Illumination device and projector

Abstract

Provided are an illumination device and a projector, in which speckle noise of a projected image is reduced in a projector provided with an illumination device. An illumination device is provided with: a first light source that emits first light having a first wavelength; a second light source that emits second light having a second wavelength different from the first wavelength; a light combining member that combines the first light and the second light and emits combined light; a first diffusion device having: a first substrate having a first diffusion surface that diffuses and emits incident synthesized light; and a first drive device that rotates the first substrate. A light-condensing element that is disposed between the light-synthesizing member and the first diffusion device and that condenses the synthesized light on a first diffusion surface of the first diffusion device; a collimating element that parallelizes the combined light emitted from the first diffusion device; and a second diffusion device that is disposed between the light collecting element and the first diffusion device, and that changes the state of the spot of the synthesized light on the first diffusion surface over time.

Description

Technical Field

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

[0002] In recent years, in order to improve the performance of projectors, an illumination device including a laser light source as a light source with a wide color gamut and high efficiency, and a projector including such an illumination device have been proposed.

[0003] For example, in the projector disclosed in Patent Document 1, three colors of light emitted from a red light source array having a laser light source emitting red light, a green light source array having a laser light source emitting green light, and a blue light source array having a laser light source emitting blue light are synthesized by a color synthesis optical system, and the synthesized light is incident on a condenser lens and focused toward a diffuser plate. In the projector disclosed in Patent Document 1, the focused synthesized light passes through the diffuser plate, thereby reducing speckle noise generated in the projected image.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-078906

[0005] In the projector disclosed in Patent Document 1, the reduction of speckle noise is insufficient simply by irradiating the composite light condensed by the condenser lens to the diffusion plate and emitting the diffused composite light from the diffusion plate, and improvement is desired. Summary of the invention

[0006] An illumination device according to one embodiment of the present invention comprises: a first light source that emits a first light of a first wavelength; a second light source that emits a second light of a second wavelength different from the first wavelength; a photosynthetic component that synthesizes the first light and the second light to emit synthesized light; a first diffusion device that comprises: a first substrate that has a first diffusion surface that diffuses and emits the incident synthesized light; and a first driving device that rotates the first substrate; a focusing element that is arranged between the photosynthetic component and the first diffusion device and focuses the synthesized light on the first diffusion surface of the first diffusion device; a collimating element that parallelizes the synthesized light emitted from the first diffusion device; and a second diffusion device that is arranged between the focusing element and the first diffusion device and causes the state of the spot of the synthesized light on the first diffusion surface to change over time. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram showing the structure of a projector according to one embodiment.

[0008] Figure 2 yes Figure 1 A schematic diagram of the illumination device of a projector.

[0009] Figure 3 is observed along the axis of rotation Figure 2 A schematic diagram of a substrate of the first diffusion device of the lighting device.

[0010] Figure 4 is observed along the axis of rotation Figure 2 A schematic diagram of a substrate of a second diffusion device of an illumination device.

[0011] Figure 5 About Figure 2 Light distribution diagram of numerical calculation example 1 of the lighting device.

[0012] Figure 6 About Figure 2 Light distribution diagram of numerical calculation example 2 of the lighting device.

[0013] Figure 7 About Figure 2 Light distribution diagram of numerical calculation example 3 of the lighting device.

[0014] Figure 8 About Figure 2 Light distribution diagram of numerical calculation example 4 of the lighting device.

[0015] Fig. 9 About Figure 2 Light distribution diagram of numerical calculation example 5 of the lighting device.

[0016] Fig.10 About Figure 2 Light distribution diagram of numerical calculation example 6 of the lighting device.

[0017] Fig.11 About Figure 2 Light distribution diagram of numerical calculation example 7 of the lighting device.

[0018] Fig.12 About Figure 2 Light distribution diagram of numerical calculation example 8 of the lighting device.

[0019] Fig.13 yes Figure 2 A schematic diagram of a substrate of a first variant of a first diffusion device of an illumination device.

[0020] Fig.14 yes Figure 2 A schematic diagram of a substrate of a second variant of the first diffusion device of the lighting device.

[0021] Fig.15 yes Figure 2 A schematic diagram of a substrate of a third variant of the first diffusion device of the lighting device.

[0022] Description of symbols

[0023] 1: projector; 2: lighting device; 20R: first light source; 20G: second light source; 24: photosynthetic component; 25: focusing element; 26: collimating element; 40: first diffusion device; 45: diffusion surface (first diffusion surface); 100: second diffusion device. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings, in order to make each component easier to see, the scale of the dimensions may be changed depending on the component.

[0025] First, refer to Figure 1 A projector according to an embodiment of the present invention will be described. Figure 1 1 is a schematic diagram showing the structure of a projector 1 according to an embodiment of the present invention. The projector 1 is a projection type image display device that displays an image on a screen SCR. The projector 1 includes an illumination device 2, a color separation optical system 3, light modulation devices 4R, 4G, 4B, a color synthesis optical system 5, and a projection optical system 6. The projector 1 is a three-panel projector having three light modulation devices.

[0026] The illumination device 2 emits white light WL toward the color separation optical system 3. The white light WL is illumination light in the projector 1, and includes red light RL, green light GL, and blue light BL. The configuration of the illumination device 2 will be described later.

[0027] The color separation optical system 3 separates the white light WL into red light RL, green light GL, and blue light BL. The color separation optical system 3 includes, for example, a first dichroic mirror 11, a second dichroic mirror 12, a first total reflection mirror 13, a second total reflection mirror 14, a third total reflection mirror 15, a first relay lens 16, and a second relay lens 17.

[0028] The first dichroic mirror 11 is arranged on the optical path of the white light WL emitted from the lighting device 2, and separates the incident white light WL into red light RL, green light GL, and blue light BL. The first dichroic mirror 11 transmits the red light RL, and reflects the green light GL and the blue light BL. The second dichroic mirror 12 is arranged on the common optical path of the green light GL and the blue light BL emitted from the first dichroic mirror 11, and separates the green light GL and the blue light BL. The second dichroic mirror 12 transmits the blue light BL, and reflects the green light GL.

[0029] The first total reflection mirror 13 reflects the red light RL toward the light modulator 4R. The second total reflection mirror 14 and the third total reflection mirror 15 guide the blue light BL to the light modulator 4B. The green light GL is reflected from the second dichroic mirror 12 toward the light modulator 4G. The red light RL, the green light GL, and the blue light BL included in the white light WL correspond to the light emitted from the lighting device 2.

[0030] The first relay lens 16 is arranged on the optical path of the blue light BL between the second dichroic mirror 12 and the second total reflection mirror 14. The second relay lens 17 is arranged on the optical path of the blue light BL between the second total reflection mirror 14 and the third total reflection mirror 15. By arranging the first relay lens 16 and the second relay lens 17 as described above, the optical loss of the blue light BL can be compensated. The optical loss of the blue light BL is caused by the fact that the optical path length of the blue light BL from the first dichroic mirror 11 to the light modulator 4B is longer than the optical path length of the red light RL from the first dichroic mirror 11 to the light modulator 4R and the optical path length of the green light GL from the first dichroic mirror 11 to the light modulator 4G.

[0031] The light modulator 4R is arranged on the optical path of the red light RL reflected by the first total reflection mirror 13 and emitted from the first total reflection mirror 13. The light modulator 4R modulates the incident red light RL according to the image information input from the image input device (not shown), forms red image light, and emits the red image light. The light modulator 4G is arranged on the optical path of the green light GL reflected by the second dichroic mirror 12 and emitted from the second dichroic mirror 12. The light modulator 4G modulates the incident green light GL according to the image information input from the image input device (not shown), forms green image light, and emits green image light. The light modulator 4B is arranged on the optical path of the blue light BL reflected by the third total reflection mirror 15 and emitted from the third total reflection mirror 15. The light modulator 4B modulates the incident blue light BL according to the image information input from the image input device (not shown), forms blue image light, and emits blue image light. The image input device is, for example, a personal computer or a portable terminal device.

