JP7776809B2 - Inspection system, inspection method, and inspection program - Google Patents

Description

This disclosure relates to an inspection system, an inspection method, and an inspection program.

Currently, inspectors visually inspect the appearance of so-called "lambda/4 wavelength components," such as lambda/4 wavelength plates or lambda/4 wavelength films, which are used to prevent external light reflection in organic EL (Electro Luminescence) displays and other devices, by sampling some components during the manufacturing process.

In response to this, it is necessary to perform visual inspections of all products and their entire surface area to ensure quality. However, in the case of transparent components such as λ/4 wavelength components, it is not easy to detect visual defects, and processing such as analyzing the polarization state of transmitted light is required.

JP 2017-116294 A Japanese Patent Application Laid-Open No. 2007-263593

However, the polarization state that makes it easy to detect visual defects differs for each inspection object, and in order to detect visual defects that occur during the manufacturing process of λ/4 wavelength components, it is desirable to use a polarization state that is appropriate for the visual defect of the component in question. Furthermore, the types of visual defects that occur during the manufacturing process of λ/4 wavelength components vary (size, shape, pattern, etc.), and during visual inspection, it is desirable to provide images that clearly show the type of visual defect so that it can be recognized.

One aspect of this is to provide images that clearly show visual defects during visual inspection of λ/4 wavelength components.

According to one aspect, the inspection system comprises:
An inspection system for inspecting the appearance of a λ/4 wavelength member, comprising:
a light emitting portion that emits light;
a light receiving unit that receives light that is emitted from the light emitting unit, reaches the λ/4 wavelength member via a polarizing member that forms an angle of 45° or 135° with respect to the polarization angle with respect to the slow axis of the λ/4 wavelength member, and is transmitted through the λ/4 wavelength member, and is separated into a direction of 0° and a direction of 90° with respect to the polarization angle of the polarizing member;
an image generating unit that calculates _s1 constituting a Stokes parameter using a light receiving signal output from the light receiving unit, and generates an image based on _s1 constituting the calculated Stokes parameter ,
The wavelength of the light emitted by the light emitting portion is a wavelength at which the phase angle of the light transmitted through the λ/4 wavelength member is shifted from 90° by an angle range of at least 5° to 15° .

When inspecting the appearance of λ/4 wavelength components, it is possible to provide images that clearly show visual defects.

FIG. 1 is a first diagram showing an example of a system for examining a configuration for making visible defects in a λ/4 wavelength member; FIG. 10 is a second diagram showing an example of a system for examining a configuration for making visible defects in a λ/4 wavelength member; FIG. 10 is a first diagram showing the results of a study on a process for making a defect in appearance apparent; FIG. 10 is a second diagram showing the results of a study on the manifestation process for the appearance defect. FIG. 1 is a diagram illustrating an example of a system configuration of an inspection system according to a first embodiment. FIG. 2 illustrates an example of a hardware configuration of an image generating apparatus. FIG. 2 is a diagram illustrating an example of a functional configuration of an image generating apparatus. FIG. 10 is a diagram showing details of the S ₁ ′ image generation process performed by the image generation device. 10A and 10B are diagrams illustrating details of sensitivity correction processing performed by the image generating device. 4 is a flowchart showing a flow of an inspection process by the inspection system according to the first embodiment. FIG. 10 is a diagram illustrating an example of a system configuration of an inspection system according to a second embodiment. FIG. 10 is a third diagram showing an example of a system for examining a configuration for making appearance defects of a λ/4 wavelength member apparent. FIG. 10 is a third diagram showing the results of a study on the manifestation process for the appearance defect. 10 is a flowchart showing the flow of an inspection process by an inspection system according to a fourth embodiment.

Each embodiment will be described below with reference to the accompanying drawings. Note that in this specification and drawings, components that have substantially the same functional configuration will be assigned the same reference numerals, and redundant explanations will be omitted.

[First embodiment]
<Overview of inspection subjects>
First, an overview of a λ/4 wavelength component, which is the object of inspection by the inspection system according to the first embodiment, will be described. λ/4 wavelength components are components used to prevent reflection of external light in organic EL displays and the like, and include both λ/4 wavelength films and λ/4 wavelength plates. When a λ/4 wavelength component has a thickness thinner than other regions, the phase difference of light passing through the region is shifted relative to the phase difference of light passing through other regions, and this is recognized as a defective appearance. Note that λ/4 does not strictly refer to 90°, but refers to an angle range of approximately 90°±15°.

There are several factors that can cause some areas to be thinner than other areas during the manufacturing process of λ/4 wavelength components. In this embodiment, the types of appearance defects for each factor are referred to as "spot unevenness," "coating streaks," "horizontal unevenness," and "flow direction streaks."

Note that during visual inspection, the λ/4 wavelength components being inspected may either have a polarizing element laminated thereon or not. Polarizing elements in this context include both polarizing films and polarizing plates.

In the first embodiment, we will explain the case where the inspection target is a λ/4 wavelength component that does not have a polarizing component laminated thereon. However, when considering the configuration for making visual defects more apparent, we will consider the optimal polarization state that can make visual defects more apparent in any case of the inspection target.

<System under consideration>
A system for examining the optimal polarization state that can reveal visual defects of a λ/4 wavelength component is described below. As described above, visual defects of a λ/4 wavelength component are caused by a shift in the phase difference of light transmitted through a certain region. The shift in the phase difference of light can be revealed in the polarization state. Therefore, in examining the optimal polarization state, the applicant focused on the Stokes parameters, which can express various polarization states.

The Stokes parameters are composed of four types of parameters, s ₀ to s ₃ , and when calculating each parameter,
0° linearly polarized signal,
45° linearly polarized signal,
90° linearly polarized signal,
135° linearly polarized signal,
Right-handed circularly polarized signal,
Left-handed circularly polarized signal,
is used.

Figures 1A and 1B are the first and second diagrams showing an example of a system for examining a configuration that exposes visual defects in a λ/4 wavelength component, and show a system for acquiring each polarization signal used to calculate the above parameters.

