TW201608233A - Inspection device for optical film - Google Patents

Abstract

The present invention relates to an inspection device for an optical film. The optical film inspection device of the present invention comprises: a light source, which irradiates light on one side of an optical film that is being conveyed; and a photographing device, which photographs the optical film. A light irradiation zone of the optical film that is irradiated by the light and a photographed zone of the optical film that is photographed have overlaping portions. As such, one single light source and a photographing device are still capable of observing each defect and obtains images photographed under various conditions. Thus, all sorts of defects can be easily inspected even without multiple light sources and imaging devices.

Description

Optical film inspection device

The present invention relates to an optical film inspection apparatus.

The image display device uses various optical films such as a polarizer, a TAC, and a retardation film. As image display devices have evolved, the optical films used have also required high quality.

However, when an optical film is manufactured, flaws are generated for various reasons. For example, when a foreign matter is mixed in the resin composition forming the optical film, bubbles may be generated when the film of the resin composition is cured, and when foreign matter is mixed between the layers when the multilayer structure film is formed, scratches may occur on the surface of the film. Various factors such as the warpage of the film.

Defects of various shapes are produced due to various factors that cause enthalpy as described above. For example, if a foreign matter is inserted or a bubble is generated, the optical film may have a defect of the unevenness at the place where it is generated, and when a scratch occurs, a linear defect occurs on the surface of the film.

After the optical film is manufactured, in order to remove the portion having such defects, a step of detecting defects is provided. As one of methods for detecting defects, a method of photographing an optical film surface with a photographing machine and analyzing the image is employed.

However, the imaging conditions in which defects of various shapes can be easily observed are not the same. Therefore, in order to detect defects of various shapes with high precision, various imaging conditions must be set, and thus a plurality of light sources and cameras are required, so that space and economic efficiency problems occur.

Japanese Patent Publication No. 1082699 discloses an optical film inspection device, but the system also has a problem that a plurality of light sources and cameras are required. Advanced technical literature

[Patent Document 1] Korean Registered Patent No. 1082699

Problem to be solved by the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical film inspection apparatus which can detect various defects with high precision without requiring a plurality of light sources and imaging devices.

It is an object of the present invention to provide an optical film inspection method. Technical means of solving problems

An optical film inspection apparatus comprising: a light source that emits light from one side of a film to be transferred; and an image pickup device that images the film; a light irradiation region of the film that is irradiated with light; and the film that is imaged A part of the imaging area overlaps.

2. The optical film inspection apparatus according to item 1, wherein the light source and the image pickup device are spaced apart from each other in a transfer direction of the film.

3. The optical film inspection apparatus according to item 1, wherein the light irradiation direction of the light source is parallel to the imaging direction of the imaging device.

4. The optical film inspection apparatus according to item 1, wherein the light irradiation direction of the light source is not parallel to the imaging direction of the image pickup apparatus.

5. The optical film inspection apparatus according to Item 1, further comprising: a periodic signal generating unit that divides the sub-imaging regions having two or different illumination ranges corresponding to the transfer direction of the film, and emits an imaging period signal to Obtaining an image of the entire film in each of the sub-imaging regions; and a control unit receiving an imaging period signal from the periodic signal generating unit, and transmitting an imaging signal to the imaging device for each imaging period, receiving from the foregoing The captured image of the imaging device detects defects.

6. The optical film inspection apparatus according to item 5, wherein the sub-imaging regions have mutually the same width, and the periodic signal generating unit emits an imaging period signal every time the film is transferred to the width of the sub-imaging region.

7. The optical film inspection apparatus according to Item 5, wherein the control unit combines the captured images received from the respective sub-imaging regions with each sub-imaging region, thereby obtaining a whole film map for each sub-imaging region. Like, detect defects based on this.

8. The optical film inspection apparatus according to item 1, wherein the light irradiation region includes an effective region of the optical film, and the light source is a light source that emits light in the effective region and has the same illuminance in the width direction of the film.

9. The optical film inspection apparatus according to item 5 above, wherein the aforementioned defect is a foreign matter defect, a concave-convex defect, or a scratch defect.

10. The optical film inspection apparatus according to the above item 9, wherein the difference in illuminance between the foreign matter defect and the peripheral normal region is 10 or more in the grayscale value, and the horizontal and vertical lengths are respectively black defects of 30 μm or more; In the region where the illuminance difference between the normal area and the surrounding normal area is 10 or more, the horizontal and vertical lengths are respectively black and white defects of 30 mm or more; the difference between the scratch defect and the surrounding normal area is 10 or more. A defect having a width of 30 mm or more and a length of 3 times or more.

