JP2018054575A - Lens appearance inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens appearance inspection apparatus in which a sufficient contrast ratio is secured in an image captured by scattered light and the accuracy of inspection using the image is good. SOLUTION: A lens appearance inspection device 1 has a narrow angle of light having a directivity angle of 30 ° or less from a lateral direction which is a direction in which a spectacle lens L, which is a lens to be inspected, intersects an optical axis of the spectacle lens L. It has a narrow-angle optical illumination means 7 that illuminates with narrow-angle optical LEDs 24, 24 ... that emit light, and illumination lenses 26, 26 ..., and a camera lens 36 that is an object-side telecentric lens directed at the spectacle lens L. A camera 8 for capturing the cage inspection image C is provided, and the camera 8 captures the inspection image C in a state where the spectacle lens L is illuminated by the narrow-angle light illuminating means 7 from the lateral direction with narrow-angle light. Take an image. [Selection diagram] Fig. 1

Description

  The present invention relates to a lens appearance inspection apparatus for inspecting the appearance of a lens such as an eyeglass lens or a camera lens.

As a lens image pickup device, one disclosed in Patent Document 1 below is known.
In this apparatus, as described in [0054] and FIG. 1, the light L emitted from the light source 31 is converted into parallel light L1 by the collimator lens 36, and the parallel light L1 is converted by the half mirror 35 and the corner cube prism 49. The light passes through the test lens 1 once and is focused on the CCD 40A.
On the other hand, in visual inspection of lenses such as spectacle lenses, in order to prevent dazzling and accurately inspect, the transmitted light of the illumination is not visually observed, but is inspected by capturing scattered light scattered at abnormal appearance points. ing. For example, in a spectacle lens, an appearance abnormality is detected as scattered light by the wearer, and the inspection by the scattered light is similar to the detection by the wearer (the user of the lens).

Japanese Patent No. 4906708

In Patent Document 1, an image of a lens is picked up by transmitted light of parallel light, and a light beam that has passed through a mark or the like diverges while the transmitted light travels in parallel, so that a clear image is obtained.
However, in Patent Document 1, an image is captured by capturing transmitted light, which may be a visual inspection and a gap inspection, which may not be suitable for the user. There is a possibility that the imaging device is not diverged and the appearance abnormality cannot be captured well.
Therefore, it is conceivable that the inspection similar to the visual inspection is automatically performed by imaging the scattered light without imaging the transmitted light.
However, in the case of imaging only with scattered light, the amount of scattered light is very small, so it is difficult to obtain the contrast ratio necessary for sufficiently accurate inspection, especially with various curve values and frequencies like eyeglass lenses. In all cases, it is difficult to secure a sufficient amount of scattered light and it is difficult to obtain a necessary contrast ratio.
Accordingly, the main object of the present invention is to provide a lens appearance inspection apparatus in which a sufficient contrast ratio is ensured in an image captured by scattered light and the inspection accuracy using the image is good. .

In order to achieve the above-mentioned object, the invention according to claim 1 is a narrow-angle light whose direction angle is 30 ° or less from the lateral direction that intersects the optical axis of the lens to be inspected. A narrow-angle light illuminating means that illuminates with light, and a camera that has an object-side telecentric lens or a bilateral telecentric lens that is directed toward the inspection target lens, and that captures an image for inspection. The inspection image is picked up in a state in which the inspection target lens is illuminated from the lateral direction with the narrow-angle light by the narrow-angle light illuminating means.
According to a second aspect of the present invention, in the above-mentioned invention, the box further includes a box whose inner surface is an antireflection surface, the box has a hole, and sandwiches the lens to be inspected. The hole is disposed on the opposite side of the camera.
According to a third aspect of the present invention, in the above-mentioned invention, the inspection object lens and the narrow-angle light illumination unit, and an enclosure covering the object-side telecentric lens or the both-side telecentric lens are further provided. The inner surface is an antireflection surface that prevents the reflection of the narrow-angle light.
The invention described in claim 4 is the above invention, further comprising a distance adjusting means for adjusting a distance between the lens to be inspected and the camera.
The invention according to claim 5 is characterized in that, in the above invention, the narrow-angle light illuminating means illuminates the entire periphery or a part of the inspection target lens.
The invention according to claim 6 is characterized in that, in the above invention, the lateral direction is a direction orthogonal to an optical axis of the lens to be inspected.

  According to the present invention, it is possible to provide a lens appearance inspection apparatus in which a sufficient contrast ratio is ensured in an image captured by scattered light and the inspection accuracy using the image is good. .

1 is a schematic perspective view of a lens appearance inspection apparatus according to the present invention. It is a longitudinal center cross-sectional schematic diagram of FIG. It is a top view of the narrow-angle light illumination means in FIG. It is a photograph which shows the image for a test | inspection in FIG. 5 is a photograph showing an image obtained by binarizing the inspection image of FIG. 4. FIG. 5 is a photograph corresponding to FIG. 4 when the stage is not a box. It is a photograph which shows the image which binarized the image for a test | inspection of FIG.

