JP5672949B2 - Light source device and projector - Google Patents

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 causes excitation light to enter the phosphor from the outside and emits the emitted light (fluorescence) obtained. In the light source of Patent Document 1, the total area of the phosphor end faces in the visible light emission direction is set to be smaller than the total area of the excitation light emission end faces. It has been proposed as a light source that can emit light. With this structure, a bright projector with high light utilization efficiency, low cost and low power consumption can be realized.

JP 2004-327361 A

  However, in the light source described in Patent Document 1, if too much light is collected in the phosphor, the light emission amount 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 too much excitation light is collected in the phosphor, the temperature rises due to self-heating, and the light emission efficiency tends to decrease.

  In addition, when the light density of the excitation light is large, the proportion of electrons excited in the phosphor molecules increases, and the number of electrons that can be excited (ground state electrons) decreases. Therefore, light emission according to the amount of excitation light can be achieved. A so-called light saturation phenomenon occurs. This also reduces the light emission efficiency.

  For this reason, even if the amount of excitation light is increased in order to obtain strong light by using a light source as described in Patent Document 1, the light emission efficiency is lowered for the above reason, so that it has been difficult to obtain a desired amount of light.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a light source device capable of suppressing a decrease in light emission efficiency and emitting strong (a large amount of light) light. 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 a light source that emits excitation light, a phosphor layer that emits fluorescence when excited by the excitation light, and condenses the excitation light on the phosphor layer. The excitation light incident surface of the phosphor layer has an inclined surface that is inclined with respect to the central axis of the incident light beam bundle. .
According to this configuration, since the inclined surface is formed on the incident surface of the phosphor layer, the irradiation area of the excitation light at the position where the excitation light is irradiated is expanded. The light density of the excitation light decreases. Therefore, in the light source device having such a phosphor layer, it is possible to suppress a decrease in light emission efficiency due to heating due to light irradiation or a light saturation phenomenon. The “inclined surface” in the present invention excludes an inclination due to a surface profile that is unintentionally formed during manufacturing.

  In the present invention, it is desirable that a concave portion whose opening area gradually decreases in the depth direction of the phosphor layer is formed on the surface of the phosphor layer, and the inclined surface is formed by the inner wall of the concave portion. .

  According to this configuration, by forming the concave portion on the surface of the phosphor layer, an inclined surface can be formed on the surface of the phosphor layer, and the light density of the excitation light can be reduced.

  Further, the fluorescence emitted from the phosphor layer irradiated with the excitation light is emitted isotropically without directivity. Therefore, if the light density is reduced as described above by forming a convex portion in the phosphor layer instead of the concave portion, fluorescence is emitted isotropically from the slope of the convex portion and spreads around. . On the other hand, if the light emitting part is a recess and has inclined surfaces facing each other, the fluorescence emitted from one inclined surface is reflected by the opposite inclined surface and emitted to the outside. It is possible to emit strong light from an even smaller area than directly using an excitation light source.

  Therefore, it is possible to provide a light source device that can suppress a decrease in light emission efficiency and emit strong light from a small area.

  In the present invention, the phosphor layer is formed on a substrate, and the surface of the substrate on which the phosphor layer is formed has a recess whose opening area gradually decreases in the depth direction of the substrate. It is good also as the said inclined surface being formed in the surface of the said fluorescent substance layer by forming and forming the said fluorescent substance layer along the inner wall of the said recessed part.

  According to this configuration, the phosphor layer itself is bent to reflect the surface shape of the substrate and the inclined surface is formed, whereby the light density of the excitation light can be reduced. In addition, since the inclined surface is formed along the concave portion of the substrate, it has inclined surfaces that face each other, suppresses the spread of fluorescence, and emits strong light from a smaller area than directly using the excitation light source. It is possible to inject. Therefore, it is possible to provide a light source device that can suppress a decrease in light emission efficiency and emit strong light from a small area.

In the present invention, it is desirable that a plurality of the recesses be formed on the surface of the phosphor layer.
According to this configuration, the irradiation area of the excitation light can be further increased, and the light density of the excitation light at the position where the excitation light is irradiated can be further reduced. In addition, when a plurality of recesses are formed on the surface of the phosphor layer, the adjacent recesses are connected in a “畝” shape to form a protrusion. Unlike a simple protrusion (for example, a weight), the protrusion is difficult to trap heat at the tip, and the conversion efficiency due to heating is unlikely to decrease. Therefore, it can be set as the light source device which suppressed the fall of luminous efficiency.

