JP5817109B2 - 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 projection type image display apparatus using a light source instead of a discharge lamp has been proposed.

  As a light source of this type, a method of generating white light using fluorescent light emission is known. For example, a light source device that extracts white light as emitted light (fluorescence) by irradiating a phosphor with light from a light emitting diode (LED) or a laser has been proposed (see Patent Document 1 below). The light source device of Patent Document 1 includes a light source of excitation light (blue light) that excites a phosphor, and a fluorescent wheel that includes a phosphor that emits a plurality of color lights corresponding to the three primary colors of light. A plurality of types of phosphors are arranged as a phosphor film by dividing the region for each type in the circumferential direction of the wheel, and the fluorescent color is emitted by irradiating the plurality of phosphor films with excitation light while rotating the wheel. Different from time to time. In this way, a plurality of color lights are mixed to emit white light.

JP 2009-277516 A

  However, in the projector using the light source device disclosed in Patent Document 1, an excitation light source must be disposed on the side opposite to the side on which the liquid crystal light valve and the projection optical system are disposed with the fluorescent wheel interposed therebetween. As a result, the size of the projector was increased. Further, in the light source device described in Patent Document 1, when the phosphor is irradiated with excitation light, the excitation light is absorbed by the phosphor and the phosphor may generate heat. As a result, there has been a problem that the reliability of the light source device is lowered.

  The present invention aims to solve at least one of the above problems.

In order to achieve the above object, a light source device of the present invention includes a solid-state light source that emits excitation light including a first wavelength region, and a second light source that is different from the first wavelength region by irradiation of the excitation light A light emitting element including a phosphor layer including a phosphor that emits fluorescence including a wavelength region, and a support substrate having a support surface that supports the phosphor layer; and the excitation light between the solid-state light source and the light emitting element. A dichroic mirror provided on the optical path, and a retardation plate provided on the optical path of the excitation light between the light emitting element and the dichroic mirror, and the support substrate includes the excitation light and A reflection surface for reflecting the fluorescence; and the dichroic mirror reflects the fluorescence and has a reflectivity with respect to the first polarization component in the first wavelength region in the second wavelength region. side The phosphor layer is provided in a first region of the support surface of the support substrate, and the phosphor layer is provided in a second region of the support surface. However, a reflective film constituting the reflective surface is provided over both the first region and the second region.

  In the configuration of the present invention, light in which a part of the excitation light that has not been used for exciting the phosphor and the fluorescence emitted from the phosphor is synthesized is output from the light source device. Since the support substrate constituting the light emitting element has a reflection surface that reflects excitation light and fluorescence, the excitation light emitted from the solid light source is reflected by the reflection surface of the support substrate and emitted from the phosphor. The reflected fluorescence is also reflected by the reflecting surface and travels toward the solid light source. That is, in the light source device of the present invention, the optical path of the excitation light emitted from the solid light source is folded back by the light emitting element, and the excitation light and the fluorescence are emitted from the light emitting element toward the solid light source. In this way, the light source device can be miniaturized by using a reflective light emitting element and having a configuration in which the optical path is folded back.

  By the way, when the reflection type light emitting element as described above is used, in order to use the output light, the light emitting element and the solid light source are arranged so that excitation light and fluorescence reflected by the light emitting element do not enter the solid light source. It is necessary to change the optical path of the light emitted from the light emitting element toward the subsequent optical system. For that purpose, a dichroic mirror may be used. However, if the dichroic mirror has only a wavelength separation function, it only transmits the excitation light in the first wavelength region and reflects the fluorescence in the second wavelength region. Light passes through the dichroic mirror and returns to the solid light source. As a result, the combined light of excitation light and fluorescence cannot be extracted outside, and desired output light cannot be obtained.

  In that regard, in the configuration of the present invention, a phase difference plate is provided that makes the polarization state of the excitation light in the return path different from the polarization state of the excitation light in the forward path, and the dichroic mirror has a first wavelength region in the first wavelength region of the excitation light. It has the characteristic that the reflectance with respect to the polarized light component is lower than the reflectance with respect to the second polarized light component. That is, the dichroic mirror transmits more first polarization components in the first wavelength region than second polarization components, and more second polarization components in the first wavelength region than first polarization components. It has the polarization separation characteristic to reflect. As a result, the first polarization component in the first wavelength region, that is, the forward excitation light can pass through the dichroic mirror and reach the light emitting element. Further, the second polarization component in the first wavelength region and the fluorescence in the second wavelength region, that is, the combined light of the excitation light and the fluorescence in the return path can be reflected toward the subsequent optical system by the dichroic mirror. . Thereby, the light source device which can obtain desired output light is realizable.

