JP3661466B2 - Coating unevenness inspection apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating unevenness inspection apparatus and method suitable for inspection of coating unevenness among coating defects, in particular, coating unevenness (metallic coating unevenness) of metallic coating that occurs in a wide range of a painted surface.
[0002]
[Prior art]
The coating unevenness (metallic coating unevenness) generated at the time of metallic coating is caused by the disorder of the arrangement of the glitter material. The causes include the pattern disorder of the coating machine, excessive amount of thinner, insufficient film thickness, and poor polishing of the intermediate coating part. In the past, such an uneven coating defect has been evaluated sensuously almost visually.
[0003]
For example, in the case of automobile painting, the body after drying the topcoat is visually checked on the inspection line for the presence of uneven coating, and the body that is judged to have poor coating unevenness is extracted outside the line. Inspect at the inspection site. At the inspection site, the body is irradiated with a high luminous flux lamp, such as an artificial sun lamp, and further devised so that the unevenness can be clearly seen, and then visual evaluation is performed. At this time, the degree of coating unevenness is currently determined based on empirical values.
[0004]
Recently, devices that measure the brightness of metallic paint surfaces (laser-type metallic sensation measuring devices, etc.) have been developed, and this device scans the paint surface to measure the brightness continuously or by measuring multiple points. A method of quantitatively evaluating the coating unevenness using a figure or the like has been devised (see, for example, JP-A-5-288690). Similarly, a method has been devised in which lightness values are measured at multiple points using a color difference meter and evaluated to some extent based on the data.
[0005]
[Problems to be solved by the invention]
However, in visual measurement by an operator, coating unevenness is visible or not visible depending on how the light source is applied, but it is noticeable that defective products are likely to flow out. Moreover, since it is visual sensory evaluation and is not quantitatively evaluated, individual differences are likely to appear in the test results.
[0006]
In addition, when inspecting and evaluating with a measuring instrument, since it is basically point measurement, measurement with a wide field of view is difficult. Therefore, in the case of metallic coating unevenness that occurs over a wide range of the body surface, measurement accuracy becomes a problem. In addition, since a large amount of measurement data is required, there is also a problem that a lot of time (man-hours) is required until a measurement result is obtained.
[0007]
The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a coating unevenness inspection apparatus and method capable of performing quantitative evaluation of coating unevenness with a wide field of view on a line.
[0008]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following means.
[0009]
(1) A coating unevenness inspection apparatus according to the present invention is a coating unevenness inspection apparatus that optically measures and evaluates coating unevenness generated on a painted surface of an object to be inspected. A light source that emits light at an angle of, an imaging unit that is installed on the shade side of the light source, and that captures an image of a painted surface irradiated with light from the light source as image data within a predetermined field of view, and is captured by the imaging unit The analysis means for analyzing the image data and calculating a quantitative evaluation value for coating unevenness, and comparing the evaluation value calculated by the analyzing means with a preset reference value, Determining means for determining presence or absence.
[0010]
(2) wherein the light source emits light at an angle of 45 degrees with respect to painted surfaces, angle between the optical axis and the coated surface of the image pickup means is smaller than 45 degrees.
[0011]
(3) A luminance histogram analysis is performed on the image data captured by the imaging unit to calculate a distribution range of luminance values, and a line profile analysis is performed on the same image data to determine a difference in intensity values. Analyzing means for calculating, and determining means for comparing the distribution width and the strength difference calculated by the analyzing means with respective reference values set in advance to determine the presence or absence of occurrence of coating unevenness.
[0012]
(4) In the above-described line profile analysis, a line profile is calculated by calculating a luminance average value with a constant height along the horizontal direction based on image data of an image spread in the horizontal direction and the height direction. And the difference in intensity of the luminance value in the line profile is calculated.
[0013]
(5) Imaging means for capturing an image spread in the horizontal direction and the height direction on the painted surface irradiated with light from the light source as image data in a predetermined range of visual field, and the horizontal direction and height captured by the imaging means Based on the image data of the image spread in the horizontal direction, the luminance average value in the width of a certain height along the horizontal direction is calculated, the line profile is analyzed, and the intensity difference of the luminance value in the line profile is calculated. Analyzing means for calculating, and determining means for comparing the strength difference calculated by the analyzing means with a reference value set in advance to determine the presence or absence of occurrence of coating unevenness.
