JP3620509B2 - Rear projector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rear projector, and more specifically, the light emitted from a light source is separated into a plurality of lights having different polarization directions, modulated, synthesized by a cross dichroic prism, and then the back of the screen via a projection lens system. The present invention relates to a rear projector that projects a projected image by being incident from the side and transmitted to the surface side, and is particularly a technique useful for eliminating color unevenness of the projected image projected on the screen.
[0002]
[Prior art]
Generally, there are two types of projectors: a front projection type projector that observes the projection plane from the image projection side, and a rear projector that projects the image from the back side using a transmission screen and observes the projection plane from the opposite side. There are two types.
[0003]
In particular, the rear projector is provided with a transmissive screen on the front surface of the cabinet, and a projection optical system for forming an image to be projected therein and a transmissive screen for projecting light emitted from the projection optical system are arranged. It has become.
[0004]
As the transmissive screen, a screen using a lenticular lens in which grooves are formed along one direction is the mainstream. 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. Therefore, it is known that the transmissive screen has a characteristic difference according to the polarization direction in the projection light that is incident from the back side and is transmitted to the front side.
[0005]
In general, a projector separates light emitted from a light source into light of three colors, green (G), blue (B), and red (R), and modulates the light of those colors according to image information. Later, it is synthesized by a cross dichroic prism and projected onto a screen.
[0006]
The cross dichroic prism 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 of four prisms. This cross dichroic prism reflects two colors of light of three colors by a wavelength selection film and transmits the remaining one color of light through the two wavelength selection films, so that the two colors of light and the remaining one color are transmitted. The light is emitted in the same direction to combine the colors.
[0007]
The wavelength selection film of the cross dichroic prism has a difference in characteristics in reflectance or transmittance depending on the polarization direction. Therefore, in general, in a projector, light of a color reflected by a wavelength selection film is made S-polarized light with respect to the wavelength selection film, and light of a color transmitted through the wavelength selection film is made P-polarized light and incident on a cross dichroic prism. A structure is known in which loss of each color when reflected by a selective film or transmitted through a wavelength selective film is prevented and the utilization efficiency of light is increased.
[0008]
On the other hand, a configuration is also known in which the rear projector is provided with a reflection mirror that leads to a transmissive screen that projects the light emitted from the projection optical system. The reflection mirror is different in principle between light oscillating in a direction perpendicular to the incident surface and light oscillating in a direction parallel to the incident surface, so that the reflectance of light oscillating in the direction orthogonal 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.
[0009]
For example, as a reflection mirror, a film-like mirror in which a reflection film is coated on one surface of a light-transmitting stretched resin film is known. This film-like mirror is excellent from the viewpoints of weight reduction and ease of handling, but has the property that its extending direction has a great influence on the reflection characteristics.
[0010]
[Problems to be solved by the invention]
In the conventional rear projector described above, even if the first color P-polarized light and the second color S-polarized light are incident on the dichroic prism to be combined and emitted, the P-polarized light of the first color is emitted. Since the polarization directions of the light and the S-polarized light of the second color are preserved, the combined light having two polarization directions different by 90 ° is incident on the reflection mirror and the screen.
[0011]
However, in the conventional rear projector, when the distance (projection distance) between the color synthesis optical system or the projection lens system and the screen is shortened, the incident angle to the reflection mirror or the screen becomes wider, and the reflection mirror Since the wavelength dependency and the incident angle dependency of the reflectance and the transmittance of the screen become conspicuous and there is a problem of causing color unevenness and luminance unevenness on the screen, it is not suitable for thinning.
[0012]
Further, there is a difference between the reflection characteristics of the reflection mirror and the film-like mirror and the transmission characteristics of the screen between the P-polarized light of the first color and the S-polarized light of the second color. When an image is affected by different characteristics depending on colors, there is a problem that the light utilization efficiency is lowered and the color balance is lost. In particular, when it is partially affected by the relationship with the extending direction of the film-like mirror, the color balance collapses as a rainbow pattern, and there is a problem that the uniformity of the projected image is significantly impaired.
[0013]
Therefore, the present invention has been made in view of the above circumstances, and even when the projection distance is shortened and the angle is widened, color unevenness and luminance unevenness do not occur on the screen due to wavelength dependency and incident angle dependency. An object of the present invention is to provide a rear projector capable of reducing the influence of polarization dependency on a screen and a reflecting mirror as much as possible and obtaining a high-efficiency and high-quality image.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a first rear projector according to the present invention is separated by a light source, a color separation optical system that separates light emitted from the light source into light of a plurality of colors, and the color separation optical system. A plurality of light modulation devices that respectively modulate the light of the plurality of colors, a color combining optical system that combines the light of the plurality of colors modulated by the plurality of light modulation devices, and the color combining optical system. A projection optical system provided with a projection lens system for projecting light, and a screen for projecting light emitted from the projection lens system from the back side and transmitting it to the front side as a projection image. In the rear projector provided, 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, the color projector is arranged between the color synthesis optical system and the screen. And having a polarization state adjusting unit which is arranged in an optical path aligned in polarization state of each color of light is projected on the screen.
[0015]
Thereby, when the polarization state adjusting means is a light composed of at least two kinds of polarization states, the plurality of colors of light synthesized by the color synthesis optical system is between the color synthesis optical system and the screen. In order to make the luminance distribution of the light of each color projected on the screen uniform by aligning the polarization state of the light of each color in the optical path, the wavelength dependency of the transmittance of the screen, the incident angle dependency, and the polarization dependency of the screen Suppresses color unevenness and brightness unevenness on the screen screen.
[0016]
Further, it is preferable that the screen is disposed at a projection distance in which the luminance distribution of the light of each color differs according to the polarization state when the light projected from the color synthesis optical system is incident on the screen as it is.
