KR100871190B1 - Wavelength- selective polarization conversion element, projection displaying optical system and image projection apparatus - Google Patents

Abstract

Provided is a wavelength selective polarization conversion element having a polarization conversion function and capable of reducing the number of optical components and simplifying the structure of the optical system. The wavelength selective polarization conversion element 5 converts unpolarized light including light in the first wavelength band B, light in the second wavelength band G, and light in the third wavelength band R into polarized light. The polarization conversion element 5 has optical separation films 32 and 34 having a characteristic in which the transmittance of light in at least the first polarization direction is changed in accordance with the wavelength range, and the polarization direction of the light from the optical separation film in the first direction. And a phase difference plate 33 for converting between the polarization direction and the second polarization direction. The polarization conversion element emits light in two wavelength bands of the first to third wavelength bands as polarized light having one polarization direction in the first and second polarization directions, and emits light in another wavelength band to the other polarization. It emits as polarized light having a direction.

Description

WAVELENGTH- SELECTIVE POLARIZATION CONVERSION ELEMENT, PROJECTION DISPLAYING OPTICAL SYSTEM AND IMAGE PROJECTION APPARATUS

1 is a diagram showing the configuration of a projection display optical system according to Embodiment 1 of the present invention;

2 is a schematic configuration diagram of a wavelength selective polarization conversion element used in Example 1;

3 is a characteristic diagram of a first optical separation film constituting the wavelength selective polarization conversion element of Example 1;

4 is a characteristic diagram of a second optical separation film constituting the wavelength selective polarization conversion element of Example 1;

5 is a diagram showing the configuration of a projection display optical system according to Embodiment 2 of the present invention;

6 is a schematic configuration diagram of a wavelength selective polarization conversion element used in Example 2;

7 is a characteristic diagram of a first optical separation film constituting the wavelength selective polarization conversion element of Example 2;

8 is a characteristic diagram of a second optical separation film constituting the wavelength selective polarization conversion element of Example 2;

9 is a diagram showing the configuration of a projection display optical system according to Embodiment 3 of the present invention;

10 is a schematic configuration diagram of a wavelength selective polarization conversion element used in Example 3;

11 is a characteristic diagram of a first optical separation membrane constituting the wavelength selective polarization conversion element of Example 3;

12 is a characteristic diagram of a second optical separation film constituting the wavelength selective polarization conversion element of Example 3;

FIG. 13 is a diagram showing the configuration of a projection display optical system according to Embodiment 4 of the present invention; FIG.

14 is a schematic configuration diagram of a wavelength selective polarization conversion element used in Example 4;

15 is a characteristic diagram of a first optical separation membrane constituting the wavelength selective polarization conversion element of Example 4

16 is a characteristic diagram of a second optical separation membrane constituting the wavelength selective polarization conversion element of Example 4;

17 shows the spectral characteristics of a dichroic prism;

Fig. 18 is a surface diagram showing an example of the film configuration of the first and second optical separation membranes constituting the wavelength selective polarization conversion element of Example 1;

19 is a characteristic diagram of the first optical separation membrane shown in FIG. 18;

20 is a characteristic diagram of a second optical separation membrane shown in FIG. 18.

<Description of the symbols for the main parts of the drawings>

1, 301, 401, 501: white light source

2, 302, 402, 502: parabolic reflectors

3, 4; 303, 304; 403, 404; 503, 504: fly's eye lens

5, 305, 405, 505: wavelength selective polarization conversion element

6, 306, 406, 506: condenser lens

7, 307, 408, 522: color separation / synthesis optical system

8, 308, 412, 507, 513: dichroic mirror

13, 313, 409: polarizing beam splitter

10, 14, 15; 310, 314, 315; 411, 413, 414; 510, 519, 521: liquid crystal panel

31, 41, 51, 61: reflective film

32, 42, 52, 62: first wavelength selective polarization separator

33, 43, 53, 63: phase difference plate

34, 44, 54, and 64: second wavelength selective polarization separator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength selective polarization conversion element for converting unpolarized light into light in a polarization direction according to a wavelength range (color), and an image projection apparatus such as a liquid crystal projector having the same.

An image projection apparatus that performs color separation and color synthesis by a polarizing beam splitter is disclosed in Japanese Patent Laid-Open Nos. 2001-154152 and 2000-19455. In the above apparatus, unpolarized light emitted from a light source is decomposed into a plurality of light beams by a lens array, and a secondary light source image is formed by each light beam, and the light beam from the secondary light source image is condensed by a condenser lens such as a liquid crystal panel. It is superimposed on an image forming element to illuminate it with approximately uniform brightness.

Here, each split light beam emitted from the lens array is incident on a polarization conversion cell corresponding to each lens cell of the lens array, which is provided in a plurality of polarization conversion elements. Each polarization conversion cell has a polarization separator, a half wave plate and a reflecting surface. Unpolarized light incident on each polarization conversion cell is separated into P-polarized light and S-polarized light by a polarization separator. P-polarized light passes through the polarization separation membrane, and then rotates the polarization direction by 90 ° with a half-wave plate and emits it as S-polarized light.

On the other hand, S-polarized light is reflected by the polarization splitting film, is reflected by the reflecting surface, and is emitted while being S-polarized. S-polarized light emitted by matching the polarization direction from the polarization conversion element is incident on the condenser lens.

Further, the S-polarized light emitted from the condenser lens is separated into the first and second wavelength band light and the third wavelength band light by the dichroic element. In this step, the first and second wavelength band light travel through the same optical path and have the same polarization direction. Thereafter, a wavelength (color) selective phase difference plate is passed through the polarization beam splitter to guide the first and second wavelength band light to the first and second image forming elements, respectively.

Thereby, it is possible to separate the first and second wavelength band light into light having different polarization directions. The wavelength selective retardation plate is made by stacking a plurality of stretched films, and converts only the polarization direction of one wavelength region light into the polarization direction orthogonal to the polarization direction among the first and second wavelength light beams incident thereto. It has the property of transmitting the wavelength region light without changing the polarization direction.

As described above, a polarization conversion element disposed in the vicinity of the lens array and a wavelength selective phase difference plate disposed in the vicinity of the polarization beam splitter are generally used as an image projection apparatus that performs color separation using the polarization beam splitter.

