JP4640254B2 - Scratch measuring device and measuring method - Google Patents

Description

  The present invention relates to a technique for quantitatively measuring scratches formed on the surface of an object.

A painted surface of an automobile body or the like is required to be hard to be scratched or to be hardly noticeable. Therefore, in the process of developing paints, a process that intentionally forms scratches on the painted surface is carried out to evaluate the resistance to scratches (abrasion resistance) and the degree to which scratches are not noticeable. A test is being conducted.
Cited Document 1 describes a technique for evaluating the difficulty of scratches. In the technique of the cited document 1, instead of the process of forming scratches on the painted surface, a transparent film material having scratches is prepared, and the transparent film material is brought into close contact with the painted surface to be evaluated. And the brightness of the site | part in which the abrasion of the transparent film material closely_contact | adhered to the coating surface is formed, and the site | part in which the abrasion is not formed are each measured. At this time, on the painted surface where scratches are conspicuous, the brightness difference between the brightness measured for the site where the scratch is formed and the brightness measured for the site where the scratch is not formed becomes large. On the other hand, the difference in brightness is small on a painted surface where scratches are not noticeable. This technique quantitatively evaluates the conspicuousness of scratches by the amount of change in brightness due to the presence or absence of scratches.
JP-A-7-55708

  On the other hand, in a test for evaluating the difficulty of scratching (abrasion resistance), a process for intentionally forming a scratch on the painted surface to be evaluated is performed, and the degree of the scratch formed on the painted surface is evaluated. The degree of scratches formed on the painted surface can be quantitatively measured by measuring the amount of change in brightness before and after the scratch formation. That is, if the brightness change amount before and after the formation of scratches is large, it indicates that many scratches have been formed on the painted surface, and it can be determined that the scratch resistance of the painted surface is low. On the other hand, if the brightness change amount before and after the formation of the scratch is small, it indicates that there is little scratch formed on the painted surface, and it can be determined that the scratch resistance of the painted surface is high. The result of evaluating the scratch resistance of the painted surface is fed back to the development of the paint, for example, and the scratch resistance can be improved by adjusting the composition of the paint.

In the process of studying the technique for improving the scratch resistance of the painted surface, the applicant of the present application has confirmed that the scratch resistance of the painted surface cannot be evaluated correctly only by the amount of change in brightness before and after the formation of the scratch. Specifically, when the scratch resistance evaluation test was performed on two types of painted surfaces, the amount of change in brightness before and after the formation of the scratches was the same, but the two types of painted surfaces were visually evaluated. There was a clear difference in the case. This indicates that the scratch resistance cannot be equated even if the coated surface has the same amount of change in brightness before and after the formation of the scratch. In the prior art, the state of the scratch formed on the painted surface cannot be measured correctly, and the scratch resistance cannot be evaluated correctly.
The present invention solves the above problems. The present invention provides a technique capable of correctly measuring scratches formed on an object surface such as a painted surface.

The technique of the present invention can be embodied in an apparatus for quantitatively measuring scratches formed on the surface of an object. The measuring apparatus is illuminated by illumination means that illuminates the object surface with illumination light at a predetermined incident angle, first brightness measurement means that measures the brightness of the object surface illuminated by the illumination means, and illumination means. A second lightness measuring means for measuring the lightness of the object surface through a polarizing filter that absorbs a component that vibrates perpendicularly to the incident surface; and an object before scratch formation measured by the first lightness measuring means. The first brightness change amount between the brightness of the surface and the brightness of the object surface after scratch formation measured by the first brightness measuring means, and the brightness of the object surface before scratch formation measured by the second brightness measurement means. And means for calculating a second lightness change amount between the lightness of the object surface after the scratch formation measured by the second lightness measurement means.
The incident surface here means a plane including the incident axis when the illumination light is incident on the object surface and the normal of the object surface.

As a result of a detailed study of the scratches formed on the object surface, the applicant of the present application has found that the scratches formed on the object surface include surface scratches that form irregularities on the object surface and internal scratches that change the surface layer of the object. Has been found to be included. Surface flaws formed on the object surface generate a minute reflecting surface on the object surface, thereby reducing the gloss of the object surface. Internal flaws formed on the surface of the object cause the surface of the object to become clouded, for example, thereby changing the color of the object itself. The change in brightness before and after the formation of scratches is accompanied by the formation of surface scratches and also by the formation of internal scratches. As in the prior art, simply measuring the amount of change in brightness before and after the formation of scratches, the total amount of change in brightness caused by surface scratches and the amount of change in brightness caused by internal scratches is measured. It is impossible to determine whether the resistance is inferior or the resistance to internal wounds is inferior.
Surface scratches and internal scratches have different formation mechanisms. Therefore, for example, when adjusting the composition of the paint in order to improve the scratch resistance of the painted surface, the measures for improving the resistance to surface scratches and the measures for improving the resistance to internal scratches are mutually It will be different. In order to appropriately take measures for improving the scratch resistance of the painted surface, it is necessary to distinguish and evaluate the scratch resistance against surface scratches and the scratch resistance against internal scratches. For this purpose, it is necessary to quantitatively measure the scratches formed on the painted surface by distinguishing between surface scratches and internal scratches.

