JPH11174232A - Diffusing and reflecting board, screen for projector using the same and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diffusing and reflecting board and a screen for projector using the same with which diffused and reflected light can be limited into desired angle range, uniform luminance can be provided within a visual area, the center of the visual area can be located in the normal direction of the diffusing and reflecting board even when illuminating light is not photographed and the direction of projecting light is located at an angle different from the normal direction of the diffusing and reflecting board, and the wavelength characteristics of the diffused and reflected light can be controlled. SOLUTION: Three hologram recording films 83, 84 and 85 are successively stuck on a base film 82 and a light absorbing layer 86, protecting layer 87 and reflection reducing layer 88 are applied on these films. Cubic holograms for diffusing and reflecting red, green and blue are respectively formed on the hologram recording films 83, 84 and 85. The cubic hologram is a paraboloid inclining the shape of the interface of each layer from the vertical direction of a screen 81 for projector on its paraboloid or central axis, and such a fine put is arranged inside the plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector screen or a reflection type liquid crystal display device using a diffuse reflection plate.

[0002]

2. Description of the Related Art In a diffusion plate used for a projector screen or a reflection type liquid crystal display device, it is desirable that light is diffused only within a desired angle range and uniform brightness is obtained within the angle range.

Further, in a diffusion plate used for a projector screen or a reflection type liquid crystal display device, it is desirable that the center of the diffusion direction is different from the regular reflection direction of the illumination light. This is because the position of the projection light source cannot be freely set if the center of the diffusion direction of the diffusion plate matches the regular reflection direction of the illumination light. In particular, in the case of a reflection type liquid crystal display device, the illumination light source is reflected by the surface reflection of the front transparent substrate, which is dazzling. Alternatively, we want to set good visibility when viewed from the normal direction, but in that direction, the human head blocks the illumination light from the normal direction, so the display is dark and the visibility is low. Is bad.

Further, in a diffusion plate used for a projector screen, contrast is reduced when room illumination light or the like other than projection light is diffused by the screen. Therefore, in order to increase the contrast at the time of illumination without impairing the brightness of the screen, it is necessary to diffusely reflect only the wavelength band of the projection light by using projection light having a narrow wavelength width such as a laser projector. desirable.

In a diffusion plate used for a reflection type color liquid crystal display device, if a wavelength band corresponding to RGB is diffusely reflected, it is convenient because it is not necessary to separately add a color filter. Therefore, in order to increase the reflection luminance and the color purity, the reflection wavelength band is set to 100 nm.
It is desirable that the wavelength be set so that the wavelength characteristic of the reflected luminance is sharp.

Here, in the case of using a diffusion plate in which beads or the like are dispersed or a metal is roughened, the degree of diffusion is changed depending on conditions such as the refractive index of the beads, the particle size, the dispersion concentration, or the particle size of the rough surface. be able to. As a result, a diffuser used for a projector screen or a reflective liquid crystal display device is a diffuser in which beads or the like are dispersed or a metal is roughened.

However, when the diffusion angle is set to a small value, the screen gain is increased, but the change in luminance in the diffusion direction is large. Also, by setting this diffusion angle to a large value, even if an attempt is made to obtain uniform luminance within a desired angle range, the characteristic of the intensity of the diffused light with respect to the angle becomes slow. Increases and the screen gain decreases. In other words, a sufficiently large screen gain and dispersion of beads or the like, or a diffuser plate with a roughened metal,
It is difficult to obtain uniform brightness within a desired angle range.

On the other hand, with regard to the angular characteristics of a diffuser plate having a roughened metal surface, the luminance of the reflected light is normally distributed on a rough surface with a normal inclination angle of a normal distribution type, and the uniformity is limited. It is known. By taking advantage of this fact, it has been practiced to intentionally shift the tilt angle from the normal distribution type to flatten the luminance characteristics of the reflected light and improve the uniformity (N. Sugiura et al., Digest of Technical Papers, AM
-LCD94, p92 and N.Sugiura et al., Digest of Tech
nical Papers, AM-LCD95, p153).

In a reflection type projection screen, a lenticular sheet, a fine convex mirror, a fine concave mirror, a spherical projection, or the like is used to improve the uniformity of diffused light luminance and the screen gain, or to make the diffusion angle off-axis by a Fresnel lens. (Japanese Unexamined Patent Publication No. 6-25 / 1994)
8717 and JP-A-8-29875).

Further, with respect to the reflection type hologram, off-axis of the diffusion angle is performed at the same time as improving the uniformity of the luminance of the diffused light (JP-A-8-123300).

[0011]

SUMMARY OF THE INVENTION
N.Sugiura et al., Digest of Technical Papers, AM-LCD9
4, p92 and N.Sugiura et al., Digest of Technical
Papers, AM-LCD95, p153, the above-mentioned JP-A-6-258717 and JP-A-8-298.
In the diffusion plate according to the method described in Japanese Patent Application Laid-Open No. 75-7575, it is possible to control uniformity and off-axis of diffused light luminance, but not to control the wavelength characteristics of diffused reflected light.

Further, according to the method described in the above-mentioned Japanese Patent Application Laid-Open No. 8-123300, a hologram produced by using a plane-wave laser beam as a reference beam and causing the laser beam passed through a diffusion plate to interfere as an object beam. In, the wavelength characteristic of the reflected light becomes slow, and the reflected wavelength characteristic cannot be made sharp.

