Lighting equipment and projectors

Abstract

To provide an illumination device in which speckle noise is suppressed. [Solution] The lighting device of the present invention includes a first light source that emits a first light, a second light source that emits a second light, a light combining member that combines the first light and the second light to emit illumination light, a light diffusing device that diffuses and reflects the illumination light, a focusing element that focuses the illumination light emitted from the light combining member toward the light diffusing device, and a collimator element that collimates the illumination light emitted from the light diffusing device. The light diffusing device includes a diffuser plate including a diffusing surface that diffuses and reflects the illumination light, and a drive device that rotates the diffuser plate around a rotation axis. The diffusing surface has a first region that reflects the illumination light at a first reflection angle and a second region that is arranged circumferentially of the diffuser plate relative to the first region and reflects the illumination light at a second reflection angle different from the first reflection angle.

Description

[Technical Field]

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

[0002] To improve the performance of projectors, projectors have been proposed that include an illumination device using a laser light source, which is a light source with a wide color gamut and high efficiency. Patent Document 1 below discloses an illumination device that includes a blue light source array, a red light source array, a green light source array, a color synthesis optical system, a condenser lens, and a diffuser. In this illumination device, light emitted from the blue light source array, red light source array, and green light source array passes through the diffuser, thereby suppressing the occurrence of speckle noise in the projected image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-078906 Summary of the Invention [Problem to be solved by the invention]

[0004] However, simply using a transmission type diffuser plate as in the illumination device of Patent Document 1 does not provide a sufficient effect of reducing speckle noise, and further reduction of speckle noise is desired. [Means for solving the problem]

[0005] To solve the above problems, one aspect of the present invention provides an illumination device including a first light source that emits first light in a first wavelength band, a second light source that emits second light in a second wavelength band different from the first wavelength band, a light combining element that combines the first light and the second light to emit illumination light, a light diffusing device that diffuses and reflects the illumination light emitted from the light combining element, a focusing element disposed between the light combining element and the light diffusing device and focusing the illumination light emitted from the light combining element toward the light diffusing device, and a collimator element that collimates the illumination light emitted from the light diffusing device. The light diffusing device includes a diffuser plate including a diffusing surface that diffuses and reflects the illumination light, and a drive device that rotates the diffuser plate around a rotation axis. The diffusing surface has a first region where the illumination light is reflected at a first reflection angle, and a second region disposed circumferentially of the diffuser plate relative to the first region where the illumination light is reflected at a second reflection angle different from the first reflection angle.

[0006] A projector according to one aspect of the present invention comprises an illumination device according to one aspect of the present invention, an optical modulation device that modulates light including the illumination light emitted from the illumination device, and a projection optical device that projects the light modulated by the optical modulation device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a projector according to a first embodiment. [Figure 2] 1 is a schematic configuration diagram of a lighting device according to a first embodiment. [Figure 3] FIG. 2 is a front view of the light diffusing device. [Figure 4] 4 is a cross-sectional view of the diffusion plate taken along line IV-IV in FIG. 3. [Figure 5] FIG. [Figure 6A] FIG. 4 is a perspective view of a portion of the diffusion plate corresponding to a first region. [Figure 6B] FIG. 10 is a perspective view of a portion of the diffusion plate corresponding to a second region. [Figure 6C] FIG. 10 is a perspective view of a portion of the diffusion plate corresponding to a third region. [Figure 7A] 10 is a diagram showing how illumination light is reflected when it is incident on a first region. FIG. [Figure 7B] 10 is a diagram showing how illumination light is reflected when it is incident on a second region. FIG. [Figure 7C] 10 is a diagram showing how illumination light is reflected when it is incident on a third region. FIG. [Figure 8] FIG. 10 is a perspective view of a diffusion plate according to a second embodiment. [Figure 9A] FIG. 4 is a perspective view of a portion of the diffusion plate corresponding to a first region. [Figure 9B] FIG. 10 is a perspective view of a portion of the diffusion plate corresponding to a second region. [Figure 9C] FIG. 10 is a perspective view of a portion of the diffusion plate corresponding to a third region. [Figure 9D] FIG. 10 is a perspective view of a portion of the diffusion plate corresponding to a fourth region. [Figure 9E] FIG. 10 is a perspective view of a portion of the diffusion plate corresponding to a fifth region. DETAILED DESCRIPTION OF THE INVENTION

[0008] [First embodiment] A first embodiment of the present invention will be described below with reference to the drawings. The projector of this embodiment is an example of a liquid crystal projector equipped with an illumination device using a laser diode. In the drawings below, the dimensions of the components may be shown on different scales to make them easier to see.

[0009] The projector 1 of this embodiment is a projection-type image display device that displays a color image on a screen (projection surface) SCR. The projector 1 is equipped with three light modulation devices corresponding to red light LR, green light LG, and blue light LB. The projector 1 is equipped with a laser diode that can obtain high-brightness, high-power light as a light-emitting element of the light source device.

[0010] FIG. 1 is a schematic configuration diagram of a projector 1 according to this embodiment. 1, the projector 1 includes an illumination device 2, a color separation and light-guiding optical system 3, a red light optical modulation device 4R, a green light optical modulation device 4G, a blue light optical modulation device 4B, a combining optical system 5, and a projection optical device 6. The red light optical modulation device 4R, the green light optical modulation device 4G, and the blue light optical modulation device 4B each form image light by modulating, in accordance with image information, each color light R, G, B obtained by separating illumination light WL emitted from the illumination device 2. The projection optical device 6 projects the image light onto a screen SCR (projection surface).

[0011] FIG. 2 is a schematic diagram of the lighting device 2. As shown in FIG. As shown in FIG. 2, the lighting device 2 includes a blue light source 20, a green light source 30, a red light source 40, a light combining member 50, a focusing element 60, a light diffusing device 70, a collimator element 80, a double-sided multi-lens array 90, and a superimposing lens 100.

[0012] In the following description, the axis along the emission direction of the colored lights LB and LR from the blue light source 20 and the red light source 40 is defined as the X axis, the axis along the emission direction of the illumination light WL from the light combining member 50 is defined as the Y axis, and the axis perpendicular to the X and Y axes is defined as the Z axis. Also, the axis that passes through the light-converging point P on the diffusing surface 71s of the diffuser 71 and is parallel to the X axis is defined as the optical axis AX1, and the axis that passes through the light-converging point P on the diffusing surface 71s and is parallel to the Y axis is defined as the optical axis AX2.

[0013] The blue light source 20 includes a blue laser diode array 21 and a first collimator lens array 22. The blue light source 20 of this embodiment corresponds to a first light source in the claims.

[0014] The blue laser diode array 21 has a plurality of blue laser diodes 211 arranged in an array. The blue laser diodes 211 emit a blue beam LB0 of a first wavelength band in the +X direction. The first wavelength band is, for example, 455 nm±10 nm. The number and arrangement of the blue laser diodes 211 are not particularly limited.

[0015] The first collimator lens array 22 is provided on the light emission side of the blue laser diode array 21. The first collimator lens array 22 has a plurality of collimator lenses 221 provided corresponding to each of the plurality of blue laser diodes 211. The collimator lenses 221 are made of convex lenses. The collimator lenses 221 collimate the blue beams LB0 emitted from the blue laser diodes 211. Hereinafter, the plurality of blue beams LB0 emitted from the first collimator lens array 22 will be collectively referred to as blue light LB. Therefore, the blue light LB is parallel light collimated by the first collimator lens array 22. The blue light LB in this embodiment corresponds to the first light in the claims.

