JP6427929B2 - projector - Google Patents

Description

  The present invention relates to a lighting device and a projector.

  2. Description of the Related Art An illumination device is known that includes a solid-state light source such as a semiconductor laser and a phosphor layer that generates fluorescence by using light emitted from the solid-state light source as excitation light. For example, in the following Patent Document 1, a semiconductor laser light source, a light separation element, a phosphor, a first reflection element, a quarter phase plate, a diffusion plate, and a second reflection element are included. A light source device is disclosed.

  In this light source device, the excitation light emitted from the semiconductor laser light source enters the light separation element and is separated into two lights by the light separation element having polarization separation characteristics. One of the lights separated by the light separation element is irradiated to the phosphor as excitation light, and fluorescence is emitted. The fluorescence is reflected toward the light separation element by the first reflection element, and is emitted to the outside through the light separation element. The other light out of the light separated by the light separation element is adjusted in the polarization state by the ¼ phase difference plate, diffused by the diffusion plate while maintaining the polarization direction, and by the second reflection element. The light is reflected toward the light separation element through the ¼ phase difference plate and is emitted to the outside through the light separation element.

JP 2013-250494 A

  In the above light source device, among the light emitted from the solid light source, the light emitted outside without being irradiated on the phosphor layer is a diffusion plate for the purpose of making the illuminance distribution uniform and eliminating speckle noise. Diffused by. However, in the light source device of Patent Document 1, when the diffusion angle of light by the diffusion plate is increased, the polarization is disturbed and the polarization holding ratio is lowered. When the polarization holding ratio decreases, the amount of light emitted to the outside via the light separation element decreases. Therefore, the diffusion angle is set to 13 ° or less in order to make the polarization holding ratio 95% or more. However, light diffusion is insufficient at this level, and the effect of making the illuminance distribution uniform and the effect of improving speckle noise cannot be obtained sufficiently.

  One aspect of the present invention has been made to solve the above-described problem, and provides an illumination device that can achieve uniform illumination distribution and improved speckle noise while suppressing a decrease in light use efficiency. One of the purposes is to provide. Another object of one embodiment of the present invention is to provide a projector having excellent display quality by including the above-described lighting device.

  In order to achieve the above object, an illumination device according to one aspect of the present invention includes a first light source that emits first light in a first wavelength band, and a second light source that is different from the first wavelength band. A second light source that emits second light in the wavelength band of the first light source, and a light source device that is excited by the light in the second wavelength band, and the first wavelength band and the second wavelength band Is provided on the opposite side of the phosphor layer that emits light of a different third wavelength band and the surface on which the second light is incident on the phosphor layer, and reflects the light generated by the phosphor layer Provided in the optical path of the second light between the reflector, the light source device and the phosphor layer, and has a polarization separation function for the light in the first wavelength band, and the third A polarization separation element that transmits or reflects light in a wavelength band, and the light emitted from the first light source and travels through the polarization separation element. A diffuse reflection element that reflects the first light toward the polarization separation element, and a retardation plate disposed in an optical path of the first light between the diffusion reflection element and the polarization separation element; The diffuse reflection element has a concavo-convex structure including a plurality of curved surfaces.

  According to said structure, after the 1st light inject | emitted from the 1st light source injects into a diffuse reflection element via a polarization splitting element and a phase difference plate, and after being reflected while diffusing by a diffuse reflection element, The light is emitted from the illumination device via the phase difference plate and the polarization separation element. On the other hand, the 2nd light inject | emitted from the 2nd light source injects into a fluorescent substance layer via a polarization separation element, and excites a fluorescent substance layer. The excited phosphor layer generates third light. Part of the third light is emitted from the phosphor layer after being reflected by the reflecting portion. The other part of the third light is emitted from the phosphor layer without being reflected by the reflecting portion. The 3rd light inject | emitted from the fluorescent substance layer is inject | emitted in the same direction as 1st light from an illuminating device by being permeate | transmitted or reflected by the polarization separation element. Thereby, illumination light including the first wavelength band and the third wavelength band can be obtained.

  According to said structure, since the diffuse reflection element has an uneven | corrugated structure containing a some curved surface, when the 1st light is reflected by a diffuse reflection element, disorder of the polarization state is suppressed. At the same time, the diffusion angle can be increased. Thereby, it is possible to realize an illuminating device capable of making the illuminance distribution uniform and improving speckle noise while suppressing a decrease in the utilization efficiency of the first light.

In the illumination device according to one aspect of the present invention, the plurality of curved surfaces may be randomly arranged in a plan view.
According to this configuration, the effect of uniformizing the illuminance distribution and the effect of improving speckle noise can be further enhanced as compared with the case where a plurality of curved surfaces are regularly arranged.

