JP2012141495A - Light source device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device capable of suppressing reduction in luminous efficiency and of emitting fluorescent light having strong intensity.SOLUTION: A light source device includes: excitation light emitting means emitting excitation light LB1 and excitation light LB2; a substrate 51 transmitting at least the excitation light LB1; and a phosphor layer 52 disposed on one principal surface of the substrate 51. The excitation light emitting means irradiates the phosphor layer 52 with the excitation light LB1 from a substrate 51 side of the phosphor layer 52 while irradiating the phosphor layer 52 with the excitation light LB2 from an opposite side of the phosphor layer 52 to the substrate 51. At least a part of an irradiation region of the excitation light LB1 is overlapped with an irradiation region of the excitation light LB2 as viewed in a plan view, and intensity of the excitation light LB1 is greater than intensity of the excitation light LB2.

Description

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

  Conventionally, in a projector, a discharge lamp such as an ultra-high pressure mercury lamp is generally used as a light source. However, this type of discharge lamp has problems such as a relatively short life, difficulty in instantaneous lighting, and ultraviolet light emitted from the lamp deteriorates the liquid crystal light bulb. In view of this, a projector using a light source instead of a discharge lamp has been proposed.

  For example, the projector proposed in Patent Document 1 uses a light source that makes excitation light incident on a phosphor layer containing a phosphor from the outside and emits emitted light (fluorescence) obtained. In the light source of Patent Document 1, the total area of the end faces in the visible light emission direction of the phosphor layer is set to be smaller than the total area of the excitation light emission end faces, and is stronger from a smaller area than directly using the excitation light source. It has been proposed as a light source that can emit light. In addition, the phosphor layer is irradiated with excitation light from the opposite side of the phosphor layer from the substrate.

JP 2004-327361 A

  In the light source described in Patent Document 1, excitation light is absorbed by a phosphor dispersed mainly in a region of the phosphor layer opposite to the substrate (excitation light irradiation side) and converted into fluorescence. Is done. Even if the intensity of the excitation light on the phosphor layer is increased in order to obtain strong light emission, the energy of the excitation light is consumed mainly in a region of the phosphor layer opposite to the substrate. That is, the light energy density mainly in the region on the opposite side of the substrate from the phosphor layer is increased. For this reason, if the intensity of the excitation light on the phosphor layer is too high, the amount of light emission decreases for the following reason.

  First, when the phosphor emits light, part of the energy changes to heat and self-heating occurs. On the other hand, the light emission efficiency of the phosphor (ratio of the light emission amount of the phosphor with respect to the incident light amount of excitation light) depends on temperature, and it is known that the conversion efficiency decreases as the temperature increases. Therefore, if the intensity of the excitation light on the phosphor layer is too high, the temperature rises due to self-heating, and the light emission efficiency tends to decrease.

  In addition, when the intensity of the excitation light (light energy density) on the phosphor layer is large, the proportion of electrons excited in the phosphor molecule increases, and the number of electrons that can be excited (ground state electrons) decreases. A so-called light saturation phenomenon occurs in which light emission according to the intensity of the excitation light cannot be performed. This also reduces the light emission efficiency.

  As described above, even if the intensity of the excitation light on the phosphor layer is increased in order to obtain strong light emission with the light source as in Patent Document 1, the light emission efficiency is lowered for the above reason. It was difficult to get.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a light source device capable of suppressing a decrease in light emission efficiency and emitting strong (a large amount of light) fluorescence. It is another object of the present invention to provide a projector having such a light source device and capable of displaying a high-quality image.

  In order to solve the above problems, a light source device of the present invention includes excitation light emitting means for emitting excitation light including first light and second light, and light having a peak wavelength of at least the first light. A transmitting substrate; and a phosphor layer that is provided on the substrate and that is excited by the excitation light and emits fluorescence having a wavelength different from that of the excitation light. The excitation light emitting unit includes the phosphor layer. Irradiating the phosphor layer with the first light from the substrate side, and irradiating the phosphor layer with the second light from the opposite side of the phosphor layer to the substrate, The region irradiated with the first light overlaps at least a part of the region irradiated with the second light of the phosphor layer in plan view, and the first light on the phosphor layer The intensity of is greater than the intensity of the second light on the phosphor layer.

  According to the present invention, the phosphor layer is irradiated with the first light from the substrate side of the phosphor layer, and the phosphor layer is irradiated with the second light from the opposite side of the phosphor layer from the substrate. That is, the first light is absorbed mainly in a region relatively close to the substrate in the phosphor layer and converted into fluorescence. The second light is absorbed mainly in a region of the phosphor layer that is relatively far from the substrate and is converted into fluorescence. In this specification, a region of the phosphor layer that is relatively close to the substrate is referred to as a first region, and a region of the phosphor layer that is relatively far from the substrate is referred to as a second region. The fluorescence emitted from the phosphor layer is the sum of the fluorescence emitted from the first region and the fluorescence emitted from the second region.

  Therefore, the intensity of the first light on the phosphor layer and the phosphor layer are compared with the case where the phosphor layer is irradiated with excitation light only from one side of the phosphor layer as in the conventional light source. Even if the intensity of each of the second lights is reduced, it is possible to obtain light emission having the same intensity as that obtained by a conventional light source. In other words, even if the light energy density applied to the first region and the light energy density applied to the second region are reduced, light emission having the same intensity as the light emission obtained by the conventional light source can be obtained. . Therefore, according to the present invention, it is possible to suppress a decrease in light emission efficiency due to heat generation or a light saturation phenomenon.

  Further, since the intensity of the first light on the phosphor layer is larger than the intensity of the second light on the phosphor layer, the amount of heat generated in the first region of the phosphor layer is the second intensity of the phosphor layer. More than the amount of heat generated in the region. Since the heat generated in the phosphor layer can be dissipated through the substrate, the region closer to the substrate (first region) and having a larger amount of heat generation is the region farther from the substrate (second region). As compared with a state where the amount of heat generation is large, heat is not easily trapped in the phosphor layer, and a decrease in luminous efficiency due to heat generation can be further suppressed.

