JP2004361243A - Apparatus and method for inspecting lustrous surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for inspecting a lustrous surface, which can carry out inspections online in a mass production process very accurately and very speedily. <P>SOLUTION: The apparatus for inspecting the lustrous surface is provided with: a light projecting section 1 which projects laser light Y obliquely onto the lustrous surface; a camera 3 which photographs the lustrous surface by using reflection light of the laser light Y reflected thereon; an image processing means 4 which obtains distortion of regular reflection light from image data photographed by the camera 3; and a determining means 5 which detects surface defects in the lustrous surface on the basis of the distortion of the regular reflection light obtained by the image processing means 4. If the direction normal to the lustrous surface is used as the reference, the inclination α of the laser light Y preferably ranges from 45 degrees to 85 degrees. The laser light projected by the light projecting section 1 preferably has zonal light beams. A semiconductor laser is preferably used for projecting the laser light in the light projecting section 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a glossy surface inspection apparatus and method for inspecting surface defects on a glossy surface.
[0002]
[Prior art]
Today, dry batteries, various household appliances, drinking water, and the like are mass-produced and stored in containers or housings made of metal, plastic, glass, and the like. The surface of such a metal or plastic or glass container or housing is generally glossy.
[0003]
Inspection of surface defects of containers or housings of various products such as the above dry batteries must be performed online in a mass production process because various products are mass-produced. Have been.
[0004]
On the other hand, as non-destructive flaw detection methods for metal surfaces, for example, a fluorescent magnetic particle flaw detection method (see Japanese Patent Application Laid-Open No. H10-282603), a liquid penetration flaw detection method, an ultrasonic flaw detection method (see Japanese Patent Application Laid-Open No. 2002-139479, etc.), radiation A flaw detection method (see JP-A-5-177351), a magnetic flaw detection method (see JP-A-6-201654), and the like have been developed.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H10-28063 [Patent Document 2]
JP 2002-139479 A [Patent Document 3]
JP-A-5-177351 [Patent Document 4]
JP-A-6-201654
[Problems to be solved by the invention]
The above-mentioned conventional method for inspecting a glossy surface relies on the skill of an inspector, and thus has errors and misperceptions due to visual observation as fundamental problems, and there are certain restrictions on improving the accuracy and speed of inspection. is there. In addition, in the above-described conventional method for inspecting a glossy surface, it is not easy to visually determine a surface defect due to halation, reflection of illumination, and the like on the glossy surface. Further, in the above-described conventional method for inspecting a glossy surface, it is difficult to determine a stain which can be corrected in a subsequent coating process or the like and a surface defect such as a scratch, and there is an inconvenience that even a problem-free stain is detected.
[0007]
In addition, although the nondestructive flaw detection method for the metal surface described above requires a high level of inspection, it basically performs a relatively long time offline inspection on a large object. It cannot be applied to online inspections in mass production processes such as.
[0008]
The present invention has been made in view of these inconveniences, and an object of the present invention is to provide a glossy surface inspection apparatus and method which can be performed on-line in a mass production process, with extremely high inspection accuracy and speed. .
[0009]
[Means for Solving the Problems]
The invention made in order to solve the above-described problem is a light emitting unit that irradiates a laser beam from a diagonal direction to a glossy surface, a camera that captures reflected light of the laser light on the glossy surface, and an image captured by the camera. The glossy surface inspection apparatus includes image processing means for acquiring distortion of regular reflection light from image data, and determination means for detecting a surface defect on a glossy surface based on distortion of regular reflection light acquired by the image processing means.
[0010]
The glossy surface inspection device uses the fact that if there is a defect such as a scratch or unevenness on the glossy surface, the specular reflection light of the laser beam irradiated from the oblique direction on the glossy surface is distorted. And the type of defect are inspected. Specifically, the glossy surface inspection apparatus irradiates the glossy surface with laser light from an oblique direction by a light emitting unit, captures reflected light of the laser light from the glossy surface by a camera, and images captured by an image processing unit. The distortion of the specular reflection light is obtained from the data, and the determining means detects a surface defect on the glossy surface based on the distortion of the specular reflection light.
