JP2005158490A - Ring-shape lighting device for image processing inspection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ring-shape lighting device for image processing inspection having an improved uniformity of illumination intensity distribution on the irradiation surface and a high illumination intensity realized. <P>SOLUTION: This is a ring-shape lighting device for image processing inspection L which comprises a doughnut shape substrate 1 having an aperture for photographing by a CCD camera or the like in the center part and a ring-shape light source 3 composed of a plurality of LEDs 2 that are arranged at prescribed spacings on the bottom side of this substrate 1 and emit light in the prescribed light distribution region, and illuminates the restricted irradiation range by emitting light from the ring-shape light source 3. A cylindrical diffusive reflection outer tube 4 which is arranged at the outside of the ring-shape light source 3 and diffusion reflects the emitting light from the ring-shape light source 3 toward the irradiation surface and a diffusive reflection inner tube 5 which is arranged at the inner side of the ring-shape light source 3 and is shorter than the diffusive reflection outer tube 4 are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ring illumination device for image processing inspection for illuminating a test object when the quality of the test object such as an industrial product is inspected by an image processing inspection method using imaging of a CCD camera.

  As a method of inspecting the quality of industrial products such as printed circuit boards and semiconductors, for example, defective soldering, defects, adhesion of foreign substances, etc. and printing errors such as the date of manufacture of drinking cans on a production line, a CCD camera For example, an image processing inspection method using photographing by the method is used. This inspection method is to inspect the presence / absence of an abnormality by photographing a specific part of the product and comparing it with the photographing result of a normal product. In such an inspection method, it is necessary to illuminate the test object brightly and uniformly, and for example, a ring-type illumination device or a dome-type illumination device is used as the illumination device.

In the ring illumination device as described above, a ring-shaped light source is configured by densely mounting a plurality of LEDs on the concave surface side of a printed wiring board configured in a truncated cone shape, and the emitted light from this ring-shaped light source is emitted. The irradiated surface is directly irradiated (directly irradiated). Further, in the dome type illumination device, a light beam emitted from a ring-shaped light source configured by arranging a plurality of LEDs in a ring shape is diffusely reflected by a dome-shaped diffuse reflection member, and this irradiation surface is irradiated with this diffuse reflection light. .
JP 2002-117706 A

  However, in the ring type illumination device described in the above-mentioned patent document, since the light from the ring-shaped light source is directly irradiated on the irradiation surface, the illuminance on the irradiation surface is high, but the illuminance unevenness occurs, and the illuminance distribution on the irradiation surface The uniformity will be low. At this time, generally, the illuminance at the center of the irradiation range on the irradiation surface is the highest. Therefore, since the surface of the test object placed on the irradiation surface is not illuminated uniformly, there arises a problem that appropriate image processing inspection cannot be performed. On the other hand, in the dome type illumination device, the illuminance unevenness is small and the uniformity of the illuminance distribution on the irradiated surface is high, but the illuminance is lower than the direct light, and the desired illuminance necessary for the image processing inspection cannot be obtained. The problem will arise. Moreover, since the light diffusely reflected by the dome-shaped diffuse reflection member spreads widely outside the required irradiation range, a useless irradiation area that is not used is generated.

  In addition, for example, when inspecting a test object having a mirror surface such as a date printed on an aluminum pack or a stamped character, when the test object is illuminated by direct light from a ring illumination device, There is a problem that glare occurs due to unevenness on the surface, and there are many specular reflection components reflected by the test object, so that the amount of light taken into the CCD camera is small. Further, due to this specular reflection component, an image of the LED constituting the ring-shaped light source appears on the surface of the object to be examined, and the CCD camera captures it, which causes a problem that appropriate image processing inspection cannot be performed. On the other hand, when the object is illuminated with diffusely reflected light from the dome-shaped illumination device, the problem that the LED image is reflected on the surface of the object is solved, but irradiation is performed in comparison with direct light. Since the illuminance at the surface is lowered, there arises a problem that desired illuminance necessary for the image processing inspection cannot be obtained.

