JP2016145848A - Optical conversion element and light source using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-performance light source that generates RGB primary colours highly efficiently and at a high speed in a time division manner without generating colour breakup, and that is configured to have less number of components as light source.SOLUTION: Semiconductor light-emitting elements 10R, 10G, 10B as a light source 1 are arranged on a heat sink 90. Light emitted from the semiconductor light-emitting element 10R is converted into parallel light through a collimator lens 20, and is further guided through a first relay lens 25R and a second relay lens 27R to a dichroic mirror 30R. Excitation light transmitting through the dichroic mirror 30R is condensed by a condenser lens 40R, and a first fluorescent emission part 51R is irradiated with the excitation light. A main optical axis of the excitation light condensed by the condenser lens 40R is disposed so as to be incident vertically to a rotation axis of a wavelength conversion part 50. Similarly, a second fluorescent emission part 51G and a third fluorescent emission part 51B are irradiated with emission light emitted from the semiconductor light-emitting elements 10G, 10B.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical conversion element used in a projector such as a commercial projector, a home projector, and a pico projector, a rear projection television, a head-up display, and the like, and particularly to a light source including the optical conversion element. The present invention relates to a light source having a large light output, a small speckle, and a high directivity of emitted light.

  Special illumination light sources include store downlights, projector light sources, automobile headlights (headlights, etc.), and halogen light, high-pressure mercury lamps, metal halide lamps, etc. are used as these light sources. . Among these, high-intensity discharge lamps such as high-pressure mercury lamps and metal halide lamps use arc discharge, and thus can emit light with high directivity with high efficiency and high output. However, there are problems such as a long time until lighting and stabilization, a large environmental load due to containing mercury, and a short time until the luminance defined as the lifetime is halved.

  In recent years, a light emitting device using a semiconductor light emitting element such as a light emitting diode (LED) or a semiconductor laser as a light source or an excitation light source has been actively developed. The structure of a light-emitting device using a semiconductor light-emitting element includes a light-emitting wavelength or emission spectrum in which the emission wavelength is changed in the range of visible light (430 to 660 nm) by changing the semiconductor material or composition, or in combination with a phosphor. Various configurations have been proposed depending on the application.

  For example, in Patent Document 1 (all R, G, B LEDs) and Patent Document 2 (all R, G, B using semiconductor lasers), LEDs and semiconductor lasers that emit blue, green, and red light are used. A combined light source has been proposed. These light sources are particularly useful for display applications because, unlike conventional high-intensity discharge lamps, light of the three primary colors can be emitted at any timing. However, since the LED has a large divergence angle of the emitted light and a large area of the light emitting portion, there is a problem that the light use efficiency in the optical system constituting the light source is low and the light output intensity of the light source cannot be increased. On the other hand, although the divergence angle of the emitted light is small but the coherence of the emitted light is high, when a light source composed of a semiconductor laser is used for a display, the image quality caused by speckle noise is particularly generated in the green region and the red region. Decrease becomes an issue.

In order to solve such a problem, a method of suppressing speckle noise while increasing light utilization efficiency by combining a semiconductor laser and a phosphor has been proposed. For example, Patent Document 3 proposes a light emitting device that combines a semiconductor laser that emits blue light, a Y ₃ (Al, Ga) ₅ O ₁₂ phosphor (green phosphor), and a CASN phosphor (red phosphor). Yes. Patent Document 4 proposes a light-emitting device in which all three primary colors are made of fluorescence by combining a semiconductor light-emitting element that emits ultraviolet light and a disk in which red, green, and blue phosphor layers are arranged in parallel. .

  Hereinafter, a conventional light emitting device will be described with reference to FIG.

As shown in FIG. 14, a conventional light-emitting device includes a light-emitting diode 1001 that emits ultraviolet light, and a color wheel 1002 in which phosphor layers including red, green, and blue phosphors are arranged for each partitioned region. When the color wheel rotates, the light emitted from the light emitting diode 1001 is sequentially converted into red, green, and blue, and is driven so that white light is emitted when observed on a time average. In the configuration of the color wheel, (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ C ₁₂ : Eu or (Ba, Mg) Al ₁₀ O ₁₇ : Eu is used as the blue phosphor. It is described that ZnS: Cu, Al or (Ba, Mg) Al ₁₀ O ₁₇ : (Eu, Mn) is used as the green phosphor, and that Y ₂ O ₂ S: Eu is used for the red phosphor. Yes. In addition, one digital mirror device (Digital Mirror Device, DMD) is synchronized with the transition of the three primary colors of red R, green G, and blue B generated by time division, and the R / G / B single color is synchronized with the DMD panel. Display video. Since this time division speed is a speed that cannot be identified by humans, it is recognized as a color image in which RGB is mixed.

JP 2009-252651 A Japanese National Patent Publication No. 11-064789 JP 2012-8409 A JP 2004-341105 A

  However, in the above configuration, (i) it is difficult to reduce the size by using a wheel, (ii) there is a divergence angle of the emitted light of the phosphor, and light is not sufficiently captured, and (iii) heat dissipation generated by the phosphor (Iv) Since the RGB time division cycle is limited by the rotation speed of the color wheel and it is difficult to make it faster than several ms, RGB color mixing is not performed correctly when the viewpoint is moved. There was a problem that the phenomenon would occur.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an optical conversion element and a light source that can solve the above-described problems without increasing the number of components.