In addition, a hologram produced by causing a hologram recording film to interfere with a laser beam having passed through a lens array as an object beam using a plane-wave laser beam as a reference beam and TJTrout et al., Proc. SPIE, Vol. 2577, p9
As described in 4-105 (1995), the reflection bandwidth of a normal hologram recording film is as small as about 20 nm. Therefore, it can be used only for illumination light with a narrow wavelength width such as laser light, and is used for applications requiring reflection at a wavelength width of about 100 nm, such as a color filter used for a color liquid crystal display device. In this case, the reflected light luminance becomes extremely low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to be able to restrict diffused light to a desired angle range, to obtain uniform luminance in a viewing zone, and to obtain illumination light. Even if the illumination direction is at an angle different from the normal direction of the diffuser, the center of the viewing zone is adjusted by the diffuser so that there is no reflection and good visibility can be obtained when viewed from the normal direction. It is an object of the present invention to provide a diffuse reflector that can be positioned in a linear direction and that can control the wavelength characteristics of diffuse reflected light, and a projector screen and a reflective liquid crystal display device using the same. is there.

[0015]

According to a first aspect of the present invention, there is provided a diffuse reflection plate, comprising: a high refractive index layer having a relatively high refractive index at a layer interval corresponding to a reflection wavelength; A low refractive index layer having a low refractive index is alternately laminated, and a lens sheet or a lenticular sheet is disposed on an optical path in front of the volume hologram.

With the above configuration, the incident light is reflected by the volume hologram, and the reflected light can be diffused by the lens sheet or the lenticular sheet disposed on the optical path in front of the volume hologram.

Therefore, the diffuse reflection light can be limited to a desired angle range, uniform luminance can be obtained in the viewing zone, there is no reflection of illumination light, and good visibility can be obtained when viewed from the normal direction. As can be obtained, even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be located in the normal direction of the diffuse reflector.

Further, the reflection bandwidth of the volume hologram can be controlled by the refractive index of each layer. In addition, the very narrow reflection bandwidth is very advantageous for laser light applications.

According to a second aspect of the present invention, there is provided a diffuse reflection plate comprising a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index at a layer interval corresponding to the reflection wavelength. Are formed alternately, and the shape of the interface of each layer of the formed volume hologram in a minute portion in the plane of the volume hologram is such that the central axis is in the vertical direction of the diffuse reflection plate. An object surface or a paraboloid whose central axis is inclined from the vertical direction of the diffuse reflection plate, and the minute portions are arranged in the surface.

With the above configuration, if the shape of the interface of each layer in the volume hologram is a paraboloid whose central axis is perpendicular to the diffuse reflection plate, the direction of reflection of light incident on the volume hologram is parabolic. It is similar to a mirror. That is, when light enters the hologram from the normal direction of the surface of the sheet, the reflected light spreads within an angle range twice as large as the maximum tilt angle of the paraboloid, and the brightness within that range becomes constant. In addition, if the shape of the interface of each layer of the volume hologram is a parabolic surface whose central axis is inclined from the vertical direction of the diffuse reflection plate, diffraction occurs around the direction of specular reflection with respect to a plane perpendicular to the central axis. Light is emitted.

Therefore, the diffuse reflection light can be limited to a desired angle range. Therefore, the illumination direction is the same as the normal direction of the diffuse reflector so that uniform brightness is obtained in the viewing zone, there is no reflection of illumination light, and good visibility is obtained when viewed from the normal direction. Even at different angles, the center of the viewing zone can be located in the direction normal to the diffuse reflector.

According to a third aspect of the present invention, there is provided a diffuse reflection plate, comprising: a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index at a layer interval corresponding to a reflection wavelength. Are alternately laminated, and in a minute portion in the plane of the volume hologram, the inclination angle of the interface of each layer of the formed volume hologram differs between the minute portions in the plane, and the minute portion is While being arranged in the plane,
A diffusion transmission plate is provided on the optical path in front of the volume hologram.

According to the above configuration, the angle of inclination of the interface of each layer of the volume hologram differs between minute portions in the plane, and the incident light on the hologram sheet in which the minute portions having different inclination angles are arranged in the plane has a volume Since the light is reflected in the direction of the angle corresponding to the inclination angle of each interface of each layer formed on the hologram, diffracted light is emitted at a plurality of angles. By disposing a diffusion plate on this hologram sheet, desired diffusion angle characteristics can be obtained.

Further, the diffusion plate used at this time may be a diffusion plate having a relatively small diffusion angle. The method of diffusing light in a wide range of angles using only the diffusion plate requires a large diffusion angle, so that the diffusion angle characteristics become slow and the backward diffusion increases. On the other hand, a diffusion plate having a relatively small diffusion angle has an advantage that the diffusion angle characteristic is steep and the back diffusion is small, so that the reduction in contrast due to the back diffusion is small.

Therefore, the diffuse reflection light can be limited to a desired angle range, uniform brightness can be obtained in the viewing zone, there is no reflection of illumination light, and good visibility can be obtained when viewed from the normal direction. As can be obtained, even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be positioned in the normal direction of the diffuser.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, in addition to any one of the first to third aspects, the volume hologram includes a plurality of types of minute portions having different reflection wavelengths. It is characterized in that, for each set of minute portions of each kind, the minute portions are arranged in the plane.

