JPH05256775A - Device for inspecting properties of coating surface - Google Patents

Abstract

PURPOSE:To obtain the device, of good measurement reliability sand capable of rapidly measuring. CONSTITUTION:An image to be inspected from a coating surface is received a CCD camera 6. In an image processor 30, a measuring region and position are automatically set on the basis of the inputted image. Contours of the image are extracted from the inputted image, and the evenness of the coating surface is found from waveforms forming the contours. The feeling of build of the coating surface is found from the number of islets included in the image obtained by the binarization process of the inputted image. The feeling of brilliance of the coated surface is found on the basis of the lightness difference between a light part and a dark part in the inputted image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint surface property inspection device for easily measuring the condition of a paint surface of an automobile, for example.

[0002]

2. Description of the Related Art Conventionally, in the production process of automobiles, the condition of the coated surface is strictly inspected. For example, as an example of the inspection of the painted surface, an inspection of image clarity can be mentioned. This image clarity inspection is a test for examining how flat the coated surface is, and conventionally, it is performed by one of the following two methods.

First, one method that has been conventionally used is a method of viewing a fluorescent lamp or the like by looking through the coating surface from an oblique direction with respect to the coating surface. According to this method, the properties of the coated surface such as the flatness of the coated surface can be easily inspected by disposing a fluorescent lamp or the like at an appropriate place. Another method is to project a stripe as an image to be inspected onto a painted surface, input the reflected image from the painted surface of this stripe with a camera, etc., and then perform image processing on this input image to inspect the painted surface property. It is a method to do. According to this method, it is possible to eliminate inspection variations due to individual differences, so that the inspection reliability is good.

The following is a specific example of the method for inspecting the properties of the coated surface by processing the image from this camera. Prior to this explanation, the types of coated surface properties will be described. There are three types of coated surface properties. One of them is smoothness.
This shows how much the relatively large undulating distortion on the coated surface is. The other is the feeling of flesh. This shows how much very fine unevenness exists on the coated surface.
The last one is gloss. This shows how large the difference between light and dark on the painted surface is reproduced.

Conventionally, in order to calculate the degree of smoothness, that is, the degree of smoothness, as shown in FIG. 10, a stripe reflection image from a painted surface captured by a camera is thinned and shown in the middle part of the figure. Such a line image is generated, the variation in each direction of the line forming the line image is obtained for each pixel as shown in the lower part of the figure, and the smoothness is quantified by the degree of variation in this direction. Kaihei 1-2210
No. 6). Then, in order to calculate the feeling of flesh, FIG.
As shown in, the two-dimensional FFT processing is applied to the stripe reflection image from the painted surface captured by the camera, and the distribution for each frequency is shown in the middle of the figure based on the data obtained as a result. This graph is used to judge whether the feeling of flesh is good or bad based on this graph.

[0006]

However, in such a conventional inspection method, the first inspection method requires a great deal of skill because it depends on the sense of the inspector, and the second method requires the skill. Since it is necessary to perform two-dimensional processing, there is a drawback that the inspection takes too long because of a large amount of information to be processed, and a drawback that the measurement reliability of smoothness is not sufficient. Further, there is a drawback that the device is large and expensive because it requires a huge memory capacity.

Among these, there is the problem of the measurement reliability of the smoothness. This is the case where, for example, when an image as shown in FIG. When the processing is performed, since the shape of the input image is almost symmetrical to the left and right, the straight line is as if it had the best smoothness. This example is a very extreme example, but one thing that can be said is that the contour lines are erroneously recognized as flat at the positions of interest on the left and right sides.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a painted surface property inspection apparatus which has good measurement reliability and can perform rapid measurement. ..

[0009]

In order to achieve the above object, the present invention projects an image to be inspected on a coated surface and inspects the property of the coated surface based on the image to be inspected reflected by the coated surface. In the painted surface property inspection device, input means for inputting the image to be inspected from the painted surface, contour line extraction means for extracting the contour line of the image from the image input to the input means, and the contour line extraction Smoothness calculating means for calculating the smoothness of the painted surface based on the degree of variation in the directionality of each contour line extracted by the means.

