JP2002243418A - Method and device for detecting gap of liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gap detecting method and a detecting device for a liquid crystal panel which can easily detect the gap of the liquid crystal panel in a short time through simple constitution. SOLUTION: The light from a light source 1 after being linearly polarized by a polarizer 11 travels through a half-mirror 12 almost in parallel to the normal of a reflection type liquid crystal panel 13 and enters on the reflection type liquid crystal panel 13. The reflected light reflected by the reflection type liquid crystal panel 13 passes through the half-mirror 12 and an analyzer 14 and is photodetected by a detector 15. In this state, the reflection type liquid crystal panel 13 is rotated on an axis nearly parallel to the normal of the reflection type liquid crystal panel 13 and the angle (quenching angle) where the output signal of the detector 15 becomes minimum is measured. According to the measured quenching angle, the gap of the reflection type liquid crystal panel 13 is detected. Here, the transmission-axis direction of the analyzer 14 is set nearly parallel and nearly orthogonal to the polarizing direction of the incident light, the output of the detector 15 is measured, and the gap of the reflection type liquid crystal panel 13 can be measured according to the measured signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a gap in a liquid crystal panel, particularly, a reflection type liquid crystal panel.

[0002]

2. Description of the Related Art A liquid crystal panel has features such as light weight, thin thickness and low power consumption. For this reason, liquid crystal panels are widely applied to monitor devices, display devices, and the like. In particular, a reflection-type liquid crystal panel having a reflection mirror on one substrate does not require a light source unit because light emitted from the outside to the liquid crystal panel is used as an illumination light source. For this reason, the reflection type liquid crystal panel is used as a display device of a portable information terminal, a cellular phone, or the like, which consumes particularly low power. At present, as these reflection-type liquid crystal panels, a type in which liquid crystal molecules are aligned substantially in parallel on both substrates, but the alignment direction of the liquid crystal molecules is twisted between the two substrates is used. Furthermore, among the reflective liquid crystal panels in which the orientation direction of the liquid crystal molecules is twisted between the two substrates, the reflective super twisted nematic liquid crystal panel (ref.
lective super twisted nematic liquid crystal
panel) (reflective twisted nematic liquid crystal panel) and reflective twisted nematic liquid crystal panel (reflectivetwisted nema)
A tic liquid crystal panel (reflection type TN liquid crystal panel) is mainly used. The reflection type STN liquid crystal panel has a twist angle of about 180 ° or more in the alignment direction of liquid crystal molecules. The reflection type TN liquid crystal panel has a twist angle of about 120 ° or less in the alignment direction of liquid crystal molecules. Below,
The reflective STN liquid crystal panel and the reflective TN liquid crystal panel are collectively called a reflective liquid crystal panel. The display performance of the reflective liquid crystal panel depends on the distance (gap) between the substrates, the refractive index of the liquid crystal, the twist angle of the alignment, the pretilt angle (the angle at which the liquid crystal molecules are raised with respect to the plane of the substrate), and the like. In particular, when producing a reflective liquid crystal panel, it is important to manage the gap. This is not limited to the reflection type liquid crystal panel, but is also important when producing a transmission type liquid crystal panel. The transmissive liquid crystal panel irradiates light from a light source from the back surface of the liquid crystal panel. Various methods have been proposed as a method for detecting the gap of the reflective liquid crystal panel. For example, a method of obtaining a gap from an interference fringe pattern appearing in a reflection spectrum in the near red region (“20
2000 Japanese Liquid Crystal Society Symposium Preprints, PCb03 ”, 3
41, and a method of detecting the gap of the liquid crystal panel from the retardation Δnd (Δn: refractive index anisotropy of the liquid crystal cell, d: thickness of the liquid crystal cell).

[0003]

However, the method for obtaining the gap of the liquid crystal panel from the pattern of interference fringes is as follows.
Because it does not take into account that there are many interfaces contributing to interference, that liquid crystal refractive index dispersion is required for light in the near-red range, and that the orientation of liquid crystal molecules is twisted, etc. It is necessary to create a curve showing the relationship for correcting the given numerical value to the actual gap value. Further, under the alignment condition of the liquid crystal used in the reflection type TN liquid crystal panel, the retardation becomes constant irrespective of the gap. For this reason, it is difficult to detect the gap of the reflective TN liquid crystal panel by the method of detecting the gap of the liquid crystal panel from the retardation. In addition, in the conventional method, the apparatus is complicated, and operation and processing are troublesome. In particular, the detection time is long. Therefore, an object of the present invention is to provide a gap detecting method and a device-up detecting device for a liquid crystal panel, which can easily and quickly detect a gap (thickness of a liquid crystal layer) of the liquid crystal panel with a simple configuration. And

[0004]

