JP2012098438A - Wavelength conversion element, light source device, and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent body wheel, a light source device, and a projector that can inhibit reduction of light use efficiency as a whole system including the fluorescent body wheel.SOLUTION: A wavelength conversion element includes a wheel substrate 31 as a substrate, a light emitting element 40 including a fluorescent body layer 41 provided on the substrate and including a fluorescent body 100 and a light transmission layer 42 provided opposite to the substrate of the fluorescent body layer 41, and a first reflection part 43a provided on a first lateral surface 34a of the light emitting element 40 crossing an interface between the fluorescent body layer 41 and the light transmission layer 42, which first reflection part 43a reflects a light advancing parallel to the substrate in an inside of the fluorescent body layer 41 in a direction opposite to the substrate.

Description

  The present invention relates to a wavelength conversion element, a light source device, and a projector, and more particularly to a phosphor wheel that generates fluorescence.

  In recent years, lasers have attracted attention as a light source with a wide color gamut and high efficiency for improving the performance of projectors. 2. Description of the Related Art Conventionally, as one of light source devices used in projectors, a light source device that uses laser light as excitation light and generates fluorescence having a wavelength different from that of the excitation light has been proposed. An increase in the temperature of the phosphor layer containing the phosphor due to the irradiation of the excitation light may cause a decrease in the generation efficiency of the fluorescence and an acceleration of the deterioration of the phosphor layer. In response to this problem, for example, by rotating a phosphor wheel provided with a phosphor layer on a wheel substrate, the energy of excitation light incident on the phosphor layer is dispersed, and the temperature rise of the phosphor layer is suppressed. Techniques for achieving this have been proposed (see, for example, Patent Documents 1 and 2).

JP 2009-277516 A JP 2010-86815 A

  The phosphor layer of the phosphor wheel is provided in a wide range with respect to the spot that is the irradiation region of the excitation light. The phosphor (phosphor crystal) dispersed in the phosphor layer emits the generated fluorescence isotropically. Since the phosphor layer has a predetermined thickness, the fluorescent component having a large angle with respect to the surface normal of the wheel substrate propagates to the outside of the excitation light irradiation region of the phosphor layer. Fluorescence propagated outside the irradiation region of the excitation light is further scattered by being incident on a phosphor existing ahead. When fluorescence propagates toward the outside of the irradiation region due to repeated scattering in the phosphor layer, the light emission area in the phosphor wheel increases. That is, etendue increases. The increase in the light emission area in the phosphor wheel increases the light that is not taken in by the optical system behind the light source device, and causes a reduction in the light utilization efficiency of the entire system including the phosphor wheel.

  Generally, a material having a refractive index higher than that of air is used as the binder for holding the phosphor in the phosphor layer. Light that has entered the interface between the phosphor layer and air at an angle greater than the critical angle from the phosphor layer side returns to the phosphor layer by total reflection at the interface. The component of the fluorescence that is totally reflected at the interface propagates inside the phosphor layer and is scattered by the phosphor existing ahead. Even by such total reflection at the interface, an increase in the light emitting area occurs. In addition, the fluorescence that has been totally reflected at the interface between the phosphor layer and the air and returned to the phosphor layer is absorbed by the phosphor, and the phosphor layer generates heat, resulting in a decrease in light emission efficiency.

  The light emitted from the phosphor layer exhibits an angular distribution close to Lambert radiation. Light emitted from the phosphor layer at a large angle with respect to the normal of the phosphor emitting surface of the phosphor layer is difficult to capture sufficiently by a pickup lens or a light guide provided on the emission side of the phosphor layer. As a result, the light utilization efficiency decreases.

  An object of the present invention is to provide a wavelength conversion element, a light source device, and a projector capable of solving at least one of the above-described problems and improving the light utilization efficiency of the entire system including a phosphor wheel. To do.

  In order to solve the above-described problems and achieve the object, a wavelength conversion element according to the present invention includes a substrate, a phosphor layer provided on the substrate, and a phosphor layer including the phosphor, and the phosphor layer opposite to the substrate. A light-transmitting element including a light-transmitting layer provided on the side, and a first side surface of the light-emitting element that intersects an interface between the phosphor layer and the light-transmitting layer, A first reflecting portion configured to reflect light traveling parallel to the substrate in a direction opposite to the substrate;

  The first reflecting portion reflects light traveling in parallel with the substrate inside the phosphor layer, thereby limiting the light emitting region and suppressing an increase in the light emitting area in the phosphor layer. That is, the light emitting region does not extend beyond the first reflecting portion.

  Furthermore, since the light transmission layer is provided on the opposite side of the phosphor layer from the substrate, the amount of light emitted from the phosphor layer to the outside of the substrate compared to the case where the light transmission layer is not provided. Will increase. This is because the critical angle at the interface between the phosphor layer and the light transmission layer is larger than the critical angle at the interface between the phosphor layer and air.

  Furthermore, the first reflecting portion can reflect light traveling in the phosphor layer in parallel with the substrate in a direction opposite to the substrate. That is, the traveling direction of the light traveling from the phosphor layer to the light transmission layer can be changed so that the light beam angle with respect to the surface normal of the substrate becomes small. As described above, by reducing the light ray angle at the exit surface of the light transmission layer, that is, the interface between the light transmission layer and air, it is possible to suppress total reflection of light at the exit surface of the light transmission layer. In addition, since the emission angle of light emitted from the light transmission layer is reduced, it is possible to increase the amount of light taken in by the pickup lens or the light guide unit.