As a specific example, the optical element disclosed in Japanese Patent Laid-Open No. 2000-19455 or Japanese Patent Laid-Open No. 11-153774 may be used. Japanese Patent Application Laid-Open No. 2000-19455 discloses a first dichroic layer that transmits light in a predetermined wavelength range and reflects light in another wavelength range, and rotates the polarization plane of the light transmitted through the first dichroic layer by 90 degrees. Disclosed is an optical element comprising a retardation layer to be made and a total reflection layer for total reflection of light from the retardation layer. Japanese Unexamined Patent Application Publication No. 11-153774 discloses a light beam splitter having wavelength selectivity and performing polarization, detection, color separation and color synthesis of light. However, as disclosed in Japanese Laid-Open Patent Publication No. 2001-154152, the use of the wavelength selective retardation plate separately from the polarization conversion element increases the number of optical parts constituting the image projection value. In addition, a structure for positioning and supporting the wavelength selective retardation plate or cooling the wavelength selective retardation plate formed of a multilayer film is required, which leads to a complicated structure.

The present invention has the same polarization conversion function as that obtained by the conventional polarization conversion element and the wavelength selective retardation plate, and in particular, it is possible to reduce the number of optical components and simplify the structure in the projection display optical system or the image projection apparatus. It is an object to provide a wavelength selective polarization conversion element.

A wavelength selective polarization conversion element as one aspect of the present invention is a polarization conversion element for converting unpolarized light including light in a first wavelength region, light in a second wavelength region, and light in a third wavelength region to polarized light. The polarization conversion element has a function of separating light by transmission and reflection, wherein at least the transmittance of light in the first polarization direction is changed between transmittance higher than 50% and transmittance lower than 50% depending on the wavelength range. It has an optical separation membrane having a characteristic of. Moreover, it has a phase difference plate which converts the polarization direction of the light from the said optical separation film between the said 1st polarization direction and the 2nd polarization direction orthogonal to the said 1st polarization direction. The polarization conversion element emits light in two wavelength bands of the first, second and third wavelength bands as polarized light having one polarization direction among the first and second polarization directions, It is characterized in that the light of the other wavelength range of the second and third wavelength range is emitted to the polarized light having the other polarization direction of the first and second polarization direction.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings.

[ Example  One]

1 shows a projection display optical system using the wavelength selective polarization conversion element according to the first embodiment of the present invention.

The luminous flux emitted from the white light source 1 is converted into parallel luminous flux by the parabolic reflector 2. In addition, the parallel luminous flux here means not only the luminous flux which is completely parallel, but the luminous flux which spreads or converges to the extent which it can see in parallel in the characteristic of an optical system. This also applies to the following examples.

This parallel light beam is divided into a plurality of light beams by the first fly's eye lens 3, and each split light beam is focused. Each split light beam is condensed in the vicinity of the second fly's eye lens 4 and the wavelength selective polarization conversion element 5 to form an image of the light source (secondary light source image). The fly's eye lenses 3 and 4 are lens arrays in which a plurality of lens cells are arranged in a two-dimensional direction. Each lens cell has a rectangular lens shape similar in shape to a liquid crystal panel (image forming element) to be described later, which is an illuminated surface.

The wavelength selective polarization conversion element 5 emits light in the blue (B) band and the green (G) band, which are the first and second wavelength bands, of the split light beams from the second fly's eye lens 4, in the first polarization direction. Converts to S-polarized light which is linearly polarized light with. Further, light in the red (R) band, which is the third wavelength region, is converted into P-polarized light, which is linearly polarized light having a second polarization direction.

S-polarized light in the B and G bands and P-polarized light in the R band are emitted by the wavelength selective polarization conversion element 5 and are reflected by the mirror 20. Thereafter, the light is condensed by the condenser lens 6, and the reflective liquid crystal panels 15, 10, and 14 for the B band, the G band, and the R band are superimposed through the color separation / synthesis optical system 7, respectively. To the enemy. In addition, at least the condenser lens 6 from the light source 1 is called an illumination optical system. This also applies to the embodiment described below.

The color separation / synthesis optical system 7 has a dichroic mirror 8 that reflects light in the B band and the R band among polarized light transmitted through the condenser lens 6 and transmits the G band light. The G band polarized light transmitted through the dichroic mirror 8 is reflected by the first polarized beam splitter 9 and enters the reflective liquid crystal panel 10 for the G band.

Here, each of the reflective liquid crystal panels is connected to the driving circuit (D). An image signal is input to a drive circuit D which is a part of a projector (image projection apparatus) equipped with the reflective display optical system from an image supply device IP such as a personal computer, a DVD player, a video deck, a television tuner, or the like. The driving circuit D drives the reflection type liquid crystal panel corresponding to each color based on the R, G, and B components of the input image signal. As a result, each reflective liquid crystal panel reflects and modulates incident light in each wavelength region and emits the image light as image light. In addition, although such a structure is not shown in the following example, it is the same.

Image light (polarized light) from the G band liquid crystal panel (hereinafter referred to as G liquid crystal panel) 10 passes through the first polarized beam splitter 9 and further passes through the second polarized beam splitter 11. Projection lens 12 projects onto a screen (not shown).

On the other hand, of the polarized light of the B band and the R band reflected by the dichroic mirror 8, the R band polarized light passes through the third polarized beam splitter 13, and the B band polarized light is the third polarized beam splitter. Reflected by (13). Thus, the B-band polarized light and the R-band polarized light emitted from the third polarization beam splitter 13 are each a B-band liquid crystal panel (hereinafter referred to as B liquid crystal panel) 15 and a R-band liquid crystal panel (hereinafter R). Condensed on a liquid crystal panel 14).

The R-band polarized light reflected by the R liquid crystal panel 14 and modulated is reflected by the third polarization beam splitter 13. In addition, the B-band polarized light reflected by the B liquid crystal panel 15 is transmitted through the third polarization beam splitter 13. Thereafter, only the polarization direction of the B band polarized light is rotated 90 degrees by the wavelength selective phase plate 16, and the polarization directions of the B band polarized light and the R band polarized light coincide. The polarized light in both bands is reflected by the second polarization beam splitter 11 and projected onto the screen by the projection lens 12.

Next, the structure and optical action of the above-mentioned wavelength selective polarization conversion element 5 will be described in detail with reference to FIG. 2 shows a schematic structure of the wavelength selective polarization conversion element 5.

The part enclosed by the circle | round | yen of the dotted line in the figure comprises one polarization conversion cell 5a, and the some lens cell in which the some polarization conversion cell 5a of the same structure comprises the fly-eye lens 3,4 It is installed correspondingly. Moreover, the light shielding plate 5b is provided in the area | region from the position of the reflective film mentioned later to the polarization conversion cell adjacent to an upward direction among the light incident surfaces of each polarization conversion cell 5a, and interrupts the incidence of the light to this part. Doing. As a result, light is incident only from the region between the reflective film and the first wavelength selective polarization separation film described later.

