JPH03170810A - Noncontact analyzer for measuring glossiness and smoothness - Google Patents

Abstract

PURPOSE:To improve the stability of measuring values of the glossiness by operating the glossiness of an object to be measured on the assumption that the scattering light has a regular distribution, obtaining the change of the glossiness in a relative narrow range and calculating a unevenness of the glossiness based on a specific formula. CONSTITUTION:A P polarized light is made incident upon a sheet-like object to be measured at an angle of incidence deflecting from the Brewster angle. A condenser lens is set on an optical axis of the reflecting light within a plane including an optical axis of the incident light and a normal line, with a photodetector provided at the focal position of the lens. The scattered light reflected at the surface of the object is received by the photodetector. Supposing that the received scattered light is a regular distribution, the glossiness is obtained in an operating part on the basis of an arithmetic expression of 'PXD' from a peak P and a half width value D of the distribution. Moreover, the change of the glossiness in a relatively narrow range is obtained in the operating part, thereby obtaining the unevenness of the glossiness based on a predetermined formula with the peak light at the surface of the strong gloss being rendered Pmax, and that at the surface of the weak gloss rendered Pmin. Accordingly, it becomes possible to obtain a stable measuring result without influences of the very minute change of the glossiness without the need of complicated operations.

Description

[Detailed description of the invention] Industrial application field> The present invention is applicable to a sheet-like object to be measured, such as paper (hereinafter referred to as "paper").
This is a non-contact analyzer that can measure the glossiness and smoothness of the surface of objects (such as objects to be measured) simultaneously online. BACKGROUND ART A conventional technique is defined in JISP8119 as a method for detecting paper smoothness (Bekk method). FIG. 8 is a diagram showing the principle of the Bekk method. In FIG. 8, the object S to be measured is a pressure vessel 1 with a lid.
It is held between the lid 1a of the container 1 and the container 1. In this state, during measurement, the air in the inner chamber 1b is pulled to a specified negative pressure by the pump 2, and the pressure gauge 3 measures the pressure in the container until it reaches a certain negative pressure (380 → 360 ln Hg). The time is measured. At this time, if the surface of the object to be measured S is rough, air leaks into the inner chamber 1b along the plane of the paper, so that the time required to reach the specified pressure is short. On the other hand, if the surface of the object to be measured S is smooth, air leaks into the inner chamber 1b along the paper surface, so it takes a long time to reach the specified pressure. Therefore, the smoothness of the object to be measured S can be measured from the measurement time difference. If the surface of the object to be measured S is smooth, better printing can be performed. Therefore, this smoothness is considered important during printing. By the way, paper, which is the object to be measured in the papermaking process,
It is conveyed sequentially while being pressurized by rolls, and the smoothness is measured during this moving state. On the other hand, in the measurement method shown in Figure 8, a sample is cut out and placed on a test device. Furthermore, it generally cannot be used online in paper-making processes, etc. because it takes time to measure. An example of this type of device that can be used online is an optical smoothness meter as shown in USP 4.019.066. Figure 9 is a diagram showing the principle structure of an optical smoothness meter, which is a conventional well-known technology. In FIG. 9, a light source 4 irradiates a sheet-shaped object S to be measured with irradiation light. The reflected light from the object to be measured S is collected by a collector 5 and then detected by a light receiver 6. At this time, since the reflected light is dispersed according to the smoothness of the surface of the object S to be measured, the degree of smoothness of the object S to be measured can be determined by measuring the spread of this dispersion. However, although this device is capable of online measurement in which measurements can be taken without contacting the object S to be measured, there is a problem in that the measurement results do not correlate well with printability compared to the Bekk method. Therefore, in order to solve this problem, the applicant of the present application proposed Utility Model Application No. 63-9174 as a technology that has a good correlation with printing suitability and is capable of online measurement.
I proposed No. 4. The structure consists of a means for making the P-polarized light incident on the object to be measured at an incident angle deviated from the Brewster's angle, and a means for making the P-polarized light incident on the object to be measured at an incident angle deviated from the Brewster's angle. The device is equipped with a condenser lens and a photodetector element arranged at the focal point of the condenser lens so that the measurement surface of the object to be measured is perpendicular to the reflected optical axis. And the measurement is
The light detection element receives the specular reflection component reflected by the surface to be measured and the diffuse reflection component reflected inside the object to be measured, and detects the diffused light (with a peak formed on the surface to be measured).
The smoothness and glossiness of the object to be measured can be determined from the cone-shaped spread of light. We confirmed this device through experiments. The measurement result of the smoothness of the object to be measured has a good correlation with the measurement result of the Bekk method when information on the surface smoothness and information on the internal structure of the object is added, and has a good correlation with the printability. At this time, P-polarized light is used as the measurement light, and a part of it is incident inside the object to be measured.
The diffuse reflection component reflected inside the area is used for measurement along with the specular reflection component. The inside of the object to be measured is an aggregate of cellulose. When a large amount of cellulose is contained, the internal structure is dense and the diffuse reflection component increases, and conversely, when the internal structure is rough, the diffuse reflection component decreases. Therefore, the photodetecting element detects the spread of the diffused light formed on the measurement surface by receiving both the specular reflection component and the diffuse reflection component. This is the first thing
The explanation will be made using the principle configuration diagram of an analyzer for non-contact measurement of gloss and smoothness shown in FIG. 0, and the diagrams used for explanation of FIGS.