  Hereinafter, examples of embodiments according to the present invention will be described with reference to the drawings as appropriate. In addition, the form of this invention is not limited to the following.

≪Configuration etc.≫
FIG. 1 is a schematic perspective view of a lens appearance inspection apparatus 1 according to the embodiment, and FIG. 2 is a vertical central cross-sectional schematic view of the lens appearance inspection apparatus 1.
The lens appearance inspection apparatus 1 has an enclosure 2 and a horizontal top plate 3, and is opened at a central portion of the top plate 3 and a box-shaped stage 4 (box body) disposed at the lower inner side of the enclosure 2. A lens holding mechanism 6 disposed around the perforation hole 5, a narrow-angle light illumination means 7 disposed on the top plate 3 of the stage 4, a camera 8 disposed on the inner upper side of the enclosure 2, and a notification means 9 and a control means 10 for controlling these, and inspects the appearance of the spectacle lens L. The lens appearance inspection apparatus 1 is suitable for the inspection of the spectacle lens L including a large number of deep curves (small curvature radius), but lenses other than the spectacle lens L (deep curve or large thickness). It may be used for inspection. In addition, at least one of the enclosure 2, the lens holding mechanism 6, and the notification unit 9 may be omitted. Furthermore, the lens appearance inspection apparatus may be combined with various inspection apparatuses that perform other inspections related to the lens. In addition, a lens appearance inspection apparatus may be configured by combining a plurality of the following lens appearance inspection apparatuses 1.

  The enclosure 2 has a box shape that can be closed, and is formed of a light shielding material. The inner surface of the enclosure 2 is subjected to antireflection processing for preventing light reflection by reducing the reflectance of light, and the inner surface of the enclosure 2 is an antireflection surface for preventing light reflection. In this case, the black color is formed (blackening process). In addition, by sticking an antireflection film, the inner surface of the enclosure 2 with the antireflection film may be formed, and the antireflection surface of the inner surface of the enclosure 2 may be formed.

The stage 4 is supported by a lift 20 as a distance adjusting means so as to be movable up and down while keeping the top 3 in a horizontal posture. The stage 4 (box) need only have a shape surrounding the inner surface so that light does not strike the inner surface located below the spectacle lens L as much as possible. Etc., there may be openings. Alternatively, the lift 20 may be omitted. A part of the stage 4 may be supported so as to be movable up and down. Further, the stage 4 or a part thereof may be movable left and right by the lift 20 or other means.
The outer surface of the stage 4 is black, and the inner surface of the stage 4 is blackened by applying a black screen.

The lens holding mechanism 6 is a mechanism for holding a spectacle lens L as a lens to be inspected, and here is a pair (two) hooks 21 and 21 having an L-shaped cross section. One planar portion of each hook 21 is fixed to the inner side of the hole 5 (the lower surface of the top plate 3) opened in the center of the top plate 3, and the other planar portion has a standing posture. It supports the peripheral edge of the spectacle lens L at its upper part. The standing portion of each hook 21 has translucency, but may not have translucency as long as the illumination light is not inhibited. The hooks 21 and 21 are arranged so as to face each other, and their distance is adjusted according to the outer diameter of the spectacle lens L.
The number of hooks 21 may be one or may be three or more. The hook 21 may be fixed to other than the inside of the hole 5. The lens holding mechanism 6 may be a cylindrical member with a flange. In this case, the inner diameter adjusting means (shape) for matching the inner diameter size (inner shape) with the outer diameter (outer shape) of the spectacle lens L. Adjustment means) may be provided. Furthermore, the material of the lens holding mechanism 6 may be resin, ceramics, glass, metal, rubber, or a combination thereof.