  In order to solve the above-described problems, an optical conversion element according to the present invention is an optical conversion element in which at least one phosphor-containing layer is provided on the surface of a uniaxial rotating substrate, and the rotation of the uniaxial rotating substrate is performed. The phosphor-containing layer is formed concentrically with respect to the axis.

  With this configuration, a rotating wheel with a large occupation area is not necessary, and the light source can be downsized.

  In the optical conversion element according to the present invention, a transparent body is laminated on the phosphor-containing layer.

  With this configuration, since the transparent body functions as a convex lens, the emission radiation angle of the fluorescence emitted from the phosphor-containing layer can be reduced, so that more efficient fluorescence can be captured.

  In the optical conversion element according to the present invention, the rotating base is a columnar heat conductor, a rotation driving mechanism having the columnar heat conductor as a rotation axis, and a cooling mechanism on a part of the surface of the columnar conductor. Is provided.

  With this configuration, it is possible to efficiently cool the heat generated in the phosphor-containing layer, and it is possible to suppress a decrease in light emission efficiency due to an increase in the temperature of the phosphor.

  The optical conversion element according to the present invention includes an antireflection film having a wavelength region of 380 nm to 700 nm on the outermost surface of the rotating base.

  With this configuration, the light reflection loss of excitation light and fluorescence is reduced, so that the conversion efficiency from excitation light to fluorescence is improved, and energy saving is possible.

  The optical conversion element according to the present invention includes a moving mechanism in a direction parallel to the rotation axis of the rotating base.

  With this configuration, a plurality of fluorescence can be emitted with one optical axis, and the optical system can be simplified.

  A light source according to the present invention includes the optical conversion element according to any one of claims 1 to 5 and an excitation light source that emits excitation light, and the excitation light is incident from a direction perpendicular to the rotation axis of the phosphor-containing layer. .

  With this configuration, a compact and highly efficient light source can be configured.

  The light source according to the present invention includes a dichroic mirror and a condenser lens between the excitation light source and the optical conversion element.

  With this configuration, the RGB three primary colors can be generated in a time-sharing manner with high efficiency and high speed in a compact configuration, so that a high-performance light source without color breakup can be realized.

  According to the configuration of the present invention, in an optical conversion element and a light source including a phosphor layer and a semiconductor solid excitation light source, RGB three primary colors can be generated efficiently with a compact configuration, and RGB can be generated by high-speed time division without causing color breakup. Light can be generated.

Sectional drawing which shows the structure of the light source which concerns on the 1st Embodiment of this invention The figure which shows the structure of the optical conversion element which concerns on the 1st Embodiment of this invention. The figure shown about the structure of the light source which concerns on the 1st Embodiment of this invention, and the time of the operation | movement which radiate | emits red, green, and blue fluorescence In the light source according to the first embodiment of the present invention, the RGB phosphor layer excitation timing chart when seven color sources are generated in a time division manner (A) Sectional drawing and (B) Side view which show the optical conversion element which concerns on the modification 1 of the 1st Embodiment of this invention (A) Sectional drawing and (B) Side view which show the optical conversion element which concerns on the modification 2 of the 1st Embodiment of this invention The figure which shows the manufacturing method of the modification 2 of the optical conversion element which concerns on the 1st Embodiment of this invention. (A) Sectional drawing and (B) Side view which show the optical conversion element which concerns on the modification 3 of the 1st Embodiment of this invention Sectional drawing which shows the optical conversion element which concerns on the modification 4 of the 1st Embodiment of this invention (A) sectional view and (B) bird's-eye view schematic diagram of wavelength converter 50 showing an optical conversion element concerning modification 5 of a 1st embodiment of the present invention. Sectional drawing which shows the optical conversion element which concerns on the modification 6 of the 1st Embodiment of this invention Sectional drawing which shows the structure of the light source which concerns on the 2nd Embodiment of this invention. The figure shown about the structure of the light source which concerns on the 2nd Embodiment of this invention, and the time of the operation | movement which radiate | emits red fluorescence, green fluorescence, and blue laser diffused light (A) (b) The figure which shows the structure of the conventional light source

  Hereinafter, the optical conversion element and the light source of the present invention will be described based on embodiments. Each of the embodiments described below shows a preferred specific example of the present invention. The numerical values, shapes, materials, component arrangement methods, usage forms, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present invention are described as optional constituent elements.

  Each figure is a schematic diagram and is not necessarily illustrated exactly. Moreover, in each figure, the same code | symbol is attached | subjected to the same component.

(First embodiment)
Hereinafter, the configurations and effects of the optical conversion element and the light source according to the first embodiment of the present invention and the modifications thereof will be described with reference to FIGS.