In the illumination device according to one aspect of the present invention, the diffuse reflection element may have the concavo-convex structure on a surface on which the first light is incident, and the concavo-convex structure may have reflectivity.
According to this configuration, unlike the case where the first light is incident on the surface opposite to the surface on which the first light is incident, for example, light loss due to the diffuse reflection element is small and the light utilization efficiency can be increased.

In the illumination device according to one aspect of the present invention, a metal reflective film may be provided on the surface of the uneven structure.
According to this configuration, the reflection characteristics are less likely to deteriorate even when the incident angle of light changes, compared to the case where a reflective film made of a dielectric multilayer film is used, for example. As a result, light loss due to the diffuse reflection element is reduced, and the light use efficiency can be increased.

In the illumination device according to one aspect of the present invention, the diffuse reflection element may be rotatable in a plane intersecting a central axis of the first light incident on the diffuse reflection element.
According to this configuration, since the irradiation position of the first light on the diffuse reflection element changes with time, damage to the diffuse reflection element due to irradiation with the first light can be reduced. In addition, since the concavo-convex structure located on the optical path of the first light changes with time, it is possible to further enhance the effect of uniforming the illuminance distribution and the effect of improving speckle noise.

In the illumination device according to one aspect of the present invention, the uneven structure may have a shape that does not cause multiple reflection.
According to this configuration, the polarization holding ratio in the diffuse reflection element can be more reliably increased.

A projector according to one aspect of the present invention includes an illumination device that emits illumination light, a light modulation device that forms image light by modulating the illumination light according to image information, and projection optics that projects the image light. And the lighting device is a lighting device according to one aspect of the present invention.
According to one aspect of the present invention, a projector having excellent display quality can be provided by including the illumination device according to one aspect of the present invention.

1 is a diagram illustrating a schematic configuration of a projector according to an embodiment of the invention. It is a top view which shows schematic structure of the illuminating device of one Embodiment. (A)-(c) It is sectional drawing which shows the structural example of a diffused reflection board. It is a top view of a diffuse reflection board.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The projector according to the present embodiment is an example of a liquid crystal projector including an illumination device using a semiconductor laser.
In the drawings used in the following description, in order to make the characteristics easy to see, a part of the drawings may be shown in an enlarged manner, and the dimensional ratios and the like of each component are not always the same as actual.

[projector]
First, an example of the projector 1 shown in FIG. 1 will be described.
FIG. 1 is a plan view showing a schematic configuration of the projector 1.

  The projector 1 according to the present embodiment is a projection type image display device that displays a color video (image) on a screen (projection surface) SCR. The projector 1 uses three light modulation devices corresponding to each color light of red light LR, green light LG, and blue light LB. The projector 1 uses a semiconductor laser (laser light source) from which light with high luminance and high output can be obtained as a light source of an illumination device.

  Specifically, as shown in FIG. 1, the projector 1 includes an illumination device 2, a uniform illumination optical system 40, a color separation optical system 3, a light modulation device 4R, a light modulation device 4G, and a light modulation device 4B. A synthesis optical system 5 and a projection optical system 6 are roughly provided.

  The illumination device 2 emits illumination light WL toward the uniform illumination optical system 40. As the lighting device 2, a lighting device to which one embodiment of the present invention described later is applied is used.

  The uniform illumination optical system 40 includes an integrator optical system 31, a polarization conversion element 32, and a superimposing optical system 33. The uniform illumination optical system 40 uniformizes the intensity distribution of the illumination light WL emitted from the illumination device 2 in the illuminated area. The illumination light WL emitted from the uniform illumination optical system 40 enters the color separation optical system 3.

  The color separation optical system 3 is for separating the white illumination light WL into the red light LR, the green light LG, and the blue light LB. The color separation optical system 3 includes a first dichroic mirror 7a and a second dichroic mirror 7b, a first total reflection mirror 8a, a second total reflection mirror 8b, a third total reflection mirror 8c, and a first A relay lens 9a and a second relay lens 9b are roughly provided.

  The first dichroic mirror 7a has a function of separating the illumination light WL from the illumination device 2 into red light LR and other light (green light LG and blue light LB). The first dichroic mirror 7a transmits the separated red light LR and reflects other light (green light LG and blue light LB). On the other hand, the second dichroic mirror 7b has a function of separating other light into green light LG and blue light LB. The second dichroic mirror 7b reflects the separated green light LG and transmits the blue light LB.

  The first total reflection mirror 8a is disposed in the optical path of the red light LR, and reflects the red light LR transmitted through the first dichroic mirror 7a toward the light modulation device 4R. On the other hand, the second total reflection mirror 8b and the third total reflection mirror 8c are arranged in the optical path of the blue light LB, and direct the blue light LB transmitted through the second dichroic mirror 7b toward the light modulation device 4B. reflect. It is not necessary to arrange a total reflection mirror in the optical path of the green light LG, and the green light LG is reflected toward the light modulation device 4G by the second dichroic mirror 7b.

