JP3552706B2 - Hologram screen - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a transmission type hologram screen using a hologram element as a screen.
[0002]
[Prior art]
FIG. 17 shows a transparent hologram screen that is attached to a show window or the like and used as a display for displaying an advertisement or the like using a moving image or a still image.
The hologram screen 9 projects projection light 21 onto the hologram element 11 from a projection device 2 (for example, a projector or the like) provided below (or above) the hologram element 11 with respect to the observer 6 as shown in FIG. The image is projected, an image is formed, and the projection light 21 is diffracted and scattered forward by the hologram element 11 so that the observer 6 can recognize the image.
[0003]
The hologram element 11 used in such a transmission type hologram screen 9 has been manufactured by recording a diffuser 88 on a photosensitive member 85 by an exposure optical system 8 as shown in FIG.
[0004]
Here, a laser beam 800 (eg, a wavelength of 514.5 nm) emitted from a laser oscillator 80 (eg, an Ar laser) is split in two directions by a translucent mirror 890.
One light is diverged by the objective lens 831 through the two reflecting mirrors 891, and then projected onto the photosensitive member 85. This light is the reference light 86.
The other light is also diverged by the objective lens 832 through the two reflecting mirrors 892, and is then introduced into the parabolic mirror 89. The light reflected by the parabolic mirror 89 passes through the diffuser 88 to become diffused light, and then is projected on the photosensitive member 85. The light from the diffuser 88 becomes the object light 87.
[0005]
[Problem to be solved]
However, the hologram screen 9 using the hologram element 11 manufactured as described above has a problem that the color of the projected image is not sufficiently reproduced, for example, the image projected from the projection device 2 has a green color tone. I was
[0006]
The spectral characteristics of the hologram element 11 are measured by a method as shown in FIG.
In this measuring method, the white light 901 is incident on the hologram element 11 at an angle equal to the incident angle θr of the reference light 86 of the exposure optical system 8 shown in FIG. In particular, the wavelength and the efficiency (= the intensity of the diffracted light in the direction of 100 × 0 ° / the intensity of the white light [%]) of the diffracted light 902 emitted in the 0 ° direction are measured. The 0 ° direction is a direction perpendicular to the surface of the hologram element 11.
[0007]
From this measurement result, a spectral characteristic having a distribution like the diagram shown in FIG. 20 was obtained. According to the figure, it has been found that this characteristic has a peak in the blue to green wavelength region, and the wavelength in the red region is weak.
That is, since the hologram element 11 has a spectral characteristic having a distribution whose efficiency varies greatly depending on the wavelength, it is considered that the color reproducibility of an image is deteriorated.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a hologram screen having excellent color reproducibility.
[0009]
[Means for solving the problem]
According to the first aspect of the present invention,From diagonally above or belowThe projected lightIn frontdiffraction·scatteringHologram element with the function of
Combined with the hologram element,Including the angle of incidence of the projection light on the center of the hologram element;Within a specific angle of incidenceonlyAnd a light scattering element for scattering the incident projection light.
[0010]
Thereby, the background light of the hologram screen can be transmitted, and only the projection light from the projection device can be scattered. Therefore, color reproducibility can be enhanced without impairing the transparency of the hologram screen.
[0011]
The specific incident angle range is determined by the size of the hologram screen and the positional relationship with the projection device.You.
That is, as shown in FIG. 5, which will be described later, the angle of incidence on the center of the hologram screen is m °, but is 1 or n ° at the end of the hologram screen. In this case, a light scattering element that can scatter light incident in the range of 1 to n is preferable.
That is,It is preferable that the range of the specific incident angle is within the range of the incident angle of the projection light from the upper end to the lower end of the hologram element.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferably, the range of the specific incident angle is 25 to 60 °.3).
In general, the angle at which the projection light from the projection device enters the center of the hologram screen is generally around 35 °.
In such a case, it is preferable to use a light scattering element that can scatter light in the range of the incident angle of about 25 to 60 °.
[0013]
Preferably, the light scattering element has a scattering degree of 5 ° or more.4).
By using a light scattering element having a degree of scattering of 5 ° or more, the effect of the present invention can be reliably obtained as is known from FIG.
If the degree of scattering is less than 5 °, it may be difficult to obtain the effects of the present invention. Further, it is preferable that the upper limit of the degree of scattering is determined by claim 6 described later. If the degree of scattering is higher than this, the projected components may be scattered too much and the image may be dark, or the transparency of the hologram screen may be impaired.