  FIG. 1 is a diagram showing a configuration of a light source according to the first embodiment of the present invention. FIG. 2 is a bird's-eye view of the wavelength conversion unit 50 used in the light source 1 according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating the configuration of the light source according to the first embodiment of the present invention and the operation for emitting red, green, and blue fluorescence. FIG. 4 is a diagram illustrating the first embodiment of the present invention. It is a figure which shows the RGB fluorescent substance layer excitation timing chart in the case of making 7 color sources time-division generation in the light source which concerns on a form.

  1 to 13, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

(Constitution)
As shown in FIG. 1, the light source 1 according to the present embodiment mainly includes semiconductor light emitting devices 10R, 10G, and 10B that are, for example, nitride semiconductor lasers that emit near-ultraviolet light, and semiconductor light emitting devices 10R, 10G, The wavelength converter 50 is configured to convert near-ultraviolet light emitted from 10B into RGB colors. In order to distinguish the semiconductor light emitting elements that excite each color of RGB, they are described as 10R, 10G, and 10B, but the same semiconductor light emitting elements may be used.

As shown in FIG. 2, the wavelength conversion unit 50 has a configuration in which a phosphor is provided for each region on the columnar base 58, and rotates at a predetermined rotational speed during operation. The diameter of the substrate 58 is 5 mm to 20 mm, and the specific configuration of the wavelength conversion unit 50 is, for example, on the predetermined outer periphery of the substrate 58 that is a cylindrical aluminum alloy rod, the first fluorescent light emitting unit 51R and the second A fluorescent light emitting part 51G and a third fluorescent light emitting part 51B are formed for each region. In the first fluorescent light emitting portion 51R, the red phosphor whose main component is La ₂ W ₃ O ₁₂ activated with Eu and Sm is an organic transparent material such as dimethyl silicone, or an inorganic transparent material such as low melting point glass. It is mixed with the binder, which is a material, and formed on the outer periphery of the substrate 58 as a phosphor layer having a thickness of 100 μm to 1000 μm and a width of 5 mm to 10 mm. The second fluorescent light emitting part 51G is obtained by mixing a green phosphor whose main component is, for example, Ce-activated Y ₃ (Al, Ga) ₅ O ₁₂ with an organic or inorganic transparent material. Further, the third fluorescent light-emitting portion 51B is obtained by mixing a blue phosphor whose main component is, for example, Eu-activated Sr ₃ MgSi ₂ O ₈ with an organic or inorganic transparent material.

  In FIG. 1, an auxiliary rotating shaft 57 is provided at the center of the base body 58, the end of the shaft is held by a bearing 59, and the other shaft end is fixed to a rotating shaft 56 of a rotating mechanism 55 such as a motor. The base body 58 is configured to rotate at the number of rotations.

  More specifically, the light source 1 including the wavelength conversion unit 50 is configured as follows.

  In FIG. 1, first, the light source 1 includes, for example, semiconductor light emitting elements 10R, 10G, and 10B, which are semiconductor lasers having a light output of 2 watts and a center wavelength of light emission wavelength in the range of 380 nm to 430 nm, on the heat sink 90. Nine (three in each of 10R, 10G, and 10B in FIGS. 1 to 3) are arranged. The light emitted from the semiconductor light emitting element 10R is converted into parallel light by the collimating lens 20, and further guided to the dichroic mirror 30R via the first relay lens 25R that is a convex lens and the second relay lens 27R that is a concave lens. Here, the dichroic mirror 30R is set to transmit light with a wavelength of 380 nm to 430 nm and reflect light with a wavelength of 430 nm to 800 nm, for example. On the main optical axis, the dichroic mirror 30R, the condenser lens 40R, and the first fluorescent light emitting portion 51R are arranged in this order. The excitation light that has passed through the dichroic mirror 30R is collected by the condenser lens 40R and irradiated onto the first fluorescent light emitting unit 51R. At this time, the main optical axis of the excitation light condensed by the condenser lens 40 </ b> R is installed so as to enter perpendicularly to the rotation axis direction of the wavelength conversion unit 50. Similarly, the emitted light emitted from the semiconductor light emitting elements 10G and 10B is irradiated onto the second fluorescent light emitting unit 51G and the third fluorescent light emitting unit 51B, respectively. At this time, the wavelength transmission characteristics of the dichroic mirrors 30G and 30B are the same as those of the dichroic mirror 30R.

(Operation)
Next, the operation of the light source 1 according to the present embodiment will be described using an image projection apparatus 199 including the light source 1 shown in FIG. The image projection apparatus 199 according to the present embodiment is mainly configured such that an image display element 71, a projection lens 65, and the like are disposed in the emission portion of the light source 1 so that an image can be projected.

  The light source 1 of the present embodiment includes a so-called red wavelength converted light 78R having a main emission wavelength in the range of 590 to 660 nm, a so-called green wavelength converted light 78G having a main emission wavelength in the range of 500 to 590 nm, A so-called blue wavelength-converted light 78B having a light emission wavelength in the range of 430 to 500 nm emits time-division RGB light 100 that is continuous in time. That is, the time-division RGB light 100 is white light formed by periodically emitting red light, green light, and blue light, which are light of the three primary colors, in the order of red → green → blue → red. Is, for example, about 8.3 ms (120 Hz) during double-speed scanning.

