JP2003066400A - Evaluating method and evaluating apparatus for liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel evaluating method and evaluating apparatus for a liquid crystal display panel which are capable of acquiring information relating to a liquid crystal layer with higher accuracy than by the conventional method. SOLUTION: The thickness of the liquid crystal layer is measured from the prismatic spectra of the transmitted light made incident on the liquid crystal panel 10 and emitted from the liquid crystal panel 10.

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 liquid crystal panel, and more particularly to a manufacturing technique suitable for examining the thickness of a liquid crystal layer provided on a semi-transmissive or transmissive liquid crystal panel. .

[0002]

2. Description of the Related Art Generally, a liquid crystal panel is formed by bonding two substrates and injecting liquid crystal between the two substrates. An electrode pattern for applying a voltage to the liquid crystal layer is formed on each of these two substrates. When a liquid crystal display device is constructed using this liquid crystal panel, the thickness of the liquid crystal layer (cell gap) has a large effect on the display characteristics. It is very important to form a uniform thickness over the entire length.

Therefore, in the conventional manufacturing process of a liquid crystal display device, an inspection is performed to evaluate the thickness and uniformity of the liquid crystal layer after the liquid crystal panel is constructed. Further, if foreign matter enters the inside of the liquid crystal layer, a display defect occurs. Therefore, it may be inspected whether there is any foreign matter inside the liquid crystal layer.

Here, the above-mentioned inspection may be carried out simply to know whether the manufactured liquid crystal panel is good or defective, and to reject defective products. Further, the thickness of the liquid crystal layer of the manufactured liquid crystal panel, etc. This is done to obtain the characteristic values of the liquid crystal panel, specify the degree of quality of the liquid crystal panel, classify, and feed back the results to obtain management data for fine adjustment of the manufacturing conditions of the manufacturing line. It is widely used as an act for evaluating a liquid crystal panel, such as being sometimes referred to.

In the conventional manufacturing process of a liquid crystal display device, when inspecting a liquid crystal panel having a liquid crystal layer, annular light is illuminated by a ring-shaped light source, and light emitted from the light source is linearly polarized by a polarizing plate. Then, the linearly polarized light is radiated to the liquid crystal panel, the transmitted light is passed through the polarizing plate, and finally the transmitted light is analyzed by a colorimeter (other CCD camera, Photomul, or spectrometer may be used). The method may be adopted.

Further, light emitted from a light source which can be regarded as a point light source is applied to a liquid crystal panel through a polarizing plate, and the transmitted light is measured by a colorimeter obliquely installed through the polarizing plate. There is also a method of detecting.

In the above method, the direction of the polarization transmission axis of the polarizing plate on the light incident side and the direction of the polarization transmission axis of the polarizing plate on the light detecting side with respect to the optical axis have an appropriate relationship, for example, Since the hue of the detection light changes according to the thickness of the liquid crystal layer when installed so that the relationship has an angle difference of 20 to 60 degrees, the liquid crystal is based on the hue of the image captured by the colorimeter. It is inspected for abnormal layer thickness and the presence of foreign matter.

[0008]

However, in the above-mentioned conventional liquid crystal panel inspecting method, the cell thickness is calculated by the change in hue. However, there is a film provided on the liquid crystal panel, for example, a film such as a color filter. By doing so, there is a problem that an accurate value cannot be obtained.

Therefore, the present invention is to solve the above-mentioned problems, and an object thereof is to provide a new liquid crystal panel evaluation method and evaluation device which can obtain information on a liquid crystal layer more accurately than before. It is in.

[0010]

In order to solve the above problems, a liquid crystal panel evaluation method of the present invention is a liquid crystal panel evaluation method for optically evaluating a liquid crystal panel. Then, polarized light in a predetermined state is made incident, and panel evaluation is performed based on the spectral characteristics of the detection light obtained from the transmitted light that has passed through the liquid crystal panel.

