JP2008267904A - Visual inspecting apparatus and method for inspecting surface state - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily cope with change of tested objects and to increase the efficiency of inspection. <P>SOLUTION: Work loading, pre-treating, inspecting, and unloading processes are implemented in parallel by rotating an index table 1 on which work stages 2 are rotatably provided at intervals of 90 degrees. Each stage 2 is locked before it reaches the test position C. When the stage 2 stops at the test position C, the stage 2 is engaged with a stage rotating mechanism 30 and can rotate. In the inspection process, the image pick-up operation is implemented by applying the light axis of the inspection image-pickup section 5 to a plurality of image pickup points while combining the rotation of the stage 2 and control to change the position and attitude of the inspection image-pickup section 5. The data required for this controlling is corrected according to the quantity of deviation of the work detected at the pre-treating position B when the table 1 stops at the preceding process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for inspecting whether or not a surface of an inspection object (hereinafter referred to as “workpiece”) has a defect by an image processing technique using an object having a predetermined three-dimensional shape as an inspection object.

  In order to detect defects on the surface of the workpiece with high accuracy, it is necessary to adjust so that the optical axes of the camera and the illumination unit are aligned in a certain direction with respect to the surface to be inspected. In particular, when the surface to be inspected is a curved surface or when a plurality of surfaces are inspected, it is necessary to perform imaging a plurality of times while changing the position and orientation of the camera and the illumination unit with respect to the workpiece.

  For example, the following Patent Document 1 describes that an articulated robot supports a work or an optical system, and controls the operation of the robot to sequentially move the inspected position to the focal position of the camera and perform imaging. ing.

JP-A-6-160066

  When inspecting while changing the position and orientation of a workpiece using a robot, if the shape or size of the workpiece to be inspected changes, the robot side mechanism may need to be changed accordingly. is there. Therefore, it is difficult to deal with various workpieces.

  On the other hand, when the camera or the illumination unit is moved by the robot, it is not necessary to change the mechanism on the robot side. However, in order to reliably image a predetermined inspection area, it is necessary to position the workpiece or detect the deviation amount of the workpiece and correct the robot control data by the deviation amount.

  In order to employ the method of positioning the workpiece, a means for fixing and supporting the workpiece is required. Therefore, as in the case where the workpiece is supported by the robot, it becomes impossible to cope with changes in the shape and size of the workpiece. Such a problem does not occur when taking the method of correcting the control data of the robot by detecting the amount of deviation, but pre-processing such as imaging and calculation for detecting the position deviation is necessary. Efficiency is reduced.

  Further, when the amount of movement of each arm of the articulated robot becomes large or the control becomes complicated, the time required for aligning the camera becomes long. In particular, when imaging is repeated a plurality of times while changing the positional relationship between the workpiece and the camera as in the inspection of a polyhedral workpiece, the efficiency of the inspection may be significantly reduced depending on the time required for camera alignment every hour. .

  In consideration of the above-mentioned various problems, the present invention can easily cope with the change of the workpiece to be inspected, and the efficiency of the inspection when performing the imaging a plurality of times while changing the imaging target position for each workpiece. The purpose is to increase

  In the appearance inspection apparatus according to the present invention, a plurality of stages each having a workpiece mounting surface having a predetermined width and not provided with means for fixing a workpiece are attached via a rotating shaft at regular intervals. A stage support table configured so as to be movable integrally and having a predetermined position within the movement range set as an inspection position; detachably mounted on the rotary shafts of the respective stages, and the mounted rotary shafts corresponding thereto A plurality of stage fixing mechanisms that prevent rotation of the stage; a stage fixing mechanism is attached to each stage's rotation axis, and the stage support table is moved so that each stage is sequentially sent toward the inspection position, and the inspection position A movement control means for temporarily stopping the stage support table every time the stage arrives at the stage; A stage rotating mechanism that is detachably mounted on the rotating shaft of the machine and rotates the mounted rotating shaft and the stage corresponding thereto; an imaging unit for inspection for generating an image for inspection of the workpiece; in the vicinity of the inspection position An imaging unit support mechanism that supports the imaging unit for inspection in such a manner that the position and orientation of the imaging unit can be changed; when the stage stops at the inspection position, at the current stop position of the stage that stops at the inspection position next to the stage Pre-processing imaging unit arranged to be capable of imaging the workpiece mounting surface; reference image registration means for registering a reference image of the workpiece mounting surface generated by the pre-processing imaging unit for the stage on which the workpiece is mounted; reference image To align the optical axis of the imaging unit for inspection with the workpiece when the stage on which the workpiece is mounted has the same position and orientation as shown in Control data registration means for registering a plurality of data relating to the operation control of the stage rotation mechanism and the imaging unit support mechanism as control data; generated by causing the preprocessing imaging unit to perform imaging whenever the stage support table stops A deviation amount calculating means for obtaining a deviation amount of a work in the image by comparing the image thus obtained with a reference image; a control data correcting means for correcting each control data registered in the control data registration means based on the deviation amount; Each time the support table stops, the stage rotation mechanism is mounted on the rotation axis of the stage that is stopped at the inspection position at that time, and the stage fixing mechanism is released from the rotation axis, and the stage support table in the previous stage is released. Stage rotation mechanism and imaging unit support using control data corrected based on the amount of deviation calculated when stopping Each configuration includes: an inspection execution unit that causes the inspection imaging unit to perform imaging a plurality of times while controlling the mechanism, and executes image processing for inspection using an image generated by the hourly imaging.

