JP2004166511A - False sunlight irradiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a false sunlight irradiation compact apparatus with small thermal quantity intended for widening application possibility not only for industry but also for other wide fields such as plant raising and capable of dynamically changing irradiation angle, light volume and even emission spectrum property. <P>SOLUTION: This false sunlight irradiation apparatus has a plurality of kinds of LED (light emitting diodes) 24 having emission spectrum properties different from each other. The component ratio of the various kinds of LED 24 or/and emission strengths thereof is(are) appropriately set up so as to make a light synthetic spectrum which is irradiated from each of the LED 24 closely resembles sunlight spectrum as the standard. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a simulated sunlight irradiating device that irradiates simulated sunlight that approximates natural sunlight.
[0002]
[Prior art]
Recently, a method of emitting light of a predetermined wavelength using a light source provided with a large number of LEDs and performing plant growth or the like has been developed. In such a method, there is a request to confirm the effect in comparison with the growth under the natural sun, but the actual sun light fluctuates greatly due to weather and seasonal differences, and it is difficult to use as a reference for comparison. There is a need for a simulated sunlight irradiation device that can be repeatedly reproduced.
[0003]
For industrial purposes such as photography and solar cell efficiency testing, for example, a simulated sunlight irradiating device having a spectral characteristic similar to that of natural sunlight has been developed. Specifically, for example, a lamp using a xenon lamp (Patent Document 1), a lamp using a combination of an incandescent lamp and a fluorescent lamp (Patent Document 2), and a lamp using a microwave lamp are known.
[0004]
[Patent Document 1]
JP-A-6-251887 [Patent Document 2]
JP 9-99106 A
[Problems to be solved by the invention]
However, such an apparatus generates heat and is bulky due to the nature of the light source, so that various inconveniences may occur when used for growing plants.
Considering that it is used as a reference for comparison as described above, in order to approximate actual sunlight that changes with time such as morning, noon, and evening, not only the irradiation angle and light amount but also the optical spectrum characteristics with time are used. It is highly likely that a function that dynamically and dynamically changes is also required. However, in the light source using the xenon lamp or the like, it is almost impossible to change the optical spectrum characteristic dynamically in the first place, and there is a possibility that a problem may occur when controlling the irradiation angle in terms of weight.
[0006]
In view of the above, the present invention has been made to provide a simulated sunlight irradiation apparatus which has a small heat generation amount and is compact, and which can dynamically change an irradiation angle, a light amount, and also an optical spectrum characteristic. The main object of the present invention is to expand the applicability of the simulated sunlight irradiation device in other wide fields such as not only for industrial use but also for growing plants.
[0007]
[Means for Solving the Problems]
That is, the simulated sunlight irradiation device according to the present invention includes a plurality of types of LEDs having different emission spectrum characteristics, and adjusts the composition ratio of the LEDs having different emission spectrum characteristics and / or the emission intensity of each LED. It is characterized in that the combined spectrum of the light emitted from each LED is similar to the sunlight spectrum.
[0008]
In such a case, since the LED is used as a light emitting source, the calorific value is small and the size can be reduced. In addition, by controlling the light emission intensity and the like for each LED, like the natural sunlight spectrum, It is possible to realize a synthesized spectrum that fluctuates according to time, season, and place in one day. Therefore, an environment closer to the natural environment can be artificially created, and its application range can be greatly expanded as compared with the conventional one. Specifically, for example, in plant cultivation, it is possible to provide a more preferable reference environment for comparison, for example, in appreciation or production of paintings, arts, crafts, etc., it is possible to perform more suitable illumination close to natural light. You can do it.
Note that the reference sunlight spectrum may be appropriately determined. As shown in Fig. 4, the actual solar spectrum may differ not only depending on the altitude and weather from the ground, but also depending on the season, weather, and region. What is necessary is just to determine the fictitious thing as a reference sunlight spectrum.
[0009]
Furthermore, according to the present invention, for example, light having a combined spectrum in which only a specific wavelength band is increased or decreased with respect to sunlight can be easily generated. Instead of irradiating plants with light in a wavelength band, the effect of a different approach of irradiating plants with light with an arbitrary wavelength band increased or decreased from sunlight can be confirmed.