  The first relay lens 9a and the second relay lens 9b are arranged on the light emission side of the second dichroic mirror 7b in the optical path of the blue light LB. The first relay lens 9a and the second relay lens 9b function to compensate for the optical loss of the blue light LB caused by the optical path length of the blue light LB being longer than the optical path lengths of the red light LR and the green light LG. have.

  The light modulation device 4R modulates the red light LR according to image information while allowing the red light LR to pass therethrough, and forms image light corresponding to the red light LR. The light modulation device 4G modulates the green light LG according to image information while allowing the green light LG to pass therethrough, and forms image light corresponding to the green light LG. The light modulation device 4B modulates the blue light LB according to image information while allowing the blue light LB to pass therethrough, and forms image light corresponding to the blue light LB.

  For example, a transmissive liquid crystal panel is used for the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B. In addition, a pair of polarizing plates (not shown) are arranged on the incident side and the emission side of the liquid crystal panel so that only linearly polarized light in a specific direction passes therethrough.

  A field lens 10R, a field lens 10G, and a field lens 10B are disposed on the incident side of the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B, respectively. The field lens 10R, the field lens 10G, and the field lens 10B are for parallelizing the red light LR, the green light LG, and the blue light LB incident on the respective light modulation devices 4R, 4G, and 4B. It is.

  The combining optical system 5 combines the image light corresponding to the red light LR, the green light LG, and the blue light LB when the image light from the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B enters. The combined image light is emitted toward the projection optical system 6. For example, a cross dichroic prism is used for the combining optical system 5.

  The projection optical system 6 is composed of a projection lens group. The projection optical system 6 enlarges and projects the image light combined by the combining optical system 5 toward the screen SCR. Thereby, an enlarged color video (image) is displayed on the screen SCR.

[Lighting device]
Next, a specific embodiment of a lighting device to which one aspect of the present invention used for the lighting device 2 is applied will be described.

The illumination device 20A shown in FIG. 2 will be described.
FIG. 2 is a plan view showing a schematic configuration of the illumination device 20A.

As shown in FIG. 2, the illumination device 20A includes an array light source 21A, a collimator optical system 22, an afocal optical system 23, a homogenizer optical system 24, an optical element 25A including a polarization separation element 50A, a first Pickup optical system 26, fluorescent light emitting element 27, phase difference plate 28, second pickup optical system 29, and diffuse reflection element 30 are roughly provided.
The diffuse reflection element 30 of the present embodiment corresponds to the diffuse reflection element in the claims. The polarization separation element 50A of the present embodiment corresponds to the polarization separation element in the claims. The retardation plate 28 of the present embodiment corresponds to the retardation plate of the claims.

  Among these components, the array light source 21A, the collimator optical system 22, the afocal optical system 23, the homogenizer optical system 24, the optical element 25A, the phase difference plate 28, and the second pickup optical system 29 are included. The diffuse reflection elements 30 are sequentially arranged side by side on the optical axis ax1 with their optical centers aligned with the optical axis ax1 shown in FIG. On the other hand, the fluorescent light emitting element 27, the first pickup optical system 26, and the optical element 25A are sequentially arranged on the optical axis ax2 with their optical centers aligned with the optical axis ax2 shown in FIG. Is arranged in. The optical axis ax1 and the optical axis ax2 are in the same plane and are in a positional relationship orthogonal to each other.

  The array light source 21A corresponds to the light source device in the present invention. The array light source 21A includes a first semiconductor laser 211 that is a first light source and a second semiconductor laser 212 that is a second light source. The plurality of first semiconductor lasers 211 and the plurality of second semiconductor lasers 212 are arranged in an array in the same plane orthogonal to the optical axis ax1.

  The first semiconductor laser 211 emits blue light BL ′ that is first light in the first wavelength band. The first semiconductor laser 211 emits laser light having a peak wavelength of 460 nm, for example, as blue light BL ′. The second semiconductor laser 212 is a laser light source for excitation light that emits excitation light BL that is second light in the second wavelength band. The second semiconductor laser 212 emits laser light having a peak wavelength of 446 nm, for example, as the excitation light BL.

  The excitation light BL and the blue light BL ′ are emitted from the array light source 21A toward the polarization separation element 50A.

  Excitation light BL and blue light BL ′ emitted from the array light source 21 </ b> A enter the collimator optical system 22. The collimator optical system 22 converts the excitation light BL and the blue light BL ′ emitted from the array light source 21 </ b> A into parallel light beams. The collimator optical system 22 is composed of, for example, a plurality of collimator lenses 22a arranged in an array. The plurality of collimator lenses 22a are arranged corresponding to the plurality of first semiconductor lasers 211 and the plurality of second semiconductor lasers 212, respectively.

