Illumination device and projector

Abstract

To provide an illumination device with less speckle noise.SOLUTION: An illumination device of the present invention comprises: a first light source unit that emits first light that is coherent light having a peak wavelength; a second light source unit that emits second light that is incoherent light having a first wavelength range including a peak wavelength; a third light source unit that emits third light in a second wavelength range different from the first wavelength range; a light composing unit that composes the first light, second light, and third light and emits first composite light; and a diffusion member that diffuses the first composite light emitted from the light composing unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lighting device and a projector.

Background Art

[0002] For the purpose of improving the performance of projectors, projectors equipped with lighting devices using laser light sources, which are light sources with a wide color gamut and high efficiency, have been proposed. Patent Document 1 below discloses a lighting device including a blue laser light source, a green laser light source, a red laser light source, a plurality of dichroic mirrors that synthesize light emitted from each laser light source, and a diffusion plate that diffuses the synthesized light synthesized by the plurality of dichroic mirrors.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses a configuration in which after synthesizing light emitted from lasers of each color, the synthesized light is diffused using a fixed diffusion plate and a rotary diffusion plate. However, in any of the fixed type and the rotary type, in the configuration of diffusing the synthesized light using a diffusion plate, there is a problem that it is difficult to sufficiently remove the speckle noise peculiar to the laser light source.

Means for Solving the Problems

[0005] To solve the above problems, a lighting device according to one aspect of the present invention includes a first light source unit that emits first light, which is coherent light having a peak wavelength; a second light source unit that emits second light, which is incoherent light having a first wavelength band including the peak wavelength; a third light source unit that emits third light having a second wavelength band different from the first wavelength band; a light combining unit that combines the first light, the second light, and the third light and emits first combined light; and a diffusing member that diffuses the first combined light emitted from the light combining unit.

[0006] A projector according to one aspect of the present invention includes the lighting device according to one aspect of the present invention, a light modulation device that modulates light including the combined light emitted from the lighting device according to image information, and a projection optical device that projects the light modulated by the light modulation device.

Brief Description of the Drawings

[0007]

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Figure 14

Mode for Carrying Out the Invention

[0008] [First Embodiment] Hereinafter, the first embodiment of the present invention will be described with reference to the drawings. The projector of the present embodiment is an example of a liquid crystal projector provided with a lighting device using a laser diode. In the following drawings, in order to make each component easy to see, the scale of the dimensions may be shown differently depending on the component.

[0009] The projector 10 of the present embodiment is a projection type image display device that displays a color image on a screen (projection surface) SCR. The projector 10 includes three light modulation devices corresponding to each color light of red light R, green light G, and blue light B. The projector 10 includes a laser diode as a light emitting element of the light source device, which can obtain high-intensity and high-output light.

[0010] FIG. 1 is a schematic configuration diagram of the projector 10 of the present embodiment. As shown in FIG. 1, the projector 10 includes a lighting device 700, a color separation light guide optical system 200, a red light modulation device 400R, a green light modulation device 400G, a blue light modulation device 400B, a synthesis optical system 500, and a projection optical device 600. The red light modulation device 400R, the green light modulation device 400G, and the blue light modulation device 400B form image light by modulating the light included in the combined light LW emitted from the lighting device 700 according to image information. The projection optical device 600 projects the image light onto a screen SCR (projection surface).

[0011] FIG. 2 is a schematic configuration diagram of the lighting device 700. As shown in FIG. 2, the lighting device 700 includes a first red light source unit 11, a second red light source unit 14, a polarization conversion element 19, a green light source unit 20, a blue light source unit 30, a light synthesis unit 40, a condenser lens 50, a diffusion device 70, a collimator lens 80, a double-sided multi-lens array 90, and a superimposing lens 100. The light synthesis unit 40 includes a first light synthesis element 41 and a second light synthesis element 42.

[0012] In the following description, as the coordinate axes, an axis parallel to the central axes of the respective color lights LR1 and LG emitted from the first red light source unit 11 and the green light source unit 20 is defined as the X-axis. An axis parallel to the central axis of the white combined light LW emitted from the lighting device 700 is defined as the Y-axis. An axis perpendicular to the X-axis and the Y-axis is defined as the Z-axis. Also, an axis parallel to the X-axis passing through the condensing point P on the diffusion surface 71a of the diffusion plate 71 is defined as the optical axis AX1. An axis parallel to the Y-axis passing through the condensing point P (the central axis of the combined light LW emitted from the diffusion plate 71) is defined as the optical axis AX2. The central axis of the red LED light LR2 emitted from the second red light source unit 14 is defined as the optical axis AX3. The central axis of the red laser light LR1 emitted from the first red light source unit 11 is defined as the optical axis AX4.

[0013] The first red light source unit 11 includes a red laser diode array 12 and a first collimator lens array 13. The first red light source unit 11 emits red laser light LR1, which is coherent light having a predetermined peak wavelength. The first red light source unit 11 of the present embodiment corresponds to the first light source unit in the claims.

[0014] The red laser diode array 12 has a plurality of red laser diodes 121 arranged in an array. The red laser diode 121 emits a red beam LR0, which is coherent light having a predetermined peak wavelength, in the +X direction. The peak wavelength is, for example, 640 nm. In FIG. 2, the plurality of red laser diodes 121 are arranged in 7 columns along the Y-axis direction, and a plurality of, for example, 4 are arranged in the direction perpendicular to the paper surface. Note that the number and arrangement of the red laser diodes 121 are not particularly limited. The red laser diode 121 is installed in such a direction that the polarization direction of the red beam LR0, which is linearly polarized light, becomes S polarization with respect to the dichroic mirror of the second photosynthetic element 42.

[0015] The first collimator lens array 13 is provided on the light emission side of the red laser diode array 12. The first collimator lens array 13 has a plurality of collimator lenses 131 provided corresponding to the respective red laser diodes 121. The collimator lens 131 is composed of a convex lens. The collimator lens 131 collimates the red beam LR0 emitted from the red laser diode 121. Hereinafter, the plurality of red beams LR0 emitted from the first collimator lens array 13 are collectively referred to as a red laser beam LR1. Therefore, the red laser beam LR1 is parallel light collimated by the first collimator lens array 13. The red laser beam LR1 of the present embodiment corresponds to the first light in the claims.

[0016] The second red light source unit 14 includes a red light emitting diode 15 and a collimator optical system 16. The second red light source unit 14 emits a red LED light LR2, which is incoherent light in a first wavelength band including the peak wavelength of the red laser beam LR1. The second red light source unit 14 of the present embodiment corresponds to the second light source unit in the claims.

