JP2019028363A - Illumination device and projector - Google Patents

Abstract

To provide an illumination device emitting light suitable for illumination.SOLUTION: An illumination device of the present invention includes: a light source device that includes at least one first light-emitting device and a plurality of second light-emitting devices and emits beam fluxes including a first sub-beam flux in a first color emitted from the at least one first light-emitting device and a second sub-beam flux in a second color different from the first color emitted from the plurality of second light-emitting devices; a beam flux reduction optical system that receives the beam fluxes; and a diffusion element disposed in a rear stage of the beam flux reduction optical system. In a front stage of the beam flux reduction optical system, the second sub-beam flux is thicker than the first sub-beam flux; and a reduction magnification of the beam flux reduction optical system on the second sub-beam flux is greater than the reduction magnification of the beam flux reduction optical system on the first sub-beam flux.SELECTED DRAWING: Figure 2

Description

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

  In recent years, a projector using a laser light source as a light source with a wide color gamut and high efficiency has been attracting attention for the purpose of improving the performance of the projector.

  As this type of projector, Patent Document 1 below discloses a red laser light source, a green laser light source, a blue laser light source, a dichroic element that synthesizes light from these laser light sources, and a diffusion element that diffuses synthesized light. A display device including a light modulation device is disclosed. The light emitted from the laser light source is coherent light and causes speckle. However, speckle can be suppressed by diffusing light using a diffusing element.

Japanese Patent Laid-Open No. 6-208089

  Since the light emission efficiency of the laser light source varies depending on the color, the number of laser light sources necessary for obtaining a white balance suitable for video display in the projector of Patent Document 1 differs for each color. In general, the luminous efficiency of blue laser light sources is higher than that of green laser light sources and red laser light sources, so the number of laser light sources required to obtain white light is small, and there are few green laser light sources and green laser light sources and red laser light sources. There are many light sources.

  Therefore, when comparing the thickness of each color light, green light and red light are thicker than blue light. As described above, when thin blue light, thick green light, and red light are diffused by one diffusing element, the thickness of the light remains greatly different after diffusion. This causes color unevenness when an image is projected by a projector or the like, and is not preferable as illumination light.

  As a means for reducing the difference in the thickness of the light beam after diffusion, a configuration in which diffusing elements having different diffusion characteristics are provided for each color light path can be considered. However, this configuration has a problem that the number of diffusing elements is increased, the number of parts is increased, and the lighting device is increased in size.

  One aspect of the present invention is made to solve the above-described problem, and is an illumination device including a light source device in which the number of light-emitting devices differs depending on colors and a diffusion element common to a plurality of color lights. Another object is to provide a lighting device that emits light suitable for lighting. Another object of one embodiment of the present invention is to provide a projector including the above lighting device.

  In order to achieve the above object, an illumination device according to an aspect of the present invention includes at least one first light emitting device and a plurality of second light emitting devices, and includes at least one first light emitting device. A first sub-beam bundle of the first color emitted and a second sub-beam bundle of a second color different from the first color emitted from the plurality of second light emitting devices; A light source device that emits a light beam including the light beam, a light beam reduction optical system on which the light beam is incident, and a diffusing element provided at a subsequent stage of the light beam reduction optical system. In the previous stage of the light bundle reduction optical system, the second sub light bundle is thicker than the first sub light bundle, and the reduction magnification of the light bundle reduction optical system with respect to the second sub light bundle is It is larger than the reduction magnification for the first sub-light bundle of the light bundle reduction optical system.

  In the illumination device according to one aspect of the present invention, the second sub-beam bundle is thicker than the first sub-beam bundle before the beam bundle-reducing optical system, and the second sub-beam bundle of the beam bundle-reducing optical system is Since the reduction magnification is larger than the reduction magnification for the first sub-beam bundle, the difference between the thickness of the first sub-beam bundle and the thickness of the second sub-beam bundle is reduced by the beam bundle reduction optical system. Therefore, even if a common diffusing element is used for sub-light bundles of different colors, the difference in the thickness of the light bundle for each color after diffusion is smaller than when the above-described light bundle reduction optical system is not provided. Light suitable for illumination can be obtained.

  In the illumination device according to one aspect of the present invention, the light bundle reduction optical system includes a first lens having a positive lens power and a second lens, and the first lens has a lens power. A first region of zero, the second lens has a second region of zero lens power, and the light bundle reduction optical system has the first sub-light bundle of the first region. It may be provided so as to pass through the region and the second region.

  According to this configuration, the first sub-light bundle passes through the region where the lens power of the first lens is zero and the region where the lens power of the second lens is zero, and thus passes through the light bundle reduction optical system. However, the beam bundle does not become thin. Thereby, the reduction magnification with respect to the 2nd sub light beam of a light beam reduction optical system can be made small compared with the case where a 1st sub light beam is reduced.

  In the illumination device according to one aspect of the present invention, the first lens has a hole penetrating the first lens in the first region, and the second lens is in the second region. A hole penetrating the second lens may be provided.

  In this configuration, the first sub-light bundle passes through a hole penetrating the first lens and the second lens. This eliminates the loss of the first sub-beam bundle due to the surface reflection of the lens.

  In the illumination device according to one aspect of the present invention, the lens surface of the first lens is flat in the first region, and the lens surface of the second lens is flat in the second region. May be.

  According to this configuration, the first lens and the second lens suitable for the light bundle reduction optical system can be easily manufactured.

  In the illumination device according to one aspect of the present invention, the light bundle reduction optical system includes a concave mirror that reflects the second sub light bundle, and a convex mirror that reflects the second sub light bundle reflected by the concave mirror; The convex mirror has a light transmission region that transmits the first sub-light bundle, and the light bundle reduction optical system includes the first sub-light bundle that has passed through the light transmission region, and the The second sub beam bundle reflected by the convex mirror may be provided so as to enter the diffusing element.

  In this configuration, the first sub-beam is transmitted through the light transmission region of the convex mirror, while the second sub-beam is sequentially reflected by the concave mirror and the convex mirror. As a result, the difference between the thickness of the first sub-beam bundle and the thickness of the second sub-beam bundle is reduced.

