JPH0735615A - Color measuring apparatus for color of object having light source fluctuation correcting function - Google Patents

Abstract

PURPOSE:To achieve a miniaturization and lower cost by curtailing the frequency desired to measure changes in a light source significantly as compared to that in the past maintaining measuring accuracy the same as ever. CONSTITUTION:A light source 2 lights a sample 1 with a Xe light source or the like having a bright line. Changes in the light source 2 are measured with a light source measuring section made up of sensors Fn1Pn1-Fn5Pn5 which comprise spectroscopic filters Fn1-Fn5 arranged facing optoelectric transducers Pn1-Pn5 such as photo diodes respectively. A changing rate of the light source of a wavelength having no bright line is calculated by interpolating a value to be obtained with the sensors Fn1-Pn1-Fn4Pn4 for measuring the wavelength having no bright line. The changing rate of the light source of the wavelength having the bright light is obtained by applying a value to be obtained with the sensor Fn5Pn5 for measuring the wavelength having the bright line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colorimetry for illuminating an object with a white light source, receiving transmitted light or reflected light from the object, and correcting the variation of the illuminating light to measure the color of the object. In particular, the present invention relates to a colorimeter for object color suitable for use in highly accurate color measurement.

[0002]

2. Description of the Related Art Generally, in an object color colorimeter for measuring an object color, a variation in a light source that illuminates a measurement sample is measured for each color measurement, and the color measurement value is corrected in accordance with the variation to achieve high accuracy. I am trying to measure. Therefore, in the case of a light source having a bright line at a specific wavelength such as a Xe (xenon) light source, unlike a stable light source such as a halogen light source, the light source fluctuation is usually measured over all wavelengths in the measurement wavelength range. Need to do.

FIG. 11 is a block diagram showing the structure of a conventional object colorimeter. The sample measuring unit is a spectral filter F1.
-Fn and photoelectric conversion elements P1 such as photodiodes
The sensor is made of Pn and is arranged so that the transmitted light or the reflected light from the sample 1 of the light source 2 is incident.
The light source measuring unit is composed of a sensor composed of spectral filters Fn + 1 to F2n and photoelectric conversion elements Pn + 1 to P2n, measures the fluctuation of the light source 2, and the light of the light source 2 is directly incident on the sensor.
Moreover, it is arranged so that transmitted light or reflected light from the sample 1 does not enter. Sensors F1P1 to Fn of the sample measuring section
Pn and the corresponding sensor of the light source measuring unit Fn + 1Pn + 1 to F2nP
2n has the same spectral sensitivity characteristic. Then, each output current from the sample measuring unit and the light source measuring unit is converted into a voltage by the current-voltage conversion circuit 3 and output, and this output voltage is converted into a digital value by the A / D conversion circuit 4. It is supposed to be output. In this case, since the number of signals is large, the digital conversion needs to be executed by parallel processing. Further, in the calculation unit 70, the output data from the light source measurement unit and the sample measurement unit are adapted to take a ratio between the corresponding sensors, respectively. The stimulus values XYZ are converted and generated. The obtained tristimulus values XYZ are converted into a color space value such as L * a * b * as necessary and displayed on the display unit 60. As in the object colorimeter shown in FIG. 11, when measuring the light source variation in the entire wavelength range, even if the re-irradiation from the sample is included, it is canceled at each measurement. It is possible to measure only the light source fluctuation.

Also proposed is a colorimeter for measuring the light source over the entire wavelength range, in which the number of spectral filters and photoelectric conversion elements for measuring the light source is smaller than that for measuring the sample. (Japanese Patent Laid-Open No. 62-284227).

Further, a system has been proposed in which the pulsed light emission of the light source is stabilized and the light source fluctuation is suppressed by devising the circuit configuration of the colorimeter (Tokusho Sho 58).
-500726).

