JP2617795B2 - Gloss measuring method and equipment for painted surfaces - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for quantitatively measuring the gloss of a painted surface.

[Prior Art] This type of measuring device is described in, for example, the coating technology “March 3, 1985”.
Monthly, published by Riko Publishing Co., Ltd. " That is, a first method is to project characters of different sizes onto a painted surface to determine which size characters can be read without being affected by the distortion, or as a second method. An image of a test chart of light and dark stripes is formed on a painted surface, and the contrast is defined by the following equation.

It is well known that a modulation transfer function (MTF) curve in which contrast values are plotted using the reciprocal of the pitch of the test chart as a horizontal axis and an area value in a predetermined range of the curve is used as an index.

In addition, as a third method, a method of irradiating a painted surface with a light beam at a fixed angle from an oblique direction, receiving reflected light at the fixed angle, and determining gloss from the light amount is also known.

[Problems to be solved by the invention]

However, the first method described above cannot automatically detect the index, and the second method can automatically output the index. However, when trying to detect fine irregularities in the glossy area, the pitch and type of the test chart are reduced. Must be increased, the arithmetic processing becomes complicated, and there remains a problem in practically improving the discrimination performance. Similarly, the third method can automatically output an index, but it is necessary to reduce the area of the light beam, and it is actually difficult to obtain high discrimination performance.

An object of the present invention is to provide a method and apparatus for more practically quantitatively measuring the gloss of a painted surface with a high degree of discrimination in view of the current situation.

[Means for solving the problem]

In order to achieve this object, the present invention confirms that the glossiness of the painted surface is caused by the degree of roughness of the surface having a roughness of 0.05 mm to almost 1 mm, which is 0.01 mm to a slightly wide limit of visual perception. Then, the measurement of the next step is performed. That is, an analog signal having a level corresponding to the unevenness of the painted surface is output by scanning the painted surface at a constant speed while shifting the painted surface in a line shape in a direction orthogonal to the line with a roughness meter. Next, the analog signal is subjected to Fourier analysis, and a slope factor corresponding to an amplitude component ratio with respect to each wavelength is calculated, and curve data of a slope factor with respect to a wavelength change is created. Further, the area of the wavelength region corresponding to the width of the unevenness of the painted surface of 1 mm is calculated from the perceptual limit of the curve data, and the value corresponding to this area value is used as a gloss index.

As a device that performs this method, a roughness meter that outputs a level analog signal according to the unevenness of the painted surface by scanning at a constant speed while shifting the painted surface in a line shape in a direction orthogonal to the line, An analog signal is input, and a band-pass filter of a band wider than the frequency band corresponding to the painted surface unevenness width of 1 mm from the visual perception limit, and the output signal of this band-pass filter is subjected to least square processing to bend the painted surface. Least square processing means for outputting a painted surface unevenness signal corresponding to the deviation value corrected for FFT means for converting the painted surface signal into a fast Fourier, and FFT processing (amplitude component) ² /
(Wavelength) A slope curve data creation means for calculating curve data of the slope factor with respect to wavelength change by calculating ² as a slope factor, and corresponding to a painted surface unevenness width of 1 mm from the visual sensitivity limit related to the gloss performance of the curve data. It is conceivable to comprise an area calculating means for calculating the area of the wavelength region to be processed and an output means for outputting a value corresponding to the area value as a gloss index.

[Action]

By scanning the painted surface with a roughness meter at a constant speed,
An analog signal that changes according to the scanning speed and the unevenness is obtained. Therefore, by Fourier analysis, as shown in FIG. 1a, the amplitude component corresponding to the width of the unevenness and its depth with respect to the wavelength change corresponding to the scanning speed is obtained. Desired. Based on these spectral components, as shown in FIG. 1b, curve data of a slope factor, which is an amplitude component / wavelength or its square, is created, and a wavelength region corresponding to an uneven width of 1 mm from the visual sensitivity limit. Is calculated, and a value corresponding to the area value is obtained as a gloss index. In this way, the integrated value of the gradient distribution for 1 mm unevenness is evaluated from the visual perception limit existing over the entire painted surface.

According to the apparatus that performs this method, the index indicating the gloss performance is automatically printed out or displayed from the output unit.

〔Example〕

FIG. 2 is a functional block diagram showing a configuration of a gloss measuring device for a painted surface according to the present invention.

In the figure, reference numeral 10 denotes a 4 × 5 mm painted surface 1 per line 5
This is a three-dimensional roughness tester that scans at a constant speed with 32 needles on a 26-point line scanning line and generates an analog signal of a wavelength and level corresponding to the unevenness of the painted surface 1 based on the fluctuation. Reference numeral 11 denotes a band-pass filter that passes a wavelength range corresponding to a concavo-convex width of 0.01 to 2.5 mm and that is digitized by the A / D converter 12. Reference numeral 13 denotes a least square processing means for obtaining a digitized painted surface unevenness signal as a surface shape based on, for example, a quintic regression curve, and generating a deviation signal as a pure painted surface unevenness signal with a corrected curvature. I do. 14 is FFT
(Fast Fourier transform) processing means for analyzing the amplitude power component for each wavelength after performing a well-known Hanning process for weighting the sampling time window. 15 is a curve of a slope factor, which is a power spectrum of a slope with respect to a wavelength change, by calculating (amplitude component) ² / (wavelength) ² in an amplitude range corresponding to an uneven width of 0.05 to 1 mm based on the result of the FFT processing. This is a slope curve data creating means for creating data. 16 is
An area calculating means for calculating an area value in a wavelength range corresponding to 0.05 to 1 mm for the curve data. 17 and 17a
Is a CRT monitor that displays curve data as output means and a printer that prints out an index as an area ratio where the calculated area value is, for example, three digits or its reference area value is, for example, 100.

