JP2008064654A - Color measuring apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately grasp an optical reflectance in a direction coinciding with an incidence direction of illuminating light. <P>SOLUTION: A color measuring apparatus includes: an illuminating means for making the illuminating light incident at an incidence angle of 45 degrees on to the surface of an object; a light receiving means for receiving reflection light reflected by the surface of the object at a bending angle of 25 degrees; a light receiving means for receiving reflection light reflected by the surface of the object at a bending angle of 45 degrees; a light receiving means for receiving reflection light reflected by the surface of the object at a bending angle of 75 degrees; an arithmetic means for computing respective optical reflectance values in directions of the bending angles of 25 degrees, 45 degrees and 75 degrees at the object surface, based on the intensity of reflection light received by each light receiving means; and an estimating means for computing an estimation value R90 of the optical reflectance in the direction of the bending angle of 90 degrees at the object surface by using the optical reflectance values R25, R45 and R75 in the directions of the bending angles of 25 degrees, 45 degrees and 75 degrees which are computed respectively. The estimation value R90 satisfies the following equation: R90=3×R25/4-7×R45/4+2×R75. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for measuring the color of an object.

Paints for automobile bodies are roughly classified into solid paints mainly composed of color pigments and metallic paints mainly composed of color pigments and glittering materials. The painted surface on which the solid paint is applied looks almost uniform regardless of changes in the light source position and the viewpoint position. On the other hand, the color of the painted surface to which the metallic paint is applied changes depending on the light source position and the viewpoint position.
For the expression of colors that change according to the position of the light source or the viewpoint, such as the color of the painted surface with metallic paint applied, the positional relationship between the light source and the viewpoint is defined by the variable angle, and the color of the object surface is described for each variable angle. To be done. The variable angle is an angle formed by a regular reflection direction in which illumination light from a light source is regularly reflected on an object surface and an observation direction in which reflected light from the object surface is observed from a viewpoint.

In order to describe the color of the object surface for each angle change, it is necessary to measure the light reflectance of the object surface for each angle change. FIG. 4 shows a state in which the light reflectance of the sample 100 that has been painted for an automobile body is measured at each change angle. In the sample 100, a coating layer 104 including a color pigment and a bright material, a colorless and transparent clear layer 102, and the like are formed on a base 106. In the measurement of the light reflectance, the sample surface (painted surface) 100a is illuminated by the light source 2, and the reflected light 8 reflected by the sample surface 100a is received by the light receiver 9. Then, from the intensity change between the illumination light 4 and the reflected light 8, the light reflectance of the sample surface 100a is calculated. In the figure, Da indicates the incident direction of the illumination light 4, Db indicates the normal direction of the sample surface 100a, Dc indicates the regular reflection direction of the illumination light 4, and Db is obtained by the light receiver 9. The light receiving direction is shown. The angle formed by the incident direction Da and the normal direction Db (here 45 degrees) indicates the incident angle of the illumination light 4, and the angle α formed by the regular reflection direction Dc and the light receiving direction Db indicates a variable angle. In order to measure the light reflectivity for each variable angle, it is necessary to receive the reflected light 8 in each variable angle α direction while changing the position of the light receiver 9 or arranging a plurality of light receivers 9. There is.
In the measurement shown in FIG. 4, in order to measure the light reflectivity in the direction of 90 degrees of change, it is necessary to measure the intensity of the reflected light 8 a in the direction of 90 degrees of change, and the light receiver 9 is connected to the illumination light 4. It is necessary to arrange in the incident direction Da. When the light receiver 9 is arranged in the incident direction Da of the illumination light 4, the light receiver 9 is interposed between the light source 2 and the sample 100 or the light source 2 is interposed between the light receiver 9 and the sample 100. It will be. If the light receiver 9 is interposed between the light source 2 and the sample 100, the illumination light 4 from the light source 2 is blocked by the light receiver 9, and the light source 2 cannot illuminate the sample surface 100a. Alternatively, if the light source 2 is interposed between the light receiver 9 and the sample 100, the reflected light 8a from the sample surface 100a is blocked by the light source 2, and the light receiver 9 reflects the reflected light 8a from the sample surface 100a. Cannot be received. Thus, the light reflectivity in the direction of the variable angle (90 degrees here) coinciding with the incident direction Da of the illumination light 4 cannot be physically measured.

