JP4049990B2 - Projector and polarization converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projector such as a liquid crystal projector using an image forming member such as a reflective liquid crystal panel, and a polarization converter suitable for application to the projector.
[0002]
[Prior art]
In general, there are various types of projectors. For example, it is easier to achieve higher resolution and higher brightness by using a reflective liquid crystal panel than a method using a transmissive liquid crystal panel. Since a single color optical element can be used as a color synthesizing element, it is advantageous for downsizing and has attracted attention.
[0003]
The basic idea of a projector using such a reflective liquid crystal panel is disclosed in, for example, Japanese Patent Application Laid-Open Nos. Hei 3-249639 and 2000-131664, and is disposed on an incident / exit optical path. Using a polarizing beam splitter and a dichroic mirror as a color separation / color synthesis element, color separation of the light from the light source and color synthesis of the modulated light reflected by the reflective liquid crystal panel for each color are performed, and a projection lens system The projection color image is obtained by making it incident on.
[0004]
FIG. 21 shows a proposal example of a basic idea of an optical element related to polarization separation and RGB separation / combination of a liquid crystal projector using such a reflective liquid crystal panel. This optical element includes a PBS (polarizing beam splitter) 100 and a dichroic prism 101 as a color separation / color combination element, and is combined with three reflective LCDs 102R, 102G, and 102B.
[0005]
The PBS 100 is disposed on overlapping input / output light paths, and includes a polarization beam splitter film 100a that reflects S-polarized component light irradiated as illumination light from the illumination optical system by 90 ° toward the color separation / color combination element 102 side. It is what you have. The dichroic prism 101 is a red dichroic having an R reflection high-pass filter characteristic that reflects the long wavelength region of the red light R so as to separate the long wavelength region corresponding to the red R region and the shorter wavelength region than the green G region. A blue dichroic film 101b having a B reflection low-pass filter characteristic for reflecting the short wavelength band of the blue light B so as to separate the short wavelength band of the blue light B from the long wavelength band of the green light G; Are configured as a cubic or rectangular parallelepiped optical element. Accordingly, the dichroic prism 101 is formed with a red dichroic film 101r parallel to the PBS film 100a of the PBS 100 and a blue dichroic film 101b orthogonal to the red dichroic film 101r. These dichroic films 101r and 101b are formed as dielectric multilayer films.
[0006]
The three reflective LCDs 102R, 102G, and 102B are arranged corresponding to the red dichroic film 101r and the blue dichroic film 101b of the dichroic prism 101, respectively. That is, the reflective LCD 102R is arranged in the reflection direction of the long wavelength longer than the red light R reflected by the red dichroic film 101r, and the reflection direction of the shorter wavelength less than the blue light B reflected by the blue dichroic film 101b. The reflective LCD 102B is disposed, and the reflective LCD 102G is disposed in the transmission direction of the red dichroic film 101r and the blue dichroic film 101b. In these reflective LCDs 102R, 102G, and 102B, although not shown, an image for each color to be projected by the information display system is formed by on / off control of each liquid crystal element.
[0007]
Further, a projection lens system (not shown) provided with a projection lens is provided on the outgoing optical path of the image modulated light between the PBS 100 and the screen (not shown).
[0008]
In such a configuration, the illumination light aligned only with the S-polarized component from the illumination system is reflected by the PBS 100 and enters the dichroic prism 101. Here, the light is split into red light R, green light G, and blue light B according to the wavelength, and is incident on the corresponding reflective LCDs 102R, 102G, and 102B. Here, each of the reflective LCDs 102R, 102G, and 102B is turned on / off in accordance with an image signal input to the liquid crystal projector by the information display system, reflects the S-polarized component as the S-polarized component when turned off, and S-polarized when turned on. The component is converted (modulated) into a P-polarized component and reflected. Then, the reflected light from each of the reflective LCDs 102R, 102G, and 102B composed of these S-polarized components or P-polarized components is combined and synthesized by the dichroic prism 101 and recursed to the PBS 100. At this time, since only the P-polarized light component reflected from the liquid crystal element corresponding part turned on in each of the reflective LCDs 102R, 102G, and 102B passes through the PBS 100, the transmitted light is image-modulated light on the screen by the projection lens system. Magnified projection. Thus, an image corresponding to the image signal input to the liquid crystal projector is displayed on the screen as a color image.
[0009]
In this way, by combining color separation and color synthesis with one dichroic prism 101, the overall configuration can be reduced in size.
[0010]
Optical technology for three-plate LCOS projectors (b) Color shutter system: According to the Nikkei Microdevices August 2000 issue pp184, "Liquid crystal rear projection TV is made cheap" A compact combination of color shutter and PBS LCD projectors are provided. Here, “color shutter” means a color polarizing filter element called “Color Select”, a product name of ColorLink.
SID99.pdf-Publication date: 04/1999 Retarder Stack Technology for Color Manipulation A technology for manipulating color is presented which using polarization, rather than thin-film interference or absorption effects.Retarder stack technology produces high performance filtering, color separation / combining, These structures are light efficient and provide saturated colors when used in sequential and subtractive (stacked-panel) display modes.
This color manipulation technique is a technique that utilizes polarization rather than the use of thin film interference or absorption effects. Delay film stacking technology provides highly efficient filtering, color separation and synthesis, and color polarization control operations. Such a configuration reduces the effect of light when used in a display mode that is attenuating sequentially (multilayer panel).
Draw out and provide a state full of colors.
As reported.
[0011]
[Problems to be solved by the invention]
However, according to such a conventional technique, even when S-polarized light is used as illumination light, the polarization purity is not 100%, or depolarization occurs when passing through the dichroic prism 101, and reaches the PBS film 100a. The actual condition is that the light to be transmitted is not purely polarized light. On the other hand, since the splitting ability of the P-polarized light and the S-polarized light of the PBS 100 is not 100%, only a single polarized light is not incident on the dichroic prism 101.
[0012]
Further, the dichroic prism 101 reflects the band of the blue light B as described above, reflects the band of the dichroic film 101b and the red light R that transmits the band less than that (the band of the green light G and the red light R), The dichroic film 101r that transmits a band exceeding that (the band of green light G and blue light B) has a prism configuration in which two dichroic films having different characteristics are crossed. Thereby, the light of each band of LCD102R, 102G, 102B controlled by the signal of R, G, B is irradiated. However, each of the dichroic films 101b and 101r cannot be completely separated into the light of the targeted band. For example, the dichroic film 101b reflects a little red light R to be transmitted. Similarly, even the dichroic film 101r reflects a small amount of blue light B to be transmitted.
[0013]
For this reason, the light ray L1 in FIG. 21 represents P-polarized light mixed with S-polarized light reflected by the PBS 100. When the light beam L1 reaches the dichroic film 101b, almost all of the band less than the blue light B band is transmitted, but a small amount of light of the red light R band is reflected and reaches the dichroic film 101r. The light of the red light R band is almost entirely reflected there and proceeds in the direction of the PBS film 100a. Since this light is P-polarized light, it almost passes through the PBS film 100a and reaches the screen through the projection lens. This phenomenon is the same for the light ray L2. These lights are mixed with the light modulated by the original LCDs 102R, 102G, and 102B, but are not modulated by the LCDs 102R, 102G, and 102B and have a certain amount of illumination light. Therefore, flare light is generated and the contrast of the image on the screen is lowered.
