JP2002350781A - Rear projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rear projector capable of yielding a high-efficiency and high-quality picture by reducing the influence of polarization dependency and incident angle dependency in a screen and a reflection mirror to the utmost. SOLUTION: A part of several color light beams composited by a color synthesizing optical system 15 is a 1st linearly polarized color light beam, and the rest is a 2nd linearly polarized color light beam. Then, the rear projector is equipped with a wavelength selection type phase plate 2G making the polarization directions of the 1st and the 2nd linearly polarized color light beams uniform by changing the polarization direction of either the 1st or the 2nd linearly polarized color light beam to that of the other in an optical path between the optical system 15 and a screen 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projector, and more particularly, to a projection lens which separates light emitted from a light source into a plurality of lights having different polarization directions, modulates the lights, combines them by a cross dichroic prism, and then combines them. The present invention relates to a rear projector that projects a projected image by being incident on the rear side of a screen and transmitting the same to the front side through a system, and is particularly useful for eliminating color unevenness of a projected image projected on a screen.

[0002]

2. Description of the Related Art Generally, a projector includes a front projection type projector for observing a projection surface from the side where an image is projected, and an image projection from the back side using a transmission type screen and a projection surface from the opposite side. There are two types of rear projectors to observe.

[0003] In particular, the rear projector is provided with a transmissive screen at the front of a cabinet, inside which a projection optical system for forming an image to be projected and a transmissive screen for projecting light emitted from the projection optical system. The configuration is arranged.

As the transmission type screen, a screen using a lenticular lens having a groove formed in one direction is mainly used. The lenticular lens has a property that the transmittance of light polarized in a direction perpendicular to the groove is higher than the transmittance of light polarized in a direction parallel to the groove.
For this reason, it is known that, in a transmissive screen, there is a characteristic difference depending on the polarization direction in the projection light that enters from the back side and transmits to the front side.

[0005] In general, a projector separates light emitted from a light source into three colors of green (G), blue (B) and red (R), and separates these colors of light in accordance with image information. After modulation, the light is synthesized by a cross dichroic prism and projected onto a screen.

The cross dichroic prism has four
It has a structure in which two types of wavelength selection films having different wavelength selection characteristics are arranged in an X shape along the interface between two prisms. The cross dichroic prism reflects two colors of light of the three colors by the wavelength selection film, transmits the remaining one color light to the two wavelength selection films, and transmits the two colors of light and the remaining one color. Are emitted in the same direction to combine colors.

[0007] The wavelength selection film of the cross dichroic prism has different characteristics in reflectance or transmittance depending on the polarization direction. Therefore, generally, in a projector, light of a color reflected by the wavelength selection film is converted into S-polarized light with respect to the wavelength selection film, and light of a color transmitted through the wavelength selection film is converted into P light.
There is known a structure in which light is incident on a cross dichroic prism as polarized light, and loss of each color when reflected by a wavelength selection film or transmitted through the wavelength selection film is prevented, thereby increasing light utilization efficiency.

On the other hand, there is also known a rear projector in which a reflection mirror for guiding light emitted from the projection optical system to a transmissive screen for projection is arranged. Since the reflecting mirror is different in principle from light oscillating in a direction perpendicular to the incident surface and light oscillating in a direction parallel to the incident surface, the reflectance of light oscillating in a direction perpendicular to the incident surface is parallel to the incident surface. It has a reflection characteristic of being higher than the reflectance of light oscillating in the direction.

For example, a film mirror in which a reflective film is coated on one surface of a light-transmitting stretched resin film is known as a reflection mirror. This film-shaped mirror is excellent from the viewpoints of weight reduction and ease of handling, but has a property that its extending direction has a great influence on the reflection characteristics.

[0010]

In the above-mentioned conventional rear projector, even if the P-polarized light of the first color and the S-polarized light of the second color enter the dichroic prism, they are combined and emitted. Since the respective polarization directions of the P-polarized light of the first color and the S-polarized light of the second color are preserved, combined light having two polarization directions different by 90 ° is incident on the reflection mirror and the screen. It has become.

However, in the above-mentioned conventional rear projector, when the distance (projection distance) between the color synthesizing optical system or the projection lens system and the screen is reduced, the angle of incidence on the reflection mirror or the screen is widened. The wavelength dependency and the incident angle dependency of the reflectance of the reflection mirror and the transmittance of the screen become remarkable, and there is a problem of causing color unevenness and luminance unevenness on the screen.

Further, between the P-polarized light of the first color and the S-polarized light of the second color, there is a difference in the reflection characteristics of the reflection mirror or film mirror and the transmission characteristics of the screen. If the image projected on the LCD is affected by different characteristics depending on the color, the light use efficiency decreases, and
There is a problem that the color balance is lost. In particular, when partially affected by the relationship with the stretching direction of the film mirror, the color balance collapse appears as a rainbow pattern,
There is a problem that the uniformity of the projected image is significantly impaired.

Therefore, the present invention has been made in view of the above circumstances, and does not cause color unevenness or luminance unevenness on a screen due to wavelength dependency or incident angle dependency even if the projection distance is shortened and the angle is widened. It is another object of the present invention to provide a rear projector capable of obtaining high-efficiency and high-quality images by minimizing the influence of polarization dependence on a screen and a reflection mirror.

[0014]

In order to achieve the above object, a first rear projector according to the present invention includes a light source, a color separation optical system for separating light emitted from the light source into light of a plurality of colors, A plurality of light modulators that respectively modulate the plurality of colors of light separated by the color separation optical system, and a color combining optical system that combines the plurality of colors of light that are respectively modulated by the plurality of light modulators, A projection lens system for projecting the light synthesized by the color synthesis optical system; and a projection system in which light emitted from the projection lens system enters from the back side and is transmitted to the front side. And a screen for projecting as an image, when the light of a plurality of colors synthesized by the color synthesis optical system is light having at least two types of polarization states, And having a polarization state adjusting unit for projecting said screen is disposed in an optical path aligned in polarization state of each color light between the academic system and the screen.

Thus, the polarization state adjusting means can
When the light of a plurality of colors synthesized by the color synthesizing optical system is light having at least two types of polarization states, the polarization state of the light of each color is changed in an optical path between the color synthesizing optical system and the screen. In order to equalize the brightness distribution of the light of each color projected on the screen, color unevenness and brightness unevenness on the screen screen based on the wavelength dependency and the incident angle dependency of the transmittance of the screen and the polarization dependency on the screen. Deter.

Further, it is preferable that when the light projected from the color synthesizing optical system is directly incident on the screen, the screen is arranged at a projection distance where the luminance distribution of the light of each color is different according to the polarization state. .