[0032] The light modulators 4R, 4G, and 4B use, for example, transmissive liquid crystal panels. Polarizing plates (not shown) are disposed on the incident side and the emitting side of the liquid crystal panel. A field lens 10R is disposed on the optical path of the red light RL between the first total reflection mirror 13 and the light modulator 4R. A field lens 10G is disposed on the optical path of the green light GL between the second dichroic mirror 12 and the light modulator 4G. A field lens 10B is disposed on the optical path of the blue light BL between the third total reflection mirror 15 and the light modulator 4B.

[0033] The color synthesis optical system 5 is arranged so as to straddle the optical path of the red image light emitted from the light modulator 4R, the optical path of the green image light emitted from the light modulator 4G, and the optical path of the blue image light emitted from the light modulator 4B. Figure 1 As shown, when viewed from above or from the side, the synthesis position of the colored light in the color synthesis optical system 5 overlaps with the intersection of the optical path of the red image light, the optical path of the green image light, and the optical path of the blue image light. In the color synthesis optical system 5, the red image light, the green image light, and the blue image light are synthesized to form colored image light. The color synthesis optical system 5 emits colored image light. The color synthesis optical system 5 uses, for example, a cross dichroic prism.

[0034] The projection optical system 6 is arranged on the optical path of the colored image light emitted from the color synthesis optical system 5. The colored image light emitted from the color synthesis optical system 5 is equivalent to the light modulated by the light modulating devices 4R, 4G, and 4B. The projection optical system 6 enlarges and projects the colored image light emitted from the color synthesis optical system 5 and incident toward the screen SCR. The colored image light enlarged and projected from the projection optical system 6 is displayed as a color image on a display surface opposite to the emission surface of the projection optical system 6 in the screen SCR.

[0035] The projection optical system 6 is composed of, for example, a plurality of optical lenses, but may be composed of one optical lens. The optical lens includes, for example, various lenses such as a plano-convex lens, a biconvex lens, a meniscus lens, an aspherical lens, a rod lens, and a free-form surface lens.

[0036] Next, refer to Figures 2 to 4 A lighting device according to an embodiment of the present invention will be described. Figure 2 1 is a schematic diagram showing the structure of an illumination device 2 according to an embodiment of the present invention. The illumination device 2 includes a first light source 20R, a second light source 20G, a third light source 20B, a photosynthesizing member 24, a focusing element 25, a first diffuser 40, a second diffuser 100, a collimating element 26, and an integrator optical system 50.

[0037] The first light source 20R includes a first laser element 21R and a first collimating lens 22R, and emits red light LR. The first laser element 21R emits red light LR. The red light LR has a wavelength band that includes a red wavelength in the visible wavelength band, for example, a wavelength band of 585 nm to 720 nm. The red light LR is emitted radially from the first laser element 21R with the optical axis AX1 as the center. In addition, the red light LR is equivalent to the first light. The wavelength that belongs to red included in the red light LR is equivalent to the first wavelength.

[0038] The first collimator lens 22R is disposed on the optical path of the red light LR emitted from the first laser element 21R and on the optical axis AX1. The center of the first collimator lens 22R in a direction perpendicular to the optical axis AX1 substantially overlaps the optical axis AX1. The first collimator lens 22R collimates the incident red light LR.

[0039] The second light source 20G includes a second laser element 21G and a second collimator lens 22G, and emits green light LG. The second laser element 21G emits green light LG. The green light LG has a wavelength band including a wavelength belonging to green in the visible wavelength band, for example, a wavelength band of 495 nm to 585 nm. The green light LG corresponds to the second light. The wavelength belonging to green included in the green light LG corresponds to the second wavelength.

[0040] The green light LG is emitted radially from the second laser element 21G with the optical axis AX2 as the center. Figure 2 As shown, in a plan view or a side view, an optical axis AX2 from the second laser element 21G to a position where colored lights are combined in a light combining member 24 described later is orthogonal to an optical axis AX1 from the first laser element 21R to a position where colored lights are combined in the light combining member 24 .

[0041] The second collimator lens 22G is disposed on the optical path of the green light LG emitted from the second laser element 21G and on the optical axis AX2. The center of the second collimator lens 22G in a direction perpendicular to the optical axis AX2 substantially overlaps the optical axis AX2. The second collimator lens 22G collimates the incident green light LG.

[0042] The third light source 20B has a third laser element 21B and a third collimating lens 22B, and emits blue light LB. The third laser element 21B emits blue light LB. The blue light LB has a wavelength band that includes wavelengths belonging to blue in the visible band, for example, a wavelength band of 380nm to 495nm. The blue light LB is emitted radially from the third laser element 21B with the optical axis AX1 as the center. The optical axis AX1 of the blue light LB is located on the same line as the optical axis AX1 of the red light LR, and is an axis that extends the optical axis AX1 of the red light LR toward the photosynthetic component 24 in a manner that passes through the synthesis position of the colored light in the photosynthetic component 24 and is further extended relative to the photosynthetic component 24 to the side opposite to the first light source 20R. The blue light LB is emitted parallel to and in the opposite direction to the red light LR relative to the photosynthetic component 24.

[0043] In addition, Figure 2In the embodiment, the first light source 20R, the second light source 20G, and the third light source 20B each have one laser light source and one collimating lens, but the number and relative arrangement of the laser light sources and the collimating lenses in these light sources are not particularly limited. For example, the first light source 20R, the second light source 20G, and the third light source 20B may each have more than two laser light sources and the same number of collimating lenses as these laser light sources. The first light source 20R, the second light source 20G, and the third light source 20B may each have components other than the laser light source and the collimating lens, such as a package for holding the laser light source and the collimating lens.

[0044] The light combining member 24 is arranged so as to straddle the optical path of the red light LR emitted from the first light source 20R, the optical path of the green light LG emitted from the second light source 20G, and the optical path of the blue light LB emitted from the third light source 20B. Figure 2 As shown, when viewed from above or from the side, the position where the colored lights are combined in the photosynthesizing component 24 overlaps with the intersection of the optical paths of the red light LR, the green light LG, and the blue light LB, that is, the intersection of the optical axis AX1 and the optical axis AX2.

[0045] In the light synthesis component 24, the incident red light LR, green light LG and blue light LB are synthesized to generate white light WL. The white light WL is equivalent to the synthesized light. The light synthesis component 24 emits the white light WL along the optical axis AX2. The optical axis AX2 of the white light WL is located on the same line as the optical axis AX2 of the green light LG. The optical axis AX2 of the white light WL is an axis that extends the optical axis AX2 of the green light LG toward the light synthesis component 24 in a manner that passes through the synthesis position of the colored light in the light synthesis component 24 and is further extended relative to the light synthesis component 24 to the side opposite to the second light source 20G.

[0046] The light synthesizing member 24 uses, for example, a cross dichroic prism 240. The cross dichroic prism 240 includes a first dichroic mirror 241 and a second dichroic mirror 242. When viewed from above or from the side with the optical axes AX1 and AX2 being orthogonal to each other, the reflection surface of the first dichroic mirror 241 and the reflection surface of the second dichroic mirror 242 are inclined relative to the optical axis AX1 and the optical axis AX2, respectively. When viewed from above or from the side, the reflection surface of the first dichroic mirror 241 and the reflection surface of the second dichroic mirror 242 each form an angle of 45° with the optical axes AX1 and AX2, respectively. When viewed from above or from the side with the optical axes AX1 and AX2 being orthogonal to each other, the reflection surface of the first dichroic mirror 241 and the reflection surface of the second dichroic mirror 242 are orthogonal to each other.

[0047] The first dichroic mirror 241 reflects the blue light LB and transmits the green light LG and the red light LR. The second dichroic mirror 242 reflects the red light LR and transmits the blue light LB and the green light LG. The red light LR emitted from the first light source 20R is incident on the second dichroic mirror 242 along the optical axis AX1, is reflected by the second dichroic mirror 242, is emitted to the side opposite to the second light source 20G along the optical axis AX2, and is transmitted through the first dichroic mirror 241. The green light LG emitted from the second light source 20G is incident on the first dichroic mirror 241 along the optical axis AX2, goes straight, and is transmitted through the first dichroic mirror 241 and the second dichroic mirror 242. The blue light LB emitted from the third light source 20B is incident on the first dichroic mirror 241 along the optical axis AX1, is reflected by the first dichroic mirror 241, is emitted to the side opposite to the second light source 20G along the optical axis AX2, and is transmitted through the second dichroic mirror 242.