  The present invention is intended to solve such problems of the prior art, and the object is to clarify the boundary between the irradiation range and the non-irradiation range, and to distribute the illuminance on the irradiation surface. Another object of the present invention is to provide a ring illumination device for image processing inspection that can improve the uniformity of the image processing and can obtain high illuminance.

  In order to achieve the above object, the present invention provides a ring comprising a donut-shaped substrate having an opening for photographing with a CCD camera or the like at the center, and a plurality of LEDs arranged at predetermined intervals on the lower surface of the donut-shaped substrate. In the ring illumination device for image processing inspection provided with a ring-shaped light source, the ring-shaped light source is disposed outside the ring-shaped light source, restricts the light distribution of emitted light from the ring-shaped light source to the outside, and the ring-shaped light source. An inner surface of the diffuse reflection outer cylinder, and an inner surface of the diffuse reflection outer cylinder has an inclined surface whose inner diameter expands toward the irradiation surface. It is characterized by comprising.

  The second aspect of the present invention is shorter than the diffuse reflection outer cylinder that is disposed inside the ring light source and diffuses and reflects the emitted light from the ring light source toward the diffuse reflection outer cylinder. A third aspect of the present invention includes a ring-shaped transmissive diffusion plate provided in the diffuse reflection inner cylinder and disposed in close proximity to the ring-shaped light source. According to a fourth aspect of the present invention, the diffuse reflection outer cylinder includes a cylinder length adjusting means capable of adjusting a cylinder length.

  According to the ring illumination device for image processing inspection of the present invention, the illumination surface is illuminated with both the direct light from the ring light source and the diffuse reflection light diffusely reflected by the diffuse reflection outer cylinder. It is possible to provide a ring illumination device for image processing inspection that can improve the uniformity of the irradiation distribution and can obtain high illuminance. In addition, since the light distribution from the ring-shaped light source to the outside is restricted by the diffuse reflection outer cylinder, the boundary between the irradiation range and the non-irradiation range becomes clear, and a useless irradiation region is eliminated. As a result, it is possible to irradiate with a constant illuminance no matter where the test object is placed within the irradiation range, so that positioning when placing the test object on the irradiation surface becomes easy.

  Even when inspecting a specimen having a specular surface, direct light from a ring-shaped light source can be obtained by attaching a ring-shaped transmissive diffuser plate to a diffuse reflection inner cylinder so as to be in close proximity to the ring-shaped light source. Since the test object is not irradiated, the specular reflection component reflected by the test object is not taken into the CCD camera. That is, the problem that the CCD camera captures an image of the LED constituting the ring-shaped light source reflected on the surface of the test object is solved. As a result, an appropriate image processing inspection can be performed, and the test object can be illuminated with high illuminance.

  An embodiment of a ring illumination device for image processing inspection (hereinafter referred to as a ring illumination device) according to the present invention will be described below with reference to FIGS. 1 is a schematic perspective view showing a ring illumination device according to the present invention, FIG. 2 is a cross-sectional view taken along line M-M ′ in FIG. 1, and FIG. 3 is a plan view showing the ring illumination device of the present invention.

  The ring-shaped illumination device L of the present invention includes a donut-shaped substrate 1, a ring-shaped light source 3 composed of a plurality of LEDs 2 disposed on the donut-shaped substrate 1, and a diffuse reflection outer cylinder 4 disposed outside the ring-shaped light source 3. And a diffuse reflection inner cylinder 5 disposed inside the ring-shaped light source 3. Also, the donut-shaped substrate 1, the diffuse reflection outer cylinder 4, and the diffuse reflection inner cylinder 5 are integrally fixed with mounting screws or an adhesive (not shown), respectively.

  First, each component of the ring-shaped illumination device L will be described. The donut-shaped substrate 1 is made of a metal having high thermal conductivity such as aluminum, and is configured in a disk shape having an opening 1a serving as a peephole for photographing with a CCD camera or the like at the center.

