JP6186779B2 - Lighting device and projector - Google Patents

Description

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

  2. Description of the Related Art Conventionally, there has been widely known a projector that irradiates illumination light emitted from an illumination device onto a light modulation device and enlarges and projects the image light modulated and emitted by the light modulation device onto a screen using a projection optical system.

  Conventionally, a discharge lamp such as an ultra-high pressure mercury lamp has been used as the light source of the projector described above. On the other hand, this type of discharge lamp has problems such as a relatively short life, difficult to light instantaneously, and ultraviolet rays emitted from the lamp deteriorate the liquid crystal light bulb.

  Therefore, a laser light source such as a semiconductor laser that can obtain light with high luminance and high output has attracted attention as a light source for a projector that can replace a discharge lamp. Compared with a conventional discharge lamp, the laser light source has advantages such as miniaturization, excellent color reproducibility, instant lighting, and long life.

  On the other hand, since the laser light emitted from the laser light source described above is coherent light, when used as a light source for a projector, speckle patterns called speckles caused by interference are displayed on the screen, which causes a deterioration in display quality. It becomes.

  For this reason, in the conventional illuminating device, for example, by passing the laser light through a rotating diffusion plate, the deterioration in display quality (so-called speckle noise) due to the generation of speckle is reduced while diffusing the laser light. (For example, see Patent Document 1).

JP 2012-194268 A

  By the way, in order to reduce the speckle noise described above, it is necessary to increase the spread angle (diffusion angle) of the light diffused by the diffusion plate. However, in the conventional lighting device, when the diffusion angle of the diffused light is increased by the diffuser plate, the ratio of backscattering increases, and the ratio of the diffused light transmitted through the diffuser plate (total light transmittance) is remarkably reduced. There was a problem.

  The present invention has been proposed in view of such conventional circumstances, and an illumination device capable of reducing speckle noise, and an image quality excellent by providing such an illumination device. It is an object to provide a projector capable of displaying.

In order to achieve the above object, an illumination apparatus according to the present invention includes a light source, a condensing optical system on which light emitted from the light source is incident, and a first light on which light collected by the condensing optical system is incident. 1 light diffusing layer and a second light diffusing layer on which light from the first light diffusing layer is incident, the first light diffusing layer and the second light diffusing layer being predetermined The light incident surface side and the light emission surface side of the translucent base material that can rotate around the rotation axis of the light-transmitting base material are provided across the circumferential direction while facing each other with a space therebetween. The diffusing power of the diffusing layer is larger than that of the first light diffusing layer.

In the illuminating device, the light condensed by the condensing optical system enters the first light diffusion layer. By making the diffusion force of the first light diffusion layer relatively small, backscattering by the first light diffusion layer can be reduced. In addition, since the light condensed by the condensing optical system is diffused relatively weakly by the first diffusion layer and then enters the second light diffusion layer, it is compared with the case where the first light diffusion layer is not provided. Thus, the incident angle to the second light diffusion layer is reduced as a whole. Therefore, the intensity of backscattered light in the second light diffusion layer is reduced. As a result, the total light transmittance is increased. Furthermore, the spread of the spot diameter of the light diffused by the second light diffusing layer does not become larger than necessary so that it cannot be swallowed by the condensing optical system in the subsequent stage, so that it is diffused by the second light diffusing layer. The utilization efficiency of the light increases. Thereby, the light condensed by the condensing optical system can be largely diffused by the light diffusing element while preventing the decrease of the total light transmittance of the diffused light due to the increase in the ratio of backscattering as in the prior art. . Therefore, according to the configuration of the illumination device, it is possible to suppress the generation of speckles, and as a result, it is possible to reduce display quality deterioration (so-called speckle noise) due to the generation of speckles.
In addition, since the first light diffusion layer and the second light diffusion layer are spaced from each other, adjusting the distance affects the backscattering by the first light diffusion layer. The spot diameter of light emitted from the second light diffusion layer can be adjusted without giving.
The first light diffusion layer and the second light diffusion layer are respectively opposed to the light incident surface side and the light emission surface side of the translucent substrate that can rotate around a predetermined rotation axis. Since it is provided over the circumferential direction of the translucent substrate, the light diffusing effect of the light diffusing element is enhanced by changing the irradiation position of the light condensed by the condensing optical system to the light diffusing element. In addition, the heat dissipation effect of the light diffusing element can be enhanced.
Another illumination device according to the present invention includes a light source, a condensing optical system on which light emitted from the light source is incident, and a first light diffusion unit on which light collected by the condensing optical system is incident. And a second light diffusion layer on which light from the first light diffusion layer is incident, the first light diffusion layer having a first diffusion force, and the second light diffusion The layer has a second diffusing force, the second diffusing force is greater than the first diffusing force, and the collected light is diffused by the first light diffusing layer into the second diffusing force. After being diffused with the first diffusion force weaker than the force, the second light diffusion layer diffuses with the second diffusion force stronger than the first diffusion force.
In the illuminating device, the light condensed by the condensing optical system enters the first light diffusion layer. By making the diffusion force of the first light diffusion layer relatively small, backscattering by the first light diffusion layer can be reduced. In addition, since the light condensed by the condensing optical system is diffused relatively weakly by the first diffusion layer and then enters the second light diffusion layer, it is compared with the case where the first light diffusion layer is not provided. Thus, the incident angle to the second light diffusion layer is reduced as a whole. Therefore, the intensity of backscattered light in the second light diffusion layer is reduced. As a result, the total light transmittance is increased. Furthermore, the spread of the spot diameter of the light diffused by the second light diffusing layer does not become larger than necessary so that it cannot be swallowed by the condensing optical system in the subsequent stage, so that it is diffused by the second light diffusing layer. The utilization efficiency of the light increases. Thereby, the light condensed by the condensing optical system can be largely diffused by the light diffusing element while preventing the decrease of the total light transmittance of the diffused light due to the increase in the ratio of backscattering as in the prior art. . Therefore, according to the configuration of the illumination device, it is possible to suppress the generation of speckles, and as a result, it is possible to reduce display quality deterioration (so-called speckle noise) due to the generation of speckles.

