JPH037897B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for determining glossiness of an object surface,
In particular, it is suitable for measuring and managing the surface quality of steel sheets, and is a method for determining the glossiness of the surface of an object, which classifies and grades the glossiness based on the visual sensation based on the light reflection intensity distribution on the object surface. Regarding improvements.

[Conventional technology]

Various methods have been proposed to determine the light sensitivity of an object's surface using light reflection measurements.A typical method is specular gloss measurement, which measures the specular reflection intensity of a white beam projected at a fixed angle. method, a method based on contrast glossiness that uses the ratio of specular reflection intensity and diffuse reflection intensity of white light projected at a certain angle, and a method based on clear glossiness, which reflects another object on the surface and observes the blurring of the reflected image with the naked eye. There is a way.

[Problems to be solved by the invention]

However, the method based on specular gloss,
Although it is widely used industrially, it has the disadvantage that it does not match reality for specular objects with small surface roughness. In addition, the method using the comparative glossiness,
Although it has the characteristic of giving a gloss level close to visual perception even to objects of different colors, the determination accuracy also tends to be low for objects that are close to mirror surfaces.
Furthermore, the method using the sharp glossiness has a problem in that quantitative indications cannot be obtained.

[Purpose of the invention]

The present invention was made to solve the above-mentioned conventional problems, and has the same color (brightness may be different).
The purpose of the present invention is to provide a method for determining the glossiness of the surface of an object that closely matches the visual glossiness and that can quantitatively determine the glossiness over a wide roughness range from specular to rough surfaces. shall be.

[Means to solve the problem]

The present invention uses the light reflection intensity distribution on the object surface to
In a method for determining the glossiness of an object's surface that classifies and ranks the glossiness based on visual perception, as shown in Figure 1, the variance σ of the height distribution of the measured surface profile is determined by the following relationship {( _The wavelengths λ _{1 and λ 2 ( λ} ¹ ₌ ^λ ₂ ), two light beams with wavelengths λ _{1 and} λ ₂ with incident angles θ ₁ and θ 2 are projected at incident angles θ ₁ and θ ₂ , and the specular reflection intensities I ₁ ,
Detect I ₂ and total reflection intensities S ₁ and S ₂ , plot representative points of each visual gloss on a two-dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ ) in advance, and smooth this. A curve l obtained by connecting the lines is determined, and the glossiness of any object to be measured is classified by a straight line m that is orthogonal to the curve l and divides the representative points according to their visual glossiness. The above objectives have been achieved. Further, the present invention, as shown by the broken line in FIG.
Furthermore, the glossiness of an arbitrary object to be measured is determined by a curve l from a reference point R on the curve l of a foot Q of a perpendicular line drawn from a point P on the two-dimensional plane of the object to the curve l. The above objective was also achieved by evaluating the distance along the . Further, in the embodiment of the present invention, the representative point of each visual gloss level is used as the center of gravity, so that an appropriate representative point can be easily determined.

[Effect]

