Illumination device and projector

Abstract

To reduce speckle noise in a projection image in a projector including an illumination device.SOLUTION: A illumination device includes: 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 with each other and emits combined light; a first diffusion device including a first substrate having a first diffusion surface on which the combined light is diffused and emitted, and a first driving device that rotates the first substrate; a light collecting element that is disposed between the light combining member and the first diffusion device and collects the combined light at the 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 temporally changes a state of a spot of the combined light at the first diffusion surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] 2. Description of the Related Art In recent years, in order to improve the performance of projectors, lighting devices equipped with laser light sources that are light sources with a wide color gamut and high efficiency, and projectors equipped with such lighting devices have been proposed.

[0003] For example, in the projector disclosed in Patent Document 1, three color lights emitted from a red light source array having a laser light source that emits red light, a green light source array having a laser light source that emits green light, and a blue light source array having a laser light source that emits blue light are mixed by a color mixing optical system, and the mixed light enters a condenser lens and is collected toward a diffuser plate. In the projector disclosed in Patent Document 1, the collected mixed light passes through the diffuser plate, thereby reducing speckle noise that occurs in the projected image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-078906 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the projector disclosed in Patent Document 1, simply irradiating the composite light focused by a focusing lens onto a diffuser plate and emitting the diffused composite light from the diffuser plate does not sufficiently reduce speckle noise, and improvements were desired. [Means for solving the problem]

[0006] An illumination device according to one embodiment of the present invention includes a first diffusing device having 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 light combining member that combines the first light and the second light to emit the combined light, a first substrate having a first diffusing surface that diffuses and emits the incident combined light, and a first drive device that rotates the first substrate, a focusing element that is disposed between the light combining member and the first diffusing device and focuses the combined light on the first diffusing surface of the first diffusing device, a collimating element that collimates the combined light emitted from the first diffusing device, and a second diffusing device that is disposed between the focusing element and the first diffusing device and changes the state of the spot of the combined light on the first diffusing surface over time. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration of a projector according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of an illumination device of the projector of FIG. [Diagram 3] 3 is a schematic view of a substrate of a first diffusing device of the lighting device of FIG. 2, viewed along an axis of rotation. [Figure 4] 3 is a schematic view of a substrate of a second diffusing device of the lighting device of FIG. 2 viewed along an axis of rotation. [Diagram 5] FIG. 3 is a light distribution diagram of a first example of numerical calculation regarding the lighting device of FIG. 2. [Figure 6] FIG. 3 is a light distribution diagram of a second example of numerical calculation regarding the lighting device of FIG. 2. [Figure 7] FIG. 3 is a light distribution diagram of a third example of numerical calculation regarding the lighting device of FIG. 2. [Figure 8] FIG. 3 is a light distribution diagram of a fourth numerical calculation example regarding the lighting device of FIG. 2. [Figure 9] FIG. 3 is a ray distribution diagram of a fifth numerical calculation example regarding the lighting device of FIG. 2. [Figure 10] FIG. 3 is a light distribution diagram of a sixth numerical calculation example regarding the lighting device of FIG. 2. [Figure 11] FIG. 3 is a light distribution diagram of Numerical Calculation Example 7 regarding the lighting device of FIG. 2. [Figure 12] FIG. 3 is a light distribution diagram of Numerical Calculation Example 8 regarding the lighting device of FIG. 2. [Figure 13] 3 is a schematic diagram of a substrate of a first variant of the first diffusion device of the lighting device of FIG. 2; FIG. [Figure 14] 3 is a schematic diagram of a substrate of a second variant of the first diffusion device of the lighting device of FIG. 2; FIG. [Figure 15] 3 is a schematic diagram of a substrate of a third variant of the first diffusion device of the lighting device of FIG. 2; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the scale of the dimensions of some components may be changed in order to make each component easier to see.

[0009] First, a projector according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the configuration 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, and 4B, a color synthesis optical system 5, and a projection optical system 6. The projector 1 is a three-plate type projector having three light modulation devices.

[0010] 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 contains red light RL, green light GL, and blue light BL. The configuration of the illumination device 2 will be described later.

[0011] 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.

[0012] The first dichroic mirror 11 is disposed 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 blue light BL. The second dichroic mirror 12 is disposed on the common optical path of the green light GL and blue light BL emitted from the first dichroic mirror 11, and separates the green light GL from the blue light BL. The second dichroic mirror 12 transmits the blue light BL and reflects the green light GL.

[0013] The first total reflection mirror 13 reflects the red light RL toward the light modulation device 4R. The second total reflection mirror 14 and the third total reflection mirror 15 guide the blue light BL to the light modulation device 4B. The green light GL is reflected from the second dichroic mirror 12 toward the light modulation device 4G. The red light RL, green light GL, and blue light BL contained in the white light WL correspond to the light emitted from the illumination device 2.

[0014] The first relay lens 16 is disposed 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 disposed on the optical path of the blue light BL between the second total reflection mirror 14 and the third total reflection mirror 15. By disposing the first relay lens 16 and the second relay lens 17 as described above, the optical loss of the blue light BL is compensated. The optical loss of the blue light BL is caused by the optical path length of the blue light BL from the first dichroic mirror 11 to the optical modulation device 4B being longer than the optical path length of the red light RL from the first dichroic mirror 11 to the optical modulation device 4R and the optical path length of the green light GL from the first dichroic mirror 11 to the optical modulation device 4G.

[0015] The light modulation device 4R is disposed 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 modulation device 4R modulates the incident red light RL according to image information input from an image input device (not shown), forms red image light, and emits the red image light. The light modulation device 4G is disposed 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 modulation device 4G modulates the incident green light GL according to image information input from an image input device (not shown), forms green image light, and emits the green image light. The light modulation device 4B is disposed 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 modulation device 4B modulates the incident blue light BL according to image information input from an image input device (not shown), forms blue image light, and emits blue image light. The image input device may be, for example, a personal computer or a portable terminal device.

[0016] Each of the light modulation devices 4R, 4G, and 4B uses, for example, a transmissive liquid crystal panel. A polarizing plate (not shown) is disposed on each of the entrance side and exit 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 modulation device 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 modulation device 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 modulation device 4B.

[0017] The color synthesis optical system 5 is disposed across the optical path of the red image light emitted from the light modulation device 4R, the optical path of the green image light emitted from the light modulation device 4G, and the optical path of the blue image light emitted from the light modulation device 4B. When viewed from the top or side as shown in FIG. 1, the synthesis position of the color 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 with each other to form color image light. The color synthesis optical system 5 emits color image light. For example, a cross dichroic prism is used for the color synthesis optical system 5.

[0018] The projection optical system 6 is disposed on the optical path of the color image light emitted from the color synthesis optical system 5. The color image light emitted from the color synthesis optical system 5 corresponds to the light modulated by the light modulation devices 4R, 4G, and 4B. The projection optical system 6 enlarges and projects the color image light emitted from and incident on the color synthesis optical system 5 toward the screen SCR. The color image light enlarged and projected from the projection optical system 6 is displayed as a color image on a display surface of the screen SCR facing the emission surface of the projection optical system 6.

