JP2023002847A - Light-emitting device and light source device - Google Patents

Abstract

To provide a light-emitting device which is configured to emit fluorescence when a fluorescence source receives excitation light from an excitation light source, and which is capable of emitting fluorescence of desired intensity without requiring a process in advance.SOLUTION: A light-emitting device (10) is provided, comprising an excitation light source (11), a fluorescent layer (122), a photosensitive element (13), and an adjustment unit (14). If an intensity phase of received fluorescence is the same as that of excitation light, the adjustment unit (14) increases intensity of the excitation light per unit area at the fluorescent layer (122), and reduces the intensity if otherwise.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light emitting device and a light source device.

2. Description of the Related Art Conventionally, image display devices such as projectors that display images by modulating light from a light source have 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 an LD (Laser Diode) and a fluorescent film that receives the excitation light emitted by the solid-state light source and emits fluorescence is used. . As for the device, a technique is known that can measure each emitted light emitted by the device by controlling the light sampling interval of the sensor unit (see, for example, Patent Document 1).

JP 2015-138045 A

In a device such as the one described above in which the fluorescent film receives excitation light and emits fluorescence, heat is generally generated in the fluorescent film according to the power of the excitation light. In addition, the luminous properties of the fluorescent film usually have temperature dependence. Therefore, the emission characteristics of the phosphor film vary depending on the temperature of the phosphor film. Therefore, it is difficult to use the above light source under the condition that the luminous efficiency is always maximized.

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 control the power of the excitation light can be considered, but this method has the following problems. For example, it is necessary to prepare a table of driving conditions of the solid-state light source with respect to the temperature of the fluorescent film in accordance with the accurate temperature characteristics and film thickness of the fluorescent film. However, the temperature of the fluorescent film generally increases nonlinearly with the increase in the intensity per unit area of the excitation light in the fluorescent film, and the temperature of the fluorescent film affects the intensity of fluorescence. Furthermore, the emission characteristics of the fluorescent film include individual differences in the fluorescent film. Therefore, it is difficult to analyze the peak emission intensity of fluorescence from the temperature of the fluorescent film.

An object of one embodiment of the present invention is to emit light with a desired emission intensity without prior treatment in a light-emitting device in which a fluorescence source emits fluorescence by receiving excitation light from an excitation light source.

In order to solve the above problems, a light-emitting device according to an aspect of the present invention includes an excitation light source for irradiating excitation light, a fluorescence source for emitting fluorescence upon receiving the excitation light from the excitation light source, and a light-receiving element for receiving part of the fluorescence emitted by a fluorescence source; detecting a phase of intensity of the fluorescence received by the light-receiving element; and an adjustment device for adjusting the intensity per unit area of light, the adjustment device adjusting 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 if the phase of the intensity of the fluorescence is opposite to the phase of the intensity of the excitation light, the intensity per unit area of the excitation light in the fluorescence source is decreased.

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

According to one embodiment of the present invention, in a light-emitting device in which a fluorescence source emits fluorescence by receiving excitation light from an excitation light source, fluorescence can be generated at a desired intensity without prior treatment.

1 is a diagram schematically showing the configuration of a light emitting device according to Embodiment 1 of the present invention; FIG. 2 is a diagram showing an example of the relationship between the laser power density of excitation light and the emission intensity of fluorescence in the light emitting device of FIG. 1. FIG. 2 is a diagram showing an example of the relationship between the laser power density of excitation light and the temperature of a fluorescent layer in the light emitting device of FIG. 1; FIG. 2 is a diagram showing an example of the behavior of the laser power of excitation light and the emission intensity of fluorescence in the emission intensity increasing region in the light emitting device of FIG. 1. FIG. 2 is a diagram showing an example of the behavior of the laser power of excitation light and the emission intensity of fluorescence in the peak intensity region in the light emitting device of FIG. 1. FIG. 2 is a diagram showing an example of the behavior of the laser power of excitation light and the emission intensity of fluorescence in the emission intensity decreasing region in the light emitting device of FIG. 1. FIG. 2 is a diagram showing another example of the behavior of the laser power of excitation light and the emission intensity of fluorescence in the emission intensity increasing region in the light emitting device of FIG. 1. FIG. 3 is a diagram showing another example of the behavior of the laser power of excitation light and the emission intensity of fluorescence in the peak intensity region in the light emitting device of FIG. 1. FIG. 2 is a diagram showing another example of the behavior of the laser power of excitation light and the emission intensity of fluorescence in the emission intensity decreasing region in the light emitting device of FIG. 1. FIG. FIG. 4 is a diagram schematically showing the configuration of a light-emitting device according to Embodiment 2 of the present invention; FIG. 10 is a diagram schematically showing the configuration of a light-emitting device according to Embodiment 3 of the present invention; FIG. 10 is a perspective view schematically showing the configuration of the main part of a light emitting device according to Embodiment 3 of the present invention; FIG. 10 is a diagram schematically showing the configuration of a light-emitting device according to Embodiment 4 of the present invention; It is a figure for introducing the structure of the light source device which concerns on Embodiment 5 of this invention. It is a figure which shows typically the structure of the light source device which concerns on Embodiment 6 of this invention.

[Embodiment 1]
(Structure of Light Emitting Device)
An embodiment of the present invention will be described in detail below. FIG. 1 is a diagram schematically showing the configuration of a light-emitting device according to Embodiment 1 of the present invention. As shown in FIG. 1, the light emitting device 10 has an excitation light source 11, a fluorescence generator 12, a light receiving element 13 and an adjustment device 14.

(excitation light source)
The excitation light source 11 is a light source for emitting excitation light. The excitation light is light that excites the phosphors in the fluorescent layer and causes the fluorescent layer to emit fluorescence when the fluorescent layer is irradiated with the excitation light. 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 generating device 12 has a reflective substrate 121 and a fluorescent 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 for light. In addition, from the viewpoint of suppressing temperature rise of the fluorescent layer 122 by removing heat from the fluorescent layer 122 that generates heat due to the irradiation of the excitation light, the reflective substrate 121 preferably has high thermal conductivity. Examples of the reflective substrate 121 include an aluminum substrate and a highly reflective alumina substrate, and a metal substrate with a highly reflective coating.

