JP2012255652A - Device and method for inspecting anodized alumina, and manufacturing method of component having anodized alumina surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for easily inspecting the state (shape of fine rugged structure, flaws, and the like) of anodized alumina, and a manufacturing method of a component having an anodized alumina surface with reduced unevenness in the shape of fine rugged structure and surface flaws.SOLUTION: An inspection device is used, comprising a linear lighting device 10 (first lighting means) which allows a mold 100 to be irradiated with light; a color line CCD camera 12 (first imaging means) which images light reflected by the anodized alumina of the mold 100; a linear lighting device 20 (second lighting means) which allows the mold 100 to be irradiated with light; a monochrome line CCD camera 22 (second imaging means) which images light reflected by the anodized alumina of the mold 100; and an image processing device 30 (image processing means) which determines quality of the anodized alumina on the basis of the color data and brightness data obtained from the images taken by the two cameras.

Description

  The present invention has an apparatus and method for inspecting an anodized alumina (porous oxide film) having a plurality of pores (fine concavo-convex structure) formed on the surface of an aluminum substrate, and an anodized alumina on the surface. The present invention relates to a method for manufacturing a member (such as a mold).

  An article having a fine concavo-convex structure with a pitch of less than or equal to the wavelength of visible light on the surface exhibits an antireflection function and the like, and thus its usefulness is drawing attention. In particular, it is known that a fine concavo-convex structure called a moth-eye structure exhibits an effective antireflection function by continuously increasing from a refractive index of air to a refractive index of a material.

The following method is known as a method for producing an article having a fine concavo-convex structure on the surface, and the method (ii) is excellent from the viewpoint of productivity and economy.
(I) A method for producing an article having a fine concavo-convex structure on its surface by directly processing the surface of a transparent substrate or the like.
(Ii) A method of transferring the inverted structure onto the surface of a transparent substrate or the like using a mold having an inverted structure corresponding to the fine concavo-convex structure.

As a method for forming an inverted structure in a mold, an electron beam drawing method, a laser beam interference method, and the like are known. In recent years, a method of anodizing the surface of an aluminum substrate has attracted attention as a method for forming an inverted structure more easily (see, for example, Patent Document 1).
Anodized alumina formed by anodizing the surface of an aluminum substrate is an aluminum oxide film (alumite) and has a plurality of pores (fine concavo-convex structure) whose pitch is equal to or less than the wavelength of visible light.

  In the anodized alumina, if unevenness occurs in the concentration or temperature of the electrolytic solution in which the aluminum substrate is immersed during anodization, or the surface property of the aluminum substrate is uneven, Some unevenness may occur in the shape of the structure (depth and inner diameter of pores, pitch between pores, etc.), the thickness of anodized alumina, and the like. When the area of the region where the shape of the fine concavo-convex structure of the anodized alumina or the thickness of the anodic alumina is not formed as designed increases, the mold cannot be used for manufacturing an article having the fine concavo-convex structure on the surface. However, until now, there has been no method for easily inspecting the shape of the fine concavo-convex structure of anodized alumina and the thickness of the anodized alumina.

Anodized alumina also has a problem that when a liquid foreign substance is easily damaged by contact or the like, the foreign substance infiltrates into the pores and fills the pores.
Therefore, the defect in the anodized alumina is obtained by combining the inspection of the shape of the fine concavo-convex structure of the anodized alumina and the thickness of the anodized alumina with the inspection of the surface of the anodized alumina for defects such as scratches and foreign matters. It is possible to investigate the cause such as in which process the error occurred and what kind of factor caused it. However, until now, there has been no method for easily inspecting the surface of the anodized alumina for defects such as scratches and foreign matters in combination with the fine concavo-convex structure of the anodized alumina.

JP 2005-156695 A

  The present invention relates to an inspection apparatus and an inspection method capable of simply inspecting the shape of the fine concavo-convex structure of anodized alumina, the thickness of the anodized alumina, and defects on the surface of the anodized alumina, and the shape of the fine concavo-convex structure of the anodized alumina. And a method for producing a member having an anodized alumina on the surface, in which unevenness in thickness of the anodized alumina is suppressed and defects on the surface of the anodized alumina are suppressed.

  As a result of intensive studies in view of the above problems, the present inventors have found that the color of light reflected by anodized alumina changes according to the fine concavo-convex structure of anodized alumina, resulting in the present invention. The color of the light reflected by the anodized alumina reflects not only the interference color of the thin film as seen in a shabby ball, but also the influence of the shape of the fine concavo-convex structure of the anodized alumina and the thickness of the anodized alumina. .

  That is, the inspection apparatus for anodized alumina of the present invention is imaged by an irradiation means for irradiating light to the anodized alumina, an imaging means for imaging the light irradiated from the irradiation means and reflected by the anodized alumina, and the imaging means. Image processing means for determining the quality of the state of the anodized alumina based on color information and luminance information obtained from the obtained image.

  The inspection apparatus for anodized alumina according to the present invention includes a first irradiation unit and a second irradiation unit as the irradiation unit, and the first irradiation unit is irradiated as the imaging unit, and the anodized alumina. A first imaging unit that images the light reflected by the second imaging unit, and a second imaging unit that images the light irradiated from the second irradiation unit and reflected by the anodized alumina. A luminance obtained from an image captured by the first imaging unit and a second imaging unit based on color information obtained from the image captured by the imaging unit. It is preferable to have a second determination unit that determines the quality of the state of the anodized alumina based on the information.

The first imaging means is preferably arranged so that the angle of the optical axis of the first imaging means is 45 to 89.9 ° with respect to the normal of the surface of the anodized alumina.
The second imaging means is preferably arranged so that the angle of the optical axis of the second imaging means is 0 to 70 ° with respect to the normal of the surface of the anodized alumina.
The first imaging means outputs an RGB image signal as the color information, and the first determination unit determines the quality of the anodized alumina state based on the RGB image signal. It may be.
The first imaging unit outputs an RGB image signal as the color information, and the image processing unit includes a conversion unit that converts the RGB image signal into HSL color system information, A 1st determination part may determine the quality of the state of an anodized alumina based on the information of an HSL color system.

  In the method for inspecting anodized alumina of the present invention, the anodized alumina is irradiated with light from the irradiation means, the light irradiated from the irradiation means and reflected by the anodized alumina is imaged by the imaging means, and the image is captured by the imaging means. The quality of the anodized alumina is determined based on the color information and luminance information obtained from the image.

  In the method for inspecting anodized alumina of the present invention, the first anodized alumina is irradiated with light from the first irradiation means, and the light irradiated from the first irradiation means and reflected by the anodized alumina is reflected by the first imaging means. Based on the color information obtained from the image captured from the image captured by the first imaging unit, the quality of the anodized alumina is determined, and the anodized alumina is irradiated with light from the second irradiation unit, The light irradiated from the second irradiation means and reflected by the anodized alumina is imaged by the second imaging means, and the anodized alumina is obtained based on the luminance information obtained from the image captured by the second imaging means. It is preferable to determine the quality of the state.

