JP6300158B2 - Inspection illumination method and inspection illumination device - Google Patents

Description

  The present invention relates to an inspection illumination method for inspecting a surface to be inspected by irradiating light, and an inspection illumination device.

  For example, when an appearance inspection of a product is performed, light is irradiated onto the inspection target surface of the inspection target using coaxial illumination as described in Patent Document 1, and reflected light or scattering from the inspection target surface. It is performed by imaging the light with a camera to determine the shape error of the inspection target surface and the presence or absence of defects by image processing.

  By the way, since the light emission mechanism of the coaxial illumination used in Patent Document 1 has a flat light emitting surface, for example, when the surface to be inspected is a curved surface or an uneven surface, light is emitted by a lens. Even if the light emitted from the emission mechanism is condensed, the light emitting surface forms an image only on a part of the inspection target surface. The fact that most of the inspection target surface can only perform light irradiation in a non-uniform and blurry state in which an image is not formed is a cause of reducing accuracy related to shape determination and defect detection of the inspection target surface. The inventor of the present application has found out that as a result of intensive studies.

JP 2012-185270 A

  The present invention has been made in view of the above-described problems, and an inspection illumination method capable of uniformly irradiating light from a light emission mechanism over the entire inspection target surface regardless of the shape of the inspection target surface, and An object is to provide an inspection illumination device.

  In the present invention, in order to realize the same irradiation mode at any inspection target point even if the inspection target surface is a curved surface or an uneven surface, the shape of the light emitting surface itself must be made appropriate to the shape of the inspection target surface. This is because the inventors of the present application found for the first time as a result of intensive studies.

  That is, the present invention uses a light emitting mechanism having a light emitting surface, a curved or uneven surface to be inspected, and a lens provided between the light emitting mechanisms to emit the light on the surface to be inspected. An inspection illumination method for irradiating light emitted from a surface, wherein the shape of the light emitting surface is set so that each point of the light emitting surface is imaged by the lens with respect to each point of the surface to be inspected It is characterized by doing.

  Further, the present invention includes a light emission mechanism having a light emitting surface, a curved or uneven surface to be inspected, and a lens provided between the light emission mechanisms, and the light emitting surface on the inspection object surface. The illumination device for inspection irradiates the light emitted from the light emitting surface, and the shape of the light emitting surface is formed so that each point of the light emitting surface is imaged by the lens with respect to each point of the surface to be inspected. It is characterized by.

  If it is such, according to the shape (profile) of the said to-be-inspected surface of a curved surface shape or an uneven surface shape, the said light emission surface is formed in an intrinsic | native shape, and with respect to each point of the said to-be-inspected surface Since each point on the light emitting surface is imaged, it is possible to irradiate uniform light over the entire surface to be inspected.

  Therefore, it is possible to perform a precise inspection of the shape of the inspection target surface itself, which has been difficult with the inspection illumination method of the present invention, and to detect fine defects on the inspection target surface.

  In order to easily determine the shape of the light emitting surface by calculation, the distance a from each point on the inspection target surface to the principal surface of the lens, and each point on the light emitting surface corresponding to each point on the inspection target surface The shape of the light emitting surface may be set so that the distance b from the lens to the principal surface of the lens and the focal length f of the lens satisfy the Gaussian imaging formula 1 / a + 1 / b = 1 / f.

  To determine the shape of the light emitting surface in consideration of the fact that the light emitting surface is imaged on the inspection target surface as an inverted real image through the lens, each point on the inspection target surface, The shape of the light emitting surface is set so that at least a part of an imaginary line connecting each point of the light emitting surface corresponding to each point on the inspection target surface intersects the main optical axis of the lens. That's fine.

  For example, as a specific shape example of the light emitting surface effective in defect inspection on the inner bottom surface of the can, when the surface to be inspected has a convex shape toward the lens side, a concave shape toward the lens side is formed. As described above, the shape of the light emitting surface is set.

  As another specific embodiment of the present invention, when the surface to be inspected has a concave shape toward the lens side, the shape of the light emitting surface is set so as to form a convex shape toward the lens side. Things.

  As described above, according to the inspection illumination method and the inspection illumination device of the present invention, even if the shape of the inspection target surface is not a flat surface but a complicated shape, the light emitting surface is imaged on the entire surface to generate uniform light. Irradiation can be performed, and the inspection accuracy can be improved as compared with the prior art.