  By combining these effects, it is possible to obtain a light source with higher luminous efficiency than in the past.

In the present invention, a first wavelength selection film that transmits at least light having the peak wavelength of the first light and reflects light having the peak wavelength of fluorescence is provided between the substrate and the phosphor layer. It is desirable that
According to this configuration, since the fluorescence emitted isotropically in the phosphor layer can be reflected to the side opposite to the substrate, the fluorescence can be effectively extracted.

In the present invention, it is desirable that the excitation light emitting means includes a first light source that emits the first light and a second light source that emits the second light.
According to this configuration, since the intensity of the first light on the phosphor layer and the intensity of the second light on the phosphor layer can be controlled independently, the first light on the phosphor layer can be controlled. It becomes easy to make the intensity of the light greater than the intensity of the second light on the phosphor layer.

In the present invention, it is desirable that the wavelength of the first light is different from the wavelength of the second light.
According to this configuration, since the first light and the second light can be combined to emit excitation light in a wide wavelength band, the absorption wavelength band of the phosphor layer and the wavelength band of the excitation light Can overlap in a wide range, and the proportion of excitation light that is effectively converted into fluorescence in the phosphor layer can be increased. Therefore, fluorescence can be efficiently generated in the phosphor layer.

In the present invention, at least light having a peak wavelength of the first light is transmitted between the substrate and the phosphor layer, and light having a peak wavelength of the fluorescence and light having a peak wavelength of the second light is transmitted. It is desirable to provide a first wavelength selection film that reflects light.
According to this configuration, the remaining portion of the second light that has not been absorbed by the phosphor layer is reflected by the first wavelength selection film and is transmitted through the phosphor layer again. At that time, since the remainder is converted into fluorescence in the phosphor layer, the excitation light can be efficiently converted into fluorescence.

In the present invention, the light having the peak wavelength of the first light is reflected on the surface of the phosphor layer opposite to the substrate, the light having the peak wavelength of the second light, and the peak of the fluorescence. It is desirable to provide a second wavelength selection film that transmits light of a wavelength.
According to this configuration, the remaining portion of the first light that has not been absorbed by the phosphor layer is reflected by the second wavelength selection film and is transmitted through the phosphor layer again. At that time, since the remainder is converted into fluorescence in the phosphor layer, the excitation light can be efficiently converted into fluorescence.

In the present invention, facing the phosphor layer, the light having the peak wavelength of the first light and the light having the peak wavelength of the fluorescence are transmitted, and the light having the peak wavelength of the second light is reflected. It is desirable that a wavelength selective mirror is provided.
According to this configuration, the first light can also be taken out and used as illumination light.

In the present invention, it is desirable that the first light is visible light and the fluorescence is a color light complementary to the first light.
According to this configuration, the light source device can emit white light by mixing the first light and the fluorescence.

In this invention, it is desirable to have a condensing means for condensing the excitation light on the phosphor layer.
According to this configuration, the light emitting region on the phosphor layer as the secondary light source can be made smaller and close to a point light source, and thus a light source device with a small etendue can be obtained.

In the present invention, the light source is preferably a laser light source array in which a plurality of laser light sources are arranged.
According to this configuration, it is possible to extract a large amount of fluorescence by increasing the intensity of the excitation light.

According to another aspect of the invention, there is provided a projector comprising: the light source device described above; a light modulation element that modulates light emitted from the light source apparatus; and a projection optical system that projects light modulated by the light modulation element. It is characterized by.
According to this configuration, since the above-described light source device is provided, a projector capable of displaying a high-quality image by stabilizing the light amount by suppressing the occurrence of the light saturation phenomenon and suppressing brightness unevenness. Can do.

It is a schematic diagram which shows the light source device and projector of 1st Embodiment. It is a front view of the light source contained in a light source device. It is a side view of the light source contained in a light source device. It is a graph which shows the light emission characteristic of a light source device and a fluorescent substance layer. It is explanatory drawing of a polarization conversion element. It is explanatory drawing which shows the light emitting element used for the light source device of 1st Embodiment. It is the graph which showed the luminous efficiency of the fluorescent substance with respect to the light energy density of excitation light. It is a schematic diagram which shows the structure of a comparative example. It is a schematic diagram which shows the structure of the light emitting element used for the light source device of 1st Embodiment. It is a schematic diagram which shows the structure of the light emitting element used for the light source device of 1st Embodiment. It is explanatory drawing which shows the light emitting element used for the light source device of 2nd Embodiment. It is explanatory drawing which shows the light emitting element used for the light source device of 3rd Embodiment. It is explanatory drawing which shows the light emitting element used for the light source device of 4th Embodiment.

[First Embodiment]
The light source device and projector according to the first embodiment of the present invention will be described below with reference to FIGS. In all the drawings below, the dimensions and ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

  FIG. 1 is a schematic diagram illustrating a light source device 100A and a projector PJ according to the present embodiment. As shown in the figure, the projector PJ includes a light source device 100, a dichroic mirror 200, a liquid crystal light valve (light modulation element) 300R, a liquid crystal light valve 300G, a liquid crystal light valve 300B, a color composition element 400, and a projection optical system 500. .

  The projector PJ generally operates as follows. From the light source device 100, light L1 including red light R and green light G and blue light L2 are emitted. The light L1 emitted from the light source device 100 is separated into red light R and green light G by the dichroic mirror 200. The light L2 is emitted as blue light B from the light source device 100. The red light R, green light G, and blue light B are incident on the corresponding liquid crystal light valve 300R, liquid crystal light valve 300G, and liquid crystal light valve 300B, respectively, and modulated. Each color light modulated by the liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B enters the color composition element 400 and is synthesized. The light synthesized by the color synthesizing element 400 is enlarged and projected onto a projection surface 600 such as a wall or a screen by the projection optical system 500, and a full-color projection image is displayed. Hereinafter, each component of the projector PJ will be described.