According to such a configuration of the present invention, the characteristics of the liquid crystal layer, such as the thickness of the liquid crystal layer and the liquid crystal layer, are determined based on the spectral characteristic of the detected light, for example, the wavelength or frequency position of the extreme value of the spectral spectrum. The panel evaluation can be performed by requesting confirmation of the retardation Δn · d, the presence or absence of foreign matter in the liquid crystal layer, and the like. That is, since the extreme wavelength position and frequency position of the spectrum of the detection light are hardly affected by the hue of the detection light, the hue other than the thickness of the liquid crystal layer such as a color liquid crystal panel having a color filter is affected. It is possible to measure the thickness of the liquid crystal layer without any problem even for a liquid crystal panel having a structure that gives

Another method of evaluating a liquid crystal panel of the present invention is a second substrate provided with one substrate provided with a first electrode, a second electrode facing the first electrode and a reflective layer having an opening. A liquid crystal panel evaluation method for optically evaluating a liquid crystal panel in which a liquid crystal layer is sandwiched between a substrate, wherein polarized light in a predetermined state is incident on the liquid crystal panel from the first substrate side, The panel evaluation is performed based on the spectral characteristics of the detection light obtained from the transmitted light that has passed through the first substrate, the first electrode, the liquid crystal layer, the second electrode, the opening of the reflective layer, and the second substrate. It is characterized by

According to such a configuration of the present invention, the characteristics of the liquid crystal layer, for example, the thickness of the liquid crystal layer, the thickness of the liquid crystal layer, based on the spectral characteristics of the detected light, for example, the extreme wavelength or frequency position of the spectral spectrum. The semi-transmissive-semi-reflective liquid crystal panel can be evaluated by determining the retardation Δn · d, the presence of foreign matter in the liquid crystal layer, and the like. That is,
Since the wavelength position and frequency position of the extremum of the spectrum of the detection light are hardly affected by the hue of the detection light,
It is possible to measure the thickness of the liquid crystal layer without any problem even for a liquid crystal panel having a structure that affects hue other than the thickness of the liquid crystal layer, such as a color liquid crystal panel having a color filter.

Further, the polarized light is mainly composed of a polarized light component having a first vibrating plane, and the detected light is mainly a polarized light component having the first vibrating plane among the transmitted light. It is characterized by being a thing. As described above, in the present invention, the polarized light is mainly composed of the polarized light component having the first vibrating surface, and the detection light is mainly the polarized light having the first vibrating surface in the transmitted light. It is desirable that the components are reduced.

Further, the detection light is characterized in that a polarization component mainly having a second vibrating surface substantially orthogonal to the first vibrating surface is extracted from the transmitted light.
As described above, in the present invention, the detected light is mainly the transmitted light and the second light that is substantially orthogonal to the first vibrating surface.
It is desirable that the polarized component having the vibrating plane is extracted.

Further, the thickness of the liquid crystal layer is obtained based on the spectral characteristic of the detection light. In this way, the thickness of the liquid crystal layer can be obtained.

Further, the thickness of the liquid crystal layer is obtained based on the wavelength or frequency position of the extreme value of the spectrum of the detection light. Thus, it is desirable to determine the thickness of the liquid crystal layer based on the wavelength or frequency position of the extreme value of the spectrum of the detection light. According to this means, the wavelength position and the frequency position of the extremum of the spectrum of the detection light are hardly affected by the hue of the detection light. Therefore, except for the thickness of the liquid crystal layer, such as a color liquid crystal panel having a color filter. It is possible to measure the thickness of the liquid crystal layer even for a liquid crystal panel having a structure that affects the hue.

Further, it is characterized in that foreign matter in the liquid crystal layer is examined based on the spectral characteristic of the detection light. In this way, it is possible to inspect foreign matter in the liquid crystal layer (including foreign matter adhered to the inner surface of the substrate of the liquid crystal panel).

A liquid crystal panel evaluation device of the present invention is a liquid crystal panel evaluation device for optically evaluating a liquid crystal panel, and comprises polarized light irradiation means for irradiating the liquid crystal panel with polarized light in a predetermined state, A detecting means for obtaining detection light from the transmitted light which has passed through the liquid crystal panel, a light detecting means for detecting the detection light, and means for obtaining the characteristic of the liquid crystal layer based on the spectral characteristic of the detection light. It is characterized by having.

According to such a configuration of the present invention, the characteristics of the liquid crystal layer, such as the thickness of the liquid crystal layer and the liquid crystal layer, are determined based on the spectral characteristics of the detected light, for example, the extreme wavelength or frequency position of the spectral spectrum. The panel evaluation can be performed by requesting confirmation of the retardation Δn · d, the presence or absence of foreign matter in the liquid crystal layer, and the like. That is, since the extreme wavelength position and frequency position of the spectrum of the detection light are hardly affected by the hue of the detection light, the hue other than the thickness of the liquid crystal layer such as a color liquid crystal panel having a color filter is affected. It is possible to measure the thickness of the liquid crystal layer without any problem even for a liquid crystal panel having a structure that gives

Another liquid crystal panel evaluation apparatus of the present invention is a liquid crystal panel evaluation apparatus for optically evaluating a liquid crystal panel, wherein linearly polarized light having a first vibrating surface is applied to the liquid crystal panel. Polarized light irradiating means for irradiating the liquid crystal panel, light detecting means for reducing the polarized light component having the first vibrating surface of the light passing through the liquid crystal panel to obtain detection light, and light for detecting the detection light. It is characterized by comprising a detecting means and a means for obtaining the characteristic of the liquid crystal layer based on the spectral characteristic of the detected light.