[0014]
Also, according to the latter liquid crystal projector using a color shutter called “color select”, there is no such problem, but the prism is used twice as compared with the former configuration, which makes the apparatus heavy. Become.
[0015]
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a projector and a polarization converter that can eliminate flare light and improve the image contrast on the screen without requiring a complicated configuration that makes the apparatus heavy. .
[0016]
[Means for Solving the Problems]
  The projector according to claim 1 is an illumination optical system including a light source that emits illumination light;A polarizing beam splitter film that separates P-polarized component light and S-polarized component light; a pair of polarizing beam splitter prisms including the polarizing beam splitter film; and a reflected light exit surface of the polarizing beam splitter prism, A first polarization characteristic having a characteristic of converting any one of the red band, green band, and blue band light of the S polarization component light separated by the beam splitter film into P polarization component light A filter, a prism having a total reflection surface provided on the first polarization characteristic filter output side, and an output surface of the prism from which the light totally reflected by the total reflection surface is output, the first polarization A half-wave plate for converting the polarization direction of light of three bands passing through the characteristic filter, and an exit surface from which the transmitted light of the polarization beam splitter prism exits. Second polarized light having a characteristic of converting one band out of three bands of the red band, the green band, and the blue band with respect to the P-polarized component light separated by the polarizing beam splitter film into S-polarized component light A polarization converter having a characteristic filter (hereinafter, the first and second polarization characteristic filters are collectively referred to simply as a polarization characteristic filter), and an illumination optical system,
SaidPolarization converterA polarization separation element that separates the P-polarized component light and the S-polarized component light that have passed through
A dichroic element having a dichroic film that separates polarization component light including two bands out of the polarization component light separated by the polarization separation element into each band component light;
Three reflections that form an image to be projected by modulating the polarization state for each of the three light bands of the red band, the green band, and the blue band separated into three bands by the polarization separation element and the dichroic film. A mold image forming member;
A projection lens system that projects an image formed by these image forming members on a screen;
Is provided.
[0017]
  Therefore,By placing a polarization converter in the illumination optical system of a projector such as a liquid crystal projector,The light in the three bands of the color band, the green band, and the blue band is converted into light having different polarization states in the second band and the first band, and is polarized and separated by the polarization separation element depending on the polarization state, and separated by the polarization separation element. Since polarization component light including two bands is band-separated by a dichroic film, it is not necessary to adopt a complicated configuration in which dichroic films that simultaneously separate three bands are crossed. With a simple configuration using a dichroic film, light in the three bands of the red band, the green band, and the blue band can be separated, and the problem of flare light can be solved to obtain a projected image with high contrast.
According to a second aspect of the present invention, there is provided a light source that emits illumination light, a pair of polarizing beam splitter prisms including a polarizing beam splitter film that separates P-polarized component light and S-polarized component light, and reflected light of the polarizing beam splitter prism S-polarized component light provided on the exit surface and separated by the polarizing beam splitter filmTheA half-wave plate for converting into P-polarized component light, a prism provided on the transmission side of the half-wave plate, having a total reflection surface, and an exit surface of the prism from which light totally reflected by the total reflection surface is emitted; , Which are provided in common to the exit surface from which the P-polarized component light transmitted through the polarizing beam splitter film is emitted, and are for three bands of the red band, the green band and the blue band relating to the P-polarized component light emitted from the respective exit surfaces. A polarization converter provided with a polarization characteristic filter having a characteristic of converting any one of the light beams into S-polarized component light, and an illumination optical system having
A polarization separation element that separates the P-polarized component light and the S-polarized component light that have passed through the polarization converter;
A dichroic element having a dichroic film that separates polarization component light including two bands out of the polarization component light separated by the polarization separation element into each band component light;
Three reflections that form an image to be projected by modulating the polarization state for each of the three light bands of the red band, the green band, and the blue band separated into three bands by the polarization separation element and the dichroic film. A mold image forming member;
A projection lens system that projects an image formed by these image forming members on a screen;
Is provided.
Therefore, similarly to the first aspect, a projected image with high contrast can be obtained.
[0018]
  Claim 3The invention described in claim 1Or 2In the projector described above, the polarization characteristic filter, the polarization separation element, and the dichroic element are integrally provided.
[0019]
Therefore, in the existing projector, the intended purpose can be easily achieved by replacing the separation portion of each color component light with this integrated optical device.
[0022]
  According to a fourth aspect of the present invention, in the projector according to the third aspect,The S-polarized component light emitted from the polarization converter isGreen bandageThe dichroic film has a characteristic of separating the blue band and the red band of the same polarization component light.
[0023]
Therefore, an example of a specific example for realizing the invention of claim 3 is presented. In particular, due to its band characteristics, the light use efficiency between the illumination light and the modulated image light can be reduced. Can provide no projector.
[0024]
  The invention according to claim 5 is the projector according to claim 3,The S-polarized component light emitted from the polarization converter isRed bandage,The dichroic film has a property of separating the blue band and the green band of the same polarization component light.
[0025]
Therefore, an example of a specific example for realizing the invention of claim 3 is presented.
[0026]
  The invention described in claim 6 is the projector according to claim 3,The S-polarized component light emitted from the polarization converter isBlue bandage,The dichroic film has a characteristic of separating the green band and the red band of the same polarization component light.
[0027]
Therefore, an example of a specific example for realizing the invention of claim 3 is presented.
[0036]
  Claim 7The described inventionClaim 4In the projector described above, the light source is a xenon lamp.
[0037]
  Therefore,Claim 4In realizing the invention described above, it is preferable to use a xenon lamp as the light source because the entire visible light region has a substantially flat spectral distribution characteristic.
[0038]
  Claim 8The described inventionClaim 5In the projector described above, the light source is a high-pressure mercury lamp.
[0039]
  Therefore,Claim 5When the high-pressure mercury lamp is used as a light source in realizing the invention described above, it has a light emission characteristic that has a large amount of light in the blue B band and a peak in the vicinity of the green G band but a small amount of light in the red R band. Become.
[0040]
  Claim 9The described inventionClaim 6In the projector described above, the light source is an LED or a halogen lamp.
[0041]
  Therefore,Claim 6In realizing the invention described above, it is preferable to use an LED or a halogen lamp as the light source because the light emission efficiency of the red R, green G, and blue B gradually decreases.
[0042]
  Claim 10The invention described in claims 4 and 5Or 6In the projector described above, the light source is a metal halide lamp.
[0043]
  Accordingly, claims 4 and 5Or 6In realizing the described invention, if a metal halide lamp is used as the light source, the spectral distribution can be controlled to some extent by the molecules to be enclosed, and therefore, it is suitable for any type.
[0044]
  Claim 11The invention described in claim 110In the projector according to any one of the above, the dichroic film has a main optical axis of the illumination light.OrthogonalIt is formed at 45 ° or less with respect to the surface.
[0045]
  Therefore, the main optical axis of the illumination lightOrthogonal planeBy making the angle of the dichroic film with respect to as small as possible, the separation characteristics for two bands in the dichroic film can be further improved.
[0046]
  Claim 12The described inventionClaim 11In the projector described above, an air gap that totally reflects the light component reflected by the dichroic film is provided between the polarization separating element and the dichroic element.
[0047]
  Therefore, by using total reflection by the air gapClaim 11The described invention can be easily realized.