According to a first aspect of the present invention, there is provided a method for detecting a gap in a liquid crystal panel according to the present invention. In the liquid crystal panel gap detecting method according to the first aspect, the polarization direction of the incident light on the liquid crystal panel is substantially perpendicular to the transmission axis direction of the analyzer provided on the reflected light side. Is rotated relative to the transmission axis direction of the analyzer, the extinction position angle at which the output signal of the light reception amount detection device receiving the reflected light is minimized, and the gap of the liquid crystal panel is determined based on the detected extinction position angle. Is detected. This makes it possible to accurately detect the gap of the liquid crystal panel by a simple method of detecting the extinction position angle in a crossed Nicols state. According to a second aspect of the present invention, there is provided a method of detecting a gap of a liquid crystal panel as described in claim 2. In the gap detecting method for a liquid crystal panel according to the second aspect, since the liquid crystal panel is rotated about an axis substantially parallel to the incident direction of the incident light, the extinction position angle can be detected with a simple configuration. Also, the third
The present invention is a liquid crystal panel gap detecting method as described in claim 3. In the gap detecting method for a liquid crystal panel according to the third aspect, the first output signal from the light reception amount detection device in a state where the transmission axis of the analyzer is substantially parallel to the polarization direction of the light incident on the liquid crystal panel; A second output signal from the light-receiving amount detection device is detected in a state where the transmission axis of the analyzer is substantially orthogonal to the polarization direction of the incident light on the liquid crystal panel, and the liquid crystal panel is detected based on the first and second output signals. To detect the gap.
Thus, the gap of the liquid crystal panel can be accurately detected by a simple method of detecting the output signal of the light-receiving amount detection device in the state of the parallel Nicols and the state of the cross Nicols. A fourth invention is a method for detecting a gap of a liquid crystal panel as described in claim 4. In the gap detecting method for a liquid crystal panel according to the fourth aspect, the amount of received light is detected in a state where the transmission axis direction of the analyzer is located on a bisector in a direction substantially parallel to the polarization direction of the incident light and a direction substantially orthogonal to the polarization direction. Detecting a third output signal from the device and detecting the first, second,
The gap of the liquid crystal panel is detected based on the third output signal. Thereby, even when it is difficult to detect the gap of the liquid crystal panel only by the output signal from the light reception amount detection device in the state of the parallel Nicols and the state of the cross Nicols, the gap of the liquid crystal panel can be reliably detected. . A fifth invention is a method for detecting a gap of a liquid crystal panel as described in claim 5. In the gap detecting method for a liquid crystal panel according to the fifth aspect, the first output signal and the second output signal are different from each other by at least two different rotations about an axis substantially parallel to a direction of incidence of incident light on the liquid crystal panel. The gap is detected at the rotation position (the installation angle of the liquid crystal panel), and based on the first and second output signals detected at each rotation position. Thereby, the gap of the liquid crystal panel can be detected with high accuracy in consideration of the amount of noise. According to a sixth aspect of the present invention, there is provided a method for detecting a gap of a liquid crystal panel according to a sixth aspect. In the gap detecting method for a liquid crystal panel according to the sixth aspect, since the angles are different from each other by 5 ° or more, the gap of the liquid crystal panel can be detected with higher accuracy. A seventh invention is a method for detecting a gap of a liquid crystal panel as described in claim 7. In the gap detecting method for a liquid crystal panel according to claim 7, a half mirror that reflects light from a light source and transmits reflected light from the liquid crystal panel is provided, and a noise light amount in a parallel Nicol state and a cross Nicol state. The transmittance of the half mirror is determined in advance, and the first and second output signals, the amount of noise in the parallel Nicol state and the cross Nicol state determined in advance, and the transmittance of the half mirror are determined based on the transmittance of the half mirror. Detect gaps. Thus, it is possible to detect the gap of the liquid crystal panel with high accuracy in consideration of the amount of noise in a state where the installation angle of the liquid crystal panel is fixed. Further, the two-dimensional distribution of the gap of the liquid crystal panel can be detected.
An eighth invention is a method for detecting a gap of a liquid crystal panel as described in claim 8. In the gap detecting method for a liquid crystal panel according to the present invention, a half mirror that reflects light from a light source and transmits reflected light from the liquid crystal panel is provided, and an amount of incident light, a state of parallel Nicols, and a cross Nicol state. The amount of noise in the state and the transmittance of the half mirror are determined in advance, the amounts of the first and second output signals and the amount of incident light determined in advance, the amount of noise in the parallel Nicol state and the amount of noise in the cross Nicol state, and the half amount. The gap of the liquid crystal panel is detected based on the transmittance of the mirror. Thus, it is possible to detect the gap of the liquid crystal panel with high accuracy in consideration of the amount of noise in a state where the installation angle of the liquid crystal panel is fixed. Further, the two-dimensional distribution of the gap of the liquid crystal panel can be detected. According to a ninth aspect of the present invention, there is provided a liquid crystal panel gap detecting method according to the ninth aspect. In the gap detecting method for a liquid crystal panel according to the ninth aspect, in a state where the transmission axis of the analyzer is substantially parallel to the polarization direction of the incident light, the amount of noise mainly including the surface reflected light from the received light amount detection device is determined. A fourth output signal is detected when the transmission axis direction of the analyzer is substantially orthogonal to the polarization direction of the incident light. A signal is detected, and a gap of the liquid crystal panel is detected based on the first, second, fourth, and fifth output signals. This makes it possible to easily detect the amount of noise in the parallel Nicols state and the crossed Nicols state, and to easily detect the gap of the liquid crystal panel in consideration of the amount of noise. Also,
A tenth invention is a liquid crystal panel gap detection method according to the tenth aspect. In the gap detecting method for a liquid crystal panel according to the tenth aspect, the reflected light from the liquid crystal panel is incident on the polarization beam splitter, and the polarization direction is substantially parallel to the polarization direction of the incident light, and the polarization direction is the incident light. The light that is substantially orthogonal to the polarization direction is separated, and the amount of each of the separated reflected lights is detected by the first and second light-receiving amount detecting devices, respectively, and is output to the first and second light-receiving amount detecting devices. The gap of the liquid crystal panel is detected based on the information. Accordingly, the amount of light received in the parallel Nicols state and the crossed Nicols state can be simultaneously detected, so that the gap of the liquid crystal panel can be detected in a shorter time. Further, an eleventh invention is a gap detecting device for a liquid crystal panel as described in claim 11. In the liquid crystal panel gap detecting apparatus according to claim 11, an analyzer arranged to receive reflected light from the liquid crystal panel and to have a transmission axis substantially orthogonal to a polarization direction of light incident on the liquid crystal panel; A light-receiving amount detecting device for receiving light passing through the light-receiving portion; and a processing device, wherein the processing device detects the light-receiving amount when the incident direction of the incident light is relatively rotated with respect to the transmission axis direction of the analyzer. The gap of the liquid crystal panel is detected based on the extinction angle at which the output signal of the device becomes minimum. This has the same effect as the first aspect of the present invention. According to a twelfth aspect of the present invention, there is provided a gap detecting device for a liquid crystal panel according to the twelfth aspect. The gap detecting device for a liquid crystal panel according to the twelfth aspect includes an analyzer that receives reflected light from the liquid crystal panel, a light-receiving amount detecting device that receives light that has passed through the analyzer, and a processing device. The first light from the light-receiving-amount detecting device in a state where the transmission axis of the analyzer is substantially parallel to the polarization direction of the incident light.
The gap of the liquid crystal panel is detected on the basis of the output signal of the second embodiment and the second output signal from the light receiving amount detection device in a state where the transmission axis direction of the analyzer is substantially orthogonal to the polarization direction of the incident light. This has the same effect as the third aspect of the invention. A thirteenth invention is a gap detecting device for a liquid crystal panel as described in claim 13. Claim 13
Since the light emitting device has a polarizer, various light emitting devices can be used in the gap detection device for a liquid crystal panel described in (1). A fourteenth invention is a gap detecting device for a liquid crystal panel as described in claim 14. The gap detecting device for a liquid crystal panel according to claim 14 uses a planar imaging device as a light receiving amount detecting device, so that a portion for detecting a gap of the liquid crystal panel can be easily specified. Can easily be detected. A fifteenth invention is a liquid crystal panel gap detection device according to the fifteenth aspect. In the gap detecting device for a liquid crystal panel according to the present invention, since the light emitting device or the light receiving amount detecting device has a wavelength selecting function, it is possible to detect gaps between pixels of various colors of the liquid crystal panel. In addition, the sixteenth invention provides
A gap detecting device for a liquid crystal panel as described in claim 16. 17. The liquid crystal panel gap detecting device according to claim 16, wherein the processing device outputs the first output at at least two different rotational positions about an axis substantially parallel to an incident direction of the incident light on the liquid crystal panel. The gap of the liquid crystal panel is detected based on the signal and the second output signal. This has the same effect as the fifth aspect of the invention. A seventeenth invention is a gap detecting device for a liquid crystal panel as described in claim 17. Claim 17
In the gap detection device for a liquid crystal panel described in the above, the processing device detects the amount of received light in a state where the transmission axis of the first output signal, the second output signal, and the analyzer is substantially parallel to the polarization direction of the incident light. A fourth output signal indicating the amount of noise mainly composed of the surface reflected light from the device, and a light reception amount detection device in a state where the transmission axis of the analyzer is arranged so as to be substantially orthogonal to the polarization direction of the incident light. And a fifth output signal indicating the amount of noise mainly composed of external light.
This has the same effect as the ninth aspect. An eighteenth invention is a gap detecting device for a liquid crystal panel as described in claim 18. Claim 18
The gap detection device for a liquid crystal panel according to the above, receives the reflected light from the liquid crystal panel, the light having a polarization direction substantially parallel to the polarization direction of the incident light to the liquid crystal panel from the reflected light, and substantially orthogonal to the polarization direction of the incident light A polarizing beam splitter that separates light having a desired polarization direction, first and second received light amount detection devices that respectively detect the amount of each reflected light emitted from the polarized beam splitter, and a processing device. Is the first,
A gap of the liquid crystal panel is detected based on a detection signal of the second light reception amount detection device. This has the same effect as the tenth aspect of the present invention. According to a nineteenth aspect, there is provided a gap detecting device for a liquid crystal panel according to the nineteenth aspect. The liquid crystal panel gap detection device according to claim 19, further comprising: an analyzer that receives reflected light from the liquid crystal panel; a light reception amount detection device that detects an amount of light passing through the analyzer; and a processing device. The apparatus includes a first output signal from the light-receiving amount detection device in a state where the transmission axis direction of the analyzer is substantially parallel to the polarization direction of the incident light, and the transmission axis direction of the analyzer is substantially the same as the polarization direction of the incident light. A state in which the second output signal from the light-receiving amount detection device in the orthogonal state and the transmission axis of the analyzer are located on a bisector in a direction substantially parallel to the polarization direction of the incident light and in a direction substantially orthogonal to the polarization direction of the incident light. Then, the gap of the liquid crystal panel is detected based on the third output signal from the light-receiving amount detecting device at step (1).
This has the same effect as the invention described in claim 4.

[0005]

Embodiments of the present invention will be described below. In the following, the liquid crystal molecules are oriented substantially parallel to both substrates, the orientation direction of the liquid crystal molecules is twisted between the two substrates, and one substrate is provided with a reflecting mirror or a reflecting member having a light reflecting function. Provided reflective liquid crystal panels (reflective TN liquid crystal panels, reflective STN liquid crystal panels, etc.)
The case where the gap (the thickness of the liquid crystal layer) is detected will be described. However, according to the present invention, the gap (the thickness of the liquid crystal layer) of a transmissive liquid crystal panel having no reflective member (a transmissive TN liquid crystal panel, a transmissive STN liquid crystal panel, etc.)
Can also be applied to the case of detecting When detecting the gap of the transmissive liquid crystal panel using the method or the apparatus of the present invention, a reflecting member such as a reflecting mirror may be separately installed substantially parallel to the substrate plane on one of the substrates of the transmissive liquid crystal panel. Good. The reflective liquid crystal panel described in this specification includes a transmissive liquid crystal panel in which a reflective member is separately provided.

[0006] The polarization state of light can be represented using an electric field vector E of light. When the polarization state of light is represented by an electric field vector of light, a change in the polarization state of light when the light passes through the liquid crystal layer can be represented by a 2 × 2 matrix (Jones matrix). Here, it is assumed that the liquid crystal layer is divided into N very thin layers. Assuming that the orientation of liquid crystal molecules is constant (azimuth φ _j [rad], tilt angle θ [rad]) in each thin layer, this thin layer can be optically regarded as a uniaxial medium. . It is assumed that this thin layer is arranged as shown in FIG. 1 with respect to the xyz coordinate system. FIG.
In the following, the z-axis is set to the incident direction of light, and the x-axis and the y-axis are set to z
Set perpendicular to the axis. In FIG. 1, light enters from the liquid crystal layer side, is reflected by the reflecting mirror, passes through the liquid crystal layer again, and exits as reflected light. Here, it is assumed that light is vertically incident on the reflective liquid crystal panel (parallel to the liquid crystal panel normal), and that the reflected light is vertically reflected from the reflective liquid crystal panel. However, in the actual measurement, it is sufficient that the light incident direction is within 20 °, preferably within 10 ° with respect to the liquid crystal panel normal. That is, the light may be incident on the reflective liquid crystal panel substantially perpendicularly.

