JP2004144565A - Apparatus and method for detecting defects in hologram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect defects on a surface of a hologram. <P>SOLUTION: The apparatus for detecting the defect, which detects the defect on the surface of a thin plate-like hologram 10 to be tested, is provided with a planar light source 11 by which the substantive surface side except the overhead section on the surface of the hologram 10 is irradiated with test light in all directions in relation to the surface of the hologram 10 to be tested, a camera 12 which photographs the surface of the hologram 10 irradiated with the test light as an image viewed directly overhead and obtains image data, and an image data comparing section 32 which judges as to whether the defect is present or not on the surface of the hologram 10 to be tested, on the basis of the image data obtained by the camera 12 and image data of a defect-free hologram having a specification identical to the hologram 10 to be tested and being previously photographed to obtain its image data. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a defect detection device and a defect detection method for detecting a defect on the surface of a hologram.
[0002]
[Prior art]
Normally, a transfer type hologram is obtained by transferring a diffraction grating pattern to a resin surface by pressing a stamper having a relief-shaped diffraction grating recorded on a plane, for example, against a resin surface, and then depositing a metal on the surface to form a reflection layer. It is manufactured by being. Of course, various materials other than resin may be used.
[0003]
Since the hologram thus formed can display images of various patterns depending on the angle of incidence of light, the hologram can be applied to an IC card or a credit card to prevent forgery or security management. Has been done.
[0004]
[Problems to be solved by the invention]
Since the hologram is applied to forgery prevention, security management, and the like, it is required to reliably produce the hologram.
[0005]
However, as described above, holograms are formed on the order of microns and are precisely formed by very complicated patterns of diffraction gratings. Therefore, their production is not easy, and it is necessary to pay sufficient attention even in the production stage. is there.
[0006]
For example, when a hologram is manufactured in a state where foreign matter such as dust adheres to the stamper and the foreign matter is still attached, every time the stamper is pressed, the unevenness of the diffraction grating is crushed, and a correct diffraction grating pattern is obtained on the surface. Can not be.
[0007]
Normally, a hologram sees diffracted light, and thus the appearance of an image changes depending on the viewpoint. For this reason, it is not possible to view all images at once under direct reflected light or under illumination conditions using one or more light sources. Further, the visible image changes due to a slight difference in light irradiation conditions. Therefore, the image to be inspected is not stable, and the inspection result cannot maintain reliability.
[0008]
For this reason, as described above, even if a correct diffraction grating is not formed on the surface and a defective hologram is manufactured, it is difficult to detect the defect, and a large number of defective holograms are continuously manufactured. There is a problem that may be continued.
[0009]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a hologram defect detection device and a defect detection method capable of accurately detecting a defect on the surface of a hologram.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention takes the following measures.
[0011]
That is, the invention according to claim 1 is an apparatus for detecting a defect on the surface of a thin hologram, which is an object, and substantially removes the surface of the hologram, which is the object, except for a portion immediately above the surface of the hologram. A light source for inspection light that irradiates inspection light from all directions on the front side, an imaging unit that captures an image of the surface of the hologram illuminated by the inspection light as viewed from directly above, and obtains image data. Based on the acquired image data and the image data of the hologram of the subject which has been previously imaged and acquired with the same specifications as the hologram of the subject, it is determined whether or not the surface of the hologram of the subject has a defect. Determining means for performing the determination.
[0012]
Therefore, in the hologram defect detection apparatus according to the first aspect of the present invention, if the diffraction grating is not correctly formed on the surface of the hologram, the inspection light will not be diffracted immediately above by taking the above measures. In the image data viewed from directly above, a black dot is captured.
[0013]
Therefore, when this black dot is observed, it is possible to detect a defect on the surface of the hologram with high accuracy by determining that the surface of the hologram has a defect.
[0014]
According to a second aspect of the present invention, in the hologram defect detection apparatus according to the first aspect of the present invention, the light source for inspection light is cylindrical, and the hologram as an object and the imaging means are arranged in the cylinder.
[0015]
Therefore, in the hologram defect detection apparatus according to the second aspect of the present invention, by taking the above-described means, the inspection light is applied to the subject from substantially all directions on the surface side except for the portion immediately above the surface of the hologram. Irradiation can be performed toward the surface of the hologram, and the imaging means can be arranged immediately above the surface of the hologram.