  The light source device 100 includes a first light source 10 and a second light source 11 as excitation light emitting means. The configuration of the first light source 10 is the same as that of the second light source 11. The excitation light LB1 is emitted as the first light from the first light source 10, and the excitation light LB2 is emitted as the second light from the second light source 11.

  On the optical path of the excitation light LB1, a collimator lens array 21, a condensing lens 22, and a light emitting element 50A are arranged in this order. A collimating optical system 20A, a dichroic mirror 30, a pickup optical system (condensing means) 40, and a light emitting element 50A are arranged in this order on the optical path of the excitation light LB2.

  A phosphor layer 52 is provided in the light emitting element 50A. The phosphor layer 52 is irradiated with excitation light LB1 emitted from the first light source 10 and excitation light LB2 emitted from the second light source 11 to generate fluorescence, and the fluorescence is emitted as illumination light of the liquid crystal light valve. It is the composition which makes it.

  Here, the first light source 10 and the second light source 11 are controlled such that the intensity of the excitation light LB1 on the phosphor layer 52 is larger than the intensity of the excitation light LB2 on the phosphor layer 52. The region (irradiation region) irradiated with the excitation light LB1 on the phosphor layer 52 is at least partially overlapped with the region (irradiation region) irradiated with the excitation light LB2 on the phosphor layer 52 in plan view. Is provided. Of course, the irradiation region of the excitation light LB1 and the irradiation region of the excitation light LB2 may be provided so as to overlap each other.

  Fluorescence emitted from the light emitting element 50A is picked up optical system (condensing means) 40, dichroic mirror 30, condensing optical system 60, polarization conversion element 70, rod integrator 80, collimating lens 90, arranged on the optical path, Are transmitted in this order and emitted to the outside of the light source device 100A.

  FIG. 2 is a front view of the first light source 10 and the second light source 11. As shown in the drawing, the first light source 10 and the second light source 11 are laser light sources in which laser light sources 16 are arranged in a two-dimensional array (25 in total) in a square shape of 5 × 5 on a base 15. It is an array.

  The first light source 10 emits blue excitation light LB1 (laser light) having a wavelength of around 450 nm (peak of emission intensity: about 445 nm, see FIG. 4A) as excitation light for exciting a fluorescent material included in the light emitting element 50A described later. ). The second light source 11 also emits blue excitation light LB2 (laser light) having a wavelength of around 450 nm as excitation light for exciting the fluorescent material. In FIG. 4A, reference numerals LB1 and LB2 indicate color light (blue light) components emitted by the first light source 10 and the second light source 11.

  In addition, the 1st light source 10 and the 2nd light source 11 are good also as using only one laser light source instead of a laser light source array as shown in FIG. Moreover, as long as it is the light of the wavelength which can excite the fluorescent substance mentioned later, you may be a light source which inject | emits the color light which has a peak wavelength other than 445 nm.

  The excitation light LB1 emitted from the first light source 10 is collimated by the collimator lens array 21 and then condensed on the phosphor layer 52 of the light emitting element 50A through the condenser lens 22.

  On the other hand, the excitation light LB2 emitted from the second light source 11 is collimated by the collimator lens array 23 included in the collimating optical system 20A and condensed after being condensed by the condenser lens 24 as shown in FIG. By passing through the conversion lens 25, the beam bundle is reduced as a whole of the excitation light LB2.

  The excitation light LB2 that has passed through the collimating optical system 20A is reflected by the dichroic mirror 30. The dichroic mirror 30 is obtained by laminating a dielectric multilayer film on the glass surface. The dichroic mirror 30 has wavelength selectivity that selectively reflects the color light in the wavelength band of the excitation light LB2 (and the excitation light LB1) and transmits the color light in the other wavelength bands. Specifically, the dichroic mirror 30 reflects blue light and transmits light having a longer wavelength than blue light (for example, light having a longer wavelength than 480 nm). Then, the excitation light LB2 enters the pickup optical system 40.

  The pickup optical system 40 includes a first lens 41 that is a convex lens, and a second lens 42 that is a half-convex lens on which excitation light via the first lens 41 enters. The pickup optical system 40 is disposed on the light axis of the excitation light LB2 reflected by the dichroic mirror 30, and condenses the excitation light LB2 on the light emitting element 50A.

  The light collection angle of the pickup optical system 40 is, for example, a maximum of 25 degrees. Further, on the light emitting element 50A, the individual spots of the laser light source 16 included in the second light source 11 are set so that the condensing positions are not completely overlapped. Is configured to draw a substantially square shape of 1 mm square. Thereby, since the light emission part on the fluorescent substance layer as a secondary light source can be shortened and it can be brought close to a point light source, it becomes possible to set it as a light source device with a small etendue.

  The light emitting element 50A includes a plate-shaped substrate 51, a phosphor layer 52 formed on the substrate 51 facing the pickup optical system 40, and a wavelength selection film provided between the substrate 51 and the phosphor layer 52. (First wavelength selection film) 56. The first wavelength selection film 56 has a property of transmitting the excitation light LB1 and the excitation light LB2 and reflecting the fluorescence emitted from the phosphor layer 52.

  The phosphor layer 52 has phosphor particles that emit fluorescence, absorbs the excitation light LB1 and the excitation light LB2 (blue light), and is yellow (emission intensity peak: about 550 nm, see FIG. 4B). It has a function of converting to fluorescence. In FIG. 4B, the component indicated by R is a color light component that can be used as red light among the yellow light emitted from the phosphor layer 52, and the component indicated by G is also used as green light. Possible color light component. In FIG. 1, red light is indicated by symbol R, green light is indicated by symbol G, and fluorescence including red light R and green light G is indicated by symbol RG. The configuration of the light emitting element 50 will be described in detail later.

  The fluorescence RG emitted from the light emitting element 50A enters the pickup optical system 40. The pickup optical system 40 also has a function of collecting (pickup) and collimating the fluorescent RG emitted isotropically by the light emitting element 50A.

  The fluorescent RG emitted from the light emitting element 50 </ b> A is collimated by the pickup optical system 40, passes through the dichroic mirror 30, and enters the condensing optical system 60. The condensing optical system 60 collects the fluorescent light and makes it incident on the polarization conversion element 70.

