Inner surface image inspection device

Abstract

The present application aims to provide an inner surface image inspection device that can flexibly cope with various inspection objects with different inner diameters. The inner surface image inspection device (1) inspects the inner surface of the hole of the inspection object and comprises: an imaging unit (2), a lens barrel (3) installed in front of the imaging unit (2) and accommodating lenses (4, 5) of the optical system, a light source unit (6) that can be attached and detached relative to the lens barrel (3), a spectroscope (10) that reflects the illumination light from the light source unit (6) in a direction parallel to the optical axis of the optical system, a cylindrical insertion unit (11) installed at the front end of the lens barrel (3) and inserted into the hole of the inspection object, a reflector (15) arranged inside the insertion unit (11) in such a manner that the reflective surface is tilted relative to the optical axis of the lenses (4, 5) of the optical system, and a direct-acting mechanism (16) that moves the reflector (15) in a manner parallel to the optical axis.

Description

Technical Field

[0001] The present application relates to an inner surface image inspection device. Background Art

[0002] An internal surface image inspection device for inspecting the inner surface of an inspection object, such as a cylindrical member, comprises an imaging unit, an optical system, a light source, and a reflector. The reflector is located in an insertion portion that is inserted into the cylindrical member during inspection. Illuminating light from the light source is reflected by the reflector and irradiated onto the inner surface of the cylindrical member. Light reflected from the inner surface of the cylindrical member passes through the optical system and enters the imaging unit, capturing an image of the inner surface. This internal image allows for inspection of surface characteristics of the cylindrical member's inner surface.

[0003] However, each optical system determines the distance from the objective lens (or its glass cover) to the object, namely the working distance (WD), as an inherent value. Therefore, it is necessary to prepare multiple inner surface image inspection devices with different working distances WD according to the inner diameter of the cylindrical member, or to have an optical system capable of changing the working distance WD. Summary of the Invention

[0004] Problems to be solved by the invention

[0005] It is desired to obtain an inner surface image inspection device that can flexibly handle various inspection objects having different inner diameters.

[0006] Means used to solve problems

[0007] One aspect of the present disclosure is an inner surface image inspection device for inspecting the inner surface of a hole to be inspected. The inner surface image inspection device comprises: an imaging unit; a lens barrel mounted in front of the imaging unit and housing an optical system; a light source unit detachably mounted to the lens barrel; a beam splitter for reflecting illumination light from the light source unit in a direction parallel to the optical axis of the optical system; a cylindrical insertion unit mounted at the front end of the lens barrel and inserted into the hole to be inspected; a reflector disposed within the insertion unit with its reflective surface tilted relative to the optical axis of the optical system; a linear motion mechanism disposed within the insertion unit and configured to move the reflector parallel to the optical axis; and a linear motion control unit that controls the linear motion mechanism to move the reflector so that a distance from the front surface of a lens of the optical system, through the reflector, to the inner surface of the hole to be inspected matches a reference operating distance of the optical system, the reference operating distance being the distance from the front end of the lens to the inner surface of the hole to be inspected, where the lens is in focus.

[0008] Effects of the Invention

[0009] According to this aspect, it is possible to flexibly cope with inspections of various inspection objects having different inner diameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is an external view of an inner surface image inspection device according to one embodiment.

[0011] Figure 2 yes Figure 1 Structural diagram of the inner surface image inspection device.

[0012] Figure 3 It shows that Figure 1 A diagram showing an example of use of an inner surface image inspection device mounted on a robot device.

[0013] Figure 4 It shows Figure 2 Supplementary diagram of the direct-acting control method of the direct-acting control unit.

[0014] Figure 5 It shows Figure 1 Figure 2 is a diagram of another structural example of an inner surface image inspection device. DETAILED DESCRIPTION

[0015] The following describes an inner surface image inspection device according to one embodiment of the present invention with reference to the accompanying drawings. This embodiment of the inner surface image inspection device inspects the surface characteristics, etc., of a bottomed hole or through-hole as an inspection target, thereby capturing an image of the inner surface. This description uses a cylindrical member as an example of the inspection target.