  Further, it is preferable that the first light diffusion layer and the second light diffusion layer are provided with a space therebetween.

  According to this configuration, by adjusting the interval, the spot diameter of light emitted from the second light diffusion layer can be adjusted without affecting the backscattering by the first light diffusion layer.

  Further, it is preferable that the second light diffusion layer is disposed at a focal position of the condensing optical system.

  According to this configuration, the spot diameter of the light emitted from the second light diffusion layer can be made smaller than the spot diameter of the light incident on the first light diffusion layer.

  Moreover, it is preferable that the thickness of the second light diffusion layer is larger than the thickness of the first light diffusion layer.

  According to this configuration, the diffusing power of the second light diffusing layer can be made larger than that of the first light diffusing layer.

  A semiconductor laser can be used as the light source.

  According to this configuration, high luminance and high output light can be obtained, and the light source can be miniaturized.

  Further, as the light source, an array light source in which a plurality of the semiconductor lasers are arranged can be used.

  According to this configuration, light with higher luminance and higher output can be obtained using an array light source in which a plurality of semiconductor lasers are arranged.

  Moreover, it is preferable that a collimator optical system is disposed in an optical path between the light source and the condensing optical system.

  According to this configuration, light emitted from the light source can be converted into parallel light and incident on the diffractive optical element.

  In addition, a projector according to the present invention includes an illumination device that emits illumination light, a light modulation device that forms image light obtained by modulating the illumination light according to image information, and a projection optical system that projects the image light. And any one of the above illumination devices is used as the illumination device.

  According to the configuration of the projector, it is possible to perform display with excellent image quality.

It is a top view which shows schematic structure of a projector. It is a top view which shows schematic structure of a 1st illuminating device. It is a top view which shows schematic structure of a 2nd illuminating device. The schematic structure of the light-diffusion element with which a 2nd illuminating device is provided is shown, (a) is the sectional drawing, (b) is the top view. It is sectional drawing for demonstrating the spreading | diffusion operation | movement of the blue light by the light-diffusion element with which a 2nd illuminating device is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

[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 is a projection type image display device that displays a color image (image) on a screen (projection surface) SCR. Further, the projector 1 uses three liquid crystal light valves (liquid crystal panels) corresponding to the respective color lights of red light R, green light G, and blue light B as light modulation devices. Further, the projector 1 uses a semiconductor laser (laser light source) capable of obtaining light with high luminance and high output as the light source of the illumination device.