[0011]
Therefore, the glossy surface inspection apparatus can prevent an inspection error and an erroneous recognition caused by visual observation such as halation or reflection of illumination, and can greatly improve the accuracy and speed of the inspection. Further, the glossy surface inspection apparatus can determine the type and degree of the surface defect based on the magnitude and shape of the distortion of the regular reflection light acquired by the image processing means. Further, since the glossy surface inspection device does not affect the distortion of the specular reflection light even if there is a dirt on the glossy surface, it is possible to reduce the detection of dirt that can be corrected by a subsequent coating process and has no problem in commercialization. be able to.
[0012]
The inclination angle of the laser light with respect to the normal direction of the glossy surface is preferably 45 ° or more and 85 ° or less. By setting the inclination angle of the laser beam irradiated by the light projecting unit within the above range, distortion of the regular reflection light due to a surface defect becomes remarkable, and inspection accuracy can be improved.
[0013]
It is preferable that the laser beam emitted by the light emitting section has a band-like light beam. By irradiating a laser beam having a band-like light beam in this manner, it is easy to obtain the distortion of the specularly reflected light, and the entire glossy surface can be inspected by scanning in one direction.
[0014]
It is preferable to use a semiconductor laser for the irradiation of the laser beam in the light emitting section. Such a semiconductor laser is preferable in that a laser beam having a sufficient output for observing reflected light on a glossy surface can be obtained with a relatively wide range of devices, and a laser beam around visible light suitable for image processing of the reflected light can be obtained.
[0015]
Further, an invention according to a glossy surface inspection method made to solve the above-mentioned problem includes an irradiation step of irradiating a laser beam from a diagonal direction to a glossy surface, and an imaging step of photographing a reflected light of the laser light on the glossy surface A process for acquiring distortion of specular reflection light from the image data of the reflected light; and a determination step of detecting a surface defect on the glossy surface based on the distortion of the regular reflection light. The glossy surface inspection method, like the above glossy surface inspection apparatus, has remarkably high inspection accuracy and speed, and can be incorporated on-line in a mass production process to dramatically improve productivity.
[0016]
Here, "specular reflection light" means mirror reflection light when there is no defect such as a scratch or unevenness on the glossy surface. "The normal direction of the glossy surface" means the normal direction of the glossy surface assuming that there is no defect.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a flowchart showing a glossy surface inspection method according to one embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing a glossy surface inspection device for performing the glossy surface inspection method of FIG. 1, and FIG. (B) is a schematic diagram showing image data when there is no surface defect and when there is a surface defect.
[0018]
The inspection method of the glossy surface shown in FIG. 1 includes an irradiation step (STP1) of irradiating the glossy surface with a laser beam from an oblique direction, an imaging step (STP2) of imaging the reflected light of the laser beam on the glossy surface, It has an image processing step (STP3) for acquiring distortion of regular reflection light from image data, and a determination step (STP4) for detecting a surface defect on a glossy surface based on the distortion of regular reflection light.
[0019]
The glossy surface inspection device shown in FIG. 2 is a device that performs the above-described glossy surface inspection method and inspects the surface (glossy surface) of the inspection object X. Specifically, the glossy surface inspection apparatus includes a light projecting unit 1, a projection screen 2, a camera 3, an image processing unit 4, a determination unit 5, and a table 6.
[0020]
The image processing unit 4 and the determination unit 5 are systematically configured by a computer including a control unit including a CPU, a ROM, a RAM, a hard disk, a monitor, a keyboard, and the like. The control unit controls each unit based on a program so as to function as the image processing unit 4 and the determination unit 5.
[0021]
The light projecting unit 1 irradiates the surface of the inspection object X placed on the table 6 with the laser beam Y from an oblique direction. As the laser beam transmitting mechanism of the light projecting unit 1, a known technology capable of irradiating the laser beam Y is employed. However, since the glossy surface inspection apparatus is for observing the reflected light of the laser light Y and detecting the surface defect of the inspection object X, the laser light Y may have an output enough to observe the reflected light. Therefore, as the laser light transmitting mechanism of the light projecting unit 1, a semiconductor laser that can irradiate the laser light Y having a wavelength near the visible light suitable for observing the distortion of the reflected light and has a relatively simple mechanism is particularly preferable. preferable.