[0017]
According to this configuration, when the light projected from the color synthesis optical system is incident on the screen as it is, 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. Nevertheless, the light transmittance of each color projected on the screen is made uniform by aligning the polarization state of the light of each color in the optical path between the color synthesis optical system and the screen. Color unevenness and luminance unevenness on the screen screen based on the wavelength dependency, incident angle dependency, and polarization dependency on the screen.
[0018]
Note that, as described above, the projection distance for arranging the screen is from the color synthesis optical system when the light of a plurality of colors synthesized by the color synthesis optical system is light having at least two kinds of polarization states. When the projected light is incident on the screen as it is, the brightness distribution of the light of each color differs depending on the polarization state.
[0019]
This projection distance is preferably set from the relationship of color unevenness due to the incident angle dependency of the screen. FIG. 16 is a graph showing the relationship. In this graph, the color difference ΔE representing the degree of color unevenness is plotted on the vertical axis, and the incident angle difference [deg] of light incident on the screen is plotted on the horizontal axis, and the color difference ΔE corresponding to the incident angle difference is plotted.
[0020]
The color difference ΔE has two colorimetric values (L and L) in the CIELAB color space.₁, A₁, B₁) And (L₂, A₂, B₂) Is given by:
ΔE = {(ΔL)²+ (Δa)²+ (Δb)²}^0.5
However, ΔL = L₁-L₂, Δa = a₁-A₂, Δb = b₁-B₂It is.
[0021]
Returning to FIG. 16, the color difference ΔE increases rapidly as the incident angle difference increases. In particular, the color difference ΔE is increased from the incident angle difference of about 33 deg to over about 3.2. The value 3.2 of the color difference ΔE is a value that falls within the range 3.2 to 6.5 defined by the Japan Color Research Institute as Class B tolerance. This class B tolerance is a range defined as “a color difference that can be treated as the same color at the impression level and is likely to be a different color”, and is recognized as color unevenness on the screen screen. It is the range to come.
[0022]
By the way, although the conventional rear projector is required to be thin, it has been manufactured so that the projection distance is inevitably long due to the size of the optical component and the like, and the incident angle difference is in the vicinity of 22 °. At the incident angle difference of 22 °, the color difference ΔE shows a small value of about 1.1. This value 1.1 is a value that falls within the range of 0.8 to 1.6 defined by the Japan Color Research Institute as AA class tolerance. This class AA tolerance is a range defined as “an error range in which a color difference is felt in an adjacent comparison and includes instrumental differences of a general colorimeter”, and is recognized as color unevenness on a screen screen. It is a range that cannot be done.
[0023]
That is, in the conventional rear projector, since the incident angle difference is inevitably determined as described above, it is not necessary to manufacture according to the relationship of the color difference ΔE according to the incident angle difference, and color unevenness appears on the screen from the relationship. It was not recognized as a problem.
[0024]
Therefore, according to the first rear projector of the present invention, even if the projection distance is shortened and the incident angle to the screen is widened as the thickness is reduced, the influence of wavelength dependency, incident angle dependency, and polarization dependency is exerted. Therefore, it is possible to display a high-efficiency and high-quality image 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 free from luminance unevenness.
[0025]
In addition, the polarization state adjusting means may include at least one of the two directions of linearly polarized light when the light of the plurality of colors has a polarization direction of linearly polarized light that vibrates in at least two directions within a plane perpendicular to the traveling direction. It is preferable to use a wavelength-selective retardation plate that aligns the polarization direction with any one of the linearly polarized light. As a result, the wavelength-selective retardation plate aligns the polarization direction with any one of at least two linearly polarized lights, so that the influence of wavelength dependence, incident angle dependence, and polarization dependence is kept small. be able to.
[0026]
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 the light of the projection image from the projection optical system to reach the screen. The projection optical system may be arranged so that light having a mirror and whose polarization direction is aligned by the polarization state adjusting means becomes S-polarized light with respect to the reflection mirror. Thereby, since the reflection efficiency of the light incident on the reflection mirror is improved, the influence of the polarization dependency of the reflection mirror is also reduced as much as possible.
[0027]
In this case, the light of the plurality of colors has one polarization state of linearly polarized light that vibrates in two directions orthogonal to each other in a plane perpendicular to the traveling direction, and the light having one linearly polarized light is the color combining optics. S-polarized blue and red light with respect to the reflective surface of the system, and light having the other linearly polarized light is P-polarized green light with respect to the reflective surface of the color synthesis optical system, and the wavelength selection The mold 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 in accordance with the polarized light to be converted and aligned, and the aligned polarized light may be configured as S-polarized light with respect to the reflection mirror.
[0028]
As a result, all polarized light incident on the reflecting mirror becomes S-polarized light, and the reflection characteristics of the reflecting mirror can be improved for all three colors. In consideration of the fact that the screen of the rear projector is generally horizontally long, it is preferable that the reflection mirror reflects image light projected from below or above the reflection mirror forward toward the screen. This arrangement is advantageous in reducing the thickness of the rear projector. Accordingly, the light that becomes S-polarized light with respect to the reflecting mirror becomes light in the polarization direction that oscillates in the horizontal direction with respect to the screen, so that the transmission characteristics of the screen can be improved for all three colors.
[0029]
Further, the polarization state adjusting means may convert any of the polarization directions into circularly polarized light when the light of the plurality of colors has any polarization direction of linear polarization that vibrates in at least two directions within a plane perpendicular to the traveling direction. A quarter-wave plate to be converted may be used. As a result, the quarter-wave plate converts any polarization direction into circularly polarized light, so that the influence of wavelength dependency, incident angle dependency, and polarization dependency can be reduced.
[0030]
The polarization state adjusting means may be disposed between the color synthesis optical system and the projection lens system. Thereby, it is possible to design the projection lens system in consideration of the influence of the polarization state adjusting means. The polarization state adjusting means may be arranged in a diaphragm portion of the projection lens system. As a result, the diameter of the light beam becomes the smallest at the stop portion (including the vicinity of the stop portion) of the projection lens system, so that the polarization state adjusting means can be made small. The polarization state adjusting means may be disposed in an optical path between the projection lens system and the screen. This eliminates the need 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.
