JP2005106764A - Coating unevenness inspection device and coating unevenness inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately judge coating unevenness of metallic coatings of various sizes. <P>SOLUTION: An image in which a surface to be coated is image-picked up is divided into a plurality of small regions to obtain an average light receiving amount of each region. Then, a dispersion value of an average light receiving amount in the image and a differential value between the maximum and minimum of the average light receiving amount in a large region obtained by collecting a plurality of the small regions are found. Based on these values, coating unevenness is determined. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coating unevenness inspection apparatus and a coating unevenness inspection method that can accurately determine the coating unevenness of a surface to be inspected.

Conventionally, the inspection of the coating unevenness of the metallic coating adopted as the body coating of the automobile is mainly performed by visual inspection by a skilled inspector. However, recently, a coating unevenness inspection method as shown in Patent Document 1 that automates the inspection of metallic coating has been proposed. In this method, the two-dimensional image data of the paint film surface obtained by imaging is divided into a plurality of unit regions, the difference in density between unit regions adjacent in the vertical or horizontal direction is sequentially calculated, and each difference is determined as a predetermined value. The coating unevenness is determined by comparing with a threshold value.
Japanese Patent Application Laid-Open No. 2003-065964

  However, the coating unevenness of the metallic paint includes spot-like small and medium-sized spots (patterns) unevenness due to changes in the coating conditions and large-size locus unevenness due to spraying unevenness of the paint gun. It is difficult to determine all of these coating unevenness with an inspection apparatus even with the latest technology described in Patent Document 1 because the size of the coating unevenness varies.

  An object of the present invention is to provide a coating unevenness inspection apparatus and a coating unevenness inspection method that can determine the unevenness of coating of metallic paints of various sizes with the same or higher accuracy than the inspection by a conventional inspector.

  The present invention divides an image obtained by imaging a surface to be coated into a plurality of small areas to obtain an average amount of received light in each area in order to be able to reliably recognize coating unevenness of various sizes. Of the average received light amount, and the maximum and minimum difference values of the average received light amount in a large region obtained by collecting a plurality of small regions.

  In this way, by obtaining the dispersion value of the average received light amount and the maximum and minimum difference values of the average received light amount for regions of different sizes, spot-like small and medium-sized spots (patterns) unevenness and large-size locus unevenness are obtained. Can be reliably determined.

  According to the coating unevenness inspection apparatus and the coating unevenness inspection method of the present invention, since the dispersion value of the average received light amount of the divided areas and the maximum and minimum difference values of the average received light amount are obtained, the spot shape in the metallic coating This makes it possible to accurately and automatically determine small and medium size unevenness (patterns) unevenness and large size locus unevenness.

  Hereinafter, embodiments of the present invention will be described in detail by dividing the first to third embodiments.

(Embodiment 1)
FIG. 1 is a block diagram illustrating a schematic configuration of the coating unevenness inspection apparatus according to the first embodiment, and FIG. 2 is a diagram illustrating a positional relationship between illumination on a surface to be inspected and a camera. FIG. 1 shows a configuration corresponding to the first, fourth, and fifth aspects of the invention.

  A coating unevenness inspection apparatus according to the present invention is included in a camera (imaging unit) 10 that captures an image of a metallic coating surface (surface to be inspected) illuminated by illumination (light irradiation unit), and reflected light from the metallic coating surface. An inclined illumination filter (filter) 20 that removes an inclination component, and a subdivided area received light amount measurement unit (area dividing means, average) that divides a captured image into a plurality of small areas and calculates an average received light amount of each divided area Received light amount calculating means) 30, dispersion value calculating section (dispersion value calculating means) 40 for calculating the dispersion value from the average received light amount of each area in the captured image, presence or absence of coating unevenness on the metallic paint surface based on the dispersion value A coating unevenness determination unit (painting unevenness determination means) 50 is provided.

  The positional relationship between the illumination and the camera with respect to the surface to be inspected is as shown in FIG. That is, the illumination 60 is arranged such that its optical axis 65 forms an angle of θ1 with the main normal 110 of the painted surface 100, and the camera 10 has an optical axis 15 of θ2 (θ2> θ1) with respect to the main normal 110. It is arranged to form. That is, the positional relationship between the illumination 60 and the camera 10 is such that diffuse reflected light from the metallic paint surface 100 is likely to enter the camera 10.

