Illumination device and projector

Abstract

The lighting device and the projector are high in efficiency. This illumination device is provided with: a first light source unit that emits first light of a first wavelength band; a second light source unit that emits second light of a second wavelength band different from the first wavelength band; a light synthesizing element that synthesizes the first light and the second light and emits synthesized light; a diffusion member that diffuses the synthesized light emitted from the light synthesizing element; and a concave mirror that condenses the combined light emitted from the light combining element and causes the condensed combined light to enter the diffusion member.

Description

Technical Field

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

[0002] For the purpose of improving the performance of a projector, a projector having an illumination device using a laser light source as a wide color gamut and high efficiency light source is proposed. Patent document 1 below discloses an illumination device including: a light source device including a blue laser, a green laser, and a red laser; a focusing optical system that focuses light emitted from the light source device; and a diffusion plate that diffuses light emitted from the focusing optical system.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-61110

[0004] Patent document 1 discloses a structure in which light emitted from lasers of different colors is synthesized to generate white synthesized light, and then the synthesized light is focused on a diffuser using a condenser lens. However, in a structure in which the synthesized light is focused using a condenser lens, the spot size of the synthesized light on the diffuser becomes larger. As a result, there is a problem in that the light utilization efficiency of the optical system at the subsequent stage of the diffuser is reduced. Summary of the invention

[0005] In order to solve the above-mentioned problems, a lighting device of one embodiment of the present invention comprises: a first light source unit, which emits a first light in a first wavelength band; a second light source unit, which emits a second light in a second wavelength band different from the first wavelength band; a photosynthetic element, which synthesizes the first light and the second light and emits the synthesized light; a diffusion component, which diffuses the synthesized light emitted from the photosynthetic element; and a concave mirror, which focuses the synthesized light emitted from the photosynthetic element and makes the focused synthesized light incident on the diffusion component.

[0006] A projector according to one embodiment of the present invention comprises: an illumination device according to one embodiment of the present invention; a light modulator that modulates light including the synthetic light emitted from the illumination device according to image information; and a projection optical device that projects the light modulated by the light modulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic configuration diagram of a projector according to the first embodiment.

[0008] Figure 2 This is a schematic structural diagram of the lighting device according to the first embodiment.

[0009] Figure 3 It is the front view of the diffusion device.

[0010] Figure 4 It is along Figure 3 A cross-sectional view of the diffuser plate along line IV-IV.

[0011] Figure 5 This is a schematic structural diagram of a lighting device according to a second embodiment.

[0012] Description of symbols

[0013] 10: Projector; 20: Blue light source unit (first light source unit); 30: Green light source unit (second light source unit); 40: Red light source unit (third light source unit); 50: Photosynthesis element; 60: Concave mirror; 71, 75: Diffuser plate (diffuser component); 72: Driving device; 80: Collimating optical system; 90: Double-sided multi-lens array (multi-lens optical system): 100: Overlapping lens; 400R: Light modulator for red light; 400G: Light modulator for green light; 400B: Light modulator for blue light; 600: Projection optical device; 700, 720: Illumination device; LB: Blue light (first light); LG: Green light (second light); LR: Red light (third light); LW: Synthesized light. DETAILED DESCRIPTION

[0014] [First embodiment]

[0015] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

[0016] The projector according to the present embodiment is an example of a liquid crystal projector including an illumination device using a laser diode.

[0017] In the following drawings, in order to make each component easier to see, the scale of the dimensions may be different depending on the component.

[0018] The projector 10 of this embodiment is a projection type image display device that displays a color image on a screen (projected surface) SCR. The projector 10 includes three light modulators corresponding to the respective colors of red light LR, green light LG, and blue light LB. The projector 10 includes a laser diode that can obtain high-brightness and high-output light as a light emitting element of the light source device.

[0019] Figure 1 It is a schematic configuration diagram of the projector 10 according to the present embodiment.

[0020] like Figure 1As shown, the projector 10 includes an illumination device 700, a color separation light guide optical system 200, a red light modulator 400R, a green light modulator 400G, a blue light modulator 400B, a synthesis optical system 500, and a projection optical device 600. The red light modulator 400R, the green light modulator 400G, and the blue light modulator 400B modulate light including the synthesized light LW emitted from the illumination device 700 according to image information to form image light. The projection optical device 600 projects the image light onto a screen SCR (projection surface).

[0021] Figure 2 This is a schematic structural diagram of the lighting device 700.

[0022] like Figure 2 As shown, the lighting device 700 includes a blue light source unit 20 , a green light source unit 30 , a red light source unit 40 , a photosynthesizing element 50 , a concave mirror 60 , a diffuser 70 , a collimating optical system 80 , a double-sided multi-lens array 90 , and a superimposing lens 100 .

