JP2000292259A - Spectrocolorimeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive portable spectrocolorimeter in which size, weight and power consumption can be reduced by providing means for driving selective switching of a plurality of light sources having different spectroscopic luminance distribution. SOLUTION: Output lights from a plurality of light sources, i.e., LEDs 101-112, having different spectroscopic luminance distribution and arranged to have a substantially aligned maximum intensity direction of light radiation intensity distribution are condensed temporarily by means of a convex lens 113. That light is returned back to a parallel light through a concave lens 114 before illuminating a matter 200 to be measured through a collimate lens 118. A switching drive means drives switching of the LEDs 101-112 selectively and light receiving elements 301-303 receives reflected light from the matter 200. Based on the output signals from the light receiving elements 301-303, reflectance in a wavelength range corresponding to the spectroscopic band of each LED 101-112 is determined. Consequently, a spectrocolorimeter satisfying international regulations as well as national regulations can be constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrocolorimeter for measuring the color of an object by specifying the spectral reflection characteristics of the object, and more particularly to a light source for illuminating the object. By switching between these light sources using a plurality of light sources having a spectral luminance distribution, the wavelength is continuously changed, and a spectrophotometer configured to measure the reflectance of the reflected light of the object under measurement at each wavelength. The present invention relates to improvement, and satisfies "illumination and light receiving conditions" defined by standards such as JIS and ISO, and achieves downsizing.

[0002]

2. Description of the Related Art Various color measuring devices have been put into practical use as color management means for products in various color-related fields such as printing, dyeing, and textiles. By the way, in order to spectrally measure the color of an object, it is necessary to specify the spectral characteristics of the reflectance of the object to be measured by some method. There is a way.

[Forward spectroscopy] A method of irradiating an object to be measured with light in a narrow wavelength range and detecting the reflected light with a detector having a relatively uniform spectral response, and sequentially switching the wavelength range of the incident light. .

"Backward spectroscopy": A method of irradiating an object to be measured with white light substantially uniformly including the entire wavelength of visible light, and detecting the spectral intensity distribution of reflected light using a spectroscope or the like.

FIG. 5 is an optical system diagram showing a configuration example of a conventional spectrophotometer based on the "forward spectroscopic method". In FIG. 5, a lamp 1 is an iodine tungsten lamp that emits white light that continuously includes visible light. The output light of the lamp 1 enters a mirror 2. The light reflected by the mirror 2 passes through a filter 3, a lens 4, and a slit 5, and is incident on one surface of a prism mirror 6. The reflected light from one surface of the prism mirror 6 is incident on a mirror 7, and the reflected light from the mirror 7 is incident on a grating (diffraction grating) 8. The reflected light of the grating 8 is incident again on the mirror 7,
The reflected light from the mirror 7 is incident on the other surface of the prism mirror 6.

The light reflected from the other surface of the prism mirror 6 passes through a lens 9 and a slit 10 and is incident on one surface of a prism mirror 11. Reflected light from one surface of the prism mirror 11 is incident on a mirror 12, and reflected light from the mirror 12 is incident on a grating 13. The reflected light of the grating 13 is again incident on the mirror 12, and the reflected light of the mirror 12 is incident on the other surface of the prism mirror 11. The gratings 8 and 13 are mechanically driven to rotate by a mechanism (not shown).

Here, the grating 8 has slits 5,
10 constitutes a first monochromator, and the grating 13 constitutes a second monochromator together with the slits 10 and 14. These monochromators increase the wavelength purity of light used for measurement, and the second monochromator functions to remove unnecessary wavelength components slightly remaining in the output light of the first monochromator. This allows
The reflected light from the other surface of the prism mirror 11 becomes monochromatic light in a desired wavelength band with less stray light.

The light reflected from the other surface of the prism mirror 11 is incident on the chopper 16 through the slit 14 and the lens 15 and is interrupted. The light interrupted by the chopper 16 enters a beam splitter 18. The light incident on the beam splitter 18 is split into reference light and sample light.