According to the above configuration, in addition to the operation according to any one of the first to third aspects, the minute portions having holograms recorded at different wavelengths diffusely reflect the light having the respective reflection wavelengths. Therefore, it is possible to form a volume hologram in which a plurality of desired reflection wavelengths are selectively hologram-recorded on one diffuse reflection plate. Therefore, by forming a volume hologram that diffusely reflects wavelength bands corresponding to three colors of red, green, and blue, a color display with good brightness and visual characteristics can be performed.

According to a fifth aspect of the present invention, in order to solve the above problem, in addition to any one of the first to fourth aspects, the volume hologram is formed by stacking a plurality of volume holograms having different reflection wavelengths. It is characterized by being.

According to the above configuration, in addition to the operation according to any one of the first to fourth aspects, the volume holograms obtained by recording holograms having different wavelengths and laminating diffusely reflect light having respective reflection wavelengths. Therefore, it is possible to form a volume hologram in which a plurality of desired reflection wavelengths are selectively hologram-recorded on one diffuse reflection plate.
Also, set the reflection wavelength so that the reflection band is adjacent,
By stacking volume holograms, the reflection bandwidth can be increased.

Accordingly, a volume hologram for diffusely reflecting wavelengths corresponding to the three colors of red, green, and blue is formed, and a volume hologram having a reflection wavelength for each color so that the reflection band is adjacent to each other to reduce the reflection bandwidth. By expanding, the appropriate reflection bandwidth as the wavelength band of each color is secured,
Color display with good brightness and visual characteristics can be performed.

According to a sixth aspect of the present invention, in order to solve the above-mentioned problems, in addition to any one of the first to fifth aspects, the volume hologram has a layer interval of the thickness of the diffuse reflector. It is characterized by a monotonous change in the direction.

According to the above configuration, in addition to the operation of any one of the first to fifth aspects, the reflection wavelength changes as the layer interval monotonously changes in the thickness direction of the diffuse reflection plate. Thereby, the reflection bandwidth of the volume hologram can be increased. Therefore, by increasing the reflection bandwidth, it is possible to adjust the diffuse reflection plate so as to have an appropriate reflection bandwidth.

The projector screen of claim 7 is:
In order to solve the above-mentioned problem, a diffuse reflection plate according to any one of claims 1 to 6 is provided as a screen.

With the above configuration, the diffuse reflection light can be limited to a desired angle range, uniform brightness can be obtained in the viewing zone, there is no reflection of illumination light, and good light is seen when viewed from the normal direction. Even if the projection direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be positioned in the normal direction of the projector screen so that visibility can be obtained.

Also, since projection light having a narrow wavelength width such as a laser projector can be used to diffusely reflect only the wavelength band of the projection light, the illumination can be performed without impairing the brightness of the screen for the projector. When the contrast is high.

Accordingly, by diffusing and reflecting only the wavelength band corresponding to the wavelength of the projection light, it is possible to provide good brightness and visual characteristics, and to perform display with good contrast even during illumination.

According to an eighth aspect of the present invention, in order to solve the above problems, the diffuse reflection plate according to any one of the first to sixth aspects is provided on a light path as a reflection type color filter. It is characterized by:

With the above configuration, the diffuse reflection light can be limited to a desired angle range, uniform luminance can be obtained in the viewing zone, there is no reflection of illumination light, and good light is seen from the normal direction. Even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be positioned in the normal direction of the diffuse reflector so that visibility can be obtained. The wavelength characteristic of the reflected light can be controlled.

That is, by diffusing and reflecting the wavelength bands corresponding to the three colors of red, green and blue, there is no need to separately add a color filter, and a color display with good brightness and visual characteristics can be performed. Can be.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a diffuse reflector according to the following embodiments will be described.

When light from a certain direction is incident on a volume hologram in which layers having a relatively high refractive index and layers having a low refractive index are alternately laminated at a layer interval corresponding to a desired wavelength, each layer has If the interface is flat, diffracted light is emitted in the direction of specular reflection on that surface. At this time, if the interface of each layer is formed at an oblique angle with respect to the surface of the sheet on which the volume hologram is formed, the direction of specular reflection is not at the interface of the sheet but at the interface of each layer. Diffracted light is emitted.

Although such a hologram sheet itself does not have a light diffusing property, a desired diffusion angle characteristic can be obtained by disposing a diffusion plate or a lens sheet on the hologram sheet.

Further, such a volume hologram is characterized in that it has a high reflectance at a specific wavelength and hardly reflects at other wavelengths. Regarding the wavelength width of the reflected light of the volume hologram, the refractive indexes of the high refractive index layer and the low refractive index layer are respectively nH and nL, the central reflection wavelength is λc, and the reflection bandwidth (full width at half maximum) is △ λ. When the number of layers having a high refractive index and a layer having a low refractive index, which are alternately stacked, is sufficiently large and the difference between nH and nL is small, △ λ / λc is approximated to nH and nL. Therefore, the following relationship holds.

Δλ / λc〜2 (nH−nL) / (πnL) That is, the wavelength width of the reflected light of the volume hologram can be controlled by the refractive index of each layer.

As a simple method of producing a volume hologram, there is a method of subjecting a hologram recording film to interference exposure. In this case, a layer having a large difference in refractive index between a laminated layer having a high refractive index and a layer having a low refractive index is used. However, it is about 0.1, and the reflection bandwidth is about 20 nm. Such an extremely narrow reflection bandwidth is very advantageous for use with laser light.

