JP6712149B2 - LED light source device - Google Patents

Description

The present invention relates to an LED light source device, and more particularly, to an LED light source device capable of reproducing natural/artificial illumination in a living environment and a special environment on a surface to be illuminated with a high degree of spectral approximation, and particularly with a low light intensity and a high degree of light intensity uniformity.

A light source device is used to measure the output performance of a two-dimensional light receiving element such as a solar cell and to inspect its uniformity.

In such a light source device, a combination of a xenon lamp and a halogen lamp is used as a light source (see Patent Documents 1 to 4). These light sources are called lamp light sources.

FIG. 1 is a conceptual configuration diagram for explaining a conventional light source device using a lamp light source of a combination of such a xenon lamp and a halogen lamp.

In FIG. 1, the light flux emitted from the lamp light source 1 arranged at the focal point of the parabolic mirror 2 is reflected by the first reflecting mirror 3 and enters the integrator 4. The light of the quantity of light made uniform by the integrator 4 is emitted again and is irradiated onto the irradiated surface 7 through the second reflecting mirror 5 and the optical system 6.

The light source device can be used as, for example, a solar simulator. In the case of a solar simulator, it is possible to use the irradiated surface 7 irradiated with the light emission of the lamp light source 1 simulated in the spectrum of sunlight as the surface of the solar cell to measure the luminous efficiency of the solar cell.

The light source device using the lamp light source 1 as described above has a problem that the life of the lamp is short, particularly when irradiation with high intensity is required. Further, since the loss of the optical system is large, only a few percent of the electric power supplied to the lamp is irradiated as light, and it is difficult to save power. Further, since the lamp light source simultaneously generates unnecessary infrared rays, there is a problem that the irradiation surface and the sample placed on the irradiation surface are unnecessarily heated.

In order to eliminate the disadvantage of the light source device by the lamp light source 1, an LED light source device using a light emitting diode (LED) as a light source has also been developed. A solar cell evaluation method and device using such an LED light source device have also been proposed (Patent Documents 5 to 8).

JP, 2010-251387, A JP, 2010-271685, A JP, 2011-119322, A JP, 2011-222655, A JP 2004-281706 A JP, 2010-287647, A JP, 2011-9248, A Japanese Patent No. 4944231

The techniques disclosed in Patent Documents 5 to 8 described above are evaluation methods and evaluation devices exclusively for evaluating the characteristics of solar cells, and a specific small number of wavelengths, for example, in Patent Document 5, infrared rays, LEDs of three wavelength bands of red and blue and a wide wavelength band of white are used. In Patent Documents 6 and 7, LEDs of wavelength bands of infrared, ultraviolet, red, and blue are used.

Then, in the invention described in Patent Document 5, each LED is caused to emit light, the absolute spectral sensitivity of the corresponding LED is acquired, and the absolute spectral sensitivity curve of the solar cell is calculated from the value of the absolute spectral sensitivity of each LED. Is disclosed.

The inventions described in Patent Documents 6 and 7 are based on the solar cell characteristic evaluation method of Patent Document 5, and are water-cooling type cooling units for eliminating the variation in the luminous efficiency of the LEDs due to the temperature in the solar cell evaluation apparatus used therefor. Is disclosed.

However, in the techniques disclosed in Patent Documents 5 to 7, the emission line spectrum of the LED emission color is discrete, and it is difficult to more ideally approximate the target spectrum.

In addition, various lighting applications are currently considered in addition to the solar simulator and the solar cell characteristic evaluation as described in Patent Documents 1 to 8 described above. In addition to conventional simulation of specific light, we are thinking of simulating indoor light, checking colors in different environments such as painted materials and printed materials, and special lighting aiming at efficient cultivation and cultivation of plants in artificial environments. Has been.

On the other hand, in recent years, there have been many opportunities to use mobile devices such as smartphones in a low illumination environment such as indoors. At that time, a charging device using a solar cell is used as an auxiliary power source for a mobile device. Therefore, similarly, it is necessary to evaluate the characteristics of the solar cell used in such a charging device, particularly the characteristics in a low illuminance environment.