According to such a configuration of the present invention, the characteristics of the liquid crystal layer, for example, the thickness of the liquid crystal layer, the thickness of the liquid crystal layer, based on the spectral characteristics of the detected light, for example, the extreme wavelength or frequency position of the spectral spectrum. The semi-transmissive-semi-reflective liquid crystal panel can be evaluated by determining the retardation Δn · d, the presence of foreign matter in the liquid crystal layer, and the like. That is,
Since the wavelength position and frequency position of the extremum of the spectrum of the detection light are hardly affected by the hue of the detection light,
It is possible to measure the thickness of the liquid crystal layer without any problem even for a liquid crystal panel having a structure that affects hue other than the thickness of the liquid crystal layer, such as a color liquid crystal panel having a color filter.

The polarized light irradiating means has a light source and a polarizing means for obtaining the polarized light from the light emitted from the light source.

Further, the polarization transmission axis of the polarization means and the polarization absorption axis of the light detection means are substantially orthogonal to each other with respect to the optical axis.

The characteristic of the liquid crystal layer is the thickness of the liquid crystal layer.

The means for determining the thickness of the liquid crystal layer is
It is characterized in that the thickness of the liquid crystal layer is derived based on the wavelength or frequency position of the extreme value of the spectrum of the detection light. Thus, it is desirable to determine the thickness of the liquid crystal layer based on the wavelength or frequency position of the extreme value of the spectrum of the detection light. According to this means, the wavelength position and the frequency position of the extremum of the spectrum of the detection light are hardly affected by the hue of the detection light. Therefore, except for the thickness of the liquid crystal layer, such as a color liquid crystal panel having a color filter. It is possible to measure the thickness of the liquid crystal layer even for a liquid crystal panel having a structure that affects the hue.

Further, it is characterized in that it is provided with means for indicating the presence or absence of foreign matter in the liquid crystal layer based on the detection light. In this way, it is possible to inspect foreign matter in the liquid crystal layer (including foreign matter adhered to the inner surface of the substrate of the liquid crystal panel).

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of a liquid crystal panel evaluation method and evaluation apparatus according to the present invention will be described in detail with reference to the accompanying drawings. The liquid crystal panel evaluation method and evaluation apparatus of the present invention are used for evaluation of transmissive or semi-transmissive / semi-reflective liquid crystal panels.

(First Embodiment) FIG. 1 is a schematic configuration diagram schematically showing the configuration of a first embodiment of an evaluation apparatus used in the liquid crystal panel evaluation method according to the present invention.

The evaluation device 20 of the present embodiment has a halogen lamp, an L lamp, and an L lamp above the base 21 for mounting the liquid crystal panel 10.
A light source 22 including an ED (light emitting diode), a CFL (cold cathode tube), and a light guide 23 including an optical fiber;
An incident optical system having a condenser 24 formed of a condenser lens or the like provided at the tip of the light guide path 23, and a polarizing plate 25 used as a polarizer arranged in front of the condenser 24 is provided. .

Below the base 21, a polarizing plate 2 used as an analyzer is provided so as to face the incident optical system.
6, a condenser 27 formed of a condenser lens or the like arranged in front of the polarizing plate 26, a light guide 28 formed of an optical fiber or the like connected to the condenser 27, and connected to the light guide 28. And a photodetector 29 including a spectroscope and a spectroscopic unit.

The detection data obtained by the photodetector 29 is sent to the evaluation processing section 30. The evaluation processing section 30 preferably has an arithmetic processing function of the above detection data, and in particular, is configured to perform arithmetic processing based on an operation program such as MPU (microprocessor unit). Is desirable.