According to this configuration, when the light projected from the color synthesizing optical system is directly incident on the screen, the screen is arranged at a projection distance in which the luminance distribution of the light of each color differs according to the polarization state. Despite
In order to equalize the polarization state of each color light in the optical path between the color synthesis optical system and the screen, and to make the luminance distribution of each color light projected on the screen the same, the wavelength dependence of the transmittance of the screen In addition, color unevenness and luminance unevenness on the screen screen based on the incident angle dependency and the polarization dependency on the screen are suppressed.

Note that, as described above, the projection distance at which the screen is arranged is such that when the light of a plurality of colors combined by the color combining optical system is light having at least two types of polarization states, When the light projected from the optical system is directly incident on the screen, the distance at which the luminance distribution of the light of each color differs depending on the polarization state.

It is preferable that the projection distance is set in view of the color unevenness accompanying the incident angle dependence of the screen. FIG.
FIG. 6 is a graph showing the relationship. In this graph, the vertical axis represents the color difference ΔE representing the degree of color unevenness, and the horizontal axis represents the incident angle difference [deg] of light incident on the screen, and plots the color difference ΔE according to the incident angle difference.

The color difference ΔE is expressed by two colorimetric values (L ₁ , a ₁ , b ₁ ) and (L ₂ , a ₁ ) in the CIELAB color space.
₂ , b ₂ ) is given by the following equation. ΔE = {(ΔL) ² + (Δa) ² + (Δb) ² } ^0.5 where ΔL = L ₁ −L ₂ , Δa = a ₁ −a ₂ , Δb = b
₁ is a -b _2.

Returning to FIG. 16, the color difference ΔE rapidly increases as the incident angle difference increases. In particular, the color difference ΔE is increasing from the incident angle difference of about 33 deg to exceed about 3.2. The value 3.2 of the color difference ΔE is a value falling within a range of 3.2 to 6.5 defined as a class B tolerance by Japan Color Research Institute. This class B tolerance is a range defined as “a color range that can be treated as the same color at the impression level and is likely to be a color difference”, and is recognized as color unevenness on the screen screen. Range.

Although the above-mentioned conventional rear projector has been demanded to be thin, it is inevitably long projection distance due to the size of the optical parts and the like, and is manufactured so as to have an incident angle difference of about 22 °. I was The incident angle difference 22 °
Shows a small color difference ΔE of about 1.1. This value 1.1 is a value falling within a range of 0.8 to 1.6 specified as an AA class tolerance by Japan Color Research Institute.
The AA class tolerance is a range defined as “a level at which a color difference is felt in adjacent comparison and includes an error range of a general colorimeter”, and is recognized as color unevenness on a screen screen. It is not possible.

That is, in the conventional rear projector, the incident angle difference is inevitably determined as described above.
It was not necessary to manufacture according to the relationship of the color difference ΔE according to the incident angle difference, and it was not recognized as a problem that color unevenness appeared on the screen from the relationship.

Therefore, according to the first rear projector of the present invention, even if the projection distance is shortened and the angle of incidence on the screen is widened as the thickness is reduced, the wavelength dependence, the incident angle dependence, and the polarization Therefore, it is possible to display high-efficiency and high-quality images without causing color unevenness and brightness unevenness on the screen screen. Therefore, according to the present invention, it is possible to provide a thin rear projector without uneven brightness.

Further, the polarization state adjusting means may be arranged so that, when the plurality of colors of light have any polarization direction of linearly polarized light which oscillates in at least two directions within a plane perpendicular to the traveling direction, the linearity in at least two directions. It is preferable to use a wavelength-selective phase difference plate that aligns the polarization direction with any one of the linearly polarized lights. Thus, the wavelength-selective phase difference plate aligns the polarization direction with any one of the linearly polarized lights in at least two directions, so that the effects of the wavelength dependence, the incident angle dependence, and the polarization dependence are reduced. be able to.

Further, the first rear projector of the present invention is further disposed in an optical path between the projection optical system and the screen, and reflects light of a projected image from the projection optical system to the screen. It has a reflection mirror to reach,
The projection optical system may be arranged so that the light whose polarization direction has been aligned by the polarization state adjusting unit becomes S-polarized light with respect to the reflection mirror. Thereby, the reflection efficiency of the light incident on the reflection mirror is improved, and the influence of the polarization dependence of the reflection mirror is reduced as much as possible.

In this case, the light of the plurality of colors has a polarization state of one of linearly polarized light vibrating in two directions orthogonal to each other in a plane perpendicular to the traveling direction, and the light having one linearly polarized light is S-polarized blue and red light for the reflecting surface of the color combining optical system, and light having the other linearly polarized light is P-polarized green light for the reflecting surface of the color combining optical system, The wavelength-selective phase difference plate may convert either the polarization direction of the blue and red light or the polarization direction of the green light. That is, the arrangement of the projection optical system may be changed according to the polarized light to be converted and aligned so that the aligned polarized light becomes S-polarized light with respect to the reflection mirror.

As a result, all the polarized light incident on the reflection mirror becomes S-polarized light, and the reflection characteristics of the reflection mirror can be improved for all three colors. Also, considering that the screen of the rear projector is generally horizontally long, it is preferable that the reflection mirror reflects the image light projected from below or above the reflection mirror toward the screen forward. This arrangement is advantageous in reducing the thickness of the rear projector. Therefore, light that becomes S-polarized light with respect to the reflection mirror becomes light that is polarized in a polarization direction that vibrates in the horizontal direction with respect to the screen, so that the transmission characteristics of the screen can be improved for all three colors.

Further, when the plurality of colors of light have any one of linearly polarized lights which oscillate in at least two directions in a plane perpendicular to the traveling direction, the polarization state adjusting means adjusts any one of the polarization directions. It may be a quarter-wave plate for converting into circularly polarized light. As a result, the quarter-wave plate converts any polarization direction into circularly polarized light, so that the influence of the wavelength dependence, the incident angle dependence, and the polarization dependence can be reduced.

The polarization state adjusting means may be arranged between the color synthesizing optical system and the projection lens system.
Thus, the design of the projection lens system can be performed in consideration of the influence of the polarization state adjusting means. The polarization state adjusting means may be arranged at a stop of the projection lens system. Accordingly, the diameter of the light beam is minimized in the stop portion (including the vicinity of the stop portion) of the projection lens system, so that the polarization state adjusting means can be reduced. Further, the polarization state adjusting means may be arranged in an optical path between the projection lens system and the screen. As a result, it is not necessary to change the configuration of the projection optical system from the light source to the projection lens system, so that a highly versatile optical system can be designed.

A second rear projector according to the present invention includes a light source, a color separation optical system for separating light emitted from the light source into light of a plurality of colors, and the plurality of colors of light separated by the color separation optical system. A plurality of light modulators each modulating light,
A projection optical system including a color combining optical system that combines the plurality of colors of light modulated by the plurality of light modulation devices, and a projection lens system that projects the light combined by the color combining optical system. A screen for projecting the light emitted from the projection lens system from the rear side and transmitting the light to the front side as a projected image, and a screen synthesized by the color synthesizing optical system. When the color light is light having at least two kinds of polarization states, the light is disposed in an optical path between the color combining optical system and the screen to convert the polarization state of each color light into a non-polarization state. It has a polarizing element.