Next, the operation of the light source 1 will be described. For example, the excitation light 75R having a central wavelength of 405 nm and a total light amount of 18 watts emitted from the plurality of semiconductor light emitting elements 10R becomes a single light beam by the collimating lens 20, the first relay lens 25R, and the second relay lens 27R, and passes through the dichroic mirror 30R. The light passes through and is condensed to an area of, for example, 1 mm ² or less by the condensing lens 40R on the first fluorescent light emitting unit 51R. Similarly, the excitation lights emitted from the semiconductor light emitting elements 10G and 10B are condensed on the second and third fluorescent light emitting portions 51G and 51B, respectively. The condensed excitation light is converted from light having a central wavelength of 405 nm into wavelength converted light 78R having a main emission wavelength of 590 nm to 660 nm by the red phosphor included in the first fluorescent light emitting member 51R, and the condensing lens 40R. Radiated to the side. At this time, the radiation angle of the wavelength converted light 78R is omnidirectional so-called Lambertian light. However, since the light emitting area is a point light source of 1 mm ² or less, it becomes almost parallel light by the condenser lens 40R and travels toward the dichroic mirror 30R. The wavelength converted light 78R is reflected by the dichroic mirror 30R and travels toward the third relay lens 41. Similarly, the green phosphor contained in the second fluorescent light emitting portion 51G converts the central wavelength from 405 nm to wavelength converted light 78G having a main light emission wavelength of 500 to 590 nm and guides it to the third relay lens 41. Further, the blue phosphor contained in the third fluorescent light emitting unit 51B is converted from the central wavelength 405 nm to the wavelength converted light 78B having the main light emission wavelength of 430 to 500 nm and guided to the third relay lens 41. The wavelength-converted lights 78R, 78G, and 78B are superimposed to form the time-division RGB light 100, which is condensed and incident on the end of the rod lens 42 by the third relay lens 41. Then, the time-division RGB light 100 multiple-reflected in the rod lens 42 is radiated after the light intensity distribution of the wavefront is converted into a rectangle, and becomes straight light by the fourth relay lens 43. The light is guided to a reflective image display element 71 such as a DMD. The light irradiated to the image display element 71 is reflected as signal light 80 on which a two-dimensional video signal is superimposed, and becomes image light 89 that can be projected onto a predetermined screen (not shown) by the projection lens 65. 199.

  Further, a driving method of the semiconductor light emitting elements 10R, 10G, and 10B for generating the time division RGB light 100 will be described. FIG. 4 is a diagram showing an RGB phosphor layer excitation timing chart when seven color sources are generated in a time division manner in the light source according to the first embodiment of the present invention. To switch one cycle in the order of blue → green → red → white → cyan → yellow → black, the semiconductor light-emitting element is turned on 10B alone (blue) → 10G alone ON (green) → 10R alone ON (red) → 10R, 10G 10B simultaneous ON (white) → 10G, 10B simultaneous ON (cyan) → 10R, 10G simultaneous ON (yellow) → 10R, 10G, 10B all OFF (black) may be sequentially operated.

(effect)
As described above, according to the present invention, by using the semiconductor light emitting element as the excitation light source, the excitation light source can be turned on / off at a high speed on a time scale on the order of nanoseconds, and double-speed scanning (120 Hz, period 8. Even at a speed of 3 ms) or more, the RGB three primary colors can be generated in a time division manner without any problem. Further, when a function equivalent to that of the present invention is realized by using a conventional color wheel, three color wheels are required, and the light source size becomes significantly larger than that of the present invention.

  With this configuration, the RGB three primary colors can be generated in a time-sharing manner with high efficiency and high speed with a compact configuration without increasing the number of components, and thus a high-performance light source without color breakup can be provided.

In the above-described configuration, the above-described phosphor is used as the phosphor, but the present invention is not limited to this. For example, Eu activated (Ba, Sr) ₃ Al ₁₀ O ₁₇ phosphor represented by Eu activated Ba ₃ Al ₁₀ O ₁₇ as a blue phosphor, Eu activated (Sr, Ca, Ba, Mg) ₁₀ , (PO ₄ ) ) ₆ Cl ₂ phosphor may be used. Further, as a green phosphor, Eu-activated β-type SiAlON phosphor, Eu-activated SrSiO ₃ phosphor, Eu-activated SrSi ₂ O ₂ N ₂ phosphor, Eu-activated Ba ₃ Si ₈ O ₁₂ N ₂ phosphor, Ce-activated CaSc ₂ O _A phosphor in which Ce or Eu is activated, such as a ₄ phosphor, can be used.

The red phosphor is not limited to Eu and Sm activated La ₂ W ₃ O ₁₂ . For example, one or more of silicon oxide, tungsten oxide, molybdenum oxide, indium oxide, yttrium oxide, zinc oxide, silicon nitride, silicon oxynitride, aluminum oxynitride, and organic polymer are included in the constituent elements of the base material Any phosphor may be used as long as the base material contains a lanthanoid ion element or a metal ion element as an activator. Specifically, Eu activated La ₂ O ₂ S phosphor, Eu activated LiW ₂ O ₈ phosphor, Eu and Sm activated LiW ₂ O ₈ phosphor, Eu and Mn activated (Sr, Ba) ₃ MgSi ₂ O ₈ fluorescence Fluorescence lifetime of phosphors such as phosphors, Mn activated 3.5MgO · 0.5MgF ₂ · GeO ₂ phosphor, Eu activated YVO ₄ phosphor, Eu activated Y ₂ O ₃ phosphor, Eu activated Y ₂ O ₂ S phosphor This embodiment is effective for a red phosphor that is long but has a narrow half-width of the fluorescence spectrum.

