JP5446232B2 - Defect inspection apparatus and defect inspection method for color filter substrate - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method for inspecting a defect in a retardation film and a foreign matter on the retardation film in a color filter having the retardation film.

  In recent years, with the development of personal computers, the increase in size of liquid crystal televisions and the spread of mobile phones, demand for color liquid crystal displays tends to increase. While the substrate size has become large and the amount of capital investment and necessary space has become enormous, there is a great demand for cost reduction for each display member. It can be said that the problem of how high-value-added members can be supplied at low cost has become a problem related to the survival of manufacturers related to liquid crystal peripheral members.

  In view of this, a technique has been developed in which a retardation film used for compensating the viewing angle of a liquid crystal display or realizing a transflective display is formed in-cell in a color filter constituting the liquid crystal display (see Patent Document 1). As a result, the panel was made thinner and the cost was reduced.

  In the formation process of the retardation film, defects such as pinholes may appear in the retardation film due to physical causes or mask shadows at the time of exposure. However, since the retardation film is transparent, the retardation film cannot be visualized by a normal color filter defect inspection method. That is, even if a defect portion exists in the retardation film, it does not appear as an abnormality such as a luminance value on the image, so that the defect cannot be detected.

  However, in order to improve the yield of products, immediately after the formation of the retardation film on the color filter, defects in the retardation film and foreign matters on the retardation film are detected, and the color filter substrate with the defective portion is processed downstream. It is essential to have an inspection method that can prevent it from flowing into the water.

JP 2007-332260 A

  The present invention has been made in view of such a situation, and an object thereof is to provide a method for detecting a retardation film defect in a color filter having a retardation film.

In order to achieve the above object, in claim 1 of the present invention, an inspection apparatus for detecting defects in a retardation film and foreign matters on the retardation film in a color filter substrate having a retardation film,
A first polarizing filter and a second polarizing filter disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other;
A transmitted illumination light source disposed outside the first polarizing filter;
Imaging means disposed outside the second polarizing filter;
Image processing means for performing predetermined image processing on the image data acquired by the imaging means and detecting defects and foreign matter ;
An inspection apparatus for a color filter substrate having a retardation film, wherein the first and second polarizing filters are arranged in a state in which polarization optical axis directions form an angle of 35 ° to 55 ° with each other. It is a thing.

Further, in claim 2 of the present invention, an inspection apparatus for detecting defects in the retardation film and foreign matters on the retardation film in a color filter substrate having the retardation film,
A first polarizing filter and a second polarizing filter disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other;
A first transmitted illumination light source disposed outside the first polarizing filter;
First imaging means disposed outside the second polarizing filter;
A third polarizing filter and a fourth polarizing filter disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other;
A second transmitted illumination light source disposed outside the third polarizing filter;
A second imaging means disposed outside the fourth polarizing filter;
Image processing means for performing predetermined image processing on the image data respectively acquired by the first imaging means and the second imaging means and detecting defects and foreign matters;
The first polarizing filter and the second polarizing filter are arranged so that their polarization optical axis directions are parallel to each other, and the third polarizing filter and the fourth polarizing filter are arranged so that their polarization optical axis directions are perpendicular to each other. The present invention provides an inspection apparatus for a color filter substrate having a retardation film.

Further, in claim 3 of the present invention, there is provided an inspection method for detecting defects in the retardation film and foreign matters on the retardation film in the color filter substrate having the retardation film,
A first polarizing filter and a second polarizing filter are disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other,
Illuminating light irradiation step of irradiating the color filter substrate with illuminating light from a transmitted illumination light source disposed outside the first polarizing filter;
An imaging step of acquiring image data of the color filter substrate by an imaging means disposed outside the second polarizing filter;
Performing predetermined image processing on the image data acquired in the imaging step and detecting defects and foreign matter ; and
An imaging step of acquiring image data of the color filter substrate in a state where the polarization optical axis directions of the first and second polarizing filters form an angle of 35 ° to 55 ° with each other;
An image processing stage that performs predetermined image processing on the image data acquired in the imaging stage and detects defects and foreign matter;
In this method, the color filter substrate having a retardation film is inspected.