1A shows an example of a system for receiving a 0° linearly polarized signal and a 90° linearly polarized signal, which are used to calculate parameters s ₀ and s _1. As shown in FIG. 1A, light emitted from a light emitting unit 110 passes through a polarizing member 120, reaches a λ/4 wavelength member 130, and is further transmitted through a λ/4 wavelength member 140 before being received by a light receiving unit 150.

As mentioned above, in the first embodiment, the inspection target is a λ/4 wavelength component that does not have a polarizing component stacked on it. However, in order to consider the optimal polarization state that can be applied even when the inspection target is a λ/4 wavelength component that has a polarizing component stacked on it, the system is configured so that light reaches the λ/4 wavelength component 130 via the polarizing component 120.

As shown by arrow 121, the polarization angle of the polarizing element 120 is either 45° or 135° with respect to the slow axis (arrow 131) of the λ/4 wavelength element 130. This is to achieve the same relationship between the slow angle of the λ/4 wavelength element on which the polarizing element is stacked and the polarization angle of the polarizing element.

Also, in FIG. 1A, arrow 141 indicates the slow axis of the λ/4 wavelength member 140. As shown in FIG. 1A, the slow axis of the λ/4 wavelength member 140 is 0°.

The light receiving unit 150 is a polarization camera. As indicated by the reference numeral 151, each pixel of the light receiving unit 150 has an area 152 that receives a 0° linearly polarized signal and an area 154 that receives a 90° linearly polarized signal.

As a result, according to the light receiving unit 150 of FIG. 1A,
- Image based on 0° linearly polarized signal (0° polarized image),
- Images based on 90° linearly polarized signals (90° polarized images),
can be output.

1B shows an example of a system for receiving a 45° linearly polarized signal, a 135° linearly polarized signal, a right-handed circularly polarized signal, and a left-handed circularly polarized signal, which are used to calculate parameters _s2 and _s3 . As shown in FIG. 1B, light emitted from a light emitting unit 110 reaches a λ/4 wavelength member 130 via a polarizing member 120, and is then received by a light receiving unit 150 after passing through a λ/4 wavelength member 160.

As indicated by arrow 121, the polarization angle of the polarizing element 120 is either 45° or 135° with respect to the slow axis (arrow 131) of the λ/4 wavelength element 130. Furthermore, as indicated by arrow 161, the slow axis of the λ/4 wavelength element 160 is 45°.

The light receiving unit 150 is a polarization camera. As indicated by the reference numeral 151, each pixel of the light receiving unit 150 has an area 153 that receives a 45° linearly polarized signal, an area 155 that receives a 135° linearly polarized signal, an area 152 that receives a right-handed circularly polarized signal, and an area 154 that receives a left-handed circularly polarized signal.

As a result, according to the light receiving unit 150 of FIG.
- Images based on 45° linearly polarized signals (45° polarized images),
- Images based on 135° linearly polarized signals (135° polarized images),
- an image based on a right-handed circularly polarized signal (right-handed circularly polarized image);
- An image based on a left-handed circularly polarized signal (left-handed circularly polarized image),
can be output.

<Polarization state study results>
Next, the optimal polarization state is examined based on each image generated using the above system. The above system calculates Stokes parameters using each image output from the light receiving unit 150, thereby generating an image corresponding to each parameter. Therefore, by comparing the images corresponding to each generated parameter, it is possible to identify the optimal polarization state that can reveal visual defects contained in the λ/4 wavelength member 130 being inspected. Figure 2A is a first diagram showing the results of an examination of the process of revealing visual defects.

2A, when generating an image corresponding to each parameter, normalized Stokes parameters S' are calculated. The normalized Stokes parameters S' are composed of four parameters, s ₀ , s ₁ ', s ₂ ', and s ₃ ', of which s ₁ ', s ₂ ', and s ₃ ' are respectively
・_s1 '= _s1 / _s0 ,
・_s2 '= _s2 / _s0 ,
・_s3 '= _s3 / _s0 ,
It is calculated as follows.

The parameter _s0 is light intensity, and the image generated by calculating the parameter _s0 is generated by adding a 0° polarized image and a 90° polarized image, as shown in FIG. 2A . The image generated by calculating the parameter _s1 is generated by subtracting a 0° polarized image and a 90° polarized image, as shown in FIG. 2A . The image generated by calculating the parameter _s2 is generated by subtracting a 45° polarized image and a 135° polarized image, as shown in FIG. 2A . The image generated by calculating the parameter _s3 is generated by subtracting a right-handed circularly polarized image and a left-handed circularly polarized image, as shown in FIG. 2A .

In Figure 2A, reference numerals 201 to 204 represent images corresponding to each parameter generated by calculating the normalized Stokes parameter S' for the λ/4 wavelength member 130 containing spot unevenness.

Of these,
Reference numeral 201 denotes an image ( _S0 image) generated by calculating the parameter _s0 ;
Reference numeral 202 denotes an image (S ₁ ′ image) generated by calculating the parameter s ₁ ′;
Reference numeral 203 denotes an image (S ₂ ′ image) generated by calculating the parameter s ₂ ′;
Reference numeral 204 denotes an image (S ₃ ′ image) generated by calculating the parameter s ₃ ′;
are shown respectively.

In addition, in Figure 2A, reference numerals 211 to 214 denote images corresponding to each parameter generated by calculating the normalized Stokes parameter S' for the λ/4 wavelength member 130 containing horizontal step unevenness.

Of these,
Reference numeral 211 denotes an image ( _S0 image) generated by calculating the parameter _s0 ;
Reference numeral 212 denotes an image (S ₁ ′ image) generated by calculating the parameter s ₁ ′;
Reference numeral 213 denotes an image (S ₂ ′ image) generated by calculating the parameter s ₂ ′;
Reference numeral 214 denotes an image (S ₃ ′ image) generated by calculating the parameter s ₃ ′;
are shown respectively.

