JPH0587505U - Aluminum orientation distribution measuring device for metallic paint surface - Google Patents

Abstract

(57) [Summary] [Purpose] Highly sensitive and rapid automatic measurement of metal unevenness on metallic coated surfaces regardless of the observation angle and lighting conditions. [Structure] The sensor unit 1 has one light source and two light receivers. A plurality of sensor units 1 are arranged side by side in the main scanning direction, and the image data in the main scanning direction is captured as an analog signal by performing scanning for the effective length. The drive device 2 is controlled by the drive signal generation circuit 3 to drive the sensor unit 1 in the sub-scanning direction. In this way, in-plane scanning is performed. This series of analog signals
After being converted into a digital signal by the A / D conversion circuit 4, it is sent to the image processing device 5. Then, the controller 6 outputs the processing result of the image processing device 5.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an aluminum orientation distribution measuring device for a metallic coated surface such as an automobile body outer panel for automatically measuring so-called metal unevenness.

[0002]

[Prior art]

 In recent years, with the trend toward higher-grade automobiles, the coating color of automobile body shells has become an important factor. Generally, when the coating color of an automobile body skin is classified according to the type of coloring component, there are solid color, metallic color and mica color. The metallic colors and mica colors include aluminum pieces and mica pieces, and are rich in novelty and variety of paint colors. Therefore, the metallic and mica colors tend to increase year by year.

Of these, the aluminum pieces contained in the metallic-colored coating film are scale-like and have larger particles than other color pigments. Therefore, when a paint containing this aluminum piece is applied to an object to be coated such as an automobile body outer plate with a spray gun or the like, the aluminum piece may not be uniformly dispersed in the coating film. In such a case, the reflection of light is not uniform, and the uneven shading characteristic of the metallic coated surface occurs. Generally, this unevenness of light and shade is called metal unevenness. The metal unevenness spreads over a wide area on the surface of the object to be coated, and the nonuniformity on the surface of the metallic surface can be detected only from a specific direction. Therefore, it is difficult to automatically measure the density distribution of metal unevenness. Therefore, conventionally, the quality of the metallic coated surface is visually determined.

[0004]

[Problems to be solved]

 However, the above-mentioned metal unevenness is characterized by the shape of the scale-like aluminum piece, and the light and shade distribution state appears to differ depending on the illumination conditions and observation direction. Therefore, the visual judgment of the quality of the metallic coated surface could be erroneous. As a means for measuring a surface such as a metallic coated surface where the reflected light has a unique pattern, there is a method of receiving the reflected light by two or more light receivers (for example, Journal of Coatings Technology, Voll. 62, No. 782 (1990)).

As shown in FIG. 7, the aluminum orientation measuring device according to this method has one light source 91 and two light receivers 92 and 93 that receive reflected light from the metallic coating surface 90 from two directions. The ratio of the reflected light from the two directions is the amount of aluminum orientation at that point. Other measuring devices of this type include metallic feeling measuring devices and gonio-color difference meters. However, with this method, only points can be measured, and much time is required to measure the surface.

Therefore, for the measurement of the surface, a density distribution measuring device that captures the state of the surface as an image is often used. As shown in FIG. 8, this type of device has a single light receiver 94 composed of an optical sensor such as a CCD. However, this type of device is not always able to measure from the direction in which the grayscale changes are large. Therefore, it has poor sensitivity and cannot be used to measure metallic coated surfaces. In view of the above conventional problems, the present invention provides an aluminum orientation distribution measuring device for a metallic coating surface, which is capable of automatically measuring metal unevenness on a metallic coating surface with high sensitivity and speed, regardless of the observation angle and lighting conditions. It is the one we are trying to provide.

[0007]

According to the present invention, there are provided a plurality of light receivers and light sources arranged in parallel in the main scanning direction and having at least two light receivers and light sources for replacing the density distribution state of metal unevenness on a metallic coating surface with an electrical analog signal. A sensor unit; a drive device for driving the plurality of sensor units in the sub-scanning direction orthogonal to the main scanning direction; and a drive signal generation circuit for driving and controlling the drive device in the sub-scanning direction. Based on the A / D conversion circuit for converting the analog signal output from the sensor unit into a digital signal and the image data obtained from the A / D conversion circuit, the density distribution state of the metal unevenness is characterized. And an image processing device for controlling the image processing device, and a controller for calculating and outputting the processing result. In the aluminum orientation distribution measuring device of metallic painted surfaces you.