On the other hand, diffuse illumination / vertical (8
In the light receiving type colorimeter for object color, the light diffused by the integrating sphere may include the re-irradiation from the sample. This is explained in JIS Z8722 regarding the sample opening error. In addition, JP-A-6
Japanese Patent Laid-Open No. 3-305225 discloses a device relating to the position of the light source measurement opening of the integrating sphere. The lower bottom surface of the colorimetric portion is made to be a flat surface so as to contact the sample surface, and the light source measurement opening portion is provided at the end thereof. It has been proposed to reduce the amount of re-irradiation by providing.

[0007]

However, as shown in FIG.
In the conventional colorimeter for object color shown in FIG. 1, a sensor such as a spectral filter for measuring a light source or a photoelectric conversion element and an A / D associated therewith are used.
The same number of processing circuits as the conversion circuits are required for the sample measurement, the processing speed is reduced, and the increase in the number of parts causes an increase in the size and cost of the colorimeter.

Further, in the device described in Japanese Patent Laid-Open No. 62-284227, the number of sensors for measuring the light source is simply reduced, so that it cannot be denied that there is a limit in accuracy.

Further, in the device described in Japanese Patent Publication No. 58-500726, the structure of the device is complicated and the cost is increased.

In addition, JIS Z8722 and Japanese Patent Laid-Open No. 63-
Even with the device described in Japanese Patent No. 305225, it has not been possible to completely eliminate the influence of re-irradiation.

The present invention solves the above-mentioned problems, and while maintaining the same measurement accuracy as the conventional one, the number of wavelengths for measuring the light source fluctuation is greatly reduced as compared with the conventional one, and the size and cost are reduced. It is an object of the present invention to provide a colorimeter for object color having a light source variation correction function.

[0012]

In order to achieve the above object, the present invention illuminates an object with a white light source and receives transmitted light or reflected light from the illuminated object to change the color of the object. In a colorimeter for measurement, a first light source sensor for measuring the light level of each wavelength of a plurality of dispersed wavelength regions among the wavelengths in which the bright line of the irradiation light does not exist, and at least one or more in which the bright line exists Second light source sensor for measuring the light level of the wavelength for each wavelength, measurement data of the first and second light source sensors at the time of calibration, and the first and second light sources at the time of color measurement of the sample object A first light source variation rate at a wavelength measurable by the first light source sensor and a second light source variation rate at a wavelength measurable by the second light source sensor are calculated from sensor measurement data. And the above calculation means Second calculation means for interpolating and calculating a light source variation rate for a wavelength range other than the plurality of dispersion wavelength ranges in the wavelength where no line exists, and the bright line are present. And a third calculation means for calculating the light source variation rate for wavelengths other than at least one wavelength from the second light source variation rate.

[0013]

2 is a characteristic diagram showing the spectral distribution of the Xe light source (A in the figure) and the spectral sensitivity (B in the figure) of the sensor of the light source measuring section of the conventional colorimeter in FIG. The Xe light source is
It has a wavelength at which bright lines exist at 480, 490, 530, 535 and 540 nm. Further, each sensor of the light source measuring unit has a peak wavelength and a half value width (approximately 15 nm) as shown by B in FIG.

The reflectance Rj of the sample at the wavelength j is

[0015]

[Formula 1] Rj = Wj × (Csmj / Cswj) / (Crmj / Crw
j) is required.

However, Wj is the reflectance of the known white calibration plate, Csmj and Cswj are the measured values of the sensor of the sample measuring part when measuring the sample and the white calibration plate, respectively, Crmj and Cr.
wj is the measurement value of the sensor of the light source measurement unit when measuring the sample and the white calibration plate, respectively.

From the reflectance Rj, the tristimulus value of the object color can be calculated by a known calculation. The light source variation rate corresponds to the denominator (Crmj / Crwj) of Equation 1. Here, reduction of the number of sensors for measuring the light source in FIG. 2 will be considered.

FIG. 3 shows a white calibration plate measured 30 times.
It is a characteristic view which shows the change of the measured value of the sensor of a light source measurement part. In FIG. 3, the ratio is based on the first measurement value. The dotted line indicates the measurement value of the sensor that measures the wavelength where the bright line does not exist, and the solid line indicates the measurement value of the sensor that measures the wavelength that the bright line exists. There is. As shown in FIG. 3, the fluctuations in the measured values of both sensors show different tendencies, so it can be seen that the two need to be measured separately.