[0016] like Figure 1 、 Figure 2As shown, the inner surface image inspection device 1 of this embodiment includes an imaging unit 2. The imaging unit 2 includes an image sensor 20, such as a CCD (Charge-coupled Device). A lens barrel 3 is mounted in front of the imaging unit 2. An optical system, preferably comprising telecentric lenses, including lenses 4 and 5, is retained within the lens barrel 3. A portion of the side surface of the lens barrel 3 is opened, and a light source unit 6 having a coaxial port 7 is detachably mounted within the opening. The light source unit 6 includes a telecentric lens 8 and a light source 9, such as an LED spotlight. Together with a beam splitter 10, such as a half mirror, arranged at a 45° angle relative to the optical axis OA of the optical system, the light source unit 6 constitutes a coaxial epi-illumination unit. Alternatively, the coaxial epi-illumination unit may be a pseudo-coaxial epi-illumination unit. Furthermore, as long as the inspection surface inside the cylindrical member WK can be uniformly illuminated, the system is not limited to coaxial epi-illumination. To simplify the structure, the following description will be based on the case where coaxial epi-illumination with a coaxial port 7 is used. The inner surface of the cylindrical member WK is curved, and since images are repeatedly taken around the entire circumference of the inner surface during inspection, a telecentric optical system with an angle of view of 0 or a value close thereto is preferred because this system does not cause inspection errors due to dimensional changes.

[0017] An insertion portion 11 is attached to the front end of the lens barrel 3. This insertion portion 11 is inserted into the cylindrical member WK, which serves as the inspection target. The insertion portion 11 comprises a cylindrical body 14, with a circular inspection window 12 and a notch 13 for sensing light formed in the side openings of the cylindrical body 14. A reflector 15, such as a right-angle prism, is housed within the cylindrical body 14. The reflector 15 is arranged so that its reflecting surface is tilted 45° relative to the optical axis OA of the optical system. Alternatively, the reflector 15 may be a plane mirror installed at a 45° tilt relative to the optical axis OA of the optical system. The reflector 15 projects an image of the inspection target surface (the inner surface of the cylindrical member WK) onto the imaging surface of the image sensor 20. Furthermore, illumination light from the light source unit 6 is emitted from the inspection window 12 in a direction perpendicular to the optical axis via the beam splitter 10 and the reflector 15, irradiating the inner surface of the cylindrical member WK. Inside the cylindrical body 14, a reflector 15 and a linear motion mechanism 16 are housed. This linear motion mechanism 16 supports the reflector 15 so that it can move linearly along the optical axis OA. Suitable linear motion mechanism 16 may include any structure, such as a ball screw mechanism or a cylindrical cam mechanism used in zoom lens mechanisms of conventional cameras. While the reflector 15 is described here as being electrically movable, it can also be moved manually.

[0018] Furthermore, the operating distance WD is defined as the distance on the optical axis OA from the front surface of the objective lens 5 of the optical system or its cover glass, via the reflector 15, to the imaging target surface (the inner surface of the cylindrical member WK). For ease of explanation, this is defined as the distance on the optical axis OA from the front surface of the objective lens 5 of the optical system, via the reflector 15, to the inner surface of the cylindrical member WK. Furthermore, the operating distance WD from the front end of the objective lens 5 to the imaging target surface on which the objective lens 5 is focused is referred to as the reference operating distance WD0.

[0019] By moving the reflector 15, the distance on the optical axis OA between the front surface of the objective lens 5 of the optical system and the reflecting surface of the reflector 15 changes. As a result, the distance on the optical axis OA (operating distance WD) between the front surface of the objective lens 5 of the optical system and the inner surface of the cylindrical member WK also changes. By moving the reflector 15 to an appropriate position according to the inner diameter of the cylindrical member WK, the operating distance WD can be made consistent with the reference operating distance WD0. This allows for flexible handling and elimination of defocusing when inspecting various cylindrical members WK with different inner diameters. In other words, even if the reference operating distance WD0 of the optical system is fixed, defocusing can be eliminated and the surface characteristics of various cylindrical members WK with different inner diameters can be inspected with high precision.

[0020] Inside the insertion portion 11, a distance sensor 17 is provided, along with a reflector 15 and a linear motion mechanism 16. This distance sensor 17 is used to measure the distance from the optical axis OA of the optical system to the inner surface of the cylindrical member WK, or to derive the distance from the optical axis OA of the optical system to the inner surface of the cylindrical member WK. Any type of distance sensor 17, such as a reflective optical type or an ultrasonic type, is suitable. Here, the distance sensor 17 is described as a reflective optical type. Laser light, for example, from the distance sensor 17 is output from the insertion portion 11 via the light sensing notch 13, reflected by the inner surface of the cylindrical member WK, and received by the distance sensor 17.