  Specifically, as shown in FIG. 1, the projector 1 has a first illumination device 2 that irradiates yellow light (first illumination light) Y, and yellow light Y from the first illumination device 2 as red. A color separation optical system 3 that separates light R and green light G, a second illumination device 4 that emits blue light (second illumination light) B, and each color light R, G, B according to image information. Three optical modulators 5R, 5G, and 5B that modulate and form image light corresponding to each color light R, G, and B, and a synthetic optical system 6 that combines the image light from each of the optical modulators 5R, 5G, and 5B And a projection optical system 7 that projects the image light from the synthesis optical system 6 toward the screen SCR.

  In the first illumination device 2, the phosphor is excited by irradiating the phosphor with blue light (excitation light) emitted from the semiconductor laser, and the phosphor light (yellow light) is emitted from the phosphor. The fluorescent light emitted from the phosphor is adjusted to have a uniform luminance distribution (illuminance distribution) and then emitted toward the color separation optical system 3.

  The color separation optical system 3 schematically includes a dichroic mirror 8, a first total reflection mirror 9a, and a second total reflection mirror 9b. Among these, the dichroic mirror 8 has a function of separating the yellow light Y from the first illumination device 2 into the red light R and the green light G, and transmits the separated red light R and the green light G. To reflect. On the other hand, the first total reflection mirror 9a reflects the red light R transmitted through the dichroic mirror 8 toward the red light modulation device 5R. On the other hand, the second total reflection mirror 9b reflects the green light G reflected by the dichroic mirror 8 toward the green light modulation device 5G.

  In the second illumination device 4, the blue light B emitted from the semiconductor laser is adjusted so as to have a uniform luminance distribution (illuminance distribution), and then irradiated toward the blue light modulation device 5B. A third total reflection mirror 9c is arranged in the optical path of the blue light B emitted from the second illumination device 4. The third total reflection mirror 9c reflects the blue light B emitted from the second illumination device 4 toward the blue light modulation device 5B.

  The light modulation devices 5R, 5G, and 5B include liquid crystal light valves (liquid crystal panels), and image light obtained by modulating the color lights R, G, and B according to image information while passing the color lights R, G, and B. Form. A pair of polarizing plates (not shown) are arranged on the incident side and the emission side of each of the light modulation devices 5R, 5G, and 5B, and a mechanism that allows only linearly polarized light in a specific direction to pass therethrough. It has become.

  Further, field lenses 10R, 10G, and 10B that collimate the color lights R, G, and B incident on the light modulators 5R, 5G, and 5B are provided on the light incident surface side of the light modulators 5R, 5G, and 5B. Has been placed.

  The synthesizing optical system 6 comprises a cross dichroic prism. When image light from each of the light modulation devices 5R, 5G, 5B is incident, the image light corresponding to each color light R, G, B is synthesized and synthesized. The emitted image light is emitted toward the projection optical system 7.

  The projection optical system 7 includes a projection lens group, and enlarges and projects the image light synthesized by the synthesis optical system 7 toward the screen SCR. Thereby, an enlarged color video (image) is displayed on the screen SCR.

[First lighting device]
Next, a specific configuration of the first lighting device 2 will be described.
FIG. 2 is a plan view showing a schematic configuration of the first lighting device 2.

  As shown in FIG. 2, the first illumination device 2 includes an array light source 21, a collimator optical system 22, a polarization separation element 23, a condensing optical system 24, a fluorescent light emitting element 25, and an integrator optical system 26. And a polarization conversion element 27 and a superimposing optical system 28.

  Further, in the first illumination device 2, the array light source 21, the collimator optical system 22, the polarization separation element 23, and one of the optical axes ax 1 and ax 2 that are orthogonal to each other on the same plane. Are arranged in this order. On the other optical axis ax2, the fluorescent light emitting element 25, the condensing optical system 24, the polarization separating element 23, the integrator optical system 26, the polarization converting element 27, and the superimposing optical system 28 are arranged in this order. They are arranged side by side.

  The array light source 21 is composed of a plurality of semiconductor lasers 21a arranged. Specifically, a plurality of semiconductor lasers 21a are arranged in an array in a plane orthogonal to the optical axis ax1.

  The semiconductor laser 21a emits blue laser light (hereinafter referred to as excitation light) BL having a peak wavelength in a wavelength range of 440 to 480 nm, for example, as the first light flux. The excitation light BL emitted from each semiconductor laser 2a is coherent linearly polarized light and is emitted toward the polarization separation element 23 in parallel with the optical axis ax1.