As is clear from FIG. 2A, of the four parameters that make up the Stokes parameters, the image (S ₁ ' image) generated by calculating parameter s ₁ ' is able to most clearly show spot unevenness and horizontal stripe unevenness, and has high visibility.

Similar visualization processing was also performed on other appearance defects, resulting in the results shown in Figure 2B. Figure 2B is a second diagram showing the results of the investigation into the visualization processing for appearance defects. As shown in Figure 2B, the image ( _S1 ' image) generated by calculating the parameter _s1 ' was also able to visualize coating streaks and machine direction streaks most effectively, demonstrating high visibility.

Therefore, in the inspection system according to the first embodiment, of the Stokes parameters that can express the polarization state, the normalized parameter s ₁ ', which can generate an image with high visibility of appearance defects, is used as the parameter that expresses the optimal polarization state.

<System configuration of the inspection system>
Next, a system configuration of an inspection system according to a first embodiment, which performs visual inspection under the above-described optimal polarization state, will be described. Fig. 3 is a diagram showing an example of the system configuration of the inspection system according to the first embodiment.

As shown in FIG. 3, the inspection system 300 according to the first embodiment includes a light emitting unit 310, a polarizing element 320, a light receiving unit 330, an image generating device 340, and a display device 350. The inspection object of the inspection system 300 according to the first embodiment is a λ/4 wavelength element 360 that does not have a polarizing element laminated thereon, and is a long element that is transported in a transport direction 371 by a transport unit (not shown). The long element referred to here includes a long film. The slow axis (symbol 361) of the λ/4 wavelength element 360 is shifted by 45° or 135° with respect to the transport direction 371.

The light emitting unit 310 is positioned below the transport path of the λ/4 wavelength member 360 and emits light toward the λ/4 wavelength member 360 transported by the transport unit to an upper inspection position.

The polarizing element 320 is positioned between the inspection position in the transport path of the λ/4 wavelength element 360 and the light emitting unit 310. As a result, the light emitted by the light emitting unit 310 reaches the λ/4 wavelength element 360 via the polarizing element 320. The polarizing element 320 is a polarizing element in which the angle between the polarization angle (reference symbol 321) and the slow axis (reference symbol 361) of the λ/4 wavelength element is 45° or 135°.

The light receiving unit 330 receives light that has passed through the λ/4 wavelength member 360 at the inspection position. The light receiving unit 330 has a prism spectrometer 331, which splits the light that has passed through the λ/4 wavelength member into a 0° direction and a 90° direction relative to the polarization angle (reference symbol 321) of the polarizing member 320. The light split in the 0° direction is received by the polarized line camera 332, which generates a 0° polarized image. The light split in the 90° direction is received by the polarized line camera 333, which generates a 90° polarized image.

The 0° direction in which light is separated relative to the polarization angle (reference symbol 321) of the polarizing element 320 is parallel to the conveying direction 371 when the conveying unit conveys the λ/4 wavelength element, which is a long-sized element. The 90° direction in which light is separated relative to the polarization angle (reference symbol 321) of the polarizing element 320 is perpendicular to the conveying direction 371 when the conveying unit conveys the λ/4 wavelength element, which is a long-sized element.

The 0° polarized image generated by the polarized line camera 332 and the 90° polarized image generated by the polarized line camera 333 are transmitted to the image generation device 340.

The image generating device 340 calculates the parameter s ₁ ' based on the 0° polarized image and the 90° polarized image transmitted from the light receiving unit 330, thereby generating an image that visualizes the appearance defects contained in the λ/4 wavelength member 360. The image generating device 340 displays the image that visualizes the appearance defects on the display device 350.

<Hardware configuration of image generating device>
Next, the hardware configuration of the image generation device 340 will be described. Fig. 4 is a diagram showing an example of the hardware configuration of the image generation device. As shown in Fig. 4, the image generation device 340 has a processor 401, a memory 402, an auxiliary storage device 403, an I/F (Interface) device 404, a communication device 405, and a drive device 406. Note that the various hardware components of the image generation device 340 are connected to each other via a bus 407.

The processor 401 has various computing devices such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processor 401 reads various programs (e.g., inspection programs) into the memory 402 and executes them.

Memory 402 includes a primary storage device such as ROM (Read Only Memory) and RAM (Random Access Memory). The processor 401 and memory 402 form what is known as a computer, and the computer realizes various functions by the processor 401 executing various programs loaded onto memory 402.

The auxiliary storage device 403 stores various programs and various data used when the various programs are executed by the processor 401.

The I/F device 404 is a device for connecting the display device 350 and operation device 410 with the image generation device 340. The I/F device 404 accepts operations by the inspector 351 on the image generation device 340 via the operation device 410. The I/F device 404 also outputs images generated by the image generation device 340 and displays them to the inspector 351 via the display device 350.

The communication device 405 is a communication device for communicating with other devices (e.g., the light receiving unit 330) via a network (not shown).

The drive device 406 is a device for loading the recording medium 420. The recording medium 420 here includes media that record information optically, electrically, or magnetically, such as CD-ROMs, flexible disks, and magneto-optical disks. The recording medium 420 may also include semiconductor memory that records information electrically, such as ROM and flash memory.

The various programs installed in the auxiliary storage device 403 are installed, for example, by inserting the distributed recording medium 420 into the drive device 406 and reading the various programs recorded on the recording medium 420 using the drive device 406. Alternatively, the various programs installed in the auxiliary storage device 403 may be installed by downloading them from a network (not shown) via the communication device 405.

<Functional configuration of image generating device>
Next, the functional configuration of the image generation device 340 will be described. FIG. 5 is a diagram showing an example of the functional configuration of the image generation device. As described above, an inspection program is installed in the image generation device 340, and by executing this program, the image generation device 340 functions as a 0° polarized image acquisition unit 501 and a 90° polarized image acquisition unit 502. The image generation device 340 also functions as an S ₀ image generation unit 503, an S ₁ image generation unit 504, an S ₁ ' image generation unit 505, an S ₁ '' image generation unit 506, a detection processing unit 507, and a display control unit 508.

