JP2013246980A - Lighting device and optical duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of adjusting hues of light to a designated hue after guiding light to a duct, and an optical duct.SOLUTION: In a lighting device 1 used for an optical duct for guiding light from a first space to a second space, the lighting device 1 includes a light source for emitting first light having a first spectrum distribution, a measuring part for measuring a second spectrum distribution of second light after guiding light to the optical duct, and a control part for calculating chromaticity coordinates of third light including the first light and the second light by using a function for calculating chromaticity coordinates using the spectrum distribution as a variable, the first spectrum distribution, and the second spectrum distribution, and making the first spectrum distribution change in a direction to lessen a distance between the chromaticity coordinates of the third light and the reference chromaticity coordinates.

Description

  Embodiments described herein relate generally to a lighting device and an optical duct.

  The electric power consumed by lighting in ordinary households is 16.1% of the total power consumption according to the “Outline of Electricity Supply and Demand 2004 of the Agency for Natural Resources and Energy”. Similarly, the power consumed by lighting in the office is 21.3% of the total power consumption according to the “Energy White Paper 2010”. As this figure shows, lighting accounts for a large percentage of power consumption in both homes and offices. To realize a low-carbon society, low power consumption of lighting is strongly desired. Under such circumstances, abundant sunlight (natural light) during the day is taken into a duct made of mirror material with a relatively high reflectivity such as aluminum, and light is emitted indoors using wall reflection with high reflectivity. Attention has been focused on “light ducts” that are used for lighting.

  In such an optical duct, light in a specific wavelength region is attenuated due to reflection on the wall surface, so that light that travels through the duct and reaches indoors has a different color from natural light. That is, the color of light in the wavelength region that is complementary to the attenuated wavelength region is enhanced. The light whose color has changed in this way is not preferable as illumination in many cases, and therefore the light color is adjusted to a desired color, for example, the light after being guided through the duct is brought close to natural light. Technology is desired.

JP 2009-176606 A

  Provided are an illuminating device and a light duct capable of adjusting the color of light after being guided through a duct to a desired color.

  An illuminating device according to an embodiment is an illuminating device used for an optical duct that guides light from a first space to a second space, the light source emitting a first light including a first wavelength as a first light flux, and the light. A measurement unit that measures the spectral distribution of the second light after being guided through the duct, and a first unit that includes the first light and the second light using the spectral distribution of the second light measured by the measurement unit. A control unit that calculates chromaticity coordinates of three lights and controls the first light flux in a direction that reduces a distance between the chromaticity coordinates of the third light and a predetermined chromaticity coordinate;

  The light duct of the embodiment includes a daylighting unit for daylighting natural light, a duct for guiding the natural light indoors, and a light emitting unit for introducing outside light after guiding the ducts into the indoors. A light source that is provided in the light emission unit and emits a first light including a first wavelength as a first light flux, and is provided at a position closer to the light collection unit than the light source of the light emission unit, and guides the light duct. A measurement unit that measures a spectral distribution of the second light after the light is emitted, and a third light including the first light and the second light by using the spectral distribution of the second light measured by the measurement unit. A control unit that calculates chromaticity coordinates and controls the first light flux in a direction that decreases a distance between the chromaticity coordinates of the third light and a predetermined chromaticity coordinate;

The block diagram of the illuminating device which concerns on 1st embodiment. Schematic of the optical duct which concerns on 1st embodiment. The figure which shows the reflective characteristic of the optical duct which concerns on 1st embodiment. The figure which shows the chromaticity diagram which concerns on 1st embodiment. The figure explaining the color shift of the light which concerns on 1st embodiment. The block diagram of the illuminating device which concerns on the modification of 1st embodiment. The block diagram of the illuminating device which concerns on 2nd embodiment. The figure which shows the chromaticity diagram which concerns on 2nd embodiment. The block diagram of the illuminating device which concerns on 3rd embodiment. The block diagram of the illuminating device which concerns on another modification.

  Embodiments for carrying out the invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram of an illumination device 100 according to the first embodiment. The illuminating device 100 of FIG. 1 is provided in the light duct 200 for taking in natural light including sunlight from the outside (first space) to the inside (second space). That is, according to the illuminating device 100 of this embodiment, the natural light inserted from the light duct 200 can be used as illumination during the day, and the light from the light source of the illuminating device 100 can be used as the illumination at night. In addition, the light emission part may be one and plural may be sufficient.