In FIG. 10, reference numeral H designates a detection head that reciprocates over the object S to be measured in its width direction. Code 8 is light source 7
It is a collimating lens that converts the light from the lens into a thousand lines of light. Reference numeral 9 denotes a polarizer disposed above the incident optical axis A so as to project light only in the P direction. Reference numeral A2 is a reflection optical axis passing through a plane including the incident optical axis A1 and the normal line N. The symbol R is the specular reflection from the surface of the object to be measured. The code R2 is
This is a certain amount of diffuse reflection from inside the object being measured. The code 11 is
For example, a C.C.I. This is a photodetection element (line sensor) consisting of a D array sensor or the like.

FIG. 11 shows the reflected light intensity Am when the Pl light is incident on the object to be measured at an incident angle φ. At this time, for example, if the object to be measured is paper, as shown in the figure, when the PI light is incident at an angle of 75 degrees deviated from Brewster's angle, and the refractive index of the paper is 1.52, regular reflection from the paper surface will occur. It can be seen that a certain amount is about 10%, and the remaining 90% goes inside the paper. Paper is an aggregate of cellulose inside, but in this case, if there is a lot of cellulose and the fibers are fine, the inner M#I
If the internal structure is dense, the amount of diffuse reflection will increase, while if the internal structure is coarse, the amount of diffuse reflection will decrease. Returning to FIG. 10, the explanation will be continued.

