Visual inspection device

Abstract

We provide a visual inspection device that enables detailed visual inspection with a compact configuration. [Solution] The visual inspection apparatus 1 of the present invention comprises a camera Cr for imaging a workpiece 2 to be inspected, and a posture changing device 7 for changing the posture of the workpiece 2 with 2 or more rotational degrees of freedom relative to the camera Cr. The camera Cr is positioned in a fixed state, and the posture changing device 7 is fixed to the camera Cr so as not to move relative to it. The field of view range R2 of the camera Cr is set to be larger than the rotation range R1 of the workpiece 2.

Description

[[Technical Field]]

[0001] The present invention relates to, for example, a visual inspection apparatus that inspects the appearance of parts manufactured on a production line. [[Background Art]]

[0002] As a visual inspection apparatus for inspecting the appearance of parts, there is an apparatus using a robot that changes the position and posture (the angle of the camera relative to the part) of a camera (for example, Patent Document 1). Automation of visual inspection can be achieved by using a robot. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2021-120666 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] The visual inspection apparatus disclosed in Patent Document 1 requires a robot that linearly moves the position of the camera in three directions, and a robot that changes the posture of the camera with three rotational degrees of freedom. As a result, the apparatus increases in size, and a large space is required for installing the apparatus.

[0005] An object of the present invention is to provide a visual inspection apparatus that can achieve detailed visual inspection with a compact configuration. [[Means for Solving the Problem]]

[0006] The visual inspection apparatus of the present invention comprises: a camera that captures an image of a work which is an inspection target; and a posture changing device that changes the posture of the work relative to the camera with two or more rotational degrees of freedom. The camera is arranged in a fixed state, and the posture changing device is fixed so as not to move relatively to the camera. A field of view range of the camera is set to be larger than a turning range of the work.

[0007] With this configuration, the workpiece's orientation is changed relative to the camera by an orientation-changing device having two or more rotational degrees of freedom, enabling detailed visual inspection. Furthermore, since the camera's field of view is set to be larger than the workpiece's rotation range, detailed visual inspection can be achieved even if the positions of the camera and orientation-changing device are fixed. This eliminates the need for a robot to move the camera and / or orientation-changing device horizontally, vertically, etc. As a result, the device can be miniaturized, allowing it to be placed in a narrow space, and the number of parts and control are reduced and simplified. Moreover, since multiple surfaces of the workpiece can be inspected by changing the orientation of the link hub at the tip without rotating the orientation-changing device, cable routing for chucks and other devices mounted on the link hub at the tip becomes easier. Thus, according to the present invention, detailed visual inspection can be achieved with a compact configuration.

[0008] In the present invention, the orientation changing device is configured such that the tip-side link hub is connected to the base-side link hub via three or more link mechanisms to change its orientation. Each link mechanism comprises a base-side and tip-side end link member, one end of which is rotatably connected to the base-side and tip-side link hubs, respectively, and a central link member, both ends of which are rotatably connected to the other ends of these base-side and tip-side end link members. Two or more of the three or more link mechanisms are provided with orientation control actuators that allow the orientation of the tip-side link hub relative to the base-side link hub to be arbitrarily changed, and the workpiece may be placed on the tip-side link hub. With this configuration, by using a link actuation device as the orientation changing device, the device can be miniaturized, and fine orientation control of the workpiece can be performed at high speed. Furthermore, since multiple surfaces of the workpiece can be inspected by changing the orientation of the tip-side link hub alone, without rotating the orientation changing device, cable routing for chucks and the like mounted on the tip-side link hub becomes easier. As a result, more detailed visual inspection can be achieved in a confined space.

[0009] In this invention, the camera may automatically adjust its field of view and depth of field. This configuration further simplifies the control of visual inspection. [Effects of the Invention]

[0010] The visual inspection device of the present invention enables detailed visual inspection with a compact configuration. [Brief explanation of the drawing]