In addition, in a coated surface property inspection apparatus for projecting an image to be inspected on a coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, the coated surface from the coated surface is inspected. Input means for inputting the inspection image, and binarizing means for binarizing the image input to the input means,
Hollow part calculating means for calculating the number of hollow parts having a size equal to or smaller than a predetermined value existing in the image to be inspected binarized by the binarizing part, and the hollow part calculated by the hollow part calculating means. And a weight feeling calculating means for calculating the weight feeling of the painted surface according to the number.

Then, in a coated surface property inspection apparatus for projecting an image to be inspected on the coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, the coated surface from the coated surface is inspected. It has an input means for inputting an inspection image, and a glossiness calculating means for calculating the glossiness of the painted surface based on the brightness difference between the brightest part and the darkest part of the image input to the input means. And

Further, in a coated surface property inspection apparatus for projecting an image to be inspected onto a coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, the coated surface from the coated surface is inspected. Input means for inputting an inspection image, light center of gravity calculating means for calculating the light center of gravity of the image to be inspected input to the input means, and skewness calculation for calculating a distortion degree of the image to be inspected input to the input means Means and a measurement region and a position for inspecting the property based on the optical centroid of the inspected image obtained by the optical centroid calculating means and the skewness of the inspected image obtained by the skewness calculating means. And a measuring area setting means for setting.

[0013]

The present invention thus constructed operates as follows. The input means inputs the image to be inspected reflected from the painted surface, and the contour line of the inputted image is extracted by the contour line extracting means. Then, the smoothness calculating means calculates the variation in the line direction of the extracted contour line for each pixel, and evaluates the smoothness of the painted surface based on the variation. Also,
The image to be inspected input to this input means is binarized by the binarizing means, and the hollow portion calculating means presents a hollow portion having a size equal to or smaller than a predetermined value existing in the binarized inspected image. Is calculated. Then, the meat feeling calculation means is
The texture of the coated surface is calculated according to the number of hollow portions.

Further, the glossiness calculating means calculates the glossiness of the coated surface by obtaining the difference in brightness between the brightest part and the darkest part of the image to be inspected input by the input means.

Then, from the image to be inspected input by the input means, the optical center of gravity of the image is calculated by the optical center of gravity calculating means. The skewness calculation means calculates the skewness of the input inspection image. The measurement area setting includes a measurement area and a position for inspecting the property based on the optical centroid of the inspected image obtained by the optical centroid calculating means and the distortion degree of the inspected image obtained by the skewness calculating means. Set.

Since the above-mentioned operations are performed uniformly by the apparatus in a predetermined order, the reliability of the inspection can be uniformly good regardless of individual differences. Further, the image processing for performing the evaluation may be performed one-dimensionally instead of two-dimensionally based on the input image and its contour line, so that the processing speed is remarkably high.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B are structural views of a measuring head that constitutes a painted surface property inspection apparatus according to the present invention. FIG. 1A is a front view mainly showing the internal structure, and FIG. 1B is a bottom view thereof.

The measuring head 25 constituting the painted surface property measuring apparatus is a small and lightweight handy type measuring head, and is provided with a casing 11 having an opening 12 serving as a light entrance / exit. In the casing 11, the light source 2, the semi-diffusing plate 3, the stripe grating 4, the mirror 10 and the convex lens 5 are provided on the light projecting side, and the light receiving lens 7, the diaphragm 8 and the CCD element constituting the CCD camera 6 are provided on the light receiving side. 9 are sequentially arranged and housed with respect to the optical axis. The light source 2 is composed of a halogen bulb 2a and a reflecting mirror 2b, and the stripe grating 4 is made of, for example, a glass plate on which a stripe pattern is printed. In this way, the stripe pattern is radiated from the light projecting side onto the coated surface 1, and the reflected light is reflected by the CC on the light receiving side.
An image is taken by the D camera 6. The reflective stripe pattern imaged by the CCD camera 6 is displayed on the screen of the built-in monitor 13 and is also output via the external connector 14 to the image processing device 30 which digitizes and records the image clarity. .. On the other hand, the opening 12 of the casing 11 is sealed with a transparent glass 15 which is a transparent plate, and four free legs 16 each of which is extendable and retractable and whose tip is rotatable are attached to the bottom surface of the casing 11.

