JP7077199B2 - Optical measuring device and orientation measuring method - Google Patents

Description

The present invention relates to an optical measuring device for measuring the degree of orientation in the manufacture of a polarizing plate, and a method for measuring the degree of orientation.

A polarizing plate that selectively transmits only unidirectional linear polarization is used in an antireflection plate used in an organic electroluminescence display device, a liquid crystal display, and the like.

As an example, the polarizing plate is manufactured as follows.
First, an alignment film is formed on the surface of the base material. Next, a composition containing a rod-shaped liquid crystal compound and a dichroic substance such as a dichroic dye is applied to the alignment film and dried to form a coating film. Next, by heat-treating the coating film, an orientation promoting step (aging step) for orienting the dichroic substance is performed. After the alignment promotion step is completed, the coating film (composition) is cured by irradiation with ultraviolet rays or the like to prepare a polarizing plate.

In such a polarizing plate, it is necessary to increase the degree of orientation in order to obtain a high degree of polarization. For that purpose, it is necessary to measure the degree of orientation of the polarizing plate.
As a device for measuring the degree of orientation (polarization dichroism), for example, Patent Document 1 describes three or more polarizing plates arranged in different polarization directions, an optical sensor opposed to the polarizing plate, and an optical sensor. It has a data processing device that calculates the maximum and minimum values of transmitted light intensity and the polarization direction for those values from the continuous relational expression between the polarization direction, the polarizing plate, and the sample transmitted light intensity with respect to the output. A device for placing a sample between a plate and an optical sensor is described.

Japanese Unexamined Patent Publication No. 6-229909

In order to obtain a polarizing plate with a high degree of orientation, it is necessary to understand the change in the degree of orientation, that is, the molecular behavior in the alignment promotion step. For example, in the case of a polarizing plate using the above-mentioned dichroic substance, it is necessary to grasp the change in the degree of orientation in the orientation promoting step of heat-treating the coating film, that is, the behavior of the dichroic substance.
For that purpose, it is necessary to measure the change in the degree of orientation in the orientation promotion step in real time according to the passage of time.
However, at present, a technique capable of measuring a change in the degree of orientation in real time in an orientation promoting step in the manufacture of a polarizing plate has not been realized.

An object of the present invention is to solve such a problem of the prior art, and an optical measuring device capable of measuring a change in the degree of orientation in an orientation promoting step in the manufacture of a polarizing plate in real time. And to provide a method for measuring the degree of orientation.

In order to solve this problem, the present invention has the following configurations.
[1] A holding unit that holds the measurement target and
A first light irradiation unit that irradiates the holding unit with linear polarization,
A second light irradiation unit that irradiates the holding unit with linear polarization,
The first light receiving part that receives the light emitted by the first light irradiation part across the holding part, and the first light receiving part.
A second light receiving part that receives the light emitted by the second light irradiating part across the holding part, and a second light receiving part.
A spectrophotometer that separates and measures the light received by the first light receiving unit and the second light receiving unit, and a spectrophotometer.
A temperature control means for controlling the temperature of the measurement target held in the holding portion, a stretching means for stretching the measurement target held in the holding portion, and a light irradiation means for irradiating the measurement target held in the holding portion with light. , With at least one, and
The first light irradiation unit and the second light irradiation unit are optical measuring devices that irradiate linearly polarized light whose polarization directions are orthogonal to each other on the holding surface of the measurement target in the holding unit.
[2] The first light irradiation unit and the second light irradiation unit irradiate the holding unit with the P wave, or the first light irradiation unit and the second light irradiation unit irradiate the holding unit with the S wave. 1] The optical measuring device according to the above.
[3] The optical measuring device according to [2], wherein the first light irradiation unit and the second light irradiation unit irradiate the holding unit with P waves.
[4] The optical measuring device according to any one of [1] to [3], which has a temperature controlling means.
[5] The optical measuring apparatus according to any one of [1] to [4], wherein the first light irradiation unit and the second light irradiation unit irradiate the holding unit with linearly polarized light including the entire wavelength range of visible light.
[6] The first light irradiation unit and the second light irradiation unit irradiate the holding portion with linearly polarized light at an angle of 1 ° or more with respect to the perpendicular line of the measurement target held by the holding portion. 5] The optical measuring device according to any one of.
[7] Absorbance from the transmittance calculation means for calculating the transmittance of the light emitted by the first light irradiation unit and the second light irradiation unit from the light measurement result by the spectrophotometer, and the transmittance calculated by the transmittance calculation means. The optical measuring apparatus according to any one of [1] to [6], further comprising an absorbance calculating means for calculating the degree of orientation and an orientation degree calculating means for calculating the degree of orientation from the absorbance calculated by the absorbance calculating means.
[8] The measurement target to be the polarizing plate is the first measurement light which is linearly polarized light in the transmission axis direction or the absorption axis direction of the polarizing plate, and the linear polarization in the axial direction different from the first measurement light of the polarizing plate. The second measurement light is incident, and the first measurement light and the second measurement light transmitted through the measurement target are separated and measured, while the orientation promotion treatment for promoting the orientation is applied to the measurement target. ,
From the measurement results of the first measurement light and the second measurement light transmitted through the measurement target, the transmittance of the first measurement light and the second measurement light with respect to the measurement target is calculated.
From the calculated transmittance, calculate the absorbance of the object to be measured,
A method for measuring the degree of orientation, which comprises calculating the degree of orientation of a measurement target from the calculated absorbance.
[9] A P wave is incident on the measurement target as the first measurement light and the second measurement light, or an S wave is incident on the measurement target as the first measurement light and the second measurement light. 8] The method for measuring the degree of orientation.
[10] The method for measuring the degree of orientation according to [9], wherein a P wave is incident on the measurement target as the first measurement light and the second measurement light.
[11] The method for measuring the degree of orientation according to any one of [8] to [10], wherein at least one of heating and cooling of the measurement target is performed as the orientation promotion treatment.
[12] The method for measuring orientation according to any one of [8] to [11], wherein the first measurement light and the second measurement light include the entire wavelength range of visible light.
[13] The method for measuring the degree of orientation according to any one of [8] to [12], wherein the measurement target is a laminate having a coating film containing a dichroic substance and a rod-shaped liquid crystal compound.
[14] Using a reference sample from which the coating film was removed from the laminate,
In the same manner as the measurement target, the first measurement light and the second measurement light transmitted through the reference sample are measured, and the measurement result of the transmitted light of the reference sample is used to measure the first measurement light and the first measurement light transmitted through the measurement target. The method for measuring the degree of orientation according to [13], wherein the transmittance of the first measurement light and the second measurement light with respect to the measurement target is calculated from the measurement result of the second measurement light.