The base 21 is constructed so that it can be moved in a direction orthogonal to the plane of the drawing by a drive mechanism 31, for example.
On the other hand, at least a part of the incident optical system and the detection optical system (for example, the condenser 24, the polarizing plate 25, the polarizing plate 26, and the condenser 27) is configured to be movable in the lateral direction in the drawing by the driving mechanism 32, for example. Has been done. Therefore, by the drive mechanisms 31 and 32, the incident optical system and the detection optical system, and the liquid crystal panel 10 mounted on the base 21 can be freely moved relative to each other on a virtual plane parallel to the panel surface of the liquid crystal panel 10. It can be moved. It should be noted that by configuring at least one of the incident optical system and the detection optical system and the base 21 to be appropriately movable, the drive mechanisms 31 and 3 described above are provided.
Various drive mechanisms functionally equivalent to 2 can be configured. The base 21 has a frame shape having a through hole 21a, and an inner edge portion of the base 21 supports an outer edge portion of the liquid crystal panel.

FIG. 2 schematically shows an optical path when the liquid crystal panel 10 is evaluated by the evaluation device 20 of this embodiment. Here, the case where the liquid crystal panel 10 is a monochrome transflective liquid crystal panel will be described. The liquid crystal panel 10 includes a first substrate 10b and a second substrate 1
0c, a sealing material 10d for sticking these substrates together, and a liquid crystal layer 10a sandwiched in a space formed by both substrates 10b and 10c and a sealing agent 10d. First
A counter transparent electrode 10e as a first electrode is formed on the substrate 10b.
Is provided on the second substrate 10c, and a reflective layer 11a made of Al or the like is provided on the second substrate 10c and I provided on the reflective layer 11a for each pixel.
A transparent electrode 11b as a second electrode made of TO or the like is provided. Further, the reflective layer 11a has openings 1 for each pixel.
1c is provided. A liquid crystal device incorporating such a liquid crystal panel functions as a transflective liquid crystal device. That is, when there is sufficient external light, the reflective layer 11
External light is reflected by a, and the reflected light functions as a reflection type for displaying. On the other hand, if the outside light is insufficient,
Light emitted from a backlight incorporated so as to be positioned on the side of the second substrate 10c when used as a liquid crystal device passes through the second substrate 10c and the opening 11c of the reflective layer 11a, and the transparent electrode 11b and the liquid crystal. Layer 10a, counter transparent electrode 10
e, it functions as a transmissive type display is performed by passing through the first substrate 10b.

In the above-mentioned incident optical system, the polarizing plate 25 has a polarization transmission axis parallel to a predetermined direction (for example, a plane orthogonal to the optical axis, and a direction P intersecting the plane including the optical axes of the incident light and the emitted light). 25t, and a polarization absorption axis 25a parallel to a plane orthogonal to the optical axis and a direction orthogonal to the above predetermined direction (for example, the direction P and the direction S orthogonal to the optical axis). By transmitting through the polarizing plate 25, linearly polarized light L having a vibrating surface including the direction of the polarization transmission axis 25t.
i is formed and enters the liquid crystal panel 10 at an incident angle θi.

On the other hand, the above-mentioned detection optical system is set so as to detect the transmitted light of the linearly polarized light Li which is incident at the incident angle θi, and the emission angle θo substantially equal to the incident angle θi.
Thus, the transmitted light emitted from the liquid crystal panel 10 enters the polarizing plate 26 and is finally guided to the photodetector 29. The polarization plate 26 is the polarization transmission axis 25 of the polarization plate 25.
It has a polarization absorption axis 26a parallel to t with respect to the optical path, and a polarization transmission axis 26t orthogonal to the polarization transmission axis 25t of the polarizing plate 25 with respect to the optical path.

When the above linearly polarized light Li enters from the side of the first substrate 10b of the liquid crystal panel 10, the first substrate 10b, the counter transparent electrode 10e, the liquid crystal layer 10a, the transparent electrode 11b, the opening 11c of the reflective layer 11a, and the second layer. Passing through the substrate 10c,
It becomes the outgoing polarized light Lt.

In the detection optical system, the outgoing polarized light Lt enters the polarizing plate 26. At this time, the outgoing polarized light Lt passes through the liquid crystal layer 10a, whereby a predetermined retardation of the liquid crystal layer 10a (optical anisotropy Δn of liquid crystal molecules in the liquid crystal layer 10a and a thickness d of the liquid crystal layer 10a) is obtained. Product) changes the polarization state of the linearly polarized light Li.
The polarized light is different from (for example, elliptically polarized light). Therefore, of the outgoing polarized light Lt, the polarization transmission axis 26t of the polarizing plate 26
Polarization components different from are absorbed by the polarizing plate 26 having the polarization absorption axis 26a. On the other hand, of the outgoing polarized light Lt, a polarized component vibrating in the direction of the polarization transmission axis 26t of the polarizing plate 26 passes through the polarizing plate 26 and is detected by the photodetector 29 as detection light Lo.