In the light source device of the present invention, the first polarization component is either P-polarized light or S-polarized light with respect to the reflection surface of the dichroic mirror, and the second polarized light component is the P-polarized light or the S-polarized light. It is the other of them, and it is preferable that the retardation plate is a quarter-wave plate for the first wavelength region.
According to this configuration, if the polarization state of the excitation light is, for example, P-polarized light in the forward path, it can be changed to S-polarized light in the backward path. Accordingly, it is possible to reliably realize a configuration in which the forward excitation light is transmitted by the dichroic mirror and the backward excitation light is reflected.

In the light source device of the present invention, it is preferable that the support base material is made of a metal substrate.
According to this configuration, since the supporting base material has light reflectivity and excellent thermal conductivity, the temperature rise of the phosphor layer is suppressed and reliability can be ensured. Further, it is possible to easily provide a light-emitting element that can have light reflectivity without forming a reflective film or the like on the support base, and has high thermal conductivity and high heat dissipation.

In the light source device of the present invention, the phosphor layer is provided in a first region of the support surface of the support base material, and the phosphor layer is provided in a second region of the support surface. No configuration can be adopted.
According to this configuration, the excitation light and the fluorescence reflected by the support base material are emitted from the light emitting element in a time division manner, and the excitation light and the fluorescence are temporally integrated to obtain a combined light of these lights. Therefore, for example, the color of the synthesized light can be adjusted by changing the area ratio between the formation region and the non-formation region of the phosphor layer.

In the light source device of the present invention, it is possible to adopt a configuration in which the light emitting element is provided with a second phosphor layer that emits fluorescence including a third wavelength region different from the second wavelength region.
According to this configuration, for example, fluorescence such as red, green, and blue constituting the three primary colors of light can be obtained, and the combined light of these lights can be used as output light. Furthermore, the color of the output light can be adjusted by adding fluorescence of other colors.

In the light source device of the present invention, a configuration including an auxiliary solid light source that emits light including a wavelength region different from the first wavelength region can be employed.
According to this configuration, the light from the auxiliary solid-state light source can be added to the output light, and the color, gradation, luminance, and the like of the output light that cannot be realized only by the light emitting element can be adjusted.

In the light source device of the present invention, it is possible to adopt a configuration in which the support base material is rotatable around a rotation axis that intersects the support surface.
According to this structure, the temperature rise of a fluorescent substance layer can be reduced effectively.

A projector of the present invention includes the light source device of the present invention, a light modulation element that modulates light emitted from the light source device, and a projection optical system that projects light modulated by the light modulation element. It is characterized by.
According to the present invention, a small projector having excellent reliability can be realized.

1 is a schematic configuration diagram illustrating a projector according to a first embodiment of the invention. It is a front view of the fluorescent substance wheel used for a projector. It is a figure which shows the polarization separation characteristic of the dichroic mirror used for a projector. It is a schematic block diagram which shows the projector of 2nd Embodiment of this invention. It is a figure which shows the polarization separation characteristic of the dichroic mirror used for a projector.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
The projector according to this embodiment is a light source device that outputs white light, a color separation optical system that color-separates white light obtained from the light source device, and three color lights that are obtained by the color separation optical system. This is an example of a so-called three-plate type liquid crystal projector provided with two liquid crystal light valves.
FIG. 1 is a schematic configuration diagram illustrating a projector according to the present embodiment. FIG. 2 is a front view of a phosphor wheel used in the projector. FIG. 3 is a diagram illustrating polarization separation characteristics of a dichroic mirror used in the projector.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  As shown in FIG. 1, the projector 1 of the present embodiment includes a light source device 2, a color separation optical system 3, a liquid crystal light valve 4R (light modulation element), a liquid crystal light valve 4G, and a liquid crystal light valve 4B, and color synthesis. An element 5 and a projection optical system 6 are provided. In the projector 1 of the present embodiment, the light emitted from the light source device 2 is separated into a plurality of color lights by the color separation optical system 3. The plurality of color lights separated by the color separation optical system 3 are incident on the corresponding liquid crystal light valve 4R, liquid crystal light valve 4G, and liquid crystal light valve 4B and modulated. A plurality of color lights modulated by the liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B are incident on the color synthesis element 5 and synthesized. The light synthesized by the color synthesizing element 5 is enlarged and projected onto the screen 7 by the projection optical system 6, and a full-color projection image is displayed.