Measuring head 2 having a structure as outlined above
Details of each component of No. 5 will be described below in order. First, the optical system of the measuring head 25 will be described. The diaphragm 8 is a pinhole diaphragm having a diameter of about 0.2 to 0.3 mm, which is narrowed down to the diffraction limit.
And the CCD element 9 are arranged. This very small diaphragm 8 blocks out all the undesired light flux that causes blurring of the image, so that it becomes possible to clearly capture the image as an image both before and after the focused object surface. The depth increases dramatically. Then, due to the dramatic increase in the depth of field by the diaphragm 8, the focus is brought into focus regardless of the position of the subject, and the stripe grating 4 is formed without moving the light-receiving lens 7 or changing the focal length thereof. It becomes possible to focus on both of the painted surfaces 1. As a result, it becomes possible to accurately measure the three textures (smoothness, suppleness, and glossiness) of sharpness corresponding to the magnitude of the waviness of the coated surface 1 as described later. In addition, since the depth of field is remarkably increased by the diaphragm 8, the sensitivity can be further improved and the sensitivity can be adjusted.
Non-contact measurement can be performed by separating 5 from the coated surface 1.
If the diameter of the pinhole 8 is made smaller than the diffraction limit, the resolution is lowered due to the diffraction phenomenon, which is not preferable.

Next, the optical system on the light projecting side will be described. The convex lens 5 included in this optical system is for arranging the stripe grating 4 in a pseudo manner as far as possible in order to increase the sensitivity. It is possible to make the device 25 smaller while increasing the sensitivity. Further, as described above, the aperture 8
Since the depth of field is extremely large and the image is in focus anywhere, the stripe grating 4 can be placed at any appropriate position in relation to the convex lens 5, and if the position of the stripe grating 4 is adjusted appropriately, it will be human. It is possible to virtually separate the striped grid 4 from the painted surface 1 at an infinite distance or more, though it is not blurred. This further improves the sensitivity. Further, in the present embodiment, the mirror 10 is provided to make the optical path obscure, thereby further downsizing the device.

The light source 2 includes a halogen bulb 2a and a reflecting mirror 2
The light source is arranged a little further than the focal point of b, and forms a condensing type light source in which light is once condensed and then spread. This is because the coated surface 1 is usually a curved surface, so that in the conventional spot-type light source that emits parallel rays, the edge of the illuminated surface tends to be darker than the central portion, so the amount of light at the edge of the illuminated surface is increased. This is to ensure more stable brightness on curved surfaces. The light distribution angle of this condensing light source 2 is, for example, 40 ° or more,
It is larger than the spot type (light distribution angle 0 to 10 °).

The semi-diffusing plate 3 for eliminating uneven light is
Unlike the diffusion plate used conventionally, it diffuses and transmits incident light within a small scattering angle range, and for example, frosted glass or focus glass is used. This semi-diffusing plate 3 is a light source 2
It is arranged before the condensing point C of the light from. Comparing the optical transmittances of the diffuser and the semi-diffuser on the optical axis, the diffuser has about 4
5% and about 85% for the semi-diffusing plate (both are actually measured values). Thus, unlike the diffuser plate, the semi-diffuser plate has a function of advancing light to some extent, so that the reduction in the amount of light irradiated to the stripe grating 4 in the optical axis direction can be relatively small. Therefore, by using the semi-diffusing plate 3, it is possible to secure the brightness required for measurement with the light source 2 having a smaller capacity than the conventional one. Further, as shown in the drawing, three semi-diffusing plates 3 are used to sufficiently eliminate the unevenness. By using an appropriate number of the semi-diffusing plates 3 in this manner, it is possible to irradiate the stripe grating 4 with light having a uniform amount while securing a light amount.