The typical perspective view showing the appearance of the inspection system concerning one embodiment of the present invention. The typical sectional view showing the internal structure of the inspection system in the embodiment. The schematic diagram shown about the irradiation optical system in the embodiment. The schematic diagram shown about the setting method of the shape of the light emission surface in the embodiment. The schematic diagram which shows the modification of the shape of the light emission surface in the embodiment. The schematic diagram which shows another modification of the shape of the light emission surface in the embodiment. The schematic diagram which shows the illuminating device for a test | inspection which concerns on another embodiment of this invention. The schematic diagram which shows the illuminating device for a test | inspection which concerns on another embodiment of this invention. The schematic diagram which shows the illuminating device for a test | inspection which concerns on different embodiment of this invention.

  An embodiment of the present invention will be described.

  The inspection illumination apparatus 100 according to the present embodiment and the inspection system 200 configured by the imaging apparatus C are so-called coaxial illumination in which the direction in which the inspection target W is imaged coincides with the direction in which the inspection target W is illuminated. This is used to cause the defect of the inspection object W to appear as a light-dark difference in an image captured by the imaging device C. Here, the feature points such as defects of the inspection object W include various defects such as surface scratches, appearance shapes, presence / absence of holes, and other feature types.

  The illumination device for inspection 100 has a substantially L-shaped housing as shown in the perspective view of FIG. 1 and the cross-sectional view of FIG. 2, and inspection light is inspected from the light emitting mechanism 1 inside thereof. An irradiation light path L1 for irradiating the object W and a reflection light path L2 until the reflected light from the inspection object W reaches the imaging device C are formed. More specifically, a first cylindrical body 91 extending in the horizontal direction and a second cylindrical body 92 extending in the vertical direction are respectively connected to the box body 93, and the second cylindrical body extending in the vertical direction. The imaging device C is attached to the upper surface opening side of 92, and the inspection object W is placed on the lower surface opening of the box 93.

  As shown in the cross-sectional view of FIG. 2 and the simplified optical path diagram of FIG. 3A, the irradiation optical path L1 is formed in an L shape, and is reflected by the first optical path L11 in which the inspection light travels in the horizontal direction. And a second optical path L12 traveling downward.

  On the first optical path L11, the light emission mechanism 1 that emits inspection light in the order in which the inspection light travels, the second diaphragm 32 provided in the vicinity of the light emission mechanism 1, and the light emission mechanism 1 A lens 2 for collecting the emitted inspection light; a first diaphragm 31 provided in the vicinity of the light incident side of the lens 2; a first light-shielding mask M1 provided in the vicinity of the first diaphragm 31; A half mirror 4 provided to be inclined with respect to the reflection light path L2 and the irradiation light path L1 so as to reflect inspection light downward is disposed. Furthermore, a third diaphragm 33 through which the inspection light reflected by the half mirror 4 passes is provided on the second optical path L12. Then, the inspection light that has passed through the third diaphragm 33 from inside the box 93 is irradiated onto the inspection object W.

  In addition, on the reflected light path L2, the third diaphragm 33, the half mirror 4, and the fourth attached to the upper surface of the box 93 are arranged in the order in which the reflected light reflected from the inspection object W proceeds. A diaphragm 34 is provided up to the imaging device C. That is, the half mirror 4 and the third diaphragm 33 are arranged in a portion where the irradiation light path L1 and the reflection light path L2 overlap. The first diaphragm 31, the second diaphragm 32, the third diaphragm 33, and the fourth diaphragm 34 described above are variable diaphragms, and the amount of diaphragm can be changed as appropriate. Further, a fixed aperture with a fixed aperture amount may be used depending on the use mode.

  Hereinafter, the arrangement and configuration of each member will be described in detail.

  The light emitting mechanism 1 has a light source 11 formed of, for example, a chip type LED or the like, and heat radiating fins 12 are projected outward. Further, as shown in the sectional view of FIG. 2, the light emitting mechanism 1 is attached so as to be able to advance and retreat in the axial direction in the first cylindrical body 91 so that the irradiation start position of the inspection light can be adjusted. is there. That is, the inspection light in the inspection object W is changed by changing the positional relationship of the light emission mechanism 1, the lens 2, and the inspection object W independently of the control of the irradiation solid angle by the first diaphragm 31 described later. The irradiation range can be controlled.

  The second diaphragm 32 is provided in the vicinity of the light source 11 of the light emission mechanism 1, and the irradiation area of the inspection light of the light emission mechanism 1 is changed by adjusting the amount of the diaphragm, and the inspection object The irradiation range of the inspection light at W can be changed.

