Abstract:
There are provided an optical member, an illuminating device, and a projection type video display apparatus, capable of satisfying both or at least one of the following two functions. That is, one is to prevent light re-incident upon a reflective polarizer from becoming linearly polarized light having an undesirable polarization direction. The other is to improve exploiting efficiency of returned light. A reflection member and a ¼λ plate are disposed on the light entrance surface side of a rod integrator, and a reflective polarizer is disposed on the light exit surface side thereof. The reflection member is formed with a light transmission-use aperture, and an LED chip of the LED is positioned in the light transmission-use aperture. A mirror is formed at the rear surface of the LED chip, thereby eliminating occurrence of light leakage from the light transmission-use aperture. Furthermore, provision of the above-described ¼λ plate prevents the light re-incident upon the reflective polarizer from becoming linearly polarized light having an undesirable polarization direction.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to an optical member and an illuminating device using the optical member.  
       BACKGROUND ART  
       [0002]     Conventionally, there have been used rod integrators with light integration effect, for preventing non-uniformity of light intensity distribution of a light source. In addition, as  FIG. 11  shows, there have been proposed illuminating devices formed with a reflective polarizer  101  and a ¼λ plate  102  being disposed on the light exit surface side of a rod integrator  100 , and a mirror  103  having a light transmission-use aperture  103   a  being disposed on the light entrance surface side thereof, thereby converting illumination light into linearly polarized light of a specific direction (see Japanese Patent Laying-open No. 2003-98597, Japanese Patent Laying-open No. 2005-25064).  
         [0003]     However, in the above-described conventional art, shown in  FIG. 10A , in a case that the ¼λ plate  102  is provided on the light exit surface side of the rod integrator  100 , and circularly-polarized light, generated as a result of being reflected by the reflective polarizer  101  and passing through the ¼λ plate  102 , is reflected for an odd number of times on the side surfaces of the rod integrator  100  before re-incidence upon the ¼ plate λ  102 , the resultant light becomes linearly polarized light having an undesirable polarization direction when passing through the ¼λ plate  102 . Therefore, there is a drawback that the polarization conversion capability is inferior. In addition, as shown in  FIG. 10B , the light reflected by the reflective polarizer  101  leaks from the light transmission-use aperture  103   a  of the mirror  103 , resulting in low exploiting efficiency of returned light (recycled light).  
       DISCLOSURE OF THE INVENTION  
       [0004]     In view of the above circumstances, an object of the present invention is to satisfy both or at least one of the following two functions. One is to prevent light re-incident upon a reflective polarizer from becoming linearly polarized light having an undesirable polarization direction. The other is to improve exploiting efficiency of returned light.  
         [0005]     In order to solve the above problems, an optical member of the present invention comprises a rod integrator for integrating lights incident from a light entrance surface and allowing the incident light to exit from a light exit surface, a reflective polarizer for transmitting a specific linearly polarized light and reflecting the other polarized lights so as to be returned to an inside of the rod integrator, out of lights that exit from the light exit surface of the rod integrator, a reflecting means with aperture for transmitting light from a light transmission-use aperture, and reflecting the returning light that exits from the light entrance surface of the rod integrator by a plane or concave reflection surface so as to be re-incident upon the light entrance surface, and a ¼λ plate provided on a light entrance surface side of the rod integrator.  
         [0006]     With the above structure, provision of the above-described ¼λ plate prevents the light re-incident upon the reflective polarizer from becoming linearly polarized light having an undesirable polarization direction. More specifically, in conventional structure (structure in which the ¼λ plate is provided on a light exit surface side of the rod integrator), reflected linearly-polarized light other than the specific linearly polarized light becomes circularly polarized light when passing through the ¼λ plate so as to become returned light. Since a rotation direction of a polarization of the circularly polarized light is reversed upon reflection, the circularly polarized light becomes the linearly polarized light other than the specific linearly polarized light after being reflected for an odd number of times and passing through the ¼λ plate. With the structure of the present application, the ¼λ plate is provided on the light entrance surface side of the rod integrator, and therefore, the above will not occur.  
