KR20220048757A - Inspection apparatus and inspection method for a defect of a circular polarizer - Google Patents

Abstract

The present application does not undergo actual panel inspection and destructive inspection, it is simple and can shorten inspection time, is economical, has improved visibility of circular polarizer defects, and has high inspection reproducibility. and an inspection method of a circularly polarizing plate.

Description

Circular polarizer inspection apparatus and circular polarizer inspection method {Inspection apparatus and inspection method for a defect of a circular polarizer}

The present application relates to a circularly polarizing plate inspection apparatus and a circularly polarizing plate inspection method

Circular polarizers used in organic light emitting diodes (OLED) display devices are inspected for defects before shipment. In order to inspect the defect of the circular polarizer, a black mode should be implemented.

Conventionally, the inspection was performed by crossing the circularly polarizing plate up and down, but the black mode was not sufficiently implemented, so that the quality level of the circularly polarizing plate could not be determined. For this reason, in the circular polarizing plate inspection step, even when a pass decision is received, there is a problem that it is impossible to check whether stains or the like remain when applied to a product or whether defects formed on the circular polarizing plate remain or disappear. In addition, in order to perform the inspection, since the two circularly polarizing plates must be crossed up and down accurately, a long inspection time is required.

In addition, as another conventional inspection method, there was a method of sampling a part of the product and proceeding with the destructive inspection. However, such destructive inspection was disadvantageous in terms of revenue because the finished product had to be destroyed, and there was a problem in that a defective circular polarizer was not detected and shipped due to a statistical error (type 1 error or type 2 error) due to sampling.

Also, as another conventional inspection method, there is a method of separately providing an inspection panel, stacking a circularly polarizing plate on the inspection panel to implement blackening, and then inspecting it under a fluorescent lamp. However, this has a problem in that the unit cost of the inspection panel is high.

In addition, as another conventional inspection method, there is a method of inspecting a defect of a circular polarizer using a light-transmitting glass having a relatively low unit cost instead of an inspection panel. Specifically, a circularly polarizing plate was laminated on one surface of the light-transmitting glass, and a black tape was attached to the opposite surface of the surface on which the circularly polarizing plate was laminated, and the test was performed under a fluorescent lamp. However, the unit cost problem was solved, but the black mode was not sufficiently implemented by the black tape, so the visibility of the defect was low, it was necessary to use the black tape, which is a consumable, and the black tape was attached to one side of the light-transmissive glass, so excessive time was required for inspection preparation. It took

Various methods for inspecting defects have been disclosed as described above. Korean Patent Registration No. 10-0957728 discloses a method of inspecting defects by irradiating light of various colors or intensities to an inspection object.

Republic of Korea Patent Registration No. 10-0957728

The inventors of the present application intend to provide a circular polarizing plate inspection apparatus and circular polarizing plate inspection method that is simple and shortened inspection time without going through actual panel inspection and destructive inspection in order to solve the above problems.

In addition, the inventors of the present application can save the unit cost compared to the inspection panel, do not use consumables such as black tape, and implement sufficient blackening to improve the visibility of the circular polarizer defect inspection apparatus and original An object of the present invention is to provide a method for inspecting a polarizing plate.

In addition, the inventors of the present application intend to provide a circularly polarizing plate inspection apparatus and a circularly polarizing plate inspection method having high inspection reproducibility.

The circularly polarizing plate inspection apparatus according to the present application may include a reflecting plate installed so that the circularly polarizing plate can be loaded, and a lighting means installed to irradiate light toward the circularly polarizing plate loaded on the reflecting plate.

The circularly polarizing plate inspection method according to the present application may be to check the defects of the circularly polarizing plate while irradiating light toward the circularly polarizing plate loaded on the reflecting plate.

The circularly polarizing plate inspection apparatus and the circularly polarizing plate inspection method according to the present application are simple and the inspection time can be shortened without going through an actual panel inspection and destructive inspection.

