JP2016006382A - Appearance inspection apparatus and method - Google Patents

Abstract

[Purpose] Enables detection of extremely thin cracks. [Structure] A plate-like object 90 having at least one resin layer 92 formed on at least one surface of the substrate is warped by the warping mechanism 70 so that the surface on which the resin layer is formed is convex. At least the surface of the resin layer of the plate-like object is imaged by the image sensor 11, an image signal representing the image is acquired, and at least the presence or absence of a crack is determined based on the acquired image signal. [Selection] Figure 10

Description

  The present invention relates to an appearance inspection apparatus and method.

  Various types of visual inspection apparatuses have been developed that detect defects generated in fine patterns formed on the surface of semiconductor substrates, metal substrates, tape carriers, and the like. For example, Patent Document 1 describes a tape carrier defect detection device and a defect detection method. This is to detect defects in leads formed on a tape carrier, and relates to image processing in which a lead on a tape carrier is imaged by a CCD camera and applied to a digitized image signal.

  That is, first, binarization processing is performed on the inspection target image, the binarized image is expanded, and the number of expansions is larger than the number of expansions in the expansion processing. Apply shrinkage treatment. The image data that has been subjected to the expansion / contraction process is compared with the binarized image data before expansion / contraction to detect a chip generated in the lead corresponding to the binarized image data.

  Further, the binarized image is subjected to a contraction process, and the expansion processing is performed on the image data subjected to the contraction process more times than the number of contractions in the contraction process. The image data that has been subjected to the contraction / expansion process is compared with the binarized image data before the contraction / expansion, and a protrusion generated on the lead corresponding to the binarized image data is detected.

JP-A-11-224892

  In the image processing described in Patent Document 1, there is a problem that a micro defect may not be detected because a contour (edge) portion of a product remains due to the expansion / contraction process and the contraction / expansion process. In addition, there is a problem with the target image itself before image processing.

  In other words, no matter how precise the image processing is, if a defect is not expressed in the image to be processed, it cannot be detected. For example, cracks (cracks) generated by drying of the resin are very narrow, and depending on the resolution of the image sensor, they may not appear on the image signal obtained by the image sensor.

  The present invention provides an appearance inspection apparatus and method that can detect even a crack having a very narrow line width.

  Another object of the present invention is to detect various defects including the cracks.

  The present invention further seeks to detect defects on both the front and back surfaces of a plate-like (film-like, plate-like, thin-plate-like) object.

  The visual inspection apparatus according to the present invention includes a warping mechanism for warping a plate-like inspection object so that at least one surface to be inspected for cracks is convex, and the surface of the one surface of the warped plate-like object. An image sensor for acquiring an image signal representing an image, and an image processing means for determining at least the presence or absence of a crack based on the image signal acquired by the image sensor.

  The visual inspection method according to the present invention warps a plate-shaped inspection object so that at least one surface to be inspected for cracks is convex, and images the surface of the one surface of the plate-shaped object in a warped state. A first image signal representing the image obtained by imaging with a sensor is acquired, and at least the presence or absence of a crack is determined based on the acquired first image signal.

  The plate-like inspection object is preferably one that can be bent and warped relatively easily by applying an external force. The plate-shaped inspection object is preferably a sheet, a film, or a thin plate. The warping mechanism may be configured to press the plate-like inspection object at at least two points spaced apart and to press in the direction opposite to the pressing direction between the two points.

  By bending the surface to be inspected so that the surface to be inspected is convex, even if there is an extremely thin crack (crack, etc.) on the surface to be inspected, the width of the image sensor is increased. Even if the resolution is low, a crack with an enlarged width appears clearly on the image acquired by the image sensor. Therefore, even a crack with a very narrow line width can be detected.

  Cracks are likely to occur on the surface of a laminate of at least two layers having different thermal shrinkage rates. The surface layer may be partially present.

  Specific examples of such a laminate of at least two layers include those in which at least one resin layer is formed on a substrate. The resin layer may be present only on a part of the substrate and not on the entire surface.