[0010]
On the other hand, as shown in FIG. 4, the actual sunlight spectrum is such that the waveform when the horizontal axis represents the wavelength and the vertical axis represents the intensity is a smooth continuous waveform. Since it is unavoidable that the LED becomes discontinuous, the combination of these LEDs and the setting of the light emission intensity alone cause some unevenness in the composite spectrum waveform as shown in FIG. It is difficult to approximate more than a predetermined degree.
[0011]
In order to solve such a problem without difficulty and to allow the synthesized spectrum to be approximated by the sunlight spectrum, it is necessary to change the emission spectrum characteristics of the LED according to the difference in the drive current value when driven by a continuous current. By appropriately setting the drive current value in one or a plurality of LEDs, the combined spectrum of the light emitted from each of the LEDs is configured to approximate the sunlight spectrum. Are preferred.
In such a case, the light emission intensity of each LED may be set according to the DUTY ratio given the current in the PWM method. In other words, the emission intensity of each LED is set by the DUTY ratio of the drive current, while the emission spectrum characteristic is set to a desired characteristic by appropriately setting the HI current value when PWM driving, that is, the peak current value. Just fine.
As shown in FIGS. 6A and 7A, the peak wavelength can be changed in a width of about 10 nm by changing the drive current value even for the same type of LED, and the discontinuity of the wavelength can be effectively reduced. This is because it can be eliminated. FIGS. 6B and 7B show peak wavelengths in the case of PWM driving. In the case of PWM driving, as long as the peak current value is not changed, the emission peak wavelength does not change even if the average current is changed in the same manner as the continuous current.
[0012]
Of course, even LEDs that are commercially available as being of the same type may actually have some variation in the peak wavelength. For example, they may be strictly selected and used as various types of LEDs having a similar peak wavelength. If the setting including the continuous current value is performed for various LEDs, the combined spectrum can be further approximated to the sunlight spectrum.
[0013]
The setting of the light emission intensity and the continuous drive current value for each LED may be performed in advance, or may be dynamically controlled. In particular, in actual sunlight, where the light spectrum and intensity change with time and cycle with a cycle of one day or one year, for example, in plant growing, a pseudo-sun with a temporal change simulating the natural sunlight. It is desirable to create light. As a specific embodiment for realizing this, it further includes a synthesized spectrum control unit for controlling the synthesized spectrum, and the synthesized spectrum control unit changes the synthesized spectrum with time, thereby changing the time of the reference sunlight spectrum. One that is configured to approximate the change can be given. Further, as a specific control mode by the composite spectrum control unit, a current is given in a PWM system, and the DUTY ratio is automatically controlled to control the emission intensity of each LED, while the emission spectrum characteristic of each LED is PWM-driven. It is conceivable to automatically control the HI current value at that time, that is, the peak current value.
[0014]
In order to uniformly mix the light emitted from the LEDs and prevent the combined spectrum from being biased depending on the irradiation place, it is preferable that the light emitting device further includes a light mixing unit that mixes the light emitted from the LEDs.
On the other hand, in the case of the present invention, many types and many LEDs are required, and the LED laying area is large. Therefore, in order to more effectively mix the light emitted from each of the LEDs, a light condensing unit that condenses the light emitted from each of the LEDs to a predetermined area is further provided, and the light mixing unit is provided with a light condensing unit. It is preferable to mix the collected light.
Specifically, the light condensing unit includes a plurality of optical fibers for introducing light emitted from one or a plurality of LEDs, and performs a light condensing operation by bundling light outgoing ends of the optical fibers. The light mixing section may be formed by using a rod lens provided continuously or substantially continuously at a light output end thereof.
[0015]
Taking into account that the irradiation angle of the sunlight changes with time, it is preferable that the emission angle of the light emitted from each of the LEDs can be changed.
In addition to plant cultivation, at the time of appreciation or production of paintings and printed matter, such as how it looks with the intensity of brightness under natural sunlight, to be able to further expand the applicability of the present invention, It is preferable that only the intensity of light emitted from each LED can be changed without changing the combined spectrum.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0017]
The simulated sunlight irradiation device 1 according to the present embodiment includes a main body 2 including a light source unit 21 and a casing 22, and a power supply unit 3 that supplies power to the light source unit 21 as shown in FIGS. And is used, for example, to create an environment that serves as a standard for plant growth.
