Measuring the color of a target coating

Abstract

Apparatus and methods for measuring the color of a target coating are provided. In one exemplary embodiment, a color measurement apparatus includes a housing configured to be disposed on a target coating. A source connected to the housing directs a beam of electromagnetic radiation toward the target coating at an entrance angle. A spherical coordinate system is used, where the entrance angle is a polar angle measured from the zenith normal to the surface of the target coating. A first detector and a second detector are connected to the housing at a first polar angle and a second polar angle, respectively, to measure electromagnetic radiation reflected by a population of flakes within the target coating, where all flakes in the population of flakes have the same angled flake normal polar angle. The first polar angle is different than the second polar angle.

Description

Technical Field

[0001] This technical field relates to coating technology, and more specifically to methods and color measuring devices for measuring the color of a target coating. Background Technology

[0002] Automobiles, vehicles, and other items are typically painted to provide corrosion protection and an attractive appearance. However, different batches of coating can have slightly different hues. When an automotive coating is damaged, such as due to an accident, the repaired parts need to be repainted with paint that matches the original coating. The color of the original target coating can be measured, but the presence of effect pigments such as interference effect pigments and reflective flakes makes matching the overall appearance of the target coating challenging. Interference effect pigments produce a pearlescent effect. Coatings can be measured at several different angles for approximate color matching, but the different effects produced by reflective flakes and interference effect pigments within the target coating are difficult to match. There is no known measuring device that can accurately and consistently distinguish between reflective flakes and interference effect pigments.

[0003] Current measuring devices illuminate a target coating with light at one or more angles and then measure the intensity of the reflected light at one or more angles. Since the light is incident on the target coating at a certain angle (such as 45°), specular lines are defined as having the same and opposite angles. Some devices measure light at +15 and -15 degrees to specular lines, but these devices are understood to be measuring light in a mirror plane that includes both the light source and the specular lines. Devices measuring light at +15 and -15 degrees to specular lines are measuring the reflection of a thin sheet with different angles relative to lines perpendicular to the coating surface, a point explained in more detail below. Therefore, these devices confuse reflected light from reflective sheets with interference effects, making it difficult to distinguish between the different effects.

[0004] Therefore, it is desirable to provide an apparatus and method capable of measuring the color of a target coating and distinguishing between reflective flakes and interference-effect pigments. Additionally, it is desirable to provide an apparatus and method for determining the amount of reflective flakes and interference-effect pigments in a target coating, as well as the type of interference flakes, thereby providing accurate appearance matching. Furthermore, other desirable features and characteristics will become apparent from the following summary and detailed description of the invention, the appended claims, and in conjunction with the accompanying drawings and this background art. Summary of the Invention

[0005] Apparatus and methods for measuring the color of a target coating are provided. In one exemplary embodiment, the color measuring apparatus includes a housing configured to be disposed on the target coating. A source is connected to the housing and an electromagnetic radiation beam is directed to the target coating at an angle of entry. A spherical coordinate system is used, where the target coating surface is a reference plane, the origin is the point around which the beam strikes the target coating surface, and the zenith is a line perpendicular to the coating surface. The angle of entry is the polar angle measured from the zenith, and the beam is defined as having an azimuth of 0. A first detector is connected to the housing and disposed to measure electromagnetic radiation reflected by a group of sheet targets within the target coating, wherein all sheets in the group of sheet targets have the same angled sheet normal polar angle, and the first detector is disposed at a first polar angle. A second detector is connected to the housing and disposed to measure electromagnetic radiation reflected by the group of sheet targets, wherein the second detector is disposed at a second polar angle different from the first polar angle.

[0006] In another embodiment, a method for measuring the color of a target coating is provided. The method includes irradiating the target coating with an electromagnetic radiation beam at an angle of entry, wherein a spherical coordinate system is used. The target coating surface is a reference plane, the origin is the point around which the beam strikes the target coating surface, and the zenith is a line perpendicular to the coating surface. The angle of entry is the polar angle measured from the zenith, and the beam is defined with an azimuth of 0. The target coating comprises flakes, wherein a group of flake targets is defined by all flakes having the same angled flake normal polar angle, and wherein the group of flake targets has multiple flake normal azimuth angles. The intensity of electromagnetic radiation reflected from the group of flake targets having a first flake normal azimuth angle is measured. The intensity of electromagnetic radiation from the group of flake targets having a second flake normal azimuth angle, wherein the second flake normal azimuth angle is different from the first flake normal azimuth angle, is also measured.