[0019] The projection optical system 6 is composed of, for example, a plurality of optical lenses, but may be composed of a single optical lens. The optical lens includes various lenses such as a plano-convex lens, a biconvex lens, a meniscus lens, an aspheric lens, a rod lens, and a free curved lens.

[0020] Next, an illumination device according to an embodiment of the present invention will be described with reference to Fig. 2 to Fig. 4. Fig. 2 is a schematic diagram showing a configuration 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 light combining member 24, a condensing element 25, a first diffusion device 40, a second diffusion device 100, a collimating element 26, and an integrated optical system 50.

[0021] The first light source 20R has a first laser element 21R and a first collimator lens 22R, and emits red light LR. The first laser element 21R emits red light LR. The red light LR has a wavelength band including wavelengths belonging to red in the visible wavelength band, for example, a wavelength band of 585 nm to 720 nm. The red light LR is emitted from the first laser element 21R radially about the optical axis AX1. The red light LR corresponds to the first light. The wavelength belonging to red included in the red light LR corresponds to the first wavelength.

[0022] 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 with the optical axis AX1. The first collimator lens 22R collimates the incident red light LR.

[0023] The second light source 20G has 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 wavelengths 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 wavelengths belonging to green that are included in the green light LG correspond to the second wavelength.

[0024] The green light LG is emitted from the second laser element 21G radially about an optical axis AX2. When viewed from the top or side as shown in FIG. 2, the optical axis AX2 from the second laser element 21G to a color light combining position in the light combining member 24, which will be described later, is perpendicular to the optical axis AX1 from the first laser element 21R to the color light combining position in the light combining member 24.

[0025] 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 with the optical axis AX2. The second collimator lens 22G collimates the incident green light LG.

[0026] The third light source 20B has a third laser element 21B and a third collimator lens 22B, and emits blue light LB. The third laser element 21B emits blue light LB. The blue light LB has a wavelength band including wavelengths belonging to blue in the visible wavelength band, for example, a wavelength band of 380 nm to 495 nm. 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 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 light combining member 24 so as to pass through the combining position of the colored lights in the light combining member 24, and is further extended in the opposite direction to the first light source 20R with respect to the light combining member 24. The blue light LB is emitted parallel to the red light LR and in the opposite direction to the light combining member 24.

[0027] 2, each of the first light source 20R, the second light source 20G, and the third light source 20B includes 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, each of the first light source 20R, the second light source 20G, and the third light source 20B may include two or more laser light sources and the same number of collimating lenses as the number of the laser light sources. Each of the first light source 20R, the second light source 20G, and the third light source 20B may include components other than the laser light source and the collimating lens, such as a package that holds the laser light source and the collimating lens.

[0028] The light combining member 24 is disposed across 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. When viewed from the top or side as shown in Fig. 2, the combining position of the colored lights in the light combining member 24 overlaps with the intersection of the optical path of the red light LR, the optical path of the green light LG, and the optical path of the blue light LB, i.e., the intersection of the optical axis AX1 and the optical axis AX2.

[0029] In the light combining member 24, the incident red light LR, green light LG, and blue light LB are combined together to generate white light WL. The white light WL corresponds to the combined light. The light combining member 24 emits the white light WL along the optical axis AX2. The optical axis AX2 of the white light WL is collinear with 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 combining member 24 so as to pass through the combination position of the colored lights in the light combining member 24, and is further extended in the opposite direction to the second light source 20G with respect to the light combining member 24.

[0030] For example, a cross dichroic prism 240 is used for the light combining member 24. The cross dichroic prism 240 has a first dichroic mirror 241 and a second dichroic mirror 242. In a plan view or a side view in which the optical axes AX1 and AX2 are perpendicular to each other, the reflecting surface of the first dichroic mirror 241 and the reflecting surface of the second dichroic mirror 242 are inclined with respect to the optical axes AX1 and AX2. In a plan view or a side view, the angle formed by each of the reflecting surfaces of the first dichroic mirror 241 and the second dichroic mirror 242 and each of the optical axes AX1 and AX2 is 45°. In a plan view or a side view in which the optical axes AX1 and AX2 are perpendicular to each other, the reflecting surface of the first dichroic mirror 241 and the reflecting surface of the second dichroic mirror 242 are perpendicular to each other.

[0031] 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 enters the second dichroic mirror 242 along the optical axis AX1, is reflected by the second dichroic mirror 242, and is emitted along the optical axis AX2 to the opposite side to the second light source 20G and transmits through the first dichroic mirror 241. The green light LG emitted from the second light source 20G enters the first dichroic mirror 241 along the optical axis AX2, travels straight, and transmits through the first dichroic mirror 241 and the second dichroic mirror 242. The blue light LB emitted from the third light source 20B enters the first dichroic mirror 241 along the optical axis AX1, is reflected by the first dichroic mirror 241, and is emitted opposite the second light source 20G along the optical axis AX2, and passes through the second dichroic mirror 242.

[0032] As described above, the red light RL, the green light LG, and the blue light LB emitted from the first dichroic mirror 241 and the second dichroic mirror 242 are combined with each other to generate white light WL. The white light WL is emitted along the optical axis AX2 from the side surface of the cross dichroic prism 240 opposite to the side surface facing the second light source 20G.

[0033] The light collecting element 25 is disposed on the optical path of the white light WL between the light combining member 24 and the first diffusing device 40. The light collecting element 25 collects the white light WL emitted from the light combining member 24 and in a collimated state toward the first diffusing device 40. The center of the light collecting element 25 in a direction perpendicular to the optical axis AX2 substantially overlaps with the optical axis AX2. The light collecting element 25 is, for example, a biconvex lens, but may be an optical element having a light collecting function other than a biconvex lens, may be a plano-convex lens, or may be composed of a plurality of optical lenses.

[0034] The first diffusing device 40 is disposed on the optical path of the white light WL emitted from the converging element 25. The first diffusing device 40 diffuses and emits the incident white light WL while being collected by the converging element 25. The first diffusing device 40 is, for example, a reflective diffusing device, and diffuses and reflects the incident white light WL.

[0035] The first diffusion device 40 has, 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 has an incident surface 41a onto which the white light WL collected by the light collecting element 25 is irradiated to form a focused spot SP of the white light WL, and a back surface 41b on the opposite side to the incident surface 41a. The substrate 41 is disposed with the incident surface 41a facing the light collecting element 25. In a plan view or side view in which the optical axes AX1 and AX2 are perpendicular to each other, the angle between the incident surface 41a and the optical axis AX2 is 45°.

