Prism and visual inspection device
The prism with annular reflective surfaces facilitates simultaneous imaging of O-ring surfaces, addressing prolonged inspection times by enabling rapid and accurate inspection of both inner and outer surfaces without rotation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- FIT LLC
- Filing Date
- 2024-11-27
- Publication Date
- 2026-06-08
AI Technical Summary
Conventional appearance inspection apparatuses for O-rings require sequential imaging by multiple cameras to inspect inner and outer surfaces, leading to prolonged inspection times.
A prism with annular reflective surfaces that allow simultaneous imaging of both inner and outer surfaces of an O-ring by a single camera, positioned on one side of the prism, reducing the need for rotation and enabling faster inspection.
The prism enables rapid inspection of both inner and outer O-ring surfaces without flipping, enhancing inspection efficiency and accuracy while simplifying the device configuration.
Smart Images
Figure 2026092793000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a prism used in an appearance inspection apparatus for performing an appearance inspection of a test object. The present invention also relates to an appearance inspection apparatus including such a prism.
Background Art
[0002] Conventionally, an appearance inspection apparatus for inspecting the appearance of an O-ring has been known (see, for example, Patent Document 1). The appearance inspection apparatus described in Patent Document 1 includes a transparent plate on which a placement surface for the O-ring is formed, a diffusion reflection plate disposed below the transparent plate, a rotating stage on which the transparent plate and the diffusion reflection plate are placed, a ring-shaped inner illumination means for irradiating diffused illumination light onto the inner upper surface of the O-ring, an inner camera for photographing the inner upper surface of the O-ring, a ring-shaped outer illumination means for irradiating diffused illumination light onto the outer upper surface of the O-ring, and an outer camera for photographing the outer upper surface of the O-ring. In the appearance inspection apparatus described in Patent Document 1, while rotating the O-ring by a rotating stage, an image of a part of the O-ring is sequentially photographed by the inner camera and the outer camera.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the appearance inspection apparatus described in Patent Document 1, it is possible to inspect the appearance of the inner peripheral side and the outer peripheral side of the O-ring formed in a ring shape. However, in the appearance inspection apparatus described in Patent Document 1, when inspecting the appearance of the O-ring, it is necessary to sequentially photograph an image of a part of the O-ring by the inner camera and the outer camera while rotating the O-ring by a rotating stage, so that the appearance inspection of the O-ring takes time.
[0005] Therefore, an object of the present invention is to provide a prism used in a visual inspection device for visual inspection of an object to be inspected, which can shorten the inspection time of the object to be inspected in the visual inspection device, even if it is possible to perform visual inspection of the inner and outer circumferences of an annular object to be inspected, such as an O-ring. Another object of the present invention is to provide a visual inspection device equipped with such a prism. [Means for solving the problem]
[0006] To solve the above problems, the present invention provides a prism used in an appearance inspection apparatus for inspecting the appearance of an object to be inspected, wherein the prism has a planar mounting surface on which the object to be inspected can be placed, and a first reflective surface and a second reflective surface that reflect light incident from the mounting surface into the interior of the prism, and the direction perpendicular to the mounting surface is defined as the axial direction of the prism, the direction perpendicular to the axial direction is defined as the radial direction of the prism, one side in the axial direction is defined as the first direction side, and the opposite side of the first direction side is defined as the second direction side, and the first reflective surface and the second reflective surface are arranged on the second direction side of the mounting surface. Both reflect light incident on the interior of the prism from the mounting surface toward the first direction, and the shapes of the first and second reflecting surfaces when viewed from the axial direction are annular, the second reflecting surface is located on the outer circumference of the first reflecting surface and is located concentrically with the first reflecting surface when viewed from the axial direction, the first reflecting surface is an inclined surface that slopes toward the second direction as it extends radially outward, and the second reflecting surface is an inclined surface that slopes toward the first direction as it extends radially outward.