What is most noticeable in the present invention is that the aluminum orientation amount in the main scanning direction is measured by a plurality of sensor units arranged side by side in the main scanning direction, and the plurality of sensor units are measured by a driving device and a driving signal generating circuit. It is configured to scan in the plane by driving in the sub scanning direction. Further, the data is digitized by an A / D conversion circuit and processed by an image processing device and a controller such as fast Fourier transform.

In the present invention, the sensor unit includes a light source and a light receiver. Examples of the light source include an LED (light emitting diode) array and a laser light scanner. Further, as the light receiver, there are those using α-Si and CCD (charge coupled device). At least two light receivers are provided for one light source. This is because the ratio of the reflected light from the two directions is the amount of aluminum orientation at the measurement point.

Here, the orientation amount of aluminum is an orientation index of aluminum and is calculated by the following equation. Aluminum orientation amount = (light amount of one reflected light) / (light amount of the other reflected light) The incident angle of the light source is, for example, 0 ° to 60 °. Here, the angle measured clockwise with respect to the normal at the measurement point is positive. Further, one of the light receivers is arranged so as to be inclined at an angle in the range of 0 ° to 90 ° so as not to overlap the incident angle of the light source. The other photodetector is installed at an angle in the range of 0 ° to -90 ° so as not to be in the direction of regular reflection with respect to the incident angle of the light source.

The plurality of sensor units are arranged side by side in the main scanning direction. Therefore, the light source and the two or more light receivers forming the sensor unit are arranged in a line along the main scanning direction. This main scanning direction should be the spraying direction of the coating gun. This makes it possible to accurately detect the density distribution of metal unevenness on the metallic coated surface. Here, metal unevenness refers to unevenness of light and shade on the metallic coated surface.

As the drive device, for example, a stepping motor or a servo motor is used. As the drive signal generation circuit, for example, there is a circuit that generates a pulse signal for control to a stepping motor. The A / D conversion circuit is a circuit that converts an analog signal output from the sensor unit into a digital signal so that the image data is processed by the image processing device and the controller.

The image processing apparatus described above is intended to characterize the density distribution state of metal unevenness by applying various arithmetic processing to image data as a digital amount obtained from the A / D conversion circuit. is there. This arithmetic processing includes smoothing processing and Fourier transform processing. Here, the smoothing process is a process for removing signals or noise with a period shorter than the grayscale period of the metal unevenness to be measured. Although various methods have been proposed for this smoothing processing, the selective local averaging (adaptive averaging) method is suitable here.

The Fourier transform process is a process for performing a Fourier transform on the smoothed image data with the acquisition pitch as a unit period to obtain a power spectrum diagram that is the frequency for each frequency. Is. This Fourier transform processing can also be processed by the FFT (Fast Fourier Transform) algorithm in the above controller. The controller has a CPU (central processing unit), a control device, a storage device that stores a predetermined calculation / control program, and a display device that outputs a processing result.

[0015]

[Action and effect]

 In the present invention, a plurality of sensor units arranged side by side in the main scanning direction are electrically scanned in the main scanning direction, and the image data for the effective length is captured. At this time, the light from the light source is reflected by the metallic coating surface and is received by the two light receivers. Each photodetector replaces the density distribution of metal unevenness on the metallic coated surface with an electrical analog signal. The ratio of the outputs of these receivers is the aluminum orientation amount. Next, the drive unit and the drive signal generation circuit drive the sensor unit at a predetermined interval in the sub-scanning direction. Then, the sensor unit is run in the main scanning direction and the image data for the effective length is captured again. In-plane scanning is performed by repeating the same scanning and driving.

The series of analog signals thus captured are converted into digital signals by the A / D conversion circuit and then sent to the image processing apparatus. In the image processing apparatus, the image data obtained from the A / D conversion circuit is subjected to processing such as smoothing to characterize the density distribution state of metal unevenness. At this time, the controller controls the image processing device and also calculates and outputs the processing result.

In this way, the ratio of the reflected light from the two directions is set as the aluminum orientation amount at the measurement point, this is scanned in the plane, and the metal unevenness is measured based on the data of the orientation amount in the plane. To do. Therefore, according to the present invention, an aluminum orientation distribution measuring device for a metallic coated surface can be provided, which is capable of automatically measuring metal unevenness on the metallic coated surface with high sensitivity and speed, regardless of the observation angle and lighting conditions. can do.