In the present invention, it is desirable that the plurality of recesses be periodically formed in a two-dimensional direction at intervals larger than the average particle diameter of the phosphor particles contained in the phosphor layer.
According to this configuration, the phosphor particles are also dispersed in the ridges between adjacent recesses in the phosphor layer. Therefore, the excitation light whose light density is reduced by being refracted on the inclined surface of the recess is irradiated to the phosphor particles with the reduced light density. Therefore, it is possible to obtain a light source device that can satisfactorily suppress a decrease in light emission efficiency due to a light saturation phenomenon.

In the present invention, it is desirable that the plurality of recesses be arranged without gaps when viewed from the incident surface side of the phosphor layer.
According to this configuration, the excitation light is always applied to the inclined surface, and it is possible to reliably suppress a decrease in light emission efficiency.

In the present invention, it is preferable that the sum of the elevation angle of the inclined surface and the light collection angle of the light collecting means is less than 90 degrees.
According to this configuration, the excitation light is less likely to be blocked by the protrusions between the recesses, and the excitation light can easily reach the bottom of the recesses. Can emit light. Therefore, it is possible to effectively suppress a decrease in light emission efficiency.

In the present invention, it is desirable that the phosphor layer is formed on the rotating substrate along the rotating direction of the rotating substrate.
According to this configuration, since the irradiation point of the excitation light is not fixed to one point, the heat generated in the phosphor layer by the irradiation of the excitation light can be dissipated in a wide region along the circumferential direction, and the luminous efficiency by heating can be reduced. The decrease can be suppressed.

In the present invention, it is desirable that the concave portion has a shape in plan view similar to the spot shape of the excitation light to be irradiated, and the area in plan view is equal to or larger than the area of the spot.
According to this configuration, if the spot position of the excitation light and the recess are relatively fixed, the excitation light can be irradiated into the recess without waste, so the light density of the excitation light is reduced and the luminous efficiency is reduced. It can be set as the light source device which can suppress the fall of this. For example, when the spot shape of excitation light is circular, it is good to make it an inverted conical recessed part.

  Further, as a result of the inventors' investigation, it has been found that it is more effective that the inclined surface of the recess is a flat surface than a curved surface. Therefore, in the present invention, it is desirable that the inclined surface has a certain inclination.

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 amount of 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 part contained in a light source device. It is a side view of the light source part 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 of 1st Embodiment. It is the graph which showed the luminous efficiency of the fluorescent substance with respect to the light density of excitation light. It is a schematic diagram which shows the structure of the light emitting element of a comparative example. It is a schematic diagram which shows the structure of the light emitting element of 1st Embodiment. It is explanatory drawing which shows the relationship between the magnitude | size of fluorescent substance particle, and the pitch of a recessed part. It is a graph which shows the relationship of the excitation light density and fluorescence emission efficiency with respect to the angle of a slope. It is explanatory drawing explaining the heat_generation | fever state of the slope according to the incident angle of excitation light. It is a schematic perspective view of the light emitting element used for the light source device which concerns on 2nd Embodiment. It is a schematic sectional drawing of the light emitting element used for the light source device which concerns on 3rd 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 first light source device 100A, a second light source device 100B, 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, and a color composition element. 400 and a projection optical system 500. Note that the configuration included in the first light source device 100A corresponds to the light source device of the present invention.

  The projector PJ generally operates as follows. The light emitted from the first light source device 100A is separated into red light R and green light G by the dichroic mirror 200. Further, blue light B is emitted from the second light source device 100B. 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 100A includes a light source unit 10A, a collimating optical system 20A, a dichroic mirror 30, a pickup optical system (condensing means) 40, a light emitting element 50A, a condensing optical system 60, a polarization conversion element 70, a rod integrator 80, and a collimating lens. 90 are arranged in this order on the optical path. The light source device 100A is configured to emit fluorescence used as illumination light of the liquid crystal light valve from the phosphor layer 52 included in the light emitting element 50 by irradiating the light emitting element 50A with excitation light emitted from the light source unit 10A. ing. As will be described later, an inclined surface is formed on the surface (incident surface) of the phosphor layer 52.