  The light duct 200 is roughly classified into two types, a horizontal light duct and a vertical light duct, depending on the installation position of the daylighting unit and the arrangement direction of the pipes. The horizontal light duct has a daylighting unit for daylighting natural light on the wall surface of the building, and the pipe is disposed substantially horizontally with respect to the ceiling of the building, for example. The vertical light duct has a daylighting unit for taking in natural light on the roof or rooftop of the building, and the piping is disposed substantially perpendicular to the ceiling of the building, for example. Each of the light ducts has one or more light emitting portions on the ceiling of the building. The light collected from the daylighting unit and transported through the light duct is inserted into the room from the light emission unit.

  Although the illuminating device 100 of this embodiment can be used with respect to both a horizontal light duct and a vertical light duct, the example used for a horizontal light duct is demonstrated.

  FIG. 2 is a schematic view of the optical duct 200. The light duct 200 of FIG. 2 includes a daylighting unit 210 that collects natural light, a duct 220 that guides natural light indoors, a light emitting unit 230 that introduces light after guiding the duct 220 into the indoors, and the illumination device 100. . The duct 220 is formed of a member such as aluminum. Natural light is guided indoors while being repeatedly reflected in the duct 220 using the inner surface of the duct 220 as a reflection surface.

  In such an optical duct 200, the light is discolored in the process of carrying natural light indoors due to reflection in the duct 220. That is, the color of light changes.

  FIG. 3 shows an example of the reflection characteristic of the duct 220 with respect to the visible light region wavelength. In FIG. 3, the horizontal axis represents the wavelength of light, and the vertical axis represents the reflectance of light. Common aluminum is used for the inner surface (reflection surface) of the duct 220. Further, the solid line indicates the light reflection characteristic at the time of one reflection, and the dotted line indicates the light reflection characteristic at the time of five reflections.

  As shown in FIG. 3, the light reflected in the duct 220 tends to have a lower reflectance of light having a short wavelength component than that of light having a long wavelength component. Therefore, the natural light taken in from the daylighting unit 210 is reflected many times in the duct 220 before reaching the light emitting unit 230, so that the short wavelength component of the light included in the natural light is lighter than the long wavelength component. Attenuates. This tendency is caused by the distance between the daylighting unit 210 and the light emitting unit 230 in the light inserted from the light emitting unit 230 provided in a deep room in the building or the light emitting unit 230 provided in an underground room. Will be particularly prominent.

  Thus, in the light emission part 230 of the light duct 200, the blue light contained in natural light reduces, and as a result, it becomes the light which is yellowish which is the complementary color. Since this yellowing of light is different from natural light, it is strongly desired to correct it to a light color with no sense of incongruity.

  1 includes an illumination light source 110, a correction light source 120, a sensor 130, a calculation unit 150, and a control unit 140.

  The illumination light source 110 is a white light source (for example, white LED) provided in the light emitting unit 230 of the light duct 200. Here, white is, for example, a color with a chromaticity in the vicinity of 3500K to 6500K on the black body radiation locus. A plurality of illumination light sources 110 can be disposed on one surface of a transparent substrate (not shown) such as acrylic, and the transparent substrates can be installed in the light emission part 230 of the optical duct 200.

  The illumination light source 110 is used when the amount of indoor light is insufficient with only natural light due to the influence of daytime weather, or when natural light cannot be used at night. Light emission of the illumination light source 110 may be such that the control unit 140 described later automatically controls ON / OFF switching and light quantity so that the indoor light quantity is always constant, or the user manually turns on, It may be one that switches OFF or adjusts the amount of light.

  The correction light source 120 is a light emitting element (LED) provided in the light emitting unit 230 of the light duct 200. Similar to the illumination light source 110, a plurality of correction light sources 120 can be arranged on one surface of the transparent substrate. The correction light source 120 compensates for the attenuated wavelength component of the light that is inserted indoors from the light emitting unit 230 of the light duct 200 by changing the spectral distribution of the emitted light. That is, in the present embodiment, the yellowing of the light that is inserted indoors from the light emitting unit 230 of the light duct 200 is corrected to obtain a desired light color (for example, white light).

  The correction light source 120 of the present embodiment is a blue LED that emits light included in a blue wavelength region (for example, 400 to 500 nm). That is, the yellowing of the light can be corrected by the balance between the light from the correction light source 120 and the light (external light) that is taken from the daylighting unit 210 and reaches the light emission unit 230 while reflecting inside the duct 220. Here, as an example, the light emitted from the correction light source 120 is monochromatic light having a wavelength of 480 nm.