According to the second rear projector, the depolarizing element converts the polarization state of the light of a plurality of colors into a non-polarization state in the optical path between the color combining optical system and the screen. The influence of the dependence, the incident angle dependence and the polarization dependence can be reduced. In addition, when there is a reflection mirror, the influence of the polarization dependence of the reflection mirror is reduced as much as possible.

A third rear projector according to the present invention includes a light source, a color separation optical system for separating light emitted from the light source into light of a plurality of colors, and the plurality of colors of light separated by the color separation optical system. A plurality of light modulators each modulating light,
A projection optical system including a color combining optical system that combines the plurality of colors of light modulated by the plurality of light modulation devices, and a projection lens system that projects the light combined by the color combining optical system. A screen for projecting the light emitted from the projection lens system from the rear side and transmitting the light to the front side as a projected image, and a screen synthesized by the color synthesizing optical system. When the color light is light having at least two types of polarization directions, the light source device includes a polarization rotator that is disposed in an optical path between the color combining optical system and the screen and rotates the polarization direction of each color light. It is characterized by the following.

According to the third rear projector, when the light of the plurality of colors has any one of linearly polarized lights oscillating in at least two directions in a plane perpendicular to the traveling direction, the polarization rotating element is used. Since both polarization directions are rotated, the influence of the wavelength dependence, incident angle dependence and polarization dependence of the screen can be reduced. In addition, when there is a reflection mirror, the influence of the polarization dependence of the reflection mirror is reduced as much as possible.

Further, in the second or third rear projector of the present invention, when the light projected from the color synthesizing optical system is directly incident on the screen, the light of each color according to the polarization state. Are preferably disposed at different projection distances.

According to this structure, when the light projected from the color synthesizing optical system is directly incident on the screen, the screen is arranged at a projection distance in which the luminance distribution of the light of each color differs according to the polarization state. Despite
In order to equalize the polarization state of each color light in the optical path between the color synthesis optical system and the screen, and to make the luminance distribution of each color light projected on the screen the same, the wavelength dependence of the transmittance of the screen In addition, color unevenness and luminance unevenness on the screen screen based on the incident angle dependency and the polarization dependency on the screen are suppressed.

Further, in the projector according to the second or third aspect of the present invention, the depolarizing element or the polarization rotating element may be disposed between the color combining optical system and the projection lens system. Thus, when designing the projection lens system, the design can be performed in consideration of the influence of the depolarizing element or the polarization rotating element. Further, the depolarizing element or the polarization rotating element may be arranged at a stop of the projection lens system. Accordingly, the diameter of the light beam is minimized in the stop portion (including the vicinity of the stop portion) of the projection lens system, so that the depolarizing element or the polarization rotating element can be reduced. Furthermore, the depolarizing element or the polarization rotating element may be arranged in an optical path between the projection lens system and the screen. As a result, it is not necessary to change the configuration of the projection optical system from the light source to the projection lens system, so that a highly versatile optical system can be designed.

Further, in the first, second and third rear projectors according to the present invention, a film made of a light-transmitting stretched resin is provided in an optical path between the projection optical system and the screen. A film mirror provided with a reflection film provided on one surface of the film, and the film mirror may be arranged such that a stretching direction of the film is orthogonal to an incident surface of the film mirror.

Accordingly, since the optical axis of the light emitted from the projection lens system is bent and the light is guided to the screen, the influence of the polarization dependence of the film mirror can be reduced as much as possible. Further, since the attenuation of the color light in the film mirror is reduced, the light use efficiency is improved.

[0040]

An embodiment of a rear projector according to the present invention will be described with reference to the drawings. In FIGS. 4 to 6, 8 to 11, 13 and 14, a line with a double arrow indicates a polarization direction parallel to the drawing, and a symbol with a dot at the center of a white circle is orthogonal to the drawing. It indicates the polarization direction. However, in FIGS. 6 and 10, the symbols attached near the film mirror 3 and the screen 4 are not the polarization directions but the extending direction of the film 31 in the film mirror 3 and the lenticular lens (not shown) in the transmission screen 4. It shall indicate the direction of the groove.

(Embodiment 1) As shown in FIGS. 5 and 6, the rear projector is composed of a projection optical system 1, a reflection mirror 3
Is housed inside the housing 5, and the transmission screen 4 is arranged on the front surface of the housing 5. FIG. 5 is a front view schematically showing a schematic configuration inside the entire rear projector, and FIG. 6 is a right side view thereof. The rear projector according to the present embodiment has a configuration in which light emitted from the projection optical system 1 is reflected by a reflection mirror 3 and is projected on a transmission screen 4 from the back.

FIG. 1 is a schematic plan view showing a main part of the projection optical system 1 of the rear projector according to the first embodiment of the present invention. The projection optical system 1 includes a polarization illumination device 11, a color separation optical system 12, a relay optical system 13, a light modulation device 14R,
14G, 14B, a color combining optical system 15 and a projection lens system 16 are provided. Further, a wavelength-selective phase difference plate 2G is provided in an optical path between the color combining optical system 15 and the screen.

As described above, the projection distance between the color synthesizing optical system 15 and the screen is such that light of a plurality of colors synthesized by the color synthesizing optical system 15 has at least two types of polarization states. In the case of light, when the light projected from the color synthesizing optical system 15 is directly incident on the screen, the distances at which the luminance distribution of the light of each color differs according to the polarization state.

The polarized light illumination device 11 mainly includes a light source 111
And a uniform illumination optical system 112. Uniform illumination optical system 1
12 is a first lens array 113, a second lens array 1
14, polarization conversion element array 115 and superimposing lens 11
6 is provided. The light emitted from the light source 111 is the first light.
The light is split into a plurality of partial light beams by the lens array 113. Each partial light beam is collimated by the second lens array 114 and further converted by the polarization conversion element array 115 into light of one kind of polarization direction whose direction is aligned.

In this embodiment, the light is converted into S-polarized light for the wavelength selection films 152 and 153 of the cross dichroic prism 151 described later. Here, the S-polarized light is a polarized light that oscillates perpendicularly to an incident surface (a surface including the normal to the reflective surface and the central axis of the incident light) on the specific reflecting surface, and the P-polarized light is a light that oscillates perpendicularly to the incident surface. Polarized light that vibrates in parallel. The polarization conversion element array 115 can also convert the wavelength selection films 152 and 153 into light that becomes P-polarized light. The light converted into one type of polarization direction by the polarization conversion element array 115 is
Is superimposed on the illuminated area.

