JP5759198B2 - Light emitting device, light source device and projector - Google Patents

Description

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

  Laser light sources are attracting attention as light sources for projectors. For example, the light source device of Patent Document 1 includes a light source that emits excitation light, and a phosphor layer that emits fluorescence in response to excitation light emitted from the light source.

JP 2010-165834 A

  Fluorescence emitted from the phosphor layer is emitted in all directions (emitted from the upper and bottom surfaces and side surfaces of the frustum-shaped translucent member). In order to reduce the emission area (emission area) of fluorescence and reduce the etendue, it is necessary to reduce the emission area by condensing excitation light on the phosphor layer. However, if the excitation light is condensed on a minute region of the phosphor layer, a light saturation phenomenon may occur or the phosphor may become high temperature, which may reduce the light emission efficiency.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the light emitting element and light source device which can raise light utilization efficiency, suppressing the fall of luminous efficiency. It is another object of the present invention to provide a projector having such a light source device and excellent in display quality.

In order to solve the above problems, a light-emitting element according to one embodiment of the present invention includes a medium having a plurality of surfaces including a light incident surface and a light exit surface, and excitation light incident on the light incident surface. A phosphor that emits fluorescence from a light exit surface, and the surface that is different from the light incident surface and the light exit surface among the plurality of surfaces reflects the fluorescence emitted from the phosphor. A reflecting surface for guiding to the light exit surface is provided, and an area of the light exit surface is smaller than an area of the light entrance surface, and the excitation light is transmitted to the light entrance surface to transmit the fluorescence. A wavelength selective reflection film for reflection is disposed, and the medium has a frustum shape having the light incident surface as a side surface, the light exit surface as an upper bottom surface, and the reflection surface as a lower bottom surface, The upper bottom surface transmits both the excitation light and the fluorescence, and also functions as the light incident surface. It is characterized in.
In order to solve the above problems, a light-emitting element according to one embodiment of the present invention includes a medium having a plurality of surfaces including a light incident surface and a light exit surface, and excitation light incident on the light incident surface. A phosphor that emits fluorescence from a light exit surface, and the surface that is different from the light incident surface and the light exit surface among the plurality of surfaces reflects the fluorescence emitted from the phosphor. A reflecting surface for guiding to the light exit surface is provided, and an area of the light exit surface is smaller than an area of the light entrance surface, and the excitation light is transmitted to the light entrance surface to transmit the fluorescence. A reflective wavelength selective reflection film is disposed, and the medium has a triangular prism shape in which the light incident surface is a first side surface, the light emission surface is a second side surface, and the reflection surface is a third side surface. It is characterized by having.
In order to solve the above-described problems, a light-emitting element of the present invention receives a medium having a plurality of surfaces including a light incident surface and a light exit surface, and excitation light incident on the light entrance surface from the light exit surface. A phosphor that emits fluorescence, and the light exit surface reflects the fluorescence emitted from the phosphor on a surface different from the light incident surface and the light exit surface among the plurality of surfaces. And a light emitting surface having a smaller area than the light incident surface.

  In the configuration of Patent Document 1, fluorescence is emitted from the entire portion where excitation light is incident on the phosphor layer. Therefore, the area of the light incident surface on which the excitation light is incident on the phosphor layer and the light emitting surface from which the light is emitted from the phosphor layer are equal. Therefore, in order to reduce the light emission area (area of the light exit surface), it is necessary to collect the excitation light and reduce the area of the light incident surface. On the other hand, in the configuration of the present invention, the light emitted from the phosphor is reflected by the reflecting surface and guided to the light emitting surface having a smaller area than the light incident surface. By increasing the area, the density of light incident on the phosphor can be reduced. Therefore, etendue can be reduced and light utilization efficiency can be increased while suppressing a decrease in light emission efficiency.

  In the light emitting element, a wavelength selective reflection film that transmits the excitation light and reflects the fluorescence may be disposed on the light incident surface.

  According to this light emitting element, it is possible to reflect the fluorescence reflected by the reflecting surface and directed toward the light incident surface to the light emitting surface side. Therefore, the amount of light extracted as fluorescence can be increased.

  In the light emitting device, the phosphor may be dispersed in the medium as phosphor particles.

  According to this light emitting element, it is possible to make the excitation light uniformly enter each phosphor particle as compared with the case where the phosphor is biased inside the medium.

  In the light emitting element, a light transmissive member that transmits the excitation light is disposed in contact with a surface of the wavelength selective reflection film that is opposite to the surface facing the medium, and a thermal conductivity of the light transmissive member. May be larger than the thermal conductivity of the wavelength selective reflection film.

  According to this light emitting element, even when the phosphor generates heat upon receiving the excitation light incident on the light incident surface, the heat generated by the phosphor is radiated to the outside through the medium, the wavelength selective reflection film, and the light transmitting member. The Therefore, it can suppress that fluorescent substance becomes high temperature, and can suppress the fall of luminous efficiency.

  In the light emitting element, an area of a cross section of the medium orthogonal to an incident optical axis of the excitation light may gradually decrease as the distance from the light incident surface increases.

  According to this light emitting element, the fluorescence emitted from the phosphor is easily guided to the light exit surface through the reflecting surface.

  In the light-emitting element, the medium may have a frustum shape having the light incident surface as a lower bottom surface, the light emission surface as an upper bottom surface, and the reflection surface as a side surface.

  According to this light emitting element, the fluorescence emitted from the phosphor is easily guided to the light exit surface through the reflecting surface.

  In the light emitting element, a holding member that holds the medium may be disposed on the reflection surface.

  According to this light emitting element, even when the medium is made of a soft material (resin or the like), the medium can be held so that the medium is not deformed.

  In the light emitting element, a surface of the holding member on the medium side may be the reflective surface.

  According to this light emitting element, there is no need to deposit a reflective film or the like on the side surface of the medium. Therefore, the manufacturing process can be simplified.

  In the light emitting element, the heat conductivity of the holding member may be larger than the heat conductivity of the medium.

  According to this light emitting element, even when the phosphor generates heat upon receiving excitation light incident on the light incident surface, the heat generated by the phosphor is radiated to the outside through the medium and the holding member. Therefore, it can suppress that fluorescent substance becomes high temperature, and can suppress the fall of luminous efficiency.