2 shows an enlarged display of one polarization conversion cell 5a. Numeral 31 denotes the above-described reflective film and constitutes a reflective surface. In order from the light incidence side, numeral 32 denotes the first wavelength selective polarization separator, numeral 33 denotes the retardation plate, and numeral 34 denote the second wavelength selective polarization separator. Hereinafter, the wavelength selective polarization separator is simply referred to as an optical separation membrane.

The first light separation film 32, the retardation plate 33, and the second light separation film 34 have an inclination of 45 degrees with respect to the incident axis direction of the light (direction from the left to the right in the drawing). In addition, the reflective film 31 is arranged in parallel with the first light separation film 32. Moreover, each optical separation film is formed as a multilayer film on the surface of the glass or acrylic board | substrate which is actually a parallel plate. In addition, the retardation plate 33 is formed in a film shape and adhered to the same substrate.

The characteristics of the first and second optical separation membranes 32 and 34 are shown in FIGS. 3 and 4, respectively. The first optical separation film 32 has a transmittance of S-polarized light of B-band and G-band light at or near 0% (less than 50%), and a transmittance of S-polarized light of R-band light at 100% or close to (50). Higher than%).

On the other hand, the second optical separation film 34 has a transmittance of S-polarized light of B band light and G-band light 100% or closer to it (higher than 50%), and a transmittance of S-polarized light of R band light to 0% or close to it ( Lower than 50%). As described above, the first and second light separation membranes 32 and 34 have characteristics in which the transmittance for S-polarized light is opposite to each other in each wavelength band.

In addition, these first and second optical separation films 32 and 34 have a characteristic in which the transmittance for P-polarized light is 100% or close to (higher than 50%) irrespective of the wavelength band.

In addition, the retardation plate 33 is a half wave plate and has a function of rotating the polarization direction of linearly polarized light by 90 degrees.

White unpolarized light is incident on the wavelength selective polarization conversion element 5 configured as described above from the left side of FIG. The P-polarized light of the B band and the G band of the unpolarized light is transmitted through the first light separation membrane 32, then is converted into S polarization through the phase difference plate 33, and is transmitted through the second light separation membrane 34 to S. It emits from the wavelength selective polarization conversion element 5 as polarized light.

The S-polarized light of the B band and the G band is reflected by the first light separation film 32, further reflected by the reflective film 31, and exits from the wavelength selective polarization conversion element 5 as S-polarized light.

Further, the P-polarized light in the R band passes through the first light separation film 32 and then passes through the retardation plate 33 to be converted into S-polarized light, and is reflected by the second light separation film 34. Then, the reflected light is again transmitted through the retardation plate 33 to be converted into P polarized light, transmitted through the first light separation film 32 and reflected by the reflecting film 31, and thus the wavelength selective polarization conversion element 5 as P polarized light. Injection from

In addition, the S-polarized light in the R band passes through the first light separation film 32, passes through the retardation plate 33, is converted into P-polarized light, and is transmitted by the second light separation film 34, and has a wavelength as P-polarized light. It emits from the selective polarization converting element 5.

The white unpolarized light incident on the wavelength selective polarization converting element 5 configured as a single element is converted into S polarized light in the B band and G band and P polarized light in the R band, and is emitted from the polarization converting element 5.

Therefore, the B-band light and the R-band light from the polarization conversion element 5 are guided from the dichroic mirror 8 to the third polarization beam splitter 13 without passing through the wavelength selective phase difference plate conventionally used. It is possible.

Thereby, the 3rd polarization beam splitter 13 can separate these B band light and R band light according to the polarization direction, and inject them into B liquid crystal panel 15 and R liquid crystal panel 14, respectively. Do.

For this reason, compared with the conventional case where a wavelength selective retardation plate is provided in the optical path from the dichroic mirror 8 to the third polarization beam splitter 13, it is possible to reduce the number of optical components of the optical system. In addition, since the wavelength selective retardation plate becomes unnecessary, the structure for supporting or cooling it is also unnecessary.

18 shows an example of the configuration as a multilayer film of the first and second light separation films 32 and 34 described with reference to FIGS. 3 and 4. In any of the optical separation films 32 and 34, PHB56 manufactured by OHARA Corporation was used as the glass substrate.

In addition, H, M, and L in a figure represent a high refractive index layer, an intermediate refractive index layer, and a low refractive index layer, respectively, and the number of the left side of H, M, L represents the thickness (nm) of each layer (film). In this configuration example, TiO ₂ was used as the high refractive index layer, Al ₂ O ₃ was used as the intermediate refractive index layer, and SiO ₂ was used as the low refractive index layer.

19 and 20 show transmittance characteristic data of the first and second light separation membranes 32 and 34 having the film structure shown in FIG. 18, respectively. Tp45 shows the transmittance characteristic when P polarized light is incident at the incident angle of 45 degrees to the optical separation membrane, and Ts45 shows the transmittance characteristic when S polarized light is incident at the incident angle of 45 degrees with the optical separation membrane.

In addition, although the specific film structure is not shown in the following Example, the characteristic corresponding to each Example can be acquired by suitably modifying the film structure shown in this Example.

Next, in this embodiment, the reason why the wavelength selective polarization conversion element 5 is arranged between the second fly's eye lens 4 and the condenser lens 6 will be described.

The fly's eye lenses 3 and 4 respectively divide the parallel light beams emitted from the parabolic reflector 2 into a plurality of light beams, and each light beam is focused on the wavelength selective polarization conversion element 5. Have

On the other hand, the condenser lens 6 has a function of condensing a plurality of split light beams emitted from the second fly's eye lens 4 to polymerize on the liquid crystal panel. In this case, when the degree of condensing of the split light flux by the second fly's eye lens 4 toward the wavelength selective polarization conversion element 5 and the degree of condensing by the condenser lens 6 are compared, little.

By the way, in general, the spectral characteristics of a multilayer film, such as a dichroic film or a polarization separation film, have a strong incidence angle dependence, and a good optical characteristic close to a design characteristic can be obtained for an incidence angle of 45 degrees. As the distance increases, the spectral characteristics tend to shift. In other words, deviation occurs in the wavelength band to be separated.

As mentioned above, the condensing degree of the light beam by the condenser lens 6 is large. For this reason, if the wavelength selective polarization conversion element 5 is arranged on the liquid crystal panel side rather than the condenser lens 6, the first and second wavelength selective polarization separation films 32 constituting the wavelength selective polarization conversion element 5, The spectral characteristics at 34 are shifted. As a result, a large amount of light in a predetermined polarization direction is mixed with each band light incident on each liquid crystal panel, and as a result, the contrast of the projected image is reduced.

For this reason, in this embodiment, the wavelength selective polarization conversion element 5 is disposed between the second fly's eye lens 4 and the condenser lens 6, and the degree of condensing of the incident light beam on the polarization conversion element 5 is determined. It is made small (finally in a state close to parallel light beam).