The color separation optical system 12 converts light (natural light) emitted from the light source 111 into light of a plurality of colors, that is, red light.
Separates into green and blue light. Color separation optical system 1
2 is a dichroic mirror 121, 122, mirror 1
23 and collimating lenses 124 and 125.
The light emitted from the polarization illuminating device 11 is separated by the first dichroic mirror 121 into red light and green and blue light. The separated red light is transmitted to the mirror 123
Then, the light enters the light modulation device 14R for red via the first collimating lens 124. On the other hand, the green and blue lights are separated by the second dichroic mirror 122 into green light and blue light. The separated green light enters the green light modulator 14G via the second collimating lens 125. The separated blue light reaches the relay optical system 13.

The relay optical system 13 includes the entrance side lens 1
31, an incident side mirror 132, an intermediate lens 133, an exit side mirror 134, and an exit side lens 135.
The blue light separated by the color separation optical system 12 is incident on the incident side lens 131, the incident side mirror 132, the intermediate lens 133,
The light enters the blue light modulator 14B via the emission mirror 134 and the emission lens 135 in this order.

The light modulators 14R, 14G, 14B
Is composed of, for example, a transmission type liquid crystal device.
FIG. 3 is a plan view showing the vicinity of the light modulators 14R, 14G, 14B and the cross dichroic prism 151 in detail.

Each of the light modulators 14R, 14G, and 14B has a polarization conversion element array 115 as shown in FIG.
The cross dichroic prism 15 described later
Light adjusted to S-polarized light is incident on one of the wavelength selective reflection films 152 and 153. Lens 124, 125, 135
And between the light modulators 14R, 14G, and 14B, in order to further increase the degree of polarization of the light whose polarization direction has been aligned by the polarization conversion element array 115, the incident-side polarizing plates 142R, 142R, and 14G.
142G and 142B are arranged. Incident side polarizing plate 1
42R, 142G, and 142B, each optical modulator 14
Light incident on R, 14G, and 14B undergoes polarization direction modulation according to image information of each color.

On the exit side of each of the light modulators 14R, 14G, 14B, exit-side polarizing plates 143R, 143G,
143B is provided, and of the modulated light, only light that becomes P-polarized light is emitted to the wavelength selective reflection films 152 and 153. P-polarized light is transmitted between the exit-side polarizing plates 143R and 143G and the cross dichroic prism 151 disposed on the exit side of the light modulators 14R and 14B.
Phase difference plates 141R and 141B for converting into polarized light
Are arranged respectively.

Accordingly, the R (red) image light and the B (blue) image light become S-polarized light with respect to the wavelength selection films 152 and 153,
(Green) The cross dichroic prism 151 is in a state where the image light is P-polarized with respect to the wavelength selection films 152 and 153.
Incident on. The positions where the phase difference plates 141R and 141B are arranged are not limited to those of the present embodiment, and the polarization directions of the light incident on each of the light modulators 14R, 14G and 14B,
It can be changed as appropriate according to the characteristics of each of the light modulators 14R, 14G, and 14B.

The color synthesizing optical system 15 comprises a cross dichroic prism 151. The cross dichroic prism 151 includes two types of wavelength selection films 15 having different wavelength selection characteristics along the interface between the four prisms.
2,153 are arranged in an X-shape. G image light passes through these two wavelength selection films 152 and 153, and
The image light and the B image light are reflected by the wavelength selection films 152 and 153, so that three colors of image light are combined.

In this embodiment, the wavelength selection films 152 and 15
R and B image light 3 used as a reflection film are incident as S-polarized light, and G image light used as a transmission film is incident as P-polarized light. Therefore, the wavelength range selected by the wavelength selection films 152 and 153 is widened, so that the light use efficiency can be improved.

As shown in FIG. 2, the retardation of the wavelength-selective phase difference plate 2G (polarization state adjusting means) becomes λ (λ / 2) at half the wavelength λo (550 nm in this embodiment). Wavelength selective type 1 with profile
/ 2 wavelength plate. In the present embodiment, only the polarization direction of the light near the wavelength of 550 nm, that is, the G image light is changed by 90 degrees by the wavelength selection type phase difference plate 2G. Therefore, as shown in FIG. 3, the G image light emitted as P-polarized light from the cross dichroic prism 151 is the same S-polarized light as the R image light and the B image light by the wavelength selection type phase difference plate 2G. Is converted to

The projection lens system 16 comprises one or a plurality of lenses. FIG. 4 is a side view schematically showing a portion near the projection lens system 16 viewed from the side. In the first embodiment, the projection lens system 16 has the reflection surface 161, and the light incident on the projection lens system 16 is reflected by the reflection surface 161, and is reflected in a direction different from the incident direction, here, a direction orthogonal to the incident direction. It is configured to inject. As shown in FIG. 4, the reflecting surface 161 has a function of changing the traveling direction of the light and simultaneously changing the polarization directions of the R image light, the G image light, and the B image light.

The light emitted from the projection optical system 1 described above is reflected by the film mirror 3, enters the screen 4 from the back side, and passes through the screen 4, as shown in FIGS. To form an image.

The film mirror 3 includes a film 31 made of a light-transmitting stretched resin, for example, polyester, and a reflection film 32 deposited on one surface of the film 31. As shown in FIG. 6, the film mirror 3 extends in the stretching direction of the film 31 (as indicated by a symbol with a dot at the center of a white circle,
(Direction perpendicular to the drawing) is attached to the housing 5 such that the positional relationship is perpendicular to the incident surface of the film mirror 3.

The screen 4 is provided with a lenticular lens (not shown), and the housing 5 is arranged such that the groove of the lenticular lens is in the vertical direction (as indicated by a double-headed arrow, a direction parallel to the drawing). Mounted on the front. Further, the projection optical system 1 causes the light emitted from the projection optical system 1 to oscillate in the direction parallel to the surface of the screen 4 and perpendicular to the groove of the lenticular lens with respect to the film mirror 3. It is installed in the lower part of the housing 5 in such a positional relationship that the light becomes polarized light.

Therefore, in this embodiment, the polarization directions of the R image light, the G image light, and the B image light emitted from the projection optical system 1 match the stretching direction of the film 31. The polarization direction of the image light incident on the screen 4 is parallel to the surface of the screen 4 and perpendicular to the groove of the lenticular lens.

That is, according to the above-described first embodiment, the polarization direction of the G image light is converted into the same direction as the polarization directions of the R image light and the B image light by the wavelength selection type phase difference plate 2G, and color synthesis is performed. The R image light, the G image light, and the B image light combined by the optical system 15 enter the film mirror 3 and the screen 4 in a state where the polarization directions are all aligned.

Therefore, according to the rear projector of the first embodiment, since all the color lights enter the film mirror 3 and the screen 4 in the same polarization state, the influence of the polarization dependence of the film mirror 3 and the screen 4 is reduced. As much as possible, the influence of the incident angle dependence can be reduced.