  In the light emitting device, the medium has a frustum shape having the light incident surface as a side surface, the light emitting surface as an upper bottom surface, and the reflecting surface as a lower bottom surface, and the upper bottom surface includes the excitation light. And both the fluorescent light and the light incident surface.

  According to this light emitting element, a reflective light emitting element can be realized.

  In the light emitting device, the medium may have a triangular prism shape in which the light incident surface is a first side surface, the light emission surface is a second side surface, and the reflection surface is a third side surface.

  According to this light emitting element, light can be extracted in a desired direction by freely adjusting the angle of each apex angle of the triangle. Therefore, the freedom degree of the arrangement design of an optical member increases.

  In the light emitting device, the medium has a quadrangular prism shape in which the light incident surface is a first side surface, the light emission surface is a second side surface, and the reflection surface is a third side surface and a fourth side surface. You may do it.

  According to this light emitting element, light can be extracted in a desired direction by freely adjusting the angle of each apex angle of the quadrangle. Therefore, the freedom degree of the arrangement design of an optical member increases.

  In the light emitting device, the medium may be glass.

  According to this light emitting element, since the medium has high heat resistance, the medium is not easily deteriorated by the heat of light incident on the light incident surface. Thus, reliability can be improved.

  The light source device of the present invention includes the light emitting element described above and an excitation light source that causes the excitation light to enter the light incident surface of the light emitting element.

  According to this light source device, since the light emitting element described above is provided, it is possible to provide a light source device capable of increasing the light utilization efficiency while suppressing a decrease in the light emission efficiency.

  The projector according to the present invention includes the light source device described above, a light modulation device that modulates light emitted from the light source device according to image information, and a projection optical system that projects the modulated light from the light modulation device as a projection image. And.

  According to this projector, since the light source device described above is provided, a projector having excellent display quality can be provided.

It is a schematic diagram which shows the optical system of the projector which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the light emitting element which concerns on 1st Embodiment of this invention. It is a figure which shows the manufacturing process of the light emitting element which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the optical system of the projector which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the light emitting element which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the 1st modification of a light emitting element. It is a schematic diagram which shows the 2nd modification of a light emitting element. It is a schematic diagram which shows the 3rd modification of a light emitting element. It is a schematic diagram which shows the 4th modification of a light emitting element.

  Embodiments of the present invention will be described below with reference to the drawings. Such an embodiment shows one aspect of the present invention, and is not intended to limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, an actual structure and a scale, a number, and the like in each structure are different.

  In the following description, the XYZ rectangular coordinate system shown in FIG. 1 is set, and each member will be described with reference to this XYZ rectangular coordinate system.

(First embodiment)
FIG. 1 is a schematic diagram showing an optical system of a projector 1000 according to the first embodiment of the present invention. In FIG. 1, reference numeral 100ax denotes an illumination optical axis (the optical axis of light emitted from the light source device 100 toward the color separation light guide optical system 200). The optical axis refers to a virtual light beam that is representative of a light beam that passes through the entire system in the optical system. A direction parallel to the illumination optical axis is taken as a Y axis.

  As shown in FIG. 1, the projector 1000 includes a light source device 100, a color separation light guide optical system 200, a liquid crystal light modulation device 400R, a liquid crystal light modulation device 400G, and a liquid crystal light modulation device 400B as a light modulation device, A dichroic prism 500 and a projection optical system 600 are provided.

  The light source device 100 has a configuration in which an excitation light source 30, a condensing optical system 40, a light emitting element 1, a collimating optical system 60, an integrator optical system 110, a polarization conversion element 120, and a superimposing lens 130 are arranged in this order.

  The excitation light source 30 emits blue (emission intensity peak: about 445 nm) laser light as excitation light that excites a fluorescent substance included in the light-emitting element 1 described later. It should be noted that a plurality of excitation light sources 30 (three in the figure) may be provided, or only one excitation light source may be used. Moreover, as long as it is the light of the wavelength which can excite the fluorescent substance mentioned later, you may be an excitation light source which inject | emits the color light which has a peak wavelength other than 445 nm.

  The condensing optical system 40 includes a first lens 42 that is a plurality of convex lenses, and a second lens 44 that is a convex lens through which light that has passed through the plurality of first lenses 42 is incident in common. The condensing optical system 40 is disposed on the beam axis of the laser light emitted from the excitation light source 30 and condenses the excitation light emitted from the plurality of excitation light sources 30.

  The light emitting element 1 transmits a part of the excitation light (blue light) Lb emitted from the excitation light source 30 and absorbs the remaining part to emit yellow (peak of emission intensity: about 550 nm) fluorescence (red light and green light). Including light).

  FIG. 2 is a cross-sectional view showing the light emitting device 1 according to the first embodiment of the present invention. FIG. 2 shows a cross section of the medium 10 cut along a plane (XY plane) parallel to the direction in which the excitation light is incident (Y-axis direction).

  As shown in FIG. 2, the light emitting element 1 includes a medium 10, a phosphor 11, a reflection film 12, a wavelength selection reflection film 13, antireflection films 14 and 16, and a light transmission member 15. Yes.

  The medium 10 has a plurality of surfaces including a light incident surface 10f1 and a light emitting surface 10f2. The light incident surface 10f1 is a surface on which light collected by the condensing optical system 40 is incident, and the light emitting surface 10f2 is a surface that emits light (fluorescence). The light incident surface 10f1 transmits excitation light, and the light emission surface 10f2 transmits fluorescence emitted from the phosphor 11. A reflective surface 12fr is provided on the side surface 10f3 (a surface different from the light incident surface 10f1 and the light emitting surface 10f2 among the plurality of surfaces). The area of the light emitting surface 10f2 is smaller than the area of the light incident surface 10f1.

  In addition, the light condensed by the condensing optical system 40 is incident on the entire surface of the light incident surface 10f1 (the area where the light condensed by the condensing optical system 40 is incident on the light incident surface 10f1 is light incident) It is equal to the area of the surface 10f1).

