JPH08327556A - Device for evaluating color of precious stone - Google Patents

Abstract

PURPOSE: To provide a device for quantitatively evaluating the color of diamond. CONSTITUTION: Only the blue light of random polarization from a light source 1 transmits through a filter, and then only light in a predetermined direction of polarization transmits through a polarizing beam splitter 24. This transmitted light transmits through an objective lens 6 and vertically illuminates diamond inside an external light-block body 8. The remaining light is entirely collected into a photodiode 33. The light reflected from each side of the diamond other than a table top is absorbed by the interior wall surface of the external light blocking body. The light reflected from the table top of the diamond is not changed in polarization and therefore passes through the polarizing beam splitter 24, so that it is not received by a CCD camera 11 located on the opposite side to the beam splitter 24. Therefore, an image 36 of the diamond taken by the CCD camera 11 is formed only of the light passing through the inside of the diamond. The luminous quantity of the image 36 can be measured quantitatively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for determining the color of jewelry.

[0002]

2. Description of the Related Art Heretofore, it has been a general practice to rely on an appraiser's visual inspection for color identification of jewels, such as discrimination of a diamond color grade. However, in such a method, it is easy to be affected by the subjectivity and individual differences of the appraiser, and in reality, the appraisal results differ depending on the skill, experience, and physical condition of the appraiser, and an objective and accurate color appraisal is possible. It is hard to say that it is done.

Therefore, instead of such a subjective appraisal,
A method of mechanically attempting quantitative measurement has been proposed. For example, JP-A-57-204440 discloses that the transmittance of diamond at red wavelengths and near-ultraviolet wavelengths is measured, and the color grade is discriminated from the difference in the transmittances.

Further, Japanese Patent Publication No. 58-47011 discloses a method using an integrating sphere having a transparent vertical pipe line. In this method, while irradiating a light beam along the pipe, the diamond is dropped into the pipe, and when the diamond passes through the integrating sphere while rotating, the amount of light passing through the diamond in the pipe and the reflection by the diamond The amount of light emitted is detected, and the color grade of diamond is determined based on the amount of transmitted light and the amount of reflected light.

Alternatively, a method of illuminating a diamond that is rotating and falling with a perfect diffused light using an integrating sphere and discriminating the diamond color grade from the difference in the amount of transmitted light of the diamond between the red wavelength and the near-ultraviolet wavelength is also known. .

[0006]

However, in the above-mentioned quantitative measurement method, since both the surface reflected light and the internally transmitted light of diamond are detected and analyzed, (transmittance) +
Due to the relationship of (reflectance) = 1, a difference in transmittance (amount of transmitted light) caused by a difference in color tone of diamond is canceled by a reflectance (amount of reflected light), and thus a subtle difference in color tone cannot be distinguished.

Further, the uncertain factor of the rotational drop is apt to have a great influence on the measured value, so that it is not suitable for the quantitative measurement. FIG. 3 shows a cut diamond 10. In the diamond 10 as described above, total reflection with no loss of light quantity is used, and the light perpendicular to the table surface 51 is converted into the table surface 51, the bezel 52, and the star 53.
When incident from each surface of the upper girdle 54 and the upper girdle 54, the light is repeatedly reflected inside, and then the table surface 51 and the bezel 5
2. What is emitted from each surface of the star 53 and the upper girdle 54 is called an ideal cut. Most commercially available diamonds are formed with such cuts.
Also, the table surface 51 of the diamond 10 and the bezel 5
2, a part of the light emitted from each surface of the star 53 and the upper girdle 54 is reflected on the back surface thereof infinitely many times, so that the amount of light emitted from the diamond 10 converges to a certain value.

Therefore, the amount of light emitted from the diamond 10 contributes only to the table surface 51.
It can be said that the emitted light from 0 can be considered only by the transmittance and reflectance of the table surface 51.

An object of the present invention is to provide a gemstone color determination apparatus which can accurately and quantitatively perform gemstone color determination up to a subtle difference in color tone without rotating and dropping the gemstone.