In the anodized alumina inspection method of the present invention, an RGB image signal is obtained as color information from the image captured by the first imaging means, and the state of the anodized alumina is determined based on the RGB image signal. Good or bad may be determined.
In the anodized alumina inspection method of the present invention, an RGB image signal is obtained as color information from the image captured by the first imaging means, and the RGB image signal is converted into HSL color system information. The quality of the anodized alumina state may be determined based on the information of the HSL color system.

  The method for producing a member having an anodized alumina on the surface thereof according to the present invention comprises a step of obtaining a member having an anodized alumina on the surface by anodizing the surface of the aluminum substrate, and an inspection of the anodized alumina according to the present invention. And a step of inspecting the anodized alumina by a method.

According to the anodized alumina inspection apparatus and inspection method of the present invention, the shape of the fine concavo-convex structure of the anodized alumina, the thickness of the anodized alumina, and the surface defects of the anodized alumina can be easily inspected.
According to the method for manufacturing a member having an anodized alumina on the surface of the present invention, the unevenness of the shape of the fine concavo-convex structure of the anodized alumina and the thickness of the anodized alumina can be suppressed, and defects on the surface of the anodized alumina can be prevented. A suppressed member having anodized alumina on the surface can be stably produced.

In addition, by simultaneously inspecting the shape of the fine concavo-convex structure of the anodized alumina, the thickness of the anodized alumina, and defects on the surface of the anodized alumina, the inspection results indicate the process and cause of the abnormality in the anodized alumina. We can investigate early. Then, by feeding back the result to the anodizing step, it is possible to prevent the abnormality from recurring and to improve the quality of the member having the anodized alumina on the surface.
In addition, a member having anodized alumina on the surface compared with the case where the inspection of the shape of the fine concavo-convex structure of anodized alumina and the thickness of the anodized alumina and the inspection of defects on the surface of the anodized alumina are performed separately Man-hours to replace As a result, the inspection time can be shortened and the risk of flaws and foreign matter adhesion due to replacement can be reduced, so that the inspection cost (manufacturing cost) of a member having anodized alumina on the surface can be reduced.

It is the top view and side view which show an example of the inspection apparatus of the anodic oxidation alumina of this invention. It is sectional drawing which shows the manufacturing process of the mold which has an anodized alumina on the surface. It is the image of the surface of the member which has an anodized alumina on the surface imaged with the 1st imaging means. FIG. 4 is a graph plotting a hue difference with respect to a normal portion in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 5 °. FIG. 4 is a graph plotting a hue difference with respect to a normal portion in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 15 °. FIG. 4 is a graph plotting a hue difference with respect to a normal portion in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 25 °. FIG. 4 is a graph plotting a hue difference with respect to a normal part in each pixel of a line 102 in FIG. 3 obtained from an image picked up by a first image pickup means having an optical axis angle θ ₁ of 35 °. FIG. 4 is a graph plotting a hue difference with respect to a normal portion in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 45 °. FIG. 4 is a graph plotting a hue difference with respect to a normal part in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 55 °. FIG. 4 is a graph plotting a hue difference with respect to a normal part in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 65 °. FIG. 4 is a graph plotting a hue difference with respect to a normal part in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 75 °. FIG. 4 is a graph plotting a hue difference with respect to a normal part in each pixel of a line 102 in FIG. 3 obtained from an image captured by a first imaging unit having an optical axis angle θ ₁ of 85 °. FIG. 4 is a graph plotting the maximum value of the hue difference with respect to the normal portion in each pixel of the line 102 in FIG. 3 for each optical axis angle θ ₁ . It is the image of the surface of the member which has an anodized alumina on the surface imaged with the 1st imaging means. It is the image of the surface of the member which has an anodized alumina on the surface imaged with the 2nd imaging means.

<Inspection equipment for anodized alumina>
FIG. 1 is a top view and a side view showing an example of the anodized alumina inspection apparatus of the present invention.
The inspection apparatus includes a rotating means (not shown) for rotating a roll-shaped mold 100 in which anodized alumina having a plurality of pores (fine concavo-convex structure) is formed on the surface of a roll-shaped aluminum substrate; A line illuminating device 10 (first irradiating means) that irradiates light in a line shape; a color line CCD camera 12 (first illuminating device) that images the light irradiated from the line illuminating device 10 and reflected by the anodized alumina of the mold 100 One imaging means); a line illuminating device 20 (second irradiating means) for irradiating the mold 100 with light in a line; and light irradiated from the line illuminating device 20 and reflected by the anodized alumina of the mold 100 A monochrome line CCD camera 22 (second imaging means) for imaging a color line CCD camera 12 and a monochrome line CCD camera 1 An image processing device 30 (image processing means) for processing an image signal from; a mold 100, a line illumination device 10, a color line CCD camera 12, a line illumination device 20, and a monochrome line CCD camera 22; Moving means (not shown) for relatively moving along the longitudinal direction.

(First irradiation means)
The line illumination device 10 is disposed so that the longitudinal direction of the light irradiation range to the mold 100 is orthogonal to the circumferential direction (rotation direction) of the mold 100.
Examples of the line illumination device 10 include a high-frequency fluorescent lamp lighting device, rod illumination, optical fiber illumination arranged in a line, LED illumination, and the like.

(First imaging means)
The color line CCD camera 12 is a camera in which a plurality of color CCD elements are arranged one-dimensionally. The color CCD element 12 receives light emitted from the line illumination device 10 and reflected by the anodized alumina of the mold 100. An RGB image signal is output for each pixel.

The color line CCD camera 12 is arranged so that the longitudinal direction of the imaging range is orthogonal to the circumferential direction (rotation direction) of the mold 100. Further, the color line CCD camera 12 has an angle θ ₁ of 45 of the optical axis L ₁ of the color line CCD camera 12 with respect to the normal line N ₁ of the surface (tangent plane) of the anodized alumina of the mold 100 in the imaging range. It is preferable to arrange it at ˜89.9 °. When the angle θ ₁ is 45 ° or more, the color of the reflected light from the anodized alumina corresponding to the fine uneven structure of the anodized alumina appears clearly. The angle θ ₁ is preferably 65 ° or more, more preferably 70 ° or more, and still more preferably 80 ° or more, from the viewpoint of being less susceptible to noise. If the angle θ ₁ exceeds 89.9 °, imaging becomes difficult. When the angle θ ₁ is around 89.9 °, the imaging range with respect to the circumferential direction of the mold 100 is increased and the imaging resolution is lowered. Also good. The first imaging means may be arranged so as to be able to receive the light irradiated on the mold by the first irradiation means and reflected by the mold 100, but preferably the light of the first imaging means. and the shaft, the optical axis of the first irradiation means, are arranged symmetrically with respect to the normal N _1.

(Second irradiation means)
The line illumination device 20 is disposed so that the longitudinal direction of the light irradiation range to the mold 100 is orthogonal to the circumferential direction (rotation direction) of the mold 100.
Examples of the line illumination device 20 include a fluorescent lamp lighting device for high-frequency lighting, rod illumination, optical fiber illumination arranged in a line, LED illumination, and the like.