Patent Document 1 describes a technique for estimating the light reflectance of a metallic coating film. In this technology, first, the metallic coating film is illuminated with illumination light with an incident angle of 45 degrees, and the light reflectances in five directions with varying angles of 15 degrees, 25 degrees, 45 degrees, 75 degrees, and 110 degrees are measured. To do. Then, a regression equation describing the relationship between the angle change and the light reflectance is obtained using the measured light reflectance in the five directions. By using this regression equation, it is possible to calculate the light reflectivity in an arbitrary direction in which the deflection angle is 10 degrees to 110 degrees. According to this technique, it is also possible to estimate the light reflectivity in the direction of the variable angle of 90 degrees that coincides with the incident direction of the illumination light.
Japanese Patent Laid-Open No. 10-010045

In the technique of Patent Document 1, it is assumed that the light reflectance changes linearly in the range where the angle of change is 80 degrees to 110 degrees. Therefore, in the range where the angle change is 80 degrees to 110 degrees, the relationship between the angle change and the light reflectance is approximated by a single linear expression. In the technique of Patent Document 1, the relationship between the angle change and the light reflectance is simplified too much, and the light reflectance in the direction in which the angle change becomes 90 degrees cannot be accurately estimated.
The present invention solves the above problems. The present invention provides a technique that makes it possible to accurately grasp the light reflectance in a direction that coincides with the incident direction of illumination light.

  The technique of the present invention can be embodied in a colorimetric apparatus that measures the color of an object surface. This color measuring device includes an illuminating unit that makes illumination light incident on an object surface from a direction with an incident angle of 45 degrees, a light receiving unit that receives reflected light reflected on the object surface in a direction with an angle of variation of 25 degrees, and an angle of change 45 on the object surface. A light receiving means for receiving the reflected light reflected in the direction of the angle, a light receiving means for receiving the reflected light reflected in the direction of the variable angle of 75 degrees on the object surface, and the surface of the object based on the intensity of the reflected light received by each light receiving means Means for calculating the light reflectance in the direction of 25 degrees, 45 degrees and 75 degrees, and the light reflectance R25 and 45 degrees in the calculated direction of 25 degrees. There is provided an estimation means for calculating an estimated value R90 of the light reflectivity in the direction of 90 ° change of the object surface using the light reflectivity R45 in the direction and the light reflectivity R75 in the direction of change of 75 °. The estimated value R90 substantially satisfies R90 = 3 · R25 / 4-7 · R45 / 4 + 2 · R75.

FIG. 3 is a graph schematically showing the result of measuring the light reflectance R (λ) of the object surface for each variable angle α by making illumination light incident on the object surface from the direction of an incident angle of 45 degrees. The present inventor has found that the following relationship holds for the behavior when the light reflectance R (λ) of the object surface changes in accordance with the angle of change α. That is, the change rate of the light reflectivity R (λ) when the variable angle changes from 25 ° to 45 ° is A1, and the light reflectivity R (λ (λ) when the variable angle changes from 45 ° to 75 °. ) Is A2, and the change rate of the light reflectance R (λ) when the change angle is changed from 75 degrees to 90 degrees is A3, the change amount between the change ratio A1 and the change ratio A2 It has been found that the amount of change between A2-A1 and the rate of change A2 and rate of change A3 is substantially equal. It has been confirmed that this relationship is effectively established for an arbitrary wavelength λ. In summary, the following formula is established.
A1 = (R45 (λ) −R25 (λ)) / (45-25) (1);
A2 = (R45 (λ) −R75 (λ)) / (75−45) (2);
A3-A2 = A2-A1 (3);
Therefore, the light reflectivity in the direction of 90 ° change is the light reflectivity R25 (λ) in the direction of 25 ° change, the light reflectivity R45 (λ) in the direction of 45 ° change, and 75 ° change. From the light reflectance R75 (λ) in the direction, the estimated value R90 (λ) can be calculated by the following equation.
R90 (λ) = R75 (λ) + A3 · (90−75)
= R75 (λ) + (2 · A2-A1) · 15
= 3 · R25 (λ) / 4-7 · R45 (λ) / 4 + 2 · R75 (λ);
According to this color measuring device, illumination light can be incident on the object surface from the direction of the incident angle of 45 degrees, and the light reflectance in the direction of the angle of change of 90 degrees on the object surface can be accurately estimated. By using this color measuring device, it is possible to accurately grasp the light reflectance in the direction that coincides with the incident direction of the illumination light.