  Moreover, the rare earth complex fluorescent substance which used the lanthanoid ion element and the metal ion element as an activation material may be sufficient. Specifically, a rare earth complex phosphor having a molecular structure in which two types of phosphine oxides are coordinated to trivalent europium.

  In the present embodiment, a semiconductor laser having a central wavelength of 405 nm is given as an example of the semiconductor light emitting device, but this is not restrictive. For example, the center wavelength can be adjusted in the range of 380 nm to 430 nm according to the absorption spectrum of the phosphor, such as the center wavelengths of 395 nm, 400 nm, and 410 nm, or a combination of a plurality of semiconductor lasers having different center wavelengths in the range of 2 nm to 10 nm. It is also possible to use with a wide spectral width.

(Modification 1)
Next, a first modification of the optical conversion element according to the first embodiment will be described with reference to FIG. The present modification is different from the first embodiment in the configuration of the wavelength conversion unit 50. For this reason, it demonstrates centering on a different part of both using the enlarged view of fluorescent-light emission part vicinity. In FIG. 5, the first to third fluorescent light emitting portions 51 </ b> R, 51 </ b> G, and 51 </ b> B of FIG. 1 are shown as the fluorescent light emitting portion 51. 5A shows a cross-sectional view in the direction parallel to the rotation axis of the wavelength conversion unit 50, and FIG. 5B shows a cross-section (side view) in the direction perpendicular to the rotation axis.

  The wavelength conversion unit 50 of the present modification is characterized in that a transparent body 60 is formed on the fluorescent light emitting unit 51 of the wavelength conversion unit 50 of the first embodiment.

  Specifically, in the side view of FIG. 5B, for example, a transparent body 60 such as a low melting point glass that is transparent with respect to a wavelength of 380 nm to 700 nm is concentrically formed on the fluorescent light emitting portion 51.

  With this configuration, the wavelength converted light 78 emitted in all directions from the fluorescent light emitting unit 51 is refracted at the air interface with the transparent body 60, and the emission angle of the wavelength converted light 78 can be reduced as shown in FIG. Therefore, the light can be collected more efficiently by a condenser lens (not shown).

  By using the configuration of this modification as described above, the emission angle of the wavelength converted light 78 that is originally emitted in Lambertian in all directions can be reduced, and the utilization efficiency of the wavelength converted light can be increased.

(Modification 2)
Next, a second modification of the light source conversion element according to the first embodiment will be described with reference to FIG. 6 shows an enlarged view of the vicinity of the fluorescent light emitting unit in FIG. 1, as in FIG. 5. FIG. 6 (A) shows a sectional view in a direction parallel to the rotation axis of the wavelength converting unit 50 (FIG. 1). FIG. 6B shows a cross-sectional (side) view in a direction perpendicular to the rotation axis. As can be seen from a comparison between FIG. 6A and FIG. 5A, the present modification is significantly different in cross-sectional shape of the transparent body 60 from the first modification.

  The transparent body 60 of this modification is characterized in that it has a cross-sectional shape as shown in FIG. More specifically, the transparent body 60 desirably has a parabola (quadratic curve) shape with respect to the reference surface of the substrate 58.

  Next, the manufacturing method of the transparent body 60 in the 2nd modification is demonstrated using FIG. First, for example, low-melting glass is poured into a lens mold, and a parabola rotating body glass lens having a hollow portion 61 is manufactured by mold molding. Next, a dispersion liquid in which phosphor particles are dispersed in liquid silicone is prepared and set in a syringe of a syringe. Further, after the base body 58 is inserted into the hollow portion 61 of the parabolic rotator, the void portion is filled with the phosphor particle dispersion with the syringe. Further, the phosphor light emitting portion 51 can be formed between the transparent body 60 and the base body 58 by performing baking at 150 ° C.

  With this configuration, the wavelength-converted light 78 emitted from the fluorescent light emitting unit 51 in all directions is refracted at the air interface with the transparent body 60 as shown in the side view of FIG. The emission angle of the wavelength converted light 78 can be reduced (FIG. 6B). Further, in the first modification, the radiation angle in the cross-sectional direction (FIG. 5A) cannot be made very small, but in this modification, as shown in FIG. Also, the radiation angle can be reduced, and the light can be collected more efficiently.

(Modification 3)
Next, a third modification of the light source conversion element according to the first embodiment will be described with reference to FIG. 8 shows an enlarged view of the vicinity of the fluorescent light emitting portion of FIG. 1, as in FIG. 5, and FIG. 8A is a cross-sectional view in a direction parallel to the rotation axis of the wavelength converting portion 50 (FIGS. 1 and 2). FIG. 8B shows a cross-sectional (side) view in a direction perpendicular to the rotation axis. As can be seen from a comparison between FIG. 8A and FIG. 5A, this modification is characterized in that an antireflection film 70 is provided on the transparent body 60 of the first modification. More specifically, the refractive index of the antireflective film 70 can be determined by assuming that the refractive index of the transparent body 60 is n.