[0016]
As a result, the hologram defect detection device according to the first aspect of the present invention can be made compact.
[0017]
The invention according to claim 3 is an apparatus for detecting a defect on the surface of a hologram while winding a thin hologram wound in a roll shape as an object, wherein the winding direction in which the hologram as the object is wound. And a slit that is grooved along a direction perpendicular to the surface of the hologram, and a substantially omnidirectional surface, except for a portion immediately above the slit, with respect to the surface of the hologram that is the subject. From, a light source for inspection light that irradiates inspection light through a slit, and an inspection area that is the surface of the hologram illuminated by the inspection light, sequentially image the image viewed from directly above through the slit, and Imaging means for arranging a single piece of image data; image data obtained by the imaging means; and a hologram having the same specifications as the hologram of the subject previously imaged and obtained, and having no defect. Determining means for determining whether or not there is a defect in the inspection area based on the image data; and winding up the hologram as the subject so that the determining means can sequentially execute after the determination by the determining means. Means.
[0018]
Therefore, in the hologram defect detection device according to the third aspect of the present invention, by taking the above-described means, the surface defect is continuously detected while producing a thin hologram wound in a roll shape. be able to.
[0019]
According to a fourth aspect of the present invention, in the hologram defect detection apparatus according to the third aspect of the present invention, the inspection light source has a cylindrical shape, and the inspection area and the imaging unit are arranged in the cylinder.
[0020]
Therefore, in the hologram defect detecting device according to the fourth aspect of the present invention, by taking the above-described means, the inspection light is directed to the inspection area from substantially all directions on the surface side except the portion immediately above the surface of the hologram. And the imaging means can be arranged directly above the surface of the hologram. As a result, the hologram defect detection device according to the third aspect of the present invention can be made compact.
[0021]
According to a fifth aspect of the present invention, in the hologram defect detection apparatus according to the first or third aspect, the inspection light source has a flat plate shape, and the imaging unit is disposed immediately above.
[0022]
Therefore, in the hologram defect detection apparatus according to the fifth aspect of the present invention, by taking the above-described means, the inspection light is directed to the inspection area from substantially all directions on the surface side except the portion immediately above the surface of the hologram. And the imaging means can be arranged directly above the surface of the hologram. As a result, it is possible to accurately detect a defect on the surface of the hologram.
[0023]
According to a sixth aspect of the present invention, there is provided the hologram defect detection apparatus according to any one of the first to fifth aspects, wherein the imaging means is disposed immediately above and provided between the imaging means and the hologram as the subject. Then, a telecentric lens for forming an image of the surface of the hologram illuminated by the inspection light as viewed from directly above the hologram by an imaging unit is added.
[0024]
The telecentric lens captures only the diffracted light from the hologram illuminated by the inspection light. Therefore, in the hologram defect detecting device according to the sixth aspect of the present invention, by taking the above measures, if the diffraction grating is not correctly formed on the surface of the hologram, the image data in the image data viewed from directly above is not obtained. A black point can be clearly imaged. As a result, it is possible to accurately detect a defect on the surface of the hologram.
[0025]
According to a seventh aspect of the present invention, in the hologram defect detection apparatus according to any one of the first to sixth aspects, the determining unit includes image data based on an image captured by the imaging unit, and image data previously captured and acquired. Comparing means for comparing the image data of a hologram having the same specifications as that of the hologram which is the subject and having no defect, and if there is a difference between the two image data as a result of the comparison by the comparing means, the defect exists. If there is no difference between the two image data, there is provided a defect determining means for determining that there is no defect.
[0026]
Therefore, in the hologram defect detection apparatus according to the seventh aspect of the present invention, by taking the above-described measures, the image data captured from immediately above the hologram as the subject is compared with the image data of the defect-free hologram. By doing so, it becomes possible to accurately detect defects on the surface of the hologram.
[0027]
The invention according to claim 8 is a method for detecting a defect on the surface of a thin hologram as an object, which is obtained by previously capturing image data of a defect-free hologram with the same specifications as the hologram as the object. In addition, the surface of the hologram, which is the subject, is irradiated with the inspection light from all directions substantially on the surface side except for the portion directly above the surface of the hologram, and the surface of the hologram irradiated by the inspection light is directly above the surface Image data obtained by capturing an image viewed from the hologram. Based on the obtained image data and the previously obtained image data of the defect-free hologram, a defect is detected on the surface of the hologram as the subject. It is determined whether or not there is.