[0023] In the following description, the axis along the emission direction of each color light LB and LR from the blue light source unit 20 and the red light source unit 40 is set as the X axis, the axis along the emission direction of the synthetic light LW from the lighting device 700 is set as the Y axis, and the axis perpendicular to the X axis and the Y axis is set as the Z axis. In addition, the axis passing through the convergence point P on the diffusion surface 71a of the diffusion plate 71 and parallel to the X axis is set as the optical axis AX1, and the axis passing through the convergence point P on the diffusion surface and parallel to the Y axis (the central axis of the synthetic light LW emitted from the diffusion plate 71) is set as the optical axis AX2.

[0024] The blue light source unit 20 includes a blue laser diode array 21 and a first collimator lens array 22. The blue light source unit 20 of the present embodiment corresponds to the first light source unit in the claims.

[0025] The blue laser diode array 21 has a plurality of blue laser diodes 211 arranged in an array. The blue laser diode 211 emits a blue light beam LB0 in a first wavelength band in the +X direction. The first wavelength band is, for example, 455 nm ± 10 nm. The number and arrangement of the blue laser diodes 211 are not particularly limited.

[0026] The first collimating lens array 22 is arranged on the light emitting side of the blue laser diode array 21. The first collimating lens array 22 has a plurality of collimating lenses 221 respectively arranged corresponding to the plurality of blue laser diodes 211. The collimating lenses 221 are composed of convex lenses. The collimating lenses 221 parallelize the blue light beam LB0 emitted from the blue laser diode 211. Hereinafter, the plurality of blue light beams LB0 emitted from the first collimating lens array 22 will be collectively referred to as blue light LB. Therefore, the blue light LB is parallel light obtained by parallelization using the first collimating lens array 22. The blue light LB of this embodiment corresponds to the first light of the claims.

[0027] The green light source unit 30 includes a green laser diode array 31 and a second collimator lens array 32. The green light source unit 30 of this embodiment corresponds to the second light source unit in the claims.

[0028] The green laser diode array 31 has a plurality of green laser diodes 311 arranged in an array. The green laser diode 311 emits a green light beam LG0 in the second wavelength band in the +Y direction. The second wavelength band is, for example, 535 nm ± 10 nm. The number and arrangement of the green laser diodes 311 are not particularly limited.

[0029] The second collimating lens array 32 is provided on the light emitting side of the green laser diode array 31. The second collimating lens array 32 has a plurality of collimating lenses 321 respectively provided corresponding to the plurality of green laser diodes 311. The collimating lenses 321 are composed of convex lenses. The collimating lenses 321 collimate the green light beam LG0 emitted from the green laser diode 311. Hereinafter, the plurality of green light beams LG0 emitted from the second collimating lens array 32 are collectively referred to as green light LG. Therefore, the green light LG is parallel light obtained by collimation using the second collimating lens array 32. The green light LG of the present embodiment corresponds to the second light of the claims.

[0030] The red light source unit 40 includes a red laser diode array 41 and a third collimator lens array 42. The red light source unit 40 of the present embodiment corresponds to the third light source unit in the claims.

[0031] The red laser diode array 41 has a plurality of red laser diodes 411 arranged in an array. The red laser diode 411 emits a red light beam LR0 in the third wavelength band in the -X direction. The third wavelength band is, for example, 640 nm ± 10 nm. The number and arrangement of the red laser diodes 411 are not particularly limited.

[0032] The third collimating lens array 42 is arranged on the light emitting side of the red laser diode array 41. The third collimating lens array 42 has a plurality of collimating lenses 421 respectively arranged corresponding to the plurality of red laser diodes 411. The collimating lens 421 is composed of a convex lens. The collimating lens 421 parallelizes the red light beam LR0 emitted from the red laser diode 411. Hereinafter, the plurality of red light beams LR0 emitted from the third collimating lens array 42 will be collectively referred to as red light LR. Therefore, the red light LR is parallel light obtained by parallelization using the third collimating lens array 42. The red light LR of this embodiment corresponds to the third light of the claims.

[0033] The light synthesis element 50 is composed of a cross dichroic prism. The cross dichroic prism has a first dichroic mirror 51 and a second dichroic mirror 52. The first dichroic mirror 51 reflects the red light LR and transmits the green light LG and the blue light LB. The second dichroic mirror 52 reflects the blue light LB and transmits the green light LG and the red light LR. Thus, the light synthesis element 50 synthesizes the blue light LB emitted from the blue light source unit 20, the green light LG emitted from the green light source unit 30, and the red light LR emitted from the red light source unit 40, and emits a white synthesized light LW toward the concave mirror 60. Since the light emitted from each laser diode is linearly polarized light, the synthesized light LW emitted from the light synthesis element 50 is also linearly polarized light.

