Light source device, illumination device, and projector

Abstract

To provide a light source device capable of suppressing speckles.SOLUTION: The light source apparatus according to the aspect of the invention includes the first light source that outputs the first light, the wavelength converter that converts the first light into the second light, the second light source that outputs the third light, the light guide section that guides the first light, the second light, and the third light, and the controller that controls the light emission state of the second light source. The wavelength conversion element has a first surface, a second surface, and a third surface. The first light enters the wavelength conversion element from the third surface via the light guide section. The second light travels through the light guide portion and is emitted from a region on the first surface side of the light guide portion. The third light includes fourth light in the first polarization state and fifth light in the second polarization state, and is incident on a region of the light guide portion on the second surface side. The second light source includes a first light emitting section that emits the fourth light and a second light emitting section that emits the fifth light. Each of the light emitters includes a laser diode. The controller temporally changes a ratio between a light amount of the fourth light and a light amount of the fifth light.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light source device, an illumination device, and a projector. [Background technology]

[0002] As a light source device for use in a projector, a light source device that utilizes fluorescence emitted from a phosphor when the phosphor is irradiated with excitation light emitted from a light-emitting element has been proposed. Patent Document 1 listed below discloses an illumination device that includes a laser light source that emits excitation light and blue light, a polarization separation element that separates the excitation light from the blue light, a fluorescent light-emitting element that wavelength-converts the excitation light into fluorescent light, and a diffusion element that diffuses the blue light. According to this illumination device, the yellow fluorescence emitted from the fluorescent light-emitting element and the blue light emitted from the diffuse reflection element are combined by the polarization separation element to generate white illumination light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-173391 Summary of the Invention [Problem to be solved by the invention]

[0004] In the illumination device of Patent Document 1, the blue light component of the white illumination light originates from laser light emitted from a laser light source. However, because laser light is coherent light, speckles caused by interference of the laser light may be visible on the screen in projectors equipped with this type of illumination device. This poses a problem of reduced display quality. Although the illumination device of Patent Document 1 is equipped with a fixed diffusion element, it is difficult to suppress speckles simply by diffusing the blue light using this type of diffusion element. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, one embodiment of the light source device of the present invention includes a first light source that emits first light in a first wavelength band, a wavelength conversion element that converts the first light into second light in a second wavelength band different from the first wavelength band, a second light source that emits third light in a third wavelength band, a light guide unit disposed between the first light source and the wavelength conversion element and that guides each of the first light, the second light, and the third light, and a control unit that controls the light emission state of the second light source. The wavelength conversion element has first and second surfaces facing opposite each other and a third surface intersecting the first and second surfaces. The first light emitted from the first light source enters the wavelength conversion element from the third surface via the light guide unit. The second light travels through the light guide unit and is emitted from a region of the light guide unit on the first surface side. The third light includes fourth light in a first polarization state and fifth light in a second polarization state different from the first polarization state, and enters a region of the light guide unit on the second surface side. The second light source has a first light-emitting unit that emits the fourth light and a second light-emitting unit that emits the fifth light. Each of the first light-emitting unit and the second light-emitting unit has a laser diode. The control unit changes over time the ratio between the amount of the fourth light emitted from the first light-emitting unit and the amount of the fifth light emitted from the second light-emitting unit.

[0006] An illumination device according to one aspect of the present invention includes the light source device according to one aspect of the present invention and a polarization conversion element that converts the polarization state of light emitted from the light source device.

[0007] A projector according to one aspect of the present invention comprises a light source device according to one aspect of the present invention, an optical modulation device that modulates light emitted from the light source device, and a projection optical device that projects the light modulated by the optical modulation device. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic configuration diagram of a projector according to a first embodiment. [Figure 2] 3 is a cross-sectional view of the light source device of the first embodiment, showing the emission state of blue light in a first period. FIG. [Figure 3] 4 is a cross-sectional view of the light source device of the first embodiment, showing the emission state of blue light in a second period. FIG. [Figure 4] 4 is a cross-sectional view of the light source device of the first embodiment, showing the emission state of blue light in a third period. FIG. [Figure 5] 3 is a cross-sectional view of the light source device taken along line VV in FIG. 2. [Figure 6] 10A and 10B are diagrams for explaining the function of a polarization conversion element. [Figure 7] FIG. 10 is a cross-sectional view of a light source device according to a second embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a light source device according to a third embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a light source device according to a fourth embodiment. [Figure 10] FIG. 10 is a schematic configuration diagram of a projector according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment of the present invention will be described below with reference to the drawings. The projector of this embodiment is an example of a projector that uses a liquid crystal panel as a light modulation device. In the drawings below, the dimensions of some components may be shown on different scales to make them easier to see.

[0010] FIG. 1 is a schematic configuration diagram of a projector 10 according to the present embodiment. 1, the projector 10 of this embodiment is a projection-type image display device that displays a color image on a screen SCR, which is a projection surface. The projector 10 is equipped with three light modulation devices corresponding to red light LR, green light LG, and blue light LB.

[0011] The projector 10 includes an illumination device 20, a color separation light-guiding optical system 200, a red light optical modulation device 400R, a green light optical modulation device 400G, a blue light optical modulation device 400B, a light combining element 500, and a projection optical device 600.

[0012] The illumination device 20 includes a light source device 30A, an integrator optical system 90, a polarization conversion element 93, and a superimposing optical system 94. The illumination device 20 emits white light LW containing red light LR, green light LG, and blue light LB. The specific configuration of the illumination device 20 will be described later.

[0013] In the following drawings, an XYZ Cartesian coordinate system will be used as necessary. The X axis is an axis parallel to the optical axis AX1 of the lighting device 20 and extends along the front-to-rear direction of the projector 10. The Y axis is an axis perpendicular to the X axis and extends along the up-down direction of the projector 10. The Z axis is an axis perpendicular to the X and Y axes and extends along the left-to-right direction of the projector 10. These notations are used to explain the positional relationship of the components of the projector 10 and do not limit the installation posture or direction of the projector 10. The optical axis AX1 of the lighting device 20 is the central axis of the white light LW emitted from the lighting device 20.

[0014] In the following explanation, one of the two directions along the X axis will be referred to as the +X direction, and the opposite direction will be referred to as the -X direction. One of the two directions along the Y axis will be referred to as the +Y direction, and the opposite direction will be referred to as the -Y direction. One of the two directions along the Z axis will be referred to as the +Z direction, and the opposite direction will be referred to as the -Z direction. When referring to two directions along the X axis collectively without distinction, they will be referred to as the X-axis direction. When referring to two directions along the Y axis collectively without distinction, they will be referred to as the Y-axis direction. When referring to two directions along the Z axis collectively without distinction, they will be referred to as the Z-axis direction.

[0015] The color separation and light-guiding optical system 200 includes a first dichroic mirror 210, a second dichroic mirror 220, a first reflecting mirror 230, a second reflecting mirror 240, a third reflecting mirror 250, a first relay lens 260, and a second relay lens 270. The color separation and light-guiding optical system 200 separates white light LW emitted from the illumination device 20 into red light LR, green light LG, and blue light LB, and guides the red light LR to a red light optical modulation device 400R, the green light LG to a green light optical modulation device 400G, and the blue light LB to a blue light optical modulation device 400B.

[0016] A field lens 300R is disposed between the color separation and light-guiding optical system 200 and the red light optical modulator 400R. A field lens 300G is disposed between the color separation and light-guiding optical system 200 and the green light optical modulator 400G. A field lens 300B is disposed between the color separation and light-guiding optical system 200 and the blue light optical modulator 400B. The field lens 300R collimates the chief ray of the red light LR incident on the red light optical modulator 400R. The field lens 300G collimates the chief ray of the green light LG incident on the green light optical modulator 400G. The field lens 300B collimates the chief ray of the blue light LB incident on the blue light optical modulator 400B.

[0017] The first dichroic mirror 210 transmits the red light LR and reflects the green light LG and blue light LB. The second dichroic mirror 220 reflects the green light LG and transmits the blue light LB. The first reflecting mirror 230 reflects the red light LR. The second reflecting mirror 240 and the third reflecting mirror 250 each reflect the blue light LB.

[0018] The red light optical modulator 400R, the green light optical modulator 400G, and the blue light optical modulator 400B each modulate the color light incident thereon in accordance with image information to generate image light. Each of the red light optical modulator 400R, the green light optical modulator 400G, and the blue light optical modulator 400B is composed of a liquid crystal panel.

[0019] Although not shown in the figure, incident-side polarizing plates are arranged between field lens 300R and red light optical modulator 400R, between field lens 300G and green light optical modulator 400G, and between field lens 300B and blue light optical modulator 400B. In addition, exit-side polarizing plates are arranged between red light optical modulator 400R and light combining element 500, between green light optical modulator 400G and light combining element 500, and between blue light optical modulator 400B and light combining element 500. The incident-side polarizing plate and the exit-side polarizing plate only transmit light linearly polarized in a specific direction.

[0020] The light combining element 500 receives the image lights emitted from the red light optical modulation device 400R, the green light optical modulation device 400G, and the blue light optical modulation device 400B, combines the image lights corresponding to the red light LR, the green light LG, and the blue light LB, and emits the combined image light toward the projection optical device 600. The light combining element 500 may be, for example, a cross dichroic prism.