The reference light is incident on a mirror 19, and the reflected light from the mirror 19 is incident on an integrating sphere 21 through a lens 20 and further incident on a standard white plate 22. After the reflected light of the standard white plate 22 is diffused by the integrating sphere 21,
Is incident on. On the other hand, the sample light is reflected by the mirrors 24 and 25, passes through the lens 26, and is incident on the reflection type DUT 28. The reflected light from the device under test 28 is diffused by the integrating sphere 21 and then enters the detector 23.

When measuring a transmission type object to be measured, the object to be measured may be installed at the position 27 and a standard white plate may be installed at the position 28. The optical trap 29 is provided to prevent light directly reflected by the standard white plate 22 and the device under test 28 from being incident on the detector 23 as necessary.

In such a configuration, the wavelengths of the reference light and the sample light can be continuously changed by a wavelength driving system (not shown). Then, a standard white plate 2 at each wavelength is obtained from an output signal of the detector 23 by a signal processing system (not shown).
The spectral reflectance is obtained from the ratio of the reflection intensity of the device under test 28 to that of the device under test 28. In the case of a transmission type DUT, the spectral transmittance is determined from the ratio to the DUT 27. Further, chromaticity can be displayed by performing a predetermined calculation using these spectral reflectances or spectral transmittances.

However, such a conventional apparatus incorporates two monochromators, which are composed of gratings 8 and 13 that are mechanically driven to rotate.
There is a problem that it is quite large and expensive, and it takes a considerable amount of time for measurement, and it is also difficult to make it portable and portable, and it is difficult to make a small device that is easy to operate and suitable for use in a production line. .

On the other hand, a light emitting diode is compact and efficiently irradiates light in a narrow wavelength range, so that it is most suitable as a light source of the above-mentioned “forward spectroscopic method”. By combining these light emitting diodes, the entire visible light wavelength range can be covered without any gap.

By the way, in order to perform high-precision measurement compatible with the colorimetric values of other colorimeters, it is necessary to specify conditions for illuminating an object to be measured and receiving light of reflected light. For example, JIS
Z8722 "Color Measurement Method-Reflected and Transmitted Object Colors""4.3.1 Geometric Conditions of Illumination and Light Receiving", "The geometric conditions of illumination and light receiving are generally the following conditions a and b. , The condition c or the condition d), and the condition b illuminates the sample with a single light beam whose angle formed by the optical axis with respect to the normal of the sample surface does not exceed 10 °. ,
The reflected light is received in a direction at an angle of 45 ± 2 ° with the normal to the sample surface.

In this case, it is specified that the illumination and received light fluxes do not include a light ray having an inclination of 8 ° or more with respect to each center line. ” Here, `` illuminate the sample with one light beam '' is to minimize the measurement error when the direction of light reflection of the sample is different by illuminating the same point of the sample from the same incident direction. Is intended. These rules are consistent with international standards such as ISO, and must be satisfied for internationally compatible colorimetry.

FIG. 6 shows an example of the configuration of a conventional colorimeter using a light emitting diode, which is disclosed in Japanese Patent Publication No. Sho 59-26891. In the figure, a large number of light emitting diodes L1-1, L1-2,..., L2-1, L2-
Are arranged alternately close to each other to make the optical path of each color approximately equivalent to the light projecting unit S1 as a whole.
The reflected light from 1 is received by a light receiving element P common to each color.

[0017]

However, in the prior art shown in FIG. 6, the positions of the light emitting diodes are set close to each other so that the light beams from the light emitting diodes of a plurality of colors are irradiated on the sample from the same optical path as much as possible. The sample is still illuminated with a plurality of different light beams, and the above-described measurement error when the direction of light reflection of the sample is different occurs directly.

Further, since the spread of the emitted light varies depending on the type and individual of the light emitting diode, the irradiation diameter and the visual field diameter on the sample are different for each light emitting diode by simply arranging them as shown in FIG. There is also a problem that the restriction is difficult.

The present invention has been made in view of such a point, and its object is to satisfy not only the requirements stipulated in the domestic standard but also the international standard, to reduce the size and weight, to reduce the power consumption, It is an object of the present invention to provide a spectrophotometer which can be carried at a low price, has a small measurement error when the direction of light reflection of a sample is different, and can easily limit a field diameter.