  The area of the cross section of the medium 10 orthogonal to the incident optical axis (Y axis) of the excitation light gradually decreases as the distance from the light incident surface 10f1 increases. Specifically, the medium 10 has a frustum shape in which the light incident surface 10f1 is a lower bottom surface, the light emission surface 10f2 is an upper bottom surface, and a reflective surface 12fr (a surface on which the reflective film 12 is in contact with the medium 10). The medium 10 has a quadrangular frustum shape. For example, the size of the light incident surface 10f1 (lower bottom surface) is 2 mm long × 2 mm wide, and the size of the light emitting surface 10f2 (upper bottom surface) is 1 mm long × 1 mm wide. It has become.

  As the medium 10, a wide variety of materials such as a resin material and an inorganic material can be used as long as they are light-transmitting substances. Especially, the inorganic material which has high heat resistance can be used suitably. In the present embodiment, an inorganic glass is used as the medium 10.

  The phosphor 11 is dispersed inside the medium 10 as phosphor particles. The phosphor 11 receives the excitation light incident on the light incident surface 10f1 and emits fluorescence. The phosphor 11 is excited by the blue light incident on the light incident surface 10f1, converts the blue light into yellow light, and radiates it.

Specifically, the phosphor 11 converts blue light from the excitation light source 30 into yellow light and emits it. The phosphor 11 is efficiently excited by blue light having a wavelength of about 445 nm, converted into yellow light (fluorescence), and emitted. As the phosphor particles, for example, YAG (yttrium / aluminum / garnet) phosphors can be used. For example, a YAG phosphor having a composition represented by (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce having an average particle diameter of 10 μm (refractive index: about 1.8) can be used.

The phosphor particle forming material may be one kind, or a mixture of particles formed using two or more kinds of forming materials may be used as the phosphor particles. For example, a material such as a phosphor having a composition represented by (Sr, Ca) AlSiN ₃ : Eu that emits red fluorescence, and a phosphor having a composition represented by (YGd) ₃ Al ₅ O ₁₂ : Ce that emits green fluorescence. It is also possible to adjust phosphor particles from which yellow light fluorescence can be obtained by mixing and using such materials.

  Here, the average particle diameter of the phosphor particles can be measured using a particle size distribution measuring apparatus (for example, SALD2200 (manufactured by Shimadzu Corporation)) based on the laser diffraction scattering method. In this embodiment, the median particle size (Median Size: median of particle size distribution) is adopted as the average particle size.

  The reflective film 12 is provided on the side surface 10f3 of the medium 10 (a surface different from the light incident surface 10f1 and the light incident surface 10f1 among the plurality of surfaces). The reflection film 12 has a reflection surface 12fr that reflects the fluorescence emitted from the phosphor 11 and guides it to the light exit surface 10f2. As a material for forming the reflective film 12, for example, aluminum (Al) can be used.

  The wavelength selective reflection film 13 is provided on the light incident surface 10 f 1 of the medium 10. The wavelength selective reflection film 13 transmits the light (excitation light) collected by the condensing optical system 40 and reflects the fluorescence emitted from the phosphor 11.

  The antireflection film 14 is provided on the light exit surface 10 f 2 of the medium 10. Thereby, reflection of fluorescence emitted from the medium 10 can be suppressed. When only the fluorescence is taken out, a wavelength selective reflection film that transmits the fluorescence and reflects the excitation light may be provided instead of the antireflection film 14.

  The light transmitting member 15 is disposed in contact with the outer surface of the wavelength selective reflection film 13 (on the side opposite to the surface facing the medium 10). The light transmissive member 15 transmits excitation light. Further, the thermal conductivity of the light transmitting member 15 is larger than the thermal conductivity of the wavelength selective reflection film 13. As a material for forming the light transmitting member 15, for example, sapphire can be used.

  The antireflection film 16 is provided on the outer surface of the light transmission member 15 (on the side opposite to the surface facing the wavelength selective reflection film 13). Thereby, reflection of the excitation light incident on the light transmission member 15 can be suppressed.

(Manufacturing method of light emitting element)
FIG. 3 is a diagram showing a manufacturing process of the light emitting device according to the first embodiment of the present invention.
First, as shown in FIG. 3A, a member having a frustum shape (such as a square frustum) in which phosphors 11 (a plurality of phosphor particles) are dispersed inside a light-transmitting medium 10 is used. prepare.

  Next, as shown in FIG. 3B, the reflective film 12 is formed on the side surface 10f3 of the medium 10 by, for example, vapor deposition.

  Next, as shown in FIG. 3C, a light transmission member 15 on which the wavelength selective reflection film 13 is formed is prepared, and the medium 10 is placed so that the light incident surface 10 f 1 is in contact with the upper surface of the wavelength selective reflection film 13. It is attached to the light transmission member 15. When sapphire is used as the light transmission member 15 as in the present embodiment, the wavelength selective reflection film 13 may be formed on the upper surface (light emission surface) of the light transmission member 15 by a known thin film forming method.

  Next, as shown in FIG. 3D, an antireflection film 14 is formed on the light exit surface 10 f 2 of the medium 10. Similarly, an antireflection film 16 is formed on the lower surface (light incident surface) of the light transmitting member 15. Before attaching the medium 10 to the light transmission member 15, the antireflection film 14 is formed on the light emitting surface 10 f 2 of the medium 10, or the antireflection film 16 is formed on the lower surface (light incident surface) of the light transmission member 15. May be.

  Through the above steps, the light emitting device 1 according to the first embodiment of the present invention is obtained.

  Returning to FIG. 1, the collimating optical system 60 is disposed on the optical path of light (excitation light and fluorescence) between the light emitting element 1 and the integrator optical system 110. The collimating optical system 60 includes a first lens 62 that suppresses the spread of light from the light emitting element 1 and a second lens 64 that substantially collimates the light incident from the first lens 62. The first lens 62 and the second lens 64 are configured as convex lenses. The collimating optical system 60 makes the light emitted from the light emitting element 1 enter the integrator optical system 110 in a substantially parallel state.