[0018]

【Example】

 An apparatus for measuring an aluminum orientation distribution on a metallic coating surface according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 to 3, the apparatus of this example is arranged in parallel in the main scanning direction X, and is for replacing the light and light distribution of the light source 11 and the metallic coating surface 90 with an electrical analog signal. A plurality of sensor units 1 having two light receivers 12, a drive unit 2 for driving the plurality of sensor units 1 in a sub-scanning direction Y which is orthogonal to the main scanning direction X, and a sub-unit of the drive unit 2 And a drive signal generation circuit 3 for controlling the drive in the scanning direction Y. Also, based on the A / D conversion circuit 4 for converting the analog signal output from the sensor unit 1 into a digital signal and the image data obtained from the A / D conversion circuit 4, the density distribution state of the metal unevenness is determined. It has an image processing device 5 for characterizing, and a controller 6 for controlling the image processing device 5 and calculating and outputting the processing result.

In this example, the spraying direction of the coating gun is the main scanning direction X. As shown in FIG. 3, the sensor unit 1 comprises a housing 10, the light source 11, the two light receivers 12, and a protective glass 13. The light source 11 is tilted along the sub-scanning direction Y so as to form an incident angle α with respect to the perpendicular L. Further, the two light receivers 12 are arranged along the sub-scanning direction Y so as to be inclined with respect to the perpendicular L so as to have reflection angles β1 and β2, respectively. In this example, α = + 30 degrees, β1 = + 60 degrees, and β2 = −60 degrees. The light receiver 12 has a condenser lens 121 and an optical sensor 122 that generates a photoelectromotive force by irradiation with light.

As shown in FIGS. 2 and 3, a plurality of sensor units 1 are arranged side by side in the main scanning direction X. Therefore, the two light receivers 12 are set as one unit, and these are arranged in the left and right one rows along the main scanning direction X. As shown in FIG. 2, the driving device 2 includes a pair of rails 21 arranged along the sub-scanning direction Y, a slider 22 slidably engaged with both rails 21, and a screw hole of the slider 22. A ball screw 24, which is screwed onto (not shown) and arranged along the rail 21, and a stepping motor 23 for rotationally driving the ball screw 24. The plurality of sensor units 1 are horizontally mounted between the sliders 22.

The drive signal generation circuit 3 is a circuit for sending a pulse to the stepping motor 23. The controller 6 has a CPU, a control device, a storage device and a display device, and the control device is connected to a system interface circuit 7 as shown in FIG. In this example, a control computer is used as the controller 6.

Since the device of this example is configured as described above, the following operational effects are exhibited. That is, in measuring the metal unevenness on the metallic coated surface, as shown in step 801 in FIG. 4, first, the image is input by the sensor unit 1. Specifically, as shown in FIG. 2, in a state where the sensor unit 1 is closely attached to the metallic coating surface 90, the sensor unit 1 is scanned in the main scanning direction X, and the image data of the effective length L is obtained. Take in. At this time, as shown in FIG. 3, the light emitted from the light source 11 is reflected by the metallic coating surface 90 and received by the two light receivers 12. Each light receiver 12 replaces the density distribution state of the metal unevenness on the metallic coated surface 90 with an electric analog signal. Here, this analog signal is a voltage generated by the optical sensor 122 of the light receiver 12. The ratio of the outputs of the two light receivers 12 is the orientation amount of aluminum.

Next, a predetermined pulse is sent from the drive signal generation circuit 3 to the stepping motor 23 of the drive device 2. As a result, the sensor unit 1 is driven in the sub-scanning direction Y by a predetermined interval. Then, the sensor unit 1 is scanned in the main scanning direction X, and the image data for the effective length L is taken in again. In-plane scanning is performed by repeating the same scanning and driving. The series of analog signals thus captured are converted into digital signals by the A / D conversion circuit 4, as shown in step 802 in FIG. After that, the image data is sent to the image processing apparatus 5 and is smoothed in the image processing apparatus 5 as shown in step 803 in FIG. By this smoothing process, signals or noise with a period shorter than the shading period of metal unevenness are removed.

Further, as shown in step 804 in FIG. 4, FFT processing is performed on the image data. Here, this FFT processing is performed by the FFT program of the controller 6. In this way, the power spectrum, which is the frequency for each frequency, is obtained by subjecting the smoothed image data to Fourier transform processing with the acquisition pitch as the unit period. Then, as shown in step 805 in FIG. 4, from the power spectrum thus obtained, the spectrum cumulative frequency at the frequency that can cause metal unevenness is calculated as the density uniformity. Further, as shown in step 806 in FIG. 4, the metal mura rank is calculated from the correspondence relationship between the density uniformity and the metal mura rank visually.

Next, description will be made based on specific data. As shown in the upper part of FIGS. 5 and 6, image data on the orientation distribution of aluminum was obtained using two metallic coating surfaces 90 having different levels of metal unevenness. The metallic coated surface 90 shown in FIG. 5 was selected to have relatively small metal unevenness by visual inspection. The metallic coated surface 90 shown in FIG. 6 is selected to have a relatively large metal unevenness by visual observation, and has a metal unevenness B. The image data was divided into 256 gradations. Then, after smoothing the original image data, the pitch of the captured data points was read as a sample time of 1 second, and the spectrum was converted by applying the FFT program. As a result, the power spectrum diagrams shown in the lower part of FIGS. 5 and 6 were obtained.

In this power spectrum diagram, the horizontal axis is the logarithmic display of the frequency, and the larger the numerical value, the shorter the cycle changes. Therefore, the presence / absence of a large shade change as in this example is paraphrased by the magnitude of the spectral amount in the small frequency part. The magnitude of these low frequency regions may be compared with the spectral amount at a specific point, but in this example, the spectral amount between frequency regions A (frequency -2.4 to -1.8) is used. It was represented by the integrated value of. Comparing the integrated values of the spectrum amount in the frequency range A in FIGS. 5 and 6, it can be seen that the integrated value of the spectrum amount is larger in FIG. From the correspondence between this evaluation value and the predetermined metal mura rank by visual inspection, the metallic paint surface 90 shown in FIG. 5 is the metal mura rank 3, while the metallic paint surface 90 shown in FIG. It turned out to be Mura rank 2. In addition, this metal mura rank shows that the larger the value, the better the metal mura level.

As described above, in this example, the ratio of the reflected light from the two directions is set as the orientation amount of aluminum at the measurement point, and this is scanned in the plane. Furthermore, based on the in-plane orientation data, the direction with the largest orientation change is extracted by the FFT method, and the nonuniformity level of the orientation of the sample is determined from the power spectrum. Therefore, according to this example, it is possible to automatically measure the metal unevenness on the metallic coating surface with high sensitivity and speed regardless of the observation angle and the illumination conditions.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining an outline of an aluminum orientation distribution measuring device for a metallic coated surface according to an embodiment.

FIG. 2 is a schematic plan view of a sensor unit and a driving device according to an embodiment.

FIG. 3 is a side sectional view of the sensor unit according to the embodiment.

FIG. 4 is a flowchart for explaining an outline of a processing procedure of image data in the aluminum orientation distribution measuring apparatus of the embodiment.

FIG. 5 is a diagram showing an example of processing results by the image processing apparatus and the controller of the embodiment.

FIG. 6 is a diagram showing another example of processing results by the image processing apparatus and the controller of the embodiment.

FIG. 7 is a schematic explanatory diagram of a conventional aluminum orientation measuring device.

FIG. 8 is a schematic explanatory view of a conventional metal unevenness density distribution measuring device.

[Explanation of symbols]

 1. ． ． Sensor unit, 11. ． ． Light source, 12. ． ． Light receiver, 2. ． ． Drive device, 3. ． ． Drive signal generation circuit, 4. ． ． A / D conversion circuit, 5. ． ． Image processing device, 6. ． ． Controller, 90. ． ． Metallic painted surface, X. ． ． Main scanning direction, Y. ． ． Sub-scanning direction,

Claims (1)

[Scope of utility model registration request] 1. A plurality of sensor units arranged in parallel in the main scanning direction, each sensor unit having at least two light receivers and light sources for replacing the density distribution of metal unevenness on a metallic coating surface with an electrical analog signal, A drive device for driving the provided plurality of sensor units in a sub-scanning direction orthogonal to the main scanning direction, a drive signal generating circuit for driving and controlling the drive device in the sub-scanning direction, and the sensor unit Based on the A / D conversion circuit for converting the output analog signal into a digital signal, and the image data obtained from the A / D conversion circuit,
An aluminum orientation of a metallic coating surface, characterized by comprising an image processing device for characterizing the density distribution state of the metal unevenness, and a controller for controlling the image processing device and computing and outputting the processing result. Distribution measuring device.