  Each excitation light BL and blue light BL ′ converted into a parallel light beam by passing through the collimator optical system 22 is incident on the afocal optical system 23. The afocal optical system 23 adjusts the beam diameters of the excitation light BL and the blue light BL ′. The afocal optical system 23 includes, for example, an afocal lens 23a and an afocal lens 23b.

  Excitation light BL and blue light BL ′ whose beam diameters are adjusted by passing through the afocal optical system 23 are incident on the homogenizer optical system 24. The homogenizer optical system 24 converts the light intensity distribution of the excitation light BL and the blue light BL ′ into a uniform state (so-called top hat distribution). The homogenizer optical system 24 includes, for example, a multi-lens array 24a and a multi-lens array 24b.

  The excitation light BL and the blue light BL ′ that have been converted to a uniform light intensity distribution by the homogenizer optical system 24 are incident on the optical element 25A. The optical element 25A is composed of, for example, a dichroic prism having wavelength selectivity. The dichroic prism has an inclined surface K that forms an angle of 45 ° with the optical axis ax1. The inclined surface K forms an angle of 45 ° with respect to the optical axis ax2. The optical element 25A is arranged so that the intersection of the optical axes ax1 and ax2 orthogonal to each other coincides with the optical center of the inclined surface K. The optical element 25A is not limited to a prism shape such as a dichroic prism, and a parallel plate dichroic mirror may be used.

  On the inclined surface K, a polarization separation element 50A having wavelength selectivity is provided. The polarization separation element 50A has a polarization separation function for separating the excitation light BL and the blue light BL ′ into an S polarization component (one polarization component) and a P polarization component (the other polarization component) for the polarization separation element 50A. ing. Specifically, the polarization separation element 50A reflects the S-polarized component of the excitation light BL and the S-polarized component of the blue light BL ′, and transmits the P-polarized component of the excitation light BL and the P-polarized component of the blue light BL ′.

  In addition, the polarization separation element 50A has a color separation function that transmits fluorescent light YL, which is third light having different wavelength bands, from excitation light BL and blue light BL ′, which will be described later, regardless of the polarization state. Yes.

  Here, the excitation light BL and the blue light BL ′ are coherent linearly polarized light. Further, the excitation light BL and the blue light BL 'have different polarization directions when entering the polarization separation element 50A.

  Specifically, the polarization direction of the excitation light BL coincides with the polarization direction of one polarization component (for example, S polarization component) reflected by the polarization separation element 50A. On the other hand, the polarization direction of the blue light BL ′ coincides with the polarization direction of the other polarization component (for example, P polarization component) transmitted by the polarization separation element 50A. Thus, when entering the polarization separation element 50A, the polarization direction of the excitation light BL and the polarization direction of the blue light BL 'are orthogonal to each other. In order to realize this configuration, the polarization direction when the blue light BL ′ is emitted from the first semiconductor laser 211 is orthogonal to the polarization direction when the excitation light BL is emitted from the second semiconductor laser 212. Thus, the first semiconductor laser 211 and the second semiconductor laser 212 may be disposed.

  Accordingly, the excitation light BL incident on the polarization separation element 50A is reflected toward the fluorescent light emitting element 27 as S-polarized excitation light BLs because the polarization direction of the excitation light BL coincides with the S-polarization component. On the other hand, the blue light BL ′ incident on the polarization separation element 50 </ b> A is transmitted toward the diffuse reflection element 30 as the P-polarized blue light BLp ′ because the polarization direction coincides with the P-polarized light component.

  Here, a case where the polarization direction of the excitation light BL is the same as the polarization direction of the blue light BL ′ when entering the polarization separation element 50 </ b> A will be considered. In this case, since the blue light BL ′ is P-polarized light, the excitation light BL is also P-polarized light. In order for the polarization separation element 50A to reflect the P-polarized excitation light BL, the polarization separation element 50A has a polarization separation function with respect to the blue light BL ′ having a peak wavelength of 460 nm, and the excitation light BL having a peak wavelength of 446 nm. On the other hand, it must not have a polarization separation function. However, it is difficult to manufacture a polarization separation element having such characteristics.

  On the other hand, in the present embodiment, the excitation light BL is S-polarized light, and the blue light BL ′ is P-polarized light. In this case, the polarization separation element 50A may have a polarization separation function not only for the blue light BL ′ having a peak wavelength of 460 nm but also for the excitation light BL having a peak wavelength of 446 nm. For this reason, it is easy to manufacture the polarization separation element.

  The S-polarized excitation light BLs emitted from the polarization separation element 50 </ b> A is incident on the first pickup optical system 26. The first pickup optical system 26 focuses the excitation light BLs toward the phosphor layer 34 of the fluorescent light emitting element 27. The first pickup optical system 26 includes, for example, a pickup lens 26a and a pickup lens 26b.