  As described above, according to the present invention, the light utilization efficiency of the entire system including the wavelength conversion element can be improved.

  In a preferred aspect of the present invention, the first side surface is along one of a direction along a circle centering on the rotation axis of the substrate and a direction intersecting the circle. Is desirable. In the case where the first side surface is along a direction along a circle centering on the rotation axis of the substrate, an increase in the light emitting area is suppressed in the radial direction of the circle, and the light beam angle of light emitted from the light transmission layer is set. Can be small. In addition, when the first side surface is along a direction intersecting with a circle centered on the rotation axis of the substrate, an increase in the light emission area in the circumferential direction of the circle is suppressed, and light emitted from the light transmission layer The light beam angle can be reduced.

  In a preferred aspect of the present invention, light that travels in parallel with the substrate through the phosphor layer is provided on the second side surface of the light-emitting element facing the first side surface. It is desirable to further have a second reflecting portion that reflects in the direction. Thereby, the increase in the light emission area can be further suppressed. Furthermore, since the amount of light emitted from the light transmission layer at a small light beam angle can be increased, the amount of light taken in by the pickup lens or the light guide means can be further increased.

  In a preferred embodiment of the present invention, the light provided on the third side surface of the light-emitting element intersecting the first side surface and traveling in the phosphor layer in parallel with the substrate is opposite to the substrate. A third reflecting portion that reflects toward the direction, and a fourth side surface of the light emitting element that faces the third side surface, and the light traveling in the phosphor layer in parallel with the substrate is transmitted to the substrate. It is desirable to further include a fourth reflecting portion that reflects in the opposite direction. As a result, an increase in the light emitting area can be further suppressed, and the amount of light emitted from the light transmission layer at a small light beam angle can be further increased.

  As a preferred embodiment of the present invention, it is desirable that the light emitting element is provided on the surface of the substrate. By providing the phosphor layer on the wheel substrate, the heat generated in the phosphor layer can be effectively dissipated to the outside.

  As a preferred embodiment of the present invention, it is desirable that the light emitting element is provided in a groove provided in the substrate. By providing the phosphor layer in the groove of the wheel substrate, the material of the phosphor layer can be stably applied.

  Moreover, as a preferable aspect of the present invention, it is desirable to further include a heat conducting portion provided on the opposite side of the first reflecting portion from the light emitting element. Thereby, the heat generated in the phosphor layer can be effectively dissipated.

  As a preferred embodiment of the present invention, the phosphor layer preferably has a binder in which the phosphor is dispersed, and the refractive index of the light transmission layer is preferably the same as the refractive index of the binder. Thereby, the fluorescence emitted from the phosphor is not reflected at the interface between the phosphor layer and the light transmission layer and returned to the phosphor layer. Therefore, it is possible to suppress light loss and heat generation due to fluorescence absorption by the phosphor layer.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a concavo-convex structure provided on the surface of the light transmission layer opposite to the phosphor layer. Thereby, reflection of light at the interface between the light transmission layer and air can be suppressed, and light can be efficiently extracted from the light transmission layer.

  Moreover, as a preferable aspect of the present invention, a wavelength separation layer that is provided between the substrate and the phosphor layer, transmits excitation light that excites the phosphor, and reflects fluorescence emitted from the phosphor. It is desirable to have The wavelength separation layer reflects the fluorescence traveling toward the incident surface of the excitation light in the phosphor layer toward the light transmission layer. Thereby, when the excitation light is irradiated from the side opposite to the surface on which the phosphor layer of the substrate is provided, the wavelength conversion element can efficiently emit fluorescence.

  Moreover, as a preferable aspect of the present invention, a reflective layer is provided between the substrate and the phosphor layer and reflects the excitation light that excites the phosphor and the fluorescence emitted from the phosphor. Is desirable. Thus, when the phosphor is irradiated with excitation light from the light transmission layer side, the wavelength conversion element can efficiently emit fluorescence and a part of the excitation light.

  As a preferred embodiment of the present invention, the substrate is preferably made of metal. Thereby, the heat generated in the phosphor layer can be effectively dissipated.

  Furthermore, a light source device according to the present invention includes an excitation light source unit that emits excitation light, and the wavelength conversion element that emits fluorescence when irradiated with the excitation light. Accordingly, it is possible to provide a light source device that has high light use efficiency as a whole system including the light source device and can obtain desired color light.

  In a preferred aspect of the present invention, the size of the spot of the excitation light formed on the wavelength conversion element in the radial direction of a circle around the rotation axis of the substrate is the radius of the phosphor layer. Desirably smaller than the width in the direction. Accordingly, it is possible to increase an allowable range of shaking due to the rotation of the wavelength conversion element so that the incident position of the excitation light does not protrude from the phosphor layer.