[0020]

According to the first aspect of the present invention, which achieves the above object, the present invention has different spectral luminance distributions so that the maximum intensity directions of the respective light emission intensity distributions substantially coincide with each other. A plurality of light sources are arranged, and they are arranged so that the optical axis substantially coincides with a position where most of the output light fluxes of these light sources pass, and the output light fluxes of the respective light sources are condensed to illuminate substantially the same point of the DUT. A light condensing optical system, a switching drive means for selectively switching and driving the plurality of light sources, and at least one light receiving element for measuring reflected light of an object to be measured by illumination of each light source. It is characterized in that a reflectance in a wavelength range corresponding to a spectral band of each light source is obtained based on an output signal of the element.

According to such a configuration, a mechanical rotating mechanism as in the related art is not required, so that a compact and lightweight, low power consumption, low cost portable spectrophotometer can be realized.

According to a second aspect of the present invention which achieves the above object, a plurality of light sources having different spectral luminance distributions and arranged so that the maximum intensity directions of the respective light emission intensity distributions substantially coincide with each other. And a condensing optical system arranged so that the optical axis substantially coincides with a position where most of the output light fluxes of these light sources pass, and a condensing optical system near the condensing point of the light condensing optical system. A diaphragm that restricts the light beam diameter, a collimator lens that is disposed at a position where the distance between the transmission diffuser plate and the diaphragm is substantially the focal length, and illuminates the object to be measured with the emitted light beam, and the plurality of light sources. Switching drive means for selectively switching, and at least one light receiving element for measuring reflected light of the object to be measured by illumination of each light source, based on an output signal of the light receiving element, to a spectral band of each light source. Reflection in the corresponding wavelength range And obtaining the.

With this configuration, it is possible to easily cope with various requirements for the field diameter by changing the aperture diameter of the stop and the focal length of the collimator lens.

According to a third aspect of the present invention which achieves the above object, in the spectrophotometer according to the second aspect, the spread angle of the light beam emitted from the collimating lens is 16 °.
The aperture diameter of the stop and the focal length of the collimator lens are set as follows. With this configuration, it is possible to satisfy the condition of the illumination light flux that is stipulated in the standard that “the illumination light flux does not include a light ray having an inclination of 8 ° or more with respect to the center line”. .

According to a fourth aspect of the present invention, which achieves the above object, in the spectral colorimeter according to any one of the first to third aspects, the illumination system includes an optical axis of the illumination light beam and a surface of the object to be measured. Illuminate the DUT so that the angle with the normal does not exceed 10 °,
The light receiving element is arranged so as to receive reflected light in a direction having an angle of 45 ± 2 ° with respect to the normal to the surface of the object to be measured. With this configuration, the sample is illuminated with one ray bundle whose optical axis forms no more than 10 ° with respect to the normal of the sample surface, which is defined in the standard. Of the reflected light in the direction of 45 ± 2 ° ”.

According to a fifth aspect of the present invention to achieve the above object, the spectrocolorimeter according to any of the first to fourth aspects receives only light in a specific direction out of the reflected light of the object to be measured. A reflecting mirror is provided so as to input to the element. By providing the reflecting mirror in this way, the mounting angle of the light receiving element does not need to be limited to 45 ± 2 °, and the structure of the spectrophotometer can be simplified and downsized.

According to a sixth aspect of the present invention which achieves the above object, in the spectral colorimeter according to the first to fifth aspects, a coefficient is added to an output signal corresponding to illumination of each light source of the light receiving element. It is characterized in that arithmetic means for obtaining a tristimulus value by multiplying and adding is provided. With this configuration, it is possible to measure the tristimulus value with a small and light-weight, low-power, low-cost portable device having no moving parts.

According to a seventh aspect of the present invention for achieving the above object, in the spectral colorimeter according to the first to sixth aspects, the addition of the relative spectral luminance distributions of the plurality of light sources is performed in a visible light range. Wherein the spectral luminance distributions of the plurality of light sources are selected so as to provide a continuous spectral luminance distribution. As a result, a plurality of light sources can be switched by electronic control, and the structure can be simplified.