  Each LED 2 has a structure in which a chip as a light emitter is packaged with a light transmitting member such as resin or glass. Each LED 2 has a light distribution property, and is composed of a power LED having a wide light distribution property that emits light within a predetermined light distribution region. Each LED 2 is fixed on the donut-shaped substrate 1 at a predetermined interval by an adhesive or soldering so that the optical axis of the LED 2 is parallel to the axis C. As a result, a ring-shaped light source 3 is configured in which a plurality (9 in this embodiment) of LEDs 2 are arranged in a ring shape. Each LED 2 is electrically connected by wiring or lead wires (not shown) on the doughnut-shaped substrate 1, and power is supplied from an external power source (not shown) through the lead wires and the like.

  The diffuse reflection outer cylinder 4 is made of a metal having high thermal conductivity such as aluminum and is formed in a cylindrical shape, and is arranged on the outside of the ring-shaped light source 3 and the donut-shaped substrate 1 and mounting screws or an adhesive (see FIG. (Not shown). Heat generated from the LED 2 can be transmitted to the diffuse reflection outer cylinder 4 having high thermal conductivity to be dissipated. The inner surface of the diffuse reflection outer cylinder 4 is subjected to a predetermined surface treatment (for example, coating with magnesium fluoride or the like) so that light is diffusely reflected, and the inner diameter of the diffuse reflection outer cylinder 4 expands toward the irradiation surface X. It is composed on the surface. In this embodiment, the inclination is about 5 degrees. The diffuse reflection outer cylinder 4 suppresses (that is, regulates) the outward light distribution of the emitted light from the ring light source 3 and diffusely reflects the emitted light from the ring light source 3 toward the irradiation surface X. It has a function to make it.

  The diffuse reflection inner cylinder 5 is made of a metal having high thermal conductivity such as aluminum and is formed in a cylindrical shape, and is arranged on the inner side of the ring-shaped light source 3 and the donut-shaped substrate 1 and mounting screws or an adhesive (see FIG. (Not shown). Heat generated from the LED 2 can be transmitted to the diffuse reflection inner cylinder 5 having high thermal conductivity to be dissipated. The outer surface of the diffuse reflection inner cylinder 5 is subjected to a predetermined surface treatment (for example, coating with magnesium fluoride or the like) so that light is diffusely reflected. Further, the length of the diffuse reflection inner cylinder 5 in the axis C direction (hereinafter referred to as the cylinder length) is configured to be shorter (that is, shorter) than the cylinder length of the diffuse reflection outer cylinder 4. Furthermore, the cylinder length of the diffuse reflection outer cylinder 4 is configured such that the illuminance distribution on the irradiation surface X and the illuminance are optimal.

  Next, operation | movement of the ring-shaped illuminating device L comprised as mentioned above is demonstrated using FIG. First, the ring-shaped illumination device L is installed above the irradiation surface X so that the ring-shaped light source 3 is substantially parallel to the irradiation surface X. At this time, each LED 2 is arranged on the lower surface of the donut-shaped substrate 1 so that each LED 2 faces the irradiation surface X side. When power is supplied to each LED 2, each LED 2 emits light. The LED 2 emits heat when the LED 2 emits light, but the heat generated from each LED 2 is transferred to the donut-shaped substrate 1, the diffuse reflection outer cylinder 4, and the diffuse reflection inner cylinder 5 and is radiated to the atmosphere.

  For convenience of explanation, FIG. 2 shows only the optical path of the emitted light from the LED 2 located on the left side of the drawing. Further, the illustrated optical path is only for a part of the emitted light rays, and it goes without saying that there are actually many other emitted light rays (the same applies to FIG. 4). For example, the LED 2 emits light within a light distribution region of an angle θ1 + θ2 + θ3. The emitted light beam from the LED 2 in the range of the angle θ1 is directly reflected from the LED 2 toward the irradiation surface without being diffusely reflected by the inner surface of the diffuse reflection outer cylinder 4 and the outer surface of the diffuse reflection inner cylinder 5, and irradiated as direct light. The surface X is irradiated. At this time, the cylindrical length of the diffuse reflection inner cylinder 5 is configured such that the diffuse reflection inner cylinder 5 does not block the direct light irradiated from the LED 2 onto the irradiation surface X.