[0017] The red light-emitting diode 15 emits red LED light LR2, which is incoherent light in the first wavelength band, in the -Y direction. The first wavelength band is, for example, 635 nm ± 50 nm. The red LED light LR2 emitted from the red light-emitting diode 15 is randomly polarized.

[0018] The collimator optical system 16 is provided on the light-emitting side of the red light-emitting diode 15. The collimator optical system 16 includes a first collimator lens 161 and a second collimator lens 162. Each of the first collimator lens 161 and the second collimator lens 162 is composed of a convex lens. The number of lenses constituting the collimator optical system 16 is not particularly limited. The collimator optical system 16 collimates the red LED light LR2 emitted from the red light-emitting diode 15 at a predetermined divergence angle.

[0019] FIG. 3 is a diagram showing the emission spectrum S1 of the red laser diode 121 and the emission spectrum S2 of the red light-emitting diode 15. As shown in FIG. 3, in the case of this embodiment, the peak wavelength of the red laser diode 121 is, for example, 640 nm, and the emission wavelength band is, for example, 640 nm ± 2 nm. Also, the peak wavelength of the red light-emitting diode 15 is, for example, 635 nm, and the emission wavelength band is, for example, 635 nm ± 50 nm. Thus, the emission wavelength band of the red laser diode 121 and the emission wavelength band of the red light-emitting diode 15 need to partially overlap. At least the peak wavelength of the red laser diode 121 may be included in the emission wavelength band of the red light-emitting diode 15. The peak wavelength of the red laser diode 121 and the peak wavelength of the red light-emitting diode 15 may be different as shown in FIG. 3 or may coincide. As the red laser diode 121, a two-wavelength hybrid laser diode having two different peak wavelengths may be used.

[0020] As shown in FIG. 2, the polarization conversion element 19 is provided between the second red light source unit 14 and the first light combining element 41. The polarization conversion element 19 converts the randomly polarized red LED light LR2 emitted from the red light emitting diode 15 into linearly polarized light that coincides with the polarization direction of the red laser light LR1 emitted from the red laser diode 121. Therefore, the red LED light LR2 emitted from the polarization conversion element 19 becomes S-polarized light with respect to the dichroic mirror of the second light combining element 42. By providing the polarization conversion element 19, the polarization directions of all color lights including the red LED light LR2 can be aligned, eliminating the need to arrange a polarization conversion element in the subsequent optical system.

[0021] As the polarization conversion element 19, an absorption type polarizing plate, a reflection type polarizing plate, a polarization beam splitter, etc. can be used, but it is desirable to use a reflection type polarizing plate. When a reflection type polarizing plate is used, light other than S-polarized light is reflected by the reflection type polarizing plate and returns to the red light emitting diode 15, so that the light can be reused and the utilization efficiency of the red LED light LR2 can be increased.

[0022] The first light combining element 41 is provided at a position where the optical path of the red laser light LR1 emitted from the first red light source unit 11 intersects with the optical path of the red LED light LR2 emitted from the second red light source unit 14. The first light combining element 41 combines the red laser light LR1 and the red LED light LR2 and emits a red combined light LR. The first light combining element 41 is composed of a stripe mirror having a plate shape. The first light combining element 41 is arranged at an angle of 45 degrees with respect to each of the optical axis AX3 and the optical axis AX4. The first light combining element 41 of the present embodiment reflects the red laser light LR1 and transmits the red LED light LR2. The red combined light LR of the present embodiment corresponds to the second combined light in the claims.

[0023] FIG. 4 is a front view of the first light combining element 41 as viewed from a direction that is 45 degrees with respect to each of the X-axis and the Y-axis (the direction of arrow U in FIG. 2). As shown in FIG. 4, the stripe mirror constituting the first photosynthetic element 41 has a plurality of reflection portions 41R that reflect the red laser light LR1 and a plurality of transmission portions 41T that transmit the red LED light LR2. In the case of this embodiment, in accordance with the arrangement of the plurality of red laser diodes 121 in seven columns, seven reflection portions 41R are provided. Each of the reflection portion 41R and the transmission portion 41T extends longitudinally in the Z-axis direction within a plane intersecting the optical path of the red laser light LR1 and the optical path of the red LED light LR2. The reflection portion 41R and the transmission portion 41T are alternately arranged along a direction (a direction at 45 degrees with respect to each of the X-axis and the Y-axis) orthogonal to the extending direction of each portion. The stripe mirror has a central stripe portion 41C in which the reflection portion 41R and the transmission portion 41T are alternately arranged, and a peripheral portion 41F. The peripheral portion 41F is a transmission portion that transmits the red LED light LR2. The Z-axis direction of this embodiment corresponds to the first direction in the claims.

[0024] As an example of the dimensions of the stripe mirror, the width Wr of the reflection portion 41R is 1.5 mm. The width Wt of the transmission portion 41T is 1.8 mm. Thus, the width Wr of the reflection portion 41R and the width Wt of the transmission portion 41T may be different from each other or may be the same as each other. In the case of this embodiment, it is desirable that the width Wr of the reflection portion 41R be narrower than the width Wt of the transmission portion 41T. Also, the length T in the extending direction (Z-axis direction) of the reflection portion 41R and the transmission portion 41T is 40 mm.

[0025] FIG. 5 is a cross-sectional view of the first photosynthetic element 41 along the line V-V in FIG. 4. As shown in FIG. 5, the stripe mirror constituting the first photosynthetic element 41 has a light-transmissive substrate 410 and a reflection film 411 provided on one surface of the light-transmissive substrate 410. The reflection film 411 is composed of a strip-shaped metal film, a dielectric multilayer film, or the like. In the first photosynthetic element 41, the region where the reflection film 411 is provided is the reflection portion 41R that reflects the red laser light LR1. The region where the reflection film 411 is not provided is the transmission portion 41T that transmits the red LED light LR2.

[0026] Next, the relationship between the arrangement of the red laser diode 121 and the reflecting portion 41R of the first photosynthetic element 41 will be described. FIG. 6 is a diagram showing a state in which a red beam LR0 is emitted from the red laser diode 121. As shown in FIG. 6, the red laser diode 121 has a rectangular light emitting surface 121a. When the emission direction of the red beam LR0 is the X-axis direction, the long side of the light emitting surface 121a is parallel to the Y-axis, and the short side of the light emitting surface 121a is parallel to the Z-axis. Generally, the light emitted from the laser diode diverges due to diffraction occurring at the light emitting surface. Therefore, the divergence angle in the short side direction of the light emitting surface is larger than the divergence angle in the long side direction of the light emitting surface. Thus, in the case of this embodiment, the divergence angle of the red beam LR0 in the Z-axis direction is larger than the divergence angle of the red beam LR0 in the Y-axis direction. Therefore, the beam diameter Dz of the red beam LR0 in the Z-axis direction emitted from the light emitting surface becomes larger than the beam diameter Dy of the red beam LR0 in the Y-axis direction. The Y-axis direction in this embodiment corresponds to the second direction in the claims.