In addition, the circular polarizing plate inspection apparatus and circular polarizing plate inspection method according to the present application can reduce the unit cost compared to the inspection panel, do not use consumables such as black tape, and implement sufficient blackening to eliminate defects in the circular polarizer plate Visibility can be improved.

In addition, the circular polarizing plate inspection apparatus and the circular polarizing plate inspection method according to the present application have high inspection reproducibility.

1 shows a circularly polarizing plate inspection apparatus according to an example of the present application.
2 is a view showing a state of a circular polarizing plate inspection result according to Inspection Example 1. Referring to FIG.
3 is a view showing the state of the circular polarizing plate inspection results according to Comparative Inspection Example 1.
4 is a view comparing the circularly polarizing plate inspection results according to Comparative Inspection Example 1 (left) and Inspection Example 1 (right) side by side.

The present application will be described in detail.

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

1 shows a circularly polarizing plate inspection apparatus 10 according to an example of the present application.

Referring to FIG. 1 , the circularly polarizing plate inspection apparatus 10 according to an example of the present application may include a reflecting plate 120 installed so that the circularly polarizing plate 110 can be loaded. In addition, the circularly polarizing plate inspection apparatus 10 according to an example of the present application may include a lighting means 130 installed to irradiate light toward the circularly polarizing plate 110 loaded on the reflecting plate 120 . . In addition, the circularly polarizing plate inspection apparatus 10 according to an example of the present application is provided with a defect measuring unit to measure defects of the circularly polarizing plate 110 in addition to the circularly polarizing plate 110 , the reflecting plate 120 and the lighting means 130 . may have been

The circular polarizer 110 is used in organic light emitting diodes (OLED) display devices, and may include a linear polarization layer and a retardation layer formed on one surface of the linear polarization layer. For example, the circularly polarizing plate 110 may include a λ/4 retardation plate on one surface of the linearly polarizing plate.

The circularly polarizing plate inspection apparatus 10 may be installed so that the phase difference plate of the circularly polarizing plate 110 is loaded adjacent to the reflecting plate 120 compared to the linearly polarizing plate.

The reflector 120 may have a reflectance of 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more for light having a wavelength of 550 nm, which is an average of the visible ray region based on a thickness of about 5 mm. In another example, the reflectance may be 100% or less, 99% or less, 95 or less, 90% or less, or 85% or less. In addition, the reflectance of the reflector 120 with respect to the light having a wavelength of 550 nm is preferably 95% or more in consideration of the wavelength, the amount of light, and the illuminance of the light provided by the lighting means 130 to be described below. In addition, the reflectance may be measured according to a standard such as ISO 9050:1990 or ISO 15368:2001. The reflective plate 120 may be, for example, light reflective glass in which a metal layer is formed on a glass substrate, but is not particularly limited thereto.

The lighting means 130 may be installed in the circularly polarizing plate inspection apparatus 10 so as to irradiate light toward the circularly polarizing plate 110 loaded on the reflecting plate 120 in order to perform the inspection of the circularly polarizing plate 110. . In addition, the lighting means 130 may provide unpolarized light, and if the conditions described below are satisfied, various known lighting may be used. For example, the lighting means 130 may be a fluorescent lamp, an incandescent lamp, an LED lamp, but is not limited thereto.

The lighting means 130 is 0° to 60°, or 0° to 55°, or 0° to 50°, or 0° to 45 with the normal direction of the surface of the circularly polarizing plate 110 loaded on the reflecting plate 120 . It may be installed to irradiate light so as to achieve an angle within the range of °. That is, the light provided by the lighting means 130 is 0° to 60°, or 0° to 55°, or 0° to 50° with the normal direction of the surface of the circularly polarizing plate 110 loaded on the reflection plate 120 . , or may have an incident angle within the range of 0° to 45°.