Further, in the present embodiment, the polarization directions of the R image light, the G image light and the B image light emitted from the projection optical system 1 become S-polarized light with respect to the film mirror 3, and Since it is configured to be polarized light that matches the stretching direction and vibrates in a direction parallel to the screen 4 and perpendicular to the groove of the lenticular lens, the reflection efficiency in the film mirror 3 and the transmission in the screen 4 High efficiency. Therefore, it is possible to obtain a high-quality image with high efficiency and without color balance collapse.

Further, the wavelength selection type phase difference plate 2G is
Since it is arranged in the optical path between the color combining optical system 15 and the projection lens system 16, the projection lens system 16 can be designed in consideration of the influence of the wavelength selection type phase difference plate 2G, and high quality can be achieved. Image can be obtained.

(Embodiment 2) FIG. 7 is a schematic plan view showing a main part of a projection optical system of a rear projector according to Embodiment 2 of the present invention. The projection optical system 1001 includes a polarization illumination device 11, a color separation optical system 12, a relay optical system 1,
3, light modulators 14R, 14G, and 14B, a color combining optical system 15, and a projection lens system 1016. In the second embodiment, wavelength-selective retarders 2R and 2B are provided in the optical path between the color combining optical system 15 and the projection lens system 1016 instead of the wavelength-selective retarder 2G. Polarized illumination device 11, color separation optical system 12, relay optical system 13, light modulators 14R, 14G, 14B and color combining optical system 15
Since the configuration and function of are the same as those of the first embodiment, the description is omitted. Further, since the projection lens system 1016 is generally used in a rear projector, the description thereof is also omitted. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The wavelength-selective phase difference plates 2R and 2B have the same profile as that shown in FIG. However, λo is, for example, 610 nm in the wavelength-selective phase plate 2R, and λo in the wavelength-selective phase plate 2B.
Is, for example, 460 nm. Wavelength-selective phase difference plate 2R
Changes only the polarization direction of the R image light by 90 degrees. Similarly,
The wavelength selection type phase difference plate 2B changes only the polarization direction of the B image light by 90 degrees.

Therefore, the R image light and the B image light are
Cross dichroic prism 15 of color combining optical system 15
1 is input as S-polarized light, and a wavelength-selective phase plate 2
The light is converted into P-polarized light by R and 2B. The G image light enters the cross dichroic prism 151 as P-polarized light, and passes through the wavelength-selective phase difference plates 2R and 2B as P-polarized light.

FIG. 8 is a diagram schematically showing this state, and is a plan view showing the light modulators 14R, 14G, 14B, the color combining optical system 15, and the wavelength-selective phase difference plates 2R, 2B. FIG. 9 is a front view schematically showing a schematic internal configuration of the entire rear projector having the projection optical system 1001 having the above-described configuration, and FIG. 10 is a right side view thereof.

The light emitted from the projection optical system 1001 is
The light is reflected by the film mirror 3 and enters the screen 4 from the rear side thereof, and transmits through the screen 4 to form an image. Also in the rear projector of this embodiment, the projection optical system 1001 uses the light (the wavelength selection film 15 of the cross dichroic prism) emitted from the projection optical system 1001.
2,153 becomes P-polarized light with respect to the film mirror 3 and coincides with the stretching direction of the film 31, and is parallel to the screen 4 and parallel to the groove of the lenticular lens. It is installed in the lower part of the housing 5 in a positional relationship such that polarized light oscillates in a vertical direction.

The polarization directions of the R image light and the B image light are converted into the same direction as the polarization direction of the G image light by the wavelength selection type phase difference plates 2 R and 2 B, and the R image light synthesized by the color synthesizing optical system 15. The G image light and the B image light are incident on the film mirror 3 and the screen 4 in a state where the polarization directions thereof are aligned.

Therefore, according to the second embodiment described above, since all the color lights are incident on the film mirror 3 and the screen 4 in the same polarization state, the influence of the polarization dependence of the film mirror 3 and the screen 4 is minimized. Reduce
The influence of the incident angle dependence can also be reduced.

In the present embodiment, in particular, the polarization direction of the image light emitted from the projection optical system 1001 is S-polarized with respect to the film mirror 3 and coincides with the stretching direction of the film 31, and , Since the polarized light oscillates in a direction parallel to the screen 4 and perpendicular to the groove of the lenticular lens,
The reflection efficiency at the film mirror 3 and the transmission efficiency at the screen 4 are also high. Therefore, it is possible to obtain a high-quality image with high efficiency and without color balance collapse.

Further, the wavelength selection type phase difference plates 2R, 2R
B is disposed in the optical path between the color combining optical system 15 and the projection lens system 1016, so that the wavelength selection type retarder 2
The projection lens system 1016 can be designed in consideration of the influence of R and 2B, and a high-quality image can be obtained.

The direction of projection from the projection optical system 1001 is not limited to vertically upward as shown in FIG. 10, but may be obliquely upward. Further, a reflecting surface having an incident surface in a direction parallel to the paper surface of FIG. 10 may be added to further bend the optical path.

(Embodiment 3) In Embodiments 1 and 2 described above, the wavelength selection phase difference plate 2G or 2R, 2B is provided between the color combining optical system 15 and the projection lens system 16 or 1016. Are arranged in the optical path, but it is also possible to arrange this inside the projection lens system.
FIG. 11 is a schematic plan view schematically showing a main part of a rear projector in which a wavelength selection phase difference plate is arranged inside a projection lens system.

In this rear projector, the first embodiment
And the wavelength selection type phase difference plate 2G or the wavelength selection type phase difference plates 2R and 2B in Embodiment 2
6 are arranged at the narrowed portion. Other configurations are the same as those in the first and second embodiments. Therefore, the same components as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted. In the description of the third embodiment and FIGS. 11 and 12, the wavelength-selective phase difference plates 2G, 2R, 2
B is represented as a wavelength-selective phase difference plate 2. Also,
In FIG. 11, the projection lens system 2016 and the screen 4
There is a film mirror 3 (see FIG. 6 and FIG. 10) in the optical path between and, but illustration of the film mirror 3 is omitted.

FIG. 12 is a diagram showing an example of the arrangement of the wavelength-selective phase difference plate 2 when the projection lens system 2016 is a retrofocus type lens system. The retrofocus type projection lens system 2016 includes five lenses including a first lens 61, a second lens 62, a third lens 63, a fourth lens 64, and a fifth lens 65 from the light incident side. It has a configuration. In this case, the projection lens system 20
Since the 16 stop portions are located between the fourth lens 64 and the fifth lens 65, the wavelength-selective phase difference plate 2 is disposed at or near the stop portion. In addition, the projection lens system 2
016 is not limited to the retrofocus type.