         [0007]     In the optical member according to the above structure, the ¼λ plate may be formed with the aperture being the same or approximately the same in position and size as the light transmission-use aperture.  
         [0008]     In addition, an illuminating device of the present invention comprises any one of the above optical members, and a light source for irradiating light onto a light entrance surface of the rod integrator via the light transmission-use aperture (hereinafter, referred to as a first illuminating device in this section).  
         [0009]     In the first illuminating device, the light source may be provided adjacent to the light transmission-use aperture. In addition, the light source may include a reflection means.  
         [0010]     In the first illuminating device, it may be possible that the light source is formed with a lamp, and a converging means for converging emission light from the lamp by any one of reflection, refraction, and diffraction, and the light transmission-use aperture is disposed in a light converging area of emission light from the light source.  
         [0011]     In addition, an illuminating device of the present invention comprises (a) an optical member including a rod integrator for integrating lights incident from a light entrance surface and allowing the incident lights to exit from a light exit surface, a reflective polarizer for transmitting a specific linearly polarized light, and reflecting the other polarized lights, out of lights that exit from the light exit surface of the rod integrator, and a ¼λ plate provided on the light exit surface side or the light entrance surface side of the rod integrator, and (b) a light source with a reflection surface having a reflection surface for reflecting light emitted from a light-emitting element so that the light is guided in an anterior direction, in which the light emitted from the light source with a reflection surface is incident upon the light entrance surface of the rod integrator, and returned light that exits from the light entrance surface of the rod integrator is reflected by the reflection surface of the light source with a reflection surface so that the returned light is once again guided to the light entrance surface of the rod integrator (hereinafter, referred to as a second illuminating device in this section).  
         [0012]     With the above structure, the light source with a reflection surface does not include a light transmission-use aperture, so that it is possible to improve exploitation efficiency of the returned light.  
         [0013]     In the second illuminating device, the reflection surface of the light source may be plane. In addition, in the second illuminating device, the reflection surface of the light source may be concave.  
         [0014]     In these illuminating devices, the light source may be a color light source for emitting light of a certain color (hereinafter, referred to as a third illuminating device in this section). Or, in these illuminating devices, the light source may be a white light source (hereinafter, referred to as a fourth illuminating device in this section).  
         [0015]     In addition, an illuminating device of the present invention comprises a third illuminating device for emitting light of a first color, a third illuminating device for emitting light of a second color, a third illuminating device for emitting light of a third color, and an optical member for transmitting light of each color from each illuminating device in approximately the same direction. In such the structure, it is possible that the light of a first color is red, the light of a second color is blue, and the light of a third color is green (hereinafter, referred to as a fifth illuminating device in this section). In addition, in the fifth illuminating device, it may be configured such that red light, blue light, and green light are continuously emitted during illumination (hereinafter, referred to as a sixth illuminating device in this section). Or, in the fifth illuminating device, it may be configured such that red light, blue light, and green light are emitted in a time-sequential manner during illumination (hereinafter, referred to as a seventh illuminating device in this section).  
         [0016]     Furthermore, a projection type video display apparatus may be formed of the third illuminating device for emitting red light, the third illuminating device for emitting blue light, the third illuminating device for emitting green light, light valves each provided for receiving light of each color from each illuminating device, and a projection means for mixing and projecting image light of each color obtained via each light valve.  
         [0017]     In addition, the projection type video display may be formed of the fourth illuminating device or the sixth illuminating device, one full-color light valve, and a projection means for projecting image light obtained via the full-color light valve.  
         [0018]     Furthermore, the projection type video display may be formed of the fourth illuminating device or the six illuminating device, a separation means for separating white color light emitted from the illuminating device into red light, green light, and blue light, light valves each provided for receiving light of each color, and a projection means for mixing and projecting image light of each color obtained via each light valve.  
         [0019]     In addition, the projection type video display may be formed of the seventh illuminating device, one light valve, means for supplying a video signal of each color to the light valve in synchronization with emission timing of light of each color, and a projection means for projecting image light obtained via the light valve.  