The 0° polarized image acquisition unit 501 acquires the 0° polarized image transmitted from the polarized line camera 332. The 0° polarized image acquisition unit 501 notifies the _S0 image generation unit 503 and the _S1 image generation unit 504 of the acquired 0° polarized image.

The 90° polarized image acquisition unit 502 acquires the 90° polarized image transmitted from the polarized line camera 333. The 90° polarized image acquisition unit 502 notifies the _S0 image generation unit 503 and the _S1 image generation unit 504 of the acquired 90° polarized image.

The S ₀ image generation unit 503 generates an S 0 image by adding the 0° polarized image notified from the 0° polarized image acquisition unit 501 and the 90° polarized image notified from the 90° polarized image acquisition unit 502. The S ₀ image generation unit 503 notifies the S _{1 ′} image generation unit 505 of the generated S ₀ image.

The _S1 image generation unit 504 generates an S1 image by calculating the difference between the 0° polarized image notified from the 0° polarized image acquisition unit 501 and the 90° polarized image notified from the 90° polarized image acquisition unit 502. _{The S1 image} generation unit 504 notifies the _S1 ′ image generation unit 505 of the generated _S1 image.

The S ₁ ' image generation unit 505 generates the S _{1 '} image by dividing the S ₁ image notified from the S ₁ image generation unit 504 by the S ₀ image notified from the S 0 image generation unit 503. Here, it is assumed that the S ₁ ' image generated by the S ₁ ' image generation unit 505 is an S ₁ ' image generated based on a 0° linear polarization signal and a 90° linear polarization signal received in the absence of the λ/4 wavelength member 360 and the polarization member 320. In this case, the S _{1 '} image generation unit 505 stores the S ₁ ' image in the correction image storage unit 510 as a correction image.

The S _{1 ' image generated based on the 0° linear polarization signal and the 90° linear polarization signal received without the λ/4 wavelength member 360 and the polarizing member 320 is an image resulting from the difference in sensitivity between the polarization line camera 332 and the polarization line camera 333, and is therefore noise. Therefore, as described above, the S 1} ' image generating unit 505 stores the S ₁ ' image generated based on the 0° linear polarization signal and the 90° linear polarization signal received without the λ/ ₄ wavelength member 360 and the polarizing member 320 in the correction image storage unit 510 as a correction image.

On the other hand, suppose that the S _{1 ' image generated by the S 1} ' image generation unit 505 is an S ₁ ' image generated based on the 0° linear polarization signal and the 90° linear polarization signal received in the presence of the λ/4 wavelength member 360 and the polarizing member 320. In this case, the S _{1 '} image generation unit 505 notifies the S ₁ '' image generation unit 506 of the generated S ₁ ' image.

The S ₁ '' image generation unit 506 removes noise from the S ₁ '' image by subtracting the correction image stored in the correction image storage unit 510 from the S ₁ '' image notified by the S ₁ '' image generation unit 505. In this way, the S ₁ '' image generation unit 506 corrects the sensitivity difference between the polarization line camera 332 and the polarization line camera 333, and generates an S ₁ '' image, which is the corrected S ₁ '' image. The S ₁ '' image generation unit 506 notifies the detection processing unit 507 and the display control unit 508 of the generated S ₁ '' image.

The detection processing unit 507 performs a visual defect detection process on the S ₁ '' image notified from the S ₁ '' image generation unit 506, and detects visual defects contained in the λ/4 wavelength member 360 that is the inspection target. Note that the visual defect detection process here may be, for example, a process of detecting an area equal to or greater than a predetermined threshold as a visual defect, or a process of detecting an area equal to or greater than a predetermined threshold and whose size and shape satisfy predetermined conditions as a visual defect.

The detection processing unit 507 also generates a rectangle circumscribing the detected area (area containing the visual defect) and extracts an S ₁ '' image (rectangular area image) of the area contained in the rectangle. The detection processing unit 507 notifies the display control unit 508 of the generated rectangle and the extracted rectangular area image.

The display control unit 508 displays the S ₁ '' image notified by the S ₁ '' image generation unit 506 on the display device 350. Furthermore, when instructed by the inspector 351, the display control unit 508 superimposes the rectangle notified by the detection processing unit 507 on the S ₁ '' image and displays it on the display device 350. Furthermore, when instructed by the inspector 351, the display control unit 508 enlarges and displays the rectangular area image notified by the detection processing unit 507 in a display area different from the display area displaying the S ₁ '' image.

<Details of processing by the image generation device>
Next, a detailed description will be given of the processing performed by each unit of the image generating device 340. Here, a detailed description will be given of the S ₁ ' image generating process performed by the S ₁ ' image generating unit 505 and the sensitivity correction process performed by the S ₁ '' image generating unit 506.

(1) Details of S ₁ ' Image Generation Processing First, details of the S ₁ ' image generation processing by the S ₁ ' image generation unit 505 will be described. FIG. 6 is a diagram showing details of the S ₁ ' image generation processing by the image generation device. As shown in FIG. 6, the S ₁ ' image generation unit 505 has an S ₁ /S ₀ calculation unit 601.

The _S1 / _S0 calculation unit 601 generates an S1 _' image by dividing the _S1 image notified from the S1 image generation unit 504 by the _S0 image notified from the _S0 image generation unit 503. Here, it is assumed that the _S1 ' image generated by the _S1 / _S0 calculation unit 601 is an _S1 ' image generated based on a 0° linear polarization signal and a 90° linear polarization signal received in the absence of the λ/ ₄ wavelength member 360 and the polarizing member 320. In this case, the _S1 / _S0 calculation unit 601 stores the _S1 ' image in the correction image storage unit 510 as a correction image.

