JP2012018209A - Light source device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device capable of improving use efficiency of light by suppressing adhesion of dust on a surface of a phosphor layer.SOLUTION: A light source device of the present invention comprises: a substrate 2 which is rotatable around a predetermined rotation axis; a phosphor layer 3 which is provided to the substrate and includes phosphor; a light source; a light condensing optical system for emitting excitation light emitted from the light source so that the excitation light is condensed at the phosphor layer; and a covering part 16 which is composed of a material which allows the transmission of at least excitation light and covers a region to which the excitation light is emitted, of the phosphor layer.

Description

  The present invention relates to a light source device and a projector, and more particularly to a technology of a light source device using fluorescence obtained by exciting a phosphor with laser light.

  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. For example, in Patent Document 1 and Patent Document 2, red light is emitted from a blue light laser and a color wheel that generates green light and red light as fluorescence by exciting the phosphor contained in the phosphor layer with laser light. Techniques for obtaining blue and green illumination light have been proposed.

JP 2009-277516 A JP 2010-86815 A

  However, if dust adheres directly to the surface of the phosphor layer of the color wheel, laser light incident on the phosphor layer or light emitted from the phosphor layer is absorbed or scattered by the dust. There is a problem that will decrease.

  SUMMARY An advantage of some aspects of the invention is that it solves at least a part of the above-described problems and can provide a light source device capable of improving light use efficiency and a projector using the light source device.

  In order to solve the above-described problems and achieve the object, the present invention includes a substrate that can be rotated around a predetermined rotation axis, a phosphor layer that includes the phosphor, and a light source provided on the substrate. And a condensing optical system that irradiates the phosphor layer so that the excitation light emitted from the light source is condensed and a member that transmits at least the excitation light. And a covering portion for covering.

  According to this invention, the area | region where excitation light is irradiated among fluorescent substance layers is covered with a cover part. When excitation light is incident on the phosphor layer from the cover side, dust can be prevented from directly adhering to the area of the phosphor layer where the excitation light is irradiated. Can be suppressed. Here, since the excitation light emitted from the light source is condensed by the condensing optical system so as to be condensed on the phosphor layer, the degree of concentration of the excitation light on the surface of the cover portion is the surface of the phosphor layer. Lower than the degree of concentration of the excitation light at. That is, the area of the region irradiated with the excitation light on the surface of the cover part is larger than the area of the region irradiated with the excitation light on the surface of the phosphor layer. Therefore, even if dust adheres to the surface of the cover portion, it is possible to suppress a decrease in the utilization efficiency of the excitation light.

  Further, when excitation light is incident on the phosphor layer from the substrate side, it is possible to prevent dust from directly adhering to the area of the phosphor layer where light is emitted from the phosphor layer. It is possible to suppress a decrease in utilization efficiency of light emitted from the layer. Here, the excitation light transmitted through the phosphor layer and the fluorescence generated from the phosphor are scattered to some extent by the phosphor and then emitted from the phosphor layer, but the light beam is interrupted immediately after the light emitted from the phosphor layer is emitted. The area is relatively small. However, when the emitted light from the phosphor layer reaches the surface of the cover portion, the luminous flux of the emitted light spreads and the cross-sectional area of the luminous flux increases. Therefore, even if dust adheres to the surface of the cover portion, it is possible to suppress a decrease in utilization efficiency of the emitted light from the phosphor layer.

  As a preferred embodiment of the present invention, it is desirable that the substrate is composed of a member that transmits at least fluorescence emitted from the phosphor. Since the substrate is constituted by a member that transmits at least the fluorescence emitted from the phosphor, a transmission-type wavelength conversion member that transmits the fluorescence emitted from the phosphor can be obtained.

  As a preferred embodiment of the present invention, it is desirable that the substrate is composed of a member that reflects at least the fluorescence emitted from the phosphor, and the excitation light is irradiated to the phosphor layer from the cover portion side. Since the substrate is composed of a member that reflects at least the fluorescence emitted from the phosphor, a reflective wavelength conversion member that reflects the fluorescence emitted from the phosphor can be obtained. In addition, by using a metal plate having high thermal conductivity as a member that reflects at least the fluorescence emitted from the phosphor, the heat dissipation efficiency of the heat generated in the phosphor layer by light irradiation can be improved. Thereby, the temperature rise of a fluorescent substance layer can be suppressed and deterioration of a fluorescent substance can be suppressed.