  An appearance inspection apparatus according to the present invention for inspecting a plate-like object having at least one resin layer formed on at least one surface of such a substrate is warped so that the surface on which the resin layer is formed is convex. A mechanism, a first image sensor that obtains a first image signal representing an image of at least the surface of the resin layer of the warped plate-like object, and the first image sensor obtained by the first image sensor; First image processing means for determining at least the presence or absence of a crack based on one image signal is provided.

  In addition, such a method for inspecting the appearance of a plate-like object is such that a plate-like object on which at least one resin layer is formed on at least one surface of the substrate is convex on the surface on which the resin layer is formed. The image of at least the resin layer of the plate-like object in the warped state is imaged by an image sensor to obtain an image signal representing the image, and at least whether or not there is a crack based on the obtained image signal Judgment.

  Since the plate-like object is warped so that the surface on which the resin layer is formed is convex, even a fine crack existing in the resin layer appears on the image of the image sensor as a crack whose width is enlarged. , Easy to detect.

  In one embodiment, the warpage mechanism includes at least three rollers disposed along a conveyance path of the plate-like object, and two of these rollers are spaced apart from each other during conveyance. The plate-like object is disposed so as to come into contact with and press the one surface on which the resin layer is formed, and the other one roller is between the two rollers and is being transported. It arrange | positions so that the other surface of a plate-shaped object may be contacted and the said other surface may be pressed. Preferably, the surfaces of these rollers are covered with an elastic body. The roller is, for example, a rubber roller.

  In one embodiment, the first image sensor is a line sensor that acquires an image on a line in a direction orthogonal to a conveyance direction of the plate-like object by the conveyance device, and is a plate that is conveyed by the conveyance device. An image signal of a surface of the object on which the resin layer is formed is acquired.

  In this way, it is possible to detect at least cracks present in the resin layer while conveying the plate-like object.

  In a preferred embodiment, the first image processing means determines the presence or absence of a defect including a crack on the surface of the one surface on which the resin layer of the plate-like object is formed.

  As a result, various defects including cracks can be detected.

  In a further preferred embodiment, the visual inspection apparatus obtains a second image signal representing a second image signal representing an image of the surface of the other surface of the plate-like object having the resin layer formed on at least one surface. The image processing apparatus further includes a sensor and second image processing means for determining the presence or absence of a defect based on the second image signal acquired by the second image sensor.

  Thereby, it becomes possible to detect defects on both the front and back surfaces of the plate-like object.

An overview of the overall configuration of the appearance inspection system is shown. It is a top view of an example of a plate-shaped inspection object. It is an enlarged plan view of a part of a plate-like inspection object. It is sectional drawing which follows the IV-IV line of FIG. It is a top view which shows a part of conveying apparatus. It is an expanded sectional view which follows the VI-VI line of FIG. 5, and shows the state which carries in an inspection target object. It is an expanded sectional view which follows the VI-VI line of FIG. 5, and shows the state which is conveying the test object. It is an expanded sectional view which follows the VIII-VIII line of Drawing 5, and shows a curvature mechanism. The arrangement of the rubber rollers of the warping mechanism is shown. It is a side view which shows the illumination imaging device of the 1st stage of an inspection station. It is a top view which shows the illumination imaging device of the 1st stage of an inspection station. It is a side view which shows the illumination imaging device of the 2nd stage of an inspection station. It is a side view which shows the illumination imaging device of the 3rd stage of an inspection station. It is a side view which shows the illumination imaging device of the 4th stage of an inspection station. It is an enlarged plan view of a part of an inspection object, and shows the presence of a crack. It is an enlarged plan view of a part of an inspection object, and shows a state where a crack is opened by warping. It is a flowchart which shows the whole operation | movement of an external appearance inspection system. It is a flowchart which shows the image processing regarding the 1st or 2nd stage of an external appearance inspection system. It is a flowchart which shows the image processing regarding the 3rd or 4th stage of an external appearance inspection system.

  FIG. 1 shows an overview of the overall configuration of the appearance inspection system.

  A plate-like (plate-like, film-like) inspection object conveyance path 60 is provided in a straight line. The transport path 60 is provided with a carry-in station, four inspection stations, and a carry-out station from the upper side to the lower side (from right to left in FIG. 1). The four inspection stations are sequentially divided into a first stage, a second stage, a third stage, and a fourth stage. A transport device 69 (described later) constituting the transport path 60 is driven and controlled by a transport drive device 61.