On the other hand, suppose that the S ₁ ' image generated by the S ₁ /S ₀ calculation unit 601 is an S ₁ ' image generated based on the 0° linear polarization signal and the 90° linear polarization signal received in the presence of the λ/4 wavelength member 360 and the polarizing member 320. In this case, the S ₁ /S ₀ calculation unit 601 notifies the S ₁ '' image generation unit 506 of the generated S ₁ ' image.

(2) Details of Sensitivity Correction Processing Next, details of the sensitivity correction processing by the S ₁ ″ image generation unit 506 will be described. FIG. 7 is a diagram showing details of the sensitivity correction processing by the image generation device. As shown in FIG. 7 , the S ₁ ″ image generation unit 506 has a difference calculation unit 701, an average value calculation unit 702, an image brightness calculation unit 703, and an adjustment unit 704.

As described above, the S ₁ ″ image generation unit 506 is notified by the S ₁ /S ₀ calculation unit 601 of the S ₁ ′ image generated based on the 0° linear polarization signal and the 90° linear polarization signal received with the λ/4 wavelength member 360 and the polarization member 320 present.

In addition, the correction image storage unit 510 stores, as a correction image, an S 1 ' image generated based on a 0° linear polarization signal and a 90° linear polarization signal received in the absence of the λ/ ₄ wavelength member 360 and the polarizing member 320.

The difference calculation unit 701 removes noise from the S ₁ ' image by subtracting the correction image stored in the correction image storage unit 510 from the S ₁ ' image notified by the S ₁ ' image generation unit 505. In this way, the difference calculation unit 701 corrects the sensitivity difference between the polarization line camera 332 and the polarization line camera 333, and generates a corrected S ₁ ' image.

The difference calculation unit 701 notifies the average value calculation unit 702 and the image brightness calculation unit 703 of the corrected S ₁ ′ image.

The average value calculation unit 702 calculates the average luminance value of a 200 pixel by 200 pixel area including the center position of the corrected S ₁ ′ image. The average value calculation unit 602 notifies the image luminance calculation unit 703 of the calculated average luminance value.

The image luminance calculation unit 703 calculates the difference from the average luminance value by subtracting the average luminance value from the luminance value of each pixel in the corrected S ₁ ' image. Furthermore, to convert the luminance value of each pixel to 10 bits (1024 gradations), the image luminance calculation unit 703 multiplies the calculated difference from the average luminance value by a value obtained by dividing 1024 gradations by the display range of the display device 350. Furthermore, the image luminance calculation unit 703 adds a predetermined offset value to the luminance value after multiplication. In other words, the image luminance calculation unit 703 converts the luminance value of each pixel in the corrected S ₁ ' image to 1024 gradations based on the following formula, and calculates the converted luminance value:
(Brightness value after conversion) = (Brightness value of S ₁ ' image after correction - average brightness value) × 1024 / (display range of display device 350) + offset value In the above formula, for example, "0.08" is set as the display range of display device 350. In the above formula, for example, "511" is set as the offset value.

The image brightness calculation unit 703 notifies the adjustment unit 704 of the image for which the converted brightness values have been calculated.

If the luminance values of the pixels included in the image for which the post-conversion luminance values have been calculated and notified by the image luminance calculation unit 703 include a luminance value greater than 1023, the adjustment unit 704 adjusts the luminance value of the pixel to 1023. If the luminance values of the pixels included in the image for which the post-conversion luminance values have been calculated and notified by the image luminance calculation unit 703 include a luminance value less than 0, the adjustment unit 704 adjusts the luminance value of the pixel to 0.

Furthermore, the adjustment unit 704 notifies the detection processing unit 507 and the display control unit 508 of the image after the adjustment of the brightness value as the S ₁ '' image. If the display device 350 is 8 bit, the adjustment unit 704 further converts the S ₁ '' image from 10 bit to 8 bit before notifying the display control unit 508. The adjustment unit 704 converts the brightness value of each pixel included in the S ₁ '' image from 10 bit to 8 bit by dividing the brightness value of each pixel included in the S ₁ '' image by "4".

<Inspection processing flow by the inspection system>
Next, a description will be given of the flow of the inspection process by the inspection system 300 according to the first embodiment. Fig. 8 is a flowchart showing the flow of the inspection process by the inspection system according to the first embodiment.

In step S801, the image generating device 340 sets the display range and offset value of the display device 350 to be used in the S ₁ ' image generating process.

In step S802, the image generating device 340 generates an S ₁ ' image based on the 0° linear polarization signal and the 90° linear polarization signal received in the absence of the λ/4 wavelength element 360 and the polarizing element 320, and stores the image in the correction image storage unit 510 as a correction image.

In step S803, the inspector 351 sets the λ/4 wavelength component 360 to be inspected.

In step S804, the inspector 351 instructs the start of transport of the λ/4 wavelength member 360 to be inspected, and also instructs the start of processing by the image generating device 340. This causes the transport of the λ/4 wavelength member 360 to be inspected to start. In addition, processing by the image generating device 340 is started, and the S ₁ '' image is displayed on the display device 350.

In step S805, the image generating device 340 determines whether or not a visual defect has been detected in the λ/4 wavelength member 360 being inspected. If it is determined in step S805 that a visual defect has not been detected (NO in step S805), the process proceeds to step S807.

On the other hand, if it is determined in step S805 that a visual defect has been detected (YES in step S805), proceed to step S806.

In step S806, the image generating device 340 displays an S ₁ ″ image in which a rectangle is superimposed on the area containing the visual defect, and also displays an enlarged image of the rectangular area, thereby notifying the inspector 351 of the visual defect.

In step S807, the image generating device 340 performs a visual inspection of the entire area of the λ/4 wavelength member 360 to be inspected, and determines whether the conveying process has ended. If it is determined in step S807 that there is an area for which visual inspection has not been performed (NO in step S807), the process returns to step S805.

On the other hand, in step S807, if it is determined that the visual inspection has been performed on the entire area of the λ/4 wavelength member 360 to be inspected and the transport process has been completed (YES in step S807), proceed to step S808.