The definition of the degree of scattering is described in Example 2 described later.
[0014]
Claim4The hologram screen according to the invention is a combination of a hologram element and a light scattering element.
Here, the effect of the light scattering element will be described. In order to clarify the effect of the light scattering element, first, the principle of the transmission type hologram screen will be described.
[0015]
As shown in FIG. 18 described above, interference fringes having various inclinations are recorded on the hologram element on which the diffuser 88 relating to the exposure optical system 8 is recorded.
That is, in any part of the hologram element, not only one type of interference fringe is recorded at one location but multiple types of interference fringes are recorded at one location.
[0016]
FIG. 8 schematically illustrates the state of such a hologram element.
However, FIG. 8 illustrates three interference fringes for three types of interference fringes for simplicity, and one of the interference fringes is particularly indicated by a thick line. More interference fringes are recorded in an actual hologram element.
[0017]
As shown in FIG. 9, the inclination of the interference fringes is such that, at an arbitrary point 850 on the photosensitive member 85 in the exposure optical system 8, the object light 870 that interferes with the reference light 860 is incident from any position on the diffusion plate 88. Is determined by
For example, the interference fringe a in FIG. 8 is formed by interference between the object light 8-a in FIG. 9 and the reference light 860, and the interference fringe b or c in FIG. 8 is the object light 8-b in FIG. Alternatively, 8-c and reference light 860 are formed by interference.
[0018]
FIG. 10 shows the state of the diffracted light 290 when the white light 29 is incident on such interference fringes a or b at the same angle θr as the reference light 86 applied to the exposure optical system 8.
FIG. 10A illustrates the case where the white light 29 is incident on the interference fringe a, and FIG. 10B illustrates the case where the white light 29 is incident on the interference fringe b.
[0019]
When the white light 29 is incident on the interference fringe a, light having the same wavelength as the recording wavelength is diffracted in the direction of the arrow y. The direction of the arrow y is the same as the direction of the object light 8-a shown in FIG. The diffracted light 290 obtained from the white light 29 is a component other than the diffracted light diffracted in the arrow direction y, a component diffracted in the direction of the arrow x by light having a wavelength longer than the recording wavelength, and a light having a shorter wavelength. And a component diffracted in the direction of arrow z.
[0020]
That is, the white light 29 becomes diffracted light 290 color-separated into an elliptical range shown in FIG. 10A and is diffracted and scattered forward from the hologram element.
Then, of the diffracted light 290, only the diffracted light component diffracted in the direction of the arrow v, which is the 0 ° direction, is detected in the above-described measurement of the spectral characteristics.
[0021]
FIG. 10B shows a case where white light 29 is incident on the interference fringe b. In this case, the white light 29 is diffracted and scattered while being color-separated into an elliptical area shown in FIG. 3, and among the diffracted lights, light having the same wavelength as the recording wavelength is diffracted in the direction of the arrow y. . In this case, since the direction of the arrow y is equal to the 0 ° direction, the light detected in the measurement of the spectral characteristic is the light diffracted in the direction of the arrow y.
Thus, the wavelength of the light diffracted in the direction of 0 ° differs according to the inclination of the interference fringes.
[0022]
As described above, all interference fringes recorded on an arbitrary portion of the hologram element form diffracted light having various wavelengths and directions.
Then, the sum total of the diffracted light in the 0 ° direction formed by all the interference fringes is detected in the spectral characteristics, and forms a spectral characteristic diagram having peaks in the blue and green regions as shown in FIG. It is.
This spectral characteristic reflects the state of light from the hologram screen that enters the eyes of the observer in front of the screen (that is, even if the diffracted light from the hologram screen has a blue or green color tone even in the observer). Observed).
[0023]
Here, using FIG. 11, diffracted light when white light 28 is incident on interference fringe b shown in FIG. 10B at an angle g larger than the incident angle θr of reference light 86 applied to exposure optical system 8. The state of 290 will be described.
[0024]
As can be seen from Bragg's diffraction formula, in such a case, light having the same wavelength as the recording wavelength is diffracted in the direction of the arrow z, and light having a wavelength longer than the recording wavelength is shifted in the direction of the arrow x, that is, in the direction of 0 °. It will be diffracted.