  FIG. 2 is a front view of the light source unit 10A. As shown in the figure, the light source unit 10A is a laser light source array in which laser light sources 12 are arranged on a base 11 in a two-dimensional array (5 in total) in a square shape of 5 × 5. As shown in FIG. 3, the excitation light emitted from the light source unit 10A is collimated by the collimator lens array 21 included in the collimating optical system 20A, collected by the condenser lens 23, and then transmitted through the collimating lens 25. By doing so, the beam bundle is narrowed as the whole excitation light.

  The light source unit 10A emits blue (light emission intensity peak: about 445 nm, see FIG. 4A) laser light as excitation light for exciting a fluorescent material included in the light emitting element 50A described later. In FIG. 4A, reference numeral LB denotes a color light component emitted from the light source unit 10A as excitation light. The light source unit 10A may use only one laser light source instead of the laser light source array as shown in FIGS. 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. In FIG. 1, excitation light emitted from the light source unit 10 </ b> A is indicated by a symbol LB.

  The excitation light transmitted 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 colored light in the wavelength band of excitation light and transmits colored light in 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). The excitation light is incident on 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 LB reflected by the dichroic mirror 30, and condenses the excitation light LB on the light emitting element 50A.

  The light collection angle of the pickup optical system 40 is, for example, a maximum of 25 degrees. In addition, on the light emitting element 50A, the individual spots of the laser light source 12 included in the light source unit 10A are set so that the condensing positions do not completely overlap. For example, the spots of the respective laser light sources 12 as a whole are set. It is configured to draw a substantially square shape of 1 mm square. In the following description, the “spot” or “beam spot” of the excitation light indicates the entire spot of the laser light source 12 included in the light source unit 10A (in the above example, the entire spot having a substantially square shape).

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

  The light emitting element 50A includes a plate-like substrate 51 and a phosphor layer 52 formed on the surface of the substrate 51 on the excitation light incident side. The phosphor layer 52 has phosphor particles that emit fluorescence, and functions to absorb excitation light (blue light) and convert it into yellow (emission intensity peak: about 550 nm, see FIG. 4B). Have 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 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, and emitting one of the p-polarized light and the s-polarized light with the same polarization direction as that of the other polarized light. Yes.

  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 symbol P2 in the figure) and reflects the 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. The direction is changed in the same direction as the traveling direction of the p-polarized light and transmitted through the λ / 2 retardation film 73 to be emitted as substantially parallel light aligned with the p-polarized light (indicated by reference numeral P1 in the figure). 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 second light source device 100B includes a light source unit 10B 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 light source unit 10B, and a condensing optical system 60, a polarization conversion element 70, and a rod integrator similar to the light source device 100A. 80 and the collimating lens 90 are arranged in this order on the optical path. That is, the light source device 100B is configured to emit blue light used as illumination light for the liquid crystal light valve.

  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 blue light B emitted from the light source device 100B 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 perspective view, and FIG. 6B is a schematic cross-sectional view.

  As shown in the drawing, the light emitting element 50A has a phosphor layer 52 formed on one surface of a plate-like substrate 51, and a plurality of concave portions 53 are periodically formed in the two-dimensional direction on the surface of the phosphor layer 52. Is formed. Each concave portion 53 has a rectangular shape in plan view, and has an inverted quadrangular pyramid shape in which the opening area gradually decreases in the depth direction of the phosphor layer 52, and from the incident surface side of the excitation light LB of the phosphor layer 52. Seen, they are arranged without gaps.

  Further, the inner wall (inclined surface) 53 a of the recess 53 is an inclined surface that is inclined with respect to the central axis LBs of the light beam of the excitation light LB incident on the recess 53. Further, since the recesses 53 are formed adjacent to each other, a space between the recesses 53 is a ridge 53b.

  The base 51 has a surface that reflects blue light, which is excitation light, and as a forming material, for example, a formation having light reflectivity such as a metal (including a semi-metal) substrate such as an aluminum substrate or a silicon substrate. It is possible to use a material plate material, or a surface of a plate material of a light-transmitting forming material such as quartz glass, crystal, sapphire (single crystal corundum), transparent resin, or the like. It is assumed that the base 51 of the present embodiment is formed using an aluminum substrate.

  The phosphor layer 52 includes a plurality of phosphor particles 55 and a base material 56 that embeds the phosphor particles 55.