3 includes a housing 23 having a hollow wide cylindrical shape having a central hole 22, and a plurality of narrow-angle light LEDs 24, 24,. Are provided with illumination lenses 26, 26,... Provided for each of the narrow-angle light LEDs 24, 24,.
The outer surface of the housing 23 is black like the inner surface of the enclosure 2.
Each narrow-angle light LED 24 emits white substantially narrow-angle light. Narrow-angle light is light having a directivity angle of 30 ° or less, and includes parallel light having a directivity angle of 0 °. Almost narrow-angle light is light that is almost narrow-angle light, but still has room for fine adjustment to approach perfect narrow-angle light, and diverges with a directivity angle slightly exceeding, for example, 30 ° ( This is light that spreads in a distant place), or light that shows such divergence when the directivity angle changes depending on conditions such as voltage. Each narrow-angle light LED 24 may emit substantially narrow-angle light of a color other than white, may emit substantially narrow-angle light other than visible light including ultraviolet rays and infrared rays, or a combination of these. Narrow angle light may be emitted. The narrow-angle light LED 24 may be a parallel light LED that emits parallel light or substantially parallel light. Nearly parallel light is almost parallel light, but still leaves room for fine adjustment to make it close to perfect parallel light. Light that diverges slightly (spreading in the distance) or light that slightly changes in convergence and divergence depending on conditions such as voltage.
Each narrow-angle light LED 24 is installed so that the light emission direction is in (in the center of) the central hole portion 22 of the housing 23.
The narrow-angle light LEDs 24, 24,... Are arranged so as to be aligned in the circumferential direction of the housing 23. Here, a total of 16 narrow-angle light LEDs 24, 24,.
Each illumination lens 26 is disposed inward of the corresponding narrow-angle light LED 24, and finely adjusts the optical path of the substantially narrow-angle light emitted from the narrow-angle light LED 24 to obtain narrow-angle light. . Note that the illumination lens 26 may be configured to convert substantially narrow-angle light, narrow-angle light, or substantially parallel light into parallel light. The illumination lens 26 may be integrated with the narrow-angle light LED 24, may be common to the plurality of narrow-angle light LEDs 24, 24,. The means for emitting narrow-angle light is not limited to the combination of the narrow-angle light LED 24 and the illumination lens 26, and may be a laser exciter or the like.

Then, the spectacle lens L is set in the central hole portion 22 (inspection position) of the housing 23 via the lens holding mechanism 6. The optical axis of the spectacle lens L is oriented in the vertical direction so that when the spectacle lens L is a convex lens, the convex surface is disposed downward, and when the spectacle lens L is a concave lens, the concave surface is upward. Be placed. The narrow-angle light illumination means 7 has the narrow-angle light LEDs 24, 24,... And the illumination lenses 26, 26,. The direction of the spectacle lens L may be opposite to that described above. However, if the direction is as described above, the scattered light from each lens can be more easily captured.
The substantially narrow-angle light emitted from each narrow-angle light LED 24 is parallel to the direction of the narrow-angle light LED 24, becomes narrow-angle light by the corresponding illumination lens 26, and increases toward the spectacle lens L. It goes straight without spreading or suddenly converging. The direction of the narrow-angle light emitted from each illumination lens 26 is a direction intersecting with the optical axis of the spectacle lens L, and more specifically, a horizontal direction orthogonal to the optical axis. The light-emitting portion of each narrow-angle light LED 24 has a predetermined size (for example, a disk with a diameter of 2 mm (millimeter)), and in the traveling direction related to the narrow-angle light from each narrow-angle light LED 24 or the illumination lens 26. The size of the vertical cross section increases from the size of the light emitting portion by the directivity angle.
Even when the narrow-angle light reaches the lens holding mechanism 6, at least the reaching part (the standing part of each hook 21) has translucency, so that the narrow-angle light passes through the lens holding mechanism 6.
The housing 23 may have other shapes such as a wide and thick arc shape, and the narrow-angle light LEDs 24, 24... And the illumination lenses 26, 26. For example, it may be arranged so as not to surround the spectacle lens L. Further, the traveling direction of substantially narrow-angle light related to the narrow-angle light LEDs 24, 24,... And the optical axis direction of the illumination lenses 26, 26,. May be oriented in a direction that intersects at an angle other than 90 °.

The camera 8 includes a camera body 34 having an image sensor 30 and storage means 32 and a camera lens 36 attached to the lower part of the camera body 34, and is taken in from the camera lens 36 based on a command from the control means 10. The inspection image C is acquired by capturing the captured image with the image sensor 30, stored in the storage unit 32, and transmitted to the control unit 10. Here, the image sensor 30 is an area sensor. The camera 8 may not include the storage unit 32 and may immediately transmit the inspection image C to the control unit 10. The storage means 32 may be volatile or nonvolatile, and may be a memory, a hard disk, or a combination thereof.
The imaging element 30 and the camera lens 36 are installed so as to face the narrow-angle light illumination means 7 and the spectacle lens L.

The imaging element 30 is assumed to have a relatively high resolution in consideration of imaging with only narrow-angle light. In addition, the imaging element 30 has a relatively high sensitivity in consideration of imaging with only narrow-angle light.
The camera lens 36 is an object side telecentric lens in which the principal ray on the object side is parallel to the lens optical axis. The camera lens 36 may be a double-sided telecentric lens in which the principal ray is parallel to the lens optical axis on both the object side and the image side.
Since the camera lens 36 is an object side telecentric lens, the depth of field is the entire depth of the spectacle lens L even in the spectacle lens L having a relatively deep depth of field, a deep curve, and a large thickness. It ’s like focusing.
The actual field of view of the camera lens 36 is relatively wide in consideration of imaging with only narrow-angle light and capturing the entire spectacle lens L, and is preferably 85 mm or more.