Further, in claim 4 of the present invention, in the color filter substrate having the retardation film, an inspection method for detecting defects in the retardation film and foreign matters on the retardation film,
On both sides of the color filter substrate, a first polarizing filter and a second polarizing filter arranged at positions parallel to the color filter substrate and facing each other are arranged,
An illumination light irradiation step of irradiating the color filter substrate with illumination light from a first transmitted illumination light source disposed outside the first polarizing filter;
An imaging step of acquiring image data of the color filter substrate by a first imaging means disposed outside the second polarizing filter;
On both sides of the color filter substrate, a third polarizing filter and a fourth polarizing filter arranged at positions parallel to the color filter substrate and facing each other are arranged,
Illuminating light irradiation step of irradiating the color filter substrate with illuminating light from a second transmitted illumination light source arranged outside the third polarizing filter;
An imaging step of acquiring image data of the color filter substrate by a second imaging means disposed outside the fourth polarizing filter;
An image processing step of performing predetermined image processing on the image data respectively acquired by the first imaging unit and the second imaging unit and detecting defects and foreign matters;
The first polarizing filter and the second polarizing filter are arranged so that their polarization optical axis directions are parallel to each other, and the third polarizing filter and the fourth polarizing filter are arranged so that their polarization optical axis directions are perpendicular to each other. This is a method for inspecting a color filter substrate having a retardation film.

According to claim 5 of the present invention, in the image processing stage of the inspection method for a color filter substrate having a retardation film according to claim 4 ,
For the image data of the color filter substrate obtained by using the first and second polarizing filters whose polarization optical axis directions are parallel to each other, a pinhole in the retardation region of the retardation film is used. Detect foreign objects on defects and no phase difference area,
For the image data of the color filter substrate obtained by using the third and fourth polarizing filters whose polarization optical axis directions are perpendicular to each other, a pinhole in the retardation region of the retardation film is used. The present invention provides an inspection method for a color filter substrate having a retardation film, characterized by detecting defects and foreign matter on the retardation film.

  By using the apparatus according to any one of claims 1 to 3 of the present invention and carrying out the inspection by the method according to any one of claims 4 to 9, a phase difference is formed immediately after the formation of the phase difference film on the color filter. Defects in the film and foreign substances on the retardation film can be detected, and a defective substrate can be prevented from flowing into the downstream process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a retardation film defect inspection apparatus for a color filter having a retardation film according to an embodiment of the present invention.

  On both sides of a color filter substrate 3 having a retardation film to be inspected, linearly polarized polarizing filters 2 and 4 are arranged in parallel to the substrate 3 so as to face each other. The transmitted illumination 5 is disposed outside the polarizing filter 4, and the image sensor 1 is disposed outside the polarizing filter 2. The image sensor 1 and the image processing unit 6 are connected by a signal line.

  The illumination light emitted from the transmitted illumination 5 is converted into linearly polarized light by the polarizing filter 4, and then converted into elliptically polarized light in the phase difference region in the in-cell phase difference film of the color filter substrate 3 and transmitted through the color filter substrate 3. . The illumination light that has passed through the color filter substrate 3 becomes linearly polarized light again by the polarization filter 2 and is received by the image sensor 1.

  In this way, the image sensor 1 acquires the light transmitted through the polarizing filter 2, the color filter substrate 3, and the polarizing filter 4 as image data. The image data acquired by the image sensor 1 is sent to the image processing unit 6 through a signal line, and predetermined image processing is performed to detect a defect.

  The structure of the color filter substrate 3 having the retardation film to be inspected is as shown in FIG. 6, where [a] in FIG. 6 is a top view and [b] is a cross-sectional view. A black matrix 301 is formed on a transparent glass substrate 306, and a transparent alignment film 302 is applied thereon. Further, a transparent retardation film 303 is applied thereon, but is applied separately in two regions 304 and 305 having different phase differences.

  The phase difference region 304 converts linearly polarized light into elliptically polarized light, but since the region 305 is a non-phase difference region, linearly polarized light is not converted into elliptically polarized light.

  It is assumed that the pinhole 7 and the foreign material 8 exist in the phase difference region 304 and the foreign material 9 exists in the region 305. Note that since the region 305 is a non-phase difference region, the presence of pinhole defects does not affect the quality of the color filter. Therefore, pinhole defects in the non-phase difference region are not subjected to inspection here.