  In the array light source 21, the polarization direction of the excitation light BL emitted from each semiconductor laser 21 a is matched with the polarization component (for example, S polarization component) reflected by the polarization separation element 23. Then, the excitation light BL emitted from the array light source 21 enters the collimator optical system 22.

  The collimator optical system 22 converts the excitation light BL emitted from the array light source 21 into parallel light. For example, a plurality of collimator lenses 22a arranged in an array corresponding to each semiconductor laser 21a. Consists of. Then, the excitation light BL converted into parallel light by passing through the collimator optical system 22 enters the polarization separation element 23.

  The polarization separation element 23 is composed of, for example, a dichroic mirror having wavelength selectivity, and this dichroic mirror is disposed in an inclined state toward the fluorescent light emitting element 25 at an angle of 45 ° with respect to the optical axis ax1. Further, the polarization separation element 23 is not limited to a parallel plate shape such as a dichroic mirror, but may be a prism shape such as a dichroic prism.

  The polarization separation element 23 has a polarization separation function for separating the excitation light BL into an S polarization component (one polarization component) and a P polarization component (the other polarization component), and reflects the S polarization component of the excitation light BL. The P-polarized component of the excitation light BL is transmitted. The polarization separation element 23 has a color separation function that transmits light in a wavelength region different from that of the excitation light BL. As described above, the excitation light BL incident on the polarization separation element 23 is totally reflected toward the fluorescent light emitting element 25 as the S-polarized excitation light BL because the polarization direction thereof coincides with the S-polarized light component. The

  The condensing optical system 24 condenses the excitation light BL toward the fluorescent light emitting element 25 and includes at least one condensing lens 24a. Then, the excitation light BL condensed by the condensing optical system 24 enters the fluorescent light emitting element 25.

  The fluorescent light-emitting element 25 is a so-called reflection-type rotating fluorescent plate, and a fluorescent layer 29 that emits fluorescent light Y, a reflective film 30 that reflects fluorescent light Y, and a rotary plate (base material) that supports the fluorescent layer 29. 31 and a drive motor 32 that rotationally drives the rotating plate 31.

  A reflective film 30 and a phosphor layer 29 are laminated on the surface of the rotating plate 31 on the side where the excitation light BL is incident. The reflective film 30 is provided between the rotating plate 31 and the phosphor layer 29. The reflective film 30 and the phosphor layer 29 are provided in a ring shape over the circumferential direction of the rotating plate 31. Then, the excitation light BL enters the phosphor layer 29 from the side opposite to the reflective film 30.

  The phosphor layer 29 includes a phosphor that is excited by absorbing the excitation light BL. The phosphor excited by the excitation light BL emits fluorescent light Y having a peak wavelength in a wavelength region of, for example, 500 to 700 nm as the second light flux.

  The reflective film 30 is made of a dielectric multilayer film or the like, and reflects the fluorescent light Y emitted from the fluorescent material layer 29 toward the side on which the excitation light BL is incident.

  The rotating plate 31 is made of a metal disc having a high heat conductor such as copper, and its central portion is attached to the rotating shaft 32 a of the drive motor 32.

  The drive motor 32 varies the irradiation position of the excitation light BL condensed by the condensing optical system 24 on the phosphor layer 29 while rotating the rotating plate 31 in the circumferential direction. Thereby, it is possible to enhance the heat radiation effect of the heat generated in the phosphor layer 29 by the irradiation of the excitation light BL.

  The fluorescent light Y emitted from the fluorescent light emitting element 25 passes through the condensing optical system 24 and then enters the polarization separating element 23. Further, the fluorescent light Y incident on the polarization separation element 23 enters the integrator optical system 26.

  The integrator optical system 26 equalizes the luminance distribution (illuminance distribution) of the fluorescent light Y, and includes, for example, a lens array 26a and a lens array 26b. The lens array 26a and the lens array 26b are composed of a plurality of lenses arranged in an array. Further, the integrator optical system 26 is not limited to the lens array 26a and the lens array 26b. For example, a rod integrator may be used. Then, the fluorescent light Y whose luminance distribution is made uniform by passing through the integrator optical system 26 enters the polarization conversion element 27.

  The polarization conversion element 27 aligns the polarization direction of the fluorescent light Y, and includes, for example, a combination of a polarization separation film and a retardation plate. Then, the fluorescent light Y whose polarization direction is aligned by passing through the polarization conversion element 27 enters the superimposing optical system 28.