Is preferred. The film thickness of the antireflection film 70 is

What should I do?

  By using the configuration of this modification as described above, it is possible to reduce the reflection loss when the excitation light 75 enters the transparent body 60, and further increase the intensity of the wavelength converted light 78 per excitation light power. It becomes possible.

  In this modification, the antireflection film 70 is provided on the transparent body 60, but the antireflection film 70 may be directly formed on the fluorescent light emitting portion 51 instead of the transparent body 60. In that case, the refractive index of the anti-reflective film 70 can be determined by assuming that the refractive index of the fluorescent light emitting portion 51 is n2.

Is preferred. The film thickness of the antireflection film 70 is such that the peak emission wavelength of the fluorescent light emitting portion 51 is λ _p .

What should I do?

  In the present modification, the antireflection film 70 has a single layer configuration, but may have a multilayer configuration.

(Modification 4)
Next, a fourth modification of the optical conversion element according to the first embodiment will be described with reference to FIG. The present modification is different from the first embodiment in the configuration of the wavelength conversion unit 50. For this reason, the difference between the two will be mainly described with reference to FIG.

  The wavelength conversion unit 50 of the present modification is characterized in that a cooling mechanism 66 is formed on a part of the base body 58 of the wavelength conversion unit 50 of the first embodiment.

  Specifically, in FIG. 9, cooling mechanisms (air cooling fins) are provided in the vicinity of the fluorescent light emitting portions 51R, 51G, and 51B.

  By using the configuration of this modification as described above, the heat generated in the fluorescent light emitting portions 51R, 51G, and 51B can be efficiently cooled, and the decrease in fluorescent intensity due to the temperature rise of the phosphor light emitting portion is suppressed. Is possible.

  In this modification, the number of cooling mechanisms is three, but the number may be changed depending on the degree of heat generation of the phosphor portion.

(Modification 5)
Then, the 5th modification of the light source which concerns on 1st Embodiment is demonstrated using FIG. This modification is different from the first embodiment in the configuration of the fluorescent light emitting unit and the excitation light source of the wavelength conversion unit 50. Therefore, with reference to FIG. 10, the description will focus on the differences between the two.

  The wavelength conversion unit 50 of the present modification differs from the first embodiment in the portions where the fluorescent light emitting units 51R, 51G, and 51B are formed on the substrate 58 and the number of optical axes for phosphor excitation. Is a feature.

  Specifically, as shown in FIG. 10, the fluorescent light emitting portions 51R, 51G, and 51B are formed by dividing the outer peripheral surface of the base body 58 along the direction perpendicular to the rotation axis, and the excitation light source has one optical axis. .

  By using the configuration of this modification as described above, the wavelength conversion unit 50 becomes more compact, and the number of optical axes can be reduced from 3 to 1, so that the light source component member can be greatly simplified and downsized. Energy saving can be realized.

  In the present modification, the fluorescent light emitting unit is formed in three divided parts using RGB phosphors, but a phosphor other than RGB, such as a yellow phosphor, may be added and a color source of three or more colors may be used.

(Modification 6)
Then, the 6th modification of the light source which concerns on 1st Embodiment is demonstrated using FIG. This modification is different from the first embodiment in the configuration of the fluorescent light emitting unit and the excitation light source of the wavelength conversion unit 50. Therefore, with reference to FIG. 11, the description will focus on the different parts.

  The wavelength conversion unit 50 according to the present modification is provided with a moving mechanism in a direction parallel to the first embodiment and the rotation shaft 56, and a portion where the fluorescent light emitting units 51R, 51G, and 51B are formed on the substrate 58. , And the number of optical axes for phosphor excitation is different.

  Specifically, as shown in FIG. 11, the fluorescent light emitting portions 51R, 51G, and 51B are formed adjacent to each other on the base 58, and the optical axis of the excitation light source is one.

  By using the configuration of this modified example as described above, the number of optical axes can be reduced from 3 to 1, so that the light source can be reduced in size and energy can be saved.

  In this modification, the three fluorescent light emitting units are RGB phosphors. However, a phosphor other than RGB, such as a yellow phosphor, may be added to use three or more color sources.

(Second Embodiment)
Hereinafter, the configurations and effects of the optical conversion element and the light source according to the second embodiment of the present invention and the modifications thereof will be described with reference to FIGS.

  FIG. 12 is a diagram showing a configuration of a light source according to the second embodiment of the present invention. FIG. 13 is a diagram for explaining the configuration of the light source according to the second embodiment of the present invention and the operation when emitting red fluorescent light, green fluorescent light, and blue laser diffused light.

  In FIG. 12 and FIG. 13, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

(Constitution)
In the light source according to the second embodiment of the present invention and the light source according to the first embodiment, the wavelength of the semiconductor light emitting element 10B is a blue wavelength of 430 nm to 470 nm, the third fluorescent light emitting unit 51B, The difference is that the condenser lens 40B is omitted. This is because the emitted light from the semiconductor light emitting device 10B is used as it is as a blue source.