  The integrator optical system 110 includes a first fly eye lens 111 and a second fly eye lens 112. The first fly-eye lens 111 and the second fly-eye lens 112 are each composed of a plurality of element lenses arranged in a matrix. The first fly-eye lens 111 has a function of dividing the light from the collimating optical system 60 by a plurality of element lenses constituting the first fly-eye lens 111 and condensing them individually. The second fly-eye lens 112 has a function of emitting the divided light flux from the first fly-eye lens 111 with an appropriate divergence angle by a plurality of element lenses constituting the second fly-eye lens 112. The integrator optical system 110 uniformizes the light intensity distribution of the light synthesized by the collimating optical system 60.

  The polarization conversion element 120 is formed of an array having a PBS, a mirror, a retardation plate, etc. as a set of elements. The polarization conversion element 120 has a function of aligning the polarization direction of each partial light beam divided by the first fly-eye lens 111 with linear polarization in one direction.

  The superimposing lens 130 appropriately converges the illumination light that has passed through the polarization conversion element 120 as a whole, and enables superimposing illumination on the illuminated areas of the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B.

  The color separation light guide optical system 200 includes a dichroic mirror 210, a dichroic mirror 220, a reflection mirror 230, a reflection mirror 240, a reflection mirror 250, a relay lens 260, and a relay lens 270. The color separation light guide optical system 200 separates the light (first light, second light, and third light) from the light source device 100 into red light, green light, and blue light, and red light, green light, and It has a function of guiding each color light of blue light to the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B to be illuminated. A condensing lens 300R, a condensing lens 300G, and a condensing lens 300B are disposed between the color separation light guide optical system 200 and the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B. Yes.

  The dichroic mirror 210 and the dichroic mirror 220 are mirrors in which a wavelength selective transmission film that reflects light in a predetermined wavelength region and transmits light in another wavelength region is formed on a substrate. Specifically, the dichroic mirror 210 transmits a red light component and reflects a green light component and a blue light component. The dichroic mirror 220 reflects the green light component and transmits the blue light component.

  The reflection mirror 230, the reflection mirror 240, and the reflection mirror 250 are mirrors that reflect incident light. Specifically, the reflection mirror 230 reflects the red light component transmitted through the dichroic mirror 210. The reflection mirror 240 and the reflection mirror 250 reflect the blue light component transmitted through the dichroic mirror 220.

  The red light transmitted through the dichroic mirror 210 is reflected by the reflection mirror 230, passes through the condenser lens 300R, and enters the image forming region of the liquid crystal light modulation device 400R for red light. The green light reflected by the dichroic mirror 210 is further reflected by the dichroic mirror 220, passes through the condenser lens 300G, and enters the image forming area of the liquid crystal light modulation device 400G for green light. The blue light transmitted through the dichroic mirror 220 passes through the relay lens 260, the incident-side reflecting mirror 240, the relay lens 270, the exit-side reflecting mirror 250, and the condensing lens 300B, thereby forming an image of the liquid crystal light modulation device 400B for blue light. Incident into the area.

  The relay lens 260, the relay lens 270, the reflection mirror 240, and the reflection mirror 250 have a function of guiding the blue light component transmitted through the dichroic mirror 220 to the liquid crystal light modulation device 400B. Thereby, even when the length of the optical path of blue light is longer than the length of the optical path of the other color light, it is possible to suppress a decrease in utilization efficiency of the blue light due to the divergence of the blue light. When the length of the optical path of other color light (for example, red light) is longer than the length of the optical path of blue light, the relay lens 260, the relay lens 270, the reflection mirror 240, and the reflection mirror 250 are arranged in the optical path of red light. It is also possible to use a configuration that does this.

  The liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B form a color image by modulating incident color light according to image information, and are lighted by the light source device 100. Although not shown, between the condenser lens 300R, the condenser lens 300G, and the condenser lens 300B and each of the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B, there is an incident side. A polarizing plate is disposed. In addition, an exit-side polarizing plate is disposed between each liquid crystal light modulation device 400R, liquid crystal light modulation device 400G, liquid crystal light modulation device 400B, and cross dichroic prism 500. The incident-side polarizing plate, the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, the liquid crystal light modulation device 400B, and the emission side polarizing plate modulate light of each incident color light.

  For example, the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B are transmissive liquid crystal light modulation devices in which liquid crystal is hermetically sealed in a pair of transparent substrates, and are provided with polysilicon TFTs as switching elements. In accordance with the received image signal, the deflection direction of one type of linearly polarized light emitted from the incident side polarizing plate (not shown) is modulated.

  The cross dichroic prism 500 is an optical element that forms a color image by synthesizing an optical image modulated for each color light emitted from an exit side polarizing plate (not shown). The cross dichroic prism 500 has a substantially square shape in plan view in which four right-angle prisms are bonded. A dielectric multilayer film is formed on the substantially X-shaped interface to which the right-angle prism is bonded. The dielectric multilayer film formed at one of the substantially X-shaped interfaces reflects red light, and the dielectric multilayer film formed at the other interface reflects blue light. By these dielectric multilayer films, the red light and the blue light are bent and aligned with the traveling direction of the green light, so that the three color lights are synthesized.

  The color image emitted from the cross dichroic prism 500 is enlarged and projected by the projection optical system 600 to form an image on the screen SCR.

  According to the light emitting device 1 of the present embodiment, the light emitted from the phosphor 11 is reflected by the reflecting surface 12fr and guided to the light emitting surface 10f2 having a smaller area than the light incident surface 10f1, so that the excitation light is incident. The density of the light incident on the phosphor 11 can be reduced by increasing the area of the light incident surface 10f1. Therefore, etendue can be reduced and light utilization efficiency can be increased while suppressing a decrease in light emission efficiency.

  Further, according to this configuration, since the wavelength selective reflection film 13 is disposed on the light incident surface 10f1, the fluorescence reflected by the reflective surface 12fr and directed toward the light incident surface 10f1 can be reflected to the light emitting surface 10f2 side. it can. Therefore, the amount of light extracted as fluorescence can be increased.

  Further, according to this configuration, since the phosphor 11 is dispersed inside the medium 10 as phosphor particles, the excitation light is emitted from each fluorescence as compared with the case where the phosphor is biased inside the medium. It can be uniformly incident on the body particles.

