JPS61233328A - Colorimetric color difference meter - Google Patents

Abstract

PURPOSE:To make possible the easy, quick and accurate measurement of the reflectivi ty, transmittance, etc. of a sample by providing an integrating sphere means, monochro matic means and photodetecting means, etc. CONSTITUTION:This color difference meter is provided with the integrating sphere 8, a diffraction grating 31 which is the monochromatic means, a photoelectron multi plier 34 which is the photodetecting means, etc. A bright tap 36 is attachably and detachably attached to the integrating sphere 8 at approximately 8 deg. angle with the perpendicular in a setting part 24. Only the wavelength of the required ray out of the rays divided by the grating 31 by changing the attaching angle of the grating 31 by a motor 35 is detected by the multiplier 34 and is passed to an amplifier 37. After the wavelength is subjected an A/D conversion 38, the output thereof is inputted to a computer (CPU) 39 by which the calculated value is stored. The light past a measuring stop 17 is conducted to the multiplier 34. The value when the incident light is shielded is made 0 and the value when the light is not shielded is made 100 and there values are stored in the CPU39 which reads the input value of the multiplier 34. The measured value of the sample is 50 if the detected value is, for example, 100 and the measurement scale is 50. The above-mentioned measurement process is repeated for each of the rays having another wavelength with respect to the same sample.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a colorimeter using an integrating sphere.

[Conventional technology]

Conventionally, a first-order colorimeter has been considered as a colorimeter that measures the color difference between two samples.

FIG. 2 is an explanatory diagram of a conventional colorimeter using an integrating sphere.

In the figure, 1 is a light source that emits continuous spectrum light, 2 is a mirror that reflects the light from this light source, 3 is an aperture,
4 is a lens, 5 is a collimator mirror that reflects the reflected light from this lens 4 to a prism 6, and leads the reflected light from this prism 6 to the measurement number shift, 8 is an integrating sphere, and 9 is an element inside this integrating sphere 8. 10 is a standard plate, 11 is a photodetector, and 12 is a microammeter. In this colorimetric colorimeter, light from a light source 1 that has passed through an aperture 3 is reflected by a mirror 4, separated into spectra by a prism 6, and then transformed into parallel rays by a collimator mirror 5, which leads to a measurement number shift. This prism 6 is rotatable in the direction of the arrow, and the wavelength can be selected so that out of the light separated by the prism 6, light having a desired wavelength is incident on the sample 9.

The reflected light from the sample 9 is photoelectrically converted by a photodetector 11, the photocurrent is indicated by a microammeter 12, and the color difference of the sample is measured using this photocurrent.

Next, measurement of color difference between two samples will be explained.

In the field of colorimetry, CIB (International Commission on Illumination) and JIS
The three primary colors (red, green) defined by

The tristimulus values of x, y, and z are used.

This is based on the fact that the human eye has three independent photosensitive mechanisms, and is thought to distinguish and perceive colors depending on the stimulation rate.

What can be directly obtained in colorimetric measurement are the above tristimulus values x, y, and z. Using these tristimulus values, for example, the following colorimetric relational expression can be used to calculate brightness, 9 chromaticity a, b
is required.

Colorimetric relationship formula % formula % Now, there are sample 1 and sample 2, and the color difference ΔE between the samples 1°2 is obtained by calculating with the following formula.

ΔE= (xL) “10 (Δ3) 10 (Δb)” Here,
For the two samples, the values of a and b are LIHa
l, bl, L, , afi, b2
Then, ΔL, Δa, and Δb are each expressed by the following equations.

ΔL=L2 Ll, Δa”a2 al + Δb=
Jb.

Note that accessories are available to enable a variety of measurements, such as the measurement of color differences in transmitted colors of gases and liquids.

FIG. 3 is an explanatory diagram of another conventional colorimetric color difference meter using an integrating sphere. In this device, light from a light source (not shown) is guided into the integrating sphere B, and the sample 9 or standard plate 10 set in the integrating sphere 8 is illuminated with diffused light from the space of the integrating sphere 8, and this diffused light is reflected. It looks like this. The reflected light from the sample 9 or the standard plate 10 is received by phototubes 13 and 14, respectively, and converted into photocurrent. By converting the reflected light from the sample 9 or the standard plate 10 and comparing the nine photocurrents, the reflectivity between the sample 9 and the standard plate 100 is compared. Since this photocurrent is weak and difficult to directly compare or indicate, it is amplified by an amplifier 15. Also to compensate for photocurrent.

Gray wedge in the measuring circuit16. A measuring screw 17 is provided in the comparison circuit, and a zero point indicator 1B is used to manage the compensation. Further, filters 19,20 are provided in front of each of the phototubes 13,14, and the filters 19,20 are screwed in pairs so that they can be switched for each required wavelength.

To use this colorimeter, first replace the filter with one of the desired wavelength, place the object to be measured, such as a sample or standard plate, into the measurement port, look through the measurement window (not shown), and then Place the object in the correct position and align the standard plate 10. The calibration value of this standard plate 10 is set on the measuring aperture #7 drum, the photocurrent is corrected with the gray wedge 16, and the zero point indicator is used to manage it. Next, the standard plate 10 is removed laterally, and the photocurrent is corrected by an electrometer diaphragm shift. by this.