The Jones matrix W _j of the j-th thin layer with respect to the incident light is represented by (Equation 1). Here, λ [μ
m] is the wavelength of light. φ [rad] is the twist angle of the liquid crystal (the difference between the azimuthal angles of the liquid crystal molecules on both substrates).
n _o is the refractive index of the liquid crystal material with respect to ordinary light (light having a polarization plane perpendicular to the long axis of the liquid crystal molecules). _ne is the refractive index of the liquid crystal material with respect to extraordinary light (light having a plane of polarization parallel to the long axis of the liquid crystal molecules). d [μm] is the gap of the liquid crystal panel (the thickness of the liquid crystal layer). Also, π is the pi, i
Indicates an imaginary unit.

(Equation 1) (Equation 1)

Similarly, Jo of the j-th thin layer for reflected light
The nes matrix W _j ^ref is represented as (Equation 2).

(Equation 2) (Equation 2)

[0009] Similarly, the Jones matrix M of the reflecting mirror is expressed as (Equation 3).

(Equation 3) (Equation 3)

[0010] From these, the Jones matrix W of the entire reflection type liquid crystal panel including the reflection mirror is represented as (Equation 4).

(Equation 4) (Equation 4) Here, Jones matrix M of the reflecting mirror, J of the thin layer with respect to the incident light
Between the Jones matrix W _j ^ref thin layer with ones matrix W _j with respect to the reflection light, it holds the relationship of (Equation 5).

(Equation 5) (Equation 5)

Therefore, (Equation 4) can be expressed as (Equation 6).

(Equation 6) (Equation 6) [T (−φ) T (φ)] in (Equation 6) is formally equal to (Equation 1) which is a Jones matrix of a uniaxial medium. Thus, it can be understood that the reflection type liquid crystal panel is optically equivalent to a uniaxial medium.

[First Embodiment] First, a first embodiment of a method for detecting a gap of a liquid crystal panel will be described. In the uniaxial medium, the polarization direction of the incident light having the largest refractive index is called a slow axis, and the polarization direction of the incident light having the smallest refractive index is called a fast axis. In this specification, directions in which the slow axis and the fast axis are projected on the substrate plane are referred to as a slow axis direction and a fast axis direction, respectively. Here, the slow axis direction of the uniaxial medium is φ _app [rad], and the retardation (the product of the anisotropy of refractive index of the uniaxial medium and the thickness) is Δn _eff 2d [μm].
If the thickness is doubled because of the reciprocation, φ _app and Δn _eff d of the uniaxial medium have the relationship of (Equation 7) with the parameters (φ, Δnd, β) of the reflective liquid crystal panel.

(Equation 7) (Equation 7)

The reflection type liquid crystal panel is set in a crossed Nicols state (the transmission axis of the polarizer provided on the incident light side (the polarization direction of the incident light of the liquid crystal panel) and the transmission axis of the analyzer provided on the reflected light side). When the light is rotated about an axis substantially parallel to the incident direction of the incident light in a state where the incident light is orthogonal, the reflected light is extinguished at a certain angle (the reflectance becomes minimum). This angle is called an extinction angle, and coincides with the slow axis direction of the uniaxial medium (or the fast axis direction orthogonal thereto). That is, by measuring the extinction angle of the reflection type liquid crystal panel from the liquid crystal alignment direction in the substrate of the incident light side, the extinction angle is perpendicular thereto slow axis direction phi _app (or Equation (7) leading phase Axial direction [φ _app + π / 2]).

Therefore, the gap d of the reflective liquid crystal panel can be detected by using (Equation 8) derived from (Equation 7).

(Equation 8) (Equation 8)

FIGS. 2 and 3 show the extinction angle using (Equation 7) when the gap d is changed near the condition (Δnd = 260 nm, φ = 70 °) used in the reflection type TN liquid crystal panel. The results of calculating φ _app and retardation Δn _eff d are shown (calculated with Δn = 0.066). From FIG.
The extinction angle φ _app changes almost linearly with the gap d, and the sensitivity is about 1 ° / 0. It turns out that it is as high as 1 μm. On the other hand, from FIG. 3, the retardation Δn _eff
It can be seen that d hardly changes particularly when the gap d is around 4 μm. That is, it is understood that it is difficult to detect the gap d of the reflective TN liquid crystal panel by the method of measuring the retardation.

As a measuring device for measuring the extinction angle of the liquid crystal panel, for example, a measuring device as shown in FIGS. 4 and 5 can be used. The measuring device shown in FIG.
The half mirror is used to make incident light and reflected light travel substantially parallel to the normal of the reflective liquid crystal panel (sample). That is, the light from the light source 10 is linearly polarized by the polarizer 11 and then applied to the half mirror 12. The light reflected by the half mirror 12 travels substantially parallel to the normal line of the reflective liquid crystal panel 13 and enters the reflective liquid crystal panel 13. The light reflected by the reflective liquid crystal panel 13 passes through the half mirror 12 and is applied to a detector (light-receiving amount detector) 15 via an analyzer 14. The measuring apparatus shown in FIG. 5 allows incident light and reflected light to travel substantially parallel to the normal of the reflective liquid crystal panel by providing a sufficient distance between the light source and the reflective liquid crystal panel (sample). . That is, the light from the light source 21 is linearly polarized by the polarizer 22, then travels substantially parallel to the normal of the reflective liquid crystal panel 23, and
3 is incident. The light reflected by the reflective liquid crystal panel 23 is applied to a detector (received light amount detector) 25 via an analyzer 24. The angle between the traveling direction of the incident light / reflected light and the normal of the reflective liquid crystal panel is set to 30 ° or less, preferably 10 ° or less.

As the light source, a light source having monochromatic means such as a spectroscope or a color filter for monochromaticizing light from the light emitting device, or a monochromatic light such as a light emitting diode (LED) or a semiconductor laser may be used. A light emitting device that emits light may be used.
In FIGS. 4 and 5, the light emitting means is constituted by the light source and the polarizer, but the constitution of the light emitting means is not limited to this. For example, the light emitting means may be constituted by a polarized light source such as a polarized laser. In this case, the polarizer can be omitted. Although not shown in FIGS. 4 and 5, it is preferable to provide a polarizer, an analyzer, and an angle detecting means for detecting a rotation angle of the reflective liquid crystal panel. Although not shown in FIGS. 4 and 5, the extinction position angle φ _app is detected from the output signal from the detector and the output signal from the angle detection means, and the reflection type angle is determined from the extinction position angle φ _app by the method described above. A processing device for detecting the gap d of the liquid crystal panel and outputting the detection result to a display device, a printer, a storage medium, or the like is provided.

Next, a method of detecting a gap in a liquid crystal panel according to the first embodiment will be described. First, in the measuring apparatus shown in FIGS. 4 and 5, the reflective liquid crystal panels 13 and 23 are rotated around an axis substantially parallel to the normal line of the reflective liquid crystal panels 13 and 23. Then, the angle at which the output signals of the detectors 15 and 25 are minimized (the reflectance is minimized) is measured, and the extinction angle φ
_app . Further, the gap d between the reflective liquid crystal panels 13 and 23 is calculated using the measured extinction angle φ _app and (Equation 8).

The use of the liquid crystal panel gap detecting method of the first embodiment makes it possible to accurately detect the liquid crystal panel gap by a very simple method of detecting the extinction position angle in a crossed Nicols state. it can.

The extinction position angle was detected by rotating the reflective liquid crystal panel. However, the polarizer and the analyzer were rotated with the transmission axis direction of the polarizer and the transmission axis direction of the analyzer orthogonal to each other. The extinction angle may be measured. Further, the polarizer, the analyzer, and the liquid crystal panel may be rotated manually, or may be rotated using a driving device such as a motor. Further, when detecting the extinction angle of a liquid crystal panel with a color filter, if the wavelength of light is fixed, some pixels cannot be measured. Therefore, it is preferable to add a wavelength selection function to the light source or the detector. Accordingly, since the wavelength of light can be selected according to the color of the pixel, gaps between pixels of various colors of the liquid crystal panel can be detected. Further, a surface-type imaging device such as a CCD camera can be used as the detector. In this case, the portion of the liquid crystal panel for detecting the gap can be easily specified.
Further, it is possible to easily detect the two-dimensional distribution of the gap of the liquid crystal panel based on the image signal of the surface image sensor.