  As the illumination 60, for example, high-intensity illumination such as a halogen lamp is used so that uneven coating of the metallic coating surface 100 is easily exposed. The camera 10 uses a CCD camera so that the coating unevenness can be distinguished with high accuracy. Since the illumination 60 and the camera 10 are in a positional relationship as shown in FIG. 2, direct reflected light from the illumination 60 is not incident on the camera 10, but diffusely reflected light from the metallic coating surface 100 is incident. .

  Here, the optical axis 65 of the illumination 60 and the optical axis 15 of the camera 10 refer to straight lines that pass through the centers of these surfaces in the optical system constituting them. The main normal line 110 of the metallic painted surface 100 is a straight line that passes through one point on the plane curve / curved surface and is perpendicular to the tangent line / tangent plane at that point, of which a contact plane (point P and a curve close to this point). The plane passing through the upper two points is within the plane defined as the limit where the two points approached P infinitely.

  Next, the operation of the coating unevenness inspection apparatus according to the present invention will be described in detail with reference to the flowchart of FIG. FIG. 3 is a flowchart corresponding to the procedures of claims 6 and 9.

  First, the illumination 60 irradiates the metallic coating surface 100 with irradiation light (S1). Next, the camera 10 receives diffuse reflection light from the metallic paint surface 100 and captures an image of the metallic paint surface 100 (S2). The tilted light component included in the captured image is removed by the tilted illumination filter 20. The inclined illumination filter 20 removes the inclined light component of the illumination from the diffuse reflected light. The determination accuracy is improved by removing an excessive gradient light component that adversely affects the accuracy of the coating unevenness determination (S3).

  The small division area received light amount measurement unit 30 divides the image of the metallic paint surface 100 captured by the camera 10 into a plurality of small regions. For example, if the captured image of the metallic paint surface 100 is an area (square) as shown in FIG. 4, this area is divided into a total of 225 subdivided areas a, b, c,. Divide equally. This divided area has a size of about 10 mm × 10 mm on the metallic painted surface 100 (S4).

  Next, the small divided area received light amount measurement unit 30 calculates the average luminance in each small divided area. Diffuse reflected light from the metallic coating surface 100 is incident on the CCD element provided in the camera 10. Each element constituting the CCD element accumulates a charge corresponding to the brightness of the diffuse reflected light. Since the CCD element has the number of elements of 1 million units, the image of the metallic coating surface 100 can be regarded as a set of pixels of 1 million units. The small divided area received light amount measuring unit 30 obtains an average of the charge amount (equivalent to the received light amount or luminance) of each region obtained by dividing the CCD element by 225, and uses this average as the luminance average of the small divided regions. Thereby, the average brightness in all the small divided areas such as the average luminance of the small divided area a and the average luminance of the small divided area b in the image of the imaged metallic paint surface 100 is obtained (S5).

The variance value calculation unit 40 calculates the variance value of the luminance average in the area of the captured image based on the luminance average of 225 in all the small divided areas. Here, the variance value is an average value of the squares of deviations of the materials x1, x2, ..., xn, that is,
{(X1−x _AVE ) ² + (x2−x _AVE ) ² +... + (Xn−x _AVE ) ² } / n
Here, x _AVE = (x1 + x2 +... + Xn) / n (S6).

  Finally, the coating unevenness determination unit 50 determines the coating unevenness of the metallic coating based on the dispersion value. FIG. 5 is a diagram showing a correlation between the variance value (SD) calculated according to the present embodiment and the sensory evaluation point of the visual inspection performed by a skilled worker that has been conventionally performed. If the SD value is large, the coating unevenness determination unit 50 determines that there is coating unevenness, and if the sensory evaluation score is high, the operator determines that there is coating unevenness. As shown in this figure, the magnitude of the SD value and the magnitude of the sensory evaluation value are almost linear, so there is a close correlation between the two values. Therefore, it can be said that the evaluation of the coating unevenness in the present embodiment is close to or higher than the sensory evaluation (S7).