As in the present embodiment, the wavelength selection retardation plate 2
Even if is disposed inside the projection lens system 2016, the same effect as in the first and second embodiments can be obtained. Further, in addition to these effects, by arranging the wavelength-selective phase difference plate 2 at the stop of the projection lens system 2016, it is possible to obtain an effect that the wavelength-selection type phase difference plate 2 can be made as small as possible.

The direction for unifying the polarized light is not particularly limited. However, as described in the first and second embodiments, the direction of the S-polarized light with respect to the film mirror 3 is the same as the stretching direction of the film 31. Direction
It is preferable to unify the polarized light so that the polarized light vibrates parallel to the screen 4 and perpendicular to the groove of the lenticular lens.

(Embodiment 4) In Embodiments 1 and 2 described above, the wavelength selection phase difference plate 2G or 2R, 2B is provided between the color combining optical system 15 and the projection lens system 16 or 1016. Are arranged in the optical path between the projection optical system and the film mirror 3.

FIG. 13 is a front view schematically showing a schematic configuration inside the entire rear projector according to the fourth embodiment of the present invention, and FIG. 14 is a right side view thereof. In this rear projector, the wavelength-selective phase difference plates 2R and 2G according to the second embodiment described above are arranged in the optical path between the projection optical system 3001 and the film mirror 3. That is, the projection optical system 3001 is different from the projection optical system 1001 in the second embodiment described above in that
R and 2B are excluded. Wavelength-selective wave plate 2
Are the wavelength-selective phase difference plates 2R and 2B in the second embodiment.
Is the same as The wavelength selection type phase difference plates 2R and 2B
Representatively, it is described as a wavelength selection type retardation plate 2. Other configurations are the same as those of the second embodiment, and therefore, the same components as those of the second embodiment are denoted by the same reference numerals and description thereof will be omitted.

This embodiment is the same as the second embodiment until the S-polarized R image light and B image light and the P-polarized G image light are combined by the cross dichroic prism of the color combining optical system 15. . The combined light is emitted from the projection optical system 3001 via the projection lens system 3016. At this stage, the polarization directions of the R image light and the B image light and the G image light are different. Projection optical system 30
The light emitted from 01 is incident on the wavelength-selective phase difference plate 2, and when transmitted therethrough, the polarization directions of the R image light and the B image light and the polarization direction of the G image light are aligned. Therefore, the light emitted from the projection optical system 3001 becomes polarized light in one direction and reaches the film mirror 3.

According to the above-described fourth embodiment, the same effects as those of the first and second embodiments can be obtained. Further, in addition to these effects, the configuration of the projection optical system 3001 does not need to be changed by disposing the wavelength-selective phase difference plate 2 in the optical path between the projection optical system 3001 and the film mirror 3. Also, the effect that the versatility of the optical system is increased can be obtained.

In the present embodiment, the second
Although the example in which the wavelength-selective phase difference plates 2R and 2B in the embodiment are arranged in the optical path between the projection optical system 3001 and the film mirror 3 has been described, the wavelength-selection type phase difference plate 2G in the first embodiment is projected. Optical system and film mirror 3
May be arranged in the optical path between them.

The direction in which the polarization is unified is not limited. However, as described in the first and second embodiments, the direction of the S-polarized light with respect to the film mirror 3 is the same as the direction in which the film 31 extends. It is preferable that the polarization be uniform so that the polarized light vibrates parallel to the screen 4 and perpendicular to the groove of the lenticular lens.

(Embodiment 5) In Embodiments 1 to 4 described above, the wavelength selection phase difference plates 2, 2G, 2R, and 2B are used as polarization state adjusting means for aligning the polarization state of each color. It is also possible to use a depolarizing element instead of such a polarization state adjusting means. In the rear projector according to the fifth embodiment, a depolarizing element is used instead of the wavelength-selective phase difference plates 2, 2R, 2G, and 2B in the first to fourth embodiments. The depolarizing element converts the polarization of the R image light, the B image light, and the G image light into a non-polarized state. The depolarizing element can be arranged at the same position as the position where the wavelength-selective phase difference plates 2, 2G, 2R, and 2B are arranged in each of the above-described embodiments. For other parts, the above first to fourth embodiments
Since the configuration can be made in the same manner as described above, a detailed description thereof will be omitted.

As an example of the depolarizing element 7, a known Corne pseudo depolarizer is shown in FIG. The depolarizing element 7 is composed of a left crystal part 71 and a right crystal part 72 having a 45-degree inclined surface, and these inclined surfaces are bonded to each other. Left crystal part 71 and right crystal part 7
No. 2 has optically opposite properties. The depolarizing element 7 has a function of converting incident linearly polarized light into a complex and linearly polarized state that continuously changes spatially. Therefore, the R image light, B incident on the depolarizing element 7
The image light and the G image light are both converted into a non-polarized state and emitted.

According to the fifth embodiment, the depolarizing element 7 converts the R image light, the B image light, and the G image light into a non-polarized state.
Similarly to the above, the influence of the polarization dependence of the film mirror or the screen can be reduced as much as possible. Therefore, a high-efficiency and high-quality image can be obtained. Further, similarly to the first or second embodiment, if the depolarizing element 7 is arranged in the optical path between the color combining optical system and the projection lens system, the projection is performed in consideration of the effect of the depolarizing element 7. Since a lens system can be designed, a high-quality image can be obtained. Further, similarly to the third embodiment, the depolarizing element 7
Is arranged at the stop of the projection lens system, the depolarizing element 7 can be made as small as possible. Further, similarly to the fourth embodiment, if the depolarizing element 7 is arranged in the optical path between the projection optical system and the film mirror, the configuration of the projection optical system does not need to be changed. Is obtained.

Furthermore, according to the present embodiment, since the polarization state after conversion has no directionality, there is no restriction on the positional relationship between the projection optical system and the reflection mirror or the screen.

The present invention is not limited to the above-described embodiment, but can be embodied in various modes without departing from the gist thereof. For example, the following modifications are possible. .

(1) In the above embodiment, the light source 11
Although the two lens arrays 113 and 114 that divide one light into a plurality of partial light beams are used, the present invention is also applicable to a projector that does not use such a lens array.

(2) In the embodiment described above, an example of a projector using three light modulators 14R, 14G, and 14B has been described.
One, two, or four or more projectors can be applied.

(3) In the above-described embodiment, an example is described in which the present invention is applied to a rear projector using a transmission type projection optical system. However, the present invention uses a reflection type projection optical system. It can be applied to a rear projector. Here, “transmission type” means that a light modulation device such as a liquid crystal device is a type that transmits light, and “reflection type” is a type that the light modulation device reflects light. Means that. For reflective projection optics,
The cross dichroic prism converts light into red, green, and blue light.
In some cases, it is used as a color light separating unit that separates light into three colors, and also used as a color light combining unit that combines modulated three colors of light again and emits them in the same direction. Even when the present invention is applied to a rear projector using a reflection type projection optical system, the same effects as those of the above-described embodiments can be obtained.