For that purpose, a light source device that enables illumination with low illuminance is required. However, a light source device that accurately simulates the sunlight spectrum in low illuminance has not been provided so far.

Therefore, in view of the above-mentioned conventional technical situation, an object of the present invention is to provide an LED light source device using an LED light source capable of outputting light of a sunlight spectrum with a high degree of spectrum approximation and a high degree of light quantity uniformity even in low illuminance. It is in.

An LED light source device according to the present invention which solves the above-mentioned problems has, as a basic aspect, an LED light source configured by a plurality of LED elements each having a different emission wavelength, and a drive current is supplied to the plurality of LED elements of the LED light source. An LED drive unit, a feedback control unit that determines the emission intensity of each of the plurality of LED elements corresponding to a predetermined wavelength spectrum, and controls the drive current of the LED drive unit, and emits light emitted by the LED light source. The illuminated surface to be received, and a spectral radiometer for measuring the intensity of each illuminance of the illuminated surface for each wavelength, based on the intensity of each wavelength measured by the spectral radiometer, the feedback control unit is the predetermined The drive current of the LED drive unit is controlled so as to correspond to the wavelength spectrum, and the LED drive unit drives the plurality of LED elements at a constant current, and further detects the current flowing through the plurality of LED elements to detect the current. It is characterized in that constant current driving is feedback-controlled.

The LED light source device according to the present invention for solving the above-mentioned problems is, in the basic aspect, further, a plurality of LED light sources are composed of a laser element and a phosphor, and the phosphor is excited by the laser element. , Emitting light of a predetermined wavelength.

LED light source device according to the present invention to solve the above problems, in the basic aspect, further, each of the output light of the plurality of LED light sources, irradiating the irradiated surface through an integrator, the irradiation surface by the It is characterized in that the wavelengths of the output lights of a plurality of LED light sources are combined.

Further, the output lights of the plurality of LED light sources are wavelength-combined through a common integrator, and the output light of the common integrator is applied to the illuminated surface.

Further, when an LED light source having a specific emission wavelength cannot be obtained, the output of the LED light source having an adjacent wavelength is approximated to the specific emission wavelength through a spatial filter.

As described above, it is possible to provide an LED light-emitting device having a simple device configuration and capable of outputting light of a target spectrum with an arbitrary illuminance from 1 SUN at maximum to 1/10000 SUN, which is about the brightness of candles.

It is a conceptual block diagram explaining the conventional light source device which uses the lamp light source of the combination of a xenon lamp and a halogen lamp. 1 is a block diagram of an embodiment of an LED light source device according to the present invention. It is a figure explaining spectrum combination by a some light source in a light source device. It is a figure which shows the example of the table of several predetermined|prescribed spectrum information previously stored in the memory|storage device 14 shown in FIG. It is a figure which shows one structural example of an LED light source device. It is a figure which shows the example which carries out spectrum shaping by a spatial filter array. It is a figure explaining the measurement result (1SUN) of the spectrum when using the LED light source device according to this invention for a solar cell light source. It is a figure explaining the measurement result (1/10000SUN) of the spectrum when the LED light source device according to this invention is used for the low illuminance of a solar cell light source.

An embodiment of an LED light source device according to the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of an LED light source device according to the present invention.

The LED light source device includes a control device 10, an LED light source 11 including a plurality of LED elements whose light emission is controlled by the control device 10, a sensor unit 130 provided on a surface 12 to be illuminated by the LED light source 11, and a main body unit. A spectral radiometer 13 composed of 131 and a storage device 14 are further provided.

The control device 10 includes an information processing unit 100 having a function similar to that of a personal computer that executes a management program, a feedback control unit 101, and an LED driving unit 102 that can handle low illuminance. Further, an analog output unit 102a for controlling the LED light source 11 with a constant current and an analog input unit 102b for detecting an actual current value flowing in the LED light source 11 are provided between the LED driving unit 102 and the LED light source 11.

The storage device 14 is provided outside the control device 10 independently or as an attachment unit of the information processing unit 100. Then, by executing the management program in the information processing unit 100, the predetermined spectrum data corresponding to each of the plurality of light sources is stored in the storage device 14 in a writable/readable manner.