         [0020]     According to the present invention, it is possible to prevent light re-incident upon a reflective polarizer from becoming linearly polarized light having an undesirable polarization direction, and in addition, to improve exploiting efficiency of returned light.  
         [0021]     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a descriptive diagram showing three-panel projection type video display apparatuses provided with optical members (illuminating devices) of the present invention;  
         [0023]      FIG. 2A  is a descriptive diagram showing the optical member (illuminating device) of  FIG. 1 ;  
         [0024]      FIG. 2B  is a descriptive diagram showing structure in which a tapered rod, which replaces a rod in the structure of  FIG. 2A , is adopted;  
         [0025]      FIG. 3  is a descriptive diagram showing another optical member (illuminating device) of the present invention;  
         [0026]      FIG. 4  is a descriptive diagram showing a single panel projection type video display apparatus provided with another optical member (illuminating device) of the present invention;  
         [0027]      FIG. 5  is a descriptive diagram showing a single panel projection type video display apparatus provided with another optical member (illuminating device) of the present invention;  
         [0028]      FIGS. 6A, 6B , and  6 C are descriptive diagrams each of which shows another optical member (illuminating device) of the present invention;  
         [0029]      FIGS. 7A, 7B  are descriptive diagrams each of which shows another optical member (illuminating device) of the present invention;  
         [0030]      FIGS. 8A, 8B  are descriptive diagrams each of which shows another optical member (illuminating device) of the present invention;  
         [0031]      FIG. 9  is a descriptive diagram showing a three panel projection type video display apparatus provided with the optical members (illuminating devices) of the present invention;  
         [0032]      FIGS. 10A, 10B  are descriptive diagrams for describing drawbacks of the prior art; and  
         [0033]      FIG. 11  is a perspective view showing a rod integrator provided with a conventional polarization conversion function. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0034]     Hereinafter, embodiments of the present invention will be described based on  FIG. 1  to  FIG. 9 .  
         [0035]      FIG. 1  shows an optical system of a projection type video display apparatus  4 A. The projection type video display apparatus  4 A is provided with three illuminating devices  51 R,  51 G and  51 B (hereinafter, a numeral “ 51 ” is used for generally referring to the illuminating device). Each illuminating device  51  is constructed of an LED (light emitting diode)  11 , and an optical member  12 A. The illuminating device  51 R emits red light, the illuminating device  51 G emits green light, and the illuminating device  51 B emits blue light.  
         [0036]     The LED  11  is constructed of an LED chip, an LED substrate, and a heat sink. The LED  11  in the illuminating device  51 R emits red light, the LED  11  in the illuminating device  51 G emits green light, and the LED  11  in the illuminating device  51 B emits blue light.  
         [0037]     The optical member  12 A performs light integration so that intensity of the light emitted from the LED  11  is rendered uniform on the surface of an object to be illuminated (liquid crystal display panel, for example). Furthermore, the optical member  12 A includes operation for converting emission light into linearly polarized light of a specific direction. The shape of a light exit surface of the optical member  12 A is equal to or approximately equal to that of a liquid crystal display panel  1 . Detailed structure of the optical member  12 A will be described later.  
         [0038]     A liquid crystal drive signal (video signal) for each color is applied to each liquid crystal display panel  1 R,  1 B, and  1 G from a driver not shown. Each image light of each color modulated as a result of passing through each liquid crystal display panel  1  is mixed by a cross dichroic prism  2  so as to become full-color image light. This full-color image light is projected by a projection lens  3 , and displayed on a screen not shown.  
         [0039]     As shown in  FIG. 2A , the optical member  12 A is constructed of a rod integrator  15 , a reflective polarizer  16  provided on the light exit surface side of the rod integrator  15 , a reflection member  13  provided on the light entrance surface side of the rod integrator  15 , and a ¼λ plate  14  provided between the reflection member  13  and the light entrance surface. The reflection member  13  is constructed of a metal mirror or a dielectric multilayer film, for example. The reflection member  13  is provided with a light transmission-use aperture  13   a,  and the light emission portion of the LED  11  is arranged in this light transmission-use aperture  13   a.  The LED chip may emit light in approximately all directions ahead thereof, for example. In addition, the LED chip is arranged so that an air gap is formed between the light entrance surface (flat surface) and the LED chip. Furthermore, the LED chip is provided with a mirror (hereinafter, referred to as an LED rear surface mirror) for guiding emitting light of the LED chip in an anterior direction. This mirror is a metal mirror, for example.  