[0028]
Accordingly, in the hologram defect detection method according to the eighth aspect of the present invention, by taking the above measures, if the diffraction grating is not correctly formed on the surface of the hologram, the inspection light will not be diffracted immediately above. In the image data viewed from directly above, a black dot is captured.
[0029]
Therefore, when this black dot is observed, it is possible to detect a defect on the surface of the hologram with high accuracy by determining that the surface of the hologram has a defect.
[0030]
A ninth aspect of the present invention is a method for detecting a defect on the surface of a hologram while winding a thin hologram wound in a roll shape as an object. Image data of the hologram of the defect is captured and acquired, and a slit that is grooved along a direction perpendicular to the winding direction in which the hologram to be inspected is wound is arranged close to the surface of the hologram. Then, on the surface of the hologram, which is the subject, the inspection light is irradiated through the slit from substantially all directions of the surface side except immediately above the slit, and the surface of the hologram irradiated by the inspection light. The inspection area is sequentially imaged as viewed from directly above through a slit, and the images are arranged into one piece of image data. This image data is combined with a previously obtained defect-free hologram. Determining whether there is a defect in the inspection area based on the image data and winding the hologram as the subject so that the next inspection area is irradiated with the inspection light after the determination is made. Is repeated to detect a defect on the surface of the thin hologram wound in a roll shape.
[0031]
Therefore, in the hologram defect detection method according to the ninth aspect of the present invention, by taking the above-described means, the surface defect is continuously detected while producing a thin hologram wound in a roll shape. be able to.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0033]
(First Embodiment)
A first embodiment of the present invention will be described with reference to FIGS.
[0034]
FIG. 1 is a functional configuration diagram illustrating an example of a hologram defect detection apparatus to which the hologram defect detection method according to the first embodiment is applied.
[0035]
That is, the hologram defect detection device to which the hologram defect detection method according to the present embodiment is applied is a device that detects a defect on the surface of a thin plate-shaped hologram 10 as an object, and includes a planar light source 11 and a camera 12. , An image capturing unit 14 and an image processing device 16.
[0036]
As shown in FIG. 1, the flat light source 11 irradiates inspection light h made of, for example, white light. A diffuser 18 which is a diffusion plate for diffusing the inspection light h is arranged on the side to which the inspection light h is irradiated. Further, as shown in the elevation view of FIG. 1 and the plan view of FIG. 2, the flat light source 11 is provided with an imaging hole 20 at the center. The imaging hole 20 is arranged immediately above the inspection position 19 provided on the inspection table 17. With this configuration, when the hologram 10 to be inspected is placed at the inspection position 19 with the surface to be inspected facing upward, the surface of the hologram 10 except for the portion directly above the hologram 10 is substantially removed. The inspection light h can be radiated from all directions on the front surface side.
[0037]
In addition, the camera 12 is arranged in the imaging hole 20 so that an image of the surface of the hologram 10 illuminated by the inspection light h can be taken from directly above. As the imaging lens 22 of the camera 12, a telecentric lens is preferably used.
[0038]
As shown in FIG. 3A, the telecentric lens is configured by a set of two lenses and a pinhole p, and the surface of the hologram 10 irradiated by the inspection light h is viewed from directly above. It is suitable for capturing an image. That is, as shown in FIG. 3A, the telecentric lens 22 (#a) forms an image using only the light that travels straight, and therefore, as shown by the symbol a in FIG. Light coming from does not form an image. Therefore, when the cylindrical body 24 is viewed from directly above, as shown in FIG. 3B, an image consisting of only the trunk 25 and the hollow part 26 is obtained.
[0039]
On the other hand, a general photographing lens 22 (#b), which is not a telecentric lens, is configured as a set of two lenses as shown in FIG. 4A, and a symbol b in FIG. As shown in (2), light entering obliquely also forms an image. Therefore, even when the cylindrical body 24 is viewed from directly above, as shown in FIG. 4B, an image is formed such that the inner side surface 27 exists between the body 25 and the hollow portion 26. .