[0048]
  Claim 13The described inventionClaim 11In the projector described above, the polarized light separating element and the dichroic element are bonded by an adhesive having an optical density substantially equal to the material of the polarized light separating element.
[0049]
  Therefore, by adopting a configuration in which the polarization separation element and the dichroic element are bonded with an adhesive having an optical density substantially equal to the material of the polarization separation element.Claim 11The described invention can be easily realized.
[0050]
  Claim 14The invention described in claim 1ThirteenIn the projector according to any one of the above, an output-side polarization characteristic filter having the same characteristics as the polarization characteristic filter is provided on the output optical path with respect to the projection lens system.
[0051]
Therefore, the polarization direction of the modulated image light can be made uniform by using the output side polarization characteristic filter, which is suitable for projecting onto a screen using the polarization characteristic.
[0052]
  Claim 15The described inventionClaim 14In the projector described above, a polarizing plate is provided on the output side of the output side polarization characteristic filter.
[0053]
Therefore, by using the polarizing plate, it is possible to cut even when polarization is disturbed in the middle of the optical path, so that the contrast on the screen can be further improved.
[0058]
DETAILED DESCRIPTION OF THE INVENTION
  The present inventionFirst configuration example of the main part of the projection device to whichWill be described with reference to FIGS.This descriptionFIG. 1 is a plan view showing a configuration example of an optical device as a main part.
[0059]
The optical device 1 generally includes a rectangular plate-shaped polarization characteristic filter 2 disposed on an incident light path of S-polarized illumination light from a light source or the like, and the polarization characteristic filter 2 integrated with an incident surface. A cubic PBS prism 3 as a polarized light separating element, and a cubic dichroic prism 4 as a dichroic element integrated with the PBS prism 3 in the reflection direction by the PBS film 3a; The output side polarization characteristic filter 5 is integrated with the output surface of the PBS prism 3. The dichroic prism 4 has a dichroic film 4a parallel to the PBS film 3a. Here, the optical characteristics of the polarization characteristic filter 2, the PBS prism 3, and the dichroic prism 4 will be described later. In accordance with the characteristics, an image forming member for the green band is used at the position where the transmitted light of the PBS prism 3 is received. A reflective LCD 6G is disposed, a reflective LCD 6R, which is an image forming member for the red band, is disposed at a position where the transmitted light from the dichroic film 4a is received, and a blue color is disposed at a position where the reflected light from the dichroic film 4a is received. A reflective LCD 6B, which is a band image forming member, is provided. In addition, a color filter 7 is provided on the front surface of the reflective LCDs 6R, 6G, and 6B to make the color characteristics that vary due to variations in the characteristics of the PBS prism 3 and the dichroic prism 4 that vary widely and to obtain a predetermined color balance. Has been. The reflective LCD 6G located at the transmission position of the PBS prism 3 is disposed away from the PBS prism 3 so that the optical path lengths from the projection lens to the reflective LCDs 6R, 6G, 6B are equal.
[0060]
In addition, although not particularly shown in FIG. 1, an illumination optical system including a light source is disposed on the incident side with respect to the polarization characteristic filter 2, and image modulated light is placed on the screen on the emission side from the emission side polarization characteristic filter 5. A projection lens system for projecting is provided.
[0061]
  here,Used in the present inventionThe polarization characteristic filter 2 will be described. As described above, the polarization characteristic filter 2 is an optical component sold by ColorLink under the trade name: Color Select, and has a polarization conversion function of a curve as shown in FIG. In the characteristic 1 curve shown in the figure, when all visible light is incident as S-polarized light, a short wavelength of about 490 nm or more and a long wavelength of about 605 nm or less are transmitted as they are with S-polarized light, and about 510 to 565 nm. Is converted to P-polarized light and transmitted. The wavelengths of 490 to 510 nm and 565 to 605 nm are converted into P-polarized light at a ratio as shown in the figure. That is, only the polarization component light for the green band is converted into P polarization component light, and the polarization component light for the blue band and the red band is emitted as it is as the polarization component light.
[0062]
However, here, an example of incidence of S-polarized light has been described. However, if all visible light is incident as P-polarized light, it is transmitted with characteristics opposite to those of S-polarized light. The curve of the characteristic 2 is shown in the opposite view to the characteristic 1 for reference.
[0063]
Incidentally, in both the characteristic 1 and characteristic 2 shown in FIG. 2, the saturated portion of the conversion rate is not 1.0 and is about 0.87 to 0.95, but this is AR coating (interfacial reflection prevention). This is because the measurement result is for a member that is not. That is, this characteristic is conversion efficiency + transmission efficiency. It is obvious that by performing the AR coating, characteristics of 0.99 or more can be obtained in the entire band.
[0064]
The output side polarization characteristic filter 5 has the same characteristics as the polarization characteristic filter 2.
[0065]
The PBS film 3a of the PBS prism 3 has a wide band (about 430 to 670 nm), reflects S-polarized light, and transmits P-polarized light. However, S-polarized light has a reflectance of about 99%, while P-polarized light has a transmittance of about 90%.
[0066]
As shown in FIG. 3, the dichroic film 4a of the dichroic prism 4 has a characteristic of reflecting a short wavelength of about 520 nm for S-polarized light and about 560 nm for P-polarized light and transmitting light below that. That is, the dichroic film 4a has a characteristic capable of separating the blue band and the red band by transmission and reflection.
[0067]
In such a configuration, a process until light in each band of R, G, and B is modulated will be individually described with reference to FIG.
[0068]
First, the process of modulating the light component for the green G band will be described. The illumination light from the light source is assumed to be S-polarized over the entire visible light band. The illumination light as S-polarized light is converted into P-polarized light for the green G band by the polarization characteristic filter 2, and the blue B band and red R band are transmitted as S-polarized light. Next, these light fluxes that have reached the PBS film 3a are transmitted through the green G band and reflected by the blue B band and the red R band, so here the green G band and the blue B and red R bands are reflected. Minutes are polarized and separated. The green G band travels straight, reaches the LCD 6G that is responsible for the modulation of the green G band, reflects off the P-polarized light at the OFF signal pixel, and converts it to S-polarized light at the ON signal pixel. These modulated light beams are returned to the PBS film 3a again. Here, the P-polarized light is transmitted and returned to the direction of the light source, while the S-polarized light is reflected and travels toward the screen as image modulated light.
[0069]
In the middle, an exit-side polarization characteristic filter 5 is provided on the exit surface side of the PBS prism 3, and after S-polarized light is converted to P-polarized light, it goes to the screen through the projection lens system. Since the output side polarization characteristic filter 5 is exactly the same as the polarization characteristic filter 2, the polarized light for only the green G band is converted, and the modulated P polarized light for the blue B band and red R band, which will be described later, is converted. The light is transmitted as it is with P-polarized light. As a result, the entire visible light band is directed toward the screen with P polarization. By inserting the output side polarization characteristic filter 5, a good image can be obtained even if it is projected on a screen using the polarization characteristic. However, when using a screen with simple diffusivity, it is not always necessary to include the output side polarization characteristic filter 5. In this case, the green G band is projected onto the screen as S-polarized light, the blue B band and red R band are projected as P-polarized light.