  As the image sensor 1, a camera using an element such as a CCD or a CMOS can be used. Further, it is possible to appropriately select which of the area sensor camera and the line sensor camera is used, but it is necessary to consider the combination with the transmission illumination 5 and a transport means (not shown).

  The transmitted illumination 5 is an illumination light source that irradiates parallel light of uniform brightness to the imaging region of the image sensor 1 of the color filter substrate 3 through the polarizing filter 4, and a transmission light, for example, is used. The light to be irradiated is preferably white light, but may be light having a spectrum in the visible range.

  When the image sensor 1 is an area sensor, the transport unit repeatedly transports and stops the color filter substrate 3. That is, when the area sensor images a predetermined imaging area when the color filter substrate 3 is stopped, the conveying means performs conveyance so that the next imaging target area comes to the imaging position of the area sensor. Such an operation is repeated as appropriate. As will be described later, when the same imaging region is imaged twice while changing the polarization direction of the polarization filter, if the polarization direction of the polarization filter 2 or 4 is adjusted when the color filter substrate 3 is stopped, the image is captured twice. Good.

  In the case where the image sensor 1 is a line sensor, a two-dimensional image may be obtained by repeating the operation in which the conveying unit conveys the color filter substrate 3 in synchronization with imaging of one line of the line sensor. . When the same imaging region is imaged twice while changing the polarization direction of the polarization filter, the color filter substrate 3 is once returned to the imaging start position after the first imaging and the polarization direction of the polarization filter 2 or 4 is adjusted. Then, the second imaging may be performed.

  The image sensor 1 and the transmitted illumination 5 are disposed so as to face each other with the substrate 3 interposed therebetween, but each surface of the substrate 3 may be in any direction. That is, the image sensor 1 may be disposed on the glass substrate 306 side on the side where the retardation film 303 is present, and vice versa. It may be arranged on the side where the phase difference film 303 is present, or may be either.

  The color filter substrate to be inspected by the defect inspection apparatus and the defect inspection method of the present invention has a configuration in which a colored layer (layer in which each pixel of RGB is formed) is formed on the retardation film 303. Therefore, the inspection is performed after the retardation film 303 is formed and before the colored layer is formed.

  A procedure for acquiring image data will be described below. As schematically shown in FIG. 2, first, the two polarizing filters 2 and 4 are arranged in such directions that their polarization optical axis directions are parallel to each other, and an image is acquired by the image sensor 1. At this time, the linearly polarized light that passes through the polarizing filter 4 is converted into elliptically polarized light in the phase difference region 304 of the retardation film 303, and therefore cannot pass through the polarizing filter 2. Therefore, it can pass through the polarizing filter 2.

  When there is a pinhole 7 defect in the phase difference region 304 of the phase difference film 303 of the color filter substrate 3 and the foreign material 8 and the foreign material 9 in the region 305, a straight line that passes through the portion without the pinhole 7 defect in the phase difference region 304. Although the polarized light is converted into elliptically polarized light, the linearly polarized light that passes through the defective portion of the pinhole 7 passes through the linearly polarized light as it is. Further, a portion where the foreign material 8 is present is shielded by the foreign material 8. Since the region 305 is a non-phase-difference region, the linearly polarized light that passes through the portion without the foreign matter is passed as it is, but the portion with the foreign matter 9 is shielded from light.

  Therefore, in the image data obtained by receiving light with the image sensor 1, the brightness value of the normal part is different in the part with the defect and the foreign substance, the defective part of the pinhole 7 appears brighter than the surroundings, and the foreign substance 9 part appears darker than the surroundings. Will come. If such image data is binarized with an appropriate threshold value by the image processing unit 6 and processed using a comparison process of a predetermined color filter defect inspection method, pins in the retardation film as shown in FIG. The hole 7 and the foreign substance 9 on the retardation film can be visualized and detected. On the other hand, the portion of the foreign material 8 is not detected at this time because it is in a light-shielded state and indistinguishable from the surroundings in the same manner as the non-defective portion of the phase difference region 304.