When the incident angle of the light provided by the illuminating means 130 exceeds 60° with the normal direction of the surface of the circularly polarizing plate 110 loaded on the reflective plate 120, the reflected light reflected by the reflective plate 120 and the illuminating means ( 130) may cause interference between the incident light provided, thereby reducing the reproducibility of the circularly polarizing plate inspection.

The wavelength of the light provided by the lighting means 130 may be in the range of 400 nm to 650 nm or 450 nm to 600 nm. That is, the lighting means 130 may be installed so as to irradiate light having a wavelength in the above range toward the circularly polarizing plate 110 loaded on the reflective plate 120 . In addition, the circularly polarizing plate inspection apparatus 10 according to the present application inspects the circularly polarizing plate 110 by implementing a black mode, which will be described later. The wavelength may appear high in the above range.

When the wavelength of the light provided by the lighting means 130 satisfies the above range, a black mode, which will be described later, is implemented to ensure visibility when inspecting the circularly polarizing plate 110 .

Illumination of light provided by the lighting means 130 may be 500 lx or more, 600 lx or more, 700 lx or more, 800 lx or more, or 900 lx or more, and in another example, 1,000 lx or less, 900 lx or less, 800 lx or less or 700 lx or less.

When the illuminance of the light provided by the lighting means 130 is greater than 1,000 lx, the blackening rate may be reduced. In addition, when the illuminance of the light provided by the lighting means 130 is less than 500 lx, even if there is a defect, there is little light passing through the circularly polarizing plate 110, so the visibility of the defect may be reduced.

The luminous flux of light provided by the lighting means 130 may be 3,200 lm or more, 3,250 lm or more, 3,300 lm or more, 3,350 lm or more, or 3,400 lm or more, and in another example 3,500 lm or less, 3,450 lm or less, 3,400 lm or more It may be less than or equal to 3,350 lm or less than or equal to 3,300 lm.

When the luminous flux of the light provided by the lighting means 130 is greater than 3,500 lm, the light generated by the lighting means 130 is reflected by the surrounding material, so that the blackening rate may be reduced. In addition, when the luminous flux provided by the lighting means 130 is less than 3,200 lm, the amount of generated light itself is small, making it difficult to inspect the circularly polarizing plate 110 .

The light provided by the lighting means 130 must satisfy at least one of the group consisting of the wavelength of the light, the illuminance of the light, and the luminous flux of the light to achieve a high blackening rate and improve the visibility of the defect.

The defect measuring unit receives the image of the circularly polarizing plate 110 loaded on the reflecting plate 120 from the photographing unit and the photographing unit for photographing the circularly polarizing plate 110 loaded on the reflective plate 120, and a control unit for inspecting whether there is a defect may include That is, the defect measuring unit may perform the inspection of the circularly polarizing plate 110 through the photographing unit and the control unit.

The circularly polarizing plate inspection method according to an example of the present application may be to check a defect of the circularly polarizing plate while irradiating light toward the circularly polarizing plate 110 loaded on the reflective plate 120 .

In addition, terms used in the circularly polarizing plate inspection method according to an example of the present application may have the same meaning as the circularly polarizing plate inspection apparatus 10 according to the above-described embodiment of the present application unless otherwise specified.

For example, in the circularly polarizing plate inspection method according to an example of the present application, the circularly polarizing plate 110 loaded on the reflecting plate 120 may include a linearly polarizing layer and a retardation layer formed on one surface of the linearly polarizing layer. For example, the circularly polarizing plate 110 may include a λ/4 retardation plate on one surface of the linearly polarizing layer. In addition, in the circularly polarizing plate inspection method, the retardation plate of the circularly polarizing plate 110 may be loaded adjacent to the reflecting plate 120 compared to the linearly polarizing plate.

In addition, the reflector 120 may have a reflectance of 80% or more with respect to light having a wavelength of 550 nm, which is an average of the visible ray region.