  The phosphor particles 55 are particulate fluorescent materials that absorb the excitation light LB emitted from the light source unit 10A shown in FIG. 1 and emit fluorescence RG. For example, the phosphor particles 55 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 emitted from the light source unit 10A is emitted from the red wavelength band to the green color. The light is converted into light including the wavelength band and emitted. As such phosphor particles 55, 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 55, 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 material for forming the phosphor particles 55 may be one type, or a mixture of particles formed using two or more types of forming materials may be used as the phosphor particles 55.

  Here, the average particle diameter of the phosphor particles 55 can be measured by 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.

  As a material for forming the substrate 56, 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.

  In the light emitting element 50A of the present embodiment, the inverted quadrangular pyramid array has a pitch of 100 μm, a height of 100 μm, and an inclined surface angle of about 63 degrees. In such a light emitting element 50A, for example, a transparent resin precursor in which phosphor particles are dispersed is applied to an aluminum substrate that is a base 51, and a mold engraved with an inverted quadrangular pyramid array pattern is pressed to form a mold. In the transferred state, the precursor can be cured to form the phosphor layer 52.

  When the phosphor layer 52 having such a surface shape is irradiated with the excitation light LB collected by the pickup optical system 40 shown in FIG. 1, the phosphor particles contained in the phosphor layer 52 emit fluorescence RG. To emit.

  Here, when the phosphor layer 52 is irradiated with the excitation light LB, the fluorescence RG can be obtained. However, the larger the irradiation amount of the excitation light LB with respect to the phosphor layer 52, the better. FIG. 7 is a graph showing the luminous efficiency of the phosphor (phosphor particles) of the phosphor layer 52 with respect to the light density of the excitation light to be irradiated. In the figure, the horizontal axis represents the light 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 irradiated to the phosphor). . The values on the vertical axis and the horizontal axis are both relative values.

  In the figure, the light 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 density of the excitation light decreases as the light density approaches the origin, and the light emission efficiency approaches 100% as much. In other words, the phosphor used for the phosphor layer 52 has a characteristic that the light emission efficiency decreases as the light density of the excitation light irradiated increases. This is because the concentration of the excitation light increases the temperature of the phosphor, and the light saturation phenomenon occurs because the amount of excitation light for the phosphor is too large.

  Here, as shown in FIG. 8, when the light emitting element included in the projector PJ is a light emitting element 50x including a phosphor layer 54 with no unevenness on the surface (FIG. 8A), FIG. As shown in b), the excitation light LB is not refracted when entering the base material 56 of the phosphor layer 54, or only slightly bent at a slight angle, so that a large change in light density occurs. There is no. For this reason, the phosphor particles 55 are excited by the excitation light LB that maintains the light density to emit light.

  On the other hand, as shown in FIG. 9, like the light emitting device 50A of the present embodiment, a plurality of inverted quadrangular concave portions 53 are formed on the surface of the phosphor layer 52, and have a slope 53a facing each other. If there is (FIG. 9A), as shown in FIG. 9B, the irradiated excitation light LB is refracted by the inclined surface 53a when entering the phosphor layer 52, so The light density is reduced compared with that before incidence. Therefore, since the phosphor particles 55 are excited by the excitation light LB whose light density is reduced, it is possible to suppress the temperature rise and the light saturation phenomenon of the phosphor particles.

  According to the inventors' investigation, it has been found that the inclined surface 53a is more effective in suppressing the reduction in luminous efficiency than the curved surface is a flat surface having a certain inclination.

  Here, it can be considered that the surface area of the phosphor layer 52 is increased in the light emitting element 50 </ b> A by forming the concave portion 53. In the case of aiming to increase the surface area of the phosphor layer 52, it seems that the same effect can be obtained by providing a plurality of convex portions. However, by forming the concave portion 53, the following is achieved. An effect is produced.

  First, when the light emitting element has a plurality of convex portions having a quadrangular pyramid shape in which the concave and convex portions 53 and the concave portions 53 of the light emitting element 50A of the present embodiment are reversed, when the excitation light is irradiated, each convex portion The excitation light is refracted on the slope and enters the convex portion. At this time, in the convex portion, excitation light is incident from the entire periphery in a plan view, so that irradiation of the excitation light is concentrated on the phosphor particles in the convex portion, and a light saturation phenomenon is likely to occur.

  On the other hand, as a result of forming a plurality of recesses on the surface of the phosphor layer as in the light emitting element 50A of the present embodiment, if the adjacent recesses are connected in a “畝” shape to form a protrusion, The excitation light is refracted at the part (slope of the concave part) and enters the convex part. However, in the ridge, excitation light is incident only from the direction intersecting the extending direction of the ridge in plan view, so that the excitation light is less likely to concentrate on the phosphor particles in the ridge, and the light saturation phenomenon It is hard to produce. Therefore, it is preferable to form a recess on the surface of the phosphor layer 52.