The specular reflection component R from the surface of the object to be measured and the diffuse reflection component R2 from inside the object are mixed and applied to the condenser lens 10. This result is based on the measurement surface 11 of the line sensor 11.
．． Above, a light pattern L1 having a peak and a spread as shown in FIG. 12 is formed. The smoothness at this time is
For example, in Fig. 12, measure the width of the spread of light (hereinafter referred to as "half-value width") D at half * (Ap/2) of the peak value (expressed by the peak voltage of scattered light) Ap, and use this half-value width D. demand. Figure 13 shows a comparison between the measurement results using the Bekk method described above and the smoothness measurement results using the analyzer that measures gloss and smoothness in a non-contact manner as shown in Figure 10, using the same sample. be. In FIG. 13, the vertical axis represents the Bekk value of the sample, and the horizontal axis represents the degree of dispersion DjS per unit basis weight. At this time, the degree of dispersion I)ts is obtained by dividing the peak value Ap by the voltage corresponding to the half-value width D, and further dividing by the voltage corresponding to the basis weight BW of the sample, DLs = K (Ap / (
It is expressed as D-Bw ) ) - (1). In the experiment, a plurality of sample papers whose Bekk values were previously measured using the Bekk method were used, and the smoothness was measured using an analyzer that measures gloss and smoothness in a non-contact manner as shown in Figure 10. The measurement results are printed approximately on the straight line l.
By the way, the light pattern shown in FIG. 12 is used to measure the smoothness as described above, but on the other hand, the peak value (peak voltage) A of the scattered light reflected from the object to be measured is
Since p is mainly due to the specular reflection component, the glossiness of the object to be measured can also be measured from this peak value. In other words, by using the peak value Ap, it is possible to form a unique system for measuring glossiness while using an analyzer that measures glossiness and smoothness in a non-contact manner (hereinafter, this component will be described). (herein referred to as "P gloss meter").
In other words, an analyzer that measures gloss and smoothness in a non-contact manner in addition to the part that measures smoothness will be subject to #I. Problems to be Solved by the Invention By the way, when used as a gloss meter, there were the following problems. Figure 14 (A). (B) to FIG. 15 are diagrams for explaining the problems of the device shown in FIG. 10, and in particular, FIG. 14 (A
) is a P gloss meter showing the object to be measured, scattered light, and its detection part in Figure 10, and Figure 14 (B) is the same figure (A>
15 is a diagram for explaining these well-known laboratory gloss meters, showing the parts corresponding to the P gloss meter shown in FIG. In FIG. 14(B), the symbol A+- is the incident optical axis. The symbols R and - are specular reflection components from the surface of the object to be measured, and the symbol A2- is a reflection optical axis passing within a plane containing the incident optical axis A1 and the normal N. Reference numeral 100 indicates the reflection optical axis A2-
This is a lens placed on the top that focuses reflected light (scattered light). Reference numeral 12 is a circular aperture. Reference numeral 13 is a photodetecting element provided on the reflected light 1t[I A 2.
The reference numeral Q- indicates scattered light which is reflected light (incidentally, the scattered light in Fig. 14 is represented by Q). The problems are explained below. Figure 14 (A). In (B), the gloss is determined from the peak value Ap using the P gloss meter as described above. That is, the laboratory gloss value obtained with the P gloss meter is obtained by taking the peak value Ap of the waveform in FIG. 15 and calculating it in a calculation section (not shown). On the other hand, in the laboratory gloss meter, the scattered light Q" from the object to be measured S is collected by a lens 100, passed through a specified aperture 12, detected by a photodetector element 13, and a calculation unit (not shown) The glossiness is determined by calculating the integral value.In other words, the measured value obtained with the lab glossmeter (lab glossiness value) is rotated around the Z axis in the shaded area in Figure 15. is the volume value (integral value of luminous flux) when

Due to differences in such measurement and calculation processes,
In the laboratory gloss meter, the fine gloss culture in the extreme areas does not appear noticeably, whereas in the P gloss meter, the sensitivity is more sensitive than necessary in order to capture minute changes in the gloss in the extreme areas. becomes. In other words, the P gloss meter appears to have poor apparent stability compared to the lab gloss values. In other words, P
Due to its construction, the gloss meter is designed to measure both gloss and smoothness at the same time, so it requires a peak value A2 as well as a half-width D, and for this reason, as described above, it is used as a detector. This is because a line-shaped linear array sensor is used. In other words, as a result of using a linear linear array sensor, it is not possible to receive all of the circular light flux like a laboratory gloss meter. The present invention has been made in view of the above-mentioned problems of the conventional technology, and its purpose is to improve gloss and smoothness in a non-contact manner using a linear linear array sensor. At least improve the stability of glossiness measurements by effectively utilizing the measured peak values and half-widths using a measuring analyzer, and by correlating them with the lab glossmeter measurements. The purpose is to provide an analyzer that measures gloss and smoothness in a non-contact manner. or,
If necessary, it is a non-contact method that can detect variations in gloss or smoothness of the object to be measured by detecting changes in gloss from the object in a relatively narrow range or from the obtained smoothness. The purpose of this project is to provide an analyzer for measuring smoothness and smoothness. Means for Solving the Problems> In order to achieve the above objects, the non-contact type analyzer of the present invention for measuring glossiness and smoothness measures a sheet-like object to be measured at an incident angle deviated from Brewster's angle. means for making the P@ light incident on an object; a condenser lens provided on a reflection optical axis passing within a plane including the incident optical axis and normal line of the P-polarized light; and a measurement surface at the focal position of the condenser lens. The glossiness and smoothness of the object to be measured are determined from a light detection element arranged perpendicular to the reflected optical axis and a detection signal based on the scattered light received by the light detection element and reflected from the surface of the object to be measured. (a) The glossiness of the object to be measured is determined by the calculation section, which calculates the scattered light with a normal distribution. This is characterized in that it is obtained by calculating based on the arithmetic expression "P×D" from the peak (P) and half-width (.D) of the normal distribution when assumed. (b) If necessary, the degree of unevenness in glossiness of the object to be measured is calculated by capturing the change in glossiness from the object to be measured in a relatively narrow range in the calculating section, and determining the level of unevenness in glossiness of the object to be measured, by determining the level of unevenness in glossiness of the object to be measured. When the light is Ptaχ and the peak light on the weakly glossy surface is Pmju, (Pmaχ+
PmLu )/(Pmax P'1tt u ), and if necessary, the unevenness of the smoothness of the object to be measured can be relatively reduced in the calculation section. By capturing the change in smoothness from the object to be measured in a narrow range, the calculated value of the peak light and half-value width on a surface with high smoothness <D/P) is calculated as (D/P)ma.
x, the calculated value of the peak light and half-width on a surface with low smoothness is (D/P) t i TL, ((D
/P) negative ax+ (D/P)mc TL )/( (D
/Plta'x(D/P)mtTL).