[0018]
More specifically, the light source unit 21 includes a printed circuit board 23, a plurality of LEDs 24 disposed on the printed circuit board 23, and a light mixing unit 25. The printed circuit board 23 has a rectangular plate shape, but may have other shapes such as a polygonal plate or a disk shape. A plurality of types (approximately 30 types) of different peak wavelengths are used as the LEDs 24 laid on the substrate 23. One or more LEDs 24 are prepared for each type, and the composition ratio of the LEDs 24 for each type is determined in advance. To be the predetermined one. Although the arrangement | positioning part of LED24 may be collectively classified for every kind, in this embodiment, in order to eliminate the deviation by the position of the synthetic | combination spectrum of the light emitted from these LED24 as much as possible, various LED24 should be as evenly as possible. It is arranged in the whole. The light mixing section 25 is a translucent or transparent rectangular plate having substantially the same contour as the printed circuit board 23, and is disposed on the light emitting end side of the LED 24.
[0019]
The casing 22 holds the light source unit 21. The casing 22 is provided with a heat radiating member (not shown) for radiating the heat generated in the light source section 21, for example.
[0020]
As shown in FIGS. 1 and 8, the power supply unit 3 supplies power to each of the LEDs 24 in a predetermined manner, and according to the power supply manner, a natural spectrum based on a combined spectrum of light emitted from the light source unit 21 is used as a reference. It approximates the light spectrum of sunlight. This device includes a light emission intensity setting unit 32 for setting the light emission intensity of each LED 24, a peak wavelength setting unit 31 for setting the peak wavelength of each LED 24, and an output unit 33.
[0021]
The light emission intensity setting section 32 determines the light emission intensity by driving each LED 24 by PWM and setting its DUTY ratio.
The peak wavelength setting unit 31 utilizes the phenomenon that the peak wavelength of the emission spectrum of the LED 24 fluctuates around 10 nm according to the applied peak current value, as shown in the experimental results of FIGS. By setting the peak current value of the LED 24 that is DUTY-driven, that is, the HI current value, to a predetermined value, even if the LED 24 is of the same type, the light spectrum characteristics of the LED 24 are slightly different as necessary. Is what it is. As described above, the current value set by the peak wavelength setting unit 31 is completely different from the general purpose of setting the emission intensity of the LED 24.
[0022]
The output unit 33 outputs power to each LED 24 in a unique manner based on each HI current value determined by the peak wavelength setting unit 31 and each DUTY ratio determined by the emission intensity setting unit 32. It is.
[0023]
The composition ratio of the various LEDs 24, the DUTY ratio of the current supplied to each LED 24, and the HI current value are appropriately set in advance so that the synthesized spectrum becomes similar to the reference sunlight spectrum. ing.
[0024]
According to the simulated sunlight irradiating device 1 according to the present embodiment configured as described above, since the LED 24 is used as a light emitting source, the amount of heat generation is small, and compactness is possible.
[0025]
Further, since the driving peak current value of one or a plurality of LEDs is appropriately set by utilizing the fact that the emission spectrum characteristic of the LED changes according to the difference of the peak current value, the peak wavelength which is the basic wavelength of the various LEDs 24 is set. Is discontinuous, the peak wavelength between them is filled, the continuity of the synthesized spectrum with respect to the wavelength is further increased, and a synthesized spectrum very similar to the sunlight spectrum can be created without difficulty.
FIG. 5 shows a composite spectrum in the case where the peak current value is not set and the emission intensity and the composition ratio of each LED are simply set. If the peak current value is set, the peak current value becomes smoother and approximates to the reference sunlight spectrum.
[0026]
Further, in addition to arranging the various LEDs 24 as evenly as possible over the whole, and since the light mixing section 25 is arranged on the light emitting end side of the LED 24, the combined spectrum of the light emitted from the light source 21 is The deviation due to the position can be prevented as much as possible.