[0007] Another embodiment provides a different method for measuring the color of a target coating. The method involves irradiating the target coating with an electromagnetic radiation beam at an angle of entry, wherein a spherical coordinate system is used. The target coating surface is a reference plane, the origin is the point around which the beam strikes the target coating surface, and the zenith is a line perpendicular to the coating surface. The angle of entry is the polar angle measured from the zenith, wherein the beam is defined as having an azimuth of 0. The target coating comprises sheets, wherein a group of sheet targets is defined by all sheets having the same angled polar angle, wherein the beam irradiates the group of sheet targets. The intensity of the electromagnetic radiation is measured using a detector arranged at a first polar angle measured from the zenith, wherein the first detector is arranged to receive electromagnetic radiation reflected from the beam by the group of sheet targets. The intensity of the electromagnetic radiation is also measured using a second detector arranged at a second polar angle measured from the zenith, wherein the second polar angle is different from the first polar angle. The second detector is also arranged to receive electromagnetic radiation reflected from the beam by the group of sheet targets. Attached Figure Description

[0008] The present disclosure will be described below in conjunction with the following figures, wherein the same numerals denote the same elements, and wherein:

[0009] Figure 1 It is a spherical coordinate system diagram used as a reference for angle measurement.

[0010] Figure 2 An exemplary embodiment demonstrating the thin film within the target coating is shown;

[0011] Figure 3 It is a side cross-sectional view showing the light intensity of the target coating when irradiated by a beam at different angles;

[0012] Figure 4 and 5 It is a side cross-sectional view depicting different implementations of an electromagnetic radiation beam propagating around and through the target coating;

[0013] Figure 6 This is a side cross-sectional view depicting an exemplary embodiment of a color measuring device mounted on a target coating;

[0014] Figure 7 The illustration shows an embodiment of the polar angle and azimuth angle of a beam of light reflected from an angled group of target slabs, wherein the angled group of target slabs is defined by a constant angled polar angle.

[0015] Figure 8 It is a graph showing the relationship between light intensity and wavelength measured at three different exit angles for the target coating, with the target coating being irradiated at an entry angle of 45 degrees.

[0016] Figure 9 This is an exemplary curve showing the intensity of electromagnetic radiation measured by two different detectors, plotting the relationship between intensity and wavelength of the electromagnetic radiation; and

[0017] Figure 10 This is a flowchart for determining the matching coating formulation for the target coating. Detailed Implementation

[0018] The following detailed description of the invention is not intended to limit this description or its application and use. Furthermore, it is not intended to be bound by any theories presented in the foregoing background or the following detailed description of the invention. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0019] The term "color data" or "color measurement data" for coatings can include measured color data, including spectral reflectance values; X, Y, Z values; L*, a*, b* values, where L* represents lightness, a* represents color from green (-) to red (+), and b* represents color from blue (-) to yellow (+); L*, C*, h* values, where L* represents lightness, C* represents chromaticity, and h* represents hue; flop index; or combinations thereof. Color data may also include the vehicle's color code, color name, or description, or combinations thereof. Color data can even further include visual aspects of the coating's color, chromaticity, hue, lightness, or darkness. Color data can be obtained visually or through color measurement devices such as colorimeters, spectrophotometers, and angle spectrophotometers. In particular, spectrophotometers obtain color data by determining the amount of light reflected, transmitted, or otherwise produced by the coating within a certain wavelength range. Color data may also include descriptive data, such as color names and vehicle color codes; binary, encrypted, or cryptographic data files containing descriptive data for one or more colors; measurement data files, such as those generated by a color measuring device; or export / import data files generated by a computing device or color measuring device. Color data may also be generated by a color-appearance dual measuring device.

[0020] This description includes several references to various angles using a spherical coordinate system. The scheme used to describe these angles will refer to... Figure 1 Let me explain. "Reference plane 2" is a plane defined by two axes and used as a reference for other measurements. Figure 1 In this context, reference plane 2 is defined by the X and Y axes. "Origin 3" is the point where the X, Y, and Z axes intersect, and "Zenith 4" is a line extending from origin 3 perpendicular to reference plane 2. A point is placed in space, and a theoretical "vector line 6" is drawn from origin 3 to that point, where the vector line represents the distance from the origin to that point. "Polar angle 8" is the angle measured from zenith 4 to vector line 6, while "azimuth 10" is the angle of the orthogonal projection of vector line 6 onto reference plane 2, measured from a fixed reference object on reference plane 2. Figure 1 The fixed reference point is the X-axis. Several points can have the same polar angle 8. If the lengths of the vector lines 6 are the same, these points will form a circle around the zenith 4.