[0014]
(6) coating unevenness inspection method according to the present invention measures the uneven paint that occurs coated surface of the object optically, in the coating unevenness inspection method of assessing, by the light source with respect to the coated surface of the object irradiating the light at a predetermined angle, a step of capturing an image of the coated surface irradiated with light as image data in a field of view of the predetermined range, by the installed image pickup means to the shade side of the light source by the light source, the It analyzes the write Mareta image data taken by the imaging means, calculating a quantitative evaluation value related uneven paint, as compared to the calculated preset reference value evaluation value, the occurrence of uneven paint And a step of determining presence or absence.
[0015]
(7) The light source emits light at an angle of 45 degrees with respect to the painted surface, and the angle formed by the optical axis of the imaging means and the painted surface is smaller than 45 degrees.
[0016]
(8) up write Mareta performing a luminance histogram analysis on the image data, and calculates the distribution width of the luminance value by performing a line profile analysis for the same image data, and calculates the intensity difference between the luminance value And a step of comparing the calculated distribution width and strength difference with respective reference values set in advance to determine the presence or absence of occurrence of coating unevenness.
[0017]
(9) In the above-described line profile analysis, a line profile is calculated by calculating a luminance average value with a constant height along the horizontal direction based on image data of an image spread in the horizontal direction and the height direction. And the difference in intensity of the luminance value in the line profile is calculated.
[0018]
(10) a step of capturing an image light is spread in the horizontal direction and the height direction in the painted surface which has been irradiated as image data in a field of view of the predetermined range, taking write Mareta, the horizontal and vertical direction to spread the image Calculating a luminance average value at a constant height along the horizontal direction based on image data, analyzing a line profile, and calculating a luminance value strength difference in the line profile; Comparing the difference in strength with a reference value set in advance, and determining the presence or absence of occurrence of coating unevenness.
[0022]
【The invention's effect】
According to the present invention, the painted surface is irradiated with light to image the painted surface with a predetermined range of visual field, that is, the image of the painted surface that can be seen visually is directly taken as an image, and image analysis is performed to quantitatively determine the coating unevenness. Since the evaluation value is calculated, it is possible not only to perform quantitative evaluation of coating unevenness with a wide field of view with high accuracy in a short time, but also to enable objective evaluation that cannot be achieved by visual sensory evaluation. There will be no individual differences.
[0023]
At that time, an artificial solar lamp is used as the light source, and the angle of the light source is set to 45 ° with respect to the painted surface, thereby facilitating detection of coating unevenness. Further, by using a CCD area camera as the image pickup means, a wide field of view can be obtained, and by setting the position of the image pickup means on the shade side of the light source, almost all coating unevenness can be detected. Therefore, it is particularly effective for metallic coating unevenness that has occurred in a wide range and has been difficult to detect conventionally.
[0024]
In addition, when measuring the entire inspection object at the same time, by installing multiple sets of light sources and imaging means in parallel, it is possible to detect coating unevenness defects of the entire inspection object with a wide field of view covering the entire inspection object. The outflow of defective products due to oversight of inspection is prevented as much as possible.
[0025]
In addition, when there is an inspection object on the line, quantitative measurement / evaluation of the inspection object that passes on the line is possible, and inspection on the line is possible. Disappear. Also from this point, the inspection time (process) can be shortened.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 is a block diagram showing a schematic configuration of a coating unevenness inspection apparatus according to an embodiment of the present invention.
[0028]
This apparatus is suitable for inspecting metallic coating unevenness that occurs over a wide range of the surface of the body 1 of an automobile. As an outline, the CCD camera 2 is used to increase the field of view, and the artificial sun is applied to the painted surface. An image that can be seen by irradiating the light from the lamp 3 is directly taken in as an image, and is subjected to image processing by image analysis software to quantitatively evaluate the presence or absence of metallic coating unevenness.