The fluorescence layer 122 is one aspect of a fluorescence source that emits fluorescence upon receiving excitation light. The fluorescent source may be any substance that contains a fluorescent substance capable of generating fluorescence. The fluorescence source may be composed of the phosphor itself that emits fluorescence, or may contain other components such as a binder. Moreover, the shape of the fluorescence source is not limited, and may have, for example, the shape of a predetermined object itself. The fluorescent source may also be in the form of a film or layer placed on the surface of the object.

The phosphor layer 122 is composed of a phosphor and a binder that binds the phosphor. The thickness of the fluorescent layer 122 can be appropriately determined according to the intended use and desired performance of the light emitting device 10 .

The color of fluorescence emitted by the phosphor can be appropriately determined according to the type of excitation light and the application of the light-emitting device. good too.

One or more phosphors may be used. For example, a fluorescent source may include two or more phosphors that emit different colors. For example, a fluorescent source may include two types of phosphors that convert near-ultraviolet excitation light into yellow and blue light. Such a fluorescence source can generate pseudo-white fluorescence that is a mixture of yellow and blue fluorescence.

The phosphor may be an organic compound or an inorganic compound as long as it is a component that emits fluorescence. When laser light is used as the excitation light, the laser power density of the laser light is generally sufficiently high, so the temperature of the fluorescence source tends to rise. 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 emitted fluorescence. For example, when the excitation light is near-ultraviolet light, examples of fluorescent substances that convert the excitation light into red light include CaAlSiN ₃ :Eu ²⁺ . Examples of phosphors that convert the excitation light to yellow light include Ca-α-SiAlON:Eu ²⁺ and Y ₃ Al ₅ O ₁₂ :Ce ³⁺ (YAG:Ce). Examples of phosphors that convert the excitation light to green light include β-SiAlON:Eu ²⁺ and Lu ₃ Al ₅ O ₁₂ :Ce ³⁺ (LuAG:Ce). Examples of phosphors that convert the excitation light to 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⁺ .

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

A binder is a material that binds a fluorescent substance to form a fluorescent substance. No binder is required if the fluorescent source can be composed of the phosphor alone. The binder can be appropriately determined depending on the binding property to the phosphor, and may be an organic compound or an inorganic compound.

The binder preferably has high thermal conductivity from the viewpoint of enhancing the heat dissipation of the fluorescent layer 122 . Moreover, 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 which include alumina and boehmite.

The binder, like the phosphor, is not limited in its form in the fluorescence source. The binder may be in the continuous phase or in the form of particles bound to the phosphor particles in the fluorescent source. Furthermore, the binder may further contain other components other than the aluminum compound as subcomponents within the range in which the desired effects such as high thermal conductivity as described above can be obtained.

Moreover, the fluorescence source may further contain other components other than the binder as long as the desired effect can be obtained. For example, the fluorescent source may further contain dopants that are added in minor amounts to adjust the color of the emitted fluorescence.

In this embodiment, the phosphor layer 122 is composed of inorganic phosphor particles and inorganic binder particles that bind the inorganic phosphor particles. A preferred example of the phosphor layer 122 includes YAG:Ce (yttrium-aluminum-garnet phosphor particles doped with cerium as a dopant, such as Y ₃ Al ₅ O ₁₂ :Ce ³⁺ ) and alumina particles as binder particles. and a layer composed of 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. Thus, the phosphor layer 122 may be composed of an inorganic binder and an inorganic phosphor bound to the binder.

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

The fluorescent layer 122 can be produced by a known method. For example, a composition of a fluorescent substance and a binder is applied to the surface of the reflective substrate 121 by a printing method, the coating film of the composition is dried, Furthermore, it is possible to produce by baking as needed.

(Light receiving element)
The light receiving element 13 is an element that receives 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 light receiving element 13 include an optical phase detector such as an interferometer.

(Regulator)
The adjustment device 14 includes a processor, and has a phase detection section 141 and a control section 142 as functional components.

The phase detector 141 detects the phase of the fluorescence intensity received by the light receiving element 13 . The phase of the intensity of fluorescence is the phase of the periodically fluctuating intensity of fluorescence. The waveform drawn by the periodic fluctuations in fluorescence intensity is not limited, and may be, for example, a sinusoidal curve or a shape formed by repeating other shapes. Furthermore, the waveform may be a regular repetition of a predetermined shape, or may be an irregular shape.

Fluorescence intensity represents the intensity of fluorescence. Fluorescence intensity can be expressed in arbitrary units, and examples of fluorescence intensity units include light energy per unit area, luminance, and any units expressed in relative values thereof. be Hereinafter, the “intensity” of fluorescence is also referred to as “luminescence intensity”.

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

Here, the phase of the intensity of the excitation light is the phase in the periodic variation of the intensity of the excitation light. A periodic change in the intensity of the excitation light is due to, for example, periodic and fine fluctuations in the output of the excitation light source 11 . For example, the periodic variation of the output of the excitation light source 11 has a period of 60 Hz to 60 kHz. The period can be appropriately determined from the above range according to the use of the light source device having the light emitting device 10, for example. Also, the amplitude of the periodic variation 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 fluorescent layer 122 is irradiated with excitation light having an excessive intensity with respect to the emission intensity of fluorescence in the fluorescent layer 122 . Therefore, if the amplitude is too large, 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 terms of the intensity of the excitation light, examples of which include the energy of the excitation light per unit area and the brightness. In the following embodiments, the "intensity" of excitation light is also referred to as "laser power".

There are various methods for adjusting the intensity per unit area of the excitation light in the fluorescent layer 122 . In this embodiment, the adjustment 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 intensity of the fluorescence and the phase of the intensity of the excitation light. The representative value of the output is the output value of the excitation light source 11 that is set so that the excitation light emitted from the excitation light source 11 has a desired intensity. The representative value may be the median value of the periodic and fine variations 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 configuration described above as long as the effects of the present embodiment can be obtained. For example, the light-emitting device 10 may further have a cooling portion (heat sink) (not shown) arranged so as to be in contact with the fluorescence-emitting device 12 . The heat sink is in contact with the reflective substrate 121 and cools the reflective substrate 121 and the phosphor layer 122 as required. It is preferable that the light-emitting device 10 further includes the cooling unit from the viewpoint of suppressing thermal deterioration of the fluorescent layer 122 .