[0070]
Next, the process of modulating the light flux for the blue B band will be described. The illumination light as described above reaches the PBS film 3a, and the light of blue B and red R bands reflected by the PBS film 3a while being S-polarized is about 560 nm or more by the dichroic film 3a of the dichroic prism 4. The short wavelength of the band (however, the wavelength in the blue B band is substantially not reflected since the light in the band of about 500 to 590 nm is not coming) is reflected and reaches the LCD 6B that is responsible for the modulation of the light in the blue B band. In the OFF signal pixel, the S-polarized light is reflected as it is, and in the ON signal pixel, it is converted into the P-polarized light and reflected. These modulated light fluxes are returned to the dichroic film 4a again, but short wavelengths of 520 nm or more are directed to the PBS film 3a. At this time, the P-polarized light of the ON signal is transmitted, and the S-polarized light of the OFF signal is reflected and returned to the direction of the light source. The light transmitted through the PBS film 3a passes through the output-side polarization characteristic filter 5, but this band passes through the projection lens without being subjected to polarization conversion and is projected onto the screen.
[0071]
The process of modulating the light beam for the red R band will be described. As described above, the S-polarized illumination light reaches the PBS film 3 a, and the blue B and red R band light reflected by the PBS film 3 a while being S-polarized is approximately about dichroic film 4 a of the dichroic prism 4. A long wavelength in a band of 560 nm or less (however, light in a band of approximately 500 to 590 nm is not transmitted, so a wavelength corresponding to a red R band is transmitted) is transmitted to an LCD 6R that is responsible for modulation of light in a red R band. In the pixel of the OFF signal, it is reflected as S-polarized light, and in the pixel of the ON signal, it is converted to P-polarized light and reflected. These modulated light fluxes are returned to the dichroic film 4a again, but long wavelengths of 520 nm or less are directed to the PBS film 3a. At this time, the P-polarized light of the ON signal is transmitted, and the S-polarized light of the OFF signal is reflected and returned to the direction of the light source. The light transmitted through the PBS film 3a passes through the output-side polarization characteristic filter 5, but this band passes through the projection lens without being subjected to polarization conversion, and is projected onto the screen.
[0072]
  So bookOptical deviceAccording to the above, despite the simple configuration, the band of each color of R, G, B is separated by the combination of the single PBS film 3a and the dichroic film 4a without using two kinds of dichroic films in the cross. In addition, flare light can be suppressed and an image with high contrast can be obtained.
[0073]
Note that the characteristic of the dichroic film 4a of the dichroic prism 4 may be opposite to that shown in FIG. That is, it is possible to create a characteristic that transmits a short wavelength of about 520 nm for S-polarized light and about 560 nm or more for P-polarized light, and reflects it at a wavelength shorter than that, depending on the design. When such a dichroic prism is used, the positions of the LCD 6B that modulates the blue B band and the LCD 6R that modulates the red R band may be switched.
[0074]
Furthermore, similar characteristics can be obtained even if a dichroic prism having a dichroic film whose characteristics are shifted to the blue B band side or the red R band side as shown in FIGS. 6 and 9 to be described later. Is self-explanatory.
[0075]
  The present inventionSecond configuration example of applied optical deviceWill be described with reference to FIGS. The aboveFirst configuration exampleParts that are the same as or correspond to the parts indicated by are denoted by the same reference numerals, and description thereof is also omitted (hereinafter referred to asDescription of figureHowever, the same shall apply sequentially).
[0076]
  BookConfiguration exampleIs structurally the same as that shown in FIG. 1, but the optical characteristics of the polarization characteristic filter 2 and the dichroic film 4a are different from those in FIG. 1, and the reflective LCDs 6R, 6G, 6B are correspondingly corresponding thereto. The placement of has been changed.
[0077]
  First, bookConfiguration exampleAs shown in FIG. 5, the polarization conversion characteristic of the polarization characteristic filter 2 in FIG. 5 is set so that a short wavelength of about 580 nm or more is transmitted as it is, and a long wavelength of about 605 nm or less is inverted. The other characteristics and features are the same as in FIG. 2 except that the polarization inversion band is different. That is, only the polarization component light for the red R band is converted into P polarization component light, and the polarization component light for the blue B band and the green G band is emitted as it is as polarization component light.
[0078]
  Also bookConfiguration exampleAs shown in FIG. 6, the dichroic film 4a of the dichroic prism 4 is set so that a short wavelength of about 520 nm or more is reflected by S-polarized light and a wavelength of about 490 nm or more is reflected by P-polarized light, and a wavelength shorter than that is transmitted. Yes. That is, the dichroic film 4a has a characteristic capable of separating the blue band and the green band by transmission and reflection.
[0079]
  The outline of the operation in such a configuration will be described. BookConfiguration exampleHowever, the S-polarized light is used as the illumination light, and after passing through the polarization characteristic filter 2, this illumination light travels straight through the PBS film 3a for the red R band, and the reflective LCD 6R for modulating the red R band. Then, the signal is modulated and returned to the PBS film 3a again, the signal is reflected there, and an image for the red R band is projected onto the screen through the projection lens. The illumination light is reflected by the PBS film 3a for green G and blue B bands, the blue dichroic film 4a of the dichroic prism 4 is reflected by the blue B band, and is modulated by the reflective LCD 6B for modulating the blue B band. In response, the light is returned to the dichroic film 4a and reflected. Since the signal component is P-polarized light, it passes through the PBS film 3a, and the image for the blue B band is projected on the screen through the projection lens. Furthermore, the long wavelength below the green G band of the illumination light that has reached the dichroic film 4a is transmitted (substantially the red R band is removed when it passes through the PBS film 3a, so only the green G band is included. Transmitted), modulated by the reflective LCD 6G for green G band modulation, returned to the dichroic film 4a and transmitted again. Since the signal component is P-polarized light, the signal is transmitted through the PBS film 3a, and an image for the green G band is projected on the screen through the projection lens.
[0080]
In this case, the projected light is projected onto the screen with red R band for S-polarized light, blue B band and green G band for P-polarized light. As in the case, an output side polarization characteristic filter may be provided.
[0081]
  Third of the present inventionConfiguration exampleWill be described with reference to FIGS. BookConfiguration exampleHowever, the optical characteristics of the polarization characteristic filter 2 and the dichroic film 4a are different from those in FIGS. 1 and 4, and the reflective LCD 6R, The arrangement of 6G and 6B is changed.
[0082]
  First, bookConfiguration exampleAs shown in FIG. 8, the polarization conversion characteristic of the polarization characteristic filter 2 is set so that a long wavelength of about 540 nm or less is transmitted as it is, and a short wavelength of about 500 nm or more is inverted. The other characteristics and features are the same as in FIG. 2 except that the polarization inversion band is different. That is, only the polarization component light for the blue B band is converted into P polarization component light, and the polarization component light for the red R band and green G band is emitted as it is as polarization component light.
[0083]
As shown in FIG. 9, the dichroic film 4a of the dichroic prism 4 is set so that a long wavelength of about 575 nm or less is reflected for S-polarized light and about 600 nm or less for P-polarized light, and a wavelength longer than that is transmitted. Yes. That is, the dichroic film 4a has a characteristic capable of separating the red band and the green band by transmission / reflection.