  The polarization conversion element 70 has a function of separating incident fluorescence into p-polarized light and s-polarized light, converting one of the p-polarized light and the s-polarized light into the polarization direction of the other polarized light, and emitting the polarized light. ing.

  FIG. 5 is an explanatory diagram of the polarization conversion element 70. As shown in the figure, the polarization conversion element 70 transmits, for example, a p-polarized component of the fluorescence RG and reflects a s-polarized component, a polarizing beam splitter film (hereinafter referred to as a PBS film) 71, a reflective film 72, and s-polarized light. And a λ / 2 retardation film 73 for converting the light into p-polarized light.

  The fluorescence RG incident on the polarization conversion element 70 is first separated into s-polarized light and p-polarized light by the PBS film 71 provided with an inclination of about 45 degrees with respect to the optical axis of the fluorescence RG. The PBS film 71 transmits p-polarized light (indicated by reference sign P2 in FIG. 5) and reflects s-polarized light in a direction of about 45 degrees with respect to the surface of the PBS film 71.

  A reflection film 72 provided with an inclination of about 45 degrees with respect to the optical axis of the s-polarized light is provided at the destination of the reflected s-polarized light, and the s-polarized light is separated by the PBS film 71. By changing the direction in the same direction as the traveling direction of the p-polarized light and passing through the λ / 2 retardation film 73, the light is emitted as substantially parallel light aligned with the p-polarized light (indicated by reference numeral P1 in FIG. 5). Of course, the configuration of the PBS film 71 may be such that all of the above-described relationships between the s-polarized light and the p-polarized light are switched, and the fluorescence RG is emitted in alignment with the s-polarized light.

  The fluorescence RG whose polarization direction is aligned by the polarization conversion element 70 is incident on one end side of the rod integrator 80. The rod integrator 80 is a prismatic optical member extending in the direction of the optical path, and generates multiple reflections in the light transmitted through the inside, thereby mixing the light emitted from the polarization conversion element 70 and uniforming the luminance distribution. It is to become. The cross-sectional shape orthogonal to the optical path direction of the rod integrator 80 is substantially similar to the outer shape of the image forming area of the liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B.

  The fluorescence RG emitted from the other end of the rod integrator 80 is collimated by the collimating lens 90 and emitted from the light source device 100A.

  On the other hand, the light source device 100 collimates a third light source 12 that is an LED (Light Emitting Diode) light source that emits blue light B, a first lens 27 that receives blue light B, and laser light that has passed through the first lens 27. A collimating optical system 20B that collimates the blue light B emitted from the third light source 12, and a condensing optical system 60, a polarization conversion element 70, and a rod integrator 80 similar to the light source device 100A. The collimating lens 90 is arranged in this order on the optical path. That is, the light source device 100 is configured to emit blue light used as illumination light for the liquid crystal light valve. However, it is not essential that the light source device 100 has a configuration for emitting the blue light B. In order to obtain the blue light B, a light source device different from the light source device 100 may be provided.

  The fluorescence RG emitted from the light source device 100A enters the dichroic mirror 200. The dichroic mirror 200 is formed by laminating a dielectric multilayer film on the glass surface, similarly to the dichroic mirror 30 described above. The dichroic mirror 200 has wavelength selectivity that reflects the green light G and transmits the red light R.

  The red light R included in the fluorescence RG passes through the dichroic mirror 200, is reflected by the mirror 210, and enters the liquid crystal light valve 300R. Further, the green light G included in the fluorescence RG is reflected by the dichroic mirror 200, reflected by the mirror 220, and enters the liquid crystal light valve 300G.

  Further, the light L2 (blue light B) emitted from the light source device 100 is reflected by the mirror 230 and enters the liquid crystal light valve 300B.

  As the liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B, commonly known ones can be used. For example, a transmission having a liquid crystal element 310 and polarizing elements 320 and 330 that sandwich the liquid crystal element 310 is used. It is composed of a light modulation device such as a liquid crystal light valve. For example, the polarizing elements 320 and 330 have a configuration in which the transmission axes are orthogonal to each other (crossed Nicols arrangement).

  The liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B are electrically connected to a signal source (not shown) such as a PC that supplies an image signal including image information. The liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B form an image by spatially modulating incident light for each pixel based on the supplied image signal. The liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B form a red image, a green image, and a blue image, respectively. The light (formed image) modulated by the liquid crystal light valve 300R, the liquid crystal light valve 300G, and the liquid crystal light valve 300B enters the color composition element 400.

The color composition element 400 is configured by a dichroic prism or the like. The dichroic prism has a structure in which four triangular prisms are bonded to each other. The surface to be bonded in the triangular prism becomes the inner surface of the dichroic prism. On the inner surface of the dichroic prism, a mirror surface that reflects red light R and transmits green light G and a mirror surface that reflects blue light B and transmits green light G are formed orthogonal to each other. The green light G incident on the dichroic prism is emitted as it is through the mirror surface. The red light R and blue light B incident on the dichroic prism are selectively reflected or transmitted by the mirror surface and emitted in the same direction as the emission direction of the green light G. In this way, the three color lights (images) are superimposed and combined, and the combined color light is enlarged and projected onto the projection surface 600 by the projection optical system 500.
In the projector PJ of the present embodiment, image display is performed as described above.

  Next, the light emitting element 50A included in the light source device 100A of the present embodiment will be described in detail with reference to FIGS.

  6A and 6B are explanatory views showing the light emitting element 50A. FIG. 6A is a schematic sectional view, and FIG. 6B is an explanatory view showing a state of light emission.

  The substrate 51 shown in FIG. 6A has a property of transmitting the excitation light LB1 that is blue light and the excitation light LB2 that is blue light. As the forming material, for example, an inorganic material such as quartz glass, crystal, and sapphire (single crystal corundum), or a transparent forming material such as an acrylic resin and a polycarbonate resin can be used. Among these, in consideration of heat dissipation described later, it is preferable to use an inorganic material having a relatively higher heat transfer property than the resin material. The substrate 51 of the present embodiment is assumed to be formed using quartz glass.

