Reflection type surface defect detection device

Abstract

The utility model discloses a reflective surface defect detection device. The device comprises a plurality of reflective surfaces (16); a base (14) for supporting an object; and a single camera (12) placed in a predetermined position; wherein each reflective surface (16) is configured to be located near one edge of the object to reflect a virtual image having a similar depth of field to the camera (12), the plurality of reflective surfaces (16) being configured to be movable in an x-y-z-theta direction respectively until at least one virtual image is substantially perpendicular to the line of sight of the camera (12), wherein theta is the inclination angle of the corresponding reflecting surface relative to the horizontal plane. The detection device only needs one camera, and is flexible to use, easy to manufacture and low in cost while the detection efficiency is improved.

Description

Technical Field

[0001] The invention relates to a system for photographing defects on the surface of an object in a single camera setup. Background Art

[0002] Typically, when inspecting irregular shaped objects for surface defects, multiple cameras are used in the setup. Each camera captures images or videos from a different angle or viewpoint of the object. These cameras can be strategically positioned to cover various areas of the irregular shaped object. A common reason for requiring multiple cameras in irregular shaped surface defect inspection is for complete coverage. For example, irregular shaped objects often have intricate details and complex surfaces that may be difficult to fully capture from a single viewpoint. By using multiple cameras, different perspectives of the object can be obtained, resulting in better coverage and a more comprehensive surface inspection. Since irregular shapes may have different depths, depressions, or protrusions that cannot be adequately captured by a normal single camera setup, multiple cameras are placed at different angles to achieve better depth perception and accurately identify defects in three-dimensional space.

[0003] While a multi-camera setup offers several advantages for irregular-shaped surface defect detection, this approach also has significant disadvantages and drawbacks. Implementing a multi-camera setup can be expensive. Each camera requires its own hardware, lenses, and image processing capabilities, which can significantly increase the overall cost of the defect detection system. In addition, the infrastructure required to synchronize and manage multiple cameras can further increase expenses. Managing and calibrating multiple cameras can be complex and time-consuming. Aligning the cameras, ensuring consistent lighting conditions for all cameras, and synchronizing image capture can be challenging tasks. The setup and configuration of a multi-camera system can require specialized knowledge and expertise.

[0004] In addition, multiple cameras take up additional space and may require specific mounting or positioning arrangements to effectively cover the entire irregular-shaped object. Depending on the size and complexity of the object, finding the right location for the camera while avoiding occlusion or interference can be a logistical challenge. Processing data from multiple cameras can be computationally intensive. The images or videos captured by each camera need to be synchronized, stitched together, and processed to accurately detect defects. The increased amount of data may also require greater storage capacity and longer processing time, affecting the real-time performance of the inspection system.

[0005] At the same time, the requirements for maintaining and calibrating multiple cameras over time can be high. Regular calibration is necessary to ensure accurate alignment, focus, and exposure settings for each camera. Any changes in camera performance or hardware degradation may require adjustment or replacement, adding further maintenance requirements. Lack of flexibility results in a system with poor versatility and adaptability to different inspection scenarios.

[0006] U.S. Patent No. 9294672B2 discloses an array camera that exhibits little or no parallax artifacts in captured images. For example, the planes of the central reflector prism of the array camera may intersect at a vertex that defines a vertical axis of symmetry for the system. The vertex may serve as the intersection of the optical axes of the sensors in the array. Each sensor in the array "sees" a portion of the image scene using a corresponding face of the central reflector prism, so each individual sensor / reflector pair represents only a sub-aperture of the entire array camera. The complete array camera has a synthetic aperture generated based on the sum of all individual aperture rays. However, because it requires multiple cameras to operate, another disadvantage is increased production costs.

[0007] Chinese patent application number CN113607750A discloses a technology combining spectral confocal, laser scattering and laser induced ultrasound methods for non-destructive detection of subsurface defects in ultra-precision optical components. It uses a dispersion lens group to focus the excitation and detection lasers at different depths within the component. The excitation laser produces thermal expansion, which causes ultrasonic vibrations in subsurface defects. The detection laser analyzes this vibration, while the spectral confocal technology captures the spatial distribution and scattered spectrum information. The technology provides multi-dimensional information, including reflection and scattering spectra, 3D shape and depth of defects, so that defects can be characterized. However, the technology is complex, costly, time-consuming and labor-intensive.

