Patent Publication Number: US-2007103645-A1

Title: Projector

Description:
TECHNICAL FIELD  
      The present invention relates to a projector including a light source device using microwaves.  
     BACKGROUND ART  
      Projectors for projecting images on the basis of image signals have been used for presentation in the meeting or home theaters. As a light source for the projector, a high-brightness light source is used to obtain a bright projected image, or a light source having an emission spectrum including red (R), green (G), and blue (B) light components, which are three primary colors of light, that are in balance is used to obtain a clear full color image.  
      Discharge lamps having high brightness, such as a halogen lamp, a metal halide lamp, and a high-pressure mercury lamp, have come into widespread use in the projectors on the market.  
      The discharge lamp needs discharge electrodes for making a discharge medium, such as gas filled in the lamp, emit light, but the discharge electrodes are abraded by discharge. The abrasion of the discharge electrodes causes the distance between the electrodes to increase, which results in a variation in the emission spectrum. When the electrodes are abraded, there has a problem in that discharge may not occur. The internal temperature and pressure of the discharge lamp need to increase and the discharge medium, such as gas, needs to be sufficiently excited until the quantity of light emitted from the discharge lamp reaches a predetermined value. In this case, it takes a predetermined amount of time to obtain the necessary amount of light.  
      A solid-state light source, such as LEDs (light emitting diodes) for emitting R, G, and B light components, has been proposed as a light source for a projector capable of effectively obtaining R, G, and B light components, but has not been developed yet. Further, the solid-state light source has a problem in that it is difficult to obtain necessary brightness.  
      In order to solve these problems, JP-A-2001-155882 discloses a projector using an electrodeless lamp as a light source device. In the light source device of the projector, a magnetron, which is a kind of vacuum tube having electrodes and a filament, generates microwaves, and the microwaves are radiated onto an electrodeless lamp having rare gas or rare-earth metal halogen compound, serving as a discharge medium, filled therein to emit light by plasma discharge. This structure makes it possible to provide a projector having an electrodeless lamp, which is a point light source having high brightness and a long life span, as a light source. The radiated microwave is not described in detail in JP-A-2001-155882, but it is guessed that the radiated microwave is a single-phase microwave from the structure in which the magnetron and the antenna form a pair.  
      It is necessary to preheat the magnetron for a predetermined period of time in order to start the magnetron to obtain a predetermined microwave. For example, JP-A-9-82112 discloses a power supply for an electrodeless lamp. In JP-A-9-82112, when the preheating temperature is high, the frequency characteristics of microwaves generated by the magnetron deteriorate. Therefore, temperature control is performed to reduce the preheating temperature when the electrode lamp is turned on.  
       FIG. 14  is a diagram illustrating the frequency characteristics of the microwaves generated by the magnetron. The frequencies of the microwaves are distributed with the center at a frequency of about 2.45 GHz, and many noise components are included in a frequency band of about 2.25 to 2.65 GHz.  
      However, in the light source devices disclosed in JP-A-2001-155882 and JP-A-9-82112, the magnetron requiring preheating is used for a source for generating microwaves. Therefore, it takes a predetermined amount of time for the electrodeless lamp to start emitting light, which makes it difficult to rapidly turn on the electrodeless lamp.  
      As shown in  FIG. 14 , since the microwaves generated by the magnetron include many noise components, many noise components in an unnecessary wavelength range are included in the spectrum of light emitted from the electrodeless lamp. Further, since a single-phase microwave is used, the efficiency of energy conversion from microwave power applied into light is not very high.  
      Therefore, in order to obtain a predetermined quantity of light including necessary spectral components, it is necessary to set high microwave power, considering the amount of energy reduced due to the noise components.  
      As described above, the light source devices of the projectors according to the related art have problems in that it is difficult to rapidly turn on the light source device and the light source device does not have high energy efficiency.  
      In order to solve the above-mentioned problems, it is an object of the invention to provide a projector having a light source device that is rapidly turned on and has high energy efficiency. Disclosure of the Invention  
      According to an aspect of the invention, there is provided a projector for projecting an image on the basis of image information. The projector includes a light source device that is used as a light source for the projected image. The light source device includes: a plurality of solid-state high-frequency oscillators that generate microwaves; a phase control unit that adjusts each of the phases of the microwaves output from the solid-state high-frequency oscillators; amplifying units that amplify the microwaves whose phases have been adjusted by the phase control unit; and a light emitting body that has a material emitting light by the microwaves filled therein. In the projector, two or more microwaves having different phases that are output from the amplifying units are radiated onto the light emitting body.  
      In the projector according to the above-mentioned aspect, preferably, light emitting areas onto which a plurality of microwaves having different phases are radiated are provided in the light emitting body so as to correspond to the solid-state high-frequency oscillators, and the inner spaces of the light emitting body including the plurality of light emitting areas communicate with each other.  
      In the projector according to the above-mentioned aspect, preferably, the light emitting body includes a light radiating area that emits light to be used to form the projected image. Preferably, the light emitting areas are radially branched from the light radiating area, and optical waveguides that guide light emitted from the light emitting areas to the light radiating area are provided at optical ends of the light emitting areas.  
      In the projector according to the above-mentioned aspect, preferably, n (n is an integer equal to or greater than 2) pairs of solid-state high-frequency oscillators and amplifying units are provided, and the phase control unit adjusts the phases of the microwaves output from the solid-state high-frequency oscillators such that the microwaves have a phase difference of (2π)/n.  
      In the projector according to the above-mentioned aspect, preferably, the integer n is 3.  
      According to another aspect of the invention, there is provided a projector for projecting an image on the basis of image information. The projector includes a light source device that is used as a light source for the projected image. The light source devices includes: a plurality of solid-state high-frequency oscillators that generate microwaves; amplifying units that are provided so as to correspond to the solid-state high-frequency oscillators and amplify the microwaves generated by the solid-state high-frequency oscillators; and a plurality of color light emitting bodies that have materials emitting light by the microwaves filled therein. In the projector, the plurality of color light emitting bodies are provided so as to correspond to the amplifying units, and the light emitting materials having different emission spectra are filled in the color light emitting bodies.  
      In the projector according to the above-mentioned aspect, preferably, the light source device further includes a light radiating portion that emits light to be used to form the projected image. Preferably, the color light emitting bodies are radially branched from the light radiating portion and are integrally formed with the light radiating portion, and optical waveguides that guide light emitted from the color light emitting bodies to the light radiating portion are provided at optical ends of the color light emitting bodies.  
      In the projector according to the above-mentioned aspect, preferably, the light source device further includes a frequency control unit that adjusts the frequencies of the microwaves generated by the solid-state high-frequency oscillators.  
      In the projector according to the above-mentioned aspect, preferably, the light source device further includes a power control unit that adjusts an amplification factor of each of the amplifying units.  
      In the projector according to the above-mentioned aspect, preferably, the light source device further includes: antennas that are provided in the respective amplifying units and radiate the microwaves amplified by the amplifying units; cavities that are provided for the respective antennas, accommodate at least some of the light emitting body or the color light emitting bodies and the antennas therein and reflect the microwaves; and isolators that are provided between the amplifying units and the antennas and prevent some of the microwaves that have been radiated from the antennas and reflected from the cavities from returning to the antennas.  
      In the projector according to the above-mentioned aspect, preferably, the plurality of solid-state high-frequency oscillators are surface acoustic wave oscillators having surface acoustic wave resonators. Preferably, each of the surface acoustic wave resonators includes a first layer that is formed of diamond or diamond-like carbon, a piezoelectric layer that is formed on the first layer, and a comb-shaped electrode that is formed on the piezoelectric layer.  
      According to the above-mentioned aspect, preferably, the projector further includes light modulating devices. Preferably, the image information is image signals for defining an image. Preferably, each of the light modulating devices modulates light emitted from the light source device on the basis of the image signals to generate modulated light for forming an image, and is any one of a transmissive liquid crystal panel, a reflective liquid crystal panel, and a tilt mirror device.  