[0021] The projection optical device 600 is composed of a plurality of projection lenses. The projection optical device 600 enlarges and projects the image light combined by the light combining element 500 onto the screen SCR, thereby displaying an image on the screen SCR.

[0022] The configurations of the light source device 30A and the illumination device 20 will be described below. 2 to 4 are cross-sectional views of light source device 30A of this embodiment. FIG. 2 shows the emission state of blue light B in a first period. FIG. 3 shows the emission state of blue light B in a second period. FIG. 4 shows the emission state of blue light B in a third period. FIG. 5 is a cross-sectional view of light source device 30A taken along line VV in FIG. 2. As will be described in more detail below, the emission state of blue light B changes over time.

[0023] As shown in Figures 2 to 5, the light source device 30A of this embodiment includes a first light source 41, a wavelength conversion element 51, a first light guiding section 71, a second light guiding section 72, a first optical layer 61, a second optical layer 62, a second light source 42, a control section 47, and a reflective layer 65.

[0024] The first light source 41 has a third light source 43 and a fourth light source 44. The third light source 43 and the fourth light source 44 have the same configuration. Each of the third light source 43 and the fourth light source 44 has a plurality of light-emitting elements 411. The plurality of light-emitting elements 411 are mounted on a substrate 412. Note that the number of light-emitting elements 411 included in the first light source 41 is not particularly limited.

[0025] The light emitting element 411 emits excitation light rays in a first wavelength band. The light emitting element 411 is composed of a light emitting diode (LED). By configuring the light emitting element 411 with an LED, it is possible to reduce the cost of the light source device 30A and improve the light emitting efficiency. The light emitting element 411 is arranged opposite the wavelength conversion element 51 and emits excitation light rays toward the wavelength conversion element 51. The first wavelength band is, for example, a wavelength band from purple to blue of 400 nm to 480 nm. The center wavelength of the first wavelength band is, for example, 455 nm. The multiple light emitting elements 411 are arranged along the X-axis direction, which is the longitudinal direction of the wavelength conversion element 51.

[0026] The third light source 43 emits a plurality of excitation light beams toward the wavelength conversion element 51 via the first light guiding section 71. The fourth light source 44 is disposed opposite to the third light source 43 with the wavelength conversion element 51 interposed therebetween. The fourth light source 44 emits a plurality of excitation light beams toward the wavelength conversion element 51 via the second light guiding section 72. In this manner, the first light source 41 causes excitation light E of a first wavelength band including a plurality of excitation light beams to be incident on the wavelength conversion element 51. The excitation light E in this embodiment corresponds to the first light in the claims.

[0027] The wavelength conversion element 51 has a plate-like shape extending along the X-axis and has six faces. The sides of the wavelength conversion element 51 extending along the X-axis are longer than the sides extending along the Y-axis and the Z-axis. The X-axis direction corresponds to the longitudinal direction of the wavelength conversion element 51. The Y-axis direction is a direction parallel to the shortest side of the wavelength conversion element 51. The length of the sides along the Y-axis is shorter than the length of the sides along the Z-axis. That is, the cross-sectional shape of the wavelength conversion element 51 cut along a plane along the YZ plane is rectangular, as shown in FIG. 5.

[0028] The wavelength conversion element 51 has a first end face 51a and a second end face 51b, a first side face 51c and a second side face 51d, a third side face 51e and a fourth side face 51f. The first end face 51a and the second end face 51b face opposite each other in the X-axis direction along the longitudinal direction of the wavelength conversion element 51. In this embodiment, the first end face 51a is located on the +X side, which is one side in the X-axis direction. The second end face 51b is located on the -X side, which is the other side in the X-axis direction. The first end face 51a of this embodiment corresponds to face 1 in the claims. The second end face 51b of this embodiment corresponds to face 2 in the claims.

[0029] The first side surface 51c and the second side surface 51d intersect the first end surface 51a and the second end surface 51b and face opposite each other along the Y axis. In this embodiment, the first side surface 51c is located on the +Y side, which is one side in the Y axis direction. The second side surface 51d is located on the -Y side, which is the other side in the Y axis direction. Excitation light E is incident on the first side surface 51c from the third light source 43 via the first light guiding section 71. Excitation light E is incident on the second side surface 51d from the fourth light source 44 via the second light guiding section 72. The first side surface 51c and the second side surface 51d in this embodiment correspond to the third side of the claims.

[0030] 5, the third side surface 51e and the fourth side surface 51f intersect with the first end surface 51a and the second end surface 51b, and with the first side surface 51c and the second side surface 51d, and face opposite each other in the Z axis direction. The third side surface 51e is located on one side, the +Z side, in the Z axis direction. The fourth side surface 51f is located on the other side, the -Z side, in the Z axis direction.

[0031] The wavelength conversion element 51 contains at least a yellow phosphor and converts the excitation light E in a first wavelength band emitted from the first light source 41 into yellow fluorescence Y in a second wavelength band different from the first wavelength band. As will be described in detail later, a portion of the yellow fluorescence Y generated inside the wavelength conversion element 51 is emitted from the first side surface 51c to the first light guiding section 71, and another portion of the yellow fluorescence Y is emitted from the second side surface 51d to the second light guiding section 72.

[0032] The wavelength conversion element 51 includes a ceramic phosphor made of a polycrystalline phosphor that converts the wavelength of the excitation light E into yellow fluorescence Y. The wavelength conversion element 51 is made of a phosphor with light scattering properties, a so-called scattering phosphor. The second wavelength band of the yellow fluorescence Y is, for example, a yellow wavelength band of 490 to 750 nm. The center wavelength of the second wavelength band is, for example, 550 nm. In other words, the fluorescence Y is yellow fluorescence containing a red light component and a green light component. The yellow fluorescence Y of this embodiment corresponds to the second light in the claims.

[0033] The wavelength conversion element 51 may contain a single crystal phosphor instead of a polycrystalline phosphor. Alternatively, the wavelength conversion element 51 may be made of fluorescent glass. Alternatively, the wavelength conversion element 51 may be made of a material in which a large number of phosphor particles are dispersed in a binder made of glass or resin. A wavelength conversion element 51 made of such a material converts blue excitation light E into yellow fluorescence Y.

[0034] Specifically, the material of the wavelength conversion element 51 includes, for example, an yttrium-aluminum-garnet (YAG) phosphor. Taking YAG:Ce containing cerium (Ce) as an activator as an example, the material of the wavelength conversion element 51 may be a material obtained by mixing raw material powders containing constituent elements such as Y2O3, Al2O3, and CeO3 and causing a solid-phase reaction, Y-Al-O amorphous particles obtained by a wet method such as a coprecipitation method or a sol-gel method, or YAG particles obtained by a gas-phase method such as a spray-drying method, a flame pyrolysis method, or a thermal plasma method.

[0035] The first optical layer 61 is disposed between the first light source 41 and the wavelength conversion element 51. That is, the first optical layer 61 is disposed between the third light source 43 and the wavelength conversion element 51, and between the fourth light source 44 and the wavelength conversion element 51. The first optical layer 61 has optical properties of transmitting the excitation light E and reflecting the yellow fluorescence Y. The first optical layer 61 is formed of, for example, a dielectric multilayer film. The first optical layer 61 is disposed on a second side surface 73d of a translucent member 73, which will be described later, facing the first light source 41.

[0036] The first light guiding section 71 and the second light guiding section 72 are disposed between the first optical layer 61 and the wavelength conversion element 51. That is, the first light guiding section 71 is disposed between the first optical layer 61 facing the third light source 43 and the first side surface 51c of the wavelength conversion element 51. The second light guiding section 72 is disposed between the first optical layer 61 facing the fourth light source 44 and the second side surface 51d of the wavelength conversion element 51. The first light guiding section 71 and the second light guiding section 72 have the same configuration.

[0037] The first light guiding section 71 and the second light guiding section 72 each guide the excitation light E emitted from the first light source 41, the yellow fluorescence Y converted by the wavelength conversion element 51, and the blue light B emitted from the second light source 42. In this embodiment, the first light guiding section 71 and the second light guiding section 72 each include a light-transmitting member 73 that transmits the excitation light E, the yellow fluorescence Y, and the blue light B. The light-transmitting member 73 is a plate-shaped member, and is bonded to the first side surface 51 c and the second side surface 51 d of the wavelength conversion element 51 with an optical adhesive (not shown). The first light guiding section 71 and the second light guiding section 72 in this embodiment correspond to the light guiding section in the claims.

[0038] The light-transmitting member 73 is made of a light-transmitting material such as borosilicate glass (e.g., BK7), quartz, synthetic quartz, crystal, SiC, GaN, MgO, YAG, sapphire, or diamond. As described above, the light-transmitting member 73 must be made of a material that can transmit the excitation light E, yellow fluorescence Y, and blue light B. The light-transmitting member 73 has a plate-like shape extending along the X-axis. As shown in FIG. 3, the light-transmitting member 73 has a rectangular cross-section cut along the YZ plane and extends elongatedly in the X-axis direction. As shown in FIG. 2, of the two end faces of the light-transmitting member 73 that intersect with the X-axis, the end face on the side of the first end face 51a of the wavelength conversion element 51 is referred to as the first end face 73a, and the end face on the side of the second end face 51b of the wavelength conversion element 51 is referred to as the second end face 73b. Of the side surfaces of the light-transmitting member 73, the side surfaces in contact with the first side surface 51c and the second side surface 51d of the wavelength conversion element 51 are referred to as first side surfaces 73c, and the side surface opposite to the first side surface 73c is referred to as second side surface 73d. Note that the light-transmitting member 73 may have a shape other than a plate shape (rectangular parallelepiped).