According to the present invention, the change in the degree of orientation in the alignment promotion step in the manufacture of the polarizing plate can be measured in real time.

It is a figure which conceptually shows an example of the optical measuring apparatus of this invention. It is a conceptual diagram for demonstrating the optical measuring apparatus shown in FIG. It is a conceptual diagram for demonstrating the optical measuring apparatus shown in FIG. It is a conceptual diagram for demonstrating another example of the optical measuring apparatus of this invention. It is a graph which shows an example of the relationship between the processing time of the alignment promotion treatment, and the temperature and the degree of orientation.

Hereinafter, the optical measuring apparatus and the method for measuring the degree of orientation of the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 1 conceptually shows an example of the optical measuring device of the present invention that implements the method of measuring the degree of orientation of the present invention.
The optical measuring device 10 shown in FIG. 1 is a device for measuring the degree of orientation of the sample S held in the holding unit 12, and includes a light irradiation optical system 14, a light receiving optical system 16, a first spectrophotometer 18a, and a first spectrophotometer. It includes a second spectrophotometer 18b, a temperature adjusting means 20, a temperature measuring means 24, a signal generator 26, and a data processing unit 30.

In the present invention, the sample S to be measured is in a state of being subjected to an orientation promoting step (alignment degree imparting step) for promoting orientation in the production of a polarizing plate (polarizer, polarizing film). The sample S is not limited, and various known substances that are subjected to the orientation promotion step in the production of the polarizing plate (straight polarizing plate) can be used. As an example, Sample S having a transparent substrate, an alignment film formed on one surface of the substrate, and a coating film of a composition containing a bicolor substance and a rod-shaped liquid crystal compound formed on the surface of the alignment film. Is exemplified. The dichroic substance is a substance that develops dichroism, such as a dichroic pigment.
Examples of the orientation promoting step include an orientation promoting step by aging that controls the temperature such as heating and cooling, an orientation promoting step by stretching, and an orientation promoting step by light irradiation such as ultraviolet irradiation. Therefore, the sample S includes, in addition to the sample having a coating film containing a compound oriented by heating such as the above-mentioned dichroic dye, a compound oriented by stretching such as a polyvinyl alcohol film containing iodine. Examples thereof include a plastic film and a sample having a coating film containing a photo-oriented compound oriented by light irradiation.
As an example, the optical measuring device 10 of the illustrated example is a device that performs orientation promotion processing on the sample S by controlling the temperature of the sample S, and has a temperature controlling means 20 that heats and / or cools the sample S. ..

The holding portion 12 is a portion for holding the sample S.
There is no limitation on the method for holding the sample S by the holding unit 12, and various known methods for holding the sheet-like material can be used. As the holding portion 12, as an example, a table on which the sample S is placed and held, a frame body that grips the entire circumference of the end portion of the sample S, and a frame body that partially grips the end portion of the sample S and tension is applied. An example is a jig that is held flat. Above all, the table on which the sample S is placed is suitably used as the holding portion 12. In the following description, the table on which the sample S is placed and held is also referred to as a "sample table" for convenience.
Here, as will be described later, the optical measuring device 10 measures the transmitted light of the sample S to measure the degree of orientation. Therefore, it is preferable that the sample table on which the sample S is placed has sufficient transparency with respect to the linear polarization irradiated by the light irradiation optical system 14. As an example, since the optical measuring device 10 preferably calculates the degree of orientation in the entire wavelength range of visible light, a quartz glass sample table is preferably exemplified as a sample table on which the sample S is placed.

The light irradiation optical system 14 is an optical system that irradiates the sample S held by the holding portion 12 with two linear polarizations whose polarization directions are orthogonal to each other on the surface of the sample S.
In the illustrated example, the light irradiation optical system 14 has a light source 34, a first light irradiation unit 36a, and a second light irradiation unit 36b.