[0022]
The projection screen 2 is a plate-like body that projects the reflected light of the laser light Y from the surface of the inspection object X. The projection screen 2 is disposed in a direction facing the light projecting unit 1 with respect to the inspection object X, and is disposed perpendicular to the surface of the inspection object X.
[0023]
The camera 3 captures an image projected on the projection screen 2, that is, the reflected light of the laser light Y from the surface of the inspection object X. The camera 3 is not particularly limited as long as the reflected light of the laser light Y can be photographed, and various known cameras can be used. However, as the camera 3, a two-dimensional CCD camera, which has a relatively simple device itself and directly acquires digital image data used for image processing, is particularly preferable.
[0024]
The image processing unit 4 acquires the distortion of the specularly reflected light based on the image data captured by the camera 3. In the image processing means 4, the method of acquiring the distortion of the specular reflected light is as follows: (a) a method of obtaining from the exclusive theoretical sum based on the image data when there is no distortion of the specular reflected light (that is, in the case of specular reflection) , (B) a method of calculating an approximate curve of the regular reflection light of the laser beam Y from the image data, and obtaining a portion deviating from the approximate curve.
[0025]
The determination unit 5 detects a surface defect of the inspection object X based on the distortion of the regular reflection light acquired by the image processing unit 4. Specifically, the type of the surface defect can be determined by the shape of the distortion of the specular reflection light, and the degree of the surface defect can be determined by the magnitude of the distortion of the specular reflection light.
[0026]
The glossy surface inspection apparatus irradiates the surface (glossy surface) of the inspection object X with the laser beam Y from an oblique direction by the light emitting unit 1 (irradiation step STP1), and the camera 3 emits the laser light from the surface of the inspection object X. The reflected light of the light Y is photographed (photographing step STP2), the distortion of the regular reflected light is acquired from the image data photographed by the image processing means 4 (image processing step STP3), and the distortion of the regular reflected light acquired by the determination means 5 is obtained. The surface defect of the inspection object X can be detected based on the above (determination step STP4). In other words, the glossy surface inspection apparatus utilizes the fact that when there is a defect such as a scratch or unevenness on the surface (glossy surface) of the inspection object X, distortion occurs in the specular reflection light of the laser light irradiated from an oblique direction. The image processing unit 4 acquires the distortion of the specular reflection light, and the surface defect of the glossy surface is detected by the determination unit 5 based on the distortion of the regular reflection light.
[0027]
Therefore, according to the glossy surface inspection apparatus, automation is possible, and the accuracy and speed of the inspection can be remarkably improved as compared with the conventional visual inspection. Further, according to the glossy surface inspection apparatus, it is possible to determine the type and degree of the surface defect based on the magnitude and shape of the distortion of the regular reflection light acquired by the image processing unit 4. Furthermore, according to the glossy surface inspection apparatus, even if there is dirt on the glossy surface, it does not affect the distortion of the specular reflection light. Only the surface defects that need to be detected can be detected.
[0028]
The lower limit of the inclination angle α of the laser beam Y with respect to the normal direction of the surface of the inspection object X is 45 °, particularly 50 °, more preferably 55 °, and the upper limit of the inclination angle α is 85 °, In particular, it is preferably 80 °, more preferably 75 °. By setting the inclination angle α of the laser beam Y to be equal to or larger than the lower limit as described above, the distortion of the regular reflection light caused by the surface defect of the inspection object X becomes remarkable, and the inspection accuracy of the glossy surface inspection apparatus is improved. be able to. On the other hand, when the inclination angle α of the laser beam Y is equal to or less than the above upper limit, the distortion of the specular reflection light caused by the surface defect of the inspection object X becomes too large, and the light amount of the distorted portion decreases. The inconvenience that the inspection accuracy of the inspection device is reduced can be reduced.