  Moreover, the light source device according to the present invention is a light source device comprising: an excitation light source unit that emits excitation light; and the wavelength conversion element according to claim 1 that emits fluorescence when irradiated with the excitation light. The first side surface intersects with a circle centered on the rotation axis of the substrate, and the wavelength conversion element is provided on the second side surface of the light emitting element facing the first side surface and the fluorescence. A second reflection unit configured to reflect light traveling in a body layer parallel to the substrate in a direction opposite to the substrate; and a pulse frequency at which the excitation light is emitted by the excitation light source unit. Assuming that F (Hz) and the rotation speed of the wavelength conversion element are m (rps), F is preferably an integral multiple of m. Thereby, the light source part for excitation light can appropriately make excitation light incident on the fluorescent substance layer provided between the 1st reflection part and the 2nd reflection part in the circumferential direction.

  Furthermore, a projector according to the present invention is characterized in that the light emitted from the light source device is modulated in accordance with an image signal and projected. Thereby, the projector can suppress the fall of the light utilization efficiency as the whole system.

FIG. 1 is a schematic configuration diagram of a projector according to a first embodiment of the invention. FIG. 2 is a diagram showing the configuration of the phosphor wheel and the pickup lens. FIG. 3 is a cross-sectional view of a main part of the phosphor wheel. FIG. 4 is a cross-sectional view of a main part of the phosphor wheel according to the first modification of the first embodiment. FIG. 5 is a plan view of the phosphor wheel according to the second modification of the first embodiment. FIG. 6 is a cross-sectional view of a main part of the phosphor wheel. FIG. 7 is a cross-sectional view of a main part of the phosphor wheel according to the third modification of the first embodiment. FIG. 8 is a cross-sectional view of a main part of the phosphor wheel according to the fourth modification of the first embodiment. FIG. 9 is a plan view of a phosphor wheel according to the second embodiment of the present invention. FIG. 10 is a perspective view of one unit structure. FIG. 11 is a cross-sectional view of the main part of the phosphor wheel in the circumferential direction. FIG. 12 is a cross-sectional view of the main part of the phosphor wheel according to the third embodiment of the present invention. FIG. 13 is a diagram illustrating an example of a light source device using a phosphor wheel.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a projector 1 according to a first embodiment of the invention. The light source device 10 emits illumination light including red (R) light, green (G) light, and blue (B) light. The light source device 10 includes a laser diode array 2, a condenser lens 4, a phosphor wheel 5 that functions as a wavelength conversion element, and a pickup lens 6.

  The laser diode array 2 is composed of a plurality of laser diodes 3 arranged in an array. The laser diode array 2 functions as a light source unit for excitation light that emits excitation light 200.

  The excitation light 200 is, for example, B light having a wavelength near 450 nm. The condensing lens 4 functions as a condensing optical system that condenses the excitation light 200 emitted from the laser diode array 2 by the phosphor wheel 5. The phosphor wheel 5 emits fluorescence having a wavelength different from that of the excitation light 200 when irradiated with the excitation light 200. The pickup lens 6 is provided on the optical path of the excitation light 200. The pickup lens 6 captures the fluorescence emitted from the phosphor wheel 5 and the excitation light 200 transmitted through the phosphor wheel 5, and advances it to the collimating optical system 11.

  The collimating optical system 11 condenses the light from the light source device 10 on the rod integrator 12. The rod integrator 12 multi-reflects incident light to make it uniform. The superimposing lens 13 superimposes the light beam divided into a plurality by the rod integrator 12 using a spatial light modulator.

  The first dichroic mirror 14 reflects R light and G light incident from the superimposing lens 13 and transmits B light. The B light transmitted through the first dichroic mirror 14 has its optical path bent by reflection by the reflection mirror 16 and is incident on the incident-side polarizing plate 20B. The light transmitted through the incident side polarizing plate 20B enters the liquid crystal panel 21B. The liquid crystal panel 21B constitutes a spatial light modulation device that modulates the B light according to the image signal. The light transmitted through the liquid crystal panel 21B is incident on the exit-side polarizing plate 22B. The light transmitted through the exit-side polarizing plate 22B enters the cross dichroic prism 23.

  The R light and G light reflected by the first dichroic mirror 14 enter the second dichroic mirror 15. The second dichroic mirror 15 reflects G light and transmits R light. The G light whose optical path is bent by the reflection at the second dichroic mirror 15 enters the incident-side polarizing plate 20G. The G light transmitted through the incident side polarizing plate 20G is incident on the liquid crystal panel 21G. The liquid crystal panel 21G constitutes a spatial light modulation device that modulates G light according to an image signal. The light transmitted through the liquid crystal panel 21G is incident on the exit-side polarizing plate 22G. The light transmitted through the exit side polarizing plate 22G enters the cross dichroic prism 23.

  The R light that has passed through the second dichroic mirror 15 has its optical path bent by reflection by the reflection mirror 17 and enters the relay lens 18. The R light that has passed through the relay lens 18 has its optical path bent due to reflection by the reflection mirror 19, and is incident on the incident-side polarizing plate 20R. The R light transmitted through the incident side polarizing plate 20R enters the liquid crystal panel 21R. The liquid crystal panel 21R constitutes a spatial light modulation device that modulates R light according to an image signal. The light transmitted through the liquid crystal panel 21R is incident on the exit-side polarizing plate 22R. The light transmitted through the exit-side polarizing plate 22R enters the cross dichroic prism 23.