  The phosphor layer 52 includes a plurality of phosphor particles 53 and a base material 54 that embeds the phosphor particles 53.

  The phosphor particles 53 are particulate fluorescent materials that absorb the excitation light LB1 emitted from the first light source 10 and the excitation light LB2 emitted from the second light source 11 shown in FIG. 1 and emit fluorescence RG. For example, the phosphor particles 53 include a substance that emits fluorescence when excited by blue light having a wavelength of about 445 nm, and a part of the excitation light LB1 and the excitation light LB2 is changed from the red wavelength band to the green wavelength. It is converted into light including up to the band and emitted. As such phosphor particles 53, those having an average particle diameter of about 1 μm to several tens of μm are known to exhibit high luminous efficiency.

As the phosphor particles 53, a commonly known YAG (yttrium, aluminum, garnet) phosphor 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 particles 53 may be formed of a single material, or a mixture of particles formed using two or more materials may be used as the phosphor particles 53.

  Here, the average particle diameter of the phosphor particles 53 can be measured by using a particle size distribution measuring apparatus (for example, SALD2200 (manufactured by Shimadzu Corporation)) based on a 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.

  As a material for forming the base material 54, a resin material having optical transparency can be used. A curable resin can be preferably used because of easy molding, and among them, a silicone resin having a high heat resistance (refractive index: 1.42) can be preferably used.

  The wavelength selection film 56 is configured by a dielectric multilayer film formed by alternately laminating, for example, two types of dielectric layers on the surface of the substrate 51. Such a wavelength selection film 56 has wavelength selectivity that selectively transmits the color light in the wavelength bands of the excitation light LB1 and the excitation light LB2, and reflects the color light in the other wavelength bands. Specifically, the wavelength selection film 56 transmits blue light and reflects light having a longer wavelength than blue light (for example, light having a longer wavelength than 480 nm).

  As shown in FIG. 6B, when the excitation light LB1 and the excitation light LB2 enter the light emitting element 50A having the above-described configuration, the phosphor particles contained in the phosphor layer 52 emit fluorescence RG. That is, a part of the excitation light LB1 incident on the phosphor layer 52 from the first surface S1 of the light emitting element 50A via the wavelength selection film 56 is absorbed by the phosphor layer 52 and converted into the fluorescence RG, and the remaining portion LB1x It passes through and is injected outside.

  Further, a part of the excitation light LB2 incident on the phosphor layer 52 from the second surface S2 of the light emitting element 50A is absorbed by the phosphor layer 52 and converted into fluorescence RG, and the remaining LB2x is converted into the wavelength selection film 56 and the substrate 51. It is injected outside through. Of course, it is possible to control the intensity of the excitation light LB1 on the phosphor layer 52 and the intensity of the excitation light LB2 on the phosphor layer 52 so that the remainder LB1x and the remainder LB2x do not occur.

  Of the fluorescent RG emitted isotropically from the phosphor particles contained in the phosphor layer 52, the component emitted in the direction of the second surface S2 is directly emitted to the outside and is emitted in the direction of the wavelength selection film 56. The component is reflected by the wavelength selection film 56 in the direction of the second surface S2, and is emitted to the outside. In this manner, the light emitting element 50A emits the fluorescence RG.

  Here, the intensity of excitation light on the phosphor layer 52 (light energy density of excitation light) is not as good as possible. FIG. 7 is a graph showing the luminous efficiency of the phosphor (phosphor particles) in the phosphor layer 52 with respect to the light energy density of the excitation light. In the figure, the horizontal axis represents the light energy density of the excitation light, and the vertical axis represents the luminous efficiency of the phosphor (ratio of the amount of fluorescence emitted by the phosphor to the amount of excitation light applied to the phosphor). The values on the vertical axis and the horizontal axis are both relative values.

  In FIG. 7, the light energy density on the horizontal axis of “0” is a state where excitation light is not irradiated. That is, FIG. 7 shows that the phosphor has a relationship in which the light emission efficiency approaches 100% as much as the light energy density of the excitation light approaches zero. In other words, the phosphor used for the phosphor layer 52 has a characteristic that the light emission efficiency decreases as the light energy density of the excitation light increases. This is because the temperature of the phosphor rises due to the concentration of the excitation light, and a light saturation phenomenon occurs because the light energy density of the excitation light applied to the phosphor is too large.

  In the light source device 100A of the present embodiment, a necessary amount of excitation light LB1 is emitted from the first light source 10, and a necessary amount of excitation light LB2 is emitted from the second light source 11, thereby increasing the temperature of the phosphor and light saturation phenomenon. This suppresses a decrease in luminous efficiency due to.

  8-10 is a figure explaining the effect of 100 A of light source devices of this embodiment. 8 to 10, the number of arrows indicating the excitation light LBx, LB1, and LB2 is illustrated in correspondence with the intensity of the excitation light on the phosphor layer 52, and the intensity of the excitation light increases as the number of arrows increases. It is big. In FIGS. 8 to 10, for simplification, a region near the substrate 51 in the phosphor layer 52 is called a first region AR1, and a region far from the substrate 51 in the phosphor layer 52 is a second region AR2. Call it.

(Effect by irradiating from both sides)
First, the effects of irradiating the excitation light LB1 and the excitation light LB2 from both sides of the light emitting element 50A will be described with reference to FIGS.

  As a comparative example, as shown in FIG. 8, with respect to the phosphor layer 52 formed in the light emitting element 50A, one surface (for example, the first surface on the substrate 51 where the phosphor layer 52 is not formed). Consider a case where the excitation light LBx is irradiated from the surface S1). In this case, the excitation light LBx to be irradiated passes through the substrate 51 and the wavelength selection film 56 and is irradiated to the phosphor layer 52.

