JP2003287818A - Reflective screen, front surface projection display device, illuminator and display system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the contrast of a display picture by suppressing the effect of external light in a display system comprising a combination of a front surface projection display device and a reflective screen. <P>SOLUTION: The reflective screen to which the projection light from the front surface projection display device is projected is made to be a cholesteric liquid crystal layer and the property of selectively reflecting the circularly polarized light of the specified direction is imparted to the reflective screen. Further, the circularly polarized light of the specified direction which is selectively reflected by the cholesteric liquid crystal layer in the reflection type screen is set for the front surface projection display device. Thereby, such an operation that the circularly polarized light of the same specified direction with the projection light from the front surface projection display device is reflected and the light other than the circularly polarized light is not reflected is obtained with the reflection type screen. That is, the projection light is advantageously reflected, the effect of the external light is suppressed and the contrast of the display picture is improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type screen for displaying an image by projecting projection light from the front side, a front projection type display device for projecting the projection light onto the reflection type screen, and these reflection type screens. The present invention relates to a lighting device provided in a room provided with a screen and a front projection display device. The present invention also relates to a display system including at least a reflective screen and a front projection display device.

[0002]

2. Description of the Related Art In recent years, as a display device, a projection type display device, which is a so-called projector, which is adapted to obtain a large-screen image display by projecting projection light according to an image on a screen, has become widespread.

A front projection display device, a so-called front projector, is known as one of such projectors. This front projector displays an image by projecting projection light from the front side of the reflective screen.

As a reflection type screen used with such a front projector, a white screen, a metal screen, a bead screen and the like have been put into practical use.

The white screen is very common as a reflection type screen, and for example, a white resin sheet having a plain surface is used for the reflection surface. As this white screen, a white resin sheet whose surface is subjected to plain or matte processing is known.

The metal screen is formed by laminating a resin layer containing a diffusing material or a film having a matte finish on the metal reflecting layer. Further, the bead screen has a diameter of, for example, 0.05 mm (50 μm) on the surface of the white resin sheet or the reflective layer such as aluminum.
It is constructed by spreading glass beads of about m).

[0007]

By the way, when performing image display using the projection type display device (front projector) as described above and a reflection type screen such as a white screen, a metal screen, or a bead screen, However, there is a problem that the contrast, which is one of the quality of the displayed image, is lowered due to the influence of external light.
That is, in a bright environment around the reflective screen, external light is reflected by the reflective screen and enters the pupil of the observer, and a sufficient contrast cannot be obtained for the displayed image.

Consider, for example, a case where the display system including the above-described front projector and reflective screen is installed indoors (indoors). In this case, in addition to the projection light from the front projector, so-called outside light also reaches the reflective screen indoors.
That is, for example, outdoor light such as sunlight or indoor illumination light emitted from a lighting fixture or the like reaches the reflection type screen and is reflected by the reflection type screen.

As described above, the brightness of the reflected light of the external light reflected by the reflective screen is displayed on the reflective screen in an environment where the brightness of the reflected light from the front projector is correspondingly bright. It becomes impossible to obtain a sufficient contrast for the image.

Therefore, the present invention has been proposed in view of the above situation, and reaches a reflective screen when an image is displayed using a display system including a front projector and a reflective screen. Provided are a reflection type screen, a front projection type display device and a lighting device which are capable of obtaining an image with sufficiently high contrast even in an environment where the outside light is bright, and the reflection type screen and the front projection type. An object of the present invention is to provide a display system including a display device and a lighting device.

[0011]

In order to solve the above problems, a reflection type screen according to the present invention is a reflection type screen which displays an image by reflecting projection light projected from a front projection type display device. The present invention is characterized in that it is provided with a reflective layer that reflects projected light, and the reflective layer is configured to have a layer made of cholesteric liquid crystal.

The reflection type screen according to the present invention is
A reflection type screen that displays an image by reflecting the projection light for image display projected from the front side to the front side, and reflects the circularly polarized light component of one direction of the projected light flux and reflects the circular polarization component of the other direction. It is characterized by having a characteristic of absorbing a polarized component.

The front projection type display device according to the present invention is a front projection type display device which displays an image by projecting projection light as projection light onto the front surface of a reflection type screen. A means is provided, and the projection light is projected as circularly polarized light in a specific direction by the polarization conversion means.

Further, the illuminating device according to the present invention is provided with at least a front projection type display device and a reflection type screen which has a reflection layer composed of a cholesteric liquid crystal layer and onto which projection light from the front projection type display device is projected. A lighting device provided in a room for illuminating the room, wherein at least illuminating light for illuminating the reflective screen is converted into circularly polarized light absorbed by the reflective screen by the polarization conversion means. It is what

Further, the illuminating device according to the present invention is provided with at least a front projection type display device and a reflection type screen which has a reflection layer composed of a cholesteric liquid crystal layer and onto which projection light from the front projection type display device is projected. An illumination device provided in a room that illuminates the room, wherein at least the illumination light that illuminates the reflective screen is circularly polarized light that passes through the reflection layer formed of the cholesteric liquid crystal layer by the polarization conversion unit, It is characterized in that the illumination light is absorbed by a light absorbing layer arranged on the back side of the reflecting layer.

Further, the illumination device according to the present invention is provided with at least a front projection type display device and a reflection type screen which has a reflection layer composed of a cholesteric liquid crystal layer and onto which projection light from the front projection type display device is projected. An illumination device provided in a room for illuminating the room, wherein the spectral intensity of a wavelength range corresponding to the selective reflection wavelength range of the reflective layer is lower than the spectral intensity of a wavelength range other than the selective reflection wavelength range. It is characterized by emitting illumination light.

The display system according to the present invention is a display system having at least a front projection type display device and a reflection type screen onto which projection light from the front projection type display device is projected. The front projection display device has a layer made of cholesteric liquid crystal and reflects a circularly polarized light component in one direction of the projected light. An image is displayed by projecting a certain projection light on the reflection type screen.

According to each of the above-mentioned constitutions of the present invention, in the reflection type screen, the reflection layer is formed by having the cholesteric liquid crystal layer made of the cholesteric liquid crystal, so that the circularly polarized light in the specific direction is selected. The function of reflecting is obtained.

Further, the reflection type screen according to the present invention has a characteristic of reflecting the circularly polarized light component in one direction and absorbing the circularly polarized light component in the other direction of the projected light flux.
A function of selectively reflecting circularly polarized light in a specific direction can be obtained.

Further, in the front projection display device according to the present invention, the projection light to be projected on the reflection type screen is circularly polarized in a specific direction by the polarization converting means.

Therefore, in the display system according to the present invention in which the reflection type screen according to the present invention and the front projection type display device are combined, the circularly polarized projection light projected from the front projection type display device is reflected. On the other hand, circularly polarized light in a direction different from that of the projected light or external light which is not circularly polarized light is selectively reflected by the pattern screen, but is not reflected by the reflective screen.

Further, in the illumination device according to the present invention for illuminating the room in which the reflection type screen and the front projection type display device according to the present invention are installed, at least the illumination light for illuminating the reflection type screen is polarized conversion means. Due to
Since the circularly polarized light is absorbed by the reflective screen, the illumination light that directly reaches the reflective screen can be prevented from being reflected by the reflective screen.

In the illuminating device according to the present invention, at least the illuminating light that illuminates the reflection type screen is converted into circularly polarized light which is transmitted through the reflection layer composed of the cholesteric liquid crystal layer by the polarization converting means, and the rear side of the reflection layer Since the illuminating light is absorbed by the light absorbing layer disposed on the side, the illuminating light that directly reaches the reflective screen can be prevented from being reflected by the reflective screen.

Further, in the lighting device according to the present invention,
Since the spectral intensity of the wavelength range corresponding to the selective reflection wavelength range of the reflective layer is such that the illumination light is lower than the spectral intensity of the wavelength range other than the selective reflection wavelength range, the illumination light is reflected The reflection on the mold screen can be suppressed.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, at least
A display system including a front projector that projects projection light and a reflective screen that displays an image by reflecting the projection light projected from the front projector will be described.

First, prior to describing a specific configuration example of the display system according to the present embodiment, the prerequisites for the configuration of the present embodiment will be described.

Cholesteric liquid crystal (CLC: Cholesteri)
c Liquid Crystal), as is well known, the alignment of liquid crystal molecular axes is the same on each plane, but on the next plane, the alignment direction of the molecular axes is slightly shifted, and on the next liquid crystal molecular axis, It has a structure in which the arrangement direction is shifted. That is, in addition to having a multifaceted structure, it has a structure in which the angle of the molecular axis shifts as it advances in the plane on which the molecules are arranged. That is, it has a so-called chiral structure in which the molecular axis is twisted as it advances in a plane.

It is also widely known that the twist pitch of the molecular axes described above exhibits selective reflection characteristics at the wavelength level.

[0030]

[Equation 1]

Cholesteric liquid crystals have the property of selectively reflecting circularly polarized light in a direction determined by the twist direction of the molecular axis. Also, the cholesteric liquid crystal can be made into a stable film with little temperature dependence by polymerizing it. It is also possible to adjust the selective reflection wavelength range by stacking or continuously changing cholesteric liquid crystals having different twist pitches of molecular axes in the thickness direction.

Therefore, it can be said that the cholesteric liquid crystal has the following features: Feature 1: Reflection function Feature 2: Circularly polarized light selection function Feature 3: Wavelength selectivity.

In the reflection type screen, in order to improve the deterioration of the contrast of the displayed image due to the external light, for example, the external light is not absorbed or reflected to the observer side on the reflection type screen. It is necessary to selectively reflect only the projection light from the front projection type front projection display device (front projection display device). That is, it is necessary to selectively reflect only the projected light with respect to the external light.