[0039] It is desirable that the thermal conductivity of the light-transmitting member 73 be greater than that of the wavelength conversion element 51. Materials for the light-transmitting member 73 that satisfy this relationship include, for example, SiC, GaN, MgO, YAG, sapphire, and diamond. With this configuration, heat from the wavelength conversion element 51 is efficiently transferred to the light-transmitting member 73, thereby suppressing a temperature rise in the wavelength conversion element 51. This makes it possible to suppress a decrease in conversion efficiency due to a temperature rise in the wavelength conversion element 51.

[0040] The second light source 42 includes a light emitting element array 96 , a half wavelength plate 97 , a collimating optical system 98 , a light combining element 95 , and a light beam width reducing optical system 99 .

[0041] The light-emitting element array 96 has a first light-emitting element 961, a second light-emitting element 962, a third light-emitting element 963, and a fourth light-emitting element 964. The four light-emitting elements are arranged in a row along the Y-axis direction, and are arranged in the order of the first light-emitting element 961, the second light-emitting element 962, the third light-emitting element 963, and the fourth light-emitting element 964 from the -Y side to the +Y side. The number of light-emitting elements included in the light-emitting element array 96 is four in this embodiment, but is not particularly limited.

[0042] The light-emitting elements 961, 962, 963, and 964 emit blue light beams Bs1, Bs2, Bs3, and Bs4 in the third wavelength band toward the light-transmitting member 73. Each of the light-emitting elements 961, 962, 963, and 964 is composed of a chip-shaped laser diode (LD) that emits blue light beams. By configuring each of the light-emitting elements 961, 962, 963, and 964 as an LD, which is a point light source, collimated light can be obtained using a collimating optical system 98. The third wavelength band is, for example, a blue wavelength band of 440 nm to 450 nm. Each of the blue light beams Bs1, Bs2, Bs3, and Bs4 is S-polarized light. Note that the terms S-polarized light and P-polarized light hereinafter refer to the polarization direction relative to a polarization separation mirror 951 of the light combining element 95, which will be described later.

[0043] Each light-emitting element 961, 962, 963, and 964 is arranged so that the light-emitting surface of the laser diode chip faces the +X side, the long side of the rectangular light-emitting surface faces the Y-axis direction, and the short side of the light-emitting surface faces the Z-axis direction. The central axis of each blue light beam Bs1, Bs2, Bs3, and Bs4 emitted from each light-emitting element 961, 962, 963, and 964 is parallel to the X-axis. The divergence angles of each blue light beam Bs1, Bs2, Bs3, and Bs4 differ in the Y-axis and Z-axis directions, with the divergence angle in the Z-axis direction being significantly larger than the divergence angle in the Y-axis direction. Therefore, as shown in Figure 5, the cross-sectional shape of each blue light beam Bs1 and Bs2 perpendicular to the central axis is an elongated ellipse, with the major axis of the ellipse facing the Z-axis direction and the minor axis of the ellipse facing the Y-axis direction.

[0044] The half-wave plate 97 is disposed on the light-emitting side of the first light-emitting element 961 and the second light-emitting element 962. The half-wave plate 97 imparts a phase difference of approximately half the wavelength of the blue light beams Bs1 and Bs2. Therefore, the S-polarized blue light beam Bs1 emitted from the first light-emitting element 961 passes through the half-wave plate 97 and is converted into a P-polarized blue light beam Bp1, which then enters the collimating optical system 98. The S-polarized blue light beam Bs2 emitted from the second light-emitting element 962 passes through the half-wave plate 97 and is converted into a P-polarized blue light beam Bp2, which then enters the collimating optical system 98. On the other hand, the half-wave plate 97 is not disposed on the light-emitting side of the third light-emitting element 963 and the fourth light-emitting element 964. Therefore, the S-polarized blue light beams Bs3 and Bs4 emitted from the third light-emitting element 963 and the fourth light-emitting element 964 enter the collimating optical system 98 while remaining S-polarized.

[0045] In the following description, the first light-emitting element 961, the second light-emitting element 962, and the half-wave plate 97 are collectively defined as the first light-emitting unit 42A. The third light-emitting element 963 and the fourth light-emitting element 964 are collectively defined as the second light-emitting unit 42B. Therefore, the first light-emitting unit 42A emits blue light Bp consisting of P-polarized blue light beams Bp1 and Bp2. The second light-emitting unit 42B emits blue light Bs consisting of S-polarized blue light beams Bs3 and Bs4. That is, the second light source 42 includes the first light-emitting unit 42A that emits P-polarized blue light Bp and the second light-emitting unit 42B that emits S-polarized blue light Bs. The blue light B emitted from the second light source 42 includes at least one of P-polarized blue light Bp and S-polarized blue light Bs. The blue light B in this embodiment corresponds to the third light in the claims. The P-polarized blue light Bp of this embodiment corresponds to the fourth light of the first polarization state in the claims, and the S-polarized blue light Bs of this embodiment corresponds to the fifth light of the second polarization state in the claims.

[0046] The collimating optical system 98 is disposed on the light-emitting element array 96's light-emitting side. The collimating optical system 98 includes a first collimating element 981, a second collimating element 982, a third collimating element 983, and a fourth collimating element 984. Each of the collimating elements 981, 982, 983, and 984 is formed of a collimator lens. The first collimating element 981 is disposed on the light-emitting side of the first light-emitting element 961 and collimates the blue light beam Bp1 emitted from the first light-emitting element 961. The second collimating element 982 is disposed on the light-emitting side of the second light-emitting element 962 and collimates the blue light beam Bp2 emitted from the second light-emitting element 962. The third collimating element 983 is disposed on the light-emitting side of the third light-emitting element 963 and collimates the blue light beam Bs2 emitted from the third light-emitting element 963. The fourth collimating element 984 is disposed on the light emission side of the fourth light emitting element 964, and collimates the blue light beam Bs2 emitted from the fourth light emitting element 964.

[0047] The light combining element 95 is disposed on the light exit side of the collimating optical system 98. The light combining element 95 has a polarization separation mirror 951 and a reflecting mirror 952. The polarization separation mirror 951 is disposed on the optical path of the P-polarized blue light Bp emitted from the first light-emitting unit 42A and transmits the P-polarized light and reflects the S-polarized light. The reflecting mirror 952 is disposed on the optical path of the S-polarized blue light Bs emitted from the second light-emitting unit 42B and reflects the S-polarized blue light Bs. Therefore, the P-polarized blue light Bp emitted from the first light-emitting unit 42A passes through the polarization separation mirror 951 and travels toward the +X side. The S-polarized blue light Bs emitted from the second light-emitting unit 42B is reflected by the reflecting mirror 952 and travels toward the -Y side, and then reflected by the polarization separation mirror 951 and travels toward the +X side. In this way, light combining element 95 combines P-polarized blue light Bp emitted from first light-emitting unit 42A and S-polarized blue light Bs emitted from second light-emitting unit 42B. With this configuration, light combining element 95 combines P-polarized blue light Bp and S-polarized blue light Bs, so that blue light B, which is a mixture of light with different polarization states, can be efficiently incident on second end surface 73b of light-transmitting member 73.

[0048] The light beam width reduction optical system 99 is disposed on the light emission side of the light combining element 95. The light beam width reduction optical system 99 has a first reflecting mirror 991 and a second reflecting mirror 992. The first reflecting mirror 991 is disposed on the optical path of the blue light ray Bp2 emitted from the second light-emitting element 962. The second reflecting mirror 992 is disposed on the -Y side of the first reflecting mirror 991. Therefore, the blue light ray Bp2 emitted from the second light-emitting element 962 passes through the polarization separation mirror 951, is reflected by the first reflecting mirror 991, and then by the second reflecting mirror 992, before traveling toward the +X side. In addition, the blue light ray Bs4 emitted from the fourth light-emitting element 964 is reflected by the reflecting mirror 952, is reflected by the polarization separation mirror 951, is reflected by the first reflecting mirror 991, and then is reflected by the second reflecting mirror 992, before traveling toward the +X side. In this way, the light beam width reduction optical system 99 reduces the light beam width of blue light B including blue light rays Bp1, Bp2, Bs3, and Bs4 emitted from the four light emitting elements 961, 962, 963, and 964. Note that the light beam width reduction optical system 99 does not necessarily have to be provided.

[0049] The control unit 47 controls the light-emitting state of the second light source 42. Specifically, the control unit 47 adjusts the power supplied to each of the light-emitting elements 961, 962, 963, and 964 constituting the second light source 42, and controls the on / off and light intensity of the blue light beams Bp1, Bp2, Bs3, and Bs4 emitted from each of the light-emitting elements 961, 962, 963, and 964. In this way, the control unit 47 changes over time the ratio between the intensity of the P-polarized blue light Bp emitted from the first light-emitting unit 42A and the intensity of the S-polarized blue light Bs emitted from the second light-emitting unit 42B. Specific examples of patterns for changing the ratio will be described later. The control unit 47 has a CPU.