[Second Embodiment] Next, a method of detecting a gap in a liquid crystal panel according to a second embodiment will be described. Consider a case where a reflective liquid crystal panel is installed such that the angle between the orientation direction of liquid crystal molecules on the substrate on the incident light side and the polarization direction of the incident light is α ⁱⁿ . The electric field vector E ^ref of the reflected light at this time is expressed as (Equation 9) from (Equation 6) and (Equation 7).

(Equation 9) (Equation 9)

From now on, the analyzer on the reflected light side is in a parallel Nicol state (the transmission axis of the polarizer on the incident light side (the polarization direction of the incident light on the liquid crystal panel) is parallel to the transmission axis of the analyzer on the reflected light side). ) And the reflectivities R _x and R _y (ratio of the amount of reflected light from the liquid crystal panel to the amount of incident light) when arranged in a crossed Nicols state are expressed as (Equation 10).

(Equation 10) (Equation 10)

Therefore, in a reflective liquid crystal panel arranged such that the angle between the orientation direction of the liquid crystal molecules on the substrate on the incident light side and the polarization direction of the incident light is α ⁱⁿ , the analyzer is in a parallel Nicol state. Alternatively, by installing the device in a crossed Nicols state and measuring the reflectances R _x and R _y , (Expression 10)
From Equations (7) and (8), the gap d of the reflective liquid crystal panel is obtained.
Can be detected.

As a measuring device for measuring the reflectance of the liquid crystal panel, for example, a measuring device as shown in FIGS. 4 and 5 can be used. Hereinafter, a method of detecting a gap in a liquid crystal panel according to the second embodiment will be described. First, in the measuring apparatus shown in FIGS. 4 and 5, the transmission axis directions of the analyzers 14 and 24 are arranged substantially parallel to the polarization direction of the incident light (parallel Nicols), and the output signals (detected light amounts) of the detectors 15 and 25 are obtained. ) Is measured. Then, the reflectance _Rx is calculated based on the measured output signals of the detectors 15 and 25 and the amounts of light emitted from the light sources 10 and 21. Next, the transmission axis directions of the analyzers 14 and 24 are arranged substantially perpendicular to the polarization direction of the incident light (crossed Nicols), and the output signals of the detectors 15 and 25 (received light amounts).
Is measured. Then, the reflectance _Ry is calculated based on the measured output signals of the detectors 15 and 25 and the amounts of light emitted from the light sources 10 and 21. Further, the gap d between the reflective liquid crystal panels 13 and 23 is calculated using the reflectances R _x and R _y and (Equation 10), (Equation 7) and (Equation 8). In the case of using the gap detection method of the liquid crystal panel of the second embodiment, the same changes, additions, and additions as in the case of using the gap detection method of the first embodiment are made to the measurement apparatus of FIGS. Deletion is possible.

In the liquid crystal panel gap detecting method according to the second embodiment, the gap of the liquid crystal panel is accurately detected by a very simple method of detecting the reflectance in the state of the parallel Nicols and the state of the cross Nicols. be able to. In addition, since it is not necessary to rotate the liquid crystal panel (sample), using a surface-type imaging device such as a CCD as a detector makes it possible to easily perform a check operation and a selection operation of a place where a gap is detected. Further, the two-dimensional distribution of the gap of the liquid crystal panel can be easily detected by using the surface type image sensor as the detector. Here, since the reflectances _Rx and _Ry have a relationship of [ _Rx + _Ry = 1], the gap d can be detected by only one of the measurements. However, since the amount of noise is included in the output signal of the detector at the time of actual measurement, the relationship between the detected _Rx and _Ry is not always [ _Rx + _Ry = 1]. Therefore, in order to measure accurately, it is desirable to detect both the reflectances _Rx and _Ry .

The method for detecting the gap of the liquid crystal panel using (Equation 10) has the following problems. One problem is that when the reflectances R _x = 1 and R _y = 0,
[Sin ² β _eff = 0] (that is, Δn _eff d = m · λ)
/ 2, m: integer) in which the _{^{or, [sin 2 2 (φ app}} + α
ⁱⁿ ) = 0] (that is, φ _app + α ⁱⁿ = m · λ / 2,
m: an integer). However, in the case of [sin ² β _eff = 0], R _x = 1 and R _y = 0 are always obtained even when the reflective liquid crystal panel is rotated, whereas [sin ² (φ _app + α ⁱⁿ ) = 0]. In this case, the reflectance changes when the reflective liquid crystal panel is rotated.
Therefore, by rotating the reflective liquid crystal panel,
[Sin ² β _eff = 0] or [sin ² (φ _app +
α ⁱⁿ ) = 0] can be distinguished.

Another problem is that since Equation (10) is represented by a trigonometric function, there are a plurality of solutions in the gap d. FIG. 6 shows the same conditions (Δn = 0.0
66, φ = 70 °, α ⁱⁿ = 0 °) show the results of calculating the reflectances R _x and R _y . From FIG. 3, it can be seen that the solution (gap d) becomes closer under the condition that one of the reflectances R _x and R _y is close to 0 and the other is close to 1, and it is difficult to distinguish between them (d = FIG. 6). Around 3 μm). Although this is rarely the case, three types of solutions are described below. A first solution is to rotate a reflection type liquid crystal panel (sample) before measurement. As a result, the gap value where one of the reflectances R _x and R _y is close to 0 and the other is close to 1 is shifted, so that the gap d can be accurately detected. Even when this method is used, it is not necessary to rotate the reflective liquid crystal panel when detecting a gap. In the second solution, the reflectance R _xy is further set in a state where the transmission axis direction of the analyzer is set on a bisector of the parallel Nicol direction and the cross Nicol direction (a direction at 45 ° to each direction). Is a method of measuring Here, the reflectance R _xy is expressed as in (Equation 9) to (Equation 11).

[Equation 11] (Equation 11) The measurement becomes difficult when _Rx or _Ry is close to 0 because
This is because two gaps d satisfying the condition exist in a close range (d = about 3 μm in FIG. 6). Under these conditions, R _xy does not become an extreme value (it changes monotonically),
By measuring R _xy , it is possible to determine which of the two gaps d existing in a close range is a true value.
By Rx, Ry, and Rxy, (Equation 11), (Equation 10),
The gap of the liquid crystal panel is detected using (Equation 7) and (Equation 8). A third solution is to provide a light source or a detector with a wavelength selection function to change the wavelength of light used for measurement. Since the reflectances R _x and R _y are functions of the wavelength λ, for example, when R _y = 0 when the light has a certain wavelength, it is possible to make R _y ≠ 0 by changing the wavelength of the light. By doing so, the gap of the liquid crystal panel can be accurately detected.

[Third Embodiment] In the above description, a case has been described in which the amount of noise contained in the output signal of the detector (light-receiving amount detector) is small. However, when the amount of noise contained in the output signal of the detector is large, the detection accuracy of the gap of the reflective liquid crystal panel is reduced. In this case, it is necessary to detect the gap of the reflection type liquid crystal panel in consideration of the amount of noise included in the output signal of the detector.

Hereinafter, a method for detecting the gap of the reflection type liquid crystal panel in consideration of the amount of noise will be described. First, a method of detecting the gap of the reflective liquid crystal panel in consideration of the amount of noise by measuring the output signal of the detector in a state of parallel Nicols and a state of cross Nicols at a plurality of installation angles will be described. In the measuring apparatus shown in FIGS. 4 and 5, the angle between the orientation direction of the liquid crystal molecules on the substrate on the incident light side and the deflection direction of the incident light is the installation angle α.
^The reflective liquid crystal panels 13 and 23 are arranged so as to be ⁱⁿ ₁ . Then, the transmission axis directions of the analyzers 14 and 24 are arranged substantially parallel to the polarization direction of the incident light (parallel Nicol state), and the output signals (light reception amounts) I _x1 of the detectors 15 and 25 are measured. Further, the transmission axis of the analyzer 14, 24 are arranged substantially at right angles to the polarization direction of the incident light (crossed Nicol state), the output signal (received light quantity) of the detector 15, 25 measures the I _y1. Next, the reflective liquid crystal panels 13 and 23 are rotated about an axis substantially parallel to the incident direction of the incident light, and the angle between the orientation direction of the liquid crystal molecules on the substrate on the incident light side and the deflection direction of the incident light is adjusted. Is an installation angle α ⁱⁿ ₂ . Then, the output signals I _x2 of the detectors 15 and 25 in the state of parallel Nicols are measured. Further, the detector 15 in a crossed Nicols state,
25 output signals I _y2 are measured.

