JP2016001153A - Apparatus and method for inspecting optical component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for inspecting an optical component that can quickly and accurately detect abnormality of an optical component.SOLUTION: An apparatus for inspecting an optical component includes an imaging part that has an abnormality detection part configured to detect abnormality to be detected with a plurality of pixels of an image pickup device, and photographs an inspection target area in every movement on a focal surface in a predetermined amount in the optical axial direction, records the maximum luminance value in an area of the abnormality detected by the abnormality detection part, and detects the position in the optical axial direction of an inspection target object with abnormality, from the position of the focal surface with the largest maximum luminance value in a corresponding area of the abnormality, from among inspection target areas photographed within a predetermined area.

Description

  The present invention relates to an inspection apparatus for inspecting an abnormality of an optical component such as a lens and an inspection method thereof.

  A mobile terminal such as a mobile phone or a smartphone is provided with a camera. Such a camera includes a lens unit in which a plurality of lenses are arranged in the optical axis direction. When there is a defect such as a scratch or deformation, or a foreign matter such as dust or dust (hereinafter collectively referred to as an abnormality), the optical performance of the lens unit is degraded, and the performance of the camera is also degraded. Therefore, an appearance inspection apparatus inspects whether there is an abnormality in the lens unit.

  The appearance inspection apparatus captures an image of the lens unit with an image capturing unit including a solid-state image sensor and an objective lens, and detects an abnormality based on the captured image. In some of the appearance inspection apparatuses, a lens having a deep depth of field is used as the objective lens, and the entire optical axis direction of the lens unit can be inspected by one photographing.

  In the lens unit, foreign matter on the surface on the image sensor side may fall and adhere to the image sensor. On the other hand, foreign matters other than the surface on the image sensor side do not fall and adhere to the image sensor. Therefore, inspection standards for abnormalities on the surface of the lens unit on the image sensor side are often set to be stricter than inspection standards for other positions. For example, in the inspection of the lens unit, the size of the abnormality on the surface on the image sensor side that is determined as a defective product is different from the abnormality on the other position, and the abnormality on the other position is larger than the abnormality on the surface. Is acceptable.

  In the appearance inspection apparatus, since inspection is performed by one photographing, it is difficult to detect where the abnormality is in the optical axis direction of the lens unit. Therefore, the most rigorous image sensor side surface inspection standard is used to detect abnormalities, and when abnormalities are detected, it is possible to determine which part the abnormality is occurring by re-inspection by the operator's visual inspection. It is re-inspected whether the abnormality is within the allowable range in the portion where the error occurs. In the case of performing inspection by such a method, since inspection is performed according to the strictest inspection standard, there is a high possibility that it will be a non-defective product by re-inspection. For this reason, the number of lens units that are defective in the appearance inspection apparatus increases, and the number of visual re-inspections also increases.

  Therefore, in the defect shape and position measuring method described in Japanese Patent Application Laid-Open No. 2007-163315, the camera is arranged so that the focal plane of the camera is parallel to the XY plane on the Z-axis extension line of the lens. The camera is operated in the Z direction by the mechanism. Thereby, the focal plane is changed in the Z direction, and the lens is inspected by changing the relative XY positions of the camera and the lens at each Z direction position, and inspecting the lens. . The illumination light is irradiated from the opposite side of the lens camera, and if there is an abnormality, it is taken as a low-contrast part. I know.

JP 2007-163315 A

  However, in the invention described in Japanese Patent Application Laid-Open No. 2007-163315, the position of the defect in the Z direction is set as the position of the movable mechanism when the defect is detected, and the error of the movable mechanism and the depth of field of the lens are reduced. An error corresponding to the combined depth occurs. For example, when a plurality of lenses of a lens unit are thin and are arranged close to each other, the method disclosed in Japanese Patent Application Laid-Open No. 2007-163315 cannot accurately determine the position of a defect (for example, whether it is internal or surface). There is a case.

  Therefore, an object of the present invention is to provide an optical component inspection apparatus capable of accurately detecting an abnormal position of an optical component in the optical axis direction.

  In order to achieve the above object, the present invention provides an imaging unit having an imaging device that acquires a captured image of a region to be inspected of an inspection object, and a drive unit that moves a focal plane of the imaging unit in a predetermined range in the optical axis direction. And an illuminating unit that irradiates illumination light to the region to be inspected, and an abnormality detecting unit that detects, as an abnormality, a portion having a luminance difference that can be recognized as an image in a field of view in the captured image. An abnormality to be detected by the abnormality detection unit is configured to be detected by a plurality of pixels of the image sensor, and the abnormality detection unit detects the region to be inspected every time a predetermined amount moves. The maximum luminance value in the abnormal region is recorded, and the abnormal light of the inspection object is detected from the position of the focal plane where the maximum luminance value in the corresponding abnormal region is maximum. Optical component inspection device that detects axial position To provide.

  In the above configuration, the imaging unit includes an imaging element that acquires a captured image and a lens that forms a captured image on the imaging element, and the depth of field of the lens is the thickness of the inspection object. It may be shallower than that.