  When illumination light is incident on the object surface, a part of the light is reflected on the object surface, and a part of the light is diffusely reflected on the surface layer of the object. Since the intensity of the surface reflected light on the object surface changes according to the properties of the object surface, it changes according to the degree of surface scratches formed on the object surface. Therefore, if the amount of change in the intensity of the surface reflected light before and after the formation of the scratch can be measured, the surface scratch formed on the object surface can be quantitatively measured. On the other hand, the intensity of the diffusely reflected light on the surface layer of the object changes according to the properties of the surface layer of the object, and thus changes according to the degree of internal flaws formed on the surface layer of the object. Accordingly, if the intensity change amount of the diffuse reflected light before and after the formation of the scratch can be measured, the surface scratch formed on the surface layer of the object can be quantitatively measured.

  In the surface reflection on the object surface, the component that vibrates perpendicularly to the incident surface is reflected by a relatively high reflectance, but the component that vibrates parallel to the incident surface has a relatively low reflectance. Reflected. Thereby, the surface reflected light reflected by the object surface becomes substantially linearly polarized light mainly including a component that vibrates perpendicularly to the incident surface. On the other hand, the diffusely reflected light diffusely reflected on the surface layer of the object becomes non-polarized light having no specific vibration direction. Therefore, when measuring the brightness of the object surface through a polarizing filter that absorbs the component that vibrates perpendicular to the incident surface, the surface reflected light is almost eliminated by the polarizing filter, mainly diffuse reflection. The intensity of light can be measured.

In the measuring apparatus embodied by the present invention, the brightness of the object surface before and after the formation of the scratch can be measured without using the polarizing filter, and can also be measured through the polarizing filter. The first brightness change amount between the brightness before scratch formation measured without using the polarizing filter and the brightness after scratch formation measured without using the polarizing filter is due to the surface scratch formed on the object surface. The sum of the lightness change amount and the lightness change amount caused by internal flaws formed on the surface layer of the object is shown. That is, the first lightness change amount quantitatively indicates the degree of scratches including both surface scratches and internal scratches. On the other hand, the second lightness change amount between the brightness before scratch formation measured through the polarizing filter and the brightness after scratch formation measured through the polarizing filter is due to internal scratches formed on the surface layer of the object. The value of about half of the brightness change amount is shown. That is, the second brightness change amount quantitatively indicates the degree of internal flaws formed on the surface layer of the object. According to the measuring apparatus embodied by the present invention, the first lightness change amount and the second lightness change amount can be respectively measured. If the first lightness change amount and the second lightness change amount are found, it is possible to quantitatively grasp each of the surface flaw formed on the object surface and the internal flaw formed on the surface layer of the object.
According to this measuring apparatus, the degree of abrasion formed on the surface of an object can be quantitatively measured by distinguishing between surface scratches and internal scratches.

In the measurement apparatus described above, the calculation means includes a first scratch index obtained by subtracting the second brightness change amount from the first brightness change amount and a second scratch index obtained by doubling the second brightness change amount. It is preferable to calculate at least one of the following.
The first scratch index obtained by subtracting the second lightness change amount by doubling the first lightness change amount corresponds to the lightness change amount caused by the surface scratch formed on the object surface. The second scratch index obtained by doubling the second lightness change amount corresponds to the lightness change amount caused by the internal flaw formed on the surface layer of the object. According to this apparatus, it is possible to obtain a first scratch index that quantitatively indicates the degree of surface scratches formed on the object surface and a second scratch index that quantitatively indicates the degree of internal scratches formed on the surface layer of the object. it can.

In the measurement apparatus described above, it is preferable that the incident angle of the illumination light is substantially equal to the Brewster angle of the object surface.
As described above, in the surface reflection on the object surface, the component that vibrates in parallel to the incident surface is reflected with a relatively low reflectance. This reflectivity changes according to the incident angle when the illumination light is incident on the object surface, and the reflectivity becomes zero at a predetermined incident angle. The incident angle at this time is generally called the Brewster angle. When the incident angle of the illumination light is equal to the Brewster angle, the surface reflected light becomes linearly polarized light having only a component that vibrates perpendicularly to the incident surface. Therefore, if the incident angle of the illumination light is equal to the Brewster angle, the surface reflected light can be completely eliminated by the polarizing filter. Thus, the first scratch index accurately corresponds to the brightness change amount caused by the surface scratch, and the second scratch index accurately corresponds to the lightness change amount caused by the internal scratch. The degree of abrasion formed on the surface of the object can be quantitatively measured by accurately distinguishing between surface scratches and internal scratches.

In the measurement apparatus described above, input means for inputting the light refractive index at the object surface, Brewster angle calculation means for calculating the Brewster angle of the object surface based on the light refractive index input by the input means, It is preferable that adjustment means for adjusting the incident angle of the illumination light to the Brewster angle calculated by the Brewster angle calculation means is added.
The Brewster angle of the object surface changes according to the light refractive index at the object surface. In this measuring apparatus, if the refractive index of the object surface is input, the incident angle of the illumination light is adjusted to be equal to the Brewster angle. Thereby, the formed scratches can be quantitatively measured with respect to various object surfaces having different optical refractive indexes.

In the measurement apparatus described above, it is preferable that the first brightness measurement means and the second brightness measurement means are configured using a common photometer. In this case, the polarizing filter is preferably detachable between the common photometer and the object surface.
Thereby, a measuring apparatus embodying the present invention can be realized without using two photometers.

