JP3095572B2 - Gloss measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glossiness measuring device, and more particularly to a glossiness measuring device capable of accurately measuring glossiness regardless of fluctuations in the moving speed of a pattern.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a glossiness measuring apparatus for quantitatively measuring the glossiness of a painted surface or the like by using a light-dark pattern having light-dark portions having different light transmittances (Japanese Patent Publication No. Sho 5).
No. 7-59490).

[0003] Such a glossiness measuring apparatus is provided with a light-dark pattern having at least one pair of a light portion and a dark portion. This light / dark pattern is mounted on a sliding table movable in a direction perpendicular to the optical axis. This sliding table is connected to a pulse motor via a reduction gear, a ball screw and the like. In addition, the device includes a lens system that irradiates the surface to be measured with light passing through the light and dark pattern. At a position where the light reflected from the surface to be measured can be received, a photoelectric conversion element that outputs an electric signal according to the intensity of the incident light is provided. A pinhole is provided on the incident side of the photoelectric conversion element, and the pinhole is provided at a position on an image plane on which the pattern is formed by the lens system. Further, the photoelectric conversion element is connected to a control unit. The control unit receives an electric signal from the photoelectric conversion element and obtains a gloss level by a method described later.

This control unit moves the light-dark pattern in the direction perpendicular to the optical axis connecting the light source and the photoelectric conversion element when measuring the glossiness. In order to move the light-dark pattern, a next open-loop control is performed. Is used.

That is, first, in order to drive the sliding table on which the light / dark pattern 16 is mounted, the control section periodically outputs a pulse to the pulse motor. The pulse motor that receives the pulse is driven accordingly to move the sliding table via a reduction gear, a ball screw, and the like. Thereby, the light and dark pattern moves in the direction perpendicular to the optical axis.

The light-dark pattern moves as described above, and the light-dark boundary portion of the light-dark pattern image passes over the pinhole. Accordingly, the light intensity of the projected image of the light and dark pattern passing over the pinhole changes, and an electric signal corresponding to the change in the light intensity is output from the photoelectric conversion element to the control unit.

Here, the blur at the boundary between light and dark in the light and dark pattern image formed via the surface to be measured, that is, the relationship between the sharpness and the glossiness of the surface to be measured, is determined when the surface to be measured has low gloss. It has been confirmed by an experiment that the blur at the boundary is large and the blur at the light-dark boundary is small when the gloss is high. Further, the tangent gradient of a curve that changes from a dark portion to a bright portion of the light intensity obtained by moving the light-dark pattern has a correlation with the glossy sensory value (visibility) of the measured surface, which is statistically obtained. It has also been experimentally confirmed that the maximum value of the tangent gradient of, that is, the maximum value of the differential value of the light intensity corresponds to the glossiness of the surface to be measured.

Therefore, the light intensity of the light-dark pattern image accompanying the movement of the light-dark boundary is detected based on the electric signal, and the light intensity curve obtained by moving the light-dark pattern is used to calculate the maximum value of the differential value of the light intensity. The value is determined and the gloss is determined.

Further, since the maximum value of the differential value of the light intensity is the glossiness, the glossiness can also be obtained from the maximum value of the change rate of the light intensity obtained from the following equation (1).

[0010]

(Equation 1) The position of the light-dark pattern where the change rate of the light intensity is maximum is the position of the light-dark pattern where the tangent gradient of the light intensity curve is maximum.

In the above equation (1), the increment of the distance means a distance by which the light and dark pattern moves by one pulse. In the conventional gloss measuring device, only the light intensity is detected without detecting the distance of the light and dark pattern moved by one pulse. Then, when calculating the light intensity, the increment of the light intensity is calculated for each pulse, divided by the distance that the light-dark pattern moves in one pulse, the change rate of the light intensity is calculated, and the maximum value is defined as the gloss. I have. Therefore, it is assumed that the moving distance of the light / dark pattern for one pulse is always constant.

[0012]

However, if the reduction gear as a transmission mechanism from the pulse motor to the sliding table has an eccentricity and a fluctuation in the ball screw, etc., the influence is given as shown in FIG. Then, the moving speed of the light and dark pattern fluctuates. The moving speed of the light-dark pattern differs depending on the position of each light-dark pattern 16, and changes periodically when focusing on the same point. This is the eccentricity of the reduction gear,
This is because the influence of the fluctuation of the ball screw is transmitted to the sliding table, and accordingly, the moving speed of the light and dark pattern periodically changes.

As described above, when the moving speed of the light and dark pattern fluctuates, the moving distance of the light and dark pattern for one pulse also fluctuates. Therefore, the increment of the distance of the light and dark pattern, which is the denominator of Equation 1, fluctuates. Therefore, since the conventional glossiness measuring device detects only the light intensity for each pulse, the obtained glossiness value differs from the original glossiness value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a glossiness measuring apparatus capable of measuring glossiness accurately regardless of fluctuations in the moving speed of a light-dark pattern. I do.