[0021] refer to Figure 2 And continue to refer to Figure 1The target coating 12 has a surface 14 that serves as a reference plane 2 for a spherical coordinate system. Reflective flakes are arranged within the target coating 12 in a slightly randomized manner, wherein the flakes have thin cross-sections and much larger top and bottom surface areas. The flakes have flake normals 21, which are perpendicular to the larger top and bottom surfaces of the flakes. In many embodiments, a large number of parallel flakes 16 are parallel to the surface 14 of the target coating 16, so that the flake normals of the parallel flakes 16 are zenith 4. The polar angle of the flakes is measured from the flake normals, so the parallel flake normal polar angle 18 of the parallel flakes 16 is 0°, measured from zenith 4 to the parallel flake normals, which are also zenith 4. The target coating 12 also includes angled flakes 20, wherein the angled flakes 20 are not parallel to the surface 14 of the target coating 16. Therefore, the angled slab 20 has an angled slab normal polar angle 22 greater than 0, measured from the zenith 4 to the angled slab normal 21. In some embodiments, as the polar angle of the slab increases, the number of slabs with constant polar angles (but different slab normal azimuth angles 23) decreases. The “slab normal azimuth angle 23” is the azimuth angle of the slab normal 21, and this azimuth angle 23 is used to define the rotational position of the slab around the zenith line 4 or a line parallel to the zenith line 4. A group of slab targets can be defined with a constant polar angle 8, so all slabs in the target group have the same polar angle 8 but various different slab normal azimuth angles 23.

[0022] refer to Figure 3 And continue to refer to Figure 1 and 2 Conventional color measurement devices combine a light beam or electromagnetic radiation beam with multiple detectors positioned at selected angles, where the detectors detect the intensity of electromagnetic radiation within a certain wavelength range. Figure 3 In the example of the conventional color measuring apparatus shown, the source 30 is positioned to emit a beam 32 with an entry angle 34 of 45 degrees (45°), where the entry angle 34 is the polar angle of the beam 32. The source 30 and the beam 32 are defined with an azimuth angle 10 of zero. A specular line 36 is the line generated when the beam 32 is reflected away from the surface 14 of the target coating 12; therefore, in the illustrated embodiment, the specular line 36 has a specular angle 38 of 45° and an azimuth angle of 180°. The specular angle 38 is the polar angle of the specular line 36.

[0023] The beam 32 strikes the target coating 12, and the light is reflected from the slabs within the target coating 12, where the light is reflected at angles that are the same as and opposite to the angle of incidence of the light on the slab surface. The target coating 12 comprises multiple slabs at various slab angles. The intensity of the reflected light is represented by a directionality term 24, where directionality term 24 represents the light intensity measured from the origin 3 at each angle. A vector (not shown) extending from the origin 3 to a point on directionality term 24 illustrates the intensity of the reflected light at the polar angle 8 and azimuth angle 10 of that vector. The length of the vector (or the distance from the origin 3) represents the light intensity, where a longer distance indicates a greater intensity. Figure 3 The directional term 24 is an ellipse. Diffuse light is also generated from the target coating 12, and the intensity of this diffuse light is called the diffuse term 26. The diffuse light is emitted with approximately the same intensity in all directions, so the diffuse term 26 is represented as a dashed semicircle around the midpoint at the origin 3. The total intensity term 28 is the sum of the directional term 24 and the diffuse term 26.

[0024] In conventional color measurement devices, detectors have been placed in multiple locations, with reference mirror line 36 indicating the detector's position. For example, as Figure 3 As shown, the term "45AS15°" refers to a position 15° (denoted as 15°) from the specular line 36 (referred to as "AS (asspecular)," meaning specular), where the beam 32 strikes the target coating 12 at an angle of entry of 45 (referred to as "45"). A detector positioned on the vector marked "45AS110" will measure diffuse light from the diffuser item 26, but essentially no reflected light from the directional item 24. Detectors positioned on the vectors marked "45AS-15°" and "45AS15°" will measure some diffuse light from the diffuser item 26 and some reflected light from the directional item 24. A detector positioned on the vector marked "45AS25°" will measure diffuse light from the diffuser item 26, but less directional light 24 from the directional item compared to detectors positioned at "45AS15°" or "45AS-15°". Conventional color measuring devices typically include detectors positioned at the “45AS-15°” position, the “45AS15°” position, and one or more other positions more than 15° from the mirror line 36. Conventional color measuring devices have detectors positioned above and below the mirror line 36 at the same angle, and detectors positioned above and below the mirror line 36 at different angles are described below.

[0025] refer to Figure 4 and 5 And continue to refer to Figure 1-3The angled sheet 20 reflects light that is the same as and opposite to the surface of the angled sheet 20, but is not reflected in the same and opposite way by the target coating surface 14 because the angled sheet 20 is not parallel to the target coating surface 14. The angled sheets 20 of the target group with constant polar angles will have multiple different sheet normal azimuth angles 23. For simplicity in this specification, Figure 4 and 5 An angled sheet 20 with sheet normal azimuth angles 23 of 180° and 0° is shown. It should be understood that, although not shown, there are other angled sheets 20 with the same polar angle. Figure 4 and 5 Angled sheets 20 are represented as lines, where these figures are oriented to display the XZ plane in two dimensions. The larger top and bottom surfaces of the angled sheets 20, having azimuth angles of 0° or 180°, are... Figure 4 and 5 The views are aligned in the image, so they do indeed appear as a simple line.