[0027] In this specification, the ratio of the length in the longitudinal direction to the length in the short side direction of the light emitting surface of the laser diode is referred to as the aspect ratio. The larger the aspect ratio of the light emitting surface, the larger the ratio of the beam diameter on the larger side to the beam diameter on the smaller side. In the example of FIG. 6, Dz / Dy becomes larger. In other words, a laser diode with a larger aspect ratio of the light emitting surface emits a beam having a more elongated beam cross-sectional shape than a laser diode with a smaller aspect ratio of the light emitting surface. Currently, in generally available laser diodes, the aspect ratio of the light emitting surface of the red laser diode is larger than the aspect ratios of the light emitting surfaces of the green laser diode and the blue laser diode. Specific examples are shown below.

[0028] FIG. 7 is a diagram showing the divergence angles in the Z-axis direction and the Y-axis direction of the red beam LR0 emitted from the red laser diode 121. FIG. 8 is a diagram showing the divergence angles in the Z-axis direction and the Y-axis direction of the green beam LG0 emitted from the green laser diode 221. In the graphs of FIGS. 7 and 8, the horizontal axis represents the divergence angle (degrees), and the vertical axis represents the relative intensity when the maximum intensity at a divergence angle of 0 degrees is set to 1. The solid-line graph represents the divergence angle in the short-side direction of the light-emitting surface, and the dashed-line graph represents the divergence angle in the long-side direction of the light-emitting surface.

[0029] As shown in FIG. 8, in the green laser diode 221, the length in the short-side direction of the light-emitting surface 221a is, for example, 1 μm, the length in the long-side direction of the light-emitting surface 221a is, for example, 36 μm, and the aspect ratio of the light-emitting surface 221a is 36. At this time, the divergence angle in the short-side direction of the light-emitting surface 221a is about ±40 degrees, and the divergence angle in the long-side direction of the light-emitting surface 221a is about ±10 degrees. Although illustration is omitted, the blue laser diode 321 also exhibits substantially the same characteristics as the green laser diode 221.

[0030] On the other hand, as shown in FIG. 7, in the case of the red laser diode 121, the length in the short-side direction of the light-emitting surface 121a is, for example, 1 μm, the length in the long-side direction of the light-emitting surface 121a is, for example, 75 μm, and the aspect ratio of the light-emitting surface 121a is 75. Thus, the aspect ratio of the light-emitting surface 121a in the red laser diode 121 is approximately twice the aspect ratio of the light-emitting surface 221a in the green laser diode 221. In this case, the divergence angle in the short-side direction of the light-emitting surface 121a is about ±40 degrees, which is the same as in the case of the green laser diode 221. However, the divergence angle in the long-side direction of the light-emitting surface 121a is about ±2 degrees, which is smaller than the divergence angle of the green laser diode 221. That is, the ratio of the beam diameter in the short-side direction to the beam diameter in the long-side direction of the light-emitting surface in the red beam LR0 is larger than the ratio of the beam diameter in the short-side direction to the beam diameter in the long-side direction of the light-emitting surface in the green beam LG0. Briefly speaking, the cross-sectional shape perpendicular to the optical axis of the red beam is more elongated than the cross-sectional shape perpendicular to the optical axis of the green beam.

[0031] FIG. 9 shows the simulation result of the intensity distribution of the red laser beam LR1 emitted from the first red light source unit 11. As shown in FIG. 9, according to the simulation conducted by the inventor, since the cross-sectional shape perpendicular to the optical axis of the red beam is sufficiently slender, the intensity distribution forms a red light beam in which four beams emitted from four red laser diodes arranged in the Z-axis direction are arranged in a thin straight line, and the red light beams are arranged in seven rows in the Y-axis direction. As a result, the interval between adjacent red light beams in the Y-axis direction becomes sufficiently wide. Therefore, in the first photosynthetic element 41 shown in FIG. 4, even if a reflecting portion 41R having an area sufficient to sufficiently reflect the red light beam is provided, the interval between the reflecting portions 41R can be widened, and the area of the transmitting portion 41T can be sufficiently ensured. Thereby, the utilization efficiency of the red LED light LR2 can be increased without reducing the utilization efficiency of the red laser light LR1. As a result, the effect of suppressing the speckle noise by the red LED light LR2 can be sufficiently obtained.

[0032] On the other hand, FIG. 10 shows the simulation result of the intensity distribution of the green laser beam as a comparative example. Note that, for the green laser diode and the red laser diode, the relationship between the vertical and horizontal of the beam cross-sectional shape and the polarization direction is opposite to each other. Therefore, when the arrangement of each laser diode is aligned so that the polarization directions are the same, the vertical and horizontal of the cross-sectional shape of each beam are opposite to each other. As shown in Fig. 10, as a result of performing a simulation with the green laser diode arranged in the same manner as the red laser diode in Fig. 9, since the cross-sectional shape perpendicular to the optical axis of the green beam is not elongated like the red laser beam, the interval between adjacent green light beams does not become sufficiently wide. Therefore, even if an attempt is made to use the same first photosynthetic element as the red laser light, the interval of the reflection portions cannot be widened, and it is difficult to secure a wide area for the transmission portions. Thus, it is desirable to apply the configuration of synthesizing laser light and LED light using the first photosynthetic element 41 as in the present embodiment to red light. In the case of the present embodiment, NURM31 (manufactured by Nichia Chemical Industries, Ltd.) was used as the red laser diode, NUGM31 (manufactured by Nichia Chemical Industries, Ltd.) was used as the green laser diode, and NUBM31 (manufactured by Nichia Chemical Industries, Ltd.) was used as the blue laser diode.

[0033] In the above-described example, the aspect ratio of the light emitting surface 121a of the red laser diode 121 is 75, and the aspect ratio of the light emitting surface 221a of the green laser diode 221 is 36. According to the speculation of the present inventor, if the aspect ratio of the light emitting surface of the laser diode is 60 or more, as shown in Fig. 9, it is considered that laser light in which a plurality of elongated light beams are arranged in a stripe shape can be generated, and it is considered to be laser light suitable for the first photosynthetic element 41 of the present embodiment.