      In the projector according to the above-mentioned aspect, preferably, the microwaves are signals in a frequency band of 300 MHz to 30 GHz. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a diagram schematically illustrating the structure of a projector according to a first embodiment of the invention.  
       FIG. 2  is a diagram schematically illustrating the structure of a microwave oscillator.  
       FIGS. 3A  is a plan view schematically illustrating a diamond SAW resonator, and  FIG. 3B  is a cross-sectional view schematically illustrating the diamond SAW resonator.  
       FIG. 4  is a diagram illustrating an example of an output frequency characteristic of the diamond SAW resonator.  
       FIG. 5  is a perspective view schematically illustrating the structure of a peripheral portion of a first electrodeless lamp.  
       FIG. 6  is a cross-sectional view of main parts of the peripheral portion of the electrodeless lamp.  
       FIG. 7  is a graph illustrating the phases of microwaves oscillated by microwave oscillators.  
       FIG. 8  is a diagram schematically illustrating the structure of an optical unit.  
       FIG. 9  is a diagram schematically illustrating the structure of a projector according to a second embodiment of the invention.  
       FIG. 10  is a perspective view schematically illustrating the structure of a peripheral portion of a second electrodeless lamp.  
       FIG. 11A  is a cross-sectional view of main parts of the peripheral portion of an electrodeless lamp according to a first aspect, and  FIG. 11B  is a cross-sectional view of main parts of the peripheral portion of an electrodeless lamp according to a second aspect.  
       FIG. 12  is a diagram schematically illustrating the structure of a projector according to a third embodiment of the invention.  
       FIG. 13  is a diagram schematically illustrating the structure of a projector according to a fourth embodiment of the invention.  
       FIG. 14  is a diagram illustrating a frequency characteristic of microwaves generated by a magnetron. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      Hereinafter, exemplary embodiments of the invention will be described in detail below with reference to the accompanying drawings.  
      (First Embodiment)  
      &lt;Outline of First Projector&gt; 
       FIG. 1  is a diagram schematically illustrating the structure of a projector according to a first embodiment of the invention.  
      A projector  100  is a so-called projector of a three liquid crystal panel type in which light emitted from a light source device  30  is separated into three color light components, that is, red, green, and blue light components, the separated light components are modulated by red, green, and blue liquid crystal light valves  77 R,  77 G, and  77 B, serving as light modulating devices, according to image signals, the modulated light components are combined into a full color optical image, and the full color optical image is enlarged and projected onto a screen SC by a projection lens  52 . The liquid crystal light valves  77 R,  77 G, and  77 B are provided for the red, green, and blue light components, respectively, and are included in the structure of an optical unit  50 .  
      In the light source device  30 , an electrodeless lamp  1 , serving as a light emitting body (hereinafter, referred to as a light emitter), is used as a light source. A light emitting material is filled in the electrodeless lamp  1 , and microwaves radiated from a plurality of antenna portions (hereinafter, referred to as antennas)  2   a  to  2   c  excite the light emitting material, thereby emitting light by means of plasma emission. The microwaves radiated from the antennas  2   a  to  2   c . are generated by corresponding microwave oscillators  10  serving as solid-state high-frequency oscillators. The high frequency means frequency in a frequency band, such as a UHF band (300 MHz to 3 GHz) or an SHF band (3 GHz to 30 GHz). The term ‘solid-state high-frequency oscillator’ is opposite to a gas oscillator, such as a vacuum tube using, for example, a magnetron, and means an oscillator using solid such as diamond.  
      &lt;Outline of Microwave Oscillator&gt; 
       FIG. 2  is a block diagram schematically illustrating the structure of the microwave oscillator.  FIG. 3A  is a plan view schematically illustrating a diamond SAW resonator, and  FIG. 3B  is a cross-sectional view schematically illustrating the diamond SAW resonator.  FIG. 4  is a diagram illustrating an example of an output frequency characteristic of the diamond SAW resonator.  
      Next, the microwave oscillator  10  of the light source device  30 , which is one of characteristics of the invention, will be described in detail with reference to  FIG. 2  and  FIGS. 3A and 3B .  
      The microwave oscillator  10  is a surface acoustic wave (hereinafter, referred to as SAW) oscillator including a surface acoustic wave resonator, and uses a SAW resonator in which a diamond monocrystalline layer is used for an elastic body transmitting surface acoustic waves.  
      The microwave oscillator  10  includes a SAW resonator  7 , an amplifier  8 , and a distributor  9  for equally distributing microwave power.  
      The SAW resonator  7  is a diamond SAW resonator, and the detailed structure thereof is shown in  FIGS. 3A and 3B .  
      As shown in  FIG. 3B , the SAW resonator  7  includes a silicon substrate  72 , serving as a base, and a diamond monocrystalline layer  73  formed on the silicon substrate  72 .  
      A piezoelectric layer  74 , such as a zinc oxide (ZnO) film, is formed on the diamond monocrystalline layer  73 .  
      Further, an electrode  75  including a comb-shaped electrode (IDT (inter digital transducer) electrode) for exciting surface acoustic waves is provided on the piezoelectric layer  74 .  
      A silicon oxide layer  76  is formed on the electrode  75 . Since the temperature dependence of the operational frequency of the silicon oxide layer  76  is opposite to that of the diamond monocrystalline layer  73 , the piezoelectric layer  74 , and the electrode  75 , the silicon oxide layer  76  provided on the uppermost layer makes it possible to improve the temperature characteristic.  
      Further, it is preferable that the diamond monocrystalline layer  73  be formed by a gas phase synthesizing method. Alternatively, a hard carbon layer having an elastic modulus close to polycrystalline diamond may be used. In addition, the piezoelectric layer  74  may be formed of AIN or Pb(Zr, Ti)O2 other than ZnO by a sputtering method or a gas phase synthesizing method.  
      As shown in  FIG. 3A , the electrode  75  includes IDT electrodes  75   a  and  75   b , which are a pair of comb-shaped electrodes arranged so as to engage with each other, and a reflector electrode  75   c  that is provided at both sides of the IDT electrodes and reflects surface acoustic waves.  
      When an electric signal is input to the IDT electrode  75   a , the SAW resonator  7  excites a surface acoustic wave on the base including the diamond monocrystalline layer  73  and holds the surface acoustic waves between both sides of the reflector  75   c . The held surface acoustic waves are multiply reflected between both sides of the reflector  75   c , which causes a stationary wave to be generated between both sides of the reflector  75   c.    
      When the surface acoustic wave reaches the IDT electrode  75   b , the SAW resonator  7  outputs an electric signal having a frequency (microwave) corresponding to the frequency of the surface acoustic wave.  
      Referring to  FIG. 2  again, the amplifier  8  is provided in the next stage of the SAW resonator  7  and amplifies a microwave oscillated by the SAW resonator  7  into a microwave having predetermined power.  
      The distributor  9  equally distributes the microwave power output from the amplifier  8  to the outside and the SAW resonator  7 .  
      The SAW resonator  7 , the amplifier  8 , and the distributor  9  are connected to one another such that the impedances thereof are matched to 50 ohm, and form the microwave oscillator  10 , which is a feedback oscillating circuit.  
      The SAW resonator  7  uses diamond as an elastic body, and thus generates a surface acoustic wave having a high transmission speed higher than 10000 m/s.  
      This characteristic enables the microwave oscillator  10  to directly oscillate microwaves without using a frequency multiplying circuit provided with, for example, a PLL (phase locked loop) circuit. The IDT electrodes  75   a  and  75   b  of the SAW resonator  7  can be configured such that the widths thereof are larger than that of another elastic body, such as quartz or ceramic. Therefore, the IDT electrodes  75   a  and  75   b  of the SAW resonator  7  can have a good power-resistant characteristic and a small variation in frequency due to a change in temperature.  
       FIG. 4  is a diagram illustrating an example of an output frequency characteristic of the microwave oscillator.  
      As shown in  FIG. 4 , in the output frequency characteristic of the microwave oscillator  10 , a power peak is obtained around a frequency of 2.45 GHz. Even when output microwave power is changed, little variation occurs in the frequency.  
