which can take into account the driving strength set by the user and prevent noise from increasing with overdriving.

Another object of the present invention is to provide a driving method for overdriving image signals in a liquid crystal display, which can take into account the driving strength set by the user, and prevent noise from increasing with overdriving.

In order to achieve the above object, the present invention proposes a driving device for a liquid crystal display, which is used to reduce the noise generated by overdrive, and receives an image signal, which is composed of continuous frames. The drive circuit includes: a brightness weight value processing A unit, which calculates a brightness weight value based on the brightness value of the current frame of the video signal and the brightness value of the previous frame; an overdrive value generating unit, which calculates a brightness weight value based on the image data of the current frame of the video signal and the image of the previous frame data to generate an overdrive value; an overdrive weight value generation unit generates an overdrive weight value according to the luminance weight value and the overdrive value; and an image signal output unit generates the overdrive weight value and The overdrive value is applied to the current frame of the image signal to obtain an output image signal; wherein, G _n ′=W _OD *G _{n — OD} +(1−W _OD )*G _n .

The driving circuit also includes a luminance value calculation unit for calculating the luminance value of the image signal.

The present invention also proposes a method for driving a liquid crystal display, which is used to reduce noise caused by overdrive. The steps include: receiving an image signal, the image signal is composed of continuous frames; calculating a brightness weight value, according to the image Signal the brightness value of the current frame and the brightness value of the previous frame; generate an overdrive value based on the image data of the current frame of the image signal and the image data of the previous frame; generate an overdrive weight value based on the brightness weight value and the overdrive value; and, applying the overdrive weight value and the overdrive value to the current frame of the image signal and outputting an output image signal;

Wherein, G _n '=W _OD *G _{n_OD} +(1-W _OD )*G _n .

By adopting the driving device and the driving method of the present invention, the noise generated by over-driving can be reduced.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

The present invention will be illustrated by the following drawings in conjunction with preferred embodiments, wherein:

Fig. 1 is an explanatory diagram of the occurrence of afterimage in the existing liquid crystal display;

FIG. 2 is a schematic diagram of an image retention reduction technology in an existing liquid crystal display;

Fig. 3 is a functional block diagram of a driving device of the present invention;

Fig. 4 is a functional block diagram of an overdrive value generation unit in the drive device of the present invention;

FIG. 5 is a flow chart of the driving method of the present invention.

Among them, reference signs:

300: drive unit

30: Brightness value calculation unit

32: Brightness weight value processing unit

34: Overdrive value generation unit

36: Overdrive weight value generation unit

38: Image signal output unit

341: memory

342: Checklist

Detailed ways

The invention discloses a driving device and a driving method for overdriving an image signal in a liquid crystal display, which will be described below through preferred embodiments in conjunction with the accompanying drawings.

In terms of function, the driving device of the present invention can be described by the functional block diagram shown in FIG. 2 . The driving device 300 in FIG. 3 includes a brightness weight value processing unit 32 , an overdrive value generation unit 34 , an overdrive weight value generation unit 36 and an image signal output unit 38 . In an embodiment, the driving device of the present invention may further include a luminance value calculation unit 30 . The driving device 300 of the present invention receives an image signal G _N composed of consecutive frames, and then applies an appropriate overdrive value to the image signal according to the difference between the previous and subsequent frames and then outputs it.

The brightness weight value processing unit 32 in the driving device 300 is used to generate a brightness weight value, which is generated according to the brightness value LY _N of the current frame G _N of the input image signal and the brightness value LY _N-1 of the previous frame G _N- 1 , and the brightness values of the current frame G _N and the previous frame G _N−1 can be obtained by a brightness value calculation unit 30 . In one embodiment, the user can adjust the brightness values LY _N and LY _N-1 by inputting a control signal Y _ctrl . The brightness signals LY _N and LY _N-1 of the current and previous frames are respectively input to the brightness weight value processing unit 32 to calculate a brightness weight value W _Y , and in one embodiment, the brightness weight value processing unit 32 is In the form of a look-up table, through a pre-designed look-up table (Look-up Table), input the brightness value LY _N of the current picture G _N and the brightness value LY _{N- 1 of the previous picture G N-1} to look up Table to obtain its corresponding brightness weight value W _Y . In addition, there is another control signal W _Th for the user to input into the brightness weight value processing unit 32 to adjust the brightness weight value. In one embodiment, the control signal W _Th is a threshold signal to limit the brightness The range of the weight value, the calculation of the brightness weight value signal W _Th is to prevent the noise from being amplified when the image signal is over-driven.

The overdrive value generating unit 34 is used to generate an overdrive value that accelerates the twisting of the liquid crystal, as shown in FIG. To store the image signal, when the current frame G _{n of} the image signal is input, the current frame G _n is first stored in the memory, and then the current frame G _n and the previous frame G _n-1 stored in the memory are respectively input to the check In the table 342, a pre-designed overdrive value _{Gn_OD} is obtained through a look-up table. The values in the look-up table 342 are pre-designed and stored in a storage unit. In another embodiment, in order to save For the storage space occupied by the look-up table, a smaller look-up table and an interpolation circuit can be used to obtain the appropriate overdrive value _{Gn_OD} .