[0011] [Figure 1] This is a front view of a visual inspection device according to the first embodiment of the present invention. [Figure 2A] This is a perspective view of a link actuation device, which is a type of attitude changing device for the same visual inspection device. [Figure 2B] This is a perspective view of the same link actuator, taken from a different angle than in Figure 2A. [Figure 3] This is a front view of the link actuator, with the two link mechanisms omitted. [Figure 4A] Figure 3 is a partial cross-sectional view of the IVA-IVA line. [Figure 4B] This is a cross-sectional view showing an enlarged view of section IVB in Figure 4A. [Figure 5] This diagram shows one of the link mechanisms of the link actuator as represented by straight lines. [Figure 6] This is a front view showing that the central axis of the link hub at the base end and the central axis of the link hub at the tip end of the link actuator are on the same line. [Figure 7] This is a front view showing the state in which the central axis of the tip-side link hub of the link actuator is at a certain operating angle with respect to the central axis of the base-side link hub. [Figure 8] This is a perspective view showing the relationship between the rotation range of the workpiece in the visual inspection device and the depth of field and field of view of the camera. [Figure 9A] This is a front view showing the state of the workpiece at the position furthest from the base end within the operating range of the link actuator. [Figure 9B] This is a front view showing the workpiece at an intermediate height within the operating range of the link actuator. [Figure 9C] It is a front view showing the state of the link actuator when a workpiece is at the position closest to the proximal end within the operating range of the same. [Figure 10] It is a front view showing the operating range of the link actuator. [Figure 11] It is a perspective view showing a modified example of the visual inspection apparatus. [Figure 12] It is a front view of a visual inspection apparatus according to a second embodiment of the present invention. [Figure 13] It is a perspective view of a pan-tilt-roll robot, which is a type of posture changing device for the visual inspection apparatus. [Figure 14] It is a perspective view showing the relationship among the operating range of the workpiece, the depth of field of the camera and the field of view of the visual inspection apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Schematic Structure of Visual Inspection Apparatus> Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a visual inspection apparatus 1 according to a first embodiment of the present invention. The visual inspection apparatus 1 detects whether there are any scratches, deformations, alterations, defects, foreign matter inclusions or the like on a workpiece 2 as an inspection object, and performs surface state confirmation, dimension measurement and the like on the workpiece 2. The workpiece 2 is, for example, a resin molded part manufactured on a production line. However, the workpiece is not limited thereto.

[0013] As shown in FIG. 1, the visual inspection apparatus 1 includes a camera Cr that captures images of the workpiece 2, and a posture changing device 7 that changes the posture of the workpiece 2 with two or more rotational degrees of freedom relative to the camera Cr. In other words, the visual inspection apparatus 1 positions the workpiece 2 with respect to the camera Cr by the link actuator 7 to perform visual inspection of the workpiece 2. The camera Cr and the posture changing device 7 are fixed immovably in the horizontal direction and the vertical direction. In the present embodiment, the posture changing device 7 is arranged below the camera Cr so as not to be relatively movable with respect to the camera Cr.

[0014] In this embodiment, the center line C1 of the camera Cr and the center line C2 of the attitude changing device 7 are positioned to coincide. The direction from the camera Cr toward the attitude changing device 7 (workpiece 2) in the direction in which these center lines C1 and C2 extend is defined as the imaging direction A1. In this embodiment, the imaging direction A1 is downward, but the imaging direction A1 is not limited to this. For example, if the attitude changing device 7 is positioned above the camera Cr, the imaging direction A1 will be upward, and if the attitude changing device 7 and the camera Cr are positioned horizontally, the imaging direction A1 will be horizontal. However, the center line C1 of the camera Cr and the center line C2 of the attitude changing device 7 do not necessarily have to coincide; for example, the camera Cr may be positioned at an angle to be directly beside (horizontally) the attitude changing device 7.

[0015] <Regarding the posture changing device 7> In this embodiment, the attitude changing device 7 is installed on the floor surface. The attitude changing device 7 may be installed directly on the floor surface or on the floor surface via a frame. However, the installation structure of the attitude changing device 7 is not limited to this. The attitude changing device 7 in this embodiment is a link actuation device 7, and as shown in Figures 2A and 2B, it comprises a parallel link mechanism 9 that supports the workpiece 2 so as to be able to change its attitude, and an attitude control actuator 10 that actsuates the parallel link mechanism 9.

[0016] <Parallel link mechanism 9> The parallel link mechanism 9 has a base link hub 12 fixed to the floor, a front link hub 13 to which the workpiece 2 is attached, and three sets of link mechanisms 14 that change the orientation of the front link hub 13 relative to the base link hub 12. The number of link mechanism sets 14 may be four or more. In the following description of the link actuation device 7, the side fixed to the floor is referred to as the base side, and the side to which the workpiece 2 is attached is referred to as the front side. Note that in Figures 1 and 3, only one set of link mechanisms 14 is shown, and the remaining two link mechanisms are omitted.

[0017] Each link mechanism 14 has a base end link member 15, a tip end link member 16, and a central link member 17, and constitutes a four-bar link mechanism consisting of four rotational pairs. Specifically, the four rotational pairs include a rotational pair between the base end link hub 12 and the base end link member 15, a rotational pair between the base end link member 15 and the central link member 17, a rotational pair between the central link member 17 and the tip end link member 16, and a rotational pair between the tip end link member 16 and the tip link hub 13.