Moreover, 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 irradiated with the excitation light. A temperature sensor is a device that detects temperature in a non-contact manner, such as an infrared temperature sensor.

(Relationship Between Intensity of Excitation Light and Emission Intensity of Fluorescence)
Next, the relationship between the intensity of 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 laser light and the emission intensity of fluorescence in the light emitting device 10. As shown in FIG. FIG. 3 is a diagram showing an example of the relationship between the laser power density of laser light and the temperature of the fluorescent layer 122 in the light emitting device 10. As shown in FIG. The laser power density is, for example, one aspect of the intensity per unit area of the excitation light on the surface of the fluorescent layer 122 . In addition, in the present embodiment, the unit of fluorescence emission intensity is “au” (arbitrary unit). As for the fluorescence emission intensity, the fluorescence emission intensity (e.g., luminance) when the excitation light is not irradiated is set to "0", and the phase of the fluorescence intensity when the excitation light is applied is twice the phase of the intensity of the excitation light. It is represented by a relative value when the emission intensity (for example, luminance) of the fluorescence at that time is set to "1".

The excitation light source 11 emits excitation light such as a blue laser. When the excitation light is incident on the fluorescent layer 122, as shown in FIG. 2, the fluorescence emission intensity in the fluorescent layer 122 increases as the laser power density of the excitation light increases. At the beginning of excitation light irradiation, the emission intensity increases substantially linearly as the laser power density increases. A region in which fluorescence emission intensity exhibits such behavior (region represented by "A" in FIGS. 2 and 3) is also referred to as a "luminescence intensity increased 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.

As the laser power density is further increased from the emission intensity increasing region, as shown in FIG. 2, the emission intensity of fluorescence increases to a maximum value, after which it begins to decrease. Thus, the emission intensity of fluorescence shows a maximum value at a certain point and then decreases with increasing laser power density. A region where the fluorescence emission intensity behaves in this way across the maximum value (for example, a range where the fluorescence emission intensity is 90% or more of the maximum value (brightness saturation point), etc. "B" in FIGS. ) is also referred to as a “peak intensity region”. Even in the peak intensity region, the temperature of the phosphor layer 122 increases with increasing laser power density, as shown in FIG.

Increasing the laser power density further from the peak intensity region decreases the emission intensity of fluorescence, as shown in FIG. Thus, after luminance saturation, the emission intensity of fluorescence decreases. A region where the emission intensity of fluorescence behaves in this way (region represented by “C” in FIGS. 2 and 3) is also referred to as a “luminescence intensity decreasing region”. Also in the emission intensity decreasing region, as shown in FIG. 3, the temperature of the phosphor layer 122 further increases as the laser power density increases.

(Example of controlling intensity of excitation light)
Next, control of the intensity of 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 flickering of the excitation light, it is preferable that the frequency of the excitation light is high. From such a point of view, the frequency of the excitation light may be, for example, 60 Hz or higher.

(If the periodic variation of the intensity of the excitation light is sinusoidal)
<Luminous Intensity Increase Area>
FIG. 4 is a diagram showing an example of the behavior of the laser power of 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 excitation light and the state of fluorescence under the output conditions are, for example, as follows. "θ" below is represented by the product of "2π", "f" (frequency [Hz]) and "t" (time [seconds]).
Laser power of excitation light: average 3.5 W
Shape of periodic fluctuation of excitation light laser power: sinusoidal curve (sin θ)
Amplitude in periodic fluctuation of excitation light laser power: 0.5 W
Emission intensity of fluorescence: average 0.927 (au)
Shape of periodic variation in fluorescence emission intensity: sinusoidal curve (sin θ)

In the emission intensity increasing region, the shape of the periodic variation in the excitation light intensity and fluorescence intensity is both represented by sin θ. The control unit 142 compares the phase of the fluorescence intensity detected by the phase detection unit 141 and the phase of the intensity of the excitation light output from the excitation light source 11 . When the intensity of the fluorescence and the intensity of the 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 controller 142 increases the output of the excitation light source 11 .

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

At the local maximum (maximum) of the emission intensity in the peak intensity region, the frequency of the periodic fluctuations in the intensity of the fluorescence is twice the frequency of the periodic fluctuations in the intensity of the excitation light. Therefore, when the periodic variation in intensity of excitation light is represented by sin θ, the periodic variation in intensity of fluorescence in the peak intensity region is represented by cos 2θ. At this time, it can be determined that the fluorescence emitted from the fluorescent layer 122 has substantially reached luminance saturation. In the above case, the controller 142 does not change the output of the excitation light source 11 .

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

In the emission intensity decreasing region, both the excitation light and the fluorescence have the same period, but the increase and decrease of the periodic fluctuation of the intensity of the fluorescence are opposite to those of the exciton intensity. Thus, in the emission intensity decreasing region, the phase of the periodic fluctuation in fluorescence intensity is opposite to the phase of the periodic fluctuation in excitation light intensity. Therefore, when the periodic variation in the intensity of the excitation light is represented by sin θ, the periodic variation in 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 fluorescent layer 122 is excessively saturated in luminance. In the above case, the control unit 142 reduces the output of the excitation light source 11 .

In addition, the amplitude on the increasing side of the periodic fluctuation of fluorescence emission intensity includes a portion smaller than the amplitude on the decreasing side of the periodic fluctuation. This is because the emission intensity of fluorescence peaks out 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, taking as an example a case where the waveform in the periodic variation 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 excitation light and the emission intensity of 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, for example, as follows.
Amplitude in periodic fluctuation of excitation light laser power: 0.5 W
Laser power of excitation light: average 3.5 W

Even if the waveform in the periodic fluctuation of the laser power of the excitation light is a triangular wave, in the emission intensity increasing region, the emission intensity of the fluorescence periodically changes in the same phase as that of the excitation light, as in the case where the waveform is a sine curve. fluctuating. Therefore, also in this case, the control unit 142 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. In FIG. The laser power of the excitation light in the peak intensity region is 4.1 W on average. Even when the waveform of the periodic fluctuation of the laser power of the excitation light is a triangular wave, in the peak intensity region, the frequency of the periodic fluctuation of the fluorescence intensity is the same as when the waveform is a sine curve. It is twice the frequency in periodic fluctuations. Therefore, in this case as well, the control unit 142 does not change the output of the excitation light source 11 .