[0034] The concave mirror 60 is disposed on the light emitting side (+Y side) of the photosynthesizing element 50. The concave mirror 60 has a reflecting surface 60a that reflects the synthesized light LW emitted from the photosynthesizing element 50. The concave mirror 60 is composed of an off-axis parabolic reflector. The off-axis parabolic reflector is a reflector whose reflecting surface is composed of a part of a parabola and the reflecting surface is configured not to intersect with the central axis (optical axis) of the parabola. In other words, the off-axis parabolic reflector has a shape in which a part of the parabola that does not include the central axis is retained in the parabola and the other parts are cut off. Therefore, the optical axis J of the concave mirror 60 is located at a position that does not intersect with the reflecting surface 60a, and is outside the incident range of the synthesized light LW to the concave mirror 60. The concave mirror 60 reflects and focuses the synthesized light LW emitted from the photosynthesizing element 50, and causes the focused synthesized light LW to be incident on the diffuser 71 described later. The specific structure of the concave mirror 60 is not particularly limited. Figure 2 In the figure, the optical axis J of the concave mirror 60 coincides with the optical axis AX2.

[0035] As described above, the color lights LB, LG, and LR incident on the photosynthesizing element 50 are parallel lights obtained by parallelization by the collimating lens arrays 22, 32, and 42, and therefore, the synthesized light LW incident on the concave mirror 60 from the photosynthesizing element 50 is also parallel light. In addition, by appropriately setting the orientation of the concave mirror 60 relative to the photosynthesizing element 50, the center axis of the synthesized light LW incident on the concave mirror 60 is parallel to the optical axis J of the concave mirror 60. According to the characteristics of the off-axis parabolic reflector, if the light incident on the off-axis parabolic reflector is parallel light and the center axis (axis parallel to the incident direction) of the incident light is parallel to the optical axis of the off-axis parabolic reflector, the light reflected by the off-axis parabolic reflector is focused on one point (focus) on the optical axis of the off-axis parabolic reflector. Therefore, in the present embodiment, the synthesized light LW reflected by the concave mirror 60 is also focused on one point on the optical axis J of the concave mirror 60. In this specification, the term "one axis is parallel to other axes" includes not only a case where one axis is completely parallel to other axes, but also a case where one axis forms an angle within ±5° with other axes.

[0036] The diffusion device 70 includes a circular diffuser plate 71 and a drive device 72. The diffuser plate 71 includes a diffuser surface 71a for diffusely reflecting the synthetic light LW emitted from the concave mirror 60. That is, the diffuser plate 71 of the present embodiment is not a transmissive diffuser plate, but a reflective diffuser plate. The diffuser surface 71a of the diffuser plate 71 is arranged at a position intersecting the optical axis AX1 and the optical axis AX2, respectively. In addition, the diffuser surface 71a of the diffuser plate 71 is arranged at the convergence point P of the synthetic light LW reflected by the concave mirror 60. In other words, the focus of the concave mirror 60 is located on the diffuser surface 71a of the diffuser plate 71. In addition, the central axis of the synthetic light LW emitted from the diffuser plate 71 is parallel to the optical axis J of the concave mirror 60.

[0037] The driving device 72 is composed of a motor, and rotates the diffuser 71 around the rotation axis C1 intersecting the diffuser surface 71a. By rotating the diffuser 71, it is possible to reduce the speckle noise that is easily generated when using the laser diode. In addition, the diffuser surface 71a in this specification does not refer to a curved surface composed of a shape of a small concave-convex structure described later, but refers to a plane in which a plurality of concave portions and a plurality of convex portions are roughly arranged. The diffuser 71 of this embodiment corresponds to the diffuser component of the claims.

[0038] Figure 3 It is a front view of the diffusion device 70. Figure 4 The diffuser plate 71 is along Figure 3 A cross-sectional view taken along line IV-IV.

[0039] like Figure 3 and Figure 4As shown, the diffuser plate 71 includes a light-transmitting substrate 710 , a metal reflective film 711 , and a dielectric multilayer film 712 .

[0040] The light-transmitting substrate 710 is made of, for example, optical glass such as BK7. The diffusion surface 71a on which the synthetic light LW is incident among the two surfaces of the light-transmitting substrate 710 is provided with a concave-convex structure 713 consisting of a plurality of concave portions and a plurality of convex portions. The concave-convex structure 713 includes a plurality of randomly arranged curved surfaces. That is, the light-transmitting substrate 710 has a concave-convex structure 713 including a plurality of concave portions and a plurality of convex portions. Each concave portion is formed into a roughly spherical shape. The depth of the concave portion is, for example, about 1 / 4 of the diameter of the sphere. The concave-convex structure 713 can be formed by cutting the light-transmitting substrate 710 by etching or the like, plastically deforming the light-transmitting substrate 710 by sandblasting or the like, and the like.