  The sensor 130 measures the amount of energy (spectral distribution) for each wavelength component of external light. As such a sensor 130, for example, a photodiode (PD: Photodiode) using a photovoltaic effect can be used.

  The control unit 140 uses the spectral distribution of the external light measured by the sensor 130 to correct the yellowing of the light (illumination light) that is inserted into the room from the light emitting unit 230 of the light duct 200, that is, to bring the illumination light closer to white. The spectral distribution of the correction light source 120 is changed in the direction. In this case, for example, a chromaticity diagram of the CIE color system can be used. The CIE color system includes an RGB color system and an XYZ color system. Here, an example using the XYZ color system will be described.

  FIG. 4 is a diagram showing a chromaticity diagram of the XYZ color system. The color of light is quantitatively expressed as coordinates (chromaticity coordinates) on the chromaticity diagram. At this time, the peripheral portion (on the solid line) of the horseshoe-shaped region surrounded by the solid line in the figure is called a spectral locus and represents monochromatic light as the wavelength is written. The chromaticity coordinates of light can be calculated by a known method specified in JIS.

  As shown in FIG. 5, the natural light color in the daylighting unit 210 of the light duct 200 is point A (white). In addition, the color of external light in the light emitting unit 230 is set to point B (yellow). As described above, the natural light taken into the duct 220 from the daylighting unit 210 is reflected in the duct 220 so that the blue component is attenuated, and the light emitting unit 230 has yellowing. That is, in the process of natural light propagating through the duct 220, the chromaticity coordinates of the external light when reaching the light emitting unit 230 move to the point B due to the influence of yellowing.

  At this time, the light color of the correction light source 120 is set to point C (blue). The light from the correction light source 120 may be any light included in the blue wavelength range (for example, 400 to 500 nm) as described above. For example, based on the configuration of the optical duct 200, the light emitted from each light emitting unit 230 may be external light. By examining the yellowing characteristics (point B) in advance, it is preferable that the light is on a straight line connecting points A and B in the chromaticity diagram and has a color on the blue side of point A. .

Using the spectral distribution measured by the sensor 130, the control unit 140 calculates the light amount of the correction light source 120 as follows, for example. Let P ₂ (λ) be the spectral distribution of external light in the light emitting part 230 of the light duct 200 obtained from the sensor 130, and let P ₃ (λ) be the spectral distribution of the light from the correction light source 120. In this case, the chromaticity coordinates (x, y) of the mixed light (illumination light) of the external light and the light from the correction light source 120 are given by the following equations. That is, by substituting (Equation 3) to (Equation 5), (Equation 1) and (Equation 2) are functions for calculating chromaticity coordinates using the spectral distribution as a variable.

  Therefore, for example, a chromaticity diagram of desired chromaticity coordinates (x0, y0) (hereinafter referred to as reference chromaticity coordinates) that can be set in advance and chromaticity coordinates (x, y) of illumination light given by the above equation The spectral distribution of the light from the correction light source 120 is calculated in the direction in which the Euclidean distance is minimized. Then, the control unit 140 controls the light emission of the correction light source 120 in an open loop so as to approach the calculated spectral distribution.

  The reference chromaticity coordinates are set in advance, but the user specifies or adjusts a desired color as the reference chromaticity coordinates using an input unit such as a controller (not shown). Also good.

  Further, here, it has been described that the light in the light emitting unit 230 is yellowed due to the reflection characteristics of the duct 220, but the color shift is not limited to this. The color shift varies depending on the reflection characteristics of the reflecting surface in the duct 220. In some cases, as shown in FIG. 5, a color shift (point B ′) may occur in the direction of the red wavelength region (for example, 600 nm to 700 nm). By using the method of the present embodiment according to the reflection characteristics of the duct 220, it is possible to apply to color shifts other than yellowing.

  In addition, the sensor 130 may have an element configuration in which a color filter (dichroic filter) that transmits light of a specific wavelength is attached to a photodiode. That is, a sensor with a color filter that transmits light of a predetermined wavelength (blue wavelength) included in the blue wavelength range and light of a predetermined wavelength (yellow wavelength) included in the yellow wavelength range (for example, 550 nm-600 nm) And a sensor with a color filter that transmits light can measure the amounts of energy of the blue wavelength and the yellow wavelength of external light, respectively.

  Further, although the correction light source 120 has been described as emitting monochromatic light, it may emit light having a predetermined wavelength region width, for example.

  According to the illumination device 100 and the light duct 200 of the present embodiment, it is possible to adjust the color of the illumination light inserted from the light duct 200.