  The superimposing optical system 28 superimposes a plurality of light beams emitted from the integrator optical system 26 on an illuminated area such as a light modulator, and includes at least one superimposing lens 28a. The fluorescent light Y is superimposed by the superimposing optical system 28, whereby the luminance distribution (illuminance distribution) is made uniform and the axial symmetry around the light axis is enhanced. Then, the fluorescent light Y superimposed by the superimposing optical system 28 enters the dichroic mirror 8 shown in FIG.

  In the first illuminating device 2 having the above-described configuration, fluorescent light (yellow light) Y adjusted to have a uniform luminance distribution (illuminance distribution) is used as the first illuminating light, as shown in FIG. The light can be emitted toward the mirror 8.

  The first illumination device 2 is not necessarily limited to the configuration shown in FIG. 2. For example, the spot diameter of the excitation light BL is in the optical path between the collimator optical system 22 and the polarization separation element 23. It is also possible to adopt a configuration in which an afocal optical system that adjusts the light intensity, a homogenizer optical system that converts the intensity distribution of the excitation light BL into a uniform state (so-called top hat distribution), and the like are also possible.

  In the first illumination device 2, the polarization direction of the excitation light BL emitted from each semiconductor laser 21 a included in the array light source 21 is matched with one polarization component (S polarization component) reflected by the polarization separation element 23. However, a configuration in which the other polarization component (P-polarization component) transmitted through the polarization separation element 23 is matched may be adopted.

  In this case, on one optical axis ax1, the array light source 21, the collimator optical system 22, the polarization separation element 23, the condensing optical system 24, and the fluorescent light emitting element 25 are arranged side by side in order. On the optical axis ax2, the polarization separation element 23, the integrator optical system 26, the polarization conversion element 27, and the superposition optical system 28 are arranged in order. The polarization separation element 23 is configured to reflect light in a wavelength region different from that of the excitation light BL.

  Thereby, the excitation light BL incident on the polarization separation element 23 is totally transmitted toward the fluorescent light emitting element 25 as the P-polarized excitation light BL because the polarization direction thereof coincides with the P-polarized light component. On the other hand, the fluorescent light Y emitted from the fluorescent light emitting element 25 passes through the condensing optical system 24 and then enters the polarization separating element 23. Then, the fluorescent light Y incident on the polarization separation element 23 is reflected toward the integrator optical system 26.

  Therefore, even when the first lighting device 2 is changed to the above configuration, the fluorescence (yellow light) Y adjusted to have a uniform luminance distribution (illuminance distribution) is used as the first illumination light. The light can be emitted toward the dichroic mirror 8 shown in FIG.

[Second lighting device]
Next, a specific configuration of the second lighting device 4 will be described.
FIG. 3 is a plan view showing a schematic configuration of the second lighting device 4.

  As shown in FIG. 3, the second illumination device 4 includes an array light source 41, a collimator optical system 42, a front-side condensing optical system 43A, a light diffusing element 44, and a rear-side condensing optical system 43B. And an integrator optical system 45, a polarization conversion element 46, and a superimposing optical system 47.

  Further, in the second illumination device 4, on the optical axis ax3, the array light source 41, the collimator optical system 42, the front condensing optical system 43A, the light diffusing element 44, and the rear condensing optics. The system 43B, the integrator optical system 45, the polarization conversion element 46, and the superimposing optical system 47 are arranged in this order.

  The array light source 41 is composed of a plurality of semiconductor lasers 41a arranged. Specifically, a plurality of semiconductor lasers 41a are arranged in an array in a plane orthogonal to the optical axis ax3.

  The semiconductor laser 41a emits blue laser light (hereinafter referred to as blue light) B having a peak wavelength in a wavelength range of 440 to 480 nm, for example, as the second illumination light. Further, the blue light B emitted from each semiconductor laser 41a is coherent linearly polarized light and is emitted toward the light diffusing element 44 in parallel with the optical axis ax3. Then, the blue light B emitted from the array light source 41 enters the collimator optical system 42.

  The collimator optical system 42 converts the blue light B emitted from the array light source 41 into parallel light. For example, a plurality of collimator lenses 42a arranged in an array corresponding to each semiconductor laser 41a. Consists of. Then, the blue light B converted into parallel light by passing through the collimator optical system 42 is incident on the front-side condensing optical system 43A.