As a result, good spectral characteristics are obtained in the first and second wavelength selective polarization separation films 32 and 34 constituting the wavelength selective polarization conversion element 5. Therefore, according to this embodiment, it is possible to obtain a projected image with high contrast by using the appropriate spectral characteristics of the wavelength selective polarization conversion element 5.

The arrangement of the wavelength selective polarization conversion element described above between the second fly's eye lens and the condenser lens is the same in the other embodiments described below.

[ Example  2]

5 shows a projection display optical system using the wavelength selective polarization conversion element according to the second embodiment of the present invention.

The light beam emitted from the white light source 301 is converted into parallel light beam by the parabolic reflector 302. This parallel light beam is divided into a plurality of light beams by the first fly's eye lens 303, and each split light beam is focused. Each split light beam is condensed in the vicinity of the second fly's eye lens 304 and the wavelength selective polarization conversion element 305 to form an image of a light source (secondary light source image).

The fly's eye lenses 303 and 304 are constructed by arranging a plurality of lens cells in a two-dimensional direction. Each lens cell has a rectangular lens shape which is similar in shape to a liquid crystal panel described later as an illuminated surface.

The wavelength selective polarization converting element 305 is a linearly polarized light P having light of B and G bands, which are the first and second wavelength bands, of the split light beams exiting the second fly's eye lens 304. Convert to polarized light. Further, light in the R band, which is the third wavelength region, is converted to S-polarized light, which is linearly polarized light having the first polarization direction.

The P-polarized light in the B and G bands and the S polarized light in the R band are emitted by the wavelength selective polarization conversion element 305 and reflected by the mirror 320. Thereafter, the light is condensed by the condenser lens 306, and is a reflective liquid crystal panel (B, G, R liquid crystal panel) 315, for the B band, the G band, and the R band via the color separation / synthesis optical system 307. Each of the lights 310 and 314 overlap each other.

The color separation / synthesis optical system 307 has a dichroic mirror 308 that reflects light in the B band and the R band of the polarized light transmitted through the condenser lens 306 and transmits the G band light. The G-band polarized light transmitted through the dichroic mirror 308 passes through the first polarization beam splitter 309 and enters the reflective G liquid crystal panel 310.

The image light (polarized light) from the G liquid crystal panel 310 is reflected by the first polarization beam splitter 309 and further reflected by the wavelength selective polarization beam splitter 311 and not shown by the projection lens 312. Is not projected on the screen. Here, the wavelength selective polarizing beam splitter 311 transmits the S-polarized light of the B band, reflects the S-polarized light of the G-band, reflects the S-polarized light of the R-band, and transmits the P-polarized light of the R-band.

On the other hand, out of the polarized light of the B band and the R band reflected by the dichroic mirror 308, the B band polarized light passes through the second polarized beam splitter 313, and the R band polarized light is the second polarized beam splitter. Reflected by 313. Thus, the B band polarized light and the R band polarized light emitted from the second polarization beam splitter 313 are focused on the reflective B liquid crystal panel 315 and the R liquid crystal panel 314, respectively.

Reflected by the B liquid crystal panel 315, and modulated B-band polarized light is reflected by the second polarization beam splitter 313. The R band polarized light reflected by the R liquid crystal panel 314 and modulated is transmitted through the second polarization beam splitter 313. Thereafter, light in both wavelength bands is transmitted by the wavelength selective beam splitter 311 and projected onto the screen by the projection lens 312.

Next, the configuration and optical operation of the above-described wavelength selective polarization conversion element 305 will be described in detail with reference to FIG. The overall configuration of the wavelength selective polarization conversion element 305 is the same as that described in the first embodiment using the drawings on the right in FIG. 2, and one polarization conversion cell is enlarged and schematically displayed in FIG. 6.

Reference numeral 41 is a reflecting film. In addition, from the light incidence side, 42 denotes the first wavelength selective polarization separator, 43 denotes the retardation plate, and 44 denote the second wavelength selective polarization separator. Hereinafter, the wavelength selective polarization separator is simply referred to as an optical separation membrane.

The first light separation film 42, the retardation plate 43, and the second light separation film 44 have an inclination of 45 degrees with respect to the direction of the incident axis of light (the direction from the left side to the right side of the drawing). In addition, the reflecting film 41 is arranged in parallel with the first light separation film 42. Moreover, each optical separation film is formed as a multilayer film on the surface of the glass or acrylic board | substrate which is actually a parallel plate. In addition, the retardation plate 43 is formed into a film shape and adhered to the same substrate.

The characteristics of the first light separation membrane 42 and the second light separation membrane 44 are shown in FIGS. 7 and 8, respectively. The first optical separation film 42 has a transmittance of S-polarized light of B-band and G-band light at or near 100% (higher than 50%), and a transmittance of S-polarized light of R-band light at 0% or close to (50). Lower than%).

On the other hand, the second optical separation film 44 has a transmittance of S-polarized light of B-band and G-band light at or near 0% (less than 50%), and a transmittance of S-polarized light of R-band light at 100% or close to it ( Higher than 50%). As described above, the first and second light separation membranes 42 and 44 have the property that the transmittance for S-polarized light is opposite to each other in each wavelength band.

In addition, these first and second optical separation films 42 and 44 have a characteristic of 100% or nearer (more than 50%) transmittance for P-polarized light regardless of the wavelength band.

The retardation plate 43 is a half wave plate and has a function of rotating the polarization direction of incident linearly polarized light by 90 degrees.

White unpolarized light is incident on the wavelength selective polarization conversion element 305 configured as described above from the left side of FIG. The P-polarized light in the R band of the unpolarized light is transmitted through the first light separation film 42 and then converted into S-polarized light through the retardation plate 43, and transmitted through the second light separation film 44 to have wavelength as S-polarized light. It emits from the selective polarization converting element 305.

S-polarized light in the R band is reflected by the first light separation film 42, and further reflected by the reflective film 41, and exits from the wavelength selective polarization conversion element 305 as S-polarized light.

The P-polarized light of the B band and the G band passes through the first light separation film 42, passes through the retardation plate 43, is converted into S-polarized light, and is further reflected by the second light separation film 44. The reflected light is again transmitted through the retardation plate 43 to be converted into P-polarized light, transmitted through the first light separation film 42 and reflected by the reflecting film 41, and thus the wavelength-selective polarization conversion element 305 as P-polarized light. Injection from

In addition, the S-polarized light of the B band and the G band passes through the first light separation film 42, passes through the retardation plate 43, is converted into P polarization, is transmitted by the second light separation film 44, and P It emits from the wavelength selective polarization conversion element 305 as polarized light.