[0084]
The outline of the operation in such a configuration will be described. Again, S-polarized light is used for the illumination light. After passing through the polarization characteristic filter 2, this illumination light travels straight through the PBS film 3a for light in the blue B band, and is a reflective LCD 6B for modulating the blue B band. The signal is modulated and returned to the PBS film 3a again, the signal is reflected there, and an image for the blue B band is projected onto the screen via the projection lens. The illumination light is reflected by the PBS film 3a for the green G and red R bands, the light for the red R band is reflected by the dichroic film 4a, modulated again by the reflective LCD 6R for red R band modulation, and again. It returns to the dichroic film 4a and is also reflected. Since the signal component is P-polarized light, it passes through the PBS film, and the red R band image is projected onto the screen via the projection lens. Further, among the illumination light that has reached the dichroic film 4a, short wavelengths longer than the green G band are transmitted (substantially, the blue B band is removed when it passes through the PBS film 3a, so only the green G band is included. Transmitted), modulated by the reflective LCD 6G for green G band modulation, returned to the dichroic film 4a and transmitted again. Since the signal component is P-polarized light, it passes through the PBS film 3a, and the image for the green G band is projected on the clean through the projection lens.
[0085]
In this case, the projected light is projected onto the screen in the blue B band as S-polarized light, red R band and green G band as P-polarized light. As in the case, an output side polarization characteristic filter may be provided.
[0086]
  These second and thirdConfiguration exampleThe detailed explanation of the behavior of polarized light is omitted, but the basics are the same as those described in the first embodiment. However, it is ideal that the reflection and transmission characteristics of the dichroic film 4a of the dichroic prism 4 are exactly the same for the S-polarized light and the P-polarized light. However, in reality, only those having a gap of about 30 nm can be obtained. Considering the reality that can not be, the second and thirdConfiguration exampleIn this method, the use efficiency of illumination light and light after modulation is different, and the light use efficiency is slightly lowered. On the other hand, the firstConfiguration exampleAccording to such a configuration, the band in which the gap occurs does not reach the dichroic prism 4, and the use efficiency of light is rarely lowered. Therefore, it can be said that this configuration is better in that respect.
[0087]
Further, in these embodiments, although not particularly illustrated, if a polarizing plate is provided on the output side of the output side polarization characteristic filter 5, the amount of polarization disturbance in the optical path can be cut, and the screen The upper contrast can be improved.
[0088]
  Also each of theseConfiguration exampleAre combined with the characteristics of various types of lamps to obtain a more optimal configuration. That is, the firstConfiguration exampleThis configuration is suitable when a light source having a substantially flat spectral distribution over the entire visible light region, such as a xenon lamp, is used. SecondConfiguration exampleThis configuration is suitable when a light source having such characteristics as a high-pressure mercury lamp that has a large amount of light for the blue B band and has a peak near the green G but a small amount of light for the red R band. ThirdConfiguration exampleThis configuration is suitable when a light source such as an LED or a halogen lamp whose red light emission efficiency is gradually reduced, such as red R, green G, and blue B, is used. When a metal halide lamp is used as a light source, the spectrum distribution can be controlled to some extent by the encapsulating molecules, soConfiguration exampleIn this case, it is possible to combine them so as to match the characteristics of each component.
[0089]
  In addition, each of the aboveConfiguration exampleIn the above description, for ease of explanation, the PBS film 3a and the dichroic film 4a are shown in parallel with each other. However, the essence of the present invention can be obtained no matter how the dichroic film 4a is rotated on the optical axis. There is no loss. In order to realize as an actual device, any position of 0 °, 90 °, 180 ° or 270 ° is stable as a mechanical arrangement and easy to make.
[0090]
  The fourth of the present inventionConfiguration exampleWill be described with reference to FIG. Each of the aboveConfiguration exampleIn the configuration example, the dichroic film 4a has an angle of 45 ° with respect to the vertical plane of the main optical axis of the illumination light. However, in order to improve the band separation characteristics for the two bands, the angle should be increased. Because it is better to make it smaller, bookConfiguration exampleThen, the example which set the angle to 30 degrees is shown. BookConfiguration exampleFor example, the firstConfiguration exampleIt is applied as a modified example. Excluding the difference in shape on the dichroic prism 4 side,Configuration exampleIt is the same as the case of.
[0091]
  An air gap 8 is provided between the PBS prism 3 and the dichroic prism 4, and the main optical axis of the illumination light isOrthogonal planeIn contrast, the light reflected by the dichroic film 4a set to 30 ° is totally reflected by the surface 4b provided with the air gap 8 and guided to the reflective LCD 6B for modulation.
[0092]
  So bookConfiguration exampleSince the dichroic film 4a is set small at an angle of 30 ° with respect to the vertical plane of the main optical axis of the illumination light, the band separation characteristics for two bands of the blue B band and the red R band are further improved. Can be better
[0093]
  The fifth of the present inventionConfiguration exampleWill be described with reference to FIG. BookConfiguration exampleEven the fourthConfiguration exampleAs in the case of, the dichroic film 4aOrthogonal planeAn example of a configuration in which the angle is set to 30 ° with respect to the adhesive 9 has a specific configuration in which an adhesive 9 having an optical density substantially equal to that of the prism material is provided between the PBS prism 3 and the dichroic prism 4. Adhered with.
[0094]
  BookConfiguration exampleIn the case of the fourthConfiguration exampleThe same effect as in the case of.
[0095]
  The fourthConfiguration exampleAnd booksConfiguration exampleThe composition of the firstConfiguration exampleAlthough there is a disadvantage that the distance between the projection lens and the modulation reflective LCDs 6R, 6G, and 6B becomes longer than that in the configuration, the configuration meets the object of the present invention. Further, the main optical axis of the illumination light of the dichroic film 4aOrthogonal planeAlthough it is possible to make the angle with respect to the angle further smaller than 30 °, there is a limit in the configuration shown in FIG. 10 because a part of the light reflected by the dichroic film 4a deviates from the total reflection region. . In addition, since the distance between the projection lens and the reflective LCDs 6R, 6G, and 6B for modulation is further increased, the diameter of the projection lens is increased and the apparatus is enlarged.
[0096]
  These fourth and fifthConfiguration exampleAs shown in the drawing, even in the configuration using the 30 ° dichroic film 4a, the cross section of the PBS film 3a and the dichroic film 4a can be seen at the same time on the drawing for easy explanation. No matter how rotated on the shaft, the essence of the present invention is not impaired. In order to realize as an actual device, any position of 0 °, 90 °, 180 ° or 270 ° is stable as a mechanical arrangement and easy to make.
[0097]
  The sixth of the present inventionConfiguration exampleWill be described with reference to FIG. BookConfiguration exampleShows a configuration example using the dichroic film 4a of 15 ° with respect to a plane orthogonal to the main optical axis, with the aforementioned angle being made smaller. Reference numeral 25 denotes a polarizing plate as described later.
[0098]
  In this case, the PBS prism 3 is not rectangular, and the surface 3 b facing the dichroic prism 4 is formed so as to be parallel to the incident surface of the dichroic prism 4, and an air gap 10 is provided between the dichroic prism 4. ing. Of the main optical axis of the dichroic film 4b.Orthogonal planeThe angle of the surface 4c provided with the air gap 10 is 15 ° with respect to the main optical axis.Orthogonal planeIs −22.5 °.
[0099]
With this configuration, the light beam reflected by the dichroic film 4b is totally reflected by the surface 4c provided with the air gap 10. If this dichroic film 4a is formed so as to reflect a long wavelength less than or equal to the red R band, it is received by a reflective LCD 6R that modulates with an electric signal for the red R band as shown in the figure, and an ON / OFF signal is received. Are returned as P-polarized light and S-polarized light. The light beam for the blue B band passes through the dichroic film 4a and is received by the reflective LCD 6B which modulates with the electrical signal for the blue B band, and returns ON and OFF signals as P-polarized light and S-polarized light. The relationship between the green G band and the PBS film 3a is the same as in the case of FIG. 1, and other basic concepts are the same as in the case of FIG.