According to an eighth aspect of the present invention which achieves the above object, in the spectral colorimeter according to the first to seventh aspects, a light emitting diode is used as the plurality of light sources. Light-emitting diodes have the advantages of being available at a lower price than other light sources, having low power consumption, being able to be driven by batteries, and being resistant to mechanical vibration, and are suitable as portable spectrophotometers. .

According to a ninth aspect of the present invention which achieves the above object, in the spectral colorimeter according to any one of the first to eighth aspects, the plurality of light sources are substantially the same with respect to the object to be measured. It is characterized by being arranged so as to satisfy lighting conditions. Thereby, the compensation process for the detection signal of the reflected light can be simplified.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are configuration diagrams of an optical system according to an embodiment of a spectrophotometer according to the present invention. FIG. 1A is a plan configuration diagram, and FIG. 1B is a side configuration diagram. FIG. 2 is a partially enlarged view of FIG. In the figure, twelve light-emitting diodes 101 to 112 used as light-emitting elements are symmetrically arranged at the upper part of the optical system with the light emitting direction facing downward. These twelve light emitting diodes 101 to 11 in this embodiment
The emission wavelengths of 2 are eight types, and two types are used for four types having low luminance.

A convex lens 113 is disposed immediately below these light emitting diodes 101 to 112, and further a convex lens 11 is disposed.
A concave lens 114 is arranged in the vicinity of the focal position of the convex lens 113 below 3. The convex lens 113 and the concave lens 114 form a condensing optical system for the output light of the light emitting diodes 101 to 112. That is, the output lights of the light emitting diodes 101 to 112 are once condensed by the convex lens 113 and returned to almost parallel light by the concave lens 114. When the field diameter is small, the device under test 200 can be directly illuminated in this state.

In the enlarged view of FIG. 2, the parallel light emitted from the concave lens 114 irradiates the transmission / diffusion plate 115, and the light passing through the transmission / diffusion plate 115 is diffused almost uniformly to stop the aperture 1.
Light is incident on the light source 16. The stop 116 restricts the luminous flux to a certain diameter.

The collimating lens 118 is disposed below the diaphragm 116 at a position substantially apart by the focal length of the collimating lens 118 so as to face the DUT 200. When viewed from the collimator lens 118, it is equivalent to a diffusion light source having an aperture diameter of the diaphragm 116 at the focal position of the collimator lens 118. Accordingly, no matter which of the light emitting diodes 101 to 112 emits light, the same optical path is formed geometrically and optically only by changing the emission wavelength of the diffusion light source. Illuminate the sample with the standard ".

Assuming that the aperture diameter of the stop 116 is r, the focal length of the collimator lens 118 is f, and the spread angle of the light beam emitted from the collimator lens 118 is θ, r / f = t
The relationship anθ holds. Here, these apertures 11
By properly selecting the aperture diameter r of 6 and the focal length f of the collimating lens 118, the "illumination ray bundle specified in the standard does not include a ray having an inclination of 8 ° or more with respect to the center line. That is, the condition of the illumination light flux.

Since the viewing angle is a full angle, 1
Must be less than 6 °. The field diameter of the spectrophotometer is determined by the diameter of the light beam emitted from the collimator lens 118. By changing the aperture diameter r of the aperture 116 and the focal length f of the collimator lens 118, the field diameter of the spectrophotometer is changed. Can be changed arbitrarily.

The reflecting mirror 117 converts light traveling in the 45 ° direction out of the light reflected by the device under test 200 into light receiving elements 301 to 30.
3 are arranged in a positional relationship of incidence. The reflecting mirror 117 may be flat or curved. By providing the reflecting mirror 117 in such a positional relationship, the light receiving element 30
It is not necessary to attach 1-303 in the 45 ° direction, and the structure of the spectrophotometer can be simplified and downsized.

The light receiving elements 301 to 303 are
They are arranged so as to have a symmetrical positional relationship around the normal line of zero. This enables measurement with little error even for the DUT 200 having different reflection characteristics depending on the direction.

FIG. 3 is a graph showing an example of the relative spectral luminance characteristics of the light emitting diodes 101 to 112, which are represented by relative values with the maximum luminance of each light emitting diode being 1. FIG. 3 shows an example of six types of different spectral luminances a to f among the eight types. Here, the spectral luminance distributions of the light emitting diodes 101 to 112 are selected such that the addition of the relative spectral luminance distributions of the light emitting diodes 101 to 112 gives continuous spectral luminance in the visible light region.