The white unpolarized light incident on the wavelength selective polarization conversion element 305 configured as a single element is converted into P polarization in the B band and G band and S polarization in the R band and emitted from the polarization conversion element 305. Thereby, the effect similar to what was demonstrated in Example 1 can be acquired.

[ Example  3]

9 shows a projection display optical system using the wavelength selective polarization conversion element according to the third embodiment of the present invention.

The light beam emitted from the white light source 401 is converted into parallel light beam by the parabolic reflector 402. This parallel light beam is divided into a plurality of light beams by the first fly's eye lens 403, and each split light beam is focused. Each split light beam is condensed near the second fly's eye lens 404 and the wavelength selective polarization conversion element 405 to form an image of a light source (secondary light source or the like).

The fly's eye lenses 403 and 404 are configured by arranging a plurality of lens cells in a two-dimensional direction. Each lens cell has a rectangular lens shape which is similar in shape to a liquid crystal panel described later as an illuminated surface.

The wavelength selective polarization conversion element 405 is a linearly polarized light P having light of B and R bands, which are the first and third wavelength bands, of the split light beams from the second fly's eye lens 404, and having a second polarization direction. Convert to polarized light. Further, light in the G band, which is the second wavelength region, is converted into S-polarized light, which is linearly polarized light having the first polarization direction.

The P-polarized light of the B and R bands and the S polarized light of the G band emitted from the wavelength selective polarization conversion element 405 are condensed by the condenser lens 406. Reflected by the mirror 407, the reflection type liquid crystal panel (B, G, R liquid crystal panel) 414, 411 for the B band, the G band, and the R band through the color separation / synthesis optical system 408. , 413, respectively, overlapping illumination.

The color separation / synthesis optical system 408 has a polarization beam splitter 409 that transmits light in B and R bands of polarized light and reflects G band light. The G-band polarized light reflected by the polarizing beam splitter 409 passes through the glass block 410 and enters the reflective G liquid crystal panel 411.

The image light (polarized light) from the G liquid crystal panel 411 passes through the glass block 410, passes through the polarizing beam splitter 409, and is projected onto the screen (not shown) by the projection lens 415.

On the other hand, B-polarized light of the B-band and R-band polarized light transmitted through the polarization beam splitter 409 is reflected by the dichroic prism 412, and the R-band polarized light is the dichroic prism 412. Penetrates. Thus, the B-band polarized light and the R-band polarized light emitted from the dichroic prism 412 are focused on the reflective B liquid crystal panel 414 and the R liquid crystal panel 413, respectively.

The B liquid crystal panel 414 is reflected and the modulated B band polarized light is reflected by the dichroic prism 412. In addition, the R band polarized light reflected by the R liquid crystal panel 413 and modulated is transmitted through the dichroic prism 412. Thereafter, light of both wavelength bands is reflected by the polarization beam splitter 409 and projected onto the screen by the projection lens 415.

Next, the configuration and optical operation of the above-described wavelength selective polarization conversion element 405 will be described in detail with reference to FIG. The overall configuration of the wavelength selective polarization conversion element 405 is the same as that described in the first embodiment using the drawings on the right side of FIG. 2, and one polarization conversion cell is enlarged and schematically displayed in FIG. 10.

Reference numeral 51 is a reflecting film. In order from the light incidence side, 52 denotes the first wavelength selective polarization separator, 53 denotes the retardation plate, and 54 denotes the second wavelength selective polarization separator. Hereinafter, the wavelength selective polarization separator is simply referred to as an optical separation membrane.

The first light separation film 52, the retardation plate 53, and the second light separation film 54 have an inclination of 45 degrees with respect to the direction of the incident axis of light (the direction from the left to the right in the drawing). In addition, the reflecting film 51 is arranged in parallel with the first light separation film 52. Moreover, each optical separation film is formed as a multilayer film on the surface of the glass or acrylic board | substrate which is actually a parallel plate. In addition, the retardation plate 53 is formed in a film shape and adhered on the same substrate.

The characteristics of the first light separation membrane 52 and the second light separation membrane 54 are shown in FIGS. 11 and 12, respectively. The first optical separation film 52 has a transmittance for S-polarized light of B-band and R-band light at or near 100% (higher than 50%), and a transmittance of S-polarized light of G-band light at 0% or close to (50). Lower than%).

On the other hand, the second optical separation film 54 has a transmittance of S-polarized light of B band light and R band light at 0% or less (less than 50%), and a transmittance of S-polarized light of G band light at 100% or close to it ( Higher than 50%). As described above, the first and second light separation membranes 52 and 54 have characteristics in which the transmittance for S-polarized light is opposite to each other in each wavelength band.

In addition, these first and second optical separation films 52 and 54 have a characteristic of 100% or nearer (more than 50%) transmittance for P-polarized light regardless of the wavelength band.

The retardation plate 53 is a half wave plate and has a function of rotating the polarization direction of incident linearly polarized light by 90 degrees.

White unpolarized light is incident on the wavelength selective polarization conversion element 405 configured as described above from the left side of FIG.

Among the unpolarized light, P-polarized light in the G band is transmitted through the first light separation film 52 and then converted into S polarization through the retardation plate 53, and is transmitted through the second light separation film 54 to be wavelength selective as S polarization. It exits from the polarization conversion element 405.

S-polarized light in the G band is reflected by the first light separation film 52, and further reflected by the reflective film 51, and exits from the wavelength selective polarization conversion element 405 as S-polarized light.

P-polarized light of the B band and the R band passes through the first light separation film 52, passes through the retardation plate 53, is converted into S polarized light, and is further reflected by the second light separation film 54. The reflected light is again transmitted through the retardation plate 53 to be converted into P polarized light, transmitted through the first light separation film 52 and reflected by the reflecting film 51, and thus, the wavelength selective polarization conversion element 405 as P polarized light. Injection from

In addition, the S-polarized light of the B band and the R band passes through the first light separation film 52, passes through the phase difference plate 53, is converted into P polarization, passes through the second light separation film 54, and P polarized light. As a result, light is emitted from the wavelength selective polarization conversion element 405.

The white unpolarized light incident on the wavelength selective polarization conversion element 405 configured as a single element is converted into P polarization in the B and R bands and S polarization in the G band and is emitted from the polarization conversion element 405. Thereby, the effect similar to what was demonstrated in Example 1 can be acquired.

[ Example  4]

Fig. 13 shows a projection display optical system using the wavelength selective polarization conversion element according to the fourth embodiment of the present invention.

The light beam emitted from the white light source 501 is converted into parallel light beam by the parabolic reflector 502. This parallel light beam is divided into a plurality of light beams by the first fly's eye lens 503, and each split light beam is focused. Each split light beam is condensed near the second fly's eye lens 504 and the wavelength selective polarization conversion element 505 to form an image of a light source (secondary light source image).