[0048] As described above, the red light LR, green light LG, and blue light LB emitted from the first dichroic mirror 241 and the second dichroic mirror 242 are combined to generate white light WL. The white light WL is emitted from the side surface of the cross dichroic prism 240 opposite to the side surface facing the second light source 20G along the optical axis AX2.

[0049] The light-converging element 25 is disposed on the optical path of the white light WL between the light-combining component 24 and the first diffusion device 40. The light-converging element 25 converges the white light WL emitted from the light-combining component 24 and in a parallelized state toward the first diffusion device 40. The center of the light-converging element 25 in a direction orthogonal to the optical axis AX2 roughly overlaps with the optical axis AX2. The light-converging element 25 is, for example, a biconvex lens, but may also be an optical element having a light-convex function other than a biconvex lens, may also be a plano-convex lens, or may be composed of a plurality of optical lenses.

[0050] The first diffuser 40 is disposed on the optical path of the white light WL emitted from the condensing element 25. The first diffuser 40 diffuses and emits the white light WL condensed and incident by the condensing element 25. The first diffuser 40 is, for example, a reflective diffuser, and diffuses and reflects the incident white light WL.

[0051] The first diffusion device 40 includes, for example, a substrate 41 and a driving device 42. The substrate 41 corresponds to the first substrate. The driving device 42 corresponds to the first driving device. The substrate 41 includes: an incident surface 41a, which is irradiated with the white light WL focused by the focusing element 25 to form a focusing point SP of the white light WL; and a back surface 41b on the side opposite to the incident surface 41a. The substrate 41 is arranged so that the incident surface 41a faces the focusing element 25. When viewed from above or from the side with the optical axes AX1 and AX2 being orthogonal to each other, the angle between the incident surface 41a and the optical axis AX2 is 45°.

[0052] The substrate 41 is mounted on the driving device 42 in a state where it can rotate around the rotation axis OX1. The driving device 42 rotates the substrate 41 around the rotation axis OX1. The driving device 42 is, for example, a motor, and has a shaft member 43 with the rotation axis OX1 as the axis. The shaft member 43 is inserted into the center of the substrate 41 from the back side 41b, for example. The centers of the incident surface 41a and the back side 41b of the substrate 41 overlap with the rotation axis OX1. The substrate 41 rotates in conjunction with the rotation of the shaft member 43 with the rotation axis OX1 as the center, and rotates around the rotation axis OX1 as described above, so that the white light WL is diffused. In addition, the driving device 42 is not limited to a motor as long as it can rotate the substrate 41 as described above.

[0053] Figure 3 4 is a schematic diagram of the substrate 41 of the first diffusion device 40, and is a diagram of the substrate 41 viewed from the incident surface 41a side along the rotation axis OX1. Figure 2 and Figure 3 As shown, when observed along the rotation axis OX1, the focal point SP of the white light WL is formed in the area between the rotation axis OX1 and the peripheral end, which is the center in the radial direction of the incident surface 41a of the substrate 41. The incident surface 41a constitutes a diffusion surface 45 that diffuses and emits the incident white light WL. The diffusion surface 45 is equivalent to the first diffusion surface. A concave-convex structure 47 is formed on the incident surface 41a. The concave-convex structure 47 is appropriately designed in consideration of the wavelength band of the white light WL in order to appropriately diffuse the white light WL, and is made in the same way as the concave-convex structure formed on a known diffusion plate. The concave-convex structure 47 can be formed, for example, by sandblasting, or by using photolithography technology to form a plurality of microlenses having a diameter less than the wavelength of the white light WL. The concave-convex structure 47 can also be formed, for example, by dispersing a plurality of particles having an appropriate particle size on the base material of the substrate 41, and covering the plurality of particles with a resin in a manner that reflects the surface shape of the plurality of particles. In addition, the concave-convex structure 47 can also be as Figure 3 Although it is formed over the entire range in the radial direction from the center to the peripheral end of the incident surface 41a as shown, it may be formed over a range including at least a part of the region to be irradiated with the focal point SP in the radial direction.

[0054] When the substrate 41 is made of a material that is transmissive to the white light WL, such as optical glass or plastic, a reflective film (not shown) is provided on the surface of the concavo-convex structure 47. When the substrate 41 is made of a material that is reflective to the white light WL, such as metal, a reflective film (not shown) may not be provided on the surface of the concavo-convex structure 47, but by providing a reflective film, the reflection characteristics of the incident surface 41a are improved. Figure 3 In FIG. 4 , the concavo-convex structure 47 is exemplified by dots. The concavo-convex structure 47 is made of a material that transmits the white light WL and does not have a light shielding property, similarly to the substrate 41 .

[0055] The speckle pattern of the white light WL at the focal point SP changes as the substrate 41 of the first diffuser 40 rotates in the rotation direction DR around the rotation axis OX1. The white light WL is diffused and reflected on the diffusion surface 45, including a diffusion, scattering or diffraction pattern based on the concavo-convex structure 47, and is emitted from the focal point SP along the optical axis AX10 as diffused light. The optical axis AX10 passes through the center of the irradiation area of ​​the focal point SP on the incident surface 41a of the substrate 41 and is parallel to the optical axis AX1.

[0056] return Figure 2 The second diffuser 100 is disposed on the optical path of the white light WL between the focusing element 25 and the first diffuser 40. The second diffuser 100 diffuses the white light WL that is focused and incident by the focusing element 25 at a position earlier than the first diffuser 40 in the traveling direction of the white light WL, and emits the diffused white light WL toward the first diffuser 40. The second diffuser 100 is a transmission type diffuser that diffuses and transmits the incident white light WL.

[0057] The second diffusion device 100 includes, for example, a substrate 110A and a driving device 111. The substrate 110A corresponds to the second substrate. The driving device 111 corresponds to the second driving device. The substrate 110A includes an incident surface 110a on which the white light WL focused by the focusing element 25 is irradiated and an emitting surface 110b on the opposite side of the incident surface 110a. The substrate 110A is arranged so that the incident surface 110a faces the focusing element 25. The incident surface 110a is orthogonal to the optical axis AX2.

[0058] The substrate 110A is mounted on the driving device 111 in a state of being rotatable around the rotation axis OX2. The driving device 111 rotates the substrate 110A around the rotation axis OX2. The driving device 111 is, for example, a motor, and has a shaft member 112 with the rotation axis OX2 as the axis center. The shaft member 112 is inserted into the center of the substrate 110A from the incident surface 110a side, for example. The centers of the incident surface 110a and the emission surface 110b of the substrate 110A overlap with the rotation axis OX2. The substrate 110A rotates in conjunction with the rotation of the shaft member 112 with the rotation axis OX2 as the center, and rotates around the rotation axis OX2 as described above, so that the white light WL is diffused, and the intensity distribution and phase distribution at the focal point SP of the white light WL irradiated on the incident surface 41a of the substrate 41 of the first diffusion device 40, and the diameter of the focal point SP are changed. That is, the second diffuser 100 changes the state of the light-converging point SP of the white light WL on the diffuser surface 45 of the first diffuser 40 over time. The drive device 111 may be any device capable of rotating the substrate 110A as described above, and is not limited to a motor.

[0059] Figure 41 is a schematic diagram of the substrate 110A of the second diffusion device 100, and is a diagram of the substrate 110A viewed from the incident surface 110a side along the rotation axis OX2. Figure 2 and Figure 4 As shown, when viewed along the rotation axis OX2, the irradiation area of ​​the white light WL in the substrate 110A is a portion of the area between the center in the radial direction of the incident surface 110a of the substrate 110A, that is, the rotation axis OX2, and the peripheral end that does not overlap with the driving device 111.