In step S808, inspector 351 determines whether to end the visual inspection. If it is determined in step S808 that the visual inspection should continue (NO in step S808), the process returns to step S802.

On the other hand, if it is determined in step S808 that the visual inspection is to be ended (YES in step S808), the inspector 351 instructs the image generation device 340 to end processing. This causes the image generation device 340 to end processing, and the inspection processing by the inspection system 300 ends.

<Summary>
As is clear from the above description, the inspection system 300 according to the first embodiment includes:
- It has a light emitting portion 310 that emits light.
The optical fiber 300 includes a light receiving unit 330 that receives light. The light emitted by the light emitting unit 310 reaches the λ/4 wavelength member 360 via a polarizing member 320, which forms an angle of 45° or 135° with the polarization angle relative to the slow axis of the λ/4 wavelength member 360. The light that has passed through the λ/4 wavelength member 360 is received by the light receiving unit 330. The light receiving unit 330 is configured to receive light that has been split into directions at 0° and 90° with respect to the polarization angle of the polarizing member 320.
The image generating device 340 calculates _s1 , which constitutes the Stokes parameter, using the received light signals (0° linear polarization signal, 90° linear polarization signal) output from the light receiving unit 330, and generates an _S1 '' image based on the calculated _s1 .

In this way, the inspection system 300 according to the first embodiment generates an image under an optimal polarization state that can reveal visual defects contained in the λ/4 wavelength member 360 and produce an image with high visibility. As a result, the inspection system 300 according to the first embodiment can provide an image that reveals visual defects during the visual inspection of the λ/4 wavelength member 360.

Second Embodiment
In the first embodiment, Fig. 3 shows an inspection system 300 for a case where a polarizing member is not laminated on a λ/4 wavelength member to be inspected. In contrast, in the second embodiment, an inspection system for a case where a polarizing member is laminated on a λ/4 wavelength member to be inspected will be described. The second embodiment will be described below, focusing on the differences from the first embodiment.

Figure 9 is a diagram showing an example of the system configuration of an inspection system according to the second embodiment. The difference from the inspection system 300 shown in Figure 3 is that the inspection system 900 shown in Figure 9 does not include a polarizing element 320. Also, in the inspection system 900 shown in Figure 9, a polarizing element 910 is stacked on the λ/4 wavelength element 360 to be inspected.

As shown in Figure 9, the polarizing member 910 is laminated on one surface of the λ/4 wavelength member 360. The λ/4 wavelength member 360 is transported so that the surface on which the polarizing member 910 is laminated faces downward (facing the light emitting section 310).

The polarizing element 910 is stacked on the λ/4 wavelength element 360 so that the angle between the polarization angle and the slow axis (reference symbol 361) of the λ/4 wavelength element is 45° or 135° (i.e., parallel to the transport direction 371).

As a result, the light emitted by the light emitting unit 310 reaches the λ/4 wavelength member 360 via the polarizing member 910, and the light that passes through the λ/4 wavelength member 360 is received by the light receiving unit 330. Note that the configuration from the light receiving unit 330 onwards is the same as that of the inspection system 300 described in the first embodiment above.

In this way, the inspection system 900 according to the second embodiment can generate images under optimal polarization conditions that can reveal visual defects and generate highly visible images, even when a polarizing element 910 is stacked on the λ/4 wavelength element 360 being inspected.

As a result, the inspection system 900 according to the second embodiment, like the first embodiment, is capable of providing images that highlight visual defects during visual inspection of the λ/4 wavelength member 360.

[Third embodiment]
In the first embodiment, an optimal polarization state capable of generating a highly visible image by making visible the appearance defects contained in the λ/4 wavelength member 360 is considered. In contrast, in the third embodiment, an optimal wavelength of light (the wavelength of light emitted from the light emitting portion) capable of generating a highly visible image by making visible the appearance defects contained in the λ/4 wavelength member 360 is considered.

<System under consideration>
First, a system for examining the optimum wavelength of light capable of revealing visual defects in a λ/4 wavelength member will be described. In the first embodiment, the wavelength of light emitted by the light emitting portion is not mentioned, but the wavelength of light emitted by the light emitting portion is also important in revealing visual defects contained in the λ/4 wavelength member 360.

Fig. 10 is a third diagram showing an example of a system for examining a configuration for revealing visual defects in a λ/4 wavelength member. The example in Fig. 10 shows an example of a system that includes three types of light emitting units, light emitting unit 1010, light emitting unit 1020, and light emitting unit 1030, and generates _S1 ' images when light is sequentially emitted from each light emitting unit to a λ/4 wavelength member 130 that has a visual defect.

The light emitted from the light emitting unit 1010 is
Red light with a wavelength of 635 nm
Phase difference of the λ/4 wavelength member 130=152 [nm],
Phase angle of light transmitted through the λ/4 wavelength member 130=86.2°
Furthermore, the light emitted from the light emitting portion 1020 is expressed as follows:
Wavelength = 515 [nm] green light,
Phase difference of the λ/4 wavelength member 130=143 [nm],
Phase angle of light transmitted through the λ/4 wavelength member 130=100.0°
Furthermore, the light emitted from the light emitting portion 1030 is expressed as follows:
Wavelength = 465 [nm] blue light,
Phase difference of the λ/4 wavelength member 130=128 [nm],
Phase angle of light transmitted through the λ/4 wavelength member 130=99.1°
is.

<Results of light wavelength study>
Next, the optimal wavelength of light is considered based on each image generated using the above system. Specifically, by comparing each S ₁ ' image generated based on the light emitted from each light emitting portion, the optimal wavelength of light that can reveal appearance defects contained in the λ/4 wavelength member 130 to be inspected is considered.

11 is a third diagram showing the results of a study on the processing for making visible appearance defects. In FIG. 11, reference numerals 1101 to 1103 denote S 1 ' images generated based on light emitted from light emitting portion 1010 to light emitted from light emitting portion 1030 for a λ/ ₄ wavelength member 130 including horizontal step unevenness.