[0016] Green light source 30 includes a green laser diode array 31 and a second collimator lens array 32. Green light source 30 of this embodiment corresponds to the second light source in the claims.

[0017] The green laser diode array 31 has a plurality of green laser diodes 311 arranged in an array. The green laser diodes 311 emit a green beam LG0 of a second wavelength band in the +Y direction. The second wavelength band is, for example, 535 nm±10 nm. The number and arrangement of the green laser diodes 311 are not particularly limited.

[0018] The second collimator lens array 32 is provided on the light emission side of the green laser diode array 31. The second collimator lens array 32 has a plurality of collimator lenses 321 provided corresponding to each of the plurality of green laser diodes 311. The collimator lenses 321 are composed of convex lenses. The collimator lenses 321 collimate the green beams LG0 emitted from the green laser diodes 311. Hereinafter, the plurality of green beams LG0 emitted from the second collimator lens array 32 will be collectively referred to as green light LG. Therefore, the green light LG is parallel light collimated by the second collimator lens array 32. The green light LG in this embodiment corresponds to the second light in the claims.

[0019] The red light source 40 includes a red laser diode array 41 and a third collimator lens array 42 .

[0020] The red laser diode array 41 has a plurality of red laser diodes 411 arranged in an array. The red laser diodes 411 emit a red beam LR0 in a third wavelength band in the -X direction. The third wavelength band is, for example, 640 nm±10 nm. The number and arrangement of the red laser diodes 411 are not particularly limited.

[0021] The third collimator lens array 42 is provided on the light emission side of the red laser diode array 41. The third collimator lens array 42 has a plurality of collimator lenses 421 provided corresponding to each of the plurality of red laser diodes 411. The collimator lenses 421 are made of convex lenses. The collimator lenses 421 collimate the red beams LR0 emitted from the red laser diodes 411. Hereinafter, the plurality of red beams LR0 emitted from the third collimator lens array 42 will be collectively referred to as red light LR. Therefore, the red light LR is parallel light that has been collimated by the third collimator lens array 42.

[0022] The number of blue laser diodes 211, the number of green laser diodes 311, and the number of red laser diodes 411 may be the same or different. By making the numbers of these laser diodes different from one another, it is possible to maximize the output of each laser diode while efficiently adjusting the white balance of the illumination light WL.

[0023] The light combining member 50 is composed of a cross dichroic prism. The cross dichroic prism has a first dichroic mirror 51 and a second dichroic mirror 52. The first dichroic mirror 51 reflects the red light LR and transmits the green light LG and blue light LB. The second dichroic mirror 52 reflects the blue light LB and transmits the green light LG and red light LR. As a result, the light combining member 50 combines the blue light LB emitted from the blue light source 20, the green light LG emitted from the green light source 30, and the red light LR emitted from the red light source 40, and emits white illumination light WL. Because the light emitted from each laser diode is linearly polarized, the illumination light WL emitted from the light combining member 50 is also linearly polarized.

[0024] The light-collecting element 60 is disposed between the light combining member 50 and the light diffusing device 70. The light-collecting element 60 is composed of a convex lens. The light-collecting element 60 collects the illumination light WL emitted from the light combining member 50 toward the diffusion plate 71 of the light diffusing device 70. The light-collecting element 60 is disposed at a position where the optical axis of the light-collecting element 60 coincides with the optical axis AX2.

[0025] The light diffusion device 70 includes a disk-shaped diffuser plate 71 and a driving device 72. The diffuser plate 71 has a diffusing surface 71s that diffuses and reflects the illumination light WL emitted from the light collecting element 60. That is, the diffuser plate 71 of this embodiment is a reflective diffuser plate rather than a transmissive diffuser plate. The diffuser plate 71 is disposed at a position where any one point on the diffusing surface 71s intersects with each of the optical axes AX1 and AX2. The diffusing surface 71s of the diffuser plate 71 is disposed at a focal point P of the illumination light WL emitted from the light collecting element 60. In other words, the focal point of the convex lens constituting the light collecting element 60 is located on the diffusing surface 71s of the diffuser plate 71.

[0026] The driving device 72 is composed of a motor, and rotates the diffuser plate 71 about a rotation axis C1 that intersects with the diffusing surface 71s. By rotating the diffuser plate 71, speckle noise that tends to occur when a laser diode is used can be reduced.

[0027] Fig. 3 is a front view of the light diffusion device 70. Fig. 4 is a cross-sectional view of the diffusion plate 71 taken along line IV-IV in Fig. 3. As shown in FIGS. 3 and 4, the diffusion plate 71 has a substrate 710, a metal reflective film 711, and a dielectric multilayer film 712.

[0028] The substrate 710 is a light-transmitting substrate made of optical glass such as BK7. Of the two surfaces of the substrate 710, the diffusion surface 71s onto which the illumination light WL is incident is provided with an uneven structure 713 consisting of multiple recesses and multiple protrusions. The uneven structure 713 includes multiple curved surfaces with random diameters and depths. That is, the substrate 710 has the uneven structure 713 including multiple recesses and multiple protrusions. Each recess is formed in a substantially spherical shape. The depth of the recess is, for example, approximately 1 / 4 of the diameter of the sphere. The uneven structure 713 can be formed by, for example, scraping the substrate 710 by etching or plastically deforming it by blasting. Note that the diffuser plate 71 may have an uneven structure with regularly-spaced diameters and depths instead of a randomly-spaced uneven structure, such as a microlens array-type diffuser plate with regularly-spaced small lens surfaces.

[0029] The metal reflective film 711 is provided along the concave-convex structure 713 of the substrate 710. The metal reflective film 711 is made of a material containing aluminum, for example. Specifically, the metal reflective film 711 is made of high-purity aluminum with an aluminum content of 99.99 wt% or more. Preferably, the metal reflective film 711 can be made of ultra-high-purity aluminum with an aluminum content of 99.999 wt% or more.

[0030] The metal reflective film 711 is obtained by forming a pure aluminum film with a smooth surface and a predetermined film thickness using a film formation method such as sputtering or vapor deposition on the diffusion surface 71s of the substrate 710. When a sputtering target with an aluminum content of, for example, 99.999 wt% is used in the film formation process, the metal reflective film 711 made of ultra-high purity aluminum with an aluminum content of 99.999 wt% is obtained.

[0031] The dielectric multilayer film 712 is provided on the surface of the metal reflective film 711 opposite to the substrate 710. That is, the diffuser 71 has a configuration in which the metal reflective film 711 and the dielectric multilayer film 712 are laminated in this order on the substrate 710. Although not shown in Fig. 4, the dielectric multilayer film 712 has a configuration in which two types of dielectric films having different refractive indices are alternately laminated multiple times.

[0032] In the diffuser plate 71 of this embodiment, the uneven structure 713 reflects the illumination light WL emitted from the concentrating element 60 once and emits it toward the collimator element 80. Therefore, the illumination light WL emitted from the concentrating element 60 is emitted from the diffuser plate 71 toward the collimator element 80 without being multiple-reflected on the diffusing surface 71s. With this configuration, the illumination light WL emitted from the concentrating element 60 is not multiple-reflected on the diffusing surface 71s, and therefore disturbance in the polarization direction of the illumination light WL due to diffusion of the illumination light WL can be suppressed.

[0033] In this specification, the diffusion surface 71s does not mean a concave-convex surface that follows the shape of the fine concave-convex structure, but means a virtual plane of the entire area where a plurality of concave portions and a plurality of convex portions are arranged. For example, considering that the diameter of the diffusion plate is on the order of several tens of mm, the thickness of the diffusion plate is on the order of several mm, and the depth of the concave-convex structure is on the order of several μm, the surface where a plurality of concave portions and a plurality of convex portions are arranged can be considered to be a substantially flat surface.