  The front-side condensing optical system 43A condenses the blue light B toward the light diffusing element 44, and includes at least one condensing lens 43c. Then, the blue light B condensed by the front condensing optical system 43 </ b> A enters the light diffusing element 44.

  As shown in FIGS. 3 and 4, the light diffusing element 44 is a so-called transmission-type rotating diffusing plate, and is a rotating plate that transmits the blue light B collected by the front condensing optical system 43A (translucent property) Substrate) 48, a first light diffusion layer 49a disposed on the light incident surface side of the rotating plate 48, a second light diffusion layer 49b disposed on the light emitting surface side of the rotating plate 48, and the rotating plate And a drive motor 50 that rotationally drives 48.

  The rotary plate 48 is made of a light-transmitting disc such as glass or optical resin, and the center thereof is attached to the rotary shaft 50 a of the drive motor 50. The first light diffusion layer 49a and the second light diffusion layer 49b are opposed to each other on the light incident surface and the light emission surface of the rotating plate 48 in a ring shape in the circumferential direction. Is provided.

As the first light diffusion layer 49a and the second light diffusion layer 49b, light having excellent heat resistance and durability, for example, a filler such as a glass frit made of a high refractive material in a binder such as a silicone resin is dispersed. A diffusion layer can be suitably used. In the light diffusing element 44, the thickness t _{2 of} the second light diffusing layer 49b is set so that the diffusing force of the second light diffusing layer 49b described later is larger than the diffusing force of the first light diffusing layer 49a. Is larger (thicker) than the thickness t _{1 of} the first light diffusion layer 49a (t ₁ <t ₂ ). In the present embodiment, glass frit having a refractive index of 1.56 and an average particle size of 3 μm is dispersed in a silicone resin having a refractive index of 1.4 as the first light diffusion layer 49a and the second light diffusion layer 49b. A light diffusion layer was used.

The thickness _{t 1} of the first light diffusion layer 49a thickness _{t 2} of the second light diffusion layer 49b is preferably adjusted within a range of 5 to 40 m. As for the distance between the first light diffusion layer 49a and the second light diffusion layer 49b, the first light diffusion layer 49a and the second light diffusion layer 49b are integrated with the rotating plate 48 interposed therebetween. In the case of being arranged in the position, it can be adjusted as appropriate depending on the thickness of the rotating plate 48. In this case, the thickness of the rotating plate 48 is preferably adjusted in the range of 0.3 to 1 mm.

  The drive motor 50 changes the irradiation position of the blue light B on the first light diffusion layer 49a and the irradiation position of the second light diffusion layer 49b by rotating the rotating plate 48 in the circumferential direction. As a result, the light diffusion effect of the blue light B can be enhanced, and the heat dissipation effect of the light diffusion element 44 can be enhanced. The blue light B diffused by the light diffusing element 44 enters the rear condensing optical system 43B.

  The rear condensing optical system 43B condenses the blue light B diffused by the light diffusing element 44 toward the integrator optical system 45, and includes at least one condensing lens 43d. Then, the blue light B condensed by the rear condensing optical system 43B enters the integrator optical system 45.

  The integrator optical system 45 equalizes the luminance distribution (illuminance distribution) of the blue light B, and includes, for example, a lens array 45a and a lens array 45b. The lens array 45a and the lens array 45b are composed of a plurality of lenses arranged in an array. Further, the integrator optical system 45 is not limited to the lens array 45a and the lens array 45b. For example, a rod integrator may be used. Then, the blue light B whose luminance distribution has been made uniform by passing through the integrator optical system 45 enters the polarization conversion element 46.

  The polarization conversion element 46 aligns the polarization direction of the blue light B, and is composed of, for example, a combination of a polarization separation film and a retardation plate. Then, the blue light B whose polarization direction is aligned by passing through the polarization conversion element 46 enters the superimposing optical system 47.

  The superimposing optical system 47 superimposes a plurality of light beams emitted from the integrator optical system 45 on an illuminated area such as a light modulator, and includes at least one superimposing lens 47a. The blue light B is superimposed by the superimposing optical system 47, whereby the luminance distribution (illuminance distribution) is made uniform and the axial symmetry around the light axis is enhanced. Then, the blue light B superimposed by the superimposing optical system 47 is incident on the third total reflection mirror 9c shown in FIG.