The measured output signals 1 _x1 , I _y1 , I _x2 , I _y2
When, a reflectance R _x1, R _y1 at installation angle alpha ⁱⁿ _1, reflectance R _x2, R _y2 at installation angle alpha ⁱⁿ ₂ are in a relationship of (Equation 12). I _x1 = (I ₀ · R _x1 + I _cx ) t _x I _y1 = (I ₀ · R _y1 + I _cy ) t _y I _x2 = (I ₀ · R _x2 + I _cx ) t _x I _y2 = (I ₀ · R _y2 + _Icy ) t _y (Equation 12) Reflectances R _x1 , R _x2 , R _y1 , R at installation angles α ⁱⁿ ₁ and α ⁱⁿ _2
y2 is a function of the gap d of the reflective liquid crystal panel,
It is represented by (Equation 10). t _x and t _y are transmittances of the half mirror 12 with respect to polarized light in a direction substantially parallel to the polarization direction of the incident light and polarized light in a direction orthogonal thereto. As shown in FIG. 5, when the half mirror is not used, t _x and t _y are 1. I _cx and I _cy are a noise light amount in a direction substantially parallel to the polarization direction of the incident light and a noise light amount in a direction substantially orthogonal to the polarization direction. From (Equation 12) and (Equation 10),
The gap d between the reflective liquid crystal panels 13 and 23, the amount of incident light I ₀ , and the amounts of noise I _cx and I _cy can be detected.

As described above, the output signals 1 _x1 of the detector at two installation angles α ⁱⁿ ₁ and α ⁱⁿ ₂ of the reflection type liquid crystal panel,
By measuring I _y1 , I _x2 , and I _y2 , the gap of the reflective liquid crystal panel can be detected in consideration of the amount of noise. Therefore, the gap d of the reflective liquid crystal panel
Can be detected with high accuracy.

In order to detect the gap d with higher accuracy, it is preferable to measure the output signals of the detector at three or more installation angles. Then, based on the measured output signal, the gap d, the amount of incident light I _0, and the amounts of noise I _cx and I _cy are determined by fitting using, for example, (Equation 13). I _x (α ⁱⁿ ) = [I ₀ · R _x (α ⁱⁿ ) + I _cx ] t _x I _y (α ⁱⁿ ) = [I ₀ · R _y (α ⁱⁿ ) + I _cy ] t _y (Equation 13) , I _x (α ⁱⁿ ) and I _y (α ⁱⁿ ) are the states of parallel Nicols at the installation angle α ⁱⁿ of the reflective liquid crystal panel, respectively.
It is an output signal of a detector in a state of cross Nicol.
R _x (α ⁱⁿ ) and R _y (α ⁱⁿ ) are the reflectance ⁱⁿ the parallel Nicol state and the cross Nicol state at the installation angle α ⁱⁿ of the reflective liquid crystal panel, respectively.

The transmittances t _x and t _y of the half mirror are measured, for example, using the method described in “Example 3” described later. When measuring the output signal of the detector with three or more installation angle, the transmittance t _x of the half mirror, one of t _y is a variable, the gap d, the amount of incident light I _0, the noise light quantity I _cx, I _cy, the transmittance t _x of the half mirror, one of t _y may be determined by fitting. In this case, the other of the transmittances t _x and t _y of the half mirror (the one not used as a variable) is determined arbitrarily (for example, 1). (Equation 1
Instead of (3), using (Equation 14) equivalent to (Equation 13), the gap d, the amount of incident light I _0, and the amounts of noise I _cx , I _cx
You can also ask for _cy . I _x (α ⁱⁿ ) = I _{0x ×} R _x (α ⁱⁿ ) + I ′ _cx I _y (α ⁱⁿ ) = I _0y × R _y (α ⁱⁿ ) + I ′ _cy I ′ _cx = I _{cx ×} t _x I ′ _{cy = I cy · t y I 0x} = I 0 · t x I 0y = I 0 · t y ( formula 14) in addition, I _x (alpha ⁱⁿ⁾ (formula 13) or (expression 14),
A common noise light amount (dark light amount of the detector) may be added to each of I _y (α ⁱⁿ ). In such a case, for example, an output signal of the detector is measured in a state where the detector is closed by a shutter, and the measured output signal is used as a dark light amount of the detector. Then, the amount of dark light is subtracted from the output signal of the detector. In order to accurately detect the gap of the reflective liquid crystal panel, it is preferable that the installation angles of the reflective liquid crystal panels are different from each other by 5 ° or more.

When measuring the output signal of the detector by changing the installation angle of the reflection type liquid crystal panel, the two-dimensional distribution of the gap of the reflection type liquid crystal panel is measured by using a surface type imaging device such as a CCD as the detector. Difficult to detect. When detecting the two-dimensional distribution of the gap of a reflective liquid crystal panel using a surface-type image sensor such as a CCD as a detector, it is necessary to fix the installation angle of the reflective liquid crystal panel and measure the output signal of the detector There is. In this case, the amount of incident light I _0, the noise light quantity I _cx, I _cy, the transmittance t _x of the half mirror, obtained in advance t _y and the like. For example, a plurality of reflective liquid crystal panels having different gaps are prepared, and the output signals of the detector in the parallel Nicol state and the cross Nicol state are measured at different installation angles. Using the measured output signal of the detector, the amount of incident light I _O and the amount of noise I
_cx, I _cy, the transmittance t _x of the half mirror, obtaining the t _y. Next, the installation angle of the reflection type liquid crystal panel to be detected is fixed, and the output signals of the detector in the state of parallel Nicols and the state of cross Nicols are measured. Then, using the measured output signal of the detector, the amount of incident light I _O , the amounts of noise I _cx and I _cy , and the transmittance t _x and t _y of the half mirror, which have been obtained in advance, for example, The gap of the reflective liquid crystal panel is calculated by one or two equations. In this case, the installation angle of the reflective liquid crystal panel to be detected may be fixed, and the output signal of the detector in one of the parallel Nicol state and the cross Nicol state may be measured. Detecting the gap of the reflective liquid crystal panel based on the output signal of the detector in the state of the parallel Nicols and the state of the cross Nicols allows the gap to be detected with higher accuracy.

Alternatively, a plurality of reflective liquid crystal panels having different gaps are prepared, and the output signals of the detector are measured at different installation angles in a parallel Nicol state and a cross Nicol state. Using the measured output signal of the detector, the noise light _amounts I _cx and I _cy and the transmittances t _x and t _y of the half mirror are obtained by, for example, (Equation 12). Next, the installation angle of the reflection type liquid crystal panel to be detected is fixed, and the output signals of the detector in the state of parallel Nicols and the state of cross Nicols are measured. Then, using the measured output signal of the detector, the noise light _amounts I _cx and I _cy obtained in advance, and the transmittances t _x and t _y of the half mirror, for example, the two expressions before or after the expression (12) Calculate the gap of the reflective liquid crystal panel by the following two equations. In this case, the gap d and the amount of incident light I
_An expression containing ₀ is obtained.

The method for obtaining the noise light _amounts I _cx and I _cy is a method for obtaining from the detector output signals in the parallel Nicol state and the cross Nicol state at a plurality of installation angles of the reflective liquid crystal panel to be detected. Not limited. For example, constituent materials such as glass, electrodes, alignment films, and liquid crystals are in a parallel Nicol state and a cross Nicol state at a plurality of installation angles of a reflective liquid crystal panel that is the same as the reflective liquid crystal panel to be detected. It is also possible to use a method of obtaining from the output signal of the detector.

An example of a method for detecting the amount of noise will be described. The noise light amount has a component of surface reflected light generated on the surface of the glass substrate of the reflective liquid crystal panel, and a component due to external light, stray light, and the like. When linearly polarized light enters the reflective liquid crystal panel, linearly polarized surface reflected light having the same polarization direction as the incident light is reflected. Therefore, the amount of noise in the parallel Nicol state includes surface reflected light and external light / stray light. On the other hand, the amount of noise in the crossed Nicols state includes only external light and stray light.

Then, the amount of noise can be detected by the following method. First, a sample in which the same glass substrate as the reflective liquid crystal panel to be detected is provided on a light absorbing material such as black glass or a black velvet sheet is prepared. Then, using the sample, measuring the output signal I _x of the detector under the condition the reflectance R _x is almost 0 in the parallel Nicol condition. In this case, since the reflectance _{Rx is} almost 0, the first expression of (Expression 13) becomes (Expression 15). The output signal I _x at this time of the detector indicates the noise amount whose main component surface reflected light. I _x = I _cx · t _x (Equation 15) From this (Equation 15), the noise light amount I _cx can be obtained.

Next, a sample having no birefringence in the incident direction of the incident light (for example, a metal reflector such as aluminum or silver) or the same glass as the reflection type liquid crystal panel to be detected is placed on the metal reflector. Prepare a sample on which the substrate is placed. Then, using the sample, measuring the output signal I _y of the detector under the condition that the reflectivity R _y is almost 0 in a cross nicol state. In this case, since the reflectance R _{y is} almost 0, (Expression 1)
The second equation of 3) is (Equation 16). The output signal I _y at this time of the detector indicates the noise amount mainly composed of external light. I _y = I _cy · t _y (Equation 16) From this (Equation 16), the noise light amount I _cy can be obtained. Note that the noise light amount _{Icy in} the state of crossed Nicols is
It can also be determined from the output signal of the detector in a crossed Nicol state in a state where no sample is installed.