Next, the structure of the measuring head 25 will be described. First, the transparent glass 15 is attached to the opening 12 of the casing 11 as a light entrance / exit, and the measuring head 25 itself has a closed structure. This prevents dust and the like from entering the inside of the measuring head 25 to contaminate the optical system and reduce the performance of the device. At this time, since the measuring head 25 is supported by the free foot 16 at a position apart from the painted surface 1, the reflected light from the glass surface does not enter the CCD camera 6 as shown in FIG. Therefore, the measurement can be performed even if the opening 12 is closed with the transparent glass 15. In addition, in the case of a device of a type that directly contacts the coated surface 1 for measurement, although not shown, if the glass is arranged in an inverted V shape so that the glass surface is perpendicular to the optical axis and sealed,
Since there is no reflection on the glass surface that is undesirable for image formation,
It can be measured even if it is sealed with glass.

Further, four free legs 16 are attached to the bottom surface of the measuring head 25. An example of this free foot 16 is shown in FIG. The free foot 16 has a swivel tip of a ball joint 17 which is freely rotatable, and the legs have a retractable structure in which a spring 18 is incorporated. A felt 19 is attached to the tip portion 17 so that the painted surface 1 is not damaged during measurement. Further, the spring 18 does not contract only by placing the measuring head 25 on the painted surface 1, and when a force larger than the weight of the head 25 is applied,
That is, it has a spring constant that contracts when pushed. In this way, the free foot 16 is a swivel type in which the tip of the foot can be swiveled, and the leg can be expanded and contracted when pushed. By appropriately adjusting the height, the reflected light from the coated surface 1 can always be captured by the CCD camera 6. Although the head 25 can be separated from the painted surface 1 by providing the foot 16 in this way, the aperture 8 in the CCD camera 6 is very small as the diffraction limit, as described above, so that the aperture 12 can be removed from the opening 12. The ambient light of (1) is almost blocked by the diaphragm 8 and is not affected by the ambient light, so that the measurement head 25 can be measured away from the painted surface 1.

Further, in this embodiment, a timer circuit is incorporated in the operation switch mounting board 20, so that the light source 2 and the CCD are automatically operated if the operation switch is not operated for a certain period of time.
When the power supply to the internal devices such as the camera 6 and the monitor 13 is cut off and the operation switch is operated, the power is immediately turned on. The image input by the CCD camera 6 of the measuring head 25 configured as described above is processed by the above-described image processing device 30 as follows. Hereinafter, the processing here will be described based on the flowchart shown in FIG. 2 with reference to the drawings after FIG.

In the coated surface property inspection apparatus of the present invention,
A process of setting the size and position of the image to be input is performed as a pre-process for inputting the measurement image so that an optimum image can be obtained when measuring the properties of the coated surface. The reason why such processing is performed is to input an image that is not affected by this curvature in view of the fact that the input image obtained differs depending on the curvature of the painted surface. This process is performed in the following steps S1 to S5.

First, the multi-valued image input from the CCD camera 6 is input to the image processing device 30 and then the device 30.
It is stored in the memory provided therein. An example of the stored image is as shown in FIG. That is, an image corresponding to the reflected light of the stripe reflected on the painted surface is input. This image will be input to the CCD camera 6 as a similar image of the output stripe image when the painted surface is flat, but when the painted surface is curved. The image is enlarged, reduced, or deformed according to its curvature. Further, when the curvature of the painted surface is large, the position of the image may move within the field of view of the CCD camera 6. If the position of the image is out of the field of view due to this movement, the collection of data required for the measurement is insufficient, which adversely affects the reliability of the measurement result. Therefore, as described below, a process of tracking the position of the stripe image and changing the size of the measurement window is performed.