[0041] The metal reflection film 711 is provided along the concavo-convex structure 713 of the light-transmitting substrate 710. The metal reflection film 711 is made of a material containing aluminum, for example. Specifically, the metal reflection film 711 is made of high-purity aluminum having an aluminum content of 99.99 wt % or more. Preferably, the metal reflection film 711 can be made of ultra-high-purity aluminum having an aluminum content of 99.999 wt % or more.

[0042] The metal reflection film 711 is obtained by forming a pure aluminum film having a predetermined thickness and a smooth surface on the diffusion surface 71a of the light-transmitting substrate 710 using a film forming method such as a sputtering method or a vapor deposition method. In the film forming step, when a sputtering target having an aluminum content of, for example, 99.999wt% is used, a metal reflection film 711 composed of ultra-high purity aluminum having an aluminum content of 99.999wt% can be obtained.

[0043] The dielectric multilayer film 712 is provided on the surface of the metal reflective film 711 opposite to the light-transmitting substrate 710. That is, the diffuser 71 has a structure in which the metal reflective film 711 and the dielectric multilayer film 712 are sequentially stacked on the light-transmitting substrate 710. Figure 4 Although not shown in the figure, the dielectric multilayer film 712 has a structure in which two types of dielectric films having different refractive indices are alternately stacked in plurality.

[0044] At the diffuser 71 of the present embodiment, the concavo-convex structure 713 reflects the synthesized light LW emitted from the concave mirror 60 once and emits it toward the collimating optical system 80. Therefore, the synthesized light LW emitted from the concave mirror 60 is emitted from the diffuser 71 toward the collimating optical system 80 in a manner that does not undergo multiple reflections at the diffuser surface 71a. According to this structure, the synthesized light LW emitted from the concave mirror 60 does not undergo multiple reflections at the diffuser surface 71a, so it is possible to suppress the disturbance of the polarization direction of the synthesized light LW. In addition, the diffuser 71 may also be a microlens array type diffuser having a microlens array.

[0045] In addition, you can also replace Figure 4 In the structure, the diffuser 71 is not provided with a metal reflection film 711, but a dielectric multilayer film 712 is directly formed on the concave-convex structure 713 of the light-transmitting substrate 710. According to this structure, the manufacturing process of the diffuser can be simplified. However, if the structure is provided with a metal reflection film 711, the metal reflection film 711 and the dielectric multilayer film 712 both have the reflection function, so the number of layers of the dielectric multilayer film 712 can be reduced.

[0046] Alternatively, the diffuser plate 71 may also be composed of a metal substrate and a dielectric multilayer film 712. As the metal substrate, for example, an aluminum alloy can be used. As the aluminum alloy, for example, an Al-Mg-Si alloy in which magnesium (Mg) and silicon (Si) are added to aluminum (Al) is used. In addition, the aluminum alloy may also contain elements such as iron (Fe), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), and titanium (Ti). In this case, a concave-convex structure is formed on one surface of the metal substrate by sandblasting the metal substrate, and the dielectric multilayer film 712 is formed on the concave-convex structure. According to this structure, the structure of the diffuser plate can be simplified.

[0047] like Figure 2 As shown, the collimating optical system 80 is provided on the light emitting side of the diffuser plate 71 on the optical axis AX2. The collimating optical system 80 is composed of a convex lens. The collimating optical system 80 collimates the synthetic light LW emitted from the diffuser plate 71 at a predetermined diffusion angle and emits it toward the double-sided multi-lens array 90.

[0048] The double-sided multi-lens array 90 and the superimposing lens 100 constitute an integrator optical system that makes the illumination distribution of the synthesized light LW emitted from the collimating optical system 80 uniform in the image forming regions of the red light modulator 400R, the green light modulator 400G, and the blue light modulator 400B.

[0049] The double-sided multi-lens array 90 is arranged on the light emitting side of the collimating optical system 80 on the optical axis AX2. The double-sided multi-lens array 90 is a multi-lens array formed by integrating the first multi-lens surface 90a and the second multi-lens surface 90b into one component. The first multi-lens surface 90a has a plurality of lenses for dividing the synthetic light LW emitted from the collimating optical system 80 into a plurality of partial light beams. The plurality of lenses are arranged in a matrix in a plane perpendicular to the optical axis AX2. The double-sided multi-lens array 90 of this embodiment corresponds to the multi-lens optical system of the claims.