The wavelength at which the bright line exists depends on the substance enclosed in the tube. The fluctuations of the respective bright lines show almost the same tendency as shown in the figure. It can be seen that measurement is possible with at least one sensor.

On the other hand, it is necessary to dispersively dispose one sensor for measuring wavelengths where there are no bright lines, at least one on the short wavelength side and one on the long wavelength side in order to capture the tendency of the entire variation.

Therefore, it is considered that at least three sensors should be used to measure the light source fluctuation.

Therefore, according to the present invention, the light level of each wavelength is measured for a plurality of dispersed wavelength regions among the wavelengths where the bright line does not exist, and the optical level is measured for at least one wavelength where the bright line exists. The light level at the wavelength is measured. Further, based on the measurement data of the first and second light source sensors at the time of calibration and the measurement data of the first and second light source sensors at the time of color measurement of the sample object, the wavelength that can be measured by the first light source sensor. And the second light source variation rate at the wavelength measurable by the second light source sensor is calculated. Then, the light source fluctuation rate for wavelength bands other than the plurality of dispersed wavelength bands within the wavelength where the bright line does not exist is calculated by interpolation calculation using the first light source fluctuation rate. On the other hand, the light source variation rate for wavelengths other than at least one wavelength in which the bright line exists is calculated from the second light source variation rate.

In this way, since the light source variation rate is obtained over the entire wavelength range, the reflectance is obtained by using each of these values, and the measurement result of the color of the object sample is obtained.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a colorimeter for object color having a light source variation correction function according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a first embodiment of the colorimeter for the same object color.

The light source 2 is a white light source composed of, for example, a Xe light source. The wavelength at which the bright line is generated for this Xe light source has been investigated in advance. The sample measuring unit is a sensor F1 including photoelectric conversion elements P1 to Pn such as photodiodes and spectral filters F1 to Fn arranged facing each other.
It is composed of P1 to FnPn, and is arranged so that the reflected light obtained by reflecting the light from the light source 2 on the sample 1 is incident. The sensors F1P1 to FnPn have the spectral sensitivity characteristics of the peak wavelength and the half width as shown by B in FIG.

The light source measuring section is composed of photoelectric conversion elements Pn1 to Pn5 such as photodiodes, and sensors Fn1Pn1 to Fn5P which are spectral filters Fn1 to Fn5 arranged facing each other.
It consists of n5 and is for measuring the fluctuation of the light source 2,
It is arranged so that the light from the light source 2 directly enters and the reflected light from the sample 1 does not enter.

The sensors Fn1Pn1 to Fn5Pn5 have the same spectral sensitivity characteristics as the sensors corresponding to the wavelengths λ1 to λ5 shown by the arrows in the upper part of FIG. 2 among the sensors F1P1 to FnPn of the sample measuring section. Table 1 shows these sensors.

[0028]

[Table 1]

In Table 1, the sensors Fn1Pn1 and Fn2Pn2
In the sensor Fn3Pn3, Fn4Pn4, the light source fluctuations at the wavelengths λ3 and λ4 where the long wavelength side does not exist and the sensor Fn5Pn5 at the wavelength λ5 where the bright line exists The light source fluctuations are measured respectively.

The sensors F1P1 to FnPn, Fn1P
The n1 to Fn5Pn5 and the light source 2 are arranged at appropriate places in a box-shaped housing formed so as to be able to shield external light.

The current-voltage conversion circuit 3 includes a photoelectric conversion element P1.
.About.Pn and Pn1 to Pn5 are converted into voltages, respectively. The A / D conversion circuit 4 converts the output voltage of the current-voltage conversion circuit 3 into a digital value.