First, the image stored in the memory is called to calculate the ellipticity of the camera visual field A as shown in FIG. At the same time, the optical center of gravity of the stripe image existing in the camera visual field A is calculated. Ellipticity calculation is
The contour line of the measurement window is extracted and the measurement is performed based on the maximum value and the minimum value of the diameter. Further, since the calculation of the optical center of gravity is a general method that has been conventionally performed, the description of the processing will be omitted here (S1, S2). Next, the center position of the stripe image is obtained based on the result of this light center of gravity calculation. This calculation is performed to determine the center position of the next measurement window in the process of determining the size of the next measurement window (S3). Then, the size and position of the measurement window are determined based on the ellipticity obtained in the above process and the center position of the stripe image. For example, as a result of the above measurement, when the camera view A is substantially circular as shown in FIG. 3A, the measurement window B is set as shown in FIG. If it is an ellipse, the measurement window B is set as shown in the figure (S4).

When the above processing is completed, the coated surface property inspection processing is performed.

First, the stripe image stored in the memory is called and binarized with a predetermined threshold value. For example, an example of the stripe image is an image as shown in FIG. 5 (A) (S5). In order to obtain the smoothness, a process of extracting a contour line from this binarized image is performed, and an image as shown in FIG. 5B is obtained (S6). Since it is a very jagged line as it is, the smoothing process is performed to obtain an image as shown in FIG. 5C (S7). Next, the direction of the normal line is obtained for each of the constituent pixels of the smoothed contour line. That is, the calculation processing of the direction as shown in FIG. More specifically, as shown in FIG. 6, the direction of the normal line is obtained for each pixel forming the contour line. This direction is very many as shown in the figure (S8). Then, statistically processing a large number of directions obtained in this way, as shown in FIG. 6, the one with little variation in direction, that is, the one with convergence has good smoothness, while A large object, that is, an object having divergence is judged to have poor smoothness (S9, S10).

On the other hand, in order to calculate the feeling of flesh, a process of extracting the width of the contour line from the binarized image is performed. If it is normal, only the stripes with the same width as the stripe reflecting the painted surface should be detected, but if the feeling of flesh is poor, small islands will be mixed in the stripe, so The width corresponding to the small island is detected. Therefore, it can be said that the extraction of the width is a process at the previous stage for recognizing how many small islands of which size exist (S11). FIG. 7 is a comparison of images with good and poor flesh feeling.
Next, from the data of the stripe width extracted in the above processing, those having a predetermined value or less, for example, 0.5 mm or less are taken out and the existence ratio of the number is obtained. Based on this ratio, the feeling of flesh is calculated (S12 to S14).

To measure the glossiness, first, the difference in brightness between the brightest portion and the darkest portion is obtained for each horizontal line of the image input through the measurement window. That is, for the image as shown in FIG. 8, a graph of the relationship between the position and the brightness is created, and the difference between the maximum brightness and the minimum brightness in the graph is obtained (S15). .. This process is performed for all horizontal lines to obtain the average of the data within the measurement window area (S16). Glossiness is obtained according to the brightness difference obtained by the above processing. Since the correlation between the brightness difference and the glossy feeling is clear as shown in FIG. 9, the calculation operation is very simple (S17).

As described above, according to the coated surface property inspection apparatus of the present invention, smoothness and fleshness of the coated surface can be obtained by subjecting the extracted contour line to one-dimensional image processing to obtain a glossy feeling. Are calculated by detecting the brightness difference of the input image. Since the quantitative measurement can be easily performed as described above, the reliability of the measurement is improved. In other words, even if an amateur makes a measurement with this apparatus, a highly reliable evaluation can be performed. Furthermore, since the image processing for obtaining this evaluation is performed based on the contour line, only one-dimensional processing is required, and the processing speed can be increased. Further, since the memory capacity is remarkably small, the device can be downsized and the cost can be reduced.

