JP2012123180A - Light source device and projector - Google Patents

Abstract

A light source device and a projector capable of ensuring high reliability and reducing the size of the device.
A light source device of the present invention includes a laser light source that emits excitation light, a phosphor wheel that transmits a part of the excitation light, emits fluorescence, and reflects the excitation light and fluorescence; A dichroic mirror 10 provided between the laser light source 9 and the phosphor wheel 12. The forward excitation light L1 is incident on the dichroic mirror 10 at a first incident angle θ1, and the backward excitation light L2 and fluorescence are incident at a second incident angle θ2 larger than the first incident angle. The mirror 10 transmits the excitation light L1 incident at the first incident angle and reflects the excitation light L2 and fluorescence incident at the second incident angle.
[Selection] Figure 1

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 by irradiating phosphors 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. Then, a plurality of types of phosphors are divided into regions in the circumferential direction of the wheel, and formed as a phosphor film. By rotating the wheel and irradiating a plurality of phosphor films with excitation light, the color of the emitted fluorescence is changed over time. It is different. 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 of Patent Document 1 described above, 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 having a selective reflection surface provided on the optical path, and the support base material includes a reflection surface that reflects the excitation light and the fluorescence, and the excitation light is incident on the selective reflection surface. The angle is smaller than the incident angle of the reflected light of the excitation light by the reflection surface with respect to the selective reflection surface.

  In the configuration of the present invention, a part of the excitation light that has not been used for exciting the phosphor, that is, the light that is a combination of the reflected light of the excitation light by the reflecting surface of the support base and the fluorescence emitted from the phosphor is synthesized. Output from the light source device. Since the support base material that constitutes the light emitting element has a reflection surface that reflects excitation light and fluorescence, the excitation light emitted from the solid-state light source is reflected by the reflection surface of the support base material of the light emitting element, and is also fluorescent. Fluorescence emitted from the body 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 reflected light and fluorescence of the excitation light 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 selective reflection surface of the dichroic mirror is arranged so as to be orthogonal to the optical axis of the excitation light, the excitation light directed to the light emitting element passes through the selective reflection surface, and then the fluorescence emitted by the light emitting element is reflected on the selective reflection surface. On the other hand, the reflected light of the excitation light from the light emitting element passes through the selective reflection surface again 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 respect, according to the present invention, the excitation light traveling toward the light emitting element can pass through the dichroic mirror and reach the light emitting element. Further, the combined light of the excitation light reflected by the reflecting surface and the fluorescence can be reflected by the dichroic mirror toward the subsequent optical system. Thereby, the light source device which can obtain desired output light is realizable. Note that in this specification, the excitation light directed to the light emitting element is simply referred to as excitation light, and the reflected light of the excitation light from the reflecting surface is simply referred to as reflected light.

The light source device of the present invention is characterized in that a reflectance of the excitation light reflected by the reflection surface by the selective reflection surface is larger than a reflectance of the excitation light by the selective reflection surface.
According to this configuration, the excitation light traveling toward the light emitting element can pass through the dichroic mirror and reach the light emitting element. Further, the combined light of the reflected light and the fluorescence can be reflected by the dichroic mirror toward the subsequent optical system. Thereby, the light source device which can obtain desired output light is realizable.

  In the light source device of the present invention, the excitation light includes a first polarization component in the first wavelength region, and on the optical path of the excitation light and the reflected light between the light emitting element and the selective reflection surface. A phase difference plate is provided on at least one of the optical paths of the optical path, and the polarization state of the reflected light when the reflected light is incident on the selective reflection surface is selected by the excitation light toward the light emitting element. Unlike the polarization state of the excitation light when entering the reflection surface, the dichroic mirror reflects the fluorescence and has a reflectance with respect to the first polarization component in the first wavelength region. It is good also as a structure lower than the reflectance with respect to the 2nd polarization | polarized-light component in a wavelength range.