  In the vicinity of the carry-in station, an inspection object carry-in device (product supply unit) 81, a magazine 82 on which the inspection object (product) is placed (stacked), and a plate-like (plate-like, film-like) surface of the inspection object A box 84 for storing slip sheets sandwiched between inspection objects for protection is arranged. In the vicinity of the unloading station, an inspection object unloading device 86, an OK magazine 87 for placing an inspection object determined to be non-defective (no defect), and an inspection object determined to be defective (having a defect) are placed. An NG magazine 88 and a box 89 for storing slip sheets sandwiched between inspection objects placed on the magazine 87 or 88 are disposed.

  Image sensors 11, 21, 31, and 41 are arranged on the first, second, third, and fourth stages of the inspection station, respectively. Although the details will be described later, the first and second stages are inspected at a high speed with relatively low resolution. In the first stage, the surface (upper surface) of the object to be inspected, and in the second stage, the back surface of the object to be inspected (upper surface) Each bottom surface is inspected. The image sensors 11 and 21 arranged on these stages are line sensors, which sequentially take images of the front and back surfaces of the inspection object being conveyed and acquire the image signals (data).

  The third and fourth stages of the inspection station inspect the area including the defect candidate on the inspection object detected in the first or second stage with high resolution and high definition. The fourth stage inspects defect candidates on the front surface (upper surface), and the fourth stage inspects defect candidates on the rear surface (lower surface) of the object. The image sensors 31 and 41 arranged on these stages are two-dimensional image sensors that image areas including defect candidates on the front and back surfaces of an object, and acquire image signals (data) thereof.

  Image signals (image data) output from these image sensors 11, 21, 31, and 41 are respectively supplied to the image processing devices 12, 22, 32, and 42, and image processing that will be described in detail later is executed. The image processing results in these image processing devices 12, 22, 32, and 42 are sent to the central device 50 for final pass / fail judgment, totalization, and the like. These pass / fail judgment results and aggregated data are given to a server (inspection result confirmation device) 52. The transport drive device 61, the carry-in device 81, the carry-out device 86, and the like are controlled by the central device 50. Each of the image processing apparatuses 12 to 42 can be realized by a single computer, or all these functions may be executed by a single computer. Further, the central device 50 and the image processing devices 12 to 42 may be realized by one computer, and the function of the server 52 may be included in this.

  The carry-in device 81 and the carry-out device 86 drive, for example, a suction disk (one or a plurality) including a plurality of vacuum (suction) cups, an arm (link) that supports the suction disk movably, and an arm. A drive unit. The carry-in device 81 sucks the slip sheet on the uppermost plate-shaped inspection object placed on the magazine 82 and places it in the slip-sheet storage box 84, and then sucks the uppermost plate-shaped inspection object. To the carry-in station on the transfer path 60, and the inspection object is transferred to the transfer device 69. The conveyance device 69 that has received the inspection object conveys the inspection object to the first stage and the second stage.

  At the first and second stages, the front and back surfaces of the inspection object are inspected. If it is determined that there is no defect, the object is transferred to the unloading station via the third and fourth stages. At the carry-out station, the non-defective inspection object is adsorbed by the carry-out device 86, carried to the OK magazine 87, and placed there. Then, a single slip sheet is taken out from the slip sheet storage box by the carry-out device 86 and placed on a non-defective product on the OK magazine 87. In the case of the first object placed on the OK magazine, a slip sheet is laid under it before placing the object.

  When a suspicious point (defect candidate) is found in the first or second stage, the inspection object is precisely inspected in the third or fourth stage, and then sent to the unloading station. The object determined to be defective (defective) is carried to the NG magazine 88 by the carry-out device 86 and placed there. A slip sheet is placed on the object if necessary. In the case of a non-defective product, the object is carried on an OK magazine 87. It goes without saying that various changes in arrangement are possible, such as making the first, second stage, and third and fourth stages different lines.

  2, 3 and 4 show an example of a plate-like (plate-like, film-like) inspection object.

  As shown in FIG. 2, the inspection object 90 has a thin and thin substrate 91, and several (four in FIG. 2) patterns 92 are formed on the surface of the substrate 91. ing. Each pattern 92 includes a large number of small pieces 93 regularly arranged vertically and horizontally.