[0034] 4, the diffuser 71 may have a configuration in which the metal reflective film 711 is not provided, and the dielectric multilayer film 712 is formed directly on the uneven structure 713 of the substrate 710. This configuration can simplify the manufacturing process of the diffuser. In contrast to this configuration, if the metal reflective film 711 is provided, the reflective function can be performed by both the metal reflective film 711 and the dielectric multilayer film 712, and the number of layers in the dielectric multilayer film 712 can be reduced.

[0035] Alternatively, the substrate 710 may be a metal substrate. For example, an aluminum alloy can be used as the metal substrate. For example, an Al-Mg-Si alloy in which magnesium (Mg) and silicon (Si) are added to aluminum (Al) can be used as the aluminum alloy. In addition, the aluminum alloy may contain elements such as iron (Fe), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), and titanium (Ti). In this case, a blasting treatment is performed on the metal substrate to form a concave-convex structure on one surface of the metal substrate, and the dielectric multilayer film 712 is then formed on the concave-convex structure. This configuration can simplify the configuration of the diffusion plate.

[0036] Fig. 5 is a perspective view of diffuser plate 71. Fig. 6A is a perspective view of a portion of diffuser plate 71 corresponding to first region 71A. Fig. 6B is a perspective view of a portion of diffuser plate 71 corresponding to second region 71B. Fig. 6C is a perspective view of a portion of diffuser plate 71 corresponding to third region 71C. 5, the diffusion surface 71s of the diffuser plate 71 is divided into three regions along the circumferential direction of the diffuser plate 71, including a first region 71A, a second region 71B, and a third region 71C. That is, the first region 71A, the second region 71B, and the third region 71C are arranged in the circumferential direction of the diffuser plate 71. Therefore, when the diffuser plate 71 rotates, for example, counterclockwise as viewed from the diffusion surface 71s side, the incident position of the illumination light WL emitted from the light collecting element 60 onto the diffuser plate 71 changes over time in the order of the first region 71A → the second region 71B → the third region 71C → the first region 71A → ...

[0037] As shown in FIG. 6A, in the first region 71A, the thickness of the diffuser plate 71 is constant regardless of the position within the first region 71A. In contrast, in the second region 71B and the third region 71C, the thickness of the diffuser plate 71 varies along the radial direction of the diffuser plate 71. As shown in FIG. 6B, in the second region 71B, the thickness of the diffuser plate 71 gradually decreases from the outer periphery toward the center of the diffuser plate 71. As shown in FIG. 6C, in the third region 71C, the thickness of the diffuser plate 71 gradually increases from the outer periphery toward the center of the diffuser plate 71, in contrast to the second region 71B. As a result, as shown in FIG. 5, the gradient along the radial direction of the diffusion surface 71s differs from region to region.

[0038] 6A to 6C, in order to make it easier to see the shape of each of the regions 71A, 71B, and 71C of the diffuser plate 71, the regions 71A, 71B, and 71C are shown separated from each other. When actually manufacturing the diffuser plate 71, as shown in FIGS. 6A to 6C, the diffuser plate may be separated into regions and then bonded together using an optical adhesive or the like. Alternatively, a diffuser plate made of an integral member may be manufactured using techniques such as cutting and polishing.

[0039] Fig. 7A is a diagram showing how the illumination light WL is reflected when it is incident on the first region 71A. Fig. 7B is a diagram showing how the illumination light WL is reflected when it is incident on the second region 71B. Fig. 7C is a diagram showing how the illumination light WL is reflected when it is incident on the third region 71C. As shown in FIG. 7A, assuming an imaginary plane K perpendicular to the rotation axis C1 of the diffuser plate 71, the diffusion surface 71s of the first region 71A is not inclined with respect to the imaginary plane K but is parallel to the imaginary plane K. In contrast, as shown in FIG. 7B, the diffusion surface 71s of the second region 71B is inclined in a direction toward the center in the radial direction with respect to the imaginary plane K. As shown in FIG. 7C, the diffusion surface 71s of the third region 71C is inclined in a direction toward the outer periphery in the radial direction with respect to the imaginary plane K, opposite to the diffusion surface 71s of the second region 71B. In other words, at least two of the diffusion surface 71s of the first region 71A, the diffusion surface 71s of the second region 71B, and the diffusion surface 71s of the third region 71C are inclined with respect to the imaginary plane K. Furthermore, if the first tilt angle of the diffusion surface 71s in the first region 71A with respect to the imaginary plane K is 0°, the first tilt angle of the diffusion surface 71s in the first region 71A, the second tilt angle β2 of the diffusion surface 71s in the second region 71B, and the third tilt angle β3 of the diffusion surface 71s in the third region 71C are different from one another. The second tilt angle β2 and the third tilt angle β3 have opposite signs with respect to the imaginary plane K.

[0040] As shown in FIG. 7A , the diffuser 71 is positioned so that the illumination light WL emitted from the condensing element 60 is incident at an incident angle of 45° during the first period in which the illumination light WL is incident on the first region 71A. Therefore, the illumination light WL is reflected at a reflection angle of 45° on the diffusion surface 71s of the first region 71A. Note that the reflection angle on the diffusion surface 71s of the first region 71A does not have to be exactly 45°; it may be 45°±2°. In this case, the central axis WL0 of the illumination light WL reflected on the diffusion surface 71s coincides with the optical axis AX1. In other words, the illumination light WL reflected on the diffusion surface 71s is incident along the optical axis of the collimator element 80. The 45° angle in this embodiment corresponds to the first reflection angle in the claims. Note that the reflection angle in this specification is the angle between the normal to the diffusion surface and the central axis of the reflected illumination light on the light incident surface perpendicular to the diffusion surface, and is a reflection angle that follows the general optical definition.

[0041] As shown in FIG. 7B , during the second period in which the illumination light WL is incident on the second region 71B, the diffusing surface 71s is tilted toward the center in the radial direction, so the incident angle of the illumination light WL is smaller than 45°. Therefore, the reflection angle of the illumination light WL reflected by the diffusing surface 71s of the second region 71B is also smaller than 45°. If the change in the reflection angle from 45° is α1, the reflection angle of the illumination light WL on the second region 71B can be expressed as 45°-α1. In this embodiment, α1 is, for example, 5°. Therefore, the reflection angle of the illumination light WL on the second region 71B is 40°. In this case, the central axis WL0 of the illumination light WL reflected on the diffusing surface 71s is tilted toward the -Y side with respect to the optical axis AX1. That is, the central axis WL0 of the illumination light WL reflected on the diffusing surface 71s is incident on the collimator element 80 at a predetermined angle tilted toward the -Y side with respect to the optical axis of the collimator element 80. When α1 is 5°, the angular deviation of the central axis WL0 of the illumination light WL incident on the collimator element 80 from the optical axis AX1 is approximately 2 to 3°. In this embodiment, 45°-α1 corresponds to the second reflection angle in the claims. α1 is preferably 1° or greater and 25° or less. More preferably, by setting α1 to 2° or greater and 10° or less, speckle noise in a projected image (described later) can be efficiently reduced, and the illumination light WL diffused by the collimator element 80, which is disposed downstream of the light path of the light diffuser 70, can be efficiently absorbed, thereby preventing the collimator element 80 from becoming larger.