The reflectance of the object to be measured is read directly on the measurement aperture shift drum, while the sample remains in contact with the measurement port.

Replace filters 19 and 20 and repeat the same measurement operation. The required time is 20-30 seconds.

Note that the tristimulus value X is the color difference between two objects.

The determination using the measured values of Y and Z is the same as in the case of the colorimeter shown in FIG. 3.

[Problem that the invention seeks to solve]

The reflectance of solid surfaces can be measured using the integrating sphere shown in Figure 2, and the reflectance of glass, film, etc. can be measured using an absorption cell.
Although it is possible to measure the transmittance of a liquid for light of various wavelengths, it is easy to cause variations in the luminous intensity of the reflected light due to replacing the sample or standard plate, or placing an absorption cell in front of the integrating sphere, which impairs measurement accuracy. do. For this reason, the optical system must be delicately adjusted each time, and the time required for measurement is often increased.

Furthermore, in the colorimeter using an integrating sphere shown in Fig. 3,
Although it is not necessary to measure the sample 9 and the standard plate 10 alternately, it is necessary to prepare and replace filters for each wavelength, and there is a restriction that the measurement target is limited to the reflectance of the solid surface. However, the drawback was that the measurement time was long.

The two types of conventional devices described above are useful for limited applications as colorimetric colorimeter; however,
What we can say in common is that in order to measure reflectance of solid surfaces, transmittance of glass, films, liquids, etc. easily, quickly, and with good reproducibility and accuracy using a single device, all of them must be satisfactory. In particular, when measuring the color difference of a sample with high gloss or metallic color, it was difficult to obtain a measured value that matched the judgment with the naked eye.

[Means for solving problems]

This invention was made in order to solve these problems.The light emitted by the light source is guided to an integrating sphere, the test object is illuminated with diffused light, and the reflection angle from the test object is approximately 8 degrees. In this method, an integrating sphere means is provided to emit light into an optical system, and the light emitted from the optical system having an optical axis that coincides with the reflected light from the integrating sphere means is separated by a monochromatic means, and the light is detected by a light detection means. You can easily check the reflectance, transmittance, etc. of the sample.

It is an object of the present invention to provide a colorimetric colorimeter that can measure color differences quickly and accurately, and in particular, can measure color differences in samples with high gloss and metallic colors that match visual judgment.

〔Example〕

A colorimetric colorimeter according to an embodiment of the present invention will be described below with reference to FIG. Note that the same reference numerals are given to the same or corresponding parts as in the conventional art, and detailed explanation thereof will be omitted.

21 is a fan for cooling the light source 1; 22 and 23 are filters disposed at the front part where the light from the light source 1 enters the integrating sphere 8; and 24 is a setting part for setting the object to be examined inside the integrating sphere 8. , 25 is an entrance through which the light reflected from the set section 24 enters the optical system 26, 27 is a lens of the optical system 26, and 28
29 is a transmission sample chamber, 29 is a pinhole through which the light from this optical system 26 enters a spectroscope 30 which is a monochromatic means, 31 is a diffraction grating, 32 is a mirror, 33 is a collimator mirror, and 34 is a light detection means. A photomultiplier tube, 35 is a motor for selecting the wavelength of the light beam separated by the diffraction grating 31, which is a monochromatic means for selecting the measurement wavelength, and 36 is a gloss trap, which is a light absorbing member, and is approximately 8 degrees from the perpendicular line in the set part 24. The optical system 26 is removably attached to the integrating sphere 8 at an angle of 8 degrees, and the optical system 26 is attached so that the optical axis of the optical system 26 coincides with the light beam reflected from the set part 24 at an angle of approximately 8 degrees. It is. 37 is an amplifier, 38 is an A/D converter, and 39 is a computer.

The effect will be explained.

In the colorimetric colorimeter according to the embodiment of the present invention, in order to make a measurement, first, the standard plate 10 is placed on the setting part 24, set at the correct position, and the mounting angle of the diffraction grating 31 is changed using the motor 35. Of the light beams separated by the diffraction grating 31, only the desired wavelength of the light beam is detected by the photomultiplier tube 34, and the amplifier 37
after being converted by the A/D converter 38, the computer 3
9, and the calculated value is stored in the computer 39.

Further, the value when the light passing through the measurement aperture 17 is guided to the photomultiplier tube 34 and the incident light is blocked is set to zero. The input value of the photomultiplier tube 34 when the incident light is not blocked is 1.
00, memorize it in the computer 39, and select the standard plate 1.
The sample 9 is placed on the setting section 24 at the zero mark, set at the correct position, and the input value of the photomultiplier tube 34 is read.

In this measurement, if the detection value of the standard plate used is, for example, 100 and the measurement scale of the sample is 50, the measured value of the sample will be 50.