  The first light shielding mask M1 is provided close to the first diaphragm 31, and is a schematic diagram of the first diaphragm 31 and the first light shielding mask M1 when viewed along the optical axis in FIG. As shown in the figure, a circular light-shielding portion M11 is formed in the center portion of the face plate of the transparent glass plate. That is, the light shielding part M11 of the first light shielding mask M1 covers a part of the opening 31a of the first diaphragm 31. The diameter of the light-shielding part M11 is formed smaller than the opening diameter of the first diaphragm 31, and the inspection light emitted from the light emission mechanism 1 passes through the vicinity of the optical axis in the first diaphragm 31. I try to block it. On the other hand, the inspection light passing through the gap between the first diaphragm 31 and the light shielding portion M11 enters the lens 2 and reaches the inspection object W.

  The first diaphragm 31 is provided on the light incident side of the lens 2, and the inspection light that is condensed at each point within the irradiation range with respect to the surface of the inspection object W by the lens 2 is equally irradiated. It is for adjusting the angle. The function related to the control of the irradiation solid angle will be described together with the operation of the first light shielding mask M1 described later.

  The lens 2 is attached to a side opening of the box 93, and is arranged so that an image forming surface, which is an image forming position of the light emitting mechanism, is located in the vicinity of the surface of the inspection object W. is there.

  The first light-shielding mask M1, the first diaphragm 31, and the lens 2 have the following effects. That is, the inclination distribution of the irradiation solid angle at each point of the image plane IM can be adjusted by the positions of the first diaphragm 31 and the first light shielding mask M1 with respect to the lens 2. As shown in FIG. 4, when the first diaphragm 31 and the first light-shielding mask M1 are disposed on the inner side of the focal point on the light emission mechanism 1 side of the lens 2, the outer side of the imaging plane IM is inclined outward. A large amount of irradiated solid angle will be formed. When the first diaphragm 31 is disposed on the focal point on the light emission mechanism 1 side, the irradiation directions of all the irradiation solid angles are parallel to the optical axis, and the first diaphragm 31 is disposed on the lens 2. In the case where it is arranged outside the focal point on the light emission mechanism 1 side, the amount of inclination toward the optical axis increases as the irradiation solid angle is at a point outside the imaging plane IM. In this example, the case where the first diaphragm 31 and the first light shielding mask M1 are provided on the light emitting mechanism 1 side of the lens 2 is described. For example, the first diaphragm 31 and the first light shielding mask M1 are the workpiece. Even when it is provided on the W side, the same effect can be obtained.

  Next, the characteristics of the shape of the light emitting surface LA of the light emission mechanism 1 set based on the shape of the inspection target surface WA of the inspection target W will be described with reference to FIG. In the present embodiment, the light emitting surface LA has the shape of the light source 11 itself. However, for example, the light diffusing plate may be irradiated with light from the light source 11 to form the light emitting surface LA having a predetermined shape. Here, in FIG. 3 and subsequent figures, for simplification of description, the optical path is described in an extended state, and members unnecessary for the description are omitted.

  In this embodiment, the inspection target surface WA has a gentle convex shape protruding toward the lens 2, and the light emitting surface LA is shaped so that the lens 2 forms an image on the entire inspection target surface WA. Is formed. That is, the shape of the light emitting surface LA is set so that each point LE of the light emitting surface LA is imaged by the lens 2 with respect to each point IF of the inspection target surface WA.

  Next, a specific procedure for setting the shape of the light emitting surface LA based on the shape of the inspection target surface WA will be described.

  In FIG. 4, the direction from the inspection object toward the light emitting surface LA along the main optical axis of the lens 2 is set as the Z axis, the depth direction in FIG. 4 is set as the Y axis, and the upward direction in FIG. 4 is set as the X axis. It is. In such a coordinate system, the shape (profile) of the inspection object surface WA has a predetermined cross section of the inspection object W as a reference surface, and the height h from the reference surface to the inspection object surface WA is X, Y. It can be expressed as a function Z = h (X, Y). Although FIG. 4 shows the case where Y is zero, it is obvious that the three-dimensional shape of the inspection target surface WA can be expressed by changing the value of Y.

  In the present embodiment, the distance a from each point IF of the inspection target surface WA to the main surface of the lens 2, and the lens from each point LE of the light emitting surface LA corresponding to each point IF on the inspection target surface WA. The shape of the light emitting surface LA is set so that the distance b to the main surface 2 and the focal length f of the lens 2 satisfy the Gaussian imaging formula 1 / a + 1 / b = 1 / f.

  In other words, the position where an image can be formed on the inspection target point IF can be obtained by drawing a Gaussian imaging formula or an optical path diagram as shown in FIG. That is, by obtaining the positions where images can be formed at the respective points IF, the coordinates to be arranged as the respective points LE of the light emitting surface LA can be calculated, and as a result, the shape (profile) of the light emitting surface LA can be calculated.

