JP2008096319A - Visual inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual inspection apparatus capable of accurately detecting a defective state, even if defective parts having directionality are present, when the state of formation of an object to be inspected is to be inspected and emitting uniform light within a region of which images are to be acquired. <P>SOLUTION: The visual inspection apparatus 1 is provided with both an illumination device 2 for emitting light to a plane of the object to be measured from an angle and a light-receiving device 6 for receiving reflected light from the plane of the object to be measured, and inspects the appearance of the object to be measured by receiving reflected light reflected at the plane of the object to be measured from among the lights emitted from the illuminating device 2. The illumination device 2 is provided with both a light-emitting part 2a, to which LEDs 21 are mounted planarly and a rotating mechanism 3 for rotating the light-emitting part 2a or the object to be measured, on a straight line as an axis extending perpendicularly from any point, inside a region to be inspected defined as a part or the whole of the plane of the object to be measured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an appearance inspection apparatus for inspecting the appearance of an inspection object, and more particularly to an appearance inspection apparatus that improves inspection accuracy by irradiating light from various directions.

  In general, an article manufactured on a manufacturing line is then inspected for formation by an automatic inspection device or the like. For example, a semiconductor chip or the like is inspected for the presence or absence of cracks, and a printed circuit board or the like is inspected for pads, wiring patterns, silk, resist, and the like formed on the surface thereof. In addition, other articles are also inspected for the presence of prints and scratches formed on the surface thereof.

  Normally, when inspecting the formation state of such an article, as shown in FIG. 6, the surface of the article is irradiated with light from an oblique direction by the LED 21 and the reflected light is received by the light receiving device 6. Inspect. At this time, since the state of the image of the defective portion changes depending on the light irradiation angle, light is irradiated from various directions, and the formation state of the article is inspected from the optimal image.

Regarding the inspection apparatus that irradiates such light, for example, as shown in FIG. 6, an LED 21 is attached to an elongated bar member to irradiate light (such as Patent Document 1), and FIG. As shown in FIG. 8, the LED 21 is attached along the inner curved surface of a hemispherical or semi-cylindrical member, or a thin hollow as shown in FIG. There is one in which a plurality of LEDs 21 are arranged in a circular pattern on the surface of a disk so that light is irradiated (Patent Document 4). According to such an apparatus, by irradiating light from an optimum angle, it is possible to generate black shadows, strong reflected light, or the like at the defective portion, thereby easily finding the defective portion of the article. It becomes like.
JP 2004-226318 A JP 2003-224353 A Japanese Patent Laid-Open No. 10-075051 JP-A-2005-315693

  However, the apparatus as described above causes the following problems. First, when light is irradiated from an elongated bar material as shown in FIG. 6, the light from the bar material is along the normal direction to the surface of the bar material on which the LEDs are arranged side by side. Since it is only irradiated, it is difficult to find cracks or protrusions whose direction matches the direction of the light. As shown in FIGS. 7 and 8, when the LED 21 is attached to a hemispherical or semi-cylindrical member or a hollow disk-like member in an arc shape or a circular shape, light can be irradiated three-dimensionally. Therefore, cracks and protrusions as described above can be found, but when light is emitted from a plurality of LEDs 21 mounted along an arc shape or a circular shape, it is formed by light irradiation from one angle. The black shade will be thinned by the light from the other side, making it impossible to find the defective part. Further, when light is emitted from the LEDs 21 that are arranged on a non-planar shape such as an arc shape or a circular shape, and arranged in different directions as a result, the amount of light irradiated to the inspected region is within the region. If the image acquisition area becomes large, a difference in brightness occurs depending on the location, which makes it impossible to perform inspection accurately.

  Therefore, the present invention has been made paying attention to the above problems, and when inspecting the formation state of an inspection object, even if there is a defective portion having directionality, the defect state is accurately detected. Another object of the present invention is to provide an appearance inspection apparatus capable of performing uniform light irradiation in a region where an image is acquired.