  According to said structure, the workpiece | work to be examined is mounted in the state which is not fixed to a stage, respectively. The rotation axis of each stage is fixed so as not to rotate until it reaches the inspection position. However, when the inspection axis reaches the inspection position, the fixing is released and the stage rotation mechanism is mounted and becomes rotatable.

  At the time of inspection, by controlling the operations of both the stage rotation mechanism and the imaging unit support mechanism, the position and angle of the imaging unit can be adjusted while rotating the stage. Therefore, it is possible to shorten the time required for aligning the imaging unit for inspection, and it is possible to efficiently perform imaging.

Further, when the workpiece is not fixed, it is necessary to correct the control data for the above control. However, the amount of deviation of the workpiece necessary for this correction is calculated before the workpiece reaches the inspection position. Therefore, it is possible to prevent the start of the inspection from being delayed due to the preprocessing. In addition, the workpiece moves to the inspection position together with the stage after calculating the positional deviation amount. However, since the stage is fixed until the inspection position is reached, the calculated positional deviation amount can be prevented from fluctuating. Therefore, it is possible to image the predetermined imaging target position of the workpiece from the predetermined direction using the control data appropriately corrected based on the deviation amount calculated before the inspection, and improve the accuracy of the inspection. Can be secured.
Furthermore, if the preprocessing includes the process of correcting the control data, the inspection can be performed more efficiently.

  In addition, in Patent Document 2 below, as a circuit pattern inspection apparatus for a substrate, a work support holder is provided with a rotary table provided at 90 ° intervals, and while rotating the rotary table in 90 ° steps, An apparatus having a configuration in which workpiece loading, misregistration detection, inspection, and unloading are performed in parallel is described. Also, the amount of deviation of the substrate to be inspected is detected at a position before the inspection position, and using this amount of deviation, the relative position between the substrate and the inspection jig (a circuit pattern is read using a large number of contacts) is determined. The correction is also described.

JP 2002-277502 A

  However, the invention described in this document is intended to inspect a circuit pattern on a plane, and the installation position of an inspection jig of a type that covers the substrate and detects the contact state with the circuit pattern is the position of the substrate. It is only adjusted according to the amount of deviation. By taking a workpiece having a three-dimensional shape as an inspection target and performing imaging multiple times while simultaneously rotating the workpiece and adjusting the position and orientation of the imaging unit, or by fixing the stage on which the workpiece is mounted to the inspection position Ensuring the accuracy of the amount of displacement detected before inspection is not described in this document at all.

  Further, in this Patent Document 2, there is disclosed a technical idea that the substrate to be inspected is fixedly supported in a holder corresponding to its shape so that various workpieces having different shapes and sizes can be inspected. Not.

  In a preferred aspect of the appearance inspection apparatus, at least three stages are arranged on the stage support table, and a predetermined stage stop position excluding the inspection position and a position where imaging by the preprocessing imaging unit is performed is performed. Set to the workpiece loading position. As a result, it is possible to carry out the workpiece unloading, misalignment detection, and inspection processes in parallel, and the inspection efficiency can be further increased.

  In a more preferred aspect, the stage support table is configured as an index table that rotates by an angle corresponding to the interval between the stages. As a result, it is possible to perform inspection by sequentially receiving a plurality of workpieces while repeating the rotation of the stage support table, and the efficiency of the inspection can be further enhanced.

  In the surface condition inspection method according to the present invention, a plurality of stages each having a workpiece mounting surface having a predetermined width, which are not provided with means for fixing the workpiece, are attached via a rotating shaft at regular intervals. A stage support table configured to be movable integrally with the stage is prepared, and a predetermined position in the moving range of the table is set as an inspection position. In addition, the inspection imaging unit is supported in the vicinity of the inspection position so that the position and posture thereof can be changed, and when the stage reaches the inspection position, the current stage of the stage that stops at the inspection position next to this stage The preprocessing imaging unit is arranged in a state where the workpiece mounting surface at the stop position can be imaged. In addition, for the stage on which the workpiece is mounted, a reference image of the workpiece mounting surface generated by the preprocessing imaging unit is registered, and the stage on which the workpiece is mounted at the same position and orientation as shown in the reference image As the control data for aligning the optical axis of the inspection imaging unit with the workpiece when stopped at the inspection position, a plurality of data relating to the rotation operation of the rotation axis and the position and orientation control of the inspection imaging unit are registered in advance.

  During inspection, the stage rotation axis is fixed, the stage support table is moved so that each stage is sent in turn toward the inspection position, and the stage is supported each time the stage reaches the inspection position. Pause the table.

  Further, each time the stage support table stops, the preprocessing imaging unit performs imaging, and the generated image is collated with the reference image to calculate the shift amount of the workpiece in the image. Also, every time the stage support table stops, it is calculated when the stage support table is stopped one stage after releasing the fixed rotation axis of the stage that is stopped at the inspection position and making the stage rotatable. The control data corrected based on the amount of misalignment is used to control the rotation operation of the rotating shaft and the position and orientation of the imaging unit for inspection. The image processing for inspection is executed using the obtained image.