[0034] Fig. 11 is a schematic diagram showing the intensity distribution of the red synthesized light LR after being synthesized by the first photosynthetic element 41. As shown in Fig. 11, the red synthesized light LR has an intensity distribution in which a circular intensity distribution derived from the red LED light LR2 and a stripe-shaped intensity distribution derived from the red laser light LR1 are superimposed. According to the simulation conducted by the present inventor, the utilization efficiency of the red laser light LR1 before and after entering the first photosynthetic element 41 is approximately 100%. On the other hand, the utilization efficiency of the red LED light LR2 before and after entering the first photosynthetic element 41 is approximately 62.5% because the red LED light LR2 incident on the reflection part 41R of the first photosynthetic element 41 becomes a loss component. If the red LED light LR2 is mixed with the red laser light LR1 at this ratio, the speckle noise of the red synthesized light LR can be sufficiently suppressed.

[0035] As shown in Fig. 2, the green light source unit 20 includes a green laser diode array 22 and a second collimator lens array 23. The green light source unit 20 of the present embodiment corresponds to the third light source unit in the claims.

[0036] The green laser diode array 22 has a plurality of green laser diodes 221 arranged in an array. The green laser diode 221 emits a green beam LG0 in the +X direction in the second wavelength band. The second wavelength band is, for example, 535 nm ± 10 nm. The number and arrangement of the green laser diodes 221 are not particularly limited. The green laser diode 221 is installed in such a direction that the polarization direction of the green beam LG0, which is linearly polarized, becomes S polarization with respect to the dichroic mirror of the second photosynthetic element 42.

[0037] The second collimator lens array 23 is provided on the light emitting side of the green laser diode array 22. The second collimator lens array 23 has a plurality of collimator lenses 231 provided corresponding to each of the plurality of green laser diodes 221. The collimator lens 231 is composed of a convex lens. The collimator lens 231 collimates the green beam LG0 emitted from the green laser diode 221. Hereinafter, the plurality of green beams LG0 emitted from the second collimator lens array 23 are collectively referred to as green light LG. Therefore, the green light LG is parallel light collimated by the second collimator lens array 23. The green light LG of the present embodiment corresponds to the third light in the claims.

[0038] The blue light source unit 30 includes a blue laser diode array 32 and a third collimator lens array 33. The blue light source unit 30 of the present embodiment corresponds to the fourth light source unit in the claims.

[0039] The blue laser diode array 32 has a plurality of blue laser diodes 321 arranged in an array. The blue laser diode 321 emits a blue beam LB0 in the +Y direction in the third wavelength band. The third wavelength band is, for example, 455 nm ± 10 nm. The number and arrangement of the blue laser diodes 321 are not particularly limited. The blue laser diode 321 is installed in such a direction that the polarization direction of the linearly polarized blue beam LB0 is S-polarized with respect to the dichroic mirror of the second photosynthetic element 42.

[0040] The third collimator lens array 33 is provided on the light emission side of the blue laser diode array 32. The third collimator lens array 33 has a plurality of collimator lenses 331 provided corresponding to each of the plurality of blue laser diodes 321. The collimator lens 331 is composed of a convex lens. The collimator lens 331 collimates the blue beam LB0 emitted from the blue laser diode 321. Hereinafter, the plurality of blue beams LB0 emitted from the third collimator lens array 33 are collectively referred to as blue light LB. Therefore, the blue light LB is parallel light collimated by the third collimator lens array 33. The blue light LB of the present embodiment corresponds to the fourth light in the claims.

[0041] The second photosynthetic element 42 is composed of a cross dichroic prism. The cross dichroic prism has a first dichroic mirror 45 and a second dichroic mirror 46. The first dichroic mirror 45 reflects the red synthetic light LR and transmits the green light LG and the blue light LB. The second dichroic mirror 46 reflects the blue light LB and transmits the green light LG and the red synthetic light LR. Thereby, the second photosynthetic element 42 synthesizes the red synthetic light LR emitted from the first photosynthetic element 41, the green light LG emitted from the green light source unit 20, and the blue light LB emitted from the blue light source unit 30, and emits the white synthetic light LW toward the condenser lens 50. Since each color light incident on the second photosynthetic element 42 is linearly polarized light, the synthetic light LW emitted from the second photosynthetic element 42 is also linearly polarized light. The white synthetic light LW of the present embodiment corresponds to the first synthetic light in the claims.

[0042] The condenser lens 50 is provided on the light emission side of the second photosynthetic element 42. The condenser lens 50 is composed of a convex lens. The condenser lens 50 condenses the white synthetic light LW emitted from the second photosynthetic element 42 and emits it toward the diffusion plate 71.

[0043] The diffusion device 70 includes a disk-shaped diffusion plate 71 and a driving device 72. The diffusion plate 71 has a diffusion surface 71a that diffusely reflects the combined light LW emitted from the condenser lens 50. That is, the diffusion plate 71 of the present embodiment is a reflective diffusion plate, not a transmissive diffusion plate. The diffusion plate 71 is disposed at a position where the diffusion surface 71a intersects each of the optical axis AX1 and the optical axis AX2. The diffusion surface 71a forms an angle of 45 degrees with each of the optical axis AX1 and the optical axis AX2. The diffusion surface 71a of the diffusion plate 71 is disposed at the condensing point P of the combined light LW condensed by the condenser lens 50. In other words, the focal point of the condenser lens 50 is located on the diffusion surface 71a of the diffusion plate 71.

[0044] The diffusion plate 71 has, for example, a light-transmissive substrate, a metal reflection film, and a dielectric multilayer film. The light-transmissive substrate is made of, for example, optical glass such as BK7, and an uneven structure including a plurality of concave portions and a plurality of convex portions is provided on one surface. The metal reflection film is provided along the uneven structure of the light-transmissive substrate. The metal reflection film is made of a material containing, for example, aluminum. The dielectric multilayer film is provided on the surface of the light-transmissive substrate opposite to the metal reflection film. The dielectric multilayer film has a configuration in which a plurality of two types of dielectric films having different refractive indexes are alternately laminated. The diffusion plate 71 may be a microlens array type diffusion plate provided with a microlens array. The dielectric multilayer film may be directly formed on the uneven structure of the light-transmissive substrate. Alternatively, the diffusion plate 71 may be composed of a metal substrate and a dielectric multilayer film.

[0045] The driving device 72 is composed of a motor and rotates the diffusion plate 71 about a rotation axis C1 that intersects the diffusion surface 71a. By rotating the diffusion plate 71, it is possible to reduce the speckle noise that easily occurs when using a laser diode. The diffusion plate 71 of the present embodiment corresponds to the diffusion member in the claims.

[0046] The collimator lens 80 is provided on the light emission side of the diffusion plate 71 on the optical axis AX2. The collimator lens 80 is composed of a convex lens. The collimator lens 80 collimates the combined light LW emitted from the diffusion plate 71 at a predetermined diffusion angle and emits it toward the double-sided multi-lens array 90.