In the above colorimetric apparatus, each of the light receiving means preferably receives the reflected light for each of a plurality of wavelength ranges. In this case, it is preferable that the calculation unit calculates a light reflectance in each of the variable angle directions for each of the plurality of wavelength regions, and the estimation unit calculates the estimated value for each of the plurality of wavelength regions.
When the light receiving means receives the reflected light from the object surface in multiple wavelength ranges and can measure the intensity of the reflected light in multiple wavelength ranges, it calculates the light reflectivity of the object surface in multiple wavelength ranges. can do. That is, the spectral reflectance of the object surface can be calculated. If the light reflectance in the direction of the angle of deviation 25, 45, 75 degrees is found for each of a plurality of wavelength ranges, the direction of the angle of deviation of 90 degrees is obtained by using the relationship of the above formulas (1), (2), (3). Can be estimated for each of a plurality of wavelength regions. That is, it is possible to estimate the spectral reflectance of the object surface in the direction of 90 ° change. If the spectral reflectance can be estimated, it is possible to quantitatively estimate the brightness, saturation, and hue when the object surface is viewed from the direction of the angle of 90 degrees.
Even when the light reflectance of the object surface is not distinguished for each wavelength range, it is possible to quantitatively estimate at least the lightness of the object surface in the direction of the 90-degree deflection.

The technique of the present invention can also be embodied in a method for measuring the color of an object surface. In this color measurement method, the illumination light is incident on the object surface from the direction of the incident angle of 45 degrees, the reflected light reflected from the object surface in the direction of the variation angle of 25 degrees is received, and the variation angle of the object surface is the direction of 45 degrees The step of receiving the reflected light reflected to the object surface, the step of receiving the reflected light reflected in the direction of the angle of deviation of 75 degrees on the object surface, and the variable angle 25 of the object surface based on the intensity of the reflected light received in each light receiving step. The step of calculating the light reflectance in the direction of 45 degrees, the direction of 45 degrees, and the direction of 75 degrees, the light reflectance R25 in the direction of 25 degrees and the light reflectance in the direction of 45 degrees A step of calculating an estimated value R90 of the light reflectivity in the direction of 90 ° change of the object surface using R45 and the light reflectivity R75 in the direction of change of 75 ° is provided. The estimated value R90 substantially satisfies R90 = 3 · R25 / 4-7 · R45 / 4 + 2 · R75.
According to this color measurement method, illumination light can be incident on the object surface from the direction of an incident angle of 45 degrees, and the light reflectance in the direction of the 90-degree change angle of the object surface can be accurately estimated. By using this color measurement method, it is possible to accurately grasp the light reflectance in the direction that coincides with the incident direction of the illumination light.

  According to the present invention, it is possible to more accurately grasp the color that changes depending on the light source position and the viewpoint position.

First, the main features of the embodiments described below are listed.
(Feature 1) The color measurement device includes a halogen lamp that illuminates the object surface.
(Characteristic 2) The color measurement device includes five light receivers. The first light receiver is provided at a position for receiving the reflected light reflected in the direction of the variable angle of 15 degrees on the object surface. The second light receiver is provided at a position for receiving the reflected light reflected in the direction of the variable angle of 25 degrees on the object surface. The third light receiver is provided at a position for receiving the reflected light reflected in the direction of the variable angle of 45 degrees on the object surface. The fourth light receiver is provided at a position for receiving the reflected light reflected in the direction of the variable angle of 75 degrees on the object surface. The fifth light receiver is provided at a position for receiving the reflected light reflected in the direction of the variable angle of 110 degrees on the object surface. Each light receiver outputs a signal corresponding to the intensity of the received reflected light.
(Characteristic 3) The color measurement device includes a display for displaying a measured value of light reflectance in each direction of change of the object surface and an estimated value of light reflectivity in the direction of 90 degrees of change of the object surface. Yes.