11. An optical film inspection method for irradiating light from one side of a film to be transferred, photographing the film, and detecting a defect of the optical film; and irradiating the light irradiation region of the film irradiated with light and the film of the film being photographed Part of the area overlaps.

12. The optical film inspection method according to item 11, wherein the light source and the image pickup device are disposed to be spaced apart from each other in a direction in which the film is transferred.

13. The optical film inspection method according to item 11, wherein the light irradiation direction of the light source and the imaging direction of the image pickup device are arranged in parallel.

14. The optical film inspection method according to item 11, wherein the light irradiation direction of the light source and the imaging direction of the image pickup device are arranged to be non-parallel.

15. The optical film inspection method according to item 11, wherein the image capturing area is divided into two or more sub-image areas having different illuminance ranges in response to a film transfer direction, and each time the film is transferred to the width of the sub-image area, The film was taken, and an image of the entire film was taken in each sub-image area.

16. The optical film inspection method according to item 11, wherein the image of the image received from each of the sub-image areas is combined for each sub-image area, thereby obtaining an image of the entire film for each sub-image area. Effect of invention

According to the optical film inspection apparatus of the present invention, even if only one light source and an imaging device are used, it is easy to observe each defect and an image captured under various imaging conditions can be obtained. Therefore, even without a plurality of light sources and imaging devices, various types of light can be easily detected. defect.

Form for implementing the invention

The present invention relates to an optical film inspection apparatus comprising: a light source that emits light from one side of a film to be transferred; and an image pickup device that images the film; a light irradiation area of the film irradiated by light and a photographing A part of the imaging region of the film overlaps; thereby, it is possible to easily observe each defect with only one light source and an imaging device, and to obtain an image captured under various imaging conditions, so that even without a plurality of light sources and imaging devices, Various defects can still be easily detected.

The invention is described in detail below.

The optical film inspection apparatus of the present invention is provided with a light source and an image pickup apparatus. An optical film inspection apparatus according to a specific example of the present invention is schematically shown in Fig. 1.

The optical film 10 to be inspected is a film which can be inspected if it is an optical system, and the kind thereof is not particularly limited. More specific examples of the optical film 10 include a polarizer, a transparent protective film, and a polarizing plate or a retardation film having a protective film adhered to at least one surface of the polarizing plate, but are not limited thereto.

The optical film 10 is generally provided by a roll-to-roll method. However, since the roll-shaped film is likely to be damaged by stretching at the end portion of the roll due to storage, transportation, handling, and the like, the entire length in the width direction is not used as a product. Cut off a part of the end in the width direction and use the remaining part.

The aforementioned remaining portion used may be referred to as an effective area of the optical film 10. The length of the end portion to be cut is not particularly limited, and may be appropriately selected depending on the desired product properties, the processing state of the product, and the like.

In the present invention, the optical film 10 may be subjected to light irradiation and imaging, and may be performed on the entire area or the effective area of the optical film 10, or the light irradiation area and the imaging area may include an effective area.

The light source 100 is irradiated with light on the film 10 from the side of the film 10 to be transferred, specifically, from the side of the surface of the film 10.

If the film 10 is irradiated with light, the light irradiation angle is not particularly limited. Hereinafter, the case where the film is vertically irradiated with light will be described by way of a specific example, but the present invention is not limited thereto.

According to an embodiment of the present invention, the light source 100 may be in the light irradiation region 110 of the film 10, and illuminate the light source 100 in such a manner as to have the same illuminance in the width direction of the film 10. As described above, the light irradiation region 110 may include an effective region of the film. Specifically, the light may be irradiated only in the effective region of the film 10 in the light irradiation region 110 so as to have the same irradiation in the width direction, but is not limited thereto. this.

The same illuminance of the present invention includes not only the same illuminance but also substantially the same illuminance. In essence, the same illuminance refers to the extent to which the inspection device cannot recognize the difference. In other words, the illuminance deviation can be exemplified by ±10%, ±5%, ±1%, ±0.1%, ±0.01%, ±0.0001%, ±0.00001%. However, the present invention is not limited to such a case. Therefore, the long side or the short side of the light source 100 has a length equal to or greater than the film width, or in the case of the square light source 100, one side or more may have a length equal to or larger than the film width. In this case, since the illuminance difference in the film width direction does not occur, it is easy to distinguish from the sub-imaging region to be described later.

