WO2021079758A1

WO2021079758A1 - Light-emitting device and light source device

Info

Publication number: WO2021079758A1
Application number: PCT/JP2020/038250
Authority: WO
Inventors: 透菅野; 豪鎌田; 裕一一ノ瀬; 英臣由井
Original assignee: シャープ株式会社
Priority date: 2019-10-23
Filing date: 2020-10-09
Publication date: 2021-04-29
Also published as: JP2023002847A

Abstract

The present invention provides a light-emitting device for emitting fluorescence upon receipt of excitation light from an excitation light source at a fluorescent source, such that the light-emitting device emits fluorescence at a desired intensity irrespective of pretreatment.　The light-emitting device has an excitation light source, a fluorescent layer, a light-receiving element, and an adjustment device. The adjustment device increases the intensity of the excitation light per unit area on the fluorescent layer if the phase of the intensity of the received fluorescence and the phase of the intensity of the excitation light are the same, or decreases the intensity if otherwise.

Description

Light emitting device and light source device

The following disclosure relates to a light emitting device and a light source device.

This application claims priority to Japanese Patent Application No. 2019-192807 filed in Japan on October 23, 2019, the contents of which are incorporated herein by reference.

Conventionally, an image display device such as a projector that modulates the light from a light source to display an image has been widely used. As the light source of the image display device, a device having a solid-state light source such as an LED (Light Emitting Diode) or LD (Laser Diode) and a fluorescent film that receives the excitation light emitted by the solid-state light source and emits fluorescence is used. Regarding the device, there is known a technique capable of measuring each emitted light emitted by the device by controlling the light sampling interval by the sensor unit (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-13845

In the above-mentioned device in which the fluorescence film receives the excitation light and emits fluorescence, heat is generally generated in the fluorescence film according to the power of the excitation light. In addition, the emission characteristics of the fluorescent film usually have temperature dependence. Therefore, the emission characteristics of the fluorescent film vary depending on the temperature of the fluorescent film. Therefore, it is difficult to use the above light source under the condition that the maximum luminous efficiency is always obtained.

As a method of using the fluorescent film with the maximum luminous efficiency, a method of measuring the temperature of the fluorescent film and feeding it back to the control of the power of the excitation light can be considered, but the following problems can be considered in this method. For example, it is necessary to perform prior processing such as preparing a table of driving conditions of a solid light source with respect to the temperature of the fluorescent film according to the accurate temperature characteristics and film thickness of the fluorescent film. However, the temperature of the fluorescence film generally increases non-linearly with respect to the increase in the intensity of excitation light per unit area in the fluorescence film, and the temperature of the fluorescence film affects the fluorescence intensity. Further, the emission characteristics of the fluorescent film include individual differences of the fluorescent film. Therefore, it is difficult to analyze the peak emission intensity of fluorescence from the temperature of the fluorescent film.

One aspect of the present invention is an object of a light emitting device that receives excitation light from an excitation light source by a fluorescence source and emits fluorescence, and generates light emission at a desired emission intensity without depending on prior treatment.

In order to solve the above problems, the light emitting device according to one aspect of the present invention includes an excitation light source for irradiating excitation light, a fluorescence source that receives the excitation light from the excitation light source and emits fluorescence, and the above. A light receiving element that receives a part of the fluorescence emitted by the fluorescence source and a phase of the fluorescence intensity received by the light receiving element are detected, and the excitation in the fluorescence source is performed according to the detected phase of the fluorescence intensity. It has an adjusting device for adjusting the intensity per unit area of light, and the adjusting device has the excitation in the fluorescence source when the phase of the intensity of the fluorescence is the same as the phase of the intensity of the excitation light. The intensity per unit area of light is increased, and when the phase of the intensity of the fluorescence is opposite to the phase of the intensity of the excitation light, the intensity of the excitation light in the fluorescence source per unit area is decreased.

Further, in order to solve the above problems, the light source device according to one aspect of the present invention includes the above light emitting device and an optical system for controlling one or both optical paths of the excitation light and the fluorescence. Have.

According to one aspect of the present invention, in a light emitting device that receives excitation light from an excitation light source with a fluorescence source and emits fluorescence, fluorescence can be generated with a desired intensity without prior treatment.

It is a figure which shows typically the structure of the light emitting device which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the relationship between the laser power density of the excitation light and the emission intensity of fluorescence in the light emitting device of FIG. It is a figure which shows an example of the relationship between the laser power density of the excitation light in the light emitting device of FIG. 1 and the temperature of a fluorescent layer. It is a figure which shows an example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the region where the emission intensity increases in the light emitting device of FIG. It is a figure which shows an example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the peak intensity region in the light emitting device of FIG. It is a figure which shows an example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the region where the emission intensity decreases in the light emitting device of FIG. It is a figure which shows another example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the region where the emission intensity increases in the light emitting device of FIG. It is a figure which shows another example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the peak intensity region in the light emitting device of FIG. It is a figure which shows another example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the region where the emission intensity is reduced in the light emitting device of FIG. It is a figure which shows typically the structure of the light emitting device which concerns on Embodiment 2 of this invention. It is a figure which shows typically the structure of the light emitting device which concerns on Embodiment 3 of this invention. It is a perspective view which shows typically the structure of the main part in the light emitting device which concerns on Embodiment 3 of this invention. It is a figure which shows typically the structure of the light emitting device which concerns on Embodiment 4 of this invention. It is a figure for introducing the structure of the light source apparatus which concerns on Embodiment 5 of this invention. It is a figure which shows typically the structure of the light source apparatus which concerns on Embodiment 6 of this invention.

[Embodiment 1]
(Configuration of light emitting device)
Hereinafter, one embodiment of the present invention will be described in detail. FIG. 1 is a diagram schematically showing a configuration of a light emitting device according to a first embodiment of the present invention. As shown in FIG. 1, the light emitting device 10 includes an excitation light source 11, a fluorescence generator 12, a light receiving element 13, and an adjusting device 14.

(Excitation light source)
The excitation light source 11 is a light source for irradiating the excitation light. The excitation light is light that excites a phosphor in the fluorescent layer to generate fluorescence from the fluorescent layer when it is irradiated to the fluorescent layer described later. The excitation light is not limited as long as it is such light. The excitation light source 11 is, for example, a blue laser or a blue LED.

(Fluorescence generator)
The fluorescence generator 12 is a device that receives excitation light from the excitation light source 11 and emits fluorescence. The fluorescence generator 12 has a reflection substrate 121 and a fluorescence layer 122.

The reflective substrate 121 has a property of supporting the fluorescent layer 122 on its surface and reflecting light. The reflective substrate 121 preferably has a high reflectance to light. Further, the reflective substrate 121 preferably has a high thermal conductivity from the viewpoint of removing heat from the fluorescent layer 122 that generates heat by irradiation with excitation light and suppressing the temperature rise of the fluorescent layer 122. Examples of the reflective substrate 121 include an aluminum substrate, an alumina substrate having high reflectivity, and a metal substrate having a highly reflective coating.

The fluorescent layer 122 is an aspect of a fluorescence source that receives excitation light and emits fluorescence. The fluorescence source may be one containing a phosphor capable of generating fluorescence. The fluorescence source may be composed of the fluorescent substance itself that emits fluorescence, or may contain other components such as a binder. Further, the shape of the fluorescence source is not limited, and may have, for example, the shape of a predetermined object itself. Further, the form of the fluorescence source may be a film or a layer arranged on the surface of the object.

The fluorescent layer 122 is composed of a fluorescent substance and a binder that binds the fluorescent substance. The thickness of the fluorescent layer 122 can be appropriately determined according to the application of the light emitting device 10 and the desired capacity.

The color of the fluorescence emitted by the phosphor can be appropriately determined according to the type of excitation light and the application of the light emitting device, and the color of the fluorescence is, for example, a color other than white light such as blue, green, and red. May be good.

The phosphor may be one kind or more. For example, the fluorescence source may include two or more types of phosphors that emit different colors. For example, the fluorescence source may include two types of phosphors that convert the excitation light of near-ultraviolet light into yellow light and blue light. Such a fluorescence source can generate pseudo-white fluorescence in which the fluorescence of yellow light and blue light is mixed.