The fly's eye lenses 503 and 504 are constituted by a plurality of lens cells arranged in a two-dimensional direction. Each lens cell has a rectangular lens shape which is similar in shape to a liquid crystal panel described later as an illuminated surface.

The wavelength selective polarization conversion element 505 is a linearly polarized light having a first polarization direction and light of B and R bands of the first and third wavelength bands of the split light beams emitted from the second fly's eye lens 504. Convert to polarized light. Further, light in the G band, which is the second wavelength region, is converted into P-polarized light, which is linearly polarized light having a second polarization direction.

S-polarized light in the B and R bands and P-polarized light in the G band emitted from the wavelength selective polarization conversion element 505 are condensed by the condenser lens 506. In addition, transmissive liquid crystal panels (hereinafter, referred to as B, G, and R liquid crystal panels) for the B, G, and R bands through the color separation / synthesis optical system 522 are respectively 519, 521, and 510. Illuminates nestedly.

The color separation / synthesis optical system 522 has a first dichroic mirror 507 that transmits R-band light and reflects B-band light and G-band light. The R-band polarized light transmitted through the first dichroic mirror 507 is reflected by the reflection mirror 508 and enters the R liquid crystal panel 510 through the field lens 509. Light modulated by the R liquid crystal panel 510 (image light) is reflected by the dichroic prism 511 and projected onto a screen (not shown) by the projection lens 512.

Meanwhile, the G band polarized light of the B band polarized light and the G band polarized light reflected by the first dichroic mirror 507 is reflected by the second dichroic mirror 513, and the B band polarized light is Passes through the second dichroic mirror 513. The G-band polarized light reflected by the second dichroic mirror 513 passes through the field lens 520 and enters the G liquid crystal panel 521. The light beam modulated by the G liquid crystal panel 521 passes through the dichroic mirror 511 and is projected onto the screen by the projection lens 512.

Further, the B-band polarized light transmitted through the second dichroic mirror 513 passes through the B liquid crystal panel (B) through the relay lenses 514, 516, the reflection mirrors 515, 517, and the field lens 518. 519). Light modulated by the B liquid crystal panel 315 (image light) is reflected by the dichroic mirror 511 and projected onto the screen by the projection lens 512.

Next, the configuration and optical operation of the above-mentioned wavelength selective polarization conversion element 505 will be described in detail with reference to FIG. The overall configuration of the wavelength selective polarization conversion element 505 is the same as that described in the first embodiment using the drawings on the right side of FIG. 2, and in FIG. 14, one polarization conversion cell is enlarged and schematically displayed.

Reference numeral 61 is a reflecting film. In order from the light incident side, 62 denotes the first wavelength selective polarization separator, 63 denotes the retardation plate, and 64 denotes the second wavelength selective polarization separator. Hereinafter, the wavelength selective polarization separator is simply referred to as an optical separation membrane.

The first light separation film 62, the retardation plate 63, and the second light separation film 64 have an inclination of 45 degrees with respect to the direction of the incident axis of light (the direction from the left side to the right side of the drawing). In addition, the reflecting film 61 is disposed in parallel with the first light separation film 62. Moreover, each optical separation film is formed as a multilayer film on the surface of the glass or acrylic board | substrate which is actually a parallel plate. In addition, the retardation plate 63 is formed in a film shape and adhered on the same substrate.

The characteristics of the first light separation membrane 62 and the second light separation membrane 63 are shown in FIGS. 15 and 16, respectively. The first optical separation film 62 has a transmittance of S-polarized light of B-band and R-band light at or near 0% (less than 50%), and a transmittance of S-polarized light of G-band light is 100% or close to (50). Higher than%).

On the other hand, the second optical separation film 64 has a transmittance of S-polarized light of B band light and R-band light 100% or closer to it (higher than 50%), and a transmittance of S-polarized light of G band light is 0% or close to it ( Lower than 50%). As described above, the first and second light separation membranes 62 and 64 have characteristics in which the transmittance for S-polarized light is reversed in each wavelength band.

In addition, these first and second light separation films 62 and 64 have a characteristic of 100% or nearer (more than 50%) transmittance for P-polarized light regardless of the wavelength band.

The retardation plate 63 is a half-wave plate and has a function of rotating the polarization direction of incident linearly polarized light by 90 degrees.

White unpolarized light is incident on the wavelength selective polarization conversion element 505 configured as described above from the left in FIG. The P-polarized light of the B band and the R band of the unpolarized light is transmitted through the first light separation film 62, is then converted into S polarization through the phase difference plate 63, and is transmitted through the second light separation film 64 to S. As polarized light, light is emitted from the wavelength selective polarization conversion element 505.

S-polarized light of the B and G bands is reflected by the first light separation film 62, and further reflected by the reflective film 61, and exits from the wavelength selective polarization conversion element 505 as S-polarized light.

The P-polarized light in the G band passes through the first light separation film 62, passes through the retardation plate 63, is converted into S-polarized light, and is further reflected by the second light separation film 64. The reflected light is again transmitted through the retardation plate 63 to be converted into P polarized light, transmitted through the first light separation film 62 and reflected by the reflecting film 61, and thus, the wavelength selective polarization conversion element 505 as P polarized light. Injection from

In addition, the S-polarized light of the G band passes through the first light separation film 62, passes through the retardation plate 63, is converted into P-polarized light, and is transmitted by the second light separation film 64, and thus, wavelengths as P-polarized light. It emits from the selective polarization conversion element 505.

The white unpolarized light incident on the wavelength selective polarization conversion element 505 configured as a single element is converted into the S polarization of the B band and the R band and the P polarization of the G band and emitted from the polarization conversion element 505.

Here, in the configuration using the conventional polarization conversion element and the transmissive liquid crystal panel, the polarization direction of the incident linearly polarized light is rotated 90 degrees between the field lens 520 and the G liquid crystal panel 521 shown in FIG. The phase plate is arranged. This is because the G band is P-polarized light and the R and B bands are S-polarized light, so that the light of the spectral characteristics of the dichroic prism shown in FIG. This is because the loss is suppressed.

On the other hand, by using the wavelength selective polarization conversion element 505 of this embodiment, the same effect can be achieved without arranging a phase plate between the field lens 520 and the G liquid crystal panel 521. It is possible.

In addition, in the present embodiment, the case where the R large area, the B large area and the G large area liquid crystal panels 510, 519, and 521 are arranged as shown in Fig. 13 will be described. In this description, the arrangement of the liquid crystal panels for these bands is not limited to this.