  In the illumination device according to one aspect of the present invention, the convex mirror includes a first surface that includes a convex surface, and a translucent member that includes a concave surface and a second surface that faces the first surface, and the first surface. A wavelength selection film provided on a surface or the second surface, and the wavelength selection film has a characteristic of transmitting the first sub-beam and reflecting the second sub-beam. May be.

  According to this configuration, the light transmission region can be used to reduce the thickness of the second sub-beam bundle. For this reason, the difference in thickness between the first sub-beam bundle and the second sub-beam bundle in the subsequent stage of the beam bundle reducing optical system is sufficiently smaller than that in the preceding stage of the beam bundle reducing optical system.

  In the illumination device according to one aspect of the present invention, the translucent member may have zero lens power in the light transmission region.

  According to this configuration, the first sub-light bundle passes through the light transmission region and is expanded as parallel light. Therefore, the reduction magnification of the light bundle reduction optical system with respect to the second sub light bundle can be reduced as compared with the case where the first sub light bundle is reduced.

  In the illumination device according to one aspect of the present invention, the wavelength selection film may be provided on the first surface, and an antireflection film may be provided on the second surface.

  According to this configuration, loss of the first sub-beam bundle and the second sub-beam bundle can be suppressed.

  In the illumination device according to one aspect of the present invention, the plurality of second light emitting devices are provided in a peripheral region of the at least one first light emitting device when viewed in parallel with an emission direction of the light beam. Also good.

  According to said structure, since the center axis | shaft of a 1st sub-beam bundle and the center axis | shaft of a 2nd sub-beam bundle can be made to correspond, color nonuniformity can be reduced. In the present specification, the central axis of the spread (distribution) of each sub-beam bundle is referred to as the central axis of each sub-beam bundle.

  A projector according to an aspect of the present invention includes an illumination device according to an aspect of the present invention, a light modulation device that forms image light by modulating light from the illumination device according to image information, and the image light. A projection optical system.

  Since the projector according to one aspect of the present invention includes the lighting device according to one aspect of the present invention, an image with little color unevenness can be projected.

It is a schematic block diagram of the projector of 1st Embodiment. It is an enlarged view of the principal part of the illuminating device of 1st Embodiment. It is a perspective view of a light source device. It is a front view of a light source device. In the illuminating device of this embodiment, it is a figure which shows the simulation result of the illumination intensity distribution of the light in the back | latter stage of a light beam reduction optical system. FIG. 11 is a diagram showing a simulation result of the illuminance distribution of light in the latter stage of the light bundle reducing optical system in the illumination device of the comparative example. It is an enlarged view of the principal part of the illuminating device of 2nd Embodiment. It is an enlarged view of the principal part of the illuminating device of 3rd Embodiment. It is an enlarged view of the principal part of the illuminating device of 4th Embodiment.

[First Embodiment]
Hereinafter, a first 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 a light source device using a semiconductor laser.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  The projector 10 of the present embodiment is a projection type image display device that projects a color image on a screen (projection surface) SCR. The projector 10 uses three light modulation devices corresponding to the respective color lights of red light LR, green light LG, and blue light LB. The projector 10 uses a semiconductor laser capable of obtaining light with high luminance and high output as a light emitting element of a light source device.

FIG. 1 is a schematic configuration diagram of a projector 10 according to the present embodiment.
As shown in FIG. 1, the projector 10 includes an illumination device 700, a color separation light guide optical system 200, a red light modulation device 400R, a green light modulation device 400G, and a blue light modulation device 400B. And a synthesis optical system 500 and a projection optical system 600. The light modulator for red light 400R, the light modulator for green light 400G, and the light modulator for blue light 400B modulate image light from the illumination device 700 according to image information to form image light. The projection optical system 600 projects image light.

  The illumination device 700 includes a light source device 710, a light beam reduction optical system 720, a polarization separation element 760, a phase difference plate 761, a condenser lens 771, a diffusion device 740, and an integrator optical system 780. Yes. In the illumination device 700, the light source device 710, the light beam reduction optical system 720, the polarization separation element 760, the phase difference plate 761, the condenser lens 771, and the diffusion device 740 are on the optical axis AX1 of the light emitted from the light source device 710. Is provided. The polarization separation element 760 and the integrator optical system 780 are provided on the optical axis AX0 of the light LW emitted from the illumination device 700.

  Hereinafter, the direction in which the light LW is emitted from the illumination device 700 is referred to as the Y direction, the direction in which the light LW is emitted from the light source device 710 is referred to as the X direction, and the direction perpendicular to the X direction and the Y direction is referred to as the Z direction. The optical axis AX1 is parallel to the X axis, and the optical axis AX0 is parallel to the Y axis.

FIG. 3 is a perspective view of the light source device 710. In FIG. 3, the pedestals of some semiconductor lasers are not shown for easy viewing of the drawing.
FIG. 4 is a front view of the light source device 710 viewed from the X-axis direction.
3 and 4, the light source device 710 includes at least one blue semiconductor laser 711B (first light emitting device), a plurality of green semiconductor lasers 711G (second light emitting device), and a plurality of red semiconductors. A laser 711R (third light emitting device) and a support member 712 are provided.

  In the present embodiment, the light source device 710 includes one blue semiconductor laser 711B, three green semiconductor lasers 711G, and three red semiconductor lasers 711R. The light source device 710 may include a plurality of blue semiconductor lasers 711B.

  The blue semiconductor laser 711B emits blue light LB (first sub-beam bundle) in the first direction. The green semiconductor laser 711G emits the green light beam LG1 in the first direction. The red semiconductor laser 711R emits the red light beam LR1 in the first direction.

  In the following description, the plurality of green light beams LG1 emitted from the plurality of green semiconductor lasers 711G are collectively referred to as green light LG (second sub-beam bundle). The plurality of red light beams LR1 emitted from the plurality of red semiconductor lasers 711R are collectively referred to as red light LR (third sub-beam bundle). The light source device 710 emits a light beam including blue light LB, green light LG, and red light LR.