The present invention was made based on the fact that the visual gloss of the surface of an object, such as a steel plate, depends on two surface roughness parameters: the average roughness and the average peak interval, and cannot be evaluated based on the average roughness alone. . That is, surface roughness is the main factor that determines the gloss of objects of substantially the same color, and it is basically considered that the degree of gloss can be evaluated by accurately grasping information on the surface roughness. Information on surface roughness can be roughly expressed by the variance σ of the height distribution of the surface profile and the autocorrelation distance T (distance at which the autocorrelation function is 1/e), and these quantities and the light reflection intensity The distribution includes e.g.
Published by Pergamon Press, P. Beckmann
and “The Scattering of
Electromagnetic Waves from Rough
There is a certain relationship as shown in ``Surfaces''.Furthermore, the results of detailed examination of these relationships by Yuichiro Asano et al. Accordingly, by satisfying each range of equations (1) and (2) above, the specular reflection intensities I ₁ and I ₂ under each condition have a relationship with the roughness parameters σ and T as shown in the following equation. I ₁ = f ₁ (σ) ... (3) I ₂ = f ₂ (σ, T) ... (4) However, the incident light intensity is set as unit intensity and the total reflectance is set as 1. Here, if the total reflectance is taken into account, the above (3),
The left side of equation (4) is I ₁ /S ₁ and I ₂ /S ₂ (S ₁ and S ₂ are
(1) and (2) (total reflection intensity under each condition), and the information on the roughness parameters σ and T is I ₁ /
It is definitely included in both S ₁ and I ₂ /S ₂ information. Therefore, the glossiness is determined by both information of I ₁ /S ₁ and I ₂ /S ₂ and can be quantified. On the other hand, if we consider a large number of samples of the same type of material but with different visual gloss levels, if we plot them on the two-dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ ), these samples will become For example, as shown in FIG. 2, in many cases, the particles are continuously distributed along a certain curve 1 on the two-dimensional plane depending on the gloss level. In FIG. 2, O is a sample with a visual gloss level of 1, ▲ is a sample with a visual gloss level of 2, and □ is a sample with a visual gloss level of 1.
Samples with visual gloss level 3 are shown. Therefore, the glossiness of these samples can be expressed as (I ₁ /
When classifying on the two-dimensional surface of S ₁ , I ₂ /S ₂ ), it is appropriate and simple to classify using a straight line m perpendicular to the curve l, as shown in FIG. The inventor considered the following method as a method for performing this classification more generally. That is, by plotting the representative points of each visual gloss on a two-dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ ) and smoothly connecting them, a curve l is obtained.
is determined, for example, by drawing on a drawing. Next, the glossiness of an arbitrary sample is determined by the distance along the curve l from the reference point R on the curve l of the foot Q of the perpendicular line drawn from the point P to the curve l on the two-dimensional plane of the sample (or (amount equivalent to). FIG. 4 shows the simplest example in which sample points are classified according to visual gloss levels 1, 2, and 3, and FIG. 5 shows an example in which these visual gloss levels are evaluated in more detail.

【Example】

Examples in which the glossiness of a stainless steel plate was evaluated according to the present invention will be described in detail below. This embodiment aims to replace the conventional visual determination of glossiness (4 levels of glossiness 1 to 4) with automatic determination by measuring the light reflection intensities I ₁ and I ₂ . This was done to test performance. The surface roughness parameter σ of the stainless steel plate treated here is 0.02 to 0.2 μm, and if an Ar laser beam of λ = 0.457 μm is used as the luminous flux, the incident angle θ = 75°, and the equation (1) above is used. can be satisfied,
Furthermore, the above equation (2) can be satisfied when the incident angle θ=10°. In addition, in the case of stainless steel plates handled here,
The total reflectance is almost constant and is used for gloss evaluation.
The dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ ) is equivalent to (I ₁ , I ₂ ). FIG. 6 shows the results of determination according to this example.
Each sample has a gloss level of 1 to 1 based on visual judgment by multiple skilled judges in comparison with standard samples.
It was classified into four stages. In Figure 6, 〇,
▲, □, and ● indicate samples with gloss levels of 1, 2, 3, and 4, respectively. On the other hand, for these samples, the specular reflection intensities I ₁ and I ₂ were measured, and for the samples belonging to each gloss level, the representative points (I ₁ , I ₂ ) on the two-dimensional plane (in this example, the center of gravity) were measured. ) After determining _C1 to _C4 , they were smoothly connected on the drawing to draw a curve l. next,
So that samples are classified by each gloss level,
Appropriate boundary lines ma perpendicular to the curve l, respectively;
mb and mc were determined. A practical method for determining these boundary lines ma, mb, and mc is, for example, by plotting a large number of sample points and determining the boundaries so that the number of false positive points for each adjacent group is minimized. As a result of automatically judging a large number of stainless steel plate samples using the judgment method determined in the above procedure, we were able to correctly judge approximately 97% of the samples.
It was confirmed that it had sufficient performance. In addition, as a method for more finely determining the glossiness, the glossiness of each of the representative points C ₁ , C ₂ , C ₃ , and C ₄ is set to 1.0,
2.0, 3.0, and 4.0, and the glossiness of each point is one reference point Rs, the intersection Ta of the curve l and the boundary point ma, the intersection Tb with the boundary line mb, the intersection Tc with the boundary line mc, and the other reference point Re. are respectively 0.5, 1.5, 2.5, 3.5, and 4.5,
Furthermore, the glossiness of any point on the curve l is determined by the curve l within each interval (0.5-1.0, 1.0-1.5,...4.0-4.5).
_The glossiness of any sample is defined as _the value proportionally interpolated along It can be defined as the gloss level of the point. According to this method, analog glossiness determination is possible. In the above embodiment, the present invention was applied to the evaluation of the glossiness of a stainless steel plate, but the scope of application of the present invention is not limited to this, and it can be similarly applied to the determination of the glossiness of the surface of a general object. it is obvious.