[0036] The substrate 41 is mounted on the driving device 42 in a state in which 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 an axis member 43 with the rotation axis OX1 as its axis. The axis member 43 is, for example, inserted into the center of the substrate 41 from the back surface 41b side. The centers of the incident surface 41a and the back surface 41b of the substrate 41 overlap with the rotation axis OX1. The substrate 41 rotates around the rotation axis OX1 as described above in conjunction with the rotation of the axis member 43 around the rotation axis OX1, and diffuses the white light WL. Note that the driving device 42 may be any device that can rotate the substrate 41 as described above, and is not limited to a motor.

[0037] FIG. 3 is a schematic diagram of the substrate 41 of the first diffusion device 40, and is a view of the substrate 41 viewed from the incident surface 41a side along the rotation axis OX1. As shown in FIG. 2 and FIG. 3, when viewed along the rotation axis OX1, the focused spot SP of the white light WL is formed in the region between the center, that is, the rotation axis OX1 and the peripheral end in the radial direction centered on 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 corresponds to the first diffusion surface. The incident surface 41a has an uneven structure 47 formed thereon. The uneven structure 47 is appropriately designed in consideration of the wavelength band of the white light WL so as to appropriately diffuse the white light WL, and is created in the same manner as the uneven structure formed on a known diffusion plate. The uneven structure 47 may be formed, for example, by blasting, or may be realized by forming a plurality of microlenses having a diameter equal to or smaller than the wavelength of the white light WL using a photolithography technique. The uneven structure 47 may be formed, for example, by scattering 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 so as to reflect the surface shape of the plurality of particles. Note that the uneven structure 47 may be formed over the entire radial range from the center to the peripheral edge of the incident surface 41a as shown in Fig. 3, but it is sufficient that the uneven structure 47 is formed over at least a portion of the radial range including the region irradiated with the focused spot SP.

[0038] When the substrate 41 is made of a material that is transparent to the white light WL, such as optical glass or plastic, a reflective film (not shown) is provided on the surface of the uneven structure 47. When the substrate 41 is made of a material that is reflective to the white light WL, such as a metal, a reflective film (not shown) does not need to be provided on the surface of the uneven structure 47, but providing a reflective film improves the reflection characteristics of the incident surface 41a. Note that in FIG. 3, the uneven structure 47 is illustrated by dots. The uneven structure 47 is made of a material that is transparent to the white light WL and does not have light blocking properties, like the substrate 41.

[0039] The speckle pattern of the white light WL at the focused spot SP changes as the substrate 41 of the first diffusion device 40 rotates in the rotation direction DR about the rotation axis OX1. The white light WL is diffused and reflected by the diffusion surface 45, includes a diffusion, scattering or diffraction pattern due to the uneven structure 47, and is emitted as diffused light from the focused spot SP along the optical axis AX10. The optical axis AX10 passes through the center of the irradiation area of ​​the focused spot SP on the entrance surface 41a of the substrate 41, and is parallel to the optical axis AX1.

[0040] 2, the second diffusion device 100 is disposed on the optical path of the white light WL between the concentrating element 25 and the first diffusion device 40. The second diffusion device 100 is disposed before the first diffusion device 40 in the traveling direction of the white light WL, and diffuses the incident white light WL while being concentrated by the concentrating element 25, and emits the diffused white light WL toward the first diffusion device 40. The second diffusion device 100 is a transmissive diffusion device that diffuses and transmits the incident white light WL.

[0041] The second diffusion device 100 has, for example, a substrate 110A and a driving device 111. The substrate 110A corresponds to a second substrate. The driving device 111 corresponds to a second driving device. The substrate 110A has an incident surface 110a onto which the white light WL being collected by the light collecting element 25 is irradiated, and an exit surface 110b on the opposite side to the incident surface 110a. The substrate 110A is disposed so that the incident surface 110a faces the light collecting element 25. The incident surface 110a is perpendicular to the optical axis AX2.

[0042] The substrate 110A is mounted on the driving device 111 in a state in which it can rotate 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 an axis member 112 with the rotation axis OX2 as its axis. The axis member 112 is, for example, inserted into the center of the substrate 110A from the incident surface 110a side. The centers of the incident surface 110a and the exit surface 110b of the substrate 110A overlap with the rotation axis OX2. The substrate 110A rotates around the rotation axis OX2 as described above in conjunction with the rotation of the axis member 112 around the rotation axis OX2, diffusing the white light WL and changing the intensity distribution and phase distribution in the focused spot 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 focused spot SP. That is, the second diffusion device 100 changes over time the state of the focused spot SP of the white light WL on the diffusion surface 45 of the first diffusion device 40. Note that the driving device 111 is not limited to a motor as long as it is a device that can rotate the substrate 110A as described above.

[0043] Fig. 4 is a schematic diagram of the substrate 110A of the second diffusion device 100, and is a view of the substrate 110A viewed from the incident surface 110a side along the rotation axis OX2. As shown in Figs. 2 and 4, when viewed along the rotation axis OX2, the irradiation area of ​​the white light WL on the substrate 110A is a part of the area that does not overlap with the driving device 111 in the radial direction centered on the incident surface 110a of the substrate 110A, that is, between the center, i.e., the rotation axis OX2, and the peripheral edge.

[0044] The incident surface 110a constitutes a diffusion surface 121 that diffuses and emits the incident white light WL. The diffusion surface 121 corresponds to a second diffusion surface. The substrate 110A rotates in a rotation direction DS, i.e., a circumferential direction, around a rotation axis OX2. 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 partitioned into the first region R1, the second region R2, the third region R3, and the fourth region R4 in the rotation direction DS. The 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°.

[0045] The uneven structure 131 is formed in the first region R1 of the diffusion surface 121. The uneven structure 131 is appropriately designed in consideration of the wavelength band of the white light WL so as to appropriately diffuse the white light WL, and is created in the same manner as the uneven structure formed on a known diffusion plate. Here, the state in which the white light WL is appropriately diffused means a state in which the white light WL diffused by the diffusion surface 121 of 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 modulation devices 4R, 4G, and 4B of the projector 1, and the speckle noise caused by the irradiated light when projected onto the screen SCR is satisfactorily reduced, as described later. The uneven structure 131 corresponds to the first uneven structure.

[0046] The uneven structure 131 may be formed by, for example, blasting or etching, or may be formed in a random pattern in which convex portions and concave portions are irregularly arranged. The uneven structure 131 may be realized, for example, by forming a plurality of microlenses having a diameter equal to or smaller than the wavelength of the white light WL using a photolithography technique. The uneven structure 131 may be formed, for example, by scattering 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 so as to reflect the surface shape of the plurality of particles.