Conversely, when white light is incident at an angle smaller than the incident angle θr, light having a wavelength shorter than the recording wavelength is diffracted in the 0 ° direction.
[0025]
Therefore, when white light having a certain range of the incident angle is incident on an interference fringe having a certain inclination, the diffracted light diffracted in the 0 ° direction by the interference fringe has a wider wavelength distribution. Become. Therefore, the spectral characteristics of the diffracted light can be broad with little difference in efficiency depending on the wavelength.
That is, by giving the incident angle of the projection light to the hologram element a certain width, the diffracted light from the hologram element becomes a state closer to white, which is closer to the light source color.
[0026]
The present invention has been devised based on the above considerations, and is intended as a means for giving a certain width to the incident angle of the projection light (corresponding to the white light according to the above description) from the projector to the hologram element. , A light scattering element and a hologram element. Thereby, the color reproducibility of the projection light can be improved.
[0027]
Note that the above discussion has mainly described projection light incident on the hologram element. Conversely, by scattering the diffracted light emitted from the hologram element, the same effect as described above can be obtained.
In this case, the diffracted light from the hologram element obtained by injecting white light has a peak in the blue or green wavelength region as described above, but the diffracted light is transmitted by an appropriate light scatterer. Can be set to a white state closer to the light source color.
Thereby, the color reproducibility of the projection light can be improved.
[0028]
As described above, according to the present invention, a hologram screen having excellent color reproducibility can be provided.
[0029]
Further, the light scattering element can be arranged at a certain distance from the hologram element.
In other words, when the light scattering element scatters the projection light so that an image is projected on the hologram element, the image projected on the hologram element is not overlapped with the image projected on the hologram element. It is necessary to keep a certain distance.
[0030]
In addition, when the distance between the light scattering element and the hologram element is large, the component of the projection light scattered at an angle that cannot enter the hologram element increases, and the utilization efficiency of the projection light deteriorates. The image may be dark (when a light scattering element is provided on the side where the projection light is incident).
For this reason, it is preferable to arrange the light scattering element and the hologram element as close as possible.
[0031]
Further, it is preferable that the light scattering element is arranged on the projection device side.5). Alternatively, it is preferable that the light scattering element is arranged on the side opposite to the projection device side.No.
[0032]
It is preferable that the vertical transmittance of the light scattering element is in the range of 30% to 100%.
Thereby, the light scattering element can transmit the background light of the hologram screen. Therefore, the observer can observe the object behind the hologram screen through the hologram screen and expand the application range of the hologram screen. use).
[0033]
In addition, the above-mentioned light-scattering element reduces incident light at least.
sin^-1{Sin θi−λ1 / λ0 · (sin θo−sin θr)} ≦ θ ≦ sin^-1{Sin θi−λ2 / λ0 · (sin θo−sin θr)}
(However, λ0: hologram recording wavelength, λ1 = 380 nm, λ2 = 780 nm [visible light region is 380 to 780 nm], θr: reference light incident angle, θo: object light incident angle, θi: diffracted light emission angle)
Is preferably scattered within the range of the angle θ determined by the mathematical formula.
[0034]
Thereby, the color of the projection light from the projection device can be almost completely reproduced. If θ is less than the lower limit of the above-described range, the user may feel that color reproducibility is poor. On the other hand, if θ exceeds the above range, the image may be too dark or the transparency of the hologram screen may be impaired.
[0035]
Note that λ0 in the above equation is a recording wavelength when a hologram element is manufactured. That is, when the laser beam 800 in the exposure optical system 8 according to FIG. 18 is an Ar laser, λ0 = 514.5 nm. Since λ1 and λ2 are the wavelengths at both ends of the visible light region, they are 380 nm and 780 nm, respectively.
As shown in FIG. 7A, θr is the incident angle of the reference light 86 on the point 85 on the photosensitive member 85 in the exposure optical system 8, θo is the incident angle of the object light 87, and θi is As shown in (b), the emission angle of the diffracted light 211 diffracted and scattered by the hologram element 11 becomes θi.
[0036]
As a substantial problem, if the light scattering element has a performance capable of scattering incident light at an angle determined by setting the incident angle θo of the object light 87 to 0 ° and the output angle θi of the diffracted light 211 to 0 °. In addition, sufficient color reproducibility can be obtained so that there is no problem in visually observing the projection light.
