JP2002350119A - Method for evaluating reflective liquid crystal display element, evaluating apparatus therefor and recording medium stored with computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure and evaluate at high speeds a sample in-plane distribution of a twist angle and an average inclination angle of liquid crystal molecules and a thickness of a liquid crystal layer in a reflective liquid crystal display element. SOLUTION: There are comprised of a light source having a plurality of wavelengths, a beam expander 2 for expanding light to enable wide-range observation, a polarizer 3 for controlling a polarization state of the light entering a sample 5, a phase element, a phase element for measuring the polarization state of the light passing the sample, an analyzer 6, an imaging lens 7, a two-dimensional CCD camera 8, and a sample stage 4 having a mechanism for rotating the liquid crystal display element of the sample 5 in a sample in-plane direction and a mechanism for moving the sample in parallel within the sample plane. The twist angle of the liquid crystal layer, the average inclination angle and the thickness of the liquid crystal layer are determined by measuring the sample direction dependency and the wavelength dispersion dependency of an intensity of reflecting light generated when the light is rotated in the sample in-plane direction while keeping a constant angle of incidence to the sample plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for evaluating a reflection type liquid crystal display device, and more particularly to a method for evaluating a twist angle (twist angle) and an average tilt angle of a liquid crystal in a liquid crystal display device and a thickness of a liquid crystal layer. The present invention relates to a method for evaluating a liquid crystal display element to be measured and an apparatus for evaluating the method.

[0002]

2. Description of the Related Art There are various methods for evaluating a conventional reflection type liquid crystal display device and its evaluation apparatus. As a method for measuring a twist angle, a method of transmitting light through a liquid crystal cell sandwiched between a polarizer and an analyzer is known. A method of determining from the light intensity has been proposed for the purpose of measuring the anchoring intensity (“Method of measuring interface anchoring intensity of liquid crystal display element”).
This is disclosed in Japanese Patent Application Laid-Open No. Hei 6-265839, 265840 (hereinafter referred to as Conventional Example 1).

A method proposed in Japanese Patent Application Laid-Open No. 8-184413 (hereinafter referred to as Conventional Example 2) is a method for measuring the thickness (hereinafter referred to as a cell gap) and the twist angle of a liquid crystal layer of a liquid crystal display device. Using a device arranged in the order of a monochromatic light source, polarizer, liquid crystal display element, analyzer, photodetector,
By adjusting the azimuth of the polarizer or analyzer and the azimuth of the liquid crystal display element, the cell gap is determined from the two sets of liquid crystal display element azimuth and the polarizer or analyzer azimuth where the transmitted light intensity detected by the photodetector is minimized. And a method for determining the twist angle.

Further, Japanese Patent No. 2778935 (issued in May 1998; hereinafter referred to as Conventional Example 3) has been determined as a method for determining a cell gap and a twist angle for the purpose of measuring the anchoring strength of a liquid crystal. A method using a light source, a polarizer, a liquid crystal display element, an analyzer, a photodetector, and a photoelastic element has been proposed in order to accurately determine an analyzer direction and a liquid crystal element direction in which transmitted light intensity is minimal. I have.

Further, as a prior application of the present invention, Japanese Patent Application No.
No. 345107 (hereinafter referred to as a prior application) proposes a method for determining a cell gap, a twist angle, and an average tilt angle, a mechanism for rotating an in-plane of a sample, a light source having a plurality of wavelengths, and polarization of light incident on the sample. Polarizer, phaser, which controls the state,
In addition, a method using a phase shifter, an analyzer, a spectroscope for monochromaticizing the wavelength of light, and a photodetector for measuring the polarization state of light transmitted through a sample has been proposed. FIG. 9 is a block diagram illustrating the configuration of this prior application.

In FIG. 1, reference numeral 31 denotes a light source He-Ne.
The laser, 3 is a polarizer, 4 is a sample stage that rotates around the optical axis, and has an encoder for reading the direction of the sample, and 5a is a liquid crystal display element as a sample. Reference numeral 6 denotes an analyzer which rotates around the optical axis, and includes an encoder for reading the direction of the analyzer. Reference numeral 32 denotes a light intensity detector using a photomultiplier. 9a controls the orientation of the sample table 4 and the analyzer 6, calculates the sample orientation dependence of the polarization state of the transmitted light from the intensity detected by the light intensity detector 32, and calculates the sample cell gap, twist angle, and liquid crystal. Is a computer that calculates the average tilt angle of

In the measurement in this case, two directions perpendicular to each other and perpendicular to the traveling direction of light are considered, and a component of one direction of the electric field vector of the light is defined as an S component, and a component of the direction orthogonal to the direction is defined as a P component. I do. At the time of measurement, the polarizer is set so that the S component and the P component of the incident light are linearly polarized at 1: 1.
The angle was set to 45 degrees with the component direction and the P component direction. The rotation analyzer method, which determines the polarization state of the light transmitted through the sample from the dependence of the detected light intensity on the orientation of the analyzer, was used. The measurement of the detected light intensity is 18 for every two degrees of the analyzer azimuth interval.
It measured about 0 direction.