According to the appearance inspection apparatus and the surface condition inspection method described above, it is not necessary to fix the workpiece to be inspected, and it is only necessary to install the workpiece on the stage with an arbitrary position and orientation. it can.
Furthermore, the rotation of the stage and the control of the position and orientation of the inspection imaging unit can efficiently align the inspection imaging unit with respect to the workpiece, and the stage is fixed until the inspection starts. Even if the amount of deviation of the workpiece is obtained in advance, the accuracy can be ensured, so that an efficient and highly accurate inspection can be performed.

FIG. 1 shows a partial configuration of an appearance inspection apparatus to which the present invention is applied.
This appearance inspection apparatus is for discriminating whether there is a defect such as unevenness or color abnormality on the surface of a workpiece W having high specular reflectivity such as a resin molded product, and uses a disk-shaped index table 1. Thus, the inspection of a large number of workpieces W can be efficiently advanced by performing the processing of loading, pre-processing, inspection, and unloading of the workpieces W in parallel.

  In addition to the table body, the index table 1 includes a drive mechanism including a motor, an encoder, and the like (none of which are shown). Further, on the upper surface of the index table 1, four work mounting stages 2 are arranged at equal angular intervals (that is, every 90 °).

  Each stage 2 includes a flat and rectangular work mounting surface 20, and is attached to the index table 1 via a rotation shaft 21 in a state where the work mounting surface 20 is horizontal.

In this embodiment, the index table 1 is repeatedly rotated while being paused every 90 ° rotation, and the work W is loaded, preprocessed, and inspected at the positions A, B, C, and D where the respective stages 2 are stopped. Each process of carrying out the workpiece W is executed. Hereinafter, the positions A, B, C, and D are referred to as “work carry-in position A”, “pre-processing position B”, “inspection position C”, and “work carry-out position D”, respectively.
Note that the preprocessing position B and the inspection position C do not mean that processing is performed at these positions, but preprocessing or inspection is performed on the workpiece W stopped at these positions. Means.

In this appearance inspection apparatus, it is possible to inspect the workpiece W mounted on the stage 2 by imaging each surface except the surface in contact with the workpiece mounting surface 20. Further, if each workpiece W is carried in twice and the vertical direction is reversed between the first loading time and the second loading time, it is possible to cope with an application for inspecting the entire surface of the workpiece W.
In the example of FIG. 1, for convenience of illustration, the workpiece W is shown as a rectangular parallelepiped object. However, in practice, various solid shapes can be used as long as they can be placed on the stage 2 in a stationary state. Can be processed.

  Above the preprocessing position B, a camera 4 and a lighting device (not shown) (may be integrated with the camera 4) are provided. The camera 4 is fixedly supported by a support member (not shown) so that the imaging surface is directly below, and the height and magnification thereof are adjusted so that the entire surface of the work mounting surface 20 of the stage 2 is included in the field of view. Hereinafter, the camera 4 is referred to as a “preprocessing camera 4”.

The preprocessing camera 4 performs imaging whenever the stage 2 stops at the preprocessing position B. The image generated by this imaging is collated with a reference image registered in advance, and the deviation amount (position deviation amount and rotation deviation amount) of the actual workpiece W with respect to the reference position and reference direction of the workpiece W indicated by the reference image. ) Is calculated. Further, processing for correcting control data used in the inspection is performed using the calculated deviation amount.
In this specification, a series of processing for the image generated by the preprocessing camera 4 is regarded as position / posture recognition processing for the workpiece W, and is expressed as follows. This position / posture recognition processing is completed before the workpiece W imaged by the preprocessing camera 4 moves to the next inspection position C.

  At the inspection position C, an inspection imaging unit 5 is provided. The inspection imaging unit 5 includes a camera 6 and an illumination device 7 and is supported by a scalar robot 9 to be described later so that the position and orientation can be changed. In the following, in order to avoid confusion with the above-described preprocessing camera 4, the camera 6 may be referred to as “inspection camera 6” or simply “camera 6”.

  A stage rotating mechanism 3 including a motor 30 is provided at a location corresponding to the inspection position C below the index table 1. This stage rotation mechanism 3 is supported by a vertical movement mechanism (not shown) so as to be movable up and down, and is connected to the rotary shaft 21 on the stage 2 side at the top dead center. This makes it possible to control the rotation direction and rotation angle of the stage 2 that has reached the inspection position C.

  In this embodiment, the workpiece W is mounted on the stage 2 so that a specific surface of the workpiece W is in contact with the workpiece mounting surface 20, and sequentially fed toward the inspection position C. At the inspection position C, the inspection imaging unit 5 is sequentially aligned with a plurality of imaging points set on the workpiece W by rotation control of the stage 2 and adjustment of the position and orientation of the inspection imaging unit 5 to execute imaging. . Control data used for this control is registered in advance by a teaching process described later, and is corrected for each workpiece W by a position / posture recognition process.

  Each stage 2 is set in a state in which rotation is prevented by a stage fixing mechanism 8 described later until the inspection position C is reached. Therefore, it is possible to prevent the shift amount of the workpiece W obtained by using the image generated by the preprocessing camera 4 from fluctuating, and at the inspection position C, the inspection imaging unit 5 and the workpiece are corrected using the corrected control data. Position alignment with W can be performed with high accuracy.

FIG. 2 individually shows the processing performed for each stage 2 while the index table 1 is rotated. Only in this figure, each stage 2 is shown as “stages a, b, c, d”.
Further, in this figure, the processing corresponding to one workpiece W is surrounded by a dotted frame, and the order of loading the workpieces W to be processed in the vicinity of these frames is <1><2><3>. Shown in In any stage 2, a new workpiece W is loaded when it stops at the loading position A, and the position / posture recognition processing, inspection, and unloading processing are performed while sequentially moving to the B, C, and D positions. Is executed.

