CN100354703C - A method for improving display crosstalk of LCD - Google Patents

Abstract

The present invention discloses a method for improving the displace crossfire of a liquid crystal display. The ratio of the length and the width of each COM running cable is controlled, and the number of squares of the running cable is decreased in a constant or in an arithmetic progression, and satisfies the following inequality: (R COM_MAX + R OUT) * C COM /1/ (Fr * N) < 3 %. In the formula R COM_MAX, IC is driven to a max value of a resistor of the COM running cable of a display area from the LCD. In R OUT, an output resistor of a COM electrode is driven by the LCD, and C COM is a load capacitor of the COM running cable of the LCD. Fr is the refresh frequency of the LCD, and N is the electrode number of the COM. Requirement is brought forward quantitatively to the resistor of the COM running cable by the present invention, and the driving rectangular pulse wave width distortion for delivering IC which is driven by the LCD to the COM running cable is controlled in a reasonable range. Thus, the phenomenon of displaying crosstalk of the LCD is effectively improved. A display is examined in black and white interlaced pictures with superpower contrast, the displayed color edge is sharp, and the phenomenon of crosstalk does not basically exist in the pictures.

Description

A kind ofly improve the method that liquid crystal display displays is crosstalked

Technical field

The present invention relates to be used for the device or the device of light intensity, color, phase place, polarization or direction, specifically relate to a kind of method that liquid crystal display displays is crosstalked of improving from the control arbitrary source based on liquid crystal.

Background technology

The super-twist nematic liquid crystal display that mobile phone, personal digital assistant, digital camera and screen game machine adopt, (hereinafter to be referred as STN-LCD), its information capacity is generally all bigger, the scan electrode quantity of LCD is corresponding many, the scan electrode quantity of LCD is many, the time of a scan electrode of scanning shortens relatively, the rect.p. waveform fabric width of LCD drive integrated circuit (hereinafter to be referred as the LCD drive IC) output narrows down relatively, and the waveform distortion amount that is equal to has bigger fabric width percent distortion.

The approximate equivalent circuit of LCD is the singly-terminal pair that is composed in series by the equivalent capacity of the equivalent d.c. resistance of pixel and this pixel and joint group and the nesa coating resistance from the electrode to the pixel, the line resistance of walking that is present in LCD inside, load capacitance and spurious impedance, the driving rect.p. number percent that can cause the LCD drive IC to be sent to the COM cabling reaches 5～10%, cause the LCD high-brightness region around certain regional brightness arranged, can follow picture and take place to change significantly, horizontal direction or vertical direction around in the viewing area form the uneven demonstration crosstalk phenomenon of strip contrast.Produce and show that the principal element of crosstalking is drive characteristic, waveform distortion and the peripheral circuit thereof of LCD drive IC and the electro-optical characteristic of LCD.The existing LCD that improves shows that the method for crosstalking is to pay attention to improving the electro-optical characteristic of LCD, as improve the manufacture craft condition, or the little liquid crystal material of employing steepness, the liquid crystal material that steepness is little can make the electro-optical characteristic of LCD more precipitous, and then improve the LCD demonstration and crosstalk, but produce little effect, the STN-LCD that selects steepness to make less than 1.03 liquid crystal material, its demonstration is crosstalked still very serious.

Summary of the invention

The technical problem to be solved in the present invention is that the drive pulse waveform distortion that the LCD drive IC is sent to the COM cabling effectively is controlled within the reasonable range, proposes a kind of method that liquid crystal display displays is crosstalked of improving.

The liquid crystal display displays crosstalk method that improves of the present invention is based on COM cabling resistance value and causes waveform distortion, and then to showing that contrast has very big influence.Detect the demonstration of LCD and crosstalk, investigate the sharpness at LCD color edge to contrast extremely strong black and white interlaced fields exactly.Therefore, crosstalk, should start with from the waveform distortion of improving LCD in order to improve the LCD demonstration.

The approximate equivalent circuit of LCD can be reduced to away the RC loop that line resistance and liquid crystal capacitance are formed, the reason of walking line resistance owing to COM causes the LCD drive IC to export the sweep waveform generation partial distortion of COM cabling to, so that liquid crystal display picture distortion, voltage mean square value that its formed influence is a display pixel changes, so that crosses black or cross bright phenomenon.Waveform distortion and COM walk line resistance and liquid crystal capacitance has direct relation, realize good display frame contrast, the COM that should reduce from the LCD drive IC to the viewing area walks line resistance, and then effectively controls the waveform distortion of COM cabling, show image quality thereby improve, promptly improve the demonstration crosstalk phenomenon.

Square resistance R Be the important performance characteristic that nesa coating manufacturer provides, the resistivity of its numerical value and electrically conducting transparent membrane material is relevant with the thickness of nesa coating, and is little to several ohm, greatly to 100 ohm.And COM walks the numerical value of line resistance is by COM track lengths, trace width and square resistance R Determined.