         [0040]     The reflective polarizer  16  is a so-called wire grid, and in this embodiment, the reflective polarizer  16  transmits S-polarized light as desired polarized light, and reflects P-polarized light (see the cited documents listed in the Background Art), for example. Needless to say, a reflection-to-transmission relationship between the S-polarize light and the P-polarized light may be reversed, that is, the reflective polarizer  16  may reflect the S-polarized light and transmit the P-polarized light. The P-polarized light reflected by the reflective polarizer  16  becomes circularly polarized light as a result of passing through the ¼λ plate  14 . The circularly polarized light is reflected by the reflection member  13 , and passes through the ¼λ plate  14  once again. The resultant light becomes the S-polarized light. The S-polarized light passes through the reflective polarizer  16  and exits from the rod integrator  15 . The shape of the rod integrator  15  is rectangular parallelepiped, however not limited thereto. In addition, the rod integrator  15  may have hollow structure of which inner surface is reflective, or may have non-hollow structure formed of a transparent member (transparent glass, for example).  
         [0041]     It is noted that in each illuminating device  51 , a plural number of LEDs  11  may be provided. In this case, a plurality of light transmission-use apertures  13   a  for guiding the emission light from each LED chip are formed. In the optical member  12 A, a tapered rod integrator  15 A may be used for the rod integrator  15 , as shown in  FIG. 2B . The size of the light exit surface of the rod integrator  15 A is larger than that of the light entrance surface. As a result of using the rod integrator  15 A, light with a low diffusion angle is guided to the light exit surface of the rod integrator  15 A. When the light with a low diffusion angle is guided to the light exit surface, transmission efficiency of desired polarized light in the reflective polarizer  16  improves. Instead of the rod integrator  15 , the rod integrator  15 A can be used in other configurations.  
         [0042]     With the illuminating device  51  provided with the above optical member  12 A, as described above, the P-polarized light reflected by the reflective polarizer  16  passes through the ¼λ plate  14 , and the resultant light becomes the circularly polarized light. The circularly polarized light is reflected by the reflection member  13 , and passes through the ¼λ plate  14  once again. The resultant light becomes the S-polarized light. The S-polarized light passes through the reflective polarizer  16 , and exits from the rod integrator  15 . That is, it is possible to prevent the light re-incident upon the reflective polarizer  16  from becoming linearly polarized light having an undesirable polarization direction. In addition, the LED  11  is provided so that the light transmission-use aperture  13   a  is shielded, and the returned light is reflected by the rear surface mirror of the LED  11 , thereby improving exploiting efficiency of the returned light.  
         [0043]      FIG. 3  is a descriptive diagram showing an illuminating device constructed of the LED  11  and an optical member  12 B. The optical member  12 B is constructed of the rod integrator  15 , and a reflection member  13 A and a ¼λ plate  14 A provided on the light entrance surface side of the rod integrator  15 . The reflection member  13 A and the ¼λ plate  14 A are located separate from the light entrance surface of the rod integrator  15 , and are concave in shape (a concave curved surface in shape, or a concave polyhedral surface in shape). In this embodiment, the ¼λ plate  14 A is formed in an area half the reflection member  13 A (the area which corresponds to a half the circumference of the reflection member  13 A). The reflection member  13 A is formed with a light transmission-use aperture  13 Aa. The light emission portion of the LED  11  is arranged in the light transmission-use aperture  13 Aa. As the reflection member  13 A, a parabolic reflector can be used, for example. The ¼λ plate  14 A may be adhered to the reflection surface of the parabolic reflector. It is noted that instead of the concave ¼λ plate  14 A, a plane ¼λ plate  14  may be disposed on the light entrance surface of the rod integrator  15 .  