[0037]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Example 1)
A hologram screen according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the hologram screen 1 of this embodiment is formed by combining a hologram element 11 having a function of diffracting a projection light 21 projected from a projection device 2 and a light scattering element 12, and Reference numeral 12 is disposed on the projection device 2 side via the adhesive layer 13.
[0038]
The light scattering element 12 is
sin^-1{Sin θi−λ1 / λ0 · (sin θo−sin θr)} ≦ θ ≦ sin^-1{Sin θi−λ2 / λ0 · (sin θo−sin θr)}
(However, λ0: hologram recording wavelength, λ1 = 380 nm, λ2 = 780 nm [visible light region is 380 to 780 nm], θr: reference light incident angle, θo: object light incident angle, θi: diffracted light emission angle)
Has a function of scattering incident light within a range of an angle θ determined by the mathematical formula (1).
[0039]
Hereinafter, the details will be described.
The hologram element 11 according to this example is manufactured by the above-described exposure optical system 8 according to FIG. In the exposure optical system 8, as shown in FIG. 7A, a diffusion plate 88 is arranged so that the incident angle θo of the object light is −20 to 10 °. Further, as shown in FIG. 7A, the incident angle θr of the reference light 86 is 35 °.
[0040]
Further, as shown in FIGS. 5 and 6, the projection light 21 is scattered by the light scattering element 12 and becomes the scattered projection light 210 to be incident on the hologram element 11. As shown in FIG. 7B, the scattered projection light 210 is diffracted and scattered by the hologram element 11 to become a diffracted light 211. The output angle θi of the diffracted light is 0 ° since the observer observes the screen in front of the hologram screen.
[0041]
Therefore, when θr = 35 °, θo = 0 °, and θi = 0 ° were substituted in the above formula, the range of θ was 25 to 60 °.
In this example, a directional light scattering film having an adhesive layer 13 (Lumisti-MFY-2555, manufactured by Sumitomo Chemical Co., Ltd.) was used as the light scattering element having such scattering characteristics.
[0042]
FIG. 2 shows the scattering characteristics of the directional light scattering film.
The scattering characteristics are obtained by measuring the intensity of scattered light β emitted for each θ by injecting white light α at an angle of 35 ° into the directional light scattering film in a measurement system as shown in FIG.
As shown in FIG. 2, the directional light-scattering film used in this example transmits light incident at an angle of approximately 20 ° or less, but light scattered from an angle exceeding 20 ° may be scattered. it can. However, a realistic scattering power is obtained in the range of 25 to 60 °.
[0043]
For this reason, by using this directional scattering film as the light scattering element 12 in the hologram screen 1, the background light of the hologram screen 1 passes through the screen and reaches the observer 6. The observer 6 can observe the background light and feels that the hologram screen 1 is transparent.
The adhesive layer 13 is made of a material having high transparency, and does not impair the transparency of the hologram screen.
[0044]
Next, FIG. 4 shows a result obtained by measuring the spectral characteristics described in the above-described prior art for the hologram screen 1 according to the present embodiment. For comparison, the spectral characteristics of the hologram element 11 alone are also described.
[0045]
As can be seen from the figure, the spectral characteristics of the hologram screen 1 are broad with very little difference in efficiency depending on the wavelength, and the image of the hologram element 11 alone has a greenish color tone even through observation with the naked eye. It was confirmed that the color of the image of the projector could be reproduced almost completely.
[0046]
Next, the operation and effect of this embodiment will be described.
FIG. 5 shows the hologram screen 1 according to the present example in which the light scattering element 12 and the hologram element 11 are combined.
The projection light 21 from the projection device 2 becomes scattered projection light 210 in the light scattering element 12 and enters the hologram element 11.
As shown in FIG. 6, when viewed from the point A on the hologram element 11, the scattered projection lights 210 scattered at different positions on the light scattering element 12 enter from different angles as indicated by 3a, 3b and 3c. .
[0047]
By providing the light scattering element 12 in this manner, the incident angle of the projection light 21 on the hologram element 11 has a certain range.
Therefore, the spectral characteristics of the hologram element 11 can be broadened, and the color reproducibility of the hologram screen 1 can be improved.
[0048]
The directional light scattering film may be translucent if the hologram screen does not need to be completely transparent (for example, a colored screen). The same applies to the adhesive layer 13.
Also, a hologram element having a light scattering function can be used as the light scattering element. For example, the same effect as that of the light scattering element can be obtained by laminating one or a plurality of the same hologram elements as those used in this example.