[0100]
Note that, as in the modification shown in FIG. 13, the prism side after passing through the dichroic film 4a also forms a total reflection surface 4d to reduce the size of the dichroic prism 4, and the light flux is folded back to obtain the blue B band. You may make it go to reflection type LCD6B for a minute modulation. According to this, the dichroic prism 4 can be made as small as possible, and the apparatus can be further lightened.
[0101]
In FIG. 13, the blue B band is configured to be the same surface as the red R band. However, when the reflection LCD cannot be arranged as shown in FIG. As shown in the modification, the reflective LCDs 6R and 6B for the red R band and the blue B band may be separated by reflecting on the opposite side.
[0102]
  The present inventionApplying optical deviceThe seventhConfiguration exampleWill be described with reference to FIG. BookConfiguration exampleFor example, the firstConfiguration exampleIn such a configuration, an application example in the case where the incident side and the emission side are switched and P-polarized light is used as illumination light will be described. Even if P-polarized light is used, the same effect can be obtained.
[0103]
Although details are omitted, basically, the roles of S-polarized light and P-polarized light are interchanged, and the contents are the same as those described in the configuration of FIG.
[0104]
  Of course, all the other things we ’ve discussed so farConfiguration exampleNeedless to say, the same purpose can be achieved by simply reversing the relationship between the illumination light and the image modulated light.
[0105]
  Next, the present inventionBefore applyingA configuration example of the projector will be described with reference to FIG. This configuration example relates to the configuration of the entire liquid crystal projector including the optical device 1 configured as described above.
[0106]
This liquid crystal projector includes, for example, an optical device 1 of the type shown in FIG. 15 and a reflective LCD 6R, 6G, 6B, an illumination optical system 22 including a light source 21, and a projection lens system 24 for a screen 23. A polarizing plate 25 is interposed between the output side polarization characteristic filter 5 and the projection lens system 24.
[0107]
As an example, the illumination optical system 22 that generates illumination light by P-polarized light includes a light source 21, a rotary parabolic mirror 26, a mirror 27 with a window 27a, a polarization converter 28, an integrator optical system 29 (fly-eye lens plates 30, 31). , 32 to condenser lens 33). As a configuration for obtaining image modulated light from the illumination light, a configuration in which another output side polarization characteristic filter 5 is inserted on the output side of the PBS prism 3 in the configuration shown in FIG. By doing this, the entire band of R, G, and B becomes S-polarized light, but as the P-polarized light component is mixed while passing through each prism, a polarizing plate 25 is added to remove it. Yes. A projection lens system 24 including a plurality of projection lenses 34 is arranged on the output side, and is configured to project an image on the screen 23.
[0108]
As shown in FIG. 16B, the polarization converter 28 has a combined structure of a PBS film 35, a total reflection mirror 36, and a half-wave plate 37.
[0109]
In such a configuration, first, the light source 21 is placed in the vicinity of the focal point of the rotary parabolic mirror 26, so that the light generated by the light source 21 becomes substantially parallel light by the rotary parabolic mirror 26 and is directed to the polarization converter 28. Head. In the meantime, a plane mirror 27 (a mirror with a window) having a window 27a having substantially the same shape as the entrance window of the polarization converter 28 (incident end faces of the two PBS prisms provided in the converter) is attached to the rotary parabolic mirror 26. The aforementioned parallel light that is arranged so as to be orthogonal to the main optical axis and does not directly enter the polarization converter 28 is returned to the paraboloid mirror 26. The returned light passes again near the focal point and is added as light incident on the polarization converter 28 by the rotary parabolic mirror 26. In the polarization converter 28, the light having random polarization is converted into P-polarized light by combining the PBS film 35 and the half-wave plate 37 (unless conversion efficiency is considered). In the configuration as shown in FIG. 16B, the incident light beam is emitted in an area twice as large as the incident side area of the polarization converter 28. The luminous flux aligned with the P-polarized light is a two-dimensional array of element lenses cut out by the fly-eye lens plate 30 at the aspect ratio (4: 3 in this case) of the reflective LCDs 6R, 6G, 6B. The outer shape is matched with the outer shape of the output side of the polarization converter 28. A cylindrical lens array 31 is formed by arranging a number of cylindrical lenses in the vicinity of the focal position of the element lens of the fly-eye lens plate 30 so as to match the number of horizontal arrays of the fly-eye lens plate 30. Each cylindrical lens is related to the condenser lens 33 and is configured to have such an intensity as to irradiate the entire lateral width of the reflective LCDs 6R, 6G, 6B. Immediately thereafter, another cylindrical lens array 32 is placed. This is the number of cylindrical lenses aligned with the number of vertical arrays of the fly-eye lens plate 30, and the intensity thereof is related to the condenser lens 33, and the reflective LCD 6R. , 6G, 6B are set to irradiate the entire vertical width.
[0110]
The illumination light by the P-polarized light thus produced is converted into S-polarized light only for the green G band by the polarization characteristic filter 2 having the characteristics as shown in FIG. 2, and is guided to the PBS prism 3, and the PBS film 3a. The light in the blue B and red R bands is transmitted and the light in the green G band is reflected. The reflected S-polarized light for the green G band is modulated by the reflective LCD 6G that controls the green G, and is reflected as it is in the S-polarized light in the OFF signal pixel, and is converted to the P-polarized light and reflected in the ON signal pixel. The These modulated light beams are returned to the PBS film 3a again. Here, the S-polarized light is reflected and returned toward the light source 21, while the P-polarized light is transmitted and travels toward the screen 23. On the way, an exit side polarization characteristic filter 5 is disposed on the exit side of the PBS prism 3, and P-polarized light is converted into S-polarized light. Then head to the screen 23. Since the output side polarization characteristic filter 5 is exactly the same as the polarization characteristic filter 2, the polarized light is converted only for the green G band, and the modulated S-polarized light for the blue B band and red R band, which will be described later, remains as it is. Transmit with S-polarized light. As a result, the entire visible light band is directed toward the screen 23 with S polarization.
[0111]
The above-mentioned illumination light reaches the PBS film 3a, and the transmitted blue B and red R band lights are reflected by the dichroic film 4a of the dichroic prism 4 so that the blue B band light is reflected. It reaches the reflective LCD 6B that is in charge of modulation, and reflects off the P-polarized light at the OFF signal pixel, and converts it to S-polarized light at the ON signal pixel. These modulated light fluxes are returned to the dichroic film 4a again, but the light for the blue B band is reflected and travels toward the PBS film 3a. At this time, the S-polarized light of the ON signal is reflected by the PBS film 3a, and the P-polarized light of the OFF signal is transmitted and returned to the light source 21. The light reflected by the PBS film 3 a passes through the output side polarization characteristic filter 5 and the polarizing plate 25, but this band passes through the projection lens system 24 without being subjected to polarization conversion and is projected onto the screen 23.