[0031]
The second rear projector according to the present invention includes a light source, a color separation optical system that separates light emitted from the light source into light of a plurality of colors, and the light of the plurality of colors separated by the color separation optical system, respectively. A plurality of light modulating devices to be modulated; a color combining optical system for combining the light of the plurality of colors modulated by the plurality of light modulating devices; and a projection lens system for projecting the light combined by the color combining optical system A projection optical system, and a screen for projecting light emitted from the projection lens system from the back side and transmitting the light to the surface side to project as a projection 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, it is arranged in the optical path between the color synthesis optical system and the screen and Characterized in that it has an anti polarizing element for converting the polarization state to non-polarized state.
[0032]
According to the second rear projector, the depolarization element converts the polarization state of the light of the plurality of colors into the non-polarization state in the optical path between the color synthesis optical system and the screen. The influence of the incident angle dependency and the polarization dependency can be reduced. In addition, when there is a reflection mirror, the influence of polarization dependency of the reflection mirror is also reduced as much as possible.
[0033]
The third rear projector of the present invention includes a light source, a color separation optical system that separates light emitted from the light source into light of a plurality of colors, and the light of the plurality of colors separated by the color separation optical system, respectively. A plurality of light modulating devices to be modulated; a color combining optical system for combining the light of the plurality of colors modulated by the plurality of light modulating devices; and a projection lens system for projecting the light combined by the color combining optical system A projection optical system, and a screen for projecting light emitted from the projection lens system from the back side and transmitting the light to the surface side to project as a projection 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 directions, it is arranged in the optical path between the color synthesis optical system and the screen and It characterized by having a polarization rotation element for rotating the polarization direction of.
[0034]
According to the third rear projector, when the light of the plurality of colors has any polarization direction of linearly polarized light that vibrates in at least two directions within a plane perpendicular to the traveling direction, Since the polarization direction is also 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 polarization dependency of the reflection mirror is also reduced as much as possible.
[0035]
In the second or third rear projector of the present invention, when the light projected from the color synthesis optical system is incident on the screen as it is, the luminance distribution of light of each color according to the polarization state. Are preferably arranged at different projection distances.
[0036]
According to this configuration, when the light projected from the color synthesis optical system is incident on the screen as it is, 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. Nevertheless, the light transmittance of each color projected on the screen is made uniform by aligning the polarization state of the light of each color in the optical path between the color synthesis optical system and the screen. Color unevenness and luminance unevenness on the screen screen based on the wavelength dependency, incident angle dependency, and polarization dependency on the screen.
[0037]
Furthermore, in the second or third projector of the present invention, the depolarizing element or the polarization rotating element may be disposed between the color synthesizing optical system and the projection lens system. Thereby, it is possible to design the projection lens system 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 disposed in a diaphragm portion of the projection lens system. As a result, the diameter of the light beam becomes the smallest at 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 made small. Furthermore, the depolarizing element or the polarization rotating element may be disposed in an optical path between the projection lens system and the screen. This eliminates the need 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.
[0038]
Furthermore, in the first, second, and third rear projectors of the present invention, in the optical path between the projection optical system and the screen, a film made of a light-transmitting stretched resin, and one of the films A film mirror provided with a reflective film provided on the surface of the film mirror, and the film mirror may be arranged so that a stretching direction of the film is orthogonal to an incident surface of the film mirror.
[0039]
As a result, the optical axis of the light emitted from the projection lens system is bent and guided to the screen, so that the influence of the polarization dependency 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]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a rear projector according to the present invention will be described with reference to the drawings. 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 shall indicate the polarization direction. However, in FIGS. 6 and 10, the symbols attached in the vicinity of the film mirror 3 and the screen 4 are not the polarization direction but the direction of the film 31 in the film mirror 3 and the lenticular lens (not shown) in the transmission screen 4. The direction of the groove shall be indicated.
[0041]
(Embodiment 1)
As shown in FIGS. 5 and 6, the rear projector is a projector in which the projection optical system 1 and the reflection mirror 3 are housed in a housing 5, and a transmission screen 4 is disposed 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 is configured such that light emitted from the projection optical system 1 is reflected by the reflection mirror 3 and projected onto the transmissive screen 4 from the back side.
[0042]
FIG. 1 is a schematic plan view showing the 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, light modulation devices 14R, 14G, and 14B, a color synthesis optical system 15, and a projection lens system 16. In addition, a wavelength selection type phase difference plate 2G is provided in the optical path between the color synthesis optical system 15 and the screen.
[0043]
Note that, as described above, the projection distance between the color synthesis optical system 15 and the screen is light in which a plurality of colors of light synthesized by the color synthesis optical system 15 have at least two types of polarization states. In this case, when the light projected from the color synthesis optical system 15 is incident on the screen as it is, the luminance distribution of the light of each color is set to a different distance depending on the polarization state.
[0044]
The polarization illumination device 11 mainly includes a light source 111 and a uniform illumination optical system 112. The uniform illumination optical system 112 includes a first lens array 113, a second lens array 114, a polarization conversion element array 115, and a superimposing lens 116. The light emitted from the light source 111 is divided into a plurality of partial light beams by the first 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 having a single polarization direction.
[0045]
In this embodiment, the wavelength selection films 152 and 153 of the cross dichroic prism 151 described later are converted into light that becomes S-polarized light. Here, S-polarized light is polarized light that vibrates perpendicularly to an incident surface (a surface including the normal line of the reflecting surface and the central axis of incident light) on a specific reflecting surface, and P-polarized light is relative to the incident surface. Polarized light oscillating in parallel. Note that the polarization conversion element array 115 can convert the wavelength selection films 152 and 153 into light that becomes P-polarized light. The light converted into one kind of polarization direction by the polarization conversion element array 115 is superimposed on the illuminated area by the superimposing lens 116.