FIG. 9 is a diagram showing another example of the behavior of the excitation light laser power and fluorescence emission intensity in the emission intensity decreasing region in the light emitting device 10 . The laser power of the excitation light in the emission intensity decreasing region is 4.6W on average. Even when the waveform in the periodic fluctuation of the laser power of the excitation light is a triangular wave, as in the case where the waveform is a sine curve, in the emission intensity decrease region, the phase of the periodic fluctuation in the intensity of the fluorescence is the intensity of the excitation light. is the opposite of the phase in the periodic variation of Also in this case, the controller 142 reduces the output of the excitation light source 11 .

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 has a more complicated shape than when the waveform of the excitation light is a sinusoidal curve. However, even in this case, the state of fluorescence is substantially the same as when the waveform of the periodic variation of the excitation light is sinusoidal. From the viewpoint of easier analysis of 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 sine curve rather than a triangular wave.

(Specific operation example in this embodiment)
The control unit 142 causes the excitation light source 11 to output excitation light at a predetermined output. The intensity of the output excitation light varies periodically. The excitation light reaches the phosphor layer 122 and excites the phosphor to generate fluorescence. Since the intensity of the excitation light applied to the phosphor periodically fluctuates, the phosphor excited by the excitation light also emits fluorescence whose emission intensity fluctuates periodically. The generated fluorescence is emitted in all directions, but the fluorescence directed toward the reflecting substrate 121 is reflected by the reflecting substrate 121 . Therefore, the fluorescence is emitted upward (the excitation light source 11 side in the drawing) from the surface of the reflective 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 of the periodic variation in the emission intensity of fluorescence detected by the light receiving element 13 . The phase detection by the phase detector 141 may be performed continuously, or may be performed intermittently at predetermined intervals, for example.

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

Regarding periodic fluctuations in emission intensity or laser power, when the phase of fluorescence is the same as the phase of excitation light, it can be determined that the emission intensity of fluorescence is located in the emission intensity increasing 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 fluorescent layer 122 becomes higher, and the emission intensity of fluorescence generated in the fluorescent layer 122 further increases.

Regarding periodic fluctuations in emission intensity or laser power, when the phase of fluorescence is opposite to the phase of excitation light, it can be determined that the emission intensity of fluorescence is located in the emission intensity decreasing region. reduces the output of the excitation light source 11 more. Thereby, the laser power density of the excitation light in the fluorescent layer 122 becomes smaller. Since the fluorescent material in the fluorescent layer 122 is an inorganic fluorescent material, it has excellent heat resistance, so that the fluorescence emission intensity changes reversibly. That is, in the emission intensity decreasing region, when the output of the excitation light source 11 is decreased, the emission intensity of fluorescence generated in the fluorescent layer 122 increases toward the maximum emission intensity and then decreases. Therefore, the emission intensity of fluorescence exits the emission intensity decrease region.

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

(Effect)
By comparing the phases of the periodically fluctuating excitation light intensity (laser power) and fluorescence intensity (luminescence 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 does not reach brightness saturation. It is possible to increase

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

Furthermore, if the phase of the fluorescence is twice the phase of the excitation light, the fluorescence is just before luminance saturation and has substantially the maximum emission intensity, so the laser power density of the excitation light in the fluorescent layer 122 is maintained. By doing so, it is possible to continue generating fluorescence at substantially the maximum emission intensity.

Therefore, in the present embodiment, it is possible to generate fluorescence at an optimum emission intensity (for example, maximum emission intensity) without obtaining in advance the configuration of the fluorescent layer 122 and its environment information. This effect is exhibited regardless of the presence or absence of individual differences caused by the fluorescent layer 122 such as the structure or thickness of the fluorescent layer 122 .

Further, in this embodiment, even when the temperature of the environment of the fluorescent layer 122 changes depending on the season, such as summer or winter, it is possible to obtain the above effect of realizing the optimum emission intensity according to the environment. .

In addition, in the present embodiment, the intensity per unit area of the excitation light in the fluorescent layer 122 is adjusted so that fluorescence with the maximum emission intensity is generated. temperature tends to rise. On the other hand, in this embodiment, the fluorescence generating device 12 is made of inorganic materials (inorganic reflecting base material, inorganic binder and inorganic fluorescent material). Therefore, in the present embodiment, the possibility that the portion of the fluorescent layer 122 irradiated with the excitation light is burned is sufficiently low, and the heat resistance and reliability can be sufficiently improved.

[Embodiment 2]
Other embodiments of the invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

(Structure of Light Emitting Device)
FIG. 10 is a diagram schematically showing the configuration of a light emitting device according to Embodiment 2 of the present invention. As shown in FIG. 10, the light emitting device 20 has an excitation light source 11, a fluorescence generating device 12, a light receiving element 13, an adjusting device 24 and a variable focus lens 25. The excitation light source 11 , fluorescence generator 12 and light receiving element 13 are the same as those in the light emitting device 10 . The variable focus lens 25 is one aspect of a variable focus device for changing the focal length of the excitation light with which the fluorescent layer 122 is irradiated.

The adjustment device 24 includes a phase detection section 141 and a control section 242 . The phase detection section 141 is configured similarly to the phase detection section 141 in the light emitting device 10 . Similarly to the control unit 142, the control unit 242 refers to and compares the phase of the fluorescence emission intensity 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. have a function. The control unit 242 further has a function of controlling the variable focus lens 25 according to the relationship between the phase of fluorescence emission intensity 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 variable focus 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 fluorescent layer 122 through the variable focus lens 25 . The light emitting device 20 is configured such that a signal from the control section 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 fluorescence emission intensity and the phase of the laser power of the excitation light.