      Further, the microwave oscillator  10  has the following characteristics. The microwave oscillator  10  does not need preheating, and directly oscillates a predetermined frequency in real time when power is supplied. The frequency characteristic of the microwave oscillator  10  does not vary even when microwave power increases, and little phase noise is generated.  
      &lt;Schematic Structure of First Projector&gt; 
      The schematic structure of the projector  100  will be described with reference to  FIG. 1 .  
      The projector  100  includes the light source device  30 , the optical unit  50 , the projection lens  52 , a control unit  53 , an image signal processing unit  54 , a liquid crystal panel driving unit  55 , a storage unit  56 , an operating unit  57 , a remote controller  58 , an operational signal receiving unit  59 , a fan driving unit  60 , and a power supply  62 .  
      The light source device  30  includes a plurality of cavities  3 , a reflector  4 , a plurality of amplifying units  11 , a power control unit  12 , a plurality of isolators  13 , and a phase control unit  14 , in addition to the electrodeless lamp  1 , the antennas  2   a  to  2   c , and the plurality of microwave oscillators  10 . The microwave oscillators  10 , the amplifying units  11 , the power control unit  12 , the isolators  13 , and the phase control unit  14  form a microwave circuit unit  18 .  
      Three sets of the microwave oscillators  10 , the amplifying units  11 , the isolators  13 , and the cavities  3  are provided to correspond to the three antennas  2   a  to  2   c , respectively.  
      The cavities  3  are hollow members formed of a material reflecting microwaves, such as aluminum. The cavities  3  concentrate microwaves radiated from the antennas  2   a  to  2   c  on light emitting areas of the electrodeless lamp  1  and prevent the microwaves from leaking to the outside.  
      The reflector  4  reflects light emitted from the light emitting areas of the electrodeless lamp  1  to converge on a point and guides the light to the optical unit  50 .  
      Each amplifying unit  11  is provided in the latter stage of the microwave oscillator  10  and amplifies microwave power output from the corresponding microwave oscillator  10 .  
      The power control unit  12  is an amplification factor adjusting circuit for adjusting the amplification factors of the three amplifying units  11  in response to a control signal output from the control unit  53 .  
      The isolators  13  are isolators for separating the microwaves reflected from the antennas  2   a  to  2   c  and consuming the separated microwaves as heat by using resistors provided therein. In this way, the isolators  13  prevent the reflected microwaves from returning to the corresponding amplifying units  11 .  
      The phase control unit  14  is a phase adjusting circuit for adjusting the phases of microwaves oscillated by the microwave oscillators  10 .  
      The optical unit  50  includes an integrator illumination optical system that converts light emitted from the electrodeless lamp  1  into light having a stable brightness distribution, a separating optical system that separates the light having a stable brightness distribution into three primary color light components, that is, a red light component, a green light component, and a blue light component, and supplies the separated red, green, and blue light components to red, green, and blue liquid crystal light valves  77 R,  77 G, and  77 B, respectively, and a combining optical system that combines light components modulated by the red, green, and blue liquid crystal light valves in response to image signals to generate full color modulated light. The optical unit  50  will be described in detail later.  
      The projection lens  52  includes a zoom lens. The projection lens  52  enlarges the full color modulated light emitted from the optical unit  50  and projects the enlarged full color image onto the screen SC.  
      The control unit  53  is a central processing unit (CPU) and controls the projector  100  by means of communication with components including the light source device  30  through a bus line Bus.  
      The image signal processing unit  54  is provided with, for example, an image converter for converting analog image signals input from an external image signal supplying apparatus  350 , such as a personal computer, into digital signals, a scaler (not shown), and a frame memory (not shown).  
      The image signal processing unit  54  converts input analog image signals, such as R, G, and B signals or components signals, into digital signals by using the image converter and performs image processing, such as scaling, on the digital image signals.  
      The image signal processing unit  54  writes to the frame memory an image represented by R, G, and B image signals at resolution of the image signals, converts the image into an image having a resolution that can be displayed by the liquid crystal light valves  77 R,  77 G, and  77 B, and reads out the converted image to generate image signals suitable for the corresponding liquid crystal light valves. A trapezoid correcting process for shaping an effective image projected onto the screen SC into a rectangle is performed together with the scaling process.  
      The liquid crystal panel driving unit  55  is a liquid crystal panel driver that supplies image signals subjected to image processing and a driving voltage to the liquid crystal light valves  77 R,  77 G, and  77 B and outputs images to the corresponding liquid crystal light valves.  
      The storage unit  56  is composed of a non-volatile memory, such as a mask ROM, a flash memory, or a ferroelectric memory (FeRAM). The storage unit  56  stores various programs for controlling the operation of the projector, such as a start program that defines the content and procedure for starting the projector  100 , including an operation of turning on the light source device  30 , and additive data.  
      For example, the programs include a phase adjusting program for allowing the phase control unit  14  of the light source device  30  to optimally adjust the phase of microwaves oscillated by the three microwave oscillators  10 .  
      The operating unit  57  is provided on the upper surface of the main body of the projector  100  and includes a plurality of operating buttons (not shown) for operating the projector  100 . The plurality of operating buttons include a ‘power button’ for starting or shutting down the projector  100 , a ‘menu button’ for displaying menu for various operations, and a ‘brightness adjusting button’ for adjusting the brightness of a projected image.  
      The remote controller  58  is a remote controller for operating the projector  100  by remote control, and includes a plurality of operating buttons for operating the projector  100 , similar to the operating unit  57 .  
      When an operator operates the operating unit  57  or the remote controller  58 , the operational signal receiving unit  59  receives operational signals and transmits the operational signals for triggering various operations to the control unit  53 .  
      The fan driving unit  60  is a driving circuit for rotating a fan F 1 , which is an axial flow fan, in response to the control signal output from the control unit  53 . The fan is not limited to the axial flow fan. For example, a Sirocco fan for concentratively supplying air around the liquid crystal light valves  77 R,  77 G, and  77 B or the cavities  3  may be further provided.  
      The power supply  62  is supplied with an AC voltage through an inlet from an external power source  351 , converts the AC voltage into a DC voltage by using an AC/DC converter (not shown) provided therein, rectifies and smoothes the DC voltage, and supplies a stabilized DC voltage to all components of the projector  100 .  
      &lt;Detailed Structure of First Electrodeless Lamp&gt; 
       FIG. 5  is a perspective view schematically illustrating the structure of a peripheral portion of the first electrodeless lamp.  FIG. 6  is a cross-sectional view illustrating the main parts of the peripheral portion of the electrodeless lamp. In  FIG. 5 , the reflector  4  is shown in sectional view for the purpose of convenience of the explanation.  
      Next, the schematic structure of the electrodeless lamp  1 , serving as the first electrodeless lamp, and a peripheral portion thereof will be described with reference to  FIGS. 5 and 6 . Three-phase current microwaves are supplied to the electrodeless lamp  1 , which is a preferable aspect of the invention.  
      The electrodeless lamp  1  is formed in a hollow shape of transmissive inorganic glass having heat resistance, such as quartz glass, and is filled with a light emitting material that is excited by a microwave to emit light by means of plasma emission. In addition, the electrodeless lamp  1  does not have electrodes.  
      The light emitting material filled in the electrodeless lamp  1  may be neon gas, argon gas, krypton gas, xenon gas, or halogen gas. A metallic material, such as mercury or sodium, or a metal compound may be filled into the electrodeless lamp  1  together with the gas. In addition, the light emitting material may be a solid.  
      The electrodeless lamp  1  is divided into three main portions, that is, a plurality of light emitting areas Spo, a plurality of optical waveguides Ref, and a light radiating area Emi.  
      Three light emitting areas Spo corresponding to the antennas  2   a  to  2   c  are provided, and each of the three light emitting areas Spo is arranged in the corresponding cavity  3  so as to face the corresponding antenna. Since the light emitting area Spo is transparent, the microwaves radiated from the antennas  2   a  to  2   c  are absorbed to an internal discharged material. The light emitting areas Spo are radially branched from the light emitting area Emi.  
      The optical waveguide Ref is an optical system for guiding light emitted from the corresponding light emitting area Spo by plasma emission to the light radiating area Emi. A reflective layer formed of, for example, aluminum is provided on the inner surface of the optical waveguide Ref. The reflective layer guides light emitted from the light emitting area Spo to the light radiating area Emi and prevents microwaves or light from leaking from the optical waveguide Ref to the outside.  
      The light radiating area Emi is represented by a hatched portion in  FIG. 5 , and is transparent. Light emitted from the light emitting areas Spo and concentrated by the optical waveguides Ref is emitted to the outside through the light radiating area Emi. Since the light radiating area Emi is disposed at a substantially focal point of the reflector  4 , light emitted from the light radiating area Emi is concentrated without leakage and is then emitted to the optical unit  50 .  
       FIG. 6  is a cross-sectional view taken long the line Q of  FIG. 5 .  
      The light emitting area Spo is provided in the cavity  3  so as to protrude with substantially the same length as the antenna  2   b . The internal reflective layer is not provided in the protruding portion.  
      The reflective layer is provided on the entire inner surface of the optical waveguide Ref, and the reflective layer is also formed up to the lower portion of the light radiating area Emi that is represented by arrow. A plurality of reflecting surfaces M 1  to M 3  for reflecting light emitted from the light emitting area Spo by plasma emission and guiding the light to the light radiating area Emi are provided on the inner surface of the optical waveguide Ref. The reflective layer is also formed on the reflecting surfaces M 1  to M 3 .  
      The reflecting surface M 1  reflects light from the light emitting area Spo to the reflecting surface M 2 . The reflecting surface M 2  reflects the light reflected from the reflecting surface M 1  to the light radiating area Emi.  
      The reflecting surface M 3  is a concave mirror having the light radiating area Emi as a focal point, and reflects light traveling all directions in the optical waveguide Ref to the light radiating area Emi.  
      In this way, light generated in the optical waveguide Ref and the light emitting area Spo is concentrated on the light radiating area Emi.  
      In this embodiment, the reflective layer is provided on the inner surface of the optical waveguide Ref, but the invention is not limited thereto. For example, the reflective layer may be provided on the outer surface of the optical waveguide Ref. In this case, it is easy to provide the reflective layer from the viewpoint of manufacture. Since the glass substrate, which is a base, serves as an optical waveguide member, it is easy to concentrate light on the light radiating area Emi.  
      The protruding length of the antenna  2   b  in the cavity  3  is preferably a quarter of the wavelength λ where the radiation efficiency of microwaves is high. Since the wavelength λ is determined by a dielectric constant of a dielectric, it is possible to decrease the length of the antenna  2   b  by filling a high molecular material having a large dielectric constant in the cavity. Alternatively, a helical antenna can be used to decrease the length of the antenna  2   b . This is similarly applied to the antennas  2   a  and  2   c.    
      The inner surface of the cavity  3  formed of a metallic material for reflecting microwaves, such as aluminum, is composed of a mirror surface, and effectively reflects microwaves radiated from the antenna  2   b  to the light emitting area Spo. The shape of the inner surface of the cavity  3  is not limited to a cylindrical shape. For example, the shape of the inner surface of the cavity  3  may be a curved surface having a curvature capable of effectively reflecting microwaves radiated from the antenna  2   b  to the light emitting area Spo.  
      Further, the cavity  3  may be formed of synthetic resin, and a dielectric material for reflecting microwaves may be coated on the inner surface of the cavity  3 .  
      &lt;Lighting Aspect of First Electrodeless Lamp&gt; 
       FIG. 7  is a graph illustrating the phases of microwaves oscillated by the microwave oscillator.  
      The lighting aspect of the electrodeless lamp  1  having the above-mentioned structure will be described with reference to  FIGS. 1 and 5  and  FIGS. 6 and 7 .  
      The optical device  30  according to this embodiment of the invention oscillates microwaves having different phases from the three antennas  2   a  to  2   c  to turn on the electrodeless lamp  1 .  
      More specifically, the control unit  53  controls the phase control unit  14  to output microwaves having the phases shown in  FIG. 7  from the microwave oscillators  10  corresponding to the three antennas  2   a  to  2   c.    
      The microwave oscillator  10  corresponding to the antenna  2   a  oscillates a microwave W 2   a  having a reference phase.  
      The microwave oscillator  10  corresponding to the antenna  2   b  oscillates a microwave W 2   b  whose phase lags the phase of the microwave W 2   a  by (2π)/3.  
      The microwave oscillator  10  corresponding to the antenna  2   c  oscillates a microwave W 2   c  whose phase lags the phase of the microwave W 2   b  by (2π)/3.  
      A phase difference among the microwaves W 2   a  to W 2   c  is (2π)/3, and energy loss is small. In addition, a three-phase current has a larger amount of energy than a single-phase alternating current. The adjustment of the phases of the microwaves W 2   a  to W 2   c  are executed by the phase adjusting program stored in the storage unit  56 , and the phase adjusting program is executed while the electrodeless lamp  1  is in an on state.  
      The number of phases of the microwaves is not limited to three. For example, microwaves having a plurality of phases, for example, four phases or six phases may be used. In this case, when the number of phases is n, a phase difference among the microwaves is (2π)/n.  
      Next, the principle of the lighting of the electrodeless lamp  1  by means of microwaves radiated from, for example, the antenna  2   b  will be described below.  
      In  FIG. 6 , the microwave W 2   b  radiated from the antenna  2   b  is reflected from the inner surface of the cavity  3  to be incident on the light emitting area Spo of the electrodeless lamp  1 .  
      When the microwave is incident on a light emitting material of the light emitting area Spo, the light emitting material is excited to emit light by means of plasma emission. In this case, the light emitting material is evaporated and dissociated into particles in a high-temperature portion onto which the microwave W 2   b  is radiated, and then emits light by means of plasma discharge. Then, the particles move to a low-temperature portion in the electrodeless lamp  1 , and are then condensed to the original light emitting material.  
      In order for the electrodeless lamp  1  to continuously emit light, a structure for preventing microwave power from being concentrated on a point and allowing the convection of the light emitting material is needed such that the cycle of evaporation, dissociation, and condensation of the light emitting material is repeated.  
      In  FIG. 5 , in the electrodeless lamp  1 , the microwaves W 2   a  to W 2   c  having different phases are radiated onto the three branched light emitting areas Spo.  
      Further, in the electrodeless lamp  1 , the cavities and the optical waveguides are formed of hollow members so as to communicate with each other. Therefore, the light emitting material is circulated by convection in the electrodeless lamp  1  with a high degree of freedom.  
      This structure makes it possible for the electrodeless lamp  1  of the light source device  30  to continue to stably emit light.  
      &lt;Schematic Structure of Optical Unit&gt; 
       FIG. 8  is a diagram schematically illustrating the structure of a peripheral portion of the optical unit.  
      A supplementary description of the optical device  30  will be made and the schematic structure of the optical unit  50  will be described below.  
      The optical device  30  further includes a lid-shaped protective glass  33  provided on the emission surface of the reflector  4 , in addition to the above-mentioned components, and the protective glass  33  is integrated with the optical device  30 .  
      The protective glass  33  is provided in a lid shape on the concave surface of the reflector  4 , and prevents dust from entering into the electrodeless lamp  1  when the optical device  30  is detached from the projector  100  or prevents broken pieces of the electrodeless lamp  1  due to a drop from being dispersed. A dielectric film for shielding microwaves may be coated on the protective glass  33 , or a metal mesh having a pitch sufficiently smaller than the wavelength λ may be inserted into the projective glass  33 .  
      Subsequently, the schematic structure of the optical unit  50  will be described.  
      The optical unit  50  includes an integrator illumination optical system  41 , a color separating optical system  42 , a relay optical system  43 , the liquid crystal light valves  77 R,  77 G, and  77 B, and a combining optical device  44 .  
      The components of the optical unit  50  are integrally provided in an optical part case  45  as a unit.  
      The integrator illumination optical system  41  is an optical system that uniformizes the illuminance of the plane on which light beams emitted from the light source device  30  are incident and which is orthogonal to the optical axis direction of the light beam (which is represented by a one-dot chain line. The integrator illumination optical system  41  includes a first lens array  111 , a second lens array  112 , a polarizing element  113 , and a superimposing lens  114 .  
      The first lens array  111  includes small lenses that are arranged in a matrix, and each of the small lenses has a substantially rectangular shape as viewed from the optical axis direction of the light beam. Each small lens divides a light beam emitted from the light source device  30  into partial light beams and emits the partial light beams in the optical axis direction thereof.  
      The second lens array  112  has substantially the same structure as the first lens array  111 , and includes small lenses that are arranged in a matrix. The second lens array  112  superimposes the light beams having passed through the small lenses of the first lens array  111  on the liquid crystal light valves  77 R,  77 G, and  77 B together with the superimposing lens  114 , thereby making the illuminance of the light beams uniform.  
      The polarizing element  113  is an optical element that converts light having two types of polarized components emitted from the electrodeless lamp  1  as the main components into one type of polarized light that can be modulated by the liquid crystal light valves  77 R,  77 G, and  77 B.  
      More specifically, light including two types of polarized components that has passed through the second lens array  112  is converted into one type of polarized light by the polarizing element  113  and is finally substantially superimposed on the liquid crystal light valves  77 R,  77 G, and  77 B by the superimposing lens  114 .  
      In this case, the polarized light accounting for about 50% of all light beams is converted into polarized light that can be modulated by the liquid crystal light valves by the polarizing element  113 , which makes it possible to improve the usage efficiency of light. When the polarizing element  113  is not provided, the polarized light accounting for half the light beams is consumed as heat.  
      The color separating optical system  42  includes two dichroic mirrors  121  and  122  and a reflecting mirror  123 . A plurality of partial light beams emitted from the integrator illumination optical system  41  are separated into three light beams, that is, red (R), green (G), and blue (B) light components by the two dichroic mirrors  121  and  122 .  
      The dichroic mirror  121  is an optical element including a dielectric multi-layer film that transmits the green light component and the blue light component but reflects the red light component.  
      The dichroic mirror  121  transmits the green light component and the blue light component, but reflects the red light component among light beams emitted from the integrator illumination optical system  41 . The reflected red light component is also reflected from the reflecting mirror  123  to be incident on the red liquid crystal light valve  77 R through a field lens  119 .  
      The field lens  119  converts the light beams passing through the second lens array  112  into light beams parallel to the central axis (main light beam) thereof. The field lenses  119  provided on the incident sides of the blue and green liquid crystal light valves  77 B and  77 G have the same function as the field lens  119  provided on the incident side of the red liquid crystal light valve  77 R.  
      The dichroic mirror  122  is an optical element including a dielectric multi-layer film that transmits the blue light component but reflects the green light component.  
      The dichroic mirror  122  reflects the green light component of the blue light component and the green light component passing through the dichroic mirror  121 . The reflected green light component is incident on the green liquid crystal light valve  77 G through the field lens  119 .  
      The blue light component passing through the dichroic mirror  122  is incident on the blue liquid crystal light valve  77 B through the relay optical system  43  and the field lens  119 .  
      The relay optical system  43  includes an incident-side lens  131 , a pair of relay lenses  133 , and reflecting mirrors  132  and  135 . The relay optical system  43  guides the blue light component separated by the color separating optical system  42  to the blue liquid crystal panel  77 B.  
      The relay optical system  43  is used for the blue light component in order to prevent a reduction in the usage efficiency of light due to the scattering of light, since the length of the optical path of the blue light component is larger than those of the other light components. That is, the relay optical system is used for the blue light component in order to transmit the partial light beam incident on the incident-side lens  131  to the field lens  119 . In this embodiment, the relay optical system  43  transmits the blue light component among the three light components, but the invention is not limited thereto. For example, the relay optical system  43  may transmit the red light component by changing the functions of the dichroic mirrors  121  and  122 .  
      Incident-side polarizing plates  82  on which the light components separated by the color separating optical system  42  are incident are provided on the incident sides of the liquid crystal light valves  77 R,  77 G, and  77 B, and emission-side polarizing plates  83  are provided on the emission sides of the liquid crystal light valves  77 R,  77 G, and  77 B.  
      The incident-side polarizing plates  82  and the emission-side polarizing plates  83  transmit light components polarized in a predetermined direction among the light beams separated by the color separating optical system  42  and absorb the other light beams. Each of the polarizing plates is formed of a laminate of a substrate made of sapphire glass and a polarizing film formed on the substrate.  
      Each of the liquid crystal light valves  77 R,  77 G, and  77 B uses polysilicon thin film transistors (TFTs) as switching elements, and includes a pair of transparent substrates opposite to each other and a liquid crystal layer interposed therebetween.  
      The liquid crystal light valves  77 R,  77 G, and  77 B, which are transmissive liquid crystal panels, modulate the red, green, and blue light components incident thereon through the incident-side polarizing plates  82  according to red, green, and blue image information and emit the modulated red, green, and blue light components through the corresponding emission-side polarizing plates  83 .  
      The combining optical system  44  is a cross dichroic prism that combines the modulated red, green, and blue light components emitted from the corresponding emission-side polarizing plates  83  and emits modulated light indicating a full color image.  
      In the combining optical system  44 , the dielectric multi-layer film for reflecting the red light component and the dielectric multi-layer film for reflecting the blue light component are provided in an X shape along the interfaces among four right-angled prisms, and the dielectric multi-layer films combine the three light components.  
      The modulated light combined by the combining optical system  44  is enlarged by the projection lens  52  and is then projected onto the screen SC.  
      The liquid crystal light valves  77 R,  77 G, and  77 B, the three emission-side polarizing plates  83 , and the combining optical system  44  are integrated into one unit.  
      As described above, according to this embodiment, the following effects are obtained.  
      (1) The microwave oscillator  10  is a diamond SAW oscillator provided with a diamond SAW resonator. Therefore, the microwave oscillator  10  generates microwaves immediately after being supplied with power and thus can rapidly turn on the electrodeless lamp  1 . In addition, the microwave oscillator  10  has a small size, high power resistance, and a small variation in frequency although the temperature varies.  
      The microwave oscillated by the microwave oscillator  10  is amplified by the amplifying unit  11  and is then radiated from the antenna provided in the cavity  3 . Therefore, the microwave is kept in the cavity  3 .  
      Therefore, the microwave does not leak to the outside of the cavity  3 , which makes it possible to prevent the microwave from having an adverse effect on medical instruments or wireless communication apparatuses, such as WLAN, Home RF, Zigbee (registered trademark), and Bluetooth (registered trademark) used in an ISM band.  
      Further, two or more microwaves having different phases output from the amplifying units  11  are radiated onto the electrodeless lamp  1 , and thus microwaves having a plurality of phases with the maximum amplitude are sequentially supplied. Thus, it is possible make the electrodeless lamp  1  to emit light with high efficiency.  
      Therefore, according to this embodiment of the invention, it is possible to provide the projector  100  including the light source device  30  capable of being rapidly turned on and emitting light with high efficiency.  
      (2) The microwaves W 2   a  to W 2   c  having different phases are radiated onto three branched light emitting areas Spo in the electrodeless lamp  1 . Therefore, energy is dispersed to a plurality of points without being concentrated on one point.  
      Furthermore, a plurality of light emitting areas Spo communicate with one another in the electrodeless lamp  1 . Therefore, the cycle of evaporation, dissociation, and condensation of a light emitting material is not hindered, and the light emitting material is continuously circulated by convection in the electrodeless lamp  1  while emitting light.  
      Therefore, it is possible to effectively convert microwave power into optical energy.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  100  including the light source device  30  with high energy efficiency.  
      (3) Each optical waveguide Ref for guiding light emitted from the corresponding light emitting area to the light radiating area Emi is provided on the upper part of the corresponding light emitting area Spo. Therefore, light components emitted from the corresponding light emitting areas Spo are concentrated on the light radiating area Emi by the optical waveguides Ref.  
      Therefore, light components are concentrated on a plurality of light emitting areas Spo without leaking to the outside, and the light components are used as a light source of a projected image, which makes it possible to improve energy efficiency and increase the quantity of light.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  100  including the light source device  30  with high energy efficiency and high brightness.  