As described above, in the reflection type screen, as means for selectively reflecting only the projected light without reflecting the external light, means A: polarized light selection means B: wavelength selection Means C: Selection by angle can be mentioned.

In the present embodiment, the reflective screen constituting the display system has, as shown in FIG. 1, a cholesteric liquid crystal (C) as a layer functioning as a reflective layer.
It has a cholesteric liquid crystal layer 3 made of LC (Cholesteric Liquid Crystal) polymer. In the reflective screen 1, the cholesteric liquid crystal layer 3 described above is used.
Feature 1 (reflective function) of is demonstrated. That is, in the reflective screen 1, the cholesteric liquid crystal layer 3
As such, it will function as a reflective layer.

Further, a light absorbing layer 4 is arranged on the back side opposite to the front side of the cholesteric liquid crystal layer 3 irradiated with the projected light. Thereby, the cholesteric liquid crystal layer 3
The light components other than the circularly polarized light in the predetermined direction that is selectively reflected by (1) are transmitted through the cholesteric liquid crystal layer 3 and are absorbed by the light absorption layer 4 without leak reflection. Further, light having a wavelength not selectively reflected by the cholesteric liquid crystal layer 3 also passes through the cholesteric liquid crystal layer 3 and is absorbed by the light absorption layer 4. That is, the features 2 and 3 of the cholesteric liquid crystal layer 3 described above are exhibited, and circularly polarized light and wavelength are selected. Also, with this,
The means A (selection by polarization) and the means B (selection by wavelength) for selective reflection described above are realized.

In order to realize the above-mentioned means C (selection by angle) for selective reflection in the present embodiment, a concrete configuration example will be described later, but as described above, the cholesteric liquid crystal layer 3 is used. In addition, the retroreflective function is provided. That is, the retroreflection function is used to adjust the light reflection angle so that the projection light from the front projection display device is reflected and reaches the observer's pupil. This makes it possible to reduce the intensity of reflected light that reaches the pupil of the observer for external light having a random incident angle distribution.

Further, as will be described later, by adding a light shielding function to an appropriate position on the reflection type screen 1, only light having an incident angle distribution corresponding to the projection light from the front projection type display device is reflected. It is also possible to realize a structure that absorbs external light having an incident angle other than that.

In this way, in this embodiment, the selection function (means C) depending on the incident angle of the incident light on the reflection type screen can be realized.

In this embodiment, the circularly polarized light selecting function (feature 2) described above is used as follows.

First, the reflective screen 1 is provided with a cholesteric liquid crystal layer 3 so that only circularly polarized light in a specific direction is reflected. Correspondingly, the front projection display device is configured to project circularly polarized projection light in the direction reflected by the cholesteric liquid crystal layer 3 of the reflection type screen 1.

In this way, the projection light from the front projection display device is made into circularly polarized light in the direction reflected by the cholesteric liquid crystal layer 3, so that at least 50% of natural light is reflected by the cholesteric liquid crystal layer 3. Since it is cut, the reduction in the contrast of the display image due to the external light is improved.

Further, since the cholesteric liquid crystal layer in the reflective screen 1 has a circularly polarized light selecting function, external light is reflected by being circularly polarized in the opposite direction of the projected light from the front projection type display device. It is possible to suppress the amount of external light reflected by the cholesteric liquid crystal layer 3 of the mold screen 1.

That is, by providing a circular polarization filter that transmits only circularly polarized light in one direction or reflects circularly polarized light in the other direction in the path where external light reaches the reflective screen 1, the reflective screen 1 It is possible to suppress the amount of reflected light of the external light at.

In this case, the external light transmitted through the circular polarization filter is not reflected by the cholesteric liquid crystal layer 3 but is circularly polarized in the direction of transmission through the cholesteric liquid crystal layer 3. As a result, the external light transmitted through the circular polarization filter is not reflected on the reflective screen 1 and does not reach the observer's pupil. That is, by using the circularly polarized light selectivity of the cholesteric liquid crystal layer 3 of the reflective screen 1 as the externally polarized light in the predetermined direction,
It is possible to improve the contrast of the display image.

In this specification, "outside light" means
In a room (indoors) where the front projection display device is arranged, it is light other than the projection light projected from the front projection display device. For example, the light emitted from the indoor illumination device and the outdoor light incident through the window. Light refers to light reflected from a wall.

Regarding the use of the polarization selectivity to suppress the reflected light of the external light as described above, it is possible to use the polarization selectivity on the assumption of linearly polarized light. However, when trying to suppress the amount of reflected light of the external light in the reflective screen by using the polarization selectivity for linearly polarized light, the polarization axis of the projection light from the front projection display device,
It is necessary to match the polarization axes of the polarized light reflected by the reflection type screen, and these polarization axes and the polarization axis of the polarization filter arranged on the path leading to the reflection type screen of external light, must be orthogonal to each other. is there.

On the other hand, when utilizing the selectivity for circularly polarized light in a predetermined direction, since circularly polarized light has no polarization axis, the front projection type display device, the reflection type screen and the polarization filter as described above are used. It is not necessary to set the angle about the polarization axis between the two.

In this embodiment, the wavelength selection function (feature 3) is used as follows.

That is, the projection light from the front projection type display device is generally composed of light of three primary colors of R (red), G (green) and B (blue). Therefore, this projected light does not necessarily have a uniform intensity over the entire wavelength range of visible light. Further, the spectral intensity distribution of the projected light does not always match the spectral intensity distribution of the external light. Therefore, as the reflection type screen in the present embodiment, the contrast of the displayed image can be improved by setting the cholesteric liquid crystal so as to selectively reflect the wavelength region having high spectral intensity in the projection light.

It is also possible to positively adopt an illuminating device which emits illumination light having high spectral intensity in a wavelength range where the spectral intensity of projected light is low. That is, in the wavelength range in which the spectral intensity of the projected light is low, indoor illumination is performed with the illumination light having high spectral intensity, so that the contrast of the display image can be improved.

As a light source of the front projection type display device,
The wavelength selection function can be used most effectively when a laser beam having a sharp spectral intensity distribution such as a laser beam is used and the external light has a uniform intensity spectrum over the entire wavelength range of visible light. .

[Structure of Reflective Screen] Hereinafter, a specific example of the display system according to the present embodiment will be described. First, a specific structure of the reflective screen according to the present embodiment will be described. As the structure of the reflection type screen, six examples from the first example to the sixth example are given.

A first example of the structure of the reflection type screen is shown in FIG.
As shown in, the substrate 5, the light shielding layer 4, the cholesteric liquid crystal layer (CLC) from the back surface (back surface) to the front surface (front surface).
Layer) 3 and the bead diffusion layer 2 are sequentially laminated. The surface of the reflective screen 1 referred to here is
The surface on which the projection light from the front projection display device, which is a front projector, is projected, and is the surface on which the observer sees. The back surface is a surface opposite to the surface on which the projection light is projected and is a surface that cannot be seen by the observer.

The bead diffusion layer 2 is made of C as shown in FIG.
The LC layer 3 is formed, for example, by laminating a layer in which a large number of beads 6 made of glass or the like are arranged. Further, when the bead diffusion layer 2 is used as the diffusion layer, it has not only the light diffusion effect but also so-called retroreflectivity.

The CLC layer 3 is formed from a sheet-shaped material obtained by polymerizing cholesteric liquid crystal. This C
The cholesteric liquid crystal forming the LC layer 3 is set so as to select and reflect circularly polarized light in a specific direction, as described above. As a result, the circularly polarized light selecting function in the reflective screen 1 is provided.

Further, as the projection light projected from the front projection type display device, it is effective for displaying an image that the projection lights corresponding to the three primary colors of R (red), G (green) and B (blue). However, the cholesteric liquid crystal in the CLC layer 3 is set to have wavelength selectivity so as to exhibit selective reflection with respect to the projection light in such an effective wavelength range. As a result, the reflective screen 1 is provided with a wavelength selection function.

The light shielding layer 4 is provided on the back surface side of the CLC layer 3 and has a function of absorbing the light that has entered from the front surface side of the reflective screen 1 and reached the light shielding layer 4.

Incident light 10 incident from the surface of the reflection type screen 1 formed as described above first enters the beads 6 forming the bead diffusion layer 2 and reaches the CLC layer 3. Then, in the CLC layer 3, a circularly polarized light component in a specific direction set in advance is selectively reflected, and other light components are transmitted through the CLC layer 3. Further, the reflected circularly polarized light in a specific direction is also selectively reflected in a wavelength range having high intensity in the projection light from the front projection display device. That is, in the CLC layer 3, circularly polarized light in a specific direction,
In addition, the light component in the wavelength range corresponding to the projection light from the front projection display device is selectively reflected.

The light transmitted without being reflected by the CLC layer 3 is absorbed by the light-shielding layer 4, and therefore is not reflected and emitted to the surface side of the reflective screen 1.

On the other hand, the light component reflected by the CLC layer 3 again passes through the bead diffusion layer 2. As described above, the bead diffusion layer 2 emits reflected light as diffused light having a certain spread and has retroreflectivity. Retroreflectivity refers to the property of reflecting the reflected light in the same direction as the incident direction of the incident light.

Therefore, in this case, the CLC
The light reflected by the layer 3 and passing through the bead diffusing layer 2 is reflected as diffused light having a certain spread, and is reflected in substantially the same direction as the incident light 10 due to the retroreflectivity. That is, the angle difference between the incident angle a of the incident light 10 and the outgoing angle b of the reflected light is within a certain angle range.