The detection light Lo has a light intensity according to the retardation Δn · d of the liquid crystal layer 10a, or a hue and a dispersion spectrum according to the color dispersion characteristic of the retardation Δn · d. Therefore, there is a correlation between the light intensity, the hue, or the dispersion spectrum of the detection light Lo and the retardation of the liquid crystal layer 10a. Therefore, by determining this correlation theoretically or by an experiment or simulation or the like. , The retardation Δn · d of the liquid crystal layer 10a based on the light intensity, hue or dispersion spectrum of the detection light Lo, or the liquid crystal layer 1 if Δn of the liquid crystal is known.
It is possible to obtain the thickness d of 0a.

In this embodiment, the thickness of the liquid crystal layer is utilized by utilizing the fact that the extreme value (minimum value or maximum value) of the dispersion spectrum of the detection light changes depending on the amount of change in the polarization state of the detection light. The height d is obtained, and the details will be described later.

Here, the incident angle θi = the output angle θo may be an appropriate angle of 0 ° or more and less than 90 °, but the critical angle (total reflection angle) θth of the linearly polarized light Li with respect to the surface of the substrate 10b. If it exceeds, linearly polarized light Li
Since the light is totally reflected on the surface of 0b and the light does not enter the liquid crystal layer 10a, the angle range of θi = θo is actually 0 degree or more and less than θth. Even within this angle range,
It is preferable to make the angle as large as possible from the viewpoint that the optical path length in the liquid crystal layer 10a can be made large, and as a result, the detection sensitivity to the liquid crystal layer 10a can be enhanced, but since the optical path length in the liquid crystal panel 10 becomes longer, The light intensity itself of the light Lo decreases.

In this embodiment, a spectroscopic unit is used as the photodetector 29 to obtain spectral characteristic data of transmitted light. This spectroscopic unit is capable of obtaining a spectroscopic spectrum of the above detection light Lo in at least a visible light region or detection data corresponding thereto. For example, a spectrometer using a spectroscopic element or a multiplex spectroscopic method is used. It may be a spectroscopic device, a multi-channel spectrometer, or the like.

In the spectroscopic unit, the spectroscopic spectrum of the light reaching the optical path in the visible light region itself, or various spectroscopic spectra equivalent to the spectroscopic spectrum, that is, the spectroscopic spectrum can be derived by a predetermined mathematical operation, Optical parameters (complex permittivity, etc.) are detected.

FIG. 4 shows an example of the spectrum of the detection light Lo. In this spectrum, there are a minimum value Mb and a maximum value Mp in the visible light region. The wavelength λb at which the minimum value Mb is obtained and the wavelength λp at which the maximum value Mp is obtained are the thickness d of the liquid crystal layer 10a of the liquid crystal display panel 10.
Has a predetermined correlation with.

In general, the optical characteristics of the liquid crystal, that is, the optical anisotropy Δn, the twist angle θ, the thickness d of the liquid crystal layer 10a, and the light between the transmission polarization axis of the polarizing plate 25 and the transmission polarization axis of the polarizing plate 26 are used. By using the Jones vector method or the 4 × 4 matrix method based on the angle φ about the axis (90 degrees in the case of this embodiment), the emission spectrum of the light source, and the optical characteristics of the first substrate and the second substrate. The above-mentioned spectrum can be derived. The positions of the minimum value Mb and the maximum value Mp in this spectrum, that is, the wavelength λ
b and λp can be represented by the above parameters. Therefore, if the optical conditions of the light source, the incident side optical system, and the emitting side optical system are constant, the thickness d of the liquid crystal layer 10a when the predetermined Δn, θ, and φ are equal to the above wavelength λb or λp. It can be represented by a function F (λ). Function indicating this thickness d =
F (λ) is practically 4 from the first order of the wavelength λb or λp.
It can be expressed by the following function.

FIG. 4 shows two spectral spectra when the thickness d of the liquid crystal layer 10a is changed (d = d0, d = d0-Δd). Usually, the above wavelength λ in the visible light region
b and λp monotonically increase according to the function F (λ) as the thickness d of the liquid crystal layer 10a increases. The above function F
(Λ) may be an empirical formula obtained from data obtained by repeating experiments in advance.