In the measurement apparatus described above, the incident angle of the illumination light is preferably approximately 57 degrees.
On a painted surface of an automobile body or the like, a clear coat layer is formed on the surface. Most of the clear coat layers have a refractive index in the range of 1.48 to 1.60, and the Brewster angle is approximately equal to 57 degrees. Therefore, when the incident angle of the illumination light is approximately 57 degrees, the scratch formed on the painted surface of the automobile body or the like can be quantitatively measured by distinguishing between the surface scratch and the internal scratch.

The technique of the present invention can also be embodied in a method for quantitatively measuring scratches formed on the surface of an object. This measuring method includes a first brightness measurement step of measuring the brightness of an object surface by irradiating illumination light at a predetermined incident angle on the object surface before scratch formation, and illuminating the object surface before scratch formation with a predetermined incident angle. A second brightness measurement step of measuring the brightness of the object surface through a polarizing filter that irradiates light and absorbs a component that vibrates perpendicular to the incident surface; and a predetermined incident angle on the object surface after the formation of the scratch Irradiating illumination light at the third brightness measurement step for measuring the brightness of the object surface, and irradiating the object surface after the scratch formation with illumination light at a predetermined incident angle and vibrating perpendicularly to the incident surface A fourth brightness measurement step for measuring the brightness of the object surface through a polarizing filter that absorbs the component, and a first between the brightness measured by the first brightness measurement step and the brightness measured by the third brightness measurement step. Lightness change amount and second lightness measurement And a step of calculating the second amount of change in lightness between the measured lightness by the measured brightness and fourth brightness measuring process by. In the calculation step, it is more preferable to calculate at least one of a first scratch index obtained by doubling and subtracting the second brightness change amount from the first brightness change amount and a second scratch index obtained by doubling the second brightness change amount. preferable.
According to this measurement method, the degree of scratches formed on the surface of an object can be quantitatively measured by distinguishing between surface scratches and internal scratches.

  According to the present invention, the degree of surface flaws formed on the surface of an object and the degree of internal flaws formed on the surface layer of the object can be quantitatively measured. Thereby, it is possible to distinguish and evaluate the scratch resistance against surface scratches and the scratch resistance against internal scratches, and it is possible to appropriately take measures for improving the scratch resistance of the object surface.

First, the main features of the embodiments described below are listed.
(Characteristic 1) The measuring apparatus includes a rotatable sample stage. The measurement apparatus adjusts the incident angle when the illumination light from the illumination unit is incident on the object surface by rotating the sample stage.
(Characteristic 2) The measuring apparatus includes a photometer that receives reflected light reflected by the object surface and measures the intensity of the reflected light.
(Characteristic 3) The measuring device includes means for adjusting a variable angle formed between the regular reflection direction of the illumination light and the light receiving axis of the photometer.
(Characteristic 4) The measurement device calculates the first scratch index and the second scratch index for each of a plurality of deflection angles.
(Characteristic 5) The measuring apparatus includes display means for displaying the calculated first scratch index and second scratch index.

A scratch resistance measuring apparatus (hereinafter simply referred to as a measuring apparatus) embodying the present invention will be described with reference to the drawings. FIG. 1 schematically shows the configuration of the measuring apparatus 10 of the present embodiment.
The measuring apparatus 10 includes a sample stage 14 on which a sample 100 that is a measurement target of scratch resistance is placed. The sample stage 14 is provided so as to be rotatable around a reference axis C. The sample 100 is fixed to the sample stage 14 so that the reference axis C is located in the sample surface 100a. Here, for convenience of explanation, an xyz orthogonal coordinate system in which the z-axis is parallel to the reference axis C is defined. In this case, the normal line Db of the sample surface 100a is located in the xy plane. When the sample stage 14 rotates about the reference axis C, the normal Db of the sample surface 100a rotates about the reference axis C in the xy plane. The measuring apparatus 10 illuminates the sample 100 on the sample stage 14. The light source device 12 is provided. The light source device 12 can be configured using, for example, a halogen lamp. The optical axis Da of the light source device 12 extends toward the reference axis C in the xy plane. In the measuring apparatus 10, the angle θ formed by the optical axis Da of the light source 12 and the normal line Db of the sample surface 100 a, that is, the incident angle θ of the illumination light 2 can be adjusted by rotating the sample stage 14. it can. Further, the plane including the optical axis Da of the light source 12 and the normal line Db of the sample surface 100a, that is, the incident surface of the illumination light 2 is always parallel to the xy plane.

  The measuring apparatus 10 includes a turntable 16, a photometer 18, and a polarizing filter 20. The turntable 16 is rotatable around the reference axis C. The photometer 18 and the polarizing filter 20 are disposed on the turntable 16. The light receiving axis Dd of the photometer 18 extends toward the reference axis C in the xy plane. The polarizing filter 20 is detachably attached between the reference axis C and the photometer 18. With the polarizing filter 20 attached, the reflected light 4 reflected by the sample 100 is received by the photometer 18 after passing through the polarizing filter 20. On the other hand, in a state where the polarizing filter 20 is removed, the reflected light 4 reflected by the sample 100 is received by the photometer 18 without passing through the polarizing filter 20.