  The cross dichroic prism 23 that is a color combining optical system combines the light modulated by each spatial light modulation device into image light, and advances it to the projection optical system 24. The projection optical system 24 projects the image light combined by the cross dichroic prism 23 onto a screen (not shown).

  FIG. 2A is a plan view of the phosphor wheel 5 that functions as a wavelength conversion element, and FIG. 2B is a cross-sectional view of the phosphor wheel 5. 2A and 2B, a wheel motor 33 is attached to the phosphor wheel 5, and in FIG. 2B, a pickup lens 6 is further combined with the phosphor wheel 5. . The phosphor wheel 5 includes a structure 32 and a wheel substrate 31 that can rotate around the rotation axis R. The structure 32 will be described in detail later. The plan view of the phosphor wheel 5 shown in FIG. 2A is a plan view of the phosphor wheel 5 as viewed from the side where the structure 32 is provided. Moreover, the cross-sectional view of the phosphor wheel 5 shown in FIG. 2B is a cross section including the center position of the phosphor wheel 5. FIG. 3 is a cross section AA ′ of the phosphor wheel 5 along the radial direction of a circle centered on the rotation axis R of the wheel substrate 31.

  As shown in FIG. 2, the wheel substrate 31 is a circular plate-like member, and is made of a transparent member such as glass. In the center of the wheel substrate 31, an opening through which the cylindrical wheel motor 33 passes is provided. The wheel substrate 31 is integrated with the wheel motor 33 by mounting the wheel substrate 31 to the wheel motor 33 in the opening. The wheel substrate 31 rotates with the center position of the circular shape as the rotation axis R by driving the wheel motor 33.

  As shown in FIG. 3, in this embodiment, the structural body 32 includes a light emitting element 40, a first reflecting portion 43a, and a second reflecting portion 43b. The light emitting element 40 includes a phosphor layer 41 including a plurality of particulate phosphors 100 and a light transmission layer 42. The phosphor 100 is excited by irradiation with the excitation light 200 to generate fluorescence. The phosphor layer 41 has a binder made of a transparent resin in which particles of the phosphor 100 are dispersed. The light transmission layer 42 is provided on the opposite side of the phosphor layer 41 from the wheel substrate 31 and transmits light incident from the phosphor layer 41.

  The structure 32 is provided on the surface 31a opposite to the side on which the excitation light 200 is incident among the plurality of surfaces of the wheel substrate 31. As shown in FIG. 2A, the light emitting element 40 included in the structure 32 forms a ring having a certain width in plan view. The ring formed by the light emitting element 40 corresponds to the locus of the irradiation area of the excitation light 200 obtained by rotating the wheel substrate 31.

  The phosphor wheel 5 can dissipate the heat generated in the phosphor 100 to the outside effectively by providing the structure 32 on the surface of the wheel substrate 31.

  As shown in FIG. 3, the light emitting element 40 includes a first side surface 34 a and a second side surface 34 b having a circular shape centering on the rotation axis R of the wheel substrate 31 in plan view. The first side surface 34a and the second side surface 34b face each other. The first side surface 34 a is the side surface of the annular light emitting element 40 on the wheel motor 33 side, and the second side surface 34 b is the side surface of the annular light emitting element 40 on the outer edge side of the wheel substrate 31. In the present embodiment, the first side surface 34a and the second side surface 34b may be collectively referred to as the side surface 34 as appropriate.

  The first reflecting portion 43 a is provided on the first side surface 34 a of the light emitting element 40, and the second reflecting portion 43 b is provided on the second side surface 34 b of the light emitting element 40. In a cross section intersecting the first side surface 34a, for example, a cross section along the radial direction of a circle centering on the rotation axis R, the distance between the first side surface 34a and the second side surface 34b is light from the phosphor 41. It increases toward the transmission layer 42. Therefore, the distance between the first reflecting portion 43 a and the second reflecting portion 43 b is also increased from the phosphor layer 41 toward the light transmitting layer 42. In the present embodiment, the first reflecting portion 43a and the second reflecting portion 43b may be collectively referred to as the reflecting portion 43 as appropriate. In addition, in this specification, for convenience, the reflecting portion provided in the above-described form is referred to as a tapered reflecting portion. Or it says that the reflective part has a taper shape. The reflector 43 reflects the fluorescence and excitation light incident from the phosphor layer 41 and the fluorescence and excitation light incident from the light transmission layer 42. As the reflection part 43, a highly reflective member, for example, a film made of a metal member is used.

  The dichroic film 44 is provided between the wheel substrate 31 and the phosphor layer 41, that is, on the incident surface 41 a of the excitation light 200 among a plurality of surfaces of the phosphor layer 41. The dichroic film 44 functions as a wavelength separation layer having a wavelength characteristic that transmits the excitation light 200 emitted from the laser diode array 2 and reflects the fluorescence emitted from the phosphor 100.

  The phosphor 100 generates fluorescence including G light and R light when irradiated with the excitation light 200. A part of the excitation light 200 incident on the phosphor layer 41 is emitted from the phosphor layer 41 toward the pickup lens 6 together with the fluorescence. As described above, the light source device 10 emits white illumination light by mixing the fluorescence including the G light and the R light and the excitation light 200 including the B light. For example, a YAG phosphor is used as the phosphor. The phosphor layer 41 is obtained, for example, by applying a mixture of powdered phosphor 100 and a binder to the wheel substrate 31 and thermally curing the mixture. The light transmission layer 42 is made of a transparent resin having the same refractive index as the binder of the phosphor layer 41.