When the focal length of the excitation light is changed, the center position of the portion (laser spot) irradiated with the excitation light in the fluorescent layer 122 does not move, but the size of the laser spot changes. The laser spot size is minimized when the focal length is equal to the distance from the variable focus lens 25 to the fluorescent layer 122 in the optical path of the excitation light. The larger the difference between the focal length and the distance from the variable focus 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 laser spot size (eg [mm ² ]), the higher the laser power density (eg [W/mm ² ]) in the fluorescent layer 122 . As the size of the laser spot increases, the laser power density in the fluorescent layer 122 decreases.

Therefore, in this 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 adjusts the focal length so that the size of the laser spot becomes smaller. The variable lens 25 is changed. When the phase of fluorescence emission intensity and the phase of excitation light laser power are opposite to each other, controller 242 causes variable focus lens 25 to change the focal length so that the size of the laser spot becomes larger. When the frequency of fluorescence emission intensity is twice the frequency of the laser power of the excitation light, controller 242 causes variable focus lens 25 to maintain its focal length so as to maintain the size of the laser spot.

(Effect)
In the light emitting device 20 , it is possible to fix the output of the excitation light source 11 and adjust the laser power density of the excitation light in the fluorescent layer 122 . Therefore, the laser power density can be adjusted without changing the amplitude of the excitation light itself.

Also, 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 become hot in summer when the temperature is higher. Therefore, the fluorescent layer 122 can be irradiated with the excitation light so that the laser spot is widened and, for example, the laser spot maximizes the emission intensity of the fluorescent light. On the other hand, the fluorescent layer 122 tends to be cold in winter when the environment is colder. The fluorescence layer 122 can be irradiated with the excitation light with a narrower laser spot.

[Embodiment 3]
Other embodiments of the invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

(Structure of Light Emitting Device)
FIG. 11 is a diagram schematically showing the configuration of a light emitting device according to Embodiment 3 of the present invention. FIG. 12 is a perspective view schematically showing the configuration of a main part of a light emitting device according to Embodiment 3 of the present invention. As shown in FIG. 11, the light emitting device 30 has an excitation light source 11, a fluorescence generating device 12, a light receiving element 13, an adjusting device 34 and a rotating device 35. The excitation light source 11 , fluorescence generator 12 and light receiving element 13 are the same as those in the light emitting device 10 . The rotating device 35 is one aspect of an incident angle changing device for changing the incident angle of the excitation light to the fluorescent layer 122 .

The adjustment device 34 has a phase detector 141 and a controller 342 . The phase detection section 141 is configured similarly to the phase detection section 141 in the light emitting device 10 . Similarly to the control unit 142, the control unit 342 refers to and compares the phase of the fluorescence emission intensity detected by the phase detection unit 141 and the phase of the laser power of the excitation light output from the excitation light source 11. have a function. The control unit 342 further has a function of controlling the rotation device 35 according to the relationship between the phase of the emission intensity of the 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 bottom and a wall rising from its periphery, a shaft 352 projecting from the wall, and a motor 353 . The bottom of the container 351 is rectangular in plan view. A wall rises from each side of the bottom. The shaft 352 extends from the outer surface of each of the pair of opposing wall portions in a direction orthogonal to the outer surface. The motor 353 is appropriately connected to the shaft 352 by a pulley and a belt (not shown) so as to serve as a driving source for rotating the shaft 352 .

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

In addition, 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 indicated by a dashed line. The angle formed by the normal line and the optical axis of the excitation light source 11 is the incident angle of the excitation light with respect to the fluorescent layer 122. In FIG. 11, the angle is represented by θ.

(Specific operation example in this embodiment)
In this embodiment, the adjusting device 34 increases or decreases the incident angle of the excitation light to the fluorescent layer 122 according to the relationship between the phase of the emission intensity of the fluorescence and the phase of the laser power of the excitation light. More specifically, the adjusting device 34 increases or decreases the incident angle of the excitation light to the fluorescent layer 122 by rotating the fluorescent layer 122 with 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 fluorescent layer 122 increases as the size of the laser spot of the excitation light in the fluorescent layer 122 decreases, and decreases as the size increases. . The size of the laser spot of the excitation light on the fluorescent layer 122 is the smallest when the incident angle θ is 0, and increases as the absolute value of the incident angle θ increases.

Therefore, in this 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 adjusts the incident angle θ to make the laser spot size smaller. The rotating device 35 is operated so that it becomes smaller. When the phase of the emission intensity of fluorescence and the phase of the laser power of the excitation light are opposite to each other, the controller 342 rotates the rotating device so that the incident angle θ becomes larger in order to increase the size of the laser spot. 35 is activated. When the phase of the fluorescence is twice the phase of the excitation light, the controller 342 causes the rotation device 35 to maintain the incident angle θ in this case so as to maintain the size of the laser spot.

(Effect)
The light-emitting device 30 has the same effects 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 invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

(Structure of Light Emitting Device)
FIG. 13 is a diagram schematically showing the configuration of a light emitting device according to Embodiment 4 of the present invention. As shown in FIG. 13, the light emitting device 40 has an excitation light source 11, a fluorescence generating device 12, a light receiving element 13, an adjusting device 44 and a Peltier element 45. The excitation light source 11 , fluorescence generator 12 and light receiving element 13 are the same as those in the light emitting device 10 . The Peltier element 45 is one aspect of an environment changing device capable of changing the environment surrounding the fluorescent layer 122 .

The adjustment device 44 includes a phase detection section 141 and a control section 442 . The phase detection section 141 is configured similarly to the phase detection section 141 in the light emitting device 10 . Like 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. Also, the controller 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 arranged on the Peltier element 45 in contact with the Peltier element 45 , and the fluorescent layer 122 is arranged on the reflective substrate 121 . The Peltier element 45 is an element that can adjust the temperature of the portion that contacts the reflective substrate 121 . The temperature adjustable range of the Peltier element 45 is -20 to 120° C., for example. Further, the light emitting device 40 is configured such that a signal from the control section 442 is input to the Peltier element 45 .