[0050] 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 overlapping lens 100 of the subsequent stage, images the images of the lenses of the first multi-lens surface 90a on the image forming areas or their vicinities of the respective image forming areas of the red light modulator 400R, the green light modulator 400G and the blue light modulator 400B. The plurality of lenses are arranged in a matrix in a plane perpendicular to the optical axis AX2. In addition, the first multi-lens surface 90a and the second multi-lens surface 90b may also be separately arranged into two multi-lens arrays. In addition, a driving device may also be provided to vibrate or swing the double-sided multi-lens array 90 in a direction perpendicular to the optical axis AX2 (in the direction of the XZ plane). By vibrating or swinging the double-sided multi-lens array 90, the speckle noise that is easily generated when using a laser diode can be reduced.

[0051] The superimposing lens 100 condenses the plurality of partial light beams emitted from the double-sided multi-lens array 90 so as to overlap each other in the image forming regions or their vicinities of the red light modulator 400R, the green light modulator 400G, and the blue light modulator 400B.

[0052] like Figure 1 As shown, the color separation light guide optical system 200 includes a dichroic mirror 240, a dichroic mirror 220, a reflector 210, a reflector 230, and a reflector 250. The color separation light guide optical system 200 separates the white synthetic light LW emitted from the illumination device 700 into red light LR, green light LG, and blue light LB, and guides the red light LR, green light LG, and blue light LB to the corresponding red light modulator 400R, green light modulator 400G, and blue light modulator 400B, respectively.

[0053] A field lens 300R is disposed between the color separation light guide optical system 200 and the red light modulator 400R. A field lens 300G is disposed between the color separation light guide optical system 200 and the green light modulator 400G. A field lens 300B is disposed between the color separation light guide optical system 200 and the blue light modulator 400B.

[0054] The dichroic mirror 240 reflects the blue light LB and transmits the red light LR and the green light LG. The dichroic mirror 220 reflects the green light LG and transmits the red light LR. The reflecting mirror 210 and the reflecting mirror 230 each reflect the red light LR. The reflecting mirror 250 reflects the blue light LB.

[0055] The red light modulator 400R is composed of a liquid crystal panel that modulates red light LR according to image information to form an image. The green light modulator 400G is composed of a liquid crystal panel that modulates green light LG according to image information to form an image. The blue light modulator 400B is composed of a liquid crystal panel that modulates blue light LB according to image information to form an image.

[0056] Although not shown in the figure, incident-side polarizing plates are disposed 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. Exit-side polarizing plates are disposed between the red light modulator 400R and the synthetic optical system 500, between the green light modulator 400G and the synthetic optical system 500, and between the blue light modulator 400B and the synthetic optical system 500. In addition, in the case where the disturbance of polarized light caused by the optical system after being emitted from the lighting device 700 can be allowed, the incident-side polarizing plate may not be disposed.

[0057] The synthesis optical system 500 synthesizes the image lights emitted from the red light modulator 400R, the green light modulator 400G, and the blue light modulator 400B. The synthesis optical system 500 is composed of a cross dichroic prism that is formed by bonding four right-angle prisms together and is approximately square in shape when viewed from above. In the cross dichroic prism, a dielectric multilayer film is provided on the approximately X-shaped interface formed by bonding the right-angle prisms together.

[0058] The image light emitted from the synthetic optical system 500 is magnified and projected onto the screen SCR by the projection optical device 600. The projection optical device 600 is composed of a plurality of lenses.

[0059] [Effects of the First Embodiment]

[0060] The lighting device 700 of this embodiment includes: a blue light source unit 20 that emits blue light LB; a green light source unit 30 that emits green light LG; a red light source unit 40 that emits red light LR; a photosynthesizing element 50 that synthesizes the blue light LB, the green light LG, and the red light LR and emits synthesized light LW; a diffusion plate 71 that diffuses the synthesized light LW emitted from the photosynthesizing element 50; and a concave mirror 60 that focuses the synthesized light LW emitted from the photosynthesizing element 50 and causes the focused synthesized light LW to enter the diffusion plate 71. The concave mirror 60 is formed of an off-axis parabolic reflector.

[0061] In the previous structure that uses a focusing lens to focus the white synthetic light on the diffuser, the glass material constituting the focusing lens has wavelength dispersion, so the actual refractive index is different according to the wavelength of the light, and as a result, chromatic aberration cannot be avoided. Therefore, when the focus of a specific color light is made consistent, other color lights become blurred, and the light spot of the synthetic light on the diffuser becomes larger as a whole. As a result, the image on the emission side multi-lens array of the rear stage of the diffuser, that is, the image of the secondary light source, becomes larger, and the optical extension becomes larger. As a result, the problem of reduced light utilization efficiency in the rear stage optical system arises. In addition, in order to minimize the reduction in light utilization efficiency, for example, it is necessary to improve the position accuracy of optical components such as the multi-lens array of the rear stage of the diffuser, the laser diode, etc., and the load of the assembly process of the lighting device becomes larger. If a combined lens including a convex lens and a concave lens is used in a focusing optical system, chromatic aberration can be corrected, but in this case, it is possible to cause the lighting device to be larger and the cost to increase.