[0010]

SUMMARY OF THE INVENTION According to one aspect of the present invention, there is provided an apparatus for assessing the color of jewelry. This device is provided with a light source, a holding unit located at a position facing the light source, for holding a jewel, and a wavelength for selectively transmitting red wavelength light and blue wavelength light from the light traveling from the light source to the jewel. Reflection from a jewel, having a selecting means and a passage opening arranged between the wavelength selecting means and the holding means, for passing only light vertically incident on the jewel from the light source and light reflected vertically from the jewel, Of the light, the light absorbing means whose inner wall surface absorbs the light so as not to directly go to the passage opening, and the reflected light which is vertically reflected from the jewel and passes through the passage opening of the light absorbing means. Among these, the reflected light selecting means for selecting only the internal transmitted light of the jewel, the image forming means for forming an image of the jewel based on the internal transmitted light of the jewel selected by the reflected light selecting means, and the formed image Light intensity measurement to measure the light intensity of Comprising the stage, and if the case where the red wavelength light is selected and blue wavelength light is selected by the wavelength selection means, and means for analyzing the ratio of measured light quantity by the light quantity measuring means.

According to one embodiment of the present invention, the reflected light selecting means includes a semi-transparent mirror and a polarizer and an analyzer arranged with the semi-transparent mirror interposed therebetween, and the polarizer and the analyzer are orthogonal Nicols. Have a relationship.

According to another aspect of the present invention, a light source, holding means for holding a jewel, which is located at a position facing the light source, and light of a specific wavelength transmitted from the light emitted from the light source. The wavelength selecting means and a passage opening arranged between the wavelength selecting means and the holding means for passing only the light vertically incident on the gemstone from the light source and the light vertically reflected from the gemstone are provided. Of the reflected light, the light absorbing means whose inner wall surface absorbs the light so as not to directly go to the passage opening, and the first amount of light which does not vertically enter the jewel from the light source is measured. The light amount measuring means, the reflected light selecting means for selecting only the internal transmitted light of the jewel among the reflected light reflected vertically from the jewel and passing through the passage of the light absorbing means, and the reflected light selecting means. Based on the transmitted light inside the gem An image forming means for forming a jewel image, a second light quantity measuring means for measuring the light quantity of the formed image, and a means for analyzing a ratio of the light quantity measured by the first and second light quantity measuring means. Provided is a gemstone color identification device.

[0013]

With the above arrangement, only the light transmitted through the jewel is selected when the jewel image is formed.
Gem surface reflections do not contribute to the image. The color of a gemstone is quantitatively evaluated by measuring the amount of light transmitted through the gemstone.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the jewelry color appraisal apparatus of the first embodiment of the present invention comprises an illuminating device, which is a light source 1.
And a lens barrel 2 to which this light source is attached. In the lens barrel 2 of the lighting device, a polarizer 4, a half mirror (semi-transparent mirror) 5 and an objective lens 6 are built in along the optical path from the light source 1. Here, either the bandpass filter 3A or 3B can be selectively arranged between the light source 1 and the polarizer 4. These band pass filters 3A, 3B
Can transmit only blue wavelength light and red wavelength light, respectively. A camera mounting portion 7 is provided on the side surface of the lens barrel 2 at a position facing the half mirror 5.

Such an illuminating device is attached to a substantially spherical external light shield 8 at the lower end of the lens barrel 2. Between the lens barrel 2 and the external light blocker 8, there is a passage opening for passing only the gemstone to be color-identified from the light source 1, for example, the light vertically incident on the diamond 10 and the light vertically reflected from the diamond 10. are doing. The inner wall surface of the external light blocker 8 is adapted to absorb light, for example, by applying a black paint or the like.

At the lower end of the external light blocker 8, that is, at a position that makes an angle of 180 degrees with respect to the illuminating device, a holding table 9 capable of fine angle adjustment is mounted. A diamond 10 to be color-identified is held on the holding table 9.

A CCD camera 11 is mounted on the camera mounting portion 7 of the illuminating device lens barrel 2 via a camera lens barrel 12. An analyzer 13 and an imaging lens 14 are arranged in the camera barrel 12 along an optical axis extending from the half mirror 5 in the illumination device barrel 2 to the CCD camera 11.
A monitor 15 is connected to the CCD camera 11 via an image analysis device 16.