The photometer 18 measures the intensity of the reflected light 4 reflected by the sample surface 100a. That is, the brightness of the sample surface 100a is measured. The photometer 18 is a so-called spectrophotometer, and the intensity of the reflected light 4 can be measured for each wavelength. The photometer 18 includes a spectroscope (for example, a prism) and a light receiving element (for example, a photodiode array). However, in the measuring apparatus 10 of the present embodiment, it is not necessary to measure the intensity of the reflected light 4 for each wavelength.
The polarizing filter 20 includes a linear polarizer whose absorption axis extends in the z-axis direction. When the reflected light 4 is transmitted, the polarizing filter 20 absorbs a component that oscillates perpendicular to the xy plane and transmits only a component that oscillates parallel to the xy plane. The xy plane is a plane including the incident axis Da of the illumination light 2 and the normal line Db of the sample surface 100a, and is an incident surface when the illumination light 2 is incident on the sample surface 100a. That is, when the reflected light 4 is transmitted, the polarizing filter 20 absorbs a component that oscillates perpendicular to the incident surface and transmits a component that oscillates parallel to the incident surface. Thereby, in a state where the polarizing filter 20 is attached, only the component that vibrates in parallel to the incident surface in the reflected light 4 enters the photometer 18.
The turntable 16 is provided to adjust the variable angle α. The variable angle α here indicates an angle α formed by the light receiving axis Dd of the photometer 18 and the regular reflection direction Dc. In the measuring apparatus 10, the turning angle α can be adjusted by rotating the turntable 16 around the reference axis C.

  As shown in FIG. 1, the measurement apparatus 10 performs operations of the first motor 22 that rotates the sample stage 14, the second motor 24 that rotates the rotary stage 16, and the operations of the first motor 22 and the second motor 24. A motor controller 26 to be controlled and a calculation device 30 are provided. The calculation device 30 includes a Brewster angle calculation unit 32, a scratch index calculation unit 34, a display device 40, an input device 42, and the like. A photometer 18 and a motor controller 26 are connected to the calculation device 30. The computing device 30 is configured using a general-purpose computer device.

  The Brewster angle calculation unit 32 calculates the Brewster angle with respect to the sample surface 100 a based on the light refractive index of the sample 100. The optical refractive index of the sample 100 can be input by an operator or the like using the input device 42. The Brewster angle calculated by the Brewster angle calculation unit 32 is taught to the motor controller 26. The motor controller 26 controls the operation of the first motor 22 to adjust the incident angle θ of the illumination light 2 to the Brewster angle. The scratch index calculation unit 34 will be described in detail later.

The Brewster angle calculated by the Brewster angle calculation unit 32 will be described with reference to FIG. FIG. 2 shows a state in which the illumination light 2 is incident on the sample surface 100a at an incident angle θ. At this time, a part of the illumination light 2 is specularly reflected by the sample surface 100a, and becomes the surface-reflected light 4a and proceeds in the specular reflection direction Dc. Further, part of the illumination light 2 is refracted on the sample surface 100a and becomes transmitted light 6 and travels in the transmission direction De. The incident axis of the illumination light 2 (the optical axis Da of the light source device 12), the normal Db of the sample surface 100a, the regular reflection direction Dc, and the transmission direction De are located in the xy plane. In general, a plane including the incident axis of the illumination light 2 (the optical axis Da of the light source device 12) and the normal line Db of the sample surface 100a is called an incident surface. In this embodiment, the xy plane corresponds to the incident surface. Further, an angle φ formed by the normal line Da of the sample surface 100a and the transmission direction De is called a transmission angle.
In the surface reflection on the sample surface 100a, the component oscillating parallel to the incident surface (xy plane) in the illumination light 2 and the component perpendicular to the incident surface (xy plane) in the illumination light 2 are vibrated. Are reflected by different reflectivities. The intensity of the component oscillating parallel to the incident surface of the illumination light 2 is Hp, the intensity of the component oscillating perpendicular to the incident surface of the illumination light 2 is Hs, and the incident surface of the surface reflected light 4a is On the other hand, if the intensity of the component oscillating in parallel is Jp and the intensity of the component oscillating perpendicularly to the incident surface of the surface reflected light 4a is Js, the following relationship is established from Fresnel's law.
Rp = Jp / Hp = tan ² (θ−φ) / tan ² (θ + φ) (1)
Rs = Js / Hs = sin ² (θ−φ) / sin ² (θ + φ) (2)
Rp and Rs in the above formula are generally called Fresnel coefficients. One Fresnel coefficient Rp indicates a reflectance with respect to a component oscillating parallel to the incident surface. The other Fresnel coefficient Rs indicates a reflectance with respect to a component oscillating perpendicularly to the incident surface. From the above equation (1), it can be seen that the Fresnel coefficient Rp becomes zero when θ + φ = π / 2. The incident angle θ at this time is referred to as Brewster angle θb. When the illumination light 2 is incident on the sample surface 100a at an incident angle equal to the Brewster angle θb, only the component that vibrates perpendicular to the xy plane is reflected on the sample surface 100a. As a result, the surface reflected light 4a becomes linearly polarized light having only the component Js that vibrates perpendicularly to the xy plane.

The Brewster angle θb can be calculated using the optical refractive index of the sample 100. When the light refractive index of air is n1 and the light refractive index of the sample 100 is n2, the following relationship is established between the incident angle θ and the transmission angle φ from Snell's law.
n1 · sin θ = n2 · sinφ (3)
From the relationship of the above equation (3) and θb + φ = π / 2, the Brewster angle θb can be obtained by the following equation.
tan θb = n2 / n1 (4)
If the measurement environment is in the atmosphere, the refractive index n1 of air can be approximated to 1, so the above equation (4) can be approximated to the following equation.
tan θb = n2 (5)
The Brewster angle calculation unit 32 calculates the Brewster angle θb using the above equation (5).