[0042] As shown in FIG. 7C , during the third period in which the illumination light WL is incident on the third region 71C, the diffusing surface 71s is tilted toward the radially outer periphery, resulting in an incident angle of the illumination light WL greater than 45°. Therefore, the reflection angle of the illumination light WL reflected by the diffusing surface 71s in the third region 71C is also greater than 45°. The change in the reflection angle from 45° in the third region 71C may be different from, but is preferably the same as, the change in the reflection angle from 45° in the second region 71B. Therefore, if the change in the reflection angle from 45° is α1, the same as in the second region 71B, the reflection angle of the illumination light WL in the third region 71C can be expressed as 45° + α1. Therefore, the reflection angle of the illumination light WL in the third region 71C is 50°. In this case, the central axis WL0 of the illumination light WL reflected by the diffusing surface 71s is tilted toward the +Y side with respect to the optical axis AX1. That is, the illumination light WL reflected by the diffusing surface 71s is incident at a predetermined angle tilted toward the +Y side with respect to the optical axis of the collimator element 80. The angle of 45°+α1 in this embodiment corresponds to the third reflection angle in the claims.

[0043] 2, the collimator element 80 is provided on the light exit side of the diffuser plate 71 on the optical axis AX1. The collimator element 80 is made up of a convex lens. The collimator element 80 collimates the illumination light WL that is emitted from the diffuser plate 71 at a predetermined diffusion angle, and emits the collimated light toward the double-sided multi-lens array 90. The collimator element 80 is disposed at a position where the optical axis of the collimator element 80 coincides with the optical axis AX1.

[0044] As described above, in the first period, the illumination light WL reflected by the diffuser plate 71 is incident on the collimator element 80 along its optical axis, and therefore, as shown in Fig. 7A, the central axis WL0 of the illumination light WL emitted from the collimator element 80 coincides with the optical axis AX1. In contrast, in the second period, the illumination light WL reflected by the diffuser plate 71 is incident on the collimator element 80 at an angle toward the -Y side with respect to the optical axis, and therefore, as shown in Fig. 7B, the central axis WL0 of the illumination light WL emitted from the collimator element 80 shifts toward the -Y side with respect to the optical axis AX1. Furthermore, in the third period, the illumination light WL reflected by the diffuser plate 71 is incident on the collimator element 80 at an angle toward the +Y side with respect to the optical axis, and therefore, as shown in Fig. 7C, the central axis WL0 of the illumination light WL emitted from the collimator element 80 shifts toward the +Y side with respect to the optical axis AX1.

[0045] The double-sided multi-lens array 90 and the superimposing lens 100 constitute an integrator optical system. The integrator optical system homogenizes the illuminance distribution of the illumination light WL emitted from the collimator element 80 in the image forming areas of the red light optical modulator 4R, the green light optical modulator 4G, and the blue light optical modulator 4B.

[0046] The double-sided multi-lens array 90 is provided on the light-emitting side of the collimator element 80 on the optical axis AX1. The double-sided multi-lens array 90 is a multi-lens array in which a first multi-lens surface 90a and a second multi-lens surface 90b are integrated into a single member. The first multi-lens surface 90a has a plurality of lenses for splitting the illumination light WL emitted from the collimator element 80 into a plurality of partial light beams. The plurality of lenses are arranged in a matrix in a plane perpendicular to the optical axis AX1.

[0047] The second multi-lens surface 90b has a plurality of lenses corresponding to the plurality of lenses of the first multi-lens surface 90a. The second multi-lens surface 90b, together with the superimposing lens 100 at the subsequent stage, forms images of the lenses of the first multi-lens surface 90a on or near the image forming areas of the red light optical modulator 4R, the green light optical modulator 4G, and the blue light optical modulator 4B. The lenses are arranged in a matrix in a plane perpendicular to the optical axis AX1. The first multi-lens surface 90a and the second multi-lens surface 90b may be provided as two separate multi-lens arrays. A driving device may also be provided to vibrate or swing the double-sided multi-lens array 90 in a direction perpendicular to the optical axis AX1 (a direction along the XZ plane). Vibrating or swinging the double-sided multi-lens array 90 further reduces speckle noise, which is likely to occur when using laser diodes.

[0048] The superimposing lens 100 focuses each of the multiple partial beams emitted from the double-sided multi-lens array 90 and superimposes them on each other in or near the image forming areas of each of the red light optical modulator 4R, the green light optical modulator 4G, and the blue light optical modulator 4B.

[0049] 1, the color separation and light-guiding optical system 3 includes a first dichroic mirror 7a, a second dichroic mirror 7b, a first reflecting mirror 8a, a second reflecting mirror 8b, a third reflecting mirror 8c, a first relay lens 9a, and a second relay lens 9b. The color separation and light-guiding optical system 3 separates the white illumination light WL emitted from the illumination device 2 into red light R, green light G, and blue light B, and guides the red light R, green light G, and blue light B to the corresponding red light optical modulator 4R, green light optical modulator 4G, and blue light optical modulator 4B, respectively.

[0050] A field lens 10R is disposed between the color separation and light-guiding optical system 3 and the red light optical modulation device 4R. A field lens 10G is disposed between the color separation and light-guiding optical system 3 and the green light optical modulation device 4G. A field lens 10B is disposed between the color separation and light-guiding optical system 3 and the blue light optical modulation device 4B.

[0051] The first dichroic mirror 7a transmits red light R and reflects green light G and blue light B. The second dichroic mirror 7b reflects green light G and transmits blue light B. The first reflecting mirror 8a reflects red light R. The second reflecting mirror 8b and the third reflecting mirror 8c each reflect blue light B. The first relay lens 9a and the second relay lens 9b are each disposed on the optical path of the blue light B to suppress loss of the blue light B.

[0052] The red light optical modulation device 4R is composed of a liquid crystal panel that modulates red light R according to image information to form an image. The green light optical modulation device 4G is composed of a liquid crystal panel that modulates green light G according to image information to form an image. The blue light optical modulation device 4B is composed of a liquid crystal panel that modulates blue light B according to image information to form an image.

[0053] Although not shown in the figure, incident-side polarizing plates are arranged between field lens 10R and red light optical modulator 4R, between field lens 10G and green light optical modulator 4G, and between field lens 10B and blue light optical modulator 4B. Exit-side polarizing plates are arranged between red light optical modulator 4R and combining optical system 5, between green light optical modulator 4G and combining optical system 5, and between blue light optical modulator 4B and combining optical system 5. Note that the incident-side polarizing plates do not need to be provided if polarization disturbance caused by the optical system after emission from illumination device 2 is tolerable.

[0054] The combining optical system 5 combines the image lights emitted from the red light optical modulator 4R, the green light optical modulator 4G, and the blue light optical modulator 4B. The combining optical system 5 is composed of a cross dichroic prism that is formed by bonding four right-angle prisms together and has a substantially square shape in a plan view. In the cross dichroic prism, a dielectric multilayer film is provided at the substantially X-shaped interface where the right-angle prisms are bonded together.

[0055] The image light emitted from the combining optical system 5 is enlarged and projected onto a screen SCR by a projection optical device 6. The projection optical device 6 is made up of a plurality of lenses.