When the noise light _amounts I _cx and I _cy are obtained,
The variable in (Equation 14) is the gap d of the reflective liquid crystal panel.
And the amount of incident light I ₀ . Therefore, the gap d of the reflective liquid crystal panel can be obtained from the detector output signals I _x and I _y in the parallel Nicols state and the cross Nicols state at one installation angle.

The amount of noise I _{cx in} the state of parallel Nicols can be treated as a function of the amount of incident light I ₀ as follows. Noise quantity I _cx in the parallel Nicol condition is the amount of surface reflected light When I _s, (Equation 1
7). _{I cx = I s + I cy} ( Equation 17) the reflectivity R _s of the glass substrate surface of the liquid crystal panel, the refractive index of air n _a (= 1), represented by using the refractive index n _g of the glass (equation 18) It is. _{R s = I s / (I} 0 + I s) = (n a -n g) 2 / (n a + n g) 2 ( Equation 18) (Equation 17), from (Equation 18), in the state of parallel Nicols The noise light amount I _cx is represented by (Equation 19). I _cx = R _s · I ₀ / (1−R _s ) + I _cy (Equation 19) The noise light amount I _cy is separately obtained by, for example, (Equation 16). As a result, two variables in (Equation 13) are the gap d and the amount of incident light I ₀ . Therefore,
At one installation angle, the gap d of the reflective liquid crystal panel can be obtained from the output signals I _x and I _y of the detector in the state of parallel Nicols and the state of cross Nicols.

[0042] In the above, the output signal I _x of the detector by installing the analyzer to the parallel Nicol condition is measured, it was measured output signal I _y of the detector by installing the analyzer to the state of crossed Nicols , I _x , and I _y can be measured simultaneously. FIG. 8 shows a measuring device capable of simultaneously measuring I _x and I _y . The measuring device shown in FIG. 8 uses a polarization beam splitter instead of an analyzer and uses a plurality of detectors. In the measuring device shown in FIG. 8, light from a light source 50 is linearly polarized by a polarizer 51 and then applied to a half mirror 52. The light reflected by the half mirror 52 travels almost parallel to the normal of the reflective liquid crystal panel (sample) 53 and enters the reflective liquid crystal panel 53. The light reflected by the reflective liquid crystal panel 53 is transmitted through the half mirror 52 and emitted to the polarization beam splitter 54. The polarization beam splitter 54 converts, from the incident light, light having a polarization direction substantially parallel to the polarization direction of the polarizer 51 (the polarization direction of the incident light of the reflective liquid crystal panel 53) and polarization substantially orthogonal to the polarization direction of the polarizer. Separate light with direction. Reflective liquid crystal panel 53 radiated from polarization beam splitter 54
The amount of light having a polarization direction substantially parallel to the polarization direction of the incident light is detected by the first detector 55, and the reflection type liquid crystal panel 5
The amount of light having a polarization direction substantially orthogonal to the polarization direction of the third incident light is detected by the second detector 56. Note that depending on the configuration of the polarization beam splitter 54, the first detector 5
5, the amount of light having a polarization direction substantially orthogonal to the polarization direction of the incident light is detected, and the second detector 56 may detect the amount of light having a polarization direction substantially parallel to the polarization direction of the incident light. is there.

[0043] In the measuring apparatus shown in FIG. 8, substantially orthogonal to the polarization direction of the detection (detection at the parallel Nicol state) between the incident light quantities I _x of light having substantially parallel polarization direction as the polarization direction of the incident light The detection of the amount _Iy of light having the polarization direction (detection in the state of crossed Nicols) can be performed without changing the installation state of the analyzer. Therefore, I _x and I _y can be detected easily and in a short time. Detected I _x ,
Based on I _y, it is possible to detect the gap of the reflective liquid crystal panel in the above-described method.

As the light source, a plurality of light sources having different wavelengths can be used. In the measuring device shown in FIG.
Two light sources 60 and 61 having different wavelengths are used as light sources. In the measuring apparatus shown in FIG. 9, the light from the light source 60 is linearly polarized by the polarizer 62 and then applied to the half mirror. The light from the light source 60 is linearly polarized by the polarizer 63 and then applied to the half mirror 65. Other configurations are the same as those of the measuring apparatus shown in FIG. Polarizer 62
And the polarizer 63 have the same polarization direction. In the measuring apparatus shown in FIG. 9, light of different wavelengths can be applied to the reflective liquid crystal panel 66 by selectively operating the light source 60 or the light source 61. This makes it easy
The amount of light reflected by the reflective liquid crystal panel can be detected in a short time by using light having different wavelengths.

An example in which a gap of a sample is detected using the method and the apparatus for detecting a gap of a liquid crystal panel of the present invention will be described below. The following samples were manufactured as the first sample of the reflection type liquid crystal panel. First, a polyimide film is spin-coated on each of two glass substrates so as to have a thickness of about 70 nm. Next, the surface is rubbed (rubbed) in one direction with a nylon cloth, and an adhesive mixed with resin beads having a diameter of 4 μm is applied to the polyimide film side of one of the substrates. Then, the two glass substrates are opposed to each other such that the polyimide film is on the inside, and the two substrates are bonded so that the directions in which the polyimide films are rubbed are orthogonal to each other. Next, liquid crystal was injected by capillary action to produce a transmissive TN liquid crystal panel (twist angle φ =
90 °). Similarly, rubbing was performed so that the twist angle φ = 240 °, bonded using resin beads having a diameter of 7 μm, and liquid crystal was injected by capillary action to produce a transmission type STN liquid crystal panel. When the gap d of these transmissive liquid crystal panels was measured by the SPM method (Japanese Patent Application Laid-Open No. 10-153780), d = 3.
87 μm, d = 6.44 μm for transmissive STN liquid crystal panel
m was obtained. The reflection mirror produced by sputtering Al on a glass substrate is used for the transmission type TN liquid crystal panel and the transmission type STN.
A reflective TN liquid crystal panel and a reflective STN liquid crystal panel were mounted on one side of the liquid crystal panel. The gap d of the samples of these reflective liquid crystal panels was detected by the following method.

"Experimental example 1" A reflection type polarizing microscope ("OPTIPHOT2-" manufactured by Nikon) having an optical system as shown in FIG.
A monochromatic band-pass filter (center wavelength: 550 nm) 32 is attached to the epi-illumination light source 31 side of the “POL” and the universal epi-illumination light source is attached. Adjusted to be in a state. At this time, the transmitted illumination light source 40 is turned off. Further, the polarization direction of the incident light was set to a direction parallel to the paper surface of FIG. Next, a sample (reflective liquid crystal panel) 35 was placed on a sample table (which can be manually rotated) with the reflecting mirror side facing down. At this time, the sample was set so that the alignment direction of the liquid crystal on the incident light side (upper substrate side) coincided with the polarization direction of the incident light. Next, while visually checking the field of view of the reflection type polarizing microscope, the sample was rotated together with the sample stage, and the angle at which the field of view became darkest, that is, the extinction angle at which the reflectance became minimum was measured. When the gap d of the sample was calculated from the measured extinction angle and (Equation 8), d = 3.86 μm for the TN liquid crystal panel and d = 6.58 for the STN liquid crystal panel.
μm was obtained.

In the same manner as in "Experimental example 2", the sample rotation angle (extinction angle) at which the output signal (light reception amount) of the detector 37 (using a photomultiplier) was minimized was measured. Then, when the gap d of the sample was calculated from the measured extinction angle and (Equation 8), d = 3.86 μm and ST for the TN liquid crystal panel.
In the N liquid crystal panel, d = 6.62 μm was obtained.

Experimental Example 3 Next, the epi-illumination light source 31 was turned off, and the transmission illumination light source 40 was turned on. Then, a bandpass filter for monochromatization (center wavelength 5
50 nm) 41, and the polarizer 4 on the side of the transmitted illumination light source
3 and the analyzer 36 were adjusted so as to be in a parallel Nicol state. At this time, the polarization direction of the incident light was set to a direction parallel to the paper surface of FIG. Next, the output signal I _x0 of the detector 37 was measured with only the sample of the reflection type liquid crystal panel placed on the sample stage. If the transmittance of the half mirror 34 to the incident light t _x, the amount of transmitted illumination light source and I _t, I _x0 =
a _{t x} · I t. Next, the polarizer 43 and the analyzer 36 on the transmission illumination light source side were rotated by 90 °, respectively, and the output signal I _x0 of the detector 37 was measured. Assuming that the transmittance of the half mirror to the incident polarized light rotated by 90 ° is t _y , I _y0 = t _y ·
The I _t. Next, the transmission illumination light source 40 was turned off and the epi-illumination illumination light source 31 was turned on. Then, a band pass filter for monochromaticization (center wavelength: 550 nm) 32 was attached to the epi-illumination light source side, and the polarizer 33 and the analyzer 36 on the epi-illumination light source side were adjusted to be in a parallel Nicol state. At this time,
The polarization direction of the incident light was set in a direction parallel to the plane of FIG. Next, the sample 35 of the reflection type liquid crystal panel was set such that the alignment direction of the liquid crystal on the incident light side (upper substrate side) coincided with the polarization direction of the incident light. In this state, it was measured output signal I _x of the detector 37. If the amount of the epi-illumination light source 31 and I _r, the _{I x = R x · t x} · I r. Next, the analyzer 36
The rotate 90 °, it was measured output signal I _y of the detector 37. If the amount of落照illumination light source 31 and I _r, I _y = _{R y}
T _y · I _r . Next, the measured I _x , I _x0 , I _y , I
_The reflectances R _x and R _y were calculated using _y0 and (Equation 12), and the calculated reflectances R _x and R _y were fitted with (Equation 10) to calculate the gap d of the sample 35. As a result, in the TN liquid crystal panel, d = 3.87 μm, STN
In the liquid crystal panel, d = 6.60 μm was obtained.