  That is, in order to solve the above-described problems, the present invention provides an illumination device that irradiates light on an inspection object having at least one flat surface obliquely with respect to the plane, and reflected light from the plane of the inspection object. A light receiving device that receives the light, and receives the reflected light reflected by the plane of the inspection object out of the light emitted from the illumination device; A light emitting part having a light emitting member mounted in a plane on the apparatus, and a straight line (hereinafter referred to as “normal line”) extending vertically from any point inside the inspection area defined as all or part of the plane of the inspection object And a rotating mechanism that rotates the light-emitting unit or the inspection object.

  With this configuration, since the planar light emitting member is rotated, even if there is a directional defective portion, the black shadow of the defective portion or strong reflection of the defective portion from the optimum position. Light can be obtained, and the shade is not reduced as it is arranged in an arc shape or a circular shape. In addition, since the inspection object is irradiated with light having a planar shape, luminance unevenness can be eliminated on the inspection object, and a highly accurate inspection can be performed over a wide range.

  Moreover, in such an invention, while attaching a light emission part on a hollow disc, electric power is supplied to the hollow disc by the induced electromotive force from the outside.

  If comprised in this way, it will become unnecessary to connect an electric power supply cable to a light emission part, and it will become possible to eliminate problems, such as twisting of an electric power supply cable by rotation of a hollow disc.

  Further, a plurality of light emitting portions are provided with the normal direction as the center.

  If comprised in this way, it will become unnecessary to rotate a light emission part 360 degree | times, and it will become possible to irradiate light from all directions with a small rotation amount. As a result, the power supply cable can be prevented from being twisted due to a large rotation.

  In the appearance inspection apparatus according to the present invention, since the light emitting unit having the light emitting material attached in a planar shape and the rotation mechanism that relatively rotates the light emitting unit around the normal direction of the region to be inspected are provided. Even if there is a characteristic defective part, it is possible to obtain the black shadow of the defective part and the strong reflected light of the defective part from the optimum position, and the shade is thin as when arranged in an arc shape. There will be no such thing. In addition, since the inspection object is irradiated with light having a planar shape, luminance unevenness can be eliminated on the inspection object, and a highly accurate inspection can be performed over a wide range.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of an appearance inspection apparatus 1 according to the present embodiment, and is an enlarged view of a portion including an illumination device 2 and a light receiving device 6.

  Normally, when there is a defective portion such as a step on the surface of the inspection object 7, when light is irradiated from the low step side to the high side as shown in FIG. 2A, the edge portion on the high step side is strong. The reflected light 9 is reflected toward the light receiving device 6, and the presence of the edge portion can be detected by the strong reflected light 9. Conversely, when light is irradiated from the higher step to the lower step, a black shade 8 is generated on the lower side as shown in FIG. 2B, and the presence of the step can be detected by this black shade 8. it can. However, when light is irradiated in parallel to the wall of the step (that is, in the front-rear direction of the paper surface), it is not possible to generate the strong reflected light 9 due to the black shade 8 or the edge. Can not. Further, when cracks are present on the surface of the inspection object 7, as shown in FIG. 3, when light is irradiated from a direction perpendicular to the groove of the cracks (that is, left and right direction on the paper surface), A black shade 8 is created on the opposite side, and the presence of the groove can be detected. However, if the light is irradiated in the same direction as the groove of the crack (that is, the front-rear direction of the paper surface), it is impossible to detect the black shade 8 or the strong reflected light 9 due to the edge. Further, when light is emitted from the LEDs 21 arranged in an arc shape or a circular shape to such a step or crack, the shade 8 may be thinned, and the presence of the step or crack may not be detected. Therefore, in this embodiment, even when a defective portion having such directionality exists, the parallel light is irradiated so that the presence of the defective portion can be accurately detected, and the parallel light is inspected. By rotating on the object 7, light can be irradiated from various directions. Hereinafter, the appearance inspection apparatus 1 in the present embodiment will be described in detail.

  As shown in FIG. 1, an appearance inspection apparatus 1 according to the present embodiment includes an illumination device 2 that irradiates light on an inspection object 7 from an oblique direction, and an inspection object 7 out of light emitted from the illumination apparatus 2. A light receiving device 6 that receives the reflected reflected light is provided, and the appearance of the inspection object 7 can be inspected by comparing an image received by the light receiving device 6 with reference data. Characteristically, the light emitting unit 2a that irradiates parallel light on the surface of the inspection object 7 obliquely and the rotating mechanism 3 that rotates the light emitting unit 2a about the normal line direction of the region to be inspected are provided. ing. In this embodiment, when inspecting the formation state of the inspection object 7, for example, when inspecting a step or a crack formed on the surface of the semiconductor chip, a pad or wiring formed on the surface of the printed circuit board is used. When inspecting the formation state of patterns, resists, silks, inspecting defective states formed on the surface of liquid crystal substrates, inspecting the printing state of print objects, when inspecting the flatness of flat objects, etc. It can be applied when inspecting the appearance of various articles.