The color evaluation by such an evaluation device will be described by taking the diamond 10 shown in FIG. 3 as an example. First, the bandpass filter 3A for blue light is arranged between the light source 1 and the polarizer 4. The random polarized light emitted from the light source 1 in this state is converted into linearly polarized light by the polarizer 4 after only the blue light is transmitted by the bandpass filter 3A. This linearly polarized light is generated by the half mirror 5 and the objective lens 6.
Through the passage of the external light blocker 8 to illuminate the diamond 10 so as to have an optical axis perpendicular to the table surface 51 of the diamond 10 on the holding table 9.

At this time, the bezel 52 of the diamond 10 is
Light reflected from the respective surfaces of the star 53 and the upper girdle 54 is absorbed by the inner wall surface of the external light blocker 8. Further, since the polarization of the reflected light from the table surface 51 does not collapse, after passing through the passage opening of the external light blocker 8 and reflected by the half mirror 5, the analyzer 13 in a state of a crossed Nicol with the polarizer 4. Cannot be transmitted and the CCD camera 11 does not receive the light.

Therefore, the image 17 displayed on the monitor 15
Are formed only by the light transmitted through the inside of the diamond 10. Therefore, the light amount of the image 17 is obtained by the image analysis device 16.

Next, the bandpass filter 3B for red light
The image 18 displayed on the monitor 15 is displayed in the same manner as in the case of using the blue light bandpass filter 3A.
Find the amount of light.

It is known that the colorless and transparent diamond has a better blue transmittance and the red transmittance does not change at all. Therefore, in order to minimize the measurement error caused by the aging of the light source, the light amount obtained from the image 17 is expressed as a ratio with respect to the light amount obtained from the image 18, so that the color tone of the diamond can be obtained with only one CCD camera. It is possible to obtain it with a numerical value.

In this embodiment, the polarizer 4, the half mirror 5 and the analyzer 13 as the reflected light selecting means may be replaced with a polarization beam splitter. in this case,
This has the effect of reducing the number of parts and simplifying the configuration.

FIG. 2 shows a jewel color-identification device according to the second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The appraisal device of FIG. 2 includes an illuminating device, and the illuminating device includes the light source 1 and a lens barrel 22 in which the light source is mounted.

The lens barrel 22 has a band-pass filter 3 capable of transmitting only blue wavelengths along the optical path from the light source 1.
A, a polarization beam splitter 24, and an objective lens 6 are built in. Here, although the bandpass filter 3A is shown in a perspective view outside the lens barrel 22, it is assumed that the bandpass filter 3A is actually disposed inside the lens barrel 22 between the light source 1 and the beam splitter 24. Camera mounting portions 26 and 27 are provided on the side surface of the lens barrel 22 so as to face each other with the pair of polarization beam splitters 24 in between. Such an illuminating device is mounted on the external light blocker 8 as in the first embodiment. The diamond 10 is held on the holding table 9. The holder 9 is attached to the external light blocker 8 at a position that makes an angle of 180 degrees with respect to the lighting device.

The CCD camera 11 is mounted on one camera mounting portion 26 via the imaging lens 14, and the photodiode 33 is mounted on the other camera mounting portion 27. The image analysis device 16 includes a photodiode 33,
The CCD camera 11 is attached via the monitor 15.

The color judgment by such an appraisal device will be described by taking the diamond 10 shown in FIG. 3 as an example. First, of the randomly polarized light emitted from the light source 1, only blue light is transmitted by the bandpass filter 3A, and then only light of a predetermined polarization direction is transmitted by the polarization beam splitter 24. The transmitted light passes through the objective lens 6, passes through the passage of the external light blocker 8, and illuminates the diamond 10 so as to have an optical axis perpendicular to the table surface 51 of the diamond 10 on the holding table 9. All the remaining light is taken into the photodiode 33. Here, as in the first embodiment, the reflected light from the respective surfaces of the bezel 52, the star 53 and the upper girdle 54 of the diamond 10 is absorbed by the inner wall surface of the external light blocker 8 and reflected from the table surface 51. Since the polarization of light does not collapse, the polarization beam splitter 24
Is transmitted, and is not received by the CCD camera 11.