      (4) The phase control unit  14  adjusts the phases of microwaves W 2   a  to W 2   c  output from the microwave oscillators  10  such that the microwaves W 2   a  to W 2   c  have a phase different of (2π)/3. Therefore, microwaves having different phases are radiated onto the three light emitting areas Spo of the electrodeless lamp  1 , and are concentrated on the light radiating area Emi.  
      In this way, a three-phase microwave having microwave power larger than that of a single-phase alternating current is converted into light with high energy efficiency.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  100  including the light source device  30  with high energy efficiency and high brightness.  
      (5) The light source device  30  includes the power control unit  12  for adjusting the amplification factor of each of the amplifying units  11 . Therefore, the adjustment of microwave power makes it possible for the electrodeless lamp  1  to emit light with a desired amount of light.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  100  including the light source device  30  capable of obtaining a desired amount of light.  
      (6) Each of the isolators  13  is provided in the latter stage of the amplifying unit  11  to shield a reflected wave. Therefore, the isolators  13  can prevent the reflected wave from returning to the amplifying unit  11 .  
      Thus, the isolators  13  can protect the amplifying unit  11  and the microwave oscillator  10  provided in the previous stage thereof from the reflected microwave.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  100  including the light source device  30  capable of stably operating.  
      (7) The projector  100  includes the high-brightness light source device  30  capable of obtaining a desired amount of light and the liquid crystal light valves  77 R,  77 G, and  77 B each of which converts light emitted from the light source device  30  into modulated light having a clear color in response to image signals.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  100  capable of obtaining a clear projected image.  
      (Second Embodiment)  
      &lt;Outline of Second Projector&gt; 
       FIG. 9  is a diagram schematically illustrating the structure of a projector according to a second embodiment of the invention.  
      A projector  200  according to the second embodiment is similar to the projector  100  according to the first embodiment except for the following three points.  
      First, an electrodeless lamp  101  of the projector  200  has a different structure from that of the electrodeless lamp  1  ( FIG. 5 ).  
      Second, instead of the phase control unit  14  ( FIG. 1 ), a frequency control unit  66  is provided in a light source device  35  of the projector  200 .  
      Third, a storage unit  56  of the projector  200  stores programs, and some of the programs are different from those in the projector  100 .  
      In the second embodiment, the same components as those in the projector  100  according to the first embodiment have the same reference numerals, and the schematic structure of the projector  200  will be described, centered on the above-mentioned three different points.  
      First, a microwave circuit unit  28  of the light source device  35  will be described with reference to  FIG. 9 .  
      The microwave circuit unit  28  includes the frequency control unit  66  in addition to the plurality of microwave oscillators  10 , the plurality of amplifying units  11 , the power control unit  12 , and the plurality of isolators  13  described in the first embodiment.  
      The frequency control unit  66  is a frequency adjusting circuit that adjusts the frequencies of microwaves oscillated by the plurality of microwave oscillators  10 . The frequency control unit  66  can stop oscillating the microwaves by setting an oscillation frequency to zero and thus control the start/stop of oscillation.  
      The frequency control unit  66  adjusts the frequencies of the microwaves oscillated by the microwave oscillators  10  according to a frequency adjusting program stored in the storage unit  56  when the electrodeless lamp  101  is turned on.  
      Adjustment information and frequencies for allowing color light emitting bodies (hereinafter, referred to as color light emitting members) CoR, CoG, and CoB ( FIG. 10 ) corresponding to the microwave oscillators  10  to emit light with the maximum efficiency are defined in the frequency adjusting program stored in the storage unit  56 .  
      &lt;Detailed Description of Second Electrodeless Lamp&gt; 
       FIG. 10  is a perspective view schematically illustrating the structure of a peripheral portion of the second electrodeless lamp.  FIGS. 11A and 11B  are cross-sectional views illustrating main parts of the peripheral portion of the electrodeless lamp. In  FIG. 10 , a reflector  4  is shown in sectional view for the purpose of convenience of the explanation.  
      The schematic structure of the electrodeless lamp  101 , serving as the second electrodeless lamp, will be described with reference to  FIG. 10  and  FIGS. 11A and 11B . In this embodiment, a description of the same components as those of the electrodeless lamp  1  will be omitted.  
      The electrodeless lamp  101  a plurality of light emitting members CoR, CoG, and CoB, a plurality of optical waveguides Ref 2 , and a light radiating portion Emi 2 .  
      Light emitting materials having different emission spectra are filled into the plurality of light emitting members CoR, CoG, and CoB. Spaces having the light emitting materials filled therein are independently provided. It is preferable that the light emitting materials have rare gases having red, green, and blue emission spectra as the main components.  
      A light emitting material having a red emission spectrum is filled into the light emitting member CoR corresponding to an antenna  2   a.    
      A light emitting material having a green emission spectrum is filled into the light emitting member CoG corresponding to an antenna  2   b.    
      A light emitting material having a blue emission spectrum is filled into the light emitting member CoB corresponding to an antenna  2   c.    
      The optical waveguides Ref 2  are optical systems for guiding light components emitted from the light emitting members CoR, CoG, and CoB by plasma emission to the light radiating portion Emi 2 .  
      A reflective layer formed of, for example, aluminum is provided on the outer surface of the optical waveguide Ref 2 . The reflective layer guides light components emitted from the light emitting members CoR, CoG, and CoB to the light radiating portion Emi 2  and prevents microwaves or light from leaking from the optical waveguide Ref 2  to the outside.  
      The light radiating portion Emi 2  is represented by a hatched portion in  FIG. 10 , and is transparent. The light components emitted from the light emitting members CoR, CoG, and CoB and concentrated by the optical waveguides Ref 2  are emitted to the outside through the light radiating portion Emi 2 .  
      Since the light radiating portion Emi 2  is disposed at a substantially focal point of the reflector  4 , light emitted from the light radiating portion Emi 2  is concentrated without leakage and is then emitted to the optical unit  50 .  
      The red, green, and blue light components are combined into substantially white light, and thus the substantially white light is emitted from the light radiating portion Emi 2 .  
       FIG. 11A  is a first aspect of the cross-sectional view of  FIG. 10  taken along the line U.  
      The light emitting member CoG is provided in the cavity  3  so as to protrude with substantially the same length as the antenna  2   b . The external reflective layer is not provided in the protruding area.  
      The light emitting material having a green emission spectrum is filled into the light emitting member CoG, and the space of the light emitting member CoG having the light emitting material filled therein is separated from the optical waveguide Ref 2  by a lens Le.  
      The lens Le condenses light emitted from the light emitting member CoG on the optical waveguide Ref 2 .  
      The reflective layer is provided on the entire outer surface of the optical waveguide Ref 2 , and the reflective layer is also formed up to the lower part of the light radiating portion Emi 2  that is represented by arrow.  
      Light incident on the optical waveguide Ref 2  passes through glass on the outer wall of the optical waveguide Ref 2  and is repeatedly reflected from the external reflective layer to be concentrated on the light radiating portion Emi 2 .  
       FIG. 11B  is a second aspect of the cross-sectional view of  FIG. 10  taken along the line U.  
      The second aspect is similar to the first aspect except for the following two different points.  
      First, the inner surface of the optical waveguide Ref 2  is formed of the same material as that forming the outer wall thereof. A reflective layer is provided on the outer surface of the optical waveguide Ref 2 .  
      Second, in the second aspect, the lens Le is not provided.  
      Light emitted from the light emitting member CoG is incident on a glass member in the optical waveguide Ref 2  and passes through the glass member. Then, the light is repeatedly reflected from the external reflective layer to be concentrated on the light radiating portion Emi 2 .  
      Since the optical waveguide Ref 2  serves as a rod integrator for repeatedly reflecting light to make the illuminance of light uniform, light emitted from the light radiating portion Emi 2  has little illuminance irregularity.  
      The structure of the cavities  3  and the protruding length of the antenna  2   b  are the same as those in the electrodeless lamp  1 .  