That is, for example, the first light emitting diode 1
At the wavelength (long wavelength side) where the intensity of the spectral luminance distribution of No. 01 is about half the peak (long wavelength side), the wavelength is such that the intensity of the spectral luminance distribution of the second light emitting diode 102 is about half the peak (short wavelength side). select. Hereinafter, similarly, each light emitting diode is selected so that the relative spectral luminance distribution is not interrupted.

FIG. 4 is an electrical connection example diagram. Each of the twelve light emitting diodes 101 to 112 has a switch 4
00 and a current source 6 through a series circuit
01 is connected. The current limiting resistor 500 limits the current flowing through each of the light emitting diodes 101 to 112 so that the driving current of each of the light emitting diodes 101 to 112 has a predetermined value. The switch 400 is on / off controlled by an output signal of the CPU 602.

The output signal of the light receiving element 200 is input to the A / D conversion circuit 604 via the current / voltage conversion circuit 603. The gain of the current / voltage conversion circuit 603 is switched and set to a predetermined value by controlling the gain switching circuit 605 with the output signal of the CPU 602. A / D conversion circuit 60
4 is taken into the CPU 602. CPU
A display 606 for displaying measurement conditions and measurement results and a keyboard 607 for setting measurement conditions and the like are connected to 602. When a plurality of light receiving elements are used, for example, the light receiving elements are connected in parallel and their outputs are added.

The measurement procedure and the operation of the apparatus will be described. 1. Measurement of Standard White Plate The reflectance of the standard white plate based on the spectral luminance of each of the light emitting diodes 101 to 112 is measured in advance, and the measurement result is stored in the CPU.
602 is stored in a non-volatile memory (not shown). Here, the reflectance is represented by R10, R20, R30, R
40, R50 and R60. By pressing a standard white plate against the opening on the lower surface of the optical holding mechanism 100 and pressing a standard measurement key (not shown) provided on the keyboard 607, the following measurement is performed in accordance with a program stored in the CPU 602.

1) The output signal of the current-voltage conversion circuit 603 is measured by the A / D conversion circuit 604 in a state where all the currents of the light emitting diodes 101 to 112 are off, and the voltage at that time is expressed by E
00. At this time, all gains are switched by the gain switching circuit 605, and the offset voltage E00 at each gain is changed.
Ask for. Here, although the offset of each range is not particularly distinguished, E00 is an offset voltage of a corresponding gain.

2) The gain is switched to a predetermined appropriate gain by the gain switching circuit 605, the switches connected to the light emitting diodes 101 and 109 having the same spectral luminance characteristic a are turned on, and the output of the current / voltage conversion circuit 603 is turned on. The signal is measured by the A / D conversion circuit 604, and the voltage at that time is expressed as E
10 ′. Thereafter, the light emitting diodes 101 and 109
Turn off the switch connected to.

3) In the same manner as in 2), seven types of light emitting diodes each having a spectral luminance characteristic are switched, and the output signal of the current / voltage conversion circuit 603 at that time is sequentially converted to A / D.
The voltage at that time is measured by the conversion circuit 604, and
20 ', E30', E40 ', E50', E60 ', E
70 'and E80'. At this time, since the light emission luminances of the light emitting diodes are different from each other, the gains are sequentially switched to an appropriate gain by the gain switching circuit 605.

4) The output E00 (offset) when the light emitting diode measured in 1) is not turned on is subtracted from each output, and each of the light emitting diodes 101 to 11 is subtracted.
2 are calculated. E10 = E10'-E00 E20 = E20'-E00 E30 = E30'-E00 E40 = E40'-E00 E50 = E50'-E00 E60 = E60'-E00 E70 = E70'-E00 E80 = E80'-E00

2. Measurement of the object to be measured The object to be measured 200 is pressed against the opening of the spectrophotometer, and a measurement key (not shown) provided on the keyboard 607 is pressed, whereby the following measurement is performed according to a program built in the CPU 602. .