  In addition, when detecting a flaw etc. parallel to the circumferential direction (rotation direction) of the mold 100, directivity and inclination are given to the emitted light of the line-shaped illumination device 20, and the circumferential direction (rotation direction) of the mold 100 and It is also possible to make the light hit the side surfaces of the parallel flaws and make the flaws stand out more clearly.

(Second imaging means)
The monochrome line CCD camera 22 is a camera in which a plurality of CCD elements are arranged one-dimensionally. The CCD element receives the light irradiated from the line illumination device 20 and reflected by the anodized alumina of the mold 100, and each pixel. Output a monochrome image signal.

The monochrome line CCD camera 22 is arranged so that the longitudinal direction of the imaging range is orthogonal to the circumferential direction (rotation direction) of the mold 100. Further, the monochrome line CCD camera 22 has an angle θ ₂ of the optical axis L ₂ of the monochrome line CCD camera 22 with respect to the normal line N ₂ of the surface (tangent plane) of the anodized alumina of the mold 100 in the imaging range. It is preferable to be arranged to be ˜70 °. If the angle theta ₂ is 70 ° or less, foreign matter anodized alumina, easy to detect defects such as scratches. However, when the angle θ ₂ is 0 °, the monochrome line CCD camera 22 itself reflected on the surface of the mold 100 is also reflected in the image and becomes noise, so the angle θ ₂ is more preferably 5 to 50 °. The second imaging unit may be arranged so as to be able to receive the light irradiated on the mold by the second irradiation unit and reflected by the mold 100. Preferably, the light of the second imaging unit is used. and the shaft, the optical axis of the second irradiation means, are arranged symmetrically with respect to the normal N _2.

(Image processing means)
The image processing apparatus 30 is a first determination unit (not shown) that determines the quality of the anodized alumina based on RGB image signals (color information) obtained from an image captured by the color line CCD camera 12. And a second determination unit (not shown) for determining the quality of the anodized alumina based on the monochrome image signal (luminance information) obtained from the image captured by the monochrome line CCD camera 22; An interface unit (not shown) that electrically connects each CCD camera and the like to each determination unit; and a storage unit (not shown) that stores color information, luminance information, a threshold value used for determination, and the like. .
The image processing apparatus 30 may include a conversion unit that converts RGB image signals into HSL color system information as necessary. In this case, a 1st determination part determines the quality of the state of an anodized alumina based on the information of an HSL color system.

The first determination unit, the second determination unit, the conversion unit, and the like may be realized by dedicated hardware; the first determination unit includes a memory and a central processing unit (CPU), and the first determination unit The function may be realized by loading a program for realizing the functions of the unit, the second determination unit, the conversion unit, and the like into the memory and executing the program. The first determination unit, the second determination unit, the conversion unit, and the like may be provided in one image processing apparatus, or each may be provided in an individual image processing apparatus.
In addition, an input device, a display device, and the like are connected to the image processing apparatus as peripheral devices. Here, the input device refers to an input device such as a display touch panel, a switch panel, or a keyboard, and the display device refers to a CRT, a liquid crystal display device, or the like.

(First determination unit)
The first determination unit acquires 256-tone RGB image signals for each pixel output from the color line CCD camera 12, and based on the acquired image signals, the shape of the fine concavo-convex structure of anodized alumina ( It is determined whether the depth and inner diameter of the pores, the pitch between the pores, etc.) and the thickness of the anodized alumina are within a predetermined range.
Further, for the purpose of simplifying the determination, the RGB image signal is converted into the HSL color system by the conversion unit, and the fine concavo-convex structure of the anodized alumina is converted based on the gradation (H) digital information. It is also possible to determine whether the shape (depth and inner diameter of pores, pitch between pores, etc.), the thickness of anodized alumina, etc. are within a predetermined range.

  In the determination, specifically, NG pixels whose color gradation is outside the preset gradation (threshold) range are extracted, and the ratio of NG pixels in a predetermined region (for example, 2000 × 4000 pixels) is When a predetermined ratio (for example, 5%) is exceeded, it is determined that the mold 100 to be inspected is a defective product.

For example, the threshold value for determination by the RGB image signal can be determined as follows.
Three types of molds A, B, and C having a pore depth of anodized alumina and a pitch between pores of 200 nm and 100 nm, 100 nm and 100 nm, 200 nm, and 200 nm, respectively, are prepared.

  The surfaces of the three types of molds are imaged using the line illumination device 10 (first irradiation means) and the color line CCD camera 12 (first imaging means) of the inspection apparatus shown in FIG. Table 1 shows the average values of 256 gradation RGB image signals.

  When the depth of the pores and the pitch between the pores are different, the color of the reflected light from the mold is different. That is, the RGB image signal values shown in Table 1 are different.

Comparing molds A and B having the same pitch between the pores and different depths of the pores, the difference in G signal is the largest at 49. Here, for example, if the mold A is a good product and the color threshold is 40, the mold B can be determined as a defective product from the difference in the G signal.
In this example, the difference in the depth of the pores is 100 nm. However, if the difference in depth is smaller than 100 nm, the determination can be made by reducing the threshold value.

When molds A and C having the same pore depth and different pitches between the pores are compared, the difference in G signal is the largest at 17. Here, for example, if the mold A is a good product and the color threshold is 10, the mold C can be determined as a defective product from the difference in the G signal.
In this example, the difference in pitch between the pores is 100 nm. However, when the difference in pitch between the pores is smaller than 100 nm, the determination can be made by reducing the threshold value.

Although both the depth of the pores and the pitch between the pores are different, when the aspect ratio (depth of the pore / pitch between the pores) is 1.0 and the same mold B and C are compared, the G signal The difference is as large as 32. Here, for example, if the mold B is a good product and the color threshold is 30, the mold C can be determined as a defective product from the difference in the G signal.
In this example, the difference in the depth of the pores and the difference in the pitch between the pores were both 100 nm. However, if the difference in the depth of the pores and the difference in the pitch between the pores is smaller than 100 nm, It is possible to make a determination by reducing.

When it is desired to identify each of the molds A, B, and C, the color threshold can be set to 10, for example, so that the determination can be made with the G signal.
In addition, it is determined whether the shape of fine concavo-convex structure of anodized alumina (depth of pore, inner diameter, pitch between pores, etc.), thickness of anodized alumina, etc. are within a predetermined range based on RGB image signals. The threshold for determining the threshold is determined by paying attention to the G signal having the largest difference among the R, G, and B signals, but the method of determining the threshold is not limited to the above-described method.

Moreover, the threshold value for determining in the HSL color system can be determined as follows.
Three types of molds A, B, and C having a pore depth of anodized alumina and a pitch between pores of 200 nm and 100 nm, 100 nm and 100 nm, 200 nm, and 200 nm, respectively, are prepared.

  The three types of molds are imaged using the line illumination device 10 (first irradiation means) and the color line CCD camera 12 (first imaging means) of the inspection apparatus shown in FIG. Are converted into the HSL color system. Table 2 shows an average value of the hue (H) signals of 256 gradations.