  Moreover, according to the illuminating device 100 and the optical duct 200 of this embodiment, the same space on the indoor ceiling can be functioned as illumination both during the daytime when natural light is used as illumination and at night when the LED light source is used as illumination. Thereby, it is possible to reduce a sense of incongruity due to a change in the position of illumination between daytime and nighttime. Moreover, the installation space of the illuminating device 100 can be shared with the light emission part 230 of the optical duct 200, the feeling of opening of an indoor ceiling can be improved, and the effective use of the ceiling space is enabled.

(Modification)
FIG. 6 is a configuration diagram of an illumination device 100 according to a modification of the first embodiment.

  In the illumination device 100 of FIG. 6, the sensor 130 measures the spectral distribution of the mixed light (illumination light) of the external light and the light from the correction light source 120.

  The control unit 140 calculates chromaticity coordinates (x, y) of illumination light using the spectral distribution measured by the sensor 130. Then, the spectral distribution of the light of the correction light source 120 is calculated in a direction in which the Euclidean distance on the chromaticity diagram between the calculated chromaticity coordinates (x, y) of the illumination light and the reference chromaticity coordinates (x0, y0) is minimized. calculate. Then, the control unit 140 controls the light emission of the correction light source 120 so as to approach the calculated spectral distribution.

  As described above, in the illumination device 100 according to the present modification, the chromaticity coordinates of the illumination light are calculated using the actual measurement value of the spectral distribution of the illumination light measured by the sensor 110. Accurate control is possible.

(Second embodiment)
FIG. 7 is a configuration diagram of an illumination device 300 according to the second embodiment. The illuminating device 300 of this embodiment differs from the illuminating device 100 of 1st embodiment by the point provided with the several light source 120 for correction | amendment which emits the light of a different wavelength. In addition, about the structure similar to the illuminating device 100 of 1st embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the illumination device 100 of the first embodiment, since the correction light source 120 is one type, as shown in the chromaticity diagram of FIG. 4, a straight line connecting the chromaticity coordinates of the correction light source 120 and the chromaticity coordinates of the external light. The light color can be corrected above.

  However, the reference chromaticity coordinates are not necessarily on the above-mentioned straight line, and even when the Euclidean distance between the reference chromaticity coordinates and the chromaticity coordinates of the illumination light is minimum, it cannot be sufficiently close to the desired color. There is also.

  In addition, the color of natural light collected from the daylighting unit 210 of the light duct 200 is not constant, and changes every moment from morning to evening. Therefore, for example, when indoor illumination light is always matched with the color of natural light, even if the Euclidean distance between the reference chromaticity coordinates and the chromaticity coordinates of the illumination light is minimum, it can be sufficiently close to the desired color. Sometimes it is not possible.

  Therefore, the illumination device 300 of the present embodiment includes a plurality of correction light sources 120 that emit light of different wavelengths, so that correction with a higher degree of freedom is possible compared to the illumination device 100 of the first embodiment. It becomes.

  The correction light source 120 of this embodiment includes two types of blue LEDs that emit light of different wavelengths included in a blue wavelength range (for example, 400 to 500 nm). Here, as an example, the illumination device includes a correction light source (first correction light source) 120a that emits monochromatic light with a wavelength of 490 nm and a correction light source (second correction light source) that emits monochromatic light with a wavelength of 470 nm. 120b.

  As shown in the chromaticity diagram of FIG. 8, the color of natural light (point A) changes within a predetermined region P due to the influence of the passage of time, for example. In addition, the color of external light in the light emitting unit 230 of the light duct 200 is point B, the color of light emitted from the first correction light source 120a is point D, and the color of light emitted from the second correction light source 120b is E. Let it be a point.

  At this time, the control unit 140 changes the spectral distribution of the first correction light source 120a and the second correction light source 120b, so that the region 140 connecting points B, D, and E in the chromaticity diagram of FIG. The light color can be corrected.

  Therefore, the illumination device 300 of the present embodiment includes the first correction light source 120a and the second correction light source 120b that emit light having different wavelengths as described above, so that the color of natural light (that is, the reference chromaticity coordinate) is obtained. Even when the value changes within a predetermined range, it is possible to sufficiently approximate the desired color by correcting light with a high degree of freedom in the region Q.

  Furthermore, in the optical duct 200 having a plurality of light emitting units 230, the distance from the daylighting unit 210 is different, so that the color of the inserted light changes for each light emitting unit 230. That is, as shown in the chromaticity diagram of FIG. 8, the color of light changes in the region R due to the color shift of the light. Even in such a case, the illumination device 300 of the present embodiment can sufficiently approximate a desired color by correcting light with a high degree of freedom in the region Q.

