JP2011075534A - Curved-surface appearance inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image inspection apparatus for detecting defects, without fail, by suppressing reflection of illumination obstructing detection of defects to a target having a curved surface of a mirror surface. <P>SOLUTION: Planar lighting systems 3a, 3b are disposed, while an area camera body 1 is covered; a diffusion plate 4 is provided on the front of the planar lighting systems 3a, 3b; a camera unit for reflecting illumination on an inspection target for allowing defects to stand out is mounted to the tip of a perpendicular articulated robot; and the positional relation between the inspection target and the camera unit is held fixed at all times, thus defects existing on the surface of the inspection target having a curved surface of a mirror surface are detected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an appearance inspection apparatus that detects an image captured by a camera by a computer and detects defects on the surface of an object. In particular, the present invention has a width or size that exists on a curved surface having a substantially specular gloss. The present invention relates to an appearance inspection apparatus capable of detecting minute defects of 1 mm or less.

  Until now, the visual inspection of a mirror-like and curved object has been mainly performed by the naked eye, and a method of visually observing the object by changing the angle of the object manually has been performed. A mirror surface with a small curvature is also inspected for defects by reflection using laser light or the like, but there are many problems such as processing capability and processing time, and the target is often limited.

  In addition, for an object having a curved surface that is not a mirror surface, appearance inspection by processing an image with an area camera is effective, and in order to obtain the effective number of pixels necessary for detecting a defect, a plurality of areas are limited. However, in order to keep the focal length of the camera constant with respect to the curved surface, it is necessary to give the camera itself or an object an up / down / left / right or rotational movement.

  In addition, when an object having a mirror surface is captured by an area camera, the camera itself may be reflected, but as a result, objects around the object may also be reflected, thereby hiding defects. Furthermore, when imaging an object with a mirror surface with an area camera, a method of arranging illumination symmetrically with respect to the camera viewing direction is common, but illumination arrangement may be difficult for a curved surface.

  As a method of inspecting a curved surface by image processing, Patent Document 1 discloses a technique using a unit in which an illumination unit in which a plurality of LEDs are arranged and a CCD camera unit are integrated in the same substrate. Patent Document 2 discloses a technique for detecting a defect by irradiating light for each predetermined region and processing a plurality of images captured so that a normal portion of a curved surface appears as a bright portion. ing.

  However, these patent documents do not necessarily fully disclose a technique that can cope with the above-described problems.

  JP 2007-278713 A   JP 2008-026149 A

  Therefore, the subject of this invention is providing the curved-surface external appearance inspection apparatus which enables the external appearance inspection of the target object which has a curved surface of a mirror surface using an area camera.

  The present invention uses a combined structure of a camera, a lighting device, and an articulated robot in order to use an area camera as a means for detecting defects such as cracks, scratches, and pinholes existing on the surface of an object having a mirror surface. It was made as a result of examination.

  That is, the present invention provides an area camera, a plurality of planar illumination devices arranged so as to form a certain angle with the axial direction of the area camera, and the area camera. An imaging unit having a diffusing plate for diffusing illumination light from the illumination device; and an articulated robot having a function of controlling a position and an angle of the imaging unit with respect to an object to be imaged; A curved surface appearance inspection apparatus having a function of detecting a defect of the object from an image obtained by irradiating and imaging the object.

  Moreover, the present invention is the curved surface appearance inspection apparatus, wherein the planar illumination device and the diffusion plate are integrated.

  Further, the present invention is the curved surface appearance inspection apparatus, wherein a range in which the illumination light irradiates the object is wider than a field of view of the area camera.

  Since the curved surface appearance inspection apparatus according to the present invention has the above-described structure, the articulated robot can arbitrarily adjust the focal point of the area camera and the angle with respect to the object. In addition, the illumination device irradiates the object with the illumination light of the planar illumination device arranged around the area camera via the diffusion plate, so that it is possible to irradiate the object with uniform illumination light. The reflection can be suppressed, and the reflection of the illumination device itself on the object can also be suppressed. In addition, in the present invention, since the planar illumination device and the diffusion plate are integrated and attached to the articulated robot, the state of the illumination light is extremely less affected by the operation of the articulated robot.