[0060] The incident surface 110a constitutes a diffusion surface 121 that diffuses and emits the incident white light WL. The diffusion surface 121 is equivalent to a second diffusion surface. The substrate 110A rotates in the rotation direction DS, that is, the circumferential direction, with the rotation axis OX2 as the center. The incident surface 110a and the diffusion surface 121 have, for example, a first region R1, a second region R2, a third region R3, and a fourth region R4. The incident surface 110a and the diffusion surface 121 are divided into a first region R1, a second region R2, a third region R3, and a fourth region R4 in the rotation direction DS. Angles θ1, θ2, θ3, and θ4 of the first region R1, the second region R2, the third region R3, and the fourth region R4 in the rotation direction DS are 90°.

[0061] A concavo-convex structure 131 is formed in the first region R1 of the diffusion surface 121. The concavo-convex structure 131 is appropriately designed in consideration of the wavelength band of the white light WL in order to appropriately diffuse the white light WL, and is made in the same manner as the concavo-convex structure formed on a known diffusion plate. Here, the state in which the white light WL is appropriately diffused refers to the following state: as described later, the white light WL diffused by the diffusion surface 121 in the second diffusion device 100 is further diffused by the diffusion surface 45 of the first diffusion device 40 and emitted from the diffusion surface 45, and then modulated into image light by the light modulators 4R, 4G, and 4B of the projector 1, and the speckle noise caused by the image light when projected onto the screen SCR is well reduced. The concavo-convex structure 131 is equivalent to the first concavo-convex structure.

[0062] The concavoconvex structure 131 can be formed, for example, by sandblasting or etching, or can be formed by a random pattern in which convex portions and concave portions are irregularly arranged. The concavoconvex structure 131 can also be realized, for example, by forming a plurality of microlenses having a diameter less than the wavelength of the white light WL using photolithography technology. The concavoconvex structure 131 can also be formed, for example, by dispersing a plurality of particles having an appropriate particle size on the base material of the substrate 110A, and covering the plurality of particles with a resin in a manner reflecting the surface shape of the plurality of particles.

[0063] A concavo-convex structure 132 is formed in the second region R2 of the diffusion surface 121. The concavo-convex structure 132 has a diffusion characteristic that is at least different from that of the concavo-convex structure 131, and has a shape that is different from that of the concavo-convex structure 131. The concavo-convex structure 132 is equivalent to the second concavo-convex structure. Specifically, the concavo-convex structure 132 can be made by a method different from that of the concavo-convex structure 131. The concavo-convex structure 132 can also be made by the same method as that of the concavo-convex structure 131, for example, having a distribution of heights of convex portions and concave portions and spacings of convex portions and concave portions that are different from those of the concavo-convex structure 131. It is also possible that, when the concavo-convex structure 131 has a uniform concavo-convex pattern, the concavo-convex structure 132 has an uneven concavo-convex pattern. On the contrary, when the concavo-convex structure 131 has an uneven concavo-convex pattern, the concavo-convex structure 132 can have a uniform concavo-convex pattern, or the concavo-convex structure 132 can have an uneven concavo-convex pattern and have unevenness of a concavo-convex pattern that is different from that of the concavo-convex structure 131.

[0064] A concavo-convex structure 133 is formed in the third region R3 of the diffusion surface 121. The concavo-convex structure 133 has diffusion characteristics different from those of the concavo-convex structures 131 and 132, and has a shape different from those of the concavo-convex structures 131 and 132. Specifically, the concavo-convex structure 133 may be made by a method different from those of the concavo-convex structures 131 and 132. The concavo-convex structure 133 may be made by the same method as the concavo-convex structures 131 and 132, for example, having a distribution of heights of convex portions and concave portions and spacings of convex portions and concave portions that are different from those of the concavo-convex structures 131 and 132. In the case where the concavo-convex structure 132 has a uniform concavo-convex pattern, the concavo-convex structure 133 may also have an uneven concavo-convex pattern. On the contrary, in the case where the concavo-convex structure 132 has an uneven concavo-convex pattern, the concavo-convex structure 133 may have a uniform concavo-convex pattern, or the concavo-convex structure 133 may have an uneven concavo-convex pattern and have unevenness of a concavo-convex pattern that is different from those of the concavo-convex structures 131 and 132.

[0065] A concavo-convex structure 134 is formed in the fourth region R4 of the diffusion surface 121. The concavo-convex structure 134 has diffusion characteristics different from those of the concavo-convex structures 131, 132, and 133, and has a shape different from those of the concavo-convex structures 131, 132, and 133. Specifically, the concavo-convex structure 134 may be made by a method different from that of the concavo-convex structures 131, 132, and 133. The concavo-convex structure 134 may be made by the same method as that of the concavo-convex structures 131, 132, and 133, for example, having a distribution of heights of convex portions and concave portions and spacings of convex portions and concave portions different from those of the concavo-convex structures 131, 132, and 133. When the concavo-convex structures 131 and 133 have a uniform concavo-convex pattern, the concavo-convex structure 134 may have an uneven concavo-convex pattern. On the contrary, when the concavo-convex structures 131 and 133 have non-uniform concavo-convex patterns, the concavo-convex structure 134 may have a uniform concavo-convex pattern, or may have a non-uniform concavo-convex pattern and have a different non-uniformity of the concavo-convex pattern from the concavo-convex structures 131 , 132 , and 133 .

[0066] like Figure 4 As shown, the concavo-convex structures 131, 132, 133, and 134 can be formed in the entire radial range from the center to the peripheral end of the incident surface 110a, but only need to be formed in a radial range that includes at least a part of the area irradiated with the white light WL.

[0067] The substrate 110A is made of a material that is transmissive to the white light WL, such as optical glass or plastic. Figure 4 In FIG. 1 , the difference in dot density indicates that the concavo-convex structures 131 , 132 , 133 , and 134 have different diffusion characteristics. The concavo-convex structures 131 , 132 , 133 , and 134 are made of a material that transmits white light WL and does not shield light, similarly to the substrate 110A.

[0068] The substrate 110A of the second diffuser 100 rotates in the rotation direction DS about the rotation axis OX2, and the amplitude distribution and phase distribution of the white light WL emitted from the focusing element 25 are modulated according to the concavo-convex structures 131, 132, 133, and 134, and the speckle pattern of the white light WL changes. Every time the substrate 110A rotates once in the rotation direction DS, four speckle patterns of the white light WL corresponding to the concavo-convex structures 131, 132, 133, and 134 are generated. The white light WL is diffused in the diffusion surface 121, including the diffusion, scattering, or diffraction patterns based on the concavo-convex structures 131, 132, 133, and 134, and is transmitted through the substrate 110A as diffused light, and is emitted from the emission surface 110b along the optical axis AX2.

[0069] The rotation speed of the substrate 110A of the second diffuser 100 rotating in the rotation direction DS around the rotation axis OX2 is, for example, 1 / 240 [rev / sec] or more. That is, the rotation speed of the drive device 111 around the rotation axis OX2 is set to 1 / 240 [rev / sec] or more. Thus, for example, the first region R1, the second region R2, the third region R3, and the fourth region R4 irradiated with the white light WL are switched in a short time of less than every 1 / 60 second. The diffusion, scattering or diffraction pattern and the speckle pattern of the focal point SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffuser 40 change in a short time of less than every 1 / 60 second. Therefore, the frequency of the state change of the focal point SP in the diffusion surface 45 of the first diffuser 40 is 60 [Hz] or more due to the rotation of the substrate 110A. That is, the switching frequency of the diffusion, scattering or diffraction pattern and the speckle pattern of the focal point SP of the white light WL incident on the diffusion surface 45 is 60 [Hz] or more.

[0070] return Figure 2 The substrate 41 of the first diffuser 40 is irradiated with the light-convex point SP of the white light WL emitted from the emission surface 110b of the substrate 110A of the second diffuser 100 in a state of diffusion and the diffusion state switching with the passage of time. Therefore, in the speckle pattern of the white light WL reflected from the incident surface 41a of the substrate 41 of the first diffuser 40 and emitted along the optical axis AX10, the synergistic effect of any of the four concavo-convex structures 131, 132, 133, and 134 and the concavo-convex structure 47 appears. The speckle pattern of the white light WL emitted along the optical axis AX10 is determined by the optical overlap of the diffusion, scattering, or diffraction pattern of any of the concavo-convex structures 131, 132, 133, and 134 and the diffusion, scattering, or diffraction pattern of the concavo-convex structure 47, and changes with the passage of time.