[0040]
As described above, by using the telecentric lens 22 (#a) as the imaging lens 22, the camera 12 captures an accurate image when viewed from directly above the hologram 10 that is the subject.
[0041]
The image capturing unit 14 acquires an image captured by the camera 12, digitizes the image, and outputs digitized image data to the image processing device 16.
[0042]
The image processing device 16 includes an inspection image data storage unit 28, a reference image data storage unit 30, an image data comparison unit 32, and a defect determination unit 34.
[0043]
The inspection image data storage unit 28 stores the image data output from the image capture unit 14 and, when requested by the image data comparison unit 32, stores the stored image data in the image data comparison unit 32. Output to
[0044]
In order to determine whether or not the surface of the hologram 10 as a subject has a defect, the hologram of the subject has the same specifications as the hologram of the subject, and is compared with image data obtained by imaging a hologram having no defect from directly above. Do it by doing. Therefore, image data of the same specification as the hologram of the subject and viewed from directly above the hologram having no defect is imaged in advance and stored in the reference image data storage unit 30.
[0045]
The image data comparison unit 32 compares the image data stored in the inspection image data storage unit 28 with the image data stored in the reference image data storage unit 30. As a comparison method, there is a method of calculating a difference or a ratio of gray values at the same coordinates, but in the present invention, any method may be used as long as it can substantially compare both image data.
[0046]
If there is a difference between the two image data as a result of the comparison by the image data comparison unit 32, the defect determination unit 34 determines that the surface of the hologram 10, which is the subject, has a defect. On the other hand, if there is no difference between the two image data, it is determined that the hologram 10 as the subject has no defect on the surface.
[0047]
Next, the operation of the hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment configured as described above is applied will be described.
[0048]
That is, in order to determine the presence / absence of a defect on the surface of the hologram 10 to be inspected using the hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment is applied, first, the inspection position 19 is detected. The hologram 10 as a specimen is arranged with its surface facing upward, that is, facing the camera 12. In this case, the hologram 10 is set at the inspection position 19 so that the camera 12 can photograph the surface of the hologram 10 from directly above.
[0049]
When the hologram 10 to be inspected is arranged at the inspection position 19 in this way, next, the inspection light h is irradiated by the flat light source 11 toward the surface of the hologram 10 to be inspected. The inspection light h emitted from the plane light source 11 is diffused by the diffuser 18. As a result, the inspection light h is applied to the surface of the hologram 10 from substantially all directions on the surface side except the portion immediately above.
[0050]
The operation in the case where the inspection light is irradiated onto the surface of the hologram 10 from substantially all directions of the front surface side except the directly above portion will be described with reference to FIG.
[0051]
That is, in order to obtain the diffracted light diffracted in the V direction on the surface of the hologram 10, for example, the inspection light h is applied to the hologram 10 from all directions except the V direction, such as the R direction shown in FIG. Need to be irradiated. At this time, if the diffraction grating is cut at the point C of the hologram 10, diffracted light in the V direction exists.
[0052]
However, when the diffraction grating at the point C is flattened, that is, when the diffraction grating has a defect, for example, as shown in the R ′ direction in FIG. No diffracted light is present. As described above, when the point C is imaged from directly above in a state where there is no diffracted light in the V direction, it is imaged as a black point.
[0053]
Therefore, the presence or absence of a defect can be detected by comparing the image data captured in this way with the image data of a defect-free hologram having the same specifications as shown in FIG.
[0054]
Therefore, if the inspection light h is applied to the hologram 10 as an object from substantially all directions of the surface except for the portion directly above, the surface of the hologram 10 has a defect and the diffraction grating is crushed. When there is a flat portion, there is no diffracted light in the upward direction (V direction) from that portion. As a result, as shown in FIG. 6B, this portion is imaged as a black point k by the camera 12 disposed directly above the hologram 10.
[0055]
Further, by forming an image of the diffracted light from the hologram 10 as the object on the camera 12 using the telecentric lens 22 (#a), an accurate image viewed from directly above the hologram 10 as the object is obtained. The image is taken.
[0056]
After the image captured by the camera 12 is acquired by the image capturing unit 14 and digitized, the digitized image data is output to the image processing device 16 and stored in the inspection image data storage unit 28. You.