  In the above configuration, the imaging magnification of the lens may image an abnormality to be detected by the abnormality detection unit larger than a shape in which pixels of the image sensor are arranged in 2 × 2. According to this configuration, since the abnormality occupies the whole of at least one pixel, it is possible to accurately detect the maximum luminance value.

  The said structure WHEREIN: The said predetermined amount may be below the said lens depth of field.

  In the above configuration, when the abnormality detection unit arranges the maximum luminance value for each position of the focal plane, a position that is an inflection point of the maximum luminance value is set in the optical axis direction of the inspection object of the abnormality. The position may be determined.

  In the above configuration, the illumination unit is arranged to irradiate the inspection object with illumination light so that the imaging unit can capture images with uniform brightness, and the abnormality detection unit is within the field of view of the captured image. A portion having a luminance difference that can be recognized as an image may be determined to be abnormal.

In the above configuration, the abnormality detection unit records the lowest luminance value in the region of the abnormality detected by the abnormality detection unit, and arranges the lowest luminance value for each position of the focal plane. The position of the inflection point may be determined as the position of the abnormal inspection target in the optical axis direction.

  ADVANTAGE OF THE INVENTION According to this invention, the inspection apparatus of the optical component which can detect the position of the optical axis direction of the abnormality of an optical component correctly can be provided.

1 is a schematic arrangement view of an example of an optical component inspection apparatus according to the present invention. It is a block diagram of the inspection apparatus of the optical component shown in FIG. It is the schematic of the imaging part used for the inspection apparatus of the optical component shown in FIG. It is the figure which showed typically the image pick-up element used for an imaging part. It is a figure which shows an example of the state by which abnormality was imaged. It is a figure which shows the other example of the state by which abnormality was imaged. It is a flowchart which shows the test | inspection operation | movement of the inspection apparatus of the optical component concerning this invention. It is a graph which shows the relationship between the maximum luminance value of an abnormal image, and a focus position. It is a flowchart which shows operation | movement of the inspection apparatus of the optical component concerning this embodiment.

  An optical component inspection apparatus according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic layout view of an example of an optical component inspection apparatus according to the present invention, and FIG. 2 is a block diagram of the optical component inspection apparatus shown in FIG. The inspection apparatus A is an apparatus for inspecting the lens unit Lt for scratches and foreign objects, using a lens unit Lt used in a camera provided in a mobile phone or the like as an inspection object. As shown in FIGS. 1 and 2, the inspection apparatus A includes a housing 1, an imaging unit 2, a drive unit 3, an illumination unit 4, an abnormality detection unit 5, a control unit 6, and a storage unit 7. I have.

  As shown in FIG. 1, the housing 1 includes a rectangular parallelepiped base 10, a support column 11 protruding from the base 10, and an inspection stage 12 attached to the support column 11. A level adjusting unit (not shown) is provided on the bottom surface of the base 10 so that the base 10 (the upper surface thereof) can be adjusted to be horizontal.

  The support 11 is erected vertically from the upper surface of the base 10. Therefore, the support | pillar 11 becomes vertical by adjusting so that the upper surface of the base 10 may become horizontal. The support 11 includes an inspection stage 12 for holding the lens unit Lt and an illumination holding unit 111 for holding the illumination unit 4. Further, the support 11 is provided with a drive unit 3 that moves the imaging unit 2 toward / separates in the optical axis direction, that is, toward the lens unit Lt.

  The inspection stage 12 is a holding base for holding the lens unit Lt when inspecting the lens unit Lt that is an inspection object. The inspection stage 12 is fixed to the support 11. The inspection stage 12 is fixed to the support 11 so as to be parallel to the base 10, and the inspection stage 2 can be made horizontal by arranging it so as to be parallel to the base 10. Although not shown, the inspection stage 2 includes a holding unit that can hold / release the inspection target (lens unit Lt).

  The holding part may be one that holds and holds the side of the inspection object using a spring or the like, or holds the inspection object on the inspection stage 2 by sucking air. May be. Further, the inspection object may be directly held, or the inspection object attached to the optical device or jig on which the inspection object is assembled may be held.

  The drive unit 3 is firmly fixed to the column 11 and supports the imaging unit 2 so as to be slidable along the column. The drive unit 3 is connected to the control unit 6 and moves the imaging unit 2 closer to or away from the lens unit Lt on the inspection stage 12 in accordance with an instruction from the control unit 6, so that the imaging unit 2 and the lens unit Lt are connected. Adjust the relative position so that it is the optimal position for inspection. When inspection is performed (when imaging is performed), the image is fixed by a fixing mechanism, the relative position is prevented from shifting, and the decrease in imaging accuracy is suppressed.

  In addition, in this embodiment, although the drive part 3 shall be firmly fixed to the support | pillar 11, it is not limited to this. For example, the imaging unit 2 may be firmly fixed by the driving unit 3, and the driving unit 3 may be slidable with respect to the support column 11 together with the imaging unit 2.