  Further, the fluorescence RG emitted from the phosphor layer 52 irradiated with the excitation light LB is isotropically emitted without directivity. For this reason, if a convex portion is formed in the phosphor layer 52 instead of the concave portion, fluorescence is emitted isotropically from the slope of the convex portion and spreads around. However, since the concave portion 53 has the inclined surfaces 53a facing each other, the fluorescent RG emitted from the one inclined surface 53a is reflected by the opposing inclined surface 53a and emitted to the outside, so that the fluorescence RG expands. Can be suppressed. Therefore, it is possible to emit strong light from a smaller area than directly using the light source of the excitation light LB.

Such a light emitting element 50A has (i) the size of the phosphor particles contained in the phosphor layer 52 and the pitch (interval) of the recesses 53 in order to suppress the temperature rise and light saturation phenomenon of the phosphor. And (ii) the angle of the slope 53a of the phosphor layer 52 is controlled and created. Further, in the relationship with the pickup optical system 40 shown in FIG. 1, (iii) the relationship between the incident angle of the excitation light incident on the phosphor layer 52 and the angle of the inclined surface 53a of the phosphor layer 52 is taken into consideration. Designed above.
These will be described in detail below.

(Relationship between phosphor particle size and recess pitch)
First, in the light emitting element 50A of the present embodiment, the pitch of the recesses 53 (L1: 100 μm) is sufficiently larger than the average particle diameter (10 μm) of the phosphor particles 55. When both are in such a relationship, as shown in FIG. 10A, phosphor particles 55 x that enter the inside of the ridges 53 b formed between the adjacent recesses 53 are generated. The phosphor particles can be irradiated in a state where the light is evenly distributed and the light density is reduced.

  On the other hand, as shown in FIG. 10B, when the pitch (L2) of the recesses 53 is smaller than the average particle diameter of the phosphor particles 55, the phosphor particles 55x are difficult to enter the ridges 53b. Then, the excitation light LB refracted on the inclined surface 53a is condensed and irradiated to the phosphor particles 55x embedded under the protruding line portion 53b while overlapping. In such an irradiation state of the excitation light LB, it is difficult to irradiate the phosphor particles 55 in a state where the light density is reduced, and overheating due to self-heating and a light saturation phenomenon are likely to occur.

  In addition, since it is a comparison between the “average particle diameter” of the phosphor particles and the pitch of the recesses 53, it is considered that the phosphor particles as a whole include those that enter the ridges 53b. However, since the amount of light emitted from the phosphor layer 52 correlates with the volume of the phosphor particles irradiated with the excitation light, the amount of the phosphor particles is small enough to enter the ridges 53b. It is considered that the reduction in light saturation is not suppressed enough.

  In addition, the formation of the fine recess 53 enlarges the area of the portion that emits fluorescence as compared with the case where the fine recess 53 is not present, compared to the focused spot of the excitation light. For this reason, if the pitch is too large, the diameter of the focused spot is enlarged, and the efficiency in the optical system on the downstream side is reduced.

  In the present embodiment, the size of the condensing spot of the excitation light LB via the pickup optical system 40 shown in FIG. 1 is 1 mm square, whereas the pitch of the fine recesses 53 is about 1/10, which is 100 μm. Therefore, there is little influence of efficiency reduction due to the expansion of the spot diameter. At this level, it is not necessary to align the collected light flux with the pattern.

  In addition, if the pitch of the recesses 53 is too large, the height (the thickness of the phosphor) also increases, causing a problem that the heat dissipation to the base 51 is deteriorated and the light emission efficiency is lowered, but about 100 μm. Such a problem is unlikely to occur at a pitch of.

(Slope angle of phosphor layer)
FIG. 11 shows the relationship between the light density of excitation light (FIG. 11A) and the luminous efficiency of fluorescence (FIG. 11B) with respect to the angle of the slope 53a of the recess 53 formed on the surface of the phosphor layer 52. It is a graph to show. Here, the refractive index of the resin forming the base material 56 of the phosphor layer 52 is calculated as 1.42. The “inclined angle” is 0 degree when there is no recess on the surface of the phosphor layer 52, and the elevation angle of the inclined surface 53a formed in the phosphor layer 52 is adopted.