A color measuring device embodying the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing the configuration of the color measuring device 10. As shown in FIG. 1, the color measurement device 10 is a portable color measurement device that can be carried by a user, and is placed on the sample surface 100 a that is a color measurement target, and the spectrum of the sample surface 100 a. This is a device for measuring reflectance.
The color measuring device 10 includes a housing 12 having a size that can be carried by a user. The housing 12 is provided with an operation button 14 that is operated by a user, a display unit 16 that displays an operation state, a measurement result, and the like of the color measurement device 10.

A dome-shaped measurement chamber 20 is provided inside the housing 12. The lower part of the measurement chamber 20 is open to the outside, and the measurement chamber 20 faces the sample surface 100a when the color measuring device 10 is placed on the sample surface 100a. The measurement chamber 20 is provided with a light source 28, a first light receiver 21, a second light receiver 22, a third light receiver 23, a fourth light receiver 24, and a fifth light receiver 25.
The light source device 28 is a light source for illuminating the sample surface 100a. Illumination light (solid arrow in the figure) 4 irradiated by the light source device 28 enters the measurement surface 100 a facing the measurement chamber 20. For the light source device 28, for example, a halogen lamp can be used.
Each of the light receivers 21 to 25 receives the reflected light (broken arrow in the figure) 8 reflected at the measurement point P on the sample surface 100 a and outputs a signal corresponding to the intensity of the reflected light 8. Each of the light receivers 21 to 25 includes a plurality of light receiving elements. Each of the plurality of light receiving elements is provided with a color filter of a different color. Each of the light receivers 21 to 25 receives the reflected light 8 for each of a plurality of wavelength ranges by a plurality of light receiving elements, and outputs a signal corresponding to the intensity of the reflected light 8 for each wavelength range. Each light receiver 21-25 is arrange | positioned in a mutually different position. Each of the light receivers 21 to 25 receives the reflected light 8 reflected at the measurement point P on the sample surface 100a in different directions.

With reference to FIG. 2, the positional relationship of the light source device 28 and each light receiver 21-25 is demonstrated. As shown in FIG. 2, the incident axis Da connecting the light source device 28 and the measurement point P on the sample surface 100a forms an angle of 45 degrees with respect to the normal direction Db of the sample surface 100a. That is, the illumination light 2 emitted from the light source device 28 is incident on the measurement point P on the sample surface 100a from a direction having an incident angle of 45 degrees. Dc in the figure indicates the regular reflection direction of the illumination light 2 at the measurement point P on the sample surface 100a. The regular reflection direction Dc forms an angle of 45 degrees on the side opposite to the incident axis Da with respect to the normal direction Db of the sample surface 100a.
The first light receiver 21 is located in a direction that forms an angle of 15 degrees from the regular reflection direction Dc toward the normal direction Db when viewed from the measurement point P on the sample surface 100a. In other words, the first light receiver 21 is arranged in the direction of the variable angle of 15 degrees. The first light receiver 21 receives the reflected light 8 reflected in the direction of the variable angle of 15 degrees at the measurement point P on the sample surface 100a.
The second light receiver 22 is positioned in a direction that forms an angle of 25 degrees from the regular reflection direction Dc toward the normal direction Db when viewed from the measurement point P on the sample surface 100a. That is, the second light receiver 22 is disposed in the direction of the variable angle of 25 degrees. The second light receiver 22 receives the reflected light 8 reflected at the measurement point P on the sample surface 100a in the direction of the variable angle of 25 degrees.
The third light receiver 23 is located in a direction that forms an angle of 45 degrees from the specular reflection direction Dc toward the normal direction Db when viewed from the measurement point P on the sample surface 100a, and the measurement point P on the sample surface 100a. It is located on the normal line direction Db. In other words, the third light receiver 23 is arranged in the direction of the variable angle 45 degrees. The third light receiver 23 receives the reflected light 8 reflected at the measurement point P on the sample surface 100a in the direction of 45 degrees.
The fourth light receiver 24 is located in a direction that forms an angle of 75 degrees from the regular reflection direction Dc toward the normal direction Db when viewed from the measurement point P on the sample surface 100a. That is, the fourth light receiver 24 is disposed in the direction of the variable angle of 75 degrees. The fourth light receiver 24 receives the reflected light 8 reflected at the measurement point P on the sample surface 100a in the direction of the variable angle of 75 degrees.
The fifth light receiver 110 is located in a direction that forms an angle of 110 degrees from the regular reflection direction Dc toward the normal direction Db when viewed from the measurement point P on the sample surface 100a. That is, the fifth light receiver 25 is arranged in the direction of the variable angle 110 degrees. The fifth light receiver 25 receives the reflected light 8 reflected in the direction of the variable angle of 110 degrees at the measurement point P on the sample surface 100a.