[0046]
The color separation optical system 12 separates light (natural light) emitted from the light source 111 into light of a plurality of colors, that is, light of three colors of red, green, and blue. The color separation optical system 12 includes dichroic mirrors 121 and 122, a mirror 123, and parallel lenses 124 and 125. The light emitted from the polarization illumination device 11 is separated into red light and green and blue light by the first dichroic mirror 121. The separated red light is incident on the red light modulation device 14R via the mirror 123 and the first collimating lens 124. On the other hand, green light and blue light are separated into green light and blue light by the second dichroic mirror 122. The separated green light is incident on the green light modulator 14G via the second collimating lens 125. The separated blue light reaches the relay optical system 13.
[0047]
The relay optical system 13 includes an incident side lens 131, 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 enters the blue light modulation device 14B via the incident side lens 131, the incident side mirror 132, the intermediate lens 133, the exit side mirror 134, and the exit side lens 135 in this order. To do.
[0048]
The light modulation devices 14R, 14G, and 14B are constituted by, for example, a transmissive liquid crystal device. FIG. 3 is a plan view showing in detail the vicinity of the light modulation devices 14R, 14G, and 14B and the cross dichroic prism 151.
[0049]
As shown in FIG. 3, in each of the light modulation devices 14R, 14G, and 14B, the polarization selective element array 115 aligns the S-polarized light with respect to the wavelength selective reflection films 152 and 153 of the cross dichroic prism 151 described later. Light enters. Between the lenses 124, 125, 135 and the light modulators 14R, 14G, 14B, in order to further increase the degree of polarization of the light whose polarization direction is aligned by the polarization conversion element array 115, the incident side polarizing plates 142R, 142G , 142B are arranged. The light that has entered the light modulation devices 14R, 14G, and 14B via the incident-side polarizing plates 142R, 142G, and 142B is modulated in the polarization direction according to the image information of each color.
[0050]
Emission-side polarizing plates 143R, 143G, and 143B are provided on the emission sides of the light modulators 14R, 14G, and 14B, respectively. Of the modulated light, P-polarized light is applied to the wavelength selective reflection films 152 and 153. Only the light that becomes is emitted. Between the exit-side polarizing plates 143R and 143G arranged on the exit side of the light modulators 14R and 14B and the cross dichroic prism 151, retardation plates 141R for converting P-polarized light into S-polarized light. 141B is arranged.
[0051]
Therefore, R (red) image light and B (blue) image light are S-polarized light with respect to the wavelength selection films 152 and 153, and G (green) image light is P-polarized light with respect to the wavelength selection films 152 and 153. Then, the light enters the cross dichroic prism 151. The positions where the phase difference plates 141R and 141B are arranged are not limited to those of the present embodiment, but the polarization direction of the light incident on each of the light modulation devices 14R, 14G and 14B, and each of the light modulation devices 14R, 14G and 14B. It can be appropriately changed according to its own characteristics.
[0052]
The color synthesizing optical system 15 includes a cross dichroic prism 151. In the cross dichroic prism 151, two types of wavelength selection films 152 and 153 having different wavelength selection characteristics are arranged in an X shape along the interface of the four prisms. The G image light passes through the two wavelength selection films 152 and 153, and the R image light and the B image light are reflected by the wavelength selection films 152 and 153, so that the three color image lights are synthesized.
[0053]
In this embodiment, R and B image light using the wavelength selection films 152 and 153 as reflection films 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.
[0054]
As shown in FIG. 2, the wavelength selection type phase difference plate 2G (polarization state adjusting means) has a profile in which the retardation is λ (λ / 2) in the vicinity of the wavelength λo (550 nm in the present embodiment). And a wavelength selective half-wave plate. In the present embodiment, only the polarization direction of light having a wavelength of about 550 nm, that is, 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 the 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 selective phase difference plate 2G. Is converted to
[0055]
The projection lens system 16 is composed of one or a plurality of lenses. FIG. 4 is a side view schematically showing a portion of the vicinity of the projection lens system 16 viewed from the side. In the first embodiment, the projection lens system 16 has a reflecting surface 161, and the light incident on the projection lens system 16 is reflected by the reflecting surface 161 to be different from the incident direction, here, in 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 light and simultaneously changing the polarization direction of R image light, G image light, and B image light.
[0056]
As shown in FIGS. 5 and 6, the light emitted from the projection optical system 1 described above is reflected by the film mirror 3, is incident on the screen 4 from the back side, passes through the screen 4, and passes through the image. Form.
[0057]
The film mirror 3 includes a film 31 made of a light-transmitting stretched resin, such as polyester, and a reflective film 32 deposited on one surface thereof. As shown in FIG. 6, the film mirror 3 is such that the stretching direction of the film 31 (the direction perpendicular to the drawing as indicated by a symbol with a dot at the center of the white circle) is perpendicular to the incident surface of the film mirror 3. It is attached to the housing 5 so as to be in a positional relationship.
[0058]
The screen 4 includes a lenticular lens (not shown), and is attached to the front surface of the housing 5 so that the groove of the lenticular lens is in the vertical direction (the direction parallel to the drawing as indicated by the double arrow symbol). It has been. Further, the projection optical system 1 is such that the light emitted from the projection optical system 1 is s-polarized light with respect to the film mirror 3 and vibrates in a direction parallel to the plane of the screen 4 and perpendicular to the groove of the lenticular lens. It is installed in the lower part of the housing | casing 5 by the positional relationship which becomes the light of the polarization | polarized-light which carries out.
[0059]
Therefore, in the present embodiment, the polarization directions of the R image light, G image light, and B image light emitted from the projection optical system 1 coincide with 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.
[0060]
That is, according to the first embodiment described above, the polarization direction of the G image light is converted to the same direction as the polarization direction of the R image light and the B image light by the wavelength selective phase difference plate 2G, and the color combining optical system 15 The R image light, the G image light, and the B image light synthesized by the above are incident on the film mirror 3 and the screen 4 with the polarization directions aligned.