Hereinafter, each component of the projector 1 will be described.
The light source device 2 includes a laser light source 9 (solid light source), a dichroic mirror 10, a quarter wavelength plate 11 (retardation plate), a phosphor wheel 12 (light emitting element), a collimating optical system 13, lens arrays 14 and 15, and polarization. The conversion element 16 and the superimposing lens 17 are arranged in this order.

    The laser light source 9 emits blue laser light having a central wavelength of emission intensity of 450 nm, for example, as excitation light that excites phosphors included in the phosphor wheel 12 described later. The blue laser light emitted from the laser light source 9 is linearly polarized light having a constant polarization state, and the polarization state with respect to the selective reflection surface 10a of the dichroic mirror 10 is P-polarized light. In the present embodiment, the wavelength 450 nm corresponds to the first wavelength region, and the P-polarized light corresponds to the first polarization component. Although the laser light source 9 is shown as an example in which one laser light source is used in FIG. 1, for example, a plurality of laser light sources may be juxtaposed. In addition, a laser light source that emits colored light having a center wavelength other than 450 nm may be used as long as it has a wavelength that can excite a phosphor to be described later.

  The dichroic mirror 10 is disposed on the optical path of the excitation light between the laser light source 9 and the phosphor wheel 12. The selective reflection surface 10 a of the dichroic mirror 10 forms an angle of 45 degrees with respect to the optical axis of the excitation light L <b> 1 emitted from the laser light source 9 toward the phosphor wheel 12 and entering the dichroic mirror 10. In a state where the angle formed by the selective reflection surface 10a and the optical axis of the excitation light L1 is 45 degrees, the dichroic mirror 10 transmits the P-polarized blue laser light having a central wavelength of the emission intensity of 450 nm and the emission intensity. It has a polarization separation characteristic that reflects S-polarized blue laser light having a central wavelength of 450 nm and fluorescence in a yellow wavelength region having a central wavelength of emission intensity of 550 nm. The polarization separation characteristics of the dichroic mirror 10 will be described in detail later. In the present embodiment, the wavelength 550 nm corresponds to the second wavelength region, and the S-polarized light corresponds to the second polarization component.

  The quarter wave plate 11 is disposed on the optical path of the excitation light between the phosphor wheel 12 and the dichroic mirror 10. Therefore, excitation light that passes from the laser light source 9 through the dichroic mirror 10 and travels toward the phosphor wheel 12, excitation light that is reflected by the phosphor wheel 12 and returns to the dichroic mirror 10, and fluorescence emitted from the phosphor wheel 12 are generated. It passes through the quarter wave plate 11. In the following description, the excitation light transmitted from the laser light source 9 through the dichroic mirror 10 and directed to the phosphor wheel 12 is the excitation light L1 in the forward path, and the excitation light reflected by the phosphor wheel 12 and returned to the dichroic mirror 10. Is referred to as a return path excitation light L2. Since the fluorescence emitted from the phosphor wheel 12 does not have a uniform polarization state, the quarter-wave plate 11 does not act on the polarization state of the fluorescence. On the other hand, since the excitation light emitted from the laser light source 9 has the polarization state aligned with the P polarization, the quarter wavelength plate 11 acts on the polarization state of the excitation light. That is, the quarter-wave plate 11 gives a half-wave phase difference between the forward excitation light L1 and the return excitation light L2 in a reciprocating manner, and changes the polarization state of the return excitation light from P-polarized light to S-polarized light. Convert.

  The phosphor wheel 12 is provided on the support substrate 19 (support base material), the reflection film 20 (reflection surface) provided on one surface 19 a (support surface) of the support substrate 19, and the reflection film 20. And a light emitting layer 21 (phosphor layer). The light emitting layer 21 includes phosphor particles (not shown), and is supported by the support surface 19 a of the support substrate 19 through the reflective film 20. The phosphor wheel 12 is disposed such that the support surface 19a faces the laser light source 9, and the light emitting layer 21 is irradiated with excitation light from the laser light source 9. The phosphor wheel 12 reflects a part of excitation light (blue laser light having a central wavelength of emission intensity of 450 nm) emitted from the laser light source 9. The phosphor wheel 12 absorbs the remainder of the excitation light and converts it into yellow fluorescence having a central wavelength of emission intensity of 550 nm, and reflects the generated yellow fluorescence to emit it toward the dichroic mirror 10. .

  As shown in FIG. 2, the planar shape when the phosphor wheel 12 is viewed from the laser light source 9 side is a circle. The support surface 19a of the support substrate 19 is divided into eight regions. On the support surface 19a of the support substrate 19, four light-emitting regions C where the light-emitting layer 21 is provided and four non-light-emitting regions where the light-emitting layer 21 is not provided. D are alternately arranged in the circumferential direction. In the present embodiment, the light emitting region C corresponds to the first region of the support surface 19a, and the non-light emitting region D corresponds to the second region of the support surface 19a.