[0021] The control unit 21 includes an overall control unit 22; an imaging control unit 23 that drives and controls the image sensor 20 to output an image signal; a light source drive unit 24 that drives the light source 9; a direct-acting drive unit 25 that drives the direct-acting mechanism 16; a sensor control unit 26 that drives and controls the distance sensor 17 and calculates the distance to the inner surface of the cylindrical member WK; and a direct-acting control unit 27. The direct-acting control unit 27 controls the direct-acting drive unit 25 based on the distance to the inner surface of the cylindrical member WK calculated by the sensor control unit 26, thereby moving the reflective mirror 15 to an appropriate position.

[0022] like Figure 3As shown, when inspecting a cylindrical member WK using the inner surface image inspection device 1, the inner surface image inspection device 1 is typically mounted on the front end of the arm of a multi-jointed robot 40. Of course, other methods may be employed, such as fixing the inner surface image inspection device 1 to an inspection table and using the multi-jointed robot 40 to move the cylindrical member WK to the inspection position. The former method will be described herein as an example.

[0023] On the base 42, a connecting rod 44 is mounted via a rotating joint J1 for rotation. On the connecting rod 44, a connecting rod 46 is connected via a rotating joint J2 for forward and backward rotation. On the connecting rod 46, a connecting rod 50 is connected via a rotating joint J3 for up and down rotation. On the connecting rod 50, a connecting rod 52 is connected via a rotating joint J4 for torsional rotation. On the connecting rod 52, a fixing frame 54 is connected via a rotating joint J5 for wrist bending rotation. A fixing frame plate 56 is provided on the fixing frame 54, and the fixing frame plate 56 is used to install the inner surface image inspection device 1 as an end effector. The fixing frame plate 56 is set to be freely axially rotatable through the rotating joint J6. The inner surface image inspection device 1 is mounted on the fixing frame plate 56 in such a way that its optical axis OA is consistent with the rotation center line of the rotating joint J6. During inner surface image inspection, the multi-jointed robot 40 is operated to insert the inner surface image inspection device 1 into the cylindrical member WK at the inspection position and rotate ideally about the optical axis OA. In sync with this rotation, the image sensor 20 repeatedly captures images of the inner surface of the cylindrical member WK.

[0024] Next, the position control of the reflector 15 by the direct-acting control unit 27 will be described. Figure 4 As shown in (a), when the reflector 15 is typically located at the center position (referred to as the reference position) P0 of the movable range, and the distance on the optical axis OA from the front surface of the objective lens 5 through the reflector 15 to the inner surface of the cylindrical member WK0 (the operating distance WD) is consistent with the reference operating distance WD, the inner diameter of the cylindrical member WK0 at this time is set to the reference diameter R0.

[0025] like Figure 4As shown in (b) of FIG. 1 , the direct-acting control unit 27 controls the direct-acting drive unit 25 based on the distance R1 between the optical axis OA and the inner surface of the cylindrical member WK1, calculated by the sensor control unit 26 based on the detection signal of the distance sensor 17, or a distance from which this distance R1 can be derived, thereby moving the reflector 15. The direction of movement is determined by comparing the distances R0 and R1. When the distance R1 is longer than the distance R0, the reflector 15 moves from the reference position P0 toward the lens barrel 3. The distance (displacement) ΔD1 from the reference position P0 to the moved position P1 is set to the absolute value of the difference between the distances R0 and R1, namely, |R0-R1|. This allows the operating distance WD1 on the optical axis OA, from the front surface of the objective lens 5 through the reflector 15 to the inner surface of the cylindrical member WK1, to coincide with the reference operating distance WD.

[0026] When inspecting the cylindrical member WK2 having a smaller inner diameter than the cylindrical member WK1, the same Figure 4 As shown in (c), when distance R2 is shorter than distance R0, the lens barrel 3 moves away from the reference position P0. The distance (displacement) ΔD2 from the reference position P0 to the post-displacement position P2 is set to the absolute value of the difference between distance R0 and distance R2: |R0-R2|. This allows the operating distance WD2 on the optical axis OA, from the front surface of the objective lens 5 through the reflector 15 to the inner surface of the cylindrical member WK1, to coincide with the reference operating distance WD.