[0056] [Effects of the first embodiment] The illumination device 2 of this embodiment includes a blue light source 20 that emits blue light LB, a green light source 30 that emits green light LG, a red light source 40 that emits red light LR, a light combining member 50 that combines the blue light LB, the green light LG, and the red light LR to emit illumination light WL, a light diffusing device 70 that diffuses and reflects the illumination light WL emitted from the light combining member 50, a focusing element 60 that is disposed between the light combining member 50 and the light diffusing device 70 and focuses the illumination light WL emitted from the light combining member 50 toward the light diffusing device 70, and a collimator element 80 that collimates the illumination light WL emitted from the light diffusing device 70. The light diffusing device 70 includes a diffuser plate 71 that includes a diffusion surface 71s that diffuses and reflects the illumination light WL, and a drive device 72 that rotates the diffuser plate 71 about a rotation axis C1. The diffusing surface 71s has a first region 71A where the illumination light WL is reflected at a first reflection angle, a second region 71B arranged in the circumferential direction of the diffusing plate 71 relative to the first region 71A where the illumination light WL is reflected at a second reflection angle different from the first reflection angle, and a third region 71C arranged in the circumferential direction of the diffusing plate 71 relative to the first region 71A and the second region 71B where the illumination light WL is reflected at a third reflection angle different from the first reflection angle and the second reflection angle.

[0057] In the illumination device 2 of this embodiment, the diffuser plate 71 rotates, causing the incident position of the illumination light WL on the diffusion surface 71s to change over time across the first region 71A, the second region 71B, and the third region 71C. Accordingly, as shown in FIGS. 7A to 7C , the angle between the central axis WL0 of the illumination light WL incident on the collimator element 80 and the optical axis of the collimator element 80 changes over time. Therefore, the illumination light WL emitted from the collimator element 80 shifts over time in a direction (the Y-axis direction) perpendicular to the optical axis of the collimator element 80. This causes the position of the illumination light WL incident on the double-sided multi-lens array 90 to change over time, resulting in a temporal change in the spatial distribution of the illumination light WL emitted from the double-sided multi-lens array 90. This causes different speckle patterns on the screen SCR to change over time, resulting in the different speckle patterns being superimposed on the observer's eye, making speckle noise less noticeable. In this way, speckle noise can be efficiently reduced.

[0058] From the viewpoint of display quality, it is desirable that the reflection angle of the illumination light WL at the diffuser 71 is basically 45°. When the reflection angle is 45°, the illumination light WL is incident along the optical axis of the collimator element 80. Therefore, after the illumination light WL is separated into three colored lights R, G, and B, each colored light R, G, and B is incident perpendicularly to each liquid crystal panel. In contrast, when the reflection angle is other than 45°, the illumination light WL is incident at an angle to the optical axis of the collimator element 80. Therefore, after the illumination light WL is separated into three colored lights R, G, and B, each colored light R, G, and B is incident at an angle to the normal direction of each liquid crystal panel. As a result, unevenness in the brightness and contrast of the image may occur.

[0059] To address this issue, in the illumination device 2 of this embodiment, the first reflection angle in the first region 71A of the diffuser 71 is 45°, the second reflection angle in the second region 71B is 45°-α1, and the third reflection angle in the third region 71C is 45°+α1. With this configuration, even if unevenness in brightness or contrast occurs during the period when the illumination light WL is incident on the second region 71B or the third region 71C, the absolute values ​​of the deviations from 45° of the second and third reflection angles are equal and opposite in sign, so the unevenness in brightness and contrast is canceled out. As a result, a projected image with less unevenness in image brightness and contrast and less speckle noise can be obtained. In particular, in this embodiment, α1 is 5°, so unevenness in image brightness and contrast can be appropriately suppressed while still achieving a sufficient speckle noise reduction effect.

[0060] Furthermore, from the viewpoint of suppressing unevenness in image brightness and contrast, it is desirable that the areas of the second region 71B and the third region 71C are equal to each other. The areas of the second region 71B and the third region 71C being equal to each other do not necessarily have to be completely equal to each other, and include a case where the difference in the areas of the two regions is 10% or less of the area of ​​one region. When the areas of the second region 71B and the third region 71C are equal to each other, the length of the second period during which the illumination light WL is reflected at the second reflection angle and the length of the third period during which the illumination light WL is reflected at the third reflection angle are equal to each other. This further facilitates canceling out unevenness in image brightness and contrast. Furthermore, in this case, the area of ​​the first region 71A may be larger than the areas of the second region 71B and the third region 71C. This minimizes the effects of unevenness in image brightness and contrast. Furthermore, if the unevenness described above does not pose a problem, the area of ​​the first region 71A, the area of ​​the second region 71B, and the area of ​​the third region 71C may be different from one another.

[0061] The projector 1 of this embodiment includes the lighting device 2 of this embodiment, light modulation devices 4R, 4G, and 4B that modulate the illumination light WL emitted from the lighting device 2 according to image information, and a projection optical device 6 that projects the light modulated by the light modulation devices 4R, 4G, and 4B.

[0062] This configuration makes it possible to realize a projector 1 with excellent display quality.

[0063] [Second embodiment] A second embodiment of the present invention will be described below with reference to the drawings. The basic configurations of the projector and lighting device of the second embodiment are the same as those of the first embodiment, but the configuration of the diffusion plate is different from that of the first embodiment, so a description of the basic configurations of the projector and lighting device will be omitted.

[0064] Fig. 8 is a perspective view of diffuser plate 75. Fig. 9A is a perspective view of a portion of diffuser plate 75 corresponding to first region 75A. Fig. 9B is a perspective view of a portion of diffuser plate 75 corresponding to second region 75B. Fig. 9C is a perspective view of a portion of diffuser plate 75 corresponding to third region 75C. Fig. 9D is a perspective view of a portion of diffuser plate 75 corresponding to fourth region 75D. Fig. 9E is a perspective view of a portion of diffuser plate 75 corresponding to fifth region 75E.

[0065] As shown in FIG. 8 , the diffusing surface 75s of the diffuser 75 is divided into five regions along the circumferential direction of the diffuser 75: a first region 75A, a second region 75B, a third region 75C, a fourth region 75D, and a fifth region 75E. The five regions are arranged in the following order when viewed clockwise from the diffusing surface 75s side of the diffuser 75, with the first region 75A as the reference: second region 75B, fourth region 75D, fifth region 75E, and third region 75C. Therefore, as the diffuser 75 rotates counterclockwise, the incident position of the illumination light WL on the diffuser 75 changes over time in the following order: first region 75A → second region 75B → fourth region 75D → fifth region 75E → third region 75C → first region 75A → ... Note that these regions do not necessarily have to be arranged in the above order, and other diffusing regions may be interposed between these regions.

[0066] As shown in FIG. 9A, the thickness of the diffuser plate 75 in the first region 75A is constant regardless of the position within the first region 75A. In contrast, as shown in FIG. 9B, the thickness of the diffuser plate 75 in the second region 75B gradually decreases from the periphery toward the center of the diffuser plate 75. As shown in FIG. 9C, the thickness of the diffuser plate 75 in the third region 75C gradually increases from the periphery toward the center, in contrast to the second region 75B. As shown in FIG. 9D, the thickness of the diffuser plate 75 in the fourth region 75D gradually decreases from the periphery toward the center, similar to the second region 75B. Furthermore, the radial gradient of the diffusion surface 75s in the fourth region 75D is greater than the radial gradient of the diffusion surface 75s in the second region 75B. As shown in FIG. 9E, the thickness of the diffuser plate 75 in the fifth region 75E gradually increases from the periphery toward the center of the diffuser plate 75, similar to the third region 75C. Furthermore, the gradient of the diffusion surface 75s in the fifth region 75E along the radial direction is greater than the gradient of the diffusion surface 75s in the third region 75C along the radial direction.

[0067] The diffuser plate 75 is disposed at an angle such that the illumination light is incident at an incident angle of 45° during a first period in which the illumination light is incident on the first region 75A. As a result, the illumination light is reflected at a reflection angle of 45° on the diffusion surface 75s of the first region 75A. The 45° in this embodiment corresponds to the first reflection angle in the claims.