In this case, the bead diffusion layer 2
By setting the refractive index of the beads 6 forming the to about 1.5 to 1.95, retroreflectivity corresponding to the refractive index of the beads can be obtained. As mentioned above, this retroreflectivity provides a choice of reflection angles. That is, if an observer is present in the incident direction of the projection light from the front projection display device, external light or the like incident on the reflective screen 1 from a direction other than the projection direction of the front projection display device is incident in the incident direction. The amount of light that is reflected and reflected toward the viewer is reduced. Then, due to the retroreflectivity, the projection light from the front projection display device returns to the observer side in the incident direction of the projection light. That is, the angle selectivity with respect to external light is provided.

Further, by providing a diffusion effect to the reflected light, it is possible to maintain uniform brightness over the entire area of the displayed image even if the area of the reflective screen 1 is a certain size or more.

A second example of the structure of the reflection type screen 1 of the present embodiment has a front surface (front surface) as shown in FIG.
The substrate 5, the bead diffusion layer 2, the CLC layer 3, and the light shielding layer 4 are sequentially laminated from the bottom to the back surface (back surface). In this configuration example, the substrate 5 is made of a transparent material.

In the reflection type screen 1 shown in FIG. 1, for example, the sheet as the bead diffusion layer 2 and the sheet as the CLC layer 3 are bonded together. On the other hand, in the reflection type screen 1 shown in FIG. 2 as the second example, the CLC layer 3 is formed directly on each bead 6 forming the bead diffusion layer 2.

In this way, C is directly applied to the beads 6.
In order to form the LC layer 3, the surface of the beads 6 may be coated with cholesteric liquid crystal, and then the coated cholesteric liquid crystal may be cured by a predetermined process. The refractive index of the beads 6 in this case is 1.
It is about 9 to 2.3.

Even in such a structure, the incident light 10
Are reflected by the CLC layer 3 after being subjected to circularly polarized light selection and wavelength selection, and are also provided with a light diffusion effect by the bead diffusion layer 2 and are reflected with retroreflectivity.

In particular, in the second example, as described above, the CLC layer 3 is directly attached to the beads 6, which results in the first example shown in FIG. The reflective screen 1 has a higher retroreflectivity. That is, the incident angle a / emission angle b of the incident light 10 in the first example (FIG. 1) and the incident angle a / emission angle b of the incident light 10 in the second example (FIG. 2). Comparing the two, the second example is smaller.

By the way, a structure having a combination of a so-called polarizing screen having a bead screen provided with a bead diffusion layer and a polarizing plate having a linearly polarized light selectivity is conventionally known. However, for a polarizing screen having linearly polarized light selectivity, in order to provide a reflection function, a polarizing plate and, for example, a reflective layer made of aluminum or the like are prepared as separate members, and, for example,
It is necessary to have a multi-layer structure in which these polarizing plates and a reflective layer are combined.

On the other hand, in the structure of the reflection type screen 1 of the present embodiment shown in FIGS. 1 and 2, the cholesteric liquid crystal having circular polarization selectivity is used instead of the polarizing plate having linear polarization selectivity. It can be said that it has layers. And
As described above, the cholesteric liquid crystal itself has the reflection function, so that the reflection function is realized only by the cholesteric liquid crystal. That is, it is not necessary to provide a reflective layer on the polarizing plate, unlike a polarizing screen having linearly polarized light selectivity. This allows
When a cholesteric liquid crystal is used for the screen, it is not necessary to add a reflective layer to give the function equivalent to that of a screen having linear polarization selectivity, so it is possible to reduce the number of members forming the screen. Become.

FIG. 3 shows the structure of a third example of the reflection type screen of this embodiment. In this figure, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted.

A reflective screen 1 as a third example shown in FIG. 3A has a substrate 5, a bead diffusion layer 2, a second light shielding layer 4B, a CLC layer 3 and a first light shielding layer 4A from the front surface to the back surface. Are laminated and formed in combination. In this case, the first light-shielding layer 4A has a function of absorbing the light component transmitted through the CLC layer 3, like the light-shielding layer 4 in FIGS. 1 and 2. In addition, the refractive index of the beads 6 in this case is also
It is about 1.9 to 2.3.

The reflection type screen 1 as the third example shown in FIG. 3 is different from the reflection type screen 1 shown in FIGS. 1 and 2 in that the second light shielding layer 4B is provided. ing. The arrangement mode of the second light shielding layer 4B will be described with reference to FIG. FIG. 3B is an enlarged schematic view of a part of the reflective screen 1 shown in FIG.

The second light shielding layer 4B is provided on the surface side of the CLC layer 3 as shown in FIG. 3 (b). Moreover, the lower side (back side) of the beads 6 forming the bead diffusion layer 2 is in a state of being embedded in the second light shielding layer 4B. Since the beads 6 are positioned with respect to the second light shielding layer 4B in this way, the layer thickness of the second light shielding layer 4B is not uniform. That is, FIG.
As can be understood from the relationship that th1 <th2 is obtained for the thickness th1 and the thickness th2 of the second light shielding layer 4B shown in FIG. The thickness is increased as it goes away from the center line C to the periphery of the beads 6.

In order to form the state in which the beads 6 are partially embedded in the second light-shielding layer 4B as described above, for example, the following may be performed. That is, it can be realized by dispersing a black pigment or the like in an adhesive agent that bonds the bead diffusion layer and the CLC film together. The adhesive containing this black pigment becomes the second light shielding layer 4B.

In this case, for example, realistically, the beads 6 are used.
In the vicinity of the center line C, there is a case where the bead 6 and the CLC layer 3 are in a state in which an adhesive layer, which is the second light shielding layer 4B, is present, though it is very thin. However, it has been found that the light transmittance of such a light shielding layer changes substantially according to the square of the thickness. Therefore,
There is a phenomenon that light is transmitted without problems in a portion where the adhesive layer as the second light-shielding layer 4B is thin, and light is not transmitted but is absorbed when a certain thickness reaches a certain boundary portion. be able to.

In the reflection type screen 1 as the third example thus formed, the first example (FIG. 1) described above is used.
Similarly to the reflective screen 1 shown in the second example (FIG. 2), circular polarization selectivity and wavelength selectivity by the CLC layer 3, light diffusion effect by the bead diffusion layer 2, and retroreflectivity (angle selectivity). ) Is obtained. Further, in the third example, more effective angle selectivity is given as described below.

In FIG. 3A, the incident light 1 incident on the reflective screen 1 is incident at an incident angle a.
0 and an incident light 10a which is incident at an incident angle c smaller than the incident angle a are shown. Here, the incident light 10 is
The projection light is projected from the front projection display device,
The incident light 10a is assumed to be external light.

In this case, if the incident angle (a) of the incident light 10 on the reflective screen 1 is larger than a predetermined angle, the incident light 10 reaches the vicinity of the central portion of the beads 6. Therefore, the incident light 10 reaches the CLC layer 3 without being absorbed by the second light shielding layer 4B around the lower side of the beads 6 in the bead diffusion layer 2. Then, the CLC layer 3 is selectively reflected according to the direction of circularly polarized light and reflected by being wavelength-selected, and further passes through the bead diffusion layer 2 to reach the observer side with diffusivity and retroreflectivity. .

On the other hand, the incident light 10a having an incident angle smaller than that of the incident light 10 reaches the peripheral portion deviated from the central portion of the bead 6, as shown in (a) of FIG. Therefore, the incident light 10a is absorbed by the second light shielding layer 4B and does not reach the CLC layer 3.

In this way, in the reflection type screen 1 of the third example, incident light whose incident angle is less than a certain angle is absorbed by the second light shielding layer 4B and is not reflected and output. That is, in this reflection type screen 1, light incident from the projection direction of the front projection type display device exhibits strong reflection, and extra light such as external light incident from other directions is not reflected. Is absorbed by. by this,
The reflective screen 1 of the third example can more effectively prevent the deterioration of the contrast due to the external light.

Although not described with reference to the drawings, also in the reflective screen 1 of the third example, the CLC layer 3 is applied to the beads 6 as in the reflective screen 1 of the second example shown in FIG. Alternatively, the second light shielding layer 4B may be formed on the CLC layer 3 by directly combining the above.

FIG. 4 shows a structural example of the reflection type screen 1 as the fourth example. In FIG. 4, the same parts as those in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

First, as shown in FIG. 4A, the reflection type screen 1 of the fourth example has a substrate 5, a bead diffusion layer 2, a second light shielding layer 4B, a CLC layer 3, and a second layer, from the front surface to the back surface. It has a structure in which one light shielding layer 4A is laminated and combined.
The refractive index of the beads 6 in this case is 1.9 to 2.
It is about 3.

That is, the basic structure of the reflection type screen 1 of the fourth example is the same as that of the reflection type screen 1 of the third example shown in FIG. However, the positional relationship between the beads 6 forming the bead diffusion layer 2 and the CLC layer 3 is different. This point will be described with reference to FIG.

FIG. 4B schematically shows a part of the reflection type screen 1 shown in FIG. 4A in an enlarged manner.

The CLC layer 3 shown in FIG. 4B has a portion which is in a bent state according to the spherical shape of the beads 6 which are spherical bodies. In this respect, for example, it can be said that the beads 6 and the CLC layer 3 have the same relationship as shown in FIG. However, in the fourth example, the central axis of curvature of the CLC layer 3 that is the reflective layer is decentered from the central axis of curvature of the individual beads 6. That is, as shown in the figure, the central axis of curvature A of the beads 6 is
It is assumed that the direction is perpendicular to the surface of the reflective screen 1. On the other hand, the central axis of curvature B of the CLC layer 3 is
It is set so as to deviate by a predetermined angle with respect to the center axis A of curvature of the beads 6.