  3 and 4, the piece 93 is square when viewed from the plane (surface, upper surface) (the pattern 92 which is a collection of these pieces 93 is also square). Each piece 93 includes a central square flat portion 95 and a reflector portion 94 surrounding the periphery of the piece 93 like a wall. The reflector portion 94 has an inclined surface (reflecting surface) 94a that descends inward. As an example, the substrate 91 is a thin copper plate (copper film), and a silver thin film (film) is formed on the flat portion 95 at the center of the upper surface of each piece 93 (for example, plating). A silver thin film (plating) 96 is also formed on the back surface of the substrate 91, and the end surface 97 is also covered with a silver thin film. The reflector portion 94 is made of a white synthetic resin. A portion of the synthetic resin may penetrate the substrate 91 in the thickness direction and be exposed on the back surface of the substrate 91 (the exposed surface is flush with the silver film 96).

  Examples of defects in such a plate-like inspection object include dirt and scratches, regardless of the material on the entire front and back surfaces. Further, regarding the silver plating 95, 96, peeling of plating, scratches, and the reflector portion 94 made of synthetic resin include the presence of bubbles, chipping, burrs, and cracks.

  In particular, since the synthetic resin has a different thermal contraction rate from that of the substrate (metal in this embodiment), it may shrink during the drying process after the resin layer is formed, and cracks may occur. This crack is extremely thin and is difficult to detect with normal image processing, especially at low resolution. Therefore, as will be described in detail later, in the first stage, the warp mechanism warps the plate-like object so that its surface (reflector 94 side) is convex, and the crack (groove) is widened and detected. Make it easier. In the inspection object 90 shown in FIGS. 2 to 4, the entire surface is not covered with the reflector portion 94 made of synthetic resin, but the resin portion (reflector portion 94) is only partially present. , Including this, a single resin layer (resin portion) formed on the substrate. Even when the resin portion of the reflector portion 94 is exposed on the back surface of the substrate 91, this exposed portion is referred to as a resin layer. In summary, thin cracks are detected in layers exposed on one side of a laminate of two or more layers with different thermal shrinkage rates (including those that are only partially covered without covering the entire surface) (especially synthetic resin layers) Therefore, a warping mechanism described later is effective.

  5, 6, and 7 show an example of the transfer device 69 that configures the transfer path 60.

  The transfer device 69 includes two guides 68 arranged along the transfer path 60 from the carry-in station to the carry-out station in parallel with a gap slightly wider than the width of the plate-like inspection object 90. These guides 68 are horizontally fixed at an appropriate height position by a support device (not shown). A movable body 63 is held on the inner portion of the guide 68 so as to be movable along its longitudinal direction and not to rotate. In this embodiment, three movable bodies 63 are provided on the left and right sides, and are arranged at intervals that can hold both sides of the elongated plate-like object 90 at three locations. Each movable body 63 is provided with a clamp 64 facing inward. A ball screw 62 is rotatably provided along the inside of the guide 68. The ball screw 62 passes through a screw hole formed in the movable body 63, and the ball screw 62 and the screw hole are engaged with each other through the ball. . The ball screw 62 is rotationally driven by the driving device 61. As the ball screw 62 rotates, the movable body 63 moves along the guide 68 in the front-rear direction (from the loading station to the unloading station or vice versa).

  Furthermore, two rails 66 are arranged in parallel with each other and movable up and down in a position corresponding to the inside of the guide 68 and slightly inward of the tip of the clamp 64 from the loading station to the unloading station. . The upper surface of the rail 66 is horizontal. The rail 66 moves up and down by the drive of the drive device 61.

  The case where the inspection object 90 is carried in at the carry-in station will be described. As shown in FIG. 6, the two rails 66 are lifted so that the upper surfaces thereof are higher than the position of the lower clamp member of the clamp 64. The clamp 64 has an upper clamp member open. The plate-like object 90 adsorbed by the carry-in device 81 (with the surface having the pattern 92 facing the upper surface) is carried right above the carry-in station and gently lowered onto the rail 66. Thereafter, as shown in FIG. 7, when the rail 66 is lowered and the upper surface thereof reaches the height position of the lower clamp member of the clamp 64, the upper clamp member is closed and the inspection object 90 is located at three positions on both sides. It is clamped by the clamp 64 at a time. At this time, the rail 66 is further lowered and separated from the inspection object 90.