[0057]
On the other hand, the reference image data storage unit 30 stores, for example, as shown in FIG. 6A, image data that has the same specifications as the hologram 10 of the subject and is obtained by imaging a defect-free hologram from directly above. It is photographed and stored in advance.
[0058]
Then, the image data comparison unit 32 compares the image data stored in the inspection image data storage unit 28 with the image data stored in the reference image data storage unit 30.
[0059]
Further, as a result of the comparison by the image data comparing unit 32, when there is a different portion between the two image data, as indicated by a black point k in FIG. It is determined that the surface of a certain hologram 10 has a defect. On the other hand, if there is no difference between the two image data, it is determined that the hologram 10 as the subject has no defect on the surface.
[0060]
As described above, in the hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment is applied, if the surface of the hologram 10 that is the subject has a defect, Since the light does not diffract right above, it can be picked up as a black point k, for example, as shown in FIG.
[0061]
Therefore, it is possible to accurately detect a defect on the surface of the hologram 10 as an object by comparing the hologram 10 having the same specifications as the object to be inspected with a hologram having no defect with image data taken from directly above. It becomes possible.
[0062]
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIGS.
[0063]
FIG. 7 is a functional configuration diagram illustrating an example of a hologram defect detection device to which the hologram defect detection method according to the second embodiment is applied.
[0064]
That is, the hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment is applied is replaced with the planar light source 11 used in the first embodiment shown in FIG. Only in that a cylindrical light source 36 as shown in FIG. Therefore, in FIG. 7, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Here, only different parts will be described.
[0065]
The cylindrical light source 36 irradiates the hollow portion 38 with inspection light h made of, for example, white light. The diffuser 18 which is a diffusion plate for diffusing the inspection light h is disposed on the inner peripheral surface of the cylindrical light source 36 on the hollow portion 38 side.
[0066]
As shown in FIG. 7, such a cylindrical light source 36 is mounted on the inspection table 17, and an inspection position 19 provided on the inspection table 17 is located on the center of the cylindrical axis of the hollow portion 38. To be arranged. Further, the camera 12 is arranged immediately above the inspection position 19 so that the center thereof is located on the same cylindrical axis center.
[0067]
With this arrangement, the inspection light h emitted from the cylindrical light source 36 is diffused in all directions by the diffuser 18, and the inspection light 19 is placed on the inspection position 19 with the surface of the hologram 10 to be inspected facing upward. In this case, the inspection light h is applied to the surface of the hologram 10 from substantially all directions on the front surface side except the upper portion. Although the higher the height H of the cylindrical light source 36 is, the higher the height is, it is ideal because the inspection light h from an angle closer to the vertical can also irradiate the hologram 10 as the subject. Any height may be used as long as the inspection light can be irradiated at an angle such that the diffracted light from the hologram 10 is incident on the camera 12. It is preferable to use a telecentric lens as the imaging lens 22, as in the first embodiment.
[0068]
As described above, by adopting a configuration in which the cylindrical light source 36 as shown in FIG. 7 is applied instead of the planar light source 11 as shown in FIG. 1, the operation and effect obtained in the first embodiment can be obtained. Can play.
[0069]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS.
[0070]
FIG. 9 is a functional configuration diagram illustrating an example of a hologram defect detection device to which the hologram defect detection method according to the third embodiment is applied.
[0071]
That is, the hologram defect detection device to which the hologram defect detection method according to the present embodiment is applied is a device that detects a surface defect while winding up a thin hologram film 40 wound in a roll shape as an object. A detection mechanism including a winding mechanism including the roll cores 42 and 46, the roller 44, and a winding device 47 for rotating the rollers and a black light-reflective layer 52 including the cylindrical light source 36, the camera 12, and the slit 54. And an image processing system including the image capturing unit 14 and the image processing device 16. Here, the configuration of the image capturing unit 14 and the image processing device 16 is the same as the configuration of the image capturing unit 14 and the image processing device 16 shown in FIG. Here, only the different parts will be described.
[0072]
The roll core 42 is a core around which the hologram film 40 which has not been inspected is wound, and the roll core 46 is a core which winds the hologram film 40 which has been inspected. The roll core 42 and the roll core 46 are configured to rotate in the direction indicated by the arrow in the drawing by driving the winding device 47 together with the roller 44. As a result, the uninspected hologram film 40 wound on the roll core 42 is supplied to the detection system side, and the hologram film 40 on which the surface defect inspection has been performed by the detection system is wound up by the roll core 46. I have.