  Moreover, although the drive part 3 is set as the structure which slides the imaging part 2, the relative position of the imaging part 2 and the lens unit Lt should just change, and the test | inspection stage 12 may approach / separate. Further, both the imaging unit 2 and the inspection stage 12 may be moved.

  The illumination unit 4 is arranged so that the inspected part is imaged with uniform brightness when the imaging unit 2 images the lens unit Lt. As shown in FIG. 1, the illumination unit 4 includes an annular stay 40 that irradiates illumination light toward the lens unit Lt from the lower surface. The stay 40 is held by the illumination holding unit 111.

  The illumination unit 4 has a plurality of LEDs (not shown) arranged side by side so as to irradiate the lens unit Lt with illumination light from the annular stay 40. And the light-diffusion member which diffuses and makes uniform the light of LED is also provided. The illumination unit 4 is connected to the control unit 6 and irradiates the lens unit Lt with illumination light in accordance with an instruction from the control unit 6.

  In addition, the structure of the illumination part 4 is not limited to this. For example, as the light source, in addition to the LED, a light emitting element by a discharge, a laser light emitting element, or the like may be used. Moreover, the structure which utilizes indirect illumination may be sufficient. A lighting unit having a structure in which the captured image of the lens unit has uniform luminance can be widely used.

  As shown in FIG. 1, the imaging unit 2 captures a lens unit Lt that is an object to be inspected through a through hole in a central portion of an annular stay 40. In the optical component inspection apparatus A, the center of the ring of the stay 40 is arranged so as to overlap the optical axis of the lens unit Lt and the imaging unit 2.

  The abnormality detection unit 5 is a circuit for determining whether or not there is an abnormality in the captured image of the inspection area of the lens unit Lt acquired (captured) by the imaging unit 2. As described above, since the imaging unit 2 is configured to capture the inspected area with uniform luminance, the abnormal image has a luminance of other parts (non-abnormal part) in the captured image. A difference appears. Therefore, the abnormality detection unit 5 detects a portion where a difference in luminance of the captured image appears as an abnormality.

  More specifically, when the imaging unit 2 captures an image so that the observation range (inspected region) has uniform brightness, if there is a thing / structure that scatters light within the observation range, that portion Is recognized as an image brighter than the surrounding luminance by scattered light. Also, if there is a thing / structure that absorbs light in the observation range, that portion is recognized as an image darker than the surrounding luminance.

  For example, it is assumed that the brightness of the captured image is represented by gradations (0 to 255). At this time, if there is a portion (bright portion) with the luminance level 150 to 200 within the observation range of the luminance level 100 to 110, the abnormality detection unit 5 recognizes the portion with the luminance level 150 to 200 as a bright image. To do. This bright part differs depending on how the illumination light is applied and the scattering object / structure, but the abnormality detection unit 5 recognizes an image (bright image) if there is a difference of +5 or more with respect to the surrounding luminance level. Can do.

  If there is a portion with a luminance level of 30-50 within the observation range of the luminance level 100-110 uniformly, the abnormality detection unit 5 recognizes the portion with the luminance level of 30-50 as a dark image. This dark portion also differs depending on how the illumination light is applied and the absorbing object / structure. A dark image). Here, if the luminance level changes slowly and the level cannot be recognized as an image, it is assumed to be uniform. For example, in a background with an average luminance level of 100, when the luminance level continuously changes within ± 4, it can be made uniform.

  The control unit 6 is a circuit that controls the optical component inspection apparatus A. The control unit 6 is a circuit including an arithmetic processing unit such as an MPU or a CPU, and has a configuration capable of performing a plurality of processes. Moreover, you may have the structure which performs a process by operating a processing program as needed.

  The storage unit 7 is connected to the control unit 6. The storage unit 7 includes a semiconductor memory such as a ROM, a RAM, and a flash memory, and a physical storage device such as a hard disk and an optical disk. The storage unit 7 stores various data processed by the control unit 6 and video data such as the projected video Pi. The storage unit 7 stores information on the position of the abnormality detected by the abnormality detection unit 5 and the position of the drive unit 3 (imaging unit 2) at that time (details will be described later). Information on the presence / absence of an abnormality and the position of the abnormality is acquired from the abnormality detection unit 5, and the position of the driving unit 3 at that time is acquired from the control unit 6.

  Next, details of the imaging unit 2 will be described with reference to a new drawing. FIG. 3 is a schematic diagram of an imaging unit used in the optical component inspection apparatus shown in FIG. As shown in FIG. 3, in this embodiment, the lens unit Lt, which is an object to be inspected, has a configuration in which two lenses Ls1 and Ls2 are arranged in the optical axis direction and held by a housing Hg. Further, in the lens unit Lt shown in FIG. 3, the abnormality Nt1 exists on the upper surface of the upper lens Ls1 (outside the lens unit Lt), and the abnormality Nt2 exists on the surface I of the lens Ls2 (inside the lens unit Lt). Yes.

  As illustrated in FIG. 3, the imaging unit 2 is a device that photographs the lens unit Lt. As shown in FIG. 3, the imaging unit 2 includes an imaging element 21 such as a CCD or a CMOS, and an imaging lens 22 that forms an image on the imaging element 21.

