CN100489600C - Method for testing thickness of LCD device liquid crystal layer - Google Patents

Abstract

The present invention provides a detecting method of the thickness of the liquid crystal layer in a liquid crystal display device, and comprises the processing as following: (1) Detecting the average inclined angle Theta of liquid crystal display devices under the different external voltages, and selecting a group of suitable incident angles Alpha and the average inclined angle Theta as the detection condition for a retardation Delta; (2) Detecting the retardation Delta of liquid crystal display devices, and recording the values used in the process of measuring the retardation Delta, of the practical incident angle Alpha and the average inclined angle Theta, and also recording the detected retardation Delta; (3) According to the refraction index of ordinary light no, the refraction index of extraordinary light ne, and the incident angles Alpha and the average inclined angle Theta used in the process of measuring the retardation Delta of liquid crystal display devices in the process (2), calculating effective double refraction coefficient Delta neff; (4) According to the retardation Delta detected and obtained in the process (2) and Delta neff calculated and obtained in the process (3), calculating and obtaining the thickness d of the liquid crystal layer in the liquid crystal display devices. The present invention can achieve the accurate value of the thickness of the liquid crystal layer, and is easy to use and low in cost.

Description

The method of testing of thickness of LCD device liquid crystal layer

Technical field

The present invention relates to a kind of method of testing liquid crystal display spare thickness of liquid crystal layer.

Background technology

Ellipsometry obtains the retardation δ that different transmitances is come testing liquid crystal display spare vertical direction by changing the angle of the polarizer and analyzer, and by following formula, promptly formula (1) is tried to achieve thickness of liquid crystal layer then.

δ＝Δnd＝(n _e-n _o)d (1)

Wherein Δ n is a double refractive inde, and d is a thickness of liquid crystal layer, n _eBe non-ordinary light refractive index, n _oIt is ordinary refraction index.

The method of above-mentioned test thickness of liquid crystal layer does not need ordinary refraction index n _o, unusual optical index n _eConcrete numerical value, but directly calculate thickness of liquid crystal layer by their difference DELTA n, greatly improved the testing efficiency of thickness of liquid crystal layer, reduced the complexity of test, this method can accurately be measured the thickness of liquid crystal layer of the horizontal liquid crystal display device of liquid crystal molecule.

But the liquid crystal molecule in present most of liquid crystal display device is not horizontal, but oblique arrangement, (angle of long axis of liquid crystal molecule and oriented layer is called the tilt angle of liquid crystal molecule promptly to have certain average slope angle, the distribution situation of comprehensive actual liquid crystal display device thickness direction tilt angle, adopt one and amount to the inclined degree that numerical value is weighed liquid crystal molecule in the whole liquid crystal display device, i.e. average slope angle).If the liquid crystal display device that adopts above-mentioned method of testing test liquid crystal molecules tilt to arrange, then the average slope angle of liquid crystal molecule is big more, and this method of testing is low more to the measuring accuracy of thickness of liquid crystal layer.

Simultaneously, elliptical polarizer all has certain test lower limit, above-mentioned method of testing has been measured the retardation of liquid crystal display device vertical direction earlier, through type (1) calculates the numerical value of thickness of liquid crystal layer again, therefore for the less liquid crystal display device of vertical direction retardation, also be difficult to realize the accurate measurement of thickness of liquid crystal layer.

Therefore, aspect the thickness of liquid crystal layer test, the liquid crystal display device of arranging for liquid crystal molecules tilt, the perhaps liquid crystal display device of vertical direction retardation little (comprising two kinds of situations of liquid crystal molecules tilt and non-oblique arrangement), the measuring accuracy of above-mentioned method of testing obviously has limitation.

Summary of the invention

Technical matters to be solved by this invention provides the method for testing of the high thickness of LCD device liquid crystal layer of a kind of measuring accuracy.The technical scheme that adopts is as follows:

A kind of method of testing of thickness of LCD device liquid crystal layer may further comprise the steps:

(1) the average slope angle θ of liquid crystal display device under the different impressed voltage conditions of test, and select one group of suitable incident angle α and average tiltangle as retardation δ test condition; Specific practice is:

(1-1) choose display pixel area as test zone (if display pixel is big inadequately, then choosing the big zone of display pixel proportion tests), the upper/lower electrode of test zone display pixel is drawn, between upper/lower electrode, apply voltage, test the average slope angle θ of liquid crystal display device under the different impressed voltages;

(1-2) with ordinary refraction index n _o, unusual optical index n _eAnd two formulas, i.e. formula (2) and formula (3) below the numerical value substitution of the average slope angle θ that obtains of test:

${\mathrm{\&Delta;n}}_{\mathrm{eff}}=\frac{n_o^2-n_e^2}{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C200710029326E00122.png"\; state="\{\{state\}\}">n</figure-callout>}}^2}\sin \mathrm{\&theta;}\cos \mathrm{\&theta;}\sin \mathrm{\&alpha;}+\frac{n_o{n}_e}{n^2}{(n^2-{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="C200710029326E00122.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;})}^{\frac{1}{2}}-{({n_o}^2-{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="C200710029326E00122.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;})}^{\frac{1}{2}}---\left(2\right)$

N wherein ²=n _o ²Cos ²θ+n _e ²Sin ²θ (3)

Calculate the pairing effective double refractive inde Δ n of different average slope angle θ _EffRelation curve with incident angle α;

(1-3) from effective double refractive inde Δ n _EffWith choose big Δ n on the relation curve of incident angle α _EffThe numerical value of pairing one group of incident angle α and average tiltangle is as the test condition of retardation δ;

(2) the retardation δ of testing liquid crystal display spare (with ellipsometry retardation δ being tested usually); Specific practice is:

The upper/lower electrode of step (1) test zone display pixel is drawn, between upper/lower electrode, apply the impressed voltage that can obtain identical average slope angle θ in the step (1-3); With the incident angle α angle chosen in the step (1-3) incident angle α as retardation δ test, the retardation δ of testing liquid crystal display spare, the numerical value of actual incident angle α, average slope angle θ that record measurement retardation δ is adopted and measured retardation δ;

(3) with ordinary refraction index n _o, unusual optical index n _e, the incident angle α that testing liquid crystal display spare retardation δ adopts in the step (2) and average tiltangle substitution formula (2) and formula (3) are calculated effective double refractive inde Δ n _Eff

(4) the Δ n that calculates of retardation δ that step (2) test is obtained and step (3) _EffThe substitution following formula, i.e. formula (4),

δ＝Δn _effd (4)

By calculating the thickness of liquid crystal layer d of liquid crystal display device.

Above-mentioned method of testing can accurately be tested the thickness of liquid crystal layer of various liquid crystal display devices, no matter the liquid crystal molecule in the liquid crystal display device is horizontal or oblique arrangement, no matter liquid crystal display device vertical direction retardation is greatly or little, can both obtain accurate test result.

According to above-mentioned formula (4) as can be known, the thickness of liquid crystal layer of accurate testing liquid crystal display spare, key is to obtain one group of accurate retardation δ and effective double refractive inde Δ n _EffNumerical value; Above-mentioned steps (1) is chosen the test condition of retardation δ, promptly chooses one and makes up suitable incident angle α and average tiltangle, its objective is and will guarantee accurately to test the retardation δ of liquid crystal display device and effective double refractive inde Δ n of correspondence _Eff

And when not applying voltage between the upper/lower electrode of test zone display pixel vertical direction (incident angle α the is zero) liquid crystal display device that retardation is bigger, when this vertical direction retardation is prescribed a time limit down greater than the test of retardation tester (being generally elliptical polarizer), can simplify above-mentioned method of testing, to save testing expense and test duration.This moment is zero with incident angle α and average slope angle θ adopts the test condition of ecosystem average slope angle (being the average slope angle when not applying any extra electric field between the upper/lower electrode) as retardation δ, upper/lower electrode that will the test zone display pixel when therefore testing is derived, and the process of the test condition of retardation δ is selected in omission, formula (2) and (3) also correspondingly are reduced to following formula, be formula (5)

${\mathrm{\&Delta;n}}_{\mathrm{eff}}=\frac{n_o{n}_e}{\sqrt{{n_o}^2{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C200710029326E00122.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&theta;}+{{\mathrm{<figure-callout\; id="2"\; label="n\; e"\; filenames="C200710029326E00122.png"\; state="\{\{state\}\}">n</figure-callout>}}_e}^2{\sin }^2\mathrm{\&theta;}}}-n_o---\left(5\right)$

The method of testing of the thickness of LCD device liquid crystal layer of this simplification may further comprise the steps:

(1) chooses display pixel area as test zone (, then choose the big zone of display pixel proportion and test), the ecosystem average slope angle θ of testing liquid crystal display spare if display pixel is big inadequately;

(2) be the test condition of zero-sum ecosystem average slope angle θ with incident angle α as retardation δ, the retardation δ of testing liquid crystal display spare (with ellipsometry retardation δ being tested usually), be vertical direction retardation δ, test zone is identical with step (1);

(3) calculate effective double refractive inde Δ n _EffSpecific practice is:

Ordinary refraction index n with the used liquid crystal of liquid crystal display device _o, unusual optical index n _eAnd step (1) the average slope angle θ substitution formula (5) of testing, calculate effective double refractive inde Δ n of vertical incidence direction _Eff

(4) the thickness of liquid crystal layer d of calculating liquid crystal display device; Specific practice is:

The Δ n that retardation δ numerical value that step (2) test is obtained and step (3) obtain _EffNumerical value substitution formula (4) is by calculating the exact value of thickness of LCD device liquid crystal layer d.