[0026] Figure 4 The first angled sheet 20A is shown. Figure 5 A second angled sheet 20B is shown, wherein the first angled sheet 20A and the second angled sheet 20B have the same angled sheet normal polar angle 22, but the sheet normal azimuth angles 23 are 0 degrees and 180 degrees, respectively. The first angled sheet 20A has the first sheet normal azimuth angle (not shown separately because the first sheet normal azimuth angle is 0 degrees and...) of the plurality of sheet normal azimuth angles 23 of the sheet target group. Figure 4 (Not visible in the middle). The second angled sheet 20B has the second sheet normal azimuth angle (not shown separately because the second sheet normal azimuth angle is 180 degrees and in the group of sheet targets) of the plurality of sheet normal azimuth angles 23. Figure 5 (Not visible in the image). As described above, the normal azimuth angles of the first and second sheets shown are 180° and 0°, but in other embodiments, the normal azimuth angles of the first and second sheets can be other angles, as long as they are different from each other.

[0027] Source 30 directs an electromagnetic radiation beam 32 to the target coating 12, with the beam 32 at an entry angle 34. The origin 3 is located at the point around which the beam 32 impacts the surface 14 of the target coating 12, but theoretically, the origin 3 can be moved to account for the travel of the beam 32 within the target coating 12. Therefore, the origin 3 is located at the point where the polar angle is measured from the surface 14, and the positional difference between the points where the beam 32 enters and exits the target coating 12 is small, such that the origin 3 is in approximately the same position, although... Figure 4 and Figure 5 The image is shown in two different locations. The entry angle 34 is the polar angle of the beam 32 measured from the zenith 4. Figure 4 and 5 A mirror plane is shown, which is the plane that includes the zenith 4, the source 30, and the beam 32 before the beam 32 reaches the target coating 12; therefore, the mirror plane is perpendicular to the reference plane 2. An azimuth angle 10 of 0° is defined as the azimuth angle 10 of the source 30, while other azimuth angles 10 are measured from this reference point. The beam 32 is emitted from the source 30 and propagates to the origin 3; therefore, the beam 32 is also defined as having an azimuth angle of 0°. Figure 4 and 5 It includes two different zenith lines 4, both perpendicular to the surface 14 of the target coating 12, and each of them is used to indicate the polar angle in a different aspect.

[0028] The beam 32 is electromagnetic radiation and may have wavelengths in the visible spectrum (i.e., light) and / or other wavelengths. The beam 32 irradiates the target coating 12 and the thin sheets within the target coating 12. The specular line 36 is a line representing the beam 32 reflected away from the surface 14 of the target coating 12 as described above. The specular line 36 also represents the beam 32 reflected away from the parallel thin sheet 16; therefore, the specular angle 38 is the same as the angle of entry 34 (because light reflects at the same and opposite angles to the incident light), but the specular angle 38 has an azimuth angle of 180°. In short, the angle of entry 34 and the specular angle 38 are the same, but extend in opposite directions from the zenith 4.

[0029] As the beam 32 enters and exits the target coating 12, the beam 32 is refracted (i.e., bent). This refraction changes the angle at which the incident beam 32 contacts the angled sheet 20. When the beam 32 reaches the angled sheet 20, it is reflected off the surface of the angled sheet 20 at an angle that is both the same as and opposite to the angle of incidence of the beam 32 on the angled sheet 20. Figure 4 and 5 In the illustrated embodiment, the entry angle 34 is 45°, the mirror angle is 45°, and the polar angle 22 of the angled sheet is approximately 4.2°, wherein the polar angle 22 of the angled sheet is measured from the sheet normal 21 to the zenith 4 as described above. Of course, in alternative embodiments, these components can have other angles. When the beam 32 enters the target coating 12, it is refracted (bent), reflected off the angled sheet 20, and then refracted again as it leaves the target coating 12, so that the beam 32 exits the target coating 40 with an exit ray at an exit angle 40. (Note: In...) Figure 4 In this context, the first emitted ray is represented by the number 42A, and the first emitted angle is represented by the number 40A. Figure 5In this context, the exiting ray is the second exiting ray indicated by numeral 42B, and the exiting angle is the second exiting angle indicated by numeral 40B. The “target group” of lamellae is defined herein as a group of angular lamellae 20 that all have substantially the same angular lamellae normal polar angle 22, but have various different lamellae normal azimuth angles 23. In one exemplary embodiment, the individual angular lamellae normal polar angle 22 is defined as a value of + / - 0.5°. Thus, in the example shown, the angular lamellae normal polar angle 22 is 3.7 to 4.7°, or 4.2° + / - 0.5°. In alternative embodiments, the individual angular lamellae normal polar angle 22 is + / - 0.3° or + / - 0.1°.