  In addition, the emitted light beam from the LED 2 in the range of the angle θ2 is diffusely reflected by the inner surface of the diffuse reflection outer cylinder 4 (see the enlarged view in FIG. 2), and irradiated to the irradiation surface X as diffuse reflection light. Thereby, the diffuse reflection outer cylinder 4 regulates the outward light distribution of the emitted light from the ring-shaped light source 3. Furthermore, the emitted light beam from the LED 2 in the range of the angle θ3 is diffusely reflected on the outer surface of the diffuse reflection inner cylinder 5 and then travels toward the diffuse reflection outer cylinder 4. Then, the light is further diffusely reflected by the inner surface of the diffuse reflection outer cylinder 4 and irradiated to the irradiation surface X as diffuse reflection light.

  Since each LED 2 is arranged in a ring shape, the direct light from each LED 2 overlaps on the irradiation surface X, and as a result, the direct light is the illuminance at the center of the irradiation range X ′ (see FIG. 1) of the irradiation surface X. There is an effect of enhancing the. Further, the diffusely reflected light from each LED 2 has an effect of increasing the illuminance near the outer periphery of the irradiation range X ′. As a result, the illuminance is substantially uniform over the entire irradiation range X ′.

  As described above, the irradiation surface X is irradiated by both direct light from each LED 2 and diffuse reflection light, and the uniformity of the illuminance distribution in the irradiation range X ′ is increased, and in the irradiation range X ′. The illuminance increases. At this time, the shape of the irradiation range X ′ of the irradiation surface X is a shape having a polygonal outer periphery, and the illumination intensity is almost the same at any point in the irradiation range X ′.

  Therefore, it becomes possible to always illuminate the surface of the test object Y with a substantially constant illuminance regardless of where the test object Y is placed within the irradiation range X ′, and alignment of the test object Y during the inspection is performed. Can be done easily. Further, the outer periphery of the irradiation range X ′, that is, the boundary between the irradiation range X ′ and the non-irradiation range is clear, and the illumination does not spread outside the necessary irradiation range X ′ as in the prior art. Therefore, a useless irradiation area does not occur, and the light from the LED 2 can be efficiently guided to the irradiation surface X.

  An image processing inspection method using the ring illumination device L of the present invention will be briefly described with reference to FIG. The test object Y is placed in the irradiation range X ′ below the ring illumination device L, and the surface of the test object Y is illuminated from above the test object Y. A CCD camera Z is installed on the upper part of the ring-shaped illuminating device L. The test object Y is photographed from the opening 1a of the donut-shaped substrate 1 using the CCD camera Z, and the image signal obtained by photographing is imaged on a personal computer or the like. (Not shown) for image processing inspection.

  FIG. 4 is a cross-sectional view taken along line M-M ′ in FIG. 1 of a ring illumination device according to another embodiment of the present invention. In this figure, the same components as those in FIG.

  In the ring-shaped illumination device L according to this embodiment, the ring-shaped transmissive diffuser plate 6 that is placed in close proximity to the ring-shaped light source 3 is fixed to the periphery of the opening end of the diffuse reflection inner cylinder 5 with a mounting screw or an adhesive. ing. At this time, the transmissive diffusing plate 6 covers emitted light rays in the range of the angle θ1. As a result, light emitted from the LED 2 in the range of the angle θ1 (that is, direct light from the LED 2) is transmitted and diffused by the transmissive diffusion plate 6. Therefore, when inspecting the test object Y having a specular surface placed on the irradiation surface X, the test object Y is not illuminated with direct light, but only with diffuse reflected light and transmitted diffused light. Therefore, the specular reflection component due to direct light is eliminated, the image of the LED 2 is not reflected on the surface of the test object Y, an appropriate image processing inspection can be performed, and the test object Y can be illuminated with high illuminance. .

  FIG. 5 is a cross-sectional view taken along line M-M ′ in FIG. 1 of a ring illumination device according to another embodiment of the present invention. In this figure, the same components as those in FIG.