[0015]

Means for Solving the Problems The present invention has been made to achieve the above-mentioned object, and a gloss measuring apparatus is provided.
A light source, a pattern including at least one pair of portions having different light transmittances, a projection unit configured to project light radiated by the light source and passing through the pattern onto a surface to be measured, and to form an image of the pattern; and a projection unit. A photoelectric conversion unit that is disposed at a position where the image of the pattern is formed and converts the light intensity of the reflected light from the surface to be measured into an electric signal, and the light of the light incident on the pattern Pattern moving means for moving the pattern in a direction orthogonal to the axis and in which the light transmittance of the pattern changes, light intensity reflected on the surface to be measured based on an electric signal input from the photoelectric conversion means Calculating means for determining the maximum value of the rate of change or differential value of the pattern and correcting the variation of the maximum value caused by the variation of the moving speed of the pattern.

[0016]

The gloss measuring device of the present invention has a light source. The light source illuminates the pattern, and the pattern includes at least one pair of portions having different light transmittances.
The pattern moving means moves the pattern in a direction perpendicular to an optical axis of light incident on the pattern and in a direction in which light transmittance of the pattern changes. The projection unit projects the light that has passed through the pattern onto the surface to be measured and forms an image of the pattern. A photoelectric conversion unit is provided at an image forming position of the projection unit. The photoelectric conversion unit converts the light intensity of the reflected light from the surface to be measured into an electric signal. The calculating means obtains the rate of change of the light intensity or the maximum value of the differential value based on the electric signal and corrects the fluctuation of the maximum value caused by the fluctuation of the moving speed of the pattern.

As described above, the change rate of the light intensity or the maximum value of the differential value of the light intensity obtained by moving the light-dark pattern changing from the dark part to the light part is obtained, and the light intensity is generated by the fluctuation of the moving speed of the pattern. Since the fluctuation of the maximum value is corrected, the obtained glossiness is accurate regardless of the fluctuation of the moving speed of the light and dark pattern.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 5 is a schematic view showing a first embodiment of the glossiness measuring device 10 of the present invention.

As shown in FIG. 5, the optical section of the gloss measuring device 10 of this embodiment is housed in a housing 28. The glossiness measuring device 10 includes a light source 12 connected to a power supply (not shown), and a condenser lens 14 that collects light emitted from the light source 12 is disposed near the light source 12. Note that a light emitting element such as a tungsten lamp, a halogen lamp, or an LED can be used as the light source 12.
On the exit side of the condenser lens 14, a light-dark pattern 16,
The projection lens 18 and the mirror 20 are arranged in order. As shown in FIG. 17, the light-dark pattern 16 is formed by depositing aluminum or the like on one portion of one surface of glass whose both surfaces are polished, thereby forming a pair of light-dark portions having different transmittances between the deposition surface 46 and the transmission surface. Has a part. The light-dark pattern 16 is
It is attached to a slide table (not shown) so as to be movable in a direction perpendicular to the optical axis. A pulse motor 26 is attached to the sliding table. The pulse motor 26 is connected to a slide table via a reduction gear, a ball screw, and the like. The light / dark pattern 16 is attached to a sliding table so as to move in a direction in which the transmittance changes, and the sliding table moves in a direction substantially orthogonal to the direction of light emitted from the condenser lens 14. Attached to. Also, the two ends of the sliding table in the moving axis direction are not moved beyond the movable range, that is, the pulse motors 26 are moved beyond the movable range.
Limit switch 3 to prevent the
8 is attached. This limit switch 38 is connected to a control circuit. The light emitted from the condenser lens 14 includes a light / dark pattern 16, a projection lens 18,
The light applied to the mirror 20 and reflected by the mirror 20 is applied to the surface 36 to be measured. A predetermined distance is maintained between the measured surface 36 and the glossiness measuring device 10 by a contact (attachment) 74.

On the reflection side of the surface 36 to be measured, a photoelectric conversion element 24 having a pinhole 22 having a hole of a predetermined diameter is formed.
Are arranged. Pinhole 22 of photoelectric conversion element 24
Is disposed at the image forming position of the projection lens 18. The reflected light from the measured surface 36 passes through the pinhole 22 and irradiates the photoelectric conversion element 24. Also, the photoelectric conversion element 24
Are connected to the control circuit 32. The control circuit 32
The pulse motor driver 30 is connected to a display device 34 for displaying glossiness and the pulse motor driver 30.
Is connected to the pulse motor 26.