  In the optical component inspection apparatus A, an abnormality of the inspection area is inspected using the opening portion Op (effective range) of the lens unit Lt as the inspection area. In the imaging unit 2, the entire inspection area is set as a subject, and the image of the inspection area is fixed so that the image of the inspection area falls within a predetermined range of the imaging element 21 and at that time in focus. That is, in the imaging unit 2, the distance from the focusing position (focus position P1) to the imaging lens is fixed.

  Details of the imaging unit 2 will be described with reference to a new drawing. FIG. 4 is a diagram schematically illustrating an image sensor used in the imaging unit. As shown in FIG. 4, the image sensor 21 has a plurality of light receiving sensors 211 arranged two-dimensionally. The light receiving sensor 211 converts incident light into an electrical signal, and the light receiving sensor 211 serves as a pixel of a captured image. The amount of light received by the sensor in each area is quantified as a gradation (here, 0 to 255).

  That is, the intensity (brightness) of the light of the image formed on the image sensor 21 by the imaging lens 22 is digitized through each light receiving sensor 211 and the information detected by all the light receiving sensors 211 is collected as an image. Data (captured image). This image data is sent to the abnormality detection unit 5.

  For example, as shown in FIG. 4, if there is an abnormality Nt1 in the lens unit Lt, an image Pt1 of an abnormality is scattered on the light emitted from the illumination unit 4 of the optical component inspection apparatus A of the present embodiment and is imaged on the imaging device 21. Forms an image. Since the optical component inspection apparatus A of the present embodiment is configured to capture the lens unit Lt as an image having a uniform luminance, the abnormal image Pt1 appears as a bright (high luminance) image in the captured image. That is, the same gradation (for example, 40) is digitized in the light receiving sensor 211 other than the abnormal image Pt1 being formed. On the other hand, in the light receiving sensor 211 in the portion where the abnormal image Pt1 is formed, the gradation is digitized to a gradation different from 40 (for example, 30, 50, etc.).

  A method for detecting an abnormality will be further described. FIG. 5A is a diagram illustrating an example of a state where an abnormality is imaged, and FIG. 5B is a diagram illustrating another example of a state where an abnormality is imaged. In FIGS. 5A and 5B, hatching is applied to clarify the portion of the abnormal image Pt.

  When the abnormal image Pt1 is detected by the image sensor 21, even if the size of the abnormal image Pt1 formed on the image sensor 21 is the same, the detection result of the light receiving sensor 211 differs depending on the position where the image is formed. May appear. For example, the abnormal images Pt11 and Pt12 shown in FIGS. 5A and 5B are both 2 × 2 pixel rectangles. The abnormal image Pt11 shown in FIG. 5A is formed so that all the edges of the four sides overlap with the boundary of the light receiving sensor 211, and the abnormal image Pt12 shown in FIG. The image is formed so as to pass through the central portion of the region.

  An abnormal image Pt11 shown in FIG. 5A is formed on the four light receiving sensors 211a to 211d. Assuming that the abnormal image Pt11 has uniform brightness (here, gradation 200), each of the pixels corresponding to the light receiving sensors 211a to 211d has gradation 200.

  And in the captured image sent to the abnormality detection part 5 from the image pick-up element 21, the gradation of the pixel corresponding to each of the four light reception sensors 211a-211d differs from the surrounding gradation. Therefore, the abnormality detection unit 5 recognizes that an abnormal image Pt11 having a size of 2 × 2 pixels corresponding to the light receiving sensors 211a to 211d is detected. The detection of the luminance of the abnormal image Pt11 from the captured image may be recognized by the value of the sum of the detected gradations. In this case, there are cases where large gradation data is detected for a small number of pixels and when small gradation data is detected for a large number of pixels. Therefore, in order to consider the size of the abnormal image, an average value obtained by dividing the total sum of gradations by the number of pixels is used. In the captured image in which the abnormal image Pt11 illustrated in FIG. 5A is captured, the gradation value is 200 with four pixels, so the average value is also the gradation 200.

  On the other hand, the abnormal image Pt12 shown in FIG. 5B is formed on the nine light receiving sensors 211a to 211i. When the abnormal image Pt1 is thus formed, the light receiving sensors 211a to 211i detect the image (gradation). Assuming that the gradation of the abnormal image Pt12 is the same as that in FIG. 5A, in the light receiving sensors 211a, 211e, 211g, and 211i where the four corners of the abnormal image Pt12 are formed, an image is formed on a quarter of the whole. Therefore, the digitized data of gradation 50 is detected. Similarly, in the light receiving sensors 211b, 211c, 211f, and 211h in which the center part of the four sides of the abnormal image Pt12 is formed, the image is formed in a half part of the whole, and therefore, the digitized data of gradation 100 Is detected. In the light receiving sensor 211d on which the center portion of the abnormal image Pt12 is formed, an image is formed on the entire surface, so that the gradation is 200.