  Here, it is necessary to set different threshold values for the binarization performed by the image processing unit 6 in the phase difference area 304 and the non-phase difference area 305. In addition, the comparison processing is to compare the image data and the luminance value at a normal position at a distance moved by an integral multiple of the pattern pitch in the defect inspection of a substrate with a pattern such as a color filter. It is a processing method.

  Next, as schematically shown in FIG. 3, the two polarizing filters 2 and 4 are arranged in such directions that their polarization optical axis directions are perpendicular to each other, and an image is acquired by the image sensor 1. . At this time, the linearly polarized light passing through the polarizing filter 4 is converted into elliptically polarized light in the retardation region 304 of the retardation film 303, and thus can pass through the polarizing filter 2. However, in the region 305, the linearly polarized light remains as it is. Therefore, it cannot pass through the polarizing filter 2.

  When there is a pinhole 7 defect in the retardation region 304 of the retardation film 303 of the color filter substrate 3 and the foreign material 8 and the foreign material 9 in the region 305, the linearly polarized light transmitted through the portion without the defect is also in the retardation region 304. Although it is converted into elliptically polarized light, the linearly polarized light that passes through the defect portion of the pinhole 7 passes through as linearly polarized light. Further, a portion where the foreign material 8 is present is shielded by the foreign material 8. Since the region 305 is a non-phase difference region, linearly polarized light is passed through as it is, but the place where the foreign material 9 is present is shielded from light.

  Accordingly, in the image data obtained by receiving light with the image sensor 1, the brightness value of the portion having the defect or foreign matter is different from that of the normal portion, the defective portion of the pinhole 7 appears darker than the surroundings, and the foreign matter 8 portion also appears darker than the surroundings. Will come. If such image data is binarized with an appropriate threshold value by the image processing unit 6 and processed using a comparison process of a predetermined color filter defect inspection method, pins in the retardation film as shown in FIG. Hole 7 and foreign substance 8 on the retardation film can be detected. On the other hand, the portion of the foreign matter 9 is not detected at this time because it is in a light-shielded state and cannot be distinguished from the surroundings, like the portion of the region 305 having no foreign matter.

  Thus, if the polarization optical axis directions of the two polarizing filters 2 and 4 are arranged so as to be parallel or perpendicular to each other and the image data of the color filter substrate 3 is acquired twice, the pin of the retardation film 303 is obtained. Hole 7, foreign matter 8, and foreign matter 9 can be detected.

  Alternatively, the image data may be acquired in a state where the angle formed by the polarization optical axis directions of the two polarizing filters is about 35 ° to 55 ° as shown in FIG. At this time, both the phase difference region 304 and the non-phase difference region 305 are in a semi-light-shielded state in which the transmitted light is partially blocked by the polarizing filter 2 and the remaining portion passes through the polarizing filter 2 in the normal part. . Here, the angle formed by the polarization optical axis directions of the two polarizing filters is adjusted so that the light shielding amounts in the normal portions of the phase difference region 304 and the non-phase difference region 305 are different. For example, FIG. 9 shows an example of an image when the normal part of the phase difference region 304 is adjusted to appear darker than the normal part of the non-phase difference region 305.

  At this time, since the pinhole 7 defect in the phase difference region 304 transmits more light than the surrounding normal part, it looks brighter than the surroundings, and the foreign matter 8 part is shielded, so it looks darker than the surrounding normal parts, It becomes a visualized state. On the other hand, since the foreign material 9 part in the non-phase difference region 305 is shielded from light, it appears darker than the surrounding normal part and becomes visible.

  If the image data as shown in FIG. 9 is binarized with an appropriate threshold value by the image processing unit 6 and processed using a comparison process of a predetermined color filter defect inspection method, the pinhole 7, foreign matter 8, foreign matter All 9 can be detected. This method has an advantage that an image as shown in FIG. 9 can be acquired in which two types of regions 304 and 305 having different phase differences can be simultaneously inspected.

  The same applies to the case of an image captured by adjusting the angle formed by the polarization optical axis directions of the two polarizing filters so that the normal portion of the phase difference region 304 looks brighter than the normal portion of the non-phase difference region 305. The pinhole 7, foreign matter 8, and foreign matter 9 can be detected by the process.