The image pickup apparatus 200 photographs the surface of the film 10 on the same side as the light source 100 or photographs a film from the other side of the film 10.

Similarly, the imaging device 200 can also be an image-capable film 10, and the imaging angle is not particularly limited. The vertical imaging film 10 will be described below by way of a specific example, but is not limited thereto.

In the present invention, a portion of the light irradiation region of the film 10 irradiated with light and a portion of the image capturing region of the film to be imaged are overlapped.

The method of realizing the overlapping of the regions is not particularly limited. For example, the light source 100 and the imaging device 200 may be disposed so as to be separated from each other in the transfer direction of the film 10.

1 is a view schematically showing an optical film inspection apparatus of the present invention in the specific example, and FIG. 2 is a top view of the light source 100 and the image pickup apparatus 200 of the optical film inspection apparatus, as shown in FIGS. 1 and 2; The light source 100 and the imaging device 200 are separated from each other in the transfer direction of the film, and the light irradiation region 110 of the film irradiated by the light and a part of the imaging region 210 of the film to be imaged are overlapped.

Moreover, as shown in FIGS. 3 and 4, it can also be realized by adjusting the light irradiation angle and the imaging angle. Therefore, the light source 100 and the imaging device 200 may be arranged such that the light irradiation direction and the imaging direction are not parallel. 3 is a view showing the specific example. Therefore, the light irradiation direction and the imaging direction may not be parallel, and one of the light irradiation region 110 and the imaging region 210 may partially overlap.

Needless to say, by adjusting the light irradiation angle and the imaging angle, as shown in FIG. 4, in a state where the light irradiation direction is parallel to the imaging direction, the light irradiation region and a part of the imaging region of the film to be photographed are overlapped. .

In this manner, the light irradiation region of the film 10 irradiated with light and a portion of the image capturing region of the film to be imaged overlap, and the image capturing region 210 of the film 10 to be imaged is caused to have a difference in illuminance in response to the film transfer direction.

Therefore, in the optical film inspection apparatus of the present invention, the image capturing area 210 is divided into two or more sub-image capturing areas 210a, 210b, and 210c having different illuminances in accordance with the film transfer direction, and each of the sub-image capturing areas 210a, 210b, and 210c is respectively An image of the entire film 10 is obtained, and defects are detected based on this.

The defects to be detected in the present invention can be roughly classified into foreign matter defects, uneven defects, and scratch defects.

The foreign matter defect, as shown in Fig. 5(a), means a defect appearing in a black dot shape, and the length in the horizontal direction and the longitudinal direction may be 30 mm or more in a region where the difference in illumination from the peripheral normal region is 10 or more. Black spotted defects are classified as foreign body defects.

As shown in Fig. 6(b), the concave and convex defects mean that the defects appearing together with black and white can be 30 mm or more in the horizontal and vertical directions in the region where the difference in illumination from the normal area in the periphery is 10 or more. Black and white defects, classified as bump defects.

As shown in Fig. 7(c), the scratch defect means a thin line-shaped defect, and the difference from the illuminance in the normal area of the periphery is 10 or more in the gray scale value, and the width is 30 mm or more and the length is 3 times or more. Defects are classified as scratch defects.

The observation conditions for these defects that can be easily observed are different. In the fifth to seventh figures, (a), (b), and (c) are photographs taken in different sub-imaging regions. (a) is in the first sub-image area (Bright field), (b) is in the second sub-image area (Gray field), and (c) is in the third sub-image area (dark) Photograph taken in the (Dark field) area.

Specifically, the foreign matter defect in FIG. 5 is easily observed in the first sub-imaging region (Bright field), and can also be observed in the second sub-imaging region (Gray field), but it is difficult to The third sub-image area (Dark field) is observed. Then, the concave-convex defect of FIG. 6 is easily observed in the second sub-image area (Gray field), and is difficult to be in the first sub-image area (Bright field) and the third sub-image area (dark area). (Dark field)) Observed. Moreover, the scratch defect of FIG. 7 is easily observed in the third sub-image area (Dark field), and is difficult to be in the first sub-image area (Bright field) and the second sub-image area (Gray (Gray field) observed.

That is, in order to detect all of these defects with high precision, it is necessary to set imaging conditions suitable for each defect, and thus a plurality of imaging devices and light sources are required.