[0050] The second optical layer 62 is disposed on the −X side of the wavelength conversion element 51, the first light guiding section 71, and the second light guiding section 72. Specifically, the second optical layer 62 is disposed opposite the second end surface 51b of the wavelength conversion element 51 and the second end surface 73b of the light-transmitting member 73. The second optical layer 62 is composed of a dielectric multilayer film that transmits blue light and reflects yellow light. Therefore, the blue light B emitted from the second light source 42 transmits through the second optical layer 62 and enters the first light guiding section 71 and the second light guiding section 72. The yellow fluorescence Y converted by the wavelength conversion element 51 propagates through the first light guiding section 71 and the second light guiding section 72 toward the −X side, and upon entering the second optical layer 62, is reflected by the second optical layer 62 and propagates through the first light guiding section 71 and the second light guiding section 72 toward the +X side.

[0051] As shown in FIG. 5 , the reflective layer 65 is disposed on both sides of the first light guiding section 71, the second light guiding section 72, and the wavelength conversion element 51 in the Z-axis direction. The reflective layer 65 reflects the excitation light E, the yellow fluorescence Y, and the blue light B. Therefore, the reflective layer 65 does not directly enter the wavelength conversion element 51, but reflects the excitation light E that enters the reflective layer 65 and makes it enter the wavelength conversion element 51. This improves the conversion efficiency of the excitation light E to the yellow fluorescence Y. The reflective layer 65 reflects the yellow fluorescence Y and the blue light B that propagate through the first light guiding section 71 and the second light guiding section 72. This reduces the loss of the yellow fluorescence Y and the blue light B. The reflective layer 65 is formed of, for example, a metal film, a dielectric multilayer film, a scattering layer, or the like.

[0052] 1, an integrator optical system 90 is provided on the light emission side of the light source device 30A. The integrator optical system 90 has a first lens array 91 and a second lens array 92. The integrator optical system 90, together with a superimposing optical system 94, functions as a uniform illumination optical system that uniformizes the intensity distribution of the white light LW emitted from the light source device 30A in each of the light modulation devices 400R, 400G, and 400B, which are the illuminated areas. The white light LW emitted from the light source device 30A is incident on the first lens array 91.

[0053] The first lens array 91 has a plurality of first lenses 91a. The plurality of first lenses 91a are arranged in a matrix in a plane parallel to the YZ plane orthogonal to the optical axis AX1 of the illumination device 20. The plurality of first lenses 91a split the white light LW emitted from the light source device 30A into a plurality of partial light beams. The shape of each of the first lenses 91a is rectangular, which is approximately similar to the shape of the image formation areas of the light modulation devices 400R, 400G, and 400B. This allows each of the partial light beams emitted from the first lens array 91 to efficiently enter the image formation areas of the light modulation devices 400R, 400G, and 400B.

[0054] The white light LW emitted from the first lens array 91 travels toward the second lens array 92. The second lens array 92 is disposed opposite the first lens array 91. The second lens array 92 has a plurality of second lenses 92a corresponding to the plurality of first lenses 91a of the first lens array 91. The second lens array 92, together with the superimposing optical system 94, forms each of the images of the plurality of first lenses 91a of the first lens array 91 near the image forming areas of the light modulation devices 400R, 400G, and 400B. The plurality of second lenses 92a are arranged in a matrix in a plane parallel to the YZ plane that is perpendicular to the optical axis AX1 of the illumination device 20. The superimposing optical system 94 is composed of a single convex lens.

[0055] In this embodiment, the first lenses 91a of the first lens array 91 and the second lenses 92a of the second lens array 92 have the same size, but may have different sizes. Also, in this embodiment, the first lenses 91a of the first lens array 91 and the second lenses 92a of the second lens array 92 are arranged so that their optical axes coincide with each other, but they may be arranged eccentrically with each other.

[0056] FIG. 6 is a diagram for explaining the function of the polarization conversion element 93. In FIG. The polarization conversion element 93 converts the polarization direction of the white light LW emitted from the second lens array 92. Specifically, the polarization conversion element 93 converts each partial beam of the white light LW split by the first lens array 91 shown in FIG. 1 and emitted from the second lens array 92 into linearly polarized light. As shown in FIG. 6, the polarization conversion element 93 has a polarization separation layer 931, a reflective layer 932, and a retardation layer 933. The polarization separation layer 931 transmits P-polarized white light LWp, which is one of the polarization components contained in the white light LW emitted from the light source device 30A, as is, and reflects S-polarized white light LWs in a direction perpendicular to the optical axis AX1 shown in FIG. 1 (Z-axis direction). The reflective layer 932 reflects the S-polarized white light LWs reflected by the polarization separation layer 931 in a direction parallel to the optical axis AX1 (X-axis direction). The retardation layer 933 is made of a half-wave plate, and converts the P-polarized white light LWp transmitted through the polarization separation layer 931 into S-polarized white light LWs.

[0057] The operation of the light source device 30A of this embodiment will be described below. As shown in FIGS. 2 to 4, in the light source device 30A, the excitation light E emitted from the first light source 41 passes through the first optical layer 61 and the light-transmitting member 73 and enters the wavelength conversion element 51.

[0058] When excitation light E is incident on the wavelength conversion element 51, the phosphor contained in the wavelength conversion element 51 is excited, and yellow fluorescence Y is emitted from any light-emitting point. At this time, the excitation light E incident on the phosphor is diffused and propagates over an area wider than the incident area, thereby expanding the width of the emission area of ​​the yellow fluorescence Y, resulting in so-called bleeding of the yellow fluorescence Y.

[0059] The yellow fluorescence Y that is incident from the light-emitting point of the wavelength conversion element 51 onto the first side surface 51c and the second side surface 51d at an incident angle less than the critical angle is emitted from the wavelength conversion element 51, enters the light-transmitting member 73, and propagates inside the light-transmitting member 73. At this time, the fluorescence Y traveling toward the +X side is reflected by the first optical layer 61 and re-enters the wavelength conversion element 51. In the present embodiment, since the wavelength conversion element 51 is made of a scattering phosphor, the yellow fluorescence Y is scattered inside the wavelength conversion element 51, is emitted again from the wavelength conversion element 51 to the light-transmitting member 73, propagates through the light-transmitting member 73, and then emitted to the outside from the first end surface 73a of the light-transmitting member 73.

[0060] Yellow fluorescence generated inside the wavelength conversion element 51 and incident on the first side surface 51c and the second side surface 51d of the wavelength conversion element 51 at an incident angle equal to or greater than the critical angle is once totally reflected by the first side surface 51c and the second side surface 51d of the wavelength conversion element 51. However, in the present embodiment, because the wavelength conversion element 51 is made of a scattering phosphor, the traveling direction of the yellow fluorescence Y2 changes inside the wavelength conversion element 51, and the incident angle of the yellow fluorescence Y with respect to the first side surface 51c and the second side surface 51d of the wavelength conversion element 51 changes. As a result, the yellow fluorescence Y is emitted from the wavelength conversion element 51 to the light-transmitting member 73, propagates through the light-transmitting member 73, and then emitted to the outside from the first end surface 73a of the light-transmitting member 73.

[0061] On the other hand, the yellow fluorescence Y that travels through the light-transmitting member 73 toward the -X side and reaches the second optical layer 62 is reflected by the second optical layer 62, travels toward the +X side, and follows the same path as the above-mentioned yellow fluorescence Y. That is, the yellow fluorescence Y propagates inside the light-transmitting member 73 or the wavelength conversion element 51 while repeatedly reflecting between the first optical layer 61 and the first side surface 51c or the second side surface 51d of the wavelength conversion element 51, and is emitted to the outside from the first end surface 73a of the light-transmitting member 73 or the first end surface 51a of the wavelength conversion element 51.

[0062] In contrast, as described above, with regard to the blue light B emitted from the second light source 42, the amount of blue light emitted from each light-emitting element 961, 962, 963, and 964 is controlled by the control unit 47, and the ratio between the amount of P-polarized blue light Bp emitted from the first light-emitting unit 42A and the amount of S-polarized blue light Bs emitted from the second light-emitting unit 42B changes over time.

[0063] An example of the pattern of change over time in the ratio of the amount of P-polarized blue light Bp to the amount of S-polarized blue light Bs will be described below. In this example, during the first period, the light intensity of the blue light Bp:the light intensity of the blue light Bs is set to 100%:0%. At this time, as shown in Fig. 2, the first light-emitting element 961 and the second light-emitting element 962 are turned on, and the third light-emitting element 963 and the fourth light-emitting element 964 are turned off. Therefore, only P-polarized blue light Bp, which includes a blue light ray Bp1 emitted from the first light-emitting element 961 and a blue light ray Bp2 emitted from the second light-emitting element 962, is incident on the second end surface 73b of the light-transmitting member 73.