(4) As a reflection mirror, a film mirror has been mainly described, but a glass mirror or a metal mirror can also be used.

(5) The lenticular type screen has been mainly described as the screen. However, other screens such as a bead screen that refracts and diffuses image light using glass beads can be used.

(6) In the above-described first to fourth embodiments, the example in which the wavelength selection type phase difference plate is used as the polarization state adjusting means for aligning the polarization state of each color light has been described. It is also possible to use a quarter wavelength plate instead of this wavelength selection type phase difference plate. The quarter-wave plate converts polarized light of R image light, B image light, and G image light into circularly polarized light. The arrangement position of the quarter-wave plate is the wavelength-selective phase difference plate 2, 2G, 2R,
It is possible to arrange at the same position as the position where 2B was arranged. Other portions can be configured in the same manner as in Embodiments 1 to 4 above.
A detailed description thereof will be omitted.

According to this configuration, since the R image light, the B image light, and the G image light are all converted into circularly polarized light by the quarter-wave plate, the same as in the first to fourth embodiments. In addition, the influence of the polarization dependence of the film mirror or the screen can be reduced as much as possible. Therefore, a high-efficiency and high-quality image can be obtained. Further, similarly to the first or second embodiment, if a quarter-wave plate is arranged in the optical path between the color combining optical system and the projection lens system, the influence of the quarter-wave plate is reduced. Since the projection lens system can be designed in consideration of the above, a high-quality image can be obtained. Further, as in the third embodiment, if a quarter-wave plate is arranged in the diaphragm of the projection lens system, the quarter-wave plate can be made as small as possible. Further, similarly to the fourth embodiment, if the quarter-wave plate is arranged in the optical path between the projection optical system and the film mirror, the configuration of the projection optical system does not need to be changed. The effect of increasing versatility is obtained.

(7) Further, the first to fourth embodiments described above
It is also possible to use a polarization rotating element instead of the polarization state adjusting means (wavelength-selective phase difference plate) in the above. The polarization rotation element has a function of rotating the polarization direction of the polarized light of the R image light, the B image light, and the G image light around the optical axis of each image light. The arrangement position of the polarization rotation element can be arranged at the same position as the position where the wavelength selection phase difference plates 2, 2G, 2R, 2B are arranged in each of the above-described embodiments. For other points, the above-described first to third embodiments are used.
4, the detailed description is omitted.

According to this configuration, the polarization rotator allows
In order to rotate the polarization directions of the R image light, B image light and G image light in a direction in which there is little difference between the reflection characteristics of the film mirror and the transmission characteristics of the screen, and then make each image light incident on the film mirror or the screen. As in the first to fourth embodiments, the influence of the polarization dependence of the film mirror and the screen can be reduced as much as possible. Therefore, a high-efficiency and high-quality image can be obtained. Further, similarly to the first or second embodiment, if the polarization rotator is disposed in the optical path between the color combining optical system and the projection lens system, the projection lens system is considered in consideration of the influence of the polarization rotator. Therefore, a high-quality image can be obtained. Further, similarly to the third embodiment, if the polarization rotator is arranged in the stop of the projection lens system, the polarization rotator can be made as small as possible. Further, similarly to Embodiment 4, if the polarization rotator is arranged in the optical path between the projection optical system and the film mirror, the configuration of the projection optical system does not need to be changed, and the versatility of the optical system is improved. The effect of increasing is obtained.

Further, the rear projector of the present invention can be made thinner in the height direction as described below. FIG. 17 is a schematic diagram illustrating the arrangement of the rear projector of the present invention. (A) shows a case where the incident angle difference is 33 deg.
(B) is a case where the incident angle difference is 20 deg. In any case, the rear projector 171 is
And the light is projected onto the screen at 173.

(A) As shown in FIG.
In the case of, the exit of the rear projector 171 can be arranged above the lower end X of the screen 173 because the projection distance is short. On the other hand, as shown in (b), when the incident angle difference is 20 deg, the exit of the rear projector 171 needs to be disposed below the lower end X of the screen 173 because the projection distance is long. . Therefore, according to the present invention, the rear projector can project a clear image without color unevenness or luminance unevenness even if the projection distance is shortened as in the incident angle difference of 33 deg and the height direction is reduced. become able to.

[0101]

As described above, according to the rear projector of the present invention, even if the projection distance is shortened and the angle of incidence on the screen is widened as the thickness is reduced, the wavelength dependence and the incidence angle dependence are reduced. And the effect of polarization dependency can be suppressed to a small degree, so that an effect that a high-efficiency and high-quality image can be displayed without causing color unevenness or luminance unevenness on the screen screen can be obtained. Therefore, according to the present invention, the effect of being able to provide a thin rear projector having no uneven brightness is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a main part of a projection optical system of a rear projector according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram illustrating a profile of a wavelength-selective phase difference plate provided in the rear projector according to the first embodiment.

FIG. 3 is a plan view schematically showing polarization directions of RGB light beams in the projection optical system of the rear projector according to the first embodiment.

FIG. 4 is a side view schematically showing the polarization directions of RGB color lights in the projection optical system of the rear projector according to the first embodiment.

FIG. 5 is a front view schematically showing a schematic configuration inside the rear projector according to the first embodiment.

6 is a right side view schematically showing a schematic configuration inside the rear projector shown in FIG. 5;

FIG. 7 is a schematic plan view showing a main part of a projection optical system of a rear projector according to a second embodiment of the present invention.

FIG. 8 is a plan view schematically showing polarization directions of RGB color lights in the projection optical system of the rear projector according to the second embodiment.

FIG. 9 is a front view schematically showing a schematic configuration inside the rear projector according to the second embodiment.

FIG. 10 is a right side view schematically showing a schematic configuration inside the rear projector shown in FIG.

FIG. 11 is a schematic plan view showing a main part of a rear projector according to a third embodiment of the present invention.

FIG. 12 is a schematic diagram showing an example of the arrangement of a wavelength-selective phase difference plate in a retrofocus type projection lens system in the rear projector according to the third embodiment.

FIG. 13 is a front view schematically showing a schematic configuration inside a rear projector according to a fourth embodiment.

FIG. 14 is a right side view schematically showing a schematic configuration inside the rear projector shown in FIG.

FIG. 15 is a perspective view showing an example of a depolarizing element used in the rear projector according to the fifth embodiment.

FIG. 16 is a graph showing a relationship between color unevenness due to incident angle dependence of a screen.

FIG. 17 is a schematic diagram illustrating an arrangement of a rear projector according to the present invention.