Also in the reflection type screen 1 of the fourth example having such a structure, circular polarization selectivity and wavelength selectivity by the CLC layer 3 and light diffusion effect and retroreflectivity (angle selectivity) by the bead diffusion layer 2 are obtained. Is obtained. As angle selectivity,
Since the second light shielding layer 4B is arranged, an absorbing action is given to incident light having a certain incident angle or more.

As described above, the center axis of curvature B of the CLC layer 3 is decentered with respect to the center axis A of curvature of the beads 6, so that light is reflected as follows. That is, the light reflected by the CLC layer 3 and transmitted through the bead diffusion layer 2 exhibits retroreflectivity as a whole by the beads 6. However, depending on the amount of eccentricity of the center axis of curvature B of the CLC layer 3 with respect to the center axis of curvature A of the beads 6, the incident light 10 may be converged in the direction deviated in the eccentric direction of the CLC layer 3 that is the reflecting surface. Will be reflected.

This means that the center axis of curvature A of the beads 6 is
By setting the eccentricity amount of the central axis of curvature B of the CLC layer 3 with respect to, it is possible to set the angle difference of the incident angle a / the outgoing angle b at which the incident light 10 is retroreflected. In this way, by setting the reflection angle of the screen reflected light after giving retroreflectivity, for example, an observer can see the screen image at a position apart from the vicinity of the front projection display device to some extent. In this case, the reflection type screen can be effectively used. That is, it is possible to provide a reflective screen more suitable for practical use.

Here, an example of a manufacturing procedure for forming the bead diffusion layer 2 and the CLC layer 3 such that the curvature center axis B of the CLC layer 3 is decentered with respect to the curvature center axis A of the beads 6. It is shown below.

Procedure 1: One layer of beads is laid and cured on a resin layer (substrate 5) having a thickness of about ½ of the diameter of the beads. As a result, the bead diffusion layer 2 is formed.

Procedure 2: The bead diffusion layer 2 formed in the above procedure 1 is coated with an ultraviolet curable resin in which a black pigment is dispersed on the entire surface and then cured by irradiation with ultraviolet rays. The layer of this ultraviolet curable resin becomes the second light shielding layer 4B.

Step 3: The buff material is wound around a roll and, while rotating in one direction, the surface of the ultraviolet curable resin formed by the above step 2 is rubbed. At this time, a large amount of resin on the surface near the center of the beads 6 with which the buffing material is in contact is scraped off, and the amount of scraping in the peripheral portion of the beads 6 with less contact is reduced. As a result, for example, as described with reference to FIG. 3B, the second light-shielding layer 4B is formed such that the central portion of the bead 6 is thin and the thickness increases toward the peripheral portion. Become.

Step 4: A cholesteric liquid crystal is applied to the entire surface on which the second light-shielding layer 4B is formed, and then cured by ultraviolet irradiation. As a result, the CLC layer 3 is formed by the layer of the cured cholesteric liquid crystal. In this state, the surface where much of the UV curable resin has been scraped functions as a reflecting surface, and the portion where the amount of scraping is small becomes the light shielding layer.

In particular, in the fourth example, the friction caused by the buff material also has the effect of a so-called rubbing treatment which defines the orientation direction of the cholesteric liquid crystal. Further, the scraped surface is provided with a fine uneven shape in one direction orthogonal to the rubbing direction. As a result, the CLC layer 3 as the reflecting surface can have the effect of scattering in the direction orthogonal to the rubbing direction. As a result, it is possible to give the screen reflected light a property of converging in the direction decentered in the vertical direction and diffusing in the horizontal direction with an appropriate spread in the angular distribution.

Then, the fourth film formed as described above
FIG. 5 shows an example of the positional relationship between the reflective screen 1 as an example and the front projection display device 20 as the present embodiment.

FIG. 5A shows the center axis A of curvature of the beads 6 shown in FIG. 4B of the reflection type screen 1.
On the other hand, there is shown a positional relationship between the reflective screen 1 and the front projection display device 20 when the direction in which the center axis of curvature B of the CLC layer 3 is decentered is the vertical direction. In this figure, the reflection type screen 1 is arranged so that the direction of the arrow X described as the eccentric direction coincides with the direction of the arrow X shown in FIG.

Further, FIG. 5B shows the reflection type screen 1 and the front projection type display device 20 when the direction in which the concavo-convex shape is given to the CLC layer 3 by the above rubbing process is the horizontal direction. The positional relationship with is shown. As can be seen from the above description, the arrow Y indicating the direction in which the uneven shape is given as shown in FIG. 5B and the arrow X indicating the eccentric direction in FIG. 5A are orthogonal to each other. Therefore, the relationship between (a) in FIG. 5 and (b) in FIG.
If the inside (a) is viewed as a side view, the inside (b) of FIG.
Can be seen as a top view.

The following can be said from FIG. 5A and FIG. 5B.

First, according to FIG. 5A, in the direction in which the center axis of curvature B of the CLC layer 3 is eccentric with respect to the center axis A of curvature of the beads 6, the projection light from the front projection type display device is On the reflective screen 1, the light is reflected by the set reflection angle while having retroreflectivity, and reaches the position P, for example. This position P is, as can be seen from the figure,
It is at a position separated from the front projection display device 20 along the eccentric direction. Then, in an environment in which an observer is near the position P, the observer can see an image with high contrast.

On the other hand, according to FIG. 5B, since irregularities are formed on the CLC layer 3 which is the reflecting surface along the arrow X direction, in the direction along the arrow Y, The reflected light will be diffused with a certain spread.
As a result, for example, it is possible to extend the field of view in the horizontal direction. This means that as long as the line of sight of the observer is substantially at the position P, an image can be seen in which the contrast does not decrease even if the image moves horizontally to some extent.

Incidentally, the first to fourth examples explained so far.
Any of the reflective screens 1 of the example is not limited to the manufacturing procedure according to the procedure 1 to the procedure 4 described above, and any one of the screen surface, the bead surface, the reflective surface (CLC layer) or a plurality of surfaces may be used. On the other hand, by giving an appropriate scattering property, it is possible to give an appropriate spread to the reflection angle distribution and widen the visible range. Also, by appropriately setting and changing the diffusivity horizontally or vertically, it is possible to obtain a bright image while practically expanding the visible range.

Regarding the method of forming the CLC layer 3 which also serves as a reflection surface, in the first example (FIG. 1) and the third example (FIG. 2), the reflection layer made of cholesteric liquid crystal which is made into a sheet in advance is bonded to the bead diffusion layer. I am going to do it. In addition, in the second example (FIG. 2) and the fourth example (FIG. 4), the cholesteric liquid crystal is applied to the bead diffusion layer 2 and then cured.

However, the method for forming the CLC layer 3 is
The present invention is not limited to these, and various other types are possible. The layer structure of the cholesteric liquid crystal may be either a structure in which the pitch is continuously changed in one layer or a multi-layer structure in which the pitch is different. Further, the setting of the selected wavelength range for the cholesteric liquid crystal should be determined in consideration of the usage environment, cost, etc. of the front projection display device and the display system.

A configuration example for improving the external light contrast by using the selective wavelength function will be described later.

FIG. 6 shows an example of the structure of a reflection type screen 1 as a fifth example. The reflective screen 1 shown in this figure is formed such that the CLC layer 3, the substrate 5 and the light shielding layer 4 are laminated from the front surface to the back surface. As can be seen from such a layer structure, the fifth example does not have the bead diffusion layer 2.

The reflection type screen 1 of this fifth example
In the above, the uneven shape is formed on the front surface side of the substrate 5. In this case, the overall retroreflectivity is given by defining the overall reflection direction by, for example, prism-shaped irregularities. Then, the CLC layer 3 is formed by applying and curing cholesteric liquid crystal on the surface side of the substrate 5 on which the uneven shape is formed. Then, by adjusting the roughness of the coated surface on the front surface side of the CLC layer 3 during the processing such as rubbing, the direction of the molecular surface is changed as shown in FIG. Adjust the angle of the diffusion range. That is, the visual field range in the predetermined direction can be adjusted.

With such a structure, the bead diffusion layer 2
It is possible to obtain the reflection type screen 1 having the circularly polarized light selectivity and the wavelength selectivity, and the reflection type screen 1 having the retroreflectivity and the diffusivity even if it does not have. That is, for example, the reflective screen 1 having the light reflection shown in FIGS. 5A and 5B can be provided.
As a result, the number of members that form the reflective screen 1 is reduced, so that the cost can be effectively reduced.

The back surface of the substrate 5 is a flat surface on which no unevenness is formed, and the light shielding layer 4 is applied or bonded to this surface.

FIG. 7 shows an example of the structure of a reflection type screen 1 as a sixth example.

Here, as the layer structure of the reflection type screen 1 of the sixth example shown in FIG. 7A, the CLC layer 3, from the front surface to the back surface, as in the fifth example shown in FIG. The substrate 5 and the light shielding layer 4 are laminated and formed, and the bead diffusion layer 2 is not provided.

Further, in the sixth example, the surface side of the substrate 5 is provided with a so-called corner cube structure as shown in FIG. 7B. Thereby, for example, the retroreflectivity is given as shown as a reflection path of the incident light 10 in (a) of FIG.

Further, in this case, the back surface side of the substrate 5 is a flat surface, and the light shielding layer 4 is applied to or bonded to this surface.