  Each of the blue semiconductor laser 711B, the green semiconductor laser 711G, and the red semiconductor laser 711R is composed of a CAN package type semiconductor laser. One or more semiconductor laser chips 715B, one or more semiconductor laser chips 715G, or one or more semiconductor laser chips 715R are accommodated in each of the housings including the pedestal 713 and the can body 714. A collimating lens 788 is attached to the light emission side of the housing.

  Since the light emission efficiency of the semiconductor laser differs for each emission color, the light output of the semiconductor laser also differs for each emission color. The emission efficiency of the blue semiconductor laser 711B is higher than the emission efficiency of the green semiconductor laser 711G and the emission efficiency of the red semiconductor laser 711R. Therefore, the light output of the blue semiconductor laser 711B is higher than the light output of the green semiconductor laser 711G and the light output of the red semiconductor laser 711R.

For example, Nichia Corporation, homepage, product information, “Laser Diode (LD)” [online], [Search June 14, 2017], Internet <URL: http: //www.nichia According to .co.jp / jp / product / laser.html>, the light output of a blue semiconductor laser (model number: NDB7K75) is, for example, 3.5 W (25 ° C), and the light of a green semiconductor laser (model number: NDG7K75T) The output is 1 W (25 ° C.), for example. Although not listed on the above website, a blue semiconductor laser array (model number: NUBM08-02) is provided. This blue semiconductor laser array includes multiple blue semiconductor lasers with an optical output of 4.5 W (25 ° C). I have.
Mitsubishi Electric Corporation, homepage, news release, “Notice of 639nm red high-power semiconductor laser for projectors” [online], [Search June 14, 2017], Internet <URL: http: //www.mitsubishielectric. co.jp/news/2016/1214.html>, the light output of the red semiconductor laser (model number: ML562G85) is 2.1 W (25 ° C.), for example.

  When the light output at the temperature of 25 ° C. is converted into the light output at the actual use temperature of 45 ° C., the light output of each color semiconductor laser is as shown in Table 1 below.

  That is, the light output of one blue semiconductor laser (model number: NDB7K75) is 2.8 W, and the light output of one blue semiconductor laser provided in the blue semiconductor laser array (model number: NUBM08-02) is 4.1 W. The light output of one green semiconductor laser (model number: NDG7K75T) is 0.8 W, and the light output of one red semiconductor laser (model number: ML562G85) is 1.26 W.

  On the other hand, the light output of each semiconductor laser necessary for obtaining white light of 1000 lm, 2000 lm, and 3000 lm, and the number of semiconductor lasers necessary for obtaining this white light are shown in Table 2 below. Street.

  As shown at the bottom of Table 2, the light output of each semiconductor laser required to obtain white light with a brightness of 1000 lm is 1.23 W for the blue semiconductor laser and 2.03 W for the green semiconductor laser. The red semiconductor laser is 2.92W. Based on these light output values and the light output of each semiconductor laser, the number of semiconductor lasers required to obtain white light with a brightness of 1000 lm is the semiconductor laser for blue light (model number: NDB7K75). ), Three green laser diode lasers, and three red laser diode lasers. This coincides with the number of semiconductor lasers 711B, 711G, and 711R of the light source device 710 of the present embodiment. However, in Table 2, for the brightness of 3000 lm, one blue semiconductor laser provided in the blue semiconductor laser array (model number: NUBM08-02) is used.

  When one semiconductor laser is provided with a plurality of semiconductor laser chips, the emission efficiency of the semiconductor laser is equal to the sum of the emission efficiencies of the plurality of semiconductor laser chips.

  According to the inventor's guess, there is a possibility that the light output of each of the semiconductor lasers 711B, 711G, and 711R will increase from the above numerical value due to the advancement of the semiconductor laser technology, but it is necessary to obtain white light. The ratio of the number of semiconductor lasers 711B, 711G, and 711R does not change. Therefore, the light source device 710 of this embodiment includes one blue semiconductor laser 711B, three green semiconductor lasers 711G, and three red semiconductor lasers 711R. The number of each semiconductor laser is shown in this example. It is not limited.

  The support member 712 is configured by a plate-like member and supports a plurality of semiconductor lasers 711B, 711G, and 711R. The material of the support member 712 is not particularly limited, but for example, a metal having high thermal conductivity is desirable.

  As shown in FIG. 4, when viewed in parallel with the emission direction of the green light LG, the plurality of green semiconductor lasers 711G and the plurality of red semiconductor lasers 711R are arranged so as to surround one blue semiconductor laser 711B. It is provided in the peripheral area. Furthermore, the green semiconductor laser 711G and the red semiconductor laser 711R are alternately provided along the circumferential direction of the support member 712. One green semiconductor laser 711G is provided in contact with the adjacent red semiconductor laser 711R. One red semiconductor laser 711R is provided in contact with the adjacent green semiconductor laser 711G. Each green semiconductor laser 711G and each red semiconductor laser 711R are provided in contact with the blue semiconductor laser 711B.

  As described above, the plurality of green semiconductor lasers 711G are provided substantially rotationally symmetrical around the central axis CB of the blue light LB in the peripheral region of the blue semiconductor laser 711B. The plurality of red semiconductor lasers 711R are provided substantially rotationally symmetrical around the central axis CB of the blue light LB in the peripheral region of the blue semiconductor laser 711B. Therefore, the central axis CG of the green light LG and the central axis CR of the red light LR coincide with the central axis CB of the blue light LB. Thereby, the color unevenness of the image displayed on the screen SCR is reduced. In the present specification, the description “substantially rotationally symmetric” includes not only a completely rotationally symmetric arrangement but also an arrangement that can reduce color unevenness to an acceptable level.