The control circuit 32, as shown in FIG.
U (central processing unit) 52, ROM (read only memory) 54, RAM (random access memory) 5
6. A correction value ROM 55 for storing a correction value for correcting a maximum value change rate of a change rate of light intensity reflected on the surface to be measured caused by a change in the moving speed of the light-dark pattern 16. CPU 52, ROM 54, RAM 5
6. Each of the correction value ROMs 55 is mutually connected to the data command bus line 50 and the like so that data and commands can be input and output between them. On the other hand, the photoelectric conversion element 24 is arranged at a position where the light passing through the pinhole 22 can be received and outputs a voltage corresponding to the intensity of the received light. The photoelectric conversion element 24 is connected to an amplifier (AMP) 64 that amplifies an input voltage with a predetermined gain. The AMP 64 is a filter 6 that removes a noise component.
2 to an ADC (analog-digital converter) 60. The ADC 60 is connected to the data command bus line 50, and converts an analog signal proportional to the light intensity applied to the photoelectric conversion element 24 into a digital signal. The display device 34 is connected to the data command bus line 50, and the obtained gloss value is displayed on the display device 34. A pulse motor driver 30 for transmitting a drive signal to the pulse motor 26 is connected to the data command bus line 50. The pulse motor driver 30 corresponds to the rotation amount and the rotation direction of the input pulse motor 26. The control signal is converted into a driving signal.

Next, the correction values stored in the correction value ROM 55 will be described in detail below.

First, the principle of a correction value for correcting a change in the rate of change in light intensity caused by a change in the moving speed of the light-dark pattern 16 will be described.

For example, on a plane, a glossiness measuring device M1 in which the moving speed of the light and dark pattern is constant, and a glossiness measuring device in which the moving speed of the light and dark pattern fluctuates due to eccentricity of the reduction gear, fluctuation of the ball screw, etc. Consider a case where measurement is performed by the device M2. At this time, the positions of the light and dark patterns where the rate of change of the light intensity is maximum are Hp ₁ and Hp ₂ , respectively, and the moving speed of the light and dark pattern 16 at that time is V ₁ and Vp.
_Suppose it was ₂ .

As shown in FIG. 13, the light / dark pattern 16
Distance S₀A (moving speed V ₁) Then t₁[Se
c], B (moving speed V_Two) Then t_TwoIt took [sec]
Then the distance S₀Is obtained from the following equation (2).

[0026]

S ₀ = V ₁ · t ₁ = V ₂ · t ₂ On the other hand, since the increment of the moving distance of the light and dark pattern 16 is equal to the distance advanced within the fixed time t _{0 [sec]} , A (moving speed) V ₁ ) is obtained from the following equation (3).

[0027]

## EQU3 ## S ₁ = V ₁ · t ₀ and B (moving speed V ₂ ) is obtained from the following equation (4).

[0028]

S ₂ = V ₂ · t ₀ This S ₂ is expressed by the following equation _{5 from the} equations 2 and 3.

[0029]

Equation 5] _{S 2 = (t 1 / t} 2) · S 1 , where the gloss moving speed of the light-dark pattern 16 is measured by the gloss measuring device M2 which fluctuates V ₂ from V ₁ values G
In the position where the light intensity changes abruptly, as shown in FIG. 12, the light intensity change amounts T ₁ and T ₂ corresponding to the distances s ₁ and s ₂ advanced for a fixed time t ₀ [sec] are T ₁ ∝s ₁ , T ₂ ∝s
_Since it is _2, it is expressed by the following equation (6).

[0030]

GT = a · log (b · S ₂ ) −c where a, b and c are constants.

Equation 6 can be transformed from Equation 5 to Equation 7 below.

[0032]

GT = a · log (b · S ₁ ) −c + a · lo
g (t ₁ / t ₂ ) Here, a · log (b · S ₁ ) −c is the gloss measured by the gloss measuring device M1 in which the moving speed of the light and dark pattern is constant.

Therefore, from Equation 7, a · log (t ₁
/ T ₂ ) is the amount of change in gloss due to the change in the moving speed of the light and dark pattern 16 from V ₁ to V ₂ .

Next, consider the curvature of the surface to be measured. First, as shown in FIG. 7, assuming that the image forming position of the light and dark pattern when the surface to be measured is a plane is F ₀ , and when the surface to be measured is a convex surface (curvature U ₁ ), Reflected light diverges, the image forming position of the light and dark pattern changes from F ₀ to F ₁ . On the other hand, if the surface to be measured concave (curvature U _2), as shown in FIG. 8, the imaging position of the light-dark pattern as F ₂ from F ₀ for the reflected light to converge from the surface to be measured Will change.

As described above, when the image of the light and dark pattern is out of focus on the photoelectric conversion element, the light intensity changes according to the curvature. As a result, the increment of the light intensity, which is the numerator of Formula 1, changes, and the obtained glossiness also changes according to the curvature.

From the above, as shown in FIG. 12, when measuring the glossiness of various curved surfaces having the same glossiness visually, the increase in light intensity (numerator of Equation 1) depends on the curvature of the surface to be measured. And the increment of the distance between the light and dark patterns (the denominator of Equation 1) changes due to the change in the moving speed of the light and dark patterns.

Therefore, the correction value ROM 5 in this embodiment is
The correction value stored in No. 5 solves the problem that the position (height) of the measurement surface changes in accordance with the curvature, thereby changing the glossiness due to the fluctuation of the moving speed of the light and dark pattern. Has become.