  The notification means 9 notifies at least the inspection result, and is, for example, a sound generation means, a display means, or a combination thereof. The sound generating means is, for example, a speaker or a buzzer, and the display means is, for example, a lamp, a 7-segment LED, a flat display, or a combination thereof. The display means may be combined with input means such as a touch panel. Independent input means (for example, a keyboard, a pointing device, or a combination thereof) may be provided.

The control means 10 is, for example, a microcomputer disposed outside or attached to the enclosure 2, and is electrically connected to the lift 20, the narrow-angle light illumination means 7, the camera 8 or the notification means 9, respectively. Each of these is controlled. The control means 10 may be incorporated in at least one of the lift 20, the narrow-angle light illumination means 7, the camera 8, or the notification means 9, or a plurality of control means 10 may be distributed so as to be capable of cooperative control.
Further, the control means 10 is electrically connected to a conveyance means (not shown) for placing the spectacle lens L at the inspection position or taking it out from the inspection position, and the control means 10 can control the conveyance means. . The conveying means is, for example, a robot hand, a conveyor, a lift of the spectacle lens L, or a combination thereof. In the case of a conveyor, the narrow-angle light illuminating means 7 can be retracted (for example, raised) or returned (lowered), and the control means 10 retracts the narrow-angle light illuminating means 7 so that the eyeglass lens L is inspected by the conveyor. Then, the narrow-angle light illumination means 7 may be returned. In the case of the lift of the spectacle lens L, after the spectacle lens L is placed at the retracted (downward) position of the spectacle lens L placement portion, the placement portion returns (rises) to the inspection position, and after the inspection, at the retracted position. The spectacle lens L may be taken out. The conveying means may convey the spectacle lens L and the lens holding mechanism 6. The lens appearance inspection apparatus 1 may be combined with a lens cleaning apparatus. In this case, the conveying means conveys the spectacle lens L to the lens cleaning apparatus, and after the spectacle lens L is cleaned, the spectacle lens L is taken out and the lens is taken out. You may convey to the external appearance inspection apparatus 1. FIG.

The control means 10 includes a storage means 40 similar to the storage means 32 of the camera, a communication means 42, and a CPU 44 for controlling them.
The storage means 40 stores a lens appearance inspection program 50 and a lens database 52.
The lens database 52 associates a lens characteristic value that is a characteristic value related to the spectacle lens L and an imaging setting value that is a setting value related to imaging by the camera 8. Here, the lens characteristic value is a value indicating the diameter of the spectacle lens L, the curve value (frequency), lens design information (diameter, floor height, center thickness, edge thickness, etc. of the spectacle lens L) and the type of coating. Any part of the values may be omitted, or other values may be added. Here, the floor height is the height from the plane to the top of the convex surface (the opposite surface of the concave surface) when the convex surface of the spectacle lens L is placed on a flat surface with the convex surface up or concave surface down, and the center thickness is The thickness at the center of the eyeglass lens L, and the edge thickness is the thickness at the edge (edge) of the eyeglass lens L. Further, various lens characteristic values may be directly input, or may be calculated by calculation from other lens characteristic values. On the other hand, the imaging setting value here is an imaging distance that is a distance between the spectacle lens L and the camera lens 36, an exposure time, and a gain, but any part of the values may be omitted. A value may be added.
The communication means 42 is a means capable of inputting / outputting various types of information, such as a hub, various terminals, a communication controller, or a combination thereof.
When the lens holding mechanism 6 capable of adjusting the inner shape is connected to the control means 10, the control means 10 controls the inner shape of the lens holding mechanism 6 according to the lens characteristic value (the diameter of the spectacle lens L). You may do it.

≪Operation etc.≫
An example of the operation of the lens appearance inspection apparatus 1 will be described below.
The lens appearance inspection apparatus 1 operates, for example, as follows by the CPU 44 (control means 10) that executes the lens appearance inspection program 50.
The transport means carries the spectacle lens L to be inspected into the inspection position in the narrow-angle light illumination means 7 under the control of the control means 10.
The control means 10 is input with the lens characteristic value of the spectacle lens L for carrying in via the communication means 42. The lens characteristic value may be input from another computer (not shown), or may be input by an input unit (not shown) (for example, a keyboard, a pointing device, a touch panel, or a combination thereof).
The enclosure 2 is provided with a door (not shown), and when the spectacle lens L is carried in, the door is opened and can pass through the spectacle lens L. After the carry-in is completed, the door is closed before imaging. Blockage by the enclosure 2 is ensured.