  As shown in the figure, when the angle of the slope is larger than 45 degrees, the light density is increased (20% or more) and reduced (FIG. 11A), and as a result, the phosphor layer having a flat surface (0 degrees). It can be seen that the luminous efficiency is 76% at 45 degrees, and the luminous efficiency is improved by several percent compared to the case where the light is irradiated with excitation light (luminous efficiency 72%) (FIG. 11B). Furthermore, as in the light emitting element 50A of the present embodiment, it is preferable that the angle of the slope exceeds 60 degrees because the light emission efficiency is improved by 10% or more (light emission efficiency of 79% at 60 degrees).

(Relationship between incident angle of excitation light and angle of slope of phosphor layer)
FIG. 12 is an explanatory diagram for explaining a heat generation state on the inclined surface 53a when the incident angle of the excitation light LB incident on the phosphor layer 52 is varied.

  First, in the light emitting element 50A of the present embodiment, the angle (elevation angle) of the inclined surface 53a of the recess 53 is 63 degrees, and the condensing angle of the pickup optical system 40 shown in FIG. That is, the sum of the angle of the slope 53a and the maximum condensing angle of the excitation light LB is 88 degrees and is set so as not to exceed 90 degrees.

  FIG. 12A is an explanatory diagram illustrating a case where the sum of the angle θ of the inclined surface 53a and the maximum condensing angle φ1 of the excitation light LB does not exceed 90 degrees. Thus, when the sum does not exceed 90 degrees, the excitation light LB is irradiated to all the inclined surfaces 53a, and the light does not concentrate. Therefore, it is possible to suppress the temperature rise and light saturation phenomenon of the phosphor particles.

  On the other hand, as shown in FIG. 12B, when the sum of the angle θ and the maximum condensing angle φ2 exceeds 90 degrees, the excitation light LB concentrates on the upper portion of the slope 53a (indicated by the symbol AR1 in the figure). End up. Further, the lower part of the slope 53a (indicated by the symbol AR2 in the figure) becomes a shadow of the convex part 53b, and the amount of the excitation light irradiated is reduced. For this reason, the temperature of the phosphor particles and the light saturation phenomenon are likely to occur at the upper part, while the amount of excitation light is insufficient at the lower part, and there is a possibility that effective light emission cannot be performed.

  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 occurrence of the light saturation phenomenon, and the light source can have a higher light emission efficiency than the conventional one.

  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 shape of the recess 53 in plan view is rectangular. However, the shape is not limited to this as long as it is a shape that can be disposed on the surface of the phosphor layer 52 without any gap. It is good also as being a recessed part which has a planar view shape. Moreover, it is not necessary that the shapes in plan view are all the same, and the concave portions may be spread on the surface of the phosphor layer 52 by combining concave portions of a plurality of types.

[Second Embodiment]
FIG. 13 is a schematic perspective 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 includes a disc (rotary substrate) 501 and a single phosphor layer 502 formed continuously on the disc 501 in the circumferential direction. A plurality of recesses are formed on the surface of the phosphor layer 502 as in the first embodiment. In addition, a motor 504 is connected to the center of the disc 501 via a rotating shaft 503 set in parallel with the central axis of the beam bundle of the excitation light LB that is incident light, and can rotate around the rotating shaft 503. Is provided.

  Further, the focal position (beam spot BS) of the excitation light LB collected by the pickup optical system 40 is disposed so as to overlap the phosphor layer 502. For example, the diameter of the disc 501 is 50 mm, and the phosphor layer 502 is provided at a position approximately 22.5 mm away from the center of the disc 501 in plan view, and the excitation light LB is formed on the phosphor layer 502. Is provided so as to be incident.

  The motor 504 rotates the light emitting element 50A at 7400 rpm, for example. In this case, the beam spot BS moves at about 18 m / sec on the phosphor layer 502. That is, the motor 504 functions as a position displacement unit that displaces the position of the beam spot on the light emitting element 50A. Thereby, since the excitation light LB does not continue to irradiate the same position on the light emitting element 50A, the thermal deterioration of the irradiation position can be prevented, and the heat dissipation can be dramatically increased, thereby extending the life of the apparatus. it can.

  In the present embodiment, the beam spot BS is 1 mm square, whereas the pitch of the recesses formed on the surface of the phosphor layer 502 is about 100 μm and 1/10. Therefore, the pattern is rotated and moved. However, increasing the spot diameter is not a problem.