         [0044]      FIG. 4  is a descriptive diagram showing a projection type video display apparatus  4 B. An illuminating device of the projection type video display apparatus  4 B is constructed of a light source  10  and the optical member  12 A. The light source  10  is constructed of a lamp such as an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp, etc., and an elliptic reflector for converging irradiating light of the lamps. It is noted that instead of using the elliptic reflector, the light source  10  may be provided with a parabolic reflector for collimating the irradiating light, and a lens for converging the collimated light from this parabolic reflector. The converging position of the light emitted from the light source  10  corresponds to the forming position of the light transmission-use aperture  13   a.  On the light exit side of the optical member  12 A, a full-color, transmissive liquid crystal display panel  1 F and a projection lens  3  are provided. In such the configuration, too, it is possible to prevent the light re-incident upon the reflective polarizer  16  from becoming the linearly polarized light having an undesired polarization direction.  
         [0045]      FIG. 5  is a descriptive diagram showing a projection type video display apparatus  4 C. An illuminating device of the projection type video display apparatus  4 C is constructed of the light source  10  and an optical member  12 C. The optical member  12 C, which has structure approximately similar to that of the optical member  12 A, is different from the optical member  12 A in that an aperture  14   a  is formed in the ¼λ plate  14 . The forming position of the aperture  14   a  corresponds to that of the light transmission-use aperture  13   a.  It is noted that in a case of guiding from an oblique direction the light from the light source  10  to the light transmission-use aperture  13   a,  the aperture  14   a  may be formed to be slightly displaced from the light transmission-use aperture  13   a.  In addition, in a case of providing a plurality of light sources  10  and a case of guiding from the oblique direction the light from each light source  10  to the light transmission-use aperture  13   a,  the aperture  14   a  may be larger in some degree than the light transmission-use aperture  13   a.  On the light exit side of the optical member  12 C, the full-color, transmissive liquid crystal display panel  1 F and the projection lens  3  are provided.  
         [0046]     It is noted that in the configurations shown in  FIGS. 4 and 5 , instead of the light source  10 , an LED for emitting white light may be provided. The LED is disposed in the light transmission-use aperture  13   a.  Furthermore, in a case that the LED includes the LED rear surface mirror, exploiting efficiency of the returned light is improved.  
         [0047]     In addition, in the configuration shown in  FIG. 3 , the light source  10  may be provided instead of the LED  11 . In this configuration, the light from the light source  10  is converged toward the light transmission-use aperture  13 Aa, and thereafter, diverged and guided to the light entrance surface of the rod integrator  15 . In addition, in such the configuration, the plane ¼λ plate  14  may be disposed on the light entrance surface. In this case, the light diverged via the light transmission-use aperture  13 Aa is irradiated onto the plane ¼λ plate  14 , thereby almost eliminating adverse effect caused by the light from the light source  10  onto the plane ¼λ plate  14 .  
         [0048]     Illuminating devices shown in FIGS.  6  to  8  are configuration examples without the reflection member  13  ( 13 A) having a light transmission-use aperture. In these configurations, the reflection surface with which the light source by itself is formed is used for reflecting the returned light, and the illuminating devices are not provided with the light transmission-use aperture. This improves the exploiting efficiency of the returned light. Regarding polarization conversion, although it is desirable to adopt a configuration capable of preventing the light re-incident upon the reflective polarizer  16  from becoming the linearly polarized light having an undesired polarization direction, it is not necessary to adopt such the configuration.  
         [0049]      FIG. 6A  is a descriptive diagram showing an illuminating device constructed of a light source  10 A and an optical member  12 D. The light source  10 A includes a lamp and a parabolic reflector  13 B, and is formed with a ¼λ plate  14 B adhered to the reflection surface of the parabolic reflector  13 B. A light emitting element of the light source  10 A is not limited to a lamp, and may be a solid light emitting element. The parabolic reflector  13 B and the ¼λ plate  14 B do not have the light transmission-use aperture. The optical member  12 D is provided with the reflective polarizer  16  on the light exit surface of the rod integrator  15 . The light source  10 A is disposed so that the light emission aperture thereof faces the light entrance surface of the rod integrator  15 . The shape of the light emission aperture may be equal to or approximately equal to that of the light entrance surface of the rod integrator  15 . It is noted that as shown in  FIG. 6B , it may be possible to use an optical member  12 E in which the plane ¼λ plate  14 , instead of the above ¼λ plate  14 A, is disposed on the light entrance surface of the rod integrator  15 . In addition, as shown in  FIG. 6C , it may be possible to use an optical member  12 F in which the plane ¼λ plate  14  is disposed between the reflective polarizer  16  and the light exit surface of the rod integrator  15 .  