[0018] As shown in Figures 2A to 4B, the base and tip end link members 15 and 16 are L-shaped. One end of the base end link member 15 is rotatably connected to the base end link hub 12, and one end of the tip end link member 16 is rotatably connected to the tip end link hub 13. The other ends of the base and tip end link members 15 and 16 are rotatably connected to both ends of the central link member 17.

[0019] The parallel link mechanism 9 is a structure that combines two spherical link mechanisms. As shown in Figure 4A, the central axes O1 of the rotational pairs of the base-side link hub 12 and the base-side end link member 15, and the central axes O2 of the rotational pairs of the base-side end link member 15 and the central link member 17 intersect at the base-side spherical link center PA. Similarly, as shown in Figure 3, the central axes of the rotational pairs of the tip-side link hub 13 and the tip-side end link member 16, and the central axes of the rotational pairs of the tip-side end link member 16 and the central link member 17 intersect at the tip-side spherical link center PB.

[0020] The distance from the center of each rotational pair between the base-side link hub 12 and each end-side link member 15 to the base-side spherical link center PA is the same. Similarly, the distance from the center of each rotational pair between each end-side link member 15 and each central link member 17 to the base-side spherical link center PA is the same. Here, "center of rotational pair" refers to the center in the direction of the centerline of the rotational pair.

[0021] Similarly, the distance from the center of each rotational pair between the tip-side link hub 13 and each end-side link member 16 to the tip-side spherical link center PB is the same. Also, the distance from the center of each rotational pair between each end-side link member 16 and each central link member 17 to the tip-side spherical link center PB is the same.

[0022] The central axes of the rotational pair between the base end link member 15 and the central link member 17, and the central axes of the rotational pair between the tip end link member 16 and the central link member 17, may have a certain intersection angle γ, or they may be parallel, as shown in Figure 3.

[0023] Figure 4A shows the relationship between the central axis O1 of the rotational pair between the base end link hub 12 and the base end link member 15, the central axis O2 of the rotational pair between the base end link member 15 and the central link member 17, and the spherical link center PA. In this embodiment, as shown in the figure, the angle α formed by the central axis O1 of the rotational pair between the base end link hub 12 and the base end link member 15, and the central axis O2 of the rotational pair between the base end link member 15 and the central link member 17, is 90°. However, the angle α may be other than 90°. Although not shown, the shape and positional relationship of the tip end link hub 13 (Figure 3) and the tip end link member 16 (Figure 3) are the same as in Figure 4A.

[0024] The three sets of link mechanisms 14 have the same geometric shape. Geometrically identical shape means that, as shown in Figure 5, the geometric model in which each link member 15, 16, and 17 are represented by straight lines, that is, the model represented by each rotational pair and the straight lines connecting these rotational pairs, has a shape in which the base end portion and the tip end portion are symmetrical with respect to the central part of the central link member 17, regardless of the orientation. Figure 5 is a diagram in which one set of link mechanisms 14 is represented by straight lines. The parallel link mechanism 9 of this embodiment is of the rotationally symmetric type, and the positional relationship between the base end portion, consisting of the base end link hub 12 and the base end link member 15, and the tip end portion, consisting of the tip end link hub 13 and the tip end link member 16, is rotationally symmetric with respect to the center line C of the central link member 17. The central part of each central link member 17 is located on a common orbital circle CO.

[0025] The base link hub 12, the tip link hub 13, and three sets of link mechanisms 14 constitute a two-degree-of-freedom mechanism in which the tip link hub 13 can rotate freely around two orthogonal axes relative to the base link hub 12. In other words, the tip link hub 13 is a mechanism that allows for two degrees of rotation and change of orientation relative to the base link hub 12. This two-degree-of-freedom mechanism is compact while allowing for a wide range of motion of the tip link hub 13 relative to the base link hub 12.

[0026] For example, the central axis QA of the base-side link hub 12 is defined as a straight line passing through the base-side spherical link center PA and intersecting at a right angle with the central axis O1 (Figure 4A) of the rotational pair of the base-side link hub 12 and the base-side end link member 15. Similarly, the central axis QB of the tip-side link hubs 12 and 13 is defined as a straight line passing through the tip-side spherical link center PB and intersecting at a right angle with the central axis O1 (Figure 4A) of the rotational pair of the tip-side link hub 13 and the tip-side end link member 16. In this case, the maximum value of the angle of inclination θ between the central axis QA of the base-side link hub 12 and the central axis QB of the tip-side link hub 13 can be set to approximately ±90°. Furthermore, the rotation angle φ of the tip-side link hub 13 relative to the base-side link hub 12 can be set in the range of 0° to 360°.