[0064] Next, in the second period, the light intensity of the blue light Bp:the light intensity of the blue light Bs is set to 50%:50%. At this time, as shown in Fig. 3, the first light-emitting element 961, the second light-emitting element 962, the third light-emitting element 963, and the fourth light-emitting element 964 are all turned on. Therefore, both the P-polarized blue light Bp including the blue light ray Bp1 emitted from the first light-emitting element 961 and the blue light ray Bp2 emitted from the second light-emitting element 962 and the S-polarized blue light Bs including the blue light ray Bs3 emitted from the third light-emitting element 963 and the blue light ray Bs4 emitted from the fourth light-emitting element 964 are incident on the second end surface 73b of the light-transmitting member 73.

[0065] Next, in the third period, the light intensity of the blue light Bp:the light intensity of the blue light Bs is set to 0%:100%. At this time, as shown in Fig. 4, the third light-emitting element 963 and the fourth light-emitting element 964 are turned on, and the first light-emitting element 961 and the second light-emitting element 962 are turned off. Therefore, only S-polarized blue light Bs, which includes a blue light ray Bs3 emitted from the third light-emitting element 963 and a blue light ray Bs4 emitted from the fourth light-emitting element 964, is incident on the second end surface 73b of the light-transmitting member 73.

[0066] The three periods may be repeated in one direction, for example, as follows: first period → second period → third period → first period → second period → third period → .... Alternatively, they may be repeated back and forth, for example, as follows: first period → second period → third period → second period → first period → second period → third period → .... When the three periods are repeated periodically in this manner, the repetition frequency of the three periods is preferably 60 Hz or higher. That is, the total time of the three periods is preferably 1 / 60 seconds or less. This configuration can suppress flicker in the projected image on the screen. Note that instead of the three periods being repeated periodically, the ratio between the amount of P-polarized blue light Bp and the amount of S-polarized blue light Bs may be varied so that the three periods occur randomly. Furthermore, the ratio between the amount of P-polarized blue light Bp and the amount of S-polarized blue light Bs may be varied continuously rather than discretely.

[0067] Furthermore, it is desirable that the amount of P-polarized blue light Bp in the first period, the sum of the amounts of P-polarized blue light Bp and S-polarized blue light Bs in the second period, and the amount of S-polarized blue light Bs in the third period are all equal. That is, it is desirable that the sum of the amounts of P-polarized blue light Bp and S-polarized blue light Bs be all equal throughout all periods. With this configuration, the amount of blue light B emitted from light source device 30A remains constant throughout all periods, thereby suppressing flicker in the projected image on the screen.

[0068] Throughout the entire period, the blue light B incident on the second end surface 73b of the light-transmitting member 73 may propagate through the first light guiding unit 71 and the second light guiding unit 72 without entering the wavelength conversion element 51 and may be emitted as blue light B from the first end surface 73a of the light-transmitting member 73. Alternatively, part of the blue light B incident on the second end surface 73b of the light-transmitting member 73 may be incident on the wavelength conversion element 51, converted to yellow fluorescence Y, and propagated through the light guiding units 71 and 72, while the other part of the blue light B may propagate as blue light B through the light guiding units 71 and 72 without being converted to yellow fluorescence Y and be emitted as white light LW from the first end surface 73a of the light-transmitting member 73. The blue light B incident on the second end surface 73b of the light-transmitting member 73 may be parallel light, converging light, or diverging light.

[0069] In this way, the light source device 30A can emit to the outside white light LW that is a combination of the yellow fluorescence Y emitted from the first end face 51a of the wavelength conversion element 51 and the first end face 73a of the light-transmitting member 73 and the blue light B emitted from the first end face 73a of the light-transmitting member 73. This makes it possible for the light source device 30A to reduce the etendue of the white light LW, thereby reducing loss of the white light LW in optical members such as the integrator optical system 90 that are arranged downstream of the light source device 30A. As a result, the utilization efficiency of the white light LW in the light source device 30A can be improved.

[0070] (Effects of the first embodiment) The light source device 30A of this embodiment includes a first light source 41 that emits excitation light E, a wavelength conversion element 51 that converts the excitation light E into yellow fluorescence Y, a second light source 42 that emits blue light B, a first light guiding section 71 and a second light guiding section 72 that are disposed between the first light source 41 and the wavelength conversion element 51 and guide the excitation light E, the yellow fluorescence Y, and the blue light B, respectively, and a control unit 47 that controls the light emission state of the second light source 42. The wavelength conversion element 51 has a first end face 51a and a second end face 51b facing opposite each other, and a first side face 51c and a second side face 51d that intersect with the first end face 51a and the second end face 51b. The excitation light E emitted from the first light source 41 passes through the first light guiding section 71 and the second light guiding section 72 and enters the wavelength conversion element 51 from the first side face 51c and the second side face 51d. Yellow fluorescence Y travels through each light-guiding unit 71, 72 and is emitted from first end surface 73a. Blue light B includes P-polarized blue light Bp and S-polarized blue light Bs, and is incident on second end surface 73b of each light-guiding unit 71, 72. Second light source 42 has first light-emitting unit 42A that emits P-polarized blue light Bp and second light-emitting unit 42B that emits S-polarized blue light Bs. First light-emitting unit 42A and second light-emitting unit 42B each have a laser diode. Controller 47 temporally changes the ratio between the amount of P-polarized blue light Bp emitted from first light-emitting unit 42A and the amount of S-polarized blue light Bs emitted from second light-emitting unit 42B.

[0071] The illumination device 20 of this embodiment includes a light source device 30A and a polarization conversion element 93 that converts the polarization state of white light LW emitted from the light source device 30A.

[0072] In projectors equipped with laser light, the interference of the laser light inevitably causes speckles in the projected image on the screen. For example, the lighting device disclosed in Patent Document 1 uses a fixed diffuse reflection element to diffuse blue light. While this method broadens the light distribution of the blue light, it is difficult to sufficiently suppress speckles. One method for suppressing speckles is to rapidly change the speckle pattern on the screen. In this case, a rotating diffuser plate can be used to diffuse the laser light. However, this method has drawbacks, such as an increase in the size of the lighting device due to the presence of the rotating diffuser plate, and noise and vibrations.

[0073] To address this issue, light source device 30A of the present embodiment rapidly switches the polarization state of blue light B emitted from second light source 42 over time, such as during a first period when 100% P-polarized blue light Bp is emitted, during a second period when 50% P-polarized blue light Bp and 50% S-polarized blue light Bs are emitted, and during a third period when 100% S-polarized blue light Bs is emitted. The temporal changes in the polarization state of blue light B cause the speckle pattern to change rapidly over time, making speckles less visible to the observer. In this way, speckles are suppressed, enabling a projector 10 with excellent display quality to be realized. Furthermore, because there is no need to add components such as a rotating diffuser, there are no problems associated with countermeasures against speckles, such as an increase in the size of the lighting device or the generation of noise or vibration.

[0074] 6, the emission position of white light LWs from polarization conversion element 93 changes corresponding to a period in which only P-polarized blue light Bp is emitted, a period in which both P-polarized blue light Bp and S-polarized blue light Bs are emitted, and a period in which only S-polarized blue light Bs is emitted. This causes the spatial distribution of white light LWs in the optical system downstream of polarization conversion element 93 to change over time. In this way, the speckle pattern also changes over time due to the temporal change in the spatial distribution of white light LWs, making it possible to more effectively suppress speckles.

[0075] The four light-emitting elements 961, 962, 963, and 964 may all have the same central wavelength, or the central wavelength of some of the light-emitting elements may differ from the central wavelength of the other light-emitting elements. For example, the average wavelength of the central wavelength of the first light-emitting element 961 and the central wavelength of the second light-emitting element 962 constituting the first light-emitting unit 42A may differ from the average wavelength of the central wavelength of the third light-emitting element 963 and the fourth light-emitting element 964 constituting the second light-emitting unit 42B, and the difference between the two average wavelengths may be 2 nm or more. With this configuration, the central wavelengths of the blue light Bp and Bs corresponding to each period change by 2 nm or more, thereby changing the speckle pattern over time and more effectively suppressing speckles. The inventors have confirmed that speckle is suppressed by changing the speckle pattern when the wavelengths of the blue light differ by 2 nm or more. In this embodiment, the average wavelength of the central wavelength of the first light-emitting element 961 and the central wavelength of the second light-emitting element 962 corresponds to the first central wavelength in the claims. The average wavelength of the central wavelength of the third light emitting element 963 and the central wavelength of the fourth light emitting element 964 in this embodiment corresponds to the second central wavelength in the claims.

[0076] Furthermore, the central wavelengths of the first light-emitting element 961 and the second light-emitting element 962 may be the same or different. When the central wavelengths of the first light-emitting element 961 and the second light-emitting element 962 are different, the difference between the central wavelengths of the first light-emitting element 961 and the second light-emitting element 962 is preferably 2 nm or more. With this configuration, the P-polarized blue light Bp emitted from the first light-emitting unit 42A contains two blue light beams Bp1 and Bp2 whose central wavelengths are 2 nm or more apart. This reduces the coherence of the blue light Bp even within a single period, thereby more effectively suppressing speckle. The central wavelength of the first light-emitting element 961 in this embodiment corresponds to the third central wavelength in the claims. The central wavelength of the second light-emitting element 962 in this embodiment corresponds to the fourth central wavelength in the claims.