[0062] In view of the above problems, according to the lighting device 700 of the present embodiment, as a light focusing unit for focusing light on the diffuser 71, a concave mirror 60 is used instead of a conventional lens, so that in principle, chromatic aberration does not occur. In addition, since the concave mirror 60 is composed of an off-axis parabolic reflector, in principle, spherical aberration does not occur when a spherical mirror is used. As described above, the synthetic light LW reflected by the concave mirror 60 is focused on one point on the optical axis J of the concave mirror 60, that is, one point on the diffuser 71. In addition, when the concave mirror 60 composed of an off-axis parabolic reflector is used, the focal length can be reduced compared to the case of using a lens.

[0063] Thus, according to the lighting device 700 of the present embodiment, the spot size of the synthetic light LW on the diffuser plate 71 can be reduced compared to the conventional lighting device. Thus, the secondary light source image formed on the second multi-lens surface 90b of the double-sided multi-lens array 90 can be reduced, and thus, the lighting device 700 with a small optical extension and excellent light utilization efficiency can be realized. In addition, since the secondary light source image can be reduced, the position accuracy of optical components such as the double-sided multi-lens array 90, laser diodes 211, 311, 411 can be relaxed, and the load of the assembly process of the lighting device 700 can be reduced. Moreover, since there is no need to use a lens for chromatic aberration correction, the enlargement and cost increase of the lighting device 700 can be suppressed.

[0064] In the case of this embodiment, the concave mirror 60 uses an off-axis parabolic reflector, and the optical axis J of the concave mirror 60 does not intersect with the reflecting surface 60a and is located outside the incident range of the synthetic light LW. In other words, a concave mirror 60 is used in which only a required minimum part that does not include the optical axis J is retained in the parabolic reflector and the other parts are cut off. Therefore, it is possible to avoid physical interference between optical components such as the diffuser 71 and the collimating optical system 80 and the concave mirror 60. As a result, the loss of the synthetic light LW can be suppressed, and the lighting device 700 can be miniaturized.

[0065] The projector 10 of this embodiment includes: the lighting device 700 of this embodiment; light modulators 400R, 400G, and 400B, which modulate light including synthetic light LW emitted from the lighting device 700 according to image information; and a projection optical device 600, which projects the light modulated by the light modulators 400R, 400G, and 400B.

[0066] According to this configuration, it is possible to realize the projector 10 which is excellent in light utilization efficiency.

[0067] [Second embodiment]

[0068] Below, use Figure 5 A second embodiment of the present invention will be described.

[0069] The basic structure of the projector of the second embodiment is the same as that of the first embodiment, but the structure of the illumination device is different from that of the first embodiment. Therefore, the description of the basic structure of the projector is omitted.

[0070] Figure 5 It is a schematic structural diagram of a lighting device 720 according to the second embodiment.

[0071] exist Figure 5 In the first embodiment, Figure 2 The same components are denoted by the same reference numerals, and description thereof will be omitted.

[0072] like Figure 5 As shown, the lighting device 720 of this embodiment includes a blue light source unit 20, a green light source unit 30, a red light source unit 40, a photosynthetic element 50, a concave mirror 60, a diffusion device 74, a collimating optical system 80, a double-sided multi-lens array 90, and a superimposed lens 100. The basic structure of the lighting device 720 is the same as that of the lighting device 700 of the first embodiment, and the structure of the diffusion plate 75 is different from that of the diffusion plate 71 of the first embodiment.

[0073] The diffuser plate 75 transmits and diffuses the synthesized light LW emitted from the concave mirror 60. That is, the diffuser plate 75 of this embodiment is different from the diffuser plate 71 of the first embodiment and is a transmissive diffuser plate. The diffuser plate 75 can be composed of a translucent substrate provided with a concave-convex structure, or a translucent substrate containing a light scattering material. The diffuser plate 75 is arranged at the convergence point P of the synthesized light LW reflected by the concave mirror 60. In the case of this embodiment, the light source units 20, 30, 40 of each color, the photosynthetic element 50 and the concave mirror 60 are arranged in a direction rotated 90 degrees clockwise relative to these components of the first embodiment, and the diffuser plate 75 is arranged parallel to the optical axis J of the concave mirror 60. The other structures of the lighting device 720 are the same as those of the lighting device 700 of the first embodiment.