Function> The present invention uses a linear linear array sensor to receive scattered light from an object to be measured, and is a non-contact method capable of obtaining values based on a peak value and half-width. In an analyzer that measures the intensity, the scattered light received by the linear array sensor is separated into the peak light and the scattered width, that is, the half-width, and independent output signals are obtained for each, and these signal values are multiplied. Stability is improved by correlating the obtained glossiness (smoothness can be determined by dividing the peak light by the half width) with the glossiness obtained with a laboratory glossmeter.

Example Examples will be described with reference to the drawings.

FIG. 1 is a diagram for explaining the present invention.

In this Figure 1, the vertical axis is the value "unit voltage (V)" obtained by multiplying the peak value (P) as a measured value by the half-width value (D), and the horizontal axis is the laboratory gloss level (JIS). Specified display, Gs
(75°) χ%”, the correlation characteristic (VOCP×
D) From this result, the correlation coefficient is higher when the glossiness is correlated as P x D than when it is correlated with the lab glossiness using only the peak light as in the past. , in the fifth factor, black circles indicate measurement points for paper belonging to brand A, and white circles indicate measurement points for paper belonging to brand iG, respectively. As can be seen from this, it can be seen that there is a correlation between the gloss levels of different brands of paper.

FIGS. 2 to 6 are diagrams for explaining the present invention. In the following explanation, the above drawings will be used as appropriate. Assuming that the scattered light that is the reflected light from the object to be measured S has a normal distribution as shown in FIG. 2, V-{1/(2π) l/2 ) exp(-(χ2 /2 ) } -(2).However, ν is the peak direction (vertical axis direction) when the scattered light is normally distributed, and χ is the horizontal axis when the scattered light is normally distributed. direction (scattering width direction).