  The excitation light BLs emitted from the first pickup optical system 26 enters the fluorescent light emitting element 27. The fluorescent light emitting element 27 includes a phosphor layer 34, a substrate 35 that supports the phosphor layer 34, and a fixing member 36 that fixes the phosphor layer 34 to the substrate 35.

  The fluorescent light emitting element 27 is provided between the side surface of the phosphor layer 34 and the substrate 35 in a state where the surface of the phosphor layer 34 opposite to the side on which the excitation light BLs is incident is in contact with the substrate 35. The phosphor layer 34 is fixedly supported on the substrate 35 by the fixing member 36.

  The phosphor layer 34 includes a phosphor that is excited by absorbing the excitation light BLs having a wavelength of 446 nm. The phosphor excited by the excitation light BLs generates fluorescent light (yellow light) YL having a peak wavelength in a wavelength region of, for example, 500 to 700 nm as the third light.

  For the phosphor layer 34, it is preferable to use a layer excellent in heat resistance and surface processability. As such a phosphor layer 34, for example, a phosphor layer in which phosphor particles are dispersed in an inorganic binder such as alumina, a phosphor layer in which phosphor particles are sintered without using a binder, and the like are preferably used. be able to.

A reflective portion 37 is provided on the side of the phosphor layer 34 opposite to the side on which the excitation light BLs is incident. The reflection unit 37 has a function of reflecting a part of the fluorescent light YL among the fluorescent light YL generated by the phosphor layer 34.
The reflection part 37 of this embodiment corresponds to the reflection part in the claims.

  It is preferable that the reflection part 37 consists of a specular reflection surface. In the fluorescent light emitting element 27, the fluorescent light YL generated in the fluorescent material layer 34 is specularly reflected by the reflecting portion 37, whereby the fluorescent light YL can be efficiently emitted from the fluorescent material layer 34.

  Specifically, the reflecting portion 37 can be configured by providing a reflecting film 37a on the surface of the phosphor layer 34 opposite to the side on which the excitation light BLs is incident. In this case, the surface of the reflective film 37a facing the phosphor layer 34 is a specular reflection surface. The reflection part 37 may be configured such that the substrate 35 is made of a base material having light reflection characteristics. In this case, the reflective film 37a is omitted, and the surface of the substrate 35 facing the phosphor layer 34 is made into a mirror surface, so that this surface can be used as a mirror reflection surface.

  For the fixing member 36, it is preferable to use an inorganic adhesive having light reflection characteristics. In this case, the light leaking from the side surface of the phosphor layer 34 can be reflected into the phosphor layer 34 by the inorganic adhesive having light reflection characteristics. Thereby, the light extraction efficiency of the fluorescent light YL generated by the phosphor layer 34 can be further increased.

  A heat sink 38 is disposed on the surface of the substrate 35 opposite to the surface that supports the phosphor layer 34. In the fluorescent light emitting element 27, heat can be radiated through the heat sink 38, and thus thermal deterioration of the phosphor layer 34 can be prevented.

  Of the fluorescent light YL generated in the phosphor layer 34, a part of the fluorescent light YL is reflected by the reflecting portion 37 and emitted to the outside of the phosphor layer 34. In addition, among the fluorescent light YL generated in the fluorescent material layer 34, another part of the fluorescent light YL is emitted outside the fluorescent material layer 34 without passing through the reflecting portion 37. In this way, the fluorescent light YL is emitted from the phosphor layer 34.

  Since the fluorescent light YL emitted from the phosphor layer 34 is non-polarized light whose polarization direction is not uniform, after passing through the first pickup optical system 26, it enters the polarization separation element 50A while remaining in a non-polarized state. . The fluorescent light YL is transmitted from the polarization separation element 50A toward the integrator optical system 31.

  The P-polarized blue light BLp ′ emitted from the polarization separation element 50 </ b> A enters the phase difference plate 28. The phase difference plate 28 is composed of a ¼ wavelength plate (λ / 4 plate) disposed in the optical path between the polarization separation element 50 </ b> A and the diffuse reflection element 30. Accordingly, the P-polarized blue light BLp ′ emitted from the polarization separation element 50A is converted into circularly-polarized blue light BLc ′ by transmitting through the phase difference plate 28, and then is transmitted to the second pickup optical system 29. Incident.

  The second pickup optical system 29 collects the blue light BLc ′ toward the diffuse reflection element 30. The second pickup optical system 29 includes, for example, a pickup lens 29a and a pickup lens 29b.

  The diffuse reflection element 30 diffuses and reflects the blue light BLc ′ emitted from the second pickup optical system 29 toward the polarization separation element 50A. Among them, as the diffuse reflection element 30, it is preferable to use an element that causes Lambert reflection of the blue light BLc ′ incident on the diffuse reflection element 30.