The phosphor may be an organic compound or an inorganic compound as long as it is a component that generates fluorescence. When the laser light is used as the excitation light, the temperature of the fluorescence source tends to rise because the laser power density of the laser light is generally sufficiently high. In this case, the phosphor is preferably an inorganic phosphor from the viewpoint of having high heat resistance. Examples of inorganic phosphors include oxynitride-based phosphors and nitride-based phosphors.

The phosphor can be appropriately selected according to the type of excitation light and the desired color of the emitted fluorescence. For example, when the excitation light is near-ultraviolet light, examples of the fluorescent substance that converts the excitation light into red light include CaAlSiN ₃ : Eu ²⁺ . Examples of the fluorescent substance that converts the excitation light into yellow light include Ca-α-SiAlON: Eu ²⁺ and Y ₃ Al ₅ O ₁₂ : Ce ³⁺ (YAG: Ce). Examples of the fluorescent substance that converts the excitation light into green light include β-SiAlON: Eu ²⁺ and Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ (LuAG: Ce). Examples of fluorescent substances that convert the excitation light into blue light include (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ C ₁₂ : Eu, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , and (Sr, Ba). ) ₃ MgSi ₂ O ₈ : Eu ²⁺ , is included.

The form of the phosphor in the fluorescence source is not limited. In the fluorescence source, the phosphor may be formed into particles, may be fine particles dispersed in a binder, or may be a liquid.

Binder is a material that binds fluorescent substances to form a phosphor. If the fluorescence source can be composed only of the phosphor, no binder is required. The binder can be appropriately determined according to the binding property to the phosphor, and may be an organic compound or an inorganic compound.

The binder preferably has a high thermal conductivity from the viewpoint of enhancing the heat dissipation of the fluorescent layer 122. Further, the binder preferably has sufficiently high heat resistance from the viewpoint of enhancing the thermal stability of the fluorescent layer 122. From this point of view, the binder is preferably an inorganic binder. Examples of inorganic binders include aluminum compounds, examples of such aluminum compounds include alumina and boehmite.

Like the phosphor, the binder is not limited in its form in the fluorescent source. The binder may be in a continuous phase or in a state of particles bound to the particles of the phosphor in the fluorescence source. Further, the binder may further contain a component other than the aluminum compound as a sub-component within a range in which the desired effect such as high thermal conductivity as described above can be obtained.

Further, the fluorescence source may further contain components other than the binder as long as the desired effect can be obtained. For example, the fluorescence source may further contain a little dopant added to adjust the color of the resulting fluorescence.

In the present embodiment, the fluorescent layer 122 is composed of particles of an inorganic phosphor and particles of an inorganic binder that binds the particles of the inorganic phosphor. Preferred examples of the fluorescent layer 122, YAG: Ce (particles of the fluorescent-doped cerium as a dopant yttrium aluminum garnet material, for _{_{_{example, Y 3 Al 5 O 12:}}} Ce 3+) and alumina particles as binder particle A layer composed of and is included. The volume-based median diameter (D50) of YAG: Ce is, for example, 25 μm. The mixing ratio of YAG: Ce and binder particles is 6: 4 by volume. As described above, the fluorescent layer 122 may be composed of an inorganic binder and an inorganic phosphor bound to the binder.

Further, the inorganic phosphor in the fluorescent layer 122 may be a mixture of YAG: Ce having a D50 of 25 μm and YAG: Ce having a D50 of 5 μm. In the fluorescent layer 122 composed of such an inorganic phosphor, the mixing ratios of YAG: Ce having a D50 of 25 μm, YAG: Ce having a D50 of 5 μm, and binder particles are in this order and in a volume ratio of 5: 3. : 2.

The fluorescent layer 122 can be produced by a known method. For example, a composition of a phosphor and a binder is applied to the surface of a reflective substrate 121 by a printing method, and the coating film of the composition is dried. Further, it can be produced by firing if necessary.

(Light receiving element)
The light receiving element 13 is an element that receives a part of the fluorescence emitted by the fluorescent layer 122. The light receiving element 13 receives light so that at least the phase of the received light can be detected. Examples of the light receiving element 13 include an optical phase detector such as an interferometer.

(Adjuster)
The adjusting device 14 includes a processor, and includes a phase detection unit 141 and a control unit 142 as a functional configuration.

The phase detection unit 141 detects the phase of the fluorescence intensity received by the light receiving element 13. The phase of fluorescence intensity is the phase of fluorescence intensity that fluctuates periodically. The waveform drawn by the periodic fluctuation of the fluorescence intensity is not limited, and may be, for example, a sinusoidal curve or a shape obtained by repeating other shapes. Further, the waveform may have a shape obtained by regularly repeating a predetermined shape, or may have an irregular shape.

Fluorescence intensity represents the intensity of fluorescence. Fluorescence intensity can be expressed in any unit, and examples of fluorescence intensity units include light energy per unit area, brightness, and any unit represented by these relative values. Is done. Hereinafter, the "intensity" of fluorescence is also referred to as "emission intensity".

The control unit 142 adjusts the intensity of the excitation light in the fluorescence layer 122 per unit area according to the phase of the detected fluorescence intensity. More specifically, when the phase of the fluorescence intensity is the same as the phase of the excitation light intensity, the control unit 142 increases the intensity of the excitation light in the fluorescence layer 122 per unit area. When the phase of the fluorescence intensity is opposite to the phase of the excitation light intensity, the intensity of the excitation light in the fluorescence layer 122 per unit area is lowered.

Here, the phase of the intensity of the excitation light is the phase in the periodic fluctuation of the intensity of the excitation light. The periodic change in the intensity of the excitation light is due to, for example, the output of the excitation light source 11 fluctuating periodically and finely. For example, the period in the periodic fluctuation of the output of the excitation light source 11 is 60 Hz to 60 kHz. The period can be appropriately determined from the above range, for example, depending on the use of the light source device having the light emitting device 10. Further, the amplitude of the periodic fluctuation of the output of the excitation light source 11 is ± 5 to 10% of the average value. If the amplitude is too small, the change in fluorescence is too small, and the phase of the intensity of the excitation light may not appear sufficiently. If the amplitude is too large, it means that the fluorescence layer 122 is irradiated with excitation light having an intensity excessive with respect to the emission intensity of the fluorescence in the fluorescence layer 122. Therefore, if the amplitude is too large, the deterioration of the fluorescent layer 122 may be accelerated, and the reliability of the light emitting device 10 may be lowered. The intensity of the excitation light is not limited in the range representing the intensity of the excitation light, and examples thereof include the energy of the excitation light per unit area and the brightness. In the following embodiments, the "intensity" of the excitation light is also referred to as "laser power".

There are various methods for adjusting the intensity of the excitation light in the fluorescent layer 122 per unit area. In the present embodiment, the adjusting device 14 increases or decreases the representative value of the output of the excitation light source 11 according to the relationship between the phase of the fluorescence intensity and the phase of the excitation light intensity. The representative value of the output is the output value of the excitation light source 11 in which the excitation light emitted from the excitation light source 11 is set to have the desired intensity. The representative value may be the median value in the periodic and minute fluctuations in the output of the excitation light source 11 described above, or may be the average value of the output values of the excitation light source 11.

(Other configurations)
The light emitting device 10 may further have a configuration other than the above-described configuration as long as the effect of the present embodiment can be obtained. For example, the light emitting device 10 may further have a cooling unit (heat sink) (not shown) arranged so as to be in contact with the fluorescence generator 12. The heat sink is in contact with the reflective substrate 121 and cools the reflective substrate 121 and the fluorescent layer 122 as needed. It is preferable that the light emitting device 10 further has the cooling unit from the viewpoint of suppressing thermal deterioration of the fluorescent layer 122.

Further, the light emitting device 10 may further have a temperature sensor (not shown). The temperature sensor detects the temperature of the portion of the fluorescent layer 122 that is irradiated with the excitation light. The temperature sensor is a device that detects the temperature in a non-contact manner, and is, for example, an infrared temperature sensor.