[0061]
Therefore, according to the rear projector of the first embodiment, 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 dependency of the film mirror 3 and the screen 4 is reduced as much as possible. Also, the influence of the incident angle dependency can be reduced.
[0062]
Furthermore, in the present embodiment, the polarization directions of the R image light, G image light, and B image light emitted from the projection optical system 1 are S-polarized with respect to the film mirror 3, and the stretching direction of the film 3 is Furthermore, 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 in the film mirror 3 and the transmission efficiency in the screen 4 are high. . Therefore, it is possible to obtain a high-quality image that is highly efficient and that does not lose color balance.
[0063]
Furthermore, since the wavelength selection type phase difference plate 2G is disposed in the optical path between the color synthesis optical system 15 and the projection lens system 16, the projection lens takes into consideration the influence of the wavelength selection type phase difference plate 2G. The system 16 can be designed and a high-quality image can be obtained.
[0064]
(Embodiment 2)
FIG. 7 is a schematic plan view showing the main part of the projection optical system of the rear projector according to the second embodiment 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 13, light modulation devices 14R, 14G, and 14B, a color synthesis optical system 15, and a projection lens system 1016. In the second embodiment, wavelength selective phase difference plates 2R and 2B are provided in the optical path between the color synthesizing optical system 15 and the projection lens system 1016 in place of the wavelength selective phase difference plate 2G. Since the configuration and functions of the polarization illumination device 11, the color separation optical system 12, the relay optical system 13, the light modulation devices 14R, 14G, and 14B and the color synthesis optical system 15 are the same as those in the first embodiment, the description thereof is omitted. Further, since the projection lens system 1016 is generally used in a rear projector, description thereof will be omitted. In addition, about the same structure as Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.
[0065]
The wavelength selection type phase difference plates 2R and 2B have the same profile as the profile shown in FIG. However, in the wavelength selection type phase difference plate 2R, λo is, for example, 610 nm, and in the wavelength selection type phase difference plate 2B, λo is, for example, 460 nm. The wavelength selection type 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.
[0066]
Accordingly, the R image light and the B image light are incident on the cross dichroic prism 151 of the color synthesis optical system 15 as S-polarized light, and are converted to P-polarized light by the wavelength selection type phase difference plates 2R and 2B. The G image light enters the cross dichroic prism 151 as P-polarized light, and passes through the wavelength selection type phase difference plates 2R and 2B as P-polarized light.
[0067]
FIG. 8 is a diagram schematically showing this state, and is a plan view showing the light modulation devices 14R, 14G, and 14B, the color synthesis optical system 15, and the wavelength selection type phase difference plates 2R and 2B. FIG. 9 is a front view schematically showing a schematic configuration inside the entire rear projector having the projection optical system 1001 having the above-described configuration, and FIG. 10 is a right side view thereof.
[0068]
The light emitted from the projection optical system 1001 is reflected by the film mirror 3 and enters the screen 4 from the back side thereof, and passes through the screen 4 to form an image. Also in the rear projector of the present embodiment, the projection optical system 1001 is configured such that the light emitted from the projection optical system 1001 (P-polarized light with respect to the wavelength selection films 152 and 153 of the cross dichroic prism) is S with respect to the film mirror 3. The housing 5 is in a positional relationship such that it becomes polarized light, and also coincides with the extending direction of the film 31 and oscillates in a direction parallel to the screen 4 and perpendicular to the groove of the lenticular lens. It is installed at the bottom of.
[0069]
R image light and G image light synthesized by the color synthesizing optical system 15 in which the polarization directions of the R image light and the B image light are converted to the same direction as the polarization direction of the G image light by the wavelength selection type phase difference plates 2R and 2B. And the B image light is incident on the film mirror 3 and the screen 4 in a state where the polarization directions are aligned.
[0070]
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 dependency of the film mirror 3 and the screen 4 is reduced as much as possible. The influence of incident angle dependency can also be reduced.
[0071]
In particular, in the present embodiment, 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 the screen 4 Are polarized so as to oscillate in a direction parallel to and perpendicular to the groove of the lenticular lens, the reflection efficiency in the film mirror 3 and the transmission efficiency in the screen 4 are also high. Therefore, it is possible to obtain a high-quality image that is highly efficient and that does not lose color balance.
[0072]
Furthermore, since the wavelength selection type phase difference plates 2R and 2B are disposed in the optical path between the color synthesis optical system 15 and the projection lens system 1016, the influence of the wavelength selection type phase difference plates 2R and 2B is taken into consideration. Thus, the projection lens system 1016 can be designed, and a high-quality image can be obtained.
[0073]
Note that the projection direction from the projection optical system 1001 is not limited to the vertically upward direction as shown in FIG. Further, a reflection surface having an incident surface in a direction parallel to the paper surface of FIG. 10 may be added to further fold the optical path.
[0074]
(Embodiment 3)
In the first and second embodiments described above, the wavelength selection phase difference plate 2G or 2R, 2B is disposed in the optical path between the color synthesis optical system 15 and the projection lens system 16 or 1016. It is also possible to arrange this inside the projection lens system. FIG. 11 is a schematic plan view schematically showing the main part of the rear projector in which the wavelength selection phase difference plate is arranged inside the projection lens system.
[0075]
In this rear projector, the wavelength selection type phase difference plate 2G or the wavelength selection type phase difference plates 2R and 2B in the first embodiment and the second embodiment are arranged in the diaphragm portion of the projection lens system 2016. Since other configurations are the same as those in the first and second embodiments, 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 selection type phase difference plates 2G, 2R, and 2B are represented as the wavelength selection type phase difference plate 2 as a representative. In FIG. 11, there is a film mirror 3 (see FIGS. 6 and 10) in the optical path between the projection lens system 2016 and the screen 4, but the film mirror 3 is not shown.
[0076]
FIG. 12 is a diagram illustrating an arrangement example of the wavelength selection type 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, since the aperture portion of the projection lens system 2016 is located between the fourth lens 64 and the fifth lens 65, the wavelength selection type phase difference plate 2 is disposed at or near the aperture portion. The projection lens system 2016 is not limited to the retrofocus type.