  The illumination device 2 constituting the appearance inspection apparatus 1 includes a light emitting unit 2a that irradiates light on the inspection object 7 from an oblique direction, and a rotating mechanism 3 that rotates the light emitting unit 2a.

  The light emitting portion 2a is formed by attaching a plurality of LEDs 21 to the surface of an elongated flat substrate 20, and the back surface side so as to irradiate light below the hollow portion 24 provided in the central portion of the hollow disc 23. Attached to. These LEDs 21 are set to have an irradiation diffusion angle of about 5 degrees, and the inspection object 7 is irradiated with substantially parallel light by aligning the direction of the optical axis thereof in one direction. In order to irradiate such parallel light from the LED 21, a light closer to parallel light may be irradiated by attaching a Fresnel lens or the like in front of the LED 21. The light emitting unit 2a is attached to the back side of the hollow disk 23 with a screw through the base member 22, and each LED 21 is set to face 30 to 60 degrees below the hollow part 24 of the hollow disk 23. . The light emitting unit 2a may be in a state where the mounting angle of the LED 21 is fixed, or the angle may be arbitrarily changed. As a method of changing this attachment angle, for example, one end side of the substrate 20 to which the LED 21 is attached is attached to the base member 22 by a hinge, and a fixing fitting having a long hole is attached to the other end side and fixed with screws. Can be adopted.

  On the other hand, the rotating mechanism 3 for rotating the light emitting unit 2a includes a hollow disk 23 to which the light emitting unit 2a is attached, and a rotation driving mechanism 31 for rotating the hollow disk 23. The hollow disk 23 is configured to be able to rotate while maintaining a state parallel to the surface of the inspection object 7. The inspection object 7 is moved to the hollow portion 24 on the center side of the hollow disk 23 from the surface. The reflected light is received by the light receiving device 6.

  The rotation drive mechanism 31 rotates the hollow disk 23 and is constituted by a motor that contacts the outer peripheral portion of the hollow disk 23. Then, by driving the rotation drive mechanism 31, an external force is applied from the outer periphery of the hollow disk 23 to rotate the hollow disk 23. In this embodiment, the hollow disk 23 is rotated by a motor that contacts the outer periphery of the hollow disk 23. In addition, a hollow disk is used by using a pulley or a gear as shown in FIG. 23 may be rotated. Then, the hollow disk 23 is rotated 360 degrees by the rotation drive mechanism 31, thereby irradiating the inspection object 7 with parallel light from an arbitrary direction.

  Moreover, in FIG. 1, 4 is an electromotive part and supplies electric power to LED21 of the light emission part 2a. The electromotive unit 4 includes a first coil 41 provided along the outer periphery of the hollow disc 23 and a second coil 42 provided so as to sandwich the front and back surfaces of the outer peripheral portion of the hollow disc 23. And an induced electromotive force is generated in the first coil 41 by generating a high-frequency magnetic field in the second coil 42. Then, the induced electromotive force is rectified by a rectifier circuit (not shown) or the like to supply stable power to the LED 21. As a result, it is not necessary to connect the power supply cable directly to the LED 21, and even when the hollow disk 23 is rotated 360 degrees, problems such as twisting of the power supply cable are eliminated. In addition, when supplying electric power by this electromagnetic induction, it becomes impossible to generate electric power on the first coil 41 side if the hollow disk 23 is entirely made of a metal member. For this reason, while the part in which the 1st coil 41 of the outer peripheral side exists is comprised with nonmetallic materials, such as resin, the inside of the 1st coil 41 is comprised with metal materials etc. with high magnetic permeability. And by pinching | interposing this metal part with the 2nd coil 42, a strong magnetic field is generated in the center part of the 1st coil 41, and a high induced electromotive force is generated.