[0077] Similarly, the central wavelengths of the third light-emitting element 963 and the fourth light-emitting element 964 may be the same or different. When the central wavelengths of the third light-emitting element 963 and the fourth light-emitting element 964 are different, the difference between the central wavelengths of the third light-emitting element 963 and the fourth light-emitting element 964 is preferably 2 nm or more. With this configuration, the S-polarized blue light Bs emitted from the second light-emitting unit 42B contains two blue light beams Bs3 and Bs4 whose central wavelengths are 2 nm or more apart. This reduces the coherence of the blue light Bs even within a single period, thereby more effectively suppressing speckle. The central wavelength of the third light-emitting element 963 in this embodiment corresponds to the fifth central wavelength in the claims. The central wavelength of the fourth light-emitting element 964 in this embodiment corresponds to the sixth central wavelength in the claims.

[0078] In view of the above, as an example, the central wavelength of the first light-emitting element 961 may be 443 nm, the central wavelength of the second light-emitting element 962 may be 445 nm, the central wavelength of the third light-emitting element 963 may be 445 nm, and the central wavelength of the fourth light-emitting element 964 may be 447 nm. In this case, the following conditions are satisfied: the difference between the central wavelength of the first light-emitting element 961 and the central wavelength of the second light-emitting element 962 is 2 nm or more; the difference between the central wavelength of the third light-emitting element 963 and the central wavelength of the fourth light-emitting element 964 is 2 nm or more; and the difference between the average wavelength of the first light-emitting portion 42A and the average wavelength of the second light-emitting portion 42B is 2 nm or more.

[0079] In the light source device 30A of this embodiment, the wavelength conversion element 51 has a first side surface 51c and a second side surface 51d facing opposite to each other, the light guiding section has a first light guiding section 71 arranged opposite to the first side surface 51c and a second light guiding section 72 arranged opposite to the second side surface 51d, and the first light source 41 has a third light source 43 that causes excitation light E to be incident on the wavelength conversion element 51 via the first light guiding section 71, and a fourth light source 44 that causes excitation light E to be incident on the wavelength conversion element 51 via the second light guiding section 72.

[0080] According to this configuration, the first side surface 51c and the second side surface 51d of the wavelength conversion element 51 are in contact with the light-transmitting member 73, so that heat from the wavelength conversion element 51 is efficiently transferred to the light-transmitting member 73, and a temperature rise in the wavelength conversion element 51 is suppressed. This makes it possible to suppress a decrease in wavelength conversion efficiency that accompanies a temperature rise in the wavelength conversion element 51. Furthermore, because the excitation light E emitted from each of the third light source 43 and the fourth light source 44 is incident on the wavelength conversion element 51 from the two side surfaces 51c, 51d, it is possible to ensure the amount of excitation light E and the amount of yellow fluorescence Y.

[0081] The projector 10 of this embodiment includes a light source device 30A, light modulation devices 400R, 400G, and 400B that modulate the light emitted from the light source device 30A, and a projection optical device 600 that projects the light modulated by the light modulation devices 400R, 400G, and 400B. With this configuration, since the light source device 30A emits white light LW, there is no need to prepare a light source device that emits blue light separately from a light source device that emits yellow fluorescent light, and a projector 10 can be realized that has a highly efficient and simple configuration and excellent display quality.

[0082] [Second embodiment] A second embodiment of the present invention will be described below with reference to FIG. The basic configuration of the light source device of the second embodiment is the same as that of the first embodiment, but the configuration of the light guide section is different from that of the first embodiment, so a description of the basic configuration of the light source device will be omitted. 7 is a cross-sectional view of a light source device 30B of the fifth embodiment cut along the XY plane. In Fig. 7, components common to those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0083] As shown in FIG. 7, the light source device 30B of this embodiment includes a first light source 41, a wavelength conversion element 51, a first light guiding section 75, a second light guiding section 76, a first optical layer 61, a second optical layer 62, a second light source 42, a control section 47, and a reflective layer (not shown).

[0084] In the light source device 30A of the first embodiment, the first light guiding section 71 and the second light guiding section 72 are formed of a light-transmitting member 73. In contrast, in the light source device 30B of the present embodiment, the first light guiding section 75 and the second light guiding section 76 are formed of an air layer 77. That is, the first optical layer 61 and the wavelength conversion element 51 are disposed apart from each other, and air exists between the first optical layer 61 and the wavelength conversion element 51. Therefore, the yellow fluorescence Y converted by the wavelength conversion element 51 and the blue light B emitted from the second light source 42 are emitted from the region of the air layer 77 on the first end surface 51 a side. The other configurations of the light source device 30B are similar to those of the light source device 30A of the first embodiment.

[0085] (Effects of the second embodiment) In this embodiment, the speckle pattern also changes over time as the polarization state of blue light B changes over time, so that the same effect as in the first embodiment can be obtained, that is, speckles can be sufficiently suppressed.

[0086] In this embodiment, the first light guiding section 75 and the second light guiding section 76 are formed with an air layer 77. This increases the difference in refractive index between the wavelength conversion element 51 and each light guiding section 75, 76 compared to when the first light guiding section and the second light guiding section are formed with a translucent material such as quartz. Therefore, the refraction angle of the fluorescence Y when it is emitted from the wavelength conversion element 51 to each light guiding section 75, 76 increases, and the fluorescence Y travels in a direction that forms a small angle with respect to the first side surface 51c and the second side surface 51d of the wavelength conversion element 51, i.e., a small angle with respect to the X-axis. Furthermore, because the regions of the first end surfaces 51a of each light guiding section 75, 76 are open to the external space and do not have a refractive index interface, the fluorescence Y that reaches the regions of the first end surfaces 51a of each light guiding section 75, 76 is emitted directly into the external space without reflection or refraction. As a result, the light source device 30B of this embodiment can improve the extraction efficiency of yellow fluorescence Y compared to the first embodiment.

[0087] [Third embodiment] A third embodiment of the present invention will be described below with reference to FIG. The basic configuration of the light source device of the third embodiment is the same as that of the first embodiment, but the arrangement of the wavelength conversion element and the light guide section is different from that of the first embodiment, so a description of the basic configuration of the light source device will be omitted. 8 is a cross-sectional view of a light source device 30C of the third embodiment cut along the XY plane. In Fig. 8, components common to those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0088] As shown in FIG. 8, the light source device 30C of this embodiment includes a first light source 41, a first wavelength conversion element 511, a second wavelength conversion element 512, a light guide section 70, a first optical layer 61, a second optical layer 62, a second light source 42, a control section 47, and a reflective layer (not shown).

[0089] The light source device 30C of this embodiment includes two wavelength conversion elements: a first wavelength conversion element 511 and a second wavelength conversion element 512. The first wavelength conversion element 511 and the second wavelength conversion element 512 have the same configuration and are arranged spaced apart from each other in the Y-axis direction. The first wavelength conversion element 511 and the second wavelength conversion element 512 each convert the excitation light E emitted from the first light source 41 into yellow fluorescence Y. The excitation light E emitted from the third light source 43 is incident on the first wavelength conversion element 511. The excitation light E emitted from the fourth light source 44 is incident on the second wavelength conversion element 512.

[0090] The light guiding unit 70 is composed of a plate-shaped light-transmitting member 73 made of quartz or the like. The first wavelength conversion element 511 and the second wavelength conversion element 512 are bonded to two side surfaces 73c, 73d of the light-transmitting member 73 with an optical adhesive. The yellow fluorescence Y converted by the first wavelength conversion element 511 and the second wavelength conversion element 512 is emitted from each wavelength conversion element 511, 512, travels inside the light guiding unit 70, and is emitted to the outside from a first end surface 73a of the light guiding unit 70. The other configurations of the light source device 30C are similar to those of the light source device 30A of the first embodiment.

[0091] (Effects of the third embodiment) In this embodiment, the speckle pattern also changes over time as the polarization state of blue light B changes over time, so that the same effect as in the first embodiment can be obtained, that is, speckles can be sufficiently suppressed.

[0092] [Fourth embodiment] A fourth embodiment of the present invention will be described below with reference to FIG. The basic configuration of the light source device of the fourth embodiment is the same as that of the first embodiment, but differs from the first embodiment in that a light diffusion element is added, so a description of the basic configuration of the light source device will be omitted. 9 is a cross-sectional view of a light source device 30D of the fourth embodiment cut along the XY plane. In Fig. 9, components common to those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0093] As shown in FIG. 9, the light source device 30D of this embodiment includes a first light source 41, a wavelength conversion element 51, a first light guiding section 75, a second light guiding section 76, a first optical layer 61, a second optical layer 62, a second light source 42, a control section 47, a light diffusion element 89, and a reflective layer (not shown).