(Relationship between excitation light intensity and fluorescence emission intensity)
Next, the relationship between the intensity of the excitation light and the emission intensity of fluorescence will be described. FIG. 2 is a diagram showing an example of the relationship between the laser power density of the laser beam and the emission intensity of the fluorescence in the light emitting device 10. FIG. 3 is a diagram showing an example of the relationship between the laser power density of the laser beam in the light emitting device 10 and the temperature of the fluorescent layer 122. The laser power density is, for example, an aspect of the intensity per unit area of excitation light on the surface of the fluorescent layer 122. Further, in the present embodiment, the unit of the emission intensity of fluorescence is "au" (arbitrary unit). As for the emission intensity of fluorescence, the emission intensity (for example, brightness) of fluorescence when not irradiated with excitation light is set to "0", and the phase of fluorescence intensity is twice the phase of excitation light intensity even when excited light is irradiated. It is represented by a relative value when the emission intensity (for example, brightness) of the fluorescence at that time is "1".

Excitation light such as a blue laser is emitted from the excitation light source 11. When the excitation light is incident on the fluorescence layer 122, as shown in FIG. 2, as the laser power density of the excitation light increases, the emission intensity of fluorescence in the fluorescence layer 122 increases. At the beginning of irradiation with the excitation light, the emission intensity increases almost linearly with the increase in the laser power density. The region in which the emission intensity of fluorescence exhibits such behavior (the region represented by "A" in FIGS. 2 and 3) is also referred to as an "emission intensity increasing region". In the emission intensity increasing region, as shown in FIG. 3, the temperature of the fluorescent layer 122 also increases as the laser power density increases.

When the laser power density is further increased from the emission intensity increase region, the emission intensity of fluorescence increases to the maximum value as shown in FIG. 2, and starts to decrease after the maximum value. As described above, the emission intensity of fluorescence reaches a maximum value at a certain point with respect to an increase in laser power density, and then decreases. A region in which the emission intensity of fluorescence behaves in this way with a maximum value in between (for example, a range in which the emission intensity of fluorescence is 90% or more of the above maximum value (luminance saturation point), etc. The region represented by "" is also referred to as a "peak intensity region". Even in the peak intensity region, as shown in FIG. 3, the temperature of the fluorescent layer 122 increases as the laser power density increases.

When the laser power density is further increased from the peak intensity region, the emission intensity of fluorescence decreases as shown in FIG. In this way, after the brightness is saturated, the emission intensity of fluorescence decreases. The region in which the emission intensity of fluorescence behaves in this way (the region represented by "C" in FIGS. 2 and 3) is also referred to as a "emission intensity reduction region". Even in the emission intensity decreasing region, as shown in FIG. 3, the temperature of the fluorescent layer 122 further increases as the laser power density increases.

(Example of controlling the intensity of excitation light)
Next, control of the intensity of the excitation light will be described. When the excitation light is a laser, the intensity of the excitation light fluctuates periodically. Here, from the viewpoint of suppressing the flicker of the excitation light, it is preferable that the frequency of the excitation light is high. From this point of view, the frequency of the excitation light may be, for example, 60 Hz or higher.

(When the periodic fluctuation of the excitation light intensity is a sinusoidal curve)
<Emission intensity increase region>
FIG. 4 is a diagram showing an example of the behavior of the laser power of the excitation light and the emission intensity of fluorescence in the emission intensity increasing region (A in FIGS. 2 and 3) in the light emitting device 10. The output conditions of the excitation light and the fluorescence state under the output conditions are as follows, for example. The following "θ" is represented by the product of "2π", "f" (frequency [Hz]), and "t" (time [second]).
Laser power of excitation light: 3.5W on average
Shape of periodic fluctuation of laser power of excitation light: sinusoidal curve (sinθ)
Amplitude in periodic fluctuation of laser power of excitation light: 0.5W
Fluorescence emission intensity: Average 0.927 (au)
Shape of periodic fluctuation of fluorescence emission intensity: sinusoidal curve (sinθ)

In the emission intensity increase region, the shape of the periodic fluctuation in the intensity of the excitation light and the intensity of fluorescence are both represented by sinθ. The control unit 142 compares the phase of the fluorescence intensity detected by the phase detection unit 141 with the phase of the excitation light output from the excitation light source 11. When the intensity of fluorescence and the intensity of excitation light are in phase, it can be determined that the fluorescence emitted from the fluorescence layer 122 has not reached luminance saturation. In the above case, the control unit 142 increases the output of the excitation light source 11.

<Peak intensity region>
FIG. 5 is a diagram showing an example of the behavior of the power of excitation light and the emission intensity of fluorescence in the peak intensity region (B in FIGS. 2 and 3) in the light emitting device 10. The output conditions of the excitation light and the fluorescence state under the output conditions are as follows, for example.
Laser power of excitation light: 4.1 W on average
Shape of periodic fluctuation of excitation light intensity: sinusoidal curve (sinθ)
Fluorescence emission intensity: Average 0.984 (au)
Shape of periodic variation in fluorescence intensity: sinusoidal curve (cos2θ)

At the maximum value (maximum value) of the emission intensity in the peak intensity region, the frequency in the periodic fluctuation of the fluorescence intensity is twice the frequency in the periodic fluctuation of the excitation light intensity. Therefore, when the periodic fluctuation of the intensity of the excitation light is represented by sinθ, the periodic fluctuation of the fluorescence intensity in the peak intensity region is represented by cos2θ. At this time, it can be determined that the fluorescence emitted from the fluorescence layer 122 has substantially reached the luminance saturation. In the above case, the control unit 142 does not change the output of the excitation light source 11.

<Emission intensity reduction region>
FIG. 6 is a diagram showing an example of the behavior of the power of the excitation light and the emission intensity of fluorescence in the emission intensity reduction region (C in FIGS. 2 and 3) in the light emitting device 10. The output conditions of the excitation light and the fluorescence state under the output conditions are as follows, for example.
Laser power of excitation light: 4.6W on average
Shape of periodic fluctuation of excitation light intensity: sinusoidal curve (sinθ)
Fluorescence emission intensity: 0.911 (au) on average
Shape of periodic fluctuation of fluorescence intensity: sinusoidal curve (sin (θ + π))

In the emission intensity decrease region, the excitation light and the fluorescence both have the same period, but the increase / decrease in the periodic fluctuation of the fluorescence intensity is the opposite of the increase / decrease in the periodic fluctuation of the exciton intensity. As described above, in the emission intensity decreasing region, the phase in the periodic fluctuation of the fluorescence intensity is the opposite of the phase of the periodic fluctuation in the intensity of the excitation light. Therefore, when the periodic fluctuation of the intensity of the excitation light is represented by sin θ, the periodic fluctuation of the fluorescence intensity in the emission intensity decreasing region is represented by sin (θ + π). In this case, it can be determined that the fluorescence emitted from the fluorescence layer 122 has excessive luminance saturation. In the above case, the control unit 142 makes the output of the excitation light source 11 smaller.

The amplitude of the fluorescence emission intensity on the increasing side of the periodic fluctuation includes a portion smaller than the amplitude on the decreasing side of the periodic fluctuation. This is because the emission intensity of fluorescence has peaked at a predetermined value due to luminance saturation.

(When the waveform of the periodic fluctuation of the intensity of the excitation light is a triangular wave)
Next, the behavior of the intensity of the excitation light and the intensity of the fluorescence will be described by taking as an example the case where the waveform in the periodic fluctuation of the intensity of the excitation light is a triangular wave.

FIG. 7 is a diagram showing another example of the behavior of the laser power of the excitation light and the emission intensity of the fluorescence in the emission intensity increasing region in the light emitting device 10. The output conditions of the excitation light in the emission intensity increasing region are as follows, for example.
Amplitude in periodic fluctuation of laser power of excitation light: 0.5W
Laser power of excitation light: 3.5W on average

Even if the waveform in the periodic fluctuation of the laser power of the excitation light is a triangular wave, the emission intensity of fluorescence is periodically in the same phase as the excitation light in the emission intensity increase region, as in the case where the waveform is a sinusoidal curve. It is fluctuating. Therefore, also in this case, the control unit 142 further increases the output of the excitation light source 11 in the above case.

FIG. 8 is a diagram showing another example of the behavior of the laser power of the excitation light and the emission intensity of the fluorescence in the peak intensity region in the light emitting device 10. The laser power of the excitation light in the peak intensity region is 4.1 W on average. Even if the waveform in the periodic fluctuation of the laser power of the excitation light is a triangular wave, in the peak intensity region, the frequency in the periodic fluctuation of the fluorescence intensity is the intensity of the excitation light, as in the case where the waveform is a sinusoidal curve. It is twice the frequency in periodic fluctuations. Therefore, also in this case, the control unit 142 does not fluctuate the output of the excitation light source 11.