[0027]
Note that the present invention is not limited to the above embodiment. For example, a configuration may be adopted in which the drive duty ratio and the peak current value for each LED can be changed stepwise by an external operation.
Specifically, for example, by operating a switch or the like, the combined spectrum is stepwise so as to be approximated to a plurality of reference sunlight spectra set according to differences in time, season, region, and the like. The setting may be made.
[0028]
As shown in FIG. 9, a light spectrum detecting unit 4 that detects a combined spectrum of light emitted from the light source unit 21, a storage unit 5 that stores a reference sunlight spectrum as data in advance, Each LED 24 is controlled by the peak wavelength setting unit 31 and the emission intensity setting unit 32 so that the combined spectrum detected by the light spectrum detection unit 4 approaches the sunlight spectrum stored in the storage unit 5. A combined spectrum control unit 6 for automatically performing feedback control of the driving peak current value and the DUTY ratio may be further provided. In this way, the combined spectrum control unit 6 can keep the combined spectrum stable irrespective of the aging of the LED 24 or the like.
[0029]
Further, in this case, the reference solar spectrum data stored in the storage unit 5 may be changed using time as a parameter. In other words, the spectrum of the actual natural sunlight fluctuates according to the time, season, and place in a day. If the reference sunlight spectrum is changed over time to simulate the change, the synthesis follows. Since the spectrum also dynamically changes, an environment closer to the natural environment can be artificially created. This makes it possible to provide a more suitable reference environment for comparison, for example, in growing plants.
[0030]
In addition, the emission angle of the light emitted from the light source unit may be configured to be changeable. Specifically, a main body support portion (not shown) that supports the main body so that the angle of the main body can be changed is provided, and the main body support angle is changed with time so that sunlight gradually changes the angle in the morning, noon, and evening. It is preferable to provide a support angle control unit (not shown).
Further, a light condensing unit for condensing the light emitted from each of the LEDs to a predetermined area may be further provided, and the condensed light may be mixed by the light mixing unit. In the following description, members corresponding to the above embodiment will be denoted by the same reference numerals.
Specifically, as shown in FIG. 10, the condensing unit 7 includes a plurality of optical fibers 71 for introducing light emitted from one or a plurality of LEDs 24, and bundles the light leading ends of the optical fibers 71. It is conceivable to provide the light mixing section 25 continuously or substantially continuously at the light output end 71a. The light mixing unit 25 is a cylindrical rod lens that reflects and mixes the light introduced from one end face inside without escaping from the side face, and emits the light from the other end face. Of course, the light condensing unit may use a lens, and the light mixing unit may have other forms than the rod lens.
In the case of this device, since a large variety of LEDs are required and the area of the light source section becomes considerably large, it is better to mix the light once collected than to mix the light emitted from each LED directly. This is because more uniform light can be obtained.
Furthermore, in order to further expand the applicability of the present invention, such as how to look at the intensity of brightness under natural sunlight in appreciation and production of paintings and printed matter as well as plant growth, It is preferable that only the intensity of light emitted from each LED can be changed without changing the combined spectrum. Specifically, the ratio of the light emission intensity of each LED may be moved up and down uniformly.
[0031]
In addition, the present invention is not limited to the illustrated example, and various changes can be made without departing from the gist of the present invention.
[0032]
【The invention's effect】
As described in detail above, according to the present invention, since the LED is used as a light emitting source, the amount of generated heat is small and the size can be reduced. As in the case of the optical spectrum, it is possible to realize a composite spectrum that varies according to time, season, and place in one day. As a result, it is possible to artificially create an environment closer to the natural environment, for example, in plant cultivation, to provide a more suitable reference environment for comparison, or in, for example, appreciation or production of paintings, arts, crafts, etc. Can be used in various ways that are not applicable to the conventional simulated sunlight irradiating device, such as being able to perform more suitable illumination close to natural light.
[0033]
Furthermore, according to the present invention, for example, light having a combined spectrum in which only a specific wavelength band is increased or decreased with respect to sunlight can be easily generated. Instead of irradiating plants with light in a wavelength band, the effect of a different approach of irradiating plants with light having an arbitrary wavelength band increased or decreased from sunlight can be confirmed.