Further, in the present embodiment, the light scattering element 12 is provided on the projection device 2 side, but the light scattering element may be provided on the observer side.
[0049]
(Example 2)
In this example, a performance test on the degree of scattering of the light scattering element will be described with reference to FIGS.
Here, the optimum scattering degree of the light scattering element used in the present invention was determined. The experimental results are shown below.
In the experiment, one to five translucent films were laminated to form a laminate. As shown in FIG. 12, incident light 51 composed of laser light having a wavelength of 514.5 nm was incident on each of the obtained laminates 52 at an angle of 35 °. The luminance of the outgoing light 53 that has passed through each laminated body 52 was measured while moving the luminance meter 5 in the angle θ direction.
[0050]
The light receiving ratio of (K / K0) × 100 [%] was calculated, where K is the luminance at each obtained θ and K0 is the luminance at θ = 0 °. The obtained light receiving ratio is plotted on the vertical axis and θ is plotted on the horizontal axis to obtain the diagram shown in FIG.
In the figure, the range of θ when the light receiving ratio is 50% or more is defined as the scattering degree. That is, for example, in a single translucent film, the range where the light receiving ratio is 50% or more is 34 to 36 °. In this case, the degree of scattering is 2 °. Others are the same.
[0051]
A hologram screen having the structure according to Example 1 was manufactured using each of the laminates 52 described above. For comparison, a conventional hologram screen having the same structure and no laminated body was also manufactured. Furthermore, a normal opaque white screen that does not use a hologram element was also prepared.
[0052]
Then, the same projection light was projected from the same projector to each hologram screen, the conventional hologram screen, and the opaque white screen, and a plurality of observers observed the color of the image projected on each screen. This observation result is shown in FIG.
In FIG. 5, "no change" indicates that the state is the same as that of the conventional hologram screen. "Improved" indicates that the color tone is improved as compared with the conventional hologram screen. "Very good" indicates that the image is close to the image on an opaque white screen.
[0053]
As can be seen from the figure, it was found that most observers felt that the color reproducibility of the image projected on the hologram screen produced with the light scattering element having a scattering degree of 5 ° or more was improved.
Further, it was found that the light scattering element could be used alone, but a plurality of light scattering elements could be used.
[0054]
(Reference example)
In this example, as shown in FIGS. 15 and 16, a hologram screen used by sticking to a window glass is described.
As shown in FIG. 15, the hologram screen 1 according to the present embodiment is configured by sandwiching the hologram element 11 with a cover film 85 via an adhesive 13 and further adhering a light scattering element 12 with an adhesive 13. The light scattering element 12 is arranged on the side opposite to the projection device 2 side.
Such a hologram screen 1 is adhered to a window glass 70 via an adhesive 13.
Others are the same as the first embodiment.
[0055]
Incidentally, FIG. 16 shows a hologram screen 7 having the same configuration as described above and having no light scattering element 12.
When the projection light 21 is projected onto the hologram screen 7 by the projection device 2, the projection light 21 is diffracted and scattered by the hologram element 11, and is emitted from the window glass 70 as emission light 215. The emitted light 215 forms an image that the observer 6 can observe.
The outgoing light 215 has a spread due to the interference fringes formed on the hologram element 11 as described above, but only the center direction of the spread is illustrated in the drawing of this example.
[0056]
By the way, not all of the projection light 21 is diffracted and scattered, and part of the light 21 passes through the hologram element 11. This is the zero-order light 219.
When the observer 6 comes on the ray of the zero-order light 219, the zero-order light 219 is directly incident on the eyes of the observer 6, and the observer feels glare.
[0057]
Conventionally, such a problem of glare has been dealt with by disposing a louver filter or the like on the hologram element 11 on the side of the observer 6 to block the zero-order light 219.
[0058]
However, the louver filter accidentally blocks outgoing light diffracted and scattered in the same direction as the 0th order light 219 together with the 0th order light 219. For this reason, when observing the hologram screen 7 from the same direction as the 0th-order light 219, a problem has arisen that the image cannot be seen because the emitted light does not reach.
[0059]
However, in the hologram screen 1 of this example, as shown in FIG. 15, the light scattering element 12 is arranged on the side opposite to the projection device 2.