  As described above, in the image data acquisition procedure described with reference to FIGS. 2 and 3, the order of the arrangement of the two polarizing filters in the direction of the polarization optical axis may be either. That is, first, image data in an arrangement in which the polarization optical axis directions of the two polarizing filters are perpendicular to each other may be acquired, and later, image data in an arrangement in which the polarization optical axis directions are parallel may be acquired.

  Adjustment of the polarization optical axis direction of two polarizing filters is fixed so that one polarization filter is fixed and an in-plane rotation mechanism is attached to the other polarization filter so that the polarization optical axis directions are parallel or perpendicular to each other. To do. At this time, either polarization filter may be attached with the in-plane rotation mechanism.

  Alternatively, the polarization optical axis direction of the two polarizing filters can be adjusted by the following method. That is, one polarizing filter is fixed in the same manner as described above, but two polarizing filters having a polarizing optical axis direction parallel to that of the other polarizing filter are prepared, and imaging is performed after replacement. Is. As a mechanism for replacing the polarizing filter, a turret mechanism or the like can be used.

  Also, as shown in FIG. 5, two imaging optical systems (1, 2, 4, 5, and 1 ′, 2 ′, 4 ′, 5 ′) are prepared in advance, and the polarization optical axes of the two polarizing filters respectively. May be arranged parallel to and perpendicular to each other. That is, in FIG. 5, for example, the polarization optical axes of the polarization filters 2 and 4 may be arranged parallel to each other, and the polarization optical axes of the polarization filters 2 'and 4' may be arranged perpendicular to each other.

  In the case of an apparatus having two imaging optical systems as shown in FIG. 5, the imaging means 1 and 1 'need to acquire images of the imaging target area, respectively. However, because of the arrangement of the two imaging optical systems, it is generally not possible to image the same region at the same time. Therefore, the color filter 3 to be inspected is moved by a conveying means or the like. It is necessary to use the moving means to move, so that both the imaging optical systems can acquire the image of the imaging target area.

  As described above, also in the case of an inspection apparatus having two imaging optical systems, the image data captured by the first imaging unit 1 and the second imaging unit 1 ′ are sent to the image processing unit 6. The image processing unit 6 performs image processing on each of the sent image data to check whether there is a defect, determines whether the color filter substrate to be inspected is a non-defective product or a defective product, displays the determination result, Or send it to a device.

As described above, the inspection apparatus and the inspection method of the present invention can detect defects in the retardation film and foreign matters on the retardation film immediately after the formation of the retardation film on the color filter. It is possible to prevent the substrate from flowing into the downstream process.

1 is a schematic configuration diagram of an inspection apparatus for a color filter substrate having a retardation film, which is an embodiment of the present invention. The schematic diagram which showed the case where the polarization optical axis directions of two polarizing filters are mutually parallel. The schematic diagram which showed the case where the polarization optical axis directions of two polarizing filters were mutually perpendicular | vertical. The schematic diagram which showed the case where the polarization optical axis direction of two polarizing filters comprises 45 degrees. The schematic block diagram of the test | inspection apparatus which has two imaging optical systems in another embodiment of this invention. The structure of the color filter substrate which has a phase difference film, (a) Top view, (b) Cross section. The schematic diagram of the image after the binarization obtained when the polarization optical axis directions of two polarizing filters are parallel to each other. The schematic diagram of the image after the binarization obtained when the polarization optical axis directions of two polarizing filters are perpendicular to each other. The schematic diagram of the image obtained when the polarization optical axis direction of two polarizing filters makes a predetermined angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 '... Image sensor 2, 2' ... Image sensor side linear polarization filter 3 ... Color filter 4 which has phase difference film, 4 '... Transmission illumination side linear polarization filter 5, 5' ... Transmission illumination 6 ... Image Processing unit 7: Pinhole 8 on retardation region 304 ... Foreign matter 9 on retardation region 304 ... Foreign matter 301 on region 305 ... Black matrix 302 ... Alignment film 303 ... Retardation film 304 ... Linearly polarized light becomes elliptically polarized light Phase difference region 305 to be converted ... Non-phase difference region 306 not changing the polarization state of linearly polarized light ... Glass substrate

Claims (5)