Hereinafter, a method of measuring the correction value will be described.
A jig shown in FIG. 14 is prepared.

A standard sample 48 is attached to this jig at the portion A in FIG. For this standard sample, for example, a flat plate glass with a black coating on the back surface is used. The standard sample 48 can be arbitrarily moved in a direction connecting the standard sample 48 and the glossiness measuring device 10 as shown in FIG. This moving distance h can be measured in advance.

Here, a case where a curved surface having a curvature U is measured will be considered. Assuming that the shortest distance between the plane passing through the line connecting the contacts 74 and the measurement point is h ₀ as shown in FIGS. 9 and 10, the curvature of this curved surface becomes the value of the following equation 8.

[0041]

U ₀ = 2 · h ₀ / (h ₀ ² + l ² ) where 1 is the radius of the circle on which the contact 74 that contacts the measurement surface is arranged as shown in FIG.

This distance h ₀ corresponds to the distance the standard sample 48 has been moved. Thus, if allowed a standard sample 48 a distance h ₀ is moved, the distance h ₀ corresponds to the curvature of U _0.

Thus, when the standard sample 48 is moved and measured variously, the glossiness obtained corresponds to the glossiness of a curved surface having a curvature corresponding to the movement distance changed by the influence of the movement speed. .

Therefore, first, the standard sample 48 is measured for glossiness at a position serving as a reference for glossiness, and is used as a reference glossiness. Next, after moving the standard sample 48 from its reference position, the rate of change in light intensity reflected from the surface to be measured is determined while moving the light-dark pattern 16,
The maximum value Tmax calculated by the following equation 9 is defined as the glossiness.

[0045]

GT = a + log (b.Tmax) -c The above measurement is performed by moving the standard sample 48 variously.

The position of the light / dark pattern 16 at which the maximum value of the change rate of the light intensity is obtained is obtained from the number of pulses of the pulse motor.

Here, when the standard sample 48 is measured by moving a distance h _j from a surface corresponding to a glossiness reference surface, for example, a position corresponding to a flat surface, the light-dark pattern 16 in which the rate of change in light intensity is maximum is measured. If the position is Hp _j and the gloss at that time is GT _j , as shown in FIG. 15, the gloss measured from the value of the gloss of the reference plane (for example, a plane) The value ΔGT _j obtained by subtracting the value of Δ is the amount by which the glossiness fluctuates under the influence of the curvature and the movement speed of the light-dark pattern 16.

[0048] In this case, the distance h _i corresponding to the curvature U _i,
The position Hp _{i of the} light-dark pattern where the rate of change of the light intensity is maximum
And corresponding. The reason will be described below.

When the standard sample 48 is measured at a position corresponding to the plane of the curvature U ₀ (= 0), the image of the light-dark pattern 16 passes over the pinhole, and the light-dark pattern 16 at which the rate of change of the light intensity becomes maximum is obtained. Position Hp ₀ corresponds to the point A ₀ in FIG. However, for example, when the standard sample 48 is moved to a position corresponding to the convex surface of the curvature U ₁ and measured, the position Hp ₁ of the light-dark pattern 16 changes to a position corresponding to A ₁ in FIG. This is because light which has passed through the projection lens 18 is reflected at the same reflection angle a ₀ as the incident angle of a ₀ when incident at an incident angle a _0, to form an image of bright and dark pattern 16 on the photoelectric conversion element 24 This is because should the position of the light-dark pattern 16 is moved from a ₀ to a _1.

Therefore, the distance h and the position Hp _i of the light-dark pattern 16 have the following relationship:

[0051]

H = d · (Hp _i −Hp ₀ ) where d is a constant.

Therefore, the distance h over which the standard sample 48 has been moved is
_It can be seen that _i corresponds to the position Hp _{i of the} light and dark pattern.

From the above, the position Hp _{i of} this light and dark pattern
Is the curvature U _i , and the distance h over which the standard sample 48 has been moved.
Corresponds to _i .

Then, as shown in FIG.
Measure the standard sample 48 by moving it variously based on the gloss value of the flat surface.
The value obtained by subtracting the specified gloss value is used as the correction value ΔGT._i(D
Dashi _i= 1 ・ 2 ・ 3 ・ ・ ・ ・ n)
Position Hp of turn 16_i(Dashi_i= 1 ・ 2 ・ 3 ・ ・ ・
• Store in the correction value ROM 55 corresponding to (n).