Therefore, the image 36 displayed on the monitor 15 is displayed.
Are formed only by the internal transmitted light of the diamond 10. Therefore, the color tone of the diamond 10 can be obtained numerically by the image analyzer 16 expressing the light amount obtained from the image 36 as a ratio to the light amount obtained by the photodiode 33.

In the second embodiment, since the bandpass filter 3A is not replaced, the measuring time is shortened as compared with the first embodiment, and two lights for determining the color tone of the diamond 10 are simultaneously detected. Therefore, there is an effect that a measurement error due to the light amount variation of the light source 1 does not occur.
Although the color identification of diamond has been described in the above embodiment, the gemstone to which the present invention is applied is not limited to diamond.

[0030]

As described above, according to the jewel color-determining apparatus of the present invention, there is no influence of external light, and the surface reflected light and the internal transmitted light of the jewel can be completely separated, resulting in surface reflection. The light can be completely removed, increasing the dynamic range of the numerical values that represent the difference in color in the measurement. Further, since the gemstone is fixed during the measurement, the stability of the measured value is increased and the reproducibility is obtained, so that the measurement accuracy is improved and the gem color determination can be realized more accurately and quantitatively. .

[Brief description of drawings]

FIG. 1 is a schematic view showing a gemstone color identification device according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a gemstone color identification device according to a second embodiment of the present invention.

FIG. 3 is a side view showing a diamond as an object of the examination of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 3A, 3B band pass filter (wavelength selecting means) 4 polarizer 8 external light blocker (light absorbing means) 9 holding table (holding means) 10 diamond 13 analyzer 15 monitor (image forming means) 16 image analysis device ( Light intensity measuring means) 24 Polarization beam splitter (reflected light selecting means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fukushima Tokunichi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (3)

[Claims] 1. A device for determining the color of a jewel, comprising: a light source, a holding means for holding the jewel, which is located at a position facing the light source, and a red light emitted from the light source toward the jewel. Wavelength selection means for selectively transmitting wavelength light and blue wavelength light, and light disposed between the wavelength selection means and the holding means, the light vertically incident on the jewel from the light source and the light vertically reflected from the jewel There is a passage opening that allows only the light to pass through, and the inner wall absorbs the light so that the light that does not go directly to the passage opening out of the reflected light from the jewelry is absorbed, and the light is reflected vertically from the jewel. Among the reflected light that has passed through the passage of the light absorbing means, the reflected light selecting means for selecting only the internal transmitted light of the jewel, and the jewel based on the internal transmitted light of the jewel selected by the reflected light selecting means Image forming means for forming an image of And a light amount measuring unit for measuring the light amount of the formed image, and a light amount measured by the light amount measuring unit in the case where the red wavelength light is selected by the wavelength selecting unit and the case where the blue wavelength light is selected. A color determination device for gemstones, comprising: 2. The reflected light selecting means includes a semi-transparent mirror and a polarizer and an analyzer arranged with the semi-transparent mirror sandwiched therebetween, and the polarizer and the analyzer have a crossed Nicols relationship. Jewel color appraisal device. 3. A device for determining the color of a jewel, comprising a light source, a holding means for holding the jewel, which is located at a position facing the light source, and a holding unit for holding a jewel that is specific to the light emitted from the light source. A wavelength selection unit that transmits wavelength light, and a passage opening that is disposed between the wavelength selection unit and the holding unit and that transmits only the light that is vertically incident on the jewel from the light source and the light that is vertically reflected from the jewel are provided. However, among the reflected light from the jewel, the light absorption means that the inner wall surface absorbs the light so as to absorb the light that does not directly go to the passage opening, and the light amount of the light that does not vertically enter the jewel from the light source. A first light amount measuring means for measuring; a reflected light selecting means for selecting only the internal transmitted light of the gemstone among the reflected light reflected vertically from the gemstone and passing through the passage of the light absorbing means; Of gems selected by the selection means Image forming means for forming an image of a jewel based on partial transmitted light, second light amount measuring means for measuring the light amount of the formed image, and a ratio of the light amounts measured by the first and second light amount measuring means. An apparatus for color identification of jewels, comprising: