# Patent

## Title
Projector

## Abstract

A projector includes: a first solid-state light source device which includes a first solid-state light source emitting main excitation light, and a fluorescent layer converting main excitation light to light including a first color light component and a second color light component different from the first color light component, and emitting converted light; a second solid-state light source device which includes a second solid-state light source emitting a third color light component different from the first color light component and the second color light component; a light modulation device modulating the first color light component, the second color light component, and the third color light component in accordance with image information; a projection optical system projecting the modulated light components from the light modulation device as a projection image; and a third solid-state light source device which includes a third solid-state light source emitting auxiliary excitation light, wherein the fluorescent layer is configured such that auxiliary excitation light is input thereto in a direction different from a direction in which main excitation light is input, and the fluorescent layer is configured to convert auxiliary excitation light to light including the first color light component and the second color light component, and to emit converted light.

## Background
BACKGROUND
1. Technical Field
The present invention relates to a projector, and in particular, to a projector using a solid-state light source.
2. Related Art
A projector is known which includes a single solid-state light source device emitting white light, a color separating and guiding optical system separating light from the single solid-state light source device into a red light component, a green light component, and a blue light component, a light modulation device modulating the respective color light components from the color separating and guiding optical system in accordance with image information, and a projection optical system projecting the modulated light components from the light modulation device as a projection image (for example, see JP-A-2005-274957). According to the projector described in JP-A-2005-274957, the three color light components which are obtained by separating white light emitted from the single solid-state light source device are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the light modulation device. Unlike a projector which includes three solid-state light source devices, the light-emission efficiency (brightness per unit power) or the temperature characteristic (the change of light amount with change in temperature) does not differ between the solid-state light source devices. As a result, the color balance of the projection image can be stabilized.
A projector is also known which includes a solid-state light source device emitting a red light component, a solid-state light source device emitting a green light component, a solid-state light source device emitting a blue light component, a light modulation device modulating the color light components from the respective solid-state light source devices in accordance with image information, and a projection optical system projecting the modulated light components from the light modulation device as a projection image (for example, see JP-A-2002-268140). According to the projector described in JP-A-2002-268140, separate solid-state light source devices (a solid-state light source device emitting a red light component, a solid-state light source device emitting a green light component, and a solid-state light source device emitting a blue light component) are provided for the respective color light components (red light component, green light component, and blue light component), and the three color light components which are respectively emitted from the three solid-state light source devices are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the light modulation device. Thus, the projection image can be brightened compared to a projector which includes a single solid-state light source device.
However, according to the projector described in JP-A-2005-274957, since white light including a red light component, a green light component, and a blue light component is generated from the single solid-state light source device, unlike a projector which includes three solid-state light source devices, a significant thermal load is concentrated on the single solid-state light source device. As a result, it is difficult to further brighten the projection image.
According to the projector described in JP-A-2002-268140, it is difficult to make the three solid-state light source devices respectively emitting the red light component, the green light component, and the blue light component (the solid-state light source device emitting the red light component, the solid-state light source device emitting the green light component, and the solid-state light source device emitting the blue light component) the same light-emission efficiency or temperature characteristic. For this reason, it is difficult to stabilize the color balance of the projection image.
SUMMARY
An advantage of some aspects of the invention is that it provides a projector capable of brightening a projection image compared to a projector including a single solid-state light source device, and stabilizing the color balance of the projection image compared to a projector including separate solid-state light source devices for respective color light components.
A projector according to an aspect of the invention includes a first solid-state light source device which includes a first solid-state light source emitting main excitation light, and a fluorescent layer converting main excitation light to light including a first color light component and a second color light component different from the first color light component, and emitting converted light, a second solid-state light source device which includes a second solid-state light source emitting a third color light component different from the first color light component and the second color light component, a light modulation device modulating the first color light component, the second color light component, and the third color light component in accordance with image information, a projection optical system projecting the modulated light components from the light modulation device as a projection image, and a third solid-state light source device which includes a third solid-state light source emitting auxiliary excitation light. The fluorescent layer is configured such that auxiliary excitation light is input thereto in a direction different from a direction in which main excitation light is input, and the fluorescent layer is configured to convert auxiliary excitation light to light including the first color light component and the second color light component, and to emit converted light.
According to this projector, the two color light components (first color light component and second color light component) emitted from the first solid-state light source device and the one color light component (third color light component) emitted from the second solid-state light source device are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the light modulation device. Therefore, the thermal load imposed on the respective solid-state light source devices can be reduced compared to a projector which includes a single solid-state light source device. As a result, the projection image can be brightened compared to a projector which includes a single solid-state light source device.
According to this projector, two color light components (first color light component and second color light component) from among the three color light components (red light component, green light component, and blue light component) which are modulated by the light modulation device are generated by using a common solid-state light source (first solid-state light source and third solid-state light source). Therefore, the color balance of the projection image can be stabilized compared to a projector which includes separate three solid-state light source devices for respective color light components.
As a result, the projector according to the aspect of the invention can brighten the projection image compared to a projector which includes a single solid-state light source device, and can stabilize the color balance of the projection image compared to a projector which includes separate three solid-state light source devices for respective color light components.
According to this projector, the first solid-state light source device converts two kinds of excitation light of main excitation light and auxiliary excitation light to light including the first color light component and the second color light component, and emits converted light. Therefore, the projection image can be further brightened.
The projector according to the aspect of the invention may further include a first collimation optical system parallelizing light emitted from the first solid-state light source device, a second collimation optical system parallelizing light emitted from the second solid-state light source device, a third collimation optical system having an optical axis orthogonal to an optical axis of the first collimation optical system and parallelizing auxiliary excitation light emitted from the third solid-state light source device, and an auxiliary excitation light reflection optical element disposed in a region including an intersection between the optical axis of the first collimation optical system and the optical axis of the third collimation optical system. The auxiliary excitation light reflection optical element may directly transmit light which is converted by the fluorescent layer and emitted from the fluorescent layer, and may reflect auxiliary excitation light from the third solid-state light source device to input auxiliary excitation light to the fluorescent layer in an opposite direction to a direction in which main excitation light from the first solid-state light source is input.
With this configuration, auxiliary excitation light is input to the fluorescent layer in the direction different from the direction in which main excitation light is input.
In this case, auxiliary excitation light which is converted to parallel light by the third collimation optical system is reflected as parallel light by the auxiliary excitation light reflection optical element, is focused by the first collimation optical system, and is efficiently input to the light-emission region of the fluorescent layer. Therefore, it is possible to suppress the spread of the light-emission region due to the third solid-state light source device being further provided.
The projector according to the aspect of the invention may further include a reflection-type polarizing plate located at the back of the first collimation optical system to directly transmit one polarized component from among polarized components included in light emitted from the first solid-state light source device and to reflect another polarized component toward the fluorescent layer.
Meanwhile, when the light modulation device of the projector is a light modulation device which uses a liquid crystal light modulation device, in general, only one polarized component from among polarized components included in light is used for modulation, and another polarized component is not used for modulation. Thus, when a light source which emits light including one polarized component and another polarized component is used as the light source of the projector, it is necessary to remove another polarized component by an incidence-side polarizing plate, which causes degradation in light use efficiency.
In contrast, with the above-described configuration, another polarized component is returned again to the fluorescent layer and reflected by the surface of the fluorescent layer. Thus, part of another polarized component is converted to one polarized component and reused, such that light use efficiency can be improved, and consequently the projection image can be further brightened.
With the above-described configuration, another polarized component is converted to parallel light by the first collimation optical system. Then, parallel light is reflected by the reflection-type polarizing plate, is focused by the first collimation optical system, and is efficiently input to the light-emission region of the fluorescent layer. Therefore, it is possible to suppress the spread of the light-emission region due to the reflection-type polarizing plate being further provided.
In the projector according to the aspect of the invention, main excitation light and auxiliary excitation light may be blue light components, the first color light component may be a red light component, the second color light component may be a green light component, and the third color light component may be a blue light component.
With this configuration, light including a red light component and a green light component can be emitted from the first solid-state light source device by using the first solid-state light source and the third solid-state light source emitting blue light components together.
Meanwhile, there is a problem in that a solid-state light source which is used in a solid-state light source device emitting a green light component has relatively low light-emission efficiency compared to a solid-state light source which is used in a solid-state light source device emitting a red light component and a solid-state light source which is used in a solid-state light source device emitting a blue light component. In contrast, the projector according to the aspect of the invention is configured such that green light components are generated by using the first solid-state light source and the third solid-state light source (emitting blue light components together) which have high light-emission efficiency compared with a solid-state light source which is used in a solid-state light source device emitting a green light component. Therefore, light-emission efficiency can be increased compared to a case where a solid-state light source device emitting a green light component is used.
In the projector according to the aspect of the invention, the first solid-state light source, the second solid-state light source, and the third solid-state light source may have the same temperature characteristic.
With this configuration, with regard to all of the color light components, change in the light amount with change in temperature can be made the same. Therefore, the color balance of the projection image can be further stabilized.
In the projector according to the aspect of the invention, main excitation light and auxiliary excitation light may be ultraviolet light, the first color light component may be a red light component, the second color light component may be a green light component, and the third color light component may be a blue light component.
With this configuration, light including a red light component and a green light component can be emitted from the first solid-state light source device by using the first solid-state light source and the third solid-state light source emitting ultraviolet light together.
A green light component is generated by using the first solid-state light source and the third solid-state light source (emitting ultraviolet light together) which have high light-emission efficiency compared to a solid-state light source which is used in a solid-state light source device emitting a green light component. Therefore, light-emission efficiency can be increased compared to a case where a solid-state light source device emitting a green light component is used.
Various kinds of fluorescent materials are known to efficiently convert ultraviolet light, thus the selection width of a fluorescent material in the fluorescent layer is widened.
In the projector according to the aspect of the invention, main excitation light may be one of a blue light component and ultraviolet light, auxiliary excitation light may be the other one of the blue light component and ultraviolet light, the first color light component may be a red light component, the second color light component may be a green light component, and the third color light component may be a blue light component.
With this configuration, light including a red light component and a green light component can be emitted from the first solid-state light source device by using the first solid-state light source emitting one of a blue light component and ultraviolet light and the third solid-state light source emitting the other one of the blue light component and ultraviolet light.
A green light component is generated by using the first solid-state light source (emitting one of a blue light component and ultraviolet light) and the third solid-state light source (emitting the other one of the blue light component and ultraviolet light) which have high light-emission efficiency compared to a solid-state light source which is used in a solid-state light source device emitting a green light component. Therefore, light-emission efficiency can be increased compared to a case where a solid-state light source device emitting a green light component is used.
In the projector according to the aspect of the invention, the fluorescent layer may be formed of a layer containing a YAG-based fluorescent material, a silicate-based fluorescent material, or a TAG-based fluorescent material.
The above-described fluorescent material can efficiently convert excitation light (main excitation light and auxiliary excitation light) to light including a red light component and a green light component, and can emit converted light. Further, the fluorescent material itself has high reliability. Therefore, with the above-described configuration, the projection image can be further brightened, and thus a high-reliable projector can be provided.
The YAG-based fluorescent material refers to a fluorescent material, such as (Y,Gd)3(Al,Ga)5O12:Ce, which has a garnet crystal structure and is based on composite oxide of yttrium and aluminum.
The silicate-based fluorescent material refers to a fluorescent material, such as (Ca,Sr,Ba)SiO4:Eu, which is based on silicate salt (silicate) with various components introduced.
The TAG-based fluorescent material refers to a fluorescent material, such as Tb3Al5O12:Ce, which has a garnet crystal structure and is based on composite oxide of terbium and aluminum.
In the projector according to the aspect of the invention, a function may be provided to remove a yellow light component from light from the first solid-state light source device.
With this configuration, the yellow light component can be removed from light from the first solid-state light source device. As a result, color reproducibility can be prevented from being deteriorated due to the yellow light component.
In the projector according to the aspect of the invention, a function may not be provided to remove a yellow light component from light from the first solid-state light source device. In this case, the yellow light component which is included in light from the first solid-state light source device can be positively used, and a brighter projection image can be projected.
In the projector according to the aspect of the invention, a function may be provided to remove main excitation light from light from the first solid-state light source device.
Meanwhile, in the projector according to the aspect of the invention, part of main excitation light emitted from the first solid-state light source device may transmit the fluorescent layer directly, which may cause degradation in color reproducibility or deterioration of the light modulation device.
However, with the above-described configuration, main excitation light can be removed from light from the first solid-state light source device. As a result, it is possible to suppress degradation in color reproducibility or deterioration of the light modulation device due to main excitation light.



BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
FIG. 1 is a plan view showing optical systems of a projector 1000 according to a first embodiment.
FIGS. 2A to 2C are diagrams illustrating a first solid-state light source device 20, a third solid-state light source device 40, and a second solid-state light source device 120 in the projector 1000 according to the first embodiment.
FIGS. 3A to 3D are graphs showing relative light-emission intensity of a first solid-state light source 24, a fluorescent layer 28, a third solid-state light source 44, and a second solid-state light source 124 in the projector 1000 according to the first embodiment.
FIG. 4 is a plan view showing optical systems of a projector 1002 according to a second embodiment.
FIG. 5 is a plan view showing optical systems of a projector 1004 according to a third embodiment.
FIG. 6 is a plan view showing optical systems of a projector 1006 according to a fourth embodiment.



DESCRIPTION OF EXEMPLARY EMBODIMENTS
Hereinafter, a projector according to exemplary embodiments of the invention will be described based on embodiments shown in the drawings.
First Embodiment
First, the configuration of a projector 1000 according to a first embodiment will be described.
FIG. 1 is a plan view showing optical systems of a projector 1000 according to a first embodiment.
FIGS. 2A to 2C are diagrams illustrating a first solid-state light source device 20, a third solid-state light source device 40, and a second solid-state light source device 120 in the projector 1000 according to the first embodiment. FIG. 2A is a sectional view of a first solid-state light source device 20. FIG. 2B is a sectional view of a third solid-state light source device 40. FIG. 2C is a sectional view of a second solid-state light source device 120.
FIGS. 3A to 3D are graphs showing relative light-emission intensity of a first solid-state light source 24, a fluorescent layer 28, a third solid-state light source 44, and a second solid-state light source 124 in the projector 1000 according to the first embodiment. FIG. 3A is a graph showing relative light-emission intensity of a first solid-state light source 24. FIG. 3B is a graph showing relative light-emission intensity of a fluorescent layer 28. FIG. 3C is a graph showing relative light-emission intensity of a third solid-state light source 44. FIG. 3D is a graph showing relative light-emission intensity of a second solid-state light source 124. The term “relative light-emission intensity” refers to the characteristic regarding intensity of light with a certain wavelength at the time of emission when a voltage is applied in the case of a solid-state light source and when excitation light is input in the case of a fluorescent layer. In the graphs, the vertical axis represents relative light-emission intensity. Light-emission intensity with a wavelength having the maximum light-emission intensity is set to 1. In the graphs, the horizontal axis represents a wavelength.
As shown in FIG. 1, the projector 1000 according to the first embodiment includes a first illumination device 10, a second illumination device 110, a color separating and guiding optical system 300, three liquid crystal light modulation devices 400R, 400G, and 400B serving as a light modulation device, a cross dichroic prism 500, and a projection optical system 600.
The first illumination device 10 includes a first solid-state light source device 20, a first collimation optical system 30, a third solid-state light source device 40, a third collimation optical system 50, a dichroic mirror 60, and a rod integrator optical system 70.
As shown in FIG. 2A, the first solid-state light source device 20 is a light-emitting diode which has a base 22, a first solid-state light source 24, a fluorescent layer 26, and a seal member 28. The first solid-state light source device 20 emits light including a red light component, a green light component, and a yellow light component (see FIG. 3B which will be described below). The first solid-state light source device 20 has lead wires and the like in addition to the above-described constituent elements, but the lead wires and the like will not be shown or described.
The base 22 is a base on which the first solid-state light source 24 is mounted.
The first solid-state light source 24 emits blue light component (the peak of light-emission intensity: about 460 nm, see FIG. 3A) as excitation light. Referring to FIG. 3A, reference numeral B denotes a color light component which is emitted as excitation light (blue light component) from the first solid-state light source 24. The first solid-state light source 24 includes gallium nitride as a main component and has a pn junction-type structure. The first solid-state light source may not have a pn junction-type structure, but may have a double hetero junction-type structure, a quantum well junction-type structure, or the like.
A reflecting layer (not shown) is formed between the first solid-state light source 24 and the base 22. A blue light component emitted from the first solid-state light source toward the base 22 is reflected toward the fluorescent layer 26 by the reflecting layer.
The fluorescent layer 26 is formed of a layer containing a (Y,Gd)3(Al,Ga)5O12:Ce which is a YAG-based fluorescent material, and is disposed in the illuminated region of the first solid-state light source 24. The fluorescent layer 26 is most efficiently excited by a blue light component with a wavelength of about 460 nm. As shown in FIG. 3B, the fluorescent layer 26 converts a blue light component emitted from the first solid-state light source 24 and a third solid-state light source 44 (which will be described below) to light including a red light component (the peak of light-emission intensity: about 610 nm), a yellow light component (the peak of light-emission intensity: about 580 nm), and a green light component (the peak of light-emission intensity: about 550 nm), and emits converted light. Referring to FIG. 3B, reference numeral B denotes a color light component, which can be used as a red light component, from among the light components emitted from the fluorescent layer 26. Reference numeral G denotes a color light component, which can be used as a green light component, from among the light components emitted from the fluorescent layer 26. Reference numeral Y denotes a color light component which is emitted as a yellow light component from the fluorescent layer.
The seal member 28 is formed of transparent epoxy resin, and protects the first solid-state light source 24 and the fluorescent layer 26.
As shown in FIG. 1, the first collimation optical system 30 includes a convex meniscus lens 32 which suppresses the spread of light from the first solid-state light source device 20, and a convex lens 34 which parallelizes light from the convex meniscus lens 32. As a whole, the collimation optical system 30 has a function to parallelize light from the first solid-state light source device 20.
As shown in FIG. 2B, the third solid-state light source device 40 is a light-emitting diode which has a base 42, a third solid-state light source 44, and a seal member 48, and emits a blue light component (see FIG. 3C which will be described below). The third solid-state light source device 40 has lead wires and the like in addition to the above-described constituent elements, but the lead wires and the like will not be shown or described.
As shown in FIG. 3C, the third solid-state light source 44 emits a blue light component (the peak of light-emission intensity: about 460 nm) as auxiliary excitation light. In FIG. 3C, reference numeral B denotes a color light component which is emitted as a color light component (blue light component) from the third solid-state light source 44.
The base 42, the third solid-state light source 44, and the seal member 48 respectively have the same configuration as the base 22, the first solid-state light source 24, and the seal member 28, thus detailed description thereof will not be repeated.
As shown in FIG. 1, the third collimation optical system 50 includes a convex meniscus lens 52 suppressing the spread of auxiliary excitation light (blue light component) from the third solid-state light source device 40, and a convex lens 54 parallelizing auxiliary excitation light (blue light component) from the convex meniscus lens 52. As a whole, the third collimation optical system 50 has a function to parallelize auxiliary excitation light (blue light component) from the third solid-state light source device 40. The third collimation optical system 50 has an optical axis orthogonal to an optical axis of the first collimation optical system 30.
The dichroic mirror 60 is disposed in a region including an intersection between the optical axis of the first collimation optical system 30 and the optical axis of the third collimation optical system 50. The dichroic mirror 60 is an auxiliary excitation light reflection optical element which directly transmits light which is converted by the fluorescent layer 26 and emitted from the fluorescent layer 26, and reflects auxiliary excitation light (blue light component) from the third solid-state light source device 40 to input auxiliary excitation light (blue light component) to the fluorescent layer 26 in an opposite direction to a direction in which main excitation light (blue light component) from the first solid-state light source 24 is input. Specifically, the dichroic mirror 60 is a mirror which has a wavelength selective transmission film formed on a substrate to reflect a blue light component and to transmit a red light component, a green light component, and a yellow light component. In FIG. 1, reference numeral B denotes a blue light component which is reflected by the dichroic mirror 60. In FIG. 1, a dotted-line arrow (see reference numeral R,G,Y) which passes through the dichroic mirror 60 denotes a red light component, a green light component, and a yellow light component which transmit the dichroic mirror 60.
The dichroic mirror 60 reflects main excitation light (blue light component) having directly transmitted the fluorescent layer 26. The blue light component having transmitted the dichroic mirror 60 is removed outside the system. That is, the projector 1000 has a function to remove main excitation light (blue light component) by the dichroic mirror 60.
The rod integrator optical system 70 includes a convex lens 72, a rod lens 74, and a convex lens 76.
The convex lens 72 focuses parallel light from the first collimation optical system 30 and guides focused light to the incidence surface of the rod lens 74.
The rod lens 74 is a solid columnar lens. The rod lens 74 multiply reflects light input from the incidence surface within the plane to make light uniform, and emits light having a uniform in-plane light-emission intensity distribution from the emission surface. As the rod lens, a hollow columnar lens, instead of a solid columnar lens, may be used.
The convex lens 76 substantially parallelizes light emitted from the emission surface of the rod lens 74, and guides relevant light to the image forming regions of the liquid crystal light modulation devices 400R and 400G.
The second illumination device 110 includes a second solid-state light source device 120, a collimation optical system 130, and a rod integrator optical system 170.
As shown in FIG. 2C, the second solid-state light source device 120 is a light-emitting diode which has a base 122, a second solid-state light source 124, and a seal member 128, and emits a blue light component (see FIG. 3C which will be described below). The second solid-state light source device 120 has lead wires and the like in addition to the above-described constituent elements, but the lead wires and the like will not be shown or described.
As shown in FIG. 3D, the second solid-state light source 124 emits blue light component (the peak of light-emission intensity: about 460 nm) as a color light component. In FIG. 3D, reference numeral B denotes a color light component which is emitted as a color light component (blue light component) from the second solid-state light source 124.
The base 122, the second solid-state light source 124, and the seal member 128 respectively have the same configuration as the base 22, the first solid-state light source 24, and the seal member 28, thus detailed description thereof will not be repeated.
The first solid-state light source 24, the third solid-state light source 44, and the second solid-state light source 124 are formed of the same material by the same manufacturing method, and have the same structure. For this reason, the first solid-state light source 24, the third solid-state light source 44, and the second solid-state light source 124 have the same temperature characteristic, such that change in the light amount with change in temperature is identical.
As shown in FIG. 1, the second collimation optical system 130 includes a convex meniscus lens 132 suppressing the spread of the blue light component from the second solid-state light source device 120, and a convex lens 134 parallelizing the blue light component from the convex meniscus lens 132. As a whole, the second collimation optical system 130 has a function to parallelize the blue light component from the second solid-state light source device 120.
The rod integrator optical system 170 includes a convex lens 172, a rod lens 174, and a convex lens 176.
The convex lens 172 focuses parallel light from the second collimation optical system 130 and guides focused light to the incidence surface of the rod lens 174.
The rod lens 174 is a solid columnar lens. The rod lens 174 multiply reflects light input from the incidence surface within the plane to make light uniform, and emits light having a uniform in-plane light-emission intensity distribution from the emission surface. As the rod lens, a hollow columnar lens, instead of a solid columnar lens, may be used.
The convex lens 176 substantially parallelizes light emitted from the emission surface of the rod lens 174, and guides relevant light to the image forming region of the liquid crystal light modulation device 400B.
The color separating and guiding optical system 300 includes a dichroic mirror 310 which is disposed upstream of the optical path, a dichroic mirror 320 and a reflecting mirror 330 which are disposed downstream of the optical path, and a reflecting mirror 340 for a blue light component. The color separating and guiding optical system 300 has a function to separate light from the first illumination device 10 into a red light component and a green light component, and to guide the color light components, the red light component and the green light component, to the liquid crystal light modulation devices 400R and 400G to be illuminated, and a function to guide the blue light component from the second illumination device 110 to the liquid crystal light modulation device 400B to be illuminated.
The dichroic mirrors 310 and 320 are mirrors which have a wavelength selective transmission film formed on the substrate to reflect light having a predetermined wavelength region and to transmit light having another wavelength region.
The dichroic mirror 310 is a dichroic mirror which reflects a green light component, and transmits a red light component and a yellow light component.
The dichroic mirror 320 is a dichroic mirror which reflects a red light component, and transmits a yellow light component. The yellow light component having transmitted the dichroic mirror 320 is removed outside the system. That is, the projector 1000 has a function to remove the yellow light component by the dichroic mirror 320. In FIG. 1, a dotted-line arrow (see reference numeral Y) extending from the dichroic mirror 320 denotes the yellow light component having transmitted the dichroic mirror 320.
The reflecting mirror 330 is a reflecting mirror which reflects a green light component.
The red light component having transmitted the dichroic mirror 310 is reflected by the dichroic mirror 320, and is input to the image forming region of the liquid crystal light modulation device 400R for a red light component.
The green light component having been reflected by the dichroic mirror 310 is further reflected by the reflecting mirror 330, and is input to the image forming region of the liquid crystal light modulation device 400G for a green light component.
The blue light component from the second illumination device 110 is reflected by the reflecting mirror 340, and is input to the image forming region of the liquid crystal light modulation device 400B for a blue light component.
The liquid crystal light modulation devices 400R, 400G, and 400B modulate the input color light components in accordance with image information to form a color image, and will be illuminated by the first illumination device 10 and the second illumination device 110. Though not shown, incidence-side polarizing plates are respectively disposed between the dichroic mirror 320 and the liquid crystal light modulation device 400R, between the reflecting mirror 330 and the liquid crystal light modulation device 400G, and between the reflecting mirror 340 and the liquid crystal light modulation device 400B. Emission-side polarizing plates are respectively disposed between the liquid crystal light modulation devices 400R, 400G, and 400B and the cross dichroic prism 500. Light modulation of the respective input color light components is carried out by the incidence-side polarizing plates, the liquid crystal light modulation devices 400R, 400G, and 400B, and the emission-side polarizing plates.
The liquid crystal light modulation devices 400R, 400G, and 400B are transmission-type liquid crystal light modulation devices in which liquid crystal serving as an electro-optical material is sealed between a pair of transparent glass substrates. For example, each of the liquid crystal light modulation devices 400R, 400G, and 400B modulates the polarization direction of one linearly polarized light emitted from the corresponding incidence-side polarizing plate in accordance with a given image signal with a polysilicon TFT as a switching element.
The cross dichroic prism 500 is an optical element which combines modulated optical images for the respective color light components emitted from the emission-side polarizing plates to form a color image. The cross dichroic prism 500 is formed by bonding four rectangular prisms to each other and substantially has a square shape in plan view. A dielectric multilayer film is formed at an interface having a substantially X shape of the bonded rectangular prisms. A dielectric multilayer film formed at one interface having a substantially X shape reflects the red light component, and a dielectric multilayer film formed at another interface reflects the blue light component. These dielectric multilayer films cause the red light component and the blue light component to be bent and arranged in the traveling direction of the green light component, such that the three color light components are combined.
The color image emitted from the cross dichroic prism 500 is enlarged and projected by the projection optical system 600 to form an image on a screen SCR.
Next, the effects of the projector 1000 according to the first embodiment will be described.
According to the projector 1000 of the first embodiment, the two color light components (red light component and green light component) emitted from the first solid-state light source device 20 and one color light component (blue light component) emitted from the second solid-state light source device 120 are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 400R, 400G, and 400B. Therefore, the thermal load imposed on the respective solid-state light source devices can be reduced compared to a projector which includes a single solid-state light source device. As a result, the projection image can be brightened compared to a projection which includes a single solid-state light source device.
According to the projector 1000 of the first embodiment, the two color light components (red light component and green light component) from among the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 400R, 400G, and 400B are generated by using the common solid-state light source (first solid-state light source 24 and third solid-state light source 44). Therefore, the color balance of the projection image can be stabilized compared to a projector which includes separate three solid-state light source devices for respective color light components.
As a result, the projector 1000 of the first embodiment can brighten the projection image compared to a projector which includes a single solid-state light source device, and can stabilize the color balance of the projection image compared to a projector which includes separate three solid-state light source devices for respective color light components.
According to the projector 1000 of the first embodiment, the first solid-state light source device 20 converts two kinds of excitation light of main excitation light and auxiliary excitation light to light including a red light component and a green light component, and emits converted light. Therefore, the projection image can be further brightened.
The projector 1000 of the first embodiment includes the auxiliary excitation light reflection optical element (dichroic mirror 60) disposed in the region including the intersection between the optical axis of the first collimation optical system 30 and the optical axis of the third collimation optical system 50. Therefore, auxiliary excitation light is input to the fluorescent layer 26 in the direction different from the direction in which main excitation light is input.
According to the projector 1000 of the first embodiment, auxiliary excitation light which is converted to parallel light by the third collimation optical system 50 is reflected as parallel light by the auxiliary excitation light reflection optical element (dichroic mirror 60), is focused by the first collimation optical system 30, and is efficiently input to the light-emission region of the fluorescent layer 26. Therefore, it is possible to suppress the spread of the light-emission region due to the third solid-state light source device 40 being further provided.
According to the projector 1000 of the first embodiment, main excitation light and auxiliary excitation light are blue light components, the first color light component is a red light component, the second color light component is a green light component, and the third color light component is a blue light component. Therefore, light including a red light component and a green light component can be emitted from the first solid-state light source device 20 by using the first solid-state light source 24 and the third solid-state light source 44 emitting blue light components.
According to the projector 1000 of the first embodiment, a green light component is generated by using the first solid-state light source 24 and the third solid-state light source 44 (emitting blue light components together) which have high light-emission efficiency compared to a solid-state light source which is used in a solid-state light source device emitting a green light component. Therefore, light-emission efficiency can be increased compared to a case where a solid-state light source device emitting a green light component is used.
According to the projector 1000 of the first embodiment, the first solid-state light source 24, the second solid-state light source 124, and the third solid-state light source 44 have the same temperature characteristic. Therefore, with regard to all of the color light components, changes in the light amount with change in temperature are made the same, such that the color balance of the projection image can be further stabilized.
According to the projector 1000 of the first embodiment, the fluorescent layer 26 is formed of a layer containing (Y,Gd)3(Al,Ga)5O12:Ce which is a YAG-based fluorescent material. Therefore, the projection image can be further brightened, and a high-reliable projector can be obtained.
According to the projector 1000 of the first embodiment, the dichroic mirror 320 has a function to remove the yellow light component from light from the first solid-state light source device 20. Therefore, the yellow light component can be removed from light from the first solid-state light source device 20. As a result, color reproducibility can be prevented from being deteriorated due to the yellow light component.
According to the projector 1000 of the first embodiment, the dichroic mirror 60 has the function to remove main excitation light (blue light component) from light from the first solid-state light source device 20. Therefore, main excitation light (blue light component) can be removed from light from the first solid-state light source device 20. As a result, it is possible to suppress degradation in color reproducibility or deterioration of the light modulation device.
Second Embodiment
FIG. 4 is a plan view showing optical systems of a projector 1002 according to a second embodiment.
The projector 1002 of the second embodiment basically has the same configuration as the projector 1000 of the first embodiment, but a first illumination device has the configuration different from that in the projector 1000 of the first embodiment.
That is, in the projector 1002 of the second embodiment, as shown in FIG. 4, a first illumination device 12 further includes a reflection-type polarizing plate 80 which is located at the back of the collimation optical system 30 to directly transmit one polarized component (for example, s polarized component) from among polarized components included in light emitted from the first solid-state light source device 20 and to reflect another polarized component (for example, p polarized component) toward the fluorescent layer 26. The reflection-type polarizing plate 80 is a wire grid polarizing plate which has fine metal wires disposed in a lattice shape at specific pitches. As the reflection-type polarizing plate, a polarization beam splitter (PBS) having a dielectric multilayer film on a substrate may be used, instead of the wire grid polarizing plate. In FIG. 4, a solid-line arrow (see reference numeral R(p),G(p),Y(p)) extending from the reflection-type polarizing plate 80 denotes another polarized component which is reflected by the reflection-type polarizing plate 80.
As described above, in the projector 1002 of the second embodiment, the first illumination device has the configuration different from that in the projector 1000 of the first embodiment; however, the two color light components (red light component and green light component) emitted from the first solid-state light source device 20 and one color light component (blue light component) emitted from the second solid-state light source device 120 are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 400R, 400G, and 400B, and the two color light components (red light component and green light component) from among the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 400R, 400G, and 400B are generated by using the common solid-state light source (first solid-state light source 24 and third solid-state light source 44). Therefore, similarly to the projector 1000 of the first embodiment, the projection image can be brightened compared to a projector which includes a single solid-state light source device, and the color balance of the projection image can be stabilized compared to a projector which includes separate solid-state light source devices for respective color light components.
According to the projector 1002 of the second embodiment, the reflection-type polarizing plate 80 is further provided. Thus, another polarized component is returned again to the fluorescent layer 26 and reflected by the surface of the fluorescent layer 26, and part of another polarized component is converted to one polarized component and reused, such that light use efficiency can be improved, and consequently the projection image can be further brightened.
According to the projector 1002 of the second embodiment, the reflection-type polarizing plate 80 is located at the back of the first collimation optical system 30. Thus, another polarized component which is converted to parallel light by the first collimation optical system 30 is reflected as parallel light by the reflection-type polarizing plate 80, is focused by the first collimation optical system 30, and is efficiently input to the light-emission region of the fluorescent layer 26. Therefore, it is possible to suppress the spread of the light-emission region due to the reflection-type polarizing plate 80 being provided.
The projector 1002 of the second embodiment has the same configuration as the projector 1000 of the first embodiment, excluding the configuration of the first illumination device. Therefore, the projector 1002 of the second embodiment also has the relevant effects from among the effects of the projector 1000 of the first embodiment.
Third Embodiment
FIG. 5 is a plan view showing optical systems of a projector 1004 according to a third embodiment.
The projector 1004 of the third embodiment basically has the same configuration as the projector 1000 of the first embodiment, but a light modulation device and a color separating and guiding optical system have the configuration different from those in the projector 1000 of the first embodiment.
That is, in the projector 1004 of the third embodiment, as shown in FIG. 5, a light modulation device has reflection-type liquid crystal light modulation devices 402R, 402G, and 402B. A color separating and guiding optical system is a color separating and guiding optical system 304. The color separating and guiding optical system 304 has a dichroic mirror 310 which reflects a green light component and transmits other color light components, and reflection-type polarizing plates 322, 332, and 342 which directly transmit one polarized component (for example, s polarized component) and reflect another polarized component (p polarized component). The reflection-type polarizing plate 322 also functions as a dichroic mirror which reflects a yellow light component and transmits a red light component. The reflection-type polarizing plate 322 is, for example, an optical element which has fine metal wires serving as a wire grid polarizing plate disposed on one surface of the substrate in a lattice shape at specific pitches and has a wavelength selective transmission film serving as a dichroic mirror on the other surface of the substrate. That is, the projector 1004 has a function to remove a yellow light component by the reflection-type polarizing plate 322.
The liquid crystal light modulation devices 402R, 402G, and 402B carry out light modulation of the respective input color light components, together with the reflection-type polarizing plates 322, 332, and 342 in the color separating and guiding optical system 304. The color separating and guiding optical system 304 has a function to separate light from the first illumination device 10 into a red light component and a green light component, to guide the respective color light components, the red light component and the green light component, to the liquid crystal light modulation devices 402R and 402G to be illuminated, and to guide the light components reflected by the liquid crystal light modulation devices 402R and 402G to the cross dichroic prism 500 as modulated light components, and a function to guide the blue light component from the second illumination device 110 to the liquid crystal light modulation device 402B to be illuminated and to guide the light component reflected by the liquid crystal light modulation device to the cross dichroic prism 500 as modulated light component.
As described above, in the projector 1004 of the third embodiment, the light modulation device and the color separating and guiding optical system have the configuration different from those in the projector 1000 of the first embodiment; however, the two color light components (red light component and green light component) emitted from the first solid-state light source device 20 and one color light component (blue light component) emitted from the second solid-state light source device 120 are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 402R, 402G, and 402B, and the two color light components (red light component and green light component) from among the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 402R, 402G, and 402B are generated by using the common solid-state light source (first solid-state light source 24 and third solid-state light source 44). Therefore, similarly to the projector 1000 of the first embodiment, the projection image can be brightened compared to a projector which uses a single solid-state light source device, and the color balance of the projection image can be stabilized compared to a projector which includes separate solid-state light source devices for respective color light components.
The projector 1004 of the third embodiment has the same configuration as the projector 1000 of the first embodiment, excluding the configuration of the light modulation device and the color separating and guiding optical system. Therefore, the projector 1004 of the third embodiment also has the relevant effects from among the effects of the projector 1000 of the first embodiment.
Fourth Embodiment
FIG. 6 is a plan view showing optical systems of a projector 1006 according to a fourth embodiment.
The projector 1006 of the fourth embodiment basically has the same configuration as the projector 1000 of the first embodiment, but a first illumination device and a second illumination device have the configuration different from those in the projector 1000 of the first embodiment.
That is, in the projector 1006 of the fourth embodiment, as shown in FIG. 6, a first illumination device 14 includes a lens integrator optical system 90, instead of the rod integrator optical system 70, and a second illumination device 112 includes a lens integrator optical system 190, instead of the rod integrator optical system 170. The lens integrator optical system 90 includes a first lens array 92, a second lens array 94, and a superimposing lens 96. The lens integrator optical system 190 includes a first lens array 192, a second lens array 194, and a superimposing lens 196.
As described above, in the projector 1006 of the fourth embodiment, the first illumination device and the second illumination device have the configuration different from those in the projector 1000 of the first embodiment; however, the two color light components (red light component and green light component) emitted from the first solid-state light source device 20 and one color light component (blue light component) emitted from the second solid-state light source device 120 are used as the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 400R, 400G, and 400B, and the two color light components (red light component and green light component) from among the three color light components (red light component, green light component, and blue light component) which are modulated by the liquid crystal light modulation devices 400R, 400G, and 400B are generated by using the common solid-state light source (first solid-state light source 24 and third solid-state light source 44). Therefore, similarly to the projector 1000 of the first embodiment, the projection image can be brightened compared to a projector which includes a single solid-state light source device, and the color balance of the projection image can be stabilized compared to a projector which includes separate solid-state light source devices for respective color light components.
The projector 1006 of the fourth embodiment has the same configuration of the projector 1000 of the first embodiment, excluding the configuration of the first illumination device and the second illumination device. Therefore, the projector 1006 of the fourth embodiment also has the same effects as the effects of the projector 1000 of the first embodiment.
Although the invention has been described on the basis of the foregoing embodiments, the invention is not limited to the foregoing embodiments. The invention may be carried out in various forms without departing from the scope and spirit of the invention. For example, the following modification may be made.
(1) Although in the foregoing embodiments, the fluorescent layer 26 is formed of a layer containing (Y,Gd)3(Al,Ga)5O12:Ce, the invention is not limited thereto. For example, the fluorescent layer may be formed of a layer containing a YAG-based fluorescent material other than (Y,Gd)3(Al,Ga)5O12:Ce, a layer containing a silicate-based fluorescent material, or a layer containing a TAG-based fluorescent material. Further, the fluorescent layer may be formed of a layer containing a mixture of a fluorescent material which converts excitation light to a red light component and a fluorescent material which converts excitation light to a green light component.
(2) Although in the foregoing embodiments, a liquid crystal light modulation device is used as a light modulation device for a projector, the invention is not limited thereto. As a light modulation device, in general, any device may be used insofar as the device modulates incident light in accordance with image information. For example, a micromirror-type light modulation device or the like may be used. As a micromirror-type light modulation device, for example, DMD (Digital Micromirror Device) (Trademark of TI Inc.) may be used.
(3) Although in the foregoing embodiments, the first solid-state light source device 20, the second solid-state light source device 120, and the third solid-state light source device 40 are light-emitting diodes, the invention is not limited thereto. The first solid-state light source device, the second solid-state light source device, and the third solid-state light source device may be, for example, semiconductor laser or organic light-emitting diodes.
(4) Although in the foregoing embodiments, main excitation light and auxiliary excitation light are both blue light components, the invention is not limited thereto. For example, main excitation light and auxiliary excitation light may be both ultraviolet light. Further, main excitation light may be one of a blue light component and ultraviolet light, and auxiliary excitation light may be the other one of the blue light component and ultraviolet light. With this configuration, light including a red light component and a green light component can be emitted from the first illumination device, and light-emission efficiency can be increased compared to a case where a solid-state light source device emitting a green light component is used. Further, the selection width of a fluorescent material in the fluorescent layer is widened.
(5) In the foregoing embodiments, when main excitation light and auxiliary excitation light are both ultraviolet light, the first color light component may be a green light component, the second color light component may be a blue light component, and the third color light component may be a red light component. Further, the first color light component may be a red light component, the second color light component may be a blue light component, and the third color light component may be a green light component.
(6) Although in the first, second, and fourth embodiments, the projector has a function to remove a yellow light component from the first solid-state light source device 20, the invention is not limited thereto. For example, the projector may not have a function to remove a yellow light component. In this case, the yellow light component included in light emitted from the first illumination device can be positively used, such that a brighter projection image can be projected. Further, when the yellow light component is not removed, the yellow light component is modulated by using a light modulation device different from that for a red light component or a green light component, such that a projection image having more excellent color reproducibility can be projected, in addition to the above-described effects.
(7) In the foregoing embodiments, the projector may further include a polarization conversion device. The polarization conversion device is a polarization conversion element which converts light including one polarized component and another polarized component to substantially one linearly polarized light with polarization direction arranged.
(8) Although in the foregoing embodiments, each collimation optical system includes two lenses of the convex meniscus lens and the convex lens, the invention is not limited thereto. For example, the collimation optical system may include only one lens or may include three or more lenses.
(9) The shape of each of the lenses which are used in the optical path of the projector in each of the foregoing embodiments is not limited to those described in the foregoing embodiments. If necessary, lenses having various shapes may be used.
(10) Although in the foregoing embodiments, an example where a projector uses three liquid crystal light modulation devices has been described, the invention is not limited to this example. The invention may be applied to a projector which uses one, two, or four or more liquid crystal light modulation devices.
(11) The invention may be applied to a front projection-type projector which projects a projection image from an observation side, or a rear projection-type projector which projects a projection image from an opposite side to the observation side.
The entire disclosure of Japanese Patent Application No: 2009-190761, filed Aug. 20, 2009 is expressly incorporated by reference herein.

## Claims

1. A projector comprising:
a first solid-state light source device which includes a first solid-state light source emitting main excitation light, and a fluorescent layer converting main excitation light to light including a first color light component and a second color light component different from the first color light component, and emitting converted light;
a second solid-state light source device which includes a second solid-state light source emitting a third color light component different from the first color light component and the second color light component;
a light modulation device modulating the first color light component, the second color light component, and the third color light component in accordance with image information;
a projection optical system projecting the modulated light components from the light modulation device as a projection image; and
a third solid-state light source device which includes a third solid-state light source emitting auxiliary excitation light,
wherein the fluorescent layer is configured such that auxiliary excitation light is input thereto in a direction different from a direction in which main excitation light is input, and the fluorescent layer is configured to convert auxiliary excitation light to light including the first color light component and the second color light component, and to emit converted light.

2. The projector according to claim 1, further comprising:
a first collimation optical system parallelizing light emitted from the first solid-state light source device;
a second collimation optical system parallelizing light emitted from the second solid-state light source device;
a third collimation optical system having an optical axis orthogonal to an optical axis of the first collimation optical system and parallelizing auxiliary excitation light emitted from the third solid-state light source device; and
an auxiliary excitation light reflection optical element disposed in a region including an intersection between the optical axis of the first collimation optical system and the optical axis of the third collimation optical system,
wherein the auxiliary excitation light reflection optical element directly transmits light which is converted by the fluorescent layer and emitted from the fluorescent layer, and reflects auxiliary excitation light from the third solid-state light source device to input auxiliary excitation light to the fluorescent layer in an opposite direction to a direction in which main excitation light from the first solid-state light source is input.

3. The projector according to claim 2, further comprising:
a reflection-type polarizing plate located at the back of the first collimation optical system to directly transmit one polarized component from among polarized components included in light emitted from the first solid-state light source device and to reflect another polarized component toward the fluorescent layer.

4. The projector according to claim 2,
wherein main excitation light and auxiliary excitation light are blue light components,
the first color light component is a red light component,
the second color light component is a green light component,
the third color light component is a blue light component, and
the auxiliary excitation light reflection optical element is a mirror which reflects the blue color light component and transmits the red color light component, the green color light component and a yellow color light component, the yellow color light component included in light from the first solid-state light source device, and the mirror has a wavelength selective transmission film.

5. The projector according to claim 2,
wherein the auxiliary excitation light reflection optical element is a dichroic mirror to remove main excitation light from light from the first solid-state light source device.

6. The projector according to claim 1,
wherein main excitation light and auxiliary excitation light are blue light components,
the first color light component is a red light component,
the second color light component is a green light component, and
the third color light component is a blue light component.

7. The projector according to claim 6,
wherein the first solid-state light source, the second solid-state light source, and the third solid-state light source have the same temperature characteristic.

8. The projector according to claim 6,
wherein the fluorescent layer is formed of a layer containing a YAG-based fluorescent material, a silicate-based fluorescent material, or a TAG-based fluorescent material.

9. The projector according to claim 1,
wherein main excitation light and auxiliary excitation light are ultraviolet light,
the first color light component is a red light component,
the second color light component is a green light component, and
the third color light component is a blue light component.

10. The projector according to claim 1,
wherein main excitation light is one of a blue light component and ultraviolet light,
auxiliary excitation light is the other one of the blue light component and ultraviolet light,
the first color light component is a red light component,
the second color light component is a green light component, and
the third color light component is a blue light component.

11. The projector according to claim 1,
wherein a function is provided to remove a yellow light component from light from the first solid-state light source device.

12. The projector according to claim 1,
wherein a function is provided to remove main excitation light from light from the first solid-state light source device.