The sample 5a used for the measurement was prepared as follows. A polyimide PI-A manufactured by Nissan Chemical Co., Ltd. is applied to glass having a width of 30 mm, a length of 40 mm, and a thickness of 1.1 mm by spin coating, dried in an oven set at 80 degrees for 15 minutes, and then set in an oven set at 250 degrees. For 60 minutes. Thereafter, the two substrates were rubbed three times at room temperature by using a rubbing roller having a diameter of 3 cm and implanted with rayon at a rotation speed of 800 rpm, a pushing length of 0.3 mm, and a roller scanning speed of 20 mm / s. The substrates were bonded to each other with a two-liquid epoxy adhesive mixed with a 5 mm spacer so that the rubbing direction of each substrate was 90 degrees, to obtain a liquid crystal element. 633n with a transition temperature of 62 degrees
Liquid crystals having a refractive index of 1.586 and 1.510 with respect to the light of m were injected into the cell at room temperature by utilizing the capillary phenomenon. After the injection portion was sealed with an epoxy-based adhesive, each cell was placed in an oven set at 90 degrees and heated for 2 hours to perform a process for homogenizing the liquid crystal orientation (isotropic process). FIG. 10 shows the measurement results of the sample orientation dependence of the polarization states Δ and ψ of the transmitted light of the sample A manufactured in such a procedure. Δ and ψ are both 2
The rotational symmetry is clearly observed.

From the measurement results, the cell gap and twist angle of Sample A were determined as follows. A cell gap d in which light having a wavelength λ is injected with a liquid crystal having a refractive index of Ne and No,
Twist angle φ, average tilt angle θ, components J11 and J12 of a 2 × 2 Jone matrix showing the optical characteristics of the liquid crystal display element when the liquid crystal element has an azimuth of 0 ° with respect to the S component of light. , J21 and J22 are J11 = sin (Φ) sin (ΦV) + cos (Φ) cos (ΦV) / V + iU
cos (Φ) sin (ΦV) / V J12 = cos (Φ) sin (ΦV) -sin (Φ) cos (ΦV) / V-iU
sin (Φ) sin (ΦV) / V J21 = −cos (Φ) sin (ΦV) + sin (Φ) cos (ΦV) / V + i
Usin (Φ) sin (ΦV) / V J22 = sin (Φ) sin (ΦV) + cos (Φ) cos (ΦV) / V-iU
cos (Φ) sin (ΦV) / V However, i is an imaginary unit, and U and V are respectively U = πd (Ne ｛1+ (Ne ² / No ² −1) sin ² θ｝)
^-1/2 -No) / λΦ V = (1 + U ² ) ^1/2

When the azimuth of the liquid crystal element has an angle A with respect to the S component direction of light, each element J of the Jone matrix of the liquid crystal element
11 (A), J12 (A), J21 (A), J22
(A) is J11 (A) = J11cos ² (A)-(J12 + J21) s
in (A) cos (A) + J22 sin ² (A) J12 (A) = J12 cos ² (A) + (J11−J22) s
in (A) cos (A) -J21 sin ² (A) J21 (A) = J21 cos ² (A) + (J11-J22) s
in (A) cos (A)-J12 sin ² (A) J22 (A) = J22 cos ² (A) + (J12 + J21) s
in (A) cos (A) + J11 sin ² (A)

In this measurement condition, since the S component and the P component enter linearly polarized light of 1: 1, the S component of the transmitted light is J11 (A) + J12 (A), and the P component is J21 (A).
+ J22 (A) with respect to S component J11 + J12 (A) with respect to phase difference Δ (A) and ratio of their absolute values | J21 (A)
+ J22 (A) | / | J11 (A) + J12 (A) | is given by an angle Ψ (A) of tanΨ (A). The values of the twist angle Φ and the cell gap d that minimize the sum of squares of the difference between the polarization states Δ (A) and Ψ (A) calculated in this way and the measured polarization states Δ and Ψ are obtained. .

Since the polarization states Δ (A) and Ψ (A) have a large nonlinearity with respect to the cell gap d and the twist angle polarization state Δ (A), ordinary non-linear methods such as the Marcut method, the fastest descent method, and the Gauss-Newton method are used. The linear least squares method does not provide a solution. Therefore, the cell gap d and the twist angle Φ are changed at fixed intervals within a fixed range, and the sum of squares of the difference between the measured values Δ (A) and Ψ (A) and the measured value is calculated. . That is, the range of the twist angles Φmin to Φmax at the interval of δ (Φmax−Φmin) / δ + 1, and the range of the cell gap dmin to dmax for each twist angle at the interval η, the condition of (dmax−dmin) / η + 1, is ｛(合計). Φm
ax−Φmin) / δ + 1｝ ｛(dmax−dmin) / η +
Δ (A) and Ψ (A) are calculated for the combination of 1｝.