However, on the other hand, for an application to a color filter of a reflection type liquid crystal display element, it is necessary to have an appropriate reflection bandwidth, so that an extremely narrow reflection bandwidth is a fatal drawback. On the other hand, it is possible to increase the reflection bandwidth by laminating a large number of volume holograms having different layer intervals between the high refractive index layer and the low refractive index layer which are alternately laminated. Also, the reflection bandwidth can be widened by a method of modulating the layer interval in the thickness direction. In the method of modulating the layer spacing in the thickness direction, the number of manufacturing steps can be significantly reduced as compared with the method of laminating many volume holograms having different layer spacings.

As another method for obtaining a desired diffusion angle characteristic, if the interface of each layer in the volume hologram is a paraboloid whose axis of rotation is the normal to the surface of the sheet, the incidence on this volume hologram is The light reflection direction is the same as that of the parabolic mirror. That is, when light enters the hologram from the normal direction of the surface of the sheet, the reflected light spreads within an angle range twice as large as the maximum tilt angle of the paraboloid, and the brightness within that range becomes constant. At this time, if the axis of rotational symmetry is inclined from the normal to the plane of the sheet, diffracted light is emitted about the direction of specular reflection with respect to a plane perpendicular to the axis of rotational symmetry.

Further, the angle of inclination of the interface of each layer of the volume hologram is different between minute portions in the plane, and the incident light on the hologram sheet in which the minute portions having different inclination angles are arranged in the plane is formed into a volume hologram. Since the light is reflected in the direction of the angle corresponding to the inclination angle of each of the interfaces of each layer, diffracted light is emitted at a plurality of angles. By disposing a diffusion plate on the hologram sheet, desired diffusion angle characteristics can be obtained. The diffusion plate used at this time may be a diffusion plate having a relatively small diffusion angle. In the method of diffusing light over a wide range of angles using only the diffusion plate, a large diffusion angle is required, so that the diffusion angle characteristics become slow, and there is a disadvantage that the backward diffusion increases. On the other hand, a diffusion plate having a relatively small diffusion angle has an advantage that the diffusion angle characteristic is steep and the back diffusion is small, so that the reduction in contrast due to the back diffusion is small.

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 1A and 1B, a diffuse reflection plate 1 according to the present embodiment is a hologram sheet 2 on which a hologram recording film 3 and a glass substrate 4 are adhered.
And a light absorption plate 5 attached to the hologram sheet 2 on the glass substrate 4 side, and a microlens sheet 6 disposed on the hologram recording film 3 side.

In the hologram sheet 2, the hologram recording film 3 includes a high refractive index layer 3a having a relatively high refractive index and a low refractive index layer 3b having a low refractive index at a layer interval corresponding to a desired reflection wavelength. Volume holograms that are alternately stacked are formed. In the cross-sectional view of the diffuse reflection plate 1 shown in FIG. 1B, only a few layers of interference fringes are shown in the hologram recording film 3;
An interference fringe structure composed of 00 high refractive index layers 3a and low refractive index layers 3b is formed.

Here, the method for producing the hologram sheet 2 will be described below with reference to FIGS.

As shown in FIG. 2, a hologram recording film 3 (Omnidex manufactured by DuPont, USA) with the cover sheet removed is adhered to one surface of the glass substrate 4 with an adhesive. On the other surface of the glass substrate 4, an antireflection layer 7 is coated to prevent ghost light during interference exposure. The sample 8 thus prepared is mounted on the two-beam interference optical system 100 shown in FIG. 3 and subjected to two-beam interference exposure with a single wavelength of 488 nm Ar laser light for 3 seconds. The laser beam intensity at this time is about 10 mW / cm ² . Further, the object light L1 emitted from the hologram recording film 3 is perpendicularly incident on the sample 8, and the reference light L2 emitted from the glass substrate 4 is 30 °
Incident at an angle of.

In the two-beam interference optical system 100, a laser beam emitted from a laser light source 101 enters a polarizing beam splitter 104 via a mirror 102 and a half-wave plate 103, and travels straight. And a light beam whose traveling direction is bent at a right angle. After passing through the polarizing beam splitter 104, the light flux passes through the lens 105 and the pinhole 106, is reflected by the off-axis parabolic mirror 107, and is applied to the sample 8 as reference light L2 by 30 ° from the glass substrate 4 side. Irradiation at an angle of On the other hand,
The light beam whose traveling direction is bent at a right angle by the polarizing beam splitter 104 is converted into a half-wave plate 108 and a lens 109.
After passing through the pinhole 110 and the off-axis parabolic mirror 11
The hologram recording film 3 then irradiates the sample 8 as object light L1 perpendicularly from the hologram recording film 3 side.

Subsequently, after exposure by the two-beam interference optical system 100, the sample 8 was irradiated with ultraviolet light (5 mW / c) of a mercury lamp.
m ² ) for 2 minutes and UV cure. Finally,
A heat treatment is performed by heating the sample 8 at 100 ° C. for 30 minutes.

By the above processing, the hologram recording film 3 is alternately provided with the high refractive index layer 3a having a relatively high refractive index and the low refractive index layer 3b having a low refractive index at a layer interval corresponding to a desired reflection wavelength. The hologram sheet 2 in which the volume hologram laminated on the hologram is formed is obtained.