[0068] During a second period in which the illumination light is incident on the second region 75B, the diffusing surface 75s of the second region 75B is tilted toward the center in the radial direction, so the angle of incidence of the illumination light is smaller than 45°. Therefore, the angle of reflection of the illumination light reflected by the diffusing surface 75s is also smaller than 45°. If the amount of change in the reflection angle from 45° is α1, the angle of reflection of the illumination light on the second region 75B can be expressed as 45°-α1. In this embodiment, α1 is, for example, 2.5°. Therefore, the angle of reflection of the illumination light on the second region 75B is 42.5°. In this embodiment, 45°-α1 corresponds to the second reflection angle in the claims. As in the first embodiment, α1 is preferably greater than or equal to 1° and less than or equal to 25°. More preferably, by setting α1 to be between 2° and 10°, speckle noise in the projected image can be efficiently reduced, and the illumination light WL diffused by the collimator element 80 arranged downstream of the optical path of the light diffusion device 70 can be efficiently absorbed, thereby preventing the collimator element 80 from becoming larger.

[0069] During the third period in which the illumination light is incident on the fourth region 75D, the diffusing surface 75s is tilted toward the center in the radial direction, so the incident angle of the illumination light is smaller than 45°, as in the second period. However, because the tilt of the diffusing surface 75s in the fourth region 75D is larger than the tilt of the diffusing surface 75s in the second region 75B, the reflection angle of the illumination light in the fourth region 75D is smaller than the reflection angle of the illumination light in the second region 75B. If the change in the reflection angle from 45° is α2, the reflection angle of the illumination light in the fourth region 75D can be expressed as 45°-α2. In this embodiment, α2 is larger than α1, for example, 5°. Therefore, the reflection angle of the illumination light in the fourth region 75D is 40°. In this embodiment, 45°-α2 corresponds to the fourth reflection angle in the claims. Note that α2 is preferably greater than α1 and is between 1° and 25°. More preferably, by setting α2 to be between 2° and 10°, speckle noise in the projected image can be efficiently reduced, and the illumination light WL diffused by the collimator element 80 arranged downstream of the optical path of the light diffusion device 70 can be efficiently absorbed, thereby preventing the collimator element 80 from becoming larger.

[0070] During the fourth period in which the illumination light is incident on the fifth region 75E, the diffusion surface 75s is tilted toward the radially outer periphery, so the angle of incidence of the illumination light is greater than 45°. Therefore, the angle of reflection of the illumination light reflected by the diffusion surface 75s is also greater than 45°. The change in the reflection angle from 45° in the fifth region 75E may be different from the change in the reflection angle from 45° in the fourth region 75D, but it is desirable that they be the same. Therefore, if the change in the reflection angle from 45° is α2, the same as in the fourth region 75D, the reflection angle of the illumination light in the fifth region 75E can be expressed as 45° + α2. Therefore, the reflection angle of the illumination light in the fifth region 75E is 50°. In this embodiment, 45° + α2 corresponds to the fifth reflection angle in the claims.

[0071] During the fifth period when the illumination light is incident on the third region 75C, the diffusing surface 75s is tilted radially outward, so the angle of incidence of the illumination light is greater than 45°, as in the fourth period. However, because the tilt of the diffusing surface 75s in the third region 75C is smaller than the tilt of the diffusing surface 75s in the fifth region 75E, the reflection angle of the illumination light in the third region 75C is smaller than the reflection angle of the illumination light in the fifth region 75E. The change in the reflection angle from 45° in the third region 75C may be different from, but is preferably the same as, the change in the reflection angle from 45° in the second region 75B. Therefore, if the change in the reflection angle from 45° is α1, the same as in the second region 75B, the reflection angle of the illumination light in the third region 75C can be expressed as 45° + α1. Therefore, the reflection angle of the illumination light in the third region 75C is 47.5°. In this embodiment, 45°+α1 corresponds to the third reflection angle in the claims.

[0072] As for the area of ​​each region, as described in the first embodiment, from the viewpoint of suppressing unevenness in image brightness and contrast, it is desirable that the area of ​​second region 75B and the area of ​​third region 75C are equal to each other, and it is desirable that the area of ​​fourth region 75D and the area of ​​fifth region 75E are equal to each other. Note that the above-mentioned case where the areas of two regions are equal to each other also includes a case where the difference between the areas of the two regions is 10% or less of the area of ​​one region. It is desirable that the area of ​​first region 75A is larger than the areas of the other four regions. It is desirable that the area of ​​second region 75B and the area of ​​third region 75C are larger than the area of ​​fourth region 75D and the area of ​​fifth region 75E, respectively. Taking the above conditions into consideration, as an example, the area of ​​the first region 75A can be set to 1 / 2 of the total area of ​​the diffuser plate 75, the area of ​​each of the second region 75B and the third region 75C can be set to 1 / 6 of the total area of ​​the diffuser plate 75, and the area of ​​each of the fourth region 75D and the fifth region 75E can be set to 1 / 12 of the total area of ​​the diffuser plate 75.

[0073] [Effects of the second embodiment] In this embodiment, different speckle patterns change over time, and so the same effect as in the first embodiment can be obtained, that is, speckle noise can be efficiently reduced.

[0074] In this embodiment, the reflection angle of the illumination light in the first region 75A is 45°, the reflection angle of the illumination light in the second region 75B is 45°-α1, the reflection angle of the illumination light in the third region 75C is 45°+α1, the reflection angle of the illumination light in the fourth region 75D is 45°-α2, and the reflection angle of the illumination light in the fifth region 75E is 45°+α2. The areas of the second region 75B and the third region 75C are equal to each other, and the areas of the fourth region 75D and the fifth region 75E are equal to each other. This configuration cancels out unevenness in brightness and contrast caused by the central axis of the illumination light being tilted with respect to the optical axis of the collimator element. This provides the same effects as the first embodiment, such as making unevenness in image brightness and contrast less visible and producing a projected image with less speckle noise.

[0075] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. In the diffuser plate of the above embodiment, the thickness of the diffuser plate varies along the radial direction of the diffuser plate in regions where the reflection angle is other than 45°. Alternatively, although not shown, the thickness of the diffuser plate may vary along the circumferential direction (arc) of the diffuser plate in regions where the reflection angle is other than 45°. With this configuration, the diffusing surface in these regions is inclined not only in the radial direction of the diffuser plate as in the above embodiment, but also in the circumferential direction of the diffuser plate. In this case, the first inclination angle of the diffusing surface in the first region relative to an imaginary plane perpendicular to the rotation axis is different from the second inclination angle of the diffusing surface in the second region relative to the imaginary plane. Furthermore, the third inclination angle of the diffusing surface in the first region relative to the imaginary plane is different from the fourth inclination angle of the diffusing surface in the second region relative to the imaginary plane. Here, the first and second inclination angles are inclination angles along the radial direction of the diffuser plate, and the third and fourth inclination angles are inclination angles along the circumferential direction of the diffuser plate. 7A to 7C of the first embodiment, the central axis of the illumination light is shifted in the Y-axis direction relative to the optical axis AX1, and also in the Z-axis direction, which is the direction perpendicular to the paper surface of FIGS. 7A to 7C. This further enhances the speckle noise reduction effect.

[0076] Although this presents a problem in that the design and manufacture of the diffuser plate is difficult, it is also possible to configure the diffusing surface in each region to be inclined only in the circumferential direction of the diffuser plate, and not in the radial direction of the diffuser plate. In this case, in Figures 7A to 7C, the central axis of the illumination light is shifted only in the Z-axis direction with respect to the optical axis AX1. With this configuration, speckle noise can be reduced, as in the above embodiment.