The second arithmetic unit 7 performs the arithmetic operation described later based on the measured value of each sensor input from the A / D conversion circuit 4, and interpolates or corrects the light source variation rate for each wavelength. The light source fluctuation rate of the wavelengths other than the wavelengths λ1, λ2, λ3, and λ4 where there is no bright line is determined by the sensors Fn1Pn1 to Fn4P.
The light source fluctuation rate measured at n4 is calculated by linear interpolation. That is, λ1 <λ <λ2
The light source fluctuation rate of the wavelength λ of is the light source fluctuation rate measured by the sensors Fn1Pn1 and Fn2Pn2, and the light source fluctuation rate of the wavelength λ of λ2 <λ <λ3 is the light source fluctuation rate measured by the sensors Fn2Pn2 and Fn3Pn3. By using the light source variation rate of the wavelength λ of λ3 <λ <λ4, the light source variation rate measured by the sensors Fn3Pn3 and Fn4Pn4 is linearly interpolated and calculated.

On the other hand, for the light source fluctuation rate at wavelengths having bright lines other than the wavelength λ5, that is, 480, 490, 530, and 540 nm, the light source fluctuation rate at the wavelength λ5 measured by the sensor Fn5Pn5, that is, 535 nm is applied as it is. ing.

The first calculation section 5 calculates the reflectance for each wavelength using the light source variation obtained by the second calculation section 7. Further, the first calculation unit 5 calculates L from the calculated reflectance.
It is converted into colorimetric values in various color spaces such as * a * b *. This color space conversion is performed based on the color space conversion system program stored in the ROM 52.

The RAM 52 stores color information such as reflectance of a known white calibration plate, calibration data when the white calibration plate is measured, measurement data of a sample, and the like. RAM71
Stores the light source variation rate and the like obtained by measurement or calculated by interpolation described later. The display unit 6 displays the colorimetric result obtained by the first calculation unit 5 as a numerical value or the like.

The control unit 18 is composed of a microcomputer or the like, and controls the entire operation of the object colorimeter. A keyboard 19 for inputting various data necessary for measurement is connected to the control unit 18. The illumination circuit 21 is driven and controlled by the control unit 18, and the light source 2
Is turned on and off.

Next, the procedure of calculating the reflectance of the first embodiment will be described with reference to FIG. 4 and according to the flowchart of FIG. FIG. 4 is an explanatory diagram showing interpolation of the light source variation rate for each peak wavelength.

It should be noted that the white calibration plate is used for the measurement in advance, and the measured values C of the sensors Fn1Pn1 to Fn5Pn5 of the light source measuring section are measured.
rwi (i = 1 to 5) and sensor F1P1 to F1 of the sample measurement unit
R of measured value Crwj (j: peak wavelength of each sensor) of nPn
It is necessary to store in AM52.

First, the light source 2 is caused to emit light by the illumination circuit 21, and the measured values C of the sensors Fn1Pn1 to Fn5Pn5 of the light source measuring section.
The rmi (i = 1 to 5) and the measured value Crmj (j: peak wavelength of each sensor) of the sensors F1P1 to FnPn of the sample measuring unit by the reflected light from the sample 1 are stored in the RAM 52 (#
1).

Next, the sensor Fn1 obtained in step # 1
From the measured values Crmi (i = 1 to 5) of Pn1 to Fn5Pn5 and the measured value Crwi obtained when the white calibration plate was measured, the light source variation rate Ki = Crmi / Crwi is calculated (# 2). FIG. 4 shows an example of the light source variation rate Ki with respect to the wavelength λi (i = 1 to 5).

Then, using K1 to K4, wavelengths λ1 and
The light source variation rate of the wavelength λj (j: peak wavelength of each sensor of the sample measurement unit) other than λ2, λ3, and λ4 is calculated by linear interpolation (# 3).

For example, in FIG. 4, the wavelength λj (λ1 <λj
The light source variation rate Kj of <λ2) is

[0043]

[Formula 2] Kj = {(K2-K1) .lamda.j + (K1.lamda.2-K2.lamda.)
1)} / (λ2-λ1).

Further, the light source fluctuation rate Kj of the wavelength λj (λ2 <λj <λ3) is

[0045]

[Expression 3] Kj = {(K3-K2) .lambda.j + (K2.lambda.3-K3.lambda.
2)} / (λ3−λ2).