5) The output signal of the current-voltage conversion circuit 603 is measured by the A / D conversion circuit 604 while all the currents of the light emitting diodes 101 to 112 are off, and the voltage at that time is expressed by E
0S. At this time, all gains are switched by the gain switching circuit 605, and the offset voltage E0S at each gain is switched.
Ask for. Here, the offset of each range is not particularly distinguished, but EOS is an offset voltage of a corresponding gain.

6) The gain is switched to a predetermined appropriate gain by the gain switching circuit 605, the switches connected to the light emitting diodes 101 and 109 having the same spectral luminance characteristic a are turned on, and the output signal of the current / voltage conversion circuit 603 is turned on. To A /
The voltage at that time measured by the D conversion circuit 604 is E1S '
And Thereafter, the switches connected to the light emitting diodes 101 and 109 are turned off.

7) The seven types of light emitting diodes having the respective spectral luminance characteristics are switched in the same manner as in 6), and the output signal of the current-voltage conversion circuit 603 at that time is sequentially changed to A /
Measured by the D conversion circuit 604, and the voltages at that time are respectively E2S ', E3S', E4S ', E5S', E6S ',
E7S 'and E8S'. At this time, since the light emission luminances of the light emitting diodes are different from each other, the gains are sequentially switched to an appropriate gain by the gain switching circuit 605.

8) The output E0S (offset) when the light emitting diode measured in 5) is not lit is subtracted from each output to obtain each of the light emitting diodes 101 to 11
2 are calculated as outputs E1S to E8S. E1S = E1S'-E0S E2S = E2S'-E0S E3S = E3S'-E0S E4S = E4S'-E0S E5S = E5S'-E0S E6S = E6S'-E0S E7S = E7S'-E0S E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E8S = E7S = E7S = E7S = E8S

9) Thus, the reflectances R1S to R1S in the spectral band of the light emitting diodes 101 to 112 of the device under test are obtained.
R8S: R1S = E1S / E10 ・ R10 R2S = E2S / E20 ・ R20 R3S = E3S / E30 ・ R30 R4S = E4S / E40 ・ R40 R5S = E5S / E50 ・ R50 R6S = E6S / E60 ・ R60 R7S = E7S / E70 R70 R8S = E8S / E80 R80

10) Tristimulus values XYZ of the measured object
Can be obtained by the following equation.

(Equation 1) Here, A is a coefficient which is predetermined and stored in a nonvolatile memory in the CPU 602, and can be switched in accordance with a measurement condition to be displayed. Examples of the measurement conditions include a CIE 2-degree visual field or a 10-degree visual field as a color matching function, and a C light source, a D65 light source, an A light source, and an F6 light source as measurement light sources.

11) Further, display according to the following color system is possible if necessary. For example, CIE 197
6 The chromaticness index in the L * a * b * color system is given by the following equation.

(Equation 2) However, X / Xn, Y / Yn or Z / Zn is 0.00
If there is a value of 8856 or less, the calculation is performed by replacing the corresponding cubic root term in the above equation with the following equation. 7.787 (X / Xn) +16/116 7.787 (Y / Yn) +16/116 7.787 (Z / Zn) +16/116

In the above calculation example, the tristimulus values are obtained from the reflectances R1s to R8s in the spectral band of each light emitting diode. However, the wavelengths at the wavelength positions where the wavelength intervals are equal from the reflectances R1s to R8s are obtained. It is also possible to obtain the spectral reflectance by using an interpolation method or the like, and to thereby obtain the chromaticity value under various conditions.

These measured values are displayed on the display unit 606 of the main unit. In the above embodiment, a light emitting diode is used as a light source, but other light sources may be used in combination with a fluorescent lamp, a white light emitting diode, or a xenon lamp covered with a filter. In particular,
In the above-described embodiment, the light source near 400 nm is insufficient because only the currently available light emitting diode is used. However, this can be covered by, for example, combining a white light emitting diode and a filter. It is desirable to add such a light source when measurement is required.

In the above embodiment, a light receiver for monitoring the light emission intensity of the light source is not used, but at least one light receiver may be used for monitoring. Furthermore, in the above-described embodiment, the description has been made as a single measuring device that directly displays a measured value, but it is also possible to use the sensor as a sensor that appropriately processes the measured value and outputs it as a measurement signal.