FIG. 5 shows a liquid crystal display panel 10 including a monochrome panel A not having a color filter as shown in FIG. 2 and color panels B and C having a color filter as shown in FIG. In each case, the above-mentioned spectrum is shown. Here, the color panel B and the color panel C each have a color filter provided with a coloring layer having a different hue. In this case, in order to reduce the measurement variation, the range of light dispersed by the spectroscopic unit is set to a range that passes through a region including a plurality of pixels in the liquid crystal display region.

As shown in FIG. 5, the spectral spectrum greatly changes depending on the presence or absence of a color filter, the type of color filter, etc., but the positions of the minimum value Mb and the maximum value Mp hardly change, and the wavelengths λb and λp are changed. Is almost constant. Therefore, when the thickness d of the liquid crystal layer is obtained using the above function F (λ), the detection value is hardly affected by the presence or absence of the color filter and the change of the filter color tone.

FIG. 6 shows a schematic flow chart of an operation program for operating the above evaluation processing section 30. First, when the liquid crystal display panel 10 is set in the evaluation device and predetermined data is input by an operator or the like from an input device (not shown) such as a keyboard, the input data is stored in the evaluation processing unit 30. Save to. This input data is the cell condition, that is, the optical anisotropy Δ of the liquid crystal.
n and twist angle θ, the angle φ of the transmission polarization axis of the polarizing plates 25 and 26, the thickness and material of the panel substrate, the optical characteristics, and the like. The evaluation processing unit also receives and records the target value d0 of the thickness d of the liquid crystal layer 10a.

The evaluation processing unit 30 obtains the function F (λ) based on the input cell condition and target value. This function F (λ) is determined by the thickness d of the liquid crystal layer 10a and the wavelength λ.
It shows the relationship with b or λp. In this embodiment, the wavelength λb corresponding to the minimum value Mb of the spectrum is used.

Next, a start command input from the outside is waited, and when the start command is input, the measurement position is set at an appropriate position and the spectroscopic measurement is started. Then, the spectroscopic unit sends the spectroscopic data to the evaluation processing section 30,
The evaluation processing unit obtains the wavelength λb based on the spectral data.

Then, from the wavelength λb to the function F
The thickness d of the liquid crystal layer 10a is calculated using (λ), and the difference between the calculated thickness d and the target value d0 Δd = | d−d0
| (Absolute value of the difference between d and d0) and the like are output to the outside (for example, display means and recording means).

After that, when the measurement location is changed according to a predetermined measurement pattern, for example, when the measurement is performed at a plurality of locations on the liquid crystal panel 10, the relative position between the liquid crystal panel 10 and the optical system is set by the drive mechanism. The relationship is changed, and the measurement is repeated at another place in the same manner as described above.

(Second Embodiment) Next, a second embodiment according to the present invention will be described with reference to FIG. Here, the liquid crystal panel 10 to be evaluated is the same as that shown in FIG. 2, and therefore its explanation is omitted. The structures of the photodetector 29 and the evaluation processing unit 30 are also the same, and therefore their explanations are omitted.

The evaluation device 40 of this embodiment includes a light source 41.
A polarizing plate 42 for converting the light emitted from the light source 41 into linearly polarized light, and a polarizing plate 4 for receiving the transmitted light formed by the linearly polarized light irradiated from the polarizing plate 42 passing through the liquid crystal panel 10.
4 and a photodetector 45 for detecting the light transmitted through the polarizing plate 44.
And an evaluation processing unit 46 for processing the detection data obtained by the photodetector 45. Also in the present embodiment, the photodetector 4 is similar to the photodetector 29 of the first embodiment.
A spectroscopic unit 5 is used.

In this embodiment, the polarization transmission axis 42t of the polarizing plate 42 is set in the direction orthogonal to the plane of the drawing, and the polarization absorption axis 44a of the polarizing plate 44 is also set in the direction orthogonal to the plane of the drawing.

In this embodiment, the light emitted from the light source 41 passes through the polarizing plate 42, and the linearly polarized light Li having an oscillating surface parallel to the polarization transmission axis 42t is incident on the liquid crystal panel 10. The incident light Li passes through the liquid crystal panel 10 and then enters the polarizing plate 44, where a polarized component having a vibrating surface parallel to the polarization absorption axis 44a of the polarizing plate 44 is absorbed.
The remaining component is detected by the photodetector 45 as the detection light Lo.

In this embodiment, the incident angle θi and the outgoing angle θo of light with respect to the liquid crystal panel 10 are both 0 degrees. Here, the transmitted light Lt passes through the liquid crystal layer 10a and is incident light Li depending on the retardation of the liquid crystal layer 10a.
Since the polarization state changes with respect to the linearly polarized light of, the polarization component may have a vibrating surface parallel to the paper surface of the figure, and this polarization component passes through the polarizing plate 44 and passes through the photodetector 45.
Detected at.