  As shown in FIG. 4, the semiconductor lasers 711B, 711G, and 711R are provided such that the long sides of the light emission regions of the semiconductor laser chips 715B, 715G, and 715R are parallel to the Z axis. Therefore, the semiconductor lasers 711B and 711G respectively emit blue light LB and green light LG that are S-polarized light with respect to the polarization separation element 760. The semiconductor laser 711 </ b> R emits red light LR that is P-polarized light with respect to the polarization separation element 760. Although not shown so that the blue light LB and the green light LG can pass through the polarization separation element 760, the blue light LB and the green light LG between the polarization separation element 760 and the light source device 710 are blue. A phase difference plate is provided for converting the polarization state of the light LB and the green light LG from S-polarized light to P-polarized light. When the semiconductor laser chip 715B is provided so as to emit the P-polarized blue light LB, the retardation plate is not necessary. The same applies to the green light LG.

FIG. 2 is an enlarged view of a main part of the lighting device 700. However, in FIG. 2, the polarization separation element 760 is not illustrated.
As shown in FIG. 2, the light beam reduction optical system 720 includes an afocal optical system including a convex lens 721 (first lens) and a concave lens 722 (second lens). The convex lens 721 has a first region 721a having positive lens power but zero lens power. The convex lens 721 has a hole 721h that passes through the convex lens 721 in the first region 721a. The concave lens 722 has a second region 722a having negative lens power but zero lens power. The concave lens 722 has a hole 722h that penetrates the concave lens 722 in the second region 722a.

  The light bundle reduction optical system 720 is provided so that the blue light LB passes through the hole 721h (first region 721a) of the convex lens 721 and the hole 722h (second region 722a) of the concave lens 722. The light bundle reduction optical system 720 is provided so that the green light LG and the red light LR pass through a portion of the convex lens 721 other than the hole 721h and a portion of the concave lens 722 other than the hole 722h.

  Thus, since the blue light LB passes through the hole 721h of the convex lens 721 and the hole 722h of the concave lens 722, the light beam reduction optical system 720 does not receive the reduction action. Therefore, the thickness of the blue light LB does not change between the front stage and the rear stage of the beam bundle reducing optical system 720. On the other hand, since the green light LG and the red light LR pass through a portion of the convex lens 721 other than the hole 721h and a portion of the concave lens 722 other than the hole 722h, the light beam reduction optical system 720 receives a reduction action. . Therefore, the thickness of each of the green light LG and the red light LR is reduced by the light beam reduction optical system 720.

  That is, the reduction magnification of the light bundle reduction optical system 720 with respect to the green light LG and the red light LR is larger than the reduction magnification of the light bundle reduction optical system 720 with respect to the blue light LB. In other words, the afocal magnification of the light bundle reduction optical system 720 with respect to the green light LG and the red light LR is smaller than the afocal magnification of the light bundle reduction optical system 720 with respect to the blue light LB. The reduction magnification of n times means that the afocal magnification is 1 / n times.

  In the present specification, when the light is composed of a plurality of light beams, the thickness of the light is the diameter of the smallest circle including the plurality of light beams as viewed from the central axis direction of the light. Is defined. When the light is composed of one light beam, the thickness of the light is defined as the diameter of the smallest circle that includes the cross section of the light beam perpendicular to the optical axis. Therefore, in the present embodiment, for example, the thickness of the green light LG is defined as the diameter of the smallest circle that includes the three light beams that constitute the green light LG.

  As shown in FIG. 1, the polarization separation element 760 is disposed so as to form an angle of 45 ° with respect to each of the optical axis AX0 and the optical axis AX1. The polarization separation element 760 is configured by a polarization separation element capable of supporting a wide band having polarization separation characteristics that transmits P-polarized light and reflects S-polarized light from the wavelength range of the blue light LB to the wavelength range of the red light LR. Hereinafter, the blue light LB, the green light LG, and the red light LR may be collectively referred to as light LW.

  The phase difference plate 761 is provided on the optical path of the light LW between the polarization separation element 760 and the diffusion device 740. The phase difference plate 761 is composed of a quarter wavelength plate that can handle a wide band from the wavelength range of the blue light LB to the wavelength range of the red light LR. The phase difference plate 761 converts the polarization state of the P-polarized light LW transmitted through the polarization separation element 760 from P-polarized light to, for example, clockwise circularly polarized light.

  The condenser lens 771 is provided on the optical path of the light LW between the phase difference plate 761 and the diffusion device 740. The condensing lens 771 condenses the light LW emitted from the phase difference plate 761 on the diffusion plate 741 of the diffusion device 740, receives and collimates the diffused light emitted from the diffusion plate 741, and forms a phase difference plate. Lead to 761.

  The diffusion device 740 includes a diffusion plate 741 and a motor 745 for rotating the diffusion plate 741. The diffusion plate 741 has, for example, a configuration in which irregularities are formed on the surface of a member having light reflectivity, and has diffuse reflectivity. The diffusion plate 741 is formed in a circular shape, for example, when viewed from the direction of the rotation shaft 743. The diffusion plate 741 diffuses and reflects the incident light LW toward the condenser lens 771. The light LW incident as clockwise circularly polarized light is diffusely reflected by the diffuser plate 741 to become diffused light as counterclockwise circularly polarized light.

  The light LW as counterclockwise circularly polarized light that is diffusely reflected by the diffuser plate 741 and transmitted again through the condenser lens 771 is transmitted through the phase difference plate 761 again to become light LW as S-polarized light. The S-polarized light LW is reflected by the polarization separation element 760 and travels toward the integrator optical system 780.

  The integrator optical system 780 includes a first lens array 781, a second lens array 782, and a superimposing lens 783. The integrator optical system 780 forms an image of the illuminance distribution of the light LW emitted from the polarization separation element 760 in each of the light modulator for red light 400R, the light modulator for green light 400G, and the light modulator for blue light 400B. Uniform in the area.

  The first lens array 781 has a plurality of lenses 786 for dividing the light LW emitted from the polarization separation element 760 into a plurality of partial beam bundles. The plurality of lenses 786 are arranged in a matrix in a plane orthogonal to the optical axis AX0.

  The second lens array 782 includes a plurality of lenses 787 corresponding to the plurality of lenses 786 of the first lens array 781. The second lens array 782, together with the superimposing lens 783 at the subsequent stage, converts the image of each lens 786 into the image forming regions of the red light light modulation device 400R, the green light light modulation device 400G, and the blue light light modulation device 400B. Alternatively, the image is formed in the vicinity thereof. The plurality of lenses 787 are arranged in a matrix in a plane orthogonal to the optical axis AX0.