  Specifically, when the distance from the main surface of the lens 2 to the reference surface of the inspection object is h0, the distance from a certain inspection target point IF to the main surface of the lens 2 that forms the inspection target surface WA is a = It can be expressed as h0-H (X, Y). The distance b between the light exit point LE corresponding to the inspection target point IF and the main surface of the lens 2 can be expressed by b = af / (af). Further, the distance Lx from the main axis of the lens 2 to the light emission point LE is Lx = − (a / b) using the magnification obtained from a and b and the distance X from the main axis of the lens 2 to the inspection target point IF. Can be represented as X. The reason why the minus sign is attached is to express that the virtual axis connecting the inspection target point IF and the light emission point LE intersects with the main axis to form an inverted real image.

  From these facts, the shape of the light emitting surface LA can be generally expressed as Lz = hL (Lx, Y) = b−bmin using the minimum value bmin of b.

  That is, the shape of the light emitting surface LA can be calculated one-on-one with respect to the coordinates indicating the shape of the inspection target surface WA.

  In the case of the light emitting surface LA set in this way, as is clear from FIGS. 3 and 4, all the light emission points LE are respectively imaged at all the inspection target points IF forming the inspection target surface WA. be able to. That is, the light emission surface LA is imaged on the entire inspection target surface WA which is a curved surface, and uniform light irradiation can be realized.

  Therefore, it is possible to precisely inspect the shape of the inspection target surface WA itself, or to inspect minute defects on the inspection target surface WA.

  A modification of this embodiment will be described with reference to FIGS. In any modification, the shape of the light emitting surface LA is determined by the method shown in FIG.

  As shown in FIG. 5, when the surface WA to be inspected has a concave shape toward the lens 2, the light emitting surface LA is formed as a convex shape toward the lens 2, and light is emitted as in FIGS. The light emitting surface LA is imaged on the entire exit surface.

  Further, as shown in FIG. 6, even if the inspection target surface WA has a complicated uneven shape, the shape of the corresponding light emitting surface LA can be calculated and set similarly. Further, as shown in FIG. 6, even if the inspection target surface WA has such a complicated shape, it is possible to form an image of the light emitting surface LA over the entire surface. Is possible.

  Other embodiments of the present invention will be described.

  As shown in FIGS. 3 to 6, it is not essential that the inspection target surface WA and the central axis of the light emitting surface be coaxial with the main optical axis. For example, as shown in FIG. In this manner, each of them may be arranged inclined with respect to the main surface of the lens. Even in such a case, the shape of the light emitting surface can be set by the same calculation and drawing as described above, and the same effect can be obtained.

  In each of the above embodiments, the entire surface of the inspection object is set as the inspection object surface, but only a part of the inspection object surface may be used as the inspection object surface. Further, the light emitting surface may be only a part rather than the entire part emitting light by the light emitting mechanism. In short, the surface to be inspected and the light emitting surface referred to in the present invention are portions where the relationship of the Gaussian imaging formula is satisfied, and another surface or the like may be formed around the portion. Moreover, the shape of the surface to be inspected is arbitrary, and the shape of the light emitting surface is not limited to that shown in the above embodiments.

  Further, as shown in FIG. 8, the shape and position of one surface of the light diffusing plate DF is set based on the Gaussian imaging formula in accordance with the shape of the inspection target surface WA, and light is emitted from the light source 11 from behind the light diffusing plate DF. May be formed to form the light emitting surface LA. In other words, the light emitting mechanism 1 may be one in which the shape of the light emitting surface LA is set by the light source 11 itself according to the inspection target surface WA, or depending on the shape of the light source 11 and the optical element that shapes the emitted light. A predetermined light emitting surface LA may be formed. In the case of the light source 11 using an LED chip or the like, the substrate is molded according to the shape of the inspection target surface WA, and a desired shape of the light emitting surface LA is obtained by spreading the LED chips on the surface of the substrate. Can do. Further, if the light emitting surface LA is formed by an optical element such as the light diffusion plate DF, the corresponding light emitting surface LA can be easily formed by resin molding or the like even if the inspection target surface WA has a complicated shape. .

  In addition, as shown in FIG. 9, the inspection illumination device 100 has a mask M between the light emitting surface LA and the inspection target surface LA, and an image of the light emitting surface LA is formed on the inspection target surface WA. You may make it form the light irradiation area | region currently imaged and the light-shielding area | region where light is not irradiated. More specifically, when a mask M formed in a lattice shape as shown in FIGS. 9A and 9B is arranged in front of the light emitting surface LA, the inspection object as shown in FIG. Even if the surface WA is a curved surface, it is possible to form a lattice with a clear boundary and limit the inspection area to a very small part, or eliminate reflected light from other than the inspection area, thereby further improving the inspection accuracy.