  As shown in FIG. 2, in this embodiment, by rotating the index table 1, four workpieces W can be performed in parallel while delaying processing by one step. In addition, since the correction of the control data is completed for any workpiece W when it stops at the inspection position C, the inspection can be immediately performed using the corrected control data. Therefore, even when a large number of workpieces W are inspected, the processing can be efficiently performed.

However, the position / posture recognition processing may be limited to the calculation of the amount of displacement of the workpiece W, and the inspection may be performed while correcting various control data.
Further, the number of stages 2 supported by the index table 1 is not limited to four. For example, as shown in FIG. 3, the stage 2 may be increased by one, and the position / posture recognition processing before the inspection may be divided into two positions B1 and B2. In this case, cameras 4a and 4b are provided at positions B1 and B2, respectively. In B1, a “rough search” for detecting the approximate position of the work W is obtained, and in B2, a detailed displacement amount of the work W is obtained. Each “detailed search” is performed.

In contrast to the above, the number of stages 2 may be three, and the work W may be carried in and out at the same position.
Further, the means for supporting the stage 2 so as to be movable is not limited to the index table 1, and for example, a table that moves along one axis is used, and along the moving direction of the table, the workpiece loading position A, the preprocessing position B, You may set each position of the inspection position C and the workpiece carry-out position D.

  FIG. 4 shows a detailed configuration of the inspection imaging unit 5. In this figure, for convenience of drawing, the size of the illumination device 7 is greatly exaggerated with respect to the camera 6 and the optical axis of the camera 6 is shown in the vertical direction of the drawing. Further, R in the figure is an area on the work W included in the visual field of the camera 6 (hereinafter referred to as “visual field corresponding area”), and P is an imaging point. This imaging point P is designated by the user as a target position for aligning the optical axes of the camera 6 and the illumination device 7 during teaching, and corresponds to the center point of the visual field corresponding region R.

  The illumination device 7 incorporates a half mirror 70 and two illumination units 71 and 72 (hereinafter referred to as “first illumination unit 71” and “second illumination unit 72”). The half mirror 70 is provided on the optical axis of the camera 6, the first illumination unit 71 is disposed on the side of the half mirror 70, and the second illumination unit 72 is disposed below the half mirror 70.

  The first illumination unit 71 is a planar light source in which a plurality of light sources 74 (specifically, LEDs) are accommodated, and a diffusion plate 75 is provided on the front surface. The second illumination unit 72 has a configuration in which a plurality of light sources 74 are arranged in an annular shape inside a dome-shaped housing 76 having a camera peep hole 78 formed on the upper surface. The optical axis of each light source 74 is set to be parallel to the optical axis of the camera 6, and a light diffusing member 77 having a truncated cone or truncated pyramid shaped inner surface is disposed at the lower part of the casing 76.

  Each of the illumination units 71 and 72 includes three types of light sources 74 that emit R, G, and B color lights so that the illumination color can be changed according to the color of the workpiece W. In FIG. 4, the difference between these emission colors is indicated by a pattern of halftone dots, diagonal lines, and the like.

  Light emitted from each light source 74 of the first illumination unit 71 is mixed by the front diffusion plate 75 and irradiated to the half mirror 70, and then travels along the optical axis of the camera 6. As a result, illumination with illumination light from the same direction as the camera 6 (hereinafter referred to as “coaxial epi-illumination”) is performed in the visual field corresponding region R.

Light emitted from each light source 74 of the second illumination unit 72 is emitted below the peephole 78 through the light diffusion plate 77. Therefore, when the illumination unit 72 is turned on, the visual field corresponding region R is illuminated with light incident from an oblique direction with respect to the optical axis of the camera 6 (hereinafter referred to as “oblique incident illumination”). .
In addition, the diameter of the emitted light is adjusted so that the illumination light from each light source 71 and 72 can illuminate the whole field-of-view corresponding | compatible area | region R, respectively.

  In this embodiment, when inspecting the presence or absence of irregularities on the surface of the workpiece W, coaxial epi-illumination by the first light source 71 is performed, and image processing focusing on the intensity of specularly reflected light incident on the camera 6 is performed. Execute. In addition, when detecting a color defect, oblique incident illumination by the second light source 72 is performed, and image processing focusing on the intensity of diffusely reflected light incident on the camera 6 is executed. Whichever illumination is performed, the intensity of the reflected light entering the camera differs depending on whether there is a defect or not.

  In the inspection of this embodiment, the above-mentioned reflection characteristics are used to detect a part having a brightness significantly different from that of the reference image as a defect. To ensure the accuracy of this type of inspection, the work W is inspected. It is necessary to accurately perform the process of aligning the optical axis of the image pickup unit 5. In particular, when detecting an uneven defect with an optical system configured as shown in FIG. 4, the optical axis of the camera 6 is used to make the optical axis of the camera 6 enter the camera 6 so that the specularly reflected light from the field-corresponding region R with respect to the coaxial incident illumination light enters the camera 6. It is desirable to be in a state matched to the normal direction of the corresponding region R. Also, when detecting a color defect, if the optical axis of the camera 6 is aligned with the normal direction of the visual field corresponding region R, diffuse reflected light from the visual field corresponding region R can be stably imaged. .