  In the second illuminating device 4 having the above-described configuration, the third total reflection shown in FIG. 1 is the blue light B adjusted to have a uniform luminance distribution (illuminance distribution) as the second illumination light. The light can be emitted toward the mirror 9c.

  Note that the second illumination device 4 is not necessarily limited to the configuration shown in FIG. 3. For example, blue light B is included in the optical path between the collimator optical system 42 and the front-side condensing optical system 43 </ b> A. An afocal optical system that adjusts the spot diameter of the light source, a homogenizer optical system that converts the intensity distribution of the blue light B into a uniform state (so-called top hat distribution), and the like can also be provided.

  By the way, the 2nd illuminating device 4 is an example of the illuminating device to which this invention is applied, By making the diffusing power of the 2nd light-diffusion layer 49b larger than the diffusing force of the 1st light-diffusion layer 49a, It is possible to suppress the generation of speckle.

  Specifically, in the light diffusing element 44 provided in the second lighting device 4, as shown in FIG. 5, the first light diffusing layer 49a is made by relatively reducing the diffusing force of the first light diffusing layer 49a. Can reduce backscatter.

  In the light diffusing element 44, a second light diffusing layer 49a is disposed at the focal position of the front-side condensing optical system 43A. Thereby, the spot diameter of the blue light B emitted from the second light diffusion layer 49b can be made smaller than the spot diameter of the blue light B incident on the first light diffusion layer 49a. The spot diameter of the blue light B emitted from the second light diffusion layer 49b can be adjusted by the diffusion force of the first light diffusion layer 49a. The smaller the diffusing power of the first light diffusing layer 49a, the smaller the spot diameter of the blue light B emitted from the second light diffusing layer 49b. In addition, the incident angle of the blue light B to the second light diffusion layer 49b as a whole is smaller than in the case where the first light diffusion layer 49a is not provided. For this reason, the intensity of the backscattered light of the blue light B in the second light diffusion layer 49b is reduced. As a result, the total light transmittance of the blue light B can be increased.

  Furthermore, the spread angle (diffusion angle) of the spot diameter of the blue light B diffused by the second light diffusion layer 49b does not become unnecessarily large enough that it cannot be swallowed by the condensing optical system 43B on the rear side. The utilization efficiency of the blue light B diffused by the second light diffusion layer 49b can be increased.

  Further, since the first light diffusion layer 49a and the second light diffusion layer 49b are provided with a space therebetween, adjusting the space affects the backscattering by the first light diffusion layer 49a. The spot diameter of the blue light B emitted from the second light diffusing layer 49b can be adjusted without giving any light.

  As described above, in the second illuminating device 4, the light is condensed by the front-side condensing optical system 43A while preventing a decrease in the total light transmittance of the diffused light due to an increase in the ratio of backscattering as in the conventional case. The blue light B thus made can be largely diffused by the light diffusing element 44.

  Therefore, in this 2nd illuminating device 4, generation | occurrence | production of a speckle can be suppressed, As a result, it becomes possible to reduce the display quality fall (what is called speckle noise) by generation | occurrence | production of a speckle. In addition, the projector 1 can display with excellent image quality by including the second illumination device 4.

In the second lighting device 4, the thickness t2 of the _second light diffusion layer 49b is set so that the diffusion power of the second light diffusion layer 49b is larger than the diffusion power of the first light diffusion layer 49a. It is larger (thick) than the thickness t _{1 of} the first light diffusion layer 49a (t ₁ <t ₂ ).

In contrast, irrespective of the thickness t ₁ of the first light diffusion layer 49a to the thickness t ₂ of the second light diffusion layer 49b, by adjusting the concentration of the filler dispersed in the binder described above The diffusing power of the first light diffusing layer 49a and the diffusing power of the second light diffusing layer 49b can be appropriately adjusted. For example, as the first light diffusion layer 49a, a material obtained by dispersing 20 parts by mass of glass frit in 80 parts by mass of silicone resin is used, and as the second light diffusion layer 49b, 50 parts by mass of 50 parts by mass of silicone resin. A portion in which part of the glass frit is dispersed can be used.

In addition, this invention is not necessarily limited to the thing of the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above-described embodiment, the first light diffusion layer 49a and the second light diffusion layer 49b are prepared by dispersing filler in a binder. However, the present invention is not limited thereto, and is formed on the surface of a glass substrate, for example. The uneven surface may be used as a light diffusion layer.