[0027] The bending angle θ is the vertical angle at which the central axis QB of the tip-side link hub 13 is inclined relative to the central axis QA of the base-side link hub 12. On the other hand, the rotation angle φ is the horizontal angle at which the central axis QB of the tip-side link hub 13 is inclined relative to the central axis QA of the base-side link hub 12. In this embodiment, the center line C2 of the attitude changing device 7 described above coincides with the central axis QA of the base-side link hub 12.

[0028] The orientation of the tip-side link hub 13 relative to the base-side link hub 12 is changed using the intersection point O of the central axis QA of the base-side link hub 12 and the central axis QB of the tip-side link hub 13 as the center of rotation. Figure 6 shows the state where the central axis QA of the base-side link hub 12 and the central axis QB of the tip-side link hub 13 are on the same line, and Figure 7 shows the state where the central axis QB of the tip-side link hub 13 takes a certain operating angle β with respect to the central axis QA of the base-side link hub 12. As shown in Figure 5, even if the orientation of the tip-side link hub 13 relative to the base-side link hub 12 changes, the distance L between the spherical link centers PA and PB of the base-side and tip-side links does not change.

[0029] As shown in Figures 4A, 4B, and 5, in this parallel link mechanism 9, when all of the following conditions 1 to 4 are met, if the angular positional relationship between the central link member 17 and the base and tip end link members 15 and 16 is the same on both the base and tip sides with respect to the plane of symmetry of the central link member 17, then due to geometric symmetry, the base side portion consisting of the base link hub 12 and the base end link member 15, and the tip side portion consisting of the tip link hub 13 and the tip end link member 16, will move in the same way.

[0030] (Condition 1) In each link mechanism 14, the angle between the central axis O1 of the rotational pair between the base end link hub 12 and the base end link member 15, and the length from the center of the rotational pair to the base end spherical link center PA are equal. In each link mechanism 14, the angle between the central axis O1 of the rotational pair between the tip end link hub 13 and the tip end link member 16, and the length from the center of the rotational pair to the tip end spherical link center PB are equal.

[0031] (Condition 2) The central axis O1 of the rotational pair between the base end link hub 12 and the base end link member 15 of each link mechanism 14, and the central axis O2 of the rotational pair between the base end link member 15 and the central link member 17, intersect with the base end spherical link center PA. The central axis O1 of the rotational pair between the tip end link hub 13 and the tip end link member 16 of each link mechanism 14, and the central axis O2 of the rotational pair between the tip end link member 16 and the central link member 17, intersect with the tip spherical link center PB.

[0032] (Condition 3) The geometric shapes of the base end link member 15 and the tip end link member 16 are equal. (Condition 4) The shape of the central link member 17 is the same at the base end and the tip end.

[0033] As shown in Figures 2A and 3, the base link hub 12 has a flat base member 6 and three rotating shaft connecting members 21 integrally provided with the base member 6. As shown in Figure 4A, a circular through hole 6a is formed in the center of the base member 6, and the three rotating shaft connecting members 21 are arranged around this through hole 6a at equal intervals in the circumferential direction. As shown in Figures 3 and 4A, the center of the through hole 6a is located on the central axis QA of the base link hub 12. As shown in Figure 4B, a rotating shaft 22 whose axis intersects the central axis QA of the base link hub 12 is rotatably connected to each rotating shaft connecting member 21. One end of the base end link member 15 is connected to this rotating shaft 22.

[0034] The rotating shaft 22 has a large-diameter section 22a, a small-diameter section 22b, and a male threaded section 22c sequentially along its axial direction, with the small-diameter section 22b being rotatably supported by the rotating shaft connecting member 21 via two bearings 23. The bearings 23 are, for example, ball bearings such as deep groove ball bearings and angular contact ball bearings. The bearings 23 are fixed by fitting the outer circumferential surface of the outer ring of the bearing 23 into an inner diameter groove provided in the rotating shaft connecting member 21. The types of bearings and installation methods for other rotating paired parts are similar.

[0035] The rotating shaft 22 is positioned concentrically with the output shaft 52a of the reduction mechanism 52, described later, at its large-diameter portion 22a. One end of the base-side end link member 15 is connected to the rotating shaft 22 so as to rotate integrally with it. A notch 25 is formed at one end of the base-side end link member 15, and the portions on both sides of this notch 25 constitute a pair of inner and outer rotating shaft support portions 26 and 27. Through holes are formed in each of these pairs of rotating shaft support portions 26 and 27. The rotating shaft connecting member 21 is positioned within the notch 25, and the small-diameter portion 22b of the rotating shaft 22 is inserted through the through hole and the inner circumferential surface of the inner ring of the bearing 23. The male threaded portion 22c of the rotating shaft 22 protrudes inward from the inner rotating shaft support portion 27.