[0047] The double-sided multi-lens array 90 and the superimposing lens 100 constitute an integrator optical system. The integrator optical system equalizes the illuminance distribution of the combined light LW emitted from the collimator lens 80 in each image formation region of the red light modulator 400R, the green light modulator 400G, and the blue light modulator 400B.

[0048] The double-sided multi-lens array 90 is provided on the light emission side of the collimator lens 80 on the optical axis AX2. The double-sided multi-lens array 90 is a multi-lens array in which the first multi-lens surface 90a and the second multi-lens surface 90b are integrated into one member. The first multi-lens surface 90a has a plurality of lenses for dividing the combined light LW emitted from the collimator lens 80 into a plurality of partial light beams. The plurality of lenses are arranged in a matrix in a plane orthogonal to the optical axis AX2.

[0049] The second multi-lens surface 90b has a plurality of lenses corresponding to the plurality of lenses of the first multi-lens surface 90a. The second multi-lens surface 90b, together with the subsequent superimposing lens 100, forms an image of each lens of the first multi-lens surface 90a in each image formation region of the red light modulation device 400R, the green light modulation device 400G, and the blue light modulation device 400B or in the vicinity thereof. The plurality of lenses are arranged in a matrix in a plane orthogonal to the optical axis AX2. Note that the first multi-lens surface 90a and the second multi-lens surface 90b may be provided separately as two multi-lens arrays. Further, a driving device for vibrating or rocking the double-sided multi-lens array 90 in a direction orthogonal to the optical axis AX2 (a direction along the XZ plane) may be provided. By vibrating or rocking the double-sided multi-lens array 90, it is possible to reduce the speckle noise that easily occurs when using a laser diode.

[0050] The superimposing lens 100 condenses each of the plurality of partial light beams emitted from the double-sided multi-lens array 90 and superimposes them on each other in each image formation region of the red light modulation device 400R, the green light modulation device 400G, and the blue light modulation device 400B or in the vicinity thereof.

[0051] As shown in FIG. 1, the color separation light guiding optical system 200 includes a dichroic mirror 240, a dichroic mirror 220, a reflection mirror 210, a reflection mirror 230, and a reflection mirror 250. The color separation light guiding optical system 200 separates the white combined light LW emitted from the illumination device 700 into red light R, green light G, and blue light B, and guides the red light R, the green light G, and the blue light B to the corresponding red light modulation device 400R, green light modulation device 400G, and blue light modulation device 400B, respectively.

[0052] A field lens 300R is disposed between the color separation light guiding optical system 200 and the red light modulation device 400R. A field lens 300G is disposed between the color separation light guiding optical system 200 and the green light modulation device 400G. A field lens 300B is disposed between the color separation light guiding optical system 200 and the blue light modulation device 400B.

[0053] The dichroic mirror 240 reflects blue light B and transmits red light R and green light G. The dichroic mirror 220 reflects green light G and transmits blue light B. Each of the reflecting mirrors 210 and 230 reflects red light R. The reflecting mirror 250 reflects blue light B.

[0054] The red light modulator 400R is composed of a liquid crystal panel that modulates red light R according to image information to form an image. The green light modulator 400G is composed of a liquid crystal panel that modulates green light G according to image information to form an image. The blue light modulator 400B is composed of a liquid crystal panel that modulates blue light B according to image information to form an image.

[0055] Although not shown, incident-side polarizing plates are arranged between the field lens 300R and the red light modulator 400R, between the field lens 300G and the green light modulator 400G, and between the field lens 300B and the blue light modulator 400B, respectively. Exit-side polarizing plates are arranged between the red light modulator 400R and the combining optical system 500, between the green light modulator 400G and the combining optical system 500, and between the blue light modulator 400B and the combining optical system 500, respectively. Note that the incident-side polarizing plate may not be provided if the polarization disturbance by the optical system after being emitted from the illumination device 700 is tolerable.

[0056] The combining optical system 500 combines the respective image lights emitted from the red light modulator 400R, the green light modulator 400G, and the blue light modulator 400B. The combining optical system 500 is composed of a cross-dichroic prism having a substantially square shape in plan view formed by bonding four right-angled prisms. In the cross-dichroic prism, a dielectric multilayer film is provided on a substantially X-shaped interface where the right-angled prisms are bonded together.

[0057] The image light emitted from the combining optical system 500 is enlarged and projected onto the screen SCR by the projection optical device 600. The projection optical device 600 is composed of a plurality of lenses.

[0058] [Effect of the First Embodiment] The lighting device 700 of the present embodiment includes a first red light source unit 11 that emits a red laser beam LR1 which is coherent light having a peak wavelength, a second red light source unit 14 that emits a red LED light LR2 which is incoherent light having a first wavelength band including the peak wavelength of the red laser beam LR1, a green light source unit 20 that emits green light LG in a second wavelength band, a blue light source unit 30 that emits blue light LB in a third wavelength band, a light combining unit 40 that combines the red laser beam LR1, the red LED light LR2, the green light LG, and the blue light LB and emits white combined light LW, and a diffuser plate 71 that diffuses the combined light LW emitted from the light combining unit 40.

[0059] The technique of diffusing laser light using a diffuser plate and suppressing the speckle noise peculiar to laser light is a well-known technique. However, the diffuser plate is required to satisfy requirements such as reducing brightness unevenness in addition to suppressing speckle noise, and not disturbing the polarization direction of the laser light while performing other functions. Therefore, it is difficult to sufficiently suppress speckle noise only by diffusing laser light using a diffuser plate.

[0060] In response to this problem, in the lighting device 700 of the present embodiment, for red light in which speckle noise is particularly likely to be visually recognized, a first red light source unit 11 that emits a red laser beam LR1 which is coherent light and a second red light source unit 14 that emits a red LED light LR2 which is incoherent light are provided, the red laser beam LR1 and the red LED light LR2 are combined, and the combined light LW is further diffused by the diffuser plate 71. As a result, since the combined light is temporally diffused in a state where the coherence of the red light is weakened compared to the case where the red laser beam is used alone, speckle noise can be sufficiently suppressed compared to the conventional configuration.

[0061] In the lighting device 700 of the present embodiment, the light synthesizing unit 40 includes a first light synthesizing element 41 that synthesizes the red laser light LR1 and the red LED light LR2 and emits the red synthesized light LR, and the red synthesized light LR emitted from the first light synthesizing element 41, the green light LG emitted from the green light source unit 20, and the blue light LB emitted from the blue light source unit 30, and a second light synthesizing element 42 that synthesizes them and emits white synthesized light LW.