  Further, according to this configuration, even when the phosphor 11 generates heat upon receiving the excitation light incident on the light incident surface 10f1, the heat generated by the phosphor 11 is generated by the medium 10, the wavelength selective reflection film 13, and the light transmission member 15. The heat is radiated to the outside via Therefore, it can suppress that the fluorescent substance 11 becomes high temperature, and can suppress the fall of luminous efficiency.

  Further, according to this configuration, the area of the cross section of the medium 10 orthogonal to the incident optical axis of the excitation light gradually decreases as the distance from the light incident surface 10f1 increases. Therefore, the fluorescence emitted from the phosphor 11 is easily guided to the light exit surface 10f2 through the reflection surface 12fr.

  Further, according to this configuration, the medium 10 has a quadrangular pyramid shape. Therefore, the fluorescence emitted from the phosphor 11 is easily guided to the light exit surface 10f2 through the reflection surface 12fr.

  Further, according to this configuration, since the medium 10 is glass and has high heat resistance, the medium 10 is hardly deteriorated by the heat of light incident on the light incident surface 10f1. Thus, reliability can be improved.

  According to the light source device 100 of the present embodiment, since the light emitting element 1 described above is provided, it is possible to provide the light source device 100 that can increase the light use efficiency while suppressing the decrease in the light emission efficiency.

  According to the projector 1000 of this embodiment, since the light source device 100 described above is provided, it is possible to provide the projector 1000 with excellent display quality.

  In the light source device 100 of the present embodiment, convex lenses are used as the first lens and the second lens in the collimating optical system, but the present invention is not limited to this. In short, it is sufficient that the collimating optical system is made to enter the integrator optical system in a state where the light emitted from the light emitting element is substantially parallelized. Further, the number of lenses constituting the collimating optical system may be one, or may be three or more.

  In the projector 1000 of this embodiment, three liquid crystal light modulation devices are used as the liquid crystal light modulation device, but the present invention is not limited to this. The present invention can also be applied to a projector using one, two, four or more liquid crystal light modulation devices.

  In the projector 1000 of the present embodiment, a transmissive projector is used, but the present invention is not limited to this. For example, a reflective projector may be used. Here, “transmission type” means that the light modulation device as the light modulation means is a type that transmits light, such as a transmission type liquid crystal display device. The “reflective type” means that a light modulation device as a light modulation unit, such as a reflection type liquid crystal display device, reflects light. Even when the present invention is applied to a reflective projector, the same effect as that of a transmissive projector can be obtained.

  In the projector 1000 of the present embodiment, the liquid crystal light modulation device is used as the light modulation device, but the present invention is not limited to this. For example, DMD (Digital Micromirror Device: registered trademark of TI) may be used.

(Second Embodiment)
FIG. 4 is a schematic diagram showing an optical system of a projector 2000 according to the second embodiment of the invention corresponding to FIG. In FIG. 4, reference numeral 101ax denotes an illumination optical axis (optical axis of light emitted from the light source device 101 toward the color separation light guide optical system 201), and reference numeral 700ax denotes an illumination optical axis (color separation guide from the light source device 700). This is the optical axis of light emitted toward the optical optical system 201).

  As shown in FIG. 4, the projector 2000 according to the present embodiment includes a light source device 101 instead of the light source device 100 described above, a point further including a light source device 700, and the color separation light guiding optics described above. The projector 200 is different from the projector 2000 according to the first embodiment in that a color separation light guide optical system 201 is provided instead of the system 200. That is, the projector 2000 according to the present embodiment is configured such that the light source device 101 emits light (yellow light) including red light and green light as illumination light, and the light source device 700 emits blue light. Since the other points are the same as the above-described configuration, the same elements as those in FIG.

  As shown in FIG. 4, the projector 1000 includes a light source device 101, a light source device 700, a color separation light guide optical system 201, three liquid crystal light modulation devices 400R as light modulation devices, a liquid crystal light modulation device 400G, and a liquid crystal. The light modulation device 400B, the cross dichroic prism 500, and the projection optical system 600 are provided.

  The light source device 101 includes an excitation light source 30, a collimating optical system 70, a dichroic mirror 50, a collimating condensing optical system 80, a light emitting element 2, a collimating optical system 60, an integrator optical system 110, and a polarization conversion element 120. And a superimposing lens 130.

  The excitation light source 30 is disposed so that the optical axis is orthogonal to the illumination optical axis 101ax. As excitation light for exciting a fluorescent material included in the light-emitting element 2 to be described later, blue (emission intensity peak: about 445 nm) laser light is emitted.

  The collimating optical system 70 is disposed on the optical path of the excitation light between the excitation light source 30 and the dichroic mirror 50. The collimating optical system 70 includes a first lens 72 and a second lens 74. The first lens 72 and the second lens 74 are convex lenses. The collimating optical system 70 makes the excitation light enter the dichroic mirror 50 in a substantially parallel state.

  The dichroic mirror 50 is on the optical path between the collimating optical system 70 and the light emitting element 2 (collimating condensing optical system 80) at an angle of 45 ° with respect to each of the optical axis of the excitation light source 30 and the illumination optical axis 101ax. It is arranged to cross. The dichroic mirror 50 transmits blue light and reflects red light and green light.

  The collimator condensing optical system 80 includes a first lens 82 and a second lens 84. The first lens 82 and the second lens 84 are convex lenses. The collimating condensing optical system 80 causes the blue light from the dichroic mirror 50 to be incident on the light emitting element 2 in a substantially condensed state, and the fluorescence emitted from the light emitting element 2 is incident on the dichroic mirror 50 in a substantially parallel state. Let

  FIG. 5 is a cross-sectional view showing a light emitting device 2 according to the second embodiment of the present invention. FIG. 5 shows a cross section of the medium 20 cut along a plane (XY plane) parallel to the direction in which the excitation light is incident (X-axis direction).

  As shown in FIG. 5, the light emitting element 2 includes a light transmissive medium 20, a phosphor 21, a reflection film 22, a wavelength selective reflection film 23, an antireflection film 24, and a holding member 27. ing.