Hereinafter, the operation of this embodiment will be described.
When a measurement start switch (not shown) of the glossiness measuring device 10 used in the present embodiment is turned on, a control signal is sent to the pulse motor driver 30 in accordance with a command from the CPU 52, and
The rotation of the pulse motor 26 is controlled. Pulse motor 2
When 6 rotates, the rotation of the pulse motor 26 is converted into linear motion of the sliding table by a conversion mechanism (not shown) represented by a rack and pinion or the like. Therefore, the predetermined rotation of the pulse motor 26 is converted into a predetermined moving amount of the sliding table. For this reason, the light-dark pattern 16 fixed to the sliding table is perpendicular to the optical axis of the projection lens 18 as indicated by the arrow A.
Move in the direction. When the light-dark pattern 16 moves, the boundary between the light part and the dark part of the light-dark pattern 16 formed by the projection lens 18 via the measured surface 36 moves on the front surface of the photoelectric conversion element 24. The photoelectric conversion element 24 converts the signal into an electric signal corresponding to the intensity of light passing through the pinhole 22. The CPU 52 obtains the gloss according to the routine described below.

Next, the control of the glossiness measurement in the control circuit 32 of this embodiment will be described with reference to the drawings.

FIG. 1 shows the main routine of the gloss measurement in this embodiment. Initialization is performed in step 100, the number of processings n is set to 1, and the maximum value T ₀ of the rate of change of light intensity is set. Is set to 0. Further, the movement amount p of the light and dark pattern 16 is taken in. On the other hand, one of the limit switches 38 is set so that the sliding table returns to the initial state.
Is turned on until the pulse motor 26 is turned on. When the initialization is completed, the process proceeds to step 104,
Then, the light intensity _Sn is captured by the photoelectric conversion element 24, and the process proceeds to step 106. In step 106, the number of processes is determined. If the process is the first time, the process proceeds to step 116. If not, the process proceeds to step 108. Step 108
In the maximum value T _n of the rate of change of the detected light intensity is calculated, the process proceeds to step 110. In step 110, the magnitude of the maximum value T _n of the rate of change of the computed light intensity at step 108 is compared with the maximum value T _n-1 which is previously calculated, the maximum value of the previous maximum value of the current processing state proceeds to step 112 is larger, the maximum value T _n of the rate of change of light intensity of the current processing is stored in the Tmax as a maximum value step 1
Proceed to 13. In step 113, a value obtained by multiplying the current number of measurements n by the movement amount p is used as the position Hp _{i of the} light-dark pattern 16.
And proceeds to step 114. On the other hand, if the maximum value of the change rate of the light intensity in the current processing state is smaller than the previous maximum value in step 110, the process proceeds to step 114 while maintaining the previously calculated maximum value T _n-1 as the maximum value. As described above, the maximum value Tmax of the rate of change of the light intensity in the boundary region between the light and dark portions is held. In step 114, the state of the other limit switch 38 on the sliding table is determined. If the light / dark pattern 16 is still movable, the limit switch 38 is off and the process proceeds to step 116. In step 116, the number of times of processing is incremented by one and the process proceeds to step 118. By rotating the pulse motor 26 by a predetermined amount, the light and dark pattern 16 is moved by the distance of the pitch p, and the process is executed again from step 104. Therefore, this processing is continued until the movement of the light / dark pattern 16 is completed by turning on the other limit switch 38. On the other hand, when the moving amount of the light and dark pattern 16 is about to exceed the movable range, the limit switch 38 is turned on, and the process proceeds to step 121. In step 121, the correction value ΔGT corresponding to the position Hp _i of the light-dark pattern when the change rate of the light intensity stored in step 113 is maximized
_i is read from the correction value ROM 55, and the routine proceeds to step 122. In the case where the rate of change of light intensity position of the light-dark pattern 16 becomes maximum is different from the position Hp _i light-dark pattern 16 is stored in the correction value ROM55 is by interpolation,
The correction value ΔGT _i is calculated. In step 122, the resulting correction value DerutaGT _i read in step 121 from the maximum value Tmax of the rate of change of light intensity gloss GT = a + lo
The gloss G is obtained by adding the value to g (b.Tmax) -c. The routine proceeds to step 124, where the value of the gloss G obtained in step 122 is displayed, and this routine ends.

In the gloss measurement main routine of the first embodiment, the maximum value Tmax of the light intensity change rate is held by moving the light-dark pattern 16 by a predetermined movement pitch p, and the held maximum value Tmax is maintained. Tmax is set in advance as a correction value ROM5.
Since the correction is performed using the correction value ΔGT _i stored in No. 5, accurate glossiness can be obtained without being affected by fluctuations in the speed fluctuation of the light-dark pattern 16.

Next, a second embodiment of the present invention will be described. The configuration of the second embodiment of the present invention is the same as the configuration of the first embodiment.

In the glossiness measuring apparatus 10 of the second embodiment, in addition to correcting the influence of the fluctuation of the moving speed of the light-dark pattern 16, the glossiness is reduced by reducing the influence of the refractive index of the paint on the surface to be measured. It is designed to measure.

Here, the reason why the refractive index of the paint on the surface to be measured must be taken into account when measuring the glossiness will be described below.