  When the depth of the pores and the pitch between the pores are different, the color of the reflected light from the mold is different. That is, the hue (H) signal values shown in Table 2 are different.

When molds A and B having the same pitch between the pores and different pore depths are compared, the difference is 10. For example, if the mold A is a non-defective product and the color threshold is 5, the mold B can be determined as a defective product.
In this example, the difference in the depth of the pores is 100 nm. However, if the difference in depth is smaller than 100 nm, the determination can be made by reducing the threshold value.

When molds A and C having the same pore depth and different pitches between the pores are compared, the difference is 24. Here, for example, if the mold A is a non-defective product and the color threshold is 20, the mold C can be determined as a defective product.
In this example, the difference in pitch between the pores is 100 nm. However, when the difference in pitch between the pores is smaller than 100 nm, the determination can be made by reducing the threshold value.

Although the depth of the pores and the pitch between the pores are both different, when the aspect ratio (depth of the pore / pitch between the pores) is 1.0 and the same mold B and C are compared, the difference is 14 It is. Here, for example, if the mold B is a good product and the color threshold is 10, the mold C can be determined as a defective product.
In this example, the difference in the depth of the pores and the difference in the pitch between the pores were both 100 nm. However, if the difference in the depth of the pores and the difference in the pitch between the pores is smaller than 100 nm, It is possible to make a determination by reducing.

When it is desired to identify each of the molds A, B, and C, the color threshold can be set to 5, for example, to make a determination.
In addition, it is determined whether the shape of fine concavo-convex structure of anodized alumina (depth and inner diameter of pores, pitch between pores, etc.), thickness of anodized alumina, etc. are within a predetermined range in the HSL color system. The method for determining the threshold value for this is not limited to the method described above.

(Second determination unit)
The second determination unit acquires a 256-tone monochrome image signal for each pixel output from the monochrome line CCD camera 22, and based on the acquired image signal, the anodized alumina has a defect such as a scratch or a foreign object Determine if there is any.

  In the determination, specifically, NG pixels whose gradation of the monochrome image signal is outside the range of the preset gradation (threshold) are extracted, and the NG pixels in a predetermined region (for example, 2000 × 4000 pixels) are extracted. When the ratio exceeds a predetermined ratio (for example, 5%), the mold 100 to be inspected is determined to be defective.

(transportation)
The moving means (not shown) includes the mold 100, the line illumination device 10, the color line CCD camera 12, the line illumination device 20, and the monochrome line CCD camera 22 in order to image the entire outer periphery of the mold 100. 100 is relatively translated along the longitudinal direction.

  The moving means fixes the mold 100 and translates the linear illumination device 10, the color line CCD camera 12, the linear illumination device 20, and the monochrome line CCD camera 22 along the longitudinal direction of the mold 100. The line illumination device 10, the color line CCD camera 12, the line illumination device 20 and the monochrome line CCD camera 22 are fixed, and the mold 100 is extended in the longitudinal direction of the imaging range of the color line CCD camera 12 and the monochrome line CCD camera 22. You may make it translate along a direction.

(Other forms)
The anodized alumina inspection apparatus according to the present invention includes an irradiation unit that irradiates light to the anodized alumina, an imaging unit that images the light irradiated from the irradiation unit and reflected by the anodized alumina, and the imaging unit. The image processing means for determining the quality of the anodized alumina based on the color information and the luminance information obtained from the image is not limited to the illustrated example.

  For example, the first irradiating means is not limited to the line-shaped illumination device 10 in the illustrated example, and may be a planar illumination device or a spot-shaped illumination device. Moreover, you may combine auxiliary members, such as a diffusion plate, a reflecting plate, a cylindrical lens, and a condensing lens, with an illuminating device.

  Further, the first image pickup means is not limited to the color line CCD camera 12 in the illustrated example, and may be a color image CCD camera or a photodetector that measures a reflection spectrum.

The second irradiating means is not limited to the line-shaped illumination device 20 in the illustrated example, and may be a planar illumination device or a spot-shaped illumination device. Moreover, you may combine auxiliary members, such as a diffusion plate, a reflecting plate, a cylindrical lens, and a condensing lens, with an illuminating device. Moreover, it is good also as a structure which irradiates from several directions combining several illuminating devices.
Further, the position of the monochrome line CCD camera 22 is changed, and the color line CCD camera 12 and the color line CCD camera 12 are configured to capture the light irradiated from the line illumination device 10 and reflected by the anodized alumina of the mold 100, thereby forming a line shape. The lighting device 20 may be omitted.

Further, the second imaging means is not limited to the monochrome line CCD camera 22 in the illustrated example, and may be a color line CCD camera.
Further, depending on the angle of the optical axis, the second imaging unit may be omitted and only the color line CCD camera 12 (first imaging unit) may be configured.
The line CCD camera is not limited, and an image CCD camera may be used.

Further, when the length of the mold 100 is within the imaging range of each of the color line CCD camera 12 and the monochrome line CCD camera 22, the above moving means may be omitted.
Alternatively, a plurality of line illumination devices 10, color line CCD cameras 12, line illumination devices 20, and monochrome line CCD cameras 22 may be arranged in the longitudinal direction of the mold 100 to image the entire outer periphery at once.

  Further, a method for determining that the mold 100 to be inspected is a defective product is not limited to the above-described method. For example, instead of determining based on the ratio of the NG pixel area as described above, an area having a large gradation difference compared to the normal part is counted as one defect even if the size is small, and even if the gradation difference is small. Even when the area is large, the defect may be counted, and the quality may be determined based on the total number of defects counted.

Further, in the image processing apparatus 30, the image signal is processed as an image signal having 256 gradations, but it is sufficient that the normal part and the abnormal part can be discriminated from the image signal. Alternatively, it may be 1024 gradations or an analog signal.
In addition, when the first imaging unit is a photodetector, the first determination unit may determine a non-defective product or a defective product from a reflection spectrum measured by the photodetector.
Further, the reflection spectrum may be measured at a constant interval (for example, every 1 nm) in a visible wavelength range (for example, 380 nm to 780 nm), may be measured in a range exceeding the visible wavelength, or may be a wavelength in a local range ( For example, it may be measured at 700 nm or a combination measured at a plurality of wavelengths in a local range (for example, near 400 nm and 700 nm).

<Inspection method for anodized alumina>
An inspection method for anodized alumina using the inspection apparatus shown in FIG. 1 will be described.

  First, a mold 100 is obtained by anodizing the surface of a roll-shaped aluminum substrate under conditions such that the pore depth of the anodized alumina and the pitch between the pores are 200 nm and 100 nm, respectively.

  The mold 100 is attached to a rotating means, and the surface of the anodized alumina of the rotating roll-shaped mold 100 is irradiated with light from the line illumination device 10, and the reflected light from the anodized alumina is imaged by the color line CCD camera 12. To do.