In FIG. 2, the LED light source 11 uses a light source having a narrow emission spectrum width (hereinafter, simply referred to as an LED element) such as a light emitting diode (LED element) or a semiconductor laser, which has a longer life and is excellent in energy efficiency. A plurality of LED elements having different emission wavelength characteristics are selected so as to cover all of the required spectral band.

As shown in FIG. 2, the irradiated surface 12 is irradiated with light emitted from the LED light source 11 whose output level is adjusted by the control device 10.

An illuminance sensor 130 having a functional unit (spectral means for detecting optical characteristics of the radiated surface 12: spectral radiometer) 13 integrated with a main body 131 is incorporated in the illuminated surface 12 in real time. This makes it possible to measure the spectrum of the irradiation light during irradiation.

Since each LED element of the LED light source 11 contributes to a unique spectral region in the spectral distribution, a computer is required to set the intensity of a specific spectral region in the spectrum measured by the spectroradiometer 13 to a desired value. The light emission intensity is feedback-controlled by the feedback control unit 101 composed of software or logic control hardware and a user interface (hardware/software).

That is, the feedback control unit 101 stores the measured value of the illuminance of each wavelength band measured by the spectroradiometer 13 and the predetermined value in order to correspond to the predetermined wavelength spectrum of the light source desired by the user and stored in the storage device 14 in advance. The LED drive unit 102 is controlled so as to compare the wavelength spectrum and reduce the difference.

The LED driving unit 102 sets the constant current value of the analog output unit 102a corresponding to the control value from the feedback control unit 101 and drives the LED light source 11. Further, the LED driving unit 102 inputs the actual current value of the LED light source 11 detected by the analog input unit 102b, and performs feedback control on the analog output unit 102a so that the constant current value becomes the previous constant current value.

Here, the LED drive unit 102, the analog output unit 102a, and the analog input unit 102b reproduce the output illuminance at low illuminance (11 lux to 1123 lux) with high light intensity uniformity so that the LED light source 11 can emit low illuminance. It is designed to be able to.

The present invention is characterized by the dual feedback control of the feedback control by the above feedback control unit 101 and the feedback control by the LED driving unit 102, whereby the range of 1/10000 SUN to 1 SUN, that is, the light of a candle. It is possible to reproduce an LED light source device capable of outputting light with low illuminance to illuminance under outdoor sunlight with a high degree of spectral approximation.

FIG. 3 is a diagram for explaining spectrum synthesis by a plurality of light sources in the light source device 10. By sequentially arranging the wavelengths (λ _{1 to} λ _n ) of a plurality of LED elements each having a narrow emission spectrum width, a spectrum synthesis 30 in a predetermined band can be obtained as shown in FIG. 3(1). Then, by controlling the emission intensity of each LED element so as to correspond to the predetermined emission spectrum 31 (FIG. 3B) desired by the user stored in the storage device 14 in advance, the emission spectrum corresponding to the desired spectrum 31 is obtained. A synthetic spectrum can be generated.

FIG. 4 is a diagram showing an example of a spectrum information table stored in advance in the storage device 14 shown in FIG. 2 and corresponding to the emission spectrum 31 desired by the user. In this spectrum information table, the emission center frequency (f _{1 to} f _n ) and the illuminance (L _{1 to} L _n ) corresponding to the desired emission spectrum 31 are set for each LED element (No. _{1 to n} ) serving as a light source. It is registered.

The feedback control unit 101 obtains the spectral illuminance distribution in real time from the spectral radiometer 13 and obtains the actual illuminance on the illuminated surface 12 for each LED element (No. 1 to No. n) of the LED light source 11 and the spectrum of FIG. The illuminance (L _{1 to} L _n ) corresponding to the desired spectrum in the information table is compared to obtain the difference. Next, a control signal is sent to the LED drive unit 102 so that this difference becomes zero, and the current of the corresponding LED element is controlled to match the illuminance of the desired spectrum 31 in the spectrum information table (FIG. 4).