[0008] Therefore, there is a need for an effective system to image defects on product surfaces with different geometries that is flexible, easy to manufacture and low-cost, requires only a single camera and improves computational efficiency, thereby requiring processing of fewer cameras. Summary of the invention

[0009] The object of the present invention is to develop an effective system for photographing surface defects of geometric objects at a relatively low cost.

[0010] Another object of the present invention is to reduce processing time, power consumption and computational complexity of processing captured images.

[0011] Therefore, these objectives can be achieved by following the teachings of the present invention, which provides a reflective surface defect detection device, comprising: multiple reflective surfaces; a base for supporting an object; and a single camera placed at a predetermined position; wherein each reflective surface is configured to be located near an edge of the object to reflect a virtual image with a similar depth of field to the camera, and the multiple reflective surfaces are configured to be movable along the xyz-θ direction respectively until at least one virtual image is approximately perpendicular to the line of sight of the camera, wherein θ is the inclination angle of the corresponding reflective surface relative to the horizontal plane.

[0012] The present invention places a camera at a predetermined position, and adjusts multiple reflective surfaces along the xyz-θ direction until at least one virtual image is approximately perpendicular to the camera line of sight, so that the virtual image after reflection is clear, and only one camera is needed to photograph defects on the surface of products with different geometric shapes. Since a single camera is used, fewer cameras need to be processed compared to the prior art, which greatly improves the calculation efficiency and reduces the cost. It is easy to manufacture and flexible to use, and can well meet the needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Features of the present invention will be more readily understood and appreciated when the following detailed description is read in conjunction with the accompanying drawings of preferred embodiments of the present invention, in which:

[0014] Figure 1 is a side view of the present invention;

[0015] Figure 2 A top view of the present invention;

[0016] Figure 3 An embodiment of the present invention configured to move in the xyz-θ direction is shown;

[0017] Figure 4 A structural diagram showing an embodiment of the present invention; and

[0018] Figure 5 A flow chart showing a configuration of the present invention is shown. DETAILED DESCRIPTION

[0019] In order to promote and understand the principles of the present invention, reference will now be made to the embodiments shown in the accompanying drawings and described in the following written specification. It should be understood that the present invention includes any changes and modifications to the illustrated embodiments, and includes further applications of the principles of the present invention that would normally occur to a person skilled in the art to which the present invention belongs.

[0020] The present invention teaches a reflective surface defect detection device for use in a single camera setting, the device comprising: a plurality of reflective surfaces (16) configured to move in an xyz-θ direction; and a base (14), wherein the base (14) supports an object, and the plurality of reflective surfaces (16) are strategically positioned near each edge of the object to reflect virtual images with similar depth of field to a camera (12). The camera (12) is placed at a predetermined position, and the plurality of reflective surfaces are adjusted along the xyz-θ direction until at least one virtual image is approximately perpendicular to the camera line of sight, so that the virtual image after reflection is clear. The device as a whole is as follows Figure 1 and Figure 2 shown.

[0021] In one embodiment of the present invention, the plurality of reflective surfaces are optical mirrors with a size of 4×7 cm.

[0022] In one of the embodiments, at least 4 optical mirrors are configured for a cube-shaped object, and at least 8 optical mirrors are configured for a complex object.

[0023] In another embodiment of the present invention, the base (14) includes but is not limited to a turntable.

[0024] In one embodiment, the base (14) is adjustable to a predetermined height to obtain a working distance for capturing virtual images of the reflective surface area and compressing these virtual images into a single image. The base (14) can be attached to the board support (18) while maintaining flexibility of the base (14) and the reflective surface in capturing the virtual image of the object.

[0025] In another embodiment of the present invention, the plurality of reflective surfaces may be moved in the xyz direction, thereby allowing greater coverage of the object surface area and allowing a greater working distance to photograph the reflective surface area, such as Figure 3 shown.