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

In this embodiment, the adjustment device 44 sets the desired temperature environment of the phosphor layer 122 by operating the Peltier device 45 . The phase of the fluorescence and the phase of the excitation light are referred to at the set temperature, and the output of the excitation light source is varied. Then, the output of the excitation light source when the phase of the fluorescence is twice the phase of the excitation light is obtained. The temperature environment of the fluorescent layer 122 is changed to another temperature by the Peltier device 45, and the output of the excitation light source when the phase of the fluorescence becomes twice the phase of the excitation light is obtained as described above. Thereby, in the light-emitting device 40, the laser power of the excitation light source corresponding to the fluorescence with the maximum emission intensity is obtained for each temperature when the temperature environment of the fluorescent layer 122 is changed.

(Effect)
With the light-emitting device 40, the characteristics of the light-emitting device can be easily evaluated for each environmental temperature.

[Embodiment 5]
Other embodiments of the invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

(Configuration of light source device)
FIG. 14 is a diagram for introducing the configuration of a light source device according to Embodiment 5 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 split along the split plane along the optical axis direction. As shown in FIG. 14 , light source device 100 has a light emitting device and reflector 120 . The light emitting device has a configuration similar to that described in the first embodiment. Reference numeral 110 in FIG. 14 denotes a line representing the dividing surface.

Reflector 120 is, for example, a cover with 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 reflector 120 is a mirror. A hole penetrating through the wall of the reflector 120 is formed in the central portion of the reflector 120 opposite to the open end.

The excitation light source 11 is arranged outside the reflector 120 . In FIG. 14, the excitation light source 11 is depicted as irradiating 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 collinear with the central axis of the reflector 120. It is placed in a 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 arranged outside the open end of the reflector 120 and at a position where it receives part of the fluorescent light and part of the excitation light emitted from the reflector 120 .

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

As is clear from the above description, in this 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 excitation light B1. The excitation light B<b>1 reaches the fluorescence generator 52 through the hole of the reflector 120 . The fluorescence generator 52 emits excitation light B2 and fluorescence B3. The excitation light B2 is, for example, excitation light surface-reflected by the fluorescent layer 122 and excitation light diffused inside the fluorescent film and reflected by the reflector 120 . Fluorescence B3 is, for example, fluorescence emitted when the fluorescent substance is excited by the excitation light that has reached the fluorescent layer 122 .

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

The light receiving element 13 receives light emitted from the reflector 120 . The emitted light is separated 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 detector 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 refers to the phase information detected by the phase detection unit 541 and controls the output of the excitation light source 11 .

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

When the phase of fluorescence emission intensity and the phase of excitation light laser power are opposite to each other, controller 542 reduces the output of excitation light source 11 . As a result, the laser power density of the excitation light B1 in the fluorescent layer 122 decreases, and the emission intensity of fluorescence increases toward the maximum 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 controller 542 keeps the output of the excitation light source 11 unchanged. As a result, the laser power density of the excitation light B1 in the fluorescent layer 122 is also maintained, and the fluorescence continues to generate substantially the maximum emission intensity.

(Effect)
The light source device 100 of the present embodiment can always generate emitted light containing fluorescent light having the maximum emission intensity based on the phase of the intensity of the emitted light. Therefore, it is possible to easily achieve light emission at a desired light emission intensity without depending on prior processing.

[Embodiment 6]
Other embodiments of the invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

(Configuration of light source device)
FIG. 15 is a diagram schematically showing the configuration of a light source device according to Embodiment 6 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 has 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 a configuration similar to that of the light emitting device described above in the first embodiment.

Wheel 210 is, for example, a disc. At least the periphery of the wheel 210 is formed with a metal layer that serves as a reflective substrate. A phosphor layer 215 is formed over the metal layer at the periphery of the wheel. The configuration of the fluorescent layer 215 is similar to that of the previous embodiment. The motor 220 pivotally supports the center of the wheel 210 in plan view, and is a driving device for rotating 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 it emits excitation light 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 irradiated onto the fluorescent layer 215 in 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 . Both lenses 250 and 260 are placed in the optical path of the excitation light between dichroic mirror 230 and wheel 210 .

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

In this embodiment, dichroic mirror 230 and lenses 240, 250, and 260 constitute an optical system that controls the optical paths of excitation light and fluorescence.

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

An excitation light B<b>1 is output from the excitation light source 11 . Excitation light B 1 passes through lens 240 to dichroic mirror 230 and is reflected toward wheel 210 . The reflected excitation light B1 reaches the fluorescent layer 215 through 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 fluorescent light is reflected by the surface of the metal layer on the back side of the fluorescent layer 215 . Fluorescence is emitted mainly in a direction perpendicular to the surface of the metal layer.

Fluorescence B3 emitted from the fluorescence 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 is transmitted through the dichroic mirror 230 and used as part of the light generated by the light source device 200 .

Fluorescence emitted from the fluorescent layer 215 is also emitted in oblique directions with respect to the main emission direction described above. The light-receiving element 13 receives the fluorescence emitted in such an oblique direction. The phase detection unit 141 detects the phase of the emission intensity of the fluorescence received by the light receiving element 13, and the control unit 142 detects the phase of the emission intensity of the fluorescence 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 by referring to the phase of the laser power of the light B1.

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

When the phase of fluorescence emission intensity and the phase of excitation light laser power are opposite to each other, control unit 142 reduces the output of excitation light source 11 . As a result, the laser power density of the excitation light B1 in the fluorescent layer 215 decreases, and the emission intensity of fluorescence increases toward the maximum 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 controller 142 keeps the output of the excitation light source 11 unchanged. As a result, the laser power density of the excitation light B1 in the fluorescent layer 215 is also maintained, and fluorescent light with a substantially maximum emission intensity continues to be generated.

(Effect)
Also in the light source device 200 of the present embodiment, similarly to the light source device 100 described above, it is possible to constantly generate emitted light containing fluorescent light having the maximum emission intensity based on the phase of the intensity of the emitted light. is. Therefore, it is possible to easily achieve light emission at a desired light emission intensity without depending on prior processing.