It is a good idea to repeat the above measurement process for the same sample using different wavelengths of light. Also.

In the colorimeter of one embodiment of the present invention, the wavelength is 380~
The time required for scanning over the 780 nm region is about 1 second, which is extremely short compared to conventional devices.

Furthermore, the basic values X, Y, and Z of the three color stimulations for the three primary colors of red, green, and blue are calculated, and the three-color coefficient x=
X/ (X±Y ten Z).

y==Y/(X0Y1Z), z=Z/(x+y1Z),
It goes without saying that calculations such as ΔE can be performed on a computer within a short period of time.

Furthermore, in order to use the colorimeter of the present invention to measure the transmittance of a liquid, it is also possible to measure the transmittance by placing an absorption cell in the transmission sample chamber 28.

Therefore, in the colorimeter according to one embodiment of the present invention, the reflected light from the object placed in the integrating sphere B is made to enter the optical system 26 at a reflection angle of approximately 8°. The reason for this is explained below.

This is because the intensity of the light beam reflected from the surface of the object to be inspected is thought to change according to the law of θ, where θ is the reflection angle, so it is desirable to select a small reflection angle θ. If the diameter is made smaller, the position of the gloss trap 36 of the integrating sphere 8 and the optical system 26 cannot be installed symmetrically with respect to the optical axis of the setting section 24 that sets the test object on the integrating sphere 8. In other words, the optical system The location overlaps with the entrance 25 of 26, which is inconvenient. Therefore, it is understood that in order to guide the reflected light from the test object to the optical system 26 on the optical path without weakening the intensity, the reflection angle is approximately 8 degrees as a geometric position. be done.

Thus, in one embodiment of the present invention, approximately 8
Since the light beam reflected at a reflection angle of ° is incident on the optical system 26, (1) the measurement light can be guided from the optical system 26 to the measuring section such as the spectrometer 30 without weakening the total intensity of the light; , and (2) the reflected light from the entrance of the optical system 26 is directly reflected by the sample.

It does not return to the mounting position of the optical system 26. Furthermore, the optical system 26
(3) Even if the sample has a glossy component, the reflected light from the sample is incident on the glossy trap 36, and this reflected light is Absorbs the luster contained in the light.

As explained in (1) to 3) above, the gloss component is removed from the reflected light from the test object, such as the sample, without significantly weakening the intensity of the reflected light from the sample. The measurement of color difference for the light obtained can be in good agreement with the judgment made by the naked eye. In conventional measurements, it was desired to be able to measure the color difference of a sample with high gloss, etc., with good agreement with the judgment made by the naked eye.One embodiment of the present invention solves this problem. It is.

However, the filter 22 also includes HA for absorbing heat rays.
By using a filter, and by using a D65 filter that can obtain light rays close to that of daylight as the filter 23, the measurement conditions for colorimetry can be made even more desirable. Thus, one embodiment of the present invention is suitable for multiple purposes.

As explained above, the colorimetric colorimeter of one embodiment of the present invention can measure not only the reflectance of solids but also the transmittance of gases and liquids.

Color difference between two samples with high gloss and metallic color can be easily, quickly and precisely determined.

〔Effect of the invention〕

As described above, the present invention is directed to an integrating sphere that directs light emitted from a light source to an integrating sphere, illuminates a test object with diffused light, and emits the light from the test object to an optical system at a reflection angle of approximately 8 degrees. means,
An optical system having an optical axis that coincides with the reflected rays from this integrating sphere means.

With a simple structure that includes a monochromatic means for dispersing the light emitted from this optical system and a light detection means for detecting the light separated by the monochromatic means, it is possible to easily and quickly measure the reflectance, transmittance, etc. of a sample. It has the advantage of being able to measure with high precision and making it possible to measure the color difference of samples with high gloss and metallic appearance, which is similar to the naked eye judgment.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a colorimetric colorimeter according to an embodiment of the present invention, Fig. 2 is an explanatory diagram of a conventional colorimetric colorimeter using an integrating sphere, and Fig. 3 is an explanatory diagram of a colorimetric colorimeter using the same integrating sphere. This is an explanatory diagram of a color difference meter using the zero position method. 1... Light source 8... Integrating sphere 9... Sample 26... Optical system 30... Spectrometer 36...Gloss trap

Claims (4)

[Claims] (1) A light source that emits light that enters the integrating sphere. The light emitted by this light source is guided into the integrating sphere, illuminates the test object with diffused light, and is emitted from the test object to the optical system at a reflection angle of approximately 8°. an optical system having an optical axis that coincides with the light beam reflected from the object by the integrating sphere means, a monochromatic means for separating the light emitted from the optical system, and a detecting light separated by the monochromatic means. A colorimetric colorimeter equipped with a light detection means. (2) The colorimeter according to claim 1, wherein the integrating sphere has a mounting portion for the object to be measured. (3) The colorimetric colorimeter according to claim 1, wherein the integrating sphere has a sample cylinder for the object to be measured. (4) The colorimeter according to claim 1, wherein the integrating sphere has a light-absorbing member.