Many kinds of paints are used on the painted surface, and the glossiness of the painted surface painted with these different types of paints must be measured in the same manner. On the other hand, it has been conventionally known that the refractive index of a paint differs depending on the type of the paint. For this reason, the respective light intensity values reflected by the surfaces coated with the paints having different refractive indexes are different. Therefore, even if the glossiness is the same, the value indicating the glossiness measured by the measuring device may be different when the coating is applied with paints having different refractive indexes even if the glossiness is the same. That is, in the glossiness measuring device 10 of the first embodiment,
Since the glossiness is calculated only from the maximum value of the change rate of the light intensity of the light and dark pattern image, the calculated glossiness value is in a relationship proportional to the refractive index of the paint, and is the same as that shown in FIG. The relationship between the refractive indices of the two types of painted surfaces showing the glossiness of the sense is that the refractive index of the paint B is larger than the refractive index of the paint A, and the difference between the light amounts of the bright part and the dark part is IA <
Since IB is satisfied, the value of the gloss is such that paint A <paint B. As described above, even when the visual sensation is the same, there is a problem that the value of the glossiness changes when measuring the measurement target surface on which different paints are applied. Therefore, in order to determine the gloss, it is necessary to consider the refractive index of the paint.

FIG. 2 shows a main routine for measuring the glossiness of the second embodiment. In the second embodiment, the same processing as that of the first embodiment is performed, but the following processing is newly added in consideration of the refractive index of the surface to be measured.

That is, when the initialization in step 100 is completed, the process proceeds to step 102, where
In 02, according to a correction value calculation subroutine described later,
A correction value k is obtained. After the correction value k is obtained, the light-dark pattern 16 is moved by a predetermined movement pitch p in the same manner as in the first embodiment, and the maximum value Tma of the rate of change of light intensity is obtained.
x is determined (steps 104 to 11).
4).

At step 114, the light and dark pattern 1
When the amount of movement of 6 is about to exceed the movable range, the limit switch 38 is turned on, and the routine proceeds to step 120. In step 120, the glossiness Q that is not affected by the refractive index of the surface to be measured is calculated from the maximum value Tmax of the change rate of the light intensity and the correction value k obtained in step 102, and step 121
Proceed to. In step 121, the correction value a correction value DerutaGT _i the rate of change of light intensity stored in step 113 corresponds to the position Hp _i light-dark pattern when the maximum ROM5
5 and proceeds to step 122. The position of the light-dark pattern 16 at which the rate of change of the light intensity is the maximum value is the position H of the light-dark pattern 16 stored in the correction value ROM 55.
If it is different from p _i , the correction value ΔGT _i is calculated by the same interpolation as in the first embodiment. In step 122,
By adding the correction value ΔGT _i read in step 121 to the gloss Q calculated in step 120, the gloss G is obtained.
The value of the gloss G obtained in step 2 is displayed, and this routine ends.

As described above, in the gloss measurement main routine of the second embodiment, first, the light-dark pattern 16 is moved by the predetermined moving pitch p, and the maximum value Tmax of the rate of change of the light intensity is held. . Then, the maximum value of the rate of change of the held light intensity is corrected by the correction value k described later, so that the glossiness Q in which the influence of the refractive index of the paint is eliminated is obtained. Is required accurate gloss G without being affected by the change in the moving speed of the light-dark pattern 16 since the correction is thus determined glossiness Q advance correction value correction value has been stored in the ROM55 ΔGT _i .

As described above, according to the second embodiment of the present invention, accurate gloss can be obtained even if the object to be measured is a sample different from the sample of the data stored in the correction value ROM 55.

Next, the subroutine 102 for calculating the correction value will be described with reference to FIG. The subroutine of this correction value calculation is to calculate the correction value k from the reference glass 40 used for calibration of the glossiness measuring device 10 and the surface to be measured.

First, at step 130, the reference glass 40
Is set, and the routine proceeds to step 132, where step 132
Then, the light amount difference value Is is calculated according to a light amount value calculation subroutine described later. In step 134, the surface to be measured for measuring the glossiness is set, and the process proceeds to step 136. In step 136, the light amount difference value Io of the surface to be measured is calculated in the same manner as in step 132. In step 138, the correction value k is calculated based on the obtained light amount difference values Is and Io.
Is calculated by the following equation (11), and this subroutine ends.

[0070]

1 / k = Io / Is Here, it is known that the glossiness is proportional to the refractive index. In the conventional glossiness measurement device, even if the luminosity shows the same glossiness, When the refractive index of the paint applied to the surface to be measured is large, the glossiness is large, and when it is small, the glossiness is small. Further, the light quantity difference value increases in proportion to the magnitude of the refractive index. For this reason, in the present embodiment, as described above, the glossiness increases when the refractive index of the surface to be measured is smaller than the reference value, and decreases when the refractive index is higher than the reference value. The glossiness is determined using a correction value k that is inversely proportional to the light amount difference value.
When the refractive index is a reference value, the light quantity difference value Is becomes the reference light quantity difference value Io, so that the correction value k becomes 1, and the glossiness is not corrected.