[Explanation of symbols]

1,1001,2001,3001 Projection optical system 11 Polarized illumination device 111 Light source 112 Uniform illumination optical system 113 First lens array 114 Second lens array 115 Polarization conversion element array 116 Superimposed lens 12 Color separation optical system 121,122 Dichroic mirror 123 Mirrors 124, 125 Parallelizing lens 13 Relay optical system 131 Incident side lens 132 Incident side mirror 133 Intermediate lens 134 Exit side mirror 135 Exit side lens 14R, 14G, 14B Light modulator 15 Color combining optical system 151 Prism 152, 153 Wavelength selection Film 16, 1016, 2016 Projection lens system 161 Reflection surface 2, 2R, 2G, 2B Wavelength-selective phase difference plate (polarization state adjusting means) 3 Film mirror 4 Screen 5 Housing 61, 62, 63, 64, 65 Lens 7 The polarizing element 71 left a crystal unit 72 right crystal portion

Claims (21)

[Claims] A light source; a color separation optical system that separates light emitted from the light source into light of a plurality of colors; and a plurality of lights that respectively modulate the light of the plurality of colors separated by the color separation optical system. A modulating device; a color synthesizing optical system for synthesizing the light of the plurality of colors modulated by the plurality of light modulating devices; and a projection lens system for projecting the light synthesized by the color synthesizing optical system. A rear projection comprising: a projection optical system; and a screen for projecting light emitted from the projection lens system from the rear side and transmitting the light to the front side to project as a projected image. When the light of a plurality of colors to be combined is light having at least two types of polarization states, the lights of the respective colors are arranged in an optical path between the color combining optical system and the screen to align the polarization states of the lights of the respective colors. Rear projector and having a polarization state adjusting unit that. 2. The screen according to claim 1, wherein when the light projected from said color combining optical system is directly incident on said screen, said screen is arranged at a projection distance in which the luminance distribution of light of each color differs according to the polarization state. The rear projector according to claim 1. 3. The method according to claim 1, wherein the polarization state adjusting unit is configured to output the linear light in at least two directions when the light of the plurality of colors has any one of linearly polarized lights oscillating in at least two directions in a plane perpendicular to the traveling direction. The rear projector according to claim 1, wherein the rear projector is a wavelength-selective phase difference plate that aligns the polarization direction with any one of the linearly polarized lights. 4. A polarization mirror disposed in an optical path between the projection optical system and the screen, the reflection mirror reflecting light of a projection image from the projection optical system to reach the screen. The projection optical system according to any one of claims 1 to 3, wherein the projection optical system is arranged so that the light whose polarization direction has been aligned by the state adjusting unit becomes S-polarized light with respect to the reflection mirror. Rear projector. 5. The light of a plurality of colors has a polarization state of one of linearly polarized lights oscillating in two directions orthogonal to each other in a plane perpendicular to the traveling direction. S-polarized blue and red light with respect to the reflecting surface of the combining optical system, and the other light having linear polarization is P-polarized green light with respect to the reflecting surface of the color combining optical system, The rear projector according to claim 4, wherein the wavelength-selective phase difference plate changes only the polarization directions of the blue and red lights. 6. The light of a plurality of colors has a polarization state of one of linearly polarized lights oscillating in two directions perpendicular to each other in a plane perpendicular to the traveling direction. S-polarized blue and red light with respect to the reflecting surface of the combining optical system, and the other light having linear polarization is P-polarized green light with respect to the reflecting surface of the color combining optical system, The rear projector according to claim 4, wherein the wavelength-selective phase difference plate changes only the polarization direction of the green light. 7. The polarization state adjusting means, when the light of the plurality of colors has any polarization direction of linearly polarized light that oscillates in at least two directions in a plane perpendicular to the traveling direction. The rear projector according to claim 1 or 2, wherein the quarter-wave plate converts the light into circularly polarized light. 8. The rear projector according to claim 1, wherein the polarization state adjusting unit is disposed between the color combining optical system and the projection lens system. . 9. The rear projector according to claim 1, wherein the polarization state adjusting unit is disposed at a stop of the projection lens system. 10. The rear projector according to claim 1, wherein the polarization state adjusting unit is disposed in an optical path between the projection lens system and the screen. . 11. A light source, a color separation optical system that separates light emitted from the light source into light of a plurality of colors, and a plurality of lights that respectively modulate the light of the plurality of colors separated by the color separation optical system. A modulating device; a color synthesizing optical system for synthesizing the light of the plurality of colors modulated by the plurality of light modulating devices; and a projection lens system for projecting the light synthesized by the color synthesizing optical system. A projection optical system, and a screen for projecting light emitted from the projection lens system from the rear side and transmitting the light to the front side to project as a projection image, wherein the rear projector includes: When the light of a plurality of colors to be combined is light having at least two types of polarization states, the light is arranged in an optical path between the color combining optical system and the screen to change the polarization state of the light of each color. Rear projector, characterized in that it comprises an anti polarizing element for converting the polarization state. 12. The screen according to claim 1, wherein when the light projected from the color synthesizing optical system is directly incident on the screen, the screen is arranged at a projection distance in which a luminance distribution of light of each color is different according to a polarization state. The rear projector according to claim 11, wherein: 13. The rear projector according to claim 11, wherein the depolarizing element is disposed between the color combining optical system and the projection lens system. 14. The depolarizing element according to claim 11, wherein the depolarizing element is disposed at a stop of the projection lens system.
Or the rear projector according to 12. 15. The rear projector according to claim 11, wherein the depolarizing element is disposed in an optical path between the projection lens system and the screen. 16. A light source, a color separation optical system for separating light emitted from the light source into light of a plurality of colors, and a plurality of lights for modulating the light of the plurality of colors separated by the color separation optical system, respectively. A modulating device; a color synthesizing optical system for synthesizing the light of the plurality of colors modulated by the plurality of light modulating devices; and a projection lens system for projecting the light synthesized by the color synthesizing optical system. A rear projection comprising: a projection optical system; and a screen for projecting light emitted from the projection lens system from the rear side and transmitting the light to the front side to project as a projected image. When the light of a plurality of colors to be combined is light having at least two types of polarization directions, the light is arranged in an optical path between the color combining optical system and the screen to change the polarization direction of the light of each color. Rear projector characterized by having a polarization rotation element for rotation. 17. When the light projected from the color synthesizing optical system is directly incident on the screen, the screen is arranged at a projection distance at which a luminance distribution of light of each color is different according to a polarization state. The rear projector according to claim 16, wherein: 18. The rear projector according to claim 16, wherein the polarization rotation element is disposed between the color combining optical system and the projection lens system. 19. The apparatus according to claim 1, wherein the polarization rotation element is disposed at a stop of the projection lens system.
18. The rear projector according to 6 or 17. 20. The rear projector according to claim 16, wherein the polarization rotation element is disposed in an optical path between the projection lens system and the screen. 21. A light-transmitting stretched resin film in an optical path between the projection optical system and the screen, and a reflection film provided on one surface of the film. 21. A film mirror according to claim 1, further comprising a film mirror, wherein the film mirror is arranged so that a stretching direction of the film is orthogonal to an incident surface of the film mirror. Rear projector.