FIG. 9 is a diagram showing another example of the behavior of the laser power of the excitation light and the emission intensity of the fluorescence in the emission intensity reduction region in the light emitting device 10. The laser power of the excitation light in the emission intensity reduction region is 4.6 W on average. Even if the waveform in the periodic fluctuation of the laser power of the excitation light is a triangular wave, the phase in the periodic fluctuation of the fluorescence intensity is the intensity of the excitation light in the emission intensity reduction region, as in the case where the waveform is a sinusoidal curve. It is the opposite of the phase in the periodic fluctuation of. In this case as well, the control unit 142 makes the output of the excitation light source 11 smaller.

When the waveform of the periodic fluctuation of the laser power of the excitation light is a triangular wave, the waveform of the periodic fluctuation of the fluorescence intensity becomes a more complicated shape than when the waveform of the excitation light is a sine curve. However, even in this case, the state of fluorescence is substantially the same as when the waveform of the periodic fluctuation of the excitation light is a sinusoidal curve. From the viewpoint of more easily analyzing the optimum waveform in the periodic fluctuation of the emission intensity of fluorescence, the waveform in the periodic fluctuation of the intensity of the excitation light is preferably a sinusoidal curve as compared with the triangular wave.

(Specific operation example in this embodiment)
The control unit 142 outputs the excitation light from the excitation light source 11 at a predetermined output. The intensity of the output excitation light fluctuates periodically. The excitation light reaches the fluorescence layer 122, excites the phosphor, and generates fluorescence. Since the intensity of the excitation light irradiated to the phosphor fluctuates periodically, the phosphor excited by the excitation light also generates fluorescence whose emission intensity fluctuates periodically. The generated fluorescence is generated in all directions, but the fluorescence toward the reflective substrate 121 is reflected by the reflective substrate 121. Therefore, the fluorescence is emitted upward (on the excitation light source 11 side in the drawing) from the surface of the reflection substrate 121.

The light receiving element 13 receives the fluorescence emitted obliquely upward among the fluorescence emitted upward from the fluorescent layer 122.

The phase detection unit 141 detects the phase in the periodic fluctuation of the emission intensity of the fluorescence detected by the light receiving element 13. The phase detection by the phase detection unit 141 may be performed continuously, or may be performed intermittently, for example, at predetermined intervals.

The control unit 142 refers to the phase in the periodic fluctuation of the emission intensity of fluorescence detected by the phase detection unit 141, and compares it with the phase in the periodic fluctuation of the laser power of the excitation light output from the excitation light source 11.

When the phase of fluorescence is the same as the phase of the excitation light with respect to the periodic fluctuation in the emission intensity or the laser power, it can be determined that the emission intensity of fluorescence is located in the emission intensity increase region. The output of the excitation light source 11 is further increased. As a result, the laser power density of the excitation light in the fluorescence layer 122 becomes higher, and the emission intensity of the fluorescence generated in the fluorescence layer 122 further increases.

When the fluorescence phase is opposite to the excitation light phase with respect to the periodic fluctuation in the emission intensity or the laser power, it can be determined that the fluorescence emission intensity is located in the emission intensity reduction region. Therefore, the control unit 142 Further reduces the output of the excitation light source 11. As a result, the laser power density of the excitation light in the fluorescent layer 122 becomes smaller. Since the phosphor in the fluorescent layer 122 is an inorganic phosphor, it has excellent heat resistance, and therefore the emission intensity of fluorescence changes reversibly. That is, in the emission intensity decrease region, when the output of the excitation light source 11 is reduced, the emission intensity of the fluorescence generated in the fluorescence layer 122 increases toward the maximum value of the emission intensity and then decreases. Therefore, the emission intensity of fluorescence is removed from the emission intensity reduction region.

Regarding the periodic fluctuation in the emission intensity or the laser power, when the fluorescence frequency is twice the frequency of the excitation light, it can be determined that the emission intensity of the fluorescence is located in the peak intensity region. , Maintain the output of the excitation light source 11. As a result, the laser power density of the excitation light in the fluorescence layer 122 is also maintained, and fluorescence is generated from the fluorescence layer 122 at a substantially maximum emission intensity.

(Action effect)
By comparing the phases of the cyclically fluctuating excitation light intensity (laser power) and the fluorescence intensity (emission intensity), it is determined whether or not the fluorescence is before luminance saturation. That is, if the phases of the excitation light and the fluorescence are the same, the fluorescence has not reached the brightness saturation. Therefore, by increasing the laser power density of the excitation light in the fluorescence layer 122, the emission intensity of the fluorescence is further increased toward the maximum value. It is possible to increase.

On the other hand, if the laser power of the excitation light and the emission intensity of the fluorescence are opposite in phase, the fluorescence is in a state of excessive brightness saturation, and the laser power density of the excitation light in the fluorescence layer 122 is lowered. Thereby, it is possible to eliminate the state of excessive brightness saturation in fluorescence, and it is possible to increase the emission intensity of fluorescence toward its maximum value.

Further, if the phase of fluorescence is twice the phase of the excitation light, the fluorescence is just before brightness saturation and has a substantially maximum emission intensity, so that the laser power density of the excitation light in the fluorescence layer 122 is maintained. By doing so, fluorescence can be continued to be generated at substantially the maximum emission intensity.

Therefore, in the present embodiment, it is possible to realize the generation of fluorescence at the optimum emission intensity (for example, the maximum value in the emission intensity) without acquiring the configuration of the fluorescence layer 122 and its environmental information in advance. This effect is exhibited regardless of the presence or absence of individual differences due to the fluorescent layer 122 such as the structure or thickness of the fluorescent layer 122.

Further, in the present embodiment, even when the temperature of the environment of the fluorescent layer 122 changes depending on the season such as summer or winter, the above effect of realizing the optimum emission intensity according to the environment can be obtained. ..

Further, in the present embodiment, since the intensity of the excitation light in the fluorescent layer 122 per unit area is adjusted so that the fluorescence at the maximum value of the emission intensity is generated, the portion of the fluorescent layer 122 to be irradiated with the excitation light. The temperature tends to rise. On the other hand, in the present embodiment, the fluorescence generator 12 is composed of an inorganic material (inorganic reflective base material, inorganic binder and inorganic fluorescent substance). Therefore, in the present embodiment, the possibility that the portion of the fluorescent layer 122 irradiated with the excitation light is burnt out is sufficiently low, and the heat resistance and reliability can be sufficiently improved.

[Embodiment 2]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

(Configuration of light emitting device)
FIG. 10 is a diagram schematically showing a configuration of a light emitting device according to a second embodiment of the present invention. As shown in FIG. 10, the light emitting device 20 includes an excitation light source 11, a fluorescence generator 12, a light receiving element 13, an adjusting device 24, and a varifocal lens 25. The excitation light source 11, the fluorescence generator 12, and the light receiving element 13 have the same configurations as those in the light emitting device 10. The varifocal lens 25 is an aspect of a varifocal device for changing the focal length of the excitation light applied to the fluorescent layer 122.

The adjusting device 24 includes a phase detection unit 141 and a control unit 242. Phase detector 141
Is configured in the same manner as the phase detection unit 141 in the light emitting device 10. Similar to the control unit 142, the control unit 242 refers to and compares the phase of the emission intensity of fluorescence detected by the phase detection unit 141 and the phase of the laser power of the excitation light output by the excitation light source 11, respectively. Has a function. Further, the control unit 242 further has a function of controlling the varifocal lens 25 according to the relationship between the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light.

The variable focus lens 25 is a lens that changes the focal length of passing light. The varifocal lens 25 is arranged in the optical path of the excitation light between the excitation light source 11 and the fluorescence generator 12 so that the excitation light passes through the optical system. The excitation light output from the excitation light source 11 reaches the fluorescence layer 122 through the varifocal lens 25. The light emitting device 20 is configured so that a signal from the control unit 242 is input to the variable focus lens 25.