  The diffuse reflection element 30 includes a diffuse reflection plate 30A and a drive source 30M such as a motor for rotating the diffuse reflection plate 30A. The rotation axis of the drive source 30M is disposed substantially parallel to the optical axis ax1. Accordingly, the diffuse reflector 30A is configured to be rotatable within a plane that intersects the central axis of the blue light BLc 'incident on the diffuse reflector 30A. The diffuse reflection plate 30A is formed, for example, in a circular shape when viewed from the direction of the rotation axis.

FIG. 3A is a cross-sectional view of the diffuse reflector 30A.
For example, the diffuse reflector 30 </ b> A shown in FIG. 3A includes a base material 43 and a reflective film 44. The base material 43 is comprised with arbitrary materials, such as glass, for example.

  Of the two surfaces of the base material 43, a concavo-convex structure 43a including a plurality of randomly arranged curved surfaces is provided on the surface on which the blue light BLc 'is incident. In the present embodiment, the concavo-convex structure 43a is composed of a plurality of recesses, and each recess is formed in a substantially spherical shape. The depth of the recess is, for example, about 1/4 of the diameter of the entire spherical surface.

  As shown in FIG. 4, the plurality of recesses are randomly arranged when the diffusive reflector 30 </ b> A is viewed from the light incident direction. 4 indicates the center of each recess, and the centers C of the plurality of recesses are randomly arranged.

  The reflection film 44 is a metal reflection film formed of a metal having a high light reflectance such as silver or aluminum. The reflective film 44 is formed along the shape of the concavo-convex structure 43a, and the surface of the reflective film 44 also has a substantially spherical shape. Since the reflective film 44 is formed on the surface of the uneven structure 43a, the uneven structure 43a has reflectivity. When the blue light BLc ′ is incident on the formation surface of the reflection film 44 of the diffuse reflection plate 30A, the blue light BLc ′ is emitted by one reflection, and multiple reflection does not occur. Thereby, disturbance of the polarization state when the blue light BLc ′ is reflected by the diffuse reflector 30A is suppressed.

  The reflection film 44 is not limited to a metal reflection film, and for example, a dielectric multilayer film can be used. However, when a metal reflection film is used as the reflection film 44, the reflection characteristics are less likely to deteriorate even if the incident angle of light changes, compared to the case where a reflection film made of a dielectric multilayer film is used. As a result, light loss due to the diffusive reflector 30A is reduced, and the light use efficiency can be increased.

When manufacturing the diffuse reflection plate 30A, first, an etching prevention film such as chromium is formed on one surface of a substrate such as glass.
Next, a plurality of holes are formed in the etching prevention film by laser processing or the like. At this time, in the laser processing machine, the coordinates of the formation position are set so that the positions of the plurality of holes to be formed are randomly arranged. As a result, a plurality of randomly arranged holes are formed in the etching prevention film.

Next, using the etching prevention film as a mask, one surface of the substrate is etched by, for example, wet etching. At this time, the wet etching conditions are adjusted to be isotropic etching. When etching is performed in this manner, the etching solution penetrates from the hole portion of the etching preventing film, and a recess is formed at a position corresponding to the hole. Since the etching is isotropic etching, the etching proceeds isotropically with the hole as a center, and as a result, the cross-sectional shape of the recess becomes substantially spherical.
Next, a metal film such as silver or aluminum is formed on one surface of the base material on which the concavo-convex structure is formed by a sputtering method, a vapor deposition method, or the like.
With the above method, the diffuse reflector 30A is completed.

3B and 3C are cross-sectional views of other examples of the diffuse reflector (diffuse reflector 30B and diffuse reflector 30C). Instead of the diffuse reflector 30A, a diffuse reflector 30B or a diffuse reflector 30C may be used.
In the diffuse reflector 30B shown in FIG. 3B, the base material 45 is formed of a metal such as silver or aluminum. Of the two surfaces of the base material 45, a concavo-convex structure 45a including a plurality of randomly arranged curved surfaces is provided on the surface on which the blue light BLc ′ is incident. The shape of the uneven structure 45a is the same as the shape of the uneven structure 43a in FIG. In this configuration, since the substrate 45 itself has light reflectivity, it is not necessary to form a metal film on the substrate 45.

  A diffuse reflection plate 30 </ b> C illustrated in FIG. 3C includes a base material 46 and a reflection film 47. The base material 46 is made of an arbitrary material such as glass. Of the two surfaces of the base material 46, a concavo-convex structure 46a including a plurality of randomly arranged curved surfaces is provided on the surface on which the blue light BLc 'is incident. The shape of the uneven structure 46a is the same as the shape of the uneven structure 43a in FIG. A reflective film 47 made of a metal such as silver or aluminum is formed on the surface opposite to the surface on which the blue light BLc ′ is incident, of the two surfaces of the substrate 46.