[0027] As described above, when inspecting various cylindrical components with different inner diameters, by moving the reflector 15 linearly along the optical axis OA, the movement distance WD on the optical axis OA from the front surface of the objective lens 5 through the reflector 15 to the inner surface of the cylindrical component WK can be made consistent with the specified distance, especially the reference movement distance WD0. Therefore, the inner surface image inspection device of this embodiment can flexibly cope with various cylindrical components WK with different inner diameters, thereby eliminating defocus and inspecting the surface characteristics of the inner surface of the cylindrical component WK with high precision.

[0028] Here, when the inner surface image inspection device 1 is mounted on the fixed frame plate 56, an installation error may occur, which may cause the optical axis OA of the inner surface image inspection device 1 to be inconsistent with the rotation centerline of the rotation joint portion J6. When the inner surface image inspection device 1 is rotated in this state, the operating distance WD on the optical axis OA from the front surface of the objective lens 5 to the inner surface of the cylindrical member WK changes according to the rotation angle. In this embodiment, since the distance between the optical axis OA and the inner surface of the cylindrical member WK1 can be repeatedly measured by the distance sensor 17, the reflector 15 is dynamically moved as the measured distance changes and the inner surface image inspection device 1 rotates, so that the operating distance WD can be aligned with the reference operating distance WD0 over the entire circumference.

[0029] In addition, even if the inner surface of the inspection object is not a perfect circle but an ellipse, and has a slightly concave-convex shape, as described above, as the distance between the optical axis OA measured by the distance sensor 17 and the inner surface of the cylindrical member WK1 changes, the reflector 15 is dynamically moved along with the rotation of the inner surface image inspection device 1, so that the action distance WD can be made consistent with the reference action distance WD0 over the entire circumference.

[0030] Furthermore, while the above description is based on a configuration equipped with the distance sensor 17, a configuration without the distance sensor 17 is also possible. The user can move the reflector 15 to any position via the direct-acting control unit 27. Typically, when the user inputs a designed inner diameter into the direct-acting control unit 27, the reflector 15 can be moved to a position where the operating distance WD matches the reference operating distance WD0.

[0031] Furthermore, in the above description, a case where the reflecting mirror 15 is moved electrically has been described, but a configuration where the reflecting mirror 15 is moved manually may also be employed.

[0032] In addition, if Figure 5 As shown, the reflector 15 can be replaced with a conical mirror 30 with a 90° apex angle. Of course, the conical mirror 30 is positioned so that its centerline coincides with the optical axis OA. The circular inspection window 12 on the side of the insertion portion 11 can also be replaced with a slit-shaped inspection window 31 extending all around. Without rotating the inner surface image inspection device 1, a single lens can capture images of the entire inner surface.

[0033] Although certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present invention. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes may be made to the embodiments of the methods and systems described herein without departing from the spirit of the present invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the present invention.

Claims

1. An inner surface image inspection device for inspecting the inner surface of a hole of an inspection object, wherein the inner surface image inspection device is characterized by: Camera Department, The lens barrel is installed in front of the camera unit and houses the optical system. The light source unit is detachable relative to the lens barrel. a beam splitter that reflects the illumination light from the light source unit in a direction parallel to the optical axis of the optical system; The cylindrical insertion portion is mounted on the front end of the lens barrel and is inserted into the hole of the inspection object. The reflecting mirror is arranged inside the insertion portion in such a manner that the reflecting surface is inclined relative to the optical axis of the optical system. a linear motion mechanism disposed inside the insertion portion and moving the reflector in parallel with the optical axis; and a direct-acting control unit that controls the direct-acting mechanism to move the reflective mirror so that a distance from the front surface of the lens of the optical system to the inner surface of the hole of the inspection object via the reflective mirror coincides with a reference operating distance of the optical system, the reference operating distance being the distance from the front end of the lens to the inner surface of the hole of the inspection object on which the lens is focused; A distance sensor is further provided for measuring the distance from the optical axis of the optical system to the inner surface of the hole of the inspection object. The direct motion control unit controls the direct motion mechanism so as to dynamically move the reflective mirror as the distance measured by the distance sensor changes.

2. The inner surface image inspection device according to claim 1, characterized in that The light source unit includes a telecentric lens.

3. The inner surface image inspection device according to claim 1, wherein The optical system includes a telecentric lens.

4. The inner surface image inspection device according to claim 1, wherein The reflector is a right-angle prism reflector or a plane reflector installed at an angle of 45° relative to the optical axis.

5. The inner surface image inspection device according to claim 1, wherein: The reflecting mirror is a conical mirror.

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