The light source 34 is a light source that irradiates a measurement light for measuring the degree of orientation of the sample S.
The light source 34 is not limited, and various known light sources can be used as long as the sample S can irradiate light including the target wavelength range of the corresponding polarizing plate.
That is, when the polarizing plate corresponding to the sample S is used for the purpose of linearly polarizing the entire visible light range, a light source capable of irradiating light including the entire wavelength range of visible light is used. Further, when the polarizing plate corresponding to the sample S is used for the purpose of selectively converting ultraviolet rays into linear polarization, a light source capable of irradiating light including the entire wavelength range of the corresponding ultraviolet rays is used. In the present invention, the visible light is light in the wavelength range of 380 to 780 nm.

In the present invention, the transmitted light of the sample S is separated into each wavelength to measure the amount of transmitted light of the sample S in the entire wavelength range of visible light, and the degree of orientation is determined for each wavelength as described later. It is preferable to calculate and calculate the degree of orientation of the sample S from the degree of orientation for each wavelength.
Therefore, as the light source 34, a light source capable of irradiating light including the entire wavelength range of visible light is preferably used. Examples of such a light source 34 include halogen lamps and xenon lamps.

The light emitted by the light source 34 is propagated by the optical fiber 38 and divided into two equal amounts by the demultiplexer 40. One of the light demultiplexed by the demultiplexer 40 is propagated to the first light irradiation unit 36a by the optical fiber 42a, and the other is propagated to the second light irradiation unit 36b by the optical fiber 42b.
The first light irradiation unit 36a and the second light irradiation unit 36b irradiate the sample S with linearly polarized light (measurement light). Both the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the polarizing plate that converts the light irradiated by the light source 34 into linear polarization and the sample S held by the holding unit 12 with the linear polarization by the polarizing plate. It has an optical lens (condensing lens).
As the polarizing plate and the projection lens used in the first light irradiation unit 36a and the second light irradiation unit 36b, all known ones can be used.

In FIG. 1, in order to clarify the configuration of the optical measuring device 10, the first light irradiation unit 36a and the second light irradiation unit 36b are shown facing each other. However, in reality, as shown conceptually in FIG. 2, the first light irradiation unit 36a and the second light irradiation unit 36b emit linearly polarized light (dashed line) on the surface of the sample S (holding unit 12). Arranged so as to be orthogonal. That is, the first light irradiation unit 36a and the second light irradiation unit 36b are arranged so that the optical axes of the light projecting lenses are orthogonal to each other.

The first light irradiation unit 36a and the second light irradiation unit 36b irradiate the surface of the sample S held by the holding unit 12 with linearly polarized light in a direction in which the polarization directions are orthogonal to each other. Therefore, the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the surface of the sample S with the direction of the transmission axis of the polarizing plate and the irradiation of light so that the polarization directions of the linearly polarized light to be irradiated are orthogonal to each other. The direction is set.
In the present invention, the surface of the sample S held by the holding portion 12 is the surface of the sample table on which the sample S is placed, the surface formed by the frame body that grips the entire circumference of the end portion of the sample S, and the like. It can be treated synonymously with the holding surface of the sample S by the holding portion 12. In the following description, the surface of the sample S held by the holding portion 12 is also simply referred to as “the surface of the sample S”.
In the optical measuring device 10, as conceptually shown in FIGS. 2 and 3, the first light irradiation unit 36a irradiates the sample S with linearly polarized light (first measurement light) in the arrow x direction. Further, the second light irradiation unit 36b irradiates the sample S with linearly polarized light (second measurement light) in the arrow y direction orthogonal to the arrow x direction.

Correspondingly, the sample S is arranged in the holding unit 12 so that the direction of the absorption axis coincides with the polarization direction (x direction) of the linearly polarized light irradiated by the first light irradiation unit 36a. Therefore, the sample S is arranged so that the direction of the transmission axis coincides with the polarization direction (y direction) of the linearly polarized light irradiated by the second light irradiation unit 36b. Alternatively, the sample S held in the holding portion 12 may be arranged with the directions of the transmission axis and the absorption axis reversed from the above.
Generally, in a polarizing plate, the orientation direction of the alignment film is the absorption axis direction, and the direction orthogonal to the absorption axis is the transmission axis.

Preferably, both the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the sample S with a P wave (P polarization). Alternatively, preferably, both the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the sample S with an S wave (S-polarized light). More preferably, as shown in FIGS. 2 and 3, both the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the sample S with P waves.
Therefore, as shown in FIGS. 2 and 3, it is preferable that the first light irradiation unit 36a and the second light irradiation unit 36b are arranged so that the linear polarizations irradiated with each other are orthogonal to each other on the surface of the sample S. ..

In the present invention, if the polarization directions of the linearly polarized light emitted by the first light irradiation unit 36a and the second light irradiation unit 36b are orthogonal to each other on the surface of the sample S, the first light irradiation unit 36a and the second light irradiation unit 36b Various configurations are available for the positional relationship of.
For example, the first light irradiation unit 36a and the second light irradiation unit 36b are arranged so as to face each other on a straight line, and as conceptually shown in FIG. 4, the linear polarization irradiated with each other is on the surface of the sample S. It may be linear.