[Modification]
(first modification)
In any of the above-described embodiments, the fluorescence generating device may further have a highly reflective film between the reflective substrate and the fluorescent layer from the viewpoint of increasing the fluorescence emission intensity. Examples of materials for the highly reflective film include silver and titanium oxide. Also, examples of the high-reflection film include a high-reflection multilayer film and a dielectric mirror. Alternatively, the fluorescence generating device may further comprise a scattering layer for scattering incident light between the reflecting 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 are obtained. For example, the fluorescent layer may be configured by attaching a fluorescent film made of an inorganic material to a reflective substrate using an organic binder, grease, or a highly heat-resistant inorganic adhesive.

(Third modification)
In any of the foregoing embodiments, the adjustment device is arranged such that the intensity per unit area of the excitation light in the phosphor is a predetermined percentage of the intensity of the excitation light that maximizes the emission intensity of the fluorescence. , the intensity per unit area of the excitation light in the phosphor may be adjusted. In this case, it may be added as a condition to be satisfied that the phase of the intensity of the fluorescence is the same as the phase of the intensity of the excitation light. Such adjustment of the intensity per unit area of the excitation light can be implemented by adopting an appropriately set threshold value.

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

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

If the threshold value is another value corresponding to the emission intensity of fluorescence, for example, the output value of the excitation light source, the adjustment device refers to the detection result obtained by the adjustment device to estimate the output value of the excitation light source. may In this case, the adjustment device further refers to the obtained estimated value in controlling the output of the excitation light source, thereby performing control of the intensity per unit area of the excitation light in the fluorescent layer based on the threshold. can.

The threshold can be set as appropriate. For example, the threshold value may be a value corresponding to an emission intensity that is less than the maximum emission intensity of fluorescence, eg, 80% of the maximum emission intensity. In this case, for example, in addition to the condition that the emission intensity of the fluorescence is 80% or less of its maximum value, if the condition that the excitation light and the fluorescence are in phase is further set, the fluorescence in the emission intensity decrease region It is possible to prevent the occurrence of For this reason, it is possible to prevent deterioration of the phosphor due to heat, and as a result, it is possible to generate fluorescence with a stable emission intensity for a long period of time. Thermal deterioration of the phosphor is, for example, a decrease in fluorescence output due to structural change, cracking, or oxidation of the phosphor, or an increase in fluorescence output due to volatilization of impurities. Alternatively, setting the conditions as described above is advantageous from the standpoint of stably using 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 acquired value obtained by obtaining the maximum value of fluorescence emission intensity or a value corresponding to the maximum value. The acquired value may be a measured value obtained by actual measurement, or an estimated value estimated based on the measurement result.

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

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

Alternatively, the threshold can be set by measuring the fluorescence emission intensity at a plurality of points from the emission intensity increasing region to just before the maximum value in the peak intensity region. For example, perform measurements at multiple points as described above, calculate the increment of luminescence intensity between the measurement points, and estimate the maximum value of luminescence intensity under the condition that the calculated value of the increment is positive but sufficiently small. do. The threshold can be set based on such estimates.

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

In addition, the above-described method using the estimated value of the maximum emission intensity of the fluorescence does not cause deterioration of the fluorescence source due to heat and the deterioration of the light-emitting device due to heat deterioration when the fluorescence source is composed of an organic compound that is relatively heat-sensitive. This is preferable from the viewpoint of suppressing reduction in reliability.

Furthermore, the adjustment device may further include a functional configuration for setting a threshold, and a functional configuration for prioritizing control based on the threshold in controlling the output of the excitation light source after setting the threshold. . By configuring the adjustment 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 threshold.

If the condition is set such that the fluorescence emission intensity is at least a predetermined percentage of the maximum value (e.g., at least 80% of the maximum value), it is possible to constantly generate fluorescence in the peak intensity range. becomes. Such threshold-based control is even more effective in terms of generating fluorescence with higher luminous efficiency.

(Fourth modification)
In any of the above-described embodiments, the adjustment device may further include an emission intensity detection section that detects the emission intensity of the fluorescence received by the light receiving element. According to this configuration, it is possible to further refer to the detection value of fluorescence emission intensity in setting the aforementioned threshold value or in controlling the intensity per unit area of the excitation light in the fluorescent layer by the controller. As a result, it becomes possible to more precisely adjust the intensity per unit area of the excitation light in the fluorescent layer.

(Fifth Modification)
In any of the above-described embodiments, adjustment of the intensity per unit area of the excitation light in the fluorescent layer in one embodiment and excitation in the fluorescent layer in another embodiment Alternatively adjusting the intensity per unit area of light may both be performed. For example, in each of Embodiments 2 to 4, the control of the output of the excitation light source in Embodiments 1, 5, and 6 may be further implemented. In this case, multiple controls may be executed simultaneously, alternately, or irregularly. Performing both the adjustment of the intensity per unit area of the excitation light in the fluorescent layer in Embodiments 2 to 4 and the adjustment in Embodiments 1, 5, and 6 means that the emission intensity of the fluorescence emitted by the fluorescent layer is more effective from the viewpoint of precisely controlling the

(Sixth modification)
In Embodiment 3, 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, a device that rotates the excitation light source 11 with the intersection of the optical axis of the excitation light source 11 and the fluorescent layer 122 as the central point of rotation is used to change the incident angle θ. may

(Seventh modification)
In Embodiment 4, the adjustment 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 summer environment, for example, it is possible to generate fluorescence in a low-temperature environment corresponding to a winter environment.

(Eighth modification)
In Embodiment 6, as in Embodiment 5, light synthesized from excitation light and fluorescence may be adopted as emitted light from the light source device. When such combined light is used as emitted light, the adjustment 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, when the control unit controls the output of the excitation light source, refer to a table storing information on the ratio of the emission intensity of the excitation light to the emission intensity of the fluorescence, which is required for the combined light. can be performed by determining the output of the excitation light source using

[Example of realization by software]
The control blocks of the adjustment devices 14, 24, 34, 44, 54 (especially 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 implemented by (hardware) or by software.

In the latter case, the coordinator 14, 24, 34, 44, 54 comprises a computer executing program instructions, which are software implementing the respective functions. This computer includes, for example, at least one processor (control device) and at least one computer-readable recording medium storing the program. 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, 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. In addition, a RAM (Random Access Memory) for developing the above program may be further provided.