[0007] In the prism of the present invention, the first and second reflective surfaces, which reflect light incident into the interior of the prism from a mounting surface on which the object to be inspected can be placed, toward the first direction, have annular shapes when viewed from the axial direction of the prism. The second reflective surface is located on the outer circumference of the first reflective surface and is arranged concentrically with the first reflective surface when viewed from the axial direction. Furthermore, in the present invention, the first reflective surface is an inclined surface that slopes toward the second direction as it extends radially outward from the prism, and the second reflective surface is an inclined surface that slopes toward the first direction as it extends radially outward from the prism.
[0008] Therefore, in a visual inspection apparatus using the prism of the present invention, if the imaging mechanism is positioned on the first direction side of the prism, for example, when inspecting an annular object to be inspected, such as an O-ring, it becomes possible to directly capture an image of the entire portion of the object to be inspected on the first direction side, either directly on the mounting surface or via a transparent glass plate, using the imaging mechanism. At the same time, it becomes possible to capture an image of the entire portion of the object to be inspected on the inner circumference and second direction side as reflected on the first reflective surface, and an image of the entire portion of the object to be inspected on the outer circumference and second direction side as reflected on the second reflective surface, using the imaging mechanism. In other words, in a visual inspection apparatus using the prism of the present invention, if the imaging mechanism is positioned on the first direction side of the prism, it becomes possible to capture an image of the entire annular object to be inspected at once. Consequently, by using the prism of the present invention in a visual inspection apparatus, it becomes possible to perform visual inspection of both the inner and outer circumferences of annular objects to be inspected, such as O-rings, while also shortening the inspection time of the object to be inspected in the visual inspection apparatus.
[0009] Furthermore, by using the prism of the present invention in a visual inspection device, it becomes possible to capture an image of the second-direction side of the object to be inspected without having to turn the object over, thus shortening the inspection time of the object to be inspected in the visual inspection device. In addition, by using the prism of the present invention in a visual inspection device, it becomes possible to capture an image of the outer surface of the object to be inspected reflected on the second reflective surface, thus enabling more accurate inspection of the object to be inspected. Moreover, by using the prism of the present invention in a visual inspection device and arranging the imaging mechanism on the first-direction side of the prism, it becomes possible to capture an image of the entire annular object to be inspected at once, thus simplifying the configuration of the visual inspection device.
[0010] In the present invention, for example, in a longitudinal section of a prism including the axis of the prism, the first reflective surface and the second reflective surface are represented by two straight lines, and the inclination angle of the first reflective surface with respect to the radial direction is equal to the inclination angle of the second reflective surface with respect to the radial direction.
[0011] The prism of the present invention can be used in a visual inspection device equipped with a photographic mechanism positioned on the first direction side of the prism. In this visual inspection device, even if it is possible to perform visual inspection of the inner and outer circumferences of an annular object to be inspected, such as an O-ring, it is possible to shorten the inspection time of the object to be inspected.
[0012] In the present invention, for example, the object to be inspected is an O-ring, and the O-ring placed on the mounting surface is arranged concentrically with the first reflective surface when viewed from the axial direction, and is positioned to overlap with either the first or second reflective surface. [Effects of the Invention]
[0013] As described above, by using the prism of the present invention in a visual inspection device, it becomes possible to perform visual inspection of the inner and outer circumferences of an annular object to be inspected, such as an O-ring, while also shortening the inspection time of the object to be inspected in the visual inspection device. [Brief explanation of the drawing]
[0014] [Figure 1] (A) is a schematic diagram illustrating the configuration of an appearance inspection device according to an embodiment of the present invention, (B) is a plan view of the prism shown in (A), (C) is a cross-sectional view of the object to be inspected and the prism shown in (A), and (D) is a bottom view of the prism shown in (A). [Figure 2] Figure 1 is a diagram illustrating the configuration of the prism shown. [Figure 3] Figure 1 is a diagram illustrating the image captured by the imaging mechanism shown. [Modes for carrying out the invention]
[0015] Embodiments of the present invention will be described below with reference to the drawings.
[0016] (Configuration of the visual inspection device and prism) Figure 1(A) is a schematic diagram illustrating the configuration of the visual inspection device 1 according to an embodiment of the present invention; Figure 1(B) is a plan view of the prism 3 shown in Figure 1(A); Figure 1(C) is a cross-sectional view of the O-ring 2 and prism 3 shown in Figure 1(A); and Figure 1(D) is a bottom view of the prism 3 shown in Figure 1(A). Figure 2 is a diagram illustrating the configuration of the prism 3 shown in Figure 1. Figure 3 is a diagram illustrating the image captured by the camera 4 shown in Figure 1.