However, since the optical film inspection apparatus of the present invention obtains an image of the entire film in each of the sub-imaging regions 210a, 210b, and 210c, and detects defects based thereon, only one light source 100 and the image pickup device 200 can still be used. High-precision detection of various types of defects.

FIG. 8 illustrates a case where the imaging region 210 is divided into three sub-imaging regions 210a, 210b, and 210c having different illuminances in response to the transfer direction of the film, so that the imaging region 210 can be distinguished to have different illuminances (grayscale values). Sub-image areas 210a, 210b, and 210c having a range of 2 or more.

The illuminance for distinguishing the sub-imaging regions 210a, 210b, and 210c is not particularly limited, and may be in accordance with the desired product performance, inspection level, illuminance of the light source 100, distance between the light source 100 and the film 10, the light source 100, and the image pickup device 200. Various adjustments are made, such as the degree of separation, the distance between the imaging device 200 and the film 10, and the like.

The sub-imaging area can also be divided according to the degree to which the light irradiation area of the film and the imaging area of the film overlap.

Specifically, the light irradiation region of the film may be divided into a main irradiation region that displays the illuminance desired by the light source 100, and a sub-illumination region that is not the illuminance.

When the imaging region 210 is divided into two sub-imaging regions, the imaging region 210 can be divided into a portion overlapping the main irradiation region and a portion overlapping the sub-illumination region.

Then, when the imaging region 210 is divided into three sub-imaging regions, the portion overlapping the main irradiation region in the imaging region 210 is regarded as the first sub-imaging region (Bright field; 210a), and the sub-illumination region is used. Divided into two regions, and a portion where the scattered light and the diffused light arrive at the imaging region 210, that is, a portion overlapping the first sub-illumination region is divided into a second sub-imaging region (Gray field; 210b) The portion where less scattered light and diffused light arrive, that is, the portion overlapping the second sub-illumination region, is divided into a third sub-imaging region (Dark field; 210c).

For example, the first sub-imaging region (Bright field; 210a) has a gray level value of 90 or more and 150 gray scale values or less, and the second sub-image capturing area (Gray field; 210b) has 30 gray levels. The value is greater than or equal to 90 grayscale values, and the third sub-image capturing area (dark field) may be an area having an illuminance of less than 30 grayscale values, but is not limited thereto.

The optical film inspection apparatus of the present invention acquires an image of the entire film for each of the sub-imaging regions 210a, 210b, and 210c, and further includes a periodic signal generating unit 300 and a control unit 400 based on the detection of the defect.

The periodic signal generating unit 300 issues an imaging period signal so that each of the sub-imaging regions 210a, 210b, and 210c acquires an image of the entire film.

Specifically, each of the sub-imaging regions 210a, 210b, and 210c has the same width, and the periodic signal generating unit 300 emits an imaging period signal every time the film is transferred to the width of the sub-imaging regions 210a, 210b, and 210c. . Then, the control unit 400 receives the imaging cycle signal from the periodic signal generation unit 300, and transmits an imaging signal to the transmission device 200 for each imaging cycle.

The widths of the sub-imaging regions 210a, 210b, and 210c are associated with the imaging period, and may be appropriately selected within the imaging region.

When the film is photographed every time the film is transferred to the width of the sub-imaging regions 210a, 210b, and 210c, the entire film is transferred to each of the sub-imaging regions 210a, 210b, and 210c.

Then, the control unit 400 combines the captured images received from the respective sub-imaging regions 210a, 210b, and 210c with the sub-imaging regions 210a, 210b, and 210c, thereby obtaining the entire film for each of the sub-imaging regions 210a, 210b, and 210c. Image, based on this detection defect.

The method of obtaining the entire image of the film is schematically shown in Fig. 9. As shown in Fig. 9, the imaging region 210 is divided into three sub-imaging regions 210a, 210b, and 210c, and the film 10 is transferred to the sub-imaging regions 210a and 210b. When the film width is 210c, the film is captured. If the entire image is captured, the image of all the transferred film in the first sub-image area 210a, the second sub-image area 210b, and the third sub-image area 210c can be obtained. .

Then, if only the images captured in the first sub-imaging region 210a are connected, as shown in FIG. 9(a), an image of the entire film can be obtained in the first sub-imaging region 210a, and the same will be obtained. The images captured by the two sub-imaging regions 210b are connected, and an image of the entire film is captured in the second sub-imaging region 210b (Fig. 9(b)), and images captured in the third sub-imaging region 210c are connected. As a result, an image of the entire film can be obtained in the third sub-image capturing area 210c (Fig. 9(c)).