[0077] The diffusion characteristics of the multiple regions may be different from each other. When the diffusion characteristics of the multiple regions are different from each other, the speckle pattern changes not only due to the shift of the illumination light but also due to the difference in diffusion characteristics. This can further enhance the speckle noise reduction effect. Note that "diffusion characteristics are different from each other" means that the uneven structures provided in each region are different from each other. Specifically, "diffusion characteristics are different from each other" means that the pitch or curvature radius of the small lens surfaces formed in the uneven structure are different from each other, or one region has an uneven structure consisting of regularly arranged small lens surfaces, while another region has an uneven structure consisting of randomly arranged uneven surfaces.

[0078] Conversely, the diffusion characteristics of the multiple regions may be the same. If the diffusion characteristics of the multiple regions are the same, it is only necessary to form a uniform uneven structure over the entire diffusion surface regardless of the region, which makes it easier to manufacture the diffuser plate. Note that "diffusion characteristics are the same" means that the uneven structures provided in each region are the same. Specifically, "diffusion characteristics are the same" means that the pitch, radius of curvature, and arrangement of the small lens surfaces formed in the uneven structure are the same, or, in the case of a random uneven structure, the random patterns are the same.

[0079] In the first embodiment, the diffusing surface has three regions, and in the second embodiment, the diffusing surface has five regions. However, to reduce speckle noise, the diffusing surface only needs to have at least two regions, and the reflection angles of the two regions on the diffusing surface need to be different from each other. In the example of the first embodiment, the diffusing surface only needs to have any two of the following three regions: a region with a reflection angle of 45°, a region with a reflection angle of 45°-α1, and a region with a reflection angle of 45°+α1. However, to reduce speckle noise and also reduce unevenness in brightness and contrast, it is desirable that the number of regions be an odd number greater than or equal to three, and that the number of regions on the side with a reflection angle smaller than 45° be equal to the number of regions on the side with a reflection angle larger than 45°.

[0080] In addition, the specific descriptions of the shape, number, arrangement, materials, etc. of each component of the lighting device and the projector are not limited to the above embodiments and can be modified as appropriate. Furthermore, in the above embodiments, an example was shown in which the lighting device of the present invention is mounted on a projector using a liquid crystal panel, but this is not limiting. The lighting device of the present invention may also be applied to a projector that uses a digital micromirror device as a light modulation device. Furthermore, the projector does not need to have multiple light modulation devices, and may be a single-panel projector that has only one light modulation device.

[0081] In the above embodiment, the illumination device of the present invention is applied to a projector, but the present invention is not limited to this. The illumination device of the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

[0082] Summary of this disclosure A summary of this disclosure is provided below.

[0083] (Appendix 1) a first light source that emits first light in a first wavelength band; a second light source that emits second light in a second wavelength band different from the first wavelength band; a light combining member that combines the first light and the second light to emit illumination light; a light diffusing device that diffuses and reflects the illumination light emitted from the light combining member; a focusing element disposed between the light combining member and the light diffusing device, which focuses the illumination light emitted from the light combining member toward the light diffusing device; a collimator element that collimates the illumination light emitted from the light diffusing device; Equipped with the light diffusion device includes a diffusion plate including a diffusion surface that diffuses and reflects the illumination light, and a drive device that rotates the diffusion plate around a rotation axis; an illumination device, wherein the diffusing surface has a first region where the illumination light is reflected at a first reflection angle, and a second region arranged in a circumferential direction of the diffusing plate relative to the first region, where the illumination light is reflected at a second reflection angle different from the first reflection angle.

[0084] According to the configuration of Supplementary Note 1, due to the rotation of the diffuser plate, there are periods when the illumination light is incident on the first region and periods when the illumination light is incident on the second region, and the central axis of the illumination light incident on the collimator element is temporally shifted over the two periods. As a result, different speckle patterns change over time, making it possible to efficiently reduce speckle noise.

[0085] (Appendix 2) the diffusion surface further includes a third region disposed in a circumferential direction of the diffusion plate relative to the first region and the second region, the third region reflects the illumination light at a third reflection angle different from the first reflection angle and the second reflection angle; 2. The lighting device of claim 1, wherein the first reflection angle is 45°, the second reflection angle is 45°-α1, and the third reflection angle is 45°+α1.

[0086] According to the configuration of Supplementary Note 2, during the period when the illumination light is incident on the second and third regions, the variations in brightness and contrast caused by the central axis of the illumination light being tilted with respect to the optical axis of the collimator element are cancelled out, thereby reducing the variations in brightness and contrast of the image.

[0087] (Appendix 3) 3. The lighting device of claim 2, wherein the area of ​​the second region and the area of ​​the third region are equal to each other.

[0088] According to the configuration of Supplementary Note 3, the length of the period during which the illumination light is incident on the second region and the length of the period during which the illumination light is incident on the third region are equal to each other, thereby further reducing unevenness in the brightness and contrast of the image.

[0089] (Appendix 4) 4. The lighting device of claim 2, wherein α1 is 5°.

[0090] According to the configuration of Supplementary Note 4, it is possible to efficiently reduce speckle noise while appropriately suppressing unevenness in the brightness and contrast of an image.

[0091] (Appendix 5) the diffusion surface further includes a third region, a fourth region, and a fifth region that are arranged in a circumferential direction of the diffusion plate relative to the first region and the second region, the third region reflects the illumination light at a third reflection angle different from the first reflection angle and the second reflection angle; the fourth region reflects the illumination light at a fourth reflection angle different from the first reflection angle, the second reflection angle, and the third reflection angle; the fifth region reflects the illumination light at a fifth reflection angle different from the first reflection angle, the second reflection angle, the third reflection angle, and the fourth reflection angle; 2. The lighting device of claim 1, wherein the first reflection angle is 45°, the second reflection angle is 45°-α1, the third reflection angle is 45°+α1, the fourth reflection angle is 45°-α2, and the fifth reflection angle is 45°+α2.

[0092] According to the configuration of Supplementary Note 5, during the period when the illumination light is incident on the second and third regions, unevenness in brightness and contrast caused by the central axis of the illumination light being tilted with respect to the optical axis of the collimator element cancels out. Also, during the period when the illumination light is incident on the fourth and fifth regions, unevenness in brightness and contrast caused by the central axis of the illumination light being tilted with respect to the optical axis of the collimator element cancels out. This makes it possible to reduce unevenness in the brightness and contrast of the image.

[0093] (Appendix 6) The area of ​​the second region and the area of ​​the third region are equal to each other, 6. The lighting device according to claim 5, wherein the area of ​​the fourth region and the area of ​​the fifth region are equal to each other.

[0094] According to the configuration of Appendix 6, the length of the period during which the illumination light is incident on the second region is equal to the length of the period during which the illumination light is incident on the third region, and the length of the period during which the illumination light is incident on the fourth region is equal to the length of the period during which the illumination light is incident on the fifth region, thereby further reducing unevenness in the brightness and contrast of the image.

[0095] (Appendix 7) 7. The lighting device of claim 5, wherein α1 is 2.5° and α2 is 5°.

[0096] According to the configuration of Supplementary Note 7, it is possible to efficiently reduce speckle noise while appropriately suppressing unevenness in the brightness and contrast of an image.

[0097] (Appendix 8) The α2 is greater than the α1, 8. The lighting device according to claim 5, wherein the five regions on the diffusion surface are arranged in the order of the second region, the fourth region, the fifth region, and the third region along the rotation direction of the diffusion plate relative to the first region.