[0077]
Even when the wavelength selection phase difference plate 2 is disposed inside the projection lens system 2016 as in the present embodiment, the same effects as those of the first and second embodiments can be obtained. Further, in addition to these effects, the wavelength selective phase difference plate 2 is arranged in the aperture portion of the projection lens system 2016, so that the wavelength selective phase difference plate 2 can be made as small as possible.
[0078]
In addition, although it does not restrict | limit in particular about the direction which unifies polarization | polarized-light, As already demonstrated in Embodiment 1 and 2, it becomes a direction which corresponds with the extending | stretching direction of the light of S-polarized light and the film 31 with respect to the film mirror 3, It is preferable to unify the screen 4 so that the polarized light oscillates in parallel with the lenticular lens and perpendicular to the groove of the lenticular lens.
[0079]
(Embodiment 4)
In the first and second embodiments described above, the wavelength selection phase difference plate 2G or 2R, 2B is disposed in the optical path between the color synthesis optical system 15 and the projection lens system 16 or 1016. It is also possible to arrange this in the optical path between the projection optical system and the film mirror 3.
[0080]
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 selection type 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 obtained by removing the wavelength selection phase difference plates 2R and 2B from the projection optical system 1001 in the second embodiment described above. The wavelength selection type phase difference plate 2 is the same as the wavelength selection phase difference plates 2R and 2B in the second embodiment. The wavelength selection type phase difference plates 2R and 2B are represented as wavelength selection type phase difference plates 2 as representatives. Since other configurations are the same as those in the second embodiment, the same components as those in the second embodiment are denoted by the same reference numerals and description thereof is omitted.
[0081]
This embodiment is the same as the second embodiment until the S-polarized R image light and the 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 through the projection lens system 3016. At this stage, the R image light, the B image light, and the G image light have different polarization directions. The light emitted from the projection optical system 3001 enters the wavelength-selective phase difference plate 2 and passes through it, so that the polarization directions of the R image light and B image light and the polarization direction of the G image light are aligned. Therefore, the light emitted from the projection optical system 3001 reaches the film mirror 3 as unidirectional polarized light.
[0082]
According to the fourth embodiment described above, the same effects as those of the first and second embodiments can be obtained. Further, in addition to these effects, the wavelength-selective retardation plate 2 is disposed in the optical path between the projection optical system 3001 and the film mirror 3, so that the configuration of the projection optical system 3001 does not have to be changed. Also, the effect of increasing the versatility of the optical system can be obtained.
[0083]
In the present embodiment, the wavelength selection type phase difference plates 2R and 2B in the second embodiment described above have been described in the optical path between the projection optical system 3001 and the film mirror 3; The wavelength selection type phase difference plate 2G according to the embodiment may be disposed in the optical path between the projection optical system and the film mirror 3.
[0084]
Although the direction for unifying the polarization is not limited, as already described in the first and second embodiments, the film mirror 3 has a direction that coincides with the S-polarized light and the stretching direction of the film 31, and the screen 4 It is preferable to unify so that the polarized light oscillates in parallel and perpendicular to the groove of the lenticular lens.
[0085]
(Embodiment 5)
In the first to fourth embodiments described above, the wavelength selection phase difference plates 2, 2G, 2R, and 2B are used as the polarization state adjusting means for aligning the polarization states of the respective colors. Instead of such a polarization state adjusting means. It is also possible to use a depolarizing element. In the rear projector according to the fifth embodiment, a depolarizing element is used instead of the wavelength selection type phase difference plates 2, 2R, 2G, and 2B in the first to fourth embodiments. The depolarizing element converts the polarization of R image light, B image light, and G image light into a non-polarized state. The arrangement position of the depolarizing 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 the above-described embodiments. Since other portions can be configured in the same manner as in the first to fourth embodiments, detailed description thereof is omitted.
[0086]
As an example of the depolarizing element 7, a known Cornu pseudo-depolarizer is shown in FIG. The depolarizing element 7 is composed of a left crystal portion 71 and a right crystal portion 72 having a 45 ° slope, and the slopes are bonded to each other. The left crystal unit 71 and the right crystal unit 72 have optically opposing properties. The depolarizing element 7 has a function of converting incident linearly polarized light into a linearly polarized state that is complex and changes spatially continuously. Accordingly, the R image light, B image light, and G image light incident on the depolarizing element 7 are all converted into a non-polarized state and emitted.
[0087]
According to the fifth embodiment, since the R image light, the B image light, and the G image light are all converted into a non-polarized state by the depolarizing element 7, as in the first to fourth embodiments, The influence of the polarization dependency of the film mirror or screen can be reduced as much as possible. Therefore, a highly efficient and high quality image can be obtained. Similarly to the first embodiment or the second embodiment, if the depolarizing element 7 is arranged in the optical path between the color synthesizing optical system and the projection lens system, the influence of the depolarizing element 7 is taken into consideration for projection. Since the lens system can be designed, a high-quality image can be obtained. Similarly to the third embodiment, the depolarizing element 7 can be made as small as possible by disposing the depolarizing element 7 in the stop portion of the projection lens system. 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, it is not necessary to change the configuration of the projection optical system. The effect of increasing is obtained.
[0088]
Furthermore, according to the present embodiment, since there is no directionality in the polarization state after conversion, there is no restriction on the positional relationship between the projection optical system and the reflection mirror or screen.
[0089]
The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0090]
(1) In the above-described embodiment, the two lens arrays 113 and 114 that divide the light of the light source 111 into a plurality of partial light beams are used. However, the present invention is applicable to a projector that does not use such a lens array. Applicable.
[0091]
(2) In the above-described embodiment, an example of a projector using three light modulation devices 14R, 14G, and 14B has been described. However, the present invention is for one, two, or four or more light modulation devices. It can also be applied to projectors that have been used.
[0092]
(3) In the above-described embodiment, an example in which the present invention is applied to a rear projector using a transmissive projection optical system has been described. However, the present invention is applied to a rear projector using a reflective projection optical system. Can also be applied. Here, “transmission type” means that a light modulation device such as a liquid crystal device transmits light, and “reflection type” is a type in which the light modulation device reflects light. It means that. In the case of a reflective projection optical system, the cross dichroic prism is used as color light separating means for separating light into three colors of red, green, and blue, and the same is obtained by synthesizing the modulated three colors of light again. In some cases, it is also used as color light combining means for emitting light in the direction of. Even when the present invention is applied to a rear projector using a reflective projection optical system, the same effects as those of the above-described embodiments can be obtained.
[0093]
(4) Although the description has been made centering on the film mirror as the reflection mirror, a glass mirror or a metal mirror can also be used.
[0094]
(5) As the screen, the description has focused on a lenticular type screen, but other screens such as a bead screen that refracts and diffuses image light using glass beads can also be used.
[0095]
(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 unit that aligns the polarization state of the light of each color has been described. It is also possible to use a quarter wave plate in place of the mold phase difference plate. The quarter wave plate converts the polarized light of R image light, B image light, and G image light into circularly polarized light. The quarter-wave plate can be arranged at the same position as the position where the wavelength-selective phase difference plates 2, 2G, 2R, 2B are arranged in the above-described embodiments. Since other portions can be configured in the same manner as in the first to fourth embodiments, detailed description thereof is omitted.
[0096]
According to this configuration, since the R-wave light, the B-image light, and the G-image light are all converted into circularly polarized light by the quarter-wave plate, the film is the same as in the first to fourth embodiments. The influence of the polarization dependency of the mirror and the screen can be reduced as much as possible. Therefore, a highly efficient and high quality image can be obtained. Similarly to the first embodiment or the second embodiment, if the quarter-wave plate is disposed in the optical path between the color synthesis optical system and the projection lens system, the influence of the quarter-wave plate is affected. Since the projection lens system can be designed in consideration, a high-quality image can be obtained. Similarly to the third embodiment, the quarter-wave plate can be made as small as possible by disposing the quarter-wave plate in the aperture section of the projection lens system. Similarly to the fourth embodiment, if the quarter-wave plate is disposed in the optical path between the projection optical system and the film mirror, it is not necessary to change the configuration of the projection optical system. The effect that versatility increases can be obtained.
[0097]
(7) Furthermore, instead of the polarization state adjusting means (wavelength selection type phase difference plate) in the first to fourth embodiments described above, a polarization rotation element can be used. The polarization rotation element has a function of rotating the polarization direction of the polarized light of R image light, B image light, and 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 the above-described embodiments. Since other portions can be configured in the same manner as in the first to fourth embodiments, detailed description thereof is omitted.
[0098]
According to this configuration, the polarization direction of the R image light, the B image light, and the G image light is rotated by the polarization rotation element in a direction in which a difference in the reflection characteristics of the film mirror and the transmission characteristics of the screen is unlikely to occur. Is incident on the film mirror and the screen, the influence of the polarization dependency of the film mirror and the screen can be reduced as much as possible in the same manner as in the first to fourth embodiments. Therefore, a highly efficient and high quality image can be obtained. Similarly to the first embodiment or the second embodiment, if the polarization rotation element is arranged in the optical path between the color synthesis optical system and the projection lens system, the projection lens system takes into account the influence of the polarization rotation element. Therefore, a high-quality image can be obtained. Similarly to the third embodiment, the polarization rotator can be made as small as possible by disposing the polarization rotator in the aperture section of the projection lens system. Similarly to the fourth embodiment, if the polarization rotation element is arranged in the optical path between the projection optical system and the film mirror, it is not necessary to change the configuration of the projection optical system. The effect of increasing is obtained.
[0099]
Further, the rear projector of the present invention can be thinned in the height direction as follows. FIG. 17 is a schematic diagram for explaining the arrangement of the rear projector of the present invention. (A) is a case where the incident angle difference is 33 deg, and (b) is a case where the incident angle difference is 20 deg. In either case, the rear projector 171 emits light to the reflection mirror 172 and projects it onto the screen 173.
[0100]
As shown in (a), in the case of an incident angle difference of 33 deg, the exit of the rear projector 171 can be disposed 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 port 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 having no color unevenness and brightness unevenness even if the projection distance is shortened and the height direction is reduced as in the incident angle difference 33 deg. become able to.
[0101]
【The invention's effect】
As described above, according to the rear projector of the present invention, even if the projection distance is shortened and the incident angle on the screen is widened as the thickness is reduced, the wavelength dependency, the incident angle dependency, and the polarization dependency are reduced. Since the influence can be suppressed to a small level, an effect of displaying a high-efficiency and high-quality image without causing color unevenness and luminance unevenness on the screen screen can be obtained. Therefore, according to the present invention, it is possible to provide a thin rear projector having no luminance unevenness.
[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 invention.
FIG. 2 is a characteristic diagram showing a profile of a wavelength selection type 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 in the projection optical system of the rear projector according to the first embodiment.
FIG. 4 is a side view schematically showing polarization directions of RGB light 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 of the interior of 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.
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 light 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 a rear projector according to a second embodiment;
10 is a right side view schematically showing a schematic configuration inside the rear projector shown in FIG. 9. FIG.
FIG. 11 is a schematic plan view showing a main part of a rear projector according to a third embodiment of the invention.
FIG. 12 is a schematic diagram illustrating an arrangement example of wavelength selection type phase difference plates 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 of the interior of a rear projector according to a fourth embodiment.
14 is a right side view schematically showing a schematic configuration inside the rear projector shown in FIG. 13. FIG.
FIG. 15 is a perspective view illustrating an example of a depolarizing element used in a rear projector according to a fifth embodiment.
FIG. 16 is a graph showing the relationship of color unevenness due to the incident angle dependency of the screen.