(Third embodiment)
FIG. 9 is a configuration diagram of an illumination device 500 according to the third embodiment. The illumination device 500 of FIG. 9 is different from the illumination devices 100 and 300 of the other embodiments in that the illumination light source 110, the correction light source 120, and the sensor 130 are provided as modules. In addition, about the structure similar to the illuminating devices 100 and 300 of other embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  9 includes a rectangular frame 510 attached to the light emission unit 230 of the light duct 200, a flat plate 520 fitted into the inner surface of the frame 510, and an illumination light source disposed in the plane of the flat plate 520. 110, the correction light source 120, and the sensor 130 provided on the inner surface of the frame 510 are provided as modules. Moreover, the control part 140 may be provided as a module similarly to another structure, and may be provided separately from a module.

The frame 510 is a rectangular member having a groove formed on the inner surface. Further, as the material of the frame 510, a metal material having excellent thermal conductivity such as aluminum (for example, thermal conductivity: 237 W · m ⁻¹ · K ⁻¹ ) is used. The frame 510 is provided with a fixing mechanism (not shown) for fixing to the light emitting part 230 of the optical duct 200. Note that a known technique is used as the fixing mechanism, and detailed description thereof is omitted here.

  The flat plate 520 is a planar member made of transparent acrylic or the like that transmits light (for example, visible light transmittance: 95%), and transmits outside light from the optical duct 200 indoors. The flat plate 520 is fixed to the frame by being fitted (fitted) into the groove of the frame 510. On the surface of the flat plate 520, there are a plurality of illumination light sources 110 and a plurality of correction light sources 120 so that the light emission direction (light traveling direction) faces the indoor side when the frame is fixed to the light emission part of the light duct. Be placed. At this time, the illumination light source 110 and the correction light source 120 are connected to the control unit 140 via the wiring 530 independently of each other.

  The sensor 130 is provided at a position (downstream) farther from the daylighting unit 210 than each light source on the inner surface of the frame 510, and is a mixture light (illumination light) of the external light transmitted through the flat plate 520 and the light from the correction light source 120. Measure the spectral distribution. The sensor 130 may be provided at a position (upstream) closer to the daylighting unit 210 than each light source on the inner surface of the frame 510, and may measure the spectral distribution of external light.

  The flat plate 520 may be made of milky white acrylic or the like (for example, visible light transmittance: 95%) that diffuses light. Thereby, the deviation of the mixed light can be reduced by diffusing the light transmitted through the flat plate 520.

  As the flat plate 520, a member capable of switching between a transmission mode that transmits light and a diffusion mode that diffuses light can be used. For this, for example, a member having liquid crystal molecules inside is used. For switching the mode, the controller 140 controls the orientation and arrangement of the liquid crystal molecules inside by applying a voltage to the flat plate 520. That is, light can be diffused by changing the refractive index of incident light. Thereby, for example, when natural light is used as illumination, more natural light can be used as illumination by using the flat plate 520 as the transmission mode. On the other hand, when the light from the illumination light source 110 is used as illumination, the flat plate 520 is used as a diffusion mode, and the luminance of light within the plane of the flat plate 520 is reduced by reducing the luminance of light directly above the illumination light source 110. It can be approached uniformly.

  According to the illuminating device 500 of this embodiment, the illuminating device 500 is made into a module, so that construction and maintenance of the illuminating device 500 can be easily performed. Therefore, it is particularly effective when there are a plurality of light emitting portions 230 of the optical duct 200.

  By the way, LEDs convert electrical energy into light energy by a phenomenon called electroluminescence. The energy conversion efficiency is about 30%, and the rest is dissipated as wasted heat energy. In addition, when a white LED is used as the illumination light source 110, the spectrum of the white LED has almost all visible light components and hardly contains infrared radiation that conveys heat, so that heat radiation due to radiation of the LED itself cannot be expected. For this reason, the overheating state continues and the junction temperature of the LED rises. As a result, the amount of emitted light decreases and the life of the LED element is shortened.

  Therefore, according to the lighting device 500 of the present embodiment, a frame that transmits heat from each light source and is excellent in thermal conductivity is provided in the light emitting portion 230 of the light duct 200 with high heat dissipation, and heat from each light source is transmitted to the light duct. The heat dissipation performance of the lighting device 500 can be improved by letting it escape.

