JPS6395309A - Method for measuring smoothness of coating surface - Google Patents

Abstract

PURPOSE:To evaluate a two-dimensional coating surface over a wide range with high accuracy, by picking up the image of the vertical stripe lattice projected to the coating surface by a two-dimensional image sensor to process the same. CONSTITUTION:A vertical stripe lattice panel 2 is arranged to the part diagonally upward with respect to a coating surface 1 on one side thereof and the vertical stripe lattice image of said panel 2 is projected to the coating surface 1. A CCD type TV camera 3 for picking up said image is arranged to the part diagonally upward with respect to the coating surface 1 on the other side thereof and connected to an image signal processing part 10. As an orange peel state worsens, the incident image to the camera 3 increases in the disturbance degree of luminosity and, when an image signal wave form is monitored by a CRT monitor tube 14, the wave form of a signal level changes corresponding to the change in luminosity caused by the vertical stripe lattice image. By this method, the image data corresponding to one picture picked up by the camera 3 are taken in RAM 13 of the processing part 10 and processed by analytical CPU 13 and a smoothness level is evaluated corresponding to the number of inflection points being detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for measuring the smoothness of a painted surface of an automobile body, etc., by optoelectronically measuring the roughness of a painted surface.

(Prior art) When performing such measurements, conventionally, light is irradiated through a vertical striped grating, and the reflected light is detected using a linear image sensor in which photodiodes are linearly arranged in the orthogonal direction.
The smoothness of the painted surface was evaluated from the amplitude distribution of the analog output signal along the sensor.

Problems that C-originated IJJ attempts to solve] However,
This method relies on human vision, and it is difficult to perform surface evaluations, so high-precision measurements have not been possible.

Therefore, according to the method for measuring the smoothness of a painted surface according to Japanese Patent Application No. 61-137312, which is an earlier application of the present application, the painted surface is irradiated with light in 7 lines, and the reflected light is imaged by a two-dimensional image sensor, and the image signal level is A method has been proposed in which the smoothness of the painted surface is determined based on the distribution of these level data. Although this makes it possible to perform highly accurate seven-sided measurements, there remains the problem that the measurement range cannot be widened because the measurement range is limited to the parallel light irradiation area.

Accordingly, an object of the present invention is to provide a method for measuring the smoothness of a painted surface of the type described above, which can be used to evaluate a two-dimensional painted surface over a wide range with high accuracy.

Means and operation for solving problem C) In order to achieve this object, the present invention maps a vertical striped grid placed on one side of the painted surface under natural light, as shown in FIG. A two-dimensional image sensor focuses on the painted surface and captures the image. At this time, by sequentially reading and scanning the image sensor in a direction substantially perpendicular to the vertical striped lattice image, the image signal level of the vertical striped lattice image changes gradually due to the fact that the vertical striped lattice image is out of focus. Furthermore, as the reflection angle of the grating image is disturbed due to the unevenness of the painted surface, the amount of light incident on the separated image sensor fluctuates, and a wavy inflection point where the slope changes from positive to negative is superimposed on the level change curve. . Therefore, the number of these inflection points is counted and the smoothness of the painted surface is determined from the magnitude of this counted value.

(Embodiments of the invention) Does the second VA implement the method of the invention? In this example, two vertical striped grid panels (the number of grids are omitted) with a width and phase interval of several 1 hm are arranged above the diagonal opening on one side of the painted surface L, and the number of surfaces of the painted surface L is In the 100-1 square, a CCD type TV left camera for capturing a vertical stripe grid image is arranged above the diagonal opening on the opposite side of the vertical strip grid image, and an image signal processing section 10 follows.

This processing section digitizes the image signal of the TV left camera generated by readout scanning ^/D converter 1
1 and a RAM + that stores this digital signal at the address corresponding to the 256 x 256 pixels of the TV left camera.
2, an analysis computer 13 that takes in image data from this memory and processes it, and a D
/Convert to analog with A converter 14b and switch circuit +4a
and a cathode ray tube monitor 14 for selectively displaying images through the screen.