  At this time, in the phosphor layer 52, the phosphor particles 53 dispersed on the side closer to the wavelength selection film 56 (first region AR1) have more excitation light LBx than the phosphor particles 53 dispersed in the second region AR2. Is absorbed and emits a lot of fluorescence. Accordingly, the phosphor particles 53 dispersed in the first area AR1 generate more heat than the phosphor particles 53 dispersed in the second area AR2. Then, the luminous efficiency of the phosphor particles 53 dispersed in the first region AR1 is lower than that of the phosphor particles 53 dispersed in the second region AR2.

  Further, if the intensity of the excitation light LBx is increased to obtain strong light emission, the light energy density of the excitation light LBx in the first region AR1 increases, and thus the phosphor particles 53 in the first region AR1 exhibit a light saturation phenomenon. Prone to occur.

  Accordingly, in the comparative example shown in FIG. 8, the phosphor particles 53 dispersed in the first region AR1 capable of receiving a large amount of excitation light LBx have a lower luminous efficiency, and the light emitting element 50A as a whole is more efficient. Cannot emit fluorescence.

  On the other hand, as shown in FIG. 9, in the light source device 100A of the present embodiment, the phosphor layer 52 is irradiated with the excitation light LB1 from the substrate 51 side of the phosphor layer 52, that is, from the first surface S1 of the light emitting element 50A. At the same time, the phosphor layer 52 is irradiated with excitation light LB2 from the opposite side of the phosphor layer 52 from the substrate 51, that is, from the second surface S2 of the light emitting element 50A. Here, in the relationship with FIG. 8, the total of the intensity of the excitation light LB1 on the phosphor layer 52 and the intensity of the excitation light LB2 on the phosphor layer 52 is the phosphor layer 52 of the excitation light LBx shown in FIG. It shall be equal to the intensity above. In FIG. 9, the intensity of the excitation light LB1 on the phosphor layer 52 and the intensity of the excitation light LB2 on the phosphor layer 52 are illustrated as being the same.

  In the light source device 100 of the present embodiment, both the intensity of the excitation light LB1 irradiated to the first area AR1 and the intensity of the excitation light LB2 irradiated to the second area AR2 are compared with each other in the first area AR1 in the comparative example. Even if it is smaller than the excitation light LBx irradiated to the light, fluorescence having the same intensity as that of the fluorescence obtained in the comparative example shown in FIG. 8 can be obtained.

  Therefore, both the optical energy density of the excitation light supplied to the first area AR1 and the optical energy density of the excitation light supplied to the second area AR2 are both supplied to the first area AR1 in the comparative example. It can be made lower than the light energy density of light. Therefore, in the light emitting element 50A according to the present embodiment, the light saturation phenomenon is less likely to occur than in the comparative example.

  Further, when the intensity of the excitation light LB1 irradiated to the first area AR1 is weakened, the amount of fluorescent light generated in the first area AR1 is reduced, so that the amount of heat generated simultaneously is reduced. Therefore, in the phosphor particles 53 dispersed in the first region AR1, the amount of generated heat is smaller than that of the comparative example shown in FIG. 8, and the light emission efficiency is not easily lowered due to heat.

  In addition, in the present embodiment, in the comparative example shown in FIG. 8, the phosphor particles 53 in the second region AR2 that were not effectively irradiated with the excitation light are also irradiated with the excitation light LB2 to generate fluorescence. Can be made.

  Therefore, as compared with the comparative example shown in FIG. 8, the irradiation with the excitation light from both sides of the light emitting element 50 </ b> A as compared with the case where the excitation light is irradiated only from one surface side of the light emitting element, It becomes difficult to cause a decrease in luminous efficiency due to the light saturation phenomenon.

  Next, the effect of controlling the intensity of the excitation light LB1 in the phosphor layer 52 to be larger than the intensity of the excitation light LB2 in the phosphor layer 52 will be described using FIG.

  As shown in FIG. 10, the first area AR1 is provided in contact with the wavelength selection film 56, while the second area AR2 is not in contact with the structure on the second surface S2, and is in contact with air. It touches. In such a configuration, the heat H <b> 1 generated in the first region AR <b> 1 is transmitted to the substrate 51 through the wavelength selection film 56. On the other hand, the heat H2 generated in the second area AR2 is radiated into the air or is transmitted to the substrate 51 through the first area AR1. Since the thermal conductivity of the wavelength selection film 56 and the substrate 51, which are structures, is larger than the thermal conductivity of air, the first region AR1 is generated in the first region AR1 when compared with the second region AR2. It can be seen that heat is easier to dissipate.

  Here, in the light source device 100A of the present embodiment, the intensity of the excitation light LB1 incident on the phosphor layer 52 from the first surface S1 is higher than the intensity of the excitation light LB2 incident on the phosphor layer 52 from the second surface S2. Is going to be bigger than that. Therefore, in the phosphor layer 52, the first region AR1 generates a larger amount of heat than the second region AR2, depending on the intensity of the excitation light irradiated. However, since the first region AR1 is more easily dissipated than the second region AR2 as described above, for example, the excitation light LB2 has a larger light amount than the excitation light LB1. It is difficult for heat to be trapped in the phosphor layer 52, and the light emission efficiency is not easily lowered due to heat generation.

  When the performance of the light source device 100A included in the projector PJ of the present embodiment as described above is roughly estimated, it is as follows.

The liquid crystal light valve 300R has a diagonal size of 0.6 inch (12.2 × 9.1 mm) and an aperture ratio of 60%, and the F number of the projection optical system 500 is F2.0. The etendue calculated from the liquid crystal light valve 300R and the projection optical system 500 is 12.5 (mm ² srad). On the other hand, on the light source side, when the light source area (the area of the excitation light LB condensed by the pickup optical system 40) is 1 mm ² and the pickup angle of the pickup optical system 40 is 80 degrees on one side, it is doubled by the polarization conversion element 70. Therefore, the etendue becomes 10.4 (mm ² srad), which can be set smaller than the etendue calculated from the liquid crystal light valve and the projection optical system 500. Therefore, the light utilization efficiency downstream from the light source device 100A is not impaired.