  Further, the surface of the anodized alumina of the rotating roll-shaped mold 100 is irradiated with light from the line illumination device 20, and the reflected light from the anodized alumina is imaged by the monochrome line CCD camera 22.

  If necessary, the line illumination device 10, the color line CCD camera 12, the line illumination device 20, and the monochrome line CCD camera 22 are translated along the longitudinal direction of the mold 100 to image the entire outer surface of the anodized alumina. .

  For the image of the entire outer periphery of the anodized alumina of the mold 100 output from the color line CCD camera 12, the image processing device 30 converts RGB image signals into HSL color system for each pixel as necessary, Digital information of a color (hue (H)) represented by 256 gradations is obtained. Further, with respect to the image of the entire surface of the outer periphery of the anodized alumina of the mold 100 output from the monochrome line CCD camera 22, the image processing apparatus 30 obtains a monochrome image signal for each pixel as digital information of 256 gradations.

  The image processing apparatus 30 extracts NG pixels whose gradation is out of a preset range from the image signals obtained from the color line CCD camera 12 and the monochrome line CCD camera 22, respectively. When the ratio of NG pixels in (× 4000 pixels) exceeds a predetermined ratio (for example, 5%), it is determined that the mold 100 to be inspected is a defective product.

  In the above-described method, the image of the entire outer periphery of the mold 100 is processed at once. However, when the image is large and processing is burdened, a method of processing in a plurality of small regions may be used.

(Function and effect)
In the inspection apparatus and inspection method for anodized alumina described above, the shape of the fine concavo-convex structure of the anodized alumina (the depth and inner diameter of the pores, the pitch between the pores, etc.), the thickness of the anodized alumina, etc. Accordingly, it is possible to estimate whether the fine concavo-convex structure of the anodized alumina is formed as designed by utilizing the change in the color of the light reflected by the anodized alumina. Further, defects such as scratches and foreign matter on the anodized alumina can also be detected. Therefore, the shape of the fine concavo-convex structure of the anodized alumina, the thickness of the anodized alumina, and the surface defects of the anodized alumina can be easily inspected.

  In addition, from the abnormalities such as the shape of fine concavo-convex structure of anodized alumina (pore depth and inner diameter, pitch between pores, etc.), the thickness of anodized alumina, and the defects of anodized alumina, foreign matter, The process and cause of the abnormality in the anodized alumina can be investigated early. In addition, the surface of the anodized alumina is compared to the case where the inspection of the shape of the fine concavo-convex structure of the anodized alumina and the thickness of the anodized alumina and the inspection of defects such as scratches and foreign materials on the anodized alumina are performed separately. Since the man-hour for replacing the member (mold) can be reduced, the inspection time can be shortened, and the risk of flaws and foreign matter adhesion due to the replacement can be reduced.

<Method for producing member having anodized alumina on its surface>
The method for producing a member having an anodized alumina on the surface thereof according to the present invention includes a step of anodizing the surface of an aluminum substrate to obtain a member having an anodized alumina on the surface (anodizing step), According to the anodized alumina inspection method, the method includes a step of inspecting the anodized alumina (inspection step) and a step of repairing the anodized alumina as necessary (repair step).
Hereinafter, a method for producing a mold having an anodized alumina on the surface, which is an example of a member having an anodized alumina on the surface, will be described.

(Anodizing process)
The anodizing step is preferably a step in which the following steps (a) to (f) are sequentially performed.
First oxide film forming step (a):
The surface of the mirror-finished aluminum substrate is anodized in an electrolytic solution under a constant voltage to form an oxide film on the surface (hereinafter also referred to as step (a)).
Oxide film removal step (b):
The oxide film is removed, and pore generation points for anodic oxidation are formed on the surface of the aluminum base (hereinafter also referred to as step (b)).
Second oxide film forming step (c):
The surface of the aluminum base material on which the pore generation point is formed is anodized again under a constant voltage in the electrolytic solution, and an oxide film having pores corresponding to the pore generation point is formed on the surface (hereinafter, process) (Also referred to as (c)).
Hole diameter expansion processing step (d):
The diameter of the pores is enlarged (hereinafter also referred to as step (d)).
Oxide film growth step (e):
The surface of the aluminum substrate having the oxide film with the enlarged pore diameter is anodized again in the electrolytic solution under a constant voltage (hereinafter also referred to as step (e)).
Repeat step (f):
If necessary, the pore diameter expansion treatment step (d) and the oxide film growth step (e) are repeated (hereinafter also referred to as step (f)).

  According to the method having the steps (a) to (f), tapered pores whose diameter gradually decreases in the depth direction from the opening are periodically formed on the surface of the mirror-finished aluminum base material. As a result, a mold in which anodized alumina having a plurality of pores is formed on the surface can be obtained.

Before the step (a), a pretreatment for removing the oxide film on the surface of the aluminum substrate may be performed. Examples of the method for removing the oxide film include a method of dipping in a chromic acid / phosphoric acid mixed solution.
Moreover, although the regularity of the arrangement of the pores is slightly lowered, the step (a) may be performed instead of the step (a) depending on the use of the material to which the mold surface is transferred.
Hereinafter, steps (a) to (f) will be described in detail.

Step (a):
In the first oxide film forming step (a), the mirror-finished aluminum substrate surface is anodized in an electrolytic solution under a constant voltage, and as shown in FIG. An oxide film 42 having holes 41 is formed.
Examples of the electrolytic solution include an acidic electrolytic solution and an alkaline electrolytic solution, and an acidic electrolytic solution is preferable.
Examples of the acidic electrolyte include oxalic acid, sulfuric acid, and a mixture thereof.

When oxalic acid is used as the electrolytic solution, the concentration of oxalic acid is preferably 0.7 M or less. If the concentration of oxalic acid exceeds 0.7M, the current value during anodic oxidation becomes too high, and the surface of the oxide film may become rough.
Moreover, by setting the voltage at the time of anodization to 30 to 60 V, it is possible to obtain a mold in which anodized alumina having highly regular pores with a pitch of about 100 nm is formed on the surface. Regardless of whether the voltage during anodization is higher or lower than this range, the regularity tends to decrease, and the pitch may be larger than the wavelength of visible light.
The temperature of the electrolytic solution is preferably 60 ° C. or lower, and more preferably 45 ° C. or lower. When the temperature of the electrolytic solution exceeds 60 ° C., a phenomenon called “burning” tends to occur, and the pores may be broken or the surface may melt and the regularity of the pores may be disturbed.

When sulfuric acid is used as the electrolytic solution, the concentration of sulfuric acid is preferably 0.7 M or less. If the concentration of sulfuric acid exceeds 0.7M, the current value at the time of anodization may become too high to maintain a constant voltage.
Further, by setting the voltage during anodization to 25 to 30 V, it is possible to obtain a mold having anodized alumina formed on the surface with highly regular pores having a pitch of about 63 nm. Regardless of whether the voltage during anodization is higher or lower than this range, the regularity tends to decrease, and the pitch may be larger than the wavelength of visible light.
The temperature of the electrolytic solution is preferably 30 ° C. or less, and more preferably 20 ° C. or less. When the temperature of the electrolytic solution exceeds 30 ° C., a phenomenon called “burning” tends to occur, and the pores may be broken or the surface may melt and the regularity of the pores may be disturbed.