From the calculated sum of squares, a combination of d1 and １1 that gives the minimum sum of squares is searched. At this time, Δ
When the twist angle and the cell gap interval for calculating (A) and Ψ (A) are larger than desired accuracy, d1-
The range from η to d1 + η is set to an interval smaller than η, for example, η /
The polarization state is calculated at 10 intervals. The same applies to the twist angle. For each cell gap, the range of Φ1-δ to Φ1 + δ is set at an interval smaller than δ, for example, at an interval of δ / 10.
The polarization state is calculated for the 21 sets, and a combination d2, Φ2 of the cell gap and the twist angle that minimizes the sum of squares of the difference between the measured value and the calculated value is searched. The above procedure is repeated until the calculated cell gap interval and twist angle interval become smaller than desired accuracy.

When the rubbing direction of the liquid crystal display device is unknown, the polarization state Δ (A), Ψ
(A) is calculated, and the rubbing direction of the sample is estimated by comparing the direction Amax or Amin that gives the maximum value or the minimum value with the direction Omax or Omin that gives the maximum or minimum value of the measured polarization states Δ and Ψ. I do. Then, the azimuth dependence of the polarization state is calculated as Δ (A−Amax + Omax).
), Ψ (A-Amax + Omax) or Δ (A-Amin
+ Omin) and Ψ (A-Amin + Omin) to obtain the sum of squares of the difference between the measured polarization state and the calculated polarization state.

In the case of sample A, the twist angle is expected to be about 90 degrees and the cell gap is assumed to be about 5 μm. Therefore, the calculation range was set to 80 to 100 degrees for the twist angle and the cell gap was set to 4 to 6 μm. At the cell gap and twist angle obtained in this way, the average tilt angle of the liquid crystal is changed at intervals of 1 degree from 0 to 5 degrees, and the residual square sum of the measured polarization state and the calculated polarization state is obtained. , The average inclination angle was 3 degrees and became a minimum. The above procedure is programmed and automatically executed in the computer 108. According to the above procedure, when the average tilt angle of the liquid crystal cell is set to 0 degree, the cell gap of the sample A is 5.13 μm.
m, the twist angle was determined to be 89.8 degrees, and the average inclination angle was determined to be 3 degrees.

[0016]

The above-mentioned prior art 1 for measuring the wavelength dependence of the transmitted light intensity and the method for measuring the confocal point both use the difference in the refractive index between the liquid crystal and the substrate. However, the twist angle, which is a factor characterizing the structure of the liquid crystal display element, cannot be determined. Further, in Conventional Example 2, which is determined from the intensity of light transmitted through the liquid crystal cell sandwiched between the polarizer and the analyzer, the twist angle cannot be obtained unless the cell gap is known.

On the other hand, in the conventional examples 2 and 3, the method of measuring the two sets of sample orientations and the orientation of the polarizer or analyzer in which the intensity of light passing through the polarizer, the sample, and the analyzer is minimized is the cell gap. And the twist angle can be determined. However, since there are a plurality of combinations of the sample orientation and the cell gap and the twist angle which give the orientation of the polarizer or the analyzer at which the light intensity is minimal, the cell gap and the twist angle of the sample are selected from these combinations. In order to determine the value, it is necessary that the value range of either the cell gap or the twist angle is known. The measurement accuracy is not easy to improve because the measurement accuracy of the azimuth of the liquid crystal element and the polarizer or the analyzer giving the minimum transmitted light intensity affects the accuracy of determining the cell gap and the twist angle. In addition, since the transmitted light of the display element is observed, it is difficult to measure a light-transmitting element such as a reflective LCD.

Further, as a method of determining the cell gap, twist angle and average inclination angle of the prior application, an in-plane rotation mechanism of the sample,
Polarizers and retarders that control the polarization state of light incident on a light source and a sample with multiple wavelengths, and a phaser, analyzer, and monochromatic light wavelength that measure the polarization state of light transmitted through the sample Similarly, in a method using a spectroscope and a photodetector, it is difficult to measure an element that does not transmit light, such as a reflective LCD.

An object of the present invention is to solve these problems and determine the in-plane distribution of the cell gap and the twist angle of the sample or the in-plane distribution of the cell gap, the twist angle and the average tilt angle of the liquid crystal at high speed and in a wide range. It is an object of the present invention to provide a method for evaluating a liquid crystal display element and an apparatus for evaluating the method, which enable the above.

[0020]

The structure of the method for evaluating a liquid crystal display element according to the present invention is such that light having a plurality of wavelengths and polarization states is kept at a constant incident angle on a display surface of a reflective liquid crystal display element as a sample. The liquid crystal display element is measured by measuring the azimuth dependence or the wavelength dependence of the intensity of light reflected from the liquid crystal display element, which is generated when the liquid crystal display element is incident and rotated in the plane of the liquid crystal display element. It is characterized in that the twist angle (twist angle) and the average tilt angle of the liquid crystal inside and the thickness of the liquid crystal layer are determined.

Further, another configuration of the method for evaluating a liquid crystal display element according to the present invention is that a parallel light having a plurality of wavelengths and polarization states spread by a beam expander on a display surface of a reflection type liquid crystal display element to be a sample is fixed. , The intensity of the light reflected by the liquid crystal display element, which is generated when the liquid crystal display element is rotated in-plane, is two-dimensionally determined. By measuring to
The twist angle (twist angle) and the average tilt angle of the liquid crystal in the liquid crystal display element and the in-plane distribution of the thickness of the liquid crystal layer are determined at high speed.

The configuration of the liquid crystal display element evaluation apparatus of the present invention is as follows.
Light having a plurality of wavelengths and polarization states is incident on the display surface of a liquid crystal display element as a sample while maintaining a constant incident angle, and light reflected from the liquid crystal display element generated when the sample is rotated in a plane. By measuring the azimuth dependency or the wavelength dependency of the intensity of the liquid crystal display element, the twist angle (twist angle) and the average tilt angle of the liquid crystal in the liquid crystal display element and the thickness of the liquid crystal layer are determined. Features.

Another configuration of the liquid crystal display element evaluation apparatus according to the present invention is such that a parallel light having a plurality of wavelengths and polarization states spread by a beam expander on a display surface of a liquid crystal display element, which is a sample, is irradiated at a predetermined incident angle. By keeping the incident and measuring the azimuth dependence or the wavelength dependence of the intensity of the light reflected from the liquid crystal display element generated when the sample is rotated in the plane and reflected by the liquid crystal display element two-dimensionally, It is characterized in that the twist angle (twist angle) and the average tilt angle of the liquid crystal in the liquid crystal display element and the in-plane distribution of the thickness of the liquid crystal layer are determined at high speed.

In these inventions, the polarization state of the parallel light incident on the reflective liquid crystal display device of the sample is one of P-polarized light and S-polarized light, and the reflected light from the liquid crystal display device is P-polarized light or S-polarized light. The reflected light from the liquid crystal display element is extracted by an analyzer, and the two-dimensional measurement of the azimuth dependence or the wavelength dependence of the intensity of the reflected light is taken by a two-dimensional CCD camera. In addition, the twist angle (twist angle) and average tilt angle of the liquid crystal in the liquid crystal display element, and the in-plane distribution of the thickness of the liquid crystal layer can be controlled over a wide range and at high speed by the sample stage moving in the in-plane direction. Can be determined.

The structure of the recording medium on which the computer program of the present invention is recorded is such that light having a plurality of wavelengths and polarization states is incident on a display surface of a liquid crystal display element serving as a sample at a constant angle of incidence, and the sample is applied to the sample. By measuring the azimuth dependence or the wavelength dependence of the intensity of light reflected from the liquid crystal display element generated when the liquid crystal display element is rotated in a plane, the twist angle (twist angle) of the liquid crystal in the liquid crystal display element is measured. And evaluating the liquid crystal display element which determines the average tilt angle and the thickness of the liquid crystal layer.

According to the structure of the present invention, monochromatic light having a certain polarization state is incident on the display surface of the liquid crystal display element, and the dependence of the reflected light intensity on the sample orientation is measured. Gap and average tilt angle can be determined at high speed and in a wide range, and by adding a mechanism to translate the sample in the plane, the in-plane distribution of the cell gap and twist angle of the sample, or the cell gap, The in-plane distribution of the twist angle and the average tilt angle of the liquid crystal can be determined at high speed over a wide range.

[0027]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In FIG. 1, 1 is a white light source, 2
Is a beam expander, 3 is a polarizer, 4 is a sample stage, which is a sample stage that rotates around the optical axis, and includes an encoder 10 for reading a sample direction and a monitor 11.
5 is a liquid crystal display element of the sample, 6 is an analyzer, 7 is an imaging lens, 8 is a two-dimensional CCD camera, 9 is a sample azimuth dependency calculated from the reflected light intensity detected by the two-dimensional CCD camera 8, It is a computer for calculating a cell gap, a twist angle, and an average tilt angle of a liquid crystal of a sample.

In this measurement, two directions perpendicular to each other and perpendicular to the traveling direction of the light are considered, and a component of one direction of the electric field vector of the light is defined as an S component, and a component of the direction orthogonal to the direction is defined as a P component. At the time of measurement, the incident light was used as the S component, and after entering the sample, a polarizer and an analyzer were provided so that the reflected S component light could be detected. The detection light intensity was measured in six directions at intervals of 30 degrees between analyzer directions.

The sample A (5) used for the measurement was prepared as follows. Width 30mm, length 40mm, thickness 1.
A polyimide PI-A manufactured by Nissan Chemical Co., Ltd. is applied to a color filter and a TFT substrate by spin coating, dried in an oven set at 80 degrees for 15 minutes, and then baked by heating in an oven set at 250 degrees for 60 minutes. did. After that, the two substrates were implanted with rayon at room temperature and had a diameter of 3
cm using a rubbing roller of 800 cm,
Pushing length 0.3mm, roller scanning speed 20mm / s
Rubbed three times. The substrates were bonded to each other with a two-liquid epoxy-based adhesive mixed with a 5 μm spacer so that the rubbing direction of each substrate was 90 degrees, to form a liquid crystal cell.
Liquid crystals having a transition temperature of 62 degrees and a refractive index of 1.586 and 1.510 with respect to light of 633 nm were injected into the cell at room temperature by utilizing the capillary phenomenon.

After sealing the injection portion with an epoxy adhesive,
Each cell was placed in an oven set at 90 degrees and heated for 2 hours to perform a treatment (isotropic treatment) for homogenizing the liquid crystal alignment. FIG. 2 shows the measurement results of the sample azimuth dependence of the reflected light intensity of the sample A manufactured in such a procedure.

From the measurement results, the cell gap and twist angle of Sample A were determined as follows. The optical characteristics of the liquid crystal display element when the light having the wavelength λ is transmitted through a liquid crystal element having a cell gap d, a twist angle Φ, an average inclination angle θ, and an azimuth angle of 0 degrees with respect to the S component of light when a liquid crystal having a refractive index Ne is injected. The components J11, J12 of the 2-by-2 Jones matrix showing the characteristics,
J21 and J22 are calculated as follows: J11 = sin (Φ) sin (Φ + cos (Φ) cos (ΦV) / V + iU
cos (Φ) sin (ΦV) / V J12 = cos (Φ) sin (ΦV) -sin (Φ) cos (ΦV) / V-i
Usin () sin (ΦV) / V J21 = -cos (Φ) sin (ΦV) + sin (Φ) cos (ΦV) / V +
iUsin (Φ) sin (Φ) / V J22 = sin (Φ) sin (ΦV) + cos (Φ) cos (ΦV) / Vi
Ucos (Φ) sin (ΦV) / V Where i is an imaginary unit, and U and V are respectively U = πd (Ne ｛1+ (Ne ² / No ² -1) sin ² θ｝ ^-1/2
−No) / λΦ V = (1 + U ² ) ^1/2

When the azimuth of the liquid crystal element has an angle A with respect to the S component direction of light, each element J of the Jone matrix of the liquid crystal element
(A) is J11 (A) = J11cos ² (A)-(J12 + J21) sin (A)
cos (A) + J22 sin ² (A) J12 (A) = J12 cos ² (A) + (J11-J22) sin
(A) cos (A) -J21 sin ² (A) J21 (A) = J21 cos ² (A) + (J11-J22) sin
(A) cos (A)-J12 sin ² (A) J22 (A) = J22 cos ² (A) + (J12 + J21) sin
(A) cos (A) + J11sin ² (A) In the case of a reflective display element, the light propagation matrix Ψ is expressed as ΨAf = J ・ R ・ J−1ΨΨ where Ψ is before incidence, ΨAf is after reflection and R is the matrix of the reflector. The light propagation matrix Ψ is represented by (P polarization component, S polarization component), and the square of the matrix element is the reflected light intensity.
This reflected light intensity may be calculated from the P-polarized light component of ΨAf.

Adaptation is made to minimize the sum of squares of the difference between the intensity calculated in this way and the measured intensity,
The values of the twist angle Φ, the cell gap d, and the average inclination angle θ are obtained. In the case of FIG. 3, a certain area (region) is determined, and within that range, the sum of the reflected light intensities for all wavelengths is measured, and the light intensity in the sample orientation obtained in this way and the light intensity obtained from the calculation are calculated. And Here, the twist angle Φ
Is 70 degrees, the cell gap d is 3 μm, and the average inclination angle θ is 3
Degree.

[Embodiment 2] FIG. 3 is a block diagram of an apparatus as another embodiment of the present invention. In FIG. 3, FIG.
The difference is that a grating 12 is added to the above configuration. That is, the reflected light from the analyzer 6 and the imaging lens 7 is dispersed into each wavelength by the grating 12 and input to the two-dimensional CCD camera 8. Also in this configuration, the computer 9a calculates the sample orientation dependency from the reflected light intensity detected by the two-dimensional CCD camera 8, and calculates the cell gap, the twist angle, and the average tilt angle of the liquid crystal of the sample 5. It is a computer.

In this case, at the time of measurement, two directions perpendicular to each other and perpendicular to the traveling direction of light are considered, and a component of one direction of the electric field vector of the light is defined as an S component, and a component of the direction orthogonal to the direction is defined as a P component. I do. At the time of measurement, the incident light was used as the S component, and after entering the sample, a polarizer and an analyzer were provided so that the reflected S component light could be detected. The detection light intensity was measured for 18 directions at intervals of 10 degrees between analyzer directions.

The sample B used for the measurement was prepared as follows. A polyimide PI-C manufactured by Nissan Chemical Co., Ltd. is applied to a color filter having a width of 30 mm, a length of 40 mm, and a thickness of 1.1 mm and a TFT substrate by spin coating, dried in an oven set at 80 degrees for 15 minutes, and then heated to 250 degrees. It was baked by heating in a set oven for 60 minutes. afterwards,
The two substrates were rubbed three times at room temperature using a rubbing roller having a diameter of 3 cm and a rayon implanted at a rotation speed of 600 rpm, a pushing length of 0.3 mm, and a roller scanning speed of 20 mm / s. The substrates were bonded to each other with a two-liquid epoxy-based adhesive mixed with a 5 μm spacer so that the rubbing direction of each substrate was 80 °, thereby forming a liquid crystal cell.

Liquid crystals having a transition temperature of 62 degrees and a refractive index of 1.586 and 1.510 for light of 633 nm were injected into the cell at room temperature by utilizing the capillary phenomenon. After the injection portion was sealed with an epoxy-based adhesive, the cells were placed in an oven set at 90 degrees and heated for 2 hours to perform a process for isolating the liquid crystal orientation (isotropic process). FIG. 4 shows the measurement results of the sample azimuth dependence of the reflected light intensity at a wavelength of 633 nm of the sample B manufactured in such a procedure. From this measurement result, values of the twist angle Φ, the cell gap d, and the average inclination angle θ are obtained in the same manner as in the first embodiment.

[Third Embodiment] As a third embodiment of the present invention, the configuration of the apparatus is the same as that of FIG. Also in this case, the computer 9 is a computer for calculating the sample orientation dependency from the intensity of the reflected light detected by the CCD camera 8, and calculating the cell gap, twist angle, and average tilt angle of the liquid crystal of the sample. At the time of measurement, two directions perpendicular to each other and perpendicular to the traveling direction of light are considered, and a component of one direction of the electric field vector of the light is defined as an S component, and a component of the direction orthogonal to the direction is defined as a P component. At the time of measurement, the incident light is P component and S component.
In order for the components to be 1: 1 and after entering the sample,
A polarizer and an analyzer were provided so that the reflected P component and S component could detect 1: 1 light. The detection light intensity was measured for 18 directions at intervals of 10 degrees between analyzer directions.

The sample C used for the measurement was prepared as follows. A polyimide PI-A manufactured by Nissan Chemical Co., Ltd. is applied to a color filter and a TFT substrate having a width of 30 mm, a length of 40 mm, and a thickness of 1.1 mm by spin coating, dried in an oven set at 80 degrees for 15 minutes, and then heated to 250 degrees. It was baked by heating in a set oven for 60 minutes. afterwards,
The two substrates were rubbed three times at room temperature using a rubbing roller of 3 cm in diameter with rayon implanted at a rotation speed of 900 rpm, a pushing length of 0.3 mm, and a roller scanning speed of 20 mm / s. Rubbing direction of each substrate is 7
The substrates were bonded to each other with a two-part epoxy adhesive mixed with a 5 μm spacer so as to be at 0 ° to form a liquid crystal cell.

A liquid crystal having a transition temperature of 62 degrees and a refractive index of 1.586 and 1.510 with respect to light of 633 nm was injected into the cell at room temperature by utilizing the capillary phenomenon. After the injection portion was sealed with an epoxy-based adhesive, each cell was placed in an oven set at 90 degrees and heated for 2 hours to perform a process for homogenizing the liquid crystal orientation (isotropic process). A wavelength of 450 nm (blue) and a wavelength of 533 nm of the sample C manufactured by such a procedure.
FIG. 5 shows the measurement results of the sample orientation dependence of the reflected light intensity at (green) and 614 nm (red) wavelengths. From this measurement result, values of the twist angle Φ, the cell gap d, and the average inclination angle θ are obtained in the same manner as in the first embodiment.

[Embodiment 4] The structure of a fourth embodiment of the present invention is the same as that of FIG.
As a, a sample stage provided with a rotation mechanism and a parallel movement mechanism shown in the perspective view of FIG. 5 is used. In FIG. 5, 21 is a rotary stage, 22 is a parallel moving mechanism for adjusting the height of the sample 5, 23 is a sample holding table on which the sample 5 is directly held, and 24 and 25 are parallel moving stages whose moving directions are orthogonal to each other. , 26 are mechanisms for adjusting the tilt angle of the sample holder 22, and the encoder 10 for reading the sample direction.
And a monitor 11.

Also in this case, since there is a sample stage 4a having a rotation mechanism and a parallel movement mechanism, the movement of the sample 5 is easy, and the computer 9 determines the sample azimuth from the reflected light intensity detected from the two-dimensional CCD camera 8. By calculating the dependence, the cell gap, twist angle, and average tilt angle of the liquid crystal of the sample can be easily calculated.

In this measurement, two directions perpendicular to each other and perpendicular to the traveling direction of light are considered, and a component of one direction of the electric field vector of the light is defined as an S component, and a component of the direction orthogonal to the direction is defined as a P component. At the time of the measurement, the polarizer 3 and the analyzer 6 were placed so that the incident light was the S component, and after being incident on the sample, the reflected S component light could be detected. The detection light intensity was measured for 18 directions at intervals of 10 degrees between analyzer directions. A flowchart for this procedure is shown in FIG.

In this measurement, first, in step S1, measurement conditions are input, and at a certain measurement position (step S2), parallel light is input / output to / from the polarizer 3 and the analyzer 6 (step S3).
The rotation direction is fixed (step S4), and measurement of the light intensity is started (step S5). Here, the direction of the sample 5 is rotated to measure the intensity in each direction. When the measurement in each direction is completed (step S6), the parameters of the cell gap, twist angle, and average tilt angle of the liquid crystal at that position are calculated by the computer 9a. (Step S7), the sample 5 is moved to the next position, and Steps S2 to S6 are repeated. When the measurement at all positions is completed (Step S8), the measurement ends.

The sample D used for the measurement was prepared as follows. A polyimide PI-A manufactured by Nissan Chemical Co., Ltd. is applied to a color filter and a TFT substrate having a width of 30 mm, a length of 40 mm, and a thickness of 1.1 mm by spin coating, dried in an oven set at 75 degrees for 15 minutes, and then heated to 250 degrees. It was baked by heating in a set oven for 60 minutes. afterwards,
The two substrates were rubbed three times at room temperature using a rubbing roller having a diameter of 3 cm in which rayon was implanted at a rotation speed of 800 rpm, a pushing length of 0.3 mm, and a roller scanning speed of 20 mm / s. The substrates were bonded to each other with a two-liquid epoxy adhesive mixed with a 3 μm spacer so that the rubbing direction of each substrate was 70 ° to form a liquid crystal cell. At this time, the pressure on the lower side of the cell was 1.5 times higher than that on the upper side.

A liquid crystal having a transition temperature of 62 degrees and a refractive index of 1.586 and 1.510 for light of 633 nm was injected into the cell at room temperature by utilizing the capillary phenomenon. After the injection portion was sealed with an epoxy-based adhesive, each cell was placed in an oven set at 90 degrees and heated for 2 hours to perform a process for homogenizing the liquid crystal orientation (isotropic process). From the measurement results of the sample azimuth dependence of the reflected light intensity at a wavelength of 633 nm of the sample D manufactured in such a procedure, the values of the twist angle Φ, the cell gap d, and the average inclination angle θ were obtained in the same manner as in the first embodiment. The in-plane distribution is obtained as shown in FIGS. 8 (a) to 8 (c).

[0047]

As described above, according to the present invention, monochromatic light having a certain polarization state is incident on the display surface of a liquid crystal display element, and the dependence of the reflected light intensity on the sample orientation is measured. The twist angle, the cell gap, and the average inclination angle can be determined at high speed and in a wide range.

Further, by adding a mechanism for moving the sample in parallel within the plane, the in-plane distribution of the cell gap and the twist angle of the specimen or the in-plane distribution of the cell gap, the twist angle, and the average tilt angle of the liquid crystal can be increased at a high speed. In addition, there is an effect that can be determined in a wide range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a sample azimuth dependency of a transmitted light intensity of a sample A of FIG. 1 at every 30 ° in-plane azimuth.

FIG. 3 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a calculated value (solid line) of the sample azimuth dependence of the reflected light intensity of the sample B in FIG. 2 and a measurement result thereof.

FIG. 5 shows each wavelength (450 nm, 533 nm,
614 nm), and a characteristic diagram showing a calculated value (solid line) of the dependence of the reflected light intensity on the sample orientation (solid line) and a measurement result thereof.

FIG. 6 is a perspective view showing a configuration of a sample stage 4 of FIG. 2;

FIG. 7 is a flowchart of a program for obtaining a cell gap, a twist angle, and an average inclination angle in FIG. 2;

FIGS. 8A to 8C are pattern diagrams showing measurement examples of distributions of a cell gap, a twist angle, and an average inclination angle of the sample D of FIG. 2;

FIG. 9 is a block diagram showing a configuration of a measuring device of the prior application.