  The medium 20 has a frustum shape in which the light incident surface is a side surface 20f1, the light emission surface is an upper bottom surface 20f2, and the reflection surface 22fr is a lower bottom surface 20f3. The upper bottom surface 20f2 has both excitation light and fluorescence. Transmits and functions as a light incident surface. The light incident surfaces 20f1 and 20f2 are surfaces on which light collected by the collimator condensing optical system 80 is incident, and the light emission surface 20f2 is a surface from which light (fluorescence) is emitted. The light incident surface 20f1 transmits excitation light, and the light emission surface 20f2 transmits fluorescence emitted from the phosphor 21. A reflective surface 22fr is provided on the lower bottom surface 20f3. The area of the light exit surface 20f2 is smaller than the area of the light incident surfaces 20f1 and 20f2 (the area of the portion where the light incident surfaces 20f1 and 20f2 are projected onto the YZ plane).

  Note that the light collected by the collimator condensing optical system 80 is incident on the entire surface of the light incident surfaces 20f1 and 20f2 (the light condensed by the collimator condensing optical system 80 is incident on the light incident surfaces 20f1 and 20f2). The area of the portion is equal to the area of the light incident surfaces 20f1 and 20f2.

  As the medium 20, a wide variety of materials such as a resin material and an inorganic material can be used as long as they are light-transmitting substances. Especially, the inorganic material which has high heat resistance can be used suitably. In the present embodiment, an inorganic glass is used as the medium 20.

  The phosphor 21 is dispersed inside the medium 20 as phosphor particles. The phosphor 21 emits fluorescence upon receiving excitation light incident on the light incident surfaces 20f1 and 20f2. The phosphor 21 is excited by the blue light incident on the light incident surfaces 20f1 and 20f2, and converts the blue light into yellow light and emits it.

  The reflective film 22 is provided on the bottom surface 20 f 3 of the medium 20. The reflection film 22 has a reflection surface 22fr that reflects the fluorescence emitted from the phosphor 21 and guides it to the light emission surface 20f2. As a material for forming the reflective film 22, for example, aluminum (Al) can be used.

  The wavelength selective reflection film 23 is provided on the side surface 20f1 (only the light incident surface 20f1 of the light incident surface 20f1 and the light incident surface 20f2) of the medium 20. The wavelength selective reflection film 23 transmits the light (excitation light) collected by the collimator condensing optical system 80 and reflects the fluorescence emitted from the phosphor 21.

  The antireflection film 24 is provided on the upper bottom surface 20 f 2 of the medium 20. Excitation light enters the upper bottom surface 20f2 of the medium 20 from the side opposite to the medium 20 of the upper bottom surface 20f2, and fluorescence enters from the medium 20 side of the upper bottom surface 20f2. Therefore, it is preferable to provide an antireflection film 24 corresponding to the wavelength of excitation light and the wavelength of fluorescence. According to this, since the excitation light can be efficiently introduced into the medium 20 from the upper bottom surface 20f2, and the fluorescence can be efficiently extracted from the upper bottom surface 20f2, the efficiency of the light source device can be increased.

  The holding member 27 is disposed in contact with the outer surface of the reflective film 22 (on the side opposite to the surface facing the medium 20). The thermal conductivity of the holding member 27 is larger than the thermal conductivity of the medium 20. As a material for forming the holding member 27, for example, Al can be used.

  Returning to FIG. 4, the fluorescence emitted from the light emitting element 2 is reflected by the dichroic mirror 50 and enters the collimating optical system 60. The collimating optical system 60 makes the light reflected by the dichroic mirror 50 enter the integrator optical system 110 in a substantially parallel state.

  The integrator optical system 110 includes a first fly eye lens 111 and a second fly eye lens 112. The first fly-eye lens 111 and the second fly-eye lens 112 are each composed of a plurality of element lenses arranged in a matrix. The first fly-eye lens 111 has a function of dividing the light from the collimating optical system 60 by a plurality of element lenses constituting the first fly-eye lens 111 and condensing them individually. The second fly-eye lens 112 has a function of emitting the divided light flux from the first fly-eye lens 111 with an appropriate divergence angle by a plurality of element lenses constituting the second fly-eye lens 112. The integrator optical system 110 uniformizes the light intensity distribution of the light synthesized by the collimating optical system 60.

  The polarization conversion element 120 is formed of an array having a PBS, a mirror, a retardation plate, etc. as a set of elements. The polarization conversion element 120 has a function of aligning the polarization direction of each partial light beam divided by the first fly-eye lens 111 with linear polarization in one direction.

  The superimposing lens 130 appropriately converges the illumination light that has passed through the polarization conversion element 120 as a whole, and enables superimposing illumination on the illuminated regions of the liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B.

  The light source device 700 includes a light source unit 710, a condensing optical system 720, a scattering plate 730, a polarization conversion integrator rod 740, and a condensing lens 750.

  The light source unit 710 is a laser light source that emits blue light (emission intensity peak: about 445 nm) made of laser light as color light.

  The condensing optical system 720 includes a first lens 721 and a second lens 722. The first lens 721 and the second lens 722 are convex lenses. The condensing optical system 720 causes the blue light B to be incident on the scattering plate 730 in a substantially condensed state.

  The scattering plate 730 scatters the blue light from the light source unit 710 with a predetermined scattering degree to obtain blue light having a light distribution similar to fluorescence. As the scattering plate 730, for example, polished glass made of optical glass can be used.

  The polarization conversion integrator rod 740 makes the in-plane intensity distribution of the blue light from the light source unit 710 uniform, and makes the polarization direction of the blue light approximately one type of linearly polarized light having the same polarization direction. The polarization conversion integrator rod 740 includes, for example, an integrator rod, a reflecting plate that is disposed on the incident surface side of the integrator rod and has a small hole through which blue light is incident, a reflective polarizing plate that is disposed on the exit surface side, It comprises.

  The condensing lens 750 condenses the light from the polarization conversion integrator rod 740 and causes it to enter the vicinity of the image forming area of the liquid crystal light modulator 400B.

  The color separation light guide optical system 201 includes a dichroic mirror 210 and reflection mirrors 222, 230, and 250. The color separation light guide optical system 201 separates light from the light source device 101 into red light and green light, and illuminates each color light of red light and green light from the light source device 101 and blue light from the light source device 700. The liquid crystal light modulation device 400R, the liquid crystal light modulation device 400G, and the liquid crystal light modulation device 400B are guided.