[0047] The uneven structure 132 is formed in the second region R2 of the diffusion surface 121. The uneven structure 132 has at least a different diffusion characteristic from the uneven structure 131 and has a different shape from the uneven structure 131. The uneven structure 132 corresponds to a second uneven structure. Specifically, the uneven structure 132 may be created by a different method from the uneven structure 131. The uneven structure 132 may be created by the same method as the uneven structure 131, and may have, for example, a different height of the convex portions and concave portions and a different pitch distribution of the convex portions and concave portions from the uneven structure 131. When the uneven structure 131 has a uniform uneven pattern, the uneven structure 132 may have a non-uniform uneven pattern. Conversely, when the uneven structure 131 has a non-uniform uneven pattern, the uneven structure 132 may have a uniform uneven pattern, or the uneven structure 132 may have a non-uniform uneven pattern and may have a non-uniform uneven pattern different from the uneven structure 131.

[0048] The uneven structure 133 is formed in the third region R3 of the diffusion surface 121. The uneven structure 133 has diffusion characteristics different from each of the uneven structures 131 and 132, and has a shape different from each of the uneven structures 131 and 132. Specifically, the uneven structure 133 may be created by a method different from each of the uneven structures 131 and 132. The uneven structure 133 is created by the same method as the uneven structures 131 and 132, and may have, for example, a distribution of heights of convex portions and concave portions and pitches of convex portions and concave portions different from each of the uneven structures 131 and 132. When the uneven structure 132 has a uniform uneven pattern, the uneven structure 133 may have a non-uniform uneven pattern. Conversely, when the uneven structure 132 has a non-uniform uneven pattern, the uneven structure 133 may have a uniform uneven pattern, or the uneven structure 133 may also have a non-uniform uneven pattern and have a different unevenness in the uneven pattern than each of the uneven structures 131, 132.

[0049] The uneven structure 134 is formed in the fourth region R4 of the diffusion surface 121. The uneven structure 134 has diffusion characteristics different from each of the uneven structures 131, 132, and 133, and has a shape different from each of the uneven structures 131, 132, and 133. Specifically, the uneven structure 134 may be created by a method different from each of the uneven structures 131, 132, and 133. The uneven structure 134 may be created by the same method as the uneven structures 131, 132, and 133, and may have, for example, a distribution of heights of convex portions and concave portions and pitches of convex portions and concave portions different from each of the uneven structures 131, 132, and 133. When the uneven structures 131 and 133 have a uniform uneven pattern, the uneven structure 134 may have a non-uniform uneven pattern. Conversely, when the uneven structures 131 and 133 have non-uniform uneven patterns, the uneven structure 134 may have a uniform uneven pattern, or the uneven structure 134 may also have a non-uniform uneven pattern and may have a different unevenness in the uneven pattern than each of the uneven structures 131, 132, and 133.

[0050] The uneven structures 131, 132, 133, and 134 may be formed over the entire radial range from the center to the peripheral edge of the incident surface 110a as shown in FIG. 4, but may be formed over at least a portion of the radial range that includes the area where the white light WL is irradiated.

[0051] The substrate 110A is made of a material that is transparent to the white light WL, such as optical glass or plastic. In Fig. 4, the uneven structures 131, 132, 133, and 134 have different diffusion characteristics, as shown by the difference in dot density. The uneven structures 131, 132, 133, and 134 are made of a material that is transparent to the white light WL and does not have a light blocking property, similar to the substrate 110A.

[0052] By rotating the substrate 110A of the second diffusion device 100 in the rotation direction DS about the rotation axis OX2, the amplitude distribution and phase distribution of the white light WL emitted from the light collecting element 25 are modulated according to the uneven 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 types of speckle patterns of the white light WL are generated according to each of the uneven structures 131, 132, 133, and 134. The white light WL is diffused by the diffusion surface 121, includes a diffusion, scattering, or diffraction pattern due to each of the uneven structures 131, 132, 133, and 134, transmits through the substrate 110A as diffused light, and is emitted from the emission surface 110b along the optical axis AX2.

[0053] The rotation speed of the substrate 110A of the second diffusion device 100 in the rotation direction DS around the rotation axis OX2 is, for example, 1 / 240 [revolutions / second] or more. That is, the rotation speed of the drive device 111 around the rotation axis OX2 is set to 1 / 240 [revolutions / second] or more. As a result, for example, the first region R1, the second region R2, the third region R3, and the fourth region R4 to which the white light WL is irradiated are switched every short time of 1 / 60 seconds or more. The diffusion, scattering, or diffraction pattern and the speckle pattern of the condensed spot SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 change every short time of 1 / 60 seconds or more. Therefore, the frequency at which the state of the condensed spot SP on the diffusion surface 45 of the first diffusion device 40 changes due to the rotation of the substrate 110A is 60 [Hz] or more. That is, the frequency at which the diffusion, scattering or diffraction pattern of the focused spot SP of the white light WL incident on the diffusing surface 45 and the speckle pattern change is 60 [Hz] or higher.

[0054] Returning to FIG. 2, the substrate 41 of the first diffusion device 40 is irradiated with a focused spot SP of white light WL emitted from the emission surface 110b of the substrate 110A of the second diffusion device 100 in a diffused state and with the diffused state switching over time. Therefore, in the speckle pattern of the white light WL reflected from the incidence surface 41a of the substrate 41 of the first diffusion device 40 and emitted along the optical axis AX10, a synergistic effect between any one of the four types of uneven structures 131, 132, 133, 134 and the uneven structure 47 appears. The speckle pattern of the white light WL emitted along the optical axis AX10 is determined by the optical overlap between the diffusion, scattering, or diffraction pattern of any one of the uneven structures 131, 132, 133, 134 and the diffusion, scattering, or diffraction pattern of the uneven structure 47, and changes over time.

[0055] The collimating element 26 is disposed on the optical path of the white light WL emitted from the substrate 41 of the first diffusion device 40. The collimating element 26 collimates 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 perpendicular to the optical axis AX10 substantially overlaps with the optical axis AX10. The collimating element 26 is, for example, a biconvex lens, but may be an optical element having a light-collecting function other than a biconvex lens, may be a plano-convex lens, or may be composed of multiple optical lenses. When the collimating element 26 is composed of one optical lens, the accuracy of collimation can be further improved by using an aspheric lens.

[0056] The integrating optical system 50 has a multi-lens array 51 and a superimposing lens 52. The integrating optical system 50 homogenizes the illuminance distribution of the white light WL emitted from the collimating element 26 in the image forming areas of the optical modulation devices 4R, 4G, and 4B arranged downstream.

[0057] The multilens array 51 is disposed on the optical path of the white light WL emitted from the collimating element 26 and collimated. The multilens array 51 is, for example, a double-sided multilens array. The double-sided multilens includes a plurality of microlenses 53 for splitting the white light WL emitted from the collimating element 26 into a plurality of small beams. The plurality of microlenses 53 are disposed adjacent to each other in a matrix along a plane perpendicular to the optical axis AX10. The microlenses 53 are, for example, plano-convex lenses that are convex toward the incident side. The double-sided multilens has a first multilens surface 51a that is provided on the incident side along the shape of the plano-convex lens that constitutes the microlens 53. The double-sided multilens includes a plurality of microlenses 54, the same number as the plurality of microlenses 53, on a surface perpendicular to the optical axis AX10. The respective microlenses 54 are disposed adjacent to each other in a matrix along a plane perpendicular to the optical axis AX10, and overlap with each of the microlenses 53. The microlenses 54 are, for example, plano-convex lenses that are convex toward the exit side. The exit-side plane of each of the multiple microlenses 54 is common to the entrance-side plane of each of the multiple microlenses 53. The double-sided multi-lens has a second multi-lens surface 51b provided on the exit side along the shape of the plano-convex lens that constitutes the microlens 54.