[0029]
The laser beam Y emitted by the light projecting unit 1 preferably has a band-like light beam. By irradiating the laser beam Y having a belt-like light beam in this manner, (a) it is easy to obtain the distortion of the regular reflection light, and the inspection accuracy is improved. (B) The glossy surface is scanned by scanning in one direction. The whole surface can be inspected, and there is an advantage that the inspection speed is improved.
[0030]
As a scanning method of the glossy surface inspection apparatus, (a) a method of moving the table 6 on which the inspection object X is mounted in the XY direction on the surface thereof, and (b) moving the light projecting unit 1 in parallel with the table 6 And (c) a method in which the light projecting unit 1 is driven in a swinging manner to change the irradiation direction of the laser light Y. In the case of changing the irradiation direction of the laser light Y in the above (c), by feeding back the irradiation direction information of the laser light Y to the determination unit 5, the error of the distortion of the regular reflection light caused by the irradiation direction of the laser light Y is reduced. Can be corrected.
[0031]
When scanning the outer peripheral surface of the columnar inspected object X using the laser beam Y having a band-shaped light beam, the light beam surface of the laser beam Y was inclined at a predetermined angle from the longitudinal axis of the inspected object X. It is preferable that the inspection object X be installed in a state where the outer peripheral surface of the inspection object X is obliquely cut by the laser beam Y, and the inspection object X be rotated around the longitudinal axis to scan the entire peripheral surface. According to this scanning method, it is possible to scan the entire peripheral surface by simply rotating the inspection object X by one rotation, and it is possible to inspect a surface defect even if the positioning in the irradiation direction of the laser beam Y is somewhat rough.
[0032]
Next, the theory of defect detection on the glossy surface by the glossy surface inspection apparatus and method will be described. First, when a flat glossy surface having no surface defects is irradiated with a laser beam Y having a band-like luminous flux from an oblique direction, the reflected light of the laser beam Y has a linear shape as shown in FIG. There is only regular reflection light. On the other hand, when a laser light Y having a band-like light beam is irradiated from an oblique direction to a flat glossy surface having a dent, the reflected light of the laser light Y becomes linear regular reflection as shown in FIG. It has a light part A and a convex distortion part B. The shape and size of the distorted portion B correspond to the type and size of the surface defect. Therefore, by recognizing the distorted portion B by image processing, it is possible to determine the presence, type, and degree of a surface defect.
[0033]
It should be noted that the glossy surface inspection apparatus and method of the present invention are not limited to the above-described embodiment. It is possible.
[0034]
【The invention's effect】
As described above, according to the glossy surface inspection apparatus and method of the present invention, automation can be performed, and the inspection level and speed can be significantly increased. It can be dramatically improved.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating a glossy surface inspection method according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram showing a glossy surface inspection apparatus for performing the glossy surface inspection method of FIG.
3A is a schematic diagram illustrating image data when there is no surface defect, and FIG. 3B is a schematic diagram illustrating image data when a surface defect exists.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Projection part 2 Projection screen 3 Camera 4 Image processing means 5 Judgment means 6 Table X Inspection object Y Laser light A Specularly reflected light part B Distorted part

Claims (5)

A light emitting unit that irradiates a laser beam from an oblique direction to a glossy surface,
A camera for capturing the reflected light of the laser light on the glossy surface,
Image processing means for acquiring the distortion of specularly reflected light from image data taken by the camera,
A glossy surface inspection apparatus comprising: a determination unit configured to detect a surface defect on a glossy surface based on distortion of specular light acquired by the image processing unit. The glossy surface inspection apparatus according to claim 1, wherein an inclination angle of the laser light with respect to a normal direction of the glossy surface is 45 ° or more and 85 ° or less. The glossy surface inspection apparatus according to claim 1, wherein the laser light emitted by the light projecting unit has a band-like light flux. 4. The glossy surface inspection apparatus according to claim 1, wherein a semiconductor laser is used for irradiating the laser beam in the light projecting section. An irradiation step of irradiating the glossy surface with laser light from an oblique direction,
A photographing process of photographing the reflected light of the laser light on the glossy surface,
An image processing step of obtaining the distortion of the specular reflection light from the image data of the reflection light,
A determining step of detecting a surface defect on a glossy surface based on the distortion of the specular reflection light.

Images