In the normal distribution that can be expressed in this way, the lab glossiness that can be determined with a lab gloss meter, that is, the body M when ABOCD rotates around the υ axis (J I S
The glossiness (light amount) is: ■=πχ+”J+πf
)2dυ ... (3) J'. However, yO is the peak value on the y-axis, χ is the half value @ value at that time, y is the V of this half value width
Value on axis. Here, when χ is expressed as a function of y, χ=(In7/(2π) I/2 } 1/2
...(4), so the second right-hand side of equation (3)
The term is
I/2) I/2 Co'd ybu? Become. On the other hand, since yO is the value at χ-0 in equation (2), '! /o = (1/ (2π) V2)exp (
- (02/2)) =1/(2π}1l2...
(6), and 'y1 is '! l, = (1/ (2π) 1/2)expf
−(χ12/2)} (7). Substituting these equations (6) and (7) into equation [5], πf f(y)
2dy = -2rr [ (1/ (2g) 1/2) ■ lTL
(1/e) - (1/(2π)"") ・ (lT
L (1/e }・exp(-(χ12/2)) =-2π [-{1/('2π) l/2 1 +(
1/(2π) I/2} exp(-(χ,'/2)) {(χ+2/2
)+1)] = {2π/(2π}V2} [1-exp(1(χ12/ 2 ) 1{(χ12
/2)+1)]...(8). Here, {2π/
Assuming <<2π)I/2}: fi, this equation (8) can be transformed into (3)
Substitute it into the second term on the right side of the equation, and then add (7
) When substituting the equational relationship, V=-rZ1' (
1/ (2g)"1exp{-(χ,'/2))+ft ・[1-exp{-(χ+'/F)){(
χ+2/2)+111 =1 [1-exp ((χ1'/2)11-
(9) is obtained. After all, this corresponds to the volume of a rotating body with a normal distribution of "0≦χ≦■". Figure 3 shows the normal distribution within the specified width χA (±χA ) shows changes in area (changes in volume). This figure 3 shows that when the normal distribution changes as the peak (y height) increases or decreases, as shown in figure 4, the specified gap (2 to 1 Z
This is the same as changing the area ratio of 2 and -2 toward the center. Based on the relationship between the peak and the volume when the reflected light is normally distributed, if the reflected light is normally distributed, the light distribution is normal even if its relative value changes, so it is included in the diagonal line in Figure 3. The area is a standard normal distribution ■
It is obtained by integrating V in the equation with respect to χ, and the volume of the rotating body corresponds to the laboratory glossiness value due to peak light change. Therefore, the reflected light is obtained by multiplying the normal distribution in equation (2) by the coefficient for changing the mountain height (i.e., the peak value P) ν=P・(1/(2π) I72 )exp(−(χ
2/2)}...0■. By the way, equation (9) is the peak intensity when measuring with a lab gloss meter, assuming that the reflected light has a normal distribution and that the change in the V-axis direction is proportional to the peak light intensity P. It represents the standard normal distribution volume when fixed (when set to 1). Therefore, the value obtained by multiplying equation (9) by P, V=P-It [1-
expl-(χ2/2)1]...01) is a general formula that indicates the volume of reflected light. This means that the volume V is a function of the peak intensity P and the scattering width direction χ. Figure 5 shows the rotation around the V-axis of the standard normal distribution, with P in the aT) equation set to 1, the x-axis of the standard normal distribution on the horizontal axis, and the volume V on the vertical axis. This is a graph of volume changes in the half-width direction. At this time, when the object to be measured is a specular object, all of the reflected light enters within the receiving aperture angle of the aperture 12 of the laboratory gloss meter, so the characteristic in the χ axis direction approaches ■. In addition, when the surface of the object to be measured is rough, the reflected light has a large degree of scattered light, so not much of the light flux falls within the specified acceptance angle of the aperture 12 of the laboratory gloss meter, and therefore χ- It means that the volume decreases as it shifts to the direction of 0 (the side where χ is close to zero).Also, the increase or decrease of the peak light does not change the shape of the normal heather, but only its ratio changes.Therefore, Since the vertical axis in Figure 5 can be seen as the lab gloss meter and the horizontal axis as the gloss of the P gloss meter, the correlation between the lab gloss meter and the P gloss meter can be seen to be curved in the high gloss range. Figure 6 shows the laboratory gloss meter and P when the reflected light is normally distributed.
This is a diagram in which the correlation of the gloss meter is calculated and plotted. In this figure, the integral at the half-width position of the normal distribution is 1/2 of the total volume (the area is 76.2%). occupy)
．． Therefore, if the shape of the quasi-normal distribution is proportional to the peak (χ = O), the value multiplied by the peak (P) and the half-width (D) is always 1/2 of the volume of the standard normal distribution, and the laboratory It is proportional to the glossiness (provided that all the reflected light flux from the object to be measured is included within the opening angle of the laboratory glossmeter). By the way, the analyzer that measures gloss and smoothness in a non-contact manner can obtain the half-width and peak value as described above.
Using the obtained peak value and half-value width, it is possible to calculate the glossiness (that is, the size of the scattered light) that approximates the volume of the laboratory glossmeter. That is, the magnitude of the received scattered light can be expressed approximately by multiplying the peak light intensity P by the half value @D, and by approximating the volume V determined by a laboratory gloss meter. Vo
c P x D − (1
2) This is the value obtained as the glossiness value.

By the way, in the gloss measurement described above, it is also possible to measure "unevenness in gloss" using only the peak light. FIG. 7 is a diagram for explaining another embodiment of the present invention.