As described above, when the entire film image is obtained for each of the sub-imaging regions 210a, 210b, and 210c, there are specific defects that are easily observed for each image, and thus various types of defects can be easily detected.

Further, the present invention provides an optical film inspection method.

The optical film inspection method of the present invention is a method of irradiating light from one side of a film to be transferred, photographing the film, and detecting a defect of the optical film; and causing a light irradiation region of the film irradiated with light and an imaging region of the film to be photographed. Some overlap.

The method of overlapping the aforementioned regions is not particularly limited. For example, the light source 100 and the imaging device 200 are disposed to be separated from each other in the transfer direction of the film 10, or the light irradiation angle and the imaging angle may be adjusted. Therefore, the light source 100 and the imaging device 200 may be arranged such that the light irradiation direction and the imaging direction are not parallel. Needless to say, by adjusting the light irradiation angle and the imaging angle, a part of the light irradiation region and the image capturing region of the film to be imaged may be overlapped in a state where the light irradiation direction is parallel to the image capturing direction.

As described above, by overlapping the light irradiation region of the film 10 and a part of the image capturing region of the film 10 to be imaged, an illuminance difference occurs in the image capturing region 210 of the film to be filmed in response to the film transfer direction.

Therefore, in the optical film inspection apparatus of the present invention, the image pickup area is divided into sub-image areas having two or more different illuminance ranges in accordance with the transfer direction of the film, and an image of the entire film is obtained for each sub-image area. defect.

Whenever the film is transferred to the width of the sub-imaging region, the film is captured, and an image of the entire film can be obtained for each sub-imaging region.

Then, the captured images received from the respective sub-imaging regions are combined for each sub-imaging region, thereby obtaining an entire film image for each sub-imaging region.

As described above, when the entire film image is obtained for each sub-imaging region, there are specific defects that are easily observed for each image, and thus various types of defects can be easily detected.

In the following, the preferred embodiments are described in order to facilitate the understanding of the present invention. However, the embodiments are merely illustrative of the present invention and are not intended to limit the scope of the appended claims. In the scope of the technical idea, changes to the embodiments may be varied and may be modified, and such changes and modifications are of course also within the scope of the appended claims. Example

Using a Testo 545 LuxMeter, the light source measured at a distance of 1 mm from the illumination surface was a light source of 200,000 lux, and the light was irradiated perpendicularly to the film from a distance of 1 cm from the transferred polarizing film. In the light irradiation region of the film, the difference in illuminance in the film width direction was not measured.

Then, on the other side of the optical film, the film was vertically photographed with an Area scan camera (Balser ac A2000-340 km) from a distance of 12 cm. The distance between the light source and the camera is 13 cm.

In accordance with the direction in which the film is transferred, the camera's imaging area is divided into a bright field, a gray field, and a dark field based on the illuminance. At that time, the image illumination intensity of each region is below 90 grayscale value to below 150 grayscale value, the gray zone is above 30 grayscale value to less than 90 grayscale value, and the dark zone is 0 grayscale value or more to less than 30 gray. Order value.

Thereafter, the film is imaged every time the film is transferred to the width of the sub-image area, and in FIG. 5, the picture taken in the bright area, the gray area, and the dark area is observed for the same foreign object defect observed. The unevenness defect is also shown in Fig. 6, and the scratch defect is also shown in Fig. 7.

Referring to Fig. 5 to Fig. 7, it can be confirmed that the foreign matter defect is easily observed in the bright region, the unevenness defect is easily observed in the gray region, and the scratch defect is easily observed in the dark region.

In the past, in order to detect all of these defects separately, three light sources and cameras were required, that is, three optical systems were provided. However, the present invention can detect all of these defects in one system.