[0062] In other words, in the lighting device 700 of the present embodiment, the red laser light LR1 and the red LED light LR2 are first synthesized to generate the red synthesized light LR, and then the red synthesized light LR, the green light LG, and the blue light LB are synthesized. According to the principle of the present invention, it is only necessary that the red laser light LR1 and the red LED light LR2 are finally synthesized. For example, a configuration in which the red laser light LR1, the green light LG, and the blue light LB are first synthesized to generate white synthesized light LW, and then the red LED light LR2 is synthesized with the white synthesized light LW is also conceivable. However, in this configuration, it is necessary to arrange a synthesizing element for synthesizing the red LED light LR2 on the optical path of the white synthesized light LW, and there is a drawback that losses of the green light LG and the blue light LB occur due to this synthesizing element. On the other hand, according to the configuration of the present embodiment, since no synthesizing element is required on the optical path of the white synthesized light LW, losses of the green light LG and the blue light LB do not occur.

[0063] In the lighting device 700 of the present embodiment, the first red light source unit 11 includes a plurality of red laser diodes 121 arranged along the Z-axis direction, and the beam diameter of the red beam LR0 emitted from the red laser diode 121 in the Z-axis direction is larger than the beam diameter in the Y-axis direction. Further, the first light synthesizing element 41 is composed of a stripe mirror that reflects the red laser light LR1 and transmits the red LED light LR2, and the stripe mirror has a plurality of reflecting portions 41R and a plurality of transmitting portions 41T, and each of the reflecting portion 41R and the transmitting portion 41T extends in the Z-axis direction in a plane intersecting the optical path of the red laser light LR1 and the optical path of the red LED light LR2, and are alternately arranged in a direction intersecting the Z-axis direction.

[0064] According to this configuration, one light beam of the red laser light LR1 has a shape that extends longitudinally in the Z-axis direction. On the other hand, the first photosynthetic element 41 is composed of a stripe mirror in which a plurality of reflection portions 41R and a plurality of transmission portions 41T are arranged in a stripe shape. Thereby, the first photosynthetic element 41 can efficiently reflect the red laser light LR1 and also suppress the loss of the red LED light LR2, and can improve the light utilization efficiency of both.

[0065] In the lighting device of the present embodiment, the stripe mirror constituting the first photosynthetic element 41 has a light-transmissive substrate 410 and a reflection film 411 provided on one surface of the light-transmissive substrate 410. In the stripe mirror, the region where the reflection film 411 is provided is the reflection portion 41R, and the region where the reflection film 411 is not provided is the transmission portion 41T.

[0066] In addition to being composed of a light-transmissive substrate and a reflection film, the stripe mirror may be configured, for example, by providing a plurality of slit-shaped openings in a metal plate, using a part of the metal plate as a reflection portion, and using the openings as transmission portions. However, according to the configuration of the present embodiment in which the stripe mirror is composed of the light-transmissive substrate 410 and the reflection film 411, the loss of the red LED light LR2 can be minimized. The reason is as follows.

[0067] FIG. 12 is an enlarged view showing a stripe mirror 91 of a comparative example using a metal plate. As shown in FIG. 12, since the stripe mirror 91 of the comparative example is composed of a metal plate, it is sufficiently thick compared to the reflection film formed on the light-transmissive substrate. Therefore, the light L1 incident on the end face 91f of the opening 91h is lost due to reflection and scattering and cannot be used in the subsequent optical system. Therefore, only the light L passing through between one corner and the other corner of the opening 91h is the light that can be used in the subsequent optical system.

[0068] FIG. 13 is an enlarged view showing the stripe mirror of the first photosynthetic element 41 of the present embodiment. As shown in FIG. 13, in the configuration of the present embodiment, since the reflective film 411 is extremely thin compared to the metal plate of FIG. 12, the influence of the light incident on the end face of the reflective film 411 can be almost ignored. Therefore, even if the width W of the transmission portion 41T shown in FIG. 13 is the same as the width W of the transmission portion (opening portion 91h) of the comparative example shown in FIG. 12, the stripe mirror of the present embodiment can transmit more light L than the stripe mirror of the comparative example. As a result, according to the present embodiment, the loss of the red LED light LR2 can be suppressed, and the utilization efficiency of the red LED light LR2 can be increased.

[0069] In the lighting device 700 of the present embodiment, the first red light source unit 11 includes a red laser diode 121 and a collimator lens 131 that collimates the red beam LR0 emitted from the red laser diode 121, and the red beam LR0 emitted from one red laser diode 121 is incident on one collimator lens 131.

[0070] In other words, in the first red light source unit 11 of the present embodiment, a single-chip type laser diode in which the red beam LR0 from one red laser diode 121 is incident on one collimator lens 131 is used. According to this configuration, compared with a double-chip type laser diode, the beam diameter of the red beam LR0 emitted from the collimator lens 131 becomes smaller, so the loss of the red laser light LR1 in the first photosynthetic element 41 is reduced, and the utilization efficiency of the red laser light LR1 can be increased.

[0071] The projector 10 of the present embodiment includes the lighting device 700 of the present embodiment, light modulation devices 400R, 400G, 400B that modulate the light including the combined light LW emitted from the lighting device 700 according to image information, and a projection optical device 600 that projects the light modulated by the light modulation devices 400R, 400G, 400B.

[0072] According to this configuration, a projector 10 with excellent display quality can be realized.

[0073] [Second Embodiment] Hereinafter, a second embodiment of the present invention will be described with reference to FIG. 14. The basic configuration of the projector in the second embodiment is the same as that in the first embodiment, and the configuration of the lighting device is different from that in the first embodiment. Therefore, the description of the basic configuration of the projector is omitted.

[0074] FIG. 14 is a schematic configuration diagram of the lighting device 720 according to the second embodiment. In FIG. 14, the same reference numerals are given to the components common to FIG. 2 used in the first embodiment, and the description thereof is omitted.

[0075] As shown in FIG. 14, the lighting device 720 of the present embodiment includes a first red light source unit 11, a second red light source unit 14, a polarization conversion element 19, a green light source unit 20, a blue light source unit 30, a light combining unit 40, a condenser lens 50, a diffusion device 70, a collimator lens 80, a double-sided multi-lens array 90, a superimposing lens 100, and a reflecting element 60. The light combining unit 40 includes a first light combining element 41 and a second light combining element 42. That is, in the lighting device 720 of the present embodiment, a reflecting element 60 is added to the lighting device 720 of the first embodiment.

[0076] The reflecting element 60 is provided at a position facing the first red light source unit 11 with the first light combining element 41 interposed therebetween. The reflecting element 60 is composed of an arbitrary reflector capable of reflecting red light. The reflecting element 60 reflects the red LED light LR2 reflected by the first light combining element 41, that is, the red LED light LR2 emitted in a direction different from the red combined light LR from the first light combining element 41, toward the first light combining element 41. The red LED light LR2 reflected by the reflecting element 60 is reflected again by the first light combining element 41, and returns to the red light emitting diode 15 via the polarization conversion element 19 and the collimator optical system 16. The red LED light LR2 that has returned to the red light emitting diode 15 is reflected by the red light emitting diode 15 and is emitted again toward the collimator optical system 16. The other configuration of the lighting device 720 is the same as that of the lighting device 700 of the first embodiment.