FIG. 3 is a flowchart showing a procedure for measuring the scratch resistance using the measuring apparatus 10. A procedure for measuring the scratch resistance using the measuring apparatus 10 will be described along the flow shown in FIG. Here, a case where the scratch resistance of a painted surface for an automobile body is measured is taken as an example.
In step S2, first, a sample (sample) 100 having a painted surface for an automobile body is prepared. As shown in FIG. 4, in a sample 100 having a painted surface for an automobile body, a paint layer 104 containing a color pigment or a glittering material, a colorless and transparent clear coat layer 102, etc. on a substrate 106 made of aluminum or the like. Is formed. The prepared sample 100 is placed on the sample stage 14 of the measuring apparatus 10.
In step S4, the optical refractive index at the sample surface 100a is input using the input device 42 or the like. Here, the optical refractive index of the clear coat layer 102 forming the sample surface 100a is input. The optical refractive index of the clear coat layer 102 can be measured in advance. In general, the optical refractive index of the clear coat layer 102 on the painted surface of an automobile body is often in the range of 1.48 to 1.60. The Brewster angle corresponding to this light refractive index is 56 to 58 degrees.

In step S6, based on the optical refractive index input in step S4, the measuring apparatus 10 makes an angle θ formed by the optical axis Da of the light source 12 and the normal line Db of the sample surface 100a, that is, the incident angle θ of the illumination light 2. Is adjusted to the Brewster angle θb. In the process of step S6, first, the Brewster angle calculation unit 32 of the calculation device 30 calculates the Brewster angle θb based on the input optical refractive index at the sample surface 100a (here, the clear coat layer 102). . For example, when the optical refractive index of the clear coat layer 102 is 1.53, the Brewster angle θb is approximately 57 degrees. Next, the motor controller 26 controls the first motor 22 to adjust the angle θ formed by the optical axis Da of the light source device 12 and the normal Db of the sample surface 100a to the calculated Brewster angle θb. That is, the incident angle θ of the illumination light 2 is adjusted to the Brewster angle θb.
In step S6, it is not always necessary to strictly adjust the incident angle θ of the illumination light 2 to the Brewster angle θb. For example, when the optical refractive index of the clear coat layer 102 is 1.53 and a measurement error of approximately 1% is allowed, the incident angle may be adjusted between 55 degrees and 59 degrees. On the other hand, even when the incident angle is fixed at 57 degrees, if the optical refractive index of the clear coat layer 102 is 1.48 to 1.60, the surface reflected light 4a vibrates in parallel to the incident surface. The ratio of the component is suppressed to within about 1%. That is, if the incident angle is set to 57 degrees, almost all of the surface reflected light 4a can be absorbed by the polarizing filter 20.

  In step S8, as shown in FIG. 5, the brightness of the sample surface 100a is measured with the polarizing filter 20 removed. That is, the intensity of the reflected light 4 reflected by the sample 100 is measured with the polarizing filter 20 removed. The variable angle α for measuring the brightness of the sample surface 100a is not particularly limited, but is preferably in the range of 5 to 30 degrees. In the present embodiment, the lightness at variable angles of 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, and 30 degrees is measured, including the processes of steps S10, S14, and S16 described later. As shown in FIG. 5, the illumination light 2 from the light source 12 enters the sample surface 100a at an incident angle of the Brewster angle θb. A part of the illumination light 2 incident on the sample surface 100 a is reflected on the sample surface 100 a, and a part thereof is diffusely reflected on the clear coat layer 102 or the paint layer 104. The surface reflected light 4a is linearly polarized light having only a component that vibrates perpendicularly to the incident surface. On the other hand, the diffuse reflected light 4b is non-polarized light having no specific vibration direction. In addition, the symbol attached | subjected with the code | symbol p in the figure has shown the component oscillating in parallel with respect to the entrance plane, and the symbol attached | subjected with the code | symbol s in the figure oscillated perpendicularly | vertically with respect to the entrance plane. Shows the ingredients. Both the surface reflected light 4a and the diffuse reflected light 4b are incident on the photometer 18, and the lightness L1 (α) is measured based on the intensities of both the surface reflected light 4a and the diffuse reflected light 4b. The measured brightness L1 (α) is input to the scratch index calculation unit 34 of the calculation device 30.

  In step S10 of FIG. 3, as shown in FIG. 6, the lightness of the sample surface 100a is measured with the polarizing filter 20 attached. That is, the intensity of the reflected light 4 reflected by the sample 100 is measured with the polarizing filter 20 attached. In this case, the surface reflected light 4a is linearly polarized light having only a component that vibrates perpendicularly to the incident surface, and thus is absorbed by the polarizing filter 20. On the other hand, since the diffusely reflected light 4b is non-polarized light having no specific vibration direction, the component oscillating parallel to the incident surface is transmitted through the polarization filter 20. As a result, only the diffusely reflected light 4b is incident on the photometer 18 at half its intensity, and the lightness L2 (α) is measured based on an intensity that is substantially half of the actual intensity of the diffusely reflected light 4b. . The measured brightness L2 (α) is input to the scratch index calculation unit 34 of the calculation device 30.