[0017] The visual inspection device 1 is a device for visually inspecting the object to be inspected 2. In this embodiment, the object to be inspected 2 is an O-ring formed in an annular shape. Therefore, in the following description, the object to be inspected 2 will be referred to as "O-ring 2". The O-ring 2 is made of rubber. When no external force is applied, the shape of the O-ring 2 is annular. The visual inspection device 1 inspects for scratches and distortions on the surface of the O-ring 2, and for the presence of foreign matter on the surface of the O-ring 2. The visual inspection device 1 is equipped with a prism 3. That is, the prism 3 is used in the visual inspection device 1. In addition to the prism 3, the visual inspection device 1 is equipped with a camera 4 as an imaging mechanism positioned above the prism 3. The visual inspection device 1 in this embodiment is equipped with one camera 4.
[0018] The camera 4 is disposed directly above the O-ring 2. The camera 4 is installed such that the optical axis of the camera 4 coincides with the vertical direction (the Z direction in FIG. 1(A)). The optical axis of the camera 4 passes through, for example, the axis of the O-ring 2 placed on a mounting surface 3c (to be described later) formed on the prism 3. In the vertical direction, an illumination mechanism (not shown) for applying light to the O-ring 2 is disposed between the O-ring 2 and the camera 4. That is, the appearance inspection apparatus 1 includes the illumination mechanism. The illumination mechanism is a bright-field illumination mechanism that directly applies light to the O-ring 2 from directly above. Further, the illumination mechanism is, for example, a ring illumination formed in a ring shape and is disposed at a position that does not interfere with the photographing by the camera 4.
[0019] The prism 3 is formed of, for example, transparent glass or resin. The prism 3 is formed in a substantially frustum shape that is flat with a short axial length with the vertical direction (the Z direction in FIG. 1(A)) as the axial direction. Specifically, the prism 3 is composed of a flat cylindrical (disk-shaped) portion that constitutes approximately the upper half of the prism 3 and a flat frustum-shaped portion that constitutes approximately the lower half of the prism 3 and whose outer diameter gradually decreases toward the lower side. The direction orthogonal to the vertical direction (i.e., the axial direction of the prism 3) is the radial direction of the prism 3.
[0020] The prism 3 is attached to a support member (not shown). A through-hole 3a penetrating the prism 3 in the vertical direction is formed at the center of the prism 3. A concave portion 3b that is recessed upward is formed on the lower surface side of the prism 3. The concave portion 3b is formed at the center of the lower surface side of the prism 3. The concave portion 3b is formed in a frustum shape whose outer diameter gradually decreases upward. The lower end of the through-hole 3a is connected to the upper end of the concave portion 3b.
[0021] In addition, the prism 3 is formed with a planar mounting surface 3c on which the O-ring 2 can be placed, and a first reflecting surface 3d and a second reflecting surface 3e that reflect light incident from the mounting surface 3c into the interior of the prism 3. The mounting surface 3c is a plane orthogonal to the vertical direction. That is, the vertical direction, which is the axial direction of the prism 3, is perpendicular to the mounting surface 3a. Also, the upper side (the Z1 direction side in FIG. 1(A)) of this embodiment is the first direction side, which is one side of the axial direction of the prism 3, and the lower side (the Z2 direction side in FIG. 1(A)) is the second direction side, which is the other side of the axial direction of the prism 3.
[0022] The mounting surface 3c constitutes the upper surface of the prism 3 and faces upward. The mounting surface 3c is formed in a circular shape. In this embodiment, the O-ring 2 is placed directly on the mounting surface 3c. The first reflecting surface 3d and the second reflecting surface 3e are disposed below the mounting surface 3c. The first reflecting surface 3d and the second reflecting surface 3e reflect the light incident from the mounting surface 3c into the interior of the prism 3 upward. The shapes of the first reflecting surface 3d and the second reflecting surface 3e when viewed from the vertical direction are in an annular shape. The second reflecting surface 3e is disposed on the outer peripheral side of the first reflecting surface 3d and is arranged concentrically with the first reflecting surface 3d when viewed from the vertical direction, and surrounds the first reflecting surface 3d when viewed from the vertical direction. The first reflecting surface 3d and the second reflecting surface 3e are arranged concentrically with the through-hole 3a when viewed from the vertical direction.