10 is a characteristic diagram showing the azimuth dependence of the polarization state of the transmitted light of the sample according to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 White light source 2 Beam expander 3 Polarizer 4 Sample stage 5 Liquid crystal display element 5a Sample 6 Analyzer 7 Imaging lens 8 Two-dimensional CCD camera 9 Computer 10 Encoder 11 Monitor 12 Grating 22 Parallel movement mechanism 23 Sample holder 21 Rotation stage 24, 25 translation stage 26 tilt angle adjustment mechanism

Continued on front page F term (reference) 2F065 AA22 AA30 AA31 CC25 DD06 GG01 HH15 JJ03 JJ26 LL09 LL21 LL33 LL34 MM04 QQ17 QQ26 QQ29 2H088 FA12 FA30 HA03 JA05 KA02 KA07 KA11 KA29 MA16

Claims (12)

[Claims] 1. A liquid crystal display device having a plurality of wavelengths and polarization states incident on a display surface of a reflective liquid crystal display device as a sample while maintaining a predetermined incident angle, and rotating the liquid crystal display device in a plane. By measuring the azimuth dependence or the wavelength dependence of the intensity of the light reflected from the liquid crystal display device, the twist angle (twist angle), the average tilt angle, and the liquid crystal of the liquid crystal in the liquid crystal display device are measured. A method for evaluating a liquid crystal display element, comprising determining a thickness of a layer. 2. A parallel light having a plurality of wavelengths and a polarization state spread by a beam expander is incident on a display surface of a reflection type liquid crystal display element as a sample at a constant incident angle, and the liquid crystal display element is irradiated with the light. By measuring two-dimensionally the azimuth dependence or the wavelength dependence of the intensity of the light reflected by the liquid crystal display element generated when the liquid crystal display element is rotated in the plane, the liquid crystal in the liquid crystal display element is measured. A liquid crystal display element evaluation method, wherein a twist angle (twist angle), an average inclination angle, and an in-plane distribution of a thickness of a liquid crystal layer are determined at high speed. 3. The polarization state of parallel light incident on the reflective liquid crystal display device of the sample is one of P-polarized light and S-polarized light, and the reflected light from the liquid crystal display device is a P-polarized light or an S-polarized light component. 3. The method for evaluating a liquid crystal display device according to claim 1 or 2. 4. The method according to claim 1, wherein the reflected light from the liquid crystal display element is extracted by an analyzer, and the two-dimensional measurement of the azimuth dependence or the wavelength dependence of the intensity of the reflected light is performed by photographing with a two-dimensional CCD camera. 3. The method for evaluating a liquid crystal display element according to 3. 5. The twist angle (twist angle) and average tilt angle of liquid crystal in a liquid crystal display element, and the in-plane distribution of the thickness of a liquid crystal layer are determined in a wide range and at high speed by a sample stage moving in the in-plane direction. 5. The method according to claim 2, wherein
The liquid crystal display element evaluation method described in the above. 6. A liquid crystal display device which is generated when light having a plurality of wavelengths and polarization states is incident on a display surface of a liquid crystal display device as a sample while maintaining a predetermined incident angle, and the sample is rotated in a plane. By measuring the azimuth dependence or the wavelength dependence of the intensity of light reflected from the liquid crystal display element, the twist angle (twist angle) and average tilt angle of the liquid crystal in the liquid crystal display element, and the thickness of the liquid crystal layer A liquid crystal display element evaluation device characterized by determining: 7. A parallel light having a plurality of wavelengths and a polarization state spread by a beam expander at a constant angle of incidence is incident on a display surface of a liquid crystal display element as a sample, and the sample is rotated in a plane. The two-dimensional measurement of the azimuth dependence or the wavelength dependence of the intensity of the light generated by the liquid crystal display element and reflected by the liquid crystal display element is performed to determine the twist angle (twist angle) of the liquid crystal in the liquid crystal display element. ), The average tilt angle and the in-plane distribution of the thickness of the liquid crystal layer are determined at high speed. 8. The polarization state of parallel light incident on a reflective liquid crystal display device of a sample is one of P-polarized light and S-polarized light, and the reflected light from the liquid crystal display device is a P-polarized light or S-polarized light component. The liquid crystal display element evaluation device according to claim 6 or 7. 9. The reflected light from the liquid crystal display element is extracted by the analyzer, and the two-dimensional measurement of the azimuth dependence or the wavelength dependence of the intensity of the reflected light is performed by photographing with a two-dimensional CCD camera. The liquid crystal display element evaluation device according to the above. 10. A sample which measures a twist angle (twist angle) and an average tilt angle of liquid crystal in a liquid crystal display element and an in-plane distribution of a thickness of a liquid crystal layer, and moves in a vertical and horizontal height direction in the measurement plane. 10. The liquid crystal display element evaluation device according to claim 7, further comprising a stage. 11. A liquid crystal display element generated when light having a plurality of wavelengths and polarization states is incident on a display surface of a liquid crystal display element serving as a sample while maintaining a constant incident angle, and the sample is rotated in a plane. By measuring the azimuth dependence or the wavelength dependence of the intensity of the light reflected from the liquid crystal display element, the twist angle (twist angle) and the average tilt angle of the liquid crystal in the liquid crystal display element, and the thickness of the liquid crystal layer are determined. A recording medium on which a computer program for evaluating a liquid crystal display element to be determined is recorded. 12. A recording medium on which a computer program for evaluating a liquid crystal display element by the liquid crystal display element evaluation method according to claim 2 is recorded.