[0071] The collimating element 26 is arranged on the optical path of the white light WL emitted from the substrate 41 of the first diffusion device 40. The collimating element 26 parallelizes the white light WL emitted from the incident surface 41a and the diffusion surface 45 of the substrate 41 and in a divergent and diffused state. The center of the collimating element 26 in a direction orthogonal to the optical axis AX10 roughly overlaps with the optical axis AX10. The collimating element 26 is, for example, a biconvex lens, but it can also be an optical element with a focusing function other than a biconvex lens, it can also be a plano-convex lens, and it can also be composed of a plurality of optical lenses. In addition, in the case where the collimating element 26 is composed of one optical lens, the accuracy of parallelization can be further improved by using an aspheric lens.

[0072] The integrator optical system 50 includes a multi-lens array 51 and a superimposing lens 52. The integrator optical system 50 makes the illuminance distribution of the white light WL emitted from the collimator 26 uniform in the image forming regions of the light modulators 4R, 4G, and 4B disposed in the subsequent stages.

[0073] The multi-lens array 51 is arranged on the optical path of the white light WL emitted from the collimating element 26 and in a parallelized state. The multi-lens array 51 is, for example, a double-sided multi-lens array. The double-sided multi-lens array includes a plurality of microlenses 53 for dividing the white light WL emitted from the collimating element 26 into a plurality of small light beams. The plurality of microlenses 53 are adjacent to each other along a plane orthogonal to the optical axis AX10 and are arranged in a matrix. The microlenses 53 are, for example, plano-convex lenses convex to the incident side. The double-sided multi-lens array has a first multi-lens surface 51a arranged on the incident side along the shape of the plano-convex lenses constituting the microlenses 53. The double-sided multi-lens array includes a plurality of microlenses 54, the same number as the plurality of microlenses 53, on a plane orthogonal to the optical axis AX10. The respective microlenses 54 are adjacent to each other along a plane orthogonal to the optical axis AX10, are arranged in a matrix, and overlap with the respective microlenses 53. The microlenses 54 are, for example, plano-convex lenses convex to the emission side. The plane on the emission side of each of the plurality of microlenses 54 is the same as the plane on the incident side of each of the plurality of microlenses 53. The double-sided multi-lens array has a second multi-lens surface 51b provided on the emission side along the shape of the plano-convex lens constituting the microlenses 54.

[0074] The overlapping lens 52 converges the multiple small beams of white light WL emitted from the multi-lens array 51, and cooperates with the multiple micro lenses 54 of the multi-lens array 51 to make them overlap each other in the image forming area or near the image forming area of ​​each of the light modulating devices 4R, 4G, and 4B. The overlapping lens 52 is, for example, a plano-convex lens, but it can also be an optical element with a focusing function other than a plano-convex lens, it can also be a biconvex lens, and it can also be composed of multiple optical lenses.

[0075] Next, refer to Figures 5 to 12 , an example of numerical calculation for calculating, by simulation, the light distribution on the incident surface of the plurality of microlenses 54 of the multi-lens array 51 in the lighting device 2 of the present embodiment.

[0076] Figures 5 to 12 Each figure treats the white light WL incident on the multiple microlenses 54 of the multi-lens array 51 as the same number of light rays, and uses dots to represent the locations where the light rays intersect the incident surfaces of the multiple microlenses 54, and is a figure showing the distribution of the light rays. Figures 5 to 12 The two-dot chain lines in the respective figures indicate the boundaries of the incident surfaces of the plurality of microlenses 54 .

[0077] In the following descriptions related to this simulation, cos nθ represents the diffusion state of the white light WL when it is diffused by one of the concavo-convex structures 131, 132, 133, and 134 formed on the incident surface 110a and the diffusion surface 121 of the substrate 110A of the second diffuser 100, for example, the concavo-convex structure 131, as an index n. n θ is a well-known diffusion coefficient for quantitatively expressing the diffusion characteristics of an optical material or optical component having diffusivity and representing the state of light diffused by the optical material or optical component. n is a natural number. When the index n is relatively large, it means that the diffusion force is relatively small, for example, it means that the spacing between the convex and concave parts of the concavo-convex structure formed on the diffusion surface 121 is relatively large, or close to the wavelength of the reference of the incident white light WL.

[0078] In this simulation, the temporal change of the concavo-convex structure due to the rotation of the substrate 110A, that is, the cosine constants of the four concavo-convex structures 131, 132, 133, and 134, are not considered. n The difference in exponent n in θ.

[0079] <Numerical Calculation Example 1>

[0080] Figure 5 1 is a diagram showing the result of calculating the light distribution on the incident surface of the plurality of micro lenses 54 of the multi-lens array 51 in the conventional lighting device in the structure of the lighting device 2 of the present embodiment without the second diffusion device 100 in the present simulation. Figure 5 As shown, in a conventional lighting device without the second diffusion device 100, the light of the white light WL is concentrated at the center of the incident surface of each of the plurality of microlenses 54 of the multi-lens array 51. In numerical calculation example 1, the high-density region where the light of the white light WL is concentrated at a higher density than the surroundings is not concentrated at one point at the center of the incident surface of each of the plurality of microlenses 54, but has a predetermined width. The high-density region is caused by the first light source 20R, the second light source 20G, and the third light source 20B having sizes respectively. The light-emitting surfaces of the first light source 20R, the second light source 20G, and the third light source 20B form a light spot image on the incident surface 41a of the substrate 41 of the first diffusion device 40. The light spot image is formed on the incident surface of the plurality of microlenses 54 that are in a conjugate relationship with the incident surface 41a.

[0081] <Numerical Calculation Example 2>

[0082] Figure 6 This is a diagram showing the result of calculating the light distribution on the incident surface of the plurality of microlenses 54 of the multi-lens array 51 in the numerical calculation example 2 of the present simulation when the diffusion state of the white light WL in the concavo-convex structure 131 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 in the structure of the present embodiment is set to an index n=100000. Figure 6 As shown, in the lighting device 2 of the present embodiment and the numerical calculation example 2, the white light WL is diffused by, for example, the concavo-convex structure 131 formed on the incident surface 110a and the diffusion surface 121 of the substrate 110A of the second diffusion device 100. Therefore, the high-density area where the light of the white light WL is concentrated more densely than the surrounding area is not concentrated at one point in the center of the incident surface of each of the multiple microlenses 54. The width of the high-density area in the numerical calculation example 2 is larger than the width of the high-density area in the numerical calculation example 1. The width of the high-density area in the numerical calculation example 2 depends on the diffusion characteristics of the concavo-convex structure 131, the diffusion state of the white light WL diffused by the concavo-convex structure 131, and the index n. According to the results of the numerical calculation example 2, it is also quantitatively confirmed that in the lighting device 2 of the present embodiment, the white light WL incident on the multi-lens array 51 is more diffused within the incident surface of each of the multiple microlenses 54 compared with the previous lighting device.