  In the ring-shaped illumination device L according to this embodiment, the diffuse reflection cylinder 7 for adjusting the tube length is provided on the outer surface of the diffuse reflection outer cylinder 4. The cylinder length adjusting diffusive reflecting cylinder 7 is formed in a cylindrical shape and has an inner diameter slightly larger than the outer diameter of the diffuse reflecting outer cylinder 4, and the inner surface is subjected to a predetermined surface treatment so that light is diffusely reflected. It is. A projection 9 provided at a position corresponding to the long groove 8 is fitted to the inner surface of the diffuse reflection cylinder 7 for adjusting the tube length in the long groove 8 in the axis C direction provided at a plurality of positions on the outer surface of the diffuse reflection outer cylinder 4. The protrusion 9 moves along the long groove 8 by sliding the adjusting diffuse reflection cylinder 7 in the direction of the axis C. As a result, the diffuse reflection cylinder 7 for adjusting the cylinder length slides on the outer surface of the diffuse reflection outer cylinder 4, and the cylinder length of the diffuse reflection outer cylinder 4 can be arbitrarily changed. The emitted light from the ring-shaped light source 3 is diffusely reflected by the inner surface of the cylinder length adjusting diffuse reflector 7, and the same effect as that of the diffuse reflector outer cylinder 4 is obtained. By increasing the length of the diffuse reflection outer cylinder 4, the uniformity of the irradiation distribution on the irradiation surface X can be increased.

  Each of the above-described embodiments is merely an example of the present invention, and it is obvious that modifications and modifications as appropriate within the spirit of the present invention are included in the claims of the present application. For example, in this embodiment, the heat generated from the LED is transferred to the donut-shaped substrate, the diffuse reflection outer cylinder, and the diffuse reflection inner cylinder to dissipate heat in the atmosphere. You may make it radiate heat from this radiation fin. Alternatively, the diffuse reflection inner cylinder may be used as a support member for simply supporting the transmissive diffuse reflection plate without performing the diffuse reflection surface treatment on the outer surface thereof.

The schematic perspective view which shows the ring-shaped illuminating device by one Example of this invention. FIG. 2 is a sectional view taken along line M-M ′ in FIG. 1. The top view which shows the ring-shaped illuminating device by one Example of this invention. The M-M 'sectional view taken on the line in FIG. 1 by the other Example of this invention. FIG. 6 is a cross-sectional view taken along line M-M ′ in FIG. 1 according to still another embodiment of the present invention.

Explanation of symbols

L Ring-shaped illumination device 1 Donut-shaped substrate 1a Opening 2 LED
DESCRIPTION OF SYMBOLS 3 Ring-shaped light source 4 Diffuse reflection outer cylinder 5 Diffuse reflection inner cylinder 6 Transmissive diffuse reflection board 7 Diffuse reflection cylinder for cylinder length adjustment 8 Long groove 9 Protrusion X Irradiation surface X 'Irradiation range Y Test object Z CCD camera

Claims (4)

  A ring shape for image processing inspection, comprising a donut-shaped substrate having an opening for photographing with a CCD camera or the like in the center, and a ring-shaped light source composed of a plurality of LEDs arranged at predetermined intervals on the lower surface of the donut-shaped substrate In the illuminating device, the light source is disposed outside the ring-shaped light source, restricts the light distribution of the emitted light from the ring-shaped light source to the outside, and faces an irradiation surface located inside and below the ring-shaped light source. A cylindrical diffuse reflection outer cylinder that diffusely reflects the inner surface of the diffuse reflection outer cylinder, and an inner surface of the diffuse reflection outer cylinder is configured to have an inclined surface that expands toward the irradiation surface. Ring lighting device.   It is disposed inside the ring-shaped light source, and includes a diffuse reflection inner cylinder that is shorter than the diffuse reflection outer cylinder that diffuses and reflects the emitted light from the ring light source toward the diffuse reflection outer cylinder. The ring illumination device for image processing inspection according to claim 1.   The ring-shaped illumination device for image processing inspection according to claim 2, further comprising a ring-shaped transmissive diffuser plate provided in the diffuse reflection inner cylinder and disposed in close proximity to the ring-shaped light source.   4. The ring-shaped illumination device for image processing inspection according to claim 1, wherein the diffuse reflection outer cylinder includes a cylinder length adjusting unit capable of adjusting a cylinder length.

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