As shown in the flowchart of FIG. 4, the analysis computer 1 reads out the image data taken into the RAM 12 in a direction orthogonal to the vertical striped lattice, and sequentially compares the signal levels of the previous and next addresses to detect small waveforms. Inflection point 17
(Figure 3a) is detected, and the number N of inflection points 17 on the entire imaging plane is detected.
, is counted.

In addition, such an inflection point portion of the read signal is subjected to low-pass processing (Fig. 3b), and the number N of large waves 18 corresponding to the number of grids after smoothing is counted from 0 then the count value N. N
, to accurately calculate the count value NY due to the unevenness of the painted surface l.
Calculate. Then, the smoothness is determined by comparing it with a verification curve table that specifies the smoothness for the count value NY stored in advance in the memory 13a, and the smoothness signal is output to an attached recording device or display device (not shown). .

Smoothness configured like this? Explain the operation of placing.

During the measurement, the focal length of the TV left camera, which is located a predetermined distance away, is set to the painted surface l, and the aperture is set in an open state. In this state, the incident image to the TV left camera is as shown in Figure 5 a if the condition of the painted surface l is bad, as shown in Figure 5 if it is f1, and as shown in Figure 5 C if it is good. As the condition of the citron skin deteriorates, the brightness changes corresponding to the lattice of the vertical striped lattice panel 2 become unclear.

In other words, as the Yuzu skin condition worsens, the degree of brightness disturbance increases. When the image signal waveform is monitored on the cathode ray tube monitor 14, the signal level changes in a wave-like manner in response to the change in brightness caused by the vertical striped lattice image, as shown in FIG. 3a. By the way, if the focus or aperture is adjusted so that the TV left camera sharply images the vertical striped grid panel 2, the incident image will have a clear brightness difference as shown in Figure 6, and the image signal will have a rectangular shape. , and it becomes difficult to detect the inflection point with sufficient level discrimination.

The image signal processing unit IO captures one screen worth of image data captured by the TV left camera into its RAM +2.

The analysis computer 13 processes the data according to the flowchart shown in FIG. 4, and thereby evaluates the smoothness level corresponding to the detected number of inflection points Nv.

Figure 7 shows the size 700× with the cap and the mutual spacing being 0.
700■■ vertical striped lattice panel, white in color and size 250
x 200mm coated plate, focal length 50mm (standard 16mm) aperture F], using a TV camera with an 8 (open 7TK) lens, 1.500mm between Vaneroo coated plates.
An experimental example is shown in which the number of inflection points for a reference coated surface having various coated skin conditions was measured under the measurement conditions of 1.20 ha between the m-board and the camera, and both the incident angle and the reflection angle of 20 degrees. Through such experiments, a table is stored in the analysis computer of the relationship between the painted skin rank and the number of inflection points at multiple levels for the type of painted surface to be measured.

In the above embodiment, the vertical striped lattice panel 2 has a painted surface l.
When calculating the number of inflection points N7, it is not necessary to subtract the number of grids N2 if there is no problem with accuracy.

(Effects of the Invention) As described above, according to the present invention, since parallel light illumination is not necessary, a wide range of measurement is possible, and high precision, automatic and
Quantitative measurement becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a flowchart explaining the method for measuring the smoothness of a painted surface according to the present invention, Fig. 2 is a diagram showing the configuration of an apparatus for carrying out this method, and Fig. 3 is a waveform explaining the operation of the same embodiment. Figure 4 is a flowchart explaining the operation of the same embodiment, Figures 5 and 6 are diagrams explaining the operation of the same embodiment, respectively, and Figure 7 shows a verification curve of the present invention based on an experimental example. FIG. l...Painted surface, 2...Vertical striped lattice panel, 3.-TV camera.

Claims (1)

[Scope of Claims] A vertical striped lattice arranged above is mapped onto a painted surface, the painted surface is imaged by a two-dimensional image sensor with focus on the painted surface, and the vertical striped lattice image is mapped in a direction substantially orthogonal to the vertical striped lattice image. The wave-like inflection points that are superimposed on the level change curve of the image signal obtained by sequentially reading the image sensor and that occur due to the unevenness of the painted surface are detected, and the inflection points are counted to calculate this value. A method for measuring the smoothness of a painted surface, which determines the smoothness of the painted surface from a counted value.