[0036] A spacer 28 is fitted around the outer circumference of the large-diameter portion 22a of the rotating shaft 22, and the end link member 15 on the base end side and the output shaft 52a of the reduction mechanism 52 are fixed together with a bolt 29 via this spacer 28. Furthermore, a nut is screwed onto the male threaded portion 22c of the rotating shaft 22. A spacer is interposed between the inner ring end face of the bearing 23 and a pair of rotating shaft support portions 26, 27, and preload is applied to the bearing 23 when the nut is screwed on.

[0037] A rotating shaft 35 is connected to the other end of the base-side end link member 15, and is rotatably connected to one end of the central link member 17. Similar to the rotating shaft 22 of the base-side link hub 12, this rotating shaft 35 has a large-diameter portion 35a, a small-diameter portion 35b, and a male threaded portion 35c, and is rotatably supported at one end of the central link member 17 via two bearings 36 at the small-diameter portion 35b. A notch 37 is formed at the other end of the base-side end link member 15, and the portions on both sides of this notch 37 constitute a pair of inner and outer rotating shaft support portions 38 and 39. Through holes are formed in these rotating shaft support portions 38 and 39, respectively. The male threaded portion 35c protrudes inward from the inner rotating shaft support portion 39.

[0038] One end of the central link member 17 is positioned within the notch 37, and the small-diameter portion 35b is inserted through the through hole and the inner circumferential surface of the inner ring of the bearing 36. Furthermore, a nut is screwed onto the male threaded portion 35c. A spacer is interposed between the inner ring end face of the bearing 36 and the pair of rotating shaft support portions 38 and 39. This applies preload to the bearing 36 when the nut is screwed on.

[0039] As shown in Figures 2A and 6, the front-end link hub 13 has a flat end member 40 and three rotating shaft connecting members 41 provided equally spaced circumferentially on the bottom surface of the end member 40. The center of the circumference on which each rotating shaft connecting member 41 is located is on the central axis QB of the front-end link hub 13. A rotating shaft 43, whose axis intersects the central axis QB of the front-end link hub 13, is rotatably connected to each rotating shaft connecting member 41. One end of the front-end end link member 16 is connected to this rotating shaft 43. The other end of the front-end end link member 16 is connected to a rotating shaft 45, which is rotatably connected to the other end of the central link member 17.

[0040] The rotating shaft 43 of the tip-side link hub 13 and the rotating shaft 45 of the central link member 17 have the same shape as the aforementioned rotating shaft 35, and are rotatably connected to the rotating shaft connecting member 41 and the other end of the central link member 17, respectively, via two bearings (not shown).

[0041] <Actuator 10 for attitude control> As shown in Figures 2A and 4A, the attitude control actuator 10 in this embodiment is a rotary actuator equipped with a reduction mechanism 52, and is installed coaxially with the rotation axis 22 on the base end member 6 of the base end link hub 12. The attitude control actuator 10 and the reduction mechanism 52 are provided integrally, and the reduction mechanism 52 is fixed to the base end member 6 by a motor fixing member 53. In this embodiment, attitude control actuators 10 are provided on all three sets of link mechanisms 14, but the attitude of the tip end link hub 13 relative to the base end link hub 12 can be determined by providing attitude control actuators 10 on at least two of the three sets of link mechanisms 14.

[0042] As shown in Figure 4B, the reduction mechanism 52 has a flange output and a large-diameter output shaft 52a. The tip surface of the output shaft 52a is a planar flange surface 54 perpendicular to the center line of the output shaft 52a. The output shaft 52a is connected to the rotation shaft support portion 26 of the base end link member 15 by bolts 29 via a spacer 28. The large-diameter portion 22a of the rotation shaft 22 constitutes the rotational pair portion between the base end link hub 12 (Figure 3) and the base end end link member 15. This rotational pair portion is fitted into an inner diameter groove 57 provided on the output shaft 52a of the reduction mechanism 52.

[0043] As shown in Figures 3 and 4A, the link actuator 7 rotates each attitude control actuator 10, thereby operating the parallel link mechanism 9. More specifically, when the attitude control actuator 10 is rotated, its rotation is reduced via the reduction mechanism 52 and transmitted to the rotating shaft 22. This changes the angle of the end link member 15 on the base side relative to the base link hub 12, and changes the attitude of the front link hub 13 relative to the base link hub 12.