[0058] The superimposing lens 52 collects each of the multiple small beams of the white light WL emitted from the multilens array 51, and superimposes the collected beams on each other in the image forming area or in the vicinity of the image forming area of ​​each of the light modulation devices 4R, 4G, and 4B in cooperation with the multiple microlenses 54 of the multilens array 51. The superimposing lens 52 is, for example, a plano-convex lens, but may be an optical element having a light collecting function other than a plano-convex lens, may be a biconvex lens, or may be composed of multiple optical lenses.

[0059] Next, a numerical calculation example in which the light distribution on the incident surface of the plurality of microlenses 54 of the multi-lens array 51 in the illumination device 2 of the present embodiment is calculated by simulation will be described with reference to FIGS.

[0060] 5 to 12 are diagrams showing the distribution of light rays, in which the white light WL incident on the multiple microlenses 54 of the multilens array 51 is treated as a common number of light rays, and the points where the light rays intersect with the incident surfaces of the multiple microlenses 54 are represented by points. The two-dot chain lines in each of the diagrams from Fig. 5 to Fig. 12 represent the boundaries of the incident surfaces of the multiple microlenses 54.

[0061] In the following description of the present simulation, the diffusion state when white light WL is diffused by one of the uneven structures 131, 132, 133, and 134 formed on the incident surface 110a and the diffusion surface 121 of the substrate 110A of the second diffusion device 100, for example, the uneven structure 131, is expressed as cos n Express it with the exponent n using θ. cos n θ is a known diffusion approximation coefficient that indicates the state of light diffused by an optical material or optical member in order to quantitatively express the diffusion characteristics of the optical material or optical member having diffusion properties. n is a natural number. When the exponent n is relatively large, it means that the diffusion power is relatively small, for example, that the pitch of the convex and concave portions of the uneven structure formed on the diffusion surface 121 is relatively large, or that it is close to the reference wavelength of the incident white light WL.

[0062] In this simulation, the change over time of the unevenness structure due to the rotation of the substrate 110A, that is, the cos n The difference in exponent n with θ is not taken into account.

[0063] <Numerical calculation example 1> FIG. 5 is a diagram showing the result of calculating the light distribution on the incident surface of the multiple microlenses 54 of the multilens array 51 in a configuration in which the second diffusion device 100 of the illumination device 2 of this embodiment is not provided, that is, in a conventional illumination device, in the numerical calculation example 1 of this simulation. As shown in FIG. 5, in the conventional illumination device not provided with the second diffusion device 100, the light rays of the white light WL are concentrated at the center of the incident surface of each of the multiple microlenses 54 of the multilens array 51. In the numerical calculation example 1, the high-density region in which the light rays of the white light WL are concentrated more densely than the surroundings does not concentrate at one point at the center of each of the incident surfaces of the multiple microlenses 54, but has a predetermined width. The high-density region is caused by the fact that each of the first light source 20R, the second light source 20G, and the third light source 20B has a size. The light-emitting surfaces of each of the first light source 20R, the second light source 20G, and the third light source 20B form spot images on the incident surface 41a of the substrate 41 of the first diffusion device 40. The spot images are formed on the entrance surfaces of a plurality of microlenses 54 that are in a conjugate relationship with the entrance surface 41a.

[0064] <Numerical calculation example 2> FIG. 6 is a diagram showing the result of calculating the light distribution on the incident surface of the multiple microlenses 54 of the multilens array 51 in the case where the diffusion state of the white light WL in the uneven structure 131 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 is set to index n=100000 in the configuration of the illumination device 2 of this embodiment in the numerical calculation example 2 of this simulation. As shown in FIG. 6, in the illumination device 2 of this embodiment and the numerical calculation example 2, the white light WL is diffused by, for example, the uneven 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 region where the light rays of the white light WL are concentrated more densely than the surroundings does not concentrate on one point at the center of each of the incident surfaces of the multiple microlenses 54. The width of the high-density region in the numerical calculation example 2 is wider than the width of the high-density region in the numerical calculation example 1. The width of the high-density region in Numerical Calculation Example 2 depends on the diffusion characteristics of the uneven structure 131, the diffusion state of the white light WL diffused by the uneven structure 131, and the index n. From the results of Numerical Calculation Example 2, it was quantitatively confirmed that in the illumination device 2 of this embodiment, the white light WL incident on the multilens array 51 is diffused within the incident surface of each of the multiple microlenses 54 more than in the conventional illumination device.

[0065] <Numerical calculation example 3-Numerical calculation example 7> 7 to 11 are diagrams showing the results of calculating the light distribution on the entrance surface of the multiple microlenses 54 of the multilens array 51 in the case where the diffusion state of the white light WL in the uneven structure 131 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 in the configuration of the illumination device 2 of this embodiment 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 in each of Numerical Calculation Example 3 to Numerical Calculation Example 7 in each of Numerical Calculation Example 3 to Numerical Calculation Example 7 of the present simulation. As shown in FIG. 7 to FIG. 11, in the illumination device 2 of this embodiment and Numerical Calculation Example 3 to Numerical Calculation Example 7, the white light WL is diffused by the uneven structure 131, for example, in the same manner 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 region where the light rays of the white light WL on the entrance surface of each of the microlenses 54 are concentrated at a higher density than the surroundings increases, and the peak of the density distribution of the white light WL decreases. From the results of Numerical Calculation Example 3 to Numerical Calculation Example 7, it was quantitatively confirmed that in the illumination device 2 of this embodiment, the white light WL incident on the multilens array 51 is diffused in the entrance surface of each of the microlenses 54 more than in the conventional illumination device, and as the index n decreases, the beam width of the white light WL increases and the peak intensity of the white light WL decreases. In the illumination device 2 of this embodiment, the white light WL incident on the multilens array 51 of the integrated optical system 50 is diffused well by any one of the uneven 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 uneven 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 condensed white light WL is contained within each of the microlenses 54, and a decrease in the utilization efficiency of the white light WL is suppressed. In addition, the polarization characteristics of each of the color lights, that is, the red light RL incident on the light modulation device 4R, the green light GL incident on the light modulation device 4G, and the blue light BL incident on the light modulation device 4B, are easily disturbed.