As shown in FIG. 1, the color measurement device 10 includes a processing circuit 34. The processing circuit 34 receives the output signals of the light receivers 21 to 25 and calculates the spectral reflectance (reflectance for each wavelength λ) R (λ) of the sample surface 100a for each variable angle. Specifically, using the output signal of the first light receiver 21, the spectral reflectance R15 (λ) of the sample surface 100a in the direction of the 15-degree variation is calculated. Further, using the output signal of the second light receiver 22, the spectral reflectance R25 (λ) of the sample surface 100a in the direction of the variable angle of 25 degrees is calculated. Further, using the output signal of the third light receiver 23, the light reflectance R45 (λ) in the direction of the angle 45 of the sample surface 100a is calculated. Further, using the output signal of the fourth light receiver 24, the spectral reflectance R75 (λ) of the sample surface 100a in the direction of the variable angle of 75 degrees is calculated. Further, using the output signal of the fifth light receiver 25, the light reflectivity R110 (λ) in the direction of the variable angle 110 of the sample surface 100a is calculated.
The processing circuit 34 can calculate various indices describing the color using the calculated spectral reflectance R (λ). For example, using the calculated spectral reflectance R (λ), each index value L ^* , a ^* , b of the CIE 1976 (L ^* , a ^* , b ^* ) color system defined by the International Commission on Illumination (CIE) ^* Can be calculated. Here, the L ^* value is an index describing the brightness of the color. The larger the L ^* value, the brighter the color. The a ^* value is an index that describes the intensity of the color with respect to the red and green hues. A larger a ^* value (positive value) indicates a red hue, and a smaller a ^* value (negative value) indicates a green hue. The b ^* value is an index that describes the intensity for yellow and blue hues. A larger b ^* value (positive value) indicates a yellow hue, and a smaller b ^* value (negative value) indicates a blue hue. Each index value L ^* , a ^* , b ^* varies depending on the angle of change. For example, the difference appears remarkably on the painted surface of the automobile body. The L ^* value, a ^* value, and b ^* value for each inflection obtained by the colorimetric device 10 are taught to a computer graphics (CG) device or the like, and used to reproduce and display the painted surface of an automobile body. be able to.

The processing circuit 34 uses the calculated spectral reflectances R25 (λ), R45 (λ), and R75 (λ) with the variable angles of 25, 45, and 75 degrees to reflect the spectral reflection of the sample surface 100a toward the variable angle of 90 degrees. The rate R90 can be estimated and calculated. Further, by using the calculated brightness indexes L25, L45, and L75 of the variable angles of 25, 45, and 75 degrees, the brightness index L90 of the sample surface 100a in the direction of the variable angle of 90 degrees can be estimated and calculated.
Referring to FIG. 3, the processing circuit 34 uses the spectral reflectances R25 (λ), R45 (λ), and R75 (λ) in the directions of the variable angles 25, 45, and 75 degrees to change the variable angle in the direction of 90 degrees. A method for estimating and calculating the spectral reflectance R90 (λ) of the above will be described. The inventor has studied the behavior when the spectral reflectance changes according to the angle change, and found that the relationship shown in FIG. 3 is established between the angle change and the spectral reflectance. That is, as shown in FIG. 3, when the change rate of the spectral reflectance R (λ) when the variable angle changes from 25 degrees to 45 degrees is A1, and the variable angle changes from 45 degrees to 75 degrees. The change rate of the spectral reflectance R (λ) is A2, and the change rate of the spectral reflectance R (λ) when the angle of change changes from 75 degrees to 90 degrees is A3. Then, it discovered that the variation | change_quantity between change rate A1 and change rate A2 and the variation | change_quantity of change rate A2 and change rate A3 became substantially equal. It has been confirmed that this relationship is effectively established for an arbitrary wavelength λ. Therefore, the spectral reflectance R90 (λ) in the direction of 90 degrees of variation is the spectral reflectance R25 (λ) in the direction of 25 degrees of variation, the spectral reflectance R45 (λ) in the direction of 45 degrees of variation, It is possible to estimate and calculate using the spectral reflectance R75 (λ) in the direction of the variable angle of 75 degrees. In summary, the following equation is established.
A1 = (R45 (λ) −R25 (λ)) / (45-25) (1);
A2 = (R75 (λ) −R45 (λ)) / (75−45) (2);
A3-A2 = A2-A1 (3);
Therefore, the spectral reflectance R90 (λ) in the direction of 90 degrees of deflection is
R90 (λ) = R75 (λ) + A3 · (90−75)
= R75 (λ) + (2 · A2-A1) · 15
= 3 · R25 (λ) / 4-7 · R45 (λ) / 4 + 2 · R75 (λ);
And an estimate can be calculated.
Using the above relationship, the processing circuit 34 uses the measured values R25 (λ), R45 (λ), and R75 (λ) of the spectral reflectances in the directions of the variable angles 25, 45, and 75 degrees to change the variable angle to 90 degrees. Calculate an estimate of the spectral reflectance in the direction.