In addition, in the circularly polarizing plate inspection method according to an example of the present application, the light irradiated toward the circularly polarizing plate 110 loaded on the reflective plate 120 may be unpolarized light, and the circular polarizing plate loaded on the reflective plate 120 . It may be incident to form an angle within the range of 0° to 60°, or 0° to 55°, or 0° to 50°, or 0° to 45° with the normal direction of the surface of the polarizing plate 110 .

In addition, the wavelength of the light irradiated toward the circular polarizing plate 110 loaded on the reflection plate 120 may be within the range of 400 nm to 650 nm, the illuminance of the light may be within the range of 500 lx to 1,000 lx, the luminous flux of light is 3,200 lm to 3,500 lm.

In addition, the light irradiated toward the circularly polarizing plate 110 loaded on the reflecting plate 120 is the characteristic of the light provided by the lighting means 130 of the circularly polarizing plate inspection apparatus 10 according to an example of the present application described above. can be the same.

In addition, the light irradiated toward the circular polarizing plate 110 loaded on the reflection plate 120 must satisfy at least one or more from the group consisting of a wavelength of light, an illuminance of light, and a luminous flux of light to achieve a high blackening rate while improving the visibility of defects. can be improved

The term blackening as used herein may mean a dark degree of a screen that appears when inspecting a circularly polarizing plate in the circularly polarizing plate inspection apparatus and circularly polarizing plate inspection method according to an example of the present application. That is, the high blackening may mean that the screen displayed after irradiating the incident light is very dark.

The high and low of blackening can be expressed by quantitatively measuring the blackening rate.

The blackening rate may be measured using a spectrophotometer measuring instrument (eg, measuring instrument using a computer color matching method). The spectrophotometer measuring device may measure a brightness value of a screen that appears when inspecting a circularly polarizing plate in the circularly polarizing plate inspection apparatus and the circularly polarizing plate inspection method, and the blackening rate may be calculated through the measured brightness value.

The lightness value may be defined according to the L value of the Lab model defined by CIE (Commission Internationale d'Eclairage). Here, the closer L is to 100, the closer to white, and the closer L is to 0, the closer to black.

The blackening rate may be defined by Equation 1 below.

[Equation 1]

Blackening rate (%)={1-(L value of Lab model)/100}*100

Here, the high blackening may mean that the blackening rate is 90% or more, or 95% or more, or 99% or more, or 99.9% or more, or 100%.

A circularly polarizing plate inspection apparatus and a circularly polarizing plate inspection method according to an example of the present application may implement a black mode, which is a mode with high blackening, to perform inspection of a circularly polarizing plate. Hereinafter, an implementation principle of the black mode will be described.

The unpolarized light L _o provided by the lighting means 130 transmits only the linearly polarized light L ₁ in a specific axial direction by the linear polarization layer. For example, the unpolarized light transmits only the linearly polarized light L ₁ having a phase of 90 by the linearly polarized layer. The linearly polarized light (L ₁ ) passing through the linearly polarized layer is changed to the circularly polarized light (L ₂ ) while passing through the λ/4 retardation plate. For example, the linearly polarized light L ₁ having a phase of 90 transmitted through the linear polarization layer may be changed to the circularly polarized light L ₂ having a phase of 135 while passing through the λ/4 retardation plate. At this time, the circularly polarized light L ₂ having a phase of 135 means light that vibrates between the phases of 90 and 180. The circularly polarized light L ₂ having a phase of 135 is reflected by the reflecting plate 120 . The reflected circularly polarized light (L ₃ ) passes through the same λ/4 retardation plate as above and is changed into linearly polarized light (L ₄ ) having a phase of 180 . Thereafter, the linearly polarized light L ₄ having a phase of 180 is absorbed by the same linearly polarized layer as above and is not transmitted. Thereby, the black mode is implemented.

A circularly polarizing plate inspection apparatus and a circularly polarizing plate inspection method implementing a black mode according to an example of the present application may detect a defect according to the following principle.