FIG. 17 is a schematic diagram illustrating the 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 Superimposing lens
12 color separation optical system
121,122 Dichroic mirror
123 mirror
124,125 Parallelizing lens
13 Relay optical system
131 Incident side lens
132 Incident side mirror
133 Intermediate lens
134 Ejector side mirror
135 Exit lens
14R, 14G, 14B light modulator
15 color synthesis optical system
151 prism
152,153 Wavelength selective film
16, 1016, 2016 Projection lens system
161 reflective surface
2,2R, 2G, 2B Wavelength selection type phase difference plate (polarization state adjusting means)
3 Film mirror
4 screens
5 Case
61, 62, 63, 64, 65 Lens
7 Depolarizer
71 Left crystal part
72 right crystal part

Claims (12)

A light source;
A color separation optical system that separates light emitted from the light source into light of a plurality of colors;
A plurality of light modulation devices that respectively modulate the light of the plurality of colors separated by the color separation optical system;
A color combining optical system for combining the light of the plurality of colors modulated by the plurality of light modulation devices;
A projection lens system for projecting light synthesized by the color synthesis optical system;
A projection optical system comprising:
A screen for projecting the light emitted from the projection lens system as a projected image by being incident from the back side and transmitted to the surface side;
In the rear projector with
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, it is arranged in an optical path between the color synthesis optical system and the screen, and the light of each color Having a polarization state adjusting means for aligning the polarization state;
A rear projector, characterized in that the polarization state adjusting means is disposed at a position where the diameter of the light beam is minimized in the stop portion of the projection lens system. 2. The screen according to claim 1, wherein when the light projected from the color synthesizing optical system is incident on the screen as it is, the screen is disposed at a projection distance in which the luminance distribution of the light of each color differs according to the polarization state. The described rear projector. The polarization state adjusting means may be any one of the linearly polarized light in at least two directions when the light of the plurality of colors has any polarization direction of linearly polarized light that vibrates in at least two directions within a plane perpendicular to the traveling direction. 3. The rear projector according to claim 1, wherein the wavelength selection type phase difference plate aligns the polarization direction with one linearly polarized light. And a reflection mirror that is disposed in an optical path between the projection optical system and the screen and reflects light of a projection image from the projection optical system to reach the screen.
4. The projection optical system according to claim 1, wherein the projection optical system is arranged so that light whose polarization direction is aligned by the polarization state adjusting means becomes S-polarized light with respect to the reflection mirror. The described rear projector. The light of the plurality of colors has a polarization state of linearly polarized light that vibrates in two directions orthogonal to each other in a plane perpendicular to the traveling direction,
The light having one linearly polarized light is S-polarized blue and red light with respect to the reflection surface of the color synthesis optical system,
The other linearly polarized light is P-polarized green light with respect to the reflecting surface of the color synthesis optical system,
The rear projector according to claim 4, wherein the wavelength selection type phase difference plate converts only the polarization direction of the blue and red light. The light of the plurality of colors has a polarization state of linearly polarized light that vibrates in two directions orthogonal to each other in a plane perpendicular to the traveling direction,
The light having one linearly polarized light is S-polarized blue and red light with respect to the reflection surface of the color synthesis optical system,
The other linearly polarized light is P-polarized green light with respect to the reflecting surface of the color synthesis optical system,
The rear projector according to claim 4, wherein the wavelength selection type phase difference plate converts only a polarization direction of the green light. The polarization state adjusting means converts any polarization direction into circularly polarized light when the light of the plurality of colors has any polarization direction of linearly polarized light that vibrates in at least two directions within a plane perpendicular to the traveling direction. The rear projector according to claim 1, wherein the rear projector is a quarter-wave plate. A light source;
A color separation optical system that separates light emitted from the light source into light of a plurality of colors;
A plurality of light modulation devices that respectively modulate the light of the plurality of colors separated by the color separation optical system;
A color combining optical system for combining the light of the plurality of colors modulated by the plurality of light modulation devices;
A projection lens system for projecting light synthesized by the color synthesis optical system;
A projection optical system comprising:
A screen for projecting the light emitted from the projection lens system as a projected image by being incident from the back side and transmitted to the surface side;
In the rear projector with
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, it is arranged in an optical path between the color synthesis optical system and the screen, and the light of each color It has a depolarizing element that converts the polarization state into a non-polarization state,
A rear projector, wherein the depolarizing element is disposed at a position where the diameter of a light beam becomes the smallest in the stop portion of the projection lens system. 9. The screen according to claim 8, wherein when the light projected from the color synthesizing optical system is incident on the screen as it is, the screen is arranged at a projection distance where the luminance distribution of the light of each color differs according to the polarization state. The described rear projector. A light source;
A color separation optical system that separates light emitted from the light source into light of a plurality of colors;
A plurality of light modulation devices that respectively modulate the light of the plurality of colors separated by the color separation optical system;
A color combining optical system for combining the light of the plurality of colors modulated by the plurality of light modulation devices;
A projection lens system for projecting light synthesized by the color synthesis optical system;
A projection optical system comprising:
A screen for projecting the light emitted from the projection lens system as a projected image by being incident from the back side and transmitted to the surface side;
In the rear projector with
When the light of a plurality of colors synthesized by the color synthesis optical system is light having at least two types of polarization directions, it is arranged in an optical path between the color synthesis optical system and the screen, and the light of each color A polarization rotation element that rotates the polarization direction;
A rear projector, characterized in that the polarization rotation element is disposed at a position where the diameter of the light beam is minimized in the stop portion of the projection lens system. 11. The screen according to claim 10, wherein when the light projected from the color synthesizing optical system is incident on the screen as it is, 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. The described rear projector. And a film mirror including a film made of a light-transmitting stretched resin and a reflective film provided on one surface of the film in an optical path between the projection optical system and the screen. ,
The rear projector according to any one of claims 1 to 11, wherein the film mirror is arranged so that a direction in which the film extends is orthogonal to an incident surface of the film mirror.

Images