  A spot of the excitation light 200 is formed on the incident surface 41 a of the phosphor layer 41. The light source device 10 is adjusted such that the spot diameter d1 of the excitation light 200 measured in the radial direction of the circle centered on the rotation axis R is smaller than the radial width M of the incident surface 41a. Thereby, it is possible to increase the upper limit value of the shake due to the rotation of the phosphor wheel 5 that is allowed to prevent the incident position of the excitation light 200 from protruding from the incident surface 41a.

  The excitation light 200 incident on the wheel substrate 31 passes through the wheel substrate 31 and the dichroic film 44 and enters the phosphor layer 41. Part of the excitation light 200 incident on the phosphor layer 41 excites the phosphor 100, and the excited phosphor 100 emits fluorescence. The fluorescence generated in the phosphor 100 is emitted approximately isotropic around the light emission position.

  Of the fluorescence and excitation light 200 that have traveled from the phosphor layer 41 to the light transmission layer 42, components that have entered the interface between the light transmission layer 42 and air at an angle smaller than the critical angle are emitted from the light transmission layer 42 into the air. To do.

  In this embodiment, since the refractive index of the light transmission layer 42 is the same as the refractive index of the binder of the phosphor layer 41, no light is reflected at the interface between the phosphor layer 41 and the light transmission layer 42. Therefore, the fluorescence emitted from the phosphor 100 and the excitation light scattered by the phosphor are not reflected at the interface between the phosphor layer 41 and the light transmission layer 42 and returned to the phosphor layer 41. As a result, light loss and heat generation due to the absorption of fluorescence by the phosphor layer 41 are suppressed. The light transmission layer 42 is not limited to the same refractive index as that of the binder, and may be formed of a material having a refractive index lower than that of the binder, for example.

  The fluorescence that has traveled toward the wheel substrate 31 inside the phosphor layer 41 is reflected by the dichroic film 44 and travels toward the light transmission layer 42. Therefore, the fluorescence emitted from the phosphor 100 can be efficiently emitted from the fluorescence emission surface 42a of the light transmission layer 42 without leaking to the wheel substrate 31 side. In the present specification, the fluorescence emission surface 42a refers to a surface from which the fluorescence emitted from the phosphor is emitted from the light transmission layer 42 into the air among the plurality of surfaces of the light transmission layer 42.

  Further, the traveling direction of the light can be changed by the tapered reflecting portion 43 so that the light ray angle with respect to the normal line N of the wheel substrate 31 becomes small. Therefore, the light ray angle at the fluorescence emission surface 42a of the light transmission layer 42 is reduced, and total reflection of light at the interface between the light transmission layer 42 and air is suppressed. As a result, light traveling inside the light transmission layer 42 is transmitted. It becomes easy to inject into the air from the fluorescence emission surface 42a of the light transmission layer 42.

  Further, the fluorescent component traveling in the phosphor layer 41 in parallel with the wheel substrate 31 is prevented from propagating in the radial direction of the phosphor wheel 5 due to reflection by the reflecting portion 43. In the phosphor wheel 5 according to the present embodiment, the propagation of the fluorescence in the phosphor layer 41 is blocked by the reflecting portion 43, so that an increase in the light emission area in the phosphor layer 41 is suppressed.

  Further, by reducing the emission angle of light emitted from the fluorescence emission surface 42a of the light transmission layer 42, the amount of light taken in by the pickup lens 6 or the like can be increased. Thereby, the projector 1 including the phosphor wheel 5 can improve the light utilization efficiency of the entire system.

(Modification 1)
FIG. 4 is a cross-sectional view of the main part of the phosphor wheel according to the first modification of the present embodiment. In the phosphor wheel 5 according to the first embodiment, the structural body 32 is provided on the surface 31a opposite to the side on which the excitation light 200 is incident among the plurality of surfaces of the wheel substrate 31. In the phosphor wheel according to the above, the structure 32 is provided in the groove 46 provided in the surface 45a of the wheel substrate 45. The reflecting portion 43 is sandwiched between the side surface 34 of the light emitting element 40 and the wall surface of the groove 46. The dichroic film 44 is provided at the bottom of the groove 46. By providing the phosphor layer 41 in the groove 46, the material of the phosphor layer 41 can be stably applied.

(Modification 2)
FIG. 5 is a plan view of the phosphor wheel 7 according to the second modification of the present embodiment. FIG. 6 is a cross-sectional view of the main part of the phosphor wheel 7. The phosphor wheel 7 according to this modification has a heat conducting portion 47 that conducts heat from the phosphor 100. The heat conducting portion 47 is provided on the surface 31 a of the wheel substrate 31 so as to be in contact with the structure 32. The heat conducting unit 47 is configured using a member having high heat conductivity, such as copper or aluminum.

  The heat generated in the phosphor 100 by the irradiation of the excitation light 200 is conducted from the phosphor layer 41 through the reflecting portion 43 or from the phosphor layer 41 through the light transmitting layer 42 and the reflecting portion 43 to the heat conducting portion 47. . The phosphor wheel 7 can dissipate the heat generated in the phosphor 100 effectively by providing the heat conducting portion 47. The phosphor wheel 7 can generate fluorescence with high efficiency by effective heat dissipation.