  In the step (a), the oxide film formed by anodizing for a long time becomes thick, and the regularity of the arrangement of the pores can be improved. By doing so, the macro unevenness | corrugation by a crystal grain boundary is suppressed more, and the mold more suitable for manufacture of the articles | goods for optical uses can be obtained. As for the thickness of an oxide film, 1-10 micrometers is more preferable, and 1-3 micrometers is still more preferable. The thickness of the oxide film can be observed with a field emission scanning electron microscope or the like.

Step (b):
After the step (a), the oxide film 42 formed in the step (a) is removed, so that the periodicity corresponding to the bottom (referred to as a barrier layer) of the removed oxide film 42 is obtained as shown in FIG. , That is, a pore generation point 43 is formed.
By removing the formed oxide film 42 once and forming the pore generation points 43 of anodic oxidation, the regularity of the finally formed pores can be improved (for example, Masuda, “Applied Physics”). ", 2000, 69, No. 5, p. 558.).

  Examples of the method for removing the oxide film 42 include a method in which aluminum is not dissolved but a solution that selectively dissolves alumina is used. Examples of such a solution include a chromic acid / phosphoric acid mixed solution.

Step (c):
The aluminum substrate 40 in which the pore generation points 43 are formed is anodized again under a constant voltage in the electrolytic solution, and an oxide film is formed again.
In step (c), anodization may be performed under the same conditions (electrolyte concentration, electrolyte temperature, chemical conversion voltage, etc.) as in step (a).
Thereby, as shown in FIG. 2, the oxide film 45 in which the columnar pores 44 are formed can be formed. Even in the step (c), deeper pores can be obtained as the anodic oxidation is performed for a longer time. However, in the case of manufacturing a mold for manufacturing an optical article such as an antireflection article, here, An oxide film having a thickness of about 0.01 to 0.5 μm may be formed, and it is not necessary to form an oxide film having a thickness enough to be formed in the step (a).

Step (d):
After the step (c), a pore diameter expansion process is performed to expand the diameter of the pores 44 formed in the step (c), and the diameter of the pores 44 is expanded as shown in FIG.
As a specific method of the pore diameter expansion treatment, a method of immersing in a solution dissolving alumina and expanding the diameter of the pores formed in the step (c) by etching can be mentioned. Examples of such a solution include a phosphoric acid aqueous solution of about 5% by mass. The longer the time of step (d), the larger the pore diameter.

Step (e):
As shown in FIG. 2, when anodized again, cylindrical pores 44 having a small diameter and extending downward from the bottom of the cylindrical pores 44 are further formed.
Anodization may be performed under the same conditions as in step (a). Deeper pores can be obtained as the anodic oxidation time is lengthened.

Step (f):
By repeating the step (d) and the step (e) and repeating the step (f), as shown in FIG. 2, the shape of the pore 44 can be changed to a taper shape in which the diameter gradually decreases in the depth direction from the opening, As a result, it is possible to obtain a mold 100 in which anodized alumina having a plurality of periodic pores is formed on the surface. It is preferable that the last end is step (d).

  By appropriately setting the conditions of the step (d) and the step (e), for example, the time for anodization and the time for the pore diameter expansion treatment, various shapes of pores can be formed. Therefore, these conditions may be set as appropriate according to the use of the article to be manufactured from the mold. In addition, when this mold is for manufacturing an antireflection article such as an antireflection film, the pitch and depth of the pores can be arbitrarily changed by appropriately setting the conditions as described above. It is also possible to design a refractive index change.

The mold thus obtained has a fine concavo-convex structure on the surface as a result of the formation of a large number of periodic pores. And when the pitch of the pores in this fine concavo-convex structure is not more than the wavelength of visible light, that is, not more than 400 nm, a so-called moth-eye structure is obtained.
The pitch is a distance from the center of the concave portion (pore) of the fine concavo-convex structure to the center of the concave portion (pore) adjacent thereto.
When the pitch is larger than 400 nm, visible light scattering occurs, so that a sufficient antireflection function is not exhibited, and it is not suitable for manufacturing an antireflection article such as an antireflection film.

When the mold is for producing an antireflection article such as an antireflection film, the pitch of the pores is not more than the wavelength of visible light, and the depth of the pores is preferably 50 nm or more, and 100 nm. More preferably.
The depth is a distance from the opening of the concave portion (pore) of the fine concavo-convex structure to the deepest portion.
If the depth of the pores is 50 nm or more, the reflectance of the surface of the article for optical use formed by the transfer of the mold surface, that is, the transfer surface is lowered.

  The aspect ratio (depth / pitch) of the mold pores is preferably 1.0 to 4.0, preferably 1.3 to 3.5, more preferably 1.8 to 3.5. Most preferred is 0-3.0. When the aspect ratio is 1.0 or more, a transfer surface with low reflectance can be formed, and the incident angle dependency and wavelength dependency thereof are sufficiently reduced. If the aspect ratio is greater than 4.0, the mechanical strength of the transfer surface tends to decrease.

The shape of the mold may be a flat plate or a roll.
The surface on which the fine uneven structure of the mold is formed may be subjected to a release treatment so that the release is easy. Examples of the release treatment method include a method of coating a silicone-based polymer or a fluorine polymer, a method of depositing a fluorine compound, a method of coating a fluorine-based or fluorine-silicone-based silane compound, and the like.

(Inspection process)
With respect to the obtained mold, reflected light from anodized alumina is imaged by the color line CCD camera 12 and the monochrome line CCD camera 22 by the inspection apparatus shown in FIG.

For the anodized alumina image of the mold 100 output from the color line CCD camera 12, the image processing device 30 converts the RGB image signal for each pixel into the HSL color system as necessary, and the color (hue ( H)) information is obtained. With respect to the image of the anodized alumina of the mold 100 output from the monochrome line CCD camera 22, the image processing apparatus 30 obtains luminance information for each pixel.
The quality of the mold 100 is judged from the acquired color information and luminance information, and if it is a good product, the mold 100 is advanced to a manufacturing process of an article having a fine concavo-convex structure on the surface.

(Repair process)
Although it is a defective product, there are no defects such as scratches, and there is only an abnormality in the fine concavo-convex structure of the entire mold (pore depth is deep or shallow overall, pore pitch is generally wide or narrow, etc.) If there is, one of the steps (a) to (f) is performed again on the mold 100 to repair the anodized alumina. If the fine uneven structure is partially abnormal rather than the entire mold, or there is a defect such as a scratch, the anode cannot be repaired only by performing any one of the steps (a) to (f). The steps (a) to (f) may be carried out from the beginning by removing the alumina oxide together with a part of the aluminum substrate. In addition, even if there is an abnormality in the partial fine concavo-convex structure, if the abnormality is a defect in which the pores are filled with foreign matter, the fine concavo-convex structure is repaired by removing the foreign matter by cleaning or the like. Also good. After the mold 100 is repaired, the inspection is performed again, and the repair process and the inspection process are repeated until the mold 100 becomes a good product.