Then, the CLC layer 3 is formed by applying and curing the cholesteric liquid crystal on the surface side of the substrate 5 having the corner cube shape as described above. Also in this case, as in the case of the fifth example described above, the angle of the diffusion range of the reflected light can be adjusted by adjusting the roughness of the coated surface on the surface side of the CLC layer 3.

Even with such a structure, it is possible to obtain a reflection type screen 1 having retroreflectivity and diffusibility as the reflection type screen 1 having circularly polarized light selectivity and wavelength selectivity without having the bead diffusion layer 2. Will be possible.

In each of the fifth and sixth examples described above, instead of forming the light shielding layer 4 on the back surface of the substrate 5, the substrate 5 itself may be formed of an absorbing material. . Even with such a configuration, the same effects as those of the fifth and sixth examples described above can be obtained.

Further, the reflection type screen according to the present invention is
As a seventh example, as shown in FIG. 8, 1/4 from the front side.
The wavelength plate 7, the absorption type linear polarizing plate 8, the diffuse reflection plate 9 and the substrate 5 may be laminated in this order. Also in this case, the reflection type screen 1 having the circularly polarized light selective reflection characteristic can be realized. That is, 1 /
Since a circular polarization plate is formed by combining the four-wave plate and the absorption type linear polarization plate, depending on the polarization state of the light incident on the reflection type screen 1, circular polarization in one direction passes through the absorption type linear polarization plate 8 and is diffusely reflected. The absorption type linearly polarizing plate 8 is reflected by the plate 9 again.
Pass through. Then, the circularly polarized light in the other direction is cut by the absorption type linear polarization plate 8.

In this reflection type screen 1,
The wave plate 7 is made of a stretched film such as polycarbonate. This quarter wave plate 7 is, for example, a quarter wave plate and one
By laminating a plurality of retardation plates such as a structure in which a / 2 wavelength plate is laminated, it becomes possible to function as a quarter wavelength plate in a wide wavelength range.

The surface of the quarter-wave plate 7 is antiglare treated. Further, by adding an antireflection film, it is possible to improve the display quality.

As the absorption type linear polarizing plate 8, a PVA film having a dichroic dye such as iodine oriented may be used. Further, the quarter wave plate 7 and the absorption type linear polarizing plate 8 are formed by an alignment treatment of a liquid crystal polymer instead of a general stretched film.
It is also possible to use a four-wave plate or a material that exhibits the function of a polarizing plate by coating.

As the diffusive reflector 9, an aluminum plate whose surface has been subjected to a diffusing treatment such as so-called hairline finishing can be used.

Further, as a reflection type screen, FIG.
As an eighth example, a retroreflective plate composed of a bead diffusion layer 2 and a reflective layer 9a may be used instead of the diffuse reflective plate 9 of FIG. The bead diffusion layer 2 is formed by arranging a plurality of beads 6 as described above.
The bead diffusion layer 2 is arranged on the back surface of the absorption type linear polarizing plate 8. Then, the reflection layer 9a is arranged on the back surface of the bead diffusion layer 2. The reflective layer 9a is formed along the back surface of each bead 6 forming the bead diffusion layer 2.

In addition, as the diffuse reflection plate, it is possible to adopt any structure as long as the polarization state of incident light can be substantially preserved and reflected.

[Configuration of Front Projection Display Device] Next, as a component of the display system of the present embodiment, a front projection display device used together with the reflective screen 1 of each of the above-described examples will be described. As described above, in the present embodiment, the reflective screen 1 has circularly polarized light selectivity, and selects and reflects circularly polarized light in a specific direction. Therefore, as the front projection display device 1, it is necessary to project circularly polarized projection light in the direction in which the reflective screen 1 side selectively reflects. The structure of the front projection display device for this purpose will be described below.

FIG. 10 shows an example of the internal structure of a front projection type display device according to this embodiment.

The front projection type display device 20 shown in FIG.
For example, a lamp 21 which is a light source and is composed of a metal halide lamp or the like is arranged at the focal position of the reflector 22 (parabolic mirror). The light emitted from the lamp 21 is reflected by the reflector 22, collimated so as to be a parallel light flux substantially parallel to the optical axis, and emitted from the opening of the reflector 22.

The light flux emitted from the opening of the reflector 22 is incident on the multi-lens array 23. By passing through the multi-lens array 23, the light flux is efficiently and uniformly applied to the effective aperture of the light valve described later.

The light flux transmitted through the multi-lens array 23 is deflected by 90 ° in the optical path by the mirror 24 and is incident on the color separation / synthesis optical system after the dichroic mirror 25.

First, the dichroic mirror 25 transmits the red luminous flux R and reflects the green luminous flux G and the blue luminous flux B. The red light flux R that has passed through the dichroic mirror 25 is deflected by 90 ° in its optical path by the mirror 26 and is guided to the condenser lens 27 in front of the red light valve 28.

On the other hand, the green and blue light beams G and B reflected by the dichroic mirror 25 are separated by the dichroic mirror 29. That is, in the dichroic mirror 29, the green light flux G is reflected, the traveling direction is deflected by 90 °, and is guided to the condenser lens 30 in front of the green light valve 31.

Further, the blue luminous flux B passes through the dichroic mirror 29 and goes straight, and is guided to the condenser lens 36 in front of the blue light valve 37 via the relay lens 32, the mirror 33, the relay lens 34 and the mirror 35. Get burned.

In this way, the red, green and blue luminous fluxes R, G and B are respectively converted into the condenser lenses 27, 30, 3 respectively.
6 through the light valves 28, 31, 37 for each color
Is incident on.

The light valves 28, 31, 3 of these respective colors
7 includes, for example, a liquid crystal panel, and an incident-side polarization plate for aligning the polarization direction of light incident on the front side of the liquid crystal panel in a fixed direction. In addition, a so-called analyzer that transmits only the light component having a predetermined polarization plane of the emitted light is arranged at the rear stage of the liquid crystal panel, and the voltage of the circuit that drives the liquid crystal changes the light intensity according to the display image. It is designed to modulate.

Then, the light fluxes of the respective colors, which are light-modulated by the light valves 28, 31, and 37, are incident on the light combining element (dichroic prism) 38 from three directions. This photosynthetic element is configured by combining a cubic prism divided into four and reflecting films 38a and 38b formed on the divided surfaces.

The red luminous flux R in the photosynthetic element 38 is
The blue light flux B reflected by the reflection film 38 a is reflected by the reflection film 38 b and emitted toward the projection lens 41. The green light flux G travels straight through the photosynthetic element 38, is transmitted, and is emitted toward the projection lens 41. This allows
The light fluxes R, G, and B are combined into one light flux and emitted toward the projection lens 41.

Further, in this embodiment, as shown in FIG.
As shown in FIG. 0, a polarization axis rotation element 39 and a quarter wavelength plate are provided on the optical path from the light combining element 38 to the projection lens 41.

Generally, in a front projection type display device using a liquid crystal panel as a light modulation element, since the liquid crystal panel utilizes linearly polarized light, the projection light of linearly polarized light is projected. Therefore, as in the present embodiment, for example, by transmitting the light flux incident on the projection lens 41 through the quarter-wave plate 40, the light flux incident on the projection lens 41 can be converted into circularly polarized light. Become. Thereby, the projection lens 4
The projected light from 1 is also circularly polarized. Since it is well known that linearly polarized light is converted into circularly polarized light by passing through a quarter-wave plate, a description of the principle of polarization conversion by the quarter-wave plate is omitted here. .

In the present embodiment, 1/4
The circularly polarized state of the projected light determined by the phase shift direction by the wave plate 40 is set so as to be circularly polarized in the direction reflected by the CLC layer 3 of the reflective screen 1.

Further, as shown in FIG. 10, in the case of the structure in which the color combination is performed by the dichroic prism (light combining element 38), the green light beam G and the blue and red light beams B,
In R and R, the polarization axes of the emitted light may be orthogonal to each other. As it is, it is inconvenient for circularly polarized light conversion, but in such a case, the polarization axis of the green light beam G is rotated and the
An element that can match the red light fluxes B and R may be arranged, for example, on the optical path of the light flux entering the projection lens 41. This corresponds to the polarization axis rotation element 39 shown in FIG. In this way, an element that selects only an appropriate wavelength range and rotates the polarization axis is well known, and has already been commercialized under the name of "Color Select" from Color Link Co., for example. .

The projection lens 41 converts the light flux incident from the photosynthesis element 38 side into projection light and projects it onto the front surface of the reflection type screen 1 of the present embodiment.

The configuration of the front projection type display device of this embodiment shown in FIG. 10 is merely an example. In particular, there are various configurations of the color separation / combination optical system as the front projection type display device as well known, and even in the front projection type display device according to the present invention, these various color separation / composition optical systems are used. It may have a synthetic optical system. Further, the front projection display device shown in FIG.
Although the configuration includes a transmissive light valve (liquid crystal panel), the configuration may include, for example, a reflective light valve.

[Structure of Illumination Device] Also, as this embodiment, an illumination device for preventing the contrast reduction of the image displayed on the reflection type screen 1 due to the external light is proposed.

As a light source of the front projection type display device, a discharge lamp such as an ultra high pressure mercury lamp (UHP lamp) or a metal halide lamp is generally used. The radiated light from such a discharge lamp contains a light component that is not effectively used in the process of color separation and illumination, and is absorbed by the members constituting the front projection display device.

Here, as an example, FIG. 15 shows the spectral distribution characteristics of the UHP lamp together with the wavelength bands of the three primary colors of RGB. As can be seen from FIG. 15, in the spectral distribution of the ultra-high pressure mercury lamp, the band where a peak is obtained at the boundary between green (G) and red (R) is a light component that is not effectively used.