[0030] The beam 32, referred to herein as “light”, is reflected from the target group and exits the target coating 12 at different exit angles 40A, 40B and / or azimuth angles depending on the different sheet normal azimuth angles of the target group. Figure 6 The diagram shows the exit angle 40 (i.e., polar angle) and associated azimuth 23 of a group of angularly angled slabs with a normal polar angle 22 of 4.2, and a beam 32 with an entry angle 34 of 45° at an azimuth angle of 0°. Figure 7 In the diagram, the polar angle is displayed on the horizontal axis, with concentric circles representing a given polar angle. The azimuth angle of the slice is displayed around the perimeter of the graph, with radial lines representing a given azimuth angle. As shown, the polar entrance angle 34 of the beam is 45° (along the concentric circles to the horizontal axis), and the azimuth angle is 0° (along the radial vertical lines to the "0" at the top of the graph). It can be seen that the minimum exit angle 40 (polar angle) of the illustrated embodiment is 30°, referred to here as the first exit angle 40A, and the maximum exit angle 40 of the illustrated embodiment is approximately 64°, referred to here as the second exit angle 40B.

[0031] Return to reference Figure 4 and 5 And continue to refer to Figure 1 , 2 6 and 7 Figure 4 The diagram shows a first exit angle of 30°, 40°A. Figure 5 The diagram shows a second emission angle 40B of approximately 64°. The first emission angle 40A and the second emission angle 40B are generated by a first angled thin plate 20A and a second angled thin plate 20B of a target group having normal azimuth angles of 180° and 0°, respectively. In this example, the mirror angle 38 is 45°. Interestingly, for... Figure 4 and 5 The angles defined between the first and second outgoing rays 42A and 42B and the mirror line 36 have different values. Figure 4In this case, the first exit angle 40A is 30°, producing a first exit ray 42A extending from near the origin 3, and the mirror angle is 45°. Therefore, the angle formed by the first exit ray 42A and the mirror line 36 is 15° (i.e., 45° - 30° = 15°). This angle can be called the positive non-mirror exit angle 44. However, in Figure 5 In this configuration, the second exit angle 40B is approximately 64°, generating a second exit ray 42B extending from near the origin 3, and the mirror angle remains at 45°. Therefore, the angle formed by the second exit ray 42B and the mirror line 36 is approximately 19° (i.e., 64° - 45° = 19°). This angle can be referred to as the negative non-mirror exit angle 46. Thus, the first exit ray 42A and the second exit ray 42B from the target group of the angled sheet 20 have different positive non-mirror exit angles 44 and negative non-mirror exit angles 46. In one exemplary embodiment, the negative non-mirror exit angle 46 is greater than the positive non-mirror exit angle 44.

[0032] refer to Figure 8 And refer to Figure 1-3 . Figure 8 This is a graph showing the light intensity measured at different angles, with an angle of entry of 45°. The wavelength of the light is shown on the X-axis, and the light intensity from the sum of the diffuse term 26 and the directional term 24 is shown on the Y-axis. Figure 8 The graph shows three lines: 45AS-15 line 90, 45AS+15 line 92, and 45AS-19 line 94. Lines 45AS+15 line 92 and 45AS-19 line 94 show the intensity of reflected light leaving effect pigment flakes with the same polar angle 8. In other words, lines 45AS+15 line 92 and 45AS-19 line 94 show the intensity of reflected light leaving the target group of flakes. Line 45AS-15 line 90 shows a higher light intensity than the other two lines shown because it measures the intensity of light reflected from flakes with different and smaller polar angles (normal polar angle 22). Line 45AS+15 line 90 uses... Figure 3 The measurement is performed using the scheme described herein; therefore, for the exemplary embodiment with an entry angle of 45° 34, line 92 of 45AS+15 corresponds to a polar angle of 30° 8. Similarly, for the same embodiment, line 90 of 45AS-15 corresponds to a polar angle of 60° 8, and line 92 of 45AS-19 corresponds to a polar angle of 64° 8. The offset between line 92 of 45AS+15 and line 94 of 45AS-19 is explained below.

[0033] The exemplary embodiment described above utilizes a target coating 12 with a refractive index of approximately 1.5. However, similar results can be observed for different refractive indices, where the measurement angles may differ from those described above. Therefore, for a group of targets with target coatings 12 having different refractive indices and angled sheets 20 having a constant angled sheet normal polar angle 22, the maximum and minimum emission angles 40 (e.g., Figure 7 (As shown) will have different values ​​than those mentioned above, but the positive non-mirror exit angle 44 and the negative non-mirror exit angle 46 will still be different, and Figure 7 The general shape of the exit angle 40 in the diagram will be the same. The exemplary embodiments described are for reference only and are not intended to be limiting.