  As a preferred embodiment of the present invention, it is desirable that a space is provided between the phosphor layer and the cover. Since a space is provided between the phosphor layer and the cover portion, the material used for the cover portion can be reduced. Further, the weight of the cover can be reduced, and as a result, the burden on the drive unit such as a motor that rotates the substrate can be reduced. Further, by reducing the burden on the drive unit, the drive unit can be reduced in size, which can contribute to the reduction in size of the light source device.

  A projector according to another aspect of the invention includes the light source device and a spatial light modulation device that modulates light emitted from the light source device in accordance with an image signal. Since the projector includes the light source device that suppresses the dust from adhering to the phosphor layer and suppresses the decrease in the light use efficiency, it is possible to improve the reliability and obtain a high-quality image.

FIG. 1 is a diagram illustrating a schematic configuration of a light source device according to Embodiment 1 of the present invention. FIG. 2 is an exploded perspective view of the light source device shown in FIG. FIG. 3 is a front view of the phosphor wheel. FIG. 4 is a cross-sectional view of the phosphor wheel. FIG. 5 is a cross-sectional view of the phosphor wheel according to the first modification of the first embodiment. FIG. 6 is a cross-sectional view of the phosphor wheel according to the second modification of the first embodiment. FIG. 7 is a cross-sectional view of the phosphor wheel according to the third modification of the first embodiment. FIG. 8 is a diagram illustrating a schematic configuration of the projector according to the second embodiment of the invention.

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

  FIG. 1 is a diagram illustrating a schematic configuration of a light source device according to Embodiment 1 of the present invention. FIG. 2 is an exploded perspective view of the light source device shown in FIG. The light source device 10 includes a light source 11, a collimator lens 12, a condenser lens 13, a phosphor wheel (wavelength conversion member) 1, a pickup lens 14, and a drive unit 15.

  The light source 11 emits excitation light toward the collimating lens 12. The light source 11 is configured by arranging a plurality of semiconductor lasers that emit laser light, for example. Note that the light source 11 may be configured by arranging a plurality of LEDs.

The collimating lens 12 and the condensing lens 13 function as a condensing optical system that irradiates the phosphor layer 3 provided on the phosphor wheel 1 so that the laser light emitted from the light source 11 is condensed. In the present embodiment, the laser beam is most concentrated on the interface between the phosphor layer 3 and the transparent plate 16 described later. It is not limited to the interface. The collimator lens 12 collimates the laser light emitted from the light source 11 and emits it toward the condenser lens 13. The condensing lens 13 condenses the laser light emitted from the collimating lens 12 toward a small part (for example, about 1 mm ² ) of the phosphor layer 3.

  FIG. 3 is a front view of the phosphor wheel 1. FIG. 4 is a cross-sectional view of the phosphor wheel 1. The phosphor wheel 1 has a substrate 2, a phosphor layer 3 containing a phosphor (not shown), and a transparent plate (covering portion) 16. The phosphor wheel 1 is arranged so that laser light enters the phosphor layer 3 from the transparent plate 16 side. The substrate 2 has a circular thin plate shape. The substrate 2 is made of a transparent member and has a property of transmitting light. For the substrate 2, for example, glass, white plate, quartz, crystal, sapphire, YAG (Yttrium Aluminum Garnet), or the like is used.

  A circular opening 2 a is formed at the center of the substrate 2. A drive shaft of the drive unit 15 for rotating the phosphor wheel 1 is inserted into the opening 2a. The drive unit 15 is, for example, a motor. As a result, the substrate 2 can be rotated about the rotation axis 5 passing through the center of the substrate 2.

  The phosphor layer 3 is coated on the surface of the substrate 2 in an annular shape having the same center as the center of the substrate 2. The phosphor layer 3 is formed by, for example, applying a mixture of a phosphor and a binder (resin material) to the surface of the substrate 2. Part of the laser light irradiated to the phosphor layer 3 is absorbed by the phosphor. The phosphor that has absorbed the laser light is excited to generate fluorescence. In this embodiment, the phosphor wheel 1 functions as a wavelength conversion member because a phosphor that generates yellow fluorescence by absorbing blue laser light is used.