  In this embodiment, therefore, the control data relating to the rotation operation of the stage 2 and the operation of the scalar robot 9 is obtained under the condition that the optical axis of the inspection imaging unit 5 is aligned with the normal direction of the imaging point P. Set to satisfy.

FIG. 5 shows a configuration of the scalar robot 9 that supports the inspection imaging unit 5.
The scalar robot 9 has a structure in which four arm portions 92, 93, 94, and 95 are sequentially connected to a base portion 91 via drive shafts c1, c2, c3, and c4, respectively, and have a predetermined height. Hanging and fixed in position. A holder unit 96 that supports the camera 6 and the illumination device 7 of the imaging unit 5 for inspection is attached to the distal arm 95. The tip arm 95 is configured to be extendable and contractible.

  Furthermore, although not shown in this figure, the holder part 96 is attached to the front-end | tip arm 95 so that rotation is possible by the axis | shaft which rotates in the arrow direction of a figure. By rotating this axis, as shown in FIG. 6, the orientation of the camera 6 and the illumination device 7 (shown as the angle α formed by the optical axis with respect to the vertical direction in the figure) is in the range of 0 to 90 °. Can be rotated.

  According to the above configuration, by controlling the rotation of the axes c1 to c4 between the arm portions and adjusting the length of the tip arm 95, and controlling the rotation of the holder portion 96, the X axis (left and right direction in the figure), The inspection imaging unit 5 is directed to an arbitrary direction in an arbitrary position in a three-dimensional space represented by the respective axes of the Y axis (the direction orthogonal to the paper surface of the drawing) and the Z axis (the vertical direction of the drawing). Can be arranged.

FIG. 7 shows the structure of the mechanism related to the rotation and fixation of the stage 2.
The rotation shaft 21 of each stage 2 is inserted into a through hole (not shown) so as to protrude long on the lower side of the index table 1. Two small and large nuts 22 and 23 are attached to the protruding portion on the lower side. The larger nut 22 is disposed near the lower surface of the index table 1, and the smaller nut 23 is disposed at the lower end of the rotating shaft 21.

  Each stage is provided with a stage fixing mechanism 8 individually. The stage fixing mechanism 8 includes a support box 81 attached to the lower surface of the index table 1, an engaging member 82 for the nut 22, a solenoid 83 having an L-shaped rod 85, and the like.

The engaging member 82 includes a recessed groove portion 84 having a groove width corresponding to the thickness of the nut 22, with the recessed groove portion 84 opposed to the nut 22, and the inside of the support box 81 along the horizontal direction of the drawing. Supported to slide. Further, the rear surface of the concave groove portion 84 is connected to the front surface of the support box 81 via a tension spring 86 in order to cause the concave groove portion 84 to protrude from the support box 81.
The solenoid 83 is supported at a position below the support box 81 by a fixing member (not shown) such that the bent portion at the tip of the L-shaped rod 85 is in contact with the front surface of the engaging member 82. Further, the support position of the solenoid 83 is adjusted so that the tip of the rod 85 is positioned below the nut 22 when the rod 85 is fully extended.

  The stage rotation mechanism 3 has a configuration in which a coupling 32, a chuck mechanism 33, and the like are provided on the drive shaft 31 of the motor 30 described above, and is disposed at a position below the inspection position C so as to be vertically movable.

  FIG. 8 shows the flow of operations of the stage fixing mechanism 8 and the stage rotating mechanism 3 that are executed after the stage 2 reaches the inspection position C and before the movement to the workpiece carry-out position D is started. In FIG. 8, for the sake of space, reference numerals are omitted in a range that does not hinder the following description.

Until the stage 2 reaches the inspection position C, the solenoid 83 of the stage fixing mechanism 8 is set in a non-excited state in which the rod 85 protrudes, and the tip of the rod 85 is positioned below the nut 22. As a result, the engaging member 82 is pulled toward the nut 22, the concave groove 84 engages with the nut 22, and the rotating shaft 21 is fixed.
FIG. 8A shows a state immediately after the stage 2 stops at the inspection position C, and the rotating shaft 21 is fixed by the stage fixing mechanism 8 in the above-described state. The stage rotation mechanism 3 is positioned below the nut 23 at the lower end of the rotation shaft 21.

  Thereafter, as shown in FIGS. 8 (2) and (3), the stage rotating mechanism 3 is raised, and the nut 23 at the lower end of the rotating shaft 21 is sandwiched by the chuck mechanism 33. As a result, when the stage rotating mechanism 3 is mounted on the rotating shaft 21, the solenoid 83 is excited and the rod 85 is pulled into the support box 81 as shown in FIG. In accordance with this movement, the engagement of the engagement member 82 with respect to the nut 22 is also released, and the rotary shaft 21 and the stage 2 become rotatable. In this state, imaging for inspection is executed while controlling the operations of the motor 30 and the scalar robot 9.

  When the imaging is completed, the rod 85 protrudes from the solenoid 83 again as shown in FIG. Thereby, the pulled state of the engaging member 82 is also recovered, the recessed groove portion 84 is engaged with the nut 22, and the rotating shaft 21 is fixed again. Further, as shown in FIG. 8 (6), the holding of the nut 23 by the chuck mechanism 33 of the stage rotating mechanism 3 is released. Thereafter, when the stage rotating mechanism 3 is lowered, the stage 2 is moved to the workpiece loading position D.