      &lt;Lighting Aspect of Second Electrodeless Lamp&gt; 
      Next, a lighting aspect of the electrodeless lamp  101  having the above-mentioned structure will be described with reference to  FIGS. 9 and 10 .  
      The optical unit  35  according to this embodiment of the invention oscillates microwaves having frequencies for allowing the light emitting members CoR, CoG, and CoB respectively corresponding to the three antennas  2   a  to  2   c  to emit light with the maximum efficiency to turn on the electrodeless lamp  101 .  
      More specifically, the control unit  53  controls the frequency control unit  66  to output microwaves having the following frequencies from the microwave oscillators  10  corresponding to the three antennas  2   a  to  2   c.    
      The microwave oscillator  10  corresponding to the antenna  2   a  outputs a microwave having a frequency for allowing the light emitting material having a red emission spectrum that is filled in the light emitting member CoR to emit light with the maximum efficiency.  
      The microwave oscillator  10  corresponding to the antenna  2   b  outputs a microwave having a frequency for allowing the light emitting material having a green emission spectrum that is filled in the light emitting member CoG to emit light with the maximum efficiency.  
      The microwave oscillator  10  corresponding to the antenna  2   c  outputs a microwave having a frequency for allowing the light emitting material having a blue emission spectrum that is filled in the light emitting member CoB to emit light with the maximum efficiency.  
      Further, the control unit  53  controls the power control unit  12  to adjust the amplification factor of each of the amplifying units  11  to radiate microwave power having energy capable of obtaining appropriate R, G, and B light components required for a clear projected image to the light emitting members CoR, CoG, and CoB.  
      The amplification factor of each microwave oscillator is defined in adjustment information of the frequency adjusting program.  
      In this way, the electrodeless lamp  101  of the light source device  35  continuously emits a necessary amount of light obtained by combining only the necessary light components.  
      In this embodiment, the light source device  35  emits substantially white light, but the invention is not limited thereto. For example, the light source device  35  may sequentially emit R, G, and B light components.  
      This is realized by the following method: the frequency control unit  66  sequentially controls the start/stop of the oscillation of microwaves from the microwave oscillators  10  corresponding to the light emitting members CoR, CoG, and CoB so that the light emitting members CoR, CoG, and CoB sequentially emit R, G, and B light components.  
      An application of a projector when sequential control is performed on the light source device  35  will be described in a third embodiment.  
      The electrodeless lamp  101  concentrates light emitted from the light emitting members CoR, CoG, and CoB on the light radiating portion Emi 2 , but the invention is not limited thereto. For example, a light emitting area may be provided for each light emitting member, and each light emitting area may be independently used as a color light source.  
      This structure makes it possible to obtain the necessary amount of R, G, and B light components.  
      An application of a projector when light emitting areas are independently provided for the light emitting members CoR, CoG, and CoB of the light source device  35  will be described in a fourth embodiment.  
      As described above, according to this embodiment, the following effects are obtained in addition to the effects described in the first embodiment.  
      (1) The microwave oscillator  10  is a diamond SAW oscillator provided with a diamond SAW resonator. Therefore, the microwave oscillator  10  generates microwaves immediately after being supplied with power and thus can rapidly turn on the electrodeless lamp  101 . In addition, the microwave oscillator  10  has a small size, high power resistance, and a small variation in frequency although the temperature varies.  
      The microwave oscillated by the microwave oscillator  10  is amplified by the amplifying unit  11  and is then radiated from the antenna provided in the cavity  3 . Therefore, the microwave is kept in the cavity  3 .  
      Therefore, the microwave does not leak to the outside of the cavity  3 , which makes it possible to prevent the microwave from having an adverse effect on medical instruments or wireless communication apparatuses, such as WLAN, Home RF, Zigbee (registered trademark), and Bluetooth (registered trademark) used in an ISM band.  
      Further, since the microwave oscillator  10  outputs a microwave having a peak around a predetermined frequency, the microwave oscillator  10  does not need extra microwave power.  
      Furthermore, the light emitting members CoR, CoG, and CoB are provided for the corresponding microwave oscillators  10 , and light emitting materials having different emission spectra are filled in the light emitting members CoR, CoG, and CoB. Therefore, the color light components necessary to project an image are emitted as color light components having a sharp characteristic.  
      Therefore, it is possible to generate only necessary color light components with high efficiency.  
      As a result, it is possible to provide the projector  200  having the light source device  35  having high energy efficiency and capable of being rapidly turned on.  
      (2) The optical waveguides Ref 2  for guiding light components emitted from the light emitting members CoR, CoG, and CoB to the light radiating portion Emi 2  are provided for the light emitting members CoR, CoG, and CoB. Therefore, light components emitted from the light emitting members CoR, CoG, and CoB are emitted from the light radiating portion Emi 2 .  
      Therefore, when all the light emitting members CoR, CoG, and CoB emit light components, a combination of the light components is emitted from the light radiating portion Emi 2 . Therefore, it is possible to use the same optical structure as a lamp emitting substantially white light. In addition, the light source device having the light emitting members CoR, CoG, and CoB that sequentially emit light components can be used as a light source of a field sequential type.  
      Thus, the invention can be applied to various optical types of projectors, and thus the convenience of the light source device  35  is improved.  
      As a result, it is possible to provide the projector  200  including the light source device  35  that is convenient for use.  
      (3) The light source device  35  includes the frequency control unit  66  for adjusting the frequencies of the microwaves oscillated by the microwave oscillators  10 . Therefore, the light source device  35  can adjust the frequencies of microwaves such that the light emitting members corresponding to the microwave oscillators  10  emit light with the maximum efficiency.  
      As a result it is possible to provide the projector  200  including the light source device  35  having high energy efficiency.  
      (4) The light source device  35  includes the power control unit  12  for adjusting the amplification factor of each of the amplifying units  11 . Therefore, the light source device  35  can adjust microwave power such that the light emitting members corresponding to the microwave oscillators  10  emit light with the maximum efficiency.  
      As a result it is possible to provide the projector  200  including the light source device  35  having high energy efficiency.  
      (5) The light source device  35  includes the power control unit  12  for adjusting the amplification factor of each of the amplifying units  11 . Therefore, the light source device  35  can adjust microwave power such that the light emitting members corresponding to the microwave oscillators  10  emit light with the maximum efficiency.  
      As a result it is possible to provide the projector  200  including the light source device  35  having high energy efficiency.  
      (6) Each of the isolators  13  is provided in the latter stage of the corresponding amplifying unit  11  to shield a reflected wave. Therefore, the isolator  13  can prevent the reflected wave from returning to the amplifying unit  11 .  
      Thus, the isolator  13  can protect the amplifying unit  11  and the microwave oscillator  10  provided in the previous stage thereof from the reflected microwave.  
      As a result, according to this embodiment of the invention, it is possible to provide the projector  200  including the light source device  35  capable of stably operating.  
      (7) The light source device  35  includes the frequency control unit  66  and the amplifying units  11 . Therefore, the light source device  35  can emit a necessary amount of light having necessary spectral components of R, G, B spectral components.  
      In this way, the light source device  35  can emit ideal light for the light modulating devices including red, green, and blue spectral components respectively corresponding to the liquid crystal light valves  77 R,  77 G, and  77 B. Similarly, even when other light modulating devices, such as tilt mirror devices or reflective liquid crystal display devices, are used, the light source device  35  can emit light having ideal spectral components for the light modulating devices.  
      As a result, it is possible to provide the projector  200  including the light source device  35  capable of emitting light having ideal spectral components.  
      (Third Embodiment)  
      &lt;First Application of Light Source Device&gt; 
       FIG. 12  is a diagram schematically illustrating the structure of a projector according to a third embodiment of the invention.  
      The schematic structure of a projector  300  that uses a tilt mirror device as a light modulating device and the light source device  35  according to the second embodiment as a light source will be described with reference to  FIGS. 8, 9 , and  12 .  
      In this embodiment, the same components as those in the first and second embodiments have the same reference numerals, and a detailed description thereof will be omitted.  
      The projector  300  uses a digital micromirror device (DMD; made by Texas Instruments Inc.), which is a single tilt mirror device, as a light modulating device.  