The unpolarized light L _o provided by the lighting means 130 transmits the linearly polarized light L ₁ ' different from the above-described linearly polarized light L ₁ ' due to the defect S on the linear polarization layer. . Thereafter, the linearly polarized light L ₁ ′ is changed to the circularly polarized light L ₂ ′ while passing through the λ/4 retardation plate, and is reflected by the reflective plate 120 . Thereafter, the reflected circularly polarized light L ₃ ′ passes through the λ/4 retardation plate again, and is changed into linearly polarized light L ₄ ′ rather than a phase of 180 . Since the linearly polarized light L ₄ ′ does not have a phase of 180, it is transmitted through the polarization layer and appears outside as the reflected light L ₅ .

Although not shown separately, even when there is a defect on the λ/4 retardation plate, the reflected light L ₅ may appear to the outside as in the case where there is a defect S on the polarizing layer.

When the circular polarizing plate 110 has a defect, the incident light does not receive the polarization effect and is reflected by the reflective plate 120 , so that the color is displayed as a color having relatively high brightness compared to the non-defective part. At this time, it is possible to determine whether there is a defect in the circularly polarizing plate 110 by receiving the reflected light.

In addition, as the color that appears when there is no defect in the circularly polarizing plate 110 is closer to black, the difference in brightness appears compared to the color that appears when there is a defect, so that the defect can be more easily detected. That is, the higher the blackening (or the higher the blacking rate), the higher the defect visibility may be.

In particular, in the case of large (about 450 μm to 2,700 μm) foreign substances and scratches that make the polarization function of the corresponding part impossible, the defect inspection is relatively easy even if the blackening rate is not high. However, since the stain does not significantly interfere with the polarization function of the circularly polarizing plate 110 , it takes a long time to detect in the prior art in which the implementation of the black mode is insufficient.

On the other hand, since the circularly polarizing plate inspection apparatus and the circularly polarizing plate inspection method according to the present application implement a black mode, foreign substances and scratches as well as stains can be detected more easily compared to the prior art, and the detection time is further shortened.

Hereinafter, the present invention will be described through more specific examples. However, the following examples are only for clearly illustrating the technical features of the present invention, and do not limit the protection scope of the present invention.

<Inspection Example 1>

Prepare a reflector (light reflective glass) having a reflectivity of about 95% or more for light of a wavelength of 550 nm so that the circular polarizer can be loaded, apply an adhesive to one side of the circular polarizer to be inspected, and then attach the circular polarizer to the reflector made it In this case, the circularly polarizing plate used as the inspection object is a circularly polarizing plate.

Then, through a fluorescent lamp, which is an illumination means having a wavelength of 400 to 650 nm, about 700 to 800 lx and about 3,300 to 3,400 lm, toward the circular polarizing plate loaded on the reflection plate, the normal direction of the surface of the circular polarizing plate and about 45° The light was irradiated to form an angle.

Thereafter, defects (stains, etc.) of the circularly polarizing plate were visually observed.

The state of the inspection result of the circularly polarizing plate according to this inspection example 1 is shown in FIG. Referring to FIG. 2 , in the circularly polarizing plate inspection apparatus and the circularly polarizing plate inspection method according to the present application, it can be observed that the portion without defects of the circularly polarizing plate is highly blackened.

The L value of the Lab model defined by CIE (Commission Internationale d'Eclairage) was measured at the place where the blackening was made using a spectrophotometer. At this time, the L value was measured to be about 2 or less, and it was shown to achieve a blackening rate of 98% or more.

In addition, the time was measured from the time the adhesive was applied on one surface of the circularly polarizing plate to the detection of defects through a visual inspection, and each was independently measured 20 times. The average of each measurement result was about 3 minutes/time.