FIG. 9 is a block diagram showing the overall configuration of the appearance inspection apparatus.
This visual inspection apparatus controls the operation of various mechanisms by a programmable logic controller (PLC) 10 under the control of the control processing apparatus 11. A robot controller 12 and a motor driver 13 are used as a lower control system of the PLC 10. Is provided.

  The robot controller 12 controls the operation of the scalar robot 9, and the motor driver 13 controls the operation of each motor of the index table 1 and the stage rotation mechanism 3.

Further, the inspection camera 6, the illumination device 7, the preprocessing camera 4, the stage fixing mechanism 8, and the like are connected to the PLC 10.
The control processing device 11 is a personal computer, and is connected to an operation unit 14 such as a mouse and a keyboard and a monitor 15 for teaching and checking work at the time of inspection.

Programs and control data necessary for operation control of the index table 1, the stage rotation mechanism 3, the scalar robot 9, and the like are created by the control processing device 11 and supplied to the PLC 10. The PLC 10 controls various mechanisms using the supplied program and control data.
Further, the image signal from the preprocessing camera 4 is input to the PLC 10 for the position / posture recognition processing, but the image signal from the inspection camera 6 is input to the control processing device 11. Most of image processing and determination processing for inspection are executed by the control processing device 11.

  FIG. 10 shows the flow of processing executed during teaching before inspection. This process is performed mainly by the control processing device 11 while accepting a setting operation by the user while controlling the operation of each unit via the PLC 10.

In the teaching of this embodiment, a non-defective non-defective workpiece W is placed on one of the stages 2 and the index table 1 is rotated in the same order as in the inspection, and the reference image used in the position / orientation recognition process; Reference control data, a reference image corresponding to the hourly imaging of the inspection camera 6 and the like are registered.
Note that the processing shown in FIG. 10 and the following FIGS. 11 and 12 can be applied to both the defect inspection and the color defect inspection.

  First, ST1 (ST is an abbreviation for “step”. The same applies to the following) accepts the loading of the non-defective workpiece W. When the user installs the non-defective workpiece W on the stage 2 that is stopped at the workpiece loading position A and performs a start operation, it is considered that the acceptance of the non-defective workpiece W has been received, and the process proceeds to ST2.

  Although it is not necessary to perform precise positioning in the workpiece loading process at the time of inspection, the position and orientation of the workpiece W are determined based on a predetermined standard position and standard for the convenience of referring to the CAD data during teaching. The workpiece W is positioned so as to match the direction. Alternatively, after setting the workpiece W, the coordinates of a plurality of predetermined reference points may be input, and the reference position and reference direction may be corrected based on the input data.

  In the next ST2, the stage 2 on which the workpiece W is mounted is moved to the preprocessing position B. In ST3, the pre-processing camera 4 is driven to image the workpiece W. In ST4, the image generated by the imaging in ST3 is registered in the memory as a reference image for position / posture recognition.

  When the registration process is completed, the process proceeds to ST5, and the stage 2 on which the workpiece W is mounted is moved to the inspection position C. In ST6, a number (hereinafter referred to as “registration number”) n for specifying registration data is set to an initial value of 1, and hereinafter, control data and non-defective images used for the n-th imaging are registered.

  In ST7, based on the CAD data of the workpiece W registered in advance, the solid shape of the workpiece W is displayed on the monitor 15, and the user designates one point on the workpiece W, so that the designated point is set as the imaging point P. Accept. In ST8, for this imaging point P, the three-dimensional coordinates and the normal direction are acquired from the CAD data.

  Next, in ST9, it is necessary to align the optical axis of the inspection imaging unit 5 with the normal direction of the designated imaging point P for the scalar robot 9 and the motor 30 of the stage rotation mechanism 3 based on the acquired data. A simple operation amount (expressed as a numerical value representing the rotation direction and rotation angle of each drive shaft) is calculated, and control data for each mechanism is set based on the calculation result. In ST10, the operation of each mechanism is controlled using the set control data. When the operation of each mechanism is completed, the process proceeds to ST11, and the inspection camera 6 causes the work W to be imaged.

  An image generated by this imaging is displayed on the monitor 15. The user confirms whether or not an image suitable for the inspection has been generated for a desired range on the surface of the workpiece W by looking at the display screen, and if it is good, performs a determination operation. When this confirmation operation is performed, the process proceeds from ST12 to ST13, and the control data set in ST9 is registered as the nth reference control data. In ST14, the image generated by the imaging in ST11 is registered as the nth non-defective image.

  On the other hand, when it is determined that the image displayed on the monitor 15 is not suitable for the inspection, the user performs a cancel operation. In this case, ST12 becomes “NO”, the process returns to ST7, and re-designation of the imaging point P is accepted.

  In this way, the set control data and the non-defective image are registered only when it is confirmed that an image suitable for the inspection has been obtained while allowing the user to confirm the image created in accordance with the designation of the imaging point P.

Thereafter, until the user's end operation is performed, the value of n is updated in ST16 and then the process returns to ST7 to accept designation of a new imaging point P. Then, the same procedure as described above is executed for the new imaging point P.
When the user determines that all parts that require inspection of the workpiece W have been imaged and performs an end operation, the process proceeds from ST15 to ST17, and the current value of n is stored as the registration number N. Furthermore, in ST18, the stage 2 on which the workpiece W is mounted is moved to the workpiece unloading position D, the workpiece W is unloaded in ST19, and the process is terminated.