Here, in the example shown in FIG. 4, in order for the polarization directions of the linearly polarized waves emitted by the first light irradiation unit 36a and the second light irradiation unit 36b to be orthogonal to each other on the surface of the sample S, the first light irradiation unit is used. The linear polarization in the x direction irradiated by 36a becomes a P wave, and the linear polarization in the y direction irradiated by the second light irradiation unit 36b becomes an S wave. As is well known, the reflectance of the P wave and the S wave are different when they are incident on the medium, and the S wave has a higher reflectance. That is, of the P wave and the S wave, the transmittance of the P wave when it is incident on the medium is higher than that of the P wave.
As will be described later, in the present invention, the alignment promotion treatment is performed on the sample S, linear polarization in the absorption axis direction and the transmission axis direction is incident on the sample S, and the transmitted light transmitted through the sample S is photometrically measured. Measure the degree of orientation. Therefore, when the P wave and the S wave are incident on the sample S, the transmittances of the two linearly polarized waves are different, so that there is a fundamental difference in the numerical value to be evaluated between the transmission axis and the absorption axis. ..
That is, when the angle formed by the incident surface of the linearly polarized light to be irradiated and the polarization direction (that is, the polarization plane) of the linearly polarized light is different between the first light irradiation unit 36a and the second light irradiation unit 36b, the measured degree of orientation is measured. An error will occur in the light, and it will be necessary to correct the measurement results.

On the other hand, in the present invention, preferably, as shown in FIGS. 2 and 3, the first light irradiation unit 36a and the second light irradiation unit 36b both irradiate the sample S with a P wave or or. Both irradiate the sample S with an S wave. This makes it possible to accurately measure the degree of orientation by eliminating the difference in transmittance between the two linearly polarized light due to the difference in the angle formed by the incident surface and the polarization surface.
More preferably, the linear polarization irradiated by the first light irradiation unit 36a and the second light irradiation unit 36b to the sample S is both P waves, so that the transmittance of the linear polarization transmitted through the sample S is increased. It is possible to measure the degree of orientation with higher efficiency.
The linear polarization emitted by the first light irradiation unit 36a and the second light irradiation unit 36b is most preferably P waves or S waves. That is, in the present invention, the linearly polarized light emitted by the first light irradiation unit 36a and the second light irradiation unit 36b has an angle formed by the incident surface and the polarization surface of 0 ° (p wave) or 90 ° (S wave). ) Is the most preferable. However, in the linear polarization emitted by the first light irradiation unit 36a and the second light irradiation unit 36b, the angle formed by the incident surface and the polarization surface is preferably in the range of 0 ° ± 5 ° or 90 ° ± 5 °. Preferably, if it is in the range of 0 ° ± 2.5 ° or 90 ° ± 2.5 °, the degree of orientation can be measured with sufficient accuracy to find out the tendency of the degree of change in the degree of orientation, as will be described later.

In the present invention, the angle formed by the polarization direction of the linearly polarized light irradiated by the first light irradiation unit 36a and the polarization direction of the linearly polarized light irradiated by the second light irradiation unit 36b is orthogonal, that is, from 90 ° on the sample S. , May be slightly off.
That is, the polarization direction of the linearly polarized light irradiated by the first light irradiation unit 36a and the polarization direction of the linearly polarized light irradiated by the second light irradiation unit 36b are slightly different from the transmission axis direction and / or the absorption axis direction of the sample S. , May be misaligned. Further, the angle formed by the linear polarization irradiated by the first light irradiation unit 36a and the linear polarization irradiated by the second light irradiation unit 36b may be slightly different from 90 °.

As will be described later, in the present invention, linear polarization in the transmission axis direction and linear polarization in the absorption axis direction are incident on the sample S, and the degree of orientation of the sample S is measured from the photometric result of the transmitted light. Perform while applying accelerated treatment. The alignment promotion treatment is the same treatment as the orientation promotion step in the production of the polarizing plate. In the illustrated example, the sample S is heated and / or cooled (aged) as an orientation promoting treatment.
According to the present invention, it is possible to detect a change in the degree of orientation in the alignment promotion step in the manufacture of the polarizing plate. As a result, by using the present invention, it is possible to determine the processing conditions in the alignment promotion step so that a high degree of orientation, that is, a high degree of polarization can be obtained in the production of the polarizing plate.
Therefore, in the present invention, if the tendency of the change in the degree of orientation with respect to the passage of the treatment time and the change in the treatment conditions in the orientation promotion treatment can be known, a certain degree of object can be achieved.
In consideration of the above points, in the present invention, the polarization directions of the linearly polarized light irradiated by the first light irradiation unit 36a and the second light irradiation unit 36b are completely orthogonal (90 °) on the surface of the sample S. It does not have to be.
That is, in the present invention, the fact that the polarization directions of the linearly polarized light irradiated by the first light irradiation unit 36a and the second light irradiation unit 36b are orthogonal to each other on the surface of the sample S is substantially 2 on the surface of the sample S. It is shown that the angle formed by the polarization directions of the two linearly polarized light is within 90 ° ± 10 °. On the surface of the sample S, the angle formed by the polarization directions of the two linearly polarized light is preferably within 90 ° ± 5 °, and 90 °, that is, orthogonality is most preferable.

The emission direction of the linearly polarized light from the first light irradiation unit 36a and the second light irradiation unit 36b is not limited as long as the two transmitted lights transmitted through the sample S can be individually and independently measured.
Specifically, the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the sample S with linearly polarized light at an angle of 1 ° or more with respect to the perpendicular line (normal line) on the surface of the sample S. preferable.
Here, in consideration of the transmittance, it is preferable that the first light irradiation unit 36a and the second light irradiation unit 36b incident the P wave at the Brewster angle. However, in the sample S, for example, an alignment film is formed on the base material, and a coating film of the composition is formed on the alignment film. When light is incident on such a sample S at a large angle, the light is reflected at the interface of each layer having a different refractive index, and an error occurs in the measured transmittance.
Considering this point, it is preferable that the first light irradiation unit 36a and the second light irradiation unit 36b irradiate the sample S with linearly polarized light at an angle of 15 ° to 45 ° with respect to the perpendicular line on the surface of the sample S. It is more preferable to irradiate the sample S with linearly polarized light at an angle of 25 ° to 35 °.