  The superimposing lens 783 condenses the partial beam bundles from the second lens array 782 to form images of each of the red light modulation device 400R, the green light modulation device 400G, and the blue light modulation device 400B. They are superimposed on each other at or near the area.

  The color separation light guide optical system 200 includes a dichroic mirror 240, a dichroic mirror 220, a reflection mirror 210, a reflection mirror 230, a reflection mirror 250, a relay lens 260, and a relay lens 270. The color separation light guide optical system 200 separates the light LW emitted from the illumination device 700 into the red light LR, the green light LG, and the blue light LB, and corresponds to the red light LR, the green light LG, and the blue light LB, respectively. To the red light modulation device 400R, the green light modulation device 400G, and the blue light modulation device 400B.

  A field lens 300R, a field lens 300G, and a field lens 300B are disposed between the color separation light guide optical system 200 and the red light light modulation device 400R, the green light light modulation device 400G, and the blue light light modulation device 400B. Are arranged respectively.

  The dichroic mirror 240 reflects the blue light LB and transmits the red light LR and the green light LG. The dichroic mirror 220 reflects the green light LG and transmits the blue light LB. The reflection mirror 210 and the reflection mirror 230 reflect the red light LR. The reflection mirror 250 reflects the blue light LB.

  Each of the light modulator for red light 400R, the light modulator for green light 400G, and the light modulator for blue light 400B is composed of a liquid crystal panel that modulates incident color light according to image information to form an image. ing.

  Although not shown, an incident-side polarizing plate is disposed between the field lens 300R and the red light light modulation device 400R. An incident side polarizing plate is disposed between the field lens 300G and the green light modulation device 400G. An incident-side polarizing plate is disposed between the field lens 300B and the blue light modulator 400B. An exit-side polarizing plate is disposed between the red light modulation device 400R and the combining optical system 500. An exit-side polarizing plate is disposed between the green light modulation device 400G and the synthesis optical system 500. An emission-side polarizing plate is disposed between the blue light modulator 400B and the combining optical system 500.

  The synthesizing optical system 500 synthesizes each image light emitted from the light modulator for red light 400R, the light modulator for green light 400G, and the light modulator for blue light 400B. The synthesizing optical system 500 includes a cross dichroic prism having a substantially square shape in plan view in which four right-angle prisms are bonded together, and a dielectric multilayer film is provided at a substantially X-shaped interface in which the right-angle prisms are bonded together. ing.

  The image light emitted from the combining optical system 500 is enlarged and projected on the screen SCR by the projection optical system 600.

Here, an illumination device of a comparative example provided with a light bundle reduction optical system composed of a normal afocal optical system, that is, a light bundle reduction optical system composed of a convex lens without a hole and a concave lens without a hole. Think.
In the illumination device of the comparative example, each of the blue light LB, the green light LG, and the red light LR is reduced by the light bundle reduction optical system at the same reduction magnification and enters the condenser lens. Therefore, the green light LG and the red light LR are incident on the condensing lens in a state of being thicker than the blue light LB, and are collected by the condensing lens and incident on the diffusion plate. Therefore, the distribution range of the incident angle when each of the green light LG and the red light LR is incident on the diffusion plate is wider than the distribution range of the incident angle when the blue light LB is incident on the diffusion plate. Since all the color lights are incident on a common diffuser plate, the diffuse angle when the green light LG and the red light LR are emitted from the diffuser plate reflects the distribution range of the incident angles, and the blue light LB is from the diffuser plate. It becomes larger than the diffusion angle at the time of injection.

  As described above, in the illumination device of the comparative example, color unevenness may occur due to a plurality of color lights having different diffusion angles entering a subsequent optical system such as an integrator optical system.

  On the other hand, in the illumination device 700 of the present embodiment, as described above, the thicknesses of the green light LG and the red light LR are reduced by the action of the light bundle reduction optical system 720, but the thickness of the blue light LB is reduced. That does not change. As a result, the difference between the thickness of the blue light LB and the thickness of the green light LG at the subsequent stage of the light beam reducing optical system 720 is smaller than the difference of the thickness at the previous stage of the light beam reducing optical system 720. Similarly, the difference between the thickness of the blue light LB and the thickness of the red light LR in the subsequent stage of the light beam reduction optical system 720 is smaller than the difference in thickness in the previous stage of the light beam reduction optical system 720.

The inventor performed a simulation for demonstrating the operation of the light beam reduction optical system 720 of the present embodiment. In the illumination device 700 of this embodiment and the illumination device of the comparative example, the thickness of each light in the latter stage of the light bundle reduction optical system was compared.
FIG. 5 is a diagram showing a simulation result of the illuminance distribution of the light in the latter stage of the light beam reducing optical system 720 in the illumination device 700 of the present embodiment. FIG. 6 is a diagram illustrating a simulation result of the illuminance distribution of light in the latter stage of the light bundle reducing optical system in the illumination device of the comparative example.

  In the illumination device of the comparative example, one blue light beam emitted from the semiconductor laser in the central portion, three green light rays and three red light rays emitted from the plurality of semiconductor lasers in the peripheral portion are all light bundles. The light passes through the convex lens and the concave lens of the reduction optical system and is subjected to the reduction action of the light bundle reduction optical system. Therefore, as shown in FIG. 6, as a result of the blue light, the green light, and the red light being reduced at the same reduction magnification, the thicknesses of the blue light, the green light, and the red light are approximately the same.

  On the other hand, in the illumination device 700 of the present embodiment, the green light LG and the red light LR are reduced at the same reduction ratio as that of the illumination device of the comparative example, but the blue light LB is not reduced. Therefore, as shown in FIG. 5, the thickness of the blue light LB located at the center is sufficiently thick compared to the case of the illumination device of the comparative example shown in FIG. 6, and the thickness of the blue light LB and the green light LG The difference between the thickness and the difference between the thickness of the blue light LB and the thickness of the red light LR is reduced.