In the embodiment described above, the liquid crystal panel for the monochrome type / semi-transmissive / semi-reflective liquid crystal device has been described as an example, but as shown in FIG. The evaluation device and the evaluation method of the present invention can be used for a panel for use.

As shown in FIG. 7, in a liquid crystal panel 100 for a color semi-transmissive semi-reflective liquid crystal device, a first substrate 101 and a second substrate 102 are bonded together with a sealing material 103, and a liquid crystal layer 104 is arranged between the substrates. It was done. First substrate 1
No. 1 on the inner surface of 01 is made of a transparent conductor such as ITO.
A counter transparent electrode 111 as an electrode is formed. A hard protective film 112 made of SiO ₂ or the like is formed on the surface of the opposing transparent electrode 111. Further, an alignment film 113 is formed on the surface of the hard protective film 112, and the surface of this alignment film 113 is subjected to rubbing treatment.

On the other hand, on the inner surface of the substrate 102, a reflection layer 114 made of a metal film such as Al is formed.
An insulating layer 115 is formed on the surface 14. Insulation layer 1
A transparent electrode 116 as a second electrode is formed on the surface 14. An opening (not shown) is provided in the reflective layer 114 for each pixel.
Is provided. The colored layer 11 is formed on the transparent electrode 116.
7 is formed, and the colored layer 117 is covered with a protective film 118 for flattening the surface. The colored layer 117 is configured such that different color tones (for example, red, green, and blue) are arranged in an appropriate pattern. An alignment film 119 is formed on the protective film 118, and its surface is subjected to rubbing treatment.

In the color semi-transmissive / semi-reflective liquid crystal panel 100 having the above-described structure, the liquid crystal layer 1 has the color filter provided with the coloring layer 117.
The light that has passed through 04 passes through the color filter and exhibits a predetermined color tone.

Since the colored layer 117 has different hues between adjacent pixels, and there are hue variations and low reproducibility, a method for obtaining the thickness of the liquid crystal layer using the hue of the detection light Lo is used. It is difficult to use. However, as in the above-described embodiment, by obtaining the thickness of the liquid crystal layer 104 by using the spectral characteristic of the detection light, it is possible to obtain a more accurate value than before.

In the above description, the liquid crystal panel for the transflective liquid crystal device is described as an example, but the evaluation device and the evaluation method in the above embodiments are applied to the liquid crystal panel for the transmissive liquid crystal device. You can also do it.

In the embodiment described above, the thickness of the liquid crystal layer of the liquid crystal panel can be detected with high accuracy and substantially without being affected by the presence / absence of a color filter or the variation in hue.

Further, in the above embodiment, the wavelength λb of the spectrum is used to obtain the thickness of the liquid crystal layer, but λp may be used, and the frequency corresponding to the wavelength or the frequency corresponding thereto may be used. Various corresponding values may be used.

In the above embodiment, the method of obtaining the thickness of the liquid crystal layer as the characteristic of the liquid crystal layer is described in detail.
Not only the thickness of the liquid crystal layer but also the liquid crystal layer characteristics such as the retardation Δn · d of the liquid crystal layer and the presence or absence of foreign matter in the liquid crystal layer can be similarly used. For example, regarding the presence / absence of foreign matter in the liquid crystal layer, the above-mentioned function F (λ) is calculated at a plurality of points, and the fact that the presence of foreign matter causes the function F (λ) to change more greatly than the target value do is used. It is possible to use a method of confirming the presence of foreign matter by the above method.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram schematically showing a structure of a first embodiment of an evaluation device according to the present invention.

FIG. 2 is an enlarged explanatory diagram schematically showing the measurement principle of the first embodiment.

FIG. 3 is a schematic configuration diagram schematically showing the structure of a second embodiment of the evaluation device according to the present invention.

FIG. 4 is a graph showing a spectroscopic spectrum detected by the evaluation device of the present invention.

FIG. 5 is a graph showing an example of a spectrum spectrum detected by the evaluation device of the present invention for liquid crystal panels having different conditions such as the presence or absence of a color filter.

FIG. 6 is a schematic flowchart showing an outline of an operation program of the evaluation device according to the present invention.

FIG. 7 is a schematic sectional view schematically showing the structure of a color transflective liquid crystal panel.