The linearly polarized light irradiated by the first light irradiation unit 36a and the second light irradiation unit 36b passes through the sample S and the holding unit 12 and is received by the light receiving optical system 16.
The light receiving optical system 16 includes a first light receiving unit 48a that is irradiated by the first light irradiation unit 36a and receives the transmitted light transmitted through the sample S, and a transmitted light that is irradiated by the second light irradiation unit 36b and transmitted through the sample S. It has a second light receiving unit 48b that receives light. Therefore, it is preferable that the first light irradiation unit 36a and the first light receiving unit 48a have the same optical axis. Similarly, it is preferable that the second light irradiation unit 36b and the second light receiving unit 48b have the same optical axis.
The first light receiving unit 48a has a light receiving lens 50a and an optical fiber 52a. The second light receiving unit 48b has a light receiving lens 50b and an optical fiber 52b. As the light receiving lens (condensing lens) and the optical fiber, known ones may be used.

The transmitted light received by the first light receiving unit 48a is collected by the light receiving lens 50a, propagated by the optical fiber 52a, and measured by the first spectrophotometer 18a. On the other hand, the transmitted light received by the second light receiving unit 48b is collected by the light receiving lens 50b, propagated by the optical fiber 52b, and photometrically measured by the second spectrophotometer 18b.
Both the first spectrophotometer 18a and the second spectrophotometer 18b are known spectrophotometers, and the transmitted light of the received sample S is separated to measure the intensity of each wavelength.
The wavelength interval measured by the first spectrophotometer 18a and the second spectrophotometer 18b, that is, the degree of spectroscopy is not limited, and is appropriately determined in the same manner as the known method for measuring the orientation of the polarizing plate. do it. The wavelength interval measured by the first spectrophotometer 18a and the second spectrophotometer 18b is preferably 10 nm or less, and more preferably 5 nm or less.

The photometric results of the first spectrophotometer 18a and the second spectrophotometer 18b are supplied to the data processing unit 30.
The data processing unit 30 will be described in detail later.

The optical measuring device 10 has a temperature controlling means. The temperature adjusting means 20 adjusts the temperature of the sample S held by the holding portion 12.
That is, the sample S corresponds to a polarizing plate whose orientation is promoted by aging by heating and / or cooling in the orientation promoting step in the production of the polarizing plate. Correspondingly, the optical measuring device 10 performs the orientation promotion treatment of the sample S by heating and / or cooling the sample S which imitates the alignment promotion step in the production of the polarizing plate.

There is no limitation on the temperature control method of the sample S by the temperature control means 20, and the heating medium is a path including a hot air supply means, a cold air supply means, various heaters such as an infrared heater, a cooling means by a Pelche element, and a holding portion 12. Various known temperature control means for sheet-like objects such as means for circulating the cooling medium and means for circulating the cooling medium through a path including the holding portion 12 can be used.
Further, the range of temperature control of the sample S by the temperature control means 20 is not limited, and may be appropriately set according to the sample S. For example, when the sample S has a coating film containing a dichroic substance and a rod-shaped liquid crystal compound as described above, the temperature control range is, for example, 20 to 200 ° C. as an example.

As described above, in the present invention, the orientation-promoting treatment of the sample P corresponding to the polarizing plate includes not only aging by temperature control but also orientation-promoting treatment by stretching and light irradiation such as ultraviolet irradiation. It is available.
Further, a plurality of such orientation promotion treatments may be performed. At this time, the plurality of orientation promotion treatments may be performed simultaneously or sequentially.

Correspondingly, the optical measuring device 10 of the present invention may have a stretching means for stretching the sample S held by the holding portion 12 in imitation of the orientation promoting step by stretching in the production of the polarizing plate. Further, the optical measuring device 10 of the present invention may have a light irradiation means for irradiating the sample S held by the holding unit 12 with light, simulating the alignment promotion step by light irradiation in the manufacture of the polarizing plate.
The optical measuring device 10 of the present invention may have only one of the stretching means and the light irradiation means. It may have both. Further, the stretching means and / or the light irradiation means may be provided in place of the temperature controlling means 20, or may be provided in addition to the temperature controlling means 20.

The stretching means is not limited, and various stretching means used in the orientation promoting step can be used in the production of the polarizing plate.
Further, the light irradiation means is not limited, and various light irradiation means used in the orientation promoting step can be used in the production of the polarizing plate. In the optical measuring apparatus of the present invention, when the light irradiating means is used for the alignment promotion processing of the sample S, the light irradiated by the light irradiating means is the light receiving lens 50a of the first light receiving unit 48a and the second light receiving. It is preferable not to enter the light receiving lens 50b of the portion 48b. Further, in the optical measuring apparatus of the present invention, when the light irradiation means is used to promote the orientation of the sample S, the light irradiation optical system 14 and the light irradiation means for performing the alignment promotion treatment irradiate light having different wavelengths. It is also preferable to do so.

The temperature measuring means 24 measures the temperature of the sample S held in the holding unit 12 and supplies the measurement result to the data processing unit 30.
There is no limitation on the temperature measuring method of the sample S by the temperature measuring means 24, and various known temperature measuring methods such as a thermocouple and a radiation thermometer can be used.
In the present invention, the temperature of the holding portion 12 such as the sample table on which the sample S is placed may be measured, and the temperature of the holding portion 12 may be used as the temperature of the sample S.