[0026] In another embodiment, an angle θ or an angle θ′ or an optimized tilt angle is adopted between each of the plurality of reflective surfaces and a corresponding edge of the cube-shaped object.

[0027] In one embodiment of the present invention, when taking an image of a complex object, the reflection device (10) is adjusted along the xyz-θ direction so that the reflected virtual image is within a desired similar depth of field.

[0028] In another embodiment, an angle θ or an angle θ' or an optimized tilt angle is adopted between each of the plurality of reflective surfaces and a corresponding edge of the complex object. The tilt angle prevents deformation of the virtual image of the reflective surface area.

[0029] For example, when the present invention is used to detect surface defects of an oblate ellipsoid, the xyz coordinates of the mirror and the equivalent working distance of the virtual image captured by the camera can be adjusted to the required depth of field range and meet the resolution requirements. The optimized mirror tilt angle θ can be easily calculated by the following formula:

[0030]

[0031] Where D is the working distance between the camera (12) and the top surface of the object; L is the length of the object, and α is the side view angle of the camera, such as Figure 4 In this case, 4 mirrors are sufficient to reflect the entire upper spherical surface area of ​​the product.

[0032] Another embodiment of the present invention is a method for photographing defects on the surface of an object using a reflective device (10) in a single camera setting, the method comprising: (a) determining the number of reflective surfaces (16); (b) positioning the reflective device (10) near each edge of the object placed on a base (14); (c) placing a camera (12) at a predetermined position; (d) adjusting the working distance and camera parameters; (e) moving the reflective device (10) along the xyz-θ direction until at least one reflected virtual image is approximately perpendicular to the camera line of sight and the reflected virtual image is clear; (f) performing quality control, wherein if the surface coverage is to be further tested, steps (a) to (f) need to be repeated, or if the image quality is to be further tested, step (e) needs to be repeated, and the flowchart of the configuration process is further as shown in FIG. Figure 5 shown.

[0033] The camera lens is an autofocus lens with a focal length of 12 mm, but the type of camera and lens will vary depending on the subject being photographed.

[0034] The invention has several advantages, including the ability to reflect different surface areas that are not visible to a single camera, thereby reducing the number of cameras required and being more cost-effective. By properly configuring the position and tilt angle of the optical mirror, different surface areas can be reflected to the camera with little deformation. With the help of the mirror, the different surface areas are compressed into a single image, thereby reducing processing time and computational complexity. Finally, by reconfiguring the mirror, the device can be easily adjusted to accommodate products of other shapes.

[0035] The present invention described above is not limited to the above embodiments and the accompanying drawings, and it is obvious to those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention.

Claims

1. A reflective surface defect detection device, comprising: a plurality of reflective surfaces (16); A base (14) for supporting an object; as well as a single camera (12) placed at a predetermined position; Each reflective surface (16) is configured to be located near an edge of the object to reflect a virtual image with a similar depth of field to the camera (12), and the multiple reflective surfaces (16) are configured to be movable along the xyz-θ direction until at least one virtual image is approximately perpendicular to the line of sight of the camera (12), wherein θ is the inclination angle of the corresponding reflective surface relative to the horizontal plane.

2. The device according to claim 1, characterized in that The reflective surface is an optical mirror.

3. The device according to claim 2, characterized in that The device comprises at least 4 optical mirrors.

4. The device according to claim 2, characterized in that The device comprises at least 8 optical mirrors.

5. The device according to claim 1 or 4, characterized in that: The plurality of reflective surfaces (16) are configured to be movable along the xyz-θ directions respectively so that the reflected virtual images are within a desired similar depth of field.

6. The device according to claim 1, characterized in that The base (14) is a turntable.

7. The device according to claim 1, characterized in that The height of the base (14) is adjustable.

8. The device according to claim 3 or 4, characterized in that The inclination angle of each of the plurality of reflective surfaces relative to the corresponding edge of the object is: Where D is the distance between the camera and the top surface of the object, L is the length of the object, and α is the viewing angle of the camera.

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