[Explanation of symbols]

10 ... Liquid crystal panel 10a, 104 ... Liquid crystal layer 10b, 101 ... First substrate 10c, 102 ... Second substrate 11a, 114 ... Reflective layer 11b, 116 ... Transparent electrode 11c ... opening 10e, 111 ... Opposing transparent electrode 20, 40 ... Evaluation device 21 ... Base 22, 41 ... Light source 23 ... Light guide (incident side) 24 ... Concentrator (incident side) 25, 42 ... Polarizing plate (incident side) 26, 44 ... Polarizing plate (outgoing side) 27 ... Concentrator (outgoing side) 28 ... Light guide (outgoing side) 29, 45 ... Photodetector (spectral unit) 30, 46 ... Evaluation processing unit (MPU) 100 ... Color transflective liquid crystal panel

Claims (14)

[Claims] 1. A method for evaluating a liquid crystal panel for optically evaluating the liquid crystal panel, which comprises detecting polarized light incident on the liquid crystal panel and transmitting light passing through the liquid crystal panel. A method for evaluating a liquid crystal panel, which comprises performing panel evaluation based on light spectral characteristics. 2. A liquid crystal layer is sandwiched between one substrate provided with a first electrode and a second substrate provided with a second electrode facing the first electrode and a reflective layer having an opening. A liquid crystal panel evaluation method for optically evaluating a liquid crystal panel, wherein polarized light in a predetermined state is incident on the liquid crystal panel from a first substrate side, the first substrate, the first electrode, and A method for evaluating a liquid crystal panel, characterized in that panel evaluation is performed based on a spectral characteristic of detection light obtained from transmitted light that has passed through a liquid crystal layer, the second electrode, the opening of the reflective layer, and the second substrate. . 3. The polarized light is mainly composed of a polarized light component having a first vibrating surface, and the detected light mainly reduces a polarized light component having the first vibrating surface of the transmitted light. The liquid crystal panel evaluation method according to claim 1 or 2, wherein the liquid crystal panel is evaluated. 4. The detection light is obtained by extracting, from the transmitted light, a polarization component mainly having a second vibrating surface substantially orthogonal to the first vibrating surface. LCD panel evaluation method. 5. The liquid crystal panel evaluation method according to claim 1, wherein the thickness of the liquid crystal layer is obtained based on the spectral characteristics of the detection light. 6. The liquid crystal panel evaluation method according to claim 5, wherein the thickness of the liquid crystal layer is obtained based on the wavelength or frequency position of the extreme value of the spectrum of the detection light. 7. The liquid crystal panel evaluation method according to claim 1, wherein foreign matter in the liquid crystal layer is examined based on a spectral characteristic of the detection light. 8. A liquid crystal panel evaluation device for optically evaluating a liquid crystal panel, comprising: polarized light irradiation means for irradiating the liquid crystal panel with polarized light in a predetermined state; and transmitted light passing through the liquid crystal panel. It is characterized by further comprising: a light detecting means for obtaining detection light from the light detecting means, a light detecting means for detecting the detection light, and a means for obtaining the characteristic of the liquid crystal layer based on the spectral characteristic of the detected light. LCD panel evaluation device. 9. A liquid crystal panel evaluation apparatus for optically evaluating a liquid crystal panel, comprising polarized light irradiation means for irradiating the liquid crystal panel with linearly polarized light having a first vibrating surface, and the liquid crystal. Detecting means for reducing the polarization component of the passing light that has passed through the panel and having the first vibrating surface to obtain detection light, light detection means for detecting the detection light, and spectral characteristics of the detection light And a means for obtaining the characteristic of the liquid crystal layer based on the above. 10. The liquid crystal panel according to claim 8, wherein the polarized light irradiation means has a light source and a polarizing means for obtaining the polarized light from the light emitted from the light source. Evaluation device. 11. The liquid crystal panel according to claim 10, wherein the polarization transmission axis of the polarization means and the polarization absorption axis of the light detection means are substantially orthogonal to each other with respect to the optical axis. Evaluation device. 12. The liquid crystal panel evaluation apparatus according to claim 8, wherein the characteristic of the liquid crystal layer is a thickness of the liquid crystal layer. 13. The means for obtaining the thickness of the liquid crystal layer derives the thickness of the liquid crystal layer based on the wavelength or frequency position of the extreme value of the spectrum of the detection light. The liquid crystal panel evaluation device according to claim 12. 14. The liquid crystal panel evaluation device according to claim 8, further comprising means for indicating the presence or absence of foreign matter in the liquid crystal layer based on the detection light. .