The signal generator 26 sends a sampling signal instructing the first spectrophotometer 18a, the second spectrophotometer 28b, and the temperature measuring means 24 to perform the measurement. The sampling signal is not limited, but a pulse signal is exemplified.
The signal generator 26 outputs a sampling signal to the first spectrophotometer 18a, the second spectrophotometer 28b, and the temperature measuring means 24 at the same timing. The first spectrophotometer 18a and the second spectrophotometer 28b measure the transmitted light received when the sampled signal is received from the signal generator 26, and the temperature measuring means 24 measures the sampled signal from the signal generator 26. At the time of receiving, the temperature of the sample S is measured.
As described above, the first spectrophotometer 18a and the second spectrophotometer 28b supply the measurement result of the transmitted light, and the temperature measuring means 24 supplies the temperature measurement result of the sample S to the data processing unit 30.

In the optical measuring device 10 of the present invention, the data processing unit 30 is provided as a preferred embodiment.
In the data processing unit 30, the first light irradiation unit 36a and the second light irradiation unit 36b are based on the measurement results of the transmitted light of the sample S measured by the first spectrophotometer 18a and the second spectrophotometer 28b for each wavelength. The transmittance of the irradiated linearly polarized sample S is calculated for each wavelength. Next, the data processing unit 30 calculates the absorbance of the linearly polarized light sample S irradiated by the first light irradiation unit 36a and the second light irradiation unit 36b for each wavelength from the calculated transmittance. Next, the data processing unit 30 calculates the degree of orientation of the sample S for each wavelength from the calculated absorbance. Further, the data processing unit 30 calculates the degree of orientation of the sample S from the calculated degree of orientation of the sample S for each wavelength.
Further, when the data processing unit 30 calculates the degree of orientation of the sample S, the data processing unit 30 associates the processing time of the orientation promotion process with the calculated degree of orientation of the sample S and the temperature measurement result supplied from the temperature measuring means 24. And output.
The above points will be described in detail later.

Such a data processing unit 30 may be configured by using, for example, a personal computer, a notebook computer, a tablet computer, or the like.
Further, the transmittance, the transmittance, and the absorbance may be calculated by the first spectrophotometer 18a and the second spectrophotometer 28b instead of the data processing unit 30.

Hereinafter, the optical measuring device and the orientation measuring method of the present invention will be described in more detail by explaining the operation of the optical measuring device 10.

First, the sample S is held by the holding portion 12. As an example, the holding unit 12 is a sample table on which the sample S is placed and held.
In this example, as an example, the sample S has an alignment film on the surface of the base material, and a composition containing a bicolor substance and a rod-shaped liquid crystal compound is applied to the surface of the alignment film and dried. It is assumed that a film is formed.
In the sample S, as an example, the direction of the absorption axis coincides with the polarization direction (arrow x direction) of the linearly polarized light irradiated by the first light irradiation unit 36a, and the direction of the transmission axis is irradiated by the second light irradiation unit 36b. It is placed on the sample table in accordance with the polarization direction (arrow y direction) of the linearly polarized light.
Further, in this example, the sample S corresponds to a polarizing plate that linearly polarizes the entire visible light range, and measures the degree of orientation of the sample S corresponding to the entire visible light range.

After the sample S is placed on the sample table, the light source 34, that is, the first light irradiation unit 36a and the second light irradiation unit 36b are driven. As a result, the linear polarization of the sample S irradiated by the first light irradiation unit 36a in the absorption axis direction (first measurement light) and the linear polarization of the sample S irradiated by the second light irradiation unit in the transmission axis direction (first). The measurement light of 2) is incident on the sample S.
The linear polarization of the sample S irradiated by the first light irradiation unit 36a in the absorption axis direction passes through the sample S and the sample table, enters the light receiving lens 50a of the first light receiving unit 48a, and propagates through the optical fiber 52a. , Is incident on the first spectrophotometer 18a.
On the other hand, the linear polarization in the absorption axis direction of the sample S irradiated by the second light irradiation unit 36b passes through the sample S and the sample table, enters the light receiving lens 50b of the second light receiving unit 48b, and propagates through the optical fiber 52b. Then, it is incident on the second spectrophotometer 18b.

After driving the first light irradiation unit 36a and the second light irradiation unit 36b, the temperature control means 20 is then driven to start an orientation promotion process in which the sample S is heated and / or cooled to promote orientation.
There is no limitation on the temperature control of the sample S, and various embodiments simulating heating and / or cooling in the orientation promoting step (aging step) in the actual production of the polarizing plate can be used. Therefore, the temperature of the sample S may be adjusted only by heating (heating), cooling (lowering) after heating, or heating again after heating and cooling, and heating and cooling may be performed a plurality of times. , May be repeated.
After starting the orientation promotion process, the signal generator 26 simultaneously outputs a sampling signal such as a pulse signal to the first spectrophotometer 18a, the second spectrophotometer 18b, and the temperature measuring means 24. Further, the data processing unit 30 measures the elapsed time from the start of the orientation promotion process.
The first spectrophotometer 18a that received the sampling signal emits the first light irradiation unit 36a and transmits the transmitted light of linearly polarized light in the absorption axis direction transmitted through the sample S and the sample table at each wavelength in the entire visible light range. The light is measured by splitting each time, and the light measurement result is supplied to the data processing unit 30.
Further, in the second spectrophotometer 18b that received the sampling signal, the second spectrophotometer 36b emits the transmitted light of linearly polarized light in the transmission axis direction transmitted through the sample S and the sample table over the entire visible light. The light is separated and measured for each wavelength, and the light measurement result is supplied to the data processing unit 30.
Further, the temperature measuring means 24 that has received the sampling signal measures the temperature of the sample S at that time and supplies the temperature measurement result to the data processing unit 30.