[0059]

According to the present invention as described above, it satisfies the conditions stipulated not only in domestic standards but also in international standards, can be reduced in size and weight, consumes less power, can be carried at low cost, and can emit light of a sample. It is possible to provide a spectrophotometer in which the measurement error when the directionality of the reflection of light is different is small and the field diameter can be easily limited.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical system according to an embodiment of a spectrophotometer according to the present invention, where (a) is a plan configuration diagram and (b) is a side configuration diagram.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a diagram illustrating a characteristic example of relative spectral luminance of a light emitting diode.

FIG. 4 is an electrical connection example diagram of an embodiment of a spectrophotometer according to the present invention.

FIG. 5 is an optical system diagram showing a configuration example of a conventional spectrophotometer.

FIG. 6 is an optical system diagram of a conventional spectral colorimeter using a light emitting diode.

[Explanation of symbols]

 101 to 112 Light emitting diode 200 DUT 301 to 303 Light receiving element 400 Switch 500 Current limiting resistor 601 Voltage source 602 CPU 603 Current / voltage conversion circuit 604 A / D conversion circuit 605 Gain switching circuit 606 Display 607 Keyboard

Claims (9)

[Claims] 1. A plurality of light sources having different spectral luminance distributions and arranged so that the maximum intensity directions of the respective light emission intensity distributions substantially coincide with each other, and a light source is provided at a position where most of the output light flux of each light source passes. A condensing optical system arranged so that their axes are substantially coincident and condensing the output light flux of each light source to illuminate substantially the same point on the object to be measured; and switching drive means for selectively switching and driving the plurality of light sources. At least one light receiving element for measuring reflected light of an object to be measured by illumination of each light source, and determining a reflectance in a wavelength range corresponding to a spectral band of each light source based on an output signal of the light receiving element. A spectral colorimeter characterized in that: 2. A plurality of light sources having different spectral luminance distributions and arranged so that the maximum intensity directions of the respective light emission intensity distributions substantially coincide with each other; A condensing optical system arranged so that their axes are substantially coincident and condensing the output light beams of the respective light sources; a stop arranged near the condensing point of the condensing optical system for limiting the light beam diameter; A diffusing plate, a collimating lens arranged at a position where the distance from the stop is substantially the focal length, and a collimating lens for illuminating the object to be measured with the emitted light beam; and switching driving means for selectively switching and driving the plurality of light sources; And at least one light receiving element for measuring reflected light of the object to be measured due to illumination of the light source, wherein a reflectance in a wavelength range corresponding to a spectral band of each light source is determined based on an output signal of the light receiving element. Featured spectral colorimetry Total. 3. The aperture diameter of the stop and the focal length of the collimator lens are set such that the spread angle of the light beam emitted from the collimator lens is 16 ° or less.
The spectrophotometer described in 1. 4. An illumination system illuminates an object to be measured such that an angle between an optical axis of an illumination light beam and a normal to a surface of the object does not exceed 10 °. 45 degrees from the line
The spectrocolorimeter according to any one of claims 1 to 3, wherein the spectrocolorimeter is arranged to receive reflected light in a direction of ± 2 °. 5. The spectrophotometer according to claim 1, wherein a reflection mirror is provided so that only light in a specific direction out of the reflected light of the object to be measured is input to the light receiving element. 6. An operation for obtaining a tristimulus value by multiplying an output signal corresponding to illumination of each light source of the light receiving element by a coefficient and adding the same, or calculating chromaticity coordinates in various colorimetric systems from the tristimulus value. 6. The spectrophotometer according to claim 1, further comprising means. 7. A method of adding a relative spectral luminance distribution of a plurality of light sources to a continuous spectral luminance distribution in a visible light region.
The spectral colorimeter according to claim 1, wherein spectral luminance distributions of the plurality of light sources are selected. 8. The spectrophotometer according to claim 1, wherein a light emitting diode is used as the plurality of light sources. 9. The spectral colorimetry according to claim 1, further comprising an arithmetic unit for obtaining spectral reflectances at equal wavelength intervals from reflectances in a wavelength range corresponding to a spectral band of each light source. Total.