【Effect of the invention】

As explained above, according to the present invention, for objects of the same color (brightness may differ), the visual glossiness matches well and can be quantified over a wide roughness range from boundary surfaces to rough surfaces. It becomes possible to determine the gloss level. Therefore, it is possible to measure and manage the surface quality online, which has excellent practical effects such as prevention of defects.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the gist of the method for determining the glossiness of an object surface according to the present invention, and FIG. 2 is a two-dimensional plane (I ₁ /S ₁ , I ₂ /
S ₂ ) A diagram showing an example of the distribution of samples on the top, Figure 3 is also a two-dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ )
FIG. 4 is a diagram showing an example of the above curve l and straight line m, FIG. 4 is a diagram showing the simplest example of classifying sample points according to the present invention, and FIG. FIG. 6 is a diagram showing an example of a more detailed evaluation of glossiness. FIG. 6 is a diagram showing the determination results of an example in which the present invention was applied to evaluate the glossiness of a stainless steel plate. σ...Dispersion, _λ1 , _λ2 ...Wavelength, _θ1 , _θ2 ...Incidence angle, _I1 , _I2 ...Specular reflection intensity, _S1 , _S2 ...Total reflection intensity, l...Curve , m, ma, mb, mc...straight line,
P...point, Q...leg of perpendicular line, R, Rs, Re...reference point, _C1 to _C4 ...representative point.

Claims (1)

[Claims] 1. In a method for determining the glossiness of an object surface, which classifies and ranks the glossiness based on the visual perception based on the light reflection intensity distribution on the surface of the object, the dispersion σ of the height distribution of the surface profile to be measured is ^The wavelengths λ ₁ ^and _{λ 2} ( _{λ 1 = λ 2 are} also ), the incident angles θ ₁ and θ ₂ are set, and two light fluxes with wavelengths λ ₁ and λ ₂ are projected at the incident angles θ ₁ and θ ₂ , and the specular reflection intensities I ₁ and I ₂ and total reflection are respectively Strength S ₁ , S ₂
, plot the representative points of each visual gloss on a two-dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ ) in advance, and define a curve l obtained by smoothly connecting these points. A method for determining the glossiness of an object surface, comprising classifying the glossiness of an arbitrary object to be measured using a straight line m that is perpendicular to the curve l and divides the representative points according to their visual glossiness. . 2. The method for determining the glossiness of an object surface according to claim 1, wherein the representative point of each visual glossiness is the center of gravity. 3 In an object surface gloss determination method that classifies and ranks the glossiness based on visual perception based on the light reflection intensity distribution of the object surface, the variance σ of the height distribution of the measured surface profile is expressed by the following equation {( 4πσ/λ ₁ )・cosθ ₁ } ² ≦1 {(4πσ/λ ₂ )・cosθ ₂ } ² ≧4 The wavelengths λ ₁ and λ ₂ (including λ ₁ = λ ₂ ) and the incident angle θ are ₁ and θ ₂ are set, two light beams with wavelengths λ ₁ and λ ₂ are projected at incident angles θ ₁ and θ ₂ , and the specular reflection intensities I ₁ and I ₂ and total reflection intensities S ₁ and S ₂ are respectively
, plot the representative points of each visual gloss on a two-dimensional plane (I ₁ /S ₁ , I ₂ /S ₂ ) in advance, and define a curve l obtained by smoothly connecting these points. The glossiness of an arbitrary object to be measured is determined by measuring the glossiness of a perpendicular line Q drawn from the point P on the two-dimensional plane of the object to the curve 1 along the curve 1 from the reference point R on the curve 1. A method for determining glossiness of an object surface, characterized in that evaluation is performed based on the distance between objects.