[0066] <Numerical calculation example 8> 12 is a diagram showing the result of calculating the light distribution on the incident surface of the multiple microlenses 54 of the multilens array 51 in the case where the diffusion state of the white light WL in the uneven structure 131 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 is set to index n=1000 in the configuration of the illumination device 2 of this embodiment in Numerical Calculation Example 8 of this simulation. As shown in FIG. 12, in the illumination device 2 of this embodiment and Numerical Calculation Example 8, similar to each example from Numerical Calculation Example 2 to Numerical Calculation Example 7, the white light WL is diffused by, for example, the uneven structure 131. However, in Numerical Calculation Example 8, the white light WL incident on the multilens array 51 does not fall within the incident surface of each of the multiple microlenses 54, and is diffused to the incident surface adjacent to each of the incident surfaces of the multiple microlenses 54. This indicates that when the index n of the diffusion state of the white light WL in the uneven structure 131 decreases to 1000, the light incident on each of the multiple microlenses 54 of the multi-lens array 51 also enters the adjacent microlenses 54. In that case, in the projector 1 of the present embodiment, the utilization efficiency of the white light WL emitted from the illumination device 2 decreases according to the amount of white light WL that spreads outward beyond each of the multiple microlenses 54. In addition, the polarization characteristics of each of the color lights, that is, the red light RL incident on the light modulation device 4R, the green light GL incident on the light modulation device 4G, and the blue light BL incident on the light modulation device 4B, are easily disturbed.

[0067] <Summary of numerical calculation examples> From the results of Numerical Calculation Example 1 to Numerical Calculation Example 8 of this simulation, the diffusion state of the white light WL in the uneven 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 is not diffused on the incident surface 110a of the substrate 110A like a flat surface with no convex or concave portions formed thereon, or a diffusion state in which the small beams of the white light WL are not incident on the incident surfaces of the microlenses 54 adjacent to the incident surfaces of the microlenses 54 on which the small beams of the white light WL are incident in the multilens array 51. The diffusion state of the white light WL in the uneven structures 131, 132, 133, and 134 is preferably a diffusion state in which the index n is greater than 1000, for example, and it can be said that a diffusion state in which the index n is greater than 2500 and less than 100000 is preferable.

[0068] The illumination device 2 of the present embodiment described above includes at least the first light source 20R and the second light source 20G, and further includes the third light source 20B. The illumination device 2 of the present embodiment includes a light combining member 24, a first diffusion device 40, a condensing 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 combining member 24 combines the red light LR and the green light GL, and emits white light (combined light) WL. The first diffusion device 40 includes 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 concentrating element 25 is disposed between the light combining member 24 and the first diffusing device 40, and focuses the white light WL on the diffusion surface 45 of the substrate 41 of the first diffusing device 40. The collimating element 26 collimates the white light WL emitted from the substrate 41 of the first diffusing device 40. The second diffusing device 100 is disposed between the concentrating element 25 and the first diffusing device 40, and changes the state of the focused spot (spot) SP of the white light WL on the diffusion surface 45 over time.

[0069] In contrast to the illumination device 2 of this embodiment, a conventional illumination device may have a configuration in which the second diffusion device 100 is not provided between the light collecting element 25 and the first diffusion device 40. In the illumination device 2 of this embodiment, the white light WL irradiated to the diffusion surface 45 of the substrate 41 of the first diffusion device 40 is diffused by any one of the uneven structures 131, 132, 133, and 134 formed on the diffusion surface 121 of the substrate 110A of the second diffusion device 100. According to the illumination device 2 of this embodiment, the white light WL with reduced speckle noise is incident on the integrated optical system 50 arranged after the first diffusion device 40, that is, on the side where the white light WL is projected, compared to a conventional illumination device without the second diffusion device 100. Therefore, according to the illumination device 2 of this embodiment, when the white light WL emitted from the illumination device 2 is projected, the speckle noise generated in the projected image can be reduced satisfactorily.

[0070] As a conventional illumination device, there is another configuration in which a diffusion device is provided between the light collecting element 25 and the first diffusion device 40, in which the uneven structure of the diffusion surface and the diffusion state of the white light WL by the diffusion surface do not change over time. In this configuration, the speckle pattern in the focused spot 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 over time. According to the illumination device 2 of this embodiment, the white light WL in which the speckle noise is reduced over time and at a higher speed is incident on the integrated optical system 50 arranged in the rear stage of the first diffusion device 40, compared to a conventional illumination device not provided with the first diffusion device 40. Therefore, according to the illumination device 2 of this embodiment, when the white light WL emitted from the illumination device 2 is projected, the speckle noise generated in the projected image can be reduced more effectively.

[0071] In the lighting device 2 of this embodiment, the second diffusion device 100 has a substrate (second substrate) 110 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 a 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 types of uneven structures along the rotation direction DS, and has, for example, a first region R1 in which an uneven structure (first uneven structure) 131 is provided, and a second region R2 in which an uneven structure (second uneven structure) 132 different from the uneven structure 131 is provided.

[0072] In the illumination device 2 of this 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 to which the white light WL incident on the diffusion surface 121 is irradiated are switched over time, and the uneven structures 131, 132 to which the white light WL is incident are switched over time. Therefore, it is possible to change the diffusion, scattering or diffraction pattern and the speckle pattern in the focused spot SP of the white light WL formed on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 over time. According to the illumination device 2 of this embodiment, the white light WL in which the speckle noise is reduced over time and at high speed is incident on the integrated optical system 50, and the speckle noise occurring in the projected image based on the white light WL can be reduced more effectively.

[0073] In the illumination device 2 of this embodiment, the frequency at which the state of the focused spots SP on the diffusion surface 45 of the first diffusion device 40 changes as a result of the rotation of the substrate 110A of the second diffusion device 100 is 60 [Hz] or higher.

[0074] In the illumination device 2 of this embodiment, the diffusion surface 121 of the substrate 110A of the second diffusion device 100 has, for example, a first region R1 and a second region R2, and further has a third region R3 and a fourth region R4. In the illumination device 2 of this embodiment, the first region R1, the second region R2, the third region R3, and the fourth region R4 into which the white light WL is incident on the diffusion surface 121 of the substrate 110A of the second diffusion device 100 are discontinuously switched at a frequency of 60 [Hz] or more. Accordingly, the diffusion, scattering, or diffraction pattern of the focused spot SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 and the speckle pattern are discontinuously switched at a frequency of 60 [Hz] or more. According to the illumination device 2 of this embodiment, the viewer of the projected image based on the white light WL is unlikely to recognize blinking or flicker of the image caused by speckle noise.

[0075] In the illumination device 2 of this embodiment, the number of regions of the diffusion surface 121 of the substrate 110A of the second diffusion device 100 is not limited to four, but is any natural number m equal to or greater than two. For example, assume that the regions on the diffusion surface 121 on which different uneven structures are formed are divided into m equal parts in the rotation direction DS, and the diffusion, scattering or diffraction pattern of the focused spot SP of the white light WL incident on the diffusion surface 45 and the speckle pattern are switched at a frequency of ct [Hz] or more. In this case, the rotation speed of the drive device 111 may be set to 1 / (ct×m) [revolutions / second] or more. The frequency ct [Hz] may be adjusted so that m is a natural number as described above.