As shown in Figure 11, of the three types of light output units, light output unit 1020 and light output unit 1030 were found to be more effective at making visual defects more apparent and providing higher visibility than light output unit 1010. In other words, a light output unit that emits light with a wavelength that is shifted by approximately 10° from the 90° phase angle at which light transmitted through the λ/4 wavelength member 130 becomes completely circularly polarized light can more effectively make visual defects more apparent and generate an image with high visibility.

Therefore, in the inspection system 300 or 900 according to the third embodiment, when the phase angle of the light transmitted through the λ/4 wavelength member 360 is θ,
5°≦｜θ-90°｜≦15°
More preferably, light having a wavelength
7.5°≦｜θ-90°｜≦12.5°
A light emitting section that emits light with a wavelength of

<Summary>
As is clear from the above description, the inspection system 300 or 900 according to the third embodiment has the following features:
It has a light emitting portion that emits light of a wavelength based on the phase angle θ of the light that has passed through the λ/4 wavelength member (light of a wavelength that satisfies 5°≦|θ−90°|≦15°).

As a result, the inspection system 300 or 900 according to the third embodiment can more clearly identify any visual defects contained in the λ/4 wavelength member 360 being inspected, thereby generating an image with high visibility.

In other words, the inspection system 300 or 900 according to the third embodiment makes it possible to provide images that more clearly show visual defects during visual inspection of the λ/4 wavelength member 360.

[Fourth embodiment]
In the above embodiments, the λ/4 wavelength member 360, which is the object of visual inspection by the inspection system 300 or 900, has been described as a long member. However, the λ/4 wavelength member, which is the object of visual inspection by the inspection system 300 or 900, is not limited to a long member and may be a sheet member. The term "sheet member" as used herein includes sheet films and sheet plates.

Even if the λ/4 wavelength element is a sheet element, the angle between the slow axis of the λ/4 wavelength element and the polarization angle of the polarizing element, and the relationship between the polarization angle of the polarizing element and the direction of the light separated by the light receiving unit, are the same as in the case of a long element.

However, when the λ/4 wavelength component to be inspected is a sheet component, the inspection process flow by inspection system 300 or 900 differs from that for long components.

Figure 12 is a flowchart showing the flow of inspection processing by the inspection system according to the fourth embodiment.

In step S801, the image generating device 340 sets the display range and offset value of the display device 350 to be used in the S ₁ ' image generating process.

In step S802, the image generating device 340 generates an S 1 ' image based on the 0° linearly polarized signal and the 90° linearly polarized signal received without the λ/4 wavelength member 360 (and the laminated polarizing member 910). The image generating device 340 also stores the generated S _{1 '} image in the correction image storage unit 510 as a correction image.

In step S1201, the image generating device 340 determines whether there is a λ/4 wavelength component to be visually inspected next. If it is determined in step S1201 that there is a λ/4 wavelength component to be visually inspected next (YES in step S1201), the process proceeds to step S1202.

In step S1202, the transport unit transports one λ/4 wavelength member 360 to be inspected to the inspection position.

In step S1203, the image generating device 340 generates the S ₁ '' image. As a result, the S ₁ '' image is displayed on the display device 350.

In step S1204, the image generating device 340 determines whether or not a visual defect has been detected in the λ/4 wavelength member being inspected. If it is determined in step S1204 that a visual defect has not been detected (NO in step S1204), the process returns to step S1201.

On the other hand, if it is determined in step S1204 that a visual defect has been detected (YES in step S1204), proceed to step S1205.

In step S1205, the image generating device 340 displays an S ₁ ″ image in which a rectangle is superimposed on the area containing the visual defect, and also displays an enlarged image of the rectangular area to notify the inspector 351 of the visual defect, and then returns to step S1201.

Also, if it is determined in step S1201 that there are no λ/4 wavelength components to be visually inspected next (NO in step S1201), proceed to step S808.

In step S808, inspector 351 determines whether to end the visual inspection. If it is determined in step S808 that the visual inspection should continue (NO in step S808), the process returns to step S802.

On the other hand, if it is determined in step S808 that the visual inspection is to be ended (YES in step S808), the inspector 351 instructs the image generation device 340 to end processing. This causes the image generation device 340 to end processing, and the inspection processing by the inspection system 300 or 900 ends.

<Summary>
As is clear from the above description, the inspection system 300 or 900 according to the fourth embodiment has the following features:
The appearance inspection is performed not only when the λ/4 wavelength member to be inspected is a long member, but also when it is a sheet member.
When the λ/4 wavelength member to be inspected is a sheet member, a transport unit is provided to transport the λ/4 wavelength member to the inspection position, similar to the case of a long member.

In this way, with the inspection system 300 or 900 according to the fourth embodiment, it is possible to make visual defects apparent and generate highly visible images regardless of whether the λ/4 wavelength component being inspected is a long component or a sheet component.

In other words, the inspection system 300 or 900 according to the fourth embodiment makes it possible to provide images that highlight visual defects during visual inspection of λ/4 wavelength members 360, regardless of whether the members are long or sheet-like members.

[Other embodiments]
In the above embodiments, normalized Stokes parameters are calculated to generate an image that visualizes a visual defect contained in a λ/4 wavelength member. However, an image may be generated by calculating the Stokes parameters without normalizing them.

Furthermore, although the above embodiments do not mention the timing for generating a correction image, the timing for generating a correction image may be, for example, the timing when the light receiving unit 330 deteriorates over time or the timing when the light emitting unit 310 deteriorates over time.

Furthermore, in each of the above embodiments, when the detection processing unit 507 detects a visual defect, it notifies the display control unit 508, which then displays the detection result to the inspector 351, thereby outputting the detection result. However, the method for outputting the detection result when the detection processing unit 507 detects a visual defect is not limited to this. For example, it may be configured to generate a CSV file indicating the detection result and output that file. Alternatively, it may be configured to notify the detection result to a defect information management system, which then marks the inspection object based on the notified detection result.