(Specific operation example in this embodiment)
In the present embodiment, the adjusting device 24 changes the focal length of the excitation light by the variable focus lens 25 according to the relationship between the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light.

When the focal length of the excitation light is changed, the position of the center of the portion (laser spot) irradiated with the excitation light in the fluorescent layer 122 does not move, and the size of the laser spot changes. When the focal length is equal to the distance from the varifocal lens 25 to the fluorescence layer 122 in the optical path of the excitation light, the size of the laser spot is minimized. The larger the difference between the focal length and the distance from the variable focal length lens 25 to the fluorescent layer 122 in the optical path of the excitation light, the larger the size of the laser spot.

When the output of the excitation light source 11 is constant, the smaller the size of the laser spot (for example, [mm2]), the larger the laser power density (for example, [W / mm2]) in the fluorescent layer 122. The larger the size of the laser spot, the smaller the laser power density in the fluorescent layer 122.

Therefore, in the present embodiment, when the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are the same, the control unit 242 focuses the focal length so that the size of the laser spot becomes smaller. Change to the variable lens 25. When the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are opposite, the control unit 242 causes the focal length to be changed to the varifocal lens 25 so that the size of the laser spot becomes larger. When the frequency of the emission intensity of fluorescence is twice the frequency of the laser power of the excitation light, the control unit 242 causes the varifocal lens 25 to maintain the focal length so as to maintain the size of the laser spot.

(Action effect)
In the light emitting device 20, the output of the excitation light source 11 can be fixed to adjust the laser power density of the excitation light in the fluorescence layer 122. Therefore, the laser power density can be adjusted without changing the amplitude of the excitation light itself.

Further, it is possible to adjust the laser power density of the excitation light according to the environment of the fluorescent layer 122. For example, the fluorescent layer 122 tends to get hot in summer, which is a hotter environment. Therefore, the laser spot can be further expanded, and the fluorescence layer 122 can be irradiated with the excitation light so that the laser spot has the maximum emission intensity of fluorescence, for example. On the other hand, in winter, which is a lower temperature environment, the fluorescent layer 122 tends to become cold. The laser spot can be narrowed and the fluorescence layer 122 can be irradiated with the excitation light.

[Embodiment 3]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

(Configuration of light emitting device)
FIG. 11 is a diagram schematically showing a configuration of a light emitting device according to a third embodiment of the present invention. FIG. 12 is a perspective view schematically showing the configuration of a main part in the light emitting device according to the third embodiment of the present invention. As shown in FIG. 11, the light emitting device 30 includes an excitation light source 11, a fluorescence generator 12, a light receiving element 13, an adjusting device 34, and a rotating device 35. The excitation light source 11, the fluorescence generator 12, and the light receiving element 13 have the same configurations as those in the light emitting device 10. The rotating device 35 is an aspect of an incident angle changing device for changing the incident angle of the excitation light on the fluorescent layer 122.

The adjusting device 34 includes a phase detection unit 141 and a control unit 342. The phase detection unit 141 is configured in the same manner as the phase detection unit 141 in the light emitting device 10. Similar to the control unit 142, the control unit 342 compares the phase of the fluorescence emission intensity detected by the phase detection unit 141 with the phase of the laser power of the excitation light output from the excitation light source 11, respectively. Has a function. Further, the control unit 342 further has a function of controlling the rotating device 35 according to the relationship between the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light.

As shown in FIGS. 11 and 12, the rotating device 35 has a container 351 having a wall portion rising from the bottom portion and its peripheral edge, a shaft 352 protruding from the wall portion, and a motor 353. The bottom of the container 351 is rectangular when viewed in a plan view. The walls stand up from each side of the bottom. The shaft 352 extends from the outer surface of each of the pair of wall portions facing each other in a direction orthogonal to the outer surface. The motor 353 is appropriately connected to the shaft 352 by a pulley, a belt, or the like (not shown) so as to serve as a drive source for rotating the shaft 352.

The fluorescence generator 12 is housed in the container 351. The rotating device 35 is arranged so that the axis 352 is orthogonal to the excitation light source 11 and the light receiving element 13 with respect to the plane including both the optical axis of the excitation light source 11 and the optical axis of the light receiving element 13. .. The fluorescence generator 12 is housed in the container 351 at a position where the intersection of the optical axis of the excitation light source 11 and the fluorescence layer 122 overlaps the center of the shaft 352 when viewed along the shaft 352. Further, the light emitting device 30 is configured so that a signal from the control unit 342 is input to the motor 353.

Note that in FIG. 11, the normal line of the fluorescent layer 122 on the plane including both the optical axis of the excitation light source 11 and the optical axis of the light receiving element 13 is shown by a dashed line. The angle formed by the normal and the optical axis of the excitation light source 11 is the angle of incidence of the excitation light on the fluorescent layer 122, and in FIG. 11, the angle is represented by θ.

(Specific operation example in this embodiment)
In the present embodiment, the adjusting device 34 increases or decreases the angle of incidence of the excitation light on the fluorescence layer 122 according to the relationship between the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light. More specifically, the adjusting device 34 increases or decreases the angle of incidence of the excitation light on the fluorescent layer 122 by rotating the fluorescent layer 122 by the rotating device 35 according to the above relationship.

As described above, when the output of the excitation light source 11 is constant, the laser power density in the fluorescence layer 122 increases as the size of the laser spot of the excitation light in the fluorescence layer 122 decreases, and decreases as the size increases. .. The size of the laser spot of the excitation light in the fluorescent layer 122 is the smallest when the incident angle θ is 0, and becomes larger as the absolute value of the incident angle θ becomes larger.

Therefore, in the present embodiment, when the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are the same, the control unit 342 sets the incident angle θ in order to reduce the size of the laser spot. The rotating device 35 is operated so as to be smaller. When the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are opposite, the control unit 342 rotates the device so that the incident angle θ becomes larger in order to increase the size of the laser spot. Operate 35. When the phase of fluorescence is twice the phase of the excitation light, the control unit 342 causes the rotating device 35 to maintain the incident angle θ in this case so as to maintain the size of the laser spot.

(Action effect)
The light emitting device 30 has the same effect as the light emitting device 20. In addition, the light emitting device 30 can change the incident angle of the excitation light with an inexpensive and simple configuration.

[Embodiment 4]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

(Configuration of light emitting device)
FIG. 13 is a diagram schematically showing a configuration of a light emitting device according to a fourth embodiment of the present invention. As shown in FIG. 13, the light emitting device 40 includes an excitation light source 11, a fluorescence generator 12, a light receiving element 13, an adjusting device 44, and a Peltier element 45. The excitation light source 11, the fluorescence generator 12, and the light receiving element 13 have the same configurations as those in the light emitting device 10. The Peltier element 45 is an aspect of an environment changing device capable of changing the environment surrounding the fluorescent layer 122.

The adjusting device 44 includes a phase detection unit 141 and a control unit 442. The phase detection unit 141 is configured in the same manner as the phase detection unit 141 in the light emitting device 10. Similar to the control unit 142, the control unit 442 has a function of referring to and comparing the phase of the fluorescence detected by the phase detection unit 141 and the phase of the excitation light output by the excitation light source 11, respectively. Further, the control unit 442 further has a function of changing the temperature environment of the fluorescent layer 122.

The Peltier element 45 supports the fluorescence generator 12. More specifically, the reflective substrate 121 is in contact with the Peltier element 45 and is arranged on the Peltier element 45, and the fluorescent layer 122 is arranged on the reflective substrate 121. The Peltier element 45 is an element whose temperature can be adjusted at a portion in contact with the reflective substrate 121. The temperature adjustable range of the Peltier element 45 is, for example, −20 to 120 ° C. Further, the light emitting device 40 is configured so that a signal from the control unit 442 is input to the Peltier element 45.

(Specific operation example in this embodiment)
As described above, when the phase of fluorescence is twice the phase of the excitation light, the emission intensity of fluorescence is maximized. Therefore, it is possible to obtain the laser power of the excitation light source at the maximum emission intensity of fluorescence by obtaining the output of the excitation light source when the phase of fluorescence is twice the phase of the excitation light.