    The support substrate 19 can be formed using, for example, an inorganic material such as glass or ceramic, a metal such as copper, or a resin such as acrylic. These materials are excellent in terms of light weight, low cost, and good workability. Further, among glass, materials such as quartz glass and neoceram have low linear expansion and excellent heat resistance. Further, among glass, materials such as quartz and sapphire have high thermal conductivity and excellent heat dissipation.

  A reflective film 20 is formed on the support surface 19 a of the support substrate 19. The reflective film 20 is formed over the entire support surface 19 a of the support substrate 19, and thus is formed over both the light emitting region C and the non-light emitting region D. Therefore, the excitation light emitted from the laser light source 9 and the fluorescence emitted from the light emitting layer 21 are reflected by the reflective film 20. As the material of the reflective film 20, a metal having a high light reflectance such as aluminum or silver, a dielectric multilayer film in which a plurality of layers of silicon oxide and titanium oxide are alternately stacked, or the like is used.

  Instead of forming the reflective film 20 on the support surface of the support substrate 19 that does not have light reflectivity, the support substrate itself may be formed of a material having light reflectivity. Specifically, instead of an inorganic material such as glass or ceramic, a resin, or the like, a metal such as aluminum or silver may be used as the material for the support substrate. When a metal is used for the material of the support substrate, the surface of the support substrate becomes a reflection surface as it is, so that it is not necessary to form a reflection film, and the manufacturing process of the phosphor wheel 12 can be simplified. Further, when a metal is used as the material for the support substrate, the heat generated by the phosphor is easily transmitted within the surface of the phosphor wheel, so that the maximum temperature reached by the phosphor can be lowered. As a result, the reliability of the phosphor wheel can be improved, and the conversion efficiency of excitation light can be improved.

  The light emitting layer 21 includes a light-transmitting base material and a plurality of phosphor particles that emit fluorescence by absorbing excitation light. As the constituent material of the base material, a resin material having optical transparency can be used, and among them, a silicon resin having a high heat resistance (refractive index: about 1.4) can be suitably used. The phosphor particles are particulate phosphors that absorb the excitation light emitted from the laser light source 9 and emit fluorescence. For example, the phosphor particles include a substance that emits fluorescence when excited by blue light having a center wavelength of 450 nm, and a part of the excitation light emitted from the laser light source 9 is changed from the red wavelength band to the green wavelength band. The light is converted into light having a relatively broad wavelength distribution including (up to the yellow wavelength region as a whole) and emitted.

As such phosphor particles, 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, commonly known YAG (yttrium, aluminum, garnet) phosphors can be used. Specifically, 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) is used. it can. The phosphor particle forming material may be one kind, or a mixture of particles formed using two or more kinds of forming materials may be used as the phosphor particles.

    As shown in FIG. 1, the phosphor wheel 12 has a motor 22 connected to the center of the support substrate 19, and is provided so as to be rotatable about a rotation shaft 23 passing through the center of the support substrate 19. The motor 22 rotates the phosphor wheel 12 at, for example, 7500 rpm when in use. In this case, the region (beam spot) irradiated with the excitation light on the phosphor wheel 12 moves at about 18 m / sec. That is, the motor 22 functions as a position displacement unit that displaces the position of the beam spot on the phosphor wheel 12. Thereby, since excitation light does not continue irradiating the same position on the fluorescent substance wheel 12, the thermal deterioration of an irradiation position can be prevented and a lifetime of an apparatus can be extended.

  In the case of the present embodiment, since the phosphor wheel 12 has the light emitting region C and the non-light emitting region D, yellow fluorescence is emitted from the phosphor wheel 12 during the period in which the excitation light irradiates the light emitting region C. During the period when the excitation light is radiating the non-light emitting region D, the blue excitation light reflected by the reflective film 20 is emitted from the phosphor wheel 12. As described above, in the phosphor wheel 12, since the four light emitting regions C and the four non-light emitting regions D are alternately arranged in the circumferential direction, blue light, yellow light, Blue light, yellow light,... Are emitted while being alternately switched every 1 msec. At this time, for the human eye, blue light and yellow light are temporally integrated, and it appears that white light, which is a combined light of blue light and yellow light, is emitted. Further, by changing the area ratio between the light emitting region C and the non-light emitting region D of the phosphor wheel 12, the ratio of the amount of blue light emitted from the phosphor wheel 12 to the amount of yellow light can be changed. Light color adjustment can be performed.