Each of the above-described units 13 to 16 can be configured by a computer programmed to take in an output signal of the A / D converter 12 and perform each of the above-described functions. This computer is followed by a printer 17a and a cathode ray tube monitor 17. In this case, when the area ratio or the like is used as an index without using the area itself as an index, the calculation may be performed by the computer.

 The operation is as follows.

The three-dimensional roughness meter 10 scans the painted surface 1 at a constant speed to generate an analog signal having an amplitude and a wavelength corresponding to the depth, width and scanning speed of the unevenness. The bandpass filter 11 removes frequency components irrelevant to the gloss evaluation by passing through a wavelength region corresponding to the coating surface unevenness width of 0.01 to 2.5 mm. With respect to the filter output digitized by the A / D converter 12, the least squares processing means 13 extracts a deviation from the quintic regression curve to generate pure painted surface unevenness data.

As a result, the FFT processing means 14 analyzes the amplitude power component (amplitude component) ² for each wavelength with respect to the coating surface unevenness signal,
The slope curve data creating means 15 is irrelevant to the Yuzu skin performance, and calculates a slope power spectrum (amplitude component) ² / (wavelength) ² in the range of 0.05 to 1 mm of the coated surface unevenness width related to the gloss performance as a slope factor, Create a slope power spectrum curve. The area calculating means 16 calculates the curve data from 0.05
Calculate the area value of the wavelength equivalent range of 1 mm. This area value corresponds to the variance of the average inclination angle distribution of the painted surface related to the gloss. The CRT monitor 17 displays the tilt power spectrum with the wavelength change as the horizontal axis, and the gloss index is printed out on the printer 17a.

As a result, an index correlated to the gloss not affected by the yuzu skin is automatically obtained as an integral value of the gradient power spectrum corresponding to the variance of the average gradient angle distribution, and the degree of gloss of the painted surface is determined by the magnitude of the value. I understand.

Table 1 shows test results in comparison with the above-mentioned conventional method in order to confirm the effects of the present invention.

As a sample, a white painted plate in which the sensory evaluation of gloss by the paired comparison method (Nakaya's modified method) was different in stages at a significant level of 1% was used.
Sheets (No.1 to No.5) were prepared. And the index of the present invention is:
Measurement area value / Sample No. 1 with the worst sensory evaluation
Reference area value × 100 was used as an index. In addition, the first method using the size of a character that can be read without being affected by the above-described distortion as an index, the commercially available device using the second method based on the MTF by Fourier transform, and the reflected light amount of the light beam Was compared with a commercially available device according to the third method. The second and third methods are for the case where the index of the best state is 100.

As is clear from this table, the discrimination ratio was greatly improved as compared with the first method, and the sample was more susceptible to the second method.
It can be seen that the difference in the luster performance between No.3 and No.4 can be reliably discriminated. Incidentally, according to this method, the index was sometimes inverted. In the third method, the discrimination performance is clearly worse than that of the present invention, and the index between No. 4 and No. 5 is reversed.

〔The invention's effect〕

As described above, according to the present invention, the integrated value of the slope factor of the unevenness having a width of 1 mm or less is automatically output as an index for quantitatively evaluating the gloss, and the gloss level can be distinguished with high accuracy.

A device that performs a least-squares process on the painted surface unevenness signal and performs an FFT process on the deviation value automatically outputs a highly reliable index that corrects the curved surface of the painted surface.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method for measuring the gloss of a painted surface according to the present invention, and FIG. 2 is a functional block diagram showing a configuration of an apparatus for implementing the method of the present invention. 1 ... Painted surface.

Claims (2)

(57) [Claims] An analog signal having a level corresponding to the unevenness of the painted surface is output by scanning the painted surface at a constant speed while shifting the painted surface in a line shape in a direction perpendicular to the line with a roughness meter. An analog signal is subjected to Fourier analysis to calculate a slope factor corresponding to the amplitude component ratio for each wavelength, and to create curve data of the slope factor with respect to a wavelength change. A method for measuring the gloss of a painted surface, comprising: calculating an area of a wavelength region corresponding to (i), and using a value corresponding to the area value as an index of luster. 2. A roughness meter which scans a coating surface at a constant speed while shifting the coating surface in a line shape in a direction orthogonal to the line, and outputs an analog signal having a level corresponding to the unevenness of the coating surface, And a bandpass filter that passes a frequency band corresponding to a painted surface unevenness width of 1 mm from the visual perception limit, and a least square processing of an output signal of the bandpass filter, thereby bending the painted surface. Least square processing means for outputting a painted surface unevenness signal corresponding to the deviation value obtained by correcting FFT means for performing fast Fourier transform processing on the painted surface unevenness signal; and (amplitude component) ² / (wavelength ) ² was calculated as the inclination factor, the slope curve data creating means for creating a curve data of the inclination factor for wavelength change, 1 mm from the visual sensing limit of the curve data An area calculating means for calculating the area of the wavelength region corresponding to the uneven width of the painted surface, and an output means for outputting a value corresponding to the area value as a gloss index, a gloss measuring apparatus for a painted surface, comprising: .