Patent ID: 11953431
Assignee: AXALTA COATING SYSTEMS IP CO., LLC
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. A method of measuring color of a target coating comprising:
illuminating the target coating with a beam of electromagnetic radiation at an entrance angle, where a spherical coordinate system is used, where a surface of the target coating is a reference plane of the spherical coordinate system, an origin of the spherical coordinate system is a point about where the beam impacts the surface of the target coating, a zenith of the spherical coordinate system is a line normal to the surface of the target coating, wherein the entrance angle is a polar angle measured from the zenith, wherein the beam is defined with an azimuth angle of 0, wherein the target coating comprises flakes, wherein a target population of flakes is defined by all the flakes in the target population of flakes having the same angled flake normal polar angle, and wherein the target population of flakes have a plurality of flake normal azimuth angles;
measuring an intensity of the electromagnetic radiation reflected from the target population of flakes having a first flake normal azimuth angle of the plurality of flake normal azimuth angles;
measuring the intensity of the electromagnetic radiation reflected from the target population of flakes having a second flake normal azimuth angle of the plurality of flake normal azimuth angles, wherein the entrance angle for the source is the same for measuring the intensity of electromagnetic radiation reflected from the target population of flakes having a first flake normal azimuth angle and for measuring the intensity of the electromagnetic radiation reflected from the target population of flakes having a second flake normal azimuth angle, where the second flake normal azimuth angle is different than the first flake normal azimuth angle; and
wherein a specular line extends from the surface of the target coating at a specular angle, wherein the specular angle is the polar angle equal to the entrance angle, wherein the specular line has the azimuth angle of 180°, wherein a positive aspecular exit angle is defined between the specular line and a first exit line, wherein the first exit line extends from a first detector to the origin, wherein the first detector measures the intensity of the elctromagentic radiation reflected from the target populat of flakes having the first flake normal azimuth angle, wherein a negative aspecular exit angle is defined between the specular line and a second exit line extending from the origin to a second detector, wherein the second detector measures the intensity of the elctromagentic radiation reflected from the target populat of flakes having the second flake normal azimuth angle, and wherein;
the negative aspecular exit angle is greater than the positive aspecular exit angle.