(Function and effect)
In the method for producing a member having an anodized alumina on the surface according to the present invention described above, the method for inspecting the anodized alumina by the anodized alumina inspecting method of the present invention includes the step of inspecting the anodized alumina. A member having an anodized alumina on the surface in which unevenness of the shape of the fine uneven structure and the thickness of the anodized alumina is suppressed and defects on the surface of the anodized alumina are suppressed can be stably manufactured.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

(Mold a)
Purity: A 99.99% aluminum ingot was cut into an outer diameter: 200 mm, an inner diameter: 155 mm, and a length: 350 mm. Electropolishing was performed in a chloric acid / ethanol mixed solution (volume ratio: 1/4) to obtain a mirror surface.

Step (a):
The aluminum substrate was anodized in a 0.3 M oxalic acid aqueous solution for 30 minutes under the conditions of DC: 40 V and temperature: 16 ° C.
Step (b):
The aluminum base material on which the oxide film having a thickness of 3 μm was formed was immersed in a 6% by mass phosphoric acid / 1.8% by mass chromic acid mixed aqueous solution to remove the oxide film.
Step (c):
The aluminum substrate was anodized in a 0.3 M oxalic acid aqueous solution for 30 seconds under the conditions of DC: 40 V and temperature: 16 ° C. At this time, stirring of the oxalic acid aqueous solution was stopped so that the temperature in the oxalic acid aqueous solution was uneven.

Step (d):
The aluminum substrate on which the oxide film was formed was immersed in a 5% by mass phosphoric acid aqueous solution at 30 ° C. for 8 minutes to perform pore diameter expansion treatment.
Step (e):
The aluminum substrate was anodized in a 0.3 M oxalic acid aqueous solution for 30 seconds under the conditions of DC: 40 V and temperature: 16 ° C. At this time, stirring of the oxalic acid aqueous solution was stopped so that the temperature in the oxalic acid aqueous solution was uneven.
Step (f):
The step (d) and the step (e) are repeated four times in total, and finally the step (d) is performed, and anodization having substantially conical pores with an average pitch of 100 nm and a depth of 200 nm in terms of design. A roll-shaped mold a having alumina formed on the surface was obtained.

(Mold b)
In the step (c) and the step (e), the average pitch: 100 nm was obtained in the same manner as in the production of the mold a, except that the oxalic acid aqueous solution was stirred so that the temperature in the oxalic acid aqueous solution was not uneven. A roll-shaped mold b having an anodized alumina having a substantially conical pore with a depth of 200 nm formed on the surface was obtained.

[Experimental Example 1]
Using the inspection apparatus shown in FIG. 1, first, the fine concavo-convex structure of the anodized alumina is inspected by the line illumination device 10 (first irradiation means) and the color line CCD camera 12 (first imaging means). did.
The mold 100 was a mold a.
As the line illumination device 10, a fluorescent light source FL20SS · EX-N / 18 manufactured by Panasonic was used at 40 kHz.
As the color line CCD camera 12, a CV-L107CL-3CCD manufactured by JAI Co. was used.
As the image processing apparatus 30, MIL9 manufactured by Matrox was used.

While changing the angle θ ₁ of the optical axis L ₁ of the color line CCD camera 12 with respect to the normal line N ₁ of the surface (tangent plane) of the anodized alumina of the mold 100 in the imaging range, the color changes while changing between 5 ° and 85 °. The surface of the mold 100 was imaged with the line CCD camera 12.
The distance between the mold 100 and the color line CCD camera 12 was about 50 cm.
The line illumination device 10 was arranged so that the reflected light from the surface of the mold 100 entered the color line CCD camera 12.

FIG. 3 is an image obtained by cutting out a part of an image obtained by imaging one round of the surface of the mold 100 under the condition of the angle θ ₁ = 85 ° of the optical axis L ₁ and converting the color to monochrome.
The abnormal portion 101 of the fine concavo-convex structure of the anodized alumina is imaged black near the center of the image.

It was converted images captured by changing the 10 ° intervals in between the angle theta ₁ of the optical axis L ₁ 5 ° ~85 ° from the RGB image signal in the image processing apparatus 30 to the hue (H) signal. 4 to 12 are graphs in which the hue difference with respect to the normal portion in each pixel of the line 102 including the abnormal portion 101 in FIG. 3 is plotted.
The hue (H) is usually expressed by 0 to 360 °, but in the image processing apparatus 30, 0 to 360 ° is expressed by 8 bit data of 0 to 255. The vertical axis of each graph in FIGS. 4 to 12 is a value obtained by taking the difference from the hue (H) of the abnormal part with the hue (H) of the normal part as a reference. The horizontal axis is a pixel.

For example, when the threshold is set to a hue difference of 1.0 or more, an abnormal portion cannot be detected at an angle θ ₁ = 5 ° to 35 ° of the optical axis L _{1 in} FIGS. Can detect the angle theta _{1 =} abnormal portion from 45 ° of the optical axis L _1, as the angle theta ₁ of the optical axis L ₁ is further increased, the detection sensitivity is increased.

Was converted images captured by changing the 5 ° intervals in between the angle theta ₁ of the optical axis L ₁ 5 ° to 85 ° from the RGB image signal in the image processing apparatus 30 to the hue (H) signal. FIG. 13 shows a plot of the maximum value of the hue difference between the normal part and the abnormal part in each image.
Than in the optical axis L ₁ angle theta of _{1 =} 65 ° in 45 ° it can be detected with high sensitivity for a large hue difference of the normal portion and an abnormal portion, an angle theta _{1 =} 80 further detection sensitivity in ° of the optical axis L ₁ is It becomes higher and can be detected with higher sensitivity at an angle θ ₁ = 85 ° of the optical axis L ₁ .

From the results of Experimental Example 1, the angle θ ₁ of the optical axis L ₁ of the color line CCD camera 12 with respect to the normal line N ₁ of the surface (tangent plane) of the anodized alumina of the mold 100 in the imaging range is preferably 45 ° or more. 65 ° or more is more preferable, 80 ° or more is further preferable, and 85 ° or more is particularly preferable.

[Example 1]
The inspection apparatus shown in FIG. 1 was used to inspect the scratches and foreign matter together with the inspection of the fine concavo-convex structure of the anodized alumina of the mold by the above-described inspection method.
The mold 100 was produced in the same procedure as the mold a.
The line illumination device 10 and the color line CCD camera 12 are the same as in Experimental Example 1.
As the line illumination device 20, LB-LS300 / 10WH manufactured by VS Technology Co., Ltd. was used.
As the monochrome line CCD camera 22, TI5150DCL manufactured by Excel was used.