  In this configuration, since the phase difference plate is provided between the light emitting element and the selective reflection surface on the optical path of the excitation light and the optical path of the reflected light, the reflected light is selectively reflected on the selective reflection surface. The polarization state of the reflected light when entering the light source is different from the polarization state of the excitation light when the excitation light is incident on the selective reflection surface toward the light emitting element. Furthermore, the dichroic mirror reflects fluorescence and has a lower reflectance for the first polarization component in the first wavelength region than for the second polarization component in the first wavelength region. That is, the selective reflection characteristic of the dichroic mirror has polarization dependency in addition to incident angle dependency. Therefore, for example, even when the incident angle dependency of the dichroic mirror is not so great and the separation between the excitation light and the reflected light is not good, the reflected light is incident on the selective reflection surface using the phase difference plate. The polarization state of the reflected light is different from the polarization state of the excitation light when the excitation light is incident on the selective reflection surface toward the light emitting element, and the dichroic mirror is made to have polarization dependence, thereby Separation from reflected light can be improved. When such a dichroic mirror is used, the first polarization component of the excitation light is efficiently transmitted through the dichroic mirror, and the second polarization component of the reflected light is efficiently reflected by the dichroic mirror. Thereby, a light source device with high light utilization efficiency can be realized.

In the light source device of the present invention, the first polarization component is either P-polarization or S-polarization with respect to the selective reflection surface, and the second polarization component is the P-polarization or the S-polarization. The other is the other, the retardation plate is provided on the optical path of the excitation light and the optical path of the reflected light between the light emitting element and the selective reflection surface, and the retardation plate is the first retardation plate. A quarter-wave plate for one wavelength region is desirable.
According to this configuration, if the polarization state of the excitation light is, for example, P polarization, the polarization state of the reflected light can be changed to S polarization. Accordingly, it is possible to reliably realize a configuration in which excitation light is transmitted toward the optical element by the dichroic mirror and reflected light is reflected toward the subsequent optical system.

  In the light source device of the present invention, the first polarization component is either P-polarization or S-polarization with respect to the selective reflection surface, and the second polarization component is the P-polarization or the S-polarization. The other, the phase difference plate is provided only on either the optical path of the excitation light or the optical path of the reflected light between the light emitting element and the selective reflection surface, It is desirable that the retardation plate is a half-wave plate for the first wavelength region.

  According to this configuration, if the polarization state of the excitation light is, for example, P polarization, the polarization state of the reflected light can be changed to S polarization. Accordingly, it is possible to reliably realize a configuration in which excitation light is transmitted toward the optical element by the dichroic mirror and reflected light is reflected toward the subsequent optical system.

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 of the phosphor layer.
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 light source device. It is a figure which shows the characteristic of the dichroic mirror used for a light source device. It is a schematic block diagram which shows the projector of 2nd Embodiment of this invention. It is a figure which shows the characteristic of the dichroic mirror used for a light source device. It is a schematic block diagram which shows the projector of 2nd Embodiment of this invention. It is a figure which shows the characteristic of the dichroic mirror used for a light source device.

[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 light source device of the projector according to the present embodiment.
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.
In the light source device 2, a laser light source 9 (solid light source), a dichroic mirror 10, a phosphor wheel 12 (light emitting element), a collimating optical system 13, lens arrays 14 and 15, a polarization conversion element 16, and a superimposing lens 17 are arranged in this order. It has a configuration.

    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. In the present embodiment, the wavelength 450 nm corresponds to the first wavelength region. 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 positional relationship of the three optical elements of the dichroic mirror 10, the laser light source 9, and the phosphor wheel 12 will be described below with the dichroic mirror 10 as the center. The dichroic mirror 10 has an angle θ1 (incident angle of excitation light) formed by the optical axis of excitation light emitted from the laser light source 9 toward the phosphor wheel 12 and the normal line of the selective reflection surface 10a of the dichroic mirror 10 is 45. It is arranged to be a degree. The dichroic mirror 10 is arranged such that an angle θ2 (incident angle of reflected light) formed by the optical axis of the reflected light of the excitation light from the phosphor wheel 12 and the normal line of the selective reflection surface 10a of the dichroic mirror 10 is 60 degrees. Has been.
In the following description, the excitation light that passes through the dichroic mirror 10 from the laser light source 9 and travels toward the phosphor wheel 12 is referred to as excitation light L1, and the reflected light of the excitation light L1 by the phosphor wheel 12 is reflected light L2. Called.