  Reference numeral 5 denotes a sensor that detects the rotation angle of the hollow disk 23 and is attached along the outer periphery of the hollow disk 23 at predetermined angles. 1 shows a state where the sensor 5 is attached to only one place for the sake of explanation, a plurality of places are actually provided. The sensor 5 includes a light emitting element 51 and a light receiving element 52, and the protrusion 25 provided on the outer periphery of the hollow disk 23 is passed between the light emitting element 51 and the light receiving element 52, thereby passing the sensor 5. The timing is detected and power is supplied to the LED 21. The sensor 5 is provided, for example, every 30 degrees to 60 degrees along the outer periphery of the hollow disk 23 and irradiates light at each angle to acquire an image. In addition, about this angle, the number of sensors 5, an attachment angle, etc., it can change suitably according to the characteristic of the test object 7, etc.

  Reference numeral 6 denotes a light receiving device, which includes a CCD camera or the like that receives reflected light from the inspection object 7. The light receiving device 6 is provided above the hollow portion 24 of the hollow disc 23. If it is difficult to attach the light receiving device 6 above the hollow disc 23, a reflecting mirror or the like is provided above the hollow portion 24 of the hollow disc 23. And may be configured to receive reflected light therefrom.

  Next, a case where the appearance state of the surface of the inspection object 7 is inspected by the appearance inspection apparatus 1 configured as described above will be described.

  For example, when an inspection object 7 having a step as shown in FIG. 2 is inspected, the inspection object 7 is placed on a stage (not shown), and the inspection object 7 is moved to the hollow portion 24 of the hollow disc 23. Let Then, the stage is stopped at the center position of the hollow portion 24 of the hollow disc 23 to rotate the hollow disc 23, and at the same time, the second coil 42 provided so as to sandwich the outer peripheral portion of the hollow disc 23. A high frequency magnetic field is generated, and an induced electromotive force is generated in the first coil 41. And it is set as the state which can supply this electric power to LED21 side.

  When the hollow disk 23 is rotated by the rotation mechanism 3, the projection 25 of the hollow disk 23 passes between the light emitting element 51 and the light receiving element 52 of the sensor 5, and the light blocking state is detected by the light receiving element 52. Electric power is supplied to the LED 21. With the power supply, parallel light is emitted from the light emitting unit, and the reflected light is received by the light receiving device 6. Further, when the hollow disk 23 continues to rotate, the projection 25 passes through the position of the next sensor 5 and the light shielding state is detected, so that light is emitted from a different angle at that time. To do. In this manner, the inspection object 7 is irradiated with light from various directions, and reflected light from a plurality of angles is received by the light receiving device 6.

  When parallel light is irradiated from the light emitting unit in this way, even if the black shade 8 or strong reflected light 9 is not received at the position of the first sensor 5, at the position of the second sensor 5. As shown in FIGS. 2A and 2B, it is possible to obtain the black shade 8 generated on the low step side and the strong reflected light 9 from the edge on the high step side.

  When the light receiving device 6 acquires these reflected lights, these images are temporarily stored in an image memory, and the presence or absence of a step or crack is detected by comparing with normal reference data stored in advance in a storage unit. In this detection, for example, an image is divided into rectangular areas to be inspected, and a histogram including luminance and the number of pixels is generated for each area to be inspected. Then, it is performed by determining whether or not the number of pixels existing within a predetermined luminance width is within a threshold value. Thereby, for example, when there is a pixel that exceeds the threshold within the predetermined luminance width of the luminance region on the bright side, it can be considered that strong reflected light 9 exists, while the threshold within the predetermined luminance width of the low luminance region. If there are more pixels, it can be considered that the black shade 8 exists. The quality of the inspection object 7 is determined from the image thus obtained, and the inspection result is output.

  Thus, according to the above embodiment, the light emitting unit 2a having the LED 21 mounted in a plane and the rotating mechanism 3 that rotates the light emitting unit 2a around the normal direction of the region to be inspected are provided. Even when there is a defective portion having the property, the black shadow 8 or the strong reflected light 9 of the defective portion can be acquired from the optimum position, as in the case of arranging in an arc shape or a circular shape. The shadow 8 is not made thinner. In addition, since the inspection object 7 is irradiated with light configured in a planar shape, unevenness in luminance can be eliminated on the inspection object 7, and a high-precision inspection can be performed over a wide range.