[0083] <Numerical Calculation Example 3-Numerical Calculation Example 7>

[0084] Figures 7 to 11 The figures respectively show the results of calculating the diffusion state of the white light WL in the concavo-convex structure 131 of the diffusion surface 121 of the substrate 110A of the second diffusion device 100 formed in the structure of the lighting device 2 of the present embodiment in the numerical calculation examples 3 to 7 of the present simulation, when the index n is set to numerical calculation example 3: index n=50000, numerical calculation example 4: index n=25000, numerical calculation example 5: index n=10000, numerical calculation example 6: index n=5000, and numerical calculation example 7: index n=2500. Figures 7 to 11As shown, in the lighting device 2 of the present embodiment and numerical calculation examples 3 to 7, the white light WL is diffused by the concavo-convex structure 131, for example, as in numerical calculation example 2. From numerical calculation example 3 to numerical calculation example 7, as the index n decreases, the width of the high-density area where the light of the white light WL at the incident surface of each of the multiple microlenses 54 is concentrated more densely than the surrounding area expands, and the peak value of the density distribution of the white light WL decreases. Based on the results of numerical calculation examples 3 to 7, it is quantitatively confirmed that: in the lighting device 2 of the present embodiment, compared with the previous lighting device, the white light WL incident on the multi-lens array 51 is more diffused in the incident surface of each of the multiple microlenses 54, and as the index n decreases, the beam width of the white light WL expands, and the peak intensity of the white light WL decreases. In the lighting device 2 of the present embodiment, the white light WL incident on the multi-lens array 51 of the integrator optical system 50 is well diffused by any of the concavo-convex structures 131, 132, 133, and 134 of the diffusion surface 121 of the substrate 110A of the second diffusion device 100 before being diffused by the concavo-convex structure 47 of the diffusion surface 45 of the substrate 41 of the first diffusion device 40. When the index n is, for example, 2500 or more, the white light WL in a focused state converges inside each of the plurality of microlenses 54, thereby suppressing a decrease in the utilization efficiency of the white light WL. In addition, the polarization characteristics of the respective colored lights of the red light RL incident on the light modulator 4R, the green light GL incident on the light modulator 4G, and the blue light BL incident on the light modulator 4B are easily disturbed.

[0085] <Numerical Calculation Example 8>

[0086] Fig.12 This is a diagram showing the result of calculating the light distribution on the incident surface of the plurality of microlenses 54 of the multi-lens array 51 in numerical calculation example 8 of the present simulation when the diffusion state of the white light WL in the concavo-convex structure 131 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 in the structure of the present embodiment is set to index n=1000. Fig.12As shown, in the lighting device 2 and numerical calculation example 8 of the present embodiment, the white light WL is diffused by the concave-convex structure 131, for example, as in each of the numerical calculation examples 2 to 7. However, in numerical calculation example 8, the white light WL incident on the multi-lens array 51 is not converged within the incident surface of each of the plurality of microlenses 54, but diffused to the incident surface adjacent to the incident surface of each of the plurality of microlenses 54. This indicates the following state: when the index n of the diffusion state of the white light WL in the concave-convex structure 131 is reduced to 1000, the light of each of the plurality of microlenses 54 incident on the multi-lens array 51 is also incident on the adjacent microlens 54. In this case, in the projector 1 of the present embodiment, the utilization efficiency of the white light WL emitted from the lighting device 2 is reduced according to the amount of white light WL that expands outwards more than the plurality of microlenses 54. Furthermore, the polarization characteristics of the red light RL incident on the light modulator 4R, the green light GL incident on the light modulator 4G, and the blue light BL incident on the light modulator 4B are easily disturbed.

[0087] <Summary of Numerical Calculation Examples>

[0088] According to the results of numerical calculation examples 1 to 8 of the present simulation, the diffusion state of the white light WL in the concavo-convex structures 131, 132, 133, and 134 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 is designed to be a non-diffusion state in which the white light WL does not diffuse on the incident surface 110a of the substrate 110A, like a flat surface without any convex or concave portions, or a diffusion state in which at least the small beams of the white light WL do not enter the incident surface of the microlens 54 adjacent to the incident surface of each microlens 54 in the multi-lens array 51. The diffusion state of the white light WL in the concavo-convex structures 131, 132, 133, and 134 is preferably a diffusion state in which the index n is greater than 1000, and preferably a diffusion state in which the index n is greater than 2500 and less than 100000.

[0089] The lighting device 2 of the present embodiment described above has at least the first light source 20R and the second light source 20G, and also has the third light source 20B. The lighting device 2 of the present embodiment has a light synthesis component 24, a first diffusion device 40, a focusing element 25, a collimating element 26, and a second diffusion device 100. The first light source 20R emits red light (first light) LR having a first wavelength. The second light source 20G emits green light (second light) LG having a second wavelength different from the first wavelength. The light synthesis component 24 synthesizes the red light LR and the green light GL and emits white light (synthesized light) WL. The first diffusion device 40 has: a substrate (first substrate) 41 having a diffusion surface (first diffusion surface) 45 that diffuses and emits the incident white light WL; and a drive device (first drive device) 42 that rotates the substrate 41. The focusing element 25 is disposed between the light combining component 24 and the first diffuser 40, and focuses the white light WL on the diffuser surface 45 of the substrate 41 of the first diffuser 40. The collimating element 26 collimates the white light WL emitted from the substrate 41 of the first diffuser 40. The second diffuser 100 is disposed between the focusing element 25 and the first diffuser 40, and changes the state of the focusing point (light spot) SP of the white light WL on the diffuser surface 45 with the passage of time.

[0090] As a conventional lighting device, there is a configuration in which the second diffuser 100 is not provided between the light collecting element 25 and the first diffuser 40. In the lighting device 2 of the present embodiment, the white light WL irradiated onto the diffuser surface 45 of the substrate 41 of the first diffuser 40 is diffused by any of the concavo-convex structures 131, 132, 133, and 134 formed on the diffuser surface 121 of the substrate 110A of the second diffuser 100. According to the lighting device 2 of the present embodiment, the white light WL with further reduced speckle noise is incident on the integrator optical system 50 disposed at a later stage than the first diffuser 40, that is, disposed on the side where the white light WL is projected, compared with the conventional lighting device not including the second diffuser 100. Therefore, according to the lighting device 2 of the present embodiment, when the white light WL emitted from the lighting device 2 is projected, the speckle noise generated in the projected image can be reduced favorably.

[0091] As a conventional lighting device, there is another structure of a diffusion device having a concavo-convex structure of the diffusion surface between the focusing element 25 and the first diffusion device 40 or a diffusion surface in which the diffusion state of the white light WL does not change with time. In this structure, the speckle pattern of the light-converging point SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 does not change with time. According to the lighting device 2 of the present embodiment, the white light WL with reduced speckle noise in time and at a high speed is incident on the integrator optical system 50 arranged at a stage later than the first diffusion device 40, as compared with the conventional lighting device not having the second diffusion device 100. Therefore, according to the lighting device 2 of the present embodiment, when the white light WL emitted from the lighting device 2 is projected, the speckle noise generated in the projected image can be more effectively reduced.

[0092] In the lighting device 2 of the present embodiment, the second diffusion device 100 has a substrate (second substrate) 110A and a driving device (second driving device) 111. The substrate 110A diffuses and transmits the incident white light WL. The driving device 111 rotates the substrate 110A in the rotation direction DS. The substrate 110A has a diffusion surface 121 that diffuses and transmits the incident white light WL. The diffusion surface 121 has at least a plurality of concave-convex structures along the rotation direction DS, for example, a first region R1 having a concave-convex structure (first concave-convex structure) 131, and a second region R2 having a concave-convex structure (second concave-convex structure) 132 different from the concave-convex structure 131.

[0093] In the lighting device 2 of the present embodiment, when the substrate 110A is rotated in the rotation direction DS by the driving device 111, the first region R1 and the second region R2 irradiated by the white light WL incident on the diffusion surface 121 are switched in time, and the concavo-convex structures 131 and 132 on which the white light WL is incident are switched in time. Therefore, the diffusion, scattering or diffraction pattern and the speckle pattern at the focal point SP of the white light WL formed on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 can be changed with time. According to the lighting device 2 of the present embodiment, the white light WL with reduced speckle noise is made incident on the integrator optical system 50 in time and at a high speed, and the speckle noise generated in the projected image based on the white light WL can be more effectively reduced.

[0094] In the lighting device 2 of the present embodiment, the frequency at which the state of the focusing point SP on the diffusion surface 45 of the first diffusion device 40 changes due to the rotation of the substrate 110A of the second diffusion device 100 is 60 [Hz] or more.

[0095] In the lighting device 2 of the present embodiment, the diffusion surface 121 of the substrate 110A of the second diffusion device 100 has, for example, the first region R1, the second region R2, the third region R3, and the fourth region R4. In the lighting device 2 of the present embodiment, the first region R1, the second region R2, the third region R3, and the fourth region R4 on which the white light WL is incident on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 are switched discontinuously at a frequency of 60 [Hz] or more. Accordingly, the diffusion, scattering, or diffraction pattern and the speckle pattern of the focal point SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 are switched discontinuously at a frequency of 60 Hz or more. According to the lighting device 2 of the present embodiment, it is difficult for an observer of the projected image based on the white light WL to recognize the flickering and flickering of the image caused by the speckle noise.