[0023] The first reflecting surface 3d constitutes the side surface of a concave portion 3b formed in a frustum of a cone shape. The first reflecting surface 3d is an inclined surface that slopes downward as it goes toward the outer side in the radial direction of the prism 3. When viewed from the vertical direction, the first reflecting surface 3d surrounds the through-hole 3a. The second reflecting surface 3e constitutes the side surface of the lower portion of the prism 3 formed in a frustum of a cone shape. The second reflecting surface 3e is an inclined surface that slopes upward as it goes toward the outer side in the radial direction of the prism 3.
[0024] The inner diameter of the annularly formed second reflective surface 3e is slightly larger than the outer diameter of the annularly formed first reflective surface 3d. For example, the outer diameter of the first reflective surface 3d is approximately 21 mm, and the inner diameter of the second reflective surface 3e is approximately 22 mm. Also, the outer diameter of the second reflective surface 3e is approximately 50 mm. Between the first reflective surface 3d and the second reflective surface 3e in the radial direction of the prism 3, an annular plane, the torus surface 3f, is formed, perpendicular to the vertical direction. The width of the annular surface 3f in the radial direction of the prism 3 is narrow.
[0025] As shown in Figure 1(C), etc., in the longitudinal cross-section of the prism 3 including the axis of the prism 3, the first reflective surface 3d and the second reflective surface 3e are represented by two straight lines. In this embodiment, the inclination angle θ1 of the first reflective surface 3d with respect to the radial direction of the prism 3 (see Figure 2(A)) and the inclination angle θ2 of the second reflective surface 3e with respect to the radial direction of the prism 3 (see Figure 2(A)) are equal. The inclination angles θ1 and θ2 are, for example, about 15°. The shape of the lower surface of the longitudinal cross-section of the prism 3 is W-shaped.
[0026] The outer diameter D (see Figure 1(C)) of the O-ring 2 inspected by the visual inspection device 1 is, for example, 30 mm or 20 mm. The O-ring 2 placed on the mounting surface 3c is positioned concentrically with the first reflective surface 3d when viewed from above. That is, the O-ring 2 is placed on the mounting surface 3c such that it is positioned concentrically with the through hole 3a, the first reflective surface 3d, and the second reflective surface 3e when viewed from above. For example, if the outer diameter of the O-ring 2 is 30 mm, the O-ring 2 placed on the mounting surface 3c is positioned to overlap with the second reflective surface 3e when viewed from above (see Figure 2(A)), and if the outer diameter of the O-ring 2 is 20 mm, the O-ring 2 placed on the mounting surface 3c is positioned to overlap with the first reflective surface 3d when viewed from above (see Figure 2(B)).
[0027] As shown in Figure 2, the first reflective surface 3d reflects light emitted from the illumination mechanism and incident on the prism 3 from above toward the inner circumference and lower part of the O-ring 2, and also reflects the light reflected by the O-ring 2 upward toward the camera 4. The second reflective surface 3e reflects light emitted from the illumination mechanism and incident on the prism 3 from above toward the outer circumference and lower part of the O-ring 2, and also reflects the light reflected by the O-ring 2 upward toward the camera 4.
[0028] Light that is reflected by O-ring 2 and then further reflected by the first reflective surface 3d before heading towards camera 4 passes on the inner circumference of O-ring 2. The inclination angle θ1 of the first reflective surface 3d is set so that light that is reflected by O-ring 2 and then further reflected by the first reflective surface 3d before heading towards camera 4 is not obstructed by O-ring 2. Light that is reflected by O-ring 2 and then further reflected by the second reflective surface 3e before heading towards camera 4 passes on the outer circumference of O-ring 2. The inclination angle θ2 of the second reflective surface 3e is set so that light that is reflected by O-ring 2 and then further reflected by the second reflective surface 3e before heading towards camera 4 is not obstructed by O-ring 2.