  The transparent plate 16 functions as a cover portion that covers a region irradiated with laser light on the surface of the phosphor layer 3. The transparent plate 16 is composed of a member having a property of transmitting laser light. For the transparent plate 16, for example, glass, white plate, quartz, crystal, sapphire, YAG (Yttrium Aluminum Garnet), or the like is used. In the present specification, for convenience, the surface of the phosphor layer 3 opposite to the substrate 2 is referred to as the surface of the phosphor layer 3, and the surface of the transparent plate 16 opposite to the phosphor layer 3 is transparent. Called the surface of the plate 16.

  The transparent plate 16 is provided so as to cover at least a region of the phosphor layer 3 that is irradiated with the laser beam condensed by the condenser lens 13. Here, when light is emitted from the light source device 10, the laser light is condensed and irradiated on a part of the phosphor layer 3 while rotating the phosphor wheel 1 about the rotation shaft 5.

  Therefore, the region irradiated with the laser light always moves on the phosphor layer 3. That is, the region of the phosphor layer 3 that is irradiated with the condensed laser light has an annular shape as with the phosphor layer 3. Therefore, the transparent plate 16 also has an annular shape.

  The transparent plate 16 may be provided so as to cover only the region irradiated with the laser light in the phosphor layer 3, or provided so as to cover the entire phosphor layer 3 including the region irradiated with the laser light. May be. Moreover, you may provide so that the fluorescent substance layer 3 and the board | substrate 2 may be covered.

  Although not shown, a dichroic that allows laser light incident from the transparent plate 16 side to pass between the transparent plate 16 and the phosphor layer 3 but reflects laser light scattered by the phosphor layer 3. A mirror is provided. By providing a dichroic mirror between the transparent plate 16 and the phosphor layer 3, the laser beam scattered by the phosphor layer 3 is reflected to the light traveling to the transparent plate 16 side, and the pickup lens 14 side to be described later Therefore, the light utilization efficiency can be improved.

  The pickup lens 14 condenses the light emitted from the phosphor layer 3. The laser light incident on the phosphor layer 3 and the fluorescence generated from the phosphor are scattered when passing through the phosphor layer 3 and travel in various directions as lumbar radiation. Therefore, the laser light and fluorescence emitted from the phosphor layer 3 are collected by the pickup lens 14 and used as illumination light, thereby improving the light utilization efficiency.

  As described above, the region of the surface of the phosphor layer 3 that is irradiated with the laser beam condensed by the condensing lens 13 is covered with the transparent plate 16, so that the laser on the surface of the phosphor layer 3 is It is possible to prevent dust from directly adhering to the region irradiated with light. As described above, since the laser beam is condensed toward a very small area of the phosphor layer 3, if dust directly adheres to the surface of the phosphor layer 3, the progress of the laser beam is likely to be hindered. Usage efficiency tends to decrease.

  On the other hand, in the present embodiment, it is possible to prevent dust from directly adhering to the region irradiated with laser light on the surface of the phosphor layer 3, so that it is possible to suppress a decrease in light utilization efficiency. Further, as shown in FIGS. 1 and 4, the transparent plate 16 has a predetermined thickness, and the laser beam is not completely condensed on the surface of the transparent plate 16. In other words, the degree of laser beam condensing on the surface of the transparent plate 16 is lower than the degree of laser beam condensing on the surface of the phosphor layer 3. That is, the thickness of the transparent plate 16 is determined so that the area of the region irradiated with light on the surface of the transparent plate 16 is larger than the area of the region irradiated with light on the surface of the phosphor layer 3. Yes. Therefore, even if dust adheres to the laser light irradiated portion on the surface of the transparent plate 16, it is possible to suppress a decrease in the utilization efficiency of the laser light.

  In addition, a part of the energy of the light transmitted through the phosphor layer 3 is converted into heat, and since the irradiation region is a very small region, the light irradiation region of the phosphor layer 3 has a very high temperature. Prone. Therefore, it is possible to suppress the occurrence of problems due to the prevention of dust from adhering to the surface of the phosphor layer 3 that tends to become high temperature, for example, the decrease in light utilization efficiency due to the scorching of the adhering dust. As described above, since the laser beam is not completely condensed on the surface of the transparent plate 16, the surface of the transparent plate 16 is less likely to be hotter than the phosphor layer 3.