[0029]
As a more specific device configuration, an artificial solar light 3 (light source) that irradiates a painted surface of an automobile body 1 (inspected object) and a CCD area camera (hereinafter simply referred to as “CCD camera”) that captures an image of the painted surface. ) 2 (imaging means), an image capturing device 4 that captures an analog image data signal from the CCD camera 2 and converts it into a digital image data signal, and an image processing device 5 equipped with image processing software for coating unevenness inspection The image processing apparatus 5 further analyzes the captured image data and calculates a quantitative evaluation value related to the metallic coating unevenness, and the calculated evaluation value. Compared with a reference value set in advance, a determination unit 7 (determination means) that determines whether or not metallic paint unevenness has occurred, and a memory 8 that stores the reference value You have me. In addition, a display device 9 is connected to the image processing device 5 in order to display the processing results of each part of the image processing device 5 to the operator.
[0030]
When simultaneously measuring the entire automobile body 1, a plurality of sets of at least a light source (artificial sunlight) 3 and a CCD camera 2 are prepared, and these are installed in parallel, so that a wide field of view that can cover the entire body 1 is covered. Secure. For example, in the example of FIG. 1, four sets of artificial sun lamps 3 and the CCD camera 2 in front of the conveyance direction A of the body 1 conveyed on the line, specifically, the right side portion in the conveyance direction A The artificial solar lamp 3a and the CCD camera 2a, the right horizontal artificial sun lamp 3b and the CCD camera 2b, the left horizontal artificial solar lamp 3c and the CCD camera 2c, and the left side artificial sun lamp 3d A CCD camera 2d is installed.
[0031]
In the above configuration, the artificial solar lamp 3 is used as the light source in order to easily detect the coating unevenness by irradiating the coating surface with a high luminous flux. The installation angle of the light source (artificial solar lamp) 3 with respect to the painted surface is preferably 45 ° between the optical axis of the light source 3 and the painted surface. In this case, the light from the light source 3 is incident at an angle of 45 ° with respect to the painted surface.
[0032]
The position of the CCD camera 2 is preferably installed on the shade (bottom) side of the light source 3. Thereby, almost all coating unevenness can be detected. In other words, the installation angle (image capture angle) of the CCD camera 2 with respect to the painted surface is such that the angle formed by the optical axis of the CCD camera 2 and the painted surface is greater than 45 ° of the incident angle of light from the light source (artificial sunlamp) 3. The smaller one is effective for most metallic coating unevenness and is preferable.
[0033]
FIG. 2 is a flowchart showing the operation of the coating unevenness inspection apparatus of FIG.
[0034]
First, the artificial solar lights 3a to 3d are turned on (ON) and irradiated with light at an incident angle of 45 ° to the painted surface (S1), and the image of the painted surface at that time corresponds from the shade side of each light source. Each of the CCD cameras 2a to 2d is photographed and captured as image data (S2).
[0035]
The image data picked up by the CCD camera 2 is input to the image processing device 5 via the image capturing device 4. First, the image analysis unit 6 performs luminance histogram analysis and / or line profile analysis using image analysis software. A quantitative evaluation value that quantitatively represents the coating unevenness is calculated (S3). The luminance histogram analysis is a technique for analyzing the histogram distribution of luminance values and obtaining the distribution width of the luminance values as the evaluation value (see FIG. 4). The line profile analysis is analyzing the line profile of the average luminance value. This is a method for obtaining a difference in brightness value as the evaluation value (see FIG. 5). The luminance histogram analysis and line profile analysis will be described in detail later.
[0036]
After the image analysis is performed and the quantitative measurement of the metallic coating unevenness is completed, the determination unit 7 then performs the quantitative evaluation of the coating unevenness by comparing the analysis result with the data of the normal part. Specifically, the calculation is performed in S3. The evaluated value is compared with a preset reference value stored in the memory 8 to determine the presence or absence (including the degree) of occurrence of metallic coating unevenness (S4). As for the evaluation level (reference value), a threshold value is determined in advance based on experience values accumulated in the past and stored in the memory 8.
[0037]
The determination result of S4 is displayed on the display device 9 (S5). At this time, for example, an intermediate S3 analysis result (a luminance histogram and its evaluation value, or a line profile and its evaluation value) may be displayed according to the operator's selection.
[0038]
Therefore, according to the present embodiment, it is possible to see the defective metallic coating unevenness of the entire body 1 passing through with a wide field of view, and the outflow of defective products due to oversight of inspection is prevented as much as possible.
[0039]
In addition, since the inspection can be performed on the line, the body 1 is not removed from the line.
[0040]
Furthermore, since the metallic coating unevenness can be quantitatively evaluated, the evaluation itself is objective, and there is no individual difference in the inspection result.