The CPU 44 of the control unit 10 refers to the lens database 52, acquires an imaging setting value corresponding to the received lens characteristic value, and allows the camera 8 and the lift 20 to perform imaging that matches the imaging setting value. In response, a command is sent through the communication means 42. Here, the control means 10 operates the lift 20 to raise or lower the stage 4 through commands to the lift 20 so as to match the imaging distance acquired in the lens database 52, and the glasses on the top plate 3. By raising or lowering the lens L, the position of the spectacle lens L with respect to the camera lens 36 is adjusted, and the imaging distance is adjusted. The stage 4 may be movable in at least one direction of front and rear, left and right (horizontal direction). Further, the camera 8 may be moved up and down or horizontally moved, and both the camera 8 and the stage 4 may be moved up and down or horizontally moved.
Further, the control means 10 transmits a light emission command for emitting narrow-angle light with a predetermined intensity to the narrow-angle light illuminating means 7, and in response thereto, each narrow-angle light of the narrow-angle light illumination means 7. The LED 24 lights up. The control unit 10 may control the narrow-angle light illuminating unit 7 so as to illuminate with the illumination intensity so that the imaging setting value includes the illumination intensity.

In this way, the spectacle lens L is illuminated by the narrow-angle light emitted from the narrow-angle light illumination means 7.
The narrow-angle light passes through the translucent spectacle lens L in a state intersecting (orthogonal) with the optical axis of the spectacle lens L, and ideally proceeds horizontally as it is and exits the spectacle lens L. . Since the narrow-angle light traveling horizontally in this manner has a narrow directivity angle and a gentle diffusion, it is difficult to reach the camera 8 disposed above the spectacle lens L, and the surface of the spectacle lens L (air and air). A very small part is directed to the camera 8 due to reflection or refraction at the interface. Such reflection or refraction is directed toward various directions as the lens (glasses lens L) having a deeper curve. In addition, when the narrow-angle light is parallel light, the parallel light does not converge or diffuse when it travels horizontally, and therefore ideally does not go in the direction of the camera 8 disposed above the spectacle lens L. In practice, however, a small portion is directed to the camera 8 due to reflection or refraction on the surface of the spectacle lens L described above.
On the other hand, when a foreign object is attached to or mixed in the spectacle lens L, the narrow-angle light reaching the foreign object is scattered, and a part of the scattered light (reflected light by the foreign object) is directed to the camera 8. The intensity of such scattered light is generally greater than the intensity of light due to reflection or refraction described above. The foreign material is, for example, dust or uneven coloring generated on the surface or inside of the spectacle lens L, bubbles, fixed matter, fragments, unevenness of the film formed on the surface of the spectacle lens L, or a combination thereof.
If the spectacle lens L has scratches / chips or poorly formed portions, the narrow-angle light that reaches the scratches / chips or poorly formed portions is scattered in the same manner as in the case of foreign matter, and a part of the light is scattered on the camera 8. Head. Hereinafter, the foreign matter, chipping, and poorly formed portion are collectively referred to as foreign matter or the like as appropriate.
In addition, even if the narrow-angle light emitted from the narrow-angle light illuminating means 7 reaches the inner surface of the enclosure 2, the inner surface of the enclosure 2 is an anti-reflection surface, so that reflection on the inner surface is prevented. The situation where the reflected light from the inner surface goes to the camera 8 is prevented.