[0076] The projector 1 of this embodiment includes the above-mentioned illumination device 2, light modulation devices 4R, 4G, and 4B, and a projection optical system 6. The light modulation device 4R modulates red light RL contained in white light WL emitted from the illumination device 2 to generate red image light. The light modulation device 4G modulates green light GL contained in the white light WL to generate green image light. The light modulation device 4B modulates blue light BL contained in the white light WL to generate blue image light. The projection optical system 6 projects the image light modulated by the light modulation devices 4R, 4G, and 4B.

[0077] In the projector 1 of the present embodiment, the illumination device 2 includes 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 modulation devices 4R, 4G, and 4B and the image light is projected onto the screen SCR, speckle noise occurring in the projected image can be effectively reduced.

[0078] Next, modified examples of the substrate 110A of the second diffusion device 100 in the illumination device 2 of this embodiment will be described with reference to Fig. 13 to Fig. 15. In the description of each modified example, content common to the modified examples already described is omitted, and configurations and content different from the modified examples already described are described.

[0079] [First Modification] FIG. 13 is a schematic diagram of the substrate 110B of the first modification of the second diffusion device 100, and is a view of the substrate 110B viewed from the incident surface 110a side along the rotation axis OX2. In the first modification, 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 embodiment may be a non-diffusion surface 141. The substrate 110B is a first modification of the substrate 110A. In the substrate 110B shown in FIG. 13, the non-diffusion surface 141 is provided in the second region R2. The non-diffusion surface 141 transmits the incident white light WL without diffusing it. The non-diffusion surface 141 is, for example, a flat surface 140 on which no uneven structure is formed.

[0080] In a first modified example of the lighting device 2 of this 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 a rotation direction DS. The substrate 110B has a diffusion surface 121 that diffuses and transmits the incident white light WL, and a non-diffusion surface 141 that is disposed at a position different from the diffusion surface 121 in the rotation direction DS and transmits the white light WL. The diffusion surface 121 has at least one type of uneven structure along the rotation direction DS, and has, for example, a first region R1 in which an uneven structure 131 is provided. The diffusion surface 121 of the substrate 110B has a third region R3 in which an uneven structure 133 different from the uneven structure 131 is provided, and a fourth region R4 in which an uneven structure 134 different from the uneven structure 131 is provided. The non-diffusion surface 141 has a flat second region R2 that does not diffuse the white light WL.

[0081] In the first modification of the illumination device 2 of this 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 to which the white light WL incident on the diffusion surface 121 is irradiated are switched over in time, and the uneven structure 131 of the first region R1 to which the white light WL is incident and the flat surface 140 of the second region R2 are switched over in time. Therefore, similarly to the case where the substrate 110A is provided, the diffusion, scattering or diffraction pattern and the speckle pattern in the focused spot 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 over time. According to the first modification of the illumination device 2 of this embodiment, the white light WL in which the speckle noise is reduced over time and at high speed is incident on the integrated optical system 50, and the speckle noise occurring in the projected image based on the white light WL can be reduced more effectively.

[0082] As another modified example of the substrate 110B (not shown), for example, a 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 uneven structure 132 may be provided in the second region R2. As another modified example of the substrate 110B (not shown), when viewed along the rotation axis OX2, a diffusion surface 121 and an uneven structure may be provided in two regions among 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 a flat surface 140, for example, may be provided as the non-diffusion surface 141 in the remaining two regions.

[0083] Another modified example of the substrate 110B (not shown) is a substrate in which the number of regions defined in the rotation direction DS is two or more but not four, and the diffusion states in which the white light WL is diffused in the regions adjacent to each other in the rotation direction DS are different from each other. In such a substrate, a non-diffusion surface 141 is provided in at least one of the multiple regions. When the number of regions defined in the rotation direction DS is five or more, the non-diffusion surface 141 may be provided in two or more regions, and the diffusion surface 121 is provided in one or more regions between the non-diffusion surfaces 141 provided in two regions in the rotation direction DS.

[0084] [Second modified example] FIG. 14 is a schematic diagram of the substrate 110C of the second modification of the second diffusion device 100, and is a view of the substrate 110C viewed from the incident surface 110a side along the rotation axis OX2. In the second modification, 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 have only the first region R1. The substrate 110C is a second modification of the substrate 110A. The angle θ1 of the first region R1 is 360°. The first region R1 of the substrate 110C has an uneven structure 135 formed therein. In the uneven structure 135, the diffusion state of the incident white light WL changes continuously along the rotation direction DS. In the uneven structure 135, for example, the height of the convex portions and the concave portions and the pitch of the convex portions and the concave portions change continuously along the rotation direction DS.

[0085] In the second modification of the illumination device 2 of the present embodiment, the diffusion surface 121 of the substrate 110C of the second diffusion device 100 has only the first region R1. In the second modification, the diffusion state of the white light WL diffused by the uneven structure in the first region R1 where the white light WL is incident on the diffusion surface 121 of the substrate 110C of the second diffusion device 100 changes continuously for each rotation along the rotation direction DS. Accordingly, the diffusion, scattering or diffraction pattern of the focused spot SP of the white light WL incident on the diffusion surface 45 of the substrate 41 of the first diffusion device 40 and the speckle pattern are continuously switched for each rotation of the substrate 110C. According to the second modification of the illumination device 2 of the present embodiment, the same action and effect as when the second diffusion device 100 includes the substrates 110A and 110B can be obtained.

[0086] [Third Modification] FIG. 15 is a schematic diagram of the substrate 110D of the third modification of the second diffusion device 100, and is a view of the substrate 110D viewed from the incident surface 110a side along the rotation axis OX2. As shown in FIG. 15, the substrate 110D of the third modification has an uneven structure 135 formed in the third region R3 of the substrate 110B of the first modification, instead of the uneven structure 133. The substrate 110D is a third modification of the substrate 110A. Including the configuration of the substrate 110D, the incident surface 110a of the substrate 110D may have a diffusion surface 121 whose diffusion state that diffuses the white light WL changes discontinuously in the rotation direction DS, a diffusion surface 121 whose diffusion state changes continuously, and a non-diffusion surface 141 where the white light WL is not diffused. According to the third modification of the lighting device 2 of this embodiment, the same action and effect as when the second diffusion device 100 includes the substrates 110A, 110B, and 110C can be obtained.

[0087] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

[0088] For example, the shape, number, arrangement, and material of each component of the illumination device and projector are not limited to those described in the above-described embodiment and modified examples, and may be changed as appropriate.