  The size of the illuminating device is calculated from the visual field size of the area camera and the distance between the area camera and the object, and as a light source, a plurality of LEDs are arranged at regular intervals to form a planar illuminating device, or an organic EL Although a planar light emitter such as an element can be used, as described above, the brightness of the entire surface can be uniformly adjusted using a diffusion plate. As a result, the object can be illuminated with uniform light, and defects existing on the uniform surface of the object are emphasized and detected.

  In addition, by making the range in which the illumination light illuminates the object wider than the field of view of the area camera, the area camera's field of view can be adjusted even if the area camera axis is not perpendicular to the surface of the object. Can be sufficiently covered, so that defects can be reliably detected. Furthermore, troubles caused by the area camera capturing the reflected image of the area camera itself can be reduced.

  A computer is used to process the captured image. However, as a method for processing, in order to exclude the influence of unevenness in the density of the image due to illumination, the threshold value is changed for each partial region of the image to perform binary processing. It is desirable to use dynamic threshold processing that performs the conversion. In addition, since the operation control of the articulated robot is also performed by a computer, it is possible to add a teaching function and ensure the same inspection position, which is a necessary condition when inspecting a mass-produced object. it can.

  According to the present invention, it is possible to make an appearance inspection of an object having a mirror-like curved surface, which has been the mainstream until now, an inspection using an area camera. Image inspection with an area camera prevents human oversight, makes it possible to quantify ambiguous criteria, and saves defects as image data, enabling database construction for quality improvement. It becomes possible.

  The figure which shows an example in arrangement | positioning of the area camera which concerns on the curved-surface external appearance inspection apparatus of this invention, and a planar illuminating device, Fig.1 (a) is a front view, FIG.1 (b) is a side view.   The figure which shows the state which attached the camera unit which concerns on the curved-surface external appearance inspection apparatus of this invention to the articulated robot, FIG. 2 (a) is a front view, FIG.2 (b) is a side view.   The figure which shows an example of the setting of the position of the camera unit which concerns on the curved-surface external appearance inspection apparatus of this invention, and a test target object.   The figure which showed the state of the reflection of the illumination to the test target object concerning the curved-surface external appearance inspection apparatus of this invention, FIG.4 (a) is a case where a test target object is a plane, FIG.4 (b) is a test target object is a curved surface In the case of FIG. 4 (c), the inspection object is a curved surface and multifaceted.

  Next, embodiments for carrying out the present invention will be described with reference to the drawings.

  1A and 1B are diagrams showing an example of the arrangement of an area camera and a planar illumination device according to the curved surface appearance inspection apparatus of the present invention. FIG. 1A is a front view and FIG. 1B is a side view. In FIG. 1, 1 is an area camera body, 2 is a lens, 3a and 3b are planar illumination devices, 4 is a diffuser plate, 5 is a fixing case, and 6 is a flange.

  The lens 2 is appropriately selected according to the field of view. Further, in this example, the planar illumination devices 3a and 3b are installed so as to form a certain angle with the area camera body 1 according to the angle of the diffusion plate 4 above and below the area camera body 1 in the drawing. . More specifically, when the diffusing plate 4 is a curved surface, it is desirable that the vertical line passing through the centers of the planar lighting devices 3 a and 3 b is aligned with the normal line of the diffusing plate 4. The distance between the planar lighting devices 3a and 3b and the diffusion plate 4 is a position where the entire diffusion plate 4 is irradiated with illumination light.

  The diffusing plate 4 is made of a transparent polymer material such as an acrylic polymer material or a polycarbonate material, which is provided with fine irregularities on the surface or in which a material that scatters light is dispersed. As described above, the illumination light of the devices 3a and 3b is used for further diffusing the illumination light at random, and has a function of uniformly illuminating the object having a specular curved surface. Furthermore, the effect which expands the irradiation range of illumination light is acquired by providing an angle so that the curved surface of a target object may be covered, or making it curved surfaces, such as R surface.

  The area camera body 1, the planar illumination devices 3 a and 3 b, and the diffusion plate 4 are arranged and fixed in a fixing case 5 and attached to the articulated robot via the flange 5.

  2A and 2B are views showing a state in which the camera unit according to the curved surface appearance inspection apparatus of the present invention is attached to the articulated robot. FIG. 2A is a front view and FIG. 2B is a side view. In FIG. 2, 7 is an articulated robot, 8 is a camera unit in which an area camera body 1, a lens 2, planar illumination devices 3a and 3b and a diffusion plate 4 are assembled, and 9 is an inspection object.