  Next, FIG. 11 and FIG. 12 show the flow of processing for the preprocessing position B and the inspection position C when the teaching is completed and the mode is changed to the inspection mode. These processes are started by a user's inspection start operation, and both processes are executed in parallel by the cooperation of the control processing device 11 and the PLC 10.

FIG. 11 shows the flow of processing for the preprocessing position B.
In the first ST101, after setting the counter k for specifying the workpiece W to be processed to 0, the loop of ST102 to 107 is executed.

  In ST102, the counter k is incremented. In ST103, the work W on the stopped stage 2 is imaged by the preprocessing camera 4. In ST104, the image generated by this imaging is collated with a reference image (for example, a normalized correlation operation is performed), and a positional deviation amount and a rotational deviation amount of the workpiece W are calculated.

  In ST105, the N reference control data registered in the teaching process are corrected using the positional deviation amount and the rotational deviation amount calculated in ST104. In ST106, the corrected control data is temporarily stored in the memory as control data for the kth workpiece W. The stored control data is cleared after being used in the inspection.

  Thereafter, each time the index table 1 rotates 90 ° and stops, the above loop is executed. When the inspection end operation is performed, ST107 is “YES” and the process is ended.

FIG. 12 shows the flow of processing at the inspection position C.
In this process, the initial value zero is set in the counter k in the first ST201, and the process waits until the index table 1 rotates 180 °, in other words, until the first workpiece W arrives at the inspection position C. When the index table 1 is rotated by 180 °, ST202 becomes “YES”, the process proceeds to ST203, and the counter k is incremented. This incremented k is used for the purpose of specifying the control data stored at the preprocessing position B for the workpiece W to be inspected.

  In ST204, initial value 1 is set to registration number n. In ST205, the nth control data of the kth work W is read from the memory. In ST206, each operation of the scalar robot 9 and the stage rotation mechanism 3 is controlled using the read control data. As a result, the optical axis of the inspection imaging unit 5 is aligned with the normal direction of the n-th imaging point P of the workpiece W.

  When the above control is completed, the work W is imaged by the inspection camera 6 in ST207. In ST208, the n-th non-defective image is read from the memory, and a difference calculation process between the non-defective image and the image generated by imaging is performed to generate a difference image indicating a brightness difference between the two images.

  Thereafter, in ST209 and 210, the difference image is binarized, and the presence / absence of a defect is determined using the binarization result. Specifically, the binarization detects pixels whose brightness difference from a non-defective image exceeds a predetermined threshold, counts the number of detected pixels, and the counted value exceeds a predetermined allowable value. In this case, it is determined that “there is a defect”. If the count value of the number of pixels is less than the allowable value, it is determined that there is no defect.

  Hereinafter, until the registration number n reaches the registration number N, n is incremented in ST212, and steps ST205 to 210 are executed for n every hour. As a result, the optical axis of the imaging unit for inspection 5 is sequentially aligned with each imaging point designated during teaching for one workpiece W, and image processing for imaging and inspection is executed.

When the processes of ST205 to 210 are performed for all N imaging points, ST211 becomes “YES”. Here, if the inspection end operation is not performed, ST213 becomes “NO”, the process returns to ST203, and the counter k is incremented again. Thereafter, each time the index table 1 is rotated by 90 ° and stopped, the workpiece W that has reached the inspection position C is sequentially inspected by executing the same processing.
Thereafter, when an inspection end operation is performed at a predetermined time point, ST213 becomes “YES” and the process ends.

  11 and 12, each time the index table 1 stops, the work W on the stage 2 stopped at the inspection position C is inspected, and the work W on the stage 2 stopped at the preprocessing position B is checked. For the next inspection, the control data can be corrected by obtaining the displacement amount of the workpiece W.

  In the appearance inspection apparatus of this embodiment, the rotation control of the stage 2 and the control for the scalar robot 9 are combined, and the optical axis of the inspection imaging unit 5 is aligned with each imaging point P. Therefore, the operation of the scalar robot 9 can be simplified. And adjustment processing for imaging can be performed in a short time. Therefore, the processing efficiency at the inspection position C can be increased.

  In addition, when the work W is brought in at the time of inspection, it is only necessary to place the work W on the stage 2 regardless of the position and orientation as long as the surface contacting the work mounting surface 20 is unified. Even if you do it, it takes less time. Further, it is possible to easily cope with a change in the workpiece W to be inspected.

  In the above embodiment, the scalar robot 9 is used as the imaging unit support mechanism for supporting the imaging unit 5 for inspection. Instead, as shown in FIG. 13, each of X, Y, and Z is used. For each axis, moving mechanisms 101, 102, and 103 that are movable along the axial direction are provided, and the inspection imaging unit 5 is rotatably supported by a holder unit 96 having the same configuration as that shown in FIG. By controlling the operation, the inspection imaging unit 5 may be supported in a state where the position and the direction of the optical axis can be changed.

It is explanatory drawing which shows schematic structure of an external appearance inspection apparatus. It is explanatory drawing which shows the flow of the process for every stage. It is explanatory drawing which shows another apparatus structure. It is explanatory drawing which shows the structure of the imaging part for a test | inspection. It is explanatory drawing which shows the structure of a scalar robot. It is explanatory drawing which shows the example of adjustment of the attitude | position of the imaging part for an inspection by a holder part. It is explanatory drawing which shows the structure of a stage fixing mechanism and a stage rotation mechanism. It is explanatory drawing which shows the flow of operation | movement of the stage fixing mechanism and stage rotation mechanism in a test | inspection position. It is a block diagram of an appearance inspection apparatus. It is a flowchart which shows the flow of the process at the time of teaching. It is a flowchart which shows the flow of a process with respect to a pre-processing position. It is a flowchart which shows the flow of the process with respect to a test | inspection position. It is explanatory drawing which shows the other example of the mechanism which supports the imaging part for a test | inspection.