[0094] The light diffusion element 89 is disposed on the first end surface 73a of the light-transmitting member 73 that constitutes the first light guide section 71 and the second light guide section 72. Specifically, the light diffusion element 89 is bonded to the first end surface 73a of the light-transmitting member 73 with an optical adhesive. The light diffusion element 89 may be made of frosted glass having a random uneven structure. Alternatively, the light diffusion element 89 may be made of a microlens array diffuser plate having a regular uneven structure. The light diffusion element 89 diffuses blue light B emitted from the first end surface 73a of the light-transmitting member 73. The light diffusion element 89 of this embodiment corresponds to the light diffusion portion in the claims. Note that the light diffusion portion may be formed by directly unevenly processing the first end surface 73a of the light-transmitting member 73. The other configurations of the light source device 30D are similar to those of the light source device 30A of the first embodiment.

[0095] (Effects of the fourth embodiment) In this embodiment, the speckle pattern also changes over time as the polarization state of blue light B changes over time, so that the same effect as in the first embodiment can be obtained, that is, speckles can be sufficiently suppressed.

[0096] The blue light propagating through each light guide 71, 72 is collimated light from the LD, a point light source, and therefore exhibits a narrow divergence angle and a narrow peak light distribution when emitted from the first end surface 73a of the translucent member 73. On the other hand, the fluorescence Y emitted from the wavelength conversion element 51 exhibits a wide divergence angle and a Lambertian light distribution. Therefore, the white light LW, which is a combination of the blue light B and the yellow fluorescence Y, may cause color unevenness in the downstream optical system due to the difference in the light distribution between the blue light and the yellow light. In contrast, the light source device 30D of this embodiment includes a light diffusion element 89 on the first end surface 73a of the translucent member 73. The blue light B is diffused by the light diffusion element 89 and emitted to the outside. This allows the light distribution of the blue light B to approach the light distribution of the yellow fluorescence Y, thereby reducing color unevenness in the downstream optical system.

[0097] [Fifth embodiment] Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG. This embodiment will exemplify another example of a projector equipped with the light source device 30A of the first embodiment. However, the projector of this example may also be equipped with the light source devices 30B, 30C, and 30D of the other embodiments. FIG. 10 is a schematic configuration diagram of a projector 15 of this embodiment.

[0098] 10, projector 15 of this embodiment includes a light source device 30A, a pickup lens 21, a rotary color wheel 22, a rod integrator 23, a condenser lens 24, a reflecting mirror 25, a digital micromirror device (DMD) 26, and a projection lens 27. That is, projector 15 of this embodiment is a projector that includes a DMD as a light modulation device.

[0099] In the case of projector 15 of this embodiment, a DMD 26 is used as the light modulation device instead of a liquid crystal panel, and therefore the polarization conversion element described in the first embodiment is not necessary. Therefore, the effect of suppressing speckles caused by changing the spatial distribution of white light using a polarization conversion element cannot be obtained. Instead, the speckle pattern caused by P-polarized light and the speckle pattern caused by S-polarized light, which are in a non-interfering relationship with each other, are superimposed on the screen SCR, thereby suppressing speckles.

[0100] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, an example was given in which the first light-emitting section and the second light-emitting section are each composed of two light-emitting elements, but the first light-emitting section and the second light-emitting section may each be composed of one light-emitting element.

[0101] In the above embodiment, the first light source is disposed facing both the first side surface and the second side surface of the wavelength conversion element, and excitation light is incident from both the first side surface and the second side surface. However, instead of this configuration, the first light source may be disposed facing only one of the first side surface and the second side surface of the wavelength conversion element, and excitation light may be incident from one side surface. In this case, a heat conductive member such as a housing may be brought into contact with the side surface on which the excitation light is not incident. This allows heat from the wavelength conversion element to be efficiently dissipated.

[0102] In addition, the specific descriptions of the shape, number, arrangement, materials, etc. of each component of the light source device and the projector are not limited to the above-described embodiments and can be modified as appropriate. Furthermore, in the above-described embodiments, an example was shown in which the light source device according to the present invention was mounted in a projector using a liquid crystal panel, but this is not limiting. The light source device according to the present invention may also be applied to a projector using a digital micromirror device as a light modulation device. Furthermore, the projector does not need to have multiple light modulation devices, and may have only one light modulation device.

[0103] In the above embodiment, the light source device of the present invention is applied to a projector, but the present invention is not limited to this. The light source device of the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

[0104] Summary of this disclosure A summary of this disclosure is provided below.

[0105] (Appendix 1) a first light source that emits first light in a first wavelength band; a wavelength conversion element that converts the first light into second light in a second wavelength band different from the first wavelength band; a second light source that emits third light in a third wavelength band; a light guiding unit disposed between the first light source and the wavelength conversion element and configured to guide each of the first light, the second light, and the third light; a control unit that controls a light emission state of the second light source; Equipped with the wavelength conversion element has a first surface and a second surface facing opposite to each other, and a third surface intersecting the first surface and the second surface; the first light emitted from the first light source passes through the light guiding portion and enters the wavelength conversion element from the third surface, the second light travels through the light guiding section and is emitted from a region of the light guiding section on the first surface side, the third light includes a fourth light in a first polarization state and a fifth light in a second polarization state different from the first polarization state, and is incident on a region of the light guiding section on the second surface side; the second light source includes a first light-emitting unit that emits the fourth light and a second light-emitting unit that emits the fifth light, each of the first light-emitting unit and the second light-emitting unit has a laser diode; The control unit changes over time the ratio between the amount of the fourth light emitted from the first light-emitting unit and the amount of the fifth light emitted from the second light-emitting unit.

[0106] According to the configuration of Supplementary Note 1, the speckle pattern changes over time as the polarization state of the third light changes over time, so that speckles originating from the third light can be sufficiently suppressed.

[0107] (Appendix 2) The light source device described in Appendix 1, wherein the second light source further has a light combining element that combines the fourth light emitted from the first light-emitting unit and the fifth light emitted from the second light-emitting unit.

[0108] According to the configuration of Supplementary Note 2, the fourth light and the fifth light are combined by the light combining element, and the combined light, which is made up of lights with different polarization states, can be efficiently incident on the area on the second surface side of the light guide section.

[0109] (Appendix 3) the control unit periodically and repeatedly changes the ratio between a plurality of periods including a first period in which the ratio is a first ratio and a second period in which the ratio is a second ratio different from the first ratio; 3. The light source device according to claim 1, wherein the repetition frequency of the plurality of periods is 60 Hz or more.

[0110] According to the configuration of Supplementary Note 3, flicker of the projected image on the projection surface can be suppressed.

[0111] (Appendix 4) The light source device described in Appendix 3, wherein the sum of the amount of light of the fourth light and the amount of light of the fifth light in the first period and the sum of the amount of light of the fourth light and the amount of light of the fifth light in the second period are equal to each other.

[0112] According to the configuration of Supplementary Note 4, the amount of the third light does not change between the first period and the second period, so that flicker of the projected image on the projection surface can be further suppressed.

[0113] (Appendix 5) the fourth light has a first center wavelength; the fifth light has a second central wavelength different from the first central wavelength, 5. The light source device according to claim 1, wherein a difference between the first central wavelength and the second central wavelength is 2 nm or more.

[0114] According to the configuration of Supplementary Note 5, the central wavelength of the third light changes by 2 nm or more for each period, so that the speckle pattern changes over time, and speckles can be effectively suppressed.

[0115] (Appendix 6) the fourth light includes a sixth light in the first polarization state and a seventh light in the first polarization state; the first light-emitting unit includes a first light-emitting element that emits the sixth light and a second light-emitting element that emits the seventh light, the fifth light includes eighth light in the second polarization state and ninth light in the second polarization state, The light source device according to any one of claims 1 to 5, wherein the second light-emitting unit has a third light-emitting element that emits the eighth light and a fourth light-emitting element that emits the ninth light.

[0116] According to the configuration of Supplementary Note 6, since each light-emitting section has two light-emitting elements, the amount of light of the third light can be increased.

[0117] (Appendix 7) the sixth light has a third central wavelength, the seventh light has a fourth central wavelength different from the third central wavelength, a difference between the third central wavelength and the fourth central wavelength is 2 nm or more; the eighth light has a fifth central wavelength, the ninth light has a sixth central wavelength different from the fifth central wavelength, 7. The light source device according to claim 6, wherein the difference between the fifth central wavelength and the sixth central wavelength is 2 nm or more.

[0118] According to the configuration of Supplementary Note 7, the fourth light and the fifth light emitted from each light-emitting unit contain light whose central wavelengths are 2 nm or more apart, so that the coherence of light within one period is reduced and speckles can be effectively suppressed.

[0119] (Appendix 8) the light guide portion has a light-transmitting member that transmits the first light, the second light, and the third light, 8. The light source device according to claim 1, wherein the second light and the third light are emitted from an end face of the light-transmitting member on the first surface side.

[0120] According to the configuration of Supplementary Note 8, the combined light of the second light and the third light can be extracted to the outside through the light-transmitting member of the light-guiding section. In addition, since the heat of the wavelength conversion element is transferred to the light-transmitting member, the temperature rise of the wavelength conversion element can be suppressed, and the decrease in wavelength conversion efficiency can be suppressed.

[0121] (Appendix 9) the light guide portion has an air layer, 8. The light source device according to claim 1, wherein the second light and the third light are emitted from a region of the air layer on the first surface side.

[0122] According to the configuration of Supplementary Note 9, the combined light of the second light and the third light can be extracted to the outside through the air layer of the light-guiding section. In addition, since the area on the first surface side of the air layer is open to the outside space, there is no refraction or reflection at the end face, and the extraction efficiency of the combined light can be increased.