[0096] In the lighting device 2 of the present embodiment, the number of regions of the diffusion surface 121 of the substrate 110A of the second diffusion device 100 is not limited to 4, but is an arbitrary natural number m greater than 2. For example, it is assumed that the region where the different concave-convex structures are formed on the diffusion surface 121 is divided into m equal parts in the rotation direction DS, and the diffusion, scattering or diffraction pattern and the speckle pattern of the focal point SP of the white light WL incident on the diffusion surface 45 are switched at a frequency greater than ct [Hz]. In this case, the rotation speed of the driving device 111 can be set to 1 / (ct×m) [revolutions / second] or greater. As described above, the frequency ct [Hz] can be adjusted so that m is a natural number.

[0097] The projector 1 of this embodiment includes the above-mentioned lighting device 2, light modulators 4R, 4G, 4B, and a projection optical system 6. The light modulator 4R modulates the red light RL included in the white light WL emitted from the lighting device 2 to generate red image light. The light modulator 4G modulates the green light GL included in the white light WL to generate green image light. The light modulator 4B modulates the blue light BL included in the white light WL to generate blue image light. The projection optical system 6 projects the image light modulated by the light modulators 4R, 4G, 4B.

[0098] In the projector 1 of the present embodiment, the illumination device 2 has a second diffusion device 100 in addition to the first diffusion device 40. According to the projector 1 of the present embodiment, when the white light WL emitted from the illumination device 2 is converted into image light by the light modulators 4R, 4G, 4B and the image light is projected onto the screen SCR, speckle noise generated in the projected image can be well reduced.

[0099] Next, refer to Figures 13 to 15Modifications of the substrate 110A of the second diffuser 100 in the lighting device 2 of the present embodiment will be described. In the description of each modification, the same contents as those of the already described modification will be omitted, and the configurations and contents different from those of the already described modification will be described.

[0100] [First Modification]

[0101] Fig.13 1 is a schematic diagram of a substrate 110B of a first modified example of the second diffusion device 100, and is a diagram of the substrate 110B viewed from the incident surface 110a side along the rotation axis OX2. In the first modified example, one of the first region R1, the second region R2, the third region R3, and the fourth region R4 of the diffusion surface 121 of the substrate 110A of the second diffusion device 100 of the above-mentioned embodiment may be a non-diffusion surface 141. The substrate 110B is a first modified example of the substrate 110A. Fig.13 In the substrate 110B shown, a non-diffusing surface 141 is provided in the second region R2. The non-diffusing surface 141 transmits the incident white light WL without diffusion. The non-diffusing surface 141 is, for example, a flat surface 140 on which no concavo-convex structure is formed.

[0102] In the first variant of the lighting device 2 of the present embodiment, the second diffusion device 100 has a substrate 110B and a driving device (second driving device) 111. The substrate 110B diffuses and transmits the incident white light WL. The driving device 111 rotates the substrate 110B in the rotation direction DS. The substrate 110B has: a diffusion surface 121, which diffuses and transmits the incident white light WL; and a non-diffusion surface 141, which is arranged at a different position from the diffusion surface 121 in the rotation direction DS and transmits the white light WL. The diffusion surface 121 has at least one concavo-convex structure along the rotation direction DS, for example, a first region R1 provided with a concavo-convex structure 131. The diffusion surface 121 of the substrate 110B has a third region R3 provided with a concavo-convex structure 133 different from the concavo-convex structure 131 and a fourth region R4 provided with a concavo-convex structure 134 different from the concavo-convex structure 131. The non-diffusion surface 141 has a flat second region R2 that does not diffuse the white light WL.

[0103] In the first modified example of the illumination device 2 of the present embodiment, when the substrate 110B is rotated in the rotation direction DS by the driving device 111, the first region R1 and the second region R2 irradiated by the white light WL incident on the diffusion surface 121 are switched in time, and the concavo-convex structure 131 of the first region R1 and the flat surface 140 of the second region R2 on which the white light WL is incident are switched in time. Therefore, as in the case of the substrate 110A, the diffusion, scattering or diffraction pattern and the speckle pattern at the light-convex point SP of the white light WL formed on the diffusion surface 45 of the substrate 41 of the first diffuser 40 can be changed with time. According to the first modified example of the illumination device 2 of the present embodiment, the white light WL with reduced speckle noise is made incident on the integrator optical system 50 in time and at a high speed, and the speckle noise generated in the projected image based on the white light WL can be reduced more effectively.

[0104] In addition, as another modification example of the substrate 110B not shown in the figure, for example, the non-diffusion surface 141 may be provided in any one of the first region R1, the third region R3, and the fourth region R4, and the concavo-convex structure 132 may be provided in the second region R2. As another modification example of the substrate 110B not shown in the figure, when viewed along the rotation axis OX2, the diffusion surface 121 and the concavo-convex structure may be provided in two regions of the first region R1, the third region R3, and the fourth region R4 that are arranged on opposite sides of the rotation axis OX2, and the flat surface 140 may be provided as the non-diffusion surface 141 in the remaining two regions.

[0105] As another modification of the substrate 110B not shown, the following substrate can be cited: the number of regions divided in the rotation direction DS of the substrate is 2 or more and not 4, and the diffusion states of the diffused white light WL in the regions adjacent to each other in the rotation direction DS are different from each other. In such a substrate, a non-diffusing surface 141 is provided in at least one region among the plurality of regions. When the number of regions divided by the rotation direction DS is 5 or more, the non-diffusing surface 141 may be provided in more than two regions, and the non-diffusing surface 141 provided between the two regions in the rotation direction DS may be provided in more than one region.

[0106] [Second Modification]

[0107] Fig.14It is a schematic diagram of a substrate 110C of a second modified example of the second diffusion device 100, and is a diagram of the substrate 110C observed from the incident surface 110a side along the rotation axis OX2. In the second modified example, the incident surface 110a and the diffusion surface 121 of the substrate 110C of the second diffusion device 100 are not divided into a plurality of regions in the rotation direction DS, and only have the first region R1. The substrate 110C is a second modified example of the substrate 110A. The angle θ1 of the first region R1 is 360°. A concave-convex structure 135 is formed in the first region R1 of the substrate 110C. In the concave-convex structure 135, the diffusion state of the incident white light WL changes continuously along the rotation direction DS. In the concave-convex structure 135, for example, the height of the convex portion and the concave portion and the spacing between the convex portion and the concave portion change continuously along the rotation direction DS.

[0108] In the second modified example of the lighting device 2 of the present embodiment, the diffusion surface 121 of the substrate 110C of the second diffuser 100 has only the first region R1. In the second modified example, in the first region R1 on which the white light WL is incident on the diffusion surface 121 of the substrate 110C of the second diffuser 100, the diffusion state of the diffused white light WL based on the concavo-convex structure changes continuously along the rotation direction DS every rotation. Accordingly, the diffusion, scattering or diffraction pattern and speckle pattern of the light-convex point SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffuser 40 are continuously switched every rotation of the substrate 110C. According to the second modified example of the lighting device 2 of the present embodiment, the same effect as the case where the second diffuser 100 includes the substrates 110A and 110B can be obtained.

[0109] [Third Modification]

[0110] Fig.15 FIG. 1 is a schematic diagram of a substrate 110D of a third modified example of the second diffusion device 100, and is a diagram of the substrate 110D viewed from the incident surface 110a side along the rotation axis OX2. Fig.15 As shown, the substrate 110D of the third modification example has a concavo-convex structure 135 instead of the concavo-convex structure 133 in the third region R3 of the substrate 110B of the first modification example. The substrate 110D is a third modification example of the substrate 110A. The incident surface 110a of the substrate 110D may also have a diffusion surface 121 that discontinuously changes the diffusion state of the white light WL in the rotation direction DS, a diffusion surface 121 that continuously changes the diffusion state, and a non-diffusion surface 141 that does not diffuse the white light WL. According to the third modification example of the lighting device 2 of the present embodiment, the same effect as the case where the second diffusion device 100 includes the substrates 110A, 110B, and 110C can be obtained.