Therefore, as the present embodiment, it is proposed that the light components unnecessary for such image display are not absorbed but are used as illumination light in the room. That is, the unnecessary light is diffused and emitted to the outside as illumination light from the front projection display device. This means that the front projection display device is also used as an illumination device. Note that, hereinafter, the front projection display device that also functions as the illumination device in the present embodiment will also be referred to as a projection / illumination device. In order to configure such a projection / illumination device, for example, in a front projection display device, unnecessary light in a band not used for image display is emitted to the outside through a housing. To do. Then, a diffusing material may be used for the exterior part of the housing so that the light inside is diffused and emitted to the outside.

Then, the spectral distribution of the illumination light of the projection / illumination device thus constructed is as shown in FIG. 16, the illumination light of the projection / illumination device is the boundary wavelength region of RG,
The intensity of the B-G boundary wavelength region has a strong distribution, as shown in FIG.
The distribution is different from that of the lamp shown in FIG. Therefore, the illumination light from the projection / illumination device is RG
It is understood that the distribution characteristics differ from the projected light corresponding to the B three primary colors.

Further, the illuminating device constitutes a single illuminating device that emits illuminating light having a spectral distribution different from that of the light projected from the front projection type display device. Even if this illuminating device is used, the above-mentioned projection / illumination is performed. The same effect as that of the device 20A can be obtained.

As such a single illuminating device, for example, a light source which emits illumination light having a peak in the RG boundary wavelength band and the BG boundary wavelength band may be adopted. In the present invention, the type of such a light source is not particularly limited, but in the embodiment, an LED (Light Emitting Dio
de) will be adopted. Therefore, in this embodiment, the lighting device is configured by using the LED that emits light having a peak in the RG boundary wavelength band and the BG boundary wavelength band.

FIG. 17 shows the spectral distribution characteristic of the illumination light from the illumination device according to the present embodiment in comparison with the band characteristic of each color of RGB. As can be seen from FIG. 17, the illumination light from the LED adopted in the illumination device of the present embodiment is
It has peaks in the RG boundary wavelength range and the BG boundary wavelength range.

Then, in the cholesteric liquid crystal forming the CLC layer of the reflection type screen 1 while configuring the illuminating device as described above, the selective reflection wavelength range is matched with the spectral distribution of the projection light from the front projection type display device. At the same time, it is set not to be selectively reflected in the RG boundary wavelength band and the BG boundary wavelength band.

Further, in this illuminating device, as shown in FIG. 11, a lamp cover including many light sources such as a fluorescent lamp and a halogen lamp is constituted by a CLC polarizing plate 20a, or as shown in FIG. Lamp cover 60a
The outer surface of the above may be covered with the polarizing plate 20a. In this case, the polarizing plate 20a has a cholesteric liquid crystal polymer (CL) on the outer surface of the lamp cover 60a.
It may be formed by coating C).

In this illuminating device, only the circularly polarized light in the direction not reflected by the reflection type screen 1 is radiated outward, and the circularly polarized light in the other direction is returned to the inside of the light source for reuse.

[Structure of Display System] Now, with reference to FIG. 13, a case will be described in which a display system including the projection / illumination device described above and the reflective screen 1 of the present embodiment is constructed. It should be noted that the term “display system” as used in this specification refers to an environment in which at least the reflective screen 1 and the front projection display device 20 are provided and the image projected on the reflective screen 1 is observed. Here, a display system as an indoor environment will be taken as an example.

FIG. 13 shows a state in which the projection / illumination device 20A is mounted and installed on the ceiling surface 53 in the room 50. The arrangement direction and the like are adjusted so as to project the projection light onto the reflection type screen 1 attached to the wall surface 52. Note that projection /
The function of the illumination device 20A as the front projection display device may be realized by, for example, the configuration shown in FIG.

As described above, since the circularly polarized projection light reflected by the reflection type screen 1 is projected from the projection / illumination device 20A, the screen selectively reflects the projection light. Will be done. This is one element for preventing the contrast of the image displayed on the reflective screen 1 from being deteriorated by external light.

From the projection / illumination device 20A, for example, illumination light as shown in FIG. 16 is diffused and emitted into the room 50. Since this illumination light exhibits a spectral distribution different from that of the projected light, it is possible to prevent the deterioration of the contrast due to the external light of the display image in this respect as well.

On top of this, the reflection type screen 1
If the reflection of the illumination light is suppressed more effectively by utilizing the wavelength selectivity of No. 3, the deterioration of the contrast of the display image due to the external light can be further prevented. That is, the selective reflection wavelength range of the cholesteric liquid crystal used in the CLC layer 3 of the reflection type screen 1 is matched with the spectral distribution of the projection light from the projection / illumination device 20A, and conversely, the RG boundary wavelength range, B- G
The setting is such that selective reflection is not performed in the boundary wavelength range of As a result, the amount of reflection of the illumination light from the projection / illumination device 20A on the reflective screen 1 is further reduced, and the reduction in the contrast of the display image due to external light is further prevented. By the way, the external light that reaches the reflective screen 1 after the illumination light is reflected on the interior surfaces such as the wall surface 52, the ceiling surface 53, and the floor surface 54 is also CLC of the reflective screen 1.
The intensity is high outside the selective reflection wavelength range of the layer 3. Therefore, C
The amount of external light reflected by the LC layer 3 is small.

Further, in FIG. 13, a CLC polarizing plate 20a is attached or a cholesteric liquid crystal polymer (CLC) on the surface of the casing of the projection / illumination device 20A in the direction corresponding to the emission direction of the projected light. ) Is coated to provide a circularly polarized light selection element.

As the CLC polarizing plate 20a, for example, a sheet of cholesteric liquid crystal can be used, and for example, the cholesteric liquid crystal has the same molecular axis as the cholesteric liquid crystal used in the CLC layer 3 of the reflection type screen 1. It gives the twist direction of.

As a result, the illumination light that reaches the reflective screen 1 side from the projection / illumination device 20A is transmitted through the CLC polarizing plate 20a. And the CLC polarizing plate 2
The light transmitted through 0a is only circularly polarized light in the direction opposite to the projection light, depending on the twisting direction of the molecular axis of the CLC polarizing plate 20a. Therefore, even if the light transmitted through the CLC polarizing plate 20a reaches the reflective screen 1, the reflective screen 1
The light is transmitted through the CLC3 layer and is absorbed in the light shielding layer. In this way, the projection / illumination device 20A has a CL
By providing the C polarizing plate 20a, it is possible to more effectively prevent the reduction in the contrast of the display image due to the external light.

By attaching a CLC polarizing plate 20a or coating a cholesteric liquid crystal polymer (CLC) on the surface of the housing of the projection / illumination device 20A, circularly polarized light in one direction is transmitted and circularly polarized light in the other direction is transmitted. By returning the polarized light to the light source side, the light can be reused.

Further, instead of the CLC polarizing plate 20a attached to the housing surface of the projection / illumination device 20A, a circularly polarized light selecting element composed of a quarter wavelength plate and a linear polarizing plate may be attached. Good. When an absorption type linear polarizing plate is used, the light utilization efficiency of illumination light may become a problem, but in that case,
By using the reflection type linear polarization plate, it is possible to transmit circularly polarized light in one direction and reflect circularly polarized light in the other direction to return it to the light source side to reuse the light.

In the room 50 shown in FIG. 13, a CLC blind 51 is attached to the window as a so-called blind curtain. This CLC blind 51 also uses a sheet of cholesteric liquid crystal, and gives the cholesteric liquid crystal the same twisting direction of the molecular axis as the cholesteric liquid crystal used in the CLC layer 3 of the reflective screen 1.

Therefore, the outside light which is going to enter the room 50 through the window becomes only the circularly polarized light in the opposite direction to the projected light by the CLC blind 51 according to the twisting direction of the cholesteric liquid crystal, and the indoor light is emitted. 50 will come in. Therefore, the light entering the room 50 through the CLC blind 51 is reflected by the reflective screen 1.
Even if it reaches, it will be absorbed without being reflected by the CLC layer 3. In this way, by attaching the CLC blind 51 to the window, it is possible to prevent the contrast of the displayed image from being lowered due to external light.

The CLC blind 51 can also be formed by coating a cholesteric liquid crystal polymer (CLC) on a base material, and further, a circularly polarized light selecting member composed of a quarter wavelength plate and a linear polarizing plate. You may make it comprised by an element.

Further, in the present embodiment, by using the wall surface 52, for example, it is possible to prevent the deterioration of the contrast of the display image due to the external light.

That is, irregularities are formed on the members forming the wall surface 52, or a member having an irregular surface is selected. Then, with respect to the surface of the member having this uneven shape, the CLC of the reflective screen 1 is
A cholesteric liquid crystal having a twist opposite that of layer 3 is applied. In addition, the wall surface member is provided with a light absorbing function or an absorption layer is provided on the back surface of the member. As a result, of the light reaching the wall surface 52, the light component of circularly polarized light in one direction is absorbed without being reflected. On the other hand, since the light reflected by the wall surface 52 is circularly polarized light in the direction of passing through the CLC layer 3 of the reflection type screen 1, even if it reaches the reflection type screen 1, it is not reflected here. Will be absorbed.

Note that the ceiling wall 53 and the floor surface 54 are not limited to the wall surface 52, and may be subjected to the same treatment. That is, in this embodiment, the same processing as that of the wall surface 52 may be performed on any of the indoor surfaces. Furthermore, not only the interior surface,
In the environment where there is a front projection type display device, the same processing is applied to the surface of various indoor installations such as furniture placed where the reflected light reaches the screen. To be done.