[0029] For example, when the appearance inspection of an O-ring 2 with an outer diameter of 30 mm is performed by the appearance inspection device 1, the camera 4 directly captures an image P1 of the entire upper part of the O-ring 2, as well as an image P2 of the entire inner and lower part of the O-ring 2 reflected on the first reflective surface 3d, and an image P3 of the entire outer and lower part of the O-ring 2 reflected on the second reflective surface 3e (see Figure 3). In other words, when the appearance inspection of the O-ring 2 is performed by the appearance inspection device 1, the camera 4 captures an image of the entire O-ring 2 at once. Images P1 to P3 are annular images and are arranged concentrically. Also, image P2 is positioned on the inner side of image P1, and image P3 is positioned on the outer side of image P1.
[0030] Similarly, when the visual inspection of an O-ring 2 with an outer diameter of 20 mm is performed by the visual inspection device 1, the camera 4 directly captures an image of the entire upper portion of the O-ring 2, as well as an image of the entire inner and lower portion of the O-ring 2 reflected on the first reflective surface 3d, and an image of the entire outer and lower portion of the O-ring 2 reflected on the second reflective surface 3e. A personal computer (PC) is electrically connected to the camera 4. The images captured by the camera 4 are transmitted to the PC. Based on the images captured by the camera 4, the PC determines whether there are any scratches or distortions on the surface of the O-ring 2, and whether there are any foreign substances attached to the surface of the O-ring 2.
[0031] (Main effects of this form) As described above, in this embodiment, the first reflective surface 3d and the second reflective surface 3e, which reflect light incident from the mounting surface 3c into the interior of the prism 3 upwards, have annular shapes when viewed from above. The second reflective surface 3e is positioned on the outer circumference of the first reflective surface 3d and is concentric with the first reflective surface 3d when viewed from above. Furthermore, in this embodiment, the first reflective surface 3d is an inclined surface that slopes downwards as it extends radially outward from the prism 3, and the second reflective surface 3e is an inclined surface that slopes upwards as it extends radially outward from the prism 3.
[0032] Therefore, in this embodiment, as described above, an overall image P1 of the upper part of the O-ring 2 is directly captured by the camera 4, and an overall image P2 of the inner and lower part of the O-ring 2 reflected on the first reflective surface 3d, and an overall image P3 of the outer and lower part of the O-ring 2 reflected on the second reflective surface 3e are also captured by the camera 4. In other words, in this embodiment, an overall image of the O-ring 2 is captured by the camera 4 at once. Consequently, in this embodiment, even though it is possible to perform visual inspection of the inner and outer circumferences of the annularly formed O-ring 2, the inspection time of the O-ring 2 in the visual inspection device 1 can be shortened.
[0033] Furthermore, in this embodiment, it becomes possible to capture an image of the lower part of the O-ring 2 with the camera 4 without having to invert the O-ring 2, thus further reducing the inspection time of the O-ring 2 in the visual inspection device 1. In addition, in this embodiment, it becomes possible to capture an image of the outer surface of the O-ring 2 reflected on the second reflective surface 3e with the camera 4, thus enabling more accurate inspection of the O-ring 2. Moreover, in this embodiment, by positioning the camera 4 above the prism 3, it becomes possible to capture an image of the entire ring-shaped O-ring 2 at once, thus simplifying the configuration of the visual inspection device 1.
[0034] (Other embodiments) In the above-described configuration, the O-ring 2 does not necessarily have to be placed directly on the mounting surface 3c. For example, the O-ring 2, which is placed on a thin, flat transparent glass plate, may be placed on the mounting surface 3c together with the glass plate. In other words, the O-ring 2 may be placed on the mounting surface 3c via a glass plate or the like. In this case, by pre-placing the O-rings 2 on each of the multiple glass plates while the visual inspection device 1 is offline, it becomes possible to easily replace the O-rings 2 set in the visual inspection device 1.