The control means 10 issues an imaging command to the camera 8, and in response to this, the camera 8 releases the shutter, captures the light captured by the camera lens 36 with the imaging device 30, and collects a set of pixel information of the still image. And the image is appropriately processed and stored in the storage means 32 as the inspection image C. Here, one inspection image C is acquired for one spectacle lens L, but a plurality of images may be acquired. Further, the camera 8 may capture a moving image and acquire a moving image for inspection.
Since the inspection image C is acquired by the camera lens 36 that is an object-side telecentric lens, even in the spectacle lens L having a deep curve or the spectacle lens L having a large thickness, all portions are focused. As a result, scattered light is generated due to foreign matter, chipping, or the like in a portion that is not in focus, and a clear image cannot be obtained, and a situation in which the inspection by the inspection image C is hindered is prevented. In addition, non-telecentric lenses capture scattered light that spreads out due to foreign matter, etc., distorted by the amount of parallax, and the actual size and state of foreign matter are unclear, or there are multiple foreign matters However, the camera lens 36 does not have such a situation, and it is possible to capture all the foreign matters in their actual sizes and states. Strictly speaking, it is difficult to completely prevent the change in size, but the change in size is remarkably suppressed as compared with the case of imaging with a non-telecentric lens. As described above, when there is a height difference in the spectacle lens L, deformation of the shape of the spectacle lens L in the imaging portion is suppressed.
The lens database 52 stores the imaging distance corresponding to the diameter and curve value of the spectacle lens L, and the entire spectacle lens L is in focus in the inspection image C (the entire spectacle lens L is captured). An imaging distance such as to be within the depth of field is obtained in advance and stored in association with the diameter and curve value of the spectacle lens L. As described above, the control unit 10 controls the lift 20 and moves the spectacle lens L via the stage 4 and the lens holding mechanism 6 so as to obtain the imaging distance. Since the camera lens 36 has a telecentric effect at least on the object side, the real field of view is constant regardless of the imaging distance.
For example, when the real field of view is 80 mm long and 80 mm wide, the depth of field is 9 mm, and the center of the depth of field is 150 mm from the tip of the camera lens 36, the floor height is 5 mm and the positive intensity number For the spectacle lens L (convex lens), the control means 10 operates the lift 20 so that the position of the floor height center (2.5 mm) matches the center position of the depth of field. On the other hand, in the same case, for a spectacle lens L (concave lens) having a negative height number with a floor height of 6 mm, the control means 10 causes the position of the center of the floor height (3 mm) to coincide with the center position of the depth of field. The lift 20 is operated. Here, consider a case where there is no lift 20 (the imaging distance is not adjusted). Since the convex lens is positioned below the support point of the lens holding mechanism 6, the concave lens is positioned above the support point of the lens holding mechanism 6, the total vertical width (floor height direction) occupied by both lenses The total value of the widths of 11 mm is 11 mm when the support point is 5 mm (convex lens) downward and 6 mm (concave lens) upward. The vertical width of 11 mm is larger than the depth of field of 9 mm. Therefore, when the imaging distance is not adjusted, at least one of the convex lens and the concave lens is partially out of focus. On the other hand, in the lens appearance inspection apparatus 1, since the imaging distance is adjusted by the lift 20, both the convex lens and the concave lens can be positioned within the depth of field, and the entire focus can be adjusted.
The eyeglass lens L is held by the lens holding mechanism 6 that holds the periphery of the eyeglass lens L so as to overlap (overlap) the hole 5 of the top plate 3 in a top view, and the camera 8 (camera lens 36) The inside of the hole 5 (inside the box-shaped stage 4) is blackened. Therefore, the camera lens 36, the spectacle lens L, and the hole 5 are arranged in the vertical direction, and the hole 5 is positioned on the opposite side of the camera lens 36 with the spectacle lens L interposed therebetween. By the conversion processing, a portion where the scattered light is not generated in the inspection image C can be made blacker, and the contrast ratio with respect to the scattered light due to the foreign matter or the like is improved. Further, reflection of scattered light traveling toward the stage 4 is prevented inside the stage 4, reflection of scattered light not caused by foreign matter or the like is suppressed, and a reduction in contrast ratio in the inspection image C is prevented. Further, since the stage 4 is box-shaped and covers a part or all of the lower part of the spectacle lens L (the part beyond the spectacle lens L when viewed from the camera lens 36), the reflected light on the inner surface of the enclosure 2 or the like Even if it goes to the lower side of the spectacle lens L, it can be blocked by the stage 4, and reflection of scattered light not caused by foreign matter or the like is suppressed, and a decrease in contrast ratio in the inspection image C is prevented.
The camera 8 transmits the inspection image C acquired in this way to the control unit 10, and the control unit 10 stores the inspection image C received by the communication unit 42 in the storage unit 40.

The control means 10 determines whether an abnormality has occurred in the stored inspection image C. Here, the determination is made based on whether or not the inspection image C includes pixels having a luminance equal to or higher than a predetermined value (for example, 128 in 256 stages) over a predetermined range (for example, a range of 3 pixels × 3 pixels). Note that when the inspection image C is acquired, a portion outside the spectacle lens L may be disposed outside the imaging range. Further, the above determination may be made based on a plurality of inspection images C, C,. In addition, the above-described determination may be based on whether or not the luminance is equal to or higher than a second predetermined value (which may be the same value as the predetermined value or a different value) even within the predetermined range. Or a predetermined number of pixels that are equal to or greater than a predetermined value (which may be the same value as the predetermined value or the second predetermined value or a different value), or a combination thereof.
The control means 10 outputs a determination result that an abnormality has occurred in the inspection image C when pixels having a luminance of a predetermined value or more exist over a predetermined range.
When the control unit 10 obtains a determination result that an abnormality has occurred in the inspection image C, the controller 10 indicates that an abnormality is observed in the appearance of the spectacle lens L related to the inspection object (the inspection result is abnormal). ), Informing means 9 is informed. The notification of the occurrence of abnormality may be generation of a buzzer sound, lighting of a lamp, pronunciation or display of a message, or a combination thereof. Further, when the notification means 9 includes a display means, the inspection image C may be displayed on the display means. Note that the notification means 9 may notify that an abnormality is not recognized (inspection result is normal) in a manner different from the manner in which the abnormality is reported.