The light absorbing plate 5 is made of a resin film colored black, and is adhered to the glass substrate 4 with an adhesive.

The microlens sheet (lens sheet) 6 has fine convex lenses each having a length of about 100 μm
Micro lens array formed at intervals of
It is arranged at the front position on the optical path. Note that the micro lens sheet 6 has a micro cylindrical lens of about 1
Lenticular sheets formed at intervals of 00 μm may be used.

Next, a wavelength of 488 is applied to the diffuse reflection plate 1.
When monochromatic light of nm was incident from an angle of 30 ° and the angular characteristics of the diffuse reflected light were measured, the characteristics shown in FIG. 4A were obtained. Further, white light is incident from an angle of 30 °, and 0 °
When the wavelength characteristics of the reflected light in the directions were measured, FIG.
Were obtained.

As described above, the diffuse reflection plate 1 according to the present embodiment manufactured by the above-described method has a substantially rectangular angle characteristic in which the luminance of the diffuse reflection light is substantially uniform in the range of −20 ° to + 20 °. Met. In addition, the diffuse reflection light is about 4
The wavelength width was about 20 nm in the range from 70 nm to about 500 nm.

As described above, the high-refractive-index layer 3a having a relatively high refractive index and the low-refractive-index layer 3b having a relatively low refractive index are alternately formed on the glass substrate 4 at a layer interval corresponding to a desired reflection wavelength. According to the diffuse reflection plate 1 in which the microlens sheet 6 is disposed on the optical path on the front surface of the hologram recording film 3 on which the volume hologram is formed, the incident light is reflected by the volume hologram. Light can be diffused by a lens sheet or a lenticular sheet disposed on the optical path in front of the volume hologram.

Accordingly, the diffuse reflection light can be limited to a desired angle range, uniform brightness can be obtained in the viewing zone, there is no reflection of illumination light, and good visibility can be obtained when viewed from the normal direction. As can be obtained, even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be located in the normal direction of the diffuse reflector.

Further, the reflection bandwidth of the volume hologram can be controlled by the refractive index of each layer. In addition, the very narrow reflection bandwidth is very advantageous for laser light applications.

[Second Embodiment] The following will describe another embodiment of the present invention with reference to FIGS.

As shown in FIGS. 5 (a) and 5 (b), the diffuse reflection plate 11 according to the present embodiment is configured by adhering a hologram recording film 13 and a glass substrate 14 with an adhesive. .

On the hologram recording film 13, high refractive index layers 13a having a relatively high refractive index and low refractive index layers 13b having a low refractive index are alternately laminated at a layer interval corresponding to a desired reflection wavelength. Volume hologram is formed. In a minute portion in the plane, the shape of the interface of each layer of the volume hologram formed is a paraboloid whose central axis is perpendicular to the diffuse reflector 11, or the central axis is perpendicular to the diffuse reflector 11. It is a paraboloid inclined from the direction, and the minute parts are arranged in the plane. FIG.
In the cross-sectional view of the diffuse reflection plate 11 shown in (b), only several layers of interference fringes are shown in the hologram recording film 13, but actually several tens to several hundreds of high refractive index layers 13a are shown.
And a low-refractive-index layer 13b.

Here, a method of manufacturing the diffuse reflection plate 11 will be described with reference to FIGS. 6 and 7.

As shown in FIG. 6, on one surface of the glass substrate 14, a hologram recording film 13 (Omnidex, manufactured by DuPont, USA) from which the cover sheet has been peeled off is adhered with an adhesive. On the other surface of the glass substrate 14, an antireflection layer 15 is coated to prevent ghost light during interference exposure. Furthermore, the micro lens sheet 1
6 is disposed on the hologram recording film 13 side. The sample 18 prepared in this manner was used as the sample 18 shown in FIG.
It is mounted on the light beam interference optical system 100 ', and is subjected to two light beam interference exposures for 3 seconds with a single wavelength of 488 nm Ar laser light.
The laser beam intensity at this time is about 10 mW / cm ² .
Further, the object light L1 ′ emitted from the hologram recording film 13 is perpendicularly incident on the sample 18, and the reference light L2 ′ emitted from the glass substrate 14 is
Incident perpendicular to.

Note that these exposure conditions are the same as those of the above-described first embodiment except that the sample 18 is mounted instead of the sample 8 and that the reference light L 2 ′ is perpendicularly incident on the sample 18. It is the same as the one.

Subsequently, the two-beam interference optical system 100 '
After exposure, the microlens sheet 16 is removed, and the sample 18 is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Finally, sample 18 was
Heat treatment is performed by heating at 00 ° C. for 30 minutes.

By the above processing, the hologram recording film 13 is alternately provided with the high refractive index layer 13a having a relatively high refractive index and the low refractive index layer 13b having a relatively low refractive index at a layer interval corresponding to a desired reflection wavelength. Thus, the diffuse reflection plate 11 having the volume hologram laminated thereon is obtained. The shape of the interface of each layer of the formed volume hologram in a minute part in the plane is a paraboloid whose central axis is perpendicular to the diffuse reflector 11 or the central axis is the diffuse reflector 1.
1 is a paraboloid inclined from the vertical direction, and the minute portions are arranged in the plane.

The microlens sheet 16 used in the process of manufacturing the diffuse reflection plate 11 is a microlens array in which minute convex lenses are formed at intervals of about 100 μm vertically and horizontally. In addition, the micro lens sheet 1
Reference numeral 6 may be a lenticular sheet in which micro cylindrical lenses are formed at intervals of about 100 μm.