Also, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. Note that one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

〔summary〕
A light-emitting device 10 according to aspect 1 of the present invention includes an excitation light source 11 for irradiating excitation light, a fluorescence source (fluorescence layer 122) that emits fluorescence upon receiving 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 detects the phase of the intensity of the fluorescence received by the light receiving element, and adjusts the intensity per unit area of the excitation light in the fluorescence source according to the detected phase of the intensity of the fluorescence and an adjustment device 14 . Then, the adjusting device increases the intensity per unit area of the excitation light 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, and the phase of the intensity of the fluorescence is equal to the intensity of the excitation light. , the intensity per unit area of the excitation light at the fluorescent source is reduced.

According to the above configuration, in a light-emitting device that emits fluorescence by receiving excitation light from an excitation light source with a fluorescence source, fluorescence can be emitted at a desired intensity without depending on prior processing.

In the light emitting device according to aspect 2 of the present invention, in the aspect 1 above, the adjustment 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 intensity of the fluorescence and the phase of the intensity of the excitation light. .

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

The light emitting device according to aspect 3 of the present invention, in aspect 1 or 2 above, may further include a variable focus device (variable focus lens 25) capable of changing the focal length of the excitation light irradiated to the fluorescence source, The adjustment device may change the focal length of the excitation light by the variable focus device according to the relationship between the phase of the intensity of the fluorescence and the phase of the intensity of the excitation light.

According to the above configuration, since 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, without changing the amplitude of the intensity of the excitation light , it is possible to adjust the intensity per unit area of the excitation light in the fluorescent source.

The light emitting device according to aspect 4 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, wherein the adjusting device is the intensity of fluorescence The incident angle of the excitation light to the fluorescence source by the incident angle changing device may be increased or decreased according to the relationship between the phase of the excitation light and the phase of the intensity of the excitation light.

According to the above configuration, similarly to the third aspect, 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.

A light-emitting device according to aspect 5 of the present invention is the rotating device according to aspect 4, wherein the incident angle changing device rotates the fluorescence source about a rotation axis parallel to a direction intersecting the optical axis of the excitation light, Often, the adjusting device increases or decreases the incident angle of the excitation light to the fluorescence source by rotating the fluorescence source with a rotation device according to the relationship between the phase of the intensity of the fluorescence and the phase of the intensity of the excitation light. may

According to the above configuration, it is more effective from the viewpoint of changing the incident angle with an inexpensive and simple configuration.

In the light-emitting device according to mode 6 of the present invention, in any one of modes 1 to 5, the fluorescence source may be composed of an inorganic binder and an inorganic phosphor bound to the binder.

The above configuration is more effective from the viewpoint of improving the heat resistance of the fluorescent source and enhancing the stability and reliability of the light emitting device.

A light-emitting device according to aspect 7 of the present invention in aspects 1 to 6 above may further include an environment changing device capable of changing the environment surrounding the fluorescence source.

According to the above configuration, it is possible to easily evaluate the characteristics of the light-emitting device due to changes in the environment.

Light source devices 100 and 200 according to aspect 8 of the present invention include the light emitting device according to any one of aspects 1 to 7 and an optical system (reflector 120 or dichroic mirror 230 and lenses 240, 250, 260).

According to the above configuration, in a light source device having a light emitting device that emits fluorescence by receiving excitation light from an excitation light source with a fluorescence source, fluorescence can be emitted with a desired emission intensity without depending on prior processing.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

Reference Signs List 10, 20, 30, 40 light emitting device 11 excitation light source 12, 52 fluorescence generator 13 light receiving element 14, 24, 34, 44, 54 adjustment device 25 variable focus lens (variable focus device)
35 rotation device 45 Peltier element (environment changing device)
Reference Signs List 100, 200 light source device 110 split surface 120 reflector (optical system)
121 reflective substrate 122, 215 fluorescent layer (fluorescent source)
141, 541 phase detector 142, 242, 342, 442, 542 controller 210 wheel 220, 353 motor 230 dichroic mirror 240, 250, 260 lens 351 container 352 axis B1, B2 excitation light B3 fluorescence

Claims (8)

an excitation light source for irradiating excitation light;
a fluorescence source that emits fluorescence upon receiving the excitation light from the excitation light source;
a light receiving element that receives part of the fluorescence emitted by the fluorescence source;
an adjustment device that detects the phase of the intensity of the fluorescence received by the light receiving element and adjusts the intensity per unit area of the excitation light in the fluorescence source according to the detected phase of the intensity of the fluorescence. death,
When the phase of the intensity of the fluorescence is the same as the phase of the intensity of the excitation light, the adjustment device increases the intensity per unit area of the excitation light in the fluorescence source and adjusts the phase of the intensity of the fluorescence. lowering the intensity per unit area of the excitation light in the fluorescence source when is in phase with the intensity of the excitation light;
Luminescent device. 2. The light-emitting device according to claim 1, wherein said adjusting device increases or decreases the representative value of the output of said excitation light source according to the relationship between the phase of the intensity of said fluorescence and the phase of said intensity of said excitation light. further comprising a variable focus device capable of changing the focal length of the excitation light irradiated to the fluorescence source;
The adjustment device changes the focal length of the excitation light by the variable focus device according to the relationship between the phase of the intensity of the fluorescence and the phase of the intensity of the excitation light.
The light-emitting device according to claim 1 or 2. further comprising an incident angle changing device capable of changing the incident angle of the excitation light to the fluorescence source;
2. The adjusting device increases or decreases the incident angle of the excitation light to the fluorescence source by the incident angle changing device according to the relationship between the phase of the intensity of the fluorescence and the phase of the intensity of the excitation light. 4. The light emitting device according to any one of 1 to 3. The incident angle changing device is a rotating device that rotates the fluorescence source about a rotation axis parallel to a direction intersecting the optical axis of the excitation light,
The adjustment device rotates the fluorescence source by the rotation device according to the relationship between the phase of the intensity of the fluorescence and the phase of the intensity of the excitation light, thereby causing the excitation light to flow into the fluorescence source. 5. The light emitting device of claim 4, wherein the angle of incidence 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 said fluorescent 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 optical paths of one or both of the excitation light and the fluorescence.

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