As is apparent from FIG. 2, when the incident angle of the illumination light 4 is 45 degrees, the direction in which the variable angle becomes 90 degrees, that is, the direction that forms an angle of 90 degrees from the regular reflection direction Dc toward the normal direction Db. Corresponds to the incident axis Da of the illumination light 4. Therefore, in order to measure the spectral reflectance R90 (λ) in the direction of the variable angle of 90 degrees, it is necessary to arrange the light receiver on the incident axis Da of the illumination light 4. In this case, the light source 28, the light receiver, and the measurement point P are aligned on the same straight line (on the incident axis Da), and the light receiver is interposed between the light source 28 and the measurement point P, or the light receiver and the measurement point P. The light source device 28 is interposed between the two. In the former positional relationship, the light receiver cannot receive the reflected light from the measurement point P, and in the latter positional relationship, the light source device 28 cannot illuminate the measurement point P. In any case, the spectral reflectance R90 (λ) in the direction of the 90-degree deflection cannot be physically measured.
The colorimetric device 10 of the present embodiment uses the spectral reflectance R90 (λ) in the direction of 90 degrees of variation that cannot be physically measured, and the spectral reflectance R25 (λ) in the directions of 25, 45, and 75 degrees of variation measured. ), R45 (λ), R75 (λ). According to the color measurement device 10 of the present embodiment, it is possible to grasp the spectral reflectances of the sample surface 100a in the directions 15, 25, 45, 75, 90, and 110 degrees.

Each spectral reflectance R (λ) in the direction of variable angles 15, 25, 45, 75, 90, and 110 degrees calculated by the processing circuit 34 is displayed on the display 16. At this time, the processing circuit 34 calculates each index value L ^* , a ^* , b ^* of the CIE 1976 (L ^* , a ^* , b ^* ) color system based on the calculated spectral reflectance R (λ). It can also be displayed on the display 16.

The above formulas (1) to (3) also hold for the L ^* value describing the lightness of the color in the CIE 1976 (L ^* , a ^* , b ^* ) color system. That is,
B1 = (L45−L25) / (45−25) (4);
B2 = (L75-L45) / (75-45) (5);
B3-B2 = B2-B1 (6);
Is established. In the above equation, L25 represents the ^{L *} value as viewed from the bending 25 degree direction to the sample surface 100a, L45 represents the ^{L *} value as viewed from the bending 45 degree direction to the sample surface 100a, the L75 The L ^* value when the sample surface 100a is viewed from the direction of the bending angle of 75 degrees is shown. B1 represents the rate of change of the L ^* value when the bending is changed to 45 degrees from 25 degrees, B2 represents the rate of change of the L ^* value when the variable angle changes from 45 degrees to 75 degrees, B3 indicates the rate of change of the L ^* value when the angle of change changes from 75 degrees to 90 degrees. Therefore, the lightness L90 when the sample surface 100a is viewed from the direction of the angle change of 90 degrees is
L90 = L75 + B3. (90-75)
= L75 + (2.B2-B1) .15
= L75 + (2.A2-A1) .15
= 3 · L25 / 4-7 · L45 / 4 + 2 · L75;
And an estimate can be calculated.