  Even in the light source device having such a light emitting element 50B, the amount of light is stabilized by suppressing the occurrence of the light saturation phenomenon, and the light source can have a higher light emission efficiency than the conventional one.

[Third Embodiment]
FIG. 14 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 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 FIG. 14A, the light emitting element 50 </ b> C is provided on the surface of the recess 513 with a base 511 having an inverted square pyramid-shaped recess 513 whose opening area gradually decreases in the depth direction. A phosphor layer 512. The concave portion 513 has a square shape with a side of 1 mm in plan view, and has a shape similar to the spot shape of the excitation light LB collected by a pickup optical system (not shown). In addition, the planar view area of the recess 513 is designed to be approximately the same as the spot area of the excitation light LB. The depth is 1 mm.

  The phosphor layer 512 is formed by applying a transparent resin that embeds the above-described phosphor particles in the recess 513. By forming the phosphor layer 512 along the inner wall of the recess 513, the surface of the phosphor layer 512 is bent and an inclined surface 514 is formed. The spot position of the excitation light LB is adjusted to the phosphor layer 512.

  Such a light emitting element 50C can be manufactured at low cost because it is not necessary to form a fine shape like the light emitting element 50A of the first embodiment and the light emitting element 50B of the second embodiment. Further, since the thickness of the phosphor layer 512 can be constant and thin, heat dissipation is good, and efficiency reduction due to temperature rise can be prevented. Furthermore, since the spot diameter does not increase, the light utilization efficiency does not decrease.

  In the present embodiment, the planar view area of the recess is approximately the same as the spot area of the excitation light LB. However, the planar view area of the recess may be larger than the spot area of the excitation light LB. Since the excitation light LB can be swallowed into the recess, the light density of the excitation light LB can be effectively reduced.

  Further, in the present embodiment, the shape of the recess in plan view is a quadrangle, but the shape of the recess in plan view may be circular. Such a recessed part is realizable by making it into an inverted conical recessed part, for example, as shown in FIG.14 (b). In this case, since the excitation light can be effectively used even if the beam spot of the excitation light LB is circular, for example, a high output single light source can be used without using a laser array as a light source of the excitation light. The light source may be used.

  Even in the light source device having such a light emitting element 50C, the amount of light is stabilized by suppressing the occurrence of the light saturation phenomenon, and the light source can have a higher light emission efficiency than the conventional one.

  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.

  For example, in the above-described embodiment, the phosphor layer is formed on the surface of the flat substrate in the first embodiment and the second embodiment, and a plurality of recesses are formed in the phosphor layer. It is good also as providing a recessed part only. In the third embodiment, the phosphor layer is bent at one location by forming the phosphor layer on the surface of the substrate having one recess. However, the surface of the substrate having a plurality of recesses is formed on the surface of the substrate. A phosphor layer may be formed and the phosphor layer may be bent at a plurality of locations.

DESCRIPTION OF SYMBOLS 12 ... Laser light source (light source part), 40 ... Pickup optical system (condensing means), 51 ... Substrate, 52, 502, 512 ... Phosphor layer, 53 ... Recess, 53a ... Inner wall (inclined surface), 55 ... Phosphor Particles 56 ... Base material, 100A, 100B ... 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 ... concave portion, 514 ... inclined surface, LB ... excitation light, PJ ... projector, RG ... fluorescence,

Claims (15)