COM cabling resistance R _COMWith square resistance R Relation as follows:

In the following formula:

The length of L:COM cabling;

The width of W:COM cabling;

The square number of COM cabling.

Following formula shows that will to make whole section COM walk line resistance as far as possible little, will shorten the COM track lengths as far as possible and increase trace width, perhaps selects the low nesa coating of square resistance.When shortening the COM track lengths and increasing trace width, should pay attention to the distribution situation that COM on the whole screen walks line resistance.In general, the COM track lengths is bigger, it is big that corresponding trace width is also wanted, all to guarantee the ratio of track lengths and trace width for every COM cabling, it is the square number of COM cabling, be a constant substantially amount or successively decrease with arithmetic progression, thus the distribution of resistance that makes the COM cabling as far as possible evenly or equal difference change, to help to improve the contrast of whole screen.

Improve the method that liquid crystal display displays is crosstalked for of the present invention, above-mentioned technical matters is solved like this:

Thisly improve the method that liquid crystal display displays crosstalks and be, control the ratio of every COM track lengths and trace width, i.e. the square number of COM cabling is a constant or successively decrease with arithmetic progression, and satisfies with lower inequality:

$\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}+R_{\mathrm{OUT}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}<3\%\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

In the inequality (1):

R _{COM_MAX}: the COM from the LCD drive IC to the viewing area walks the maximal value of line resistance;

R _OUT: the COM electrode output resistance of LCD drive IC;

C _COM: the load capacitance of a COM line of LCD;

The refreshing frequency of Fr:LCD;

The N:COM number of electrodes.

COM walks line resistance and changes with track lengths is different, selects its maximal value here, the R of same LCD drive IC _OUTIt generally is constant.

Inequality (1) is the qualification of the COM from the LCD drive IC to the viewing area being walked the maximum value of line resistance permission.Satisfy the COM that inequality (1) requires and walk line resistance, can guarantee that COM by LCD inside walks line resistance, load capacitance and spurious impedance and the LCD drive IC that causes is sent to the driving rect.p. waveform fabric width percent distortion of a COM cabling and is controlled in 3%.

For further improving the technical matters that liquid crystal display displays is crosstalked, the present invention preferably improves the method that liquid crystal display displays crosstalks and is, controls every COM cabling, also satisfies with lower inequality:

$\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}-R_{\mathrm{COM}\_\mathrm{MIN}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}<1.8\%\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

In the inequality (2):

R _{COM_MAX}: the COM from the LCD drive IC to the viewing area walks the maximal value of line resistance;

R _{COM_MIN}: the COM from the LCD drive IC to the viewing area walks the minimum value of line resistance;

C _COM: the load capacitance of a COM line of LCD;

The refreshing frequency of Fr:LCD;

The N:COM number of electrodes.

Inequality (2) is the qualification of the COM from the LCD drive IC to the viewing area being walked the maximum deflection difference value of line resistance permission.The COM that satisfies inequality (2) requirement walks line resistance, can guarantee that the difference of driving rect.p. waveform fabric width percent distortion that LCD drive IC that different COM electrodes are caused by the walking line resistance, load capacitance of LCD inside is sent to the COM cabling less than 1.8%, shows that image quality is better thereby make.

The present invention walks line resistance to COM and claims quantitatively, basically can guarantee effectively that same or different COM electrodes are walked line resistance, load capacitance by the COM of LCD inside and the LCD drive IC that causes is sent to the driving rect.p. waveform fabric width distortion of COM cabling, be controlled within the reasonable range, and then produce effects ground improves the demonstration crosstalk phenomenon of LCD, investigate display to contrast extremely strong black and white interlaced fields, the color clear-cut margin of its demonstration, picture does not have crosstalk phenomenon substantially.

Embodiment:

A kind ofly improve the method that liquid crystal display displays is crosstalked

Below in conjunction with embodiment the present invention is described in further detail.

Embodiment: LCD is that dot matrix is 128 * 160, COM number of electrodes 160, be dutycycle DUTY=1/160, it is the ratio of time with the time of scanning one width of cloth picture of a COM line of scanning, refreshing frequency is the STN-LCD of 75Hz.

The LCD drive IC adopts the S6B33B0A of Samsung.

The COM cabling be the COM electrode earlier at small pieces cabling on glass to the transfer printing point, be transferred to big sheet glass by the transfer printing point again, cabling is to drive IC then.160 COM electrode cabling square bases are originally arranged with arithmetic progression, and difference is 7 squares.

When design COM cabling, by adjusting track lengths and trace width, cabling square number successively decreases with arithmetic progression.160 COM electrodes of integrated planning cabling, substantially arrange with arithmetic progression, this arithmetic progression is 1352,1345,1338 ..., 835.6,829.1,822.8,816.6,809.9,803.5 ..., 317.2,310.4,303.4, difference is 7 substantially.