  As shown in FIG. 11, the unevenness of the metallic coating includes uneven spots of small and medium-sized spots (patterns) due to fluctuations in the coating conditions shown in FIG. Although there is a large-size locus unevenness due to the spraying unevenness of the paint gun, when the unevenness of paint is obtained from the average brightness dispersion value of the small divided areas as in this embodiment, the small-size unevenness of the spot is accurately determined. can do.

(Embodiment 2)
FIG. 6 is a block diagram showing a schematic configuration of the coating unevenness inspection apparatus in the second embodiment, and this block diagram shows a configuration corresponding to the invention described in claims 2, 4, and 5. The first embodiment is different from the second embodiment in that the block diagram of the second embodiment includes a medium division area received light amount measurement unit 70 and a luminance maximum / minimum value difference calculation unit 80. In the present embodiment, the small divided area received light amount measuring unit 30 functions as a first area dividing unit. In the second embodiment, since the same blocks as those in the first embodiment have the same functions, the description thereof is omitted.

  The medium division area received light amount measurement unit 70 functions as a second area division unit, and the image captured by the camera 10 is divided into a plurality of medium areas (the small division areas of the first embodiment (constituting the first area)). Are divided into a plurality of middle divided areas and constitute the second area), and the average received light amount of each divided area is calculated.

  The luminance maximum / minimum value difference calculation unit 80 functions as a difference value calculation unit, and calculates the difference between the maximum and minimum of the average received light amount (luminance average) of all the middle divided areas.

  Next, the operation of the coating unevenness inspection apparatus according to the present invention will be described in detail with reference to the flowchart of FIG. FIG. 7 is a flowchart corresponding to the procedures of claims 7 and 9. Of the steps in this flowchart, the processing in steps S11 to S15 is exactly the same as the processing in steps S1 to S5 in the first embodiment, and a description thereof will be omitted.

  The medium division area received light amount measurement unit 70 divides the image of the metallic paint surface 100 captured by the camera 10 into a plurality of medium regions. For example, if the captured image of the metallic paint surface 100 is a region (square) as shown in FIG. 4, this region is divided into a total of 16 middle divided regions A, B, C,. To divide. This divided area has a size of about 40 mm × 40 mm on the metallic paint surface 100 (S16).

  Next, the middle divided area received light amount measurement unit 70 calculates the average luminance in each middle divided area. The medium division area received light amount measurement unit 70 obtains the average of the amount of charge (equivalent to the amount of received light or the luminance) of each region obtained by dividing the CCD element included in the camera 10 into 16 and sets this average as the luminance average of the medium division region. As a result, the average luminance in all the medium divided areas such as the average luminance of the medium divided area A and the average luminance of the medium divided area B is obtained (S17).

  Next, the variance value calculation unit 40 calculates the variance value of the luminance average in the region of the captured image based on the luminance average of 225 in all the small divided regions. The process in this step is exactly the same as the process in S6 of the first embodiment (S18).

  The luminance maximum / minimum value difference calculation unit 80 extracts the maximum and minimum of the average received light amount (luminance average) of all the middle divided areas (S19), and calculates the difference (S20).

  Finally, the coating unevenness determination unit 50 determines the coating unevenness of the metallic coating based on the difference between the obtained average brightness dispersion value and the maximum value and the minimum value (S21).

  As described above, there are irregularities in metallic paint, such as uneven spots of small and medium size (patterns) due to fluctuations in the coating conditions and large-size trace irregularities due to spraying unevenness of the paint gun. When the coating unevenness is obtained from the luminance average dispersion value of the small divided areas and the maximum / minimum luminance difference of the medium divided areas as described above, the small and medium uneven spots as shown in FIG. 11A are accurately determined. be able to.

(Embodiment 3)
FIG. 8 is a block diagram showing a schematic configuration of the coating unevenness inspection apparatus in the third embodiment, and this block diagram shows a configuration corresponding to the invention described in claims 3, 4, and 5. The second embodiment is different from the third embodiment in that the block diagram of the third embodiment includes a large divided area received light amount measuring unit 70 and a luminance maximum / minimum value difference calculating unit 95. In the third embodiment, the same blocks as those in the first and second embodiments have exactly the same functions, and thus the description thereof is omitted.

  The large divided area received light amount measurement unit 90 functions as a third area dividing unit, and the image captured by the camera 10 is divided into a plurality of large areas (a plurality of medium divided areas (constituting the second area) of the second embodiment). And the average received light amount of each divided area is calculated.