  In this case, since the difference in the distribution range of the incident angles when the blue light LB, the green light LG, and the red light LR are incident on the diffusion plate 741 is small, the diffusion angle when each color light is emitted from the diffusion plate 741. The difference is also reduced. As described above, according to the illumination device 700 of the present embodiment, even if the common diffuser plate 741 is used for color lights having different thicknesses, the thickness of the light bundle for each color after diffusion is larger than that of the conventional case. The difference can be reduced, and light suitable for illumination can be obtained. Therefore, the color lights LB, LG, and LR having a small difference in the diffusion angle can be incident on the subsequent optical system such as the integrator optical system 780, and color unevenness can be reduced.

  Further, in the illumination device of the comparative example having a general light bundle reduction optical system, as means for reducing the difference in the diffusion angle of the plurality of color lights, a plurality of diffusion plates having different diffusing forces are provided for each light path of each color light. A configuration to be provided can be considered. However, when this configuration is adopted, problems such as an increase in the number of parts and an increase in the size of the lighting device occur. On the other hand, in the illuminating device 700 of this embodiment, since one diffuser plate 741 can be shared by all the color lights, the above-described problems do not occur.

  In the illumination device 700 of this embodiment, the blue light LB passes through the hole 721h of the convex lens 721 and the hole 722h of the concave lens 722. Therefore, the loss of the blue light LB due to the surface reflection of the convex lens 721 and the concave lens 722 can be eliminated.

  Further, in the light source device 710 of the present embodiment, the number of each of the green semiconductor laser 711G and the red semiconductor laser 711R having relatively low emission efficiency is larger than the number of the blue semiconductor laser 711B having relatively high emission efficiency. This makes it easier to balance the color of light emitted from the light source device 710 than when the number of semiconductor lasers of each color is the same.

  Further, in the light source device 710 of this embodiment, each of the seven semiconductor lasers including one blue semiconductor laser 711B, three green semiconductor lasers 711G, and three red semiconductor lasers 711R is adjacent to each other. Therefore, the light source device 710 can be reduced in size.

  A transmission type diffusing element has a large light loss due to backscattering. However, since the diffusion plate 741 of the present embodiment is a reflection type, light loss is small, and the lighting device 700 can be downsized.

  Since the projector 10 of the present embodiment includes the illumination device 700 described above, an image with little color unevenness can be projected.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
The basic configuration of the illumination device of the second embodiment is the same as that of the first embodiment, and the configuration of the light bundle reduction optical system is different from that of the first embodiment. Therefore, description of the whole illuminating device is abbreviate | omitted and only a light beam reduction optical system is demonstrated.
FIG. 7 is an enlarged view of a main part of the illumination device of the second embodiment.
In FIG. 7, the same reference numerals are given to the same components as those used in the first embodiment, and the description will be omitted. Also in FIG. 7, the polarization separation element is not shown in the same manner as in FIG.

  As shown in FIG. 7, in the illumination device 702 of the present embodiment, the light bundle reduction optical system 724 is configured by an afocal optical system including a convex lens 725 and a concave lens 726. The convex lens 725 has a first region 725a where the lens power is zero, and the lens surface of the convex lens 725 is flat in the first region 725a. The concave lens 726 has a second region 726a in which the lens power is zero, and the lens surface of the concave lens 726 is flat in the second region 726a.

  The light bundle reduction optical system 724 is provided so that the blue light LB passes through the first region 725 a of the convex lens 725 and the second region 726 a of the concave lens 726. The light bundle reduction optical system 724 is provided so that the green light LG and the red light LR pass through a portion of the convex lens 725 other than the first region 725a and a portion of the concave lens 726 other than the second region 726a. It has been.

Thus, since the blue light LB passes through the first region 725a of the convex lens 725 and the second region 726a of the concave lens 726, it is not subjected to the reduction action of the light bundle reduction optical system 724, and the light bundle reduction optical system. The thickness does not change between the front stage and the rear stage of 724. On the other hand, since the green light LG and the red light LR pass through a portion of the convex lens 725 other than the first region 725a and a portion of the concave lens 726 other than the second region 726a, the light bundle reducing optical system. 724 is subjected to a reduction action. Therefore, the thickness of each of the green light LG and the red light LR is reduced by the light bundle reduction optical system 724. That is, the reduction magnification of the light bundle reduction optical system 724 with respect to the green light LG and the red light LR is larger than the reduction magnification of the light bundle reduction optical system 724 with respect to the blue light LB.
Other configurations of the illumination device are the same as those in the first embodiment.

  Also in this embodiment, the same effects as those in the first embodiment can be obtained, such as an illumination device capable of obtaining light suitable for illumination and a projector capable of projecting an image with little color unevenness.

  In the case of this embodiment, the first region 725a and the second region 726a having zero lens power are formed by processing part of the lens surfaces of the convex lens 725 and the concave lens 726 to be flat. Therefore, it is not necessary to drill the lens, and the convex lens 725 and the concave lens 726 can be easily manufactured.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.
The basic configuration of the illumination device of the third embodiment is the same as that of the first embodiment, and the configuration of the light bundle reduction optical system is different from that of the first embodiment. Therefore, description of the whole illuminating device is abbreviate | omitted and only a light beam reduction optical system is demonstrated.
FIG. 8 is an enlarged view of a main part of the illumination device of the third embodiment.
In FIG. 8, the same components as those used in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Also in FIG. 8, illustration of a polarization separation element is abbreviate | omitted similarly to FIG.

  As shown in FIG. 8, in the illumination device 706 of the present embodiment, the light bundle reduction optical system 728 is configured by an afocal optical system including a convex lens 721 (first lens) and a convex lens 729 (second lens). Has been. The convex lens 721 has a first region 721a having positive lens power but zero lens power. The convex lens 721 has a hole 721h that passes through the convex lens 721 in the first region 721a. The convex lens 729 has a second region 729a having positive lens power but zero lens power. The convex lens 729 has a hole 729h that passes through the convex lens 729 in the second region 729a.