With regard to some cablings, the cabling from the COM electrode to drive IC is not a straight line, and width is not that every place is all identical, but decides according to actual cabling situation, cabling space, and track lengths is big, and corresponding trace width is suitably big.

The largest block number is 1352, and minimum square number is 303.4.Suitably selecting the square resistance R of nesa coating is 5 Ω.

COM walks the product that line resistance is square resistance and cabling square number, and it is 1352 * 5 Ω=6760 Ω that corresponding maximum COM walks line resistance, and it is 303.4 * 5 Ω=1517 Ω that minimum COM walks line resistance.

The COM electrode output impedance of LCD drive IC is 1.0K Ω.

The COM linear load electric capacity of LCD is 0.256nF.Calculate by following formula:

C _ROW＝ε ₀ε _LCS/d _LC。

In the following formula:

ε ₀: permittivity of vacuum 9 * 10 ^-12F/m;

ε _LC: the relative dielectric constant of liquid crystal, the concrete numerical value difference of different liquid crystal materials generally is 25;

S: the area of a COM electrode, present embodiment are 0.225mm * 30.323mm=6.82mm ²

d _LC: the box of LCD is thick, generally is about 6 microns.

Calculate $\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}+R_{\mathrm{OUT}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}$

$=\frac{(6760+1000)\&times;0.256*{10}^{-9}}{1/(75\&times;160)}$

$=2.38\%$

$<3\%;$

Calculate again $\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}-R_{\mathrm{COM}\_\mathrm{MIN}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}$

$=\frac{(6760-1517)\&times;0.256*{10}^{-9}}{1/(75\&times;160)}$

$=1.61\%$

$<1.8\%.$

Present embodiment test quantity is 10000PCS, and the quantity of crosstalking is 16PCS, and the demonstration crosstalk phenomenon of LCD has the improvement of produce effects.

Reference examples: LCD is that dot matrix is 128 * 160, COM number of electrodes 160, square resistance R Be 7 Ω, driving frequency is the STN-LCD of 75Hz.

The LCD drive IC adopts the S6B33B0A of Samsung.

When design COM cabling, by adjusting COM track lengths and trace width, the largest block number is 1802, and minimum square number is 484.Suitably select the square resistance R of nesa coating Be 7 Ω.

COM walks the product that line resistance is square resistance and cabling square number, and it is 1802 * 7=12614 Ω that corresponding maximum COM walks line resistance, and it is 484 * 7=3388 Ω that minimum COM walks line resistance.

The COM linear load electric capacity of LCD is 0.256nF, and the serial line interface electrode output resistance of LCD drive IC is 1.0K Ω.

Calculate $\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}+R_{\mathrm{OUT}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}$

$=\frac{(12614+1000)\&times;0.256*{10}^{-9}}{1/(75\&times;160)}$

$=4.18\%$

$>3\%;$

Calculate again $\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}-R_{\mathrm{COM}\_\mathrm{MIN}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}$

$=\frac{(12614-3388)\&times;0.256*{10}^{-9}}{1/(75\&times;160)}$

$=2.83\%$

$>1.8\%.$

This reference examples test quantity is 10000PCS, and the quantity of crosstalking is 1933PCS, and the demonstration crosstalk phenomenon of LCD is more serious.

Above content be in conjunction with concrete preferred implementation to further describing that the present invention did, can not assert that concrete enforcement of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to the scope of patent protection that the present invention is determined by claims of being submitted to.

Claims (2)

1. one kind is improved the method that liquid crystal display displays is crosstalked, and it is characterized in that: control the ratio of every COM track lengths and trace width, i.e. the square number of COM cabling is a constant or successively decrease with arithmetic progression, and satisfies with lower inequality:

$\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}+R_{\mathrm{OUT}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}<3\%$

In the inequality:

R _{COM_MAX}: the COM from the LCD drive IC to the viewing area walks the maximal value of line resistance;

R _OUT: the COM electrode output resistance of LCD drive IC;

C _COM: the load capacitance of a COM line of LCD;

The refreshing frequency of Fr:LCD;

The N:COM number of electrodes.

2. improve the method that liquid crystal display displays is crosstalked according to claim 1 is described, it is characterized in that: control every COM cabling, also satisfy with lower inequality:

$\frac{(R_{\mathrm{COM}\_\mathrm{MAX}}-R_{\mathrm{COM}\_\mathrm{MIN}})\&times;C_{\mathrm{COM}}}{1/(\mathrm{Fr}\&times;N)}<1.8\%$

In the inequality:

R _{COM_MAX}: the COM from the LCD drive IC to the viewing area walks the maximal value of line resistance;

R _{COM_MIN}: the COM from the LCD drive IC to the viewing area walks the minimum value of line resistance;

C _COM: the load capacitance of a COM line of LCD;

The refreshing frequency of Fr:LCD;

The N:COM number of electrodes.