Therefore, the correction value k obtained in this routine
Is multiplied by the maximum value of the rate of change of light intensity, thereby correcting the effect of the refractive index of the paint on the surface to be measured, and calculating the glossiness without being affected by the refractive index of the paint applied to the surface to be measured. Can be As a result, even if the measured object is different from the sample of the data stored in the correction value ROM 55, the data of the correction value ROM 55 can be used.

Note that, as shown in FIG.
Reference numeral 0 denotes a reference glass 41 on one surface and a painted surface 42 coated with, for example, black paint on the other surface, which is used to calibrate the glossiness of the reference glass surface 41. However, the light passing through the reference glass surface 41 is reflected on the back surface of the other painted surface 42 and is returned to the reference glass surface 41 again.
The back surface is inclined at an angle so that a change in the amount of reflected light does not affect the gloss value. This reference glass has the correction value Δ stored in the correction value ROM 55.
It is the same as the standard sample when GT _i was measured.

Next, a subroutine 13 for calculating the light amount difference value
2 will be described with reference to FIG.

The subroutine for calculating the light amount difference value irradiates the maximum and minimum light amounts on the surface to be measured by moving the light-dark pattern 16 and measures the reflected light from the surface to be measured, as shown in FIG. The light amount difference value I is obtained.

First, in step 140, the light / dark pattern 16 is moved to a position where the light flux passing through the light / dark pattern 16 is minimized, that is, until one of the limit switches 38 of the sliding table is turned on, and step 142 is executed.
In step 142, the output value So of the photoelectric conversion element 24 is fetched, and the flow proceeds to step 144. Step 1
At 44, the light / dark pattern 16 is moved to a position where the luminous flux passing through the light / dark pattern 16 is maximized, that is, until the other limit switch 38 of the sliding table is turned on, and the process proceeds to step 146. At step 146,
The output value Sc of the photoelectric conversion element 24 is fetched, and step 1 is executed.
Go to 48. In step 148, the output value Sc is subtracted from the taken output value So of the photoelectric conversion element 24 to calculate the light amount difference value I, and the present subroutine ends.

As described above, according to the glossiness measuring apparatus according to the second embodiment of the present invention, even when the visual feeling is the same even on the surface to be measured coated with different kinds of paints, ,
The effect that the glossiness can be quantitatively evaluated without changing the glossiness due to the influence of the type of the paint, and the accurate glossiness can be quantitatively evaluated without the influence of the curvature is obtained.

In the first and second embodiments described above, the correction value ΔGT _i stored in the correction value ROM 55 is used.
The glossiness of various curved surfaces is measured in advance, and a value obtained by subtracting the glossiness value of each curved surface from the glossiness value when the measured surface is a reference surface, for example, a flat surface, and a light-dark pattern 1
Although 6 is positioned Hp _i to correspond to the not limited to this, for example, it may be as follows.

First, various curvatures are stored in the correction value ROM 55 in place of the position Hp _i of the light and dark pattern 16,
Correction value DerutaGT _i may also be stored so as to correspond to the curvature. In this case, the curvature of the surface to be measured is obtained for each measurement, and the correction value Δ stored in the correction value ROM 55 based on the curvature.
What is necessary is just to perform the process of reading and calculating GT _i .

[0079] Second, the correction value ROM55 the value of the ratio of glossiness of gloss and various curved planes, be stored in correspondence with the position Hp _i curvature or light-dark pattern 16 of the curved surface Good. In this case, it may be read the value of the stored ratios in the correction value ROM55 from the position Hp _i of the curved surface of curvature or light-dark pattern 16. Note that the correction value R
When reading the value of the ratio stored in the OM 55, it is necessary to measure the curvature of the surface to be measured for each measurement.

[0080] Thirdly, the correction value ROM55 may be stored glossiness of the plane, and be stored in correspondence glossiness of various curved position Hp _i curvature or light-dark pattern 16 of the curved surface Good. In this case, the correction value from the position Hp _i curvature or light-dark pattern 16 of the measurement surface ROM5
5 is read, the read value is subtracted from the flat gloss value, and the subtracted value is added to the measured gloss value. When reading the value of the ratio stored in the correction value ROM 55 from the curvature, it is necessary to measure the curvature of the surface to be measured for each measurement.

Further, in the above embodiment, the correction value ΔG
Is provided with the correction value ROM55 for storing T _i, not limited to this, for example, that for calculating the exact gloss in accordance with the measured glossiness change in the moving speed of the light-dark pattern 16 A possible arithmetic expression may be stored, and processing may be performed based on this arithmetic expression.

Further, in the above embodiment, the increase in light intensity is calculated for each pulse, and this is divided by the distance that the light-dark pattern moves in one pulse, the rate of change in light intensity is obtained, and the maximum value is calculated as the gloss level. However, the present invention is not limited to this, and the maximum value of the tangent gradient of the light intensity curve of the reflected light, which is the differential value of the light intensity, may be obtained and used as the gloss.