  The dichroic mirror 10 transmits blue laser light (excitation light L1) having a central wavelength of emission intensity of 450 nm and an incident angle of 45 degrees, while blue laser light having a central wavelength of emission intensity of 450 nm and an incident angle of 60 degrees ( It has a characteristic of reflecting the reflected light L2). The dichroic mirror 10 has a characteristic of reflecting yellow fluorescent light having a central wavelength of luminescence intensity of 550 nm regardless of the incident angle. The selective reflection characteristics of the dichroic mirror 10 will be described in detail later.

  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) made of a phosphor. 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 has a support surface 19 a disposed toward 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, converts it into yellow fluorescence having a central wavelength of emission intensity of 550 nm, and reflects the generated yellow fluorescence to be emitted toward the dichroic mirror 10. . In the present embodiment, the wavelength 550 nm corresponds to the second wavelength region.

  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 reflection film 20 reflects the excitation light emitted from the laser light source 9 and the fluorescence emitted from the light emitting layer 21 by the reflection 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 reflected 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 around the light axis L 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 in the light source device 2 of the present embodiment will be described.
FIG. 3 is a diagram showing selective reflection 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 selective reflection surface of the dichroic mirror is provided with a dielectric multilayer film. If the incident angle changes when light enters the dielectric multilayer film, the effective thickness of the dielectric multilayer film for that light changes. To do. As a result, the dichroic mirror 10 exhibits different reflection characteristics depending on the incident angle of light incident on the selective reflection surface 10a. In FIG. 3, the solid line indicates the reflectance of light having an incident angle of 45 degrees, and the broken line indicates the reflectance of light having an incident angle of 60 degrees.

  As shown in FIG. 3, in the dichroic mirror 10 of the present embodiment, when the incident angle of incident light is 45 degrees, the reflectance changes approximately in the vicinity of 475 nm. For example, the reflectance of 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 of 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. Further, when the incident angle is 60 degrees, the reflectance changes approximately in the vicinity of 425 nm. For example, the reflectance of blue light having a wavelength of 450 nm and the reflectance of yellow light having a wavelength of 550 nm are both approximately 100%, and substantially all of these lights are reflected.

  In the present embodiment, the excitation light L1 (blue light) emitted from the laser light source 9 and having a center wavelength of 450 nm is incident on the dichroic mirror 10 at an incident angle of 45 degrees. Therefore, the excitation light L1 is as shown in FIG. It is possible to transmit the selective reflection surface 10a of the dichroic mirror 10 having a selective reflection characteristic. On the other hand, since the reflected light L2 (blue light) having a center wavelength of 450 nm is incident on the dichroic mirror 10 at an incident angle of 60 degrees, it is reflected by the selective reflection surface 10a of the dichroic mirror 10 having selective reflection characteristics as shown in FIG. To do. The 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 incident angle.

  Thus, since the dichroic mirror 10 of this embodiment has selective reflection characteristics as shown in FIG. 3, the excitation light L1 is incident on the dichroic mirror 10 at an incident angle θ1 = 45 degrees, and the reflected light L2 is dichroic. Desired white light can be obtained by setting the positional relationship of each component so as to be incident on the mirror 10 at an incident angle θ2 = 60 degrees.

  In the light source device 2 of the present embodiment, the optical path of the excitation light L1 emitted from the laser light source 9 is folded back by the phosphor wheel 12, and is emitted from the phosphor wheel 12 toward the laser light source 9 as reflected light L2. Further, the fluorescence generated by the light emitting layer 21 is also emitted from the phosphor wheel 12 toward the laser light source 9. The reflected light L2 and fluorescence emitted from the phosphor wheel 12 are 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. .