An inspection apparatus for detecting defects in a retardation film and foreign matter on the retardation in a color filter substrate having a retardation film,
A first polarizing filter and a second polarizing filter disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other;
A transmitted illumination light source disposed outside the first polarizing filter;
Imaging means disposed outside the second polarizing filter;
Image processing means for performing predetermined image processing on the image data acquired by the imaging means and detecting defects and foreign matter ;
An inspection apparatus for a color filter substrate having a retardation film, wherein the first and second polarizing filters are arranged in a state where their polarization optical axis directions form an angle of 35 ° to 55 ° with each other . An inspection apparatus for detecting defects in a retardation film and foreign matters on the retardation film in a color filter substrate having a retardation film,
A first polarizing filter and a second polarizing filter disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other;
A first transmitted illumination light source disposed outside the first polarizing filter;
First imaging means disposed outside the second polarizing filter;
A third polarizing filter and a fourth polarizing filter disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other;
A second transmitted illumination light source disposed outside the third polarizing filter;
A second imaging means disposed outside the fourth polarizing filter;
Image processing means for performing predetermined image processing on the image data respectively acquired by the first imaging means and the second imaging means and detecting defects and foreign matters;
The first polarizing filter and the second polarizing filter are arranged so that their polarization optical axis directions are parallel to each other, and the third polarizing filter and the fourth polarizing filter are arranged so that their polarization optical axis directions are perpendicular to each other. An inspection apparatus for a color filter substrate having a retardation film. An inspection method for detecting defects in a retardation film and foreign matter on the retardation film in a color filter substrate having a retardation film,
A first polarizing filter and a second polarizing filter are disposed on both sides of the color filter substrate at positions parallel to the color filter substrate and facing each other,
Illuminating light irradiation step of irradiating the color filter substrate with illuminating light from a transmitted illumination light source disposed outside the first polarizing filter;
An imaging step of acquiring image data of the color filter substrate by an imaging means disposed outside the second polarizing filter;
An image processing stage that performs predetermined image processing on the image data acquired in the imaging stage and detects defects and foreign matter;
Have
An imaging step of acquiring image data of the color filter substrate in a state where the polarization optical axis directions of the first and second polarizing filters form an angle of 35 ° to 55 ° with each other;
An image processing stage that performs predetermined image processing on the image data acquired in the imaging stage and detects defects and foreign matter;
A method for inspecting a color filter substrate having a retardation film. An inspection method for detecting defects in a retardation film and foreign matter on the retardation film in a color filter substrate having a retardation film,
On both sides of the color filter substrate, a first polarizing filter and a second polarizing filter arranged at positions parallel to the color filter substrate and facing each other are arranged,
An illumination light irradiation step of irradiating the color filter substrate with illumination light from a first transmitted illumination light source disposed outside the first polarizing filter;
An imaging step of acquiring image data of the color filter substrate by a first imaging means disposed outside the second polarizing filter;
On both sides of the color filter substrate, a third polarizing filter and a fourth polarizing filter arranged at positions parallel to the color filter substrate and facing each other are arranged,
Illuminating light irradiation step of irradiating the color filter substrate with illuminating light from a second transmitted illumination light source arranged outside the third polarizing filter;
An imaging step of acquiring image data of the color filter substrate by a second imaging means disposed outside the fourth polarizing filter;
An image processing step of performing predetermined image processing on the image data respectively acquired by the first imaging unit and the second imaging unit and detecting defects and foreign matters;
The first polarizing filter and the second polarizing filter are arranged so that their polarization optical axis directions are parallel to each other, and the third polarizing filter and the fourth polarizing filter are arranged so that their polarization optical axis directions are perpendicular to each other. A method for inspecting a color filter substrate having a retardation film. In the image processing stage of the method for inspecting a color filter substrate having a retardation film according to claim 4 ,
For the image data of the color filter substrate obtained by using the first and second polarizing filters whose polarization optical axis directions are parallel to each other, a pinhole in the retardation region of the retardation film is used. Detect foreign objects on defects and no phase difference area,
For the image data of the color filter substrate obtained by using the third and fourth polarizing filters whose polarization optical axis directions are perpendicular to each other, a pinhole in the retardation region of the retardation film is used. A method for inspecting a color filter substrate having a retardation film, characterized by detecting defects and foreign matter on the retardation film.

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