[0073]
As shown by an arrow in the plan view of FIG. 10, a slit 54 is formed in the black anti-reflection layer 52 of the detection system along a direction substantially perpendicular to the winding direction in which the hologram film 40 as the subject is wound. I'm cutting. Then, as the roller 44 rotates, the hologram film 40 is positioned immediately below the slit 54. Then, as shown in FIG. 10, the hologram film 40 (this portion is referred to as the “inspection area 41”) seen through the slit 54 is made substantially flat.
[0074]
The cylindrical light source 36 has the same configuration as that described in the second embodiment, and the center G of the slit 54 as shown in the plan view of FIG. Deploy. With such a configuration, the inspection light is applied to the surface of the inspection area 41 from the substantially entire surface side except the portion directly above the slit 54 via the slit 54.
[0075]
Further, the camera 12 is arranged immediately above the inspection position 19 so that the center thereof is located on the same cylindrical axis center. As a result, the camera 12 captures an image of the inspection area 41 illuminated by the inspection light as viewed from directly above via the slit 54. An imaging lens 22 is provided on the front side of the camera 12. It is preferable that the imaging lens 22 also uses the telecentric lens 22 (#a) as described in the first and second embodiments. By using the telecentric lens 22 (#a), the camera 12 captures a clear image of the inspection area 41 viewed from directly above.
[0076]
The image captured by the camera 12 is digitized by the image capturing unit 14, and the digitized image data is output to the image processing device 16. Defect determination is performed on the image data. Since the configurations of the image capturing unit 14 and the image processing device 16 are as described in the first embodiment, detailed description will be omitted here.
[0077]
When a defect is determined for one piece of image data in which the inspection area 41 is arranged in this way, the winding device 47 sends the hologram film 40 from the roll core 42 side to the roll core 46 side, so that the next One image data (see FIG. 11) on which the inspection area 41 is arranged is inspected.
[0078]
Then, the defect determination is also performed as described above for one image data in which the next inspection area 41 is arranged, and by repeating this, the surface defect of the hologram film 40 is continuously detected.
[0079]
Next, the operation of the hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment configured as described above is applied will be described.
[0080]
That is, using a hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment is applied, the hologram film 40 on a thin plate wound in a roll shape around the roll core 42 is wound around the roll core 46 while being wound around the roll core 46. In order to determine the presence or absence of a defect in, first, the winding device 47 is driven. Accordingly, the roll core 42 and the roll core 46 rotate together with the roller 44 in the direction indicated by the arrow in FIG. As a result, the uninspected hologram film 40 wound around the roll core 42 is supplied to the detection system side, and the hologram film 40, whose surface has been inspected for defects by the detection system, is wound by the roll core 46.
[0081]
As shown by the arrow in the plan view of FIG. 10, a slit 54 is formed in the black anti-reflection layer 52 of the detection system along a direction perpendicular to the winding direction in which the hologram film 40 as the subject is wound. Has been. Then, the hologram film 40 is located directly below the slit 54. Then, as shown in FIG. 10, the inspection area 41 of the hologram film 40 seen through the slit 54 becomes substantially flat.
[0082]
When the inspection area 41 is arranged via the slit 54 in this manner, the cylindrical light source 36 irradiates the inspection light toward the surface of the hologram film 40 next. The inspection light emitted from the cylindrical light source 36 is diffused by the diffuser 18. As a result, the inspection light is irradiated onto the surface of the inspection area 41 from substantially all directions on the front surface side except for the portion directly above.
[0083]
As described above, when the inspection area 41 is irradiated with the inspection light from substantially all directions of the surface side except the upper portion, there is a defect in one piece of image data in which the inspection area 41 is arranged. When there is a flat portion where the diffraction grating is crushed, there is no diffracted light in the upward direction (the V direction shown in FIG. 5) from that portion. As a result, this point is imaged by the camera 12 disposed immediately above the inspection area 41 as, for example, a black point k as shown in FIG. 6B.
[0084]
Further, by forming an image of the diffracted light from the inspection area 41, which is the subject, on the camera 12 using the telecentric lens 22 (#a), an accurate image viewed from directly above the inspection area 41 is captured. .