The data processing unit 30 calculates the transmittance of the linearly polarized light transmitted through the sample S in the absorption axis direction for each wavelength from the photometric result of the transmitted light supplied from the first spectrophotometer 18a.
Further, the data processing unit 30 calculates the transmittance of the linearly polarized light transmitted through the sample S in the transmission axis direction for each wavelength from the photometric result of the transmitted light supplied from the second spectrophotometer 18b.
The transmittance may be calculated by a known method. For example, it may be calculated by "transmittance T = I / I ₀ " using the incident light amount I ₀ and the transmitted light amount I.

Here, as described above, the sample S has an alignment film on the surface of the base material, and a composition containing a bicolor substance and a rod-shaped liquid crystal compound is applied to the surface of the alignment film and dried. It formed a film.
Therefore, a reference sample having no coating film and only the base material and the alignment film is prepared in advance, and the transmitted light of the reference sample is measured by the first spectrophotometer 18a and the second spectrophotometer 18b. The data processing unit 30 preferably calculates the transmittance using the photometric result of this reference sample.
As an example, in the above-mentioned calculation of the transmittance, a method of using the photometric result of the reference sample as the incident light amount I ₀ is exemplified. As another method, a method of calculating the transmittance from the ratio between the photometric result of the reference sample and the photometric result of the sample S can be used, assuming that the photometric result of the reference sample is 100%.

After the data processing unit 30 calculates the transmittance of the linear polarization in the absorption axis direction and the transmittance of the linear polarization in the transmission axis direction for each wavelength in the entire visible light range, the data processing unit 30 then calculates the transmittance of the linear polarization in the transmission axis direction, and then the absorption axis for each wavelength. And the absorbance of the transmission axis is calculated.
The absorbance A may be calculated by "absorbance A = -log ₁₀ T", where T is the same as above.

After calculating the absorbance of the absorption axis and the transmission axis for each wavelength in the entire visible light range, the data processing unit 30 calculates the degree of orientation S for each wavelength by the following formula.
Degree of orientation S = (A _a -A _t ) / (2A _t + A _a )
In the above formula, "A _t " is the absorbance of the transmission axis, and "A _a " is the absorbance of the absorption axis.

After calculating the degree of orientation for each wavelength in the entire visible light in this way, the degree of orientation for the sample S is calculated using the degree of orientation for each wavelength.
The degree of orientation of the sample S using the degree of orientation for each wavelength can be calculated as the degree of visibility correction by applying a sensitivity correction called the degree of visibility correction to the degree of orientation S calculated for each wavelength. good.

When the alignment promotion process of the sample S is completed, the data processing unit 30 outputs the calculated degree of orientation of the sample S, the temperature measurement result of the sample S, and the time lapse of the alignment promotion process in association with each other.
As an example, the data processing unit 30 has, for example, the processing time (seconds [s]) and the temperature and orientation degree (visual sensitivity) of the sample S with the processing time of the orientation promotion processing as the horizontal axis as shown in FIG. Create a graph showing the relationship with the corrected orientation) and output it.
From this graph, the relationship between the treatment time, the temperature change of the sample P, and the change in the degree of orientation in the orientation promotion treatment can be grasped. Therefore, according to the present invention, it is possible to properly grasp the change in the degree of orientation in the alignment promotion step in the manufacture of the polarizing plate, and set the processing conditions for the alignment promotion step in which a high degree of orientation, that is, a high degree of polarization can be obtained. It will be possible.

As described above, in the polarizing plate, the absorbance on the transmission axis and the absorbance on the absorption axis are required to calculate the degree of orientation. For that purpose, the transmittance of linearly polarized light in the transmission axis direction and the transmittance of linearly polarized light in the absorption axis direction are required.
Moreover, as shown in FIG. 5, in the orientation promotion treatment (alignment promotion step), the degree of orientation changes from moment to moment with time.
Therefore, in order to accurately measure the degree of orientation while performing the orientation promotion treatment, it is necessary to simultaneously measure the transmittance of the linearly polarized light in the transmission axis direction and the transmittance of the linearly polarized light in the absorption axis direction.

In the measurement of the degree of orientation in the conventional polarizing plate, the transmittance of the linearly polarized light in the transmission axis direction and the transmittance of the linearly polarized light in the absorption axis direction cannot be measured at the same time while performing the orientation promotion treatment.

On the other hand, in the present invention, two linearly polarized lights whose polarization directions are orthogonal to each other are incident on the sample S on the surface of the sample S, and the transmitted light of the two linearly polarized light transmitted through the sample S is measured. The sample S is subjected to an orientation promotion treatment that imitates the orientation promotion step.
Therefore, according to the present invention, the transmittance of the linearly polarized light in the transmission axis direction and the transmittance of the linearly polarized light in the absorption axis direction can be measured simultaneously and in real time while performing the orientation promotion treatment. Therefore, according to the present invention, as shown in FIG. 5, the relationship between the passage of the treatment time and the change in the treatment conditions and the change in the degree of orientation in the orientation promotion treatment can be appropriately grasped.
In particular, as described above, by making the two linear polarizations incident on the sample S between the S polarizations or the P polarizations, the transmittance (reflectance) of the two direct polarizations caused by the polarization is made uniform. Therefore, it becomes possible to measure the degree of orientation more accurately.