In FIG. 7, the peak light is more sensitive to changes in gloss than a lab gloss meter, so it captures changes in gloss from the object S in a relatively narrow range, and (Pmaχ+PmL
TL ) / (Ptaχ Pat TL )・・−(1
3) The magnitude of the uneven glossiness of the object S to be measured can be calculated and detected as follows. However, Ptaχ is the peak light on the surface sA with high gloss, and P1ltTL is the peak light on the surface SB with low gloss. Incidentally, unevenness in smoothness can be determined from equation (4) in the same manner as described above.

( (D/P)tax+ (D/P)xLu }/((
D/P) tax (D/PluLul"f14) Effects of the Invention> Since the present invention is constructed as described above, it produces the following effects.

The glossiness and smoothness of the object to be measured can be simultaneously measured by the first device from the peak output and half-width output detected by the line sensor, and the unevenness of the glossiness of the object to be measured can also be measured from the glossiness. The gloss level can only be used for peak light! 11, it is possible to perform more sensitive measurements than with a laboratory gloss meter, and it is also possible to measure the unevenness of the gloss of the object to be measured, and the gloss can be determined by multiplying the peak output and the half-width output. The calculation result at this time has a very high correlation coefficient in relation to the glossiness obtained with the laboratory glossmeter, so there is no need to perform complicated calculations, and the glossiness result from this calculation is , it is possible to obtain stable measurement results, that is, measurement results that are not affected by minute changes in gloss.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention, FIGS. 2 to 6 are diagrams for explaining the present invention, FIG. 7 is a diagram for explaining other embodiments of the present invention, and FIG. 8 is a diagram for explaining the present invention. A diagram showing the principle of the kk method, Figure 9 is a diagram showing the principle configuration of an analyzer that measures optical smoothness, which is a conventional well-known technique, and Figure 10 shows an analyzer that measures gloss and smoothness using a non-contact method. FIGS. 11 to 13 are diagrams used to explain FIG. 10, and FIGS. 14 to 15 are diagrams used to explain problems with the apparatus shown in FIG. H...Detection head, S...Measurement object, 7...Light source, 8...Collimating lens, 9...Polarizer, 10...
... Condensing lens, 11... Photodetection element (line sensor). Figure 7 Figure 6 Figure 9 Figure 10 Figure S Foil 1 1 Figure 12 Figure l3 Figure

Claims (3)

[Claims] (1) A means for making P-polarized light incident on a sheet-like object at an incident angle deviated from Brewster's angle, provided on a reflection optical axis passing within a plane including the incident optical axis and normal line of the P-polarized light. a condenser lens, a photodetection element disposed at the focal position of the condenser lens so that the measurement surface is perpendicular to the reflected optical axis, and scattered light received by the photodetection element and reflected on the surface of the object to be measured. An analyzer for measuring glossiness and smoothness of the object in a non-contact manner, which is equipped with a calculation unit capable of calculating the glossiness and smoothness of the object to be measured from a detection signal based on light. is the peak (P) and half-width (D) of the normal distribution when the scattered light is assumed to be a normal distribution in the calculation unit.
), an analyzer for measuring glossiness and smoothness in a non-contact manner, characterized in that the results are calculated based on the formula "P×D". (2) In the non-contact type analyzer for measuring glossiness and smoothness according to claim 1, the magnitude of glossiness unevenness of the object to be measured is determined in a relatively narrow range in the calculation section. When the change in glossiness from the object to be measured is taken, and the peak light on the highly glossy side is P_m_a_x and the peak light on the weakly glossy side is P_m_i_n, then (P_m_a_x+P_m_i_n)/(P_m_a_
1. An analyzer for measuring glossiness and smoothness in a non-contact manner, characterized in that glossiness and smoothness can be obtained by calculation based on an arithmetic expression consisting of x-P_m_i_n). (3) In the non-contact type analyzer for measuring glossiness and smoothness according to claim 1, the unevenness of the smoothness of the object to be measured is determined in the calculation section by measuring the unevenness of the object in a relatively narrow range. By capturing the change in smoothness from the object to be measured, calculate the calculated value of peak light and half width on a surface with high smoothness (D/P) (D/P)_m
When _a_x is the calculated value of peak light and half-width on a surface with low smoothness is (D/P)_m_i_n, {(D/P)_m_a_x+(D/P)_m_i_n}
/{(D/P)_m_a_x-(D/P)_m_i_n
} An analyzer for measuring gloss and smoothness in a non-contact manner, characterized by being able to calculate and obtain the results based on the calculation formula.