[0044] <Regarding the mounting structure of workpiece 2> As shown in Figures 2A and 2B, in this embodiment, the workpiece 2 is detachably attached to the tip member 40 of the link hub 13 on the tip side of the link actuation device 7 via a gripping device 61. More specifically, the gripping device 61 is attached as an end effector to the tip member 40 of the link hub 13 on the tip side. In this embodiment, a two-jaw chuck is used as the gripping device 61. However, the gripping device 61 is not limited to a two-jaw chuck. In this embodiment, the two jaws are operated by an air cylinder built into the chuck, so that the workpiece 2 is gripped by the gripping device 61 and attached to the link actuation device 7. However, the mounting structure of the workpiece 2 is not limited to this.

[0045] <Regarding the rotation range R1 of Workpiece 2> Figures 8 and 9A to 9C show the rotation range R1 of the workpiece 2 of the visual inspection device 1 of this embodiment, i.e., the operating range of the attitude changing device 7. Figure 9A shows the workpiece 2 at the position furthest from the base end, Figure 9B shows the workpiece at an intermediate height, and Figure 9C shows the workpiece 2 at the position closest to the base end.

[0046] Here, the rotation range R1 of workpiece 2 refers to the trajectory traced by the radial outer end of workpiece 2, that is, the end furthest from the spherical link center PA on the base end side of the attitude change device 7 in workpiece 2. The rotation range R1 may be set to be slightly larger than the trajectory traced by workpiece 2. As shown in Figure 8, the rotation range R1 of workpiece 2 is a nearly spherical part whose center lies on the center line C2 of the attitude change device 7.

[0047] The rotation range R1 of workpiece 2 is set as follows. As shown in Figure 10, Lb is the distance between the spherical link centers PA and PB on the base and tip sides, Lc is the distance from the spherical link center PB on the tip side to the tip surface of the link hub 13 on the tip side, and Ld is the distance from the tip surface of the link hub 13 on the tip side to the tip of workpiece 2. Distance Lb is the same as the distance L between the spherical link centers PA and PB on the base and tip sides in Figure 5. The angle θ in Figure 10 is the bending angle of the link actuator 7 described above.

[0048] In this case, if D is the diameter of the base (circle) of the rotation range R1 which is part of a sphere, and H is the height of the rotation range R1, then the diameter D and height H of the rotation range R1 can be calculated using the following formulas.

number

[0049] <Regarding cameras and lighting equipment> As shown in Figure 1, the camera Cr is installed, for example, on a mount 60 in a suspended state supported horizontally. More specifically, the mount 60 in this embodiment has a plurality of vertical members 60a extending in the vertical direction and a horizontal member 60b connected to the upper end of the vertical members 60a and extending in the horizontal direction, and the camera Cr is immovably supported on the horizontal member 60b. However, the structure of the mount 60 is not limited to this. Also, the support structure for the camera Cr is not limited to the illustrated example.

[0050] As described above, the camera Cr is fixed and cannot move horizontally or vertically. Furthermore, the camera Cr in this embodiment does not have a pan function to move the camera from side to side or a tilt function to move the camera up and down. The camera Cr in this embodiment has a function to automatically adjust the field of view and depth of field (focus).

[0051] The visual inspection apparatus 1 of this embodiment is equipped with a lighting fixture Le for illuminating the workpiece 2. The lighting fixture Le of this embodiment is a ring light with an annular light-emitting part and is mounted on a horizontal member 60b so as to be located on the outer circumference of the camera Cr. The lighting fixture Le is, for example, a light-emitting diode (LED). However, the lighting fixture Le is not limited to a light-emitting diode and may be a fluorescent lamp or a mercury lamp. Also, the lighting fixture Le may be provided at a distance from the camera Cr.

[0052] The central axis C1 of the camera Cr and the central axis of the annular light-emitting part of the illuminator Le are concentrically positioned, and these central axes of the camera Cr and illuminator Le coincide with the central axis QB (Figure 3) of the link hub 13 at the front end. However, the central axes of the camera Cr and illuminator Le do not necessarily coincide with the central axis QB (Figure 3) of the link hub 13 at the front end, and may be parallel to the central axis QB (Figure 3). Furthermore, the central axes of the camera Cr and illuminator Le may be inclined with respect to the central axis QB (Figure 3) of the link hub 13 at the front end.

[0053] However, the lighting fixture Le is not limited to a ring-shaped light, nor is its installation location limited to the position in this embodiment. Specifically, as shown in Figure 11, one or more bar lights Le1, surface lights Le, etc., may be placed in a position that does not interfere with the rotation range R1 of the workpiece 2 and the field of view R2 of the camera Cr.