  Since the ball screw 62 is rotationally driven, the inspection object 90 is transported toward the first stage of the inspection station with its both sides clamped and held by the clamps 64. Further, in this state, the sheet is transported from the first stage to the second stage, through the third and fourth stages to the unloading station.

  When the inspection object 90 reaches the carry-out station, the rail 66 is raised to receive the inspection object 90 and the clamp 64 is released. The inspection object 90 held on the pair of rails 66 is adsorbed by the carry-out device 86 and carried to the magazine 87 or 88. Thereafter, the ball screw 62 is rotated in the reverse direction, and the clamp 64 is returned to the carry-in station.

  Although a state in which one inspection object 90 is conveyed from the carry-in station to the carry-out station is described, a plurality of clamps may be provided to convey a plurality of inspection objects at a required interval. Needless to say, a conveying device having a configuration other than the above, such as a roller conveyor, can be applied.

  8 and 9 show an example of the configuration of the warping mechanism 70. FIG. The warpage mechanism 70 is disposed on the first stage of the inspection station (see FIG. 5). 8 and 9 show the state in which the inspection object 90 has reached the first stage. The warping mechanism 70 is composed of three rubber rollers 71, 72, 73 arranged along the conveyance path 60. The diameter of these rubber rollers is much larger than the thickness of the inspection object 90, so that the inspection object 90 is represented by a bold solid line. FIG. 9 is further enlarged to show the warped state, and the warped state of the inspection object 90 is greatly exaggerated (also exaggerated in FIGS. 8 and 10).

  Of the three rubber rollers 71, 72, 73, the two rollers 71 and 73 in the front-rear direction are arranged at the same height in parallel with each other at an appropriate interval in the transport direction, and the other roller 72 is The rollers 71 and 73 are arranged in the middle of the rollers 71 and 73 in parallel with the rollers 71 and 73. The rubber rollers 71 and 73 are rotatably supported above the position through which the inspection object 90 passes (support members are not shown). The rubber roller 72 is rotatably supported below a position where the inspection object 90 passes (a support member is not shown). The lengths of these rollers 71 to 73 are slightly shorter than the distance between the two rails 66, and are about the entire width of the pattern 92 on the inspection object 90 or slightly shorter than that.

  The height positions at which the upper rubber rollers 71 and 73 are in contact with the upper surface of the inspection object 90 are slightly lower than the height positions at which the lower rubber roller 72 and the lower surface of the inspection object 90 are in contact. The height positions of the rubber rollers 71 to 73 are determined. The height positions of the rollers 71 to 73 are determined so that the inspection object 90 conveyed with the both sides clamped by the clamps 64 can pass between the upper rollers 71 and 73 and the lower rollers 72. It has been.

  Therefore, when the inspection object 90 conveyed with the both sides clamped by the clamps 64 passes between these rollers 71 to 73, the inspection object 90 is lightly moved downward by the upper rollers 71 and 73. Since it is pressed and lightly pressed upward by the lower roller 72, the inspection object 90 warps so as to protrude upward at the position of the roller 72. As will be described later, the upper surface of the inspection object 90 is imaged by the image sensor 21 in the first stage.

  As shown in FIG. 15, when the pattern 92 or the piece 93 of the inspection object 90 has a particularly thin crack 99 in the reflector portion 94 made of resin, the inspection object 90 is moved upward by the warpage mechanism 70. Since it is warped to be convex, the crack opens slightly as shown by reference numeral 99A in FIG. 16, and appears as a thick line. In this way, the thin cracks existing on the surface of the inspection object 90 are forcibly expanded by the warp mechanism 70 and appear clearly on the image by the image sensor 11. Since it is sufficient that the cracks are slightly opened, the degree of warping may be small.