[0089] In the above embodiment, an example of a reflective diffusion device as the first diffusion device is shown as the illumination device of the present invention, but the present invention is not limited to this example. For example, the illumination device of the present invention may include a transmissive diffusion device as the first diffusion device. In that case, a reflective film is not provided on the substrate of the first diffusion device. The composite light diffused by the diffusion surface of the substrate of the first diffusion device and transmitted through the substrate is emitted from the exit surface of the substrate along an optical axis aligned with the optical axis of the composite light incident on the substrate. In the above embodiment, since the first diffusion device is a reflective diffusion device, there is less disturbance in the polarization of the composite light emitted from the first diffusion device compared to the case of a transmissive diffusion device.

[0090] In the above embodiment, the illuminating device of the present invention is an example in which the diffusion surface of the second diffusion device is formed by the incident surface of the substrate of the second diffusion device, but is not limited to this example. For example, the diffusion surface of the second diffusion device may be formed by the exit surface of the substrate of the second diffusion device, or may be formed by both the incident surface and the exit surface of the substrate of the second diffusion device.

[0091] In the above embodiment, an example in which the illumination device of the present invention is mounted on a projector using a liquid crystal panel has been shown, but the present invention is not limited to this example. For example, the illumination device of the present invention may be applied to a projector using a digital micromirror device as a light modulation device. The projector of the present invention may not have a plurality of light modulation devices, and may be a single-panel projector having only one light modulation device.

[0092] [Summary of this disclosure] The following is a summary of this disclosure. (Supplementary Note 1) An illumination device comprising: a first diffusing device having 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 light combining member that combines the first light and the second light and emits a combined light, a first substrate having a first diffusing surface that diffuses and emits the combined light incident thereon, and a first drive device that rotates the first substrate; a focusing element that is disposed between the light combining member and the first diffusing device and focuses the combined light on the first diffusing surface of the first diffusing device, a collimating element that collimates the combined light emitted from the first diffusing device, and a second diffusing device that is disposed between the focusing element and the first diffusing device and changes a spot state of the combined light on the first diffusing surface over time.

[0093] The configuration of Supplementary Note 1 allows the optical system downstream of the first diffusion device to receive combined light with reduced speckle noise, compared to a configuration that does not include a second diffusion device, or a configuration in which the diffusion state of the combined light entering as the second diffusion device does not change over time. Therefore, the configuration of Supplementary Note 1 allows the speckle noise generated in the projected image to be effectively reduced when the combined light emitted from the lighting device is projected.

[0094] (Appendix 2) The lighting device of Appendix 1, wherein the second diffusion device has a second substrate that diffuses and emits the incident combined light, and a second drive device that rotates the second substrate, the second substrate having a second diffusion surface that diffuses and transmits the incident combined light, the second diffusion surface having a first region having a first unevenness structure, and a second region having a second unevenness structure different from the first unevenness structure.

[0095] With the configuration of Supplementary Note 2, when the second substrate is rotated by the second driving device, the first region and the second region irradiated with the combined light incident on the second diffusing surface are switched over time, and the diffusing surface onto which the combined light is incident is switched over time. Therefore, the diffusion, scattering or diffraction pattern and the speckle pattern in the spot of the combined light formed on the first diffusing surface can be changed over time.

[0096] (Supplementary Note 3) The lighting device of Supplementary Note 1, wherein the second diffusion device includes a second substrate that diffuses and emits the incident combined light, and a second drive device that rotates the second substrate, the second substrate including a second diffusion surface that diffuses and transmits the incident combined light, and a non-diffusion surface that is positioned differently from the second diffusion surface and transmits the combined light, the diffusion surface including a first region having a concave-convex structure, and the non-diffusion surface including a flat second region that does not diffuse the combined light.

[0097] With the configuration of Supplementary Note 3, when the second substrate is rotated by the second driving device, the first region and the second region irradiated with the combined light incident on the second diffusing surface are switched over time, and the diffusing surface and the non-diffusing surface on which the combined light is incident are switched over time. Therefore, the diffusion, scattering or diffraction pattern and the speckle pattern in the spot of the combined light formed on the first diffusing surface can be changed over time.

[0098] (Supplementary Note 4) Any one of Supplementary Notes 1 to 3, wherein the frequency at which the state of the spot on the first diffusion surface of the first diffusion device changes due to the rotation of the second substrate that diffuses and emits the incident combined light in the second diffusion device is 60 Hz or more.

[0099] According to the configuration of Supplementary Note 4, the diffusion, scattering or diffraction pattern of the spot of the composite light incident on the first diffusion surface and the speckle pattern are discontinuously switched at a frequency of 60 Hz or more. According to the configuration of Supplementary Note 4, a viewer of a projected image based on the composite light does not recognize blinking or flicker of the image caused by speckle noise.

[0100] (Supplementary Note 5) A projector comprising: an illumination device according to any one of Supplementary Note 1 to Supplementary Note 4; a light modulation device that modulates light emitted from the illumination device; and a projection optical system that projects the light modulated by the light modulation device.

[0101] With the configuration of Supplementary Note 5, when the composite light emitted from the illumination device is converted into image light by the light modulation device and the image light is projected, speckle noise occurring in the projected image can be effectively reduced. [Explanation of symbols]

[0102] 1...projector, 2...illumination device, 20R...first light source, 20G...second light source, 24...light combining member, 25...light-collecting element, 26...collimating element, 40...first diffusion device, 45...diffusion surface (first diffusion surface), 100...second diffusion device.

Claims

1. a first light source that emits a 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 a combined light; a first diffusion device including a first substrate having a first diffusion surface that diffuses the incident combined light and emits the combined light; and a first drive device that rotates the first substrate; a focusing element disposed between the light combining member and the first diffusing device, the focusing element focusing the combined light on the first diffusing surface of the first diffusing device; a collimating element that collimates the combined light emitted from the first diffusion device; a second diffusion device disposed between the light collecting element and the first diffusion device and configured to change a spot state of the combined light on the first diffusion surface over time; Equipped with Lighting equipment.

2. The second diffusion device is a second substrate that diffuses the incident combined light and emits the combined light; A second drive device that rotates the second substrate; having the second substrate has a second diffusion surface that diffuses and transmits the incident combined light, The second diffusion surface is a first region provided with a first uneven structure; a second region provided with a second uneven structure different from the first uneven structure; having 10. The lighting device of claim 1.

3. The second diffusion device is a second substrate that diffuses the incident combined light and emits the combined light; A second drive device that rotates the second substrate; having The second substrate is a second diffusion surface that diffuses and transmits the incident combined light; a non-diffusion surface that is disposed at a position different from the second diffusion surface and transmits the combined light; having the second diffusion surface has a first region provided with a concave-convex structure, the non-diffusing surface has a flat second region that does not diffuse the combined light; 10. The lighting device of claim 1.

4. a frequency at which the state of the spot on the first diffusion surface of the first diffusion device changes due to rotation of a second substrate in the second diffusion device, the second substrate diffusing and emitting the incident combined light is 60 Hz or more; The lighting device according to claim 1 .

5. The lighting device according to claim 1 ; a light modulation device that modulates light emitted from the illumination device; a projection optical system that projects the light modulated by the light modulation device; Equipped with projector.

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