  In step S12 of FIG. 3, the sample 100 is removed from the measuring apparatus 10, and a scratch forming process is performed on the sample surface 100a. The scratch forming process is a process for artificially forming a scratch on the sample surface 100a. For example, a method of spraying sand particles or the like on the sample surface 100a and rubbing the sample surface 100a with a cloth material or the like can be mentioned. Alternatively, the actual vehicle test may be performed by mounting the sample 100 on the body of the actual vehicle over a predetermined period. The method of scratch formation processing is not particularly limited, and a conventionally used method can be employed. The sample 100 that has been subjected to the scratch forming process is placed on the sample table 14 again. Instead of performing the scratch forming process on the sample 100, another sample (that formed the same painted surface) subjected to the scratch forming process may be prepared. Alternatively, if a scratch forming process is performed in advance on a part of the sample surface 100a, it is only necessary to change the mounting position of the sample 100 on the sample stage 14 in step S12.

  In step S14, as shown in FIG. 7, the brightness of the sample surface 100a after the scratch forming process is measured with the polarizing filter 20 removed. That is, the brightness of the reflected light 4 reflected by the sample 100 after the scratch formation process is measured with the polarizing filter 20 removed. In this step S14, as in the previous step S8, both the surface reflected light 4a and the diffuse reflected light 4b are incident on the photometer 18, and the brightness L3 is obtained by combining the intensities of both the surface reflected light 4a and the diffuse reflected light 4b. (Α) is measured. However, in the sample 100 on which the scratch formation process has been performed, a surface flaw 112 is generated on the sample surface 100 a and an internal flaw 114 is generated inside the sample 100. The surface flaw 112 here means irregularities generated on the sample surface 100a. Further, the internal scratch 114 means white turbidity generated inside the sample 100 (here, the clear coat layer 102). The surface flaw 112 and the internal flaw 114 worsen the appearance of the painted surface, and the coated surface in which both the surface flaw 112 and the internal flaw 114 are less likely to be produced has better scratch resistance. The surface scratch 112 forms a minute reflecting surface on the sample surface 100a. As a result, the intensity of the surface reflected light 4a changes greatly (usually increases) as more surface scratches 112 are formed, particularly in the range of 5 to 30 degrees of deflection. Moreover, since the internal flaw 114 makes the clear coat layer 102 cloudy, the diffuse reflection in the clear coat layer 102 is increased. As a result, the more the internal scratches 114 are formed, the more the intensity of the diffuse reflected light 4b changes (usually increases). Therefore, between the lightness L3 (α) measured in step S14 and the lightness L1 (α) measured in the previous step S8, the lightness change amount dLa (α) caused by the surface scratch 112, A difference due to the lightness change amount dLb (α) due to the internal scratch 114 occurs. That is, L3 (α) −L1 (α) = dLa (α) + dLb (α). This lightness change amount L3 (α) −L1 (α) corresponds to the first lightness change amount described in the claims. For example, depending on the angle of change α for measuring the lightness L1 (α), L3 (α), the lightness change amount dLa (α) caused by the surface flaw 112 and the lightness change amount dLb (α) caused by the internal flaw 114 May cancel out and lightness L1 (α) and lightness L3 (α) may be equal. In the technique of this embodiment, even in such a case, the scratch resistance can be measured correctly. The measured brightness L3 (α) is input to the scratch index calculation unit 34 of the calculation device 30.

  In step S16, as shown in FIG. 8, with the polarization filter 20 attached, the brightness of the sample surface 100a after the scratch forming process is measured. That is, the brightness of the reflected light 4 reflected by the sample 100 after the scratch formation process is measured with the polarizing filter 20 attached. In this step S16, as in the previous step S10, only the component of the diffuse reflected light 4b oscillating parallel to the incident surface is incident on the photometer 18, and the actual brightness of the diffuse reflected light 4b is determined. Approximately half the brightness L4 (α) is measured. Between the lightness L4 (α) measured in step S16 and the lightness L2 (α) measured in the previous step S10, about half of the lightness change amount dLb (α) caused by the internal flaw 114 is obtained. Differences occur. That is, L4 (α) −L2 (α) = dLb (α) / 2. This lightness change amount L4 (α) −L2 (α) corresponds to the second lightness change amount recited in the claims. The measured brightness L4 (α) is input to the scratch index calculation unit 34 of the calculation device 30.

In step S18, the scratch index calculation unit 34 of the calculation device 30 uses the lightness L1 (α), L2 (α), L3 (α), and L4 (α) measured in steps S8, S10, S14, and S16. The first scratch index E1 (α) is calculated. The first scratch index E1 (α) is calculated by the following equation.
E1 (α) = (L3 (α) −L1 (α))
-2 ・ (L4 (α) −L2 (α)) (6)
As is clear from the above description, the first scratch index E1 (α) is equal to the lightness change amount dLa (α) generated in the surface reflected light 4a before and after the scratch formation processing in step S12. That is, the first scratch index E1 (α) quantitatively indicates the surface scratch 112 formed on the sample 100 by the scratch forming process. It can be said that the smaller the absolute value of the first scratch index E1 (α), the better the scratch resistance with respect to the surface scratch 112 (the surface scratch 112 is less likely to be attached).

In step S20, the scratch index calculation unit 34 of the calculation device 30 calculates the second scratch index E2 (α) using the lightness L2 (α) and L4 (α) measured in steps S10 and S16. The second scratch index E2 (α) is calculated by the following equation.
E2 (α) = 2 · (L4 (α) −L2 (α)) (7)
As is clear from the above description, the second scratch index E2 (α) is equal to the lightness change amount dLb (α) generated in the diffuse reflected light 4b before and after the scratch formation processing in step S12. That is, the second scratch index E2 (α) quantitatively indicates the internal scratch 114 formed on the sample 100 by the scratch forming process. It can be said that the smaller the absolute value of the second scratch index E2 (α), the better the scratch resistance with respect to the internal scratch 114 (the internal scratch 114 is less likely to be attached).
In step S22, the first scratch index E1 (α) calculated in step S18 and the second scratch index E2 (α) calculated in step S20 are displayed on the display device 40.