Next, the wavelength 48 is applied to the diffuse reflection plate 11.
When monochromatic light of 8 nm was incident from an angle of 30 ° and the angular characteristics of the diffuse reflected light were measured, the characteristics shown in FIG. 8A were obtained. Further, white light is incident from an angle of 30 °, and 0
When the wavelength characteristics of the reflected light in the ° direction were measured, FIG.
The characteristics shown in (b) were obtained. The measurement conditions are the same as those in the first embodiment.

As described above, the diffuse reflection plate 11 according to the present embodiment manufactured by the above-described method has a substantially rectangular angle characteristic in which the luminance of the diffuse reflection light is substantially uniform in the range of + 10 ° to + 50 °. there were. The diffuse reflection light had a wavelength width of about 20 nm in a range from about 470 nm to about 500 nm.

Further, the diffuse reflection plate 11 'shown in FIG.
Shows the sample 18 prepared as described above, as shown in FIG.
It is mounted on the light beam interference optical system 100 in place of the sample 8 and manufactured by the same process as the method of manufacturing the diffuse reflection plate 11.

The diffuse reflection plate 11 ′ is
Similarly to the above, a hologram recording film 13 'on which a volume hologram formed by alternately laminating a high refractive index layer 13'a and a low refractive index layer 13'b is attached to a glass substrate 14'. Have been. However, the diffuse reflection plate 11 '
The angle of the center axis of the paraboloid formed by the interface of each layer of the volume hologram formed on the hologram recording film 13 ′ is different from that of the diffuse reflection plate 11.

Then, when the angular characteristics and the wavelength characteristics of the diffuse reflection light of the diffuse reflection plate 11 'were measured under the same conditions as the measurement conditions described above, the same results as in the above-described first embodiment were obtained (FIG. 11). (FIGS. 4A and 4B).

Here, if the shape of the interface of each layer in the volume hologram is a paraboloid whose rotational symmetric axis is the normal line of the diffuse reflection plate 11, the direction of reflection of incident light on this volume hologram is parabolic. It is similar to a mirror. That is, when light enters this hologram from the normal direction of the sheet surface, the reflected light spreads within an angle range of twice the maximum tilt angle of the paraboloid,
The luminance within that range becomes constant. If the axis of rotational symmetry is inclined from the normal line of the diffuse reflection plate 11 ', diffracted light is emitted about the direction of specular reflection with respect to a plane perpendicular to the axis of rotational symmetry. Thereby, a desired diffusion angle characteristic can be obtained.

As described above, the glass substrate 14 (14 ')
A high refractive index layer 13a (13'a) having a relatively high refractive index and a low refractive index layer 13b (13'b) having a low refractive index are alternately stacked on top of each other at a layer interval corresponding to a desired reflection wavelength. The volume hologram is formed, and in a minute portion in the plane, the shape of the interface of each layer of the formed volume hologram is a parabolic surface whose central axis is perpendicular to the diffuse reflection plate 11, or According to the diffuse reflector 11 (11 ') whose central axis is inclined from the vertical direction of the diffuse reflector 11 and the minute portions are arranged in the plane, the diffuse reflected light is formed at a desired angle. Can be limited to a range. Therefore,
The illumination direction is different from the normal direction of the diffuse reflector so that uniform brightness is obtained in the viewing zone, there is no reflection of illumination light, and good visibility is obtained when viewed from the normal direction. In this case, the center of the viewing zone can be positioned in the normal direction of the diffuse reflection plate.

Third Embodiment Another embodiment of the present invention will be described below with reference to FIGS. 9 to 11.

As shown in FIGS. 9A and 9B, the diffuse reflection plate 21 according to the present embodiment includes a hologram sheet 22 on which a hologram recording film 23 and a glass substrate 24 are attached, And a diffusion transmission plate 25 disposed on the hologram recording film 23 side of the sheet 22.

In the hologram sheet 22, the hologram recording film 23 includes a high refractive index layer 23a having a relatively high refractive index and a low refractive index layer 23b having a relatively low refractive index at a layer interval corresponding to a desired reflection wavelength. Volume holograms that are alternately stacked are formed. The angle of inclination of the interface of each layer of the formed volume hologram is different between minute portions in the plane, and the minute portions having different inclination angles are arranged in the plane. Although only a few layers of interference fringes are shown in the hologram recording film 23 in the cross-sectional view of the diffuse reflection plate 21 shown in FIG. An interference fringe structure including the layer 23a and the low refractive index layer 23b is formed.

Here, the method of manufacturing the hologram sheet 22 will be described with reference to FIGS. 10 and 3.

As shown in FIG. 10, the glass substrate 24
A hologram recording film 23 (Omnidex, manufactured by DuPont, USA) from which the cover sheet has been peeled off is adhered to one surface of the substrate with an adhesive. On the other surface of the glass substrate 24, an antireflection layer 26 is coated to prevent ghost light during interference exposure. Further, a prism sheet 28 having an apex angle of 110 ° is disposed so as to overlap the hologram recording film 23, and water is filled between the hologram recording film 23 and the prism sheet 28 to adjust the refraction angle. A layer 27 is provided. Sample 2 prepared in this way
9 is transferred to the two-beam interference optical system 100 shown in FIG.
And two-beam interference exposure with Ar laser light of a single wavelength of 488 nm for 3 seconds. The laser beam intensity at this time is about 10 mW / cm ² . The object light L1 emitted from the hologram recording film 23 side is the sample 2
The reference light L2 which is perpendicularly incident on the sample 9 and emitted from the glass substrate 24 side is incident on the sample 18 at an angle of 30 °. These exposure conditions are the same as those in the first embodiment.