  And in the captured image sent to the abnormality detection part 5 from the image pick-up element 21, a gradation differs with the surrounding gradation in the pixel corresponding to each of nine light reception sensors 211a-211i. Therefore, the abnormality detection unit 5 recognizes that an abnormality in the size of 3 × 3 pixels corresponding to the light receiving sensors 211a to 211i has been detected. Since the sum of gradations of each pixel is 800 and the number of pixels is 9, the average value is 89.9.

  As described above, even when an abnormal image having the same size and brightness is formed on the image sensor 21, the size of the abnormal image detected by the abnormality detection unit 5 is determined by the relative positional relationship with the light receiving sensor 211 that forms the image. In addition, the luminance changes greatly.

  Accordingly, when the abnormality detection unit 5 detects an abnormal image of the captured image sent from the imaging unit 2, the abnormality detection unit 5 acquires the luminance (gradation) of the pixel corresponding to the abnormal image. Then, the maximum value of the luminance (gradation) of the pixel corresponding to the acquired abnormal image is set as the maximum luminance value, and the luminance value is representative of the luminance of the abnormal image.

  For example, in the abnormal image Pt11 shown in FIG. 5A, since the gradation is 200 for all the pixels, the maximum luminance value of the abnormal image is the gradation 200. On the other hand, also in the abnormal image Pt12 shown in FIG. 5B, the maximum luminance value for detecting the abnormal image Pt12 is the same value as 200 of 211d that occupies all the abnormal images.

  By acquiring the maximum luminance (gradation) among the pixels corresponding to the abnormal image, it is possible to accurately acquire the luminance for evaluating the abnormal position regardless of the position of the abnormal image and the light receiving sensor. Is possible.

  In order for the abnormality detection unit 5 to accurately detect the maximum luminance value, it is preferable that at least one of the light receiving sensors on which an abnormal image is formed can detect the abnormal image on the entire light receiving surface. Therefore, in the lens unit Lt, it is determined whether or not it is a defective product due to the size of the abnormality, and the abnormal image determined to be a defective product is a shape in which the light receiving sensors 211 are arranged in 2 × 2. Is preferably larger.

  In addition, in the lens unit Lt that is an inspection object, when a defect of a certain size or more, such as a foreign matter, exists in the lens that constitutes the lens unit Lt, the lens unit Lt is handled as a defective product. In the optical component detection apparatus A, the imaging unit 2 images the opening portion Op of the lens unit Lt, and the abnormality detection unit 5 detects whether there is an abnormality.

  The imaging unit 2 has a fixed distance to the focus position P1, and the size (magnification) of the image formed on the imaging device 21 is the size of the abnormality to be detected, the imaging lens 21 and the imaging device. It is determined by 22 positions (distances). Therefore, when there is an abnormality in the size that the imaging unit 2 determines to be a defective product within the focus position P1 or the depth of field, the imaging unit 2 is larger than the shape in which the light receiving sensors 211 are arranged in 2 × 2 on the imaging element 21. The configurations of the imaging lens 21 and the image sensor 22 are determined so as to form an image.

  Next, the operation of the optical component inspection apparatus according to the present invention will be described with reference to the drawings. FIG. 6 is a flowchart showing the inspection operation of the optical component inspection apparatus according to the present invention, and FIG. 7 is a graph showing the relationship between the maximum luminance value of the abnormal image and the focus position (focal plane position). The operation of the optical component inspection apparatus will be described with reference to FIG.

  As shown in FIG. 3, the lens unit Lt has a configuration in which a plurality of lenses Ls1 and Ls2 are arranged in the optical axis direction. For example, it is assumed that the surfaces of the lens Ls1 and the lens Ls2 are abnormal. .

  The control unit 6 determines that the focus position P1 of the imaging unit 2 is a reference position a0 that is in front of the foremost part of the lens unit Lt (step S101). Then, the control unit 6 sends an instruction to the drive unit 3, and moves the imaging unit 2 so that the focus position P1 overlaps the reference position a0 (step S102). The reference position a0 may be the upper surface of the lens Ls1 close to the imaging unit 2, but this position may be behind the other parts of the lens Ls1 depending on the shape of the lens unit Lt. .

  The control unit 6 sends an instruction to the imaging unit 2, and images the opening portion Op of the lens unit Lt as an inspection area (step S103). Then, the captured image is sent from the imaging unit 2 to the abnormality detection unit 5, and the abnormality detection unit 5 detects an abnormality that appears in the captured image (step S104). The abnormality detection by the abnormality detection unit 5 is as described above, and an image that extends over a plurality of pixels and has a higher luminance (higher gradation) than other parts is detected as abnormal.

  The control unit 6 determines whether or not the abnormality detection unit 5 has detected an abnormality (step S105). When the abnormality detection unit 5 detects an abnormality (Yes in step S105), the control unit 6 acquires information on the maximum luminance value from the abnormality detection unit 5 (step S106), and the current focus position on the image sensor 21. And the maximum luminance value are stored in the storage unit 7 in association with each other (step S107). Note that the current focus position can be detected based on the position of the imaging unit 2.