9 to 12 show an example of measurement results obtained by the measurement apparatus 10. FIG. 9 shows the measurement results of the lightness L1 (α), L2 (α), L3 (α), and L4 (α) of the first painted surface (sample X). FIG. 10 shows measurement (calculation) results of the first scratch index E1 (α) and the second scratch index E2 (α) of the sample X. FIG. 11 shows the measurement results of the lightness L1 (α), L2 (α), L3 (α), and L4 (α) of the second painted surface (sample Y). FIG. 12 shows measurement (calculation) results of the first scratch index E1 (α) and the second scratch index E2 (α) of the sample Y. In addition, in FIGS. 9-12, although all the measurement results in each variable angle of 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, and 30 degrees are displayed, when evaluating the measurement results, It is sufficient to pay attention only to the measurement result of one variable angle (for example, 20 degrees).
When FIG. 9 and FIG. 11 are compared, the measured brightness L1 (α), L2 (α), and L3 (α) are the same between sample X and sample Y, but only the brightness L4 (α) is different. Specifically, the brightness L4 (α) measured with the sample X is larger than the brightness L4 (α) measured with the sample Y. In such a case, for example, if measurement using the polarizing filter 20 is not performed, only the amount of change between the lightness L1 (α) and the lightness L3 (α) is compared, and the scratch resistance of both is equivalent. The conclusion is reached. On the other hand, according to the measuring apparatus 10 of the present embodiment, as is apparent from comparison between FIGS. 10 and 12, the samples X and Y can obtain different scratch indices E1 (α) and E2 (α). . From the measurement results shown in FIGS. 10 and 12, it is found that the sample X is more likely to have the surface flaw 112 and the inner flaw 114 is less likely to be attached than the sample Y.

  According to the measuring apparatus 10 of the present embodiment, the degree of the surface scratch 112 and the internal scratch 114 formed on the sample 100 by the scratch forming process can be quantified independently. Thereby, for example, the evaluation of the scratch resistance of the painted surface or the like can be performed separately from the surface scratch 112 and the internal scratch 114. Since the surface flaw 112 and the internal flaw 114 have different formation mechanisms, the measures for reducing their formation are also different. If it is found that the scratch resistance is inferior with respect to the surface scratch 112, it is possible to take measures suitable for reducing the formation of the surface scratch 112. In addition, if it is found that the scratch resistance is poor with respect to the internal scratch 114, it is possible to take measures suitable for reducing the formation of the internal scratch 114. By feeding back the scratch resistance measured using the measuring apparatus 10 to a paint developer or a coating process designer, it is possible to realize a coated surface having excellent scratch resistance.

In the technique of the present embodiment, the incident angle θ of the illumination light 2 is not necessarily limited to the Brewster angle θb, and as a result, the surface reflected light 4a may include a component that vibrates parallel to the incident surface. When the incident angle θ of the illumination light 2 is set to a predetermined angle, the Fresnel coefficients Rs and Rp shown in the above equations (1) and (2) can be calculated from the incident angle θ and the light refractive index at the sample surface 100a. . If the Fresnel coefficients Rs and Rp are found, the proportion of the component that vibrates in parallel to the incident surface in the surface reflected light 4a is found. When this ratio is Q, Q = Rp / (Rs + Rp), and 0 ≦ Q <0.5. In this case, the lightness L1 (α), L2 (α), L3 (α), and L4 (α) measured in steps S8, S10, S14, and S16 in FIG.
L1 (α) = La (α) + Lb (α)
L2 (α) = La (α) · Q + Lb (α) / 2
L3 (α) = La (α) + dLa (α) + Lb (α) + dLb (α)
L4 (α) = (La (α) + dLa (α)) · Q + (Lb (α) + dLb (α)) / 2
In the above formula, La indicates the lightness corresponding to the intensity of the surface reflected light 4a, and Lb indicates the lightness corresponding to the intensity of the diffusely reflected light 4b. Further, dLa (α) indicates a brightness change amount corresponding to the intensity change of the surface reflected light 4a caused by the formation of the surface scratch 112, and dLb (α) indicates the diffuse reflected light 4b caused by the formation of the internal scratch 114. The brightness change amount corresponding to the intensity change is shown. From the lightness L1 (α), L2 (α), L3 (α), and L4 (α), the lightness change amount dLa (α) caused by the surface flaw 112 and the lightness change amount dLb caused by the internal flaw 114 are And can be calculated as:
dLa (α) = (L3 (α) −L1 (α)) / (1-2 · Q)
-2 · (L4 (α) -L2 (α)) / (1-2 · Q) (8)
dLb (α) = 2 · (L4 (α) −L2 (α)) / (1-2 · Q)
-2 · Q (L3 (α) -L1 (α)) / (1-2 · Q) (9)
Therefore, in step 18 of FIG. 3, the first scratch index E1 (α) = dLa (α) can be calculated by using the above-described equation (8). In Step 20 of FIG. 3, the second scratch index E2 (α) = dLb (α) can be calculated by using the above-described equation (9). Expressions (8) and (9) are generalized expressions (6) and (7) with respect to an arbitrary incident angle θ. By using the equations (8) and (9), the first scratch index E1 (α) and the second scratch index E2 (α) are correctly set without adjusting the incident angle θ of the illumination light 2 to the Brewster angle θb. Can be measured. In this case, instead of the Brewster angle calculation unit 32, means for calculating the ratio Q = Rp / (Rs + Rp) of the component that vibrates parallel to the incident surface in the surface reflected light 4a may be added. This ratio Q can be calculated using the incident angle θ of the illumination light 2 and the light refractive index at the sample surface 100a. When this method is employed, a mechanism for adjusting the incident angle of the illumination light 2 is not necessary.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
For example, in the above-described embodiment, the first lightness change amount L3 (α) −L1 (α) and the second lightness change amount L4 (α) −L2 (α) that are measured (calculated) are used, and the first scratch index E1. Although (α) and the second scratch index E2 (α) are calculated and displayed, it is not always necessary to calculate the first scratch index E1 (α) and the second scratch index E2 (α). Using the measured brightness L1 (α), L2 (α), L3 (α), L4 (α), the first brightness change amount L3 (α) −L1 (α) and the second brightness change amount L4 (α) −. L2 (α) may be calculated and displayed. If the first lightness change amount L3 (α) -L1 (α) and the second lightness change amount L4 (α) -L2 (α) are determined, the degree of the formed surface flaw 112 and the degree of the internal flaw 114, respectively. Can be grasped quantitatively.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The schematic diagram which shows the structure of the measuring apparatus of an Example. The figure explaining the polarization state of surface reflection. The flowchart which shows the procedure which measures abrasion resistance quantitatively. The figure which illustrates the composition of the painting surface. The figure which shows a mode that the brightness of a sample is measured (before a scratch formation process, without a polarizing filter). The figure which shows a mode that the brightness of a sample is measured (before a scratch formation process, with a polarizing filter). The figure which shows a mode that the brightness of a sample is measured (after a scratch formation process, without a polarizing filter). The figure which shows a mode that the brightness of a sample is measured (with a polarizing filter after an abrasion formation process). The figure which shows the example of a measurement of a brightness (sample X). The figure which shows the example of a measurement of a scratch index (sample X). The figure which shows the example of a measurement of a brightness (sample Y). The figure which shows the example of a measurement of a scratch index (sample Y).