In the present embodiment, the adjusting device 44 sets the desired temperature environment of the fluorescent layer 122 by operating the Peltier element 45. The output of the excitation light source is fluctuated by referring to the phase of fluorescence and the phase of excitation light at the set temperature. Then, the output of the excitation light source when the phase of fluorescence becomes twice the phase of the excitation light is obtained. The temperature environment of the fluorescence layer 122 is changed to another temperature by the Peltier element 45, and the output of the excitation light source when the phase of fluorescence becomes twice the phase of the excitation light is obtained as described above. As a result, in the light emitting device 40, the laser power of the excitation light source corresponding to the fluorescence of the emission intensity which becomes the maximum value is obtained for each temperature when the temperature environment of the fluorescent layer 122 is changed.

(Action effect)
In the light emitting device 40, the characteristics of the light emitting device for each environmental temperature can be easily evaluated.

[Embodiment 5]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

(Configuration of light source device)
FIG. 14 is a diagram for introducing the configuration of the light source device according to the fifth embodiment of the present invention. The light source device is a reflective laser headlight. The headlight is, for example, a vehicle headlight. FIG. 14 schematically shows a state in which the light source device is divided by a dividing surface along the optical axis direction thereof. As shown in FIG. 14, the light source device 100 includes a light emitting device and a reflector 120. The light emitting device has the same configuration as the configuration described above in the first embodiment. Reference numeral 110 in FIG. 14 is a line representing the divided surface.

The reflector 120 is, for example, a cover having an open end. The shape of the reflector 120 is such that its cross-sectional shape gradually expands in a parabolic shape toward the open end. The inner surface of the reflector 120 is a mirror. A hole penetrating the wall portion of the reflector 120 is formed in the central portion opposite to the open end of the reflector 120.

The excitation light source 11 is arranged outside the reflector 120. In FIG. 14, the excitation light source 11 is drawn so as to irradiate the excitation light B1 obliquely with respect to the central axis of the reflector 120, but the optical axis of the excitation light source 11 is on the same line as the central axis of the reflector 120. It is arranged at the position where. The excitation light source 11 outputs blue excitation light such as a blue laser as excitation light.

The fluorescence generator 52 is arranged on the axis of the reflector 120 with the fluorescence layer 122 facing the open end of the reflector 120. The fluorescence generator 52 has the same configuration as the fluorescence generator 12 in the light emitting device 10. The fluorescent layer 122 emits yellow fluorescence when irradiated with excitation light.

The light receiving element 13 is located outside the open end of the reflector 120 and at a position where it receives a part of the fluorescence emitted from the reflector 120 and a part of the excitation light.

The adjusting device 54 includes a phase detection unit 541 and a control unit 542. The phase detection unit 541 is configured to detect both the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light from the light received by the light receiving element 13. The control unit 542 is configured to control the output of the excitation light source 11 by referring to both the phase of the emission intensity of fluorescence detected by the phase detection unit 541 and the phase of the laser power of the excitation light. The adjusting device 54 may be arranged in the light receiving element 13, the excitation light source 11, or may be arranged independently of these.

As is clear from the above description, in the present embodiment, the reflector 120 constitutes an optical system that controls the optical paths of excitation light and fluorescence.

(Specific operation example in this embodiment)
The excitation light source 11 outputs the excitation light B1. The excitation light B1 reaches the fluorescence generator 52 through the holes of the reflector 120. The excitation light B2 and the fluorescence B3 are emitted from the fluorescence generator 52. The excitation light B2 is, for example, the excitation light surface-reflected by the fluorescent layer 122 and the excitation light diffused inside the fluorescent film and reflected by the reflector 120. Fluorescence B3 is, for example, fluorescence emitted by exciting a fluorescent substance by excitation light that has reached the fluorescence layer 122.

The excitation light B2 and the fluorescence B3 emitted from the fluorescence generator 52 are reflected by the reflector 120 to become white light mainly in a desired direction, for example, the axial direction of the reflector 120 as an optical axis, and are emitted from the reflector 120. ..

The light receiving element 13 receives the light emitted from the reflector 120. The emitted light is divided into an excitation light component and a fluorescence component by passing through an appropriate optical filter in the light receiving element 13, for example.

The phase detection unit 541 detects the phase of the laser power of the excitation light from the light received by the light receiving element 13, and also detects the phase of the emission intensity of fluorescence. The control unit 542 controls the output of the excitation light source 11 with reference to the phase information detected by the phase detection unit 541.

For example, when the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are the same, the control unit 542 increases the output of the excitation light source 11. As a result, the laser power density of the excitation light B1 in the fluorescence layer 122 is increased, and the emission intensity of fluorescence is increased.

When the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are opposite, the control unit 542 reduces the output of the excitation light source 11. As a result, the laser power density of the excitation light B1 in the fluorescence layer 122 decreases, and the emission intensity of fluorescence increases toward the maximum value of the emission intensity and then decreases.

When the frequency of the emission intensity of fluorescence is twice the frequency of the laser power of the excitation light, the control unit 542 maintains the output of the excitation light source 11 unchanged. As a result, the laser power density of the excitation light B1 in the fluorescence layer 122 is also maintained, and fluorescence with an intensity that substantially maximizes the emission intensity continues to be generated.

(Action effect)
The light source device 100 of the present embodiment can always generate the emitted light including the fluorescence of the intensity which becomes the maximum value of the emission intensity based on the phase of the intensity of the emitted light. Therefore, it is possible to easily realize light emission with a desired light emission intensity without depending on prior processing.

[Embodiment 6]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

(Configuration of light source device)
FIG. 15 is a diagram schematically showing a configuration of a light source device according to a sixth embodiment of the present invention. The light source device has a fluorescent wheel and is, for example, a light source device for a projector. As shown in FIG. 15, the light source device 200 includes a light emitting device, a wheel 210, a fluorescent layer 215, a motor 220, a dichroic mirror 230, and

lenses

240, 250, 260. The light emitting device has the same configuration as the light emitting device described above in the first embodiment.

The wheel 210 is, for example, a disk. A metal layer serving as a reflective substrate is formed on at least the peripheral portion of the wheel 210. The fluorescent layer 215 is formed on the above-mentioned metal layer at the peripheral edge of the wheel. The configuration of the fluorescent layer 215 is the same as that of the above-described embodiment. The motor 220 pivotally supports the center of the wheel 210 when viewed in a plan view, and is a drive device for rotationally driving the wheel 210.

The dichroic mirror 230 is a member that reflects excitation light incident at an incident angle of 45 ° and transmits excitation light incident at other incident angles and light of other wavelengths.

The excitation light source 11 is arranged at a position where the excitation light is emitted at an incident angle of 45 ° with respect to the dichroic mirror 230. The wheel 210 is arranged at a position where the excitation light reflected by the dichroic mirror 230 is applied to the fluorescent layer 215 from a direction perpendicular to the surface of the metal layer.

The lens 240 is arranged in the optical path of the excitation light between the excitation light source 11 and the dichroic mirror 230. The

lenses

250 and 260 are all arranged in the optical path of the excitation light between the dichroic mirror 230 and the wheel 210.

The light receiving element 13 is arranged at a position on the fluorescent layer 215 side away from the wheel 210 and at a position outside the optical path of the excitation light to the wheel 210 in an oblique direction with respect to the optical path. Further, the adjusting device 14 is configured in the same manner as the adjusting device 14 in the light emitting device 10 of the above-described embodiment.

In the present embodiment, the dichroic mirror 230 and the

lenses

240, 250, 260 constitute an optical system that controls the optical path of excitation light and fluorescence.

(Specific operation example in this embodiment)
The wheel 210 is rotated at high speed by the motor 220. The fluorescent layer 215 also moves at high speed on a circular orbit together with the wheel 210.

Excitation light B1 is output from the excitation light source 11. The excitation light B1 passes through the lens 240, reaches the dichroic mirror 230, and is reflected toward the wheel 210. The reflected excitation light B1 reaches the fluorescence layer 215 through the

lenses

250 and 260. The fluorescent substance in the fluorescent layer 215 is excited by the excitation light B1 and emits fluorescence. Part of the fluorescence is reflected on the surface of the metal layer on the back side of the fluorescence layer 215. Fluorescence is mainly emitted in a direction perpendicular to the surface of the metal layer.