[0034]

As described above, according to the present invention, it is possible to perform a quantitative measurement regardless of who measures it, so that it is possible to perform a highly reliable measurement. In addition, since the calculation for performing this measurement is one-dimensional, the measurement speed is improved. further,
Since the three textures of the painted surface are processed by different processes, the separation of the three textures can be made clear. Since the position and size of the measurement window are changed according to the curvature of the painted surface, the measurement reliability can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a measuring head portion of a coated surface property inspection device according to the present invention.

FIG. 2 is a processing flowchart of the apparatus shown in FIG.

FIG. 3 is a diagram for explaining the operation of determining the size and position of a measurement window in the flowchart shown in FIG.

FIG. 4 is a diagram for explaining the operation of determining the size and position of the measurement window in the flowchart shown in FIG.

5 is a diagram for explaining the operation of the process of calculating the evaluation of smoothness in the flowchart shown in FIG.

FIG. 6 is a diagram for explaining the operation of the process of calculating the evaluation of smoothness in the flowchart shown in FIG.

FIG. 7 is a diagram for explaining the operation of the process for calculating the evaluation of the feeling of flesh in the flowchart shown in FIG.

FIG. 8 is a diagram for explaining the operation of the process of calculating the glossiness evaluation in the flowchart shown in FIG.

FIG. 9 is a graph showing the relationship between the difference in brightness and the glossy feeling.

FIG. 10 is a diagram for explaining the operation of smoothness evaluation calculation processing in a conventional apparatus.

FIG. 11 is a diagram for explaining the operation of the evaluation calculation process of the feeling of flesh in the conventional device.

FIG. 12 is a diagram for explaining a defect when a smoothness is calculated by a conventional device.

[Explanation of symbols]

6 ... CCD camera (input means) 25 ... measurement head 30 ... image processing device (contour line extraction means, smoothness calculation means, hollow portion calculation means, binarization means, body feeling calculation means,
(Glossiness calculation means, light center of gravity calculation means, skewness calculation means, measurement position setting means)

Claims (4)

[Claims] 1. A coated surface property inspection apparatus for projecting an image to be inspected on a coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, comprising: Input means for inputting an inspection image, contour line extracting means for extracting a contour line of the image from the image input by the input means, and a degree of variation in directionality of each part of the contour line extracted by the contour line extracting means. And a smoothness calculating means for calculating the smoothness of the painted surface based on the above. 2. A coated surface property inspection apparatus for projecting an image to be inspected on a coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, comprising: Input means for inputting an inspection image, binarization means for binarizing the image input to the input means, and a predetermined value or less existing in the inspection image binarized by the binarization means Hollow portion calculating means for calculating the number of hollow portions having a size of, and a body thickness calculating means for calculating the thickness feeling of the painted surface according to the number of hollow portions calculated by the hollow portion calculating means. An apparatus for inspecting a painted surface, comprising: 3. A coated surface property inspection apparatus for projecting an image to be inspected on a coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, comprising: It has an input means for inputting an inspection image, and a glossiness calculating means for calculating the glossiness of the painted surface based on the brightness difference between the brightest part and the darkest part of the image input to the input means. A painted surface property inspection device. 4. A coated surface property inspection apparatus for projecting an image to be inspected onto a coated surface and inspecting the property of the coated surface based on the image to be inspected reflected by the coated surface, comprising: Input means for inputting an inspection image, light center of gravity calculating means for calculating the light center of gravity of the image to be inspected input to the input means, and skewness calculation for calculating the degree of distortion of the image to be inspected input to the input means Means, a measurement region and a position for inspecting the property based on the optical centroid of the inspected image obtained by the optical centroid calculating means and the skewness of the inspected image obtained by the skewness calculating means. A coated surface property inspection device, comprising: a measurement region setting means for setting.