  10 and 11 show a configuration example of the illumination photographing apparatus in the first stage of the inspection station. This illumination photographing apparatus is fixed above the first stage. In the first stage, the inspection object 90 is photographed from the upper surface and inspected. The illuminating device is composed of a coaxial epi-illuminating device 13 disposed immediately above the photographing position by the image sensor 11 and two bar illuminating devices 14 disposed at positions before and after the conveying direction and extending in the width direction of the conveying path. The surface of the inspection object 90 including the reflector portion 94 having the inclined surface is uniformly illuminated without shadow. The image sensor 11 is a line sensor, and a portion of the inspection object 90 disposed just above the lower roller 72 described above is line-shaped over the entire width in the width direction as indicated by reference numeral 11A in FIG. Scan to capture the image. Since imaging by the image sensor 11 is repeatedly performed while conveying the inspection object 90, the set of output image signals of the image sensor 11 represents a two-dimensional image of the upper surface (surface) of the inspection object 90. Needless to say, the image sensor 11 includes an optical system (including enlargement and reduction) for forming an object image.

  FIG. 12 shows a configuration example of the illumination photographing apparatus in the second stage of the inspection station. This illumination photographing apparatus is fixed below the second stage. In the second stage, the inspection object 90 is imaged and inspected from the lower surface. Like the first stage, the illuminating device is arranged at a position before and after the coaxial epi-illumination device 23 arranged immediately above the photographing position by the image sensor 21 and in the conveying direction, and extends in the width direction of the conveying path. It comprises two bar lighting devices 24. The image sensor 21 is a line sensor, and scans the inspection object 90 in the width direction in the width direction in the process of transporting the inspection object 90 to capture an image.

  FIG. 13 shows an illumination photographing apparatus arranged on the third stage. The illumination photographing apparatus is held above the third stage so as to be movable (movable at least in the horizontal direction) and can be moved by a driving device (not shown). As described above, the third stage observes the area including the defect candidate on the inspection object 90 found by the inspection in the first stage with high accuracy. A ring illumination device 33 is used as the illumination device, and the area of the defect candidate portion is illuminated uniformly. The image sensor 31 is a two-dimensional image sensor and includes an enlargement / reduction optical system. In response to a command from the central device 50, the conveyance of the inspection object 90 is stopped, and the illumination device 33 and the image sensor 31 move to a position immediately above the area including the defect candidate portion, and an image of the area is necessary. Magnify according to the and shoot with high resolution.

  FIG. 14 shows an illumination photographing apparatus arranged on the fourth stage. The illumination photographing apparatus is held below the fourth stage so as to be movable (movable at least in the horizontal direction) and can be moved by a driving device (not shown). In the fourth stage, as described above, an area including defect candidates on the inspection object 90 discovered by the inspection in the second stage is observed with high accuracy. As the illuminating device 43, a ring illuminating device 43 is used to uniformly illuminate the area of the defect candidate portion. The image sensor 41 is a two-dimensional image sensor and includes an enlargement / reduction optical system. In response to a command from the central device 50, the conveyance of the inspection object 90 is stopped, and the illumination device 43 and the image sensor 41 are moved to a position immediately below the area including the defect candidate portion, and an image of the area is required. Magnify accordingly and shoot with high resolution.

  FIG. 17 shows the overall operation of the above-described visual inspection system, particularly shown in FIG.

  Under the control of the central device 50 (or the server 52), the inspection object (product) is picked up from the magazine 82 by the carry-in device 81 and passed to the transfer device 69 at the carry-in station (S11). Is taken out and moved to the slip box 84 (S12). Since the central apparatus 50 (or server 52) provides a conveyance command to the conveyance apparatus 69, the conveyance apparatus 69 starts the conveyance operation, and the inspection object 90 at the loading station is inspected with both sides thereof clamped by the clamps 64. It is conveyed to the first stage of the station (S13).

  In the first stage, the surface (upper surface) of the inspection object 90 is imaged by the image sensor 11 while being conveyed by the conveying device 69. The image signal output from the image sensor 11 is given to the image processing device 12, and image processing described later is performed (S14). The inspection object 90 is subsequently sent to the second stage, and similarly, the back surface (lower surface) of the inspection object 90 is imaged by the image sensor 21, and image processing is performed based on the image signal output from the image sensor 21. Predetermined image processing is executed in the device 22 (S15). The image processing results in the image processing devices 12 and 22 are sent to the central device 50 (S16), and the central device 50 determines the quality of the inspection object 90 (S17).