    The collimating optical system 13 includes a first lens 25 that suppresses the spread of light emitted from the phosphor wheel 12, and a second lens 26 that substantially collimates the light incident from the first lens 25. The light emitted from the phosphor wheel 12 is made parallel. The 1st lens 25 and the 2nd lens 26 are comprised by the convex lens.

    The lens arrays 14 and 15 make the luminance distribution of the light emitted from the collimating optical system 13 uniform. The lens array 14 has a plurality of first microlenses 27 arranged in a matrix. Similarly, the lens array 15 includes a plurality of second microlenses 28 arranged in a matrix. The first microlens 27 and the second microlens 28 have a one-to-one correspondence. The light emitted from the collimating optical system 13 is spatially divided and incident on the plurality of first microlenses 27. The first microlens 27 forms an image of the incident light on the corresponding second microlens 28. Thereby, a secondary light source image is formed on each of the plurality of second microlenses 28. Note that the outer shapes of the first microlens 27 and the second microlens 28 are substantially similar to the outer shapes of the image forming areas of the liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B.

    The polarization conversion element 16 aligns the polarization state of the light emitted from the lens arrays 14 and 15. The polarization conversion element 16 includes a plurality of polarization conversion cells. Each polarization conversion cell has a one-to-one correspondence with the second microlens 28. The light from the secondary light source image formed on the second microlens 28 enters the incident area of the polarization conversion cell corresponding to the second microlens 28.

    Each polarization conversion cell is provided with a polarization beam splitter film (hereinafter referred to as a PBS film) and a phase difference plate corresponding to the incident region. The light incident on the incident region is separated into P-polarized light and S-polarized light with respect to the PBS film by the PBS film. One of the P-polarized light and S-polarized light (here, S-polarized light) is reflected by the reflecting member and then enters the phase difference plate. The S-polarized light incident on the phase difference plate is converted into the polarization state of the other polarization (here, P-polarized light) by the phase difference plate, becomes P-polarized light, and is emitted together with the P-polarized light.

    The superimposing lens 17 superimposes the light emitted from the polarization conversion element 16 on the liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B that are illuminated areas. The light emitted from the light source device 2 is spatially divided and then superimposed, whereby the luminance distribution is made uniform and the axial symmetry about the light axis is enhanced.

    The color separation optical system 3 includes a dichroic mirror 30, a dichroic mirror 31, a mirror 32, a mirror 33, a mirror 34, a field lens 35R, a field lens 35G, a field lens 35B, a relay lens 36, and a relay lens 37. The dichroic mirror 30 and the dichroic mirror 31 are formed, for example, by laminating a dielectric multilayer film on a glass surface. The dichroic mirror 30 and the dichroic mirror 31 have characteristics of selectively reflecting color light in a predetermined wavelength band and transmitting color light in other wavelength bands. Here, the dichroic mirror 30 reflects green light and blue light, and the dichroic mirror 31 reflects green light.

    The light L emitted from the light source device 2 enters the dichroic mirror 30. Of the light L, red light LR is transmitted through the dichroic mirror 30 and incident on the mirror 32, and is reflected by the mirror 32 and incident on the field lens 35R. The red light LR is collimated by the field lens 35R and then enters the liquid crystal light valve 4R for red light modulation.

    Green light LG and blue light LB in the light L are reflected by the dichroic mirror 30 and enter the dichroic mirror 31. The green light LG is reflected by the dichroic mirror 31 and enters the field lens 35G. The green light LG is collimated by the field lens 35G and then enters the liquid crystal light valve 4G for green light modulation.

    The blue light LB that has passed through the dichroic mirror 31 passes through the relay lens 36, is reflected by the mirror 33, passes through the relay lens 37, is reflected by the mirror 34, and enters the field lens 35B. The blue light LB is collimated by the field lens 35B and then enters the liquid crystal light valve 4B for blue light modulation. Since the optical path of the blue light LB is longer than the optical path of the other red light LR and the optical path of the green light LG, the optical path of the blue light LB is included for the purpose of compensating for the loss of light due to the long optical path length. Such a relay optical system is applied.

    The liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B are constituted by transmissive liquid crystal light valves. The liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B are electrically connected to a signal source (not shown) such as a personal computer that supplies an image signal including image information. The liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B modulate the incident light for each pixel based on the supplied image signal to form an image. The liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B form a red image, a green image, and a blue image, respectively. The light (formed image) modulated by the liquid crystal light valve 4R, the liquid crystal light valve 4G, and the liquid crystal light valve 4B enters the color composition element 5.