  More specifically, the light source 1 of the present embodiment is configured as follows.

  In FIG. 12, first, the light source 1 includes, for example, semiconductor light emitting devices 10R and 10G, which are semiconductor lasers having a light output of 2 watts and a central wavelength of the emission wavelength in the range of 380 nm to 430 nm, and a central wavelength of the emission wavelength of 430 nm to 430 nm. For example, nine semiconductor light emitting elements 10B, which are semiconductor lasers in the range of 470 nm, are arranged (three in each of 10R, 10G, and 10B in FIGS. 12 to 13). The light emitted from the semiconductor light emitting elements 10R and 10G is condensed on the first fluorescent light emitting unit 51R and the second fluorescent light emitting unit 51G, respectively, in the same procedure as described in the first embodiment. The At this time, the main optical axis of the excitation light collected by the condensing lenses 40R and 40G is installed so as to enter perpendicularly to the rotation axis direction of the wavelength conversion unit 50. The light emitted from the semiconductor light emitting element 10B is converted into parallel light by the collimator lens 20, and is further guided to the dichroic mirror 30B via the first relay lens 25B that is a convex lens and the second relay lens 27B that is a concave lens. . Here, the dichroic mirror 30B is set so as to transmit light with a wavelength of 380 nm to 430 nm and reflect light with a wavelength of 430 to 800 nm, for example. Therefore, the blue laser light emitted from the semiconductor light emitting element 10B and converted into parallel light is reflected by the dichroic mirror 30B, and then superimposed on the red and green wavelength converted light to become time-division RGB light 100.

(Operation)
Next, the operation of the light source 1 according to the present embodiment will be described using an image projection apparatus 199 including the light source 1 shown in FIG. Constituent members of the image projection apparatus 199 in the present embodiment are given the same reference numerals as those in the first embodiment, and detailed description thereof is omitted.

  The light source 1 of the present embodiment includes a so-called red wavelength converted light 78R having a main emission wavelength in the range of 590 to 660 nm, a so-called green wavelength converted light 78G having a main emission wavelength in the range of 500 to 590 nm, A blue laser beam 79 having a light emission wavelength in the range of 430 to 470 nm emits time-division RGB light 100 that is continuous in time. That is, the time-division RGB light 100 is white light formed by periodically emitting red light, green light, and blue light, which are light of the three primary colors, in the order of red → green → blue → red. Is, for example, about 8.3 ms (120 Hz) during double-speed scanning.

Next, the operation of the light source 1 will be described. For example, the excitation light 75R having a central wavelength of 405 nm and a total light amount of 18 watts emitted from the plurality of semiconductor light emitting elements 10R becomes a single light beam by the collimating lens 20, the first relay lens 25R, and the second relay lens 27R, and passes through the dichroic mirror 30R. The light passes through and is condensed to an area of, for example, 1 mm ² or less by the condensing lens 40R on the first fluorescent light emitting unit 51R. Similarly, the excitation light emitted from the semiconductor light emitting element 10G is condensed on the second fluorescent light emitting unit 51G. The condensed excitation light is converted from light having a central wavelength of 405 nm into wavelength converted light 78R having a main emission wavelength of 590 nm to 660 nm by the red phosphor included in the first fluorescent light emitting member 51R, and the condensing lens 40R. Radiated to the side. At this time, the radiation angle of the wavelength converted light 78R is omnidirectional so-called Lambertian light. However, since the light emitting area is a point light source of 1 mm ² or less, it becomes almost parallel light by the condenser lens 40R and travels toward the dichroic mirror 30R. The wavelength converted light 78R is reflected by the dichroic mirror 30R and travels toward the third relay lens 41. Similarly, the green phosphor contained in the second fluorescent light emitting portion 51G converts the central wavelength from 405 nm to wavelength converted light 78G having a main light emission wavelength of 500 to 590 nm and guides it to the third relay lens 41.

  Further, the wavelength-converted lights 78R and 78G and the blue laser light 79 are superimposed to form a time-division RGB light 100, which is condensed and incident on the end of the rod lens 42 by the third relay lens 41. Then, the time-division RGB light 100 multiple-reflected in the rod lens 42 is radiated after the light intensity distribution of the wavefront is converted into a rectangle, and becomes straight light by the fourth relay lens 43. The light is guided to a reflective image display element 71 such as a DMD. The light irradiated to the image display element 71 is reflected as signal light 80 on which a two-dimensional video signal is superimposed, and becomes image light 89 that can be projected onto a predetermined screen (not shown) by the projection lens 65. 199.

(effect)
As described above, according to the present invention, by using the semiconductor light emitting element as the excitation light source, the excitation light source can be turned on / off at a high speed on a time scale on the order of nanoseconds, and double-speed scanning (120 Hz, period 8. Even at a speed of 3 ms) or more, the RGB three primary colors can be generated in a time division manner without any problem. Further, when a function equivalent to that of the present invention is realized by using a conventional color wheel, three color wheels are required, and the light source size becomes significantly larger than that of the present invention.