  The light bundle reduction optical system 728 is provided so that the blue light LB passes through the first region 721a of the convex lens 721 and the second region 729a of the convex lens 729. The light bundle reduction optical system 728 is provided so that the green light LG and the red light LR pass through a portion of the convex lens 721 other than the first region 721a and a portion of the convex lens 729 other than the second region 729a. It has been.

Thus, since the blue light LB passes through the first region 721a of the convex lens 721 and the second region 729a of the convex lens 729, it is not subjected to the reduction action of the light bundle reduction optical system 728, and the light bundle reduction optical system. The thickness does not change between the former stage and the latter stage of 728. On the other hand, the green light LG and the red light LR pass through a portion of the convex lens 721 other than the first region 721a and a portion of the convex lens 729 other than the second region 729a. 728 is subjected to the reduction action. Therefore, the thickness of each of the green light LG and the red light LR is reduced by the light beam reduction optical system 728. That is, the reduction magnification of the light bundle reduction optical system 728 for the green light LG and the red light LR is larger than the reduction magnification of the light bundle reduction optical system 728 for the blue light LB.
Other configurations of the illumination device are the same as those in the first embodiment.

  Also in this embodiment, the same effects as those in the first embodiment can be obtained, such as an illumination device capable of obtaining light suitable for illumination and a projector capable of projecting an image with little color unevenness.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
The basic configuration of the illumination device of the fourth embodiment is the same as that of the first embodiment, and the configuration of the light bundle reduction optical system is different from that of the first embodiment. Therefore, description of the whole illuminating device is abbreviate | omitted and only a light beam reduction optical system is demonstrated.
FIG. 9 is an enlarged view of a main part of the illumination device of the fourth embodiment.
9, the same code | symbol is attached | subjected to the same component as FIG. 1 used in 1st Embodiment, and description is abbreviate | omitted. Also in FIG. 9, the polarization separation element is not shown in the same manner as in FIG.

  As shown in FIG. 9, in the illumination device 704 of the present embodiment, the light bundle reduction optical system 820 reflects green light LG (second sub light bundle) and red light LR (third sub light bundle). A concave mirror 821 and a convex mirror 822 that reflects the green light LG and the red light LR reflected by the concave mirror 821 are included.

  The concave mirror 821 is provided such that the reflecting surface 821r is positioned on the optical path of the plurality of green light beams LG1 and the plurality of red light beams LR1 emitted from each of the plurality of green semiconductor lasers 711G and the plurality of red semiconductor lasers 711R. . The reflecting surface 821r is desirably provided on the concave surface of the concave mirror 821 (the surface facing the light source device 710).

  The concave mirror 821 has an annular shape having a hole 821h corresponding to the optical path of the blue light LB when viewed along the optical axis AX1. That is, the reflecting surface 821r is not provided on the optical path of the blue light LB. Accordingly, the concave mirror 821 reflects the green light LG and the red light LR and allows the blue light LB to pass therethrough. The concave mirror 821 does not necessarily have the hole 821h corresponding to the optical path of the blue light LB, and a translucent member may be provided in a portion corresponding to the optical path of the blue light LB.

  The convex mirror 822 includes a translucent member 823, a wavelength selection film 824, and an antireflection film 825. The translucent member 823 is made of a translucent material such as glass, for example, and has a first surface 823a including a convex surface and a second surface 823b including a concave surface. The second surface 823b is opposed to the first surface 823a. The wavelength selection film 824 is provided over the entire first surface 823 a of the translucent member 823. The wavelength selection film 824 has characteristics of transmitting the blue light LB and reflecting the green light LG and the red light LR. The antireflection film 825 is provided on the second surface 823 b of the translucent member 823. Note that the wavelength selection film 824 may be provided on the second surface 823b of the translucent member 823.

  The convex mirror 822 has a light transmission region 822t that transmits the blue light LB. In the present embodiment, the wavelength selection film 824 is provided over the entire first surface of the translucent member 823, and there is no difference in the configuration of the convex mirror 822 between the light transmission region 822t and a region other than the light transmission region 822t. . Therefore, a portion of the convex mirror 822 that transmits the blue light LB is referred to as a light transmission region 822t. The translucent member 823 has zero lens power in the light transmission region 822t. Note that the wavelength selection film 824 may be provided only in a region of the first surface of the translucent member 823 excluding the light transmission region 822t. Alternatively, the convex mirror 822 may be provided with a hole in a portion corresponding to the light transmission region 822t of the translucent member 823, like the concave mirror 821.

  In the light beam reduction optical system 820, the blue light LB passes through the light transmission region 822 t of the convex mirror 822, sequentially passes through the phase difference plate 761 and the condenser lens 771, and enters the diffusion plate 741. The green light LG and the red light LR are reflected by the reflecting surface 821r of the concave mirror 821, reflected by the wavelength selection film 824 of the convex mirror 822, and sequentially transmitted through the phase difference plate 761 and the condensing lens 771 to the diffusion plate 741. Incident. As described above, the light bundle reduction optical system 820 is provided so that the blue light LB transmitted through the light transmission region 822t and the green light LG and the red light LR reflected by the convex mirror 822 are incident on the diffusion plate 741. ing.

  The reduction magnification of the light bundle reduction optical system 820 with respect to the green light LG and the red light LR is larger than the reduction magnification of the light bundle reduction optical system 820 with respect to the blue light LB. Therefore, the difference between the thickness of the blue light LB and the thickness of the green light LG in the subsequent stage of the light bundle reducing optical system 820 is smaller than the difference in the thickness in the previous stage of the light bundle reducing optical system 820. Similarly, the difference between the thickness of the blue light LB and the thickness of the red light LR at the subsequent stage of the light beam reducing optical system 820 is smaller than the difference of the thickness at the previous stage of the light beam reducing optical system 820.

  When the portion corresponding to the light transmission region 822t of the convex mirror 822 is configured by the light transmissive member 823, the curvature of the first surface 823a in the light transmission region 822t and the curvature of the second surface 823b in the light transmission region 822t are appropriately set. By designing as above, the thickness of the blue light LB incident as parallel light can be enlarged while maintaining the parallelism. Thereby, the difference between the thickness of the blue light LB and the thickness of the green light LG and the red light LR can be further reduced.