         [0050]      FIG. 7A  is a descriptive diagram showing an illuminating device constructed of the LED  11  and the optical member  12 E. The size of the light exit surface of the LED  11  (size of the LED rear surface mirror) is the same or approximately the same as (dimensional approximation of 90 percent or more, for example) that of the light entrance surface of the rod integrator  15 , and all or almost all of the light entrance surface of the rod integrator  15  is covered with the LED rear surface mirror. If the shape of the light entrance surface of the rod integrator  15  is quadrangle, that of the light exit surface of the LED  11 , too, may be quadrangle.  
         [0051]      FIG. 7B  shows a descriptive diagram showing an illuminating device constructed of the LED  11  and the optical member  12 F. The size of the light exit surface of the LED  11  (size of the LED rear surface mirror) is the same or approximately the same as (dimensional approximation of 90 percent or more, for example) that of the light entrance surface of the rod integrator  15 , and all or almost all of the light entrance surface of the rod integrator  15  is covered with the LED rear surface mirror. If the shape of the light entrance surface of the rod integrator  15  is quadrangle, that of the light exit surface of the LED  11 , too, may be quadrangle.  
         [0052]      FIG. 8A  is a descriptive diagram showing an illuminating device constructed of the two LEDs  11  and an optical member  12 G. The optical member  12 G is provided with the tapered rod integrator  15 A of which light exit surface is larger than the light entrance surface. On the light exit surface of the rod integrator  15 A, the reflective polarizer  16  is arranged. The two LEDs  11 ,  11  have the primary optical axes perpendicular to the center axis of the rod integrator  15 A, and are disposed adjacent to the light entrance surface of the rod integrator  15 A. On the light emission side of each LED  11 , a ¼λ plate  14 C is disposed. The returned light that exits from the light entrance surface of the rod integrator  15 A is reflected by each of mirrors  17 , and passes through the ¼λ plate  14 C. This is followed by being reflected by the LED rear surface mirror of the LED  11 . The resultant light passes through the ¼λ plate  14 C once again. Thereafter, the resultant light is reflected by the mirror  17 , and is incident upon the light entrance surface of the rod integrator  15 A.  
         [0053]      FIG. 8B  is a descriptive diagram showing an illuminating device constructed of the two LEDs  11  and an optical member  12 H. The optical member  12 H is provided with the tapered rod integrator  15 A of which light exit surface is larger than the light entrance surface. On the light exit surface of the rod integrator  15 A, the reflective polarizer  16  is disposed. The two LEDs  11 ,  11  have the primary optical axes perpendicular to the center axis of the rod integrator  15 A, and are disposed adjacent to the light entrance surface of the rod integrator  15 A. Each light emitted from the two LEDs  11 ,  11  is reflected by each of the mirrors  17 , and guided to the light entrance surface of the rod integrator  15 A. The returned light that exits from the light entrance surface of the rod integrator  15 A is reflected in the order of the mirror  17 , the LED rear surface mirror of the LED  11 , and the mirror  17 , and is incident upon the light entrance surface of the rod integrator  15 A. Thereafter, the resultant light reaches the ¼λ plate  14 .  
         [0054]     In these configurations in  FIGS. 8A and 8B , it is possible to adopt a configuration in which a larger number of LEDs are provided.  