FIG. 5 shows an example of the configuration of the LED light source 11. A plurality of light sources having the same configuration (three light sources in the figure for simplification) are shown. The light source uses light emitting diodes (LED elements) 20A (20B, 20C). Here, each of the LED elements 20A (20B, 20C) may be composed of a plurality of LED elements of the same standard so as to obtain a required light emission intensity.

The light emitted from the LED element 20A (20B, 20C) is input to the integrator 22A (22B, 22C) through the coupling optical system 21A (21B, 21C). By the integrator 22A (22B, 22C), the illuminance of light emitted from the LED element 20A (20B, 20C) can be made uniform.

The output of the integrator 22A (22B, 22C) is radiated again through the projection optical system D1 (D2, D3) and is radiated to the illuminated surface 12. As shown in the figure, the light from each light source is arranged by the integrator 22A (22B, 22C) so that the illuminance surface distribution on the illuminated surface 12 becomes uniform. Since the radiation angle characteristic of each light source is peculiar to the light source, the coupling optical system 21A (21B, 21C) is set so that the loss upon incidence on the integrator 22A (22B, 22C) is minimized.

Each of the three LED elements 20A (20B, 20C) has a different wavelength spectrum. Therefore, the spectrum of the light irradiated on the irradiated surface 12 is obtained by superimposing (combining) different wavelength spectra of the three light sources.

That is, in the most basic configuration, the distributions of the light beams from the three light sources are adjusted by the integrators and are combined on the irradiated surface 12. That is, each of the three light sources has a different wavelength spectrum. Therefore, the spectrum of the light irradiated on the irradiated surface 12 is obtained by superimposing (combining) different wavelength spectra of the three light sources.

At this time, instead of the configuration in which the projection optical system D1 (D2, D3) is used to image-illuminate the illuminated surface 12, the exit end surface of the projection optical system D1 (D2, D3) is used as a secondary light source. It is possible to use Koehler illumination for forming an image on the illuminated surface 25 by using a lens as a diaphragm according to the purpose.

In the light source device 10 of FIG. 5 described above, the spectral distribution of the irradiation light flux is basically a superposition of the intensity spectral distributions of all the light sources. In order to continuously cover a desired wavelength band, a sufficient type of light source is required, and each spectral width needs to be appropriate. Since the intensity of each light source can be easily changed by the power source and the LED driving unit 102, the degree of freedom of spectrum generation can be secured as a whole.

Here, in the above configuration, when wavelength selection is performed from procurable LED elements, it is assumed that a light source that completely covers the desired wavelength band cannot be obtained.

In such a case, if there is a light source having a sufficient spectral width in the vicinity wavelength, by passing it through an appropriately designed optical filter, or by spectral shaping with a spatial filter array having wavelength discriminating property, It can be used as a desired light source. At this time, spatial intensity/spectral unevenness inevitably occurs in the light flux after passing through the filter, but such unevenness is eliminated by passing through the integrator.

FIG. 6 is a diagram for explaining such correspondence and is an example of spectrum shaping by a spatial filter array. When a light source having a wavelength λ cannot be obtained ((1) in FIG. 6), it is assumed that a spectrum of light sources having adjacent wavelengths is synthesized and obtained.

In FIG. 6A, spectra A and B are emission spectra of the light source A and the light source B adjacent to the spectrum D, respectively. When the light source corresponding to the spectrum D cannot be procured, the spectra A and B are first combined to generate the combined spectrum C (FIG. 6(2)).

Then, the combined light E of the combined spectrum C of the light source A and the light source B is passed through the spatial filter 70 (FIG. 6(3)), so that after passing through the spatial filter 70, the spectrum D of the central wavelength λ (FIG. 6(4)). ) Can be generated.

The spatial filter 70 is a two-dimensional or one-dimensional array of filters having different transmission characteristics. If the light beam passing through this filter array has a finite thickness, it is possible to change the spectrum of each part of the light beam and re-assemble it at the exit. By doing so, it is possible to finely adjust the spectrum to be obtained.

There are also the following methods to deal with cases where the light source cannot be procured in the market.