  The inspection object 90 in which defect candidates are partially found in the inspection in the first stage is sent to the third stage. In the third stage, a high resolution image of the area including the position of the defect candidate is obtained by the image sensor 31. Based on the acquired image data, the image processing device 32 performs image processing to be described later (S18).

  Similarly, the inspection object 90 in which defect candidates are partially found in the processing in the second stage is imaged in the fourth stage by the image sensor 41 in the vicinity area including the defect candidates, and the image data Are processed by the image processing device 42 (S19).

  The image processing results of the image processing devices 32 and 42 are given to the central device 50, and strict quality determination is performed based on the image processing results (S21).

  The inspection object 90 determined to be a non-defective product by the central device 50 in S17 or S21 is transported to the unloading station, and then transferred to the OK magazine 87 by the unloading device 86, where the slip sheet is placed on the slip sheet box 89. (S22, S23). The inspection object 90 determined to be defective is transported to the carry-out station, then moved to the NG magazine 88 by the carry-out device 86, and a slip sheet is placed thereon (S24, S25).

  The central device 50 outputs the inspection result to the server 52 (S26). The user can confirm the inspection result of the object inspected in the server 52.

  The above inspection may be performed while sequentially conveying a plurality of inspection objects, or the above inspection may be performed one by one.

  FIG. 18 shows the inspection in the first stage or the second stage, particularly the image processing in the image processing apparatus 12 or 22.

  The image signal (image data) acquired by the image sensor 11 or 21 is given to the image processing device 12 or 22. There are two types of image processing in the image processing apparatus 12 or 22. The first image processing mainly detects fine defects (including scratches, chips, burrs, and cracks) in the reflector portion 94 made of synthetic resin (S32 to S37). The second image processing detects relatively large defects such as dirt on the surface of the substrate 91 (silver plating layers 95, 96, etc.), peeling of plating, scratches, absence of the reflector portion 94, etc. (S38). ~ S40).

  In the first image processing, first, the acquired image data is binarized to extract the resin reflector 94 (S32). The resin is white in this embodiment, and can be distinguished from other parts by binarization and extracted. A binary image is a black and white image. The binary image is subjected to white expansion processing (or black contraction processing) (S33). As a result, an image is generated from which the stain and chipping (defect candidates) of the resin portion appearing black are removed. The size of defects that can be removed depends on the size of the expansion (or contraction) filter and the number of treatments. The image data subjected to the above white expansion (black contraction) processing is then subjected to white contraction (black expansion) processing the same number of times using a filter of the same size as in S33 (S34).

  Difference processing between the image subjected to the white expansion / contraction (black contraction / expansion) processing (S33, S34) and the binary image obtained in S32 is performed (S35). As a result, defect candidates removed by the expansion and contraction processing described above appear in the difference image obtained. The defect candidates appearing on the difference image data are labeled, and the area (number of pixels) is counted for each defect candidate (S36). Then, for each defect candidate, the area (number of pixels) is compared with a given threshold value (th1) (S37). A defect candidate having an area (the number of pixels) larger than the threshold th1 is a place to be inspected in detail at stage 3 or 4.

  As described above, since the width of the micro crack having a very narrow width is enlarged by the warp mechanism 70 in the first stage, the defect candidate to be inspected in the third stage in the first image processing described above. Determined.

  In the second image processing, an image of an inspection object having no defect (this is referred to as a reference image) is prepared in advance. Difference processing is performed between the image data of the inspection object obtained by photographing and the image data of the reference image (S38). The defect candidate appearing in the difference image is labeled to obtain the area (number of pixels) of the defect candidate (S39). Then, each defect candidate is compared with a predetermined threshold value (th2) (this threshold value th2 is larger than the previous threshold value th1) (S40), and an area (number of pixels) larger than the threshold value th2. These defect candidates are determined as defect candidates to be inspected precisely in the third or fourth stage.

  The results of these first and second image processing (the presence or absence of defect candidates and their positions (coordinates on the inspection object)) are given to the central device 50.