  If it is determined that there is no abnormality at the current focus position (No in step S105), whether or not the current focus position is the position farthest from the reference position in the range to be inspected (position a6 in FIG. 3). (Step S108). If the current focus position is not the farthest position (No in step S108), the control unit 6 sends an instruction to the drive unit 3 to move the imaging unit 2 (return to step S102). Note that when the imaging unit 2 is moved, the driving unit 3 is moved by a predetermined amount. In FIG. 3, the drive unit 3 moves to the next position by moving the imaging unit 2 by a predetermined amount. For example, if the current focus position P1 is the reference position a0, the imaging unit 2 is moved to a position a1 by moving a predetermined amount.

  When the current focus position P1 is the farthest position (here, a6) (Yes in step S108), the control unit 6 checks whether the maximum luminance value is stored in the storage unit 7 (step S109). . By checking whether or not the maximum luminance value is stored, it can be determined whether or not there is an abnormality in the lens unit Lt. When the maximum luminance value is not stored (No in step S109), the control unit 6 determines that there is no abnormality in the lens unit Lt (step S110).

  In the optical component inspection apparatus A, the focus position P1 of the imaging unit 2 is moved, and the maximum luminance value is detected at the movement position (reference position a0 to position a6). At the position where the abnormality is overlapped with the focus position P1 or at the position within the depth of field, the state where the abnormality is most focused is achieved, so the maximum luminance value is maximized. On the contrary, when the abnormality is out of focus position P1 and the depth of field, the image of the abnormality in the captured image is not in focus, and the maximum luminance value also decreases.

  For example, as shown in FIG. 3, it is assumed that the abnormality Nt2 is located on the inner surface (position a4) of the lens Ls2 on the surface (position a1) of the lens Ls1 of the lens unit Lt. At this time, the relationship between the maximum luminance value and the position of the focus position P1 is shown in FIG. FIG. 7 is a graph in which the horizontal axis represents the distance from the reference position of the focus position P1, and the vertical axis represents the maximum luminance value. The positions a0 to a6 indicate the focus position P1 at the time of imaging, but actually, the reference position a0 is set to 0 and the physical distance from the reference position a0 is used.

  At this time, when the focus position P1 of the imaging unit 2 is moved, the maximum luminance value of the image of the abnormality Nt1 is plotted with a diamond shape, and the maximum luminance value of the image of the abnormality Nt2 is plotted with a circle. Looking at the graph of FIG. 7, the plot of the abnormality Nt1 is an inflection point (maximum value) at the position a1. Similarly, the plot of the abnormality Nt2 is an inflection point (maximum value) at the position a4. The maximum luminance value is maximized when the focus position P1 overlaps with an abnormal position.

  Using this, when the maximum luminance value is stored (Yes in step S109), the control unit 6 compares the maximum luminance value stored in the storage unit 7 and detects the maximum value. Then, it is determined that the position is abnormal (step S111).

  The optical component inspection apparatus A according to the present invention confirms the position in the thickness direction of the abnormal optical component in the procedure as described above. Thereby, it is possible to accurately detect whether or not there is an abnormality in the optical component, and if there is an abnormality, where in the thickness direction it is.

  Then, after inspecting the optical component, the optical component inspection apparatus A notifies whether or not there is an abnormality in the inspected lens unit Lt, and if there is an abnormality, in which part the abnormality is present. May be provided. Further, the abnormality at the position where it is determined that there is an abnormality in the lens unit Lt is confirmed again, and information on the position and size of the abnormality is detected and presented (for example, displayed on a display unit (not shown)). May be.

  By doing in this way, it is possible to acquire reliably and correctly the position of the abnormality, whether or not there is an abnormality in the lens unit Lt (optical component). In addition, in the lens unit Lt, the magnitude of an abnormality that is allowed at an abnormal position may be different.

  Therefore, the optical component inspection apparatus A inspects the lens unit Lt, and when an inspection result indicating that there is an abnormality is obtained, the focus position is again superimposed on the position where the abnormality is present, and the magnitude of the abnormality is detected. It is also possible to confirm whether or not the abnormality is acceptable. By doing in this way, it is possible to determine that the lens unit Lt that has a certain size or more but includes an abnormality permitted by the position is a conforming product. Thereby, a non-defective product can be determined as a defective product, and the occurrence of a lens unit Lt that is determined to be a non-defective product that is within the allowable range by re-inspection by an inspector's visual inspection or the like can be suppressed.

  In the present embodiment, the driving unit 3 repeats moving and imaging the imaging unit 2 with a predetermined movement amount. The predetermined movement amount may be a constant movement amount. A field with a certain amount of movement is preferable if it is less than the depth of field of the imaging lens 22, since it can be photographed without missing in the optical axis direction. However, since such a movement amount may increase the number of movements, it may be determined according to the structure of the lens unit Lt that is the inspection object. In this case, the movement amount is not necessarily constant. . For example, as shown in FIG. 3, when the configuration of the lens unit Lt (arrangement of the lens Ls1 and the lens Ls2) is known in advance, and the position where the abnormality occurs (is likely to occur), the abnormality occurs. The imaging unit 2 may be moved so that the focus position P1 overlaps the position where it is likely to occur (is likely to occur).