  In the present embodiment, as described with reference to FIG. 3, the reflectance R1 of the excitation light L1 having an incident wavelength of 450 nm at 45 degrees is substantially 0%, and the reflected light having a wavelength of 450 nm incident at 60 degrees is approximately 0%. A dichroic mirror 10 having a reflectance R2 of L2 of approximately 100% is used. Although it is preferable that the difference between the reflectance R1 and the reflectance R2 is large, the reflectance R1 is not necessarily about 0% and the reflectance R2 is not necessarily about 100%. It is sufficient that the incident angle θ2 is larger than the incident angle θ1 and the reflectance R2 is larger than the reflectance R1.

  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.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.
The basic configuration of the projector according to this embodiment is the same as that of the first embodiment, except that the light source device includes a retardation plate.
FIG. 4 is a schematic configuration diagram illustrating the projector according to the present embodiment. FIG. 5 is a diagram illustrating 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 is omitted.

  In the light source device of the projector according to the present embodiment, the blue laser light emitted from the laser light source 9 is linearly polarized light whose polarization state is constant, and the polarization state with respect to the selective reflection surface 44a of the dichroic mirror 44 is P-polarized light. As shown in FIG. 4, the quarter wavelength plate 11 is disposed between the phosphor wheel 12 and the dichroic mirror 44 on the optical path of the excitation light L1 and the optical path of the reflected light L2. Therefore, the excitation light L1 transmitted from the laser light source 9 through the dichroic mirror 44 to the phosphor wheel 12, the reflected light L2 reflected by the phosphor wheel 12 and directed to the dichroic mirror 44, and the phosphor wheel 12 are emitted. The fluorescence passes through the quarter-wave plate 11.

  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 L1 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 L1. The quarter-wave plate 11 also acts on the polarization state of the reflected light L2 of the excitation light that has received the action of the quarter-wave plate 11. That is, the polarization state of the reflected light L2 transmitted through the quarter-wave plate 11 is S-polarized light.

Hereinafter, the operation of the dichroic mirror 44 and the quarter-wave plate 11 in the light source device 2 of the present embodiment will be described.
FIG. 5 is a diagram showing the polarization separation characteristics of the dichroic mirror 44 in the light source device 2 of the present embodiment. The horizontal axis of FIG. 5 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 44 has different reflection characteristics depending on whether the polarized light incident on the selective reflection surface 44a 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.

  As shown in FIG. 5, the reflectivity of the dichroic mirror 44 of this embodiment changes approximately in the vicinity of 475 nm for P-polarized light. 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 with respect to yellow light having a wavelength of 550 nm is substantially 100% regardless of the polarization state, 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 this embodiment, since the laser light source 9 emits P-polarized blue light having a center wavelength of 450 nm as the excitation light L1, the excitation light L1 is selectively reflected by the dichroic mirror 44 having the polarization separation characteristics shown in FIG. The surface 44a can be transmitted. As shown in FIG. 4, when the excitation light L1 that has passed through the dichroic mirror 44 passes through the quarter-wave plate 11, the phase advances by ¼ wavelength, so that the P-polarized light is converted into, for example, clockwise circularly-polarized light. The 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 is converted to counterclockwise circularly polarized light. The Therefore, the reflected light L2 of the excitation light L1 from the phosphor wheel 12 is counterclockwise circularly polarized light. When the reflected light L2 passes through the quarter-wave plate 11, the phase is delayed by a quarter wavelength, so that the counterclockwise circularly polarized light is converted into S-polarized light. The reflected light L2 having a center wavelength of 450 nm converted to S-polarized light is reflected by the selective reflection surface 44a of the dichroic mirror 44 having the polarization separation characteristics shown in FIG. Further, the yellow fluorescence having a center wavelength of 550 nm emitted from the phosphor wheel 12 is reflected by the selective reflection surface 44a of the dichroic mirror 44 having the polarization separation characteristics shown in FIG. 5 regardless of the polarization state.

  The incident angle dependency of the dichroic mirror 44 is not so great. For example, the characteristic of the dichroic mirror 44 with respect to light with an incident angle of 45 degrees is the characteristic indicated by the solid line in FIG. Is the characteristic indicated by the alternate long and short dash line in FIG. When the central wavelength of the excitation light emitted from the laser light source 9 is 450 nm, the excitation light L1 incident at an incident angle of 45 degrees and the reflected light L2 incident at an incident angle of 60 degrees cannot be sufficiently separated, and much of the reflected light L2 Passes through the dichroic mirror 44 and returns to the laser light source 9.