In the above embodiment, an example has been described in which a program is used to determine the maximum fluctuation amount of light intensity by software. However, the present invention is not limited to software, and can be performed by electrical hardware. For example, the maximum fluctuation amount may be obtained by a peak hold circuit,
Also, the glossiness can be obtained by combining the differentiation circuit and the peak hold circuit.

In the above embodiment, an example in which a change in sharpness is detected by moving a light and dark pattern has been described. However, the present invention is not limited to moving a light and dark pattern, and the light and dark pattern is fixed. Use, providing a detection aperture such as a pinhole on the incident side of the photoelectric conversion element,
The detection aperture is arranged so that it can move in the direction in which the transmittance of the light and dark pattern image changes, and the detection aperture such as a pinhole is moved so as to change the position of the light and dark pattern image incident on the photoelectric conversion element. The light amount changing from the dark part to the bright part of the image may be detected.

In the above embodiment, an example using a light-dark pattern having a pair of light-dark portions has been described. However, the present invention is not limited to a pattern of a pair of light-dark portions. The present invention can easily be applied to a case where glossiness is obtained by detecting contrast using a rectangular pattern having a shape. Also, an example using a transmissive light / dark pattern has been described, but a reflective light / dark pattern may be used.

In the above-described embodiment, the case where the glossiness is corrected using the reference glass has been described. However, the reference calibration and correction data may be stored in advance without using the reference glass. it can.

[0087]

According to the glossiness measuring apparatus of the present invention, there is obtained an effect that accurate glossiness can be quantitatively evaluated without being affected by fluctuations in the moving speed of the pattern.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a glossiness measurement control routine according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a glossiness measurement control routine according to a second embodiment of the present invention.

FIG. 3 is a flowchart illustrating a correction value calculation subroutine according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing a light amount difference value calculation subroutine according to a second embodiment of the present invention.

FIG. 5 is a glossiness measuring apparatus to which the present invention is applied.

FIG. 6 is a block diagram of a control circuit according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between image forming positions of a light and dark pattern when a surface to be measured is a flat surface and a convex surface.

FIG. 8 is a diagram illustrating a relationship between image forming positions of a light and dark pattern when a surface to be measured is a flat surface and a concave surface.

FIG. 9 is a cross-sectional view when the glossiness measuring device to which the present invention is applied is in contact with a surface to be measured, and a diagram showing an arrangement of contacts.

FIG. 10 is a diagram illustrating the position of a light-dark pattern 16 when glossiness of a flat surface and a curved surface is obtained.

FIG. 11 is a diagram illustrating a relationship between a rotation angle of a pulse motor and a moving speed of a light-dark pattern 16;

FIG. 12 is a diagram illustrating a relationship between the position of a knife edge pattern of a light and dark pattern and light intensity.

FIG. 13 is a diagram illustrating a relationship between a moving speed of a light and dark pattern and a moving distance.

FIG. 14 is a schematic view of a jig for measuring a correction value ΔGT _i .

FIG. 15 is a diagram illustrating a relationship between a moving distance of a sample attached to a jig and a gloss level, and a relationship between a position Hp _{j of a} pattern where a change rate of light intensity is maximum and a correction value ΔGT _j . It is.

FIG. 16 shows a correction value ΔGT _i corresponding to a position Hp _{i of a} light-dark pattern where the rate of change of light intensity is the maximum.
FIG. 6 is a diagram illustrating a state stored in a storage unit 55;

FIG. 17 is a perspective view illustrating a shape of a light and dark pattern used in the example of the present invention.

FIG. 18 is a perspective view showing the shape of a reference glass for calibrating a glossiness measuring device used in an example of the present invention.

FIG. 19 is a diagram illustrating a relationship between a moving amount of a light and dark pattern and light intensity.

FIG. 20 is a diagram illustrating a relationship between a light-dark pattern movement amount and light intensity.

[Description of Signs] 10 Glossiness measuring device 16 Light / dark pattern 18 Projection lens 24 Photoelectric conversion element 26 Pulse motor 32 Control circuit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Motobe 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-4-256840 (JP, A) JP-A-63- 109351 (JP, A) JP-A-7-286958 (JP, A) JP-A-53-4977 (JP, U) JP-B-37-7445 (JP, B2) JP-B-39-5095 (JP, B2) (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01B 11/30

Claims (1)

(57) [Claims] 1. A light source, a pattern provided with at least one pair of portions having different light transmittances, and a projection means for projecting light irradiated by the light source and passing through the pattern onto a surface to be measured and forming an image of the pattern. And photoelectric conversion means arranged at a position where the image of the pattern is formed by the projection means and converting the light intensity of the reflected light from the surface to be measured into an electric signal; and incident on the pattern. Pattern moving means for moving the pattern in a direction orthogonal to the optical axis of the light to be transmitted and in which the light transmittance of the pattern changes; and a surface to be measured based on an electric signal input from the photoelectric conversion means. Calculating means for determining the rate of change of light intensity or the maximum value of the differential value reflected at the position, and correcting the fluctuation of the maximum value caused by the fluctuation of the moving speed of the pattern. Measuring device.