  The red light transmitted through the dichroic mirror 210 is reflected by the reflection mirror 230, passes through the condenser lens 300R, and enters the image forming area of the liquid crystal light modulation device 400R for red light.

  The green light reflected by the dichroic mirror 210 is further reflected by the reflection mirror 222, passes through the condenser lens 300G, and enters the image forming area of the liquid crystal light modulation device 400G for green light.

  The blue light from the light source device 700 is reflected by the reflection mirror 250, passes through the condenser lens 300B, and enters the image forming region of the blue light liquid crystal light modulation device 400B.

  According to the light emitting element 2 of the present embodiment, the reflective light emitting element 2 can be realized.

(Modification 1)
FIG. 6 is a cross-sectional view showing a first modification of the light emitting device according to the present invention.
As shown in FIG. 6, the light-emitting element 2A according to this modification includes a light-transmitting medium 20A, a phosphor 21A, a reflection film 22A, a wavelength selective reflection film 23A, an antireflection film 24A, and a holding member. 27A.

  The medium 20A has a triangular prism shape in which the light incident surface is the first side surface 20Af1, the light emission surface is the second side surface 20Af2, and the reflection surface 22Afr is the third side surface 20Af3. The light incident surface 20Af1 is a surface on which excitation light is incident, and the light emission surface 20Af2 is a surface from which light (fluorescence) is emitted. The light incident surface 20Af1 transmits excitation light, and the light exit surface 20Af2 transmits fluorescence emitted from the phosphor 21A. A reflective surface 22Afr is provided on the third side surface 20Af3. The area of the light emitting surface 20Af2 is smaller than the area of the light incident surface 20Af1.

  The medium 20A has a right triangular prism shape. For example, the angle θA1 formed by the first side face 20Af1 and the second side face 20Af2 is 90 degrees, the angle θA2 formed by the first side face 20Af1 and the third side face 20Af3 is 30 degrees, and the second side face 20Af2 and the third side face 20Af2. The angle θA3 formed with the side surface 20Af3 is 60 degrees.

  According to the light emitting element 2A of this modification, light can be extracted in a desired direction by freely adjusting the angle of each apex angle of the triangle. Therefore, the freedom degree of the arrangement design of an optical member increases.

(Modification 2)
FIG. 7 is a cross-sectional view showing a second modification of the light emitting device according to the present invention, corresponding to FIG. As shown in FIG. 7, the light-emitting element 1 </ b> A according to this modification is different from the light-emitting element 1 described above in that a holding member 17 that holds the medium 10 is disposed. Since the other points are the same as the above-described configuration, the same elements as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, the light emitting element 1 </ b> A includes a medium 10, a phosphor 11, a wavelength selective reflection film 13, antireflection films 14 and 16, a light transmission member 15, and a holding member 17. Yes. In this modification, silicon resin is used as the medium 10.

  The holding member 17 is disposed in contact with the side surface 10 f 3 of the medium 10. The holding member 17 is made of a metal material. As a material for forming the holding member 17, for example, Al can be used. The surface on the medium 10 side of the holding member 17 is a reflecting surface 17fr. The thermal conductivity of the holding member 17 is larger than the thermal conductivity of the medium 10.

  According to the light emitting element 1A of the present modification, even when the medium 10 is made of a soft material (resin or the like), the medium 10 can be held so that the medium 10 is not deformed.

  Further, according to this configuration, it is not necessary to deposit a reflective film or the like on the side surface 10f3 of the medium 10. Therefore, the manufacturing process can be simplified.

  Further, according to this configuration, even when the phosphor 11 generates heat upon receiving the excitation light incident on the light incident surface 10 f 1, the heat generated by the phosphor 11 is radiated to the outside via the medium 10 and the holding member 17. The Therefore, it can suppress that the fluorescent substance 11 becomes high temperature, and can suppress the fall of luminous efficiency.

(Modification 3)
FIG. 8 is a cross-sectional view showing a third modification of the light emitting device according to the present invention, corresponding to FIG. As shown in FIG. 8, the light-emitting element 1B according to this modification is different from the above-described light-emitting element 1A in that the phosphor 11B has a layer structure, a light diffusion plate 18 is provided. Since the other points are the same as the above-described configuration, the same elements as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 8, the light emitting element 1B includes a medium 10B, a phosphor 11B, a wavelength selective reflection film 13, antireflection films 14, 16, a light transmission member 15, a holding member 17, and a light diffusion plate. 18. In this modification, silicon resin is used as the medium 10B, and the phosphor particles are not dispersed in the medium 10B.

The phosphor 11B is provided on the side surface 10Bf3 of the medium 10B. The phosphor 11B is excited by the blue light diffused by the light diffusion plate 18 and incident on the phosphor 11B, and the blue light is converted into yellow light and emitted. The phosphor 11B is composed of a layer containing, for example, (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce, which is a YAG phosphor. As the phosphor 11, another phosphor that emits yellow light may be used.

  The light diffusing plate 18 is provided on the outer surface of the wavelength selective reflection film 13 (on the side opposite to the surface facing the medium 10B). The light diffusing plate 18 has a function of diffusing light incident toward the light incident surface 10Bf1 and causing the light to enter the phosphor 11B.

  Also in the light emitting element 1B of the present modification, the light use efficiency can be increased while suppressing a decrease in the light emission efficiency.

  In the light emitting element 1B of this modification, the configuration in which the medium 10B is a silicon resin has been described as an example, but the present invention is not limited thereto. For example, the medium may be an air layer. Thereby, the structure of the light emitting element can be simplified. When the medium is an air layer, the phosphor 11B is formed on the side wall surface of the opening of the holding member 17, and then an antireflection film 14 is provided in a portion overlapping the opening on the upper side of the holding member 17. By attaching the light transmitting member 15 in which the wavelength selective reflection film 13, the light diffusing plate 18, and the antireflection film 16 are formed in a portion that overlaps the opening on the side, a light emitting device in which the medium is an air layer can be manufactured. .