  Any of the diffuse reflectors shown in FIGS. 3A to 3C may be used as the diffuse reflector of the present embodiment. However, from the viewpoint that the loss of light is small, the surface on which the blue light BLc ′ is incident is light-reflecting like the diffuse reflector 30A in FIG. 3A or the diffuse reflector 30B in FIG. Those having properties are preferred. This is because there is a possibility of light loss when the blue light BLc ′ is incident on the base material 46 as in the diffusing reflection plate 30 </ b> C of FIG.

  3A to 3C include a plurality of concave portions arranged at random, but may include a plurality of concave portions arranged regularly. However, when a plurality of concave portions are regularly arranged, a diffraction phenomenon may occur, but an effect of suppressing a decrease in the utilization efficiency of the first light can be obtained.

  In the illuminating device 20A, by using such a diffuse reflection element 30, it is possible to diffusely reflect the blue light BLc 'and obtain the blue light BLc' having a substantially uniform illuminance distribution.

  As shown in FIG. 2, the blue light BLc ′ diffusely reflected by the diffuse reflection element 30 passes through the second pickup optical system 29 again and enters the phase difference plate 28 to be converted into blue light BLs ′. The The blue light BLs' is incident on the polarization separation element 50A. As described above, the blue light BLc ′ before entering the diffuse reflection element 30 is circularly polarized light. If the polarization state of the blue light BLc ′ is not disturbed at all by the diffuse reflection element 30, the blue light BLs ′ is S-polarized light and does not include the P-polarized component. Even if the polarization state of the blue light BLc ′ is disturbed to some extent by the diffuse reflection element 30, the main component of the blue light BLs ′ is the S-polarized component. The S-polarized component of the blue light BLs ′ is reflected by the polarization separation element 50A.

  As a result, the blue light BLs ′ is emitted from the illumination device 20A as the illumination light WL together with the fluorescent light YL transmitted through the polarization separation element 50A. That is, the blue light BLs ′ and the fluorescent light YL are emitted in the same direction from the polarization separation element 50A. Thereby, illumination light (white light) WL obtained by combining the blue light BLs ′ and the fluorescent light (yellow light) YL is obtained.

  The illumination light WL emitted from the illumination device 20A enters the integrator optical system 31. The integrator optical system 31 is for making the luminance distribution (illuminance distribution) uniform. The integrator optical system 31 includes, for example, a lens array 31a and a lens array 31b. The lens arrays 31a and 31b are made up of a plurality of microlenses arranged in an array.

  The illumination light WL that has passed through the integrator optical system 31 enters the polarization conversion element 32. The polarization conversion element 32 aligns the polarization direction of the illumination light WL. The polarization conversion element 32 includes, for example, a polarization separation film and a phase difference plate. The polarization conversion element 32 aligns the polarization direction of the fluorescent light YL whose polarization direction is not uniform and the polarization direction of the S-polarized blue light BLs ′, so that the other polarization component is changed to one polarization component (for example, a P polarization component). Is converted into an S-polarized component.

  The illumination light WL whose polarization direction is aligned by passing through the polarization conversion element 32 enters the superimposing optical system 33. The superimposing optical system 33 superimposes the illumination light WL emitted from the polarization conversion element 32. The superimposing optical system 33 is composed of, for example, a superimposing lens. The illuminance distribution in the illuminated area is made uniform by the integrator optical system 31 and the superimposing optical system 33.

  In the illuminating device 20A having the above-described configuration, since the diffuse reflector 30A has an uneven structure including a plurality of randomly arranged curved surfaces, the blue light BLc ′ is reflected by the diffuse reflector 30A. In this case, disturbance of the polarization state is suppressed, and the diffusion angle can be increased.

  If the polarization state of the blue light BLc ′ is greatly disturbed by the diffuse reflector 30A, the P-polarized component contained in the blue light BLs ′ increases, and the component reflected by the polarization separation element 50A decreases. However, according to the present invention, since the P-polarized component contained in the blue light BLs ′ can be reduced, it is possible to suppress a decrease in the amount of the blue light BLs ′ emitted from the illumination device 20A. As a result, it is possible to realize an illuminating device 20A capable of making the illuminance distribution uniform and improving speckle noise while suppressing a decrease in the utilization efficiency of the first light.

  In particular, in the case of the present embodiment, since the diffuse reflection element 30 includes the diffuse reflection plate 30A that is rotatable, the irradiation position of the blue light BLc ′ on the diffuse reflection element 30 changes with time. Therefore, it is possible to reduce damage to the diffuse reflector 30A due to the irradiation with the blue light BLc '. In addition, since the concavo-convex structure located on the optical path of the blue light BLc ′ changes with time, the effect of uniformizing the illuminance distribution and the effect of improving speckle noise can be further enhanced.