[0054] <Regarding camera depth of field and field of view> As shown in Figure 8, the depth of field F is defined as the range in the depth direction where the camera Cr is in focus, and the horizontal dimension (the dimension perpendicular to the center line C1 of the camera Cr) is defined as the field of view Fv, with respect to the distance La from the tip of the camera Cr to the workpiece 2. In this embodiment, the field of view Fv is a square with side length A, and the area in focus is a truncated pyramidal pyramid extended from the field of view Fv along the angle of view direction D1 by the depth of field F. This area of ​​the truncated pyramidal pyramid is defined as the field of view range R2. The field of view Fv is not limited to this, and may be a rectangular parallelepiped, for example, as shown in Figure 11.

[0055] As shown in Figure 8, the field of view R2 of camera Cr is set to be larger than the rotation range R1 of workpiece 2. Specifically, the entire rotation range R1, which consists of a part of a sphere, is set to fall within the field of view R2, which consists of a pyramidal pyramidal base.

[0056] Thus, regardless of the orientation of the attitude changing device 7, the entire workpiece 2 is within the field of view R2 of the camera Cr. In particular, even when the workpiece 2 is furthest vertically from the spherical link center PA at the base end (when the workpiece 2 is closest to the camera Cr), as shown in Figure 9A, the entire workpiece 2 is within the field of view R2 of the camera Cr (the range of depth of field F). Furthermore, even when the workpiece 2 is furthest horizontally from the spherical link center PA at the base end, as shown in Figure 9C, the entire workpiece 2 is within the field of view R2 (field of view Fv) of the camera Cr.

[0057] In this embodiment, the field of view and depth of field (focus) of the camera Cr are automatically adjusted, and as shown in Figure 8, the workpiece 2 (rotation range R1) is located within the field of view Fv of the camera Cr and within the area F in which the camera Cr is in focus, i.e., within the field of view R2 of the camera Cr. This allows the workpiece 2 to be visually inspected from any direction, even when the positions of the camera Cr and the attitude changing device 7 are fixed.

[0058] In this embodiment, since the rotation range R1 of the workpiece 2 is within the field of view R2 of the camera Cr, a focused image can be captured even without an adjustment function. By incorporating an automatic adjustment function, the depth of field F and the field of view Fv can be freely set within the space of a pyramidal pyramidal structure extending from the camera Cr. This allows for the acquisition of, for example, partially magnified images, improving the accuracy of visual inspection.

[0059] <Outline of the inspection process using the visual inspection device> Next, the operation of the visual inspection device 1 of this embodiment will be described. First, the workpiece 2 is brought in by a loading device such as a conveyor belt and gripped by the link actuator 7. Next, as shown in Figures 9A to 9C, the link actuator 7 is operated to position the workpiece 2 from various angles relative to the camera Cr and acquire images, and OK / NG judgment is made by image processing.

[0060] The link actuator 7 positions the workpiece 2, for example, by adopting a pre-registered posture, or by executing a pre-created motion pattern. However, the operation of the link actuator 7 is not limited to these methods. Furthermore, image processing is not limited to real-time; at this stage, only image acquisition may be performed, and OK / NG (pass / fail) judgment may be made in a separate process.

[0061] The inspection may be performed with the workpiece 2 fixed in place, while acquiring and processing images, or the orientation of the workpiece 2 may be changed by the link actuator 7 while acquiring and processing images. After the inspection is complete, the workpiece 2 is placed on the discharge device and discharged. The loading device and discharge device may be the same device (for example, a single conveyor) or separate devices. Furthermore, the workpieces 2 that have been judged as good or bad may be classified into good and bad products, and separate discharge locations may be provided for each.

[0062] [Effects and Effects] With the above configuration, the workpiece 2's orientation is changed relative to the camera Cr by the orientation changing device 7, which has two or more rotational degrees of freedom, enabling detailed visual inspection. Furthermore, since the field of view R2 of the camera Cr shown in Figure 8 is set to be larger than the rotation range R1 of the workpiece 2, detailed visual inspection can be achieved even if the positions of the camera Cr and the orientation changing device 7 are fixed. As a result, a robot to move the camera Cr and / or the orientation changing device 7 in the horizontal, vertical, etc., is not required. Consequently, the device is miniaturized, allowing it to be placed in a narrow space, and the number of parts is reduced and control is simplified. Thus, with the above configuration, detailed visual inspection can be achieved with a compact configuration.