The fluorescent B3 emitted from the fluorescent layer 215 mainly passes through the

lenses

260 and 250 and reaches the dichroic mirror 230. Since the dichroic mirror 230 is a member that reflects only the excitation light incident at 45 °, the fluorescence B3 passes through the dichroic mirror 230 and is used as a part of the light generated by the light source device 200.

The fluorescence emitted from the fluorescent layer 215 is also emitted in a direction oblique to the above-mentioned main emission direction. The light receiving element 13 receives the fluorescence emitted in such an oblique direction. The phase detection unit 141 detects the phase of the fluorescence emission intensity received by the light receiving element 13, and the control unit 142 detects the phase of the fluorescence emission intensity detected by the phase detection unit 141 and the excitation output from the excitation light source 11. The output of the excitation light source 11 is controlled with reference to the phase of the laser power of the light B1.

For example, when the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are the same, the control unit 142 increases the output of the excitation light source 11. As a result, the laser power density of the excitation light B1 in the fluorescence layer 215 is increased, and the emission intensity of fluorescence is increased.

When the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are opposite, the control unit 142 reduces the output of the excitation light source 11. As a result, the laser power density of the excitation light B1 in the fluorescence layer 215 decreases, and the emission intensity of fluorescence increases toward the maximum value of the emission intensity and then decreases.

When the frequency of the emission intensity of fluorescence is twice the frequency of the laser power of the excitation light, the control unit 142 maintains the output of the excitation light source 11 unchanged. As a result, the laser power density of the excitation light B1 in the fluorescence layer 215 is also maintained, and fluorescence with an intensity that substantially maximizes the emission intensity continues to be generated.

(Action effect)
In the light source device 200 of the present embodiment as well, similarly to the light source device 100 described above, it is possible to always generate the emitted light including the fluorescence of the intensity that becomes the maximum value of the emission intensity based on the phase of the intensity of the emitted light. Is. Therefore, it is possible to easily realize light emission with a desired light emission intensity without depending on prior processing.

[Modification example]
(First modification)
In any of the above embodiments, the fluorescence generator may further have a highly reflective film between the reflective substrate and the fluorescent layer from the viewpoint of increasing the emission intensity of fluorescence. Examples of materials for the highly reflective film include silver and titanium oxide. Examples of high-reflection films include anti-reflective multilayer films and dielectric mirrors. Alternatively, the fluorescence generator may further have a scattering layer that scatters incident light between the reflective substrate and the fluorescence layer.

(Second modification)
In any of the above embodiments, the fluorescent layer may have other structures as long as the effects of the above embodiments can be obtained. For example, the fluorescent layer may be formed by attaching a fluorescent film made of an inorganic material to a reflective substrate with an organic binder, grease, or a highly heat-resistant inorganic adhesive.

(Third modification example)
In any of the above embodiments, the adjusting device is such that the intensity of the excitation light in the phosphor per unit area is a value of a predetermined ratio with respect to the intensity of the excitation light that maximizes the emission intensity of fluorescence. , The intensity of the excitation light in the phosphor per unit area may be adjusted. In this case, the fact that the phase of the fluorescence intensity is the same as the phase of the excitation light intensity may be further added as a condition to be satisfied. Such adjustment of the intensity per unit area of the excitation light can be carried out by adopting an appropriately set threshold value.

For example, the regulator may further control the intensity of excitation light per unit area in the fluorescence layer based on a threshold value corresponding to the desired emission intensity of fluorescence. The threshold value may be the value of the emission intensity of fluorescence itself, the value of the intensity per unit area of the excitation light in the fluorescence layer, or the output value of the excitation light source corresponding to the emission intensity. You may.

When the threshold value is the emission intensity of fluorescence itself, the adjusting device may further include an emission intensity detection unit that detects the emission intensity of fluorescence received by the light receiving element. In this case, the adjusting device further refers to the emission intensity detected by the emission intensity detection unit in controlling the output of the excitation light source. Thereby, the intensity of the excitation light in the fluorescent layer per unit area can be controlled based on the above threshold value.

When the threshold value is another value corresponding to the emission intensity of fluorescence, for example, the output value of the excitation light source, the adjusting device estimates the output value of the excitation light source with reference to the detection result acquired by the adjusting device. You may. In this case, the adjusting device may control the intensity of the excitation light in the fluorescent layer per unit area based on the above threshold value by further referring to the obtained estimated value in the control of the output of the excitation light source. it can.

The threshold value can be set as appropriate. For example, the threshold value may be a value corresponding to an emission intensity less than the maximum value of the emission intensity of fluorescence, for example, an emission intensity of 80% of the maximum value. In this case, for example, if the condition that the emission intensity of fluorescence is 80% or less of the maximum value and the condition that the excitation light and the fluorescence are in phase are further set, the fluorescence in the emission intensity decrease region is further set. Can be prevented from occurring. Therefore, deterioration of the phosphor due to heat can be prevented, and as a result, fluorescence having a stable emission intensity for a long period of time can be generated. The thermal deterioration of the phosphor is, for example, a structural change or cracking of the phosphor, a decrease in the fluorescence output due to oxidation of the phosphor, or an increase in the fluorescence output due to the volatilization of impurities. Alternatively, setting the above conditions is advantageous from the viewpoint of stable use of a fluorescence source made of an organic material, which has relatively low heat resistance, for a long period of time.

The above-mentioned threshold value can be set based on the maximum value of the emission intensity of fluorescence or the value corresponding to the maximum value. The acquired value may be a measured value actually measured or an estimated value estimated based on the measurement result.

For example, the threshold value can be set (for example, 80% of the measured value) based on the measured value obtained by actually measuring the maximum value of the fluorescence emission intensity.

Alternatively, the threshold is the value of the intensity of the excitation light in the fluorescence layer per unit time when the frequency of the intensity of the fluorescence is twice the frequency of the intensity of the excitation light, or the output value of the excitation light source. May be good. In this case, the threshold value can be set, for example, by recording the measured value when the frequency of the fluorescence intensity is twice the frequency of the excitation light intensity.

Alternatively, the threshold value can be set by measuring the emission intensity of fluorescence at a plurality of points from the emission intensity increase region to immediately before the maximum value in the peak intensity region. For example, the measurement is performed at the above-mentioned multiple points, the increment of the emission intensity between the measurement points is calculated, and the maximum value of the emission intensity is estimated on condition that the calculated value of the increment is positive but sufficiently small. To do. The threshold value can be set based on such an estimated value.

Furthermore, if other values corresponding to the emission intensity (such as the output value of the excitation light source) are acquired at the above measurement points, it is possible to estimate other values corresponding to the estimated value of the maximum emission intensity. Is. Such other values can also be set as thresholds. According to the above method, the threshold value can be set without actually measuring the maximum value of the emission intensity of fluorescence, which is preferable from the viewpoint of preventing the phosphor from being deteriorated by heat by setting the threshold value. ..

Further, in the above method using the estimated value of the maximum value of the emission intensity of fluorescence, when the fluorescence source is constructed by using an organic compound relatively weak to heat, the deterioration due to heat of the fluorescence source and the resulting deterioration of the light emitting device It is preferable from the viewpoint of suppressing the decrease in reliability.

Further, the adjusting device may be further provided with a functional configuration for setting the threshold value and, after setting the threshold value, a functional configuration for prioritizing the control based on the threshold value in the control of the output of the excitation light source. .. By configuring the adjusting device in this way, it is possible to suitably control the intensity per unit area of the excitation light in the fluorescent layer based on the above-mentioned threshold value.

If the emission intensity of fluorescence is set on the condition that it is equal to or more than a predetermined ratio to the maximum value (for example, 80% or more of the maximum value), fluorescence in the peak intensity region can be constantly generated. It becomes. Control based on such a threshold value becomes even more effective from the viewpoint of generating fluorescence with higher luminous efficiency.

(Fourth modification)
In any of the above-described embodiments, the adjusting device may further include a light emitting intensity detecting unit that detects the light emitting intensity of the fluorescence received by the light receiving element. According to this configuration, it is possible to further refer to the detected value of the emission intensity of fluorescence in the above-mentioned setting of the threshold value or in the control by the control unit of the intensity per unit area of the excitation light in the fluorescence layer. As a result, the intensity of the excitation light in the fluorescent layer per unit area can be adjusted more precisely.