[0085]
After the image captured by the camera 12 is acquired by the image capturing unit 14 and digitized, the digitized image data is output to the image processing device 16 and stored in the inspection image data storage unit 28. You.
[0086]
On the other hand, the reference image data storage unit 30 has the same specifications as the hologram 10 of the subject, and for example, as shown in FIG. It is photographed and stored in advance.
[0087]
Then, the image data comparison unit 32 compares the image data stored in the inspection image data storage unit 28 with the image data stored in the reference image data storage unit 30.
[0088]
Further, as a result of the comparison by the image data comparing unit 32, when there is a difference between the two image data, the defect determining unit 34 determines that there is a defect in one piece of the image data that has arranged the inspection area 41. Is done. On the other hand, if there is no difference between the two pieces of image data, it is determined that one piece of image data including the inspection areas has no defect.
[0089]
When a defect is determined for one image data in which the inspection area 41 is arranged in this way, the winding device 47 sends the hologram film 40 from the roll core 42 side to the roll core 46 side. As shown in (1), one image data in which the next inspection area 41 is arranged is inspected.
[0090]
Then, the defect determination is also performed as described above for one image data in which the next inspection area is arranged, and by repeating this, the surface defect of the hologram film 40 is continuously detected.
[0091]
As described above, in the hologram defect detection apparatus to which the hologram defect detection method according to the present embodiment is applied, by the above-described operation, the defect detection on the surface of the hologram film 40 as the object is continuously performed. It is possible to do.
[0092]
Similar effects can be obtained by adopting a configuration in which the planar light source 11 is used instead of the cylindrical light source 36 as in the relationship between the first embodiment and the second embodiment. Can be.
[0093]
Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to such configurations. Within the scope of the technical idea described in the claims, those skilled in the art can come up with various modified examples and modified examples, and these modified examples and modified examples are also within the technical scope of the present invention. It is understood that it belongs to.
[0094]
【The invention's effect】
As described above, according to the present invention, the surface of a hologram, which is a subject, is irradiated with inspection light from substantially all directions on the surface side except for a portion immediately above the surface of the hologram, and is irradiated with the inspection light. It is possible to obtain image data in which the surface of the hologram is viewed from directly above.
[0095]
If there is a defect on the surface of the hologram, a black dot is picked up in this image data, so that a hologram defect detection apparatus and defect detection method capable of detecting a defect on the surface of the hologram with high accuracy Can be realized.
[Brief description of the drawings]
FIG. 1 is a functional configuration diagram showing an example of a hologram defect detection apparatus to which a hologram defect detection method according to a first embodiment is applied.
FIG. 2 is a plan view showing an example of a flat light source.
FIG. 3 is a schematic diagram for explaining the principle of a telecentric lens.
FIG. 4 is a schematic diagram for explaining the principle of a non-telecentric lens.
FIG. 5 is a diagram for explaining a diffraction direction of diffracted light by a hologram.
FIG. 6 is a schematic diagram showing an example of hologram image data.
FIG. 7 is a functional configuration diagram showing an example of a hologram defect detection device to which the hologram defect detection method according to the second embodiment is applied.
FIG. 8 is a perspective view showing an example of a cylindrical light source.
FIG. 9 is a functional configuration diagram showing an example of a hologram defect detection apparatus to which the hologram defect detection method according to the third embodiment is applied.
FIG. 10 is a detailed diagram of a detection system.
FIG. 11 is a schematic diagram for explaining an inspection area.