[0063] Furthermore, by using the link actuation device 7 as the posture changing device, the device can be miniaturized, and precise posture control of the workpiece becomes possible. As a result, even more detailed visual inspection can be achieved in a confined space.

[0064] In the above embodiment, the camera Cr automatically adjusts its field of view Fv and depth of field F. This ensures that, as shown in Figure 8, the entire workpiece 2 is within the depth of field F and field of view Fv of the camera Cr, regardless of the orientation of the link actuator 7. As a result, the control of visual inspection is further simplified.

[0065] <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to Figures 12 to 13. Figure 12 is a front view of the visual inspection apparatus 1A according to the second embodiment. In the description of the second embodiment, components that are the same as those in the prior embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0066] In the second embodiment, a pan-tilt-roll robot 70 is used as the posture changing device. As shown in Figure 13, the pan-tilt-roll robot 70 is a robot that can rotate in three directions: pan, tilt, and roll. Pan is rotation in the horizontal (left and right) direction, and tilt is rotation in the vertical (up and down) direction. Rolling moves in a direction that rotates the workpiece 2, in addition to these two-axis rotations (pan and tilt).

[0067] If workpiece 2 is rotated using only panning, only the same face of workpiece 2 can be imaged by camera Cr. If workpiece 2 is rotated using rolling in addition to panning, all faces of workpiece 2 can be imaged by camera Cr. Furthermore, if a tilting mechanism is included, the loading and unloading of workpiece 2 can also be performed by robot 70. The other configurations are the same as in the first embodiment.

[0068] In the second embodiment, as shown in Figure 14, the field of view R2 of the camera Cr is set to be larger than the rotation range R1 of the workpiece 2. In other words, regardless of the orientation of the link actuator 7, the entire workpiece 2 can be brought within the depth of field F of the camera Cr and the field of view Fv of the camera Cr. As a result, the control of visual inspection is further simplified.

[0069] In the second embodiment, as shown in Figure 12, the center line C1 of the camera Cr and the center line C2 of the attitude changing device 70 coincide. However, the center line C1 of the camera Cr and the center line C2 of the attitude changing device 70 do not necessarily coincide; for example, the camera Cr may be angled and positioned directly beside (horizontally) the attitude changing device 70. This allows the visual inspection device 1A to be configured compactly in the vertical direction.

[0070] The present invention is not limited to the embodiments described above, and various additions, modifications, or deletions are possible without departing from the spirit of the invention. For example, in the above embodiments, a link actuator 7 was used as the attitude changing device, but the attitude changing device is not limited to the link actuator 7 and the pan-tilt-roll robot, but may be any robot that can be controlled to have two or more degrees of freedom of angle with respect to the camera Cr, such as a horizontal articulated robot (SCARA robot). Therefore, such a robot is also included within the scope of the present invention. [Explanation of Symbols]

[0071] 1.1A Visual Inspection Device 2 Work (Item to be inspected) 7. Link Actuator (Attitude Change Device) 10 Actuators for attitude control 12. Link hub on the base end 13. Link hub at the tip 14 Link mechanism 15. End link member on the base side 16 End link member on the tip side 17 Central link member 70. Pan-Tilt-Roll Robot (Posture Changing Device) CR camera Fv field of view R1 turning range R2 field of view

Claims

1. A fixed-position camera that images the workpiece to be inspected, The device comprises a posture changing device fixed to the camera so as not to move relative to it, which changes the posture of the workpiece with two or more rotational degrees of freedom relative to the camera, An appearance inspection device in which the field of view of the camera is set to be larger than the rotation range of the workpiece.

2. In the visual inspection apparatus according to claim 1, The attitude changing device is, The link hub at the base end is connected to the link hub at the tip end via three or more link mechanisms so that its orientation can be changed. Each of the link mechanisms comprises a base-side and a tip-side end link member, one end of which is rotatably connected to the base-side link hub and the tip-side link hub, respectively, and a central link member, both ends of which are rotatably connected to the other ends of these base-side and tip-side end link members. Two or more of the three or more link mechanisms are provided with attitude control actuators that allow the attitude of the tip-side link hub relative to the base-side link hub to be arbitrarily changed. An appearance inspection device in which the workpiece is positioned on the aforementioned tip-side link hub.

3. The appearance inspection apparatus according to claim 1, wherein the camera is an appearance inspection apparatus in which the field of view and focus are automatically adjusted.

4. In the visual inspection apparatus according to any one of claims 1 to 3, if D is the diameter of the bottom surface of the rotation range R1 of the workpiece and H is the height of the rotation range R1, the diameter D of the rotation range R1 and the height H of the rotation range R1 can be determined by the following formula. [Math 2]

Images