As described above, according to the above embodiments, the action of the polarization separation film and the retardation plate having the characteristic that the transmittance of light in the specific polarization direction in the wavelength selective polarization conversion element varies depending on the wavelength range, The first unpolarized light in two wavelength bands and the second unpolarized light in another wavelength band are converted into polarized light having different polarization directions. This makes it possible to realize a polarization conversion element as a single element having a wavelength selective polarization conversion function.

Therefore, it is possible to guide one of the light in the two wavelength ranges from the polarization conversion element and the light in the other wavelength range to the polarizing beam splitter from the same optical path without passing through the conventional wavelength selective retardation plate. Thereby, it is possible to isolate | separate these wavelength range light according to the polarization direction by the said polarizing beam splitter.

For this reason, color separation is performed using a polarizing beam splitter, and the number of optical components of a projection display optical system or an image projecting device for guiding the first to third wavelength light to the corresponding image forming element, respectively, is smaller than before. It is possible. In addition, since the wavelength selective retardation plate becomes unnecessary, the structure for supporting or cooling it is also unnecessary, and the structure of the image projection apparatus can be simplified.

As the wavelength selective polarization conversion element, it is also possible to adopt a configuration other than that described in the above embodiments. For example, in the wavelength band for converting unpolarized light into P-polarized light, the first light separation film is characterized by transmitting P-polarized light and S-polarized light, and the second light separation film is made to transmit S-polarized light by reflecting P-polarized light. . On the other hand, in the wavelength band for converting unpolarized light into S-polarized light, the first light separation film is characterized by transmitting P-polarized light to reflect S-polarized light, and the second light separation film is made to transmit P-polarized light and S-polarized light.

As a result, any one of R, G, and B converts one wavelength band of light into P-polarized light and the other two wavelength bands of light into S-polarized light, or one of them converts one wavelength band of light into S-polarized light. It is possible to convert two wavelength band light into P-polarized light.

In each of the above embodiments, the case where the wavelength selective polarization conversion element has two wavelength selective polarization separation membranes, and only the transmittance with respect to the S polarization of each wavelength selective polarization separation membrane is greatly changed according to the wavelength band has been described. However, as a wavelength selective polarizing separator, the transmittances for S-polarized light and P-polarized light vary greatly depending on the wavelength band (for example, the high and low transmittances for S-polarized light and P-polarized light are reversed in each wavelength band). You may also By using such a wavelength selective polarization separation membrane, by combining one wavelength selective polarization separation membrane and a retardation plate, it is possible to realize a function equivalent to that of the wavelength selective polarization conversion element described in the above embodiments.

In the present embodiment, the case where a reflective liquid crystal panel or a transmissive liquid crystal panel is used as the image forming element has been described. However, in the present invention, another image forming element, for example, a DMD (digital micromirror device) may be used.

Claims (20)