[Brief description of the drawings]
FIG. 1 is an overall front view of a simulated sunlight irradiation apparatus according to an embodiment of the present invention.
FIG. 2 is a front view of the main body of the embodiment with a part broken.
FIG. 3 is a bottom view of the main body in the embodiment.
FIG. 4 is a sunlight spectrum waveform diagram as a reference in the embodiment.
FIG. 5 is a composite spectrum waveform diagram when only emission intensity control is performed in the embodiment.
FIG. 6 is a wavelength change diagram showing a change in peak wavelength when an LED having a basic peak wavelength of 472 nm is driven by a continuous current (a) and when the LED is driven by PWM (b).
FIG. 7 is a wavelength change diagram showing a change in peak wavelength when an LED having a basic peak wavelength of 524 nm is driven by a continuous current (a) and when the LED is driven by PWM (b).
FIG. 8 is a functional block diagram of a power supply unit in the embodiment.
FIG. 9 is a functional block diagram of a power supply unit according to another embodiment of the present invention.
FIG. 10 is a schematic view showing a light source unit according to still another embodiment of the present invention.
[Explanation of symbols]
1. Simulated sunlight irradiation device.
24 ・ ・ ・ LED
25 light mixing unit 6 synthesized spectrum control unit

Claims (12)

A plurality of types of LEDs having different emission spectrum characteristics are provided, and a combination composition ratio of these various LEDs or / and their emission intensities are appropriately set, and a combined spectrum of light emitted from each of the LEDs is set as a reference. A pseudo sunlight irradiator configured to approximate the solar spectrum. A plurality of the reference sunlight spectra can be provided in accordance with a difference in time, season, region, and the like, and the combined spectrum can be set in a stepwise manner so as to approximate each of the plurality of reference sunlight spectra. 2. The simulated sunlight irradiation device according to claim 1, wherein: By utilizing the fact that the emission spectrum characteristic of an LED changes in accordance with the difference in the drive current value when driven by a continuous current, the drive current value of one or a plurality of LEDs is appropriately set so that the emission of the LED can be improved. The simulated sunlight irradiation device according to claim 1 or 2, wherein the spectrum characteristics are set to desired characteristics, and the combined spectrum of the light emitted from each of the LEDs is configured to approximate a sunlight spectrum. The current is given by the PWM method, the emission intensity of each LED is set according to the DUTY ratio, and the emission current characteristic of the LED is changed according to the difference of the applied peak current value. The light emission spectrum characteristic of the LED is set to a desired characteristic by appropriately setting, and the combined spectrum of light emitted from each of the LEDs is configured to be close to the sunlight spectrum. 3. The simulated sunlight irradiation device according to 2. A composite spectrum control unit for controlling the composite spectrum, wherein the composite spectrum control unit changes the composite spectrum with time to approximate the temporal change of a reference sunlight spectrum. The simulated sunlight irradiation device according to 1, 2, 3, or 4. The simulated sunlight irradiation device according to claim 5, wherein the combined spectrum control unit controls the combined spectrum by adjusting the emission intensity of each LED. The simulated sunlight irradiation device according to claim 5, wherein the combined spectrum control unit controls a combined spectrum by changing an emission spectrum characteristic of each LED. The simulated sunlight irradiation device according to claim 1, further comprising a light mixing unit that mixes light emitted from each of the LEDs. 9. The simulated sunlight irradiation device according to claim 8, further comprising a light condensing unit that condenses the light emitted from each of the LEDs to a predetermined area, wherein the light mixing unit mixes the collected light. . The light condensing unit is provided with a plurality of optical fibers for introducing light emitted from one or a plurality of LEDs, and performs a light condensing action by bundling light outgoing ends of the optical fibers, The simulated sunlight irradiation device according to claim 9, wherein the light mixing unit uses a rod lens provided continuously or substantially continuously at the light output end. The simulated sunlight irradiation device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein an emission angle of light emitted from each of the LEDs is changeable. The structure which can change only the intensity | strength of the light emitted from each said LED, without changing the said composite spectrum, Claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 12. The simulated sunlight irradiation device according to item 11.

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