  Thus, even if the incident angle dependency of the dichroic mirror 44 is not so great and the separation between the excitation light L1 and the reflected light L2 is not good, in the light source device 42 of the present embodiment, 1/4. Using the wave plate 11, the polarization state of the reflected light L2 when the reflected light L2 is incident on the selective reflection surface 44a of the dichroic mirror 44, and the excitation state when the excitation light L1 is incident on the selective reflection surface 44a toward the light emitting element. By making the dichroic mirror 44 have the polarization dependence shown by the solid line and the broken line in FIG. 5, the separation property between the excitation light L1 and the reflected light L2 can be improved. it can. When such a dichroic mirror 44 is used, the excitation light L1 is efficiently transmitted through the dichroic mirror 44, while the reflected light L2 is efficiently reflected by the dichroic mirror 44. Thereby, a light source device with high light utilization efficiency can be realized.

In the present embodiment, as described with reference to FIG. 5, the reflectance Rp of P-polarized light having a wavelength of 450 nm is approximately 0%, and the reflectance Rs of S-polarized light having a wavelength of 450 nm is approximately 100%. A dichroic mirror 10 is used. Although it is preferable that the difference between the reflectance Rp and the reflectance Rs is large, the reflectance Rp is not necessarily approximately 0% and the reflectance Rs is not necessarily approximately 100%.
For example, when the 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 reflected light L2 in which the S polarization component is dominant over the P polarization component is incident on the dichroic mirror 10, the excitation light L1 In the first wavelength region included, the reflectance for the S-polarized component should be higher than the reflectance for the P-polarized component. In this way, the dominant P-polarized component of the elliptically polarized excitation light L1 is transmitted through the dichroic mirror 10 and enters the light emitting layer 21, and the dominant S-polarized component of the elliptically polarized reflected light L2 is the dichroic mirror. 10 is reflected toward the subsequent optical system. Therefore, a light source device with high efficiency can be realized.
Similarly, when the excitation light L1 in which the S polarization component is dominant over the P polarization component is incident on the dichroic mirror 10, and the reflected light L2 in which the P polarization component is dominant over the S polarization component is incident on the dichroic mirror 10, In the first wavelength region included in L1, it is sufficient that the reflectance for the P-polarized component is higher than the reflectance for the S-polarized component.

[Modification]
In the second embodiment, the quarter-wave plate 11 as the retardation plate is disposed on the optical path of the excitation light L1 and the optical path of the reflected light L2 between the phosphor wheel 12 and the dichroic mirror 44. . However, the method of using the phase difference plate is not limited to this.
A half-wave plate may be provided as a retardation plate only on the optical path of the excitation light L <b> 1 between the phosphor wheel 12 and the dichroic mirror 44. Alternatively, a half-wave plate may be provided as a retardation plate only on the optical path of the reflected light L2 between the phosphor wheel 12 and the dichroic mirror 44. In any case, as in the second embodiment, the polarization state of the reflected light L2 when the reflected light L2 enters the selective reflection surface 44a of the dichroic mirror 44 is changed so that the excitation light L1 is directed toward the light emitting element. The polarization state of the excitation light L1 when entering the light 44a can be different. For example, if the polarization state of the excitation light L1 when the excitation light L1 is incident on the selective reflection surface 44a is P-polarized light, the polarization of the reflected light L2 when the reflected light L2 is incident on the selective reflection surface 44a of the dichroic mirror 44 The state can be S-polarized light. Thereby, a light source device with high light utilization efficiency can be realized.

  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 capable of ensuring high reliability and reducing the size of the device.