(Modification 4)
FIG. 9 is a cross-sectional view showing a fourth modification of the light emitting device according to the present invention.
As shown in FIG. 9, the light emitting element 2B according to this modification includes a light transmissive medium 20B, a phosphor 21B, a reflective film 22B, a wavelength selective reflection film 23B, an antireflection film 24B, and a holding member. 27B.

  The medium 20B has a quadrangular prism shape in which the light incident surface is the first side surface 20Bf1, the light emission surface is the second side surface 20Bf2, and the reflection surface 22Bfr is the third side surface 20Bf3 and the fourth side surface 20Bf4. . The light incident surface 20Bf1 is a surface on which excitation light is incident, and the light emission surface 20Bf2 is a surface from which light (fluorescence) is emitted. The light incident surface 20Bf1 transmits excitation light, and the light emission surface 20Bf2 transmits fluorescence emitted from the phosphor 21B. A reflective surface 22Bfr is provided on the third side surface 20Bf3 and the fourth side surface 20Bf4. The area of the light emitting surface 20Bf2 is smaller than the area of the light incident surface 20Bf1.

  The medium 20B has a quadrangular prism shape. For example, the angle θB1 formed by the first side face 20Bf1 and the second side face 20Bf2 is 145 degrees, the angle θB2 formed by the first side face 20Bf1 and the third side face 20Bf3 is 90 degrees, and the third side face 20Bf3 and the fourth side face 20Bf3. The angle θB3 formed by the side surface 20Bf4 is 90 degrees, and the angle θB4 formed by the fourth side surface 20Bf4 and the second side surface 20Bf2 is 45 degrees.

  According to the light emitting element 2 </ b> B of the present modification, light can be extracted in a desired direction by freely adjusting the square apex angles. Therefore, the freedom degree of the arrangement design of an optical member increases.

  The present invention is applicable not only when applied to a front projection type projector that projects from the side that observes the projected image, but also when applied to a rear projection type projector that projects from the side opposite to the side that observes the projected image. can do.

  In each of the above embodiments, the example in which the illumination device of the present invention is applied to a projector has been described, but the present invention is not limited to this. For example, the lighting device of the present invention can be applied to other optical devices (for example, an optical disk device, a car headlamp, a lighting device, etc.).

1, 1A, 1B, 2, 2A, 2B ... Light emitting element 10, 10B, 20, 20A, 20B ... Medium, 10f1, 20f1, 20f2 ... Light incident surface, 10f2, 20f2 ... Light exit surface, 10f3 ... Side surface (multiple ), 11, 21, 21A... Phosphor, 12, 22, 22A... Reflective film, 12fr, 17fr, 22fr, 22Afr... Reflective surface, 13, 23,. 23A ... wavelength selective reflection film, 15 ... light transmitting member, 17, 27, 27A, 27B ... holding member, 20Af1 ... first side, 20Af2 ... second side, 20Af3 ... third side, 20Bf1 ... first Side surface, 20Bf2 ... second side surface, 20Bf3 ... third side surface, 20Bf4 ... fourth side surface, 30 ... excitation light source, 400R, 400G, 400B ... liquid crystal light modulation device (light modulation device), 600 The projection optical system, 1000 ... projector

Claims (12)

A medium having a plurality of surfaces including a light incident surface and a light exit surface;
A phosphor that receives excitation light incident on the light incident surface and emits fluorescence from the light exit surface; and
Of the plurality of surfaces, a surface different from the light incident surface and the light emitting surface is provided with a reflecting surface that reflects the fluorescence emitted from the phosphor and guides it to the light emitting surface.
Area of the light exit plane has smaller Kuna' than the area of the light incident surface,
A wavelength selective reflection film that transmits the excitation light and reflects the fluorescence is disposed on the light incident surface,
The medium has a frustum shape having the light incident surface as a side surface, the light emitting surface as an upper bottom surface, and the reflecting surface as a lower bottom surface,
The light emitting element , wherein the upper bottom surface transmits both the excitation light and the fluorescence and functions as the light incident surface . A medium having a plurality of surfaces including a light incident surface and a light exit surface;
A phosphor that receives excitation light incident on the light incident surface and emits fluorescence from the light exit surface; and
Of the plurality of surfaces, a surface different from the light incident surface and the light emitting surface is provided with a reflecting surface that reflects the fluorescence emitted from the phosphor and guides it to the light emitting surface.
Area of the light exit plane has smaller Kuna' than the area of the light incident surface,
A wavelength selective reflection film that transmits the excitation light and reflects the fluorescence is disposed on the light incident surface,
The light-emitting element, wherein the medium has a triangular prism shape in which the light incident surface is a first side surface, the light emission surface is a second side surface, and the reflection surface is a third side surface . The phosphor emitting device according to claim 1 or 2, characterized in that it is distributed inside the medium as phosphor particles. A light transmissive member that transmits the excitation light is disposed in contact with a surface of the wavelength selective reflection film opposite to the surface facing the medium;
The light thermal conductivity of the transparent member, the light emitting device according to any one of claims 1 to 3 being greater than the thermal conductivity of the wavelength-selective reflective layer.   5. The light emission according to claim 2, wherein an area of a cross section of the medium orthogonal to an incident optical axis of the excitation light gradually decreases as the distance from the light incident surface increases. element.   6. The medium according to claim 2, wherein the medium has a frustum shape in which the light incident surface is a lower bottom surface, the light emission surface is an upper bottom surface, and the reflection surface is a side surface. Light emitting element.   The light emitting device according to claim 2, wherein a holding member that holds the medium is disposed on the reflection surface.   The light emitting element according to claim 7, wherein a surface of the holding member on the medium side is the reflective surface.   The light emitting device according to claim 7 or 8, wherein the heat conductivity of the holding member is larger than the heat conductivity of the medium. Light-emitting device according to any one of claims 1 to 9, wherein the medium is glass. The light emitting device according to any one of claims 1 to 10 ,
An excitation light source that causes the excitation light to enter the light incident surface of the light emitting element;
A light source device comprising: The light source device according to claim 11 ;
A light modulation device that modulates light emitted from the light source device according to image information;
A projection optical system that projects modulated light from the light modulation device as a projection image;
A projector comprising:

Images