The light source variation rate Kj of the wavelength λj (λ3 <λj <λ4) is

[0047]

[Formula 4] Kj = {(K4-K3) .lambda.j + (K3.lambda.4-K4.lambda.
3)} / (λ4−λ3).

The light source variation rate Kj at the wavelength λj (λ4 <λj ≦ 700 nm) is obtained by an extrapolation method using the value of the wavelength λ4 as it is. That is,

[0049]

## EQU5 ## Calculated by Kj = K4.

With this, the light source fluctuation rate of the peak wavelengths of all the sensors is calculated, and the wavelength at which the bright line exists is also included in this. Therefore, next, the light source variation rate of the wavelength at which the bright line exists is all replaced with K5 (# 4). For example, in FIG. 4, the light source variation rate of the wavelength λi where the bright line exists is K5. As described above, the light source variation rate is calculated by distinguishing the wavelengths in which the bright line exists and the wavelengths in which the bright line does not exist.

Then, the reflectances at the peak wavelengths of the sensors F1P1 to FnPn of the sample measuring section are calculated based on the equation 1 (# 5). Here, the wavelength for which the reflectance should be calculated is the wavelength of 10 nm pitch in the range of 400 to 700 nm, but the peak wavelength of the sensor does not always completely match these wavelengths, as shown in FIG. Therefore, the reflectance at the 10 nm pitch of 400 to 700 nm is calculated from the calculated reflectance at the peak wavelength by a cubic interpolation method or the like (# 6). Then, a tristimulus value is calculated from this reflectance and displayed as a colorimetric value (# 7).

FIG. 6 shows the variation rate of the light source when the light source measuring sensor is arranged as shown in FIG.
It is a figure which shows the relative error of the light source variation calculated by the said correction procedure. As shown in FIG. 6, the relative error is suppressed to 0.5% or less over the entire wavelength, which has no influence on the actual measurement.

Next, the evaluation result of the repeatability of measuring the white calibration plate 30 times at intervals of 10 seconds will be described. First,
Reflectance R (i, λ) at each wavelength at each wavelength (i = 1 to 3)
0, λ = 400 to 700) is calculated, and the standard deviation σ (λ) of the reflectance for each wavelength is

[0054]

[Equation 6]

It is calculated by

On the other hand, regarding the color value, the color value L at each time is also
From * (i), a * (i), b * (i) (i = 1 to 30), the standard deviation σ (ΔE * ab) of ΔE * ab is

[0057]

[Equation 7]

[0058]

[Equation 8]

[0059]

[Equation 9]

[0060]

[Equation 10]

It is calculated by

The repeatability is evaluated by the standard deviation σ (λ) and standard deviation σ (ΔE * ab) calculated as described above. According to this evaluation, the measurement result by the above correction procedure shows that σ (λ) is within 0.10 and σ (Δ is the same as when the light source measurement sensor is arranged as shown in FIG.
E * ab) is suppressed to 0.03 or less, and a highly accurate color measurement result is obtained.

A sensor for measuring a light source is provided for a plurality of wavelengths having a bright line, and the obtained light source variation rate is used to calculate the light source variation rate of another wavelength at which the bright line exists by interpolation or the like. You may As a result, it is possible to more accurately correct the light source fluctuation rate that is not exactly the same depending on the wavelengths in which the bright line exists, and thus it is possible to further improve the measurement accuracy.

In the first embodiment, when there is no light source measuring sensor that receives the peak wavelength adjacent to the peak wavelength at which the bright line exists, the evaluation of the repeatability at wavelengths near the peak wavelength is deteriorated. There is. The second embodiment is intended to improve this point, and will be described below with reference to FIGS. 7 and 8 and Table 2. FIG. 7 is an explanatory diagram showing the correction of the reflectance for each peak wavelength.

In the second embodiment, the second arithmetic unit 7 once obtains the reflectance of the peak wavelength for which there is no light source measuring sensor for receiving the peak wavelength adjacent to the peak wavelength where the bright line exists. A certain function such as a cubic function is assumed by using the reflectance of the wavelength and the reflectance of the peak wavelengths of two points before and after each adjacent to the wavelength, and this function is determined by the least square method, The wavelength reflectance is recalculated.