[0077] [Effect of the Second Embodiment] Also in this embodiment, the red laser light LR1 and the red LED light LR2 are combined, and further, the combined light LW is diffused, so that the same effect as that of the first embodiment can be obtained, that is, speckle noise can be sufficiently suppressed while maintaining the utilization efficiency of each light.

[0078] Furthermore, according to the configuration of this embodiment, a reflecting element 60 is provided that reflects the red LED light LR2 reflected by the first light synthesizing element 41 toward the first light synthesizing element 41. Therefore, the red LED light LR2 reflected by the first light synthesizing element 41 does not become stray light inside the projector, and problems such as a decrease in contrast and an increase in the temperature of the optical components due to the stray light can be suppressed. In addition, since the red LED light LR2 returned to the red light emitting diode 15 is emitted again from the red light emitting diode 15, the recycling of the red LED light LR2 can be achieved, and the utilization efficiency of the red LED light LR2 can be increased.

[0079] Note that the technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. In the lighting device of the above embodiment, in the first light synthesizing element, the red laser light from the first red light source unit is reflected and the red LED light from the second red light source unit is transmitted. Instead of this configuration, the first red light source unit and the second red light source unit may be arranged in the reverse of the above embodiment, and in the first light synthesizing element, the red laser light from the first red light source unit may be transmitted and the red LED light from the second red light source unit may be reflected. In this case, the arrangement of the reflecting portion and the transmitting portion of the first light synthesizing element may be reversed from the arrangement of the above embodiment shown in FIG. 4.

[0080] In the above second embodiment, a reflecting element is used as means for blocking stray light from the first light synthesizing element. Instead of this configuration, a light absorbing material that absorbs stray light from the first light synthesizing element may be used.

[0081] In the above embodiment, it was described that it is desirable to apply the colored light synthesized from the laser light and the LED light to red light, but it may also be applied to green light or blue light.

[0082] The lighting device of the above embodiment includes a rotary diffuser, but the diffuser does not necessarily have to be rotatable and may be fixed.

[0083] In addition, regarding the specific descriptions of the shapes, numbers, arrangements, materials, etc. of the respective components of the lighting device and the projector, it is not limited to the above embodiment and can be appropriately changed. Further, in the above embodiment, an example in which the lighting device according to the present invention is mounted on a projector using a liquid crystal panel was shown, but it is not limited thereto. The lighting device according to the present invention may be applied to a projector using a digital micromirror device as a light modulation device. Further, the projector does not necessarily have to have a plurality of light modulation devices and may be a single-plate projector having only one light modulation device.

[0084] In the above embodiment, an example in which the lighting device of the present invention is applied to a projector was shown, but it is not limited thereto. The lighting device of the present invention can also be applied to lighting fixtures, automobile headlights, etc.

[0085] [Summary of the present disclosure] Hereinafter, a summary of the present disclosure is appended.

[0086] (Appended Note 1) A first light source unit that emits first light, which is coherent light having a peak wavelength; A second light source unit that emits second light, which is incoherent light having a first wavelength band including the peak wavelength; A third light source unit that emits third light in a second wavelength band different from the first wavelength band; A light synthesizing unit that synthesizes the first light, the second light, and the third light and emits first synthesized light; A diffusion member that diffuses the first synthesized light emitted from the light synthesizing unit; A lighting device comprising:

[0087] According to the configuration of Supplementary Note 1, the first light which is coherent light and the second light which is incoherent light are synthesized as light in the first wavelength band, and the first synthesized light in which the third light in the second wavelength band is further synthesized with the synthesized light in the first wavelength band is diffused, whereby speckle noise can be sufficiently suppressed while maintaining the light utilization efficiency.

[0088] (Supplementary Note 2) The first light source unit includes a laser diode. The lighting device according to Supplementary Note 1, wherein the second light source unit includes a light emitting diode.

[0089] According to the configuration of Supplementary Note 2, a first light source unit that emits the first light which is coherent light and a second light source unit that emits the second light which is incoherent light can be easily realized.

[0090] (Supplementary Note 3) The light synthesizing unit a first light synthesizing element that synthesizes the first light and the second light and emits second synthesized light; a second light synthesizing element that synthesizes the second synthesized light emitted from the first light synthesizing element and the third light emitted from the third light source unit and emits the first synthesized light; The lighting device according to Supplementary Note 2, comprising:

[0091] According to the configuration of Supplementary Note 3, since there is no need to arrange an element for synthesizing the second light on the optical path of the light obtained by synthesizing the first light and the third light, the loss of the third light can be suppressed.

[0092] (Supplementary Note 4) The first light synthesizing element is composed of a stripe mirror that reflects one of the first light and the second light and transmits the other. The stripe mirror has a plurality of reflection portions and a plurality of transmission portions. In each of the reflection portion and the transmission portion, they extend in a first direction in a plane intersecting the optical path of the first light and the optical path of the second light, and are alternately arranged along a direction intersecting the first direction. The lighting device according to Supplementary Note 3.

[0093] According to the configuration of Supplementary Note 4, the first light and the second light can be efficiently combined.

[0094] (Supplementary Note 5) The first light source unit includes a plurality of the laser diodes, the plurality of laser diodes are arranged along the first direction, the beam diameter of the first light emitted from the laser diode in the first direction is larger than the beam diameter in the second direction intersecting the first direction of the first light on the stripe mirror, the lighting device according to Supplementary Note 4.

[0095] According to the configuration of Supplementary Note 5, first light having an elongated cross-sectional shape in the first direction can be generated, and a highly efficient first light combining element can be realized.

[0096] (Supplementary Note 6) the laser diode has a light emitting surface, the ratio of the length in the second direction to the length in the first direction of the light emitting surface is 60 or more, the lighting device according to Supplementary Note 5.

[0097] According to the configuration of Supplementary Note 6, first light having a sufficiently elongated cross-sectional shape in the first direction can be generated, which is suitable for the stripe mirror.

[0098] (Supplementary Note 7) the stripe mirror has a light-transmissive substrate and a reflective film provided on one surface of the light-transmissive substrate, in the stripe mirror, the region where the reflective film is provided is the reflection portion, and the region where the reflective film is not provided is the transmission portion, the lighting device according to any one of Supplementary Notes 4 to 6.