Further, when the drive unit 3 moves the imaging unit 2 by a certain amount of movement and performs imaging after the movement, the abnormality does not overlap with the focus position P1 or enter the depth of field. There is also. In preparation for such a case, as shown in FIG. 7, an approximate curve indicating the relationship between the reference position and the distance from the focus position at the time of imaging may be created to determine the position of the abnormality.

  FIG. 7 shows the approximate curve Ft1 of the maximum luminance value of the image of the abnormality Nt1 and the approximate curve Ft2 of the maximum luminance value of the image of the abnormality Nt2 together with the above-described plot. The positions a0 to a6 indicate the focus position (focal plane) P1 at the time of imaging. In practice, however, the reference position a0 is set to 0, and the graph and the approximate curve are obtained using the physical distance from the reference position a0. Creating.

  By creating an approximate curve (approximation formula) and determining the position of the inflection point in this way, even when an abnormality does not overlap with the focus position P1 during imaging, or even if it is not placed within the depth of field It is possible to accurately detect the position of the abnormal optical axis direction. In addition, after detecting the position of the abnormality in this way, the focus position P1 may be superimposed on the position where there is an abnormality, and imaging may be performed to confirm the abnormality. By doing so, it is possible to accurately determine whether or not there is an abnormality.

  By using such approximate calculation, even when there are few shooting locations with respect to the length of the lens unit Lt in the optical axis direction, even if there is no abnormality within the focus position P1 or the depth of field, the abnormality is not detected. It is possible to detect an accurate position in the optical axis direction.

  When detecting the maximum value of the above-mentioned maximum luminance value, those that do not satisfy a certain threshold value may be excluded from the comparison targets. In addition, although not described in detail above, the position and size of the abnormality in the plane orthogonal to the optical axis can be detected from the captured image.

(Second Embodiment)
FIG. 8 is a flowchart showing the operation of the optical component inspection apparatus according to this embodiment. The configuration of the optical component inspection apparatus of the present embodiment is the same as that of the optical component inspection apparatus A. The flowchart shown in FIG. 8 includes detection of the magnitude of abnormality (step S201) after detection of the maximum luminance value (step S106), and determination of whether or not the magnitude of abnormality meets the standard (step S202). The flowchart is the same as that shown in FIG. Since steps S101 to S106 and steps S108 to S111 that are not related to the new steps S201 and 202 are the same, detailed description thereof is omitted.

  In an optical component, the allowable magnitude of anomalies may vary depending on the position. For example, in the case of the lens unit Lt, an abnormality in the position of the lens unit Lt of the lens Ls1 and the lens Ls2 facing the surface on the image sensor side may adhere to the image sensor of the camera. It gets smaller. On the other hand, since an abnormality other than the surface facing the image sensor side is less likely to adhere to the image sensor of the camera, the allowable size is larger than the abnormality facing the surface on the image sensor side.

  In the optical component inspection apparatus A, after detecting an abnormality (Yes in step S105), the maximum luminance value is detected (step S106), and then the size of the image of the abnormality in which the maximum luminance value is detected is detected (step S201). ). Since the imaging device 21 and the imaging lens 22 of the imaging unit 2 are fixed in position and fixed in magnification, the control unit 6 detects the size of the abnormal image from the captured image, thereby detecting the size of the abnormality. Can be detected.

  As shown in FIG. 5B, the abnormal image formed on the image sensor 21 may be formed on only a part of the light receiving sensor 211. In such a case, if the size of the image is determined only by the luminance of the image, it is detected larger than the actual size. Even if it is detected large, there is no problem because the possibility of missing a defective product is reduced. However, it is preferable to detect an accurate size since a product that is not originally defective may be detected as a defective product. Therefore, the control unit 6 may estimate the size of the abnormal image, that is, the size of the abnormality by using the detected luminance (gradation) value and the maximum luminance value of the abnormal image. .

  In this way, by estimating the size of the abnormal image based on the maximum luminance value and the luminance value of the pixel detecting the abnormal image, and then detecting the size of the abnormal, Can be detected.

  In the lens unit Lt, the magnitude of abnormality that is recognized as a defective product is different between the surface on the image sensor side and other positions. Therefore, in the inspection apparatus A for optical components, the configuration of the lens unit Lt in the storage unit 7 and the magnitude of the abnormality that identifies the lens unit Lt as a defective product are normalized by the position in the thickness direction and stored in the storage unit 7. Yes. For this reason, after the magnitude of the abnormality is detected in step S201, the standard value of the magnitude of the abnormality at the imaging position is called from the storage unit 7 and compared with the detected magnitude of the abnormality (step S202).

  If the detected abnormality is larger than the standard abnormality (Yes in step S202), the control unit 6 determines that the detected abnormality is a detection-necessary abnormality in that portion, and the current imaging position ( The focus position P1), the magnitude of the abnormality, and the maximum luminance value are stored in the storage unit (step S203). If the detected abnormality is smaller than the standard abnormality (No in step S202), it is determined that there is no abnormality recognized as a defective product, and the current focus position P1 is the reference position. It is determined whether it is farthest than (step S108).