Subsequently, after exposure by the two-beam interference optical system 100, the prism sheet 28 is removed, and the water layer 27 is exposed.
And the sample 29 was irradiated with ultraviolet light of a mercury lamp (5 mW /
cm ² ) for 2 minutes to perform UV cure. Finally, a heat treatment is performed by heating the sample 29 at 100 ° C. for 30 minutes.

By the above processing, the hologram recording film 23 is alternately provided with the high refractive index layer 23a having a relatively high refractive index and the low refractive index layer 23b having a relatively low refractive index at a layer interval corresponding to a desired reflection wavelength. The hologram sheet 22 in which the volume hologram laminated on is formed. The angle of inclination of the interface of each layer of the formed volume hologram is different between minute portions in the plane, and the minute portions having different inclination angles are arranged in the plane.

The prism sheet 28 used in the process of manufacturing the hologram sheet 22 has prisms having apical angles of 110 ° formed at intervals of about 100 μm.

The diffusion transmission plate 25 is a transmission type diffusion plate in which aluminum oxide particles are dispersed in a resin and applied on a sheet. The hologram sheet 22 is arranged at a front position on the optical path.

Next, the wavelength 48 is applied to the diffuse reflection plate 21.
When monochromatic light of 8 nm was incident from an angle of 30 ° and the angular characteristics of the diffuse reflected light were measured, the characteristics shown in FIG. 11A were obtained. Also, white light is incident from an angle of 30 °,
When the wavelength characteristic of the reflected light in the 0 ° direction was measured, FIG.
The characteristics shown in (b) were obtained. The measurement conditions are the same as those in the first embodiment.

As described above, the diffuse reflection plate 21 according to the present embodiment manufactured by the above-described method has a substantially rectangular luminance characteristic of the diffuse reflection light, and has a diffuse reflection light of about 470 nm to about 500 nm. In the range of about 20 nm. The angle characteristic of the diffuse reflection light from the diffuse reflection plate 21 is closer to a rectangle than the diffusion plate using a random rough surface.

Here, the angle of inclination of the interface of each layer of the volume hologram is different in a minute portion in the plane, and the incident light on the hologram sheet 22 in which the minute portions having different inclination angles are arranged in the plane is a volume hologram. The light is reflected in the direction of the angle corresponding to the inclination angle of each of the interfaces of the respective layers, so that the diffracted light is emitted at a plurality of angles. By arranging the diffusion transmission plate 25 on the hologram sheet 22, desired diffusion angle characteristics can be obtained.

The diffuse transmission plate 25 used at this time is
A diffusion plate having a relatively small diffusion angle may be used. The method of diffusing light over a wide range of angles using only the diffusion transmission plate requires a large diffusion angle, so that the diffusion angle characteristics become slow and the backward diffusion increases. On the other hand, a diffusion transmission plate having a relatively small diffusion angle has an advantage that the diffusion angle characteristic is steep and that the rear diffusion is small, so that the decrease in contrast due to the rear diffusion is small.

As described above, the high-refractive-index layer 23a having a relatively high refractive index and the low-refractive-index layer 23b having a relatively low refractive index are alternately formed on the glass substrate 24 at a layer interval corresponding to a desired reflection wavelength. The volume holograms laminated on each other are formed, and the tilt angle of the interface of each layer of the formed volume hologram is different in a minute portion in the plane, and the minute portions having different tilt angles are arranged in the plane. According to the diffuse reflection plate 21 in which the diffuse transmission plate 25 is disposed on the optical path on the front surface thereof, the diffuse reflection light can be limited to a desired angle range, uniform brightness can be obtained in the viewing area, and illumination light can be obtained. Even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone is diffused so that there is no reflection and good visibility is obtained when viewed from the normal direction. Can be positioned in the normal direction.

[Fourth Embodiment] The following will describe another embodiment of the present invention with reference to FIGS.

As shown in FIGS. 12A and 12B, the diffuse reflection plate 31 according to the present embodiment is configured by bonding a hologram recording film 33 and a glass substrate 34 with an adhesive. .

On the hologram recording film 33, three types of minute portions (first minute portion 35, second minute portion 36, and third minute portion 37) having different wavelengths for diffuse reflection are arranged in the plane. . Then, for each set of minute portions of various types, the minute portions are arranged in a plane. In the first minute portion 35, a high-refractive-index layer 35a having a relatively high refractive index and a low-refractive-index layer 35b having a relatively low refractive index are alternately arranged at a layer interval corresponding to a desired first wavelength. A stacked volume hologram is formed. Similarly, in the second minute portion 36, a volume hologram in which high refractive index layers 36a and low refractive index layers 36b are alternately laminated at a layer interval corresponding to the second wavelength is formed.
On the third minute portion 37, a volume hologram in which high refractive index layers 37a and low refractive index layers 37b are alternately stacked at a layer interval corresponding to a third wavelength is formed.