  Also in this embodiment, the same effects as those in the first embodiment can be obtained, such as an illumination device capable of obtaining light suitable for illumination and a projector capable of projecting an image with little color unevenness.

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 above embodiment, the light source device including one blue semiconductor laser, three green semiconductor lasers, and three red semiconductor lasers is illustrated, but the number of semiconductor lasers is not limited to this. . For example, the light source device may include a plurality of blue semiconductor lasers. In that case, the plurality of green semiconductor lasers and the plurality of red semiconductor lasers only need to be provided rotationally symmetrically around the central axis of the entire light beam composed of the plurality of blue light beams emitted from the plurality of blue semiconductor lasers. Or the semiconductor laser of the same color does not necessarily need to be arrange | positioned at rotational symmetry, for example, may be arrange | positioned at the grid | lattice form in two directions orthogonal to each other.

  Moreover, in the said embodiment, although the example of the illuminating device provided with the light source device which has three types of semiconductor lasers from which the color of light mutually differs was given, this invention is a semiconductor laser of at least 2 colors from which the color of light differs from each other The present invention can be applied to an illumination device including a light source device having

  In the above embodiment, the reduction ratio of the light bundle reduction optical system with respect to the first sub light bundle is 1, and the first sub light bundle (blue light) is not reduced even when it passes through the light bundle reduction optical system. Although the reduction magnification with respect to the first sub light bundle of the light bundle reduction optical system is larger than 1, the first sub light bundle may be reduced when it passes through the light bundle reduction optical system. Good. Even in this case, it is only necessary that the reduction magnification for the second sub-beam bundle of the light bundle reduction optical system satisfies the relationship larger than the reduction magnification for the first sub-beam bundle.

  In the above embodiment, an example of a diffusion plate that can be rotated by a motor has been described as the diffusion element. However, a fixed diffusion plate that does not include a motor may be used. In addition, the number, arrangement, shape, material, size, and the like of each component of the light source device, the illumination device, and the projector exemplified in the above embodiment can be changed as appropriate.

  In the above-described embodiment, a projector including three light modulation devices has been exemplified. However, the present invention can also be applied to a projector that displays a color image with a single light modulation device. A digital mirror device may be used as the light modulation device.

  In the above embodiment, an example in which the light source device and the illumination device according to the present invention are applied to a projector has been shown, but the present invention is not limited to this. The light source device or the lighting device according to the present invention can also be applied to a lighting fixture such as an automobile headlight.

  DESCRIPTION OF SYMBOLS 10 ... Projector, 400B ... Light modulation device for blue light, 400G ... Light modulation device for green light, 400R ... Light modulation device for red light, 600 ... Projection optical system, 700, 702, 704, 706 ... Illumination device, 710 ... Light source device, 711B ... Blue semiconductor laser (first light emitting device), 711G ... Green semiconductor laser (second light emitting device), 711R ... Red semiconductor laser (third light emitting device), 720, 724, 728, 820 ... Light bundle reduction optical system, 721, 725 ... convex lens (first lens), 721a, 725a ... first region, 721h, 722h, 729h ... hole, 722, 726 ... concave lens (second lens), 722a, 726a , 729a ... second region, 729 ... convex lens (second lens), 741 ... diffusing plate (diffusing element), 821 ... concave mirror, 822 ... convex Mirror, 822t ... light transmitting area, 823 ... light-transmitting member, 824 ... wavelength selection film, 825 ... antireflection film.

Claims (10)

At least one first light-emitting device and a plurality of second light-emitting devices, a first sub-beam of a first color emitted from the at least one first light-emitting device, and the plurality of second light-emitting devices. A light source device that emits a light bundle including a second sub-light bundle of a second color different from the first color emitted from the two light emitting devices;
A light beam reduction optical system on which the light beam is incident;
A diffusing element provided at a subsequent stage of the light bundle reduction optical system,
In the previous stage of the light bundle reduction optical system, the second sub light bundle is thicker than the first sub light bundle,
The illumination device, wherein a reduction magnification of the light bundle reduction optical system with respect to the second sub light bundle is larger than a reduction magnification of the light bundle reduction optical system with respect to the first sub light bundle. The light bundle reduction optical system includes a first lens having a positive lens power and a second lens,
The first lens has a first region where the lens power is zero;
The second lens has a second region where the lens power is zero,
The illumination device according to claim 1, wherein the light bundle reduction optical system is provided so that the first sub-light bundle passes through the first region and the second region. The first lens has a hole penetrating the first lens in the first region;
The lighting device according to claim 2, wherein the second lens has a hole penetrating the second lens in the second region. The lens surface of the first lens is flat in the first region,
The lighting device according to claim 2, wherein a lens surface of the second lens is flat in the second region. The light bundle reduction optical system includes a concave mirror that reflects the second sub-light bundle, and a convex mirror that reflects the second sub-light bundle reflected by the concave mirror,
The convex mirror has a light transmission region that transmits the first sub-beam.
The light bundle reduction optical system is provided so that the first sub light bundle transmitted through the light transmission region and the second sub light bundle reflected by the convex mirror are incident on the diffusing element. The lighting device according to claim 1. The convex mirror includes a translucent member having a first surface including a convex surface, a second surface including a concave surface and facing the first surface, and a wavelength provided on the first surface or the second surface. A selective membrane,
The lighting device according to claim 5, wherein the wavelength selection film has a characteristic of transmitting the first sub-beam and reflecting the second sub-beam.   The lighting device according to claim 6, wherein the translucent member has zero lens power in the light transmission region. The wavelength selective film is provided on the first surface,
The lighting device according to claim 6, wherein an antireflection film is provided on the second surface.   9. The device according to claim 1, wherein the plurality of second light emitting devices are provided in a peripheral region of the at least one first light emitting device when viewed in parallel with an emission direction of the light beam. The lighting device according to one item. The lighting device according to any one of claims 1 to 9,
A light modulation device that forms image light by modulating light from the illumination device according to image information; and
A projector comprising: a projection optical system that projects the image light.