[0099] According to the configuration of Supplementary Note 7, the loss of light transmitted through the transmission portion can be suppressed, and the light utilization efficiency can be improved.

[0100] (Supplementary Note 8) An illumination device according to any one of Appendices 3 to 7, further comprising a polarization conversion element provided between the second light source unit and the first photosynthetic element, for converting the second light emitted from the light emitting diode into linearly polarized light having a polarization direction that coincides with the polarization direction of the first light emitted from the laser diode.

[0101] According to the configuration of Appendix 8, it becomes possible to align the polarization directions of all the light, and there is no need to arrange a polarization conversion element in the subsequent optical system.

[0102] (Appendix 9) The illumination device according to Appendix 8, wherein the polarization conversion element is a reflective polarizing plate.

[0103] According to the configuration of Appendix 9, the light that has not passed through the polarization conversion element can be recycled, and the light utilization efficiency can be improved.

[0104] (Appendix 10) The first light source unit includes the laser diode and a collimator lens for collimating the first light emitted from the laser diode. The illumination device according to any one of Appendices 2 to 9, wherein the first light emitted from one laser diode is incident on one collimator lens.

[0105] According to the configuration of Appendix 10, since the beam diameter of the first light becomes smaller, the loss of the first light in the first photosynthetic element is reduced, and the utilization efficiency of the first light can be improved.

[0106] (Appendix 11) The illumination device according to any one of Appendices 3 to 9, further comprising a reflection element that reflects the second light emitted in a direction different from the emission direction of the second combined light from the first photosynthetic element toward the first photosynthetic element.

[0107] According to the configuration of Supplementary Note 11, stray light generated from the first photosynthetic element can be suppressed, and the light reflected by the reflecting element can be recycled.

[0108] (Supplementary Note 12) The lighting device further includes a fourth light source unit that emits fourth light in a third wavelength band different from the first wavelength band and the second wavelength band. The photosynthetic unit synthesizes the first light, the second light, the third light, and the fourth light. The first light is red light, the second light is red light, the third light is green light, and the fourth light is blue light. The lighting device according to any one of Supplementary Notes 1 to 11.

[0109] According to the configuration of Supplementary Note 12, white first synthesized light can be obtained, and speckle noise caused by red light, which is particularly easy to visually recognize, can be reduced.

[0110] (Supplementary Note 13) The lighting device according to any one of Supplementary Notes 1 to 12, A light modulation device that modulates the light included in the synthesized light emitted from the lighting device according to image information, A projection optical device that projects the light modulated by the light modulation device, A projector comprising the above.

[0111] According to the configuration of Supplementary Note 13, a projector with excellent display quality can be realized.

Explanation of Reference Signs

[0112] 10… Projector, 11… First red light source unit (first light source unit), 14… Second red light source unit (second light source unit), 15… Red light emitting diode, 19… Polarization conversion element, 20… Green light source unit (third light source unit), 30… Blue light source unit (fourth light source unit), 40… Light combining unit, 41… First light combining element, 41R… Reflection part, 41T… Transmission part, 42… Second light combining element, 60… Reflection element, 71… Diffusion plate (diffusion member), 121… Red laser diode, 121a… Light emitting surface, 410… Translucent substrate, 411… Reflective film, 400R… Red light modulation device, 400G… Green light modulation device, 400B… Blue light modulation device, 600… Projection optical device, 700, 720… Lighting device, LR1… Red laser light (first light), LR2… Red LED light (second light), LG… Green light (third light), LB… Blue light (fourth light), LR… Red combined light (second combined light), LW… Combined light (first combined light).

Claims

1. A first light source unit that emits first light, which is coherent light having a peak wavelength; A second light source unit that emits second light, which is incoherent light having a first wavelength band including the peak wavelength; A third light source unit that emits third light in a second wavelength band different from the first wavelength band; A light combining unit that combines the first light, the second light, and the third light and emits first combined light; A diffusing member that diffuses the first combined light emitted from the light combining unit; comprising A lighting device.

2. The first light source unit includes a laser diode, The second light source unit includes a light emitting diode, The lighting device according to claim 1.

3. The light combining unit A first light combining element that combines the first light and the second light and emits second combined light; A second light combining element that combines the second combined light emitted from the first light combining element and the third light emitted from the third light source unit and emits the first combined light; comprising The lighting device according to claim 2.

4. The first light combining element is composed of a stripe mirror that reflects one of the first light and the second light and transmits the other, The stripe mirror has a plurality of reflecting portions and a plurality of transmitting portions, Each of the reflecting portion and the transmitting portion extends in a first direction in a plane intersecting the optical path of the first light and the optical path of the second light, and are alternately arranged along a direction intersecting the first direction, The lighting device according to claim 3.

5. The first light source unit includes a plurality of the laser diodes, The plurality of laser diodes are arranged along the first direction. The beam diameter of the first light emitted from the laser diode in the first direction is larger than the beam diameter in the second direction intersecting the first direction of the first light on the stripe mirror. The lighting device according to claim 4.

6. The laser diode has a light emitting surface. The ratio of the length in the second direction to the length in the first direction of the light emitting surface is 60 or more. The lighting device according to claim 5.

7. The stripe mirror has a light transmissive substrate and a reflective film provided on one surface of the light transmissive substrate. In the stripe mirror, the region where the reflective film is provided is the reflection portion, and the region where the reflective film is not provided is the transmission portion. The lighting device according to any one of claims 4 to 6.

8. A polarization conversion element is further provided between the second light source unit and the first light combining element, and converts the second light emitted from the light emitting diode into linearly polarized light with a polarization direction matching the polarization direction of the first light emitted from the laser diode. The lighting device according to any one of claims 3 to 6.

9. The polarization conversion element is a reflective polarizing plate. The lighting device according to claim 8.

10. The first light source unit includes the laser diode and a collimator lens that collimates the first light emitted from the laser diode. The first light emitted from one of the laser diodes enters one of the collimator lenses. The lighting device according to any one of claims 2 to 6.

11. Further comprising a reflecting element that reflects the second light emitted from the first photosynthetic element in a direction different from the emission direction of the second synthesized light toward the first photosynthetic element, The lighting device according to any one of claims 3 to 6.

12. Further comprising a fourth light source unit that emits fourth light in a third wavelength band different from the first wavelength band and the second wavelength band, The photosynthetic unit synthesizes the first light, the second light, the third light, and the fourth light, The first light is red light, the second light is red light, the third light is green light, and the fourth light is blue light, The lighting device according to any one of claims 1 to 6.

13. The lighting device according to any one of claims 1 to 6, A light modulation device that modulates the light included in the first synthesized light emitted from the lighting device according to image information, A projection optical device that projects the light modulated by the light modulation device, Comprising: A projector.

Images