  In the illuminating device 20A, the fluorescent light YL generated by exciting the phosphor layer 34 with the excitation light BLs, and the blue light BLs ′ obtained by diffusing and reflecting the blue light BLp ′ with the diffuse reflection element 30. Can be used to obtain illumination light WL excellent in color purity and color reproducibility.

  That is, the blue light BL ′ having a peak wavelength of 460 nm is blue light having higher visibility than the excitation light BL having a peak wavelength of 446 nm. In addition, a wider color gamut can be obtained when light having a peak wavelength of 460 nm is used than when light having a peak wavelength of 446 nm is used. That is, light having a peak wavelength of 460 nm is more suitable for forming a color image than light having a peak wavelength of 446 nm. Therefore, when the illumination light WL is obtained using the blue light BL ′ having a peak wavelength of 460 nm and the fluorescent light YL, the illumination light WL is obtained using the excitation light BL and the fluorescent light YL having a peak wavelength of 446 nm. It is possible to improve the color gamut (color reproduction range) of the illumination light WL than the case.

  Further, the second semiconductor laser 212 that emits the excitation light BL is generally less expensive than the first semiconductor laser 211 that emits the blue light BL ′. Accordingly, in the illumination device 20A, the second semiconductor laser 212 that emits laser light having a peak wavelength of 446 nm is used as the laser light source for excitation light, and the laser light having a peak wavelength of 460 nm is emitted to the laser light source for blue light. By using the first semiconductor laser 211, it is possible to improve the color gamut at a lower cost.

  As described above, according to the projector 1 including such an illumination device 20A, it is possible to perform display with excellent image quality while reducing the size and weight of the device.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the diffusive reflector used in the above embodiment, the concavo-convex structure is configured by a plurality of concave portions having a curved surface, but may be configured by a plurality of convex portions having a curved surface. That is, you may use the diffuse reflection board which the uneven | corrugated shape reversed with respect to the diffuse reflection board shown in FIG. Moreover, the concavo-convex structure may be composed of a plurality of concave portions made of a curved surface and a plurality of convex portions made of a curved surface. Moreover, in the said embodiment, although the example of the diffuse reflection element provided with the diffuse reflection plate made rotatable was given, when the damage of a diffuse reflection plate does not become a problem, a diffuse reflection plate does not necessarily need to rotate. . In the above-described embodiment, an example in which the first wavelength band is different from the second wavelength band has been described. However, the first wavelength band may coincide with the second wavelength band. In addition, the shape, number, arrangement, material, and the like of the various components of the lighting device and the projector are not limited to the above-described embodiment, and can be changed as appropriate.

  In the above embodiment, an example in which the lighting device according to the present invention is mounted on a projector has been shown, but the present invention is not limited to this. The lighting device according to the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 2 and 20A ... Illumination device, 4R, 4G, 4B ... Light modulation device, 6 ... Projection optical system, 21A ... Array light source (light source device), 28 ... Phase difference plate, 30 ... Diffuse reflection element, 34 ... Phosphor layer, 37 ... reflecting part, 43a, 45a, 46a ... uneven structure, 44,47 ... reflective film, 50A ... polarization separating element, 211 ... first semiconductor laser (first light source), 212 ... second Semiconductor laser (second light source).

Claims (4)

An illumination device that emits illumination light;
A light modulation device that forms image light by modulating the illumination light according to image information;
A projection optical system for projecting the image light,
The lighting device includes:
A light source device comprising a first light source for emitting a first laser beam of a first wavelength band, a second light source for emitting a second laser beam of the second wavelength band, and
A phosphor layer that is excited by light of the second wavelength band and emits light of a third wavelength band different from the second wavelength band;
A reflection part provided on the opposite side of the surface of the phosphor layer from which the second laser light is incident, and reflecting light generated by the phosphor layer;
Provided in the optical path of the second laser light between the light source device and the phosphor layer, the first laser light and the second laser light are incident, and light in the first wavelength band And a polarization separation element that has a polarization separation function for the light of the second wavelength band and transmits or reflects the light of the third wavelength band,
A diffuse reflection element that reflects the first laser light emitted from the first light source and traveling through the polarization separation element toward the polarization separation element;
A retardation plate disposed in an optical path of the first laser beam between the diffuse reflection element and the polarization separation element;
With
The diffuse reflection element includes a base material made of glass,
Have a concavo-convex structure in which the first laser beam of said substrate comprises a plurality of curved surfaces provided on the surface on the side of incidence,
A projector , wherein a metal reflective film is provided on a surface of the concavo-convex structure along the shape of the concavo-convex structure . The projector according to claim 1, wherein the plurality of curved surfaces are randomly arranged in a plan view . The diffuse reflection element projector according to claim 1 or claim 2, characterized in that it is rotatable in intersecting plane to said first laser beam central axis of incident on the diffuse reflection element. The relief structure, the projector according to any one of up to claims 1 to 3, characterized in that it has a shape that does not cause multiple reflections.