Explanation of symbols

10: measuring device 12: light source 14: sample table 16: rotating table 18: photometer 20: polarization filter 22: first motor 24: second motor 26: motor controller 30: calculation device 32: Brewster angle calculation unit 34 : Scratch index calculation unit 40: display device 42: input device

Claims (7)

An apparatus for quantitatively measuring scratches formed on an object surface,
Illuminating means for irradiating illumination light at a predetermined incident angle on the object surface;
First brightness measuring means for measuring the brightness of the object surface illuminated by the illumination means;
Second brightness measuring means for measuring the brightness of the object surface illuminated by the illuminating means via a polarizing filter that absorbs a component oscillating perpendicular to the incident surface;
The first brightness change amount between the brightness of the object surface before scratch formation measured by the first brightness measurement means and the brightness of the object surface after scratch formation measured by the first brightness measurement means, and the second brightness measurement Means for calculating a second brightness change amount between the brightness of the object surface before scratch formation measured by the means and the brightness of the object surface after scratch formation measured by the second brightness measurement means;
A measuring apparatus comprising:   The calculating means calculates at least one of a first scratch index obtained by subtracting the second lightness change amount from the first lightness change amount and a second scratch index obtained by doubling the second lightness change amount. The measuring apparatus according to claim 1.   The measuring apparatus according to claim 1, wherein an incident angle of the illumination light is substantially equal to a Brewster angle of the object surface. Input means for inputting a refractive index of light on the object surface;
Brewster angle calculation means for calculating the Brewster angle of the object surface based on the light refractive index input by the input means;
Adjusting means for adjusting the incident angle of the illumination light to the Brewster angle calculated by the Brewster angle calculating means;
The measuring apparatus according to claim 3, further comprising: The first brightness measurement means and the second brightness measurement means are configured using a common photometer,
5. The measuring apparatus according to claim 1, wherein the polarizing filter is detachable between the common photometer and the object surface.   3. The measuring apparatus according to claim 1, wherein an incident angle of the illumination light is approximately 57 degrees. A method for quantitatively measuring scratches formed on the surface of an object,
A first brightness measurement step for measuring the brightness of the object surface when the illumination light is irradiated at a predetermined incident angle on the object surface before the formation of the scratch;
The brightness of the object surface when the illumination surface is irradiated with illumination light at a predetermined incident angle is measured through a polarizing filter that absorbs a component that vibrates perpendicularly to the illumination light incident surface. A second brightness measurement step;
A third brightness measurement step for measuring the brightness of the object surface when illumination light is irradiated at a predetermined incident angle on the object surface after the formation of scratches;
The brightness of the object surface when the illumination surface is irradiated with illumination light at a predetermined incident angle is measured through a polarizing filter that absorbs a component that vibrates perpendicularly to the illumination light incident surface. A fourth brightness measurement step;
Measured by the first brightness change amount between the brightness measured by the first brightness measurement process and the brightness measured by the third brightness measurement process, the brightness measured by the second brightness measurement process, and the fourth brightness measurement process. A calculation step of calculating a second brightness change amount between the determined brightness,
A measuring method comprising:

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