10‧‧‧Optical film
100‧‧‧Light source
110‧‧‧Lighting area
200‧‧‧ camera
210‧‧‧Photography area
210a, 210b, 210c‧‧‧ sub-camera area
300‧‧‧cycle signal generation department
400‧‧‧Control Department

Fig. 1 is a view schematically showing an optical film inspection apparatus according to a specific example of the present invention. Fig. 2 is a top view of a light source and an image pickup apparatus of an optical film inspection apparatus according to a specific example of the present invention. Fig. 3 is a specific example of adjusting the light irradiation angle of the light source and the imaging angle of the imaging device. Fig. 4 is a specific example of adjusting the light irradiation angle of the light source and the imaging angle of the imaging device. Fig. 5 is a view showing an optical film inspection apparatus according to a specific example of the present invention, in different imaging areas (bright field (a), gray field (b), dark field (dark area). (c)) Take an image of the same defect. Figure 6 is an optical film inspection apparatus according to a specific example of the present invention, in different imaging areas (bright field (a), gray field (b), dark field (dark area) (c)) Take an image of the same defect. Figure 7 is an optical film inspection apparatus according to a specific example of the present invention, in different imaging areas (bright field (a), gray field (b), dark field (dark area) (c)) Take an image of the same defect. Fig. 8 is a view showing a case where the imaging region is divided into three sub-imaging regions having different illuminances in response to the transfer direction of the film. Fig. 9 is a view schematically showing a method of acquiring an entire image of an image from an image acquired in an individual sub-imaging region.

10‧‧‧Optical film

100‧‧‧Light source

110‧‧‧Lighting area

200‧‧‧ camera

210‧‧‧Photography area

300‧‧‧cycle signal generation department

400‧‧‧Control Department

Claims (16)

An optical film inspection apparatus comprising: a light source that emits light from one side of a film to be transferred; and an image pickup device that images the film; a light irradiation region of the film irradiated with light and an image capturing region of the film that is photographed Part of the overlap. The optical film inspection apparatus according to claim 1, wherein the light source and the image pickup device are spaced apart from each other in a transfer direction of the film. The optical film inspection apparatus according to claim 1, wherein the light irradiation direction of the light source is parallel to the imaging direction of the image pickup device. The optical film inspection apparatus according to claim 1, wherein the light irradiation direction of the light source is not parallel to the imaging direction of the imaging device. The optical film inspection apparatus according to claim 1, further comprising: a periodic signal generating unit that divides the sub-imaging regions having two or more different illuminance ranges in response to the transfer direction of the film, and emits an imaging period signal, Obtaining an image of the entire film for each of the sub-imaging regions; and a control unit receiving an imaging period signal from the periodic signal generating unit, and transmitting an imaging signal to the imaging device for each imaging period, receiving from the foregoing The captured image of the imaging device detects defects. The optical film inspection apparatus of claim 5, wherein the sub-imaging regions have mutually the same width, and the periodic signal generating unit emits an imaging period signal every time the film is transferred to the width of the sub-imaging region. The optical film inspection apparatus according to claim 5, wherein the control unit combines the captured images received from the respective sub-imaging regions with each sub-imaging region, thereby obtaining the entire film for each sub-imaging region. Image, based on this detection defect. The optical film inspection apparatus according to claim 1, wherein the light irradiation region includes an effective region of the optical film, and the light source is a light source that emits light in the effective region and has the same illuminance in the width direction of the film. The optical film inspection apparatus of claim 5, wherein the defect is a foreign matter defect, a concave-convex defect, or a scratch defect. The optical film inspection apparatus according to claim 9, wherein in the region where the difference between the foreign matter defect and the peripheral normal region is 10 gray scale or more, the lateral and longitudinal lengths are respectively black defects of 30 mm or more; In the region where the illuminance difference between the normal area and the surrounding normal area is 10 or more, the horizontal and vertical lengths are respectively black and white defects of 30 mm or more; the illuminance difference between the scratch defect and the surrounding normal area is 10 or more. Among them, the width is 30 mm or more and the length is 3 times or more. An optical film inspection method for irradiating light from one side of a film to be transferred, photographing the film, and detecting a defect of the optical film; and causing a light irradiation region of the film irradiated with light and an imaging region of the film to be photographed Some overlap. The optical film inspection method according to claim 11, wherein the light source and the image pickup device are disposed to be spaced apart from each other in a direction in which the film is transferred. The optical film inspection method according to claim 11, wherein the light irradiation direction of the light source and the imaging direction of the image pickup device are arranged in parallel. The optical film inspection method according to claim 11, wherein the light irradiation direction of the light source and the imaging direction of the image pickup device are arranged non-parallel. The optical film inspection method according to claim 11, wherein the image capturing area is divided into two or more sub-image areas having different illuminance ranges in response to a film transfer direction, and each time the film is transferred to the width of the sub-image area The film is taken, and an image of the entire film is obtained in each sub-image area. The optical film inspection method according to claim 11, wherein the image received from each sub-image area is combined with each sub-image area, thereby obtaining an image of the entire film for each sub-image area.