  According to the light source device 100A having the above-described configuration, the amount of light is stabilized by suppressing the temperature rise of the phosphor and the occurrence of the light saturation phenomenon of the phosphor, which cause a decrease in the light emission efficiency. Thus, a light source with high luminous efficiency can be obtained.

  Further, according to the projector PJ having the above-described configuration, the amount of light is stabilized by suppressing the occurrence of the light saturation phenomenon, and unevenness in brightness is suppressed, thereby enabling high-quality image display.

  In the present embodiment, the light emitting element 50A has the wavelength selection film 56. However, even if the wavelength selection film 56 is not provided, the temperature rise of the phosphor that causes a decrease in the light emission efficiency or the fluorescence. It is possible to suppress the occurrence of light saturation of the body, and a light source with high luminous efficiency can be obtained.

  In the present embodiment, the first light source 10 and the second light source 11 are used. For example, only the first light source 10 is used, and the excitation light is on the optical path of the excitation light emitted from the first light source 10. May be divided into two so as to be incident from the first surface S1 and the second surface S2 of the light emitting element 50A.

[Second Embodiment]
FIG. 11 is a schematic cross-sectional view of a light emitting element 50B used in the light source device according to the second embodiment of the present invention. The light emitting element 50B of the present embodiment is partially in common with the light emitting element 50A included in the light source device of the first embodiment. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  As shown in the drawing, the light emitting element 50B selectively transmits the color light in the wavelength band of the excitation light LB1 and reflects the color light in the other wavelength band between the substrate 51 and the phosphor layer 52. A wavelength selective film 57 having a property is provided. Specifically, the wavelength selection film 57 transmits ultraviolet light (for example, light having a wavelength of 405 nm) and reflects light having a longer wavelength than ultraviolet light (for example, light having a longer wavelength than 425 nm). The wavelength selection film 57 having such a configuration can be formed by appropriately selecting the thickness of each dielectric layer to be formed and the refractive index of the material for forming the dielectric layer when forming the dielectric multilayer film. it can.

  The phosphor layer 52 of the light emitting element 50B is formed by dispersing phosphor particles having an absorption band in the ultraviolet region. For example, the YAG phosphor shown in the first embodiment can be suitably used because it has an absorption band in the ultraviolet region.

  In the light source device having such a light emitting element 50B, instead of the first light source 10 included in the light source device 100A of the first embodiment, ultraviolet light (for example, light having a wavelength of 405 nm) is used as a light source that emits the excitation light LB1. Is used. From such a light source, the excitation light LB1 is emitted while controlling the intensity of the excitation light LB1 in the phosphor layer 52 to be greater than the intensity of the excitation light LB2 in the phosphor layer 52.

  In the light source device having the light emitting element 50B having such a configuration, similarly to the light emitting element 50A of the first embodiment, the temperature rise of the phosphor causing the decrease in the light emission efficiency and the occurrence of the light saturation phenomenon of the phosphor are caused. Therefore, the light source can have a higher light emission efficiency than the conventional light source.

  In addition, the excitation light LB1, which is ultraviolet light, does not mix with the fluorescent RG because the ultraviolet light is not perceived by the human eye even if the remainder LB1x that is not absorbed by the phosphor layer 52 is generated. Can be reproduced more faithfully.

  Further, the excitation light LB 2 that is blue light is reflected by the wavelength selection film 57. Therefore, the remaining part LB2x that is not absorbed by the phosphor layer 52 is reflected and transmitted through the phosphor layer 52 again, irradiated to the phosphor particles in the phosphor layer 52, and efficiently converted into fluorescence RG.

  By combining these effects, the light source device having the above-described light emitting element 50 </ b> B can be a light source with higher luminous efficiency than the conventional one.

[Third Embodiment]
FIG. 12 is a schematic cross-sectional view of a light emitting element 50C used in the light source device according to the third embodiment of the present invention. The light emitting element 50C of the present embodiment is partially in common with the light emitting element 50B provided in the light source device of the second embodiment. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 2nd Embodiment, and detailed description is abbreviate | omitted.

  As shown in the figure, the light emitting element 50C has a wavelength selectivity that selectively reflects color light in the wavelength band of the excitation light LB1 and transmits color light in other wavelength bands on the surface of the phosphor layer 52. A two-wavelength selective film 58 is provided. Specifically, the wavelength selection film 58 reflects ultraviolet light (for example, light having a wavelength of 405 nm) and transmits light having a longer wavelength than ultraviolet light (for example, light having a longer wavelength than 425 nm).

  In the light source device having the light emitting element 50C having such a configuration, similarly to the light emitting element 50A of the first embodiment, the temperature rise of the phosphor and the occurrence of the light saturation phenomenon of the phosphor cause a decrease in the light emission efficiency. Therefore, the light source can have a higher light emission efficiency than the conventional light source.

  In addition, the excitation light LB1 that is ultraviolet light is reflected by the wavelength selection film 58 even if the remainder LB1x that is not absorbed by the phosphor layer 52 is generated. Therefore, the remaining portion LB1x that is not absorbed by the phosphor layer 52 is reflected and transmitted through the phosphor layer 52 again, irradiated to the phosphor particles in the phosphor layer 52, and efficiently converted into fluorescence RG.

  Further, the excitation light LB 2 that is blue light is reflected by the wavelength selection film 57. Therefore, the remaining part LB2x that is not absorbed by the phosphor layer 52 is reflected and transmitted through the phosphor layer 52 again, irradiated to the phosphor particles in the phosphor layer 52, and efficiently converted into fluorescence RG.

  By combining these effects, the light source device having the above-described light emitting element 50B can efficiently convert the irradiated excitation lights LB1 and LB2 into the fluorescent light RG, and has a higher light emission efficiency than the conventional light source. It can be.