For example, in FIG. 7, wavelengths λ11 and λ1
3, λ15, λ17 are wavelengths having light source measurement sensors for receiving the respective wavelengths, and assuming that the wavelength λ15 is a wavelength at which a bright line exists, the reflectance of the wavelength λ14 (λ16) is the wavelength λ12, Recalculation is performed using the reflectances of λ13, λ15, λ16 (wavelengths λ14, λ15, λ17, λ18). As a result, the wavelengths λ14 and λ
The repeatability rating of 16 is improved.

Next, the procedure for calculating the reflectance will be described with reference to FIG. 7 and according to the flowchart of FIG.

Since Steps # 11 to # 15 are the same as Steps # 1 to # 5 in FIG. 5, description thereof will be omitted. From the above, the reflectance at each peak wavelength as indicated by the circle in FIG. 7 is calculated.

Here, it is assumed that the evaluation of the repeatability of the reflectances of the wavelengths λ14 and λ16 is lowered (the error is increased). Here, wavelengths λ12 to λ16 including two points each before and after the wavelength λ14.
Function f that approximates the five points of reflectances R12 to R16 of
Assuming (λ), the function f (λ) is obtained by the least square method (# 16). In this embodiment, a cubic function is assumed as an example. The solid line in FIG. 7 shows this function f (λ). Similarly, the function g (λ) is obtained using the reflectances R14 to R18 of the wavelengths λ14 to λ18 including two points before and after the wavelength λ16. The broken line in FIG. 7 indicates the function g
(Λ) is shown.

Then, the reflectance of the wavelength λ14 is f (λ1
4) Recalculate the reflectance at the wavelength λ16 as g (λ16) (# 17). As a result, the reflectances R14 and R16 are
The value indicated by ○ changes to the value indicated by × (○ → × in Fig. 7)
). The following steps # 18 and # 19 are the same as steps # 6 and # 7 in FIG.

[0071]

[Table 2]

Table 2 shows the effect of the correction according to the second embodiment, and shows the standard deviation σ (λ) of the reflectance in the evaluation of the repeatability before and after the correction. It can be seen that the evaluation of repeatability is improved at each wavelength.

As described above, according to the second embodiment, the light source variation rate of the wavelength at the boundary between the wavelength where the bright line exists and the wavelength where the bright line does not exist can be appropriately approximated.

Next, the third object colorimeter of the present invention will be described.
An example will be described based on FIGS. 9 and 10. Third
The configuration of the embodiment is similar to that of the first embodiment.

The third embodiment is intended to apply the object color measuring device according to the present invention to a diffuse illumination / vertical (8 °) light receiving system object color measuring device. In this case, it is necessary to estimate the amount of re-irradiation from the sample 1 at the wavelength where the sensor is not arranged, but this will be described with reference to the sample measurement example shown in FIG.

When a sample as shown by A in FIG. 9 is measured, a sensor for measuring a light source which receives wavelengths λi and λi + n depends on the reflectance of the sample as shown by B in the figure. It is considered that the re-irradiated portion is included.

Therefore, first, in the procedure described in the first embodiment, by using the light source variation rates of the wavelengths λi and λi + n, the light source variation rates of the wavelengths λi + 1 to λi + n-1 are calculated by linear interpolation. To calculate.

Then, the reflectances Ri to Ri + n of the sample are calculated from the light source fluctuation rate using the equation (1). And from this reflectance,

[0079]

[Equation 11] Km ′ = Km + (Rm−Ri) · (Ki + n−Ki) /
The light source variation rate Km is corrected by (Ri + n-Ri). However, m = i + 1 to i + n
-1.

In the present embodiment, as shown in equation 11, correction is made according to the reflectance at that wavelength. By using the corrected light source fluctuation rate, the reflectance is recalculated according to the equation 1 to obtain the reflectance at that wavelength.

FIG. 10 is a diagram showing an example of the correction according to the third embodiment. In the figure, A indicates the reflectance given to the sample, B indicates the error between the reflectance before correction and A, and C indicates the error between the reflectance after correction and A. As shown in FIG.
The error amount is lower after correction.