  The heat conduction part 47 is not limited to the case of completely covering a part other than the structure 32 on the surface of the wheel substrate 31. In order to effectively dissipate the heat generated in the phosphor 100, the heat conducting unit 47 may be provided on at least a part of the surface 31 a of the wheel substrate 31 around the structure 32. . The phosphor wheel 7 may be configured such that a part of the heat conducting portion 47 functions as a reflecting portion in addition to providing the reflecting portion 43 between the side surface 34 of the light emitting element 40 and the heat conducting portion 47.

(Modification 3)
FIG. 7 is a cross-sectional view of the main part of the phosphor wheel according to the third modification of the present embodiment. In the phosphor wheel according to the present modification, the structure 32 is provided in the groove 48 formed in the wheel substrate 45 and the heat conducting unit 47. Also in this modification, the phosphor wheel can dissipate the heat generated in the phosphor 100 effectively by providing the heat conducting portion 47. The heat conducting portion 47 may completely cover a portion of the surface of the wheel substrate 45 other than the groove 48, or may be provided on a part of the periphery of the structure 32.

(Modification 4)
FIG. 8 is a cross-sectional view of the main part of the phosphor wheel according to the fourth modification of the present embodiment. The phosphor wheel according to this modified example has a concavo-convex structure (moth eye structure) 49 provided on the fluorescence emission surface 42 a of the light transmission layer 42.

  Each of the concavo-convex structures 49 is, for example, formed with a width shorter than the wavelength of fluorescence and is provided two-dimensionally. The uneven structure 49 suppresses reflection of light at the interface between the light transmission layer 42 and air. The phosphor wheel according to this modification can efficiently extract light from the light transmission layer 42 by the uneven structure 49.

(Modification 5)
In the phosphor wheel according to the above-described embodiment and Modifications 1 to 4, the first reflecting portion 43a and the second reflecting portion 43b are provided, but only one of them may be provided. For example, when only the second reflecting portion 43b is provided, the fluorescent component that travels at a large angle with respect to the normal line N is reflected toward the outer side of the wheel substrate 31 by reflection at the second reflecting portion 43b. Propagation is prevented. The light reflected by the second reflecting portion 43 b travels while being scattered by the phosphor 100 inside the phosphor layer 41 and enters the light transmission layer 42. Therefore, even when only one of the first reflecting portion 43a and the second reflecting portion 43b is provided, the effect of improving the light utilization efficiency of the entire system can be obtained.

  FIG. 9 is a plan view of a phosphor wheel 50 that functions as a wavelength conversion element according to the second embodiment of the present invention. In the present embodiment, the reflecting portions are provided on the side surface provided in the shape of a circle centered on the rotation axis R of the wheel substrate 31 and the side surface provided in the radial direction of the circle. The phosphor wheel 50 is applied to the light source device 10 of the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The structure including the phosphor layer is divided into a plurality of unit structures 51 by reflection portions arranged in the circumferential direction.

  FIG. 10 is a perspective view of one unit structure 51. The unit structure 51 includes a light emitting element 57, a first reflection portion 54a provided in the circumferential direction, a second reflection portion 54b, a third reflection portion 55a provided in the radial direction, and a fourth reflection portion. 55b is included. The light emitting element 57 includes a phosphor layer 52 including a particulate phosphor 100 and a light transmission layer 53. As described above, the light emitting element 57 is surrounded by the first reflecting portion 54a, the second reflecting portion 54b, the third reflecting portion 55a, and the fourth reflecting portion 55b. The first reflecting portion 54a and the second reflecting portion 54b provided in the circumferential direction for one unit structure 51 are arranged in the radial direction of the circle in the same manner as the reflecting portion 43 (see FIG. 3) in the first embodiment. It has a tapered shape in the cross section along. In the present embodiment, the first reflecting portion 54a and the second reflecting portion 54b may be collectively referred to as the reflecting portion 54 as appropriate. Similarly, the third reflecting portion 55a and the fourth reflecting portion 55b may be collectively referred to as the reflecting portion 55.

  FIG. 11 is a cross-sectional view of the main part of the phosphor wheel 50 in the circumferential direction indicated by a dashed line in FIG. The plurality of unit structures 51 are partitioned from each other by the reflection portion 55 and are arranged in the circumferential direction. The dichroic film 56 that is a wavelength separation layer is provided between the wheel substrate 31 and the phosphor layer 52 of each unit structure 51. The reflection portion 55 provided in the radial direction with respect to one unit structure 51 has a tapered shape in a cross section along the circumferential direction.

  In the phosphor wheel 50 according to the present embodiment, the light-emitting region is provided in the circumferential direction and the radial direction by providing the reflective portion 54 having a tapered shape in the circumferential direction and providing the reflective portion 55 having a tapered shape in the radial direction. Limited. For this reason, it is possible to suppress an increase in the light emission area and to reduce the light beam angle on the fluorescence emission surface 53a of the light transmission layer 53. Thereby, the projector 1 including the phosphor wheel 50 can further improve the light utilization efficiency of the entire system.