[0034] Now for reference Figure 6 And continue to refer to Figure 1-5 7. In an optional embodiment, the target coating 12 is overly applied to the substrate 50, but in an alternative embodiment, the target coating 12 may be removed from the substrate 50. In an exemplary embodiment, a color measuring device 52 for measuring the color of the target coating 12 includes a housing 54 configured to hold the target coating 12, a source 30 for generating a beam 32, and a plurality of detectors configured to detect the intensity of electromagnetic radiation. As used herein, the term “overly applied” means directly on and in contact with, or above, such that an intervening component or space may be located between the overlying component and a lower component. The source 30 and each of the plurality of detectors are connected to the housing 54. The source 30 is connected to the housing 54 such that the beam 32 is directed to the target coating 12 at an angle of entry 34. As used herein, the term “connected” means directly or indirectly connected such that the source 30 can be mounted in the housing 54, or the source 30 can be indirectly fixed in a location within the housing 54, such as by a bracket, wire, or other type of connector. The positions of the source 30 and the detector define the angled sheet normal polar angle 22 of the target group of sheet pieces being measured, so different groups of sheet pieces can be measured by moving the source 30 and / or the detector. Each different group of sheet pieces has a constant angled sheet normal polar angle 22, but the angled sheet normal polar angle 22 of each different group of sheet pieces is different.

[0035] A first detector 56 is connected to housing 54 and positioned to measure the intensity of electromagnetic radiation reflected from the target group at a first polar angle 58. A second detector 60 is connected to housing 54 and positioned to measure the intensity of electromagnetic radiation reflected from the target group at a second polar angle 62, wherein the first polar angle 58 and the second polar angle 62 are different from each other. In one exemplary embodiment, the first polar angle 58 is the same as the first emission angle 40A, so the first detector 56 can be positioned along the first emission ray 42A. In one exemplary embodiment, the second polar angle 62 is the same as the second emission angle 40B, so the second detector 60 can be positioned along the second emission ray 42B. The first emission ray 42A can be defined between the first detector 56 and the origin 3, and the second emission ray 42B can be defined between the second detector 60 and the origin 3. However, in alternative embodiments, the first polar angle 58 and / or the second polar angle 62 may differ from the first exit angle 40A and / or the second exit angle 40B, wherein the first detector 56 and / or the second detector 60 may be connected to the housing 54 at azimuth angles other than 180°, either in or outside the mirror plane. The first detector 58 and the second detector 62 are positioned to measure reflections from a group of targets within the angled sheet 20; therefore, the first detector 58 and the second detector 62 are positioned in… Figure 7 The location indicated on the ellipse diagram.

[0036] The interference sheet acts as a filter, and its color changes with the angle of incidence of the incoming light. (Reference) Figure 4 and 5 The angle of incidence of the first angled sheet 20A is smaller than that of the second angled sheet 20B. Therefore, assuming the angled sheets 20 are interference sheets, the colors of the reflected light from the first outgoing ray 42A and the second outgoing ray 42B are different. The number of angled sheets 20 in the target coating 10 can be determined at least in part by evaluating the intensity measured by the first detector 56 and the intensity measured by the second detector 60. Furthermore, the amount of interference effect from the target coating 12 can be determined by comparing the intensity measured by the first detector 58 and the second detector 62, respectively, and thus the amount of interference effect pigment (if present) in the target coating 12.

[0037] Refer again Figure 6 And continue to refer to Figure 1-5 7. The color measuring device 52 may also include an optional third detector 64, and in various embodiments may include additional detectors. The third detector 64 is positioned at a third polar angle 66. The third polar angle 66 differs from either the first polar angle 58 or the second polar angle 62. The optional third detector 64 can be used to measure color data of the target coating 12, such as L*, a*, b* data, or other color data known to those skilled in the art.

[0038] The azimuth angle 10 of the first detector 56 and / or the second detector 60 can be the same, such as 180 degrees in one exemplary embodiment, but the normal azimuth angles 23 of the first and second sheets are different from each other, even though the azimuth angle 10 of the first detector 56 and the second detector 60 can be the same. Figure 4 , 5 In the embodiment shown in Figure 6, the normal azimuth angle of the first sheet is 0 degrees, and the reflection from the first angled sheet 20A is measured by the first detector 56 at an azimuth angle 10 of 180 degrees. The normal azimuth angle of the second sheet is 180 degrees (opposite to the 0 degrees of the first angled sheet 20A), and the reflection from the second angled sheet 20B is measured by the second detector 60 at an azimuth angle 10 of 180 degrees (the same as the azimuth angle 10 of the first detector 56).

[0039] Due to the principle of optical path reciprocity, the source 30 and the detector can be interchanged with the same result. In one exemplary embodiment, the color measurement device 52 may include multiple sources 30 and a single detector, all of which are arranged in accordance with... Figure 6 The opposite is true as shown in the diagram. However, the plurality of sources 30 can be activated at different times, so the single detector detects the light intensity from only one source 30 at a time. The interchangeability of the sources 30 and the detector applies to the various embodiments described herein.