  The luminance maximum / minimum value difference calculation unit 95 functions as a difference value calculation unit, and calculates a difference between the maximum and minimum of the average received light amount (luminance average) of all large divided areas.

  Next, the operation of the coating unevenness inspection apparatus according to the present invention will be described in detail with reference to the flowcharts of FIGS. 9 and 10 are flowcharts corresponding to the procedures of claims 8 and 9. Of the steps in this flowchart, the processing in steps S21 to S27 is exactly the same as the processing in steps S11 to S17 in the second embodiment, and a description thereof will be omitted.

  The large divided area received light amount measuring unit 90 divides the image of the metallic paint surface 100 captured by the camera 10 into a plurality of large areas. For example, if the captured image of the metallic paint surface 100 is a region (square) as shown in FIG. 4, the region is divided into a total of three large divided regions α,. This divided area has a size of about 200 mm × 40 mm on the metallic painted surface 100 (S28).

  Next, the large divided area received light amount measurement unit 90 calculates the average luminance in each large divided area. The large divided area received light amount measuring unit 90 obtains an average of the charge amount (equivalent to the received light amount or luminance) of each region obtained by dividing the CCD element included in the camera 10 into three, and sets this average as the luminance average of the large divided region. Thereby, the luminance averages in all large divided areas such as the luminance average of the large divided area α and the luminance average of β of the captured image of the metallic paint surface 100 are obtained (S29).

  Next, the variance value calculation unit 40 calculates the variance value of the luminance average in the region of the captured image based on the luminance average of 225 in all the small divided regions. The process in this step is exactly the same as the process in S6 of the first embodiment (S30).

  The luminance maximum / minimum value difference calculation unit 80 extracts the maximum and minimum of the average received light amount (luminance average) of all the middle divided areas (S31), and calculates the difference between them (S32).

  The luminance maximum / minimum value difference calculating unit 95 extracts the maximum and minimum of the average received light amount (luminance average) of all large divided regions (S33), and calculates the difference between them (S34).

  Finally, the coating unevenness determination unit 50 determines the coating unevenness and the type of metallic coating based on the difference between the obtained luminance average dispersion value and the maximum and minimum values of the middle and large divided regions ( S35).

  As described above, the metallic coating unevenness includes spotted medium and small-sized spots (patterns) unevenness due to fluctuations in the coating conditions and large-size locus unevenness due to spraying unevenness of the coating gun. As described above, when the unevenness of painting is obtained from the dispersion value of the luminance average of the small divided areas and the maximum and minimum luminance difference between the middle divided area and the large divided area, the small size to the large size as shown in FIGS. Not only can the coating unevenness be accurately identified, but also the type of coating unevenness, such as whether the coating unevenness is small-sized unevenness, medium-sized unevenness, or large-size unevenness, is also accurately determined. can do.

It is a block diagram which shows schematic structure of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 1). It is a figure which shows the positional relationship of the illumination with respect to a to-be-inspected surface, and a camera (Embodiment 1-3). It is a flowchart which shows operation | movement of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 1). It is a figure with which it uses for description of a division area (Embodiments 1-3). It is a figure which shows the correlation with the variance value (SD) calculated by Embodiment 1, and the sensory evaluation point of the visual inspection by the skilled worker conventionally performed. It is a block diagram which shows schematic structure of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 2). It is a flowchart which shows operation | movement of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 2). It is a block diagram which shows schematic structure of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 3). It is a flowchart which shows operation | movement of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 3). It is a flowchart which shows operation | movement of the coating nonuniformity inspection apparatus concerning this invention (Embodiment 3). It is a figure which shows the kind of coating nonuniformity.

Explanation of symbols

10 cameras,
20 inclined illumination filter,
30 Sub-area light reception measurement unit,
40 variance value calculation unit,
50 Paint unevenness judgment part,
60 lighting,
15, 65 optical axis,
70 Medium division area received light amount measurement part,
80, 95 luminance maximum / minimum value difference calculation unit,
90 Large division area received light amount measurement part,
100 metallic paint surface,
110 Main normal.