Furthermore, in the above embodiments, a case has been described in which a polarizing member is not laminated on the λ/4 wavelength member to be inspected, or a case in which a polarizing member is laminated on the λ/4 wavelength member to be inspected. However, the λ/4 wavelength member to be inspected may also be laminated with another member (e.g., a substrate) that does not affect the front retardation.

Furthermore, in each of the above embodiments, it has been described that one light receiving unit 330 is installed when performing visual inspection of a λ/4 wavelength member, but multiple light receiving units 330 may be installed depending on the width direction length of the λ/4 wavelength member.

Furthermore, in each of the above embodiments, the 0° polarized image and the 90° polarized image transmitted from one light receiving unit 330 are described as being processed by one image generating device 340, but a configuration in which multiple image generating devices 340 process them may also be used.

Note that the present invention is not limited to the configurations described in the above embodiments, and may be combined with other elements. These aspects may be modified without departing from the spirit of the present invention, and may be determined appropriately depending on the application form.

300: Inspection system 310: Light emitting section 320: Polarizing member 330: Light receiving section 331: Prism spectroscope 332: Polarized line camera 333: Polarized line camera 340: Image generating device 350: Display device 501: 0° polarized image acquiring section 502: 90° polarized image acquiring section 503: _S0 image generating section 504: _S1 image generating section 505: _S1 ' image generating section 506: _S1 '' image generating section 507: Detection processing section 508: Display control section 601: _S1 / _S0 calculation section 701: Difference calculation section 702: Average value calculation section 703: Image brightness calculation section 704: Adjustment section 910: Polarizing member

Claims (13)

An inspection system for inspecting the appearance of a λ/4 wavelength member, comprising:
a light emitting portion that emits light;
a light receiving unit that receives light that is emitted from the light emitting unit, reaches the λ/4 wavelength member via a polarizing member that forms an angle of 45° or 135° with respect to the polarization angle with respect to the slow axis of the λ/4 wavelength member, and is transmitted through the λ/4 wavelength member, and is separated into a direction of 0° and a direction of 90° with respect to the polarization angle of the polarizing member;
an image generating unit that calculates _s1 constituting a Stokes parameter using a light receiving signal output from the light receiving unit, and generates an image based on _s1 constituting the calculated Stokes parameter ,
An inspection system, wherein the wavelength of the light emitted by the light emitting unit is a wavelength at which the phase angle of the light transmitted through the λ/4 wavelength member is shifted from 90° by an angle range of at least 5° to 15° . The image generation unit
calculating s ₀ constituting a Stokes parameter using a light receiving signal output from the light receiving unit;
The image is generated using a value obtained by dividing _s1 constituting the Stokes parameter by _s0 constituting the Stokes parameter.
The inspection system of claim 1 . The image generation unit
correcting the image generated based on _s1 constituting the Stokes parameter by using a light receiving signal output by the light receiving unit when the light is received without passing through the λ/4 wavelength member and the polarizing member;
The inspection system of claim 1 . The inspection system of claim 1, wherein the polarizing element is disposed between the light emitting unit and the λ/4 wavelength element and polarizes the light emitted by the light emitting unit. The inspection system of claim 1, wherein the polarizing member is laminated on the λ/4 wavelength member. The inspection system of claim 1, wherein the λ/4 wavelength member is a sheet member or a long member. a conveying unit that conveys the λ/4 wavelength member on which the polarizing member is laminated to an inspection position;
The inspection system according to claim 5 , wherein the transport unit transports the λ/4 wavelength member on which the polarizing member is stacked so that the surface on which the polarizing member is stacked faces the light emitting unit. 8. The inspection system according to claim 7 , wherein the slow axis of the λ/4 wavelength member is shifted by 45° or 135° with respect to the conveying direction when the conveying unit conveys the long-sized member. The inspection system according to claim 7 , wherein the 0° direction in which the light is separated with respect to the polarization angle of the polarizing member is parallel to the conveying direction in which the conveying section conveys the elongated member. The inspection system according to claim 7 , wherein the 90° direction in which the light is separated relative to the polarization angle of the polarizing member is perpendicular to the conveying direction in which the conveying section conveys the elongated member. The inspection system according to claim 3 , wherein a detection process is performed on the image corrected by the image generating unit to detect defects in the appearance of the λ/4 wavelength member. An inspection method for an inspection system that inspects the appearance of a λ/4 wavelength member, comprising:
a light receiving step of receiving light that is emitted from a light emitting unit that emits light, reaches the λ/4 wavelength member via a polarizing member that forms an angle of 45° or 135° with respect to the polarization angle with respect to the slow axis of the λ/4 wavelength member, and is transmitted through the λ/4 wavelength member, and is separated into a direction of 0° and a direction of 90° with respect to the polarization angle of the polarizing member;
an image generating step of calculating _s1 constituting a Stokes parameter using the light receiving signal output in the light receiving step , and generating an image based on _s1 constituting the calculated Stokes parameter ;
an inspection method, wherein the wavelength of the light emitted by the light emitting portion is a wavelength at which the phase angle of the light transmitted through the λ/4 wavelength member is shifted from 90° by an angle range of at least 5° to 15° ; An inspection program for an inspection system that inspects the appearance of a λ/4 wavelength member,
a light receiving step of receiving light that is emitted from a light emitting unit that emits light, reaches the λ/4 wavelength member via a polarizing member that forms an angle of 45° or 135° with respect to the polarization angle with respect to the slow axis of the λ/4 wavelength member, and is transmitted through the λ/4 wavelength member, and is separated into a direction of 0° and a direction of 90° with respect to the polarization angle of the polarizing member;
an image generating step of calculating _s1 constituting a Stokes parameter using the light receiving signal output in the light receiving step , and generating an image based on _s1 constituting the calculated Stokes parameter ;
The wavelength of the light emitted by the light emitting unit is a wavelength at which the phase angle of the light transmitted through the λ/4 wavelength member is shifted from 90° by an angle range of at least 5° to 15° .