[0040] Interference effects can be detected when reflections from a single sheet target group are measured at two (or more) different sheet normal azimuth angles 23. In the above description, the first detector 56 and the second detector 60 can simultaneously measure the intensity of electromagnetic radiation (during which time source 30 is activated and beam 32 is projected onto target coating 12). In an alternative embodiment, reflections from the sheet target group can be measured at a first sheet normal azimuth angle at a first time, then source 30 can be moved to change the angle of entry 34. Reflections from the sheet target group can then be measured at a second sheet normal azimuth angle at a second time, later than the first time. The same detectors can even be used at both the first and second times to measure the intensity of reflected electromagnetic radiation, possibly without moving the detectors, and reflections from the target group can still be measured at different first and second sheet normal azimuth angles. Thus, in some embodiments, the intensity of electromagnetic radiation reflected from the target group is measured at the same time at different sheet normal azimuth angles 23, while in other embodiments, measurements are performed at different times.

[0041] refer to Figure 9 And continue to refer to Figure 1-8The intensity of electromagnetic radiation measured by the first detector 56 and the second detector 60 is graphically displayed as a first curve 70 and a second curve 72, where the "Y" axis represents intensity and the "X" axis represents the wavelength of electromagnetic radiation. It can be seen that the first curve 70 and the second curve 72 are similar, but there is an offset or shift between them. This is similar to what was described above. Figure 8 The shift observed is caused by interference effect pigments in the target coating 12. As described above, the interference sheet acts as a filter and changes color with the incident angle of the incoming light. The first detector 56 and the second detector 60 are positioned at different polar angles, so they measure the reflections from the target group of sheets with different incident angles from the beam 32, thus measuring different colors if the target group includes the interference sheet.

[0042] The amount and type of interference effect pigment can be estimated by determining the offset magnitude of the first curve 70 and the second curve 72, and by determining the peak intensities of the first curve 70 and the second curve 72, respectively. The offset magnitude can be determined in various ways and can be manipulated using computers, software, and other electronic data. In one exemplary embodiment, the first curve 70 is mathematically offset towards the second curve 72 (or vice versa, where the second curve 72 is offset towards the first curve 70) by one unit, and the result is evaluated to determine whether the offset produces alignment. In one exemplary embodiment, the first curve 70 is offset by a wavelength of one nanometer, where one nanometer is the aforementioned "unit," but in alternative embodiments, other units or offset increments may be used. After the first curve 70 is offset by one unit, the process of offsetting the first curve 70 is repeated until the first curve 70 and the second curve 72 are aligned. When the first curve 70 is offset too far, an increase in misalignment relative to the previous offset is found. Therefore, optimal alignment can be found by incrementally offsetting one curve towards the other until the alignment begins to deteriorate. The measurement of the offset is an exemplary method for comparing the intensity of electromagnetic radiation measured by the first detector 52 and the second detector 54.

[0043] In one exemplary embodiment, a first curve peak 74 is evaluated to determine the wavelength of the electromagnetic radiation, where the wavelength of the electromagnetic radiation corresponds to the color of the interference effect pigment. In an alternative embodiment, a second curve peak 76 is evaluated to determine the color. If the target coating 10 does not contain the interference effect pigment but does contain reflective flakes, then during measurement, the first curve 70 and the second curve 72 will be aligned and there will be no offset between them. Therefore, measuring the intensity of electromagnetic radiation reflected from the target group of angled flakes 20 at two different angles allows the color measuring device 52 to distinguish the reflective flakes in the target coating 12 from the interference effect pigment.

[0044] The color measuring device 52 described above can be used to determine the matching coating formulation of the target coating 12. Figure 10 The method 78 for determining a matching coating formulation is illustrated. Step 80 includes measuring color measurement data for multiple different coatings, wherein the coating formulations for said multiple different coatings are known. The color measurement data is measured using the color measuring device 52 described above. In step 82, the color measurement data for said multiple different coating colors is recorded in a database. Step 84 includes measuring color measurement data for the target coating 12 as described above to obtain target coating color measurement data. In step 86, the target coating color measurement data is compared with the color measurement data in the database to locate the matching recorded color measurement data. The matching color measurement data corresponds to a known matching coating formulation that can be used to match the appearance of the target coating 12. This method allows the user to accurately find a matching coating formulation for the target coating 12 containing reflective flakes and / or interference effect pigments, which can help match coatings on damaged vehicles or coatings from original equipment manufacturers (OEMs).

[0045] While at least one embodiment has been given in the foregoing detailed description of the invention, it should be understood that numerous variations exist. It should also be understood that the embodiments(s) are merely exemplary and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed description of the invention will provide a convenient roadmap for those skilled in the art to implement the embodiments, and it should be understood that various changes can be made to the function and arrangement of the elements described in the embodiments without departing from the scope set forth in the appended claims and their legal equivalents.