(Fifth variant)
In any of the above embodiments, the intensity of the excitation light in the fluorescent layer in one embodiment is adjusted per unit area, and the excitation in the fluorescent layer in the other embodiment is obtained within the range in which the effect of the embodiment can be obtained. Both may be performed with another adjustment of the intensity per unit area of light. For example, in each of the second to fourth embodiments, the output of the excitation light source in the first, fifth, and sixth embodiments may be further controlled. In this case, the controls to be executed a plurality of times may be executed simultaneously, alternately, or irregularly. Performing both control of the adjustment of the intensity per unit area of the excitation light in the fluorescent layer in the second to fourth embodiments and the adjustment in the first, fifth, and sixth embodiments is the emission intensity of the fluorescence emitted by the fluorescent layer. It is even more effective from the viewpoint of precisely controlling.

(Sixth variant)
In the third embodiment, the configuration for changing the incident angle of the excitation light with respect to the fluorescent layer 122 is not limited to the rotating device 35. For example, instead of the rotating device 35, the incident angle θ is changed by adopting a device that rotates the excitation light source 11 with the intersection of the optical axis of the excitation light source 11 and the fluorescence layer 122 as the center point of rotation. You may.

(7th variant)
In the fourth embodiment, the adjusting device may adjust the temperature of the fluorescent layer to generate fluorescence according to the temperature environment. According to this configuration, even when the light emitting device is used in a hot environment in summer, for example, it is possible to generate fluorescence in a low temperature environment corresponding to the environment in winter.

(Eighth variant)
In the sixth embodiment, as in the fifth embodiment, the light synthesized from the excitation light and the fluorescence may be adopted as the light emitted from the light source device. When such combined light is used as the emitted light, the adjusting device may further control the output of the excitation light source, for example, from the viewpoint of adjusting the color of the emitted light. For such further control, for example, refer to a table that stores information on the ratio of the emission intensity of excitation light to the emission intensity of fluorescence, which is required for the light to be synthesized when the control unit controls the output of the excitation light source. It can be carried out by determining the output of the excitation light source.

[Example of realization by software]
The control blocks of the adjusting

devices

14, 24, 34, 44, 54 (particularly, the

phase detection units

141, 541 and the

control units

142, 242, 342, 442, 542) are logic circuits formed in an integrated circuit (IC chip) or the like. It may be realized by (hardware) or by software.

In the latter case, the adjusting

devices

14, 24, 34, 44, 54 include a computer that executes a program instruction, which is software that realizes each function. This computer includes, for example, at least one processor (control device) and at least one computer-readable recording medium that stores the program. Then, in the computer, the processor reads the program from the recording medium and executes it, thereby achieving the object of the present invention.

As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, in addition to a “non-temporary tangible medium” such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (RandomAccessMemory) or the like for expanding the above program may be further provided.

Further, the program may be supplied to the computer via an arbitrary transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. It should be noted that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.

[Summary]
The light emitting device 10 according to the first aspect of the present invention includes an excitation light source 11 for irradiating excitation light, a fluorescence source (fluorescence layer 122) that emits fluorescence in response to excitation light from the excitation light source, and fluorescence emitted by the fluorescence source. The light receiving element 13 that receives a part of the light receiving element and the phase of the fluorescence intensity received by the light receiving element are detected, and the intensity of the excitation light in the fluorescence source per unit area is adjusted according to the detected fluorescence intensity phase. It has an adjusting device 14. Then, when the phase of the fluorescence intensity is the same as the phase of the excitation light intensity, the adjusting device increases the intensity of the excitation light per unit area in the fluorescence source, and the fluorescence intensity phase is the excitation light intensity. When the phase is opposite to that of, the intensity of the excitation light in the fluorescence source per unit area is lowered.

According to the above configuration, in a light emitting device that receives excitation light from an excitation light source by a fluorescence source and emits fluorescence, fluorescence can be emitted with a desired intensity without prior treatment.

In the light emitting device according to the second aspect of the present invention, in the above aspect 1, the adjusting device may increase or decrease the representative value of the output of the excitation light source according to the relationship between the phase of the fluorescence intensity and the phase of the excitation light intensity. ..

According to the above configuration, the intensity per unit area of the excitation light in the fluorescence source also increases or decreases due to the substantial increase or decrease in the output of the excitation light source, which is even more effective from the viewpoint of easily adjusting the emission intensity of fluorescence.

The light emitting device according to the third aspect of the present invention may further include a varifocal device (varifocal lens 25) capable of changing the focal length of the excitation light applied to the fluorescence source in the above aspect 1 or 2. The adjusting device may change the focal length of the excitation light by the focus variable device according to the relationship between the phase of the fluorescence intensity and the phase of the excitation light intensity.

According to the above configuration, it is possible to adjust the intensity per unit area of the excitation light in the fluorescence source without changing the output of the excitation light from the excitation light source, so that the amplitude of the intensity of the excitation light is not changed. , It becomes possible to adjust the intensity of the excitation light in the fluorescence source per unit area.

The light emitting device according to the fourth aspect of the present invention may further include an incident angle changing device capable of changing the incident angle of the excitation light to the fluorescence source in the above aspects 1 to 3, and the adjusting device may include the fluorescence intensity. The angle of incidence of the excitation light on the fluorescence source by the incident angle changing device may be increased or decreased depending on the relationship between the phase of the excitation light and the phase of the intensity of the excitation light.

According to the above configuration, it is possible to adjust the intensity per unit area of the excitation light in the fluorescence source without changing the amplitude of the intensity of the excitation light, as in the third aspect.

The light emitting device according to the fifth aspect of the present invention is a rotating device that rotates the fluorescence source around a rotation axis parallel to the direction in which the incident angle changing device intersects the optical axis of the excitation light in the above aspect 4. Often, the regulator increases or decreases the angle of incidence of the excitation light on the fluorescence source by rotating the fluorescence source with a rotating device according to the relationship between the phase of the fluorescence intensity and the phase of the excitation light intensity. You may.

Claims

An excitation light source for irradiating excitation light,
A fluorescence source that receives the excitation light from the excitation light source and emits fluorescence,
A light receiving element that receives a part of the fluorescence emitted by the fluorescence source, and
It has an adjusting device that detects the phase of the fluorescence intensity received by the light receiving element and adjusts the intensity of the excitation light in the fluorescence source per unit area according to the detected phase of the fluorescence intensity. And
When the phase of the intensity of the fluorescence is the same as the phase of the intensity of the excitation light, the adjusting device increases the intensity of the excitation light in the fluorescence source per unit area, and the phase of the intensity of the fluorescence. Is opposite to the phase of the intensity of the excitation light, the intensity of the excitation light in the fluorescence source per unit area is lowered.
Light emitting device.
The light emitting device according to claim 1, wherein the adjusting device increases or decreases the representative value of the output of the excitation light source according to the relationship between the phase of the intensity of fluorescence and the phase of the intensity of the excitation light.
Further having a focus variable device capable of changing the focal length of the excitation light applied to the fluorescence source,
The adjusting device changes the focal length of the excitation light by the focus variable device according to the relationship between the phase of the fluorescence intensity and the phase of the excitation light intensity.
The light emitting device according to claim 1 or 2.
It further has an incident angle changing device capable of changing the incident angle of the excitation light to the fluorescent source.
The adjusting device increases or decreases the angle of incidence of the excitation light on the fluorescence source by the incident angle changing device according to the relationship between the phase of the fluorescence intensity and the phase of the excitation light intensity. The light emitting device according to any one of 3 to 3.
The incident angle changing device is a rotating device that rotates the fluorescence source around a rotation axis parallel to the direction intersecting the optical axis of the excitation light.
The adjusting device rotates the fluorescence source by the rotating device according to the relationship between the phase of the intensity of the fluorescence and the phase of the intensity of the excitation light, whereby the excitation light is transferred to the fluorescence source. The light emitting device according to claim 4, wherein the incident angle is increased or decreased.
The light emitting device according to any one of claims 1 to 5, wherein the fluorescence source is composed of an inorganic binder and an inorganic phosphor bound to the binder.
The light emitting device according to any one of claims 1 to 6, further comprising an environment changing device capable of changing the environment surrounding the fluorescence source.
A light source device comprising the light emitting device according to any one of claims 1 to 7 and an optical system for controlling one or both optical paths of the excitation light and the fluorescence.