With the above configuration, the color measurement device 10 is placed on the sample surface 100a such as an automobile body to be measured, and can measure the color of the sample surface 100a. The colorimetric device 10 illuminates the sample surface 100a by the light source device 28, receives the reflected light 8 reflected at the measurement point P on the sample surface 100a by the five light receivers 21 to 25, and changes the angle of change to five angles. Measure the light reflectance. At this time, the colorimetric device 10 can also calculate an L ^* value that describes the lightness when the sample surface 100a is viewed from each angle change direction, from each of the measured reflectances in each angle change direction. The colorimetric device 10 can estimate and calculate the light reflectance of the sample surface 100a in the 90-degree change direction using the light reflectance of the sample surface 100a in the directions of 25, 45, and 75 degrees. it can. Further, using each lightness index ^{L *} value when viewed sample surface 100a from bending 25,45,75 degree direction, a lightness index ^{L *} value when viewed sample surface 100a from bending 90 degree direction Estimate can be calculated. According to the colorimetric device 10, it is possible to grasp the light reflectivity of the sample surface 100a in the direction of 90 ° change and the brightness when the sample surface 100a is viewed from the direction of 90 ° change.

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.
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.

FIG. 2 is a partial cross-sectional view illustrating a configuration of a color measurement device according to an embodiment. The figure which shows the positional relationship of a light source device and each light receiver. The figure explaining the method of estimating the light reflectivity to 90 degrees of variable angles. The figure which shows a mode that a light reflectivity is measured for every variable angle.

Explanation of symbols

10: Color measuring device 12: Housing 14: Operation button 16: Display unit 20: Measurement chamber 21, 22, 23, 24, 25: Light receiver 28: Light source 34: Processing circuit 100: Sample 100a: Sample surface

Claims (3)

Illuminating means for making illumination light incident on the object surface from an incident angle direction of 45 degrees;
A light receiving means for receiving the reflected light reflected from the object surface in the direction of a variable angle of 25 degrees;
A light receiving means for receiving the reflected light reflected from the object surface in the direction of the angle of 45 degrees;
A light receiving means for receiving the reflected light reflected from the object surface in the direction of the variable angle of 75 degrees;
Calculation means for calculating the light reflectances in the direction of 25 degrees, 45 degrees and 75 degrees of the object surface based on the intensity of the reflected light received by each light receiving means;
Using the calculated light reflectivity R25 in the direction of the variable angle of 25 degrees, the light reflectivity R45 in the direction of the variable angle of 45 degrees, and the light reflectivity R75 in the direction of the variable angle of 75 degrees, the direction of the variable angle of 90 degrees An estimation means for calculating an estimated value R90 of light reflectance to
The estimated value R90 is substantially the following equation:
R90 = 3 ・ R25 / 4-7 ・ R45 / 4 + 2 ・ R75
A colorimetric device characterized by satisfying Each of the light receiving means receives the reflected light for each of a plurality of wavelength ranges,
The calculation means calculates the light reflectance in each of the variable angle directions for each of the plurality of wavelength ranges,
The colorimetric apparatus according to claim 1, wherein the estimation unit calculates the estimated value for each of the plurality of wavelength ranges. A color measurement method for an object surface,
A step of making illumination light incident on the object surface from a direction of an incident angle of 45 degrees;
Receiving reflected light reflected from the object surface in the direction of a variable angle of 25 degrees;
Receiving the reflected light reflected from the object surface in the direction of the angle of 45 degrees;
Receiving the reflected light reflected from the object surface in the direction of the variable angle of 75 degrees;
A step of calculating light reflectances in the direction of 25 degrees, 45 degrees and 75 degrees of the object surface based on the intensity of the reflected light received in each light receiving step;
Using the calculated light reflectivity R25 in the direction of the variable angle of 25 degrees, light reflectivity R45 in the direction of the variable angle of 45 degrees, and light reflectivity R75 in the direction of the variable angle of 75 degrees, the direction of the variable angle of the object surface is changed to 90 degrees. Calculating an estimated value R90 of the light reflectance of
The estimated value R90 is substantially the following equation:
R90 = 3 ・ R25 / 4-7 ・ R45 / 4 + 2 ・ R75
A colorimetric method characterized by satisfying the above.

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