Claims

1. A color measuring device, comprising: A housing, wherein the housing is configured to be disposed on a target coating comprising a sheet; A source for generating electromagnetic radiation is connected to the housing, wherein the source is positioned to direct an electromagnetic radiation beam toward a target coating at an angle of entry, wherein a spherical coordinate system is used, wherein the surface of the target coating is the reference plane of the spherical coordinate system, the origin of the spherical coordinate system is the point around which the beam strikes the surface of the target coating, the zenith of the spherical coordinate system is a line perpendicular to the coating surface, wherein the angle of entry is a polar angle measured from the zenith, and wherein the beam is defined as having an azimuth of 0. A first detector is connected to the housing and positioned to measure electromagnetic radiation reflected by a group of sheet targets within a target coating, wherein all sheets in the group of sheet targets have the same angled sheet normal polar angle, and the first detector is positioned at a first polar angle; and A second detector is connected to the housing and positioned to measure electromagnetic radiation reflected by a group of thin-film targets, wherein the second detector is positioned at a second polar angle, and wherein the second polar angle is different from the first polar angle. The mirror line extends from the target coating surface at a mirror angle, wherein the mirror angle is an polar angle equal to the angle of entry, wherein the azimuth angle of the mirror line is 180°, wherein the positive non-mirror exit angle is defined as the angle between the mirror line and the first exit ray, wherein the first exit ray extends from the first detector to the origin, and wherein the negative non-mirror exit angle is defined as the angle between the mirror line and the second exit ray extending from the origin to the second detector, wherein the negative non-mirror exit angle is greater than the positive non-mirror exit angle.

2. The color measuring device according to claim 1, wherein: The first detector is configured to measure electromagnetic radiation reflected by a group of thin-film targets having a first azimuth angle. and The second detector is configured to measure electromagnetic radiation reflected by a group of thin-film targets having a second azimuth angle different from that of the first thin-film.

3. The color measuring device according to claim 1, wherein the mirror plane is defined as a plane including the source and the zenith, and wherein: The first detector is located in the mirror plane.

4. The color measuring device according to claim 3, wherein the second detector is disposed in the mirror plane.

5. A method for measuring the color of a target coating, comprising: An electromagnetic radiation beam is used to irradiate a target coating at an angle of entry, wherein a spherical coordinate system is used, wherein the surface of the target coating is the reference plane of the spherical coordinate system, the origin of the spherical coordinate system is the point around which the beam strikes the surface of the target coating, the zenith of the spherical coordinate system is a line perpendicular to the coating surface, wherein the angle of entry is the polar angle measured from the zenith, wherein the beam is defined as having an azimuth of 0, wherein the target coating comprises flakes, wherein a group of flake targets is defined by all flakes in the group of flake targets having the same angled flake normal polar angle, and wherein the group of flake targets has multiple flake normal azimuth angles; Measure the intensity of electromagnetic radiation reflected from a group of thin-film targets having a first thin-film normal azimuth among the plurality of thin-film normal azimuths; and The intensity of electromagnetic radiation reflected from a group of thin-plate targets having a second normal azimuth angle among the plurality of thin-plate normal azimuth angles, wherein the second normal azimuth angle is different from the first normal azimuth angle, is measured. The mirror line extends from the target coating surface at a mirror angle, wherein the mirror angle is an polar angle equal to the angle of entry, wherein the azimuth angle of the mirror line is 180°, wherein the positive non-mirror exit angle is defined as the angle between the mirror line and the first exit ray, wherein the first exit ray extends from the first detector to the origin, wherein the first detector measures the intensity of electromagnetic radiation reflected from a group of sheet targets having a first sheet normal azimuth angle, wherein the negative non-mirror exit angle is defined as the angle between the mirror line and the second exit ray extending from the origin to the second detector, wherein the second detector measures the intensity of electromagnetic radiation reflected from a group of sheet targets having a second sheet normal azimuth angle, and wherein the negative non-mirror exit angle is greater than the positive non-mirror exit angle.

6. The method according to claim 5, wherein: The measurement of electromagnetic radiation reflected from a group of thin-film targets with a first azimuth angle and the measurement of electromagnetic radiation reflected from a group of thin-film targets with a second azimuth angle occur simultaneously.

7. The method according to claim 5, further comprising: A first curve is formed by plotting the first intensity relative to the wavelength of electromagnetic radiation, wherein the first intensity is the intensity of electromagnetic radiation reflected from a group of thin-film targets having a first azimuth angle normal to the thin film. A second curve is formed by plotting the second intensity relative to the wavelength of the electromagnetic radiation, where the second intensity is the intensity of the electromagnetic radiation reflected from the group of thin-film targets having a second azimuth normal angle; and Determine the offset of the first curve relative to the second curve.

8. The method of claim 7, further comprising: Determine the peak value of the first curve; and The color of the interference effect pigment in the target coating is determined from the peak value of the first curve.

9. The method according to claim 5, further comprising: The angle of entry is changed between (1) measuring the electromagnetic radiation reflected from the group of thin-plate targets with a first azimuth angle and (2) measuring the electromagnetic radiation reflected from the group of thin-plate targets with a second azimuth angle.

Images