  Further, as shown in FIG. 10, the correction light source 110 may be provided at the end of the duct 220, and the prism 340 provided immediately above the light emission unit 230 and the sensor 130 provided on the prism 340 may be provided. . At this time, the prism 340 reflects the light from the correction light source 110 and the outside light after being guided through the duct 220 indoors. Further, a part of the external light incident on the prism 340 is reflected to the sensor 130, and the sensor 130 measures the spectral distribution of the external light.

  According to the lighting device and the optical duct of at least one embodiment described above, it is possible to adjust the color of light after being guided through the duct to a desired color. Moreover, since the light source for illumination is provided in the light emission part of the light duct, a sufficient amount of illumination light can be supplied indoors even if the light duct has a plurality of light emission parts.

  These embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 100, 300, 500 ... Illuminating device 110 ... Illumination light source 120 ... Correction light source 130 ... Sensor 140 ... Control part 200 ... Light duct 210 ... Daylighting part 220 ... · Duct 230 ··· Light emitting portion 120a ··· First correction light source 120b ··· Second correction light source 510 ··· Frame 520 ··· Flat plate 530 ··· Wiring 540 · · · Prism

Claims (9)

An illumination device used in an optical duct that guides light from a first space to a second space,
A light source emitting first light having a first spectral distribution;
A measurement unit for measuring a second spectral distribution of the second light after being guided through the optical duct;
Using the function for calculating the chromaticity coordinates with the spectral distribution as a variable, the first spectral distribution and the second spectral distribution, the chromaticity coordinates of the third light including the first light and the second light are obtained. A controller that calculates and changes the first spectral distribution in a direction to reduce the distance between the chromaticity coordinate of the third light and the reference chromaticity coordinate;
A lighting device comprising:   The lighting device according to claim 1, wherein the first light is monochromatic light having a first wavelength included in a blue wavelength region. The measurement unit measures the amount of energy of the second wavelength included in the blue wavelength range of the second light and the third wavelength included in the yellow wavelength range,
The lighting device according to claim 1, wherein the control unit calculates chromaticity coordinates of the third light by using energy amounts of the second wavelength and the third wavelength. An illumination device used in an optical duct that guides light from a first space to a second space,
A light source emitting first light having a first spectral distribution;
A measurement unit for measuring a second spectral distribution of the third light including the first light and the second light after being guided through the optical duct;
A function for calculating chromaticity coordinates using the spectral distribution as a variable, the chromaticity coordinates of the third light using the second spectral distribution, and the chromaticity coordinates of the third light and predetermined chromaticity coordinates. A control unit that changes the first spectral distribution in a direction to reduce the distance to
A lighting device comprising: A frame having an inner surface formed with grooves,
A flat plate having a surface fitted in the groove and transmitting the second light;
Further comprising
5. The illumination device according to claim 1, wherein the light source is disposed on the surface of the flat plate, and the measurement unit is provided on the inner surface of the frame.   The illumination device according to claim 5, further comprising an illumination light source that is disposed on the surface of the flat plate and emits white light. A daylighting unit for daylighting,
A duct for guiding the natural light indoors;
A light emitting part for introducing the first light after guiding the duct into the indoor space;
A light source that is provided in the light emission unit and emits second light having a first spectral distribution;
A measuring unit provided at a position closer to the daylighting unit than the light source of the light emitting unit, and measuring a second spectral distribution of the second light;
Using the function for calculating the chromaticity coordinates with the spectral distribution as a variable, the first spectral distribution and the second spectral distribution, the chromaticity coordinates of the third light including the first light and the second light are obtained. A controller that calculates and changes the first spectral distribution in a direction to decrease the distance between the chromaticity coordinates of the third light and the predetermined chromaticity coordinates;
With light duct. A daylighting unit for daylighting,
A duct for guiding the natural light indoors;
A light emitting part for introducing the first light after guiding the duct into the indoor space;
A light source that is provided in the light emission unit and emits second light having a first spectral distribution;
A measuring unit that is provided at a position farther from the daylighting unit than the light source of the light emitting unit, and that measures a second spectral distribution of the third light including the first light and the second light;
A function for calculating chromaticity coordinates using the spectral distribution as a variable, the chromaticity coordinates of the third light using the second spectral distribution, and the chromaticity coordinates of the third light and predetermined chromaticity coordinates. A control unit that controls the first light flux in a direction that reduces the distance to
With light duct.   The optical duct according to claim 7 or 8, comprising a plurality of the light emitting portions.