[0123] (Appendix 10) the third surface of the wavelength conversion element has a first side surface and a second side surface facing in opposite directions, the light guiding section includes a first light guiding section disposed opposite the first side surface and a second light guiding section disposed opposite the second side surface, The light source device according to any one of Supplementary Note 1 to Supplementary Note 9, wherein the first light source includes a third light source that causes the first light to be incident on the wavelength conversion element via the first light guiding section, and a fourth light source that causes the first light to be incident on the wavelength conversion element via the second light guiding section.

[0124] According to the configuration of Supplementary Note 10, the amount of the first light incident on the wavelength conversion element can be increased, and therefore the amount of the second light can be increased.

[0125] (Appendix 11) the wavelength conversion element includes a first wavelength conversion element that converts the first light and the second light into the third light, and a second wavelength conversion element that converts the first light and the second light into the third light, the light guiding portion is disposed between the first wavelength conversion element and the second wavelength conversion element, The light source device according to any one of claims 1 to 9, wherein the first light source includes a third light source that causes the first light to be incident on the first wavelength conversion element and a fourth light source that causes the first light to be incident on the second wavelength conversion element.

[0126] According to the configuration of Supplementary Note 11, the amount of the first light incident on the wavelength conversion element can be increased, and therefore the amount of the second light can be increased.

[0127] (Appendix 12) the first light is blue light; the second light is yellow light containing a green light component and a red light component, 12. The light source device according to claim 1, wherein the third light is blue light.

[0128] According to the configuration of Supplementary Note 12, a light source device capable of efficiently emitting white light can be realized.

[0129] (Appendix 13) The light source device according to any one of claims 1 to 12, further comprising a light diffusion section arranged in a region on the first surface side of the light guide section and diffusing the third light.

[0130] According to the configuration of Supplementary Note 13, the light distribution of the third light can be widened to approach the light distribution of the second light, thereby reducing color unevenness in the optical system at the subsequent stage.

[0131] (Appendix 14) 14. The light source device according to claim 1, wherein the first light source has a light emitting diode that emits the first light.

[0132] According to the configuration of Supplementary Note 14, it is possible to reduce the cost of the light source device and improve the light emission efficiency.

[0133] (Appendix 15) A light source device according to any one of Supplementary Note 1 to Supplementary Note 14; a polarization conversion element that converts the polarization state of light emitted from the light source device; A lighting device comprising:

[0134] According to the configuration of Supplementary Note 15, the emission position of the third light from the polarization conversion element changes depending on the first period and the second period, so that the spatial distribution of the third light in the optical system subsequent to the polarization conversion element changes over time, thereby changing the speckle pattern over time, and thus making it possible to more effectively suppress speckles.

[0135] (Appendix 16) A light source device according to any one of Supplementary Note 1 to Supplementary Note 14; a light modulation device that modulates the light emitted from the light source device; a projection optical device that projects the light modulated by the light modulation device; A projector equipped with

[0136] According to the configuration of Appendix 16, the light source device emits a composite light that combines the second light and the third light, so that only one light source device is required, and a projector with a highly efficient and simple configuration and excellent display quality can be realized. [Explanation of symbols]

[0137] 10, 15...Projector, 30A, 30B, 30C, 30D...Light source device, 41...First light source, 42...Second light source, 42A...First light-emitting section, 42B...Second light-emitting section, 43...Third light source, 44...Fourth light source, 47...Control section, 51...Wavelength conversion element, 51a...First end face (first surface), 51b...Second end face (second surface), 51c...First side face (third surface), 51d...Second side face (third surface), 70...Light guiding section, 71, 75...First light guiding section, 72, 76...Second light guiding section, 73...Translucent member, 77...Air layer, 89...Light diffusion element (light diffusion section), 95...Light synthesis Element, 511...first wavelength conversion element, 512...second wavelength conversion element, 961...first light-emitting element, 962...second light-emitting element, 963...third light-emitting element, 964...fourth light-emitting element, 400B, 400G, 400R...light modulation device, 600...projection optical device, E...excitation light (first light), B...blue light (second light), Y...yellow fluorescence (third light), Bp...P-polarized blue light (fourth light), Bs...S-polarized blue light (fifth light), Bp1...blue light ray (sixth light), Bp2...blue light ray (seventh light), Bs3...blue light ray (eighth light), Bs4...blue light ray (ninth light).

Claims

1. a first light source that emits first light in a first wavelength band; a wavelength conversion element that converts the first light into second light in a second wavelength band different from the first wavelength band; a second light source that emits third light in a third wavelength band; a light guide portion disposed between the first light source and the wavelength conversion element and configured to guide each of the first light, the second light, and the third light; a control unit that controls a light emission state of the second light source; Equipped with the wavelength conversion element has a first surface and a second surface facing opposite to each other, and a third surface intersecting the first surface and the second surface; the first light emitted from the first light source passes through the light guiding portion and enters the wavelength conversion element from the third surface, the second light travels through the light guiding section and is emitted from a region on the first surface side of the light guiding section, the third light includes a fourth light in a first polarization state and a fifth light in a second polarization state different from the first polarization state, and is incident on a region of the light guiding unit on the second surface side; the second light source includes a first light-emitting unit that emits the fourth light and a second light-emitting unit that emits the fifth light, each of the first light-emitting unit and the second light-emitting unit includes a laser diode; The control unit changes, over time, a ratio between the amount of the fourth light emitted from the first light-emitting unit and the amount of the fifth light emitted from the second light-emitting unit.

2. The light source device according to claim 1 , wherein the second light source further includes a light combining element that combines the fourth light emitted from the first light-emitting portion and the fifth light emitted from the second light-emitting portion.

3. the control unit periodically and repeatedly changes the ratio between a plurality of periods including a first period in which the ratio is a first ratio and a second period in which the ratio is a second ratio different from the first ratio; 3. The light source device according to claim 1, wherein a repetition frequency of the plurality of periods is 60 Hz or more.

4. 4. The light source device according to claim 3, wherein a sum of the amount of the fourth light and the amount of the fifth light in the first period and a sum of the amount of the fourth light and the amount of the fifth light in the second period are equal to each other.

5. the fourth light has a first center wavelength; the fifth light has a second center wavelength different from the first center wavelength, 3. The light source device according to claim 1, wherein the difference between the first central wavelength and the second central wavelength is 2 nm or more.

6. the fourth light includes a sixth light in the first polarization state and a seventh light in the first polarization state; the first light-emitting unit includes a first light-emitting element that emits the sixth light and a second light-emitting element that emits the seventh light, the fifth light includes eighth light in the second polarization state and ninth light in the second polarization state, 3 . The light source device according to claim 1 , wherein the second light-emitting section includes a third light-emitting element that emits the eighth light and a fourth light-emitting element that emits the ninth light.

7. the sixth light has a third center wavelength, the seventh light has a fourth center wavelength different from the third center wavelength, a difference between the third central wavelength and the fourth central wavelength is 2 nm or more; the eighth light has a fifth center wavelength, the ninth light has a sixth central wavelength different from the fifth central wavelength, The light source device according to claim 6 , wherein the difference between the fifth central wavelength and the sixth central wavelength is 2 nm or more.

8. the light guide portion has a light-transmitting member that transmits the first light, the second light, and the third light, 3. The light source device according to claim 1, wherein the second light and the third light are emitted from an end face of the light-transmitting member on the first surface side.

9. the light guide portion has an air layer, 3. The light source device according to claim 1, wherein the second light and the third light are emitted from a region of the air layer on the first surface side.

10. the third surface of the wavelength conversion element has a first side surface and a second side surface facing opposite to each other, the light guiding section includes a first light guiding section disposed opposite the first side surface and a second light guiding section disposed opposite the second side surface, 3. The light source device according to claim 1, wherein the first light source includes a third light source that causes the first light to be incident on the wavelength conversion element via the first light guiding section, and a fourth light source that causes the first light to be incident on the wavelength conversion element via the second light guiding section.

11. the wavelength conversion element includes a first wavelength conversion element that converts the first light and the second light into the third light, and a second wavelength conversion element that converts the first light and the second light into the third light, the light guiding portion is disposed between the first wavelength conversion element and the second wavelength conversion element, 3. The light source device according to claim 1, wherein the first light source includes a third light source that causes the first light to be incident on the first wavelength conversion element, and a fourth light source that causes the first light to be incident on the second wavelength conversion element.

12. the first light is blue light, the second light is yellow light containing a green light component and a red light component, The light source device according to claim 1 , wherein the third light is blue light.

13. The light source device according to claim 1 , further comprising a light diffusion section arranged in a region on the first surface side of the light guide section, the light diffusion section diffusing the third light.

14. 3. The light source device according to claim 1, wherein the first light source includes a light emitting diode that emits the first light.

15. The light source device according to claim 1 or 2; a polarization conversion element that converts the polarization state of light emitted from the light source device; A lighting device comprising:

16. The light source device according to claim 1 or 2; a light modulation device that modulates the light emitted from the light source device; a projection optical device that projects the light modulated by the light modulation device; A projector equipped with

Images