The present invention by testing liquid crystal display spare under a certain incident angle and average slope angle retardation and obtain corresponding effectively double refractive inde, calculate the thickness of liquid crystal layer of liquid crystal display device, obtain the accurate numerical value of thickness of liquid crystal layer, for making the liquid crystal display device of retardation greater than elliptical polarizer test lower limit by changing incident direction and applying impressed voltage, no matter the liquid crystal molecule in the liquid crystal display device is horizontal or oblique arrangement, no matter liquid crystal display device vertical direction retardation is greatly or little, and the present invention can both obtain accurate thickness of liquid crystal layer test result; Obtain the tilt angle numerical value of different impressed voltage correspondences by test, find big pairing incident angle of retardation and average slope angle, carry out retardation test again, can realize accurately testing the thickness of liquid crystal layer of little but some the incident direction retardation of vertical direction retardation like this greater than the liquid crystal display device of elliptical polarizer test lower limit; For the bigger liquid crystal display device of vertical direction retardation, adopt the method for testing of simplifying to save testing expense and test duration.Compare with the method for originally utilizing ellipsometry test thickness of liquid crystal layer, the present invention mainly needs to carry out the test of tilt angle, whole process may need to draw display pixel electrode, impressed voltage is provided and regulates the incident angle angle, but the testing procedure that need not to transform original instrument and adjust original instrument is more easily implemented; For the mechanism that the tilt angle testing tool is arranged, implement the testing procedure that the present invention only needs to increase a tilt angle, test process only needs auxiliary material, external power supply and the simple incident angle angle regulator of extraction electrode can realize that cost is low.

Description of drawings

Fig. 1 is the process flow diagram of the preferred embodiment of the present invention;

Fig. 2 is that the test zone display pixel is drawn and the external power supply connection diagram in the preferred embodiment of the present invention.

Embodiment

As shown in Figure 1, when at first between the upper/lower electrode of test zone display pixel, not applying voltage, the retardation of pretest liquid crystal display device vertical direction is if retardation, then adopts following method one testing liquid crystal display spare thickness of liquid crystal layer less than the test lower limit of elliptical polarizer; If retardation, then adopts following method two (i.e. the method for Jian Huaing) testing liquid crystal display spare thickness of liquid crystal layer more than or equal to the test lower limit of elliptical polarizer.

Method one

Method one may further comprise the steps:

(1) the average slope angle θ of liquid crystal display device under the different impressed voltage conditions of test, and select one group of suitable incident angle α and average tiltangle as retardation δ test condition; Specific practice is:

(1-1) with reference to Fig. 2, choose display pixel 21～29 zones as test zone (if display pixel is big inadequately, then choosing the big zone of display pixel proportion tests), upper/lower electrode 4, the 5 usefulness conductive materials 10 of test zone display pixel 21～29 are drawn, and by lead 11 connection external power supplies 12, between upper/lower electrode 10, apply voltage, test the average slope angle θ of liquid crystal display device under the different impressed voltages; Top electrode 4 is located on the transparency carrier 1 among Fig. 2, and bottom electrode 5 is located on the transparency carrier 2;

(1-2) with ordinary refraction index n _o, unusual optical index n _eAnd the numerical value substitution formula (2) and the formula (3) of testing the average slope angle θ that obtains, calculate the pairing effective double refractive inde Δ n of different average slope angle θ _EffRelation curve with incident angle α;

(1-3) from effective double refractive inde Δ n _EffWith choose big Δ n on the relation curve of incident angle α _EffThe numerical value of pairing one group of incident angle α and average tiltangle is as the test condition of retardation δ;

(2) the retardation δ of testing liquid crystal display spare (retardation δ being tested) with ellipsometry; Specific practice is:

The upper/ lower electrode 4,5 of step (1) test zone display pixel 21～29 is drawn, between upper/ lower electrode 4,5, apply the impressed voltage that can obtain identical average slope angle θ in the step (1-3); With the incident angle α angle chosen in the step (1-3) incident angle α as retardation δ test, the retardation δ of testing liquid crystal display spare, the numerical value of actual incident angle α, average slope angle θ that record measurement retardation δ is adopted and measured retardation δ;

(3) with ordinary refraction index n _o, unusual optical index n _e, the incident angle α that testing liquid crystal display spare retardation δ adopts in the step (2) and average tiltangle substitution formula (2) and formula (3) are calculated effective double refractive inde Δ n _Eff

(4) the Δ n that calculates of retardation δ that step (2) test is obtained and step (3) _EffSubstitution formula (4) is by calculating the thickness of liquid crystal layer d of liquid crystal display device.

Method two

Method two may further comprise the steps:

(1) chooses display pixel area as test zone (, then choose the big zone of display pixel proportion and test), the ecosystem average slope angle θ of testing liquid crystal display spare if display pixel is big inadequately;

(2) be the test condition of zero-sum ecosystem average slope angle θ with incident angle α as retardation δ, with the retardation δ of elliptical polarizer testing liquid crystal display spare, i.e. vertical direction retardation δ, test zone is identical with step (1); Vertical direction retardation δ can continue to use above-mentioned pretest obtain the retardation of liquid crystal display device vertical direction, so this step can be omitted;

(3) calculate effective double refractive inde Δ n _EffSpecific practice is:

Ordinary refraction index n with the used liquid crystal of liquid crystal display device _o, unusual optical index n _eAnd step (1) the average slope angle θ substitution formula (5) of testing, calculate effective double refractive inde Δ n of vertical incidence direction _Eff

(4) the thickness of liquid crystal layer d of calculating liquid crystal display device; Specific practice is:

The Δ n that retardation δ numerical value that step (2) test is obtained and step (3) obtain _EffNumerical value substitution formula (4) is by calculating the exact value of thickness of LCD device liquid crystal layer d.

Claims (1)

1, a kind of method of testing of thickness of LCD device liquid crystal layer may further comprise the steps:

(1) the average slope angle θ of liquid crystal display device under the different impressed voltage conditions of test, and select one group of suitable incident angle α and average tiltangle as retardation δ test condition; Specific practice is:

(1-1) choose display pixel area, the upper/lower electrode of test zone display pixel is drawn, between upper/lower electrode, apply voltage, test the average slope angle θ of liquid crystal display device under the different impressed voltages as test zone;

(1-2) with ordinary refraction index n _o, unusual optical index n _eAnd two formulas, i.e. formula (2) and formula (3) below the numerical value substitution of the average slope angle θ that obtains of test:

${\mathrm{\&Delta;n}}_{\mathrm{eff}}=\frac{n_o^2-n_e^2}{n^2}\sin \mathrm{\&theta;}\cos \mathrm{\&theta;}\sin \mathrm{\&alpha;}+\frac{n_o{n}_e}{n^2}{(n^2-{\sin }^2\mathrm{\&alpha;})}^{\frac{1}{2}}-{\left({n_o^2-\sin }^2\mathrm{\&alpha;}\right)}^{\frac{1}{2}}---\left(2\right)$

N wherein ²=n _o ²Cos ²θ+n _e ²Sin ²θ (3)

Calculate the pairing effective double refractive inde Δ n of different average slope angle θ _EffRelation curve with incident angle α;

(1-3) from effective double refractive inde Δ n _EffWith choose big Δ n on the relation curve of incident angle α _EffThe numerical value of pairing one group of incident angle α and average tiltangle is as the test condition of retardation δ;

(2) the retardation δ of testing liquid crystal display spare; Specific practice is:

The upper/lower electrode of step (1) test zone display pixel is drawn, between upper/lower electrode, apply the impressed voltage that can obtain identical average slope angle θ in the step (1-3); With the incident angle α angle chosen in the step (1-3) incident angle α as retardation δ test, the retardation δ of testing liquid crystal display spare, the numerical value of actual incident angle α, average slope angle θ that record measurement retardation δ is adopted and measured retardation δ;

(3) with ordinary refraction index n _o, unusual optical index n _e, the incident angle α that testing liquid crystal display spare retardation δ adopts in the step (2) and average tiltangle substitution formula (2) and formula (3) are calculated effective double refractive inde Δ n _Eff

(4) the Δ n that calculates of retardation δ that step (2) test is obtained and step (3) _EffThe substitution following formula, i.e. formula (4),

δ＝Δn _effd (4)

By calculating the thickness of liquid crystal layer d of liquid crystal display device.

Images