[0049]

(Equation 12) (Equation 20)

The following samples were prepared as the second sample of the reflection type liquid crystal panel. First, an alignment film varnish “AL3000” for liquid crystal display manufactured by JSR is applied to one surface of each of two glass substrates by spin coating. After the application, baking is performed to form a polyimide film having a thickness of about 70 nm. Next, the polyimide film surface is rubbed with a rayon velvet cloth, and an adhesive mixed with resin beads having a diameter of 3.0 μm is applied to one of the glass substrates on the polyimide film side. Next, the two glass substrates are opposed to each other so that the polyimide film is on the inside, and are bonded so that the rubbing direction has an angle of 70 °. Next, wavelength 5
A liquid crystal having a birefringence Δn of 0.070 at 50 nm is injected by a capillary phenomenon, and a transmissive TN liquid crystal panel (having a twist angle φ
= 70 °). The gap of this transmissive TN liquid crystal panel is measured by Otsuka Electronics' gap measuring device "RETS".
As a result, a gap d = 2.94 μm was obtained by a rotation analyzer method. Next, a reflective plate made by sputtering aluminum was attached to one side of the transmissive TN liquid crystal panel to produce a reflective TN liquid crystal panel. The gap d of the reflective TN liquid crystal panel was detected by the following method.

"Experimental Example 4" For detection of the gap, a reflection type polarizing microscope having an optical system as shown in FIG. 7 (a Nikon "OPTIPHOT2-POL" fitted with a universal epi-illumination light source) was used. Epi-illumination light source 31
The band pass filter for monochromatization (center wavelength 550n)
m) By attaching 32, the measurement wavelength is set to 550.
nm. The polarizer 33 on the side of the epi-illumination proof light source 31 was adjusted so that the polarization direction to the sample was perpendicular to the paper surface. The reflective liquid crystal panel 35 of the sample was set such that the orientation direction of the liquid crystal on the incident light side (upper substrate side) coincided with the polarization direction of the incident light. Next, the epi-illumination light source 31 is turned on (the transmission illumination light source 40 is turned off), and the polarizer 33 and the analyzer 36 on the epi-illumination light source side are in a parallel Nicol state.
The output signal I _x1 of the detector 37 was measured. Subsequently, the analyzer 36 was rotated 90 ° to be in a crossed Nicols state, and the output signal I _y1 of the detector 37 in the crossed Nicols state was measured. Next, the reflective liquid crystal panel 35 of the sample was rotated clockwise by 5 ° when viewed from the incident direction of the incident light, and the angle between the polarization direction of the incident light and the orientation direction of the liquid crystal on the incident light side was set to 5 °. Then, in the same procedure as described above, the output signal I of the detector 37 in the state of parallel Nicols and the state of cross Nicols
_x2 and _Iy2 were measured. Next, the reflective liquid crystal panel 3 of the sample
5 was further rotated 5 ° clockwise. Then, the output signals I _x3 and I _y3 of the detector 37 in the parallel Nicol state and the cross Nicol state were measured in the same procedure as described above. Next, the reflection type liquid crystal panel 35 of the sample was further rotated by 5 °.
Rotated clockwise. Then, in the same procedure as above,
The output signals I _x4 and I _y4 of the detector 37 in the state of parallel Nicols and the state of cross Nicols were measured. Then, the output signal _{I x1, I y1 ~I x4 ~I} y4 measured, by fitting using Equation (13), the gap d, the amount of incident light I _0, the noise light quantity I _cx, I _{c y} , Half mirror 34
Was determined transmittance t _x, transmission t _y of the half mirror 34 was fixed to 1. The resulting gap d was 2.95 μm.

"Experimental Example 5" In Experimental Example 4, the reflection type liquid crystal panel 35 as a sample was rotated by 5 °, and the detectors 37 in the parallel Nicol state and the cross Nicol state at four installation angles in all were installed. Was measured. In Experimental Example 5, the output signal of the detector 37 in the parallel Nicol state and the cross Nicol state was measured at one installation angle.
That is, the reflection type liquid crystal panel 35 as a sample is arranged so that the orientation direction of the liquid crystal on the incident light side coincides with the polarization direction of the incident light, and the detector 37 in the parallel Nicol state and the cross Nicol state at that time. The output signals I _x1 and I _y1 were measured. Next, a reflective liquid crystal panel 35 removed, using a black glass as a sample in place was measured output signal I _x of the detector 37 in the state of parallel Nicols. And
The output signal I _x, measured using transmittance t _x and the half mirror 34 obtained in Experimental Example 4 (Formula 15) was determined noise quantity I _cx. Next, using an aluminum reflector had been attached to the reflective liquid crystal panel 35 as a sample was measured output signal I _y of the detector 37 in a cross-Nicol state. In Experimental Example 4, since the transmittance t _y of the half mirror 34 was fixed at 1, the measured output signal I _y was used as the noise light amount I _cy from (Equation 17). Next, the transmittance t _x of the half mirror 34 obtained in Experimental Example 4, the transmittance t _y of the half mirror 34 fixed at 1, the noise light _amounts I _cx and I _cy obtained in the above procedure, and the measured output signal I _x1 , I _y1 by using (Equation 13) to determine the gap d and the amount of incident light I ₀ . The resulting gap d was 2.96 μm.

The method and apparatus for detecting a gap in a liquid crystal panel of the present invention are not limited to the configuration described in the embodiment, and various changes, additions, and deletions can be made without departing from the spirit of the present invention. The liquid crystal panel gap detecting device according to the present invention includes a measuring device and a processing device that processes an output signal of the measuring device to calculate a gap of the liquid crystal panel. An invention described in a claim as a method or an apparatus can also be described as an invention in an apparatus or a method.

[0054]

As described above, the gap detecting method for a liquid crystal panel according to any one of claims 1 to 9 and claim 1.
With the use of the liquid crystal panel gap detecting device according to the present invention, the gap of the liquid crystal panel can be easily detected in a short time with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a coordinate system and an alignment direction of liquid crystal molecules.

FIG. 2 is a diagram showing a result of calculating an extinction angle based on a gap of a liquid crystal panel.

FIG. 3 is a diagram illustrating a result of calculating a retardation of a liquid crystal panel based on a gap of the liquid crystal panel.

FIG. 4 is a diagram showing an example of a measuring device used in the method for detecting a gap of a liquid crystal panel of the present invention.

FIG. 5 is a diagram showing another example of the measuring device used in the liquid crystal panel gap detecting method of the present invention.

FIG. 6 is a diagram showing calculation results of reflectance in a state of parallel Nicols and a state of cross Nicols.

FIG. 7 is a diagram showing another example of the measuring device used in the liquid crystal panel gap detecting method of the present invention.

FIG. 8 is a diagram showing another example of a measuring device used in the method for detecting a gap of a liquid crystal panel of the present invention.

FIG. 9 is a diagram showing another example of a measuring device used in the method for detecting a gap of a liquid crystal panel of the present invention.