  When the determination process or the abnormality occurrence notification process for the inspection image C is completed, the control unit 10 instructs the narrow-angle light illumination unit 7 to turn off the light, and carries out the spectacle lens L by the transport unit, so that the next inspection target is obtained. When the spectacle lens L is present, the above process is repeated. The lighting of the narrow-angle light illumination means 7 may be continued.

≪Effects≫
The lens appearance inspection apparatus 1 described above applies narrow-angle light, which is light having a directivity angle of 30 ° or less, from a lateral direction that intersects with the optical axis of the spectacle lens L. Narrow-angle light illumination means 7 illuminated by narrow-angle light LEDs 24, 24... And illumination lenses 26, 26..., And a camera lens 36 which is an object-side telecentric lens directed to the spectacle lens L A camera 8 that captures the image C for imaging, and the camera 8 captures the image C for inspection in a state where the spectacle lens L is illuminated by the narrow-angle light illumination means 7 from the lateral direction with the narrow-angle light. .
Therefore, the camera 8 hardly captures the narrow-angle light that is transmitted laterally through a normal part free of foreign matter or the like in the generation of the inspection image C, but reaches the abnormal part with foreign matter or the like and is reflected. Since the angular light is clearly captured, the contrast ratio in the inspection image C becomes extremely good, and accordingly, foreign matters and the like are easily found. Further, since the camera 8 generates the inspection image C through the camera lens 36 that is an object side telecentric lens, even in the case of the spectacle lens L having a large thickness or curve value, the thickness direction (the optical axis direction of the spectacle lens L). ), A clear inspection image C can be obtained, and it is not necessary to acquire a plurality of images with different focus positions. Can be detected at an appropriate position or size in the inspection image C, and even when a plurality of foreign objects or the like are generated, the inspection image C can be detected at an appropriate position or size. Therefore, an accurate inspection can be ensured by the inspection image C.
In particular, when the inspection by the lens appearance inspection apparatus 1 is compared with the inspection using transmitted light such as that of Patent Document 1 described above, in the inspection of transmitted light, the portion corresponding to the foreign matter is dark and the other portions are bright. The use of images may result in an inspection that does not match the situation in which the user feels a foreign object, and the light beam reflected by the foreign object may not diverge well and may not be captured by the camera, which may affect the accuracy of the inspection. However, in the inspection of the lens appearance inspection apparatus 1, an inspection image C is used in which the part corresponding to the foreign matter is bright and the other part is dark, and the inspection suitable for the user's situation can be performed. A high contrast ratio can be ensured and excellent inspection accuracy can be ensured.
On the other hand, compared with direct visual inspection using reflected light, diffuse light such as foreign matters is magnified or shrunk by the action of the spectacle lens L by direct visual inspection, causing erroneous determination, or such enlargement or reduction. The degree of the difference varies depending on the power of the spectacle lens L. In particular, in the lens to be inspected such as the spectacle lens L having various powers, the difference is remarkable, and such a difference is also a cause of erroneous determination. However, in the inspection by the lens appearance inspection apparatus 1, in the inspection image C captured by a lens having at least the object side telecentric, the diffused light such as a foreign substance has the same size regardless of the portion of the spectacle lens L. It is picked up and picked up at the same size regardless of the frequency of the spectacle lens L, so that erroneous determination can be avoided and more accurate inspection can be performed.

In addition, a stage 4 having an inner surface serving as an antireflection surface is provided. The stage 4 has a hole 5, and the hole 5 is formed on the opposite side of the camera lens 36 (camera 8) across the spectacle lens L. Is arranged to be located. Accordingly, the inner surface of the spectacle lens L beyond the spectacle lens L as viewed from the camera lens 36 can be separated from the spectacle lens L, and reflection light and repetitive reflection light can be prevented from entering the stage 4. Even if it enters, the reflection is suppressed by the antireflection surface, and as a result, the lowering of the contrast ratio is suppressed by preventing the reflected light and scattered light from illuminating the above-mentioned inner surface where the distance from the spectacle lens L is secured, The contrast ratio in the inspection image C can be further improved, and the inspection image C that can perform inspection with higher accuracy can be acquired.
FIG. 4 is a photograph showing the inspection image C when the stage 4 is a box like the lens appearance inspection apparatus 1, and FIG. 5 is a binary image (brightness threshold) of the inspection image C of FIG. FIG. 6 shows an image C for inspection when the stage is not a box (no light entry prevention means for the surface below the spectacle lens L). FIG. 7 is a photograph showing an image obtained by binarizing the inspection image C of FIG.
In the photograph of FIG. 6, although the contrast ratio is good, the upper right, lower right, upper left, and lower left portions just inside the narrow-angle light illumination means 7 are portions P having higher luminance than the surroundings. Such a portion P is generated by dividing the narrow-angle light illuminating means 7 into four parts for each arc having a central angle of 90 °, and the joining surface and parts (screws, etc.) used for joining. This is due to the appearance of reflected light. The occurrence of these portions P appears remarkably in the photograph of FIG. 7 relating to binarization, and depending on the setting of the threshold value or the like, when analyzing a high luminance portion, that is, a foreign matter existing portion in the binarized image, There is a possibility that the reflected light from the joint surface or parts is mistaken as a foreign substance or the like.
On the other hand, in the photograph of FIG. 4, the contrast ratio is further improved compared to the photograph of FIG. 6, and the brightness of the reflected light due to the structure (bonding) of the narrow-angle light illumination means 7 is suppressed. . Such suppression of luminance can be seen well from the fact that the portion P does not appear even after binarization in the photograph of FIG. 5 related to binarization as in the photograph of FIG.
From these photographs, the effect of preventing reflection of reflected light (including that from the narrow-angle light illumination means 7) and the effect of improving the contrast ratio can be seen by installing the box (stage 4).