  As shown in FIG. 11, a region where the phosphor 100 is not provided exists between two unit structures 51 adjacent to each other. Therefore, the laser diode array 2 (see FIG. 1) does not irradiate the excitation light 200 to a region where the phosphor 100 is not provided, that is, the excitation light 200 is appropriately applied to the phosphor layer 52 of each unit structure 51. The excitation light 200 is emitted at a pulse frequency corresponding to the rotation of the phosphor wheel 50 so as to be incident. The light source device 10 can improve the light use efficiency by stopping the emission of the excitation light 200 to the region where the phosphor 100 is not provided, and can stabilize the intensity of the light emitted from the light source device 10. it can. Furthermore, the lifetime of the laser diode 3 can be extended by using pulsed light emission.

When one pulse of excitation light 200 is incident on the phosphor wheel 50, the length L of the irradiation region in the circumferential direction is calculated by the equation (1).
L = d2 + 2πrmD / F (1)

  However, d2 is the spot diameter (unit m) in the circumferential direction of the excitation light 200, r is the distance (unit m) between the radial center of the light emitting element 57 and the rotation center R, and m is the phosphor wheel 50. The rotation speed (unit: rps), D is the duty ratio of the pulse of the excitation light 200, and F is the pulse frequency (unit: Hz) of the excitation light 200. As shown in FIG. 10, by setting the length of the incident surface 52a of the phosphor layer 52 in the circumferential direction to L, the excitation light 200 can be appropriately irradiated to the unit structure 51.

When the length L is allowable up to T times the spot diameter d2, in other words, the amount of bleeding of the excitation light 200 is allowable up to T times the spot diameter d2, T = L / d2 is substituted into the equation (1). Thus, equation (2) for the distance r is obtained.
r = (T−1) d2F / (2πrmD) (2)

  For example, when the pulse frequency F is 100 kHz, the duty ratio D is 0.3, the spot diameter d2 is 1 mm, the rotational speed m is 10,000 / 60 rps (= 10000 rpm), and T is 1.1, The distance r is calculated to be approximately 3.2 cm. At this time, the length of one unit structure 51 in the circumferential direction is approximately 1.1 mm. The light source device 10 synchronizes the irradiation of the excitation light 200 by the laser diode array 2 and the rotation of the phosphor wheel 50 by design and driving according to such calculation.

  The number S of unit structures 51 formed on the phosphor wheel 50 is obtained by S = F / m. Since S is an integer, F is an integral multiple of m. Thereby, the laser diode array 2 can appropriately make the excitation light 200 incident on the light emitting element 57 of each unit structure 51 while avoiding the region where the phosphor 100 is not provided.

  The phosphor wheel of each embodiment is not limited to being applied to the projector 1 that uses a transmissive liquid crystal panel as a spatial light modulator. The phosphor wheel may be applied to a projector equipped with a reflective LCOS (Liquid Crystal On Silicon) or DMD (Digital Micromirror Device).

  FIG. 12 is a cross-sectional view of a main part of a phosphor wheel 70 that functions as a wavelength conversion element according to Example 3 of the invention. Differences from the phosphor wheel 5 according to the first embodiment will be described. In the phosphor wheel 70 according to the present embodiment, a reflection layer 72 that reflects the excitation light 200 and fluorescence is provided on the incident surface 41 a of the phosphor layer 41 instead of the dichroic film 44. The excitation light 200 is applied to the phosphor 100 from the side where the structure 32 of the wheel substrate 31 is provided.

  The fluorescence that has traveled toward the wheel substrate 31 inside the phosphor layer 41 is reflected by the reflection layer 72 and travels toward the light transmission layer 42. Therefore, the fluorescence emitted from the phosphor 100 can be efficiently emitted from the fluorescence emission surface 42a of the light transmission layer 42 without leaking to the wheel substrate 31 side. Similarly, the excitation light traveling inside the phosphor layer 41 toward the wheel substrate 31 is also reflected by the reflection layer 72 and can be efficiently emitted from the fluorescence emission surface 42 a of the light transmission layer 42.

  FIG. 13 shows an example of the light source device 74 using the phosphor wheel 70. The excitation light 200 is applied to the phosphor 100 from the side where the structure 32 of the wheel substrate 31 is provided, and a part of the excitation light 200 and the fluorescence emitted by the phosphor 100 are captured by the pickup lens 6. . The light captured by the pickup lens 6 proceeds to the collimating optical system 11 described in the first embodiment. In this way, the light source device 74 is used as a light source for the projector. Even with such a reflective wheel substrate, the effect of improving the light utilization efficiency of the entire system can be obtained, as with the transmissive wheel substrate described in the first embodiment.

  In the case of the reflective phosphor wheel 70, it is not necessary to use a transparent member as the wheel substrate 31. If a metal is used as the wheel substrate, the heat generated in the phosphor 100 can be effectively dissipated. In this case, as shown in Modification 1 of Example 1, it is preferable to provide the light emitting element 40 in a groove provided on the surface of the wheel substrate. According to this configuration, the heat generated in the phosphor 100 can be dissipated more efficiently. Furthermore, if a metal having a high light reflectance such as aluminum is used, the wheel substrate itself functions as a reflecting member, so that it is not necessary to provide the reflecting portion 43 and the reflecting layer 72.