In addition, 30 sheets of good products and 30 sheets of defective products were provided to three inspectors in any order, and the inspection of the circularly polarizing plate according to Inspection Example 1 was repeated three times. As a result, while inspecting a total of 180 sheets (60 sheets X 3 times), there was one detection error that judged a good product as a defective product or a defective product as a good product. The detection accuracy was shown. In this case, the detection accuracy was calculated as {1-(number of error occurrence/total number of inspections)}*100.

As such, in the inspection of the circular polarizer according to Inspection Example 1, it is possible to improve the visibility of defects in the circular polarizer by implementing sufficient blackening, and to increase the detection accuracy by having high inspection reproducibility.

<Comparative test example 1>

A reflectance of about 11% (light-transmitting glass) for light of a wavelength of 550 nm was prepared so that the circularly polarizing plate could be loaded, and an adhesive was applied to one surface, and then the circularly polarizing plate to be inspected was bonded. In this case, the circularly polarizing plate used as the inspection object is a circularly polarizing plate.

Then, through a fluorescent lamp, which is a lighting means having a wavelength of 400 to 650 nm, about 700 to 800 lx and about 3,300 to 3,400 lm, toward the circular polarizing plate loaded on the plate, the normal direction of the surface of the circular polarizing plate and about 45° The light was irradiated to form an angle.

Thereafter, defects (stains, etc.) of the circularly polarizing plate were visually observed.

The state of the inspection result of the circularly polarizing plate according to Comparative Inspection Example 1 is shown in FIG. 3 . Referring to FIG. 3 , it can be observed that blackening is lower than that of Inspection Example 1.

The L value of the Lab model defined by CIE (Commission Internationale d'Eclairage) was measured for the relatively dark part using a spectrophotometer. At this time, the L value was measured to be about 26.2, and it was shown to achieve a blackening rate of 73.8%.

Referring to FIG. 4 in which the results of the test according to Test Example 1 and the results according to Comparative Test Example 1 are side-by-side compared, the difference between them can be observed more clearly.

Referring to FIG. 4 , the left is the test result of Comparative Test Example 1, and the right is the test result of Test Example 1. It can be seen that the blackening is higher on the right side than on the left side. In addition, on the right side, stains and the like are easily observed through high blackening, whereas on the left side, stains and the like are difficult to observe due to relatively low blackening. In addition, since light is transmitted on the left side, the visibility of defects of the circularly polarizing plate is low.

In addition, the time was measured from the time the adhesive was applied to one surface of the circularly polarizing plate until the stain was detected through a visual inspection, and each was independently measured 20 times. The average of each measurement result was about 5 minutes/time.

<Comparative test example 2>

A reflecting plate (light reflective glass) having a reflectance of about 95% for light of a wavelength of 550 nm was prepared so that the circularly polarizing plate could be loaded, and an adhesive was applied to one side, and then the circularly polarizing plate to be inspected was bonded. In this case, the circularly polarizing plate used as the inspection object is a circularly polarizing plate.

Then, through a fluorescent lamp, which is a lighting means having a wavelength of 400 to 650 nm, about 1,500 to 2,000 lx, and about 3,300 to 3,400 lm, toward the circularly polarizing plate loaded on the plate, the normal direction of the surface of the circularly polarizing plate and about 45° The light was irradiated to form an angle.

Thereafter, defects (stains, etc.) of the circularly polarizing plate were visually observed.

The blackening rate of Comparative Test Example 2 was calculated in the same manner as in Test Example 1, and was found to be about 70%. In addition, the visibility with respect to the defect of a circularly polarizing plate was also low.

<Comparative test example 3>

A reflecting plate (light reflective glass) having a reflectance of about 95% for light of a wavelength of 550 nm was prepared so that the circularly polarizing plate could be loaded, and an adhesive was applied to one side, and then the circularly polarizing plate to be inspected was bonded. In this case, the circularly polarizing plate used as the inspection object is a circularly polarizing plate.