[0112]
Further, the illumination light reaches the PBS film 3a, and the transmitted blue B and red R band lights are transmitted through the dichroic film 4a of the dichroic prism 4, and the red R band light is transmitted, and the red R band light is transmitted. The reflection type LCD 6 </ b> R responsible for the modulation is reflected, and the P signal is reflected as it is in the pixel of the OFF signal, and the S signal is reflected after being converted into the S signal in the pixel of the ON signal. These modulated light fluxes are returned to the dichroic film 4a again, but light for the red R band is transmitted and travels toward the PBS film 3a. At this time, the S-polarized light of the ON signal is reflected by the PBS film 3a, and the P-polarized light of the OFF signal is transmitted and returned to the light source 21. The light that has passed through the PBS film 3 a passes through the output side polarization characteristic filter 5 and the polarizing plate 25, but this band passes through the projection lens system 24 without being subjected to polarization conversion and is projected onto the screen 23.
[0113]
In this way, light in each of the R, G, and B bands can be superimposed on the screen 23 to form a desired color image.
[0114]
  Of the present inventionFirstThe embodiment will be described with reference to FIG. This embodiment is described above.Configuration exampleAs described above, the present invention relates to the entire configuration of the liquid crystal projector including the optical device 1. In the present embodiment, the polarization characteristic filter 2 is disposed between the polarization converter 28 and the fly-eye lens plate 30 in the illumination optical system 22 independently of the optical device 1. Thus, the polarization characteristic filter 2 is configured as an illumination optical system 22 that causes the green G band light to enter the PBS prism 3 as S-polarized component light, blue B, and red light as P-polarized component light. At this time, the behavior in the integrator optical system 29 does not need to consider polarization, and thus operates in the same manner as in FIG. Since there is no polarization characteristic filter 2 after exiting the condenser lens 33, the behavior after entering the PBS prism 3 is exactly the same as in FIG.
[0115]
As a configuration for selectively controlling the polarization of the illumination light itself for each band, various other configurations may be adopted, but a configuration as in a modification shown in FIG. 18 may be used. In FIG. 18, only the part corresponding to the light source 21 to the integrator optical system 29 is drawn. The difference from FIG. 17 is the structure of the polarization converter 38 and the insertion positions of the polarization converter 38 and the polarization characteristic filter 2. The polarization converter 38 is configured using a polarization alignment prism array 39 and a half-wave plate 37. In this modification, the polarization converter 38 is inserted after the cylindrical lens array 31 in the integrator optical system 29, and the polarization characteristic filter 2 is inserted thereafter. Even with such a configuration, the light emitted from the integrator optical system 29 can have the same characteristics as in FIG.
[0116]
  Of the present inventionSecondThe embodiment will be described with reference to FIG. The present embodiment relates to a polarization converter 41 suitable for being interposed in the illumination optical system 22 including the polarization characteristic filter 2 as in the case described with reference to FIGS. The polarization converter 41 includes a pair of PBS prisms 42 each having a PBS film (polarization beam splitter film) 42a that reflects an S-polarized component in incident light whose polarization direction is random, and the PBS films 42a. Polarization characteristic filters 2 provided on the reflection light emission surfaces of the PBS prism 42 facing each other, a prism 43 having a total reflection surface 43a provided on the emission side, and light totally reflected by the total reflection surface 43a is emitted. The half-wave plate 44 provided on the exit surface of the prism 43, and the polarization characteristic filter 2 provided on the exit surface from which the transmitted light exits in the PBS prism 42.
[0117]
In such a configuration, the polarization of one band component (for example, green G) of red R, green G, and blue B among the S polarization components incident on the PBS prism 42 and reflected and separated by the PBS film 42a. Only the polarization direction is converted into P-polarized light by the polarization characteristic filter 2, totally reflected by the total reflection surface 43 a, and then polarized in the entire band by the half-wave plate 44. In the light emitted from the half-wave plate 44, one band (for example, green G) is an S-polarized component, and two bands are a P-polarized component. On the other hand, the P-polarized light component incident on the PBS prism 42 and transmitted and separated by the PBS film 42a is simply passed through the polarization characteristic filter 2. Therefore, the polarization direction of only one of the band components (for example, green G) of red R, green G, and blue B in the P-polarized component is converted into S-polarized light by the polarization characteristic filter 2 and emitted. Even with such a configuration, the polarization converter 41 as a whole has uniform characteristics of the emitted light.
[0118]
  As shown in FIG. 20 showing a modification, the half-wave plate 44 and the polarization characteristic filter 2 may be replaced. In this case, the polarization converter41The polarization characteristic filter 2 located on the output side of the light has a polarization conversion function for converting the polarization direction of only one band component of red R, green G, and blue B into P-polarized light components into S-polarized light. It only has to be. As a result, one band is emitted with S polarization and two bands with P polarization.
  This configuration is substantially the same as the combination of “polarization converter 28 and polarization characteristic filter 2” shown in FIG. 17, and has the same function.
[0119]
In each of the above-described embodiments, the PBS film and the dichroic film are all held by the prism. However, even if formed with a plate-like transparent material (so-called mirror), the essence of the present invention is impaired. is not.
[0120]
【The invention's effect】
  Claim 1Or 2According to the projector of the described invention, the light of the three bands of the red band, the green band, and the blue band is converted into light having different polarization states in the two bands and the one band by using the polarization characteristic filter, Polarized light is separated by the polarization separation element, and the polarization component light including two bands separated by the polarization separation element is band-separated by the dichroic film, so the dichroic film that simultaneously separates the three bands crosses. There is no need to adopt a complicated configuration, and a simple configuration using a single polarization separation film or dichroic film can separate light in the three bands of the red band, the green band and the blue band, eliminating the problem of flare light. Thus, a projected image with high contrast can be obtained.
[0121]
  Claim 3According to the described invention, claim 1Or 2In the projector described above, the polarization characteristic filter, the polarization separation element, and the dichroic element are integrally provided. Therefore, in an existing projector, by replacing each color component light separation portion with this integrated optical device, The purpose of the period can be easily achieved.
[0123]
According to the invention described in claim 4, an example of a specific example for realizing the invention described in claim 3 is presented. In particular, in view of the band characteristics, the illumination light and the modulated image light It is possible to provide a projector that does not reduce the light utilization efficiency.
[0124]
According to the invention described in claim 5, an example of a specific example for realizing the invention described in claim 3 is presented.
[0125]
According to the invention described in claim 6, an example of a specific example for realizing the invention described in claim 3 is presented.
[0130]
  Claim 7According to the described invention,Claim 4In realizing the invention described above, it is preferable to use a xenon lamp as a light source because the entire visible light region has a substantially flat spectral distribution characteristic.
[0131]
  Claim 8According to the described invention,Claim 5In realizing the invention described above, it is preferable to use a high-pressure mercury lamp as a light source because it has a light emission characteristic that has a large amount of light in the blue B band and a peak near the green G band but a small amount of light in the red R band It becomes.
[0132]
  Claim 9According to the described invention,Claim 6In realizing the invention described above, it is preferable to use an LED or a halogen lamp as a light source because the light emission efficiency of red R, green G, and blue B gradually decreases.
[0133]
  Claim 10According to the described invention, claims 4 and 5 are provided.Or 6In realizing the described invention, by using a metal halide lamp as a light source, the spectral distribution can be controlled to some extent by the molecules to be encapsulated, which is suitable for any type.
[0134]
  Claim 11According to the described invention, claim 110In the projector according to any one of the above, the main optical axis of the illumination lightOrthogonal planeSince the angle of the dichroic film with respect to is made as small as possible, the separation characteristics for two bands in the dichroic film can be further improved.