[Third Embodiment]
Hereinafter, a third 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. 6 is a schematic configuration diagram illustrating the projector according to the present embodiment. FIG. 7 is a diagram illustrating characteristics of a dichroic mirror used in the light source device.
In FIG. 6, the same components as those in FIG. 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the projector 46 of the present embodiment, as shown in FIG. 6, the light source device 47 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 so that the optical path of the emitted light L3 intersects the optical path of the excitation light L1 from the laser light source 9, and the incident angle θ3 with respect to the selective reflection surface 48a of the dichroic mirror 48 forms an angle of 60 degrees. Has been. 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. 7, the dichroic mirror 48 of the present embodiment is different in selective reflection characteristics from the dichroic mirror 10 of the first embodiment. Specifically, in this embodiment, the selective reflection characteristic on the short wavelength side is the same as that of the first embodiment, but the selective reflection characteristic on the long wavelength side is different. For light with an incident angle of 60 degrees, the reflectivity 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 48 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 red light emitted from the auxiliary laser light source 43 is The light passes through the selective reflection surface 48a. 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 this embodiment, since the light source device 47 includes the auxiliary laser light source 43 that can be individually controlled, the color and gradation can be selected by appropriately selecting the color and amount of light emitted from the auxiliary laser light source 43. 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 1,41,46 ... Projector, 2,42,47 ... Light source device, 4R, 4G, 4B ... Liquid crystal light valve (light modulation element), 9 ... Laser light source (solid light source), 10, 44, 48 ... Dichroic mirror, DESCRIPTION OF SYMBOLS 11 ... 1/4 wavelength plate (phase difference plate), 12 ... Phosphor wheel (light emitting element), 19 ... Support substrate (support base material), 20 ... Reflective film, 21 ... Light emitting layer, 43 ... Auxiliary laser light source (auxiliary) Solid light source).

Claims (11)

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, and having a selective reflection surface;
With
The support substrate includes a reflective surface that reflects the excitation light and the fluorescence;
An incident angle of the excitation light with respect to the selective reflection surface is smaller than an incident angle of the reflected light of the excitation light with the reflection surface with respect to the selective reflection surface.   2. The light source device according to claim 1, wherein a reflectance of the excitation light reflected by the reflection surface by the selective reflection surface is greater than a reflectance of the excitation light by the selective reflection surface. The excitation light includes a first polarization component in the first wavelength region;
A phase difference plate is provided on at least one of the optical path of the excitation light and the optical path of the reflected light between the light emitting element and the selective reflection surface,
The polarization state of the reflected light when the reflected light is incident on the selective reflection surface is different from the polarization state of the excitation light when the excitation light is incident on the selective reflection surface toward the light emitting element.
The dichroic mirror reflects the fluorescence and has a reflectance for the first polarization component in the first wavelength region lower than a reflectance for the second polarization component in the first wavelength region. The light source device according to claim 1 or 2. The first polarization component is either P-polarized light or S-polarized light with respect to the selective reflection surface, and the second polarization component is the other of the P-polarized light and the S-polarized light,
The phase difference plate is provided on the optical path of the excitation light and the optical path of the reflected light between the light emitting element and the selective reflection surface,
The light source device according to claim 3, wherein the retardation plate is a ¼ wavelength plate for the first wavelength region. The first polarization component is either P-polarized light or S-polarized light with respect to the selective reflection surface, and the second polarization component is the other of the P-polarized light and the S-polarized light,
The phase difference plate is provided only on either the optical path of the excitation light or the optical path of the reflected light between the light emitting element and the selective reflection surface,
The light source device according to claim 3, wherein the retardation plate is a half-wave plate with respect to the first wavelength region.   The light source device according to claim 1, wherein the support base is made of a metal substrate.   The phosphor layer is provided in a first region of a support surface of the support substrate, and the phosphor layer is not provided in a second region of the support surface. Item 7. The light source device according to any one of Items 1 to 6.   8. The second phosphor layer that emits fluorescence including a third wavelength region different from the second wavelength region is provided on the light emitting element. 9. The light source device described.   9. 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. 10.   The light source device according to any one of claims 1 to 9, wherein the support base material is rotatable about a rotation axis that intersects a support surface of the phosphor layer.   A light source device according to any one of claims 1 to 10, 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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