  FIG. 19 shows image processing in the inspection performed in the third or fourth stage. In the third or fourth stage, the image sensor 31 or 41 is positioned at a position where a high-resolution enlarged image of the area including the defect candidate is taken based on the inspection result of the first or second stage given from the central device 50. Is done. The transfer device 69 stops the transfer operation, and the inspection object is stationary. The size of the area including the defect candidate is, for example, the size of the piece 93. A reference image of the piece 93 having no defect is prepared in advance.

  An image of the piece 93 including defect candidates is acquired by the image sensor 31 or 41 by photographing with the image sensor 31 or 41 (S51). Difference processing is performed between the image data of the piece of the inspection object obtained by imaging and the image data of the reference image of the piece (S52). The defective portion appearing in the difference image is labeled to determine the area (number of pixels) of the defective portion (S53). Then, each defective portion is compared with a predetermined threshold value (th3) (S54), and an inspection object having a defective portion having an area (number of pixels) larger than the threshold value th3 is determined to be a defective product, and the threshold is set. If it is smaller than the value th3, it is not finally judged as a defect. These processes are performed for all defect candidates.

  An inspection object having at least one portion determined to be defective is determined as a defective product. The processing result of the third or third stage is given to the central device 50.

11, 21, 31, 41 Image sensor
12, 22, 32, 42 Image processing device
50 Central unit
52 servers
60 Transport path
61 Transport drive
62 Ball screw
63 Movable body
64 clamps
66 rails
68 Guide
70 Warpage mechanism
71, 72, 73 Rubber roller
90 Inspection object
91 Board
92 patterns
93 pieces
94 Resin reflector
99 crack
99A Crack expanded by warping

Claims (9)

A warping mechanism that warps a plate-like inspection object so that at least one surface to be inspected for cracks is convex;
An image sensor that acquires an image signal representing an image of the surface of the plate-like object in a warped state, and image processing that determines at least the presence or absence of a crack based on the image signal acquired by the image sensor means,
An appearance inspection apparatus comprising: A warping mechanism for warping a plate-like object having at least one resin layer formed on at least one surface of the substrate so that the surface on which the resin layer is formed is convex;
A first image sensor that acquires a first image signal representing an image of at least the surface of the resin layer of the plate-like object in a warped state, and the first image sensor acquired by the first image sensor First image processing means for determining at least the presence or absence of cracks based on an image signal;
An appearance inspection apparatus comprising: A transport device for transporting the plate-like object;
The warpage mechanism includes at least three rollers disposed along the plate-like object conveyance path by the conveyance device, and two of these rollers are spaced apart from each other and the plate in the middle of conveyance. It is arranged so as to contact and press the one surface on which the resin layer of the object is formed, and the other roller is between the two rollers and the plate-like object being transported Arranged to contact and press against other surfaces,
The first image sensor acquires an image of the plate-like object being transported by the transport device;
The appearance inspection apparatus according to claim 2.   The appearance inspection apparatus according to claim 3, wherein the first image sensor is a line sensor that acquires an image on a line in a direction orthogonal to a conveyance direction of the plate-like object by the conveyance apparatus.   The said 1st image processing means determines the presence or absence of the defect of the surface of the said one surface in which the said resin layer of the said plate-shaped target object is formed, The statement of any one of Claim 2 to 4 Appearance inspection device. A second image sensor for acquiring a second image signal representing an image of the surface of the other surface of the plate-like object having the resin layer formed on at least one surface; and the second image sensor, Second image processing means for determining the presence or absence of a defect based on the acquired second image signal;
The visual inspection apparatus according to claim 2, further comprising: A transport device for transporting the plate-like object;
The first image sensor and the second image sensor are sequentially arranged along a conveyance path of the plate-like object by the conveyance device.
The appearance inspection apparatus according to claim 6. The plate inspection object is warped so that at least one surface to be inspected for cracks is convex.
A first image signal representing the image obtained by imaging the surface of the one surface of the warped plate-like object by an image sensor;
Determining at least the presence or absence of cracks based on the acquired first image signal;
Appearance inspection method. A plate-like object having at least one resin layer formed on at least one surface of the substrate is warped so that the surface on which the resin layer is formed is convex;
An image signal representing the image is obtained by imaging at least the surface of the resin layer of the warped plate-like object with an image sensor;
Determining at least the presence or absence of cracks based on the acquired image signal;
Appearance inspection method.

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