[0082]

As described above, according to the present invention, the light level of the radiated light is measured for each of a plurality of dispersed wavelength regions of the wavelength where the bright line does not exist, and at least 1 of the bright line exists. For the above wavelengths, the light levels of the wavelengths are measured, and the measurement data of the first and second light source sensors at the time of calibration and the first and the second at the time of color measurement of the sample object are measured.
From the measurement data of the light source sensor, the first light source variation rate at the wavelength measurable by the first light source sensor and the second light source variation rate at the measurable wavelength by the second light source sensor are calculated. A light source variation rate for a wavelength range other than the plurality of dispersion wavelength ranges within the wavelength where the bright line does not exist is calculated by performing an interpolation calculation using the first light source variation rate, and at least one or more where the bright line exists Since the light source fluctuation rate for wavelengths other than the above wavelength is calculated from the second light source fluctuation rate, the number of wavelengths for measuring the light source fluctuation can be significantly increased while maintaining the same measurement accuracy as the conventional colorimeter. By reducing the number, it is possible to reduce the number of parts of the sensor and the processing circuit, reduce the size and weight of the colorimeter, and reduce the cost. When applied to the diffuse illumination / vertical (8 degree) light receiving system, the influence of re-irradiation of the reflected light from the sample can be corrected as much as possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a colorimeter for object color having a light source variation correction function according to the present invention.

2 is a characteristic diagram showing the spectral distribution of the Xe light source (A in the figure) and the spectral sensitivity (B in the figure) of the sensor of the light source measuring unit of the conventional colorimeter for object colors shown in FIG. is there.

FIG. 3 is a characteristic diagram showing a change in a measurement value of a sensor of a light source measurement unit when a white calibration plate is measured 30 times.

FIG. 4 is an explanatory diagram showing interpolation of a light source variation rate for each wavelength.

FIG. 5 is a flowchart showing a correction procedure of the first embodiment.

FIG. 6 is a diagram showing a relative error of the light source variation calculated by the correction procedure of the first embodiment with respect to the light source variation when the light source measuring sensor is arranged and measured as shown in FIG. .

FIG. 7 is an explanatory diagram showing correction of reflectance for each peak wavelength.

FIG. 8 is a flowchart showing a correction procedure of the second embodiment.

FIG. 9 is a diagram showing a measurement example of a sample.

FIG. 10 is a diagram showing an example in which correction is performed according to the third embodiment.

FIG. 11 is a block diagram showing a configuration of a conventional object colorimeter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sample 2 light source 3 current-voltage conversion circuit 4 A / D conversion circuit 5 1st calculation part 6 display part 7 2nd calculation part 18 control part 19 keyboard 21 illumination circuit 51,71 RAM 52 ROM F1 to Fn, Fn1 to Fn5 spectroscopy Filter P1 to Pn, Pn1 to Pn5 Photoelectric conversion element

Claims (1)

[Claims] 1. A colorimeter for illuminating an object with a white light source and receiving transmitted light or reflected light from the illuminated object to measure the color of the object, wherein a wavelength at which a bright line of the illuminating light does not exist Of the plurality of dispersed wavelength regions, a first light source sensor for measuring the light level of the wavelength, and a second light source sensor for measuring the light level of the wavelength for at least one wavelength in which a bright line exists. The first light source sensor can measure from the light source sensor, the measurement data of the first and second light source sensors at the time of calibration, and the measurement data of the first and second light source sensors at the time of color measurement of the sample object. Of a plurality of wavelengths in which the bright line does not exist, and a first calculation means for calculating a first light source fluctuation rate at a different wavelength and a second light source fluctuation rate at a wavelength measurable by the second light source sensor. Other than the dispersion wavelength range of Second calculating means for interpolating and calculating a light source variation rate for a wavelength range using the first light source variation rate, and a second light source variation rate for a wavelength other than at least one wavelength in which the bright line exists. And a third calculation means for calculating from the light source variation rate of 1. The colorimeter for object color having a light source variation correction function.