In the above description, the front projection type display device has the function of the illumination device. However, as described above, the illumination light having a spectral distribution different from that of the projection light from the front projection type display device is used. Alternatively, a single illumination device that emits illumination light that is circularly polarized light in a direction opposite to the projection light from the front projection type display device is configured, and even if this illumination device is used, it is similar to the above-mentioned projection / illumination device 20A. The effect can be obtained.

FIG. 14 shows an example of construction of an indoor environment as the display system of the present embodiment, in which the lighting device 60 having the above-mentioned configuration is installed.

In FIG. 14, first, the lighting device 6
0 is attached to the ceiling surface 53 and emits illumination light having peaks in the RG boundary wavelength band and the BG boundary wavelength band, as described above.

Further, in this case, the front projection type display device 20 of the present embodiment having no illumination function is the same as the stand 2
0b, it is arranged in a floor-standing form. Then, projection light is projected from the front projection type display device 20 onto the reflection type screen 1 attached to the wall surface 52.

Also in this case, the circularly polarized projection light reflected by the reflection type screen 1 is projected from the front projection type display device 20, and the reflection type screen 1 selectively reflects this projection light.

Then, as shown in FIG. 17, illumination light having a spectral distribution different from that of the projected light is diffused and emitted from the illumination device 60 in the room 50.

At the same time, in the reflective screen 1, as described above, the selective reflection wavelength range of the cholesteric liquid crystal used in the CLC layer 3 is set to the front projection display device 2.
In accordance with the spectral distribution of the projected light from 0, it is set not to be selectively reflected in the RG boundary wavelength range and the BG boundary wavelength range. Therefore, in the reflection type screen 1, the reflection of the illumination light from the illumination device 60 is suppressed as much as possible. In this way, the reduction of the contrast of the displayed image due to the external light is further prevented. In this case, too,
The natural light that reaches the reflective screen 1 by reflecting the illumination light on the interior surfaces such as the wall surface 52, the ceiling surface 53, and the floor surface 54 has a high intensity outside the selective reflection wavelength range of the CLC layer 3 of the reflective screen 1. , CLC layer 3 hardly reflects.

Further, as shown in FIG. 14, a lighting device 60.
On the surface of, the CLC polarizing plate 20a is attached or the cholesteric liquid crystal polymer (CLC) is coated at a position corresponding to the irradiation direction of the illumination light to the reflective screen 1.

As the CLC polarizing plate 20a, it is possible to use a sheet of cholesteric liquid crystal as in the case described above with reference to FIG. Further, the cholesteric liquid crystal serving as the CLC polarizing plate 20a is given the same twisting direction of the molecular axis as the cholesteric liquid crystal used in the CLC layer 3 of the reflective screen 1.

As a result, the illuminating light that reaches the reflective screen 1 from the illuminating device 60 is emitted from the CLC polarizing plate 20.
By transmitting a, only circularly polarized light in the direction opposite to the projected light from the front projection display device 20 is transmitted, so that even when it reaches the reflective screen 1, it is transmitted through the CLC3 layer and is absorbed in the light shielding layer. . Also in this case, the illumination light that directly or indirectly reaches the reflection type screen 1 from the illumination device 60 is hard to be reflected by the reflection type screen 1, and the reduction in the contrast of the display image due to the external light is prevented. ing.

Further, the illumination device 60, as described above,
Circularly polarized light in the direction opposite to the projection light from the front projection display device can be emitted. Also in this case, the circularly polarized projection light reflected by the reflection type screen 1 is projected from the front projection type display device 20, and the reflection type screen 1 selectively reflects this projection light.

Then, from the illumination device 60, circularly polarized illumination light in a direction not reflected by the reflection type screen 1 is diffused and emitted in the room 50. In the reflective screen 1, as described above, the reflection of the illumination light from the illumination device 60 is suppressed as much as possible due to the circularly polarized light selective reflection characteristic of the cholesteric liquid crystal used in the CLC layer 3.
In this way, the reduction of the contrast of the displayed image due to the external light is further prevented.

Even in the environment of the display system shown in FIG. 14, as in FIG. 13, the CLC blind 51 is used.
Can be provided in the window to prevent the contrast of the displayed image from being lowered by external light. In addition, the wall surface 52,
The interior surface such as the ceiling surface 53 and the floor surface 54, or the surface of an installed object such as furniture can be subjected to the same processing as described with reference to FIG. 13 to improve the contrast of a display image.

In the example shown in FIG. 13, the projection / illumination device 20A allows one device to have a projection light projection function and an illumination function, so that it is not necessary to provide a separate illumination device, for example. That is advantageous. On the other hand, in the example shown in FIG. 14, since the illumination device is independent, it is easy to use a light source having a peak in the RG boundary wavelength band and the BG boundary wavelength band, which is close to the ideal one. Is advantageous in that it can be selected. Also, regarding the selection of the type of light source, there is an advantage that it is possible to select from a plurality of candidates in consideration of performance, cost and the like.

[0185]

As described above, in the reflection type screen according to the present invention, since the reflection layer is formed by having the cholesteric liquid crystal layer made of cholesteric liquid crystal, circularly polarized light in a specific direction is selected. The function of reflecting is obtained. Further, the reflective screen according to the present invention has a characteristic of reflecting the circularly polarized light component in one direction and absorbing the circularly polarized light component in the other direction of the projected light flux, so that the circularly polarized light in the specific direction is selected. The function of reflecting is obtained.

Further, in the front projection type display device according to the present invention, the projection light to be projected on the reflection type screen is circularly polarized in a specific direction by the polarization converting means.

Therefore, in the display system according to the present invention in which the reflection type screen according to the present invention and the front projection type display device are combined, the circularly polarized projection light projected from the front projection type display device is reflected. On the other hand, circularly polarized light in a direction different from that of the projected light or external light which is not circularly polarized light is selectively reflected by the pattern screen, but is not reflected by the reflective screen.

Further, in the illuminating device according to the present invention for illuminating the room in which the reflection type screen and the front projection type display device according to the present invention are installed, at least the illumination light for illuminating the reflection type screen is polarized conversion means. Thus, the circularly polarized light is absorbed by the reflection type screen, so that the illumination light that directly reaches the reflection type screen can be prevented from being reflected by the reflection type screen.

In the illuminating device according to the present invention, at least the illuminating light that illuminates the reflection type screen is converted into circularly polarized light which passes through the reflection layer composed of the cholesteric liquid crystal layer by the polarization conversion means, and the rear side of the reflection layer Since the illuminating light is absorbed by the light absorbing layer disposed on the side, the illuminating light that directly reaches the reflective screen can be prevented from being reflected by the reflective screen.

As described above, in the present invention, by utilizing the circularly polarized light selectivity in the reflection type screen,
It is possible to reduce the influence of external light and display an image with excellent contrast while maintaining the light amount of the projected light to be equal to or less than a certain light amount. An image with improved contrast can be displayed by disposing an optical element having circularly polarized light selectivity on the path through which external light reaches the reflective screen.

In the present invention, as described above, since the circularly polarized light selectivity is used in order to suppress the influence of external light and improve the contrast of the display image, the reflection type screen and the front projection type display are used. The allowable amount of the positional relationship between the device and the lighting device can be increased.

That is, for example, when linearly polarized light is used as the characteristic of selective reflection in the reflection type screen, it may be arranged between the reflection type screen, the front projection type display device and the illuminating device depending on the polarization direction of the projected light. Since the positional relationship and the installation direction are defined, the effect of improving the contrast of the display image cannot be obtained unless the installation is performed as specified. On the other hand, when circularly polarized light is used as the characteristic of selective reflection in the reflective screen, the position between the reflective screen, the front projection display device, the lighting device, etc. can be set if the relationship about the direction of circular polarization is appropriate. Relationships and installation directions are not specified, and the degree of freedom regarding these installations is improved.

In the lighting device according to the present invention,
Since the spectral intensity of the wavelength range corresponding to the selective reflection wavelength range of the reflective layer is such that the illumination light is lower than the spectral intensity of the wavelength range other than the selective reflection wavelength range, the illumination light is reflected The reflection on the mold screen can be suppressed.

For example, for the cholesteric liquid crystal layer of the reflection type screen, the selective reflection wavelength range is set so as to selectively reflect the light in the wavelength band of the projection light of the front projection type display device, while the illumination emitted by the illumination device is set. Regarding light, it is assumed that the spectral intensity in a wavelength range different from the selective reflection wavelength range of the reflection type screen (that is, the wavelength range of the projection light of the front projection type display device) is strong. By making such a relationship between the selective reflection wavelength range of the cholesteric liquid crystal layer of the reflection type screen and the spectral intensity of the illumination light from the illumination device,
Regarding the illumination light, even if it reaches the reflection type screen directly or indirectly, the reflection on the reflection type screen is suppressed. That is, in this case, it is possible to suppress the influence of external light and improve the contrast of the displayed image by utilizing the wavelength selectivity of the reflective screen.

That is, according to the present invention, when an image is displayed by using a display system including a front projector and a reflection type screen, the ambient light reaching the reflection type screen is sufficiently high even in a bright environment. Provided are a reflection type screen, a front projection type display device and a lighting device which are adapted to obtain a contrast image, and
It is possible to provide a display system including the reflective screen, the front projection display device, and the lighting device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a structure (first example) of a screen as an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing the structure (second example) of the screen according to the present embodiment.

FIG. 3 is a cross-sectional view schematically showing the structure (third example) of the screen according to the present embodiment.

FIG. 4 is a cross-sectional view schematically showing the structure (fourth example) of the screen according to the present embodiment.

FIG. 5 is an explanatory view schematically showing a state of reflected light on the screen of the fourth example.