  In addition, as for the light sources included in the first illumination device 2 and the second illumination device 4, the array light source 21 and the array light source 41 in which a plurality of semiconductor lasers 21a and semiconductor lasers 41a are arranged are illustrated, but the configuration is not limited thereto. Instead, it may consist of one light source. Furthermore, as the light source, the semiconductor laser 21a and the semiconductor laser 41a described above can be suitably used, but a solid light emitting element such as a light emitting diode (LED) may be used.

  Moreover, in the said embodiment, although the projector 1 provided with the light modulation apparatus 5R, the light modulation apparatus 5G, and the light modulation apparatus 5B was illustrated, it is also applicable to the projector which displays a color image | video (image) with one light modulation apparatus. Is possible. Further, the light modulation device is not limited to the above-described liquid crystal panel, and for example, a digital mirror device (DMD: registered trademark of Texas Instruments Inc., USA) can be used.

  DESCRIPTION OF SYMBOLS 1 ... Projector 2 ... 1st illumination device 3 ... Color separation optical system 4 ... 2nd illumination device 5R, 5G, 5B ... Light modulation device 6 ... Synthesis optical system 7 ... Projection optical system 8 ... Dichroic mirror 9a ... 1st Total reflection mirror 9b ... Second total reflection mirror 9c ... Third total reflection mirror 10R, 10G, 10B ... Field lens 21 ... Array light source 21a ... Semiconductor laser 22 ... Collimator optical system 23 ... Polarization separation element 24 ... Collection Optical optical system 25 ... Fluorescent light emitting element 26 ... Integrator optical system 27 ... Polarization conversion element 28 ... Superimposing optical system 29 ... Phosphor layer 30 ... Reflective film 31 ... Rotating plate (base material) 32 ... Drive motor 41 ... Array light source 41a ... Semiconductor laser 42 ... collimator optical system 43A ... front-side condensing optical system 43B ... rear-side condensing optical system 44 ... light diffusing element 45 ... Integrator optical system 46 ... Polarization conversion element 47 ... Superimposing optical system 48 ... Rotating plate (translucent substrate) 49a ... First light diffusion layer 49b ... Second light diffusion layer 50 ... Drive motor SCR ... Screen BL ... excitation light Y ... fluorescence light (yellow light) R ... red light G ... green light B ... blue light

Claims (8)

A light source;
A condensing optical system on which light emitted from the light source is incident;
A first light diffusion layer on which light collected by the condensing optical system is incident;
A second light diffusion layer on which light from the first light diffusion layer is incident,
The first light diffusing layer and the second light diffusing layer are spaced apart from each other on the light incident surface side and the light emitting surface side of the translucent substrate that can rotate around a predetermined rotation axis. While facing each other, provided in the circumferential direction,
The illuminating device characterized in that the diffusing power of the second light diffusing layer is larger than that of the first light diffusing layer. A light source;
A condensing optical system on which light emitted from the light source is incident;
A first light diffusion layer on which light collected by the condensing optical system is incident;
A second light diffusion layer on which light from the first light diffusion layer is incident,
The first light diffusion layer has a first diffusion power;
The second light diffusion layer has a second diffusion power;
The second diffusing power is greater than the first diffusing power;
The condensed light is diffused by the first light diffusion layer with the first diffusion force weaker than the second diffusion force, and then the first light diffusion layer causes the first light diffusion layer to diffuse the first light. The illuminating device is diffused with the second diffusing force stronger than the diffusing force of.   The illumination device according to claim 1, wherein the second light diffusion layer is disposed at a focal position of the condensing optical system.   The lighting device according to claim 1, wherein a thickness of the second light diffusion layer is larger than a thickness of the first light diffusion layer. The illumination device according to any one of claims 1 to 4 , wherein a semiconductor laser is used as the light source. The illumination device according to claim 5 , wherein an array light source in which a plurality of the semiconductor lasers are arranged is used as the light source. The lighting device according possible to claim 5 or 6, characterized in that the collimator optical system in the optical path is arranged between the focusing optical system and the light source. An illumination device that emits illumination light;
A light modulation device for forming image light obtained by modulating the illumination light according to image information;
A projection optical system for projecting the image light,
As the lighting device, a projector, which comprises using a lighting device according to any one of claims 1-7.

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