A wavelength selective polarization conversion element for converting unpolarized light including light in a first wavelength region, light in a second wavelength region, and light in a third wavelength region into polarized light, Has a function of separating light by transmission and reflection, and also has a characteristic that the transmittance for light in at least the first polarization direction varies between transmittance higher than 50% and transmittance lower than 50% depending on the wavelength range. Optical separation membrane, Converting the first polarization direction into a second polarization direction orthogonal to the first polarization direction when transmitting the light of the first wavelength region, the light of the second wavelength region and the light of the third wavelength region once; Also having a phase difference plate for converting the second polarization direction to the first polarization direction, The polarization conversion element converts light in two wavelength bands among the first, second and third wavelength bands into polarized light having one polarization direction among the first and second polarization directions, Converts light in one of the second and third wavelength bands into polarized light having the polarization direction of the other of the first and second polarization directions, The optical separation film and the retardation plate is a wavelength selective polarization conversion device, characterized in that formed integrally with each other. The optical separation membrane of claim 1, wherein the optical separation membrane comprises a first light separation membrane and a second light having different wavelength ranges showing a transmittance higher than 50% and a wavelength range lower than 50% with respect to the light in the first polarization direction. With a separator, And the first optical separation film, the retardation plate, and the second optical separation film are arranged in order from the incident side of the light to the polarization conversion element. 3. The first and second optical separation membranes are characterized in that the transmittance of light in the second polarization direction in the first, second and third wavelength ranges is higher than 50%. A wavelength selective polarization conversion element. 4. The first polarization membrane according to claim 3, wherein the first optical separation membrane has a transmittance of less than 50% for light in the first polarization direction in the two wavelength ranges, and the first polarization direction in the other wavelength region. Has a transmittance of more than 50% for light, The second optical separation film has a transmittance of 50% or more for light in the first polarization direction in the two wavelength ranges, and a transmittance for light in the first polarization direction in the other wavelength range. Less than 50%, The light in the first polarization direction in the two wavelength ranges is reflected by the first light separation film and is emitted The light in the second polarization direction in the two wavelength ranges passes through the first light separation membrane, is converted into light in the first polarization direction by the phase difference plate, and then passes through the second light separation membrane. Injection, The light in the first polarization direction in the other wavelength range passes through the first light separation membrane, and is converted into light in the second polarization direction by the phase difference plate, and then transmitted through the second light separation membrane. By injection The light in the second polarization direction in the other wavelength range passes through the first light separation membrane, is converted into light in the first polarization direction by the retardation plate, and then by the second light separation membrane. And reflecting and converting the light into the light in the second polarization direction again by the retardation plate, and then transmitting the light through the first light separation membrane to emit light. 4. The first polarization membrane according to claim 3, wherein the first optical separation membrane has a transmittance of more than 50% for light in the first polarization direction in the two wavelength ranges, and the first polarization direction in the other wavelength region. Has a transmittance of less than 50% for light, The second optical separation film has a transmittance of less than 50% for light in the first polarization direction in the two wavelength ranges, and a transmittance for light in the first polarization direction in the other wavelength range. Higher than 50%, The light in the first polarization direction in the two wavelength bands passes through the first light separation membrane, is converted into light in the second polarization direction by the phase difference plate, and then passes through the second light separation membrane. Injection, The light in the second polarization direction in the two wavelength ranges passes through the first light separation membrane, is converted into light in the first polarization direction by the phase difference plate, and then reflected by the second light separation membrane. After being converted into light in the second polarization direction again by the retardation plate, the light is transmitted through the first optical separation membrane, The light in the first polarization direction in the other wavelength range is reflected by the first light separation film and is emitted The light in the second polarization direction in the other wavelength range passes through the first light separation membrane and is converted into light in the first polarization direction by the phase difference plate, and then passes through the second light separation membrane. Wavelength-selective polarization conversion element, characterized in that the injection. The wavelength selective polarization converting element according to claim 1, further comprising a reflecting surface which reflects light reflected by the optical separation film and is directed toward the exit direction from the polarization converting element. The wavelength selective polarization converting element according to claim 1, further comprising a plurality of polarization conversion cells each comprising the optical separation film and the retardation plate. delete delete delete delete delete According to claim 1, It is formed integrally with the optical separation film and the retardation plate, and provided with a substrate made of glass or acrylic, The optical separation membrane is attached to the substrate, The light impinging on the optical separation film is incident on the polarization conversion element from the substrate, characterized in that the wavelength selective polarization conversion element. A wavelength selective polarization conversion element for converting unpolarized light including light in a first wavelength region, light in a second wavelength region, and light in a third wavelength region into polarized light, The polarization conversion element is sequentially from the incident side of the light, Transmittance with respect to light in the first polarization direction in two wavelength ranges of the first, second, and third wavelength ranges is lower than 50%, and in light in the first polarization direction in the other wavelength region. The transmittance of light is higher than 50%, and the transmittance of light in the second polarization direction in the first, second, and third wavelength bands is higher than 50%, When the light of the first wavelength region, the light of the second wavelength region and the light of the third wavelength region are transmitted once, the first polarization direction is converted into a second polarization direction orthogonal to the first polarization direction, and further A phase difference plate for converting the polarization direction to the first polarization direction, The transmittance with respect to the light in the first polarization direction in the two wavelength ranges is higher than 50%, and the transmittance with respect to the light in the first polarization direction in the other wavelength region is lower than 50%. Has a second optical separation membrane having a characteristic in which the transmittance of light in the second polarization direction in the first, second and third wavelength ranges is higher than 50%, The first and second optical separation film and the retardation plate are integrally formed with each other, The light in the first polarization direction in the two wavelength ranges is reflected by the first light separation film and is emitted. The light in the second polarization direction in the two wavelength ranges passes through the first light separation membrane, is converted into light in the first polarization direction by the retardation plate, and then passes through the second light separation membrane. Injection, The light in the first polarization direction in the other wavelength range is transmitted through the first light separation membrane, and is converted into light in the second polarization direction by the phase difference plate, and then transmitted through the second light separation membrane. By injection The light in the second polarization direction in the other wavelength range passes through the first light separation membrane, is converted into light in the first polarization direction by the retardation plate, and then by the second light separation membrane. And reflecting and converting the light into the light in the second polarization direction again by the retardation plate, and then transmitting the light through the first light separation membrane to emit light. A wavelength selective polarization conversion element for converting unpolarized light including light in a first wavelength region, light in a second wavelength region, and light in a third wavelength region into polarized light, The polarization conversion element is sequentially from the incident side of the light, Transmittance with respect to light in the first polarization direction in two wavelength bands of the first, second and third wavelength bands is higher than 50%, and light in the first polarization direction in another wavelength band A first optical separation membrane having a property of having a transmittance of less than 50% and a transmittance of light of the second polarization direction in the first, second and third wavelength bands of more than 50%, When transmitting the light of the first wavelength band, the light of the second wavelength band and the light of the third wavelength band once, converting the first polarization direction into a second polarization direction orthogonal to the first polarization direction, In addition, the phase difference plate for converting the second polarization direction to the first polarization direction, The transmittance with respect to the light in the first polarization direction in the two wavelength ranges is lower than 50%, the transmittance with respect to the light in the first polarization direction in the other one wavelength region is higher than 50%, A second light separation membrane having a characteristic in which transmittance of light in the second polarization direction in the first, second, and third wavelength ranges is higher than 50%; The first and second optical separation film and the retardation plate are integrally formed with each other, The light in the first polarization direction in the two wavelength ranges passes through the first light separation membrane, is converted into light in the second polarization direction by the phase difference plate, and then passes through the second light separation membrane. Injection, The light in the second polarization direction in the two wavelength ranges passes through the first light separation membrane, is converted into light in the first polarization direction by the retardation plate, and then reflected by the second light separation membrane. After being converted into light in the second polarization direction again by the retardation plate, the light is transmitted through the first light separation membrane, The light in the first polarization direction in the other wavelength range is reflected by the first light separation film and emitted; The light in the second polarization direction in the other wavelength region passes through the first light separation membrane and is converted into light in the first polarization direction by the phase difference plate, and then passes through the second light separation membrane. Wavelength-selective photoelectric conversion element, characterized in that for injection. A wavelength selective polarization conversion element for converting unpolarized light including light in a first wavelength region, light in a second wavelength region, and light in a third wavelength region into polarized light, The conversion element is sequentially from the incident side of the light, A first optical separation membrane having a characteristic in which transmittance with respect to light in the first polarization direction varies between transmittances higher than 50% and transmittances lower than 50% depending on the wavelength range; When transmitting the light of the first wavelength region, the light of the second wavelength region and the light of the third wavelength region once, converting the first polarization direction into a second polarization direction orthogonal to the first polarization direction, and A phase difference plate for converting the second polarization direction to the first polarization direction, And having a second optical separation membrane having a property in which the transmittance of the light in the first polarization direction is changed between transmittance higher than 50% and transmittance lower than 50% according to the wavelength range. A wavelength range where the transmittance of the first light separation membrane with respect to the light in the first polarization direction is higher than 50% and a wavelength range where the transmittance of the second light separation membrane with respect to the light in the first polarization direction is higher than 50% are different from each other, The wavelength range where the transmittance of the first light separation membrane to the light in the first polarization direction is lower than 50% and the wavelength range where the transmittance of the second light separation membrane to the light in the first polarization direction is lower than 50% are different from each other. The first and second optical separation film and the retardation plate are integrally formed with each other, The polarization conversion element converts light in two wavelength regions of the first, second and third wavelength regions into light having one polarization direction among the first and second polarization directions, and A wavelength selective polarization conversion element, characterized in that for converting light to light in a different polarization direction. A first image forming element, a second image forming element, and a third image forming element for each of light in a first wavelength region, light in a second wavelength region, and light in a third wavelength region; 17. The first, second and third image forming elements comprising the wavelength selective polarization converting element according to any one of claims 1 to 7 or 13 to 16, and comprising light from the polarization converting element. An illumination optical system for illuminating; A projection optical system for projecting light emitted from the first, second and third image forming elements, And the polarization converting element converts unpolarized light including light of the first, second and third wavelength bands emitted from the light source into linearly polarized light. 18. The system of claim 17, wherein the illumination optical system comprises: a lens array for dividing unpolarized light into a plurality of light beams; And a condenser lens for condensing luminous flux from said wavelength selective polarization converting element. The image projection apparatus according to claim 17, And an image supply device for supplying an image signal to the image projection device. The wavelength selective polarization conversion device according to any one of claims 1 to 7 or 13 to 16, which converts unpolarized illumination light including light of the first, second and third wavelength bands into polarized light. Illumination optical system comprising a.

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