    The color synthesizing element 5 is constituted by a dichroic prism. 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 and transmits green light and a mirror surface that reflects blue light and transmits green light are formed orthogonal to each other. The green light incident on the dichroic prism goes straight through the mirror surface and is emitted. The red light and blue light 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. In this way, the three color lights (images) are superimposed and synthesized, and the synthesized color lights are enlarged and projected onto the screen 7 by the projection optical system 6.

Hereinafter, the operation of the dichroic mirror 10 and the quarter wavelength plate 11 in the light source device 2 of the present embodiment will be described.
FIG. 3 is a diagram showing the polarization separation characteristics of the dichroic mirror 10 in the light source device 2 of the present embodiment. The horizontal axis of FIG. 3 is the wavelength of light [nm], and the vertical axis is the reflectance of light (= the amount of reflected light / the amount of incident light) [%]. The dichroic mirror 10 has different reflection characteristics depending on whether the polarized light incident on the selective reflection surface 10a is P-polarized light or S-polarized light. The solid line in FIG. 3 indicates the reflectance of P-polarized light, and the broken line indicates The reflectance of S-polarized light is shown.

  As shown in FIG. 3, the dichroic mirror 10 of the present embodiment reflects the light at approximately 475 nm with respect to the P-polarized light in a state where the angle formed by the selective reflection surface 10a and the optical axis of the excitation light L1 is 45 degrees. The rate changes. For example, the reflectivity for blue light having a wavelength of 450 nm is approximately 0%, and substantially the entire amount of blue light having a wavelength of 450 nm is transmitted. On the other hand, for example, the reflectance for yellow light having a wavelength of 550 nm is approximately 100%, and substantially the entire amount of yellow light having a wavelength of 550 nm is reflected. For S-polarized light, the reflectance changes approximately in the vicinity of 425 nm. For example, the reflectance with respect to blue light having a wavelength of 450 nm and the reflectance with respect to yellow light having a wavelength of 550 nm are both approximately 100%, and substantially all of the light is reflected.

  In the present embodiment, since the laser light source 9 emits P-polarized blue light having a central wavelength of 450 nm as the excitation light L1, the excitation light L1 is selectively reflected by the dichroic mirror 10 having the polarization separation characteristics shown in FIG. The surface 10a can be transmitted. As shown in FIG. 1, when the forward excitation light L1 that has passed through the dichroic mirror 10 passes through the quarter-wave plate 11, the phase advances by 1/4 wavelength, so that the P-polarized light is converted into, for example, clockwise circularly-polarized light. The The forward excitation light L1 that has become clockwise circularly polarized light is then reflected by the phosphor wheel 12, and the phase advances by 1/2 wavelength due to this reflection, so that the clockwise circularly polarized light becomes counterclockwise circularly polarized light. Converted. When the backward excitation light L2 that has become counterclockwise circularly polarized light passes through the quarter-wave plate 11, the phase is delayed by a quarter wavelength, so that the counterclockwise circularly polarized light is converted to S-polarized light. The blue light having a center wavelength of 450 nm converted to S-polarized light is reflected by the selective reflection surface 10a of the dichroic mirror 10 having the polarization separation characteristics shown in FIG. Further, yellow fluorescence emitted from the phosphor wheel 12 and having a center wavelength of 550 nm is reflected by the selective reflection surface 10a of the dichroic mirror 10 regardless of the polarization state.

  If the dichroic mirror 10 does not have the polarization separation characteristic as shown in FIG. 3, the return path excitation light L2 may pass through the dichroic mirror 10 and the optical path may not be changed toward the subsequent optical system. In the present embodiment, since white light is generated by blue excitation light and yellow fluorescence, desired white light cannot be obtained. In that respect, the light source device 2 of the present embodiment can obtain desired white light because the dichroic mirror 10 has the polarization separation characteristics as shown in FIG.

  In the light source device 2 of the present embodiment, the optical path of the excitation light emitted from the laser light source 9 is folded back by the phosphor wheel 12, and the excitation light and the fluorescence are emitted from the phosphor wheel 12 toward the laser light source 9. On the way, the light is reflected by the dichroic mirror 10 toward the subsequent optical system. In this way, the light source device 2 can be downsized by using the reflective phosphor wheel 12 and turning the optical path back. Moreover, since the support substrate 19 of the phosphor wheel 12 is excellent in thermal conductivity, the temperature rise of the phosphor is suppressed, reliability can be ensured, and the phosphor conversion efficiency can be increased.