  In other words, in a conventional inspection illumination device that cannot form an image of the entire light emitting surface even on a curved surface, when the inspection target surface is a curved surface or an uneven surface, the outer edge of the light irradiation region is blurred and the light shielding region In addition, the present invention can solve the problem that part of the light is irradiated and the reflection and scattering of unnecessary light cannot be suppressed, and the inspection accuracy can be improved.

  The mask is not limited to a person who completely blocks light, and may transmit a predetermined amount of inspection light, for example. That is, the light shielding region may be a region where light does not reach completely, or a region where the light amount is reduced with respect to the light irradiation region. Even in such a case, the difference in the amount of light between the light irradiation region and the light shielding region can be accurately adjusted, and it is possible to inspect even those that were conventionally difficult to inspect. Further, as can be seen from the example of FIG. 9, the inspection target surface and the light emitting surface are not continuous surfaces but may be formed discontinuously.

  Although this invention is used for a test | inspection, it is used for various test | inspections, such as a surface test | inspection, an external appearance test | inspection, a shape test | inspection, A use is not specifically limited. The effect of the present invention can be enjoyed as long as inspection is performed based on an image obtained by imaging reflected light and scattered light from the inspection target surface.

  In addition, various modifications and combinations of the embodiments may be performed without departing from the spirit of the present invention.

200: Inspection system 100: Illumination device for inspection 1: Light emission mechanism 11: Light source LA: Light emitting surface LE: Light emission point W: Inspection target WA: Inspection target surface IF: Inspection target point (imaging point)

Claims (10)

Light emitted from the light emitting surface to the inspection target surface using a light emission mechanism having a light emitting surface, a curved or uneven surface to be inspected, and a lens provided between the light emission mechanisms An illumination method for inspection that irradiates
An inspection illumination method, wherein the shape of the light emitting surface is set so that each point of the light emitting surface is imaged by the lens with respect to each point of the inspection target surface.   Distance a from each point on the inspection target surface to the main surface of the lens, distance b from each point on the light emitting surface corresponding to each point on the inspection target surface to the main surface of the lens, focal point of the lens The illumination method for inspection according to claim 1, wherein the shape of the light emitting surface is set so that the distance f satisfies a Gaussian imaging formula 1 / a + 1 / b = 1 / f.   At least a part of an imaginary line connecting each point on the inspection target surface and each point on the light emitting surface corresponding to each point on the inspection target surface intersects the main optical axis of the lens. The illumination method for inspection according to claim 1 or 2, wherein the shape of the light emitting surface is set as described above.   4. The illumination method for inspection according to claim 1, wherein when the surface to be inspected has a convex shape toward the lens side, the shape of the light emitting surface is set so as to form a concave shape toward the lens side. .   4. The illumination method for inspection according to claim 1, wherein when the surface to be inspected has a concave shape toward the lens side, the shape of the light emitting surface is set so as to form a convex shape toward the lens side. 5. . A light emitting mechanism having a light emitting surface, a curved or uneven surface to be inspected, and a lens provided between the light emitting mechanism, and the light emitted from the light emitting surface to the inspection target surface An illumination device for inspection that irradiates,
The illumination device for inspection, wherein the shape of the light emitting surface is formed such that each point of the light emitting surface is imaged by the lens with respect to each point of the inspection target surface.   Distance a from each point on the inspection target surface to the main surface of the lens, distance b from each point on the light emitting surface corresponding to each point on the inspection target surface to the main surface of the lens, focal point of the lens The illumination device for inspection according to claim 6, wherein the shape of the light emitting surface is formed so that the distance f satisfies a Gaussian imaging formula 1 / a + 1 / b = 1 / f.   At least a part of an imaginary line connecting each point on the inspection target surface and each point on the light emitting surface corresponding to each point on the inspection target surface intersects the main optical axis of the lens. The inspection illumination device according to claim 6 or 7, wherein the shape of the light emitting surface is formed as described above.   9. The inspection according to claim 6, wherein when the surface to be inspected has a convex shape toward the lens side, the shape of the light emitting surface is formed so as to form a concave shape toward the lens side. Lighting device.   9. The inspection according to claim 6, wherein when the surface to be inspected has a concave shape toward the lens side, the shape of the light emitting surface is formed so as to form a convex shape toward the lens side. Lighting device.