[0111] As mentioned above, although the preferred embodiment of the present invention is described in detail, the present invention is not limited to this specific embodiment, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0112] For example, the shape, number, arrangement, and material of each component of the lighting device and the projector are not limited to those described in the above-mentioned embodiment and modified examples, and may be modified as appropriate.

[0113] In the above-mentioned embodiment, as the lighting device of the present invention, an example of a reflective diffuser as the first diffuser is shown, but the present invention is not limited to this example. For example, the lighting device of the present invention may also have a transmissive diffuser as the first diffuser. In this case, a reflective film is not provided on the substrate of the first diffuser. The synthetic light diffused by the diffusion surface of the substrate of the first diffuser and transmitted through the substrate is emitted from the emission surface of the substrate along an optical axis that is in a straight line with the optical axis of the synthetic light incident on the substrate. In addition, in the above-mentioned embodiment, the first diffuser is a reflective diffuser, and therefore, compared with the case of a transmissive diffuser, the polarization disorder of the synthetic light emitted from the first diffuser is less.

[0114] In the above-mentioned embodiment, as the lighting device of the present invention, an example is shown in which the diffusion surface of the second diffusion device is constituted by the incident surface of the substrate provided by the second diffusion device, but the present invention is not limited to this example. For example, the diffusion surface of the second diffusion device may be constituted by the emission surface of the substrate of the second diffusion device, or may be constituted by both the incident surface and the emission surface of the substrate of the second diffusion device.

[0115] In the above-mentioned embodiment, an example of the lighting device of the present invention being mounted on a projector using a liquid crystal panel is shown, but the present invention is not limited to this example. For example, the lighting device of the present invention can also be applied to a projector using a digital micromirror device as a light modulator. The projector of the present invention may not have a plurality of light modulators, but may be a single-panel projector having only one light modulator.

[0116] [Summary of the present disclosure]

[0117] The following is a summary of the present disclosure.

[0118] (Supplementary Note 1) A lighting device, comprising: a first light source that emits a first light of a first wavelength; a second light source that emits a second light of a second wavelength different from the first wavelength; a photosynthetic component that synthesizes the first light and the second light to emit synthesized light; a first diffusion device that has a first substrate and a first driving device, the first substrate having a first diffusion surface that diffuses and emits the incident synthesized light, and the first driving device rotates the first substrate; a focusing element that is arranged between the photosynthetic component and the first diffusion device and focuses the synthesized light on the first diffusion surface of the first diffusion device; a collimating element that parallelizes the synthesized light emitted from the first diffusion device; and a second diffusion device that is arranged between the focusing element and the first diffusion device and causes the state of the light spot of the synthesized light on the first diffusion surface to change with the passage of time.

[0119] According to the structure of Supplementary Note 1, compared with a structure without the second diffuser or a structure in which the diffusion state of the incident synthetic light is not changed with time as the second diffuser, the synthetic light with reduced speckle noise can be made incident on the optical system at the stage after the first diffuser. Therefore, according to the structure of Supplementary Note 1, when the synthetic light emitted from the illumination device is projected, the speckle noise generated in the projected image can be well reduced.

[0120] (Note 2) According to the lighting device described in Note 1, the second diffusion device comprises: a second substrate that diffuses and emits the incident synthetic light; and a second driving device that rotates the second substrate, the second substrate having a second diffusion surface that diffuses and transmits the incident synthetic light, and the second diffusion surface having: a first area that has a first concave-convex structure; and a second area that has a second concave-convex structure different from the first concave-convex structure.

[0121] According to the structure of Supplementary Note 2, when the second substrate is rotated by the second driving device, the first area and the second area irradiated by the synthesized light incident on the second diffusion surface are switched in time, and the diffusion surface on which the synthesized light is incident is switched in time. Therefore, the diffusion, scattering or diffraction pattern and the speckle pattern in the light spot of the synthesized light formed on the first diffusion surface can be changed with the passage of time.

[0122] (Supplementary Note 3) The lighting device according to Supplementary Note 1, wherein the second diffusion device comprises: a second substrate, which diffuses and emits the incident synthetic light; and a second driving device, which rotates the second substrate, the second substrate comprising: a second diffusion surface, which diffuses and transmits the incident synthetic light; and a non-diffusing surface, which is arranged at a position different from the second diffusion surface and transmits the synthetic light, the second diffusion surface having a first area provided with a concave-convex structure, and the non-diffusing surface having a flat second area that does not diffuse the synthetic light.

[0123] According to the configuration of Supplementary Note 3, when the second substrate is rotated by the second driving device, the first area and the second area irradiated by the synthesized light incident on the second diffusion surface are switched in time, and the diffusion surface and the non-diffusion surface on which the synthesized light is incident are switched in time. Therefore, the diffusion, scattering or diffraction pattern and the speckle pattern in the light spot of the synthesized light formed on the first diffusion surface can be changed with the passage of time.

[0124] (Note 4) An illumination device according to any one of Notes 1 to 3, wherein the frequency at which the state of the light spots on the first diffusion surface of the first diffusion device changes by rotating the second substrate in the second diffusion device that diffuses and emits the incident synthetic light is greater than 60 Hz.

[0125] According to the structure of Supplementary Note 4, the diffusion, scattering or diffraction pattern and the speckle pattern of the light spot of the synthetic light incident on the first diffusion surface are switched discontinuously at a frequency of 60 Hz or more. According to the structure of Supplementary Note 4, an observer of the projected image based on the synthetic light can not recognize the flickering and flickering of the image caused by the speckle noise.

[0126] (Supplement 5) A projector comprising: an illumination device according to any one of Supplements 1 to 4; a light modulating device for modulating light emitted from the illumination device; and a projection optical system for projecting light modulated by the light modulating device.

[0127] According to the configuration of Supplementary Note 5, when the synthesized light emitted from the illumination device is converted into image light by the light modulating device and the image light is projected, speckle noise generated in the projected image can be reduced favorably.

Claims

1. A lighting device comprising: a first light source emitting a first light having a first wavelength; a second light source that emits a second light having a second wavelength different from the first wavelength; a light combining member for combining the first light and the second light to emit combined light; a first diffusion device comprising: a first substrate having a first diffusion surface for diffusing and emitting the incident synthetic light; and a first driving device for rotating the first substrate; a light-condensing element disposed between the light-combining component and the first diffusion device, and converging the synthesized light onto the first diffusion surface of the first diffusion device; a collimating element for collimating the synthesized light emitted from the first diffusion device; as well as The second diffusion device is disposed between the light-collecting element and the first diffusion device, and changes the state of the light spot of the synthesized light on the first diffusion surface with the passage of time.

2. The lighting device according to claim 1, wherein: The second diffusion device comprises: a second substrate which diffuses the incident synthetic light and emits it; and a second driving device that rotates the second substrate, The second substrate has a second diffusion surface for diffusing and transmitting the incident synthetic light. The second diffusion surface includes a first region provided with a first concavo-convex structure and a second region provided with a second concavo-convex structure different from the first concavo-convex structure.

3. The lighting device according to claim 1, wherein: The second diffusion device comprises: a second substrate which diffuses the incident synthetic light and emits it; and a second driving device that rotates the second substrate, The second substrate has: a second diffusion surface that diffuses and transmits the incident synthetic light; and a non-diffusion surface that is arranged at a position different from the second diffusion surface and transmits the synthetic light. The second diffusion surface has a first region provided with a concavo-convex structure, The non-diffusion surface has a flat second region that does not diffuse the synthetic light.

4. The lighting device according to any one of claims 1 to 3, wherein: By rotating the second substrate of the second diffusion device that diffuses and emits the incident synthetic light, the frequency at which the state of the light spot on the first diffusion surface of the first diffusion device changes is 60 Hz or more.

5. A projector comprising: The lighting device according to any one of claims 1 to 4; a light modulation device for modulating light emitted from the illumination device; and A projection optical system projects the light modulated by the light modulation device.

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