  As described above, the phosphor wheel, the light source device, and the projector according to the present invention are useful when displaying an image using laser light.

  1 projector, 2 laser diode array, 3 laser diode, 4 condenser lens, 5 phosphor wheel, 6 pickup lens, 7 phosphor wheel, 10 light source device, 11 collimating optical system, 12 rod integrator, 13 superimposing lens, 14 1 dichroic mirror, 15 second dichroic mirror, 16, 17, 19 reflecting mirror, 18 relay lens, 20R, 20G, 20B incident side polarizing plate, 21R, 21G, 21B liquid crystal panel, 22R, 22G, 22B exit side polarizing plate, 23 cross dichroic prism, 24 projection optical system, 31 wheel substrate, 31a surface, 32 structure, 33 wheel motor, 34a first side, 34b second side, 40 light emitting element, 41 phosphor layer, 41a incident surface, 42 Light transmission layer, 42a Fluorescent emission surface, 43a 1st reflection portion, 43b 2nd reflection portion, 44 dichroic film, 45 wheel substrate, 45a surface, 46 groove, 47 heat conduction portion, 48 groove, 49 uneven structure, 50 Phosphor wheel, 51 unit structure, 52 phosphor layer, 52a entrance surface, 53 light transmission layer, 53a fluorescence exit surface, 54 reflector, 54a first reflector, 54b second reflector, 55 reflector, 55a Third reflecting portion, 55b Fourth reflecting portion, 56 Dichroic film, 57 Light emitting element, 70 Phosphor wheel, 72 Reflecting layer, 74 Light source device, 100 Phosphor, 200 Excitation light, N normal, R Rotation axis

Claims (16)

A substrate,
A light emitting device provided on the substrate and including a phosphor layer containing a phosphor and a light transmission layer provided on the opposite side of the phosphor layer from the substrate;
Provided on the first side surface of the light-emitting element that intersects the interface between the phosphor layer and the light transmission layer, the light traveling inside the phosphor layer in parallel with the substrate is directed in the direction opposite to the substrate. A first reflecting part to be reflected,
A wavelength conversion element comprising:   2. The first side surface according to claim 1, wherein the first side surface is along one of a direction along a circle centering on a rotation axis of the substrate and a direction intersecting with the circle. Wavelength conversion element.   Second reflection provided on the second side surface of the light emitting element facing the first side surface and reflecting the light traveling in the phosphor layer in parallel with the substrate in a direction opposite to the substrate. The wavelength conversion element according to claim 2, further comprising a portion. A third reflection is provided on a third side surface of the light emitting element that intersects the first side surface, and reflects light traveling in the phosphor layer in parallel with the substrate in a direction opposite to the substrate. And
A fourth reflection is provided on a fourth side surface of the light emitting element facing the third side surface, and reflects light traveling in the phosphor layer in parallel with the substrate in a direction opposite to the substrate. And
The wavelength conversion element according to claim 2, further comprising:   The wavelength conversion element according to any one of claims 1 to 4, wherein the light emitting element is provided on a surface of the substrate.   The wavelength conversion element according to claim 1, wherein the light emitting element is provided in a groove provided in the substrate.   The wavelength conversion element according to claim 1, further comprising a heat conduction part provided on a side of the first reflection part opposite to the light emitting element. The phosphor layer has a binder in which the phosphor is dispersed,
The wavelength conversion element according to claim 1, wherein a refractive index of the light transmission layer is the same as a refractive index of the binder.   9. The wavelength conversion element according to claim 1, wherein the wavelength conversion element has an uneven structure provided on a surface of the light transmission layer opposite to the phosphor layer.   2. A wavelength separation layer that is provided between the substrate and the phosphor layer, transmits excitation light that excites the phosphor, and reflects fluorescence emitted from the phosphor. The wavelength conversion element as described in any one of 9 to 9.   The reflective layer which is provided between the said board | substrate and the said fluorescent substance layer, and reflects the excitation light which excites the fluorescent substance, and the fluorescence inject | emitted from the said fluorescent substance is characterized by the above-mentioned. The wavelength conversion element as described in any one.   The wavelength conversion element according to claim 1, wherein the substrate is made of metal. An excitation light source unit that emits excitation light;
A wavelength conversion element according to any one of claims 1 to 12, which emits fluorescence upon irradiation with the excitation light.   A size of a spot of the excitation light formed on the wavelength conversion element in a radial direction of a circle centering on a rotation axis of the substrate is smaller than a width of the phosphor layer in the radial direction. The light source device according to claim 13. A light source device comprising: an excitation light source unit that emits excitation light; and the wavelength conversion element according to claim 1 that emits fluorescence when irradiated with the excitation light.
The first side surface intersects a circle centered on the rotation axis of the substrate;
The wavelength conversion element is provided on the second side surface of the light emitting element facing the first side surface, and transmits light traveling in the phosphor layer in parallel with the substrate in a direction opposite to the substrate. A second reflecting portion for reflecting;
F is an integral multiple of m, where F (Hz) is the pulse frequency at which the excitation light is emitted from the excitation light source unit, and m (rps) is the rotation speed of the wavelength conversion element. Light source device.   A projector, wherein the light emitted from the light source device according to any one of claims 13 to 15 is modulated in accordance with an image signal and projected.

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