  In the present embodiment, an example in which white light is generated by blue light emitted from the laser light source 9 and yellow light emitted from the phosphor wheel 12 is shown, but the present invention is not limited to this configuration. For example, a red light emitting region provided with a phosphor that emits red light using blue light as excitation light, a green light emitting region provided with a phosphor that emits green light using blue light as excitation light, and a phosphor are not provided. A phosphor wheel including a non-light emitting region that reflects blue light that is excitation light may be used. In this case, red light, green light, and blue light are emitted while being sequentially switched during one rotation of the phosphor wheel, and white light obtained by combining these lights is obtained. For example, red light is fluorescence including the second wavelength region, green light is fluorescence including the third wavelength region, and the red light emitting region corresponds to, for example, the first region of the support surface 19a. .

  Further, for example, white, yellow, and black-green light may be added to these three primary colors to form four colors, thereby widening the expression range of colors, gradations, luminances, and the like. Or if it is set as the structure which arranges the area | region of the same characteristic in one fluorescent substance wheel periodically and repeatedly, a color breakup can be reduced. For example, one phosphor wheel is divided into six areas, and these areas are divided into a red light emission area, a green light emission area, a non-light emission area (blue light emission area), a red light emission area, a green light emission area, and a non-light emission area ( Blue light emission areas) may be assigned in this order.

In the present embodiment, as described with reference to FIG. 3, the reflectance Rp for P-polarized blue light having a wavelength of 450 nm is approximately 0%, and the reflectance Rs for S-polarized blue light having a wavelength of 450 nm is approximately A dichroic mirror 10 that is 100% is used. Although it is preferable that the difference between the reflectance Rp and the reflectance Rs is large, it is not always necessary that the reflectance Rp is approximately 0% and the reflectance Rs is approximately 100%.
For example, the forward excitation light L1 in which the P polarization component is dominant over the S polarization component is incident on the dichroic mirror 10, and the return excitation light L2 in which the S polarization component is dominant over the P polarization component is incident on the dichroic mirror 10. In the first wavelength region included in the excitation light L1, it is sufficient that the reflectance for the S-polarized component is higher than the reflectance for the P-polarized component. In this way, the dominant P-polarized component of the elliptically polarized excitation light L1 passes through the dichroic mirror 10 and enters the light emitting layer 21, and is dominant among the elliptically polarized excitation light L2 reflected by the phosphor wheel 12. S-polarized components are reflected by the dichroic mirror 10 toward the subsequent optical system. Therefore, a light source device with high efficiency can be realized.
Similarly, the forward excitation light L1 in which the S polarization component is dominant over the P polarization component enters the dichroic mirror 10, and the return excitation light L2 in which the P polarization component is dominant over the S polarization component enters the dichroic mirror 10. In this case, it is sufficient that the reflectance for the P-polarized component is higher than the reflectance for the S-polarized component in the first wavelength region included in the excitation light L1.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the projector of this embodiment is the same as that of the first embodiment, except that an auxiliary solid-state light source is provided in the light source device.
FIG. 4 is a schematic configuration diagram illustrating the projector according to the present embodiment. FIG. 5 is a diagram showing polarization separation characteristics of a dichroic mirror used in the light source device.
In FIG. 4, the same reference numerals are given to the same components as those in FIG. 1 of the first embodiment, and detailed description thereof will be omitted.

  In the projector 41 of the present embodiment, as shown in FIG. 4, the light source device 42 includes an auxiliary laser light source 43 (auxiliary solid light source) in addition to the laser light source 9. The auxiliary laser light source 43 is disposed such that the optical path of the emitted light L3 is orthogonal to the optical path of the excitation light L1 from the laser light source 9 and forms an angle of 45 degrees with respect to the selective reflection surface 44a of the dichroic mirror 44. The auxiliary laser light source 43 may emit color light having the same color as that emitted from the laser light source 9 (excitation light), or may emit color light having the same color as the fluorescence emitted from the phosphor wheel 12. Alternatively, the light emitted from the laser light source 9 or the color light different from the fluorescence emitted from the phosphor wheel 12 may be emitted. The auxiliary laser light source 43 of this embodiment emits red light having a center wavelength of 660 nm. The auxiliary laser light source 43 can be turned on / off independently of the laser light source 9.