[0098] According to the configuration of Supplementary Note 8, during the period when the illumination light is incident on the fifth region, unevenness in the brightness and contrast of the image can be efficiently reduced.

[0099] (Appendix 9) 9. The lighting device according to claim 2, wherein the area of ​​the first region is larger than the area of ​​the second region and the area of ​​the third region.

[0100] According to the configuration of Supplementary Note 9, it is possible to suppress unevenness in brightness and contrast caused by the central axis of the illumination light being tilted with respect to the optical axis of the collimator element.

[0101] (Appendix 10) 10. The lighting device according to claim 1, wherein the diffusion characteristics of the first region and the diffusion characteristics of the second region are different from each other.

[0102] According to the configuration of Supplementary Note 10, the speckle pattern changes due to the difference in diffusion characteristics between the two regions, so that the speckle noise reduction effect can be further enhanced.

[0103] (Appendix 11) 10. The lighting device according to claim 1, wherein the diffusion characteristics of the first region and the diffusion characteristics of the second region are the same.

[0104] According to the configuration of Supplementary Note 11, it is only necessary to form a uniform diffusion structure over the entire diffusion surface regardless of the region, which makes it easier to manufacture the diffusion plate.

[0105] (Appendix 12) at least one of the diffusion surface of the first region and the diffusion surface of the second region is inclined with respect to a virtual plane perpendicular to the rotation axis, 12. The lighting device of claim 1, wherein a first inclination angle of the diffusion surface in the first region relative to the virtual plane and a second inclination angle of the diffusion surface in the second region relative to the virtual plane are different from each other.

[0106] According to the configuration of Appendix 12, by making the first inclination angle of the diffusion surface in the first region and the second inclination angle of the diffusion surface in the second region different from each other, it is possible to realize a diffusion plate in which the first reflection angle in the first region and the second reflection angle in the second region are different from each other.

[0107] (Appendix 13) a third inclination angle of the diffusion surface in the first region with respect to the virtual plane and a fourth inclination angle of the diffusion surface in the second region with respect to the virtual plane are different from each other; 13. The lighting device described in Appendix 12, wherein the first tilt angle and the second tilt angle are tilt angles along the radial direction of the diffusion plate, and the third tilt angle and the fourth tilt angle are tilt angles along the circumferential direction of the diffusion plate.

[0108] According to the configuration of Supplementary Note 13, the central axis of the illumination light incident on the collimator element is shifted not only in the radial direction of the diffuser plate but also in the direction perpendicular to the radial direction of the diffuser plate, thereby further enhancing the effect of reducing speckle noise.

[0109] (Appendix 14) An illumination device according to any one of Supplementary Note 1 to Supplementary Note 13; a light modulation device that modulates light including the illumination light emitted from the illumination device; a projection optical device that projects the light modulated by the light modulation device; A projector equipped with

[0110] According to the configuration of Supplementary Note 14, a projector with excellent display quality can be realized. [Explanation of symbols]

[0111] 1...projector, 2...illumination device, 4R...light modulation device for red light, 4G...light modulation device for green light, 4B...light modulation device for blue light, 6...projection optical device, 20...blue light source (first light source), 30...green light source (second light source), 40...red light source, 50...light combining member, 60...light focusing element, 70...light diffusion device, 71, 75...diffusion plate, 71A, 75A...first region, 71B, 75B...second region, 71C, 75C...third region, 75D...fourth region, 75E...fifth region, 71s, 75s...diffusion surface, 72...drive device, 80...collimator element, LB...blue light (first light), LG...green light (second light), LR...red light, WL...illumination light.

Claims

1. a first light source that emits first light in a first wavelength band; a second light source that emits second light in a second wavelength band different from the first wavelength band; a light combining member that combines the first light and the second light to emit illumination light; a light diffusing device that diffuses and reflects the illumination light emitted from the light combining member; a focusing element disposed between the light combining member and the light diffusing device, which focuses the illumination light emitted from the light combining member toward the light diffusing device; a collimator element that collimates the illumination light emitted from the light diffusing device; Equipped with the light diffusion device includes a diffusion plate including a diffusion surface that diffuses and reflects the illumination light, and a drive device that rotates the diffusion plate around a rotation axis; the diffusing surface has a first region where the illumination light is reflected at a first reflection angle, and a second region that is arranged in a circumferential direction of the diffusing plate relative to the first region and where the illumination light is reflected at a second reflection angle different from the first reflection angle.

2. the diffusion surface further includes a third region disposed in a circumferential direction of the diffusion plate relative to the first region and the second region, the third area reflects the illumination light at a third reflection angle different from the first reflection angle and the second reflection angle; 2. The lighting device of claim 1, wherein the first reflection angle is 45 degrees, the second reflection angle is 45 degrees - α1, and the third reflection angle is 45 degrees + α1.

3. The lighting device according to claim 2 , wherein the area of ​​the second region and the area of ​​the third region are equal to each other.

4. The lighting device according to claim 2 , wherein α1 is 5°.

5. the diffusion surface further includes a third region, a fourth region, and a fifth region that are arranged in a circumferential direction of the diffusion plate relative to the first region and the second region, the third area reflects the illumination light at a third reflection angle different from the first reflection angle and the second reflection angle; the fourth area reflects the illumination light at a fourth reflection angle different from the first reflection angle, the second reflection angle, and the third reflection angle; the fifth region reflects the illumination light at a fifth reflection angle different from the first reflection angle, the second reflection angle, the third reflection angle, and the fourth reflection angle; 2. The lighting device of claim 1, wherein the first reflection angle is 45°, the second reflection angle is 45°-α1, the third reflection angle is 45°+α1, the fourth reflection angle is 45°-α2, and the fifth reflection angle is 45°+α2.

6. The area of ​​the second region and the area of ​​the third region are equal to each other, The lighting device according to claim 5 , wherein the fourth region and the fifth region have an equal area.

7. The lighting device according to claim 5 , wherein the angle α1 is 2.5° and the angle α2 is 5°.

8. The α2 is greater than the α1, 6. The lighting device according to claim 5, wherein on the diffusion surface, the five regions are arranged in the following order along a rotation direction of the diffusion plate with the first region as a reference: the second region, the fourth region, the fifth region, and the third region.

9. The lighting device according to claim 2 , wherein an area of ​​the first region is larger than an area of ​​the second region and an area of ​​the third region.

10. The lighting device according to claim 1 , wherein the diffusion characteristics of the first region and the diffusion characteristics of the second region are different from each other.

11. The lighting device according to claim 1 , wherein the diffusion characteristics of the first region and the diffusion characteristics of the second region are the same.

12. at least one of the diffusion surface of the first region and the diffusion surface of the second region is inclined with respect to a virtual plane perpendicular to the rotation axis, 9. The lighting device according to claim 1, wherein a first inclination angle of the diffusing surface in the first region with respect to the virtual plane and a second inclination angle of the diffusing surface in the second region with respect to the virtual plane are different from each other.

13. a third inclination angle of the diffusion surface in the first region with respect to the virtual plane and a fourth inclination angle of the diffusion surface in the second region with respect to the virtual plane are different from each other, the first tilt angle and the second tilt angle are tilt angles along a radial direction of the diffusion plate, The lighting device according to claim 12 , wherein the third tilt angle and the fourth tilt angle are tilt angles along a circumferential direction of the diffusion plate.

14. A lighting device according to any one of claims 1 to 8; a light modulation device that modulates light including the illumination light emitted from the illumination device; a projection optical device that projects the light modulated by the light modulation device; A projector equipped with

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