  With this configuration, the RGB three primary colors can be generated in a time-sharing manner with high efficiency and high speed with a compact configuration without increasing the number of components, and thus a high-performance light source without color breakup can be provided.

In the above-described configuration, the above-described phosphor is used as the phosphor, but the present invention is not limited to this. For example, Eu activated β-type SiAlON phosphor, Eu activated SrSiO ₃ phosphor, Eu activated SrSi ₂ O ₂ N ₂ phosphor, Eu activated Ba ₃ Si ₈ O ₁₂ N ₂ phosphor, Ce activated CaSc _{2 as} green phosphor. A phosphor in which Ce or Eu is activated, such as an O ₄ phosphor, can be used. The red phosphor is not limited to Eu, Sm activated La ₂ W ₃ O ₁₂ . For example, one or more of silicon oxide, tungsten oxide, molybdenum oxide, indium oxide, yttrium oxide, zinc oxide, silicon nitride, silicon oxynitride, aluminum oxynitride, and organic polymer are included in the constituent elements of the base material Any phosphor may be used as long as the base material contains a lanthanoid ion element or a metal ion element as an activator. Specifically, Eu activated La ₂ O ₂ S phosphor, Eu activated LiW ₂ O ₈ phosphor, Eu and Sm activated LiW ₂ O ₈ phosphor, Eu and Mn activated (Sr, Ba) ₃ MgSi ₂ O ₈ fluorescence Fluorescence lifetime of phosphors such as phosphors, Mn activated 3.5MgO · 0.5MgF ₂ · GeO ₂ phosphor, Eu activated YVO ₄ phosphor, Eu activated Y ₂ O ₃ phosphor, Eu activated Y ₂ O ₂ S phosphor This embodiment is effective for a red phosphor that is long but has a narrow half-width of the fluorescence spectrum. Moreover, the rare earth complex fluorescent substance which used the lanthanoid ion element and the metal ion element as an activation material may be sufficient. Specifically, a rare earth complex phosphor having a molecular structure in which two types of phosphine oxides are coordinated to trivalent europium.

  In the present embodiment, a semiconductor laser having a central wavelength of 405 nm is given as an example of the semiconductor light emitting device, but this is not restrictive. For example, the center wavelength can be adjusted in the range of 380 nm to 430 nm according to the absorption spectrum of the phosphor, such as the center wavelengths of 395 nm, 400 nm, and 410 nm, or a combination of a plurality of semiconductor lasers having different center wavelengths in the range of 2 nm to 10 nm. The spectrum width may be widened.

  According to the present invention, in a light source that emits light emitted from a semiconductor laser by converting it into fluorescence with a plurality of phosphors, a light source with high conversion efficiency and high color reproducibility is provided without increasing the number of components. Therefore, it can be widely used not only for display illumination such as a projector, rear projection television, and head-up display, but also for in-vehicle illumination such as a headlight or medical illumination such as an endoscope.

DESCRIPTION OF SYMBOLS 1 Light source 10R, 10G, 10B Semiconductor light-emitting device 20 Collimating lens 25R, 25G, 25B 1st relay lens 27R, 27G, 27B 2nd relay lens 30R, 30G, 30B Dichroic mirror 40R, 40G, 40B Condensing lens 41 1st 3 relay lens 42 rod lens 43 fourth relay lens 45 reflection mirror 50 wavelength conversion unit 51R first fluorescent light emitting unit 51G second fluorescent light emitting unit 51B third fluorescent light emitting unit 55 rotating mechanism 56 rotating shaft 57 auxiliary rotation Shaft 58 Base 59 Bearing 60 Transparent body 61 Hollow portion 65 Projection lens 70 Antireflection film 71 Image display element 75R, 75G, 75B Excitation light 78, 78R, 78G, 78B Wavelength converted light 79 Blue laser light 80 Signal light 89 Video light 90 Heat sink 95 fan 100 Pixel RGB light 199 image projection apparatus

Claims (7)

An optical conversion element in which at least one phosphor-containing layer is provided on a surface of a uniaxial rotating substrate, wherein the phosphor-containing layer is formed concentrically with respect to a rotation axis of the uniaxial rotating substrate. An optical conversion element characterized by that. The optical conversion element according to claim 1, wherein a transparent body is laminated on the phosphor-containing layer. The rotary substrate is a columnar heat conductor, and includes a rotation drive mechanism having the columnar heat conductor as a rotation axis, and a cooling mechanism on a part of the surface of the columnar conductor. 3. The optical conversion element according to 1 or 2. 4. The optical conversion element according to claim 1, further comprising an antireflection film having a wavelength region of 380 nm to 700 nm on the outermost surface of the rotating base. 5. The optical conversion element according to any one of claims 1 to 4, further comprising a moving mechanism in a direction parallel to the rotation axis of the rotating base. 6. A light source comprising: the optical conversion element according to claim 1; and an excitation light source that emits excitation light, wherein the excitation light is incident from a direction perpendicular to the rotation axis of the phosphor-containing layer. The light source according to claim 6, further comprising a dichroic mirror and a condenser lens between the excitation light source and the optical conversion element.

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