[0074] [Effects of the Second Embodiment]

[0075] In this embodiment, compared with the previous lighting device, the spot size on the diffuser 75 can also be reduced, so the secondary light source image can be reduced, and the lighting device 720 with excellent light utilization efficiency can be realized. The position accuracy of optical components such as the double-sided multi-lens array 90 can be relaxed, and the load of the assembly process of the lighting device 720 can be reduced. There is no need to use lenses for chromatic aberration correction. Therefore, the same effect as the first embodiment can be obtained, which can suppress the enlargement and cost increase of the lighting device 720.

[0076] In addition, the technical scope of the present invention is not limited to the above-mentioned embodiment, and various modifications can be added within the scope not departing from the gist of the present invention.

[0077] The lighting device of the above embodiment has an off-axis parabolic reflector as a focusing unit for focusing light on the diffuser, but it can also be equipped with a spherical mirror instead of the off-axis parabolic reflector. In this structure, chromatic aberration can also be eliminated. In addition, in the case where there is no obstacle in terms of physical interference between optical components and reduction in light utilization efficiency, a parabolic reflector having an optical axis at a position intersecting with the reflecting surface can be used instead of the off-axis parabolic reflector. In addition, the lighting device of the above embodiment has a rotatable diffuser, but the diffuser does not necessarily have to be rotatable and can also be fixed.

[0078] In addition, the specific description of the shape, number, arrangement, material, etc. of each component of the lighting device and the projector is not limited to the above-mentioned embodiment, and can be appropriately changed. In addition, in the above-mentioned embodiment, an example of mounting the lighting device of the present invention on a projector using a liquid crystal panel is shown, but it is not limited to this. The lighting device of the present invention can also be applied to a projector using a digital micromirror device as a light modulator. In addition, the projector may not have multiple light modulators, but may be a single-board projector having only one light modulator.

[0079] In the above-mentioned embodiment, an example in which the lighting device of the present invention is applied to a projector is shown, but the lighting device of the present invention is not limited thereto and can also be applied to lighting equipment, a headlight of a car, and the like.

[0080] [Summary of the present disclosure]

[0081] The following is a summary of the present disclosure.

[0082] (Note 1)

[0083] A lighting device, comprising: a first light source unit that emits a first light in a first wavelength band; a second light source unit that emits a second light in a second wavelength band different from the first wavelength band; a photosynthetic element that synthesizes the first light and the second light and emits the synthesized light; a diffusion component that diffuses the synthesized light emitted from the photosynthetic element; and a concave mirror that focuses the synthesized light emitted from the photosynthetic element and causes the focused synthesized light to be incident on the diffusion component.

[0084] According to the configuration of Supplementary Note 1, since a concave mirror is used as light focusing means for focusing light onto the diffusion member, chromatic aberration does not occur, and a lighting device with excellent light utilization efficiency can be realized.

[0085] (Note 2)

[0086] According to the lighting device described in Supplementary Note 1, the concave mirror is an off-axis parabolic reflector.

[0087] According to the structure of Supplementary Note 2, in addition to suppressing chromatic aberration, spherical aberration can also be suppressed. In addition, since physical interference between optical components such as a diffusion component and a concave mirror is avoided, the loss of synthetic light can be suppressed and the lighting device can be miniaturized.

[0088] (Note 3)

[0089] According to the lighting device described in Supplementary Note 2, the synthesized light incident on the off-axis parabolic reflector is parallel light, and the central axis of the synthesized light incident on the off-axis parabolic reflector is parallel to the optical axis of the off-axis parabolic reflector.

[0090] According to the configuration of Supplementary Note 3, the synthesized light reflected by the off-axis parabolic reflector can be focused on a focal point on the optical axis of the off-axis parabolic reflector. Thus, the light utilization efficiency can be sufficiently improved.

[0091] (Note 4)

[0092] According to the lighting device described in Supplementary Note 3, the optical axis of the off-axis parabolic reflector is located outside the incident range of the synthetic light to the off-axis parabolic reflector.

[0093] According to the structure of Supplementary Note 4, physical interference between optical components such as a diffusion component and the off-axis parabolic reflector can be reliably avoided.

[0094] (Note 5)

[0095] According to the lighting device described in Supplement 3 or 4, the focus of the off-axis parabolic reflector is located on the diffusion surface of the diffusion component.

[0096] According to the configuration of Supplementary Note 5, the synthesized light reflected by the off-axis parabolic reflector can be focused on the diffusion surface of the diffusion member. Thus, the spot size of the synthesized light on the diffusion surface can be minimized, and the light utilization efficiency can be fully improved.

[0097] (Note 6)

[0098] According to the lighting device according to Supplementary Note 4 or 5, the diffusion member is a reflection-type diffusion member that diffuses and reflects the synthetic light, and the central axis of the synthetic light emitted from the diffusion member is parallel to the optical axis of the off-axis parabolic reflector.