[Explanation of symbols]

 10, 21, 31, 40, 50, 60, 61 Light source 11, 22, 33, 43, 51, 62, 63 Polarizer 12, 34, 52, 65 Half mirror 13, 23, 35, 53, 66 Reflective liquid crystal Panel 14, 24, 36 Analyzer 15, 25, 37, 55, 56, 68, 69 Detector 32, 41 Bandpass Filter 42 Mirror 54, 67 Polarizing Beam Splitter

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuya Satake 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Takahiro Nishioka 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Ryo Denki Co., Ltd. (72) Susumu Sato, Inventor, 4-7-7, Yashihashihonmachi, Akita City, Akita Prefecture (72) Inventor Toshiaki Maehara F-term (reference) 2F065 AA22 CC00 DD06 FF04 GG06 GG07 HH08 JJ03 JJ26 LL22 LL33 LL34 LL37 2H088 FA12 FA30 MA17

Claims (19)

[Claims] 1. A method for detecting a gap in a liquid crystal panel, wherein polarized incident light is incident substantially parallel to a normal line of the liquid crystal panel,
Arranging the liquid crystal panel such that the reflected light from the liquid crystal panel is received by the light receiving amount detector through an analyzer having a transmission axis substantially orthogonal to the polarization direction of the incident light; Rotating the polarization direction relative to the transmission axis direction of the analyzer to detect an extinction position angle at which the intensity of light detected by the received light amount detection device is minimized, and based on the detected extinction position angle Detecting the gap of the liquid crystal panel by using the method. 2. The method for detecting a gap in a liquid crystal panel according to claim 1, wherein the liquid crystal panel is rotated about an axis substantially parallel to the incident direction of the incident light, thereby polarizing the incident light on the liquid crystal panel. A gap detection method for a liquid crystal panel in which the direction and the transmission axis direction of the analyzer are relatively rotated. 3. A method for detecting a gap in a liquid crystal panel, wherein polarized incident light is incident substantially parallel to a normal line of the liquid crystal panel,
Arranging the liquid crystal panel so that the reflected light from the liquid crystal panel is received by the light receiving amount detection device via the analyzer; and receiving the light with the transmission axis of the analyzer being substantially parallel to the polarization direction of the incident light. Detecting a first output signal from the detection device; detecting a second output signal from the light reception amount detection device in a state where a transmission axis of the analyzer is substantially orthogonal to a polarization direction of the incident light; Detecting a gap in the liquid crystal panel based on the first and second output signals. 4. The method for detecting a gap in a liquid crystal panel according to claim 3, wherein the transmission axis of the analyzer is positioned on a bisector in a direction substantially parallel to the polarization direction of the incident light and in a direction substantially orthogonal to the polarization direction of the incident light. Detecting a third output signal from the received light amount detecting device in the state where the liquid crystal panel is in a closed state.
A method for detecting a gap in a liquid crystal panel based on second and third output signals. 5. The liquid crystal panel gap detecting method according to claim 3, wherein the step of detecting the first output signal and the step of detecting the second output signal include the steps of: A step of performing the rotation at at least two different rotation positions about an axis substantially parallel to the direction, wherein the step of detecting the gap of the liquid crystal panel includes the steps of: outputting the first and second output signals detected at each rotation position; A method for detecting a gap in a liquid crystal panel based on the detected gap. 6. The method for detecting a gap in a liquid crystal panel according to claim 5, wherein each angle is different by 5 ° or more. 7. The method for detecting a gap in a liquid crystal panel according to claim 3, wherein the light from the light source is reflected by a half mirror and is incident on the liquid crystal panel, and the reflected light from the liquid crystal panel is transmitted through the half mirror. In the step of detecting the gap of the liquid crystal panel, first,
A gap detecting method for a liquid crystal panel, wherein a gap of a liquid crystal panel is detected based on a second output signal, a previously obtained light amount of noise, and transmittance of a half mirror. 8. The method for detecting a gap in a liquid crystal panel according to claim 3, wherein light from a light source is reflected by a half mirror to be incident on the liquid crystal panel, and reflected light from the liquid crystal panel is transmitted through the half mirror. In the step of detecting the gap of the liquid crystal panel, first,
A gap detection method for a liquid crystal panel, wherein a gap of a liquid crystal panel is detected based on a second output signal and a previously obtained amount of incident light, a noise light amount, and a transmittance of a half mirror. 9. The method for detecting a gap of a liquid crystal panel according to claim 3, wherein the surface reflected light from the received light amount detection device is detected when the transmission axis of the analyzer is substantially parallel to the polarization direction of the incident light. Detecting a fourth output signal indicating a noise light amount as a main component; and, in a state where a transmission axis of the analyzer is substantially orthogonal to a polarization direction of the incident light, external light from the light reception amount detection device as a main component. Detecting a fifth output signal indicating the amount of noise to be generated. In the step of detecting the gap of the liquid crystal panel,
A gap detecting method for a liquid crystal panel, wherein a gap of a liquid crystal panel is detected based on second, fourth, and fifth output signals. 10. A method for detecting a gap in a liquid crystal panel, comprising: a step of inputting polarized incident light substantially parallel to a normal line of the liquid crystal panel; and a step of inputting reflected light from the liquid crystal panel to a polarizing beam splitter to obtain polarized light. Separating light having a direction substantially parallel to the polarization direction of the incident light and light having a polarization direction substantially orthogonal to the polarization direction of the incident light; and an amount of light having a polarization direction substantially parallel to the polarization direction of the incident light. Detecting the amount of light, the polarization direction of which is substantially orthogonal to the polarization direction of the incident light, with the second light reception amount detection device, Detecting the gap of the liquid crystal panel based on the detection signal and the detection signal of the second light reception amount detection device. 11. A gap detecting device for a liquid crystal panel, comprising: a light emitting device for causing polarized incident light to enter substantially parallel to a normal line of the liquid crystal panel; and a reflected light from the liquid crystal panel; An analyzer arranged substantially orthogonal to the polarization direction, a light-receiving amount detection device that receives light passing through the analyzer, and a processing device, wherein the processing device transmits the polarization direction of the incident light through the analyzer. A gap detection device for a liquid crystal panel that detects a gap of a liquid crystal panel based on an extinction position angle at which an output signal of the light reception amount detection device is minimized when rotated relatively to an axial direction. 12. A gap detecting device for a liquid crystal panel, comprising: a light emitting device for causing polarized incident light to enter substantially parallel to a normal line of the liquid crystal panel; and an analyzer arranged to receive reflected light from the liquid crystal panel. A light-receiving amount detecting device that receives light that has passed through the analyzer; and a processing device. The processing device is configured to detect the light-receiving amount when the transmission axis of the analyzer is substantially parallel to the polarization direction of the incident light. A liquid crystal panel that detects a gap of the liquid crystal panel based on the first output signal of the first embodiment and a second output signal from the light reception amount detection device in a state where the transmission axis of the analyzer is substantially orthogonal to the polarization direction of the incident light. Gap detection device. 13. The gap detecting device for a liquid crystal panel according to claim 12, wherein the light emitting device has a polarizer. 14. The gap detecting device for a liquid crystal panel according to claim 12, wherein the light receiving amount detecting device uses a surface-type imaging device. 15. The gap detecting device for a liquid crystal panel according to claim 12, wherein the light emitting device or the light receiving amount detecting device has a wavelength selecting function. 16. The gap detecting device for a liquid crystal panel according to claim 12, wherein the processing device has a rotation center about an axis substantially parallel to an incident direction of the incident light on the liquid crystal panel. A liquid crystal panel gap detection device that detects a liquid crystal panel gap based on a first output signal and a second output signal at at least two different rotational positions. 17. The gap detecting device for a liquid crystal panel according to claim 12, wherein the processing device has a first output signal, a second output signal, and a transmission axis of the analyzer, the polarization direction of the incident light. A fourth output signal indicating the amount of noise mainly composed of surface reflected light from the received light amount detection device in a state substantially parallel to the light reception amount detection device, and a state in which the transmission axis of the analyzer is substantially orthogonal to the polarization direction of the incident light. A liquid crystal panel gap detecting device for detecting a gap of the liquid crystal panel based on a fifth output signal indicating a noise light amount mainly composed of external light from the light receiving amount detecting device. 18. A gap detecting device for a liquid crystal panel, comprising: a light emitting device for causing polarized incident light to be incident substantially parallel to a normal line of the liquid crystal panel; and a reflected light from the liquid crystal panel; A polarization beam splitter for separating light having a polarization direction substantially parallel to the polarization direction and light having a polarization direction substantially orthogonal to the polarization direction of the incident light; and a polarization direction of the incident light radiated from the polarization beam splitter substantially parallel to the polarization direction of the incident light. A first light-receiving amount detecting device that receives light having a different polarization direction; a second light-receiving amount detecting device that receives light having a polarization direction substantially orthogonal to the polarization direction of the incident light, emitted from the polarization beam splitter; A processing device, wherein the processing device detects a gap of the liquid crystal panel based on a detection signal of the first light reception amount detection device and a detection signal of the second light reception amount detection device. Detection device. 19. A gap detecting device for a liquid crystal panel, comprising: a light emitting device for causing polarized incident light to enter substantially parallel to a normal line of the liquid crystal panel; an analyzer for receiving reflected light from the liquid crystal panel; A light-receiving amount detecting device for receiving the transmitted light; and a processing device, the processing device comprising: a first output from the light-receiving amount detecting device when a transmission axis of the analyzer is substantially parallel to a polarization direction of the incident light; Signal, a second output signal from the light-receiving amount detection device in a state where the transmission axis of the analyzer is substantially orthogonal to the polarization direction of the incident light, and a direction in which the transmission axis of the analyzer is substantially parallel to the polarization direction of the incident light; A gap detection device for a liquid crystal panel that detects a gap of a liquid crystal panel based on a third output signal from a light reception amount detection device in a state of being located on a bisector in a direction substantially orthogonal to the liquid crystal panel.