Claims (9)

A light irradiation means for irradiating the surface to be inspected with light;
Imaging means for capturing an image of the surface to be inspected;
Area dividing means for dividing the captured image into a plurality of areas;
Average received light amount calculating means for calculating the average received light amount of each of the divided areas;
Dispersion value calculating means for calculating the dispersion value from the average amount of received light in each region;
Coating unevenness determining means for determining the coating unevenness of the surface to be inspected based on the calculated dispersion value;
A coating unevenness inspection apparatus characterized by comprising: A light irradiation means for irradiating the surface to be inspected with light;
Imaging means for capturing an image of the surface to be inspected;
First area dividing means for dividing the captured image into a plurality of first areas;
Second area dividing means for dividing the captured image into a plurality of second areas larger than the first area;
Average received light amount calculating means for calculating the average received light amount of each of the divided first region and second region;
Dispersion value calculating means for calculating the dispersion value from the average amount of received light in each first region;
Difference value calculating means for calculating the maximum and minimum difference values based on the average received light amount of each second region;
Coating unevenness determining means for determining the coating unevenness of the surface to be inspected based on the calculated dispersion value of the first region and the difference value of the second region;
A coating unevenness inspection apparatus characterized by comprising: A light irradiation means for irradiating the surface to be inspected with light;
Imaging means for capturing an image of the surface to be inspected;
First area dividing means for dividing the captured image into a plurality of first areas;
Second area dividing means for dividing the captured image into a plurality of second areas larger than the first area;
A third area dividing means for dividing the captured image into a plurality of third areas larger than the second area;
Average received light amount calculating means for calculating the average received light amount of each of the divided first region, second region and third region;
Dispersion value calculating means for calculating the dispersion value from the average amount of received light in each first region;
Difference value calculating means for calculating the maximum and minimum difference values based on the average received light amount of each second region, and calculating the maximum and minimum difference values based on the average received light amount of each third region; ,
Coating unevenness determining means for determining the coating unevenness and the type of the surface to be inspected based on the calculated dispersion value of the first region and the difference values of the second region and the third region;
A coating unevenness inspection apparatus characterized by comprising:   The angle formed by the optical axes of the light irradiating means and the imaging means with respect to the main normal of the surface to be inspected is such that the diffuse reflected light from the surface to be inspected is easily incident on the imaging means. The angle formed by the optical axis of the irradiating unit and the main normal line is set smaller than the angle formed by the optical axis of the imaging unit and the main normal line. Coating unevenness inspection equipment.   The coating unevenness inspection apparatus according to claim 1, further comprising a filter that removes an inclination component included in reflected light from the surface to be inspected. Irradiating the surface to be inspected with light;
Capturing an image of the surface to be inspected;
Dividing the captured image into a plurality of regions;
Calculating an average amount of received light for each of the divided areas;
Calculating the dispersion value from the average amount of light received in each region;
Determining coating unevenness of the surface to be inspected based on the calculated dispersion value;
A method for inspecting coating unevenness, comprising: Irradiating the surface to be inspected with light;
Capturing an image of the surface to be inspected;
Dividing the captured image into a plurality of first regions and dividing the image into a plurality of second regions larger than the first region;
Calculating an average received light amount of each of the divided first region and second region;
Calculating the dispersion value from the average received light amount of each first region and calculating the maximum and minimum difference values based on the average received light amount of each second region;
Determining coating unevenness of the surface to be inspected based on the calculated dispersion value of the first region and the difference value of the second region;
A method for inspecting coating unevenness, comprising: Irradiating the surface to be inspected with light;
Capturing an image of the surface to be inspected;
The captured image is divided into a plurality of first areas, the image is divided into a plurality of second areas larger than the first area, and the image is further divided into a plurality of third areas larger than the second area. A step of dividing;
Calculating an average received light amount of each of the divided first region, second region, and third region;
The dispersion value is calculated from the average received light amount of each first region, the maximum and minimum difference values are calculated based on the average received light amount of each second region, and the average received light amount of each third region is also calculated. Calculating the maximum and minimum difference values, respectively;
Determining coating unevenness of the surface to be inspected based on the calculated dispersion value of the first region and the difference value of the second region and the third region;
A method for inspecting coating unevenness, comprising:   The coating unevenness according to any one of claims 6 to 8, further comprising a step of removing an inclination component included in reflected light from the surface to be inspected after the step of taking an image of the surface to be inspected. Inspection method.