  In this way, when storing the maximum luminance value, the abnormality detecting the maximum luminance value is compared with the standardized value recognized as a defective product, and the maximum luminance value detected from the allowable abnormality is compared with the comparison target. It can be omitted. Thereby, the comparison procedure can be reduced.

  In the embodiment described above, it is assumed that the abnormality appears with high luminance when the surface having the abnormality is in focus. Therefore, the maximum luminance value of the abnormal image is used as the maximum luminance when detecting the position of the abnormality. The present invention is not limited to this. For example, if the abnormality is black (absorbs light), low brightness appears when the subject is in focus. The position can be detected by adopting the lowest luminance value. At this time, the luminance distribution corresponding to FIG. 7 is a downwardly convex graph, and the inflection point appears in the portion of the lowest luminance value. By utilizing this fact, an abnormal position in the optical axis direction may be detected.

  In the embodiment described above, the inspection target is a lens unit in which a plurality of lenses are arranged. However, the present invention is not limited to this. For example, it may be used to detect an abnormality inside one lens, or may be used to detect an abnormality in other optical system components, structures, and the like.

  In addition, there may be a plurality of abnormalities in the inspection area. In that case, when shooting while changing the position of the focal plane, abnormalities appear at almost the same position in the plane coordinates perpendicular to the optical axis corresponding to each abnormality, so the maximum brightness in shooting at each position in the optical axis direction A value is stored for each abnormality, and the position in the optical axis direction where the maximum luminance value is maximized for each abnormality may be detected.

  In the above configuration, before the abnormality detection unit 5 detects an abnormality, image processing may be performed so that the captured image becomes a smoothed image with less noise components.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

Lt lens unit 1 case 10 base 11 support 111 illumination holding unit 12 inspection stage 2 imaging unit 21 imaging element 211 light receiving sensor 22 imaging lens 3 drive unit 4 illumination unit 40 stay 5 abnormality detection unit 6 control unit 7 storage unit

Claims (9)

An imaging unit having an imaging element for acquiring a captured image of a region to be inspected of an inspection object;
A drive unit that moves a focal plane of the imaging unit in a predetermined range in an optical axis direction of the inspection object;
An illumination unit that irradiates illumination light to the inspection region;
An abnormality detection unit that detects an abnormality in a portion of the captured image that has a luminance difference that can be recognized as an image in the field of view,
The imaging unit is configured such that an abnormality to be detected by the abnormality detection unit is detected by a plurality of pixels of the image sensor, and the subject is detected each time the focal plane is moved by a predetermined amount in the optical axis direction. Take a picture of the inspection area,
The maximum brightness value in the region of abnormality detected by the abnormality detection unit is recorded, and the abnormality is detected from the focal plane position where the maximum luminance value of the corresponding region of abnormality is maximized. An inspection apparatus for optical parts, wherein a position of the inspection object in the optical axis direction is detected. The imaging unit includes an imaging device that acquires a captured image, and a lens that forms a captured image on the imaging device,
The optical component inspection apparatus according to claim 1, wherein a depth of field of the lens is shallower than a thickness of the inspection object.   3. The optical component according to claim 2, wherein the imaging magnification of the lens is arranged at a position where an abnormality to be detected by the abnormality detection unit is imaged larger than a shape in which the pixels of the imaging element are arranged in 2 × 2. Inspection equipment.   The optical component inspection apparatus according to claim 2, wherein the predetermined amount is equal to or less than the lens depth of field.   The illumination unit is disposed so as to irradiate the inspection object with illumination light so that the imaging unit can capture images with uniform brightness, and the abnormality detection unit has a brightness higher than that of the periphery of the captured image. The optical component inspection apparatus according to claim 1, wherein a portion having a difference is determined to be abnormal.   When the maximum luminance value is arranged for each position of the focal plane, the abnormality detection unit determines a position that is an inflection point of the maximum luminance value as a position in the optical axis direction of the inspection object of the abnormality. The optical component inspection apparatus according to claim 1.   A focal plane in which the lowest luminance value is recorded instead of the highest luminance value detected in the abnormality region detected by the abnormality detection unit, and the lowest luminance value in the corresponding abnormality region is lowest among the images taken within the predetermined range. The optical component inspection apparatus according to any one of claims 1 to 5, wherein a position in the optical axis direction of the inspection object having the abnormality is detected from the position of the abnormality.   The minimum luminance value is recorded in addition to the maximum luminance value in the abnormal region detected by the abnormality detecting unit, and the image of the focal plane in which the minimum luminance value in the corresponding abnormal region is lowest is recorded within the predetermined range. The optical component inspection apparatus according to any one of claims 1 to 6, wherein a position of the abnormal inspection target in an optical axis direction is detected from a position.   When the lowest luminance value is arranged for each position of the focal plane, the abnormality detecting unit determines a position that is an inflection point of the lowest luminance value as a position in the optical axis direction of the inspection object of the abnormality. The optical component inspection apparatus according to claim 7 or 8.

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