Although the optical measuring device and the orientation measuring method of the present invention have been described in detail above, the present invention is not limited to the above-mentioned examples, and various improvements and changes are made without departing from the gist of the present invention. Of course, you may.

It is suitably used for setting conditions for an orientation promotion step in the manufacture of a polarizing plate.

10 Optical measuring device 12 Holding unit 14 Light irradiation optical system 16 Light receiving optical system 18a First spectrophotometer 18b Second spectrophotometer 20 Temperature control means 24 Temperature measuring means 26 Signal generator 30 Data processing unit 34 Light source 36a First light Irradiation part 36b Second light irradiation part 38, 42a, 42b, 52a, 52b Optical fiber 40 demultiplexer 48a First light receiving part 48b Second light receiving part 50a, 50b Light receiving lens

Claims (12)

A holding unit that holds the measurement target and
A first light irradiation unit that irradiates the holding unit with linearly polarized light,
A second light irradiation unit that irradiates the holding unit with linearly polarized light,
A first light receiving unit that receives the light emitted by the first light irradiation unit and a first light receiving unit that sandwiches the holding unit.
A second light receiving unit that receives the light emitted by the second light irradiation unit and a second light receiving unit that sandwiches the holding unit.
A spectrophotometer that separates and measures the light received by the first light receiving unit and the second light receiving unit, and a spectrophotometer.
A temperature control means for controlling the temperature of the measurement target held in the holding portion, a stretching means for stretching the measurement target held in the holding portion, and light for irradiating the measurement target held in the holding portion with light. It has at least one of the irradiation means and
The first light irradiation unit and the second light irradiation unit irradiate the holding unit with P waves or S waves so that the polarization directions are orthogonal to each other on the holding surface of the measurement target in the holding unit. Is to irradiate the holding portion.
Further, the first light irradiation unit and the second light irradiation unit are optical measuring devices in which emitted P waves or S waves are arranged so as to be orthogonal to each other on the holding surface of the holding unit. The optical measuring device according to claim 1 , wherein the first light irradiation unit and the second light irradiation unit irradiate the holding unit with P waves. The optical measuring device according to claim 1 or 2 , which has the temperature controlling means. The optical measuring apparatus according to any one of claims 1 to 3 , wherein the first light irradiation unit and the second light irradiation unit irradiate the holding unit with linearly polarized light including the entire wavelength range of visible light. The first light irradiation unit and the second light irradiation unit irradiate the holding portion with linearly polarized light at an angle of 1 ° or more with respect to the perpendicular line of the measurement target held by the holding portion. The optical measuring device according to any one of 4 to 4 . A transmittance calculation means for calculating the transmittance of light emitted by the first light irradiation unit and the second light irradiation unit from the photometric results of the spectrophotometer.
An absorbance calculating means for calculating the absorbance from the transmittance calculated by the transmittance calculating means, and an absorbance calculating means.
The optical measuring apparatus according to any one of claims 1 to 5 , further comprising an orientation degree calculation means for calculating an orientation degree from the absorbance calculated by the absorbance calculation means. The measurement target to be the polarizing plate is different from the first measurement light which is an S wave or P wave polarized in the transmission axis direction or the absorption axis direction of the polarizing plate and the first measurement light of the polarizing plate. A second measurement light, which is linearly polarized in the axial direction and whose polarization direction with respect to the incident surface is equal to that of the first measurement light, is incident on the surface of the polarizing plate so as to be orthogonal to the surface of the polarizing plate and is transmitted through the measurement target. The first measurement light and the second measurement light were separated and measured by subjecting the measurement target to an orientation promotion treatment for promoting orientation.
From the measurement results of the first measurement light and the second measurement light transmitted through the measurement target, the transmittance of the first measurement light and the second measurement light with respect to the measurement target is calculated.
From the calculated transmittance, the absorbance of the measurement target is calculated.
A method for measuring the degree of orientation, which comprises calculating the degree of orientation of the object to be measured from the calculated absorbance. The method for measuring the degree of orientation according to claim 7 , wherein a P wave is incident on the measurement target as the first measurement light and the second measurement light. The method for measuring the degree of orientation according to claim 7 or 8 , wherein at least one of heating and cooling of the measurement target is performed as the alignment promotion treatment. The method for measuring orientation according to any one of claims 7 to 9 , wherein the first measurement light and the second measurement light include the entire wavelength range of visible light. The method for measuring the degree of orientation according to any one of claims 7 to 10 , wherein the measurement target is a laminate having a coating film containing a dichroic substance and a rod-shaped liquid crystal compound. Using a reference sample obtained by removing the coating film from the laminate,
In the same manner as the measurement target, the first measurement light and the second measurement light transmitted through the reference sample are measured.
Using the measurement result of the transmitted light of the reference sample, the first measurement light and the first measurement light with respect to the measurement target are obtained from the measurement results of the first measurement light and the second measurement light transmitted through the measurement target. The method for measuring the degree of orientation according to claim 11 , which calculates the transmission rate of the measurement light of 2.

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