Then, through a fluorescent lamp, which is a lighting means having a wavelength of 400 to 650 nm, about 1,500 to 2,000 lx and about 5,000 to 6,000 lm, toward the circular polarizing plate loaded on the plate, the normal direction of the surface of the circular polarizing plate and about 45° The light was irradiated to form an angle.

Thereafter, defects (stains, etc.) of the circularly polarizing plate were visually observed.

The blackening rate of Comparative Test Example 4 was calculated in the same manner as in Test Example 1, and was found to be about 68%. In addition, the visibility with respect to the defect of a circularly polarizing plate was also low.

In the above, the configuration and characteristics of the present application have been described based on the example according to the present application, but the present application is not limited thereto, and it is understood that various changes or modifications can be made within the spirit and scope of the present application. It is apparent to those skilled in the art that such changes or modifications fall within the scope of the appended claims.

10: circularly polarizing plate inspection device 120: reflector
110: circular polarizer 130: lighting means

Claims (14)

An inspection device for a circularly polarizing plate comprising a linearly polarizing layer and a retardation layer formed on one surface of the linearly polarizing layer,
a reflector installed so that the circularly polarizing plate can be loaded; and
Circularly polarizing plate inspection apparatus comprising a lighting means installed to irradiate light toward the circularly polarizing plate loaded on the reflection plate.
According to claim 1,
The reflector is a circular polarizing plate inspection device that has a reflectance of 80% or more for light with a wavelength of 550 nm.
According to claim 1,
The lighting means is a circularly polarizing plate inspection device that is installed to irradiate light forming an angle within the range of 0° to 60° with the normal direction of the surface of the circularly polarizing plate loaded on the reflecting plate.
According to claim 1,
The illuminating means is a circularly polarizing plate inspection device which is installed so as to irradiate light of a wavelength within the range of 400 nm to 650 nm toward the circularly polarizing plate loaded on the reflecting plate.
According to claim 1,
The lighting means is a circularly polarizing plate inspection device that is installed to irradiate light of an illuminance within the range of 500 lx to 1,000 lx toward the circularly polarizing plate loaded on the reflecting plate.
The method of claim 1,
The lighting means is a circularly polarizing plate inspection device that is installed so as to irradiate light of a luminous flux within the range of 3,200 lm to 3,500 lm toward the circularly polarizing plate loaded on the reflecting plate.
According to claim 1,
Circularly polarizing plate inspection apparatus further comprising a defect measuring unit installed to measure the defects of the circularly polarizing plate.
A method for inspecting a circularly polarizing plate comprising a linearly polarizing layer and a retardation layer formed on one surface of the linearly polarizing layer,
While irradiating light toward the circularly polarizing plate loaded on the reflector, the circularly polarizing plate inspection method for checking the defects of the circularly polarizing plate.
9. The method of claim 8,
A circularly polarizing plate inspection method in which the circularly polarizing plate is loaded on the reflective plate so that the retardation layer is adjacent to the reflective plate compared to the linearly polarizing plate.
9. The method of claim 8,
A reflective plate is a circular polarizing plate inspection method that has a reflectance of 80% or more for light with a wavelength of 550 nm.
9. The method of claim 8,
A circularly polarizing plate inspection method for irradiating light at an angle within the range of 0° to 60° with the normal direction of the surface of the circularly polarizing plate loaded on the reflecting plate.
9. The method of claim 8,
A circularly polarizing plate inspection method of irradiating light having a wavelength in the range of 400 nm to 650 nm toward the circularly polarizing plate loaded on the reflective plate.
9. The method of claim 8,
A circularly polarizing plate inspection method of irradiating light of an illuminance within the range of 500 lx to 1,000 lx toward the circularly polarizing plate loaded on the reflecting plate.
9. The method of claim 8,
A circularly polarizing plate inspection method of irradiating light of an illuminance within the range of 3,200 lm to 3,500 lm toward the circularly polarizing plate loaded on the reflecting plate.

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