         [0055]     In addition, an illuminating device X may be adopted. This illuminating device is provided with the illuminating devices ( 51 R,  51 G and  51 B) for emitting light of each color, shown in  FIG. 1 , in which the light of each color (red light, blue light, and green light) from these illuminating devices are guided by a cross dichroic prism or a cross dichroic mirror in the same direction, for example. An illuminating device configured as such can be adopted. Needless to say, another illuminating device or optical member of the present invention may be used for the illuminating device for each color. A liquid crystal display panel used in the projection type video display apparatus using the illuminating device for guiding the light of each color in the same direction has structure with RGB color filters, or has structure without the RGB color filters. In a case of using the liquid crystal display panel of the structure with the RGB color filters, all illuminating devices are simultaneously illuminated, and white light is guided to the liquid crystal display panel. In a case of using the liquid crystal display panel of the structure without the RGB color filters, each illuminating device is illuminated in a time-sequential manner for a predetermined time period, and in synchronization of timing of illuminating for the predetermined time period, a video signal of each color is applied to the liquid crystal display panel.  
         [0056]      FIG. 9  is a descriptive diagram showing a three-panel projection type video display apparatus  4 D. The projection type video display apparatus  4 D is provided with, for example, the optical member  12 C and the light source  10  shown in  FIG. 5 . Needless to say, instead of the optical member  12 C and the light source  10 , the projection type video display apparatus  4 D may be provided with another illuminating device or optical member of the present invention. White light emitted from the light source  10  is incident upon the optical member  12 C, and the polarization direction of the white light is directed in a common direction, thereby the white light is optically integrated. Thereafter, the white light exits from the optical member  12 C. The white light that exits from the optical member  12 C is guided to a first dichroic mirror  68 . The first dichroic mirror  68  transmits light in a red wavelength band, and reflects light in a cyan (green+blue) wavelength band. The light in a red wavelength band passing through the first dichroic mirror  68  is reflected by a reflection mirror  69 , thereby the optical path of the light is changed. The red light reflected by the reflection mirror  69  passes through a transmissive liquid crystal display panel  81  for red light via a condenser lens  70 , thereby the red light is optically modulated. On the other hand, the light in a cyan wavelength band reflected by the first dichroic mirror  68  is guided to a second dichroic mirror  71 .  
         [0057]     The second dichroic mirror  71  transmits the light in a blue wavelength band, and reflects the light in a green wavelength band. The light in a green wavelength band reflected by the second dichroic mirror  71  is guided to a transmissive liquid crystal display panel  82  for green light via a condenser lens  72 . As a result of passing therethrough, the light is optically modulated. In addition, the light in a blue wavelength band passing through the second dichroic mirror  71  is guided to a transmissive liquid crystal display panel  83  for blue light via reflection mirrors  74 ,  76 , relay lenses  73 ,  75 , and a condenser lens  77 . As a result of passing through the transmissive liquid crystal display panel  83 , the light is optically modulated.  
         [0058]     The respective liquid crystal display panel  81 ,  82 , and  83  are constructed of incidence side polarizers  81   a ,  82   a,  and  83   a,  panel portions  81   b,    82   b,  and  83   b  formed by sealing liquid crystal between one pair of glass plates (on which pixel electrodes and alignment films are formed), and light emission side polarizers  81   c,    82   c,  and  83   c.  Each modulated light (image light of each color) modulated via the liquid crystal display panels  81 ,  82 , and  83  is mixed by a cross dichroic prism  78 , thereby the resultant light becomes color image light. The color image light is projected by a projection lens  79 , and displayed on a screen.  
         [0059]     In the above descriptions, although the projection type video display apparatus (rear projection type or front projection type) uses the transmissive liquid crystal display panel, this is not always the case. A reflective liquid crystal display panel may be used. In addition, instead of these liquid crystal display panels, a display panel for individually driving a multiple of micro mirrors serving as dots may be used.  
         [0060]     In addition, in the illuminating devices described above, a projection-use curved surface mirror may be used instead of the projection lens. Furthermore, as the solid light emitting element, besides the LED, an organic or inorganic EL (electroluminescence), etc., may be used.  
         [0061]     Although the present invention has been described in detail by the use of illustration, the present invention is merely described by the use of Figures and examples, and thus, it is obvious that the present invention is not limited thereto. The spirit and the scope of the present invention are limited only by the terms in the attached claims.