The color line CCD camera 12 serving as the first image pickup means has an optical axis L ₁ of the color line CCD camera 12 with respect to the normal line N ₁ of the surface (tangent plane) of the anodized alumina of the mold 100 in the image pickup range. It arrange | positioned so that angle (theta) ₁ might be 80 degrees.
The distance between the mold 100 and the color line CCD camera 12 was about 50 cm.
The line illumination device 10 as the first irradiation means was arranged so that the reflected light from the surface of the mold 100 entered the color line CCD camera 12.

The monochrome line CCD camera 22 which is the second imaging means has an optical axis L ₂ of the monochrome line CCD camera 22 with respect to the normal N ₂ of the surface (tangent plane) of the anodized alumina of the mold 100 in the imaging range. It arrange | positioned so that angle (theta) ₂ might be 10 degrees.
The distance between the mold 100 and the monochrome line CCD camera 22 was about 50 cm.
The second irradiation means linear illumination device 20 is, with respect to the normal line N ₃ of the surface (tangent plane) of the anodized alumina mold 100 in the imaging range, the linear illumination device 20 of the optical axis L ₃ It arrange | positioned so that angle (theta) ₃ might be 45 degrees.

  In Example 1, since the length of the mold 100 is within the imaging range of the first and second imaging units, the first imaging unit, the first irradiation unit, the second imaging unit, and the second irradiation unit. The moving means for translating the means is omitted.

FIG. 14 shows an image obtained by cutting out a part of an image obtained by imaging the entire surface of the mold 100 using the first irradiation unit and the first imaging unit, and converting the color into monochrome.
The anomalous part 210 of the fine concavo-convex structure of anodized alumina is imaged whiter than the normal part at the upper center of the image.

FIG. 15 shows a part of a monochrome image obtained by imaging one turn of the surface of the mold 100 using the second irradiation unit and the second imaging unit, and the cut-out position is the same as FIG. is there.
The defects 211, 212, and 213 on the surface of the mold 100 are imaged as white bright spots.

Since the defects 211 and 213 are linear, it can be determined from the image that they are scratch defects.
If the abnormal portion 210 of the fine concavo-convex structure of anodized alumina exists alone, it is considered that the abnormal portion 210 occurred during the anodizing step.
In addition, when the defect 212 exists alone, it is considered that the defect 212 is generated by scratches or foreign matters other than the anodizing step.

Here, the defect 212 is located almost at the center of the abnormal portion 210 of the fine concavo-convex structure of the anodized alumina, and a liquid material such as fat spreads around the defect 212 to fill the pores, so that the fineness of the anodized alumina is fine. It seems reasonable to assume that the abnormal part 210 of the uneven structure was caused.
Therefore, the defect 212 was generated not because of the adhering foreign substances in the post process but in the anodization process, and it was possible to feed back that the clean process in the post process was important.
Incidentally, when the defect 212 was enlarged and observed, the adhesion of foreign matters could be visually recognized.

  An inspection apparatus and an inspection method for an anodized alumina according to the present invention are used to manufacture a mold for forming an anodized alumina having a fine concavo-convex structure whose pitch is equal to or less than the wavelength of visible light by anodizing the surface of an aluminum substrate. Useful.

10 Line illumination device (first irradiation means)
12 Color line CCD camera (first imaging means)
20 Line illumination device (second irradiation means)
22 Monochrome line CCD camera (second imaging means)
30 Image processing device (image processing means)
40 Aluminum base 45 Oxide film (anodized alumina)
100 Mold (member)

Claims (13)

An irradiation means for irradiating light to the anodized alumina;
Imaging means for imaging light emitted from the irradiation means and reflected by the anodized alumina;
An anodized alumina inspection apparatus comprising: image processing means for determining the quality of an anodized alumina based on color information and luminance information obtained from an image captured by an imaging means. As said irradiation means, it has a first irradiation means and a second irradiation means,
As the imaging means, a first imaging means for imaging the light irradiated from the first irradiation means and reflected by the anodized alumina, and an image of the light irradiated from the second irradiation means and reflected by the anodized alumina. A second imaging means,
The image processing means is picked up by the first image pickup means and the first image pickup means based on the color information obtained from the image picked up by the first image pickup means and the second image pickup means. 2. The anodized alumina inspection apparatus according to claim 1, further comprising: a second determination unit configured to determine whether the state of the anodized alumina is good based on luminance information obtained from the obtained image.   The said 1st imaging means is arrange | positioned so that the angle of the optical axis of a 1st imaging means may be 45-89.9 degrees with respect to the normal line of the surface of anodized alumina. Anodized alumina inspection equipment.   The said 2nd imaging means is arrange | positioned so that the angle of the optical axis of a 2nd imaging means may be 0-70 degrees with respect to the normal line of the surface of anodized alumina. Anodized alumina inspection equipment. The first imaging means outputs an RGB image signal as the color information;
5. The anodized alumina inspection apparatus according to claim 1, wherein the first determination unit determines whether the state of the anodized alumina is good based on RGB image signals. The first imaging means outputs an RGB image signal as the color information;
The image processing means includes a conversion unit that converts RGB image signals into HSL color system information,
The anodized alumina inspection according to any one of claims 1 to 4, wherein the first determination unit is configured to determine the quality of the anodized alumina state based on information of the HSL color system. apparatus. Irradiate light to the anodized alumina from the irradiation means,
The light irradiated from the irradiation means and reflected by the anodized alumina is imaged by the imaging means,
An anodized alumina inspection method for determining whether or not the state of an anodized alumina is good based on color information and luminance information obtained from an image captured by an imaging unit. Irradiate light from the first irradiation means to the anodized alumina,
The first imaging means images the light irradiated from the first irradiation means and reflected by the anodized alumina,
Based on the color information obtained from the image picked up by the first image pickup means, determine the quality of the anodized alumina state,
Irradiate light from the second irradiation means to the anodized alumina,
The second imaging means images the light irradiated from the second irradiation means and reflected by the anodized alumina,
The anodized alumina inspection method according to claim 7, wherein the quality of the state of the anodized alumina is determined based on luminance information obtained from an image captured by the second imaging unit.   The first imaging unit is disposed so that an angle of an optical axis of the first imaging unit is 45 to 89.9 ° with respect to a normal line of the surface of the anodized alumina. Inspection method for anodized alumina.   The second image pickup unit is arranged so that an angle of an optical axis of the second image pickup unit is 0 to 70 ° with respect to a normal line of the surface of the anodized alumina. Inspection method for anodized alumina. Obtaining an RGB image signal as color information from the image captured by the first imaging means,
The anodized alumina inspection method according to any one of claims 7 to 10, wherein the quality of the state of the anodized alumina is determined based on the RGB image signals. Obtaining an RGB image signal as color information from the image captured by the first imaging means,
Converting the RGB image signal into HSL color system information;
The method for inspecting anodized alumina according to any one of claims 7 to 10, wherein the quality of the state of the anodized alumina is determined based on information on the HSL color system. A step of anodizing the surface of the aluminum substrate to obtain a member having anodized alumina on the surface;
A method for producing a member having an anodized alumina on a surface thereof, comprising: a step of inspecting the anodized alumina by the anodized alumina inspecting method according to any one of claims 7 to 12.