[0135]
  Claim 12According to the described invention, by utilizing the total reflection by the air gapClaim 11The described invention can be easily realized.
[0136]
  Claim 13According to the described invention, the polarization separation element and the dichroic element are bonded with an adhesive having an optical density substantially equal to the material of the polarization separation element.Claim 11The described invention can be easily realized.
[0137]
  Claim 14According to the described invention, claim 1ThirteenIn the projector according to any one of the above, it is possible to align the polarization direction of the modulated image light by using the output side polarization characteristic filter, which is suitable for projection onto a screen using the polarization characteristic.
[0138]
  Claim 15According to the described invention,Claim 14In the projector described above, by providing a polarizing plate on the output side of the output side polarization characteristic filter, it is possible to cut even when polarization is disturbed in the middle of the optical path, so that the contrast on the screen can be further improved.
[Brief description of the drawings]
FIG. 1 shows the first of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 2 is a characteristic diagram showing optical characteristics of the polarization characteristic filter.
FIG. 3 is a characteristic diagram showing optical characteristics of the dichroic film.
FIG. 4 shows the second of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 5 is a characteristic diagram showing optical characteristics of the polarization characteristic filter.
FIG. 6 is a characteristic diagram showing optical characteristics of the dichroic film.
FIG. 7 shows the third aspect of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 8 is a characteristic diagram showing optical characteristics of the polarization characteristic filter.
FIG. 9 is a characteristic diagram showing optical characteristics of the dichroic film.
FIG. 10 shows the fourth aspect of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 11 shows the fifth aspect of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 12 shows the sixth aspect of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 13 is a plan view illustrating a configuration example of an optical device as a main part in the modification.
FIG. 14 is a plan view showing a configuration example of an optical device as a main part in different modified examples.
FIG. 15 shows the seventh aspect of the present invention.Configuration exampleIt is a top view which shows the structural example of the optical device of the principal part in.
FIG. 16 shows the present invention.Before applyingIt is a top view which shows the structural example of a liquid crystal projector.
FIG. 17 shows the present invention.FirstIt is a top view which shows the structural example of the liquid crystal projector in embodiment.
FIG. 18 is a plan view of a main part showing a modification example thereof.
FIG. 19 shows the present invention.SecondIt is a top view which shows the structural example of the polarization converter in embodiment.
FIG. 20 shows the present invention.The fruitForm of applicationVariations ofIt is a top view which shows the structural example of the polarization converter.
FIG. 21 is a plan view showing a conventional example.
[Explanation of symbols]
2 Polarization characteristic filter
3 Polarization separation element
4 Dichroic elements
4a Dichroic membrane
5 Output side polarization characteristics filter
6R, 6G, 6B Image forming member
8 Air gap
9 Adhesive
10 Adhesive
21 Light source
22 Illumination optics
23 screens
24 Projection lens system
25 Polarizing plate
41 Polarization converter
42a Polarizing beam splitter film
44 half-wave plate
51 Polarization converter

Claims (15)

A light source that emits illumination light; a pair of polarizing beam splitter prisms each including a polarizing beam splitter film that separates P-polarized component light and S-polarized component light; and A first polarization characteristic having a characteristic of converting any one of the red band, green band, and blue band light of the S polarization component light separated by the beam splitter film into P polarization component light A filter, a prism having a total reflection surface provided on the first polarization characteristic filter emission side, and an emission surface of the prism from which the light totally reflected by the total reflection surface is emitted; A half-wave plate for converting the polarization direction of light of three bands passing through the polarization characteristic filter; and an output surface from which the transmitted light of the polarizing beam splitter prism is emitted, A second polarization characteristic filter having a characteristic of converting the one band of the red band, the green band, and the blue band of the P polarization component light separated by the beam splitter film into S polarization component light (Hereinafter, the first and second polarization characteristic filters are collectively referred to simply as a polarization characteristic filter),
An illumination optical system having
A polarization separation element that separates the P-polarized component light and the S-polarized component light that have passed through the polarization converter ;
A dichroic element having a dichroic film that separates polarization component light including two bands out of the polarization component light separated by the polarization separation element into each band component light;
Three reflections that form an image to be projected by modulating the polarization state for each of the three bands of red, green, and blue bands separated into three bands by the polarization separation element and the dichroic film A mold image forming member;
A projection lens system for projecting an image formed by these image forming members onto a screen;
A projector comprising: A light source for emitting illumination light, a pair of polarizing beam splitter prism having a polarizing beam splitter film for separating the P-polarized component light and S-polarized component light, provided on the reflected light exit surface of the polarization beam splitter prism, the A half-wave plate for converting S-polarized component light separated by the polarization beam splitter film into P-polarized component light, a prism having a total reflection surface provided on the transmission side of the half-wave plate, and the total reflection surface P-polarized component light that is provided in common to the exit surface of the prism from which the totally reflected light exits and the exit surface from which the P-polarized component light transmitted through the polarizing beam splitter film exits, and exits from the respective exit surfaces. A polarization converter comprising a polarization characteristic filter having a characteristic of converting any one of the three bands of light of the red band, the green band, and the blue band into S-polarized component light, An illumination optical system and having
A polarization separation element that separates the P-polarized component light and the S-polarized component light that have passed through the polarization converter ;
A dichroic element having a dichroic film that separates polarization component light including two bands out of the polarization component light separated by the polarization separation element into each band component light;
Three reflections that form an image to be projected by modulating the polarization state for each of the three bands of red, green, and blue bands separated into three bands by the polarization separation element and the dichroic film A mold image forming member;
A projection lens system for projecting an image formed by these image forming members onto a screen;
A projector comprising: The projector according to claim 1, wherein the polarization separation element and the dichroic element are integrally provided . 4. The projector according to claim 3 , wherein the S-polarized component light emitted from the polarization converter is for a green band , and the dichroic film has a characteristic of band-separating a blue band and a red band for the same polarized component light. 4. The projector according to claim 3 , wherein the S-polarized component light emitted from the polarization converter is for a red band , and the dichroic film has a characteristic of band-separating a blue band and a green band for the same polarized component light. 4. The projector according to claim 3 , wherein the S-polarized component light emitted from the polarization converter is for a blue band , and the dichroic film has a characteristic of band-separating a green band and a red band for the same polarized component light. The projector according to claim 4, wherein the light source is a xenon lamp. The projector according to claim 5, wherein the light source is a high-pressure mercury lamp. The projector according to claim 6, wherein the light source is an LED or a halogen lamp.   The projector according to claim 4, 5, or 6, wherein the light source is a metal halide lamp. The projector according to claim 1, wherein the dichroic film is formed at an angle of 45 ° or less with respect to a plane orthogonal to the main optical axis of the illumination light. The projector according to claim 11, wherein an air gap that totally reflects a light component reflected by the dichroic film is provided between the polarization separation element and the dichroic element. The projector according to claim 11, wherein the polarization separation element and the dichroic element are bonded by an adhesive having an optical density substantially equal to a material of the polarization separation element. The projector according to any one of claims 1 to 13, further comprising an output-side polarization characteristic filter having the same characteristics as the polarization characteristic filter on an output optical path with respect to the projection lens system. The projector according to claim 14, further comprising a polarizing plate on an output side of the output side polarization characteristic filter.

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