[0099] According to the structure of Supplementary Note 6, compared with the case of using a transmission type diffusion member, the loss associated with light scattering can be reduced and the light utilization efficiency can be improved. In addition, the diffusion member and the off-axis parabolic reflector can be efficiently arranged, and the lighting device can be miniaturized.

[0100] (Note 7)

[0101] The lighting device according to any one of Appendixes 1 to 6, further comprising a third light source unit, the third light source unit emitting a third light of a third wavelength band different from the first wavelength band and the second wavelength band, the photosynthesis element synthesizing the first light, the second light and the third light,

[0102] The first band is a blue band, the second band is a green band, and the third band is a red band.

[0103] According to the structure of Supplementary Note 7, it is possible to realize a lighting device that emits white synthetic light.

[0104] (Note 8)

[0105] The lighting device according to Supplementary Note 7, wherein each of the first light source unit, the second light source unit, and the third light source unit includes a laser diode.

[0106] According to the structure of Supplementary Note 8, it is possible to realize an illumination device that has a wide color gamut and is highly efficient and can emit linearly polarized light.

[0107] (Note 9)

[0108] The lighting device according to Supplementary Note 8 further comprises a driving device configured to rotate the diffusion member around a rotation axis intersecting the diffusion surface.

[0109] According to the structure of Supplementary Note 9, speckle noise caused by using a laser diode can be reduced.

[0110] (Note 10)

[0111] The lighting device according to any one of Supplementary Notes 1 to 9, further comprising: a collimating optical system that parallelizes the synthetic light emitted from the diffusion component; a multi-lens optical system that divides the synthetic light emitted from the collimating optical system into a plurality of partial light beams; and

[0112] A superimposing lens causes the plurality of partial light beams emitted from the multi-lens optical system to overlap on an illuminated surface.

[0113] According to the structure of Supplementary Note 10, the secondary light source image on the emission-side multi-lens surface of the multi-lens optical system can be reduced in size, and a lighting device with excellent light utilization efficiency can be realized.

[0114] (Note 11)

[0115] A projector comprising:

[0116] The lighting device as described in any one of Notes 1 to 10;

[0117] a light modulation device for modulating light including the synthetic light emitted from the illumination device according to image information; and

[0118] A projection optical device projects the light modulated by the light modulation device.

[0119] According to the structure of Supplementary Note 11, a projector with high light utilization efficiency can be realized.

Claims

1. A lighting device comprising: a first light source unit that emits a first light in a first wavelength band; a second light source unit that emits a second light in a second wavelength band different from the first wavelength band; a photosynthesizing element that synthesizes the first light and the second light and emits the synthesized light; a diffusion member for diffusing the synthesized light emitted from the light synthesizing element; as well as A concave mirror is configured to condense the synthesized light emitted from the light composing element and make the condensed synthesized light incident on the diffusion member.

2. The lighting device according to claim 1, wherein: The concave mirror is an off-axis parabolic reflector.

3. The lighting device according to claim 2, wherein: The synthesized light incident on the off-axis parabolic reflector is parallel light, and a central axis of the synthesized light incident on the off-axis parabolic reflector is parallel to an optical axis of the off-axis parabolic reflector.

4. The lighting device according to claim 3, wherein: The optical axis of the off-axis parabolic reflector is located outside the incident range of the synthetic light to the off-axis parabolic reflector.

5. The lighting device according to claim 3, wherein: The focus of the off-axis parabolic reflector is located on the diffusion surface of the diffusion component.

6. The lighting device according to claim 4, wherein: The diffusion member is a reflective diffusion member that diffuses and reflects the synthetic light. The central axis of the synthetic light emitted from the diffusion member is parallel to the optical axis of the off-axis parabolic reflector.

7. The lighting device according to claim 1 or 2, wherein: The lighting device further includes a third light source unit that emits third light in a third wavelength band that is different from the first wavelength band and the second wavelength band. The photosynthesizing element synthesizes the first light, the second light, and the third light. The first band is a blue band, the second band is a green band, and the third band is a red band.

8. The lighting device according to claim 7, wherein: The first light source unit, the second light source unit, and the third light source unit each include a laser diode.

9. The lighting device according to claim 8, wherein: The lighting device further includes a driving device that rotates the diffusion member around a rotation axis that intersects the diffusion surface.

10. The lighting device according to claim 1 or 2, wherein: The lighting device further comprises: a collimating optical system for collimating the synthetic light emitted from the diffusion component; a multi-lens optical system that splits the synthetic light emitted from the collimating optical system into a plurality of partial light beams; and A superimposing lens causes the plurality of partial light beams emitted from the multi-lens optical system to overlap on an illuminated surface.

11. A projector comprising: The lighting device according to claim 1 or 2; a light modulation device for modulating light including the synthetic light emitted from the illumination device according to image information; and A projection optical device projects the light modulated by the light modulation device.

Images