[Fourth Embodiment]
FIG. 13 is a schematic cross-sectional view showing a configuration in the vicinity of the light emitting element 50D used in the light source device according to the fourth embodiment of the present invention. The light emitting element 50D of the present embodiment is partly in common with the light emitting element 50A included in the light source device of the first embodiment. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  As shown in the figure, the light emitting element 50D selectively transmits the color light in the wavelength band of the excitation light LB1 and reflects the color light in the other wavelength band between the substrate 51 and the phosphor layer 52. A wavelength selective film 59 having the property. Specifically, the wavelength selection film 59 transmits blue light (for example, light having a wavelength of 450 nm), and light having a wavelength longer than that of ultraviolet light (for example, light having a wavelength of 405 nm) and blue light (for example, 480 nm). Longer wavelength light). The wavelength selection film 59 having such a configuration can be formed by appropriately selecting the thickness of each dielectric layer to be formed and the refractive index of the material for forming the dielectric layer when forming the dielectric multilayer film. it can.

  In the light source device having such a light emitting element 50D, ultraviolet light (for example, light having a wavelength of 405 nm) is used as a light source that emits the excitation light LB2 instead of the second light source 11 included in the light source device 100A of the first embodiment. Is used. From such a light source, the excitation light LB2 is emitted while controlling the intensity of the excitation light LB1 in the phosphor layer 52 to be greater than the intensity of the excitation light LB2 in the phosphor layer 52.

  Further, a dichroic mirror (wavelength selection mirror) 31 is provided instead of the dichroic mirror 30 of the first embodiment. The dichroic mirror 31 is obtained by laminating a dielectric multilayer film on the glass surface. The dichroic mirror 31 has wavelength selectivity that selectively reflects color light in the wavelength band of the excitation light LB2 and transmits color light in other wavelength bands. Specifically, the dichroic mirror 31 uses an ultraviolet light reflecting mirror that reflects ultraviolet light and transmits light having a longer wavelength than ultraviolet light (for example, light having a longer wavelength than 425 nm).

  In the light source device having the light emitting element 50D having such a configuration, similarly to the light emitting element 50A of the first embodiment, the temperature rise of the phosphor and the occurrence of the light saturation phenomenon of the phosphor causing the decrease in the light emission efficiency. Therefore, the light source can have a higher light emission efficiency than the conventional light source.

  Further, the excitation light LB2 which is ultraviolet light is reflected by the wavelength selection film 59. Therefore, the remaining part LB2x that is not absorbed by the phosphor layer 52 is reflected and transmitted through the phosphor layer 52 again, irradiated to the phosphor particles in the phosphor layer 52, and efficiently converted into fluorescence RG.

  By combining these effects, the light source device having the above-described light emitting element 50D can be a light source with higher luminous efficiency than the conventional light source device.

  In addition, in the excitation light LB1 that is blue light, the remaining portion LB1x that is not absorbed by the phosphor layer 52 passes through the phosphor layer 52 and leaks, and thus the remaining portion LB1x can be used as illumination light. At this time, by controlling the light amount of the excitation light LB1, the excitation light LB1 that is blue light and the fluorescent light RG that is complementary yellow light of the excitation light LB1 can be mixed and emitted as white light WL. Therefore, a light source device capable of performing full color display without separately preparing a blue light source can be provided.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... 1st light source (excitation light emission means), 11 ... 2nd light source (excitation light emission means), 31 ... Wavelength selection mirror, 40 ... Pickup optical system (condensing means), 51 ... Substrate, 52 ... Phosphor layer 53 ... phosphor particles, 54 ... base material, 56, 57, 59 ... first wavelength selection film, 58 ... second wavelength selection film, 100A ... light source device, 300B ... liquid crystal light valve (light modulation element), 300G ... Liquid crystal light valve (light modulation element), 300R ... Liquid crystal light valve (light modulation element), 500 ... Projection optical system, 501 ... Disc (rotary substrate), 513 ... Recess, 514 ... Inclined surface, LB1, LB2 ... Excitation light , PJ ... projector, RG ... fluorescence,

Claims (11)

Excitation light emitting means for emitting excitation light including first light and second light;
A substrate that transmits at least light having a peak wavelength of the first light;
A phosphor layer that is provided on the substrate and is excited by the excitation light to emit fluorescence having a wavelength different from that of the excitation light,
The excitation light emitting means irradiates the phosphor layer with the first light from the substrate side of the phosphor layer, and emits the second light from the opposite side of the phosphor layer to the substrate. Irradiate the phosphor layer,
The region of the phosphor layer irradiated with the first light overlaps with at least a part of the region of the phosphor layer irradiated with the second light in a plan view,
The light source device, wherein the intensity of the first light on the phosphor layer is greater than the intensity of the second light on the phosphor layer.   A first wavelength selection film that transmits at least light having the peak wavelength of the first light and reflects light having the peak wavelength of the fluorescence is provided between the substrate and the phosphor layer. The light source device according to claim 1.   3. The light source device according to claim 1, wherein the excitation light emitting unit includes a first light source that emits the first light and a second light source that emits the second light. 4. .   The light source device according to claim 3, wherein the wavelength of the first light is different from the wavelength of the second light.   First light that transmits at least light having the peak wavelength of the first light and reflects light having the peak wavelength of the fluorescence and light having the peak wavelength of the second light is transmitted between the substrate and the phosphor layer. The light source device according to claim 4, further comprising a wavelength selection film.   Reflecting light having a peak wavelength of the first light and transmitting light having a peak wavelength of the second light and light having a peak wavelength of the fluorescence on a surface of the phosphor layer opposite to the substrate. The light source device according to claim 4, wherein a second wavelength selection film is provided.   Opposite the phosphor layer, there is provided a wavelength selection mirror that transmits light having the peak wavelength of the first light and light having the peak wavelength of the fluorescence and reflects light having the peak wavelength of the second light. The light source device according to claim 4, wherein the light source device is provided. The first light is visible light;
The light source device according to claim 7, wherein the fluorescent light is a complementary color light of the first light.   The light source device according to claim 1, further comprising a condensing unit that condenses the excitation light on the phosphor layer.   The light source device according to claim 1, wherein the light source is a laser light source array in which a plurality of laser light sources are arranged.   11. A light source device according to claim 1, a light modulation element that modulates light emitted from the light source device, and a projection optical system that projects light modulated by the light modulation element. A projector characterized by that.

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