Furthermore, the enclosure 2 which covers the camera 8 which has the spectacle lens L and the narrow-angle light illumination means 7, and the camera lens 36 is provided, and the inner surface of the enclosure 2 of the narrow-angle light emitted from the narrow-angle light illumination means 7 is provided. It is painted black so as to provide an antireflection surface that prevents reflection. Therefore, it is possible to prevent external light (natural light, illumination light, etc.) from entering the enclosure 2 from the outside, thereby preventing external light from appearing in the inspection image C, and narrow-angle light on the inner surface of the enclosure 2. By suppressing reflection and further reflection of reflected light (repetition of reflection), it is possible to prevent the reflected light from appearing in the inspection image C, and to achieve an excellent contrast ratio in the inspection image C. It is possible to acquire an inspection image C that can perform an inspection with high accuracy.
Further, since the lens appearance inspection apparatus 1 includes the lift 20 that adjusts the imaging distance that is the distance between the spectacle lens L and the camera 8, the spectacle lens L having different characteristic values is continuously inspected. Even in this case, it is possible to secure an imaging distance suitable for the characteristic value, and the spectacle lens L according to any characteristic value has a small number of clear inspection images C (here, one). ) Can be obtained, and an accurate inspection with a small amount of processing and inspection time can be realized.

Further, since the narrow-angle light illuminating means 7 illuminates the entire periphery of the spectacle lens L or a part thereof, the narrow-angle light in the lateral direction can be evenly given to the spectacle lens L, and more reliably. The inspection image C for the inspection with higher accuracy can be acquired by causing the reflection of the foreign matter or the like.
In addition, since the direction in which the narrow-angle light illuminating means 7 irradiates the narrow-angle light is a direction orthogonal to the optical axis of the spectacle lens L, the narrow-angle light is more appropriately irradiated, and more accurate. An inspection image C for high inspection can be acquired.

  1 .... Lens appearance inspection device, 2 .... Enclosure, 4 .... Stage (box), 5 .... (Stage) hole, 7..Narrow-angle light illumination means, 8 .... Camera, 20 .... Lift ( Distance adjustment means), 24 ... Narrow-angle LED, 26 ... Lighting lens, 36 ... Camera lens (object-side telecentric lens or double-sided telecentric lens), C ... Image for inspection, L ... Eyeglass lens (inspection) Target lens).

Claims (6)

Narrow-angle light illuminating means for illuminating the inspection target lens with a narrow-angle light having a directivity angle of 30 ° or less from a lateral direction that intersects the optical axis of the inspection target lens;
A camera that has an object-side telecentric lens or a bilateral telecentric lens that is directed to the lens to be inspected and captures an image for inspection; and
With
The lens appearance inspection apparatus, wherein the camera captures the inspection image in a state where the inspection target lens is illuminated from the lateral direction with the narrow-angle light by the narrow-angle light illuminating unit. Furthermore, it has a box body whose inner surface is an antireflection surface,
2. The lens appearance inspection according to claim 1, wherein the box has a hole, and is arranged so that the hole is located on a side opposite to the camera with the lens to be inspected in between. apparatus. Further, the inspection object lens and the narrow-angle light illumination means, and an enclosure covering the object side telecentric lens or the both side telecentric lens,
3. The lens appearance inspection apparatus according to claim 1, wherein an inner surface of the enclosure is an antireflection surface that prevents the reflection of the narrow-angle light. The lens appearance inspection apparatus according to claim 1, further comprising a distance adjusting unit that adjusts a distance between the lens to be inspected and the camera. The lens appearance inspection apparatus according to any one of claims 1 to 4, wherein the narrow-angle light illumination unit illuminates the entire periphery or a part of the inspection target lens. 6. The lens appearance inspection apparatus according to claim 1, wherein the lateral direction is a direction orthogonal to an optical axis of the inspection target lens.