At present, semiconductor laser light sources and light emitting diodes having a short wavelength and a high output are available in the market. As already demonstrated and realized in white light emitting diodes, if a phosphor that efficiently emits fluorescence in a desired wavelength band is used, it can be designed properly by exciting the phosphor with the laser light source and the light emitting diode light source. A bandpass optical filter can be used as a light source in a desired wavelength band.

FIG. 7 is a diagram illustrating a spectrum measurement result when the LED light source device according to the present invention described above is used in a solar simulator. The solar simulator is a device used when indoors are used to measure the luminous efficiency of solar cells and the like. Therefore, the illumination device used as the solar simulator is required to output irradiation light that is close to the spectrum of sunlight.

In FIG. 7, spectrum I is the spectrum of sunlight. Spectrum II is the spectrum of the LED light source device according to the present invention.

As can be easily understood from the figure, in the LED light source device according to the present invention, some peak values are partially present, but in the wavelength region of 400 nm to 800 nm, the emission spectrum is hardly jumped and the entire spectrum is almost continuous. It can be seen that it can occur and preferably approximates the spectrum I of sunlight.

FIG. 8 shows a spectrum in the case of low illuminance (1/10000 SUN) equivalent to the light of a candle. Similarly, spectrum I is the spectrum of sunlight. Spectrum II is the spectrum of the LED light source device according to the present invention.

Also from this figure, according to the present invention, a spectrum close to the reference sunlight spectrum can be obtained even in low illuminance. The horizontal axis represents wavelength and the vertical axis represents illuminance.

Here, by selecting an efficient LED element and performing an appropriate thermal design, it is possible to maintain the temperature of the LED light source constant by general forced air cooling without having a large-scale mechanism such as water cooling. is there.

As described above, the LED light source device according to the present invention has a simple device configuration that uses a light source that can be operated at an extremely long life and at an economical power consumption rate. It is possible to use a device with low power consumption, such as a laser light source or a light emitting diode light source, which provides a light source device that can be changed and generates and emits a uniform luminous flux, which is a great industrial contribution.

10 Control device
100 information processing unit 101 feedback control unit 102 LED driving unit 102a analog output unit 102b analog input unit
11 LED Light Source 12 Illuminated Surface 13 Spectral Radiometer 130 Illuminance Sensor 131 Spectral Radiometer Main Body 14 Storage Device

Claims (5)

An LED light source composed of a plurality of LED elements each having a different emission wavelength,
An LED drive unit that supplies a drive current to a plurality of LED elements of the LED light source;
A feedback control unit that determines the emission intensity of each of the plurality of LED elements corresponding to a predetermined wavelength spectrum and controls the drive current of the LED drive unit;
A surface to be illuminated which is illuminated by the LED light source;
A spectral radiometer for measuring the intensity of each illuminance of the illuminated surface for each wavelength ,
An analog output section for driving the LED light source with a constant current;
An analog input unit for detecting the actual current value of the LED light source,
Based on the intensity of each wavelength to be measured by the spectroradiometer, the feedback control section feedback controls the driving current of the LED driving unit so as to correspond to said predetermined wavelength spectrum, the further output of the analog input section The LED driving section feedback-controls constant current driving of the analog output section ,
An LED light source device characterized by the above. In claim 1,
The plurality of LED light sources are composed of a laser element and a phosphor,
The LED light source device, wherein the phosphor is excited by the laser element and emits light of a predetermined wavelength. In claim 2,
Furthermore, the output light of each of the plurality of LED light sources is applied to the irradiation target surface through an integrator, and the wavelengths of the output lights of the plurality of LED light sources are combined on the irradiation target surface.
An LED light source device characterized by the above. In Claim 2 or 3,
Further, the output lights of the plurality of LED light sources are wavelength-combined through a common integrator, and the output light of the common integrator is applied to the irradiation surface.
An LED light source device characterized by the above. In claim 1 or 2,
When an LED light source with a specific emission wavelength cannot be obtained, the output of the LED light source with an adjacent wavelength is approximated to the specific emission wavelength through a spatial filter.
An LED light source device characterized by the above.