A light source that emits excitation light;
A phosphor layer that emits fluorescence when excited by the excitation light;
Condensing means for condensing the excitation light on the phosphor layer,
The incident surface of the excitation light in the phosphor layer has an inclined surface that is inclined with respect to the central axis of the incident light beam of the excitation light,
On the surface of the phosphor layer, a recess whose opening area gradually decreases in the depth direction of the phosphor layer is formed, and the inclined surface is formed by the inner wall of the recess,
A plurality of the recesses are formed on the surface of the phosphor layer,
The plurality of recesses are arranged without gaps when viewed from the incident surface side of the phosphor layer ,
The light source device , wherein the plurality of recesses are periodically formed in a two-dimensional direction at intervals larger than an average particle diameter of the phosphor particles contained in the phosphor layer . A light source that emits excitation light;
A phosphor layer that emits fluorescence when excited by the excitation light;
Condensing means for condensing the excitation light on the phosphor layer,
The incident surface of the excitation light in the phosphor layer has an inclined surface inclined with respect to the central axis of the incident light beam bundle of the excitation light,
The phosphor layer is formed on a substrate, and a concave portion whose opening area gradually decreases in the depth direction of the substrate is formed on a surface of the substrate on which the phosphor layer is formed, and an inner wall of the concave portion The inclined surface is formed on the surface of the phosphor layer by forming the phosphor layer along
A plurality of the recesses are formed on the surface of the phosphor layer,
The plurality of recesses are arranged without gaps when viewed from the incident surface side of the phosphor layer ,
The light source device , wherein the plurality of recesses are periodically formed in a two-dimensional direction at intervals larger than an average particle diameter of the phosphor particles contained in the phosphor layer . The phosphor layer on a rotating substrate, a light source apparatus according to claim 1 or 2, characterized in that it is formed along the rotation direction of the rotary substrate. A light source that emits excitation light;
A phosphor layer that emits fluorescence when excited by the excitation light;
Condensing means for condensing the excitation light on the phosphor layer,
The incident surface of the excitation light in the phosphor layer has an inclined surface that is inclined with respect to the central axis of the incident light beam of the excitation light,
On the surface of the phosphor layer, a recess whose opening area gradually decreases in the depth direction of the phosphor layer is formed, and the inclined surface is formed by the inner wall of the recess,
The light source device characterized in that the concave shape of the concave portion is similar to the spot shape of the excitation light to be irradiated, and the planar view area is equal to or larger than the area of the spot. A light source that emits excitation light;
A phosphor layer that emits fluorescence when excited by the excitation light;
Condensing means for condensing the excitation light on the phosphor layer,
The incident surface of the excitation light in the phosphor layer has an inclined surface that is inclined with respect to the central axis of the incident light beam of the excitation light,
The phosphor layer is formed on a substrate, and a concave portion whose opening area gradually decreases in the depth direction of the substrate is formed on a surface of the substrate on which the phosphor layer is formed, and an inner wall of the concave portion The inclined surface is formed on the surface of the phosphor layer by forming the phosphor layer along
The light source device characterized in that the concave shape of the concave portion is similar to the spot shape of the excitation light to be irradiated, and the planar view area is equal to or larger than the area of the spot. A light source that emits excitation light;
A phosphor layer that emits fluorescence when excited by the excitation light;
Condensing means for condensing the excitation light on the phosphor layer,
The incident surface of the excitation light in the phosphor layer has an inclined surface that is inclined with respect to the central axis of the incident light beam of the excitation light,
The inclination of the inclined surface has a certain inclination,
The light source device, wherein a sum of an elevation angle of the inclined surface and a light collection angle of the light collecting means is less than 90 degrees. Wherein the surface of the phosphor layer, claim wherein the opening area in the depth direction of the phosphor layer is gradually reduced to recesses formed, characterized in that the inclined surface by an inner wall of said recess is formed 6 The light source device according to 1. The phosphor layer is formed on a substrate, and a concave portion whose opening area gradually decreases in the depth direction of the substrate is formed on a surface of the substrate on which the phosphor layer is formed, and an inner wall of the concave portion The light source device according to claim 6 , wherein the inclined surface is formed on a surface of the phosphor layer by forming the phosphor layer along the surface. Wherein the surface of the phosphor layer, the light source apparatus according to claim 7 or 8, wherein a plurality of said recesses are formed. The light source device according to claim 9 , wherein the plurality of recesses are periodically formed in a two-dimensional direction at intervals larger than an average particle diameter of the phosphor particles included in the phosphor layer. 11. The light source device according to claim 10 , wherein the plurality of recesses are arranged without gaps when viewed from the incident surface side of the phosphor layer. The phosphor layer on a rotating substrate, a light source device according to any one of claims 7 to 11, characterized in that it is formed along the rotation direction of the rotary substrate. The recess, in plan view shape is a similar figure to the excitation light of the spot shape to be irradiated, according to claim 7 or 8 in plan view area, wherein the at area of the spot equal to or greater than Light source device. The light source device according to any one of claims 1 to 13 , wherein the light source is a laser light source array in which a plurality of laser light sources are arranged. Comprising a any one of the light source apparatus of claims 1 14, a light modulation element for modulating light emitted from the light source device, and a projection optical system that projects the light modulated by the light modulation device A projector characterized by that.

Images