Explanation of symbols

W Work P Imaging point 1 Index table 2 Stage 3 Stage rotation mechanism 4 Preprocessing camera 5 Inspection imaging unit 6 Inspection camera 7 Illumination device 8 Stage fixing mechanism 9 Scalar robot 10 PLC
11 Control processing device 20 Work surface 21 Rotating shaft

Claims (4)

A plurality of stages having workpiece mounting surfaces of a predetermined width that are not provided with means for fixing the workpieces, are attached via a rotation shaft at regular intervals, and are configured to be movable integrally with these stages. A stage support table in which a predetermined position within the moving range is set as an inspection position;
A plurality of stage fixing mechanisms that are detachably attached to the rotation shafts of the respective stages, and that prevent the rotation of the attached rotation shafts and the corresponding stages;
A stage fixing mechanism is attached to each stage rotation shaft, and the stage support table is moved so that each stage is sequentially sent toward the inspection position. Each time the stage reaches the inspection position, the stage support is supported. A movement control means for temporarily stopping the table;
A stage rotating mechanism that is detachably mounted on the rotating shaft of the stage stopped at the inspection position, and rotates the mounted rotating shaft and the corresponding stage;
An inspection imaging unit for generating an image for inspection of the workpiece;
In the vicinity of the inspection position, an imaging unit support mechanism that supports the imaging unit for inspection in a state where the position and orientation thereof can be changed;
When the stage stops at the inspection position, a preprocessing imaging unit that is arranged so as to be able to image the workpiece mounting surface at the current stop position of the stage that stops at the inspection position next to the stage;
Reference image registration means for registering a reference image of the workpiece mounting surface generated by the preprocessing imaging unit for the stage on which the workpiece is mounted;
The stage rotation mechanism as control data for aligning the optical axis of the imaging unit for inspection with the workpiece when a stage on which the workpiece is mounted at the same position and orientation as shown in the reference image stops at the inspection position. And control data registration means for registering a plurality of data relating to operation control of the imaging unit support mechanism,
Each time the stage support table is stopped, a deviation amount calculating means for obtaining a deviation amount of a workpiece in the image by causing the preprocessing imaging unit to perform imaging and comparing the generated image with the reference image;
Control data correction means for correcting each control data registered in the control data registration means based on the deviation amount of the workpiece calculated by the deviation amount calculation means;
Each time the stage support table stops, the stage rotating mechanism is mounted on the rotating shaft of the stage that is stopped at the inspection position at that time, and the mounting of the stage fixing mechanism on the rotating shaft is released. Using the control data corrected based on the amount of deviation calculated when the stage support table is stopped, the inspection imaging unit is made to perform imaging multiple times while controlling the stage rotation mechanism and the imaging unit support mechanism, and the imaging is performed every hour. An appearance inspection apparatus comprising inspection execution means for executing image processing for inspection using the image generated by.   At least three stages are provided on the stage support table, and a predetermined stage stop position is set as a work carry-in position excluding the inspection position and a position where imaging by the preprocessing imaging unit is performed. The visual inspection apparatus according to claim 1.   The visual inspection apparatus according to claim 2, wherein the stage support table is configured as an index table that rotates by an angle corresponding to an interval between the stages. A plurality of stages each having a workpiece mounting surface of a predetermined width, which are not provided with means for fixing a workpiece, are mounted via a rotation shaft at regular intervals, and can be moved integrally with these stages. Prepare a support table, set a predetermined position of the moving range of this table as the inspection position,
An imaging unit for inspection is supported in the vicinity of the inspection position so that the position and orientation thereof can be changed, and when the stage stops at the inspection position, the current stage of the stage that stops at the inspection position next to the stage In a state where the work mounting surface at the stop position can be imaged, a preprocessing imaging unit is deployed,
For the stage on which the workpiece is mounted, the reference image of the workpiece mounting surface generated by the preprocessing imaging unit is registered, and the stage on which the workpiece is mounted at the same position and orientation as shown in the reference image is As control data for aligning the optical axis of the imaging unit for inspection with the workpiece when stopped at the inspection position, a plurality of data relating to the control of the rotational operation of the rotating shaft and the position and orientation of the imaging unit for inspection are registered. Every
With the rotation axis of each stage fixed, the stage support table is moved so that each stage is sequentially sent toward the inspection position, and the stage support table is temporarily moved each time the stage reaches the inspection position. Stop,
Each time the stage support table stops, the preprocessing imaging unit performs imaging, and the generated image is collated with the reference image to calculate the amount of work displacement in the image,
Each time the stage support table stops, it is calculated at the time when the stage support table is stopped one stage after releasing the fixation of the rotation axis of the stage that is stopped at the inspection position and making the stage rotatable. Using the control data corrected based on the amount of deviation, while controlling the rotation operation of the rotating shaft and the position and orientation of the inspection imaging unit, the imaging unit for inspection performs multiple imaging, and is generated by imaging every hour A surface state inspection method, wherein image processing for inspection is executed using the processed image.

Images