  As shown in FIG. 2, in the present invention, in order to make the orientation of the camera unit 8 toward the object 9 and the distance between the camera unit 8 and the inspection object 9 appropriate, It is desirable to use a seven-axis one, and the camera unit 8 is installed on the six-axis part or the seven-axis part of the articulated robot.

  FIG. 3 is a diagram showing an example of setting of the positions of the camera unit and the inspection object according to the curved surface appearance inspection apparatus of the present invention. In FIG. 3, 8a, 8b and 8c are camera units, 10a, 10b and 10c are surfaces perpendicular to the axes of the camera units 8a, 8b and 8c, and 11a, 11b and 11c are camera units 8a, 8b and 8c. A tangent plane at a point where the axis and the inspection object intersect, 12 is an inspection object having a plurality of curved surfaces.

  In the operation of the curved surface appearance inspection apparatus of the present invention, as shown in FIG. 3, the orientation of the camera units 8a, 8b, 8c toward the inspection object 12, the camera units 8a, 8b, 8c and the inspection object It is necessary to appropriately set the distance to 12 in accordance with the state of the surface of the inspection object 12, and the articulated robot is controlled by a computer and teaching is also performed. In the example shown in FIG. 3, since the camera units 8a, 8b, and 8c and the tangent planes 11a, 11b, and 11c are not orthogonal, it is possible to avoid reflection of the camera units 8a, 8b, and 8c themselves on the imaging screen. .

  FIG. 4 is a diagram showing a state of illumination reflected on the inspection object according to the curved surface appearance inspection apparatus of the present invention. FIG. 4 (a) shows a case where the inspection object is a plane, and FIG. Is the case where the inspection object is a curved surface, and FIG. 4C is the case where the inspection object is a curved surface and has many surfaces.

  As described above, it is necessary to appropriately adjust the direction and distance of the camera unit 8 depending on the state of the inspection object as shown in FIG. 4, but FIG. In this example, the camera unit 8 is inclined with respect to the surface of the object 14, and the illumination can be reflected on the entire detection surface by adjusting the angle of the diffusion plate. Although FIG. 4B is a curved surface, illumination can be similarly reflected. In FIG. 4C, the object to be inspected is a multi-faceted curved surface, but a portion other than the partial illumination is shown. In this case, inspection can be performed by setting the orientation and position of the camera unit 8 so as to divide and capture multiple faces.

  As described above, according to the present invention, it is possible to provide a curved appearance inspection apparatus that can reliably and easily perform an appearance inspection of a curved surface of a mirror surface, which has been difficult to detect with a defect in the conventional appearance inspection apparatus. The appearance inspection efficiency of painted cars can be greatly improved. It should be noted that the present invention is not limited to the above-described embodiment, and can be conceived by those having ordinary knowledge in the field of the present invention, and design changes within a range not departing from the gist including various modifications and corrections Of course, the present invention is included in the present invention.

DESCRIPTION OF SYMBOLS 1,10 Area camera main body 2,11 Lens 3a, 3b Planar illuminating device 4 Diffuser 5 Fixing case 6 Robot mounting flange 7 Articulated robot 8, 8a, 8b, 8c Camera unit 9, 12 Inspection object 10a, 10b , 10c Surfaces 11a, 11b, 11c perpendicular to the axis of the camera unit 12 Tangential plane at the point where the axis of the camera unit intersects the inspection object 12 Illumination unit

Claims (3)

  An area camera, a plurality of planar illumination devices arranged to form a certain angle with the axial direction of the area camera, and arranged around a lens of the area camera, and illuminating light from the planar illumination device An imaging unit having a diffusion plate for diffusing, and an articulated robot having a function of controlling a position and an angle of the imaging unit with respect to an object to be imaged; A curved surface appearance inspection apparatus having a function of detecting a defect of the object from an obtained image.   The curved surface appearance inspection apparatus according to claim 1, wherein the planar illumination device and the diffusion plate are integrated.   The curved surface appearance inspection apparatus according to claim 1, wherein a range in which the illumination light irradiates the object is wider than a field of view of the area camera.

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