FIG. 6 is a sectional view schematically showing the structure (fifth example) of the screen according to the present embodiment.

FIG. 7 is a cross-sectional view schematically showing the structure (sixth example) of the screen according to the present embodiment.

FIG. 8 is a cross-sectional view schematically showing the structure (seventh example) of the screen according to the present embodiment.

FIG. 9 is a cross-sectional view schematically showing the structure (eighth example) of the screen according to the present embodiment.

FIG. 10 is a diagram showing an internal configuration example of a front projection display device of the present embodiment.

FIG. 11 is a cross-sectional view showing a configuration of an illumination device according to the present invention.

FIG. 12 is a cross-sectional view showing another example of the configuration of the illumination device.

FIG. 13 shows a projection / display of this embodiment as a display system.
It is explanatory drawing which shows the example of an indoor environment in which the illuminating device was installed.

FIG. 14 is an explanatory diagram showing an example of an indoor environment in which the front projection display device of the present embodiment is installed as a display system.

FIG. 15 is a spectral distribution diagram showing spectral distribution characteristics of a light source (UHP lamp) of a projection lens in comparison with RGB colors.

FIG. 16 is a spectral distribution diagram showing the spectral distribution characteristics of the projection / illumination device of the present embodiment in comparison with the RGB colors.

FIG. 17 shows the spectral distribution characteristics of the lighting device of the present embodiment,
It is a spectral distribution chart shown in comparison with each color of RGB.

[Explanation of symbols]

1 reflective screen, 2 bead diffusion layer, 3 CLC
Layer, 4 light shielding layer, 4A first light shielding layer, 4B second light shielding layer,
5 substrate, 7 1/4 wavelength plate, 8 absorption type linear polarization plate,
9 diffuse reflection plate, 10, 10a incident light, 20 front projection type display device, 39 polarization axis rotating element, 40 1/4 wavelength plate, 20A projection / illumination device, 50 room, 51 CL
C blind, 52 wall surface, 53 ceiling surface, 54 floor surface, 60 lighting device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 5/126 G02B 5/126 2K103 5/128 5/128 5/30 5/30 G02F 1/13 505 G02F 1/13 505 1/1335 1/1335 G03B 21/00 G03B 21/00 DF Term (reference) 2H021 BA02 BA09 2H042 BA02 BA04 BA05 BA12 BA14 BA19 DA01 DB01 DB02 DB08 DD10 DE00 EA04 EA07 EA14 EA15 2H049 BA03 BA43 BB03 BB63 BC21 2H088 EA14 EA15 EA18 GA03 HA13 HA14 HA17 HA21 HA24 HA28 MA02 2H091 FA05X FA05Z FA12X FA14Z FA26X FA26Z FA41Z LA17 MA07 2K103 AA01 AA11 AA16 AB01 CA01

Claims (26)

[Claims] 1. A reflection type screen for displaying an image by reflecting projection light projected from a front projection type display device, comprising a reflection layer for reflecting the projection light, wherein the reflection layer is a cholesteric liquid crystal. A reflective screen, comprising a layer made of. 2. The cholesteric liquid crystal in the reflection layer selectively reflects a selective reflection wavelength region in a wavelength region which is considered to be higher than a predetermined level in the spectral intensity of the projection light from the front projection type display device. The reflective screen according to claim 1, wherein the reflective screen is set. 3. The reflective screen according to claim 1, wherein a bead layer formed by spreading beads is provided on the front surface side of the reflective layer. 4. A light absorbing member provided so as to be interposed between the bead layer and the reflective layer, wherein the light absorbing member has a thickness that increases from a central portion to a peripheral portion of each bead. The reflective screen according to claim 3, which is different. 5. The reflective layer is formed with a plurality of concave portions corresponding to the curved surfaces of the beads forming the bead layer, and the centers of curvature of the concave portions are deviated from the centers of curvature of the beads. The reflective screen according to claim 3, wherein the reflective screen is provided. 6. The reflective screen according to claim 1, wherein the reflective layer is formed to have a concavo-convex shape formed of a plurality of prism shapes having a predetermined size. 7. The reflective screen according to claim 1, wherein the reflective layer is formed to have a plurality of concave and convex shapes in the shape of a corner cube. 8. A reflection type screen for displaying an image by reflecting projection light for image display projected from the front surface to the front surface side, wherein a circularly polarized light component of one direction in a projected light flux is Reflected,
A reflective screen having a characteristic of absorbing a circularly polarized light component in another direction. 9. A structure in which a quarter-wave plate, an absorption type linear polarization plate and a diffuse reflection plate are laminated in this order from the front side, and a unidirectional circular polarization component of the projected light flux is / 4 wave plate forms linearly polarized light in the first direction, transmits the absorption type linear polarizing plate, and is reflected by the diffusive reflection plate. 9. The reflection type screen according to claim 8, wherein a linearly polarized light in a second direction orthogonal to the first direction is made by the wave plate and is absorbed by the absorption type linearly polarizing plate. 10. A front projection display device for displaying an image by projecting projection light as projection light onto the front surface of a reflection type screen, comprising: polarization conversion means, wherein the polarization conversion means A front projection display device characterized in that projected light is projected as circularly polarized light in a specific direction. 11. The polarization conversion means comprises a quarter-wave plate arranged on an optical path between a color separation / synthesis optical system and a projection lens in a front projection type display device. 11. The front projection type display device according to claim 10. 12. The direction of circularly polarized light of the projected light is reflected on a projection surface of a reflective screen having a characteristic of reflecting a circularly polarized light component in one direction and absorbing a circularly polarized light component in the other direction of the projected light flux. 11. The front projection display device according to claim 10, wherein the front projection display device is in the one direction. 13. A room provided with at least a front projection type display device and a reflection type screen which has a reflection layer composed of a cholesteric liquid crystal layer and onto which projection light from the front projection type display device is projected. An illumination device for illuminating a room, wherein at least illumination light for illuminating the reflection type screen is converted into circularly polarized light which is absorbed by the reflection type screen by a polarization conversion means. 14. A room provided with at least a front projection type display device and a reflection type screen which has a reflection layer made of a cholesteric liquid crystal layer and onto which projection light from the front projection type display device is projected. An illumination device for illuminating a room, wherein at least illumination light for illuminating the reflection type screen is circularly polarized light which is transmitted through the reflection layer composed of the cholesteric liquid crystal layer by a polarization conversion means, and is provided on the rear side of the reflection layer An illuminating device, wherein the illuminating light is absorbed by a light absorbing layer arranged. 15. The illumination device according to claim 13, wherein the polarization conversion means is a cholesteric liquid crystal layer, and emits light emitted from a light source through the cholesteric liquid crystal layer. 16. The light source for the projection light in the front projection display device is used as a light source, and the remaining light component of the light used as the projection light is used as illumination light. Lighting equipment. 17. A room provided with at least a front projection type display device and a reflection type screen which has a reflection layer made of a cholesteric liquid crystal layer and onto which projection light from the front projection type display device is projected. A lighting device for illuminating an interior, wherein the spectral intensity of a wavelength region corresponding to the selective reflection wavelength region of the reflection layer emits illumination light lower than the spectral intensity of a wavelength region other than the selective reflection wavelength region. Characteristic lighting device. 18. The light source of projection light in the front projection display device is used as a light source, and the remaining light component of the light used as the projection light is used as illumination light. Lighting equipment. 19. The light-emitting element that emits light having a wavelength other than the selective reflection wavelength range of the reflective layer is used as a light source, and the light emitted from the light-emitting element is used as illumination light. Illumination device described. 20. A display system having at least a front projection type display device and a reflection type screen on which projection light from the front projection type display device is projected, wherein the reflection type screen comprises a layer made of cholesteric liquid crystal. Having a reflective layer that reflects a circularly polarized light component in one direction of the projected light, the front projection display device provides a projected light that is circularly polarized light in one direction that is reflected by the reflective layer of the reflective screen. A display system, which displays an image by projecting on the reflection type screen. 21. At least illumination light for illuminating the reflection type screen is converted into circularly polarized light which is transmitted through a reflection layer having a layer made of the cholesteric liquid crystal by a polarization conversion means, and is arranged behind the reflection layer. 21. The display system according to claim 20, further comprising an illumination device that absorbs the illumination light with a light absorption layer. 22. An illumination device is provided, which emits illumination light having a spectral intensity in a wavelength region corresponding to the selective reflection wavelength region of the reflective layer lower than a spectral intensity in a wavelength region other than the selective reflection wavelength region. 21. The display system according to claim 20, wherein: 23. A circular polarization filter for transmitting at least the light reaching the reflection type screen out of the outdoor light into the room as a circularly polarized light absorbed by the reflection type screen. Item 21. The display system according to Item 20. 24. Formed from cholesteric liquid crystal,
21. The display system according to claim 20, further comprising a blind curtain that transmits light from the outside into the room as circularly polarized light that passes through a reflective layer having a layer made of the cholesteric liquid crystal. 25. Reflection for selectively reflecting a circularly polarized light component transmitted through a reflective layer having a layer made of the cholesteric liquid crystal on at least a wall surface, a floor surface and a ceiling surface in a range where reflected light reaches the reflective screen. The display system according to claim 20, further comprising a member. 26. The indoor surface of the room in which the front projection display device and the reflection type screen onto which the projection light from the front projection display device is projected are installed has an uneven shape on the surface, 21. The display system according to claim 20, wherein a surface made of cholesteric liquid crystal having a twist direction of a molecular axis opposite to a twist direction of a molecular axis of the layer made of the cholesteric liquid crystal in the reflective layer is formed.