Therefore, the zero-order light 219 that has passed through the hologram element 11 is scattered by the light scattering element 12, becomes a spread state, and becomes diffused light 218 that diffuses toward the observer 6.
[0060]
Therefore, it is possible to prevent the observer 6 in the same direction as the zero-order light 219 from feeling glare.
Further, the outgoing light arriving from the same direction as the zero-order light 219 is also diffused, but is not blocked. Therefore, the image does not disappear.
Note that this embodiment also has the same operation and effect as the first embodiment.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the use of a hologram screen according to a first embodiment.
FIG. 2 is a diagram showing scattering characteristics of the light scattering element according to the first embodiment.
FIG. 3 is an explanatory diagram of a measurement system of a scattering characteristic of the light scattering element according to the first embodiment.
FIG. 4 is a diagram showing spectral characteristics of the hologram screen and the hologram element of the present embodiment alone according to the first embodiment.
FIG. 5 is an explanatory view showing the structure of the hologram screen according to the first embodiment;
FIG. 6 is an explanatory diagram showing an effect of the light scattering element in the hologram screen of the present embodiment according to the first embodiment.
FIGS. 7A and 7B are explanatory views of a main part in an exposure optical system for producing a hologram element according to the first embodiment, and FIG. 7B is an explanatory view of diffracted light from the hologram element.
FIG. 8 is an explanatory diagram of interference fringes in the hologram element.
FIG. 9 is an explanatory view of a main part of an exposure optical system for producing a hologram element.
FIG. 10 is an explanatory diagram showing a certain interference fringe in the hologram element and a state of white light interfered by the interference fringe.
FIG. 11 is an explanatory diagram illustrating a state in which white light is incident on a certain interference fringe in the hologram element at an angle g larger than the incident angle θr of the reference light applied to the exposure optical system.
FIG. 12 is an explanatory diagram showing a method for measuring a light receiving rate according to the second embodiment.
FIG. 13 is an explanatory diagram showing a relationship between a laminated body and a light receiving rate at θ according to the second embodiment.
FIG. 14 is a distribution diagram showing the relationship between the degree of scattering and the state of color reproducibility according to the second embodiment.
FIG.Reference exampleFIG. 3 is a cross-sectional explanatory view of a hologram screen provided with a light scattering element on the side opposite to the projection device according to the first embodiment.
FIG.Reference exampleFIG. 2 is a cross-sectional explanatory view of a hologram screen without a light scattering element according to FIG.
FIG. 17 is a diagram illustrating the use of a hologram screen according to a conventional example.
FIG. 18 is an explanatory view of an exposure optical system for producing a hologram element.
FIG. 19 is an explanatory diagram of a measurement system of spectral characteristics of a hologram element.
FIG. 20 is a diagram illustrating spectral characteristics of a hologram element.
[Explanation of symbols]
1. . . Hologram screen,
11. . . Hologram element,
12. . . Light scattering element,
2. . . Projector,
21. . . Projected light,

Claims (7)

A hologram element having a function of diffracting and scattering the projection light projected from obliquely above or below the projection device forward is combined with the hologram element, and the incident angle of the projection light to the center of the hologram element is determined. A hologram screen comprising: a light scattering element for scattering projection light incident only within a specific incident angle range. 2. The hologram screen according to claim 1, wherein the range of the specific incident angle is within a range of the incident angle of the projection light from the upper end to the lower end of the hologram element. 2. The hologram screen according to claim 1, wherein the range of the specific incident angle is 25 to 60 [deg.]. 2. The hologram screen according to claim 1, wherein the light scattering element has a degree of scattering of 5 ° or more. 2. The hologram screen according to claim 1, wherein the light scattering element is disposed on a projection device side. The hologram screen according to any one of claims 1 to 5, wherein a vertical transmittance of the light scattering element is in a range of 30 to 100%. The light scattering element according to any one of claims 1 to 6, wherein the light scattering element converts incident light into at least sin ^-1 {sin θi-λ1 / λ0 · (sin θo −sin θr)}.
≦ θ ≦ sin ^-1 {sin θi−λ2 / λ0 · (sin θo−sin θr)}
(However, λ0: hologram recording wavelength, λ1 = 380 nm, λ2 = 780 nm [visible light region is 380 to 780 nm], θr: reference light incident angle, θo: object light incident angle, θi: diffracted light emission angle)
A hologram screen that scatters light within a range of an angle θ determined by the mathematical formula (1).

Images