[Modification 1]
FIG. 5 is a cross-sectional view of the phosphor wheel 1 according to the first modification of the first embodiment. The laser light transmitted through the phosphor layer 3 and the fluorescence generated from the phosphor are scattered to some extent by the phosphor and then emitted from the phosphor layer 3. The area is relatively small. For this reason, if dust adheres directly to the emission surface of the phosphor layer, the utilization efficiency of the emitted light from the phosphor layer 3 is reduced.

  However, in the first modification, the transparent plate 16 that transmits the light emitted from the phosphor layer 3 is provided on the emission surface side of the phosphor layer 3. When the emitted light from the phosphor layer 3 reaches the surface of the transparent plate 16, the luminous flux of the emitted light spreads and the cross-sectional area of the luminous flux increases. Therefore, even if dust adheres to the surface of the transparent plate 16, it is possible to suppress a decrease in utilization efficiency of the emitted light from the phosphor layer 3.

  Although not shown, there is a dichroic mirror between the substrate 2 and the phosphor layer 3 that transmits the laser light incident from the substrate 2 side but reflects the laser light scattered by the phosphor layer 3. Is provided. By providing a dichroic mirror between the substrate 2 and the phosphor layer 3, the laser beam scattered by the phosphor layer 3 reflects light traveling toward the substrate 2 and proceeds toward the pickup lens 14 described later. Therefore, the utilization efficiency of light can be improved.

[Modification 2]
FIG. 6 is a cross-sectional view of the phosphor wheel according to the second modification of the first embodiment. In the second modification, a space is provided between the phosphor layer 3 and the transparent plate 16. That is, a concave portion is provided on the surface of the transparent plate 16 facing the phosphor layer 3.

  Since the concave portion is provided in the transparent plate 16, the material used for the transparent plate 16 can be reduced. Further, the weight of the transparent plate 16 can be reduced, and as a result, the burden on the driving unit 15 that rotates the phosphor wheel 1 can be reduced. Further, by reducing the burden on the drive unit 15, the drive unit 15 can be reduced in size, which can contribute to the reduction in size of the light source device 10.

  In addition, the larger the distance between the surface of the transparent plate 16 and the phosphor layer 3 that is the target for condensing the laser light, the wider the laser light irradiation range on the surface of the transparent plate 16. If the irradiation range of the laser beam is widened, it is difficult for the light use efficiency to be reduced due to dust adhering to the surface of the transparent plate 16. Therefore, when the transparent plate 16 is thickened to increase the distance between the surface of the transparent plate 16 and the phosphor layer 3, the weight of the transparent plate 16 increases, and as a result, the driving unit 15 that rotates the phosphor wheel 1. The burden on is increased.

  On the other hand, in the second modification, since the concave portion is provided in the transparent plate 16, even when the transparent plate 16 is thickened, the material used for the transparent plate 16 can be reduced. 16 can be reduced in weight.

  Therefore, in the second modification, the distance between the surface of the transparent plate 16 and the phosphor layer 3 can be increased while keeping the increase in the weight of the transparent plate 16 low. It becomes easy to plan.

[Modification 3]
FIG. 7 is a cross-sectional view of the phosphor wheel 1 according to the third modification of the first embodiment. In the third modification, the phosphor wheel 1 is arranged so that laser light is incident on the phosphor layer 3 from the transparent plate 16 side and fluorescence is generated from the phosphor, as shown in FIG. Yes. However, the board | substrate 2 is comprised with the reflection member which reflects fluorescence at least, and is made into the reflection type wavelength conversion member. For example, a metal plate is used as the substrate 2.

  Even in such a configuration, as shown in FIG. 7, it is possible to prevent dust from adhering to the portion where the laser beam is condensed, and to suppress a decrease in light utilization efficiency. Further, a metal plate having high thermal conductivity can be used as the substrate 2. Therefore, the heat dissipation efficiency of the heat generated in the phosphor layer 3 due to the laser light irradiation can be improved, and the temperature rise of the phosphor layer 3 can be suppressed and deterioration of the phosphor layer 3 can be easily suppressed. Even when the substrate 2 is configured by a reflecting member, a space may be provided between the phosphor layer 3 and the transparent plate 16 as in the second modification.