[0041]
【Example】
A specific example will be described below.
[0042]
FIG. 3 is a configuration diagram of a coating unevenness inspection apparatus according to an embodiment of the present invention. In the figure, members common to those in FIG.
[0043]
The object to be inspected is a painted silver door outer 10, the light source is an artificial sun lamp 3, and the CCD camera 2 is a color CCD camera (lens: COSMICAR TV ZOOM LENS 12.5 to 75 mm). A personal computer 20 is connected to the color CCD camera 2 via an image capturing device (V-Port) 4. The personal computer serves as both the image processing device 5 and the display device 9 of FIG. And about the mutual positional relationship of the door outer 10, the artificial solar light 3, and the color CCD camera 2, the artificial solar light 3 is an angle of 45 degrees with respect to the coating surface of the door outer 10, and the door outer 10 The color CCD camera 2 is fixed at a position 1700 mm from the intersection of the optical axis of the artificial solar lamp 3 and the door outer 10. The angle of the color CCD camera 2 with respect to the painted surface (CCD camera angle) is appropriately set each time within a range smaller than 45 °, which is the incident angle of the artificial sunlamp 3.
[0044]
FIG. 4 is a diagram showing an example of image processing results by luminance histogram analysis, in which a coating unevenness occurrence door (FIG. (A)) and an OK level door (FIG. (B)) are compared.
[0045]
Specifically, with the device of FIG. 3, the CCD camera angle is 25 °, the door where the metallic paint unevenness is generated, and the door of the OK level by visual evaluation are taken, and the brightness of a certain range of the captured image is obtained. When the histogram of values is plotted, it is as shown in FIG. 4 (A) and FIG. 4 (B). As is apparent from the comparison of these two drawings, the variation in the luminance value increases as the degree of coating unevenness increases, and the width of the luminance value distribution becomes wider. Therefore, the coating unevenness can be quantitatively expressed using this luminance value distribution width.
[0046]
FIG. 5 is a diagram showing an example of image processing results by line profile analysis, and compares the coating unevenness generation door (FIG. (A)) with the OK level door (FIG. (B)).
[0047]
Specifically, when the same image used for the luminance histogram analysis is calculated and plotted along the front-and-rear direction (pixel position or horizontal coordinate) of the door, the luminance average value at a certain height width is plotted. 5A and 5B, respectively. As is clear from the comparison of these two drawings, the brightness difference in the brightness value increases with increasing degree of the coating unevenness with vertical streaks such as locus unevenness. This kind of coating unevenness can be quantified by measuring the difference in value.
[0048]
As a result of the experiment, as described above, the image capture angle condition (CCD camera angle) of the CCD camera 2 is smaller than 45 ° of the incident angle of the artificial sun lamp 3, as shown in FIG. It is valid.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a coating unevenness inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the operation of the coating unevenness inspection apparatus of FIG.
FIG. 3 is a configuration diagram of a coating unevenness inspection apparatus according to an embodiment of the present invention.
FIG. 4 is a diagram illustrating an example of an image processing result by luminance histogram analysis.
FIG. 5 is a diagram illustrating an example of an image processing result by line profile analysis.
[Explanation of symbols]
1 ... Auto body (inspected object),
2. CCD area camera (imaging means),
3 ... Artificial solar light (light source),
4 ... Image capturing device,
5 ... Image processing device,
6 ... Image analysis unit (analysis means),
7: Determination unit (determination means),
8: Reference value memory,
9: Display device,
10 ... door outer,
20 ... PC.