In order to reduce the effect of noise amplification caused by overdrive, the drive device 300 of the present invention has an overdrive weight value generation unit 36, which is used to generate an overdrive weight value to limit and adjust the overdrive value to reduce noise the goal of. The overdrive weight value generating unit 36 determines an appropriate overdrive weight value W _OD according to the brightness weight value W _Y and the overdrive value G _{n_OD} , and generates an overdrive weight value W by referring to the brightness factor and the size of the overdrive value at the same time. _OD , to achieve the purpose of reducing noise.

Finally, the driving device 300 applies the overdrive value G _{n_OD} and the overdrive weight W _OD to the current frame G _n of the image signal through an image signal output unit 38 to obtain an output image signal G _n ′. In a preferred embodiment, the output image signal _Gn ' can be represented by the following formula:

G _n '＝W _OD *G _{n_OD} +(1-W _OD )*G _n

In this way, the obtained output image signal G _n ′ can achieve the purpose of over-driving the liquid crystal molecules, and can also reduce the noise generated therefrom.

As shown in FIG. 5 , it is a flowchart of the driving method proposed by the present invention. Its main steps are as follows:

In step S101, an image signal is received, and the image signal is composed of continuous frames.

Step S102, calculating a brightness weight value based on the brightness value of the current frame and the brightness value of the previous frame of the video signal. First calculate the luminance value of the input video signal, and then use the luminance value of the current picture of the video signal and the luminance value of the previous picture to generate a luminance weight value. The luminance weight value can be checked by checking a pre-designed look-up table get.

Step S103, generating an overdrive value based on the image data of the current frame and the image data of the previous frame of the image signal. In one embodiment, by checking a pre-designed look-up table, an overdrive value can be found according to the image data of the current frame and the image data of the previous frame of the image signal. In another embodiment, in order to save the storage space occupied by the look-up table, a smaller look-up table may be used, and an interpolation method may be used to obtain an appropriate overdrive value.

Step S104, generating an overdrive weight value based on the brightness weight value and the overdrive value. In order to prevent the noise from being amplified due to overdrive, the present invention uses an overdrive weight value to limit and adjust the overdrive value to achieve the purpose of reducing noise. produced.

Step S105 , applying the overdrive weight value and the overdrive value to the current frame of the image signal and outputting it. The obtained overdrive weight value and overdrive value are applied to the current image of the image signal, so that the image signal has an overdrive effect, so as to reduce the generation of afterimage, and avoid the noise generated by overdrive through the overdrive weight value.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (13)

1. A driving device for a liquid crystal display, used to reduce noise generated due to overdrive, and receive an image signal, which is composed of continuous frames, characterized in that the driving device includes: A brightness weight value processing unit, which calculates a brightness weight value according to the brightness value of the current frame of the video signal and the brightness value of the previous frame; an overdrive value generation unit, which generates an overdrive value according to the image data of the current frame and the image data of the previous frame of the image signal; an overdrive weight value generating unit for generating an overdrive weight value according to the brightness weight value and the overdrive value; and an image signal output unit, which applies the overdrive weight value and the overdrive value to the current frame of the image signal to obtain an output image signal; Among them, G _n '=W _OD *G _{n_OD} +(1-W _OD )*G _{n Gn_OD} is the overdrive value, _WOD is the overdrive weight value, _Gn is the current frame of the video signal, and _Gn ' is the output video signal. 2. The driving device according to claim 1, further comprising a luminance value calculation unit for calculating the luminance value of the image signal. 3. The driving device according to claim 2, wherein the luminance value calculation unit receives a control parameter to adjust the luminance value of the image signal. 4. The driving device according to claim 1, wherein the brightness weight value processing unit receives a control signal, and the control signal is used to control the threshold value of the brightness weight value. 5. The driving device according to claim 1, wherein the overdrive value generating unit comprises a first look-up table, and the overdrive value can be obtained through the first look-up table. 6. The driving device according to claim 5, wherein the first look-up table is stored in a first memory. 7. The driving device according to claim 6, wherein the overdrive value generation unit comprises an interpolation circuit. 8. The driving device as claimed in claim 1, wherein the image data of the previous frame of the image signal is stored in a second memory. 9. The driving device according to claim 1, wherein the brightness weight value processing unit comprises a second look-up table, through which the brightness weight value can be looked up. 10. A driving method for a liquid crystal display, used to reduce noise generated due to overdrive, characterized in that the steps include: receiving an image signal, the image signal is composed of continuous frames; calculating a luminance weight value based on the luminance value of the current frame and the luminance value of the previous frame of the video signal; generating an overdrive value based on the image data of the current frame and the image data of the previous frame of the image signal; generating an overdrive weight value based on the luminance weight value and the overdrive value; and applying the overdrive weight value and the overdrive value to the current frame of the video signal and outputting an output video signal; Among them, G _n '=W _OD *G _{n_OD} +(1-W _OD )*G _{n Gn_OD} is the overdrive value, _WOD is the overdrive weight value, _Gn is the current frame of the video signal, and _Gn ' is the output video signal. 11. The driving method as claimed in claim 10, further comprising a step of: calculating the luminance value of the image signal. 12. The driving method according to claim 10, wherein the overdriving value is obtained by looking up a table. 13. The driving method according to claim 10, wherein the overdrive value is obtained through table look-up and interpolation.

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