  Further, since the light emitting unit 2a is mounted on the hollow disk 23 and power is supplied to the hollow disk 23 from the outside by an induced electromotive force, it is not necessary to connect a power supply cable to the light emitting unit 2a. It becomes possible to eliminate the twist of the power supply cable due to the above.

  In addition, this invention is not limited to the said embodiment, It can implement in a various aspect.

  For example, in FIG. 1, one light emitting unit 2 a is provided in the hollow disc 23, but a plurality of light emitting units 2 a may be provided as shown in FIG. 5. If a plurality of light emitting portions 2a are attached to the hollow disk 23 in this way, reflected light from all directions can be received without rotating the hollow disk 23 by 360 degrees, and the LED 21 directly. Even when the power supply cable is connected to the power supply cable, the power supply cable is not twisted.

  In addition, in the case where a plurality of light emitting units 2a are provided in this way, the depression angles with respect to the inspected region plane for each light emitting unit 2a may be different. For example, if the angle between the LED 21 and the horizontal direction is set to 30 degrees, 45 degrees, 60 degrees, etc. for each light emitting unit 2a, not only the direction around the rotation axis but also the depression angle with respect to the plane of the inspected area from a plurality of values By selecting, it becomes possible to acquire images under more various irradiation conditions.

  Furthermore, in the said embodiment, although the light emission part 2a is attached to the hollow disc 23, it is not necessary to attach the light emission part 2a to the hollow disc 23, and the mechanism rotated while holding the light emission part 2a. As long as it is provided, it may be attached to any member.

  In addition, in the above-described embodiment, the light emitting unit 2a side is rotated. On the contrary, the inspection object 7 side may be rotated. When the light emitting unit 2a side is rotated, it is not necessary to align the image acquired by the light receiving device 6 and the image of the reference data. On the other hand, when the inspection object 7 side is rotated, There is a merit that problems such as twisting of the power supply cable as in rotating the light emitting section 2a are eliminated.

1 is an external perspective view of an external appearance inspection apparatus according to an embodiment of the present invention. The figure which shows the irradiation state of the light in case the level | step difference has arisen in the test target object The figure which shows the irradiation state of the light in case the crack has arisen in the test object The figure which shows the operation state of the external appearance inspection apparatus in the form Schematic which shows the external appearance inspection apparatus in other embodiment. The figure which shows the external appearance inspection apparatus which arranged LED in the bar material in a prior art example The figure which shows the external appearance inspection apparatus which arranged LED inside the hemispherical member in a prior art example The figure which shows the external appearance inspection apparatus which arranged LED on the hollow disc in a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Appearance inspection apparatus 2 ... Illumination device 2a ... Light emission part 20 ... Board | substrate 21 ... LED
22 ... Base member 23 ... Hollow disc 24 ... Hollow part 25 ... Projection part 3 ... Rotating mechanism 31 ... Rotation drive mechanism 4 ... Electromotive part 41 ... No. One coil 42 ... second coil 5 ... sensor 51 ... light emitting element 52 ... light receiving element 6 ... light receiving device 7 ... inspection object 8 ... shade 9 ... Strong reflected light

Claims (3)

An illumination device that irradiates light onto the inspection object having an at least one flat surface obliquely with respect to the plane, and a light receiving device that receives reflected light from the plane of the inspection object, and is irradiated from the illumination device. In the appearance inspection apparatus that inspects the appearance of the inspection object by receiving the reflected light reflected by the plane of the inspection object among the emitted light, in the illumination device,
A light emitting part having a light emitting member attached in a planar shape, and the light emitting part or the inspection concerned with a straight line extending perpendicularly from an arbitrary point inside the inspection area defined as all or part of the plane of the inspection object An appearance inspection apparatus comprising a rotation mechanism for rotating an object.   The appearance inspection according to claim 1, wherein the light emitting unit is mounted on a hollow disk, and an electromotive unit that supplies electric power from the outside by an induced electromotive force is provided on the hollow disk. apparatus.   The appearance inspection apparatus according to claim 1, wherein a plurality of the light emitting units are provided around the axis.

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