  As shown in FIG. 5, the dichroic mirror 44 of the present embodiment is different in polarization separation characteristics from the dichroic mirror 10 of the first embodiment. Specifically, in the case of this embodiment, the polarization separation characteristic on the short wavelength side is the same as that of the first embodiment, but the polarization separation characteristic on the long wavelength side is different. For P-polarized light, the reflectance changes approximately in the vicinity of 625 nm in addition to in the vicinity of 475 nm. For example, the reflectance for red light having a wavelength of 660 nm is approximately 0%, and substantially the entire amount of red light having a wavelength of 660 nm is transmitted. Therefore, the dichroic mirror 44 exhibits the same behavior as the first embodiment with respect to the excitation light emitted from the laser light source 9 and the fluorescence emitted from the phosphor wheel 12, and the P-polarized light emitted from the auxiliary laser light source 43. The red light is transmitted through the selective reflection surface 44a. Thus, the red light emitted from the auxiliary laser light source 43 travels toward the subsequent optical system together with the blue light emitted from the laser light source 9 and the yellow light emitted from the phosphor wheel 12.

  Also in the present embodiment, the same effects as those of the first embodiment can be obtained, such as providing a light source device and a projector that can ensure high reliability and reduce the size of the device. Furthermore, in the case of the present embodiment, the light source device 42 includes the auxiliary laser light source 43 that can be individually controlled. Therefore, by appropriately selecting the color and light amount of the light emitted from the auxiliary laser light source 43, the color and gradation are selected. The range of expression such as brightness can be freely expanded.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, white light is synthesized by blue excitation light emitted from a laser light source and yellow fluorescence emitted from a phosphor wheel, or red fluorescence, green fluorescence, and blue excitation light are combined. An example of a projector having a configuration in which white light is synthesized, and the obtained white light is separated into red light, green light, and blue light by a color separation optical system and led to three light modulation elements is shown. Instead of this configuration, one light modulation element is driven in time division in synchronization with emission of red fluorescence, green fluorescence, and blue excitation light in time division, and images for red light and green light are used. A projector that is configured to display a full-color image by sequentially displaying an image and an image for blue light, a so-called single-plate projector may be used. In this case, a liquid crystal light valve may be used as the light modulation element, but DMD (Digital Micromirror Device: registered trademark of TI) may be used. Moreover, although the example of the fluorescent substance wheel was demonstrated as a light emitting element, you may use the fluorescent element provided with the light emitting layer on the fixed flat plate. In addition, the constituent material, shape, number, arrangement, and the like of each component of the projector shown in the above embodiment can be appropriately changed.

  DESCRIPTION OF SYMBOLS 1,41 ... Projector, 2,42 ... Light source device, 4R, 4G, 4B ... Liquid crystal light valve (light modulation element), 9 ... Laser light source (solid light source), 10, 44 ... Dichroic mirror, 11 ... 1/4 wavelength Plate (retardation plate), 12 ... phosphor wheel (light emitting element), 19 ... support substrate (support base material), 20 ... reflection film, 21 ... light emitting layer, 43 ... auxiliary laser light source (auxiliary solid light source).

Claims (7)

A solid-state light source that emits excitation light including a first wavelength region;
Provided is a phosphor layer including a phosphor that emits fluorescence including a second wavelength region different from the first wavelength region by irradiation of the excitation light, and a support substrate having a support surface that supports the phosphor layer. A light emitting element;
A dichroic mirror provided on the optical path of the excitation light between the solid-state light source and the light-emitting element;
A retardation plate provided on the optical path of the excitation light between the light emitting element and the dichroic mirror,
The support substrate includes a reflective surface that reflects the excitation light and the fluorescence;
The dichroic mirror reflects the fluorescence and has a lower reflectance for the first polarization component in the first wavelength region than a reflectance for the second polarization component in the first wavelength region,
The phosphor layer is provided in a first region of the support surface of the support substrate, and the phosphor layer is not provided in a second region of the support surface,
A light source device characterized in that a reflective film constituting the reflective surface is provided over both the first region and the second region. The first polarization component is either P-polarized light or S-polarized light with respect to the reflecting surface of the dichroic mirror, and the second polarization component is the other of the P-polarized light and the S-polarized light. ,
The light source device according to claim 1, wherein the retardation plate is a ¼ wavelength plate for the first wavelength region.   The light source device according to claim 1, wherein the support base is made of a metal substrate.   The second phosphor layer that emits fluorescence including a third wavelength region different from the second wavelength region is provided in the light emitting element. The light source device described.   5. The light source device according to claim 1, further comprising an auxiliary solid-state light source that emits light including a wavelength region different from the first wavelength region.   6. The light source device according to claim 1, wherein the support base material is rotatable about a rotation axis that intersects the support surface. 7.   A light source device according to any one of claims 1 to 6, a light modulation element that modulates light emitted from the light source device, a projection optical system that projects light modulated by the light modulation element, A projector characterized by comprising:

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