      The projector  300  includes a light source device  35 , a first lens array  111 , a second lens array  112 , a superimposing lens  114 , a DMD  301 , and a projection lens  52 .  
      Light emitted from the light source device  35  passes through the first lens array  111  and the second lens array  112  to have uniform illuminance, and then passes through the superimposing lens  114 . Then, the light is incident on the DMD, thereby forming an image.  
      The DMD  301  is a light modulating device that reproduces contrast by changing the angle of a plurality of small mirrors arranged in a lattice shape several thousand times or more per second in response to image signals to turn on or off the small mirrors.  
      The projector having a single DMD according to the related art uses a light source device for emitting substantially white light, and thus needs to have a rotary member including R, G, and B color filters, called color wheels, in order to obtain R, G, and B light components from the white light. Accurate rotation control needs to be performed on the color wheel, and the color wheel occupies a large area in the projector.  
      The projector  300  controls the light source device  35  so that the light source device  35  sequentially emits R, G, and B light components. Further, image signal information corresponding to the color light components is transmitted to the DMD  301  in synchronization with the time when the color light components are switched.  
      Then, the DMD  301  sequentially reflects modulated light, that is, the R, G, and B light components forming an image.  
      The projection lens  52  enlarges the modulated light from the DMD  301  and projects the enlarged light onto the screen.  
      The projected image is displayed by sequentially projecting the R, G, and B light components. However, the R, G, and B light components incident on the human eye are superimposed in the brain by the residual image phenomenon of the human eye (brain) so that a viewer views a full color image by the three primary color principle of light.  
      As described above, according to this embodiment, the following effects are obtained in addition to the effects of the above-described embodiments.  
      (1) The projector  300  uses the DMD  301  as a light modulating device and deals with all light components regardless of the polarization of light. Therefore, the projector  300  does not need the incident-side polarizing plate  82 , the emission-side polarizing plate  83 , and the polarizing element  113  of the optical unit in the first embodiment.  
      Further, the projector  300  does not need the color wheel, unlike the projector according to the related art including a light source device for emitting substantially white light that needs the color wheel.  
      Accordingly, it is possible to simplify the structure of an optical system and thus to achieve a projector having a small size. In addition, it is possible to reduce the number of driving parts and thus improve the reliability of the projector.  
      As a result, it is possible to provide a projector having a small size and high reliability.  
      (Fourth Embodiment)  
      &lt;Second Application of Light Source Device&gt; 
       FIG. 13  is a diagram schematically illustrating the structure of a projector according to a fourth embodiment of the invention.  
      In this embodiment, light emitting areas are provided for the light emitting members CoR, CoG, and CoB of the electrodeless lamp  101  according to the second embodiment, and the light emitting areas are independently used as electrodeless lamps. The schematic structure of a projector  400  using the electrodeless lamps for R, G, and B light components will be described below with reference to  FIGS. 9, 10 , and  13 .  
      In the fourth embodiment, the same components as those in the first and second embodiments have the same reference numerals, and a description thereof will be omitted.  
      The projector  400  includes lamp bodies LR, LG, and LB, first lens arrays  111 , second lens arrays  112 , polarizing elements  113 , and superimposing lenses  114 , liquid crystal light valves  77 R,  77 G, and  77 B, a combining optical system  44 , and a projection lens  52 .  
      The lamp body LR includes an electrodeless lamp  101 R, an antenna  2   a , a cavity  3 , and a reflector  4 .  
      The electrodeless lamp  101 R is an independent electrodeless lamp that emits a red light component and includes the light emitting member CoR of the electrodeless lamp  101  according to the second embodiment and the light radiating portion Emi 2  integrally formed with the light emitting member CoR in a cylindrical shape.  
      The antenna  2   a , the cavity  3 , and the reflector  4  have the same structures as those in the light source device  35 . The antenna  2   a  is connected to the microwave oscillator  28  (not shown) of the light source device  35  through a cable.  
      The structure of the lamp bodies LG and LB is similar to the structure of the lamp body LR except that the light emitting member CoG of the electrodeless lamp  101 G emits a green light component and the light emitting member CoB of the electrodeless lamp  101 B emits a blue light component.  
      The first lens array  111 , the second lens array  112 , the polarizing element  113 , and the superimposing lens  114  are provided for each of the optical paths of the lamp bodies LR, LG, and LB. The first lens arrays  111 , the second lens arrays  112 , the polarizing elements  113 , and the superimposing lenses  114  make the illuminance of the R, G, and B light components nearly uniform, polarize the R, G, and B light components in a predetermined direction, and cause the polarized light components to be incident on the corresponding liquid crystal light valves  77 R,  77 G, and  77 B.  
      The combining optical system  44  combines color light components modulated by the liquid crystal light valves  77 R,  77 G, and  77 B into modulated light for forming a full color image in response to image signals and emits the modulated light.  
      The projection lens  52  enlarges the modulated light and projects the enlarged light onto the screen.  
      As described above, according to this embodiment, the following effects are obtained in addition to the effects of the above-described embodiments.  
      (1) The lamp bodies LR, LG, and LB emit R, G and B light components, respectively. Therefore, it is unnecessary to separate light into R, G, and B color light components, and thus the color separating optical system  42  according to the first embodiment that includes two dichroic mirrors  121  and  122  and the reflecting mirror  123  is not needed.  
      Thus, it is possible to shorten the length of an optical path.  
      As a result, it is possible to provide the projector  400  having a small size.  
      (2) The power control unit  14  adjusts the quantity of R, G, and B light components respectively emitted from the lamp bodies LR, LG, and LB to a predetermined value. Therefore, it is possible to directly adjust the color of a projected image while viewing the projected image.  
      Therefore, it is possible to provide the projector  400  capable of obtaining a clear projected image.  
      The invention is not limited to the above-described embodiments, and various modifications and changes of the invention can be made without departing from the scope of the invention. For example, the following modifications can be made.  
      (First Modification)  
      A first modification will be described with reference to  FIG. 8 . In the above-described embodiments, the light source device  30  or the light source device  35  is provided in the projector, but the invention is not limited thereto.  
      For example, since the light source device  30  is rapidly and reliably turned on, can stably obtain a desired quantity of light, and has a small size and a light weight, it may be applied to illuminating devices for airplanes, ships, and vehicles and interior illuminating devices.  
      (Second Modification)  
      A second modification will be described with reference to  FIG. 8 . In the first embodiment, the projector  100  is a projector of a three-liquid-crystal-panel type that uses three liquid crystal light valves  77 R,  77 G, and  77 B as light modulating devices, but the invention is not limited thereto.  
      For example, the projector may use as a light modulating device a single liquid crystal light valve that has red, green, and blue color filters arranged in a matrix and emits full-color modulated light. Alternatively, the projector may use a reflective liquid crystal display device or a tilt mirror device as a light modulating device.  
      For example, when the tilt mirror device is used, the incident-side polarizing plate  82 , the emission-side polarizing plate  83 , and the polarizing element  113  are not needed. Therefore, the structure of an optical system is different from that shown in  FIG. 8  according to a light modulating device used.  
      A rear projector including the above-mentioned light modulating device and a screen may be used.  
      These structures also make it possible to obtain the same effects as described in the embodiments.  
      (Third Modification)  
      A third modification will be described with reference to  FIG. 5 . In the first embodiment, the light radiating area Emi and the light emitting areas Spo of the electrodeless lamp  1  are provided so as to extend in the opposite direction, but the invention is not limited thereto. For example, the electrodeless lamp may include a plurality of light emitting areas and one light radiating area.  
      For example, a plurality of light emitting areas and a light radiating area may be provided in a trefoil shape or a starfish shape with the light radiating area disposed at the center thereof.  
      Further, similarly, a plurality of light emitting members and one light radiating portion may be provided in the electrodeless lamp  101  according to the second embodiment.  
      These structures also make it possible to obtain the same effects as described in the first and second embodiments.  
      As described above, according to the invention, it is possible to provide a projector including a light source device that is rapidly turned on and emits light with high energy efficiency.