Claims (10)

In the coating unevenness inspection device that optically measures and evaluates the coating unevenness that occurs on the painted surface of the inspection object,
A light source that irradiates light at a predetermined angle with respect to the painted surface of the inspection object;
An imaging unit that is installed on the shade side of the light source and captures an image of a painted surface irradiated with light from the light source as image data in a predetermined range of visual field;
Analyzing the image data captured by the imaging means, and calculating the quantitative evaluation value for the coating unevenness;
A determination unit that compares the evaluation value calculated by the analysis unit with a reference value set in advance, and determines the presence or absence of occurrence of coating unevenness;
A coating unevenness inspection apparatus characterized by comprising: Before Symbol light source illuminates the light at an angle of 45 degrees with respect to painted surfaces, painted according to claim 1 the angle between the optical axis and the coated surface of the imaging means, characterized in that less than 45 degrees Unevenness inspection device. In the coating unevenness inspection device that optically measures and evaluates the coating unevenness that occurs on the painted surface of the inspection object,
A light source that irradiates light at a predetermined angle with respect to the painted surface of the inspection object;
Imaging means for capturing an image of the painted surface irradiated with light from the light source as image data in a predetermined range of visual field;
A luminance histogram analysis is performed on the image data captured by the imaging unit to calculate a distribution range of luminance values, and a line profile analysis is performed on the same image data to calculate a difference in luminance values. Analysis means;
A coating unevenness inspection apparatus comprising: a determination unit that compares the distribution width and the strength difference calculated by the analysis unit with respective reference values set in advance to determine whether or not the coating unevenness has occurred. . In the line profile analysis, based on the image data of the image spread in the horizontal direction and the height direction, the line profile is analyzed by calculating a luminance average value at a constant height along the horizontal direction, 4. The coating unevenness inspection apparatus according to claim 3, wherein a difference in intensity between luminance values in the line profile is calculated. In the coating unevenness inspection device that optically measures and evaluates the coating unevenness that occurs on the painted surface of the inspection object,
A light source that irradiates light at a predetermined angle with respect to the painted surface of the inspection object;
An imaging means for capturing an image spread in the horizontal direction and the height direction on the painted surface irradiated with light from the light source as image data in a predetermined range of visual field;
Based on the image data of the image that is captured by the imaging means and spreads in the horizontal direction and the height direction, the line profile is analyzed by calculating a luminance average value at a constant height along the horizontal direction. Analysis means for calculating the intensity difference of the luminance value in the line profile ;
A coating unevenness inspection apparatus comprising: a determination unit that compares the strength difference calculated by the analysis unit with a reference value set in advance to determine whether or not the coating unevenness has occurred. In the coating unevenness inspection method that optically measures and evaluates the coating unevenness that occurs on the painted surface of the inspection object,
Irradiating light at a predetermined angle with a light source on the painted surface of the object to be inspected;
Capturing an image of a painted surface irradiated with light from the light source as image data with a predetermined range of field of view by an imaging means installed on the shade side of the light source ;
It analyzes the write Mareta image data taken by the imaging unit, calculating a quantitative evaluation value related uneven paint,
The calculated evaluation value as compared with a preset reference value, and determining the presence or absence of the occurrence of coating unevenness,
A coating unevenness inspection method characterized by comprising: 7. The uneven coating according to claim 6 , wherein the light source emits light at an angle of 45 degrees with respect to the painted surface, and an angle formed by the optical axis of the imaging means and the painted surface is smaller than 45 degrees. Inspection method. In the coating unevenness inspection method that optically measures and evaluates the coating unevenness that occurs on the painted surface of the inspection object,
Irradiating light at a predetermined angle with respect to the painted surface of the object to be inspected;
A process of capturing an image of a painted surface irradiated with light as image data in a predetermined range of field of view;
Performing a luminance histogram analysis on write Mareta image data taken, calculates the distribution width of the luminance value by performing a line profile analysis for the same image data, a step of calculating the intensity difference of the luminance values,
And a step of comparing the calculated distribution width and strength difference with respective reference values set in advance to determine the presence or absence of occurrence of coating unevenness. In the line profile analysis, based on the image data of the image spread in the horizontal direction and the height direction, the line profile is analyzed by calculating a luminance average value at a constant height along the horizontal direction, The method for inspecting unevenness in coating according to claim 8, wherein a difference in intensity between luminance values in the line profile is calculated. In the coating unevenness inspection method that optically measures and evaluates the coating unevenness that occurs on the painted surface of the inspection object,
Irradiating light at a predetermined angle with respect to the painted surface of the inspection object;
A step of taking an image spread in the horizontal direction and the height direction on the painted surface irradiated with light as image data in a predetermined range of visual field;
Take write Mareta, based on the image data in the horizontal direction and the height direction to spread the image, analyzing the calculated and line profile luminance average value of the width of the horizontal direction along with certain height, line Calculating the intensity difference of the brightness value in the profile ;
And a step of comparing the calculated strength difference with a reference value set in advance to determine the presence or absence of occurrence of uneven coating.

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