  FIG. 8 is a diagram illustrating a schematic configuration of the projector according to the second embodiment of the invention. The projector 60 according to the second embodiment includes the light source device 10 according to the first embodiment. Laser light emitted from the light source 11 enters the phosphor wheel 1 as excitation light. The laser light incident on the phosphor wheel 1 excites the phosphor (not shown), and fluorescence is emitted from the phosphor. Illumination light including red (R) light, green (G) light, and blue (B) light is emitted from the light source device 10 by the laser light transmitted through the phosphor and the fluorescence emitted from the phosphor. . For example, if a blue laser and a phosphor layer containing phosphors emitting red and green bands are used as the light source, the three primary colors of light can be reproduced with a small number of structures.

  The homogenizing optical system 64 is an optical system that homogenizes the intensity distribution of light incident from the light source device 10 and includes, for example, a rod integrator. The dichroic mirror 65 transmits B light out of the light from the uniformizing optical system 64 and reflects R light and G light. The dichroic mirror 66 transmits R light and reflects G light. The dichroic mirrors 65 and 66 function as a color separation optical system that separates the light from the light source device 10 for each color.

  The R light transmitted through the dichroic mirror 66 is reflected by the reflection mirrors 67 and 68 and then enters the R light spatial light modulator 70R. The spatial light modulation device 70R modulates the R light according to the image signal. The G light reflected by the dichroic mirror 66 is incident on the spatial light modulator 70G for G light. The spatial light modulation device 70G modulates the G light according to the image signal. The B light transmitted through the dichroic mirror 65 is reflected by the reflection mirror 69 and then enters the B light spatial light modulator 70B. The spatial light modulators 70R, 70G, and 70B are, for example, transmissive liquid crystal display devices.

  A cross dichroic prism 71, which is a color synthesis optical system, synthesizes the respective color lights modulated by the spatial light modulation devices 70R, 70G, and 70B. The projection optical system 72 projects each color light synthesized by the cross dichroic prism 71 onto the screen 73.

  Since the projector 60 includes the light source device 10 that suppresses the dust from adhering to the surface of the phosphor layer and suppresses the decrease in light use efficiency, it is possible to improve the reliability and obtain a high-quality image. Become. The projector 60 may be configured to include the light source device 10 according to the first, second, and third modifications described in the first embodiment.

  The projector 60 is not limited to the case where a transmissive liquid crystal display device is used as the spatial light modulation device. As the spatial light modulator, a reflective liquid crystal display (Liquid Crystal On Silicon; LCOS), DMD (Digital Micromirror Device), GLV (Grating Light Valve), or the like may be used.

  As described above, the light source device according to the present invention is suitable for use in a projector.

DESCRIPTION OF SYMBOLS 1 Phosphor wheel (wavelength conversion member), 2 board | substrate, 2a opening, 3 phosphor layer, 5 rotating shaft, 10 light source device, 11 light source, 12 collimating lens, 13 condensing lens, 14 pick-up lens, 15 drive part, 16 Transparent plate (cover), 60 projector, 64 homogenizing optical system, 65 dichroic mirror, 66 dichroic mirror, 67 reflecting mirror, 69 reflecting mirror, 70R spatial light modulator, 70G spatial light modulator, 70B spatial light modulator, 71 Cross dichroic prism, 72 projection optical system, 73 screen

Claims (5)

A substrate that is rotatable about a predetermined rotation axis;
A phosphor layer including a phosphor provided on the substrate;
A light source;
A condensing optical system for irradiating the phosphor layer with the excitation light emitted from the light source;
A light source device comprising: at least a member that transmits the excitation light; and a cover that covers a region of the phosphor layer that is irradiated with the excitation light.   The light source device according to claim 1, wherein the substrate is configured by a member that transmits at least fluorescence emitted from the phosphor. The substrate is composed of at least a member that reflects fluorescence emitted from the phosphor,
The light source device according to claim 1, wherein the excitation light is applied to the phosphor layer from the cover portion side.   The light source device according to claim 1, wherein a space is provided between the phosphor layer and the cover. The light source device according to any one of claims 1 to 4,
A projector comprising: a spatial light modulator that modulates light emitted from the light source device according to an image signal.

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