[Explanation of symbols]
h… Inspection light
k ... black dot
p ... pinhole
10 Hologram
11 Planar light source
12… Camera
14 ... Image capture unit
16. Image processing device
17… Inspection table
18 ... Diffuser
19… Inspection position
20 ... Imaging hole
22 ... Imaging lens
22 (#a): Telecentric lens
22 (#b): Non-telecentric lens
24 Cylindrical body
25 ... torso
26 ... hollow part
27 ... inside surface
28: Image data storage for inspection
30: Reference image data storage
32: Image data comparison unit
34: Defect judgment unit
36 ... Cylindrical light source
38 hollow part
40 ... hologram film
41… Inspection area
42, 46 ... roll core
44 ... Roller
47 ... Winding device
52: Black anti-reflection layer
54 ... Slit

Claims (9)

An apparatus for detecting a defect on the surface of a thin hologram as an object,
On the surface of the hologram that is the subject, an inspection light source for irradiating inspection light from substantially all directions on the surface side except for a portion directly above the surface of the hologram,
Imaging means for capturing an image of the surface of the hologram illuminated by the inspection light as viewed from directly above, and acquiring image data;
Based on the image data acquired by the imaging means and the image data of the hologram, which has been previously imaged and acquired and has the same specifications as the hologram as the object, defects on the surface of the hologram as the object are detected. A hologram defect detection device, comprising: a determination unit that determines whether or not there is a hologram. The hologram defect detection device according to claim 1,
A defect detection device for a hologram, wherein the inspection light source has a cylindrical shape, and the hologram as the subject and the imaging unit are arranged in a substantially cylinder. An apparatus for detecting a defect on the surface of the hologram while winding up a thin hologram wound in a roll shape as an object,
A slit that is grooved along a direction perpendicular to the winding direction in which the hologram as the subject is wound, and is disposed close to the surface of the hologram;
On the surface of the hologram that is the subject, from substantially all directions on the surface side except immediately above the slit, a light source for inspection light that irradiates inspection light through the slit,
Imaging means for sequentially inspecting the inspection area, which is the surface of the hologram illuminated by the inspection light, as viewed from directly above through the slit, and arranging these images as one image data;
Based on the image data obtained by the imaging unit and the image data of a hologram having the same specifications as the hologram as the subject and previously imaged and obtained, it is determined whether there is a defect in the inspection area. Determining means for determining;
A hologram defect detection device comprising: a winding unit that winds the hologram as the subject so that the determination unit can sequentially execute the hologram. The hologram defect detection device according to claim 3,
A hologram defect detection device, wherein the inspection light source has a cylindrical shape, and the inspection area and the imaging unit are arranged substantially in a cylinder. The hologram defect detection device according to claim 1 or 3,
The inspection light source is a hologram defect detection device having a flat plate shape, and the imaging unit disposed immediately above the inspection light source. The hologram defect detection device according to any one of claims 1 to 5,
The imaging unit is disposed immediately above, provided between the imaging unit and the hologram that is the subject, the image of the surface of the hologram illuminated by the inspection light viewed from the immediately above, A hologram defect detection device to which a telecentric lens for forming an image in an imaging unit is added. The hologram defect detection device according to any one of claims 1 to 6,
The determining means includes:
Image data based on an image captured by the imaging unit, and a comparison unit that compares the image data of a hologram having no defect with the same specifications as the hologram that is the subject that has been captured and acquired in advance,
As a result of the comparison by the comparing means, if there is a difference between the two image data, it is determined that there is the defect, and if there is no difference between the two image data, the defect is not present. A hologram defect detection device, comprising: A method for detecting a defect on the surface of a thin plate-shaped hologram that is an object,
In advance, image data of a hologram having no defect with the same specification as the hologram that is the subject is imaged and acquired,
For the surface of the hologram that is the subject, irradiate the inspection light from substantially all directions of the surface side except the upper portion of the hologram surface,
Obtain image data by capturing an image of the surface of the hologram illuminated by the inspection light as viewed from directly above,
Based on the acquired image data and the previously acquired defect-free hologram image data, the hologram is configured to determine whether there is a defect on the surface of the hologram that is the subject. Defect detection method. A method for detecting a defect on the surface of the hologram while winding up a thin hologram wound in a roll shape as an object,
In advance, image data of a hologram having no defect with the same specification as the hologram that is the subject is imaged and acquired,
A slit grooved along a direction perpendicular to a winding direction in which the hologram as the subject is wound is arranged close to the surface of the hologram,
On the surface of the hologram that is the subject, from substantially all directions on the surface side except directly above the slit, irradiate inspection light through the slit,
The inspection area, which is the surface of the hologram illuminated by the inspection light, sequentially captures an image viewed from directly above through the slit, and arranges them as one image data,
Based on the image data and the previously acquired defect-free hologram image data, it is determined whether the inspection area has a defect,
After the determination is made, the defect of the surface of the thin hologram wound in the roll shape is detected by repeating the winding of the hologram as the subject so that the determination means can sequentially execute the determination. Hologram defect detection method.

Images