[0035] In the above-described configuration, the first reflective surface 3d is represented by two straight lines in the longitudinal section of the prism 3. However, the first reflective surface 3d may be formed in such a way that it is represented by two curves in the longitudinal section of the prism 3. That is, the first reflective surface 3d may be formed as a convex curved surface that bulges inward and downward in the radial direction of the prism 3, or as a concave curved surface that sinks outward and upward in the radial direction of the prism 3. Even in this case, the first reflective surface 3d is an inclined surface that slopes downward as it moves outward in the radial direction of the prism 3. Furthermore, in this case, it becomes possible to change the size of the image P2 captured by the camera 4.
[0036] Similarly, the second reflective surface 3e may be formed such that it is represented by two curves in the longitudinal section of the prism 3. That is, the second reflective surface 3e may be formed as a convex curved surface that bulges outward and downward in the radial direction of the prism 3, or as a concave curved surface that sinks inward and upward in the radial direction of the prism 3. Even in this case, the second reflective surface 3e is an inclined surface that slopes upward as it moves outward in the radial direction of the prism 3. In this case, it becomes possible to change the size of the image P3 captured by the camera 4.
[0037] In the above-described configuration, the prism 3 does not necessarily have an annular surface 3f. That is, the inner diameter of the second reflective surface 3e and the outer diameter of the first reflective surface 3d may be equal. Also, in the above-described configuration, the inclination angle θ1 of the first reflective surface 3d and the inclination angle θ2 of the second reflective surface 3e may be different. Furthermore, in the above-described configuration, the object to be inspected 2, which is visually inspected by the visual inspection device 1, may be an annular sealing member other than an O-ring, such as a packing or gasket, or an annular member other than a sealing member. Also, the object to be inspected 2 may be formed in an annular shape other than an annular shape, or it may not be formed in an annular shape at all. For example, the object to be inspected 2 may be formed in a C shape. Furthermore, in the above-described configuration, the illumination mechanism for illuminating the O-ring 2 may be a dark-field illumination mechanism. [Explanation of Symbols]
[0038] 1. Visual inspection device 2 O-ring (object under inspection) 3 prisms 3c Mounting surface 3d 1st reflective surface 3e 2nd reflective surface 4. Camera (shooting mechanism) Z prism axis Z1 1st direction side Z2 2nd direction side θ1 Inclination angle of the first reflecting surface θ2 Inclination angle of the second reflecting surface
Claims
1. A prism used in a visual inspection device for performing visual inspection of an object to be inspected, The prism has a planar mounting surface on which the object to be inspected can be placed, and a first reflective surface and a second reflective surface that reflect light incident from the mounting surface into the interior of the prism. If the direction perpendicular to the mounting surface is defined as the axial direction of the prism, the direction perpendicular to the axial direction is defined as the radial direction of the prism, one side in the axial direction is defined as the first direction side, and the side opposite the first direction side is defined as the second direction side, The first reflective surface and the second reflective surface are arranged on the second direction side of the aforementioned mounting surface, and reflect light incident from the aforementioned mounting surface into the interior of the prism toward the first direction side. The shapes of the first and second reflective surfaces when viewed from the axial direction are annular. The second reflective surface is positioned on the outer periphery of the first reflective surface and is arranged concentrically with the first reflective surface when viewed from the axial direction. The first reflective surface is an inclined surface that slopes toward the second direction as it moves outward in the radial direction, A prism characterized in that the second reflective surface is an inclined surface that slopes toward the first direction as it moves outward in the radial direction.
2. In the longitudinal section of the prism including the axis of the prism, the first reflective surface and the second reflective surface are represented by two straight lines. The prism according to claim 1, characterized in that the inclination angle of the first reflecting surface with respect to the radial direction is equal to the inclination angle of the second reflecting surface with respect to the radial direction.
3. An appearance inspection apparatus comprising a prism according to claim 1 or 2, and an imaging mechanism disposed on the first direction side of the prism.
4. The object to be inspected is an O-ring, The appearance inspection apparatus according to claim 3, characterized in that the O-ring placed on the mounting surface is arranged concentrically with the first reflective surface when viewed from the axial direction, and is positioned to overlap with the first reflective surface or the second reflective surface.