Here, the shape of the interface of each layer of the volume hologram formed in the first minute portion 35, the second minute portion 36, and the third minute portion 37 is such that the central axis is
1 may be a paraboloid or a paraboloid whose central axis is inclined from the vertical direction of the diffuse reflection plate 31. In addition, the first minute portion 35 and the second minute portion 3
6. The inclination angle of the interface of each layer of the volume hologram formed in the third minute portion 37 may be different for each minute portion.

The diffuse reflection plate 3 shown in FIG.
In the sectional view of FIG. 1, only a few layers of interference fringes are shown in each minute portion (first minute portion 35, second minute portion 36, and third minute portion 37) of the hologram recording film 33; Tens to hundreds of high refractive index layers 35a, 36
a, 37a and the low refractive index layers 35b, 36b, 37b form an interference fringe structure.

In addition, the first wavelength is set so that the first minute portion 35 reflects red. The second wavelength is set so that the second minute portion 36 reflects green. Further, the third wavelength is set so that the third minute portion 37 reflects blue.

Here, a method of manufacturing the diffuse reflection plate 31 will be described below with reference to FIGS.

As shown in FIG.
A hologram recording film 33 (Omnidex, manufactured by DuPont, USA) with the cover sheet peeled off is adhered to one surface of the substrate with an adhesive. On the other surface of the glass substrate 34, an antireflection layer 38 is coated to prevent ghost light during interference exposure. Further, the microlens sheet 39 is disposed on the hologram recording film 33 side. The sample 40 prepared in this manner was used as the sample 40 shown in FIG.
It is mounted on the light beam interference optical system 100 instead of the sample 8. Here, the light shielding mask 41 is provided on the glass substrate 34 side of the sample 40.
The light-shielding mask 42 is provided on the microlens sheet 39 side. The light-shielding mask 41 is provided with a light-shielding portion 41a and a light-transmitting portion 41b in a slit shape with a width of 2: 1. Similarly, the light-shielding portion 42 is
a and the light transmitting portion 42b are provided in a slit shape.

First, through the light shielding masks 41 and 42 set at the first light shielding position, which is the initial setting position, respectively.
The sample 40 is subjected to two-beam interference exposure with Ar laser light having a single wavelength of 458 nm for 15 seconds.

Thus, the light transmitting portion 41b and the light transmitting portion 4
2b, the first minute portion 35
, A volume hologram in which the high refractive index layers 35a and the low refractive index layers 35b are alternately laminated is formed.

Next, the light-shielding masks 41 and 42 are set at the second light-shielding positions. The second light-shielding position is defined as a light-shielding mask 41 such that a minute portion corresponding to the light-transmitting portions 41a and 42a at the first light-shielding position is completely shielded from light.
42 are light-transmitting portions 41a and 42 from the first light-shielding position, respectively.
This is the position moved by the width of a. A single wavelength NdYA having a wavelength of 532 nm is applied to the sample 40 via the light shielding masks 41 and 42 set at the second light shielding positions.
Two-beam interference exposure is performed for 3 seconds with G laser light.

As a result, the light transmitting portion 41b and the light transmitting portion 4
2b, the second minute portion 36
, A volume hologram in which the high refractive index layers 36a and the low refractive index layers 36b are alternately laminated is formed.

Finally, the above-mentioned light-shielding masks 41 and 42 are respectively set at the third light-shielding positions. The third light-shielding position is a light-transmitting portion 41 at the first light-shielding position and the second light-shielding position.
The positions where the light-shielding masks 41 and 42 are moved from the second light-shielding position by the widths of the light-transmitting portions 41a and 42a, respectively, so that the minute portions corresponding to a and 42a are completely shielded from light. The wavelength 647n is applied to the sample 40 via the light-shielding masks 41 and 42 set at the third light-shielding positions, respectively.
The two-beam interference exposure is performed for 5 seconds with Kr laser light having a single wavelength of m.

As a result, the light transmitting portion 41b and the light transmitting portion 4
2b, the second minute portion 37
, A volume hologram in which the high refractive index layers 37a and the low refractive index layers 37b are alternately laminated is formed.

The laser beam intensity at this time is about 10 m.
W / cm ² . Also, the hologram recording film 33
The object light L1 emitted from the side enters the sample 40 perpendicularly, and the reference light L2 emitted from the glass substrate 34 enters the sample 40 at an angle of 30 °.

Further, by setting the light-shielding masks 41 and 42 so as to be sequentially shifted from the first light-shielding position, the second light-shielding position, and the third light-shielding position, the two surfaces of the sample 40 can be subjected to two-beam interference exposure.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 39 is removed, and the sample 40 is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Finally, sample 40 was
Heat treatment is performed by heating at 0 ° C. for 30 minutes.

By the above processing, three types of minute portions (first minute portion 35, second minute portion 36, and third minute portion 37) having different wavelengths to be diffusely reflected are provided one by one on the hologram recording film 33. For each set of small parts of
The diffuse reflection plate 31 in which the minute portions are arranged in the plane is obtained. In the first minute portion 35, a high-refractive-index layer 35a having a relatively high refractive index and a low-refractive-index layer 35b having a relatively low refractive index alternately at a layer interval corresponding to a desired first wavelength. A stacked volume hologram is formed. Similarly, the second minute portion 36 has a high refractive index layer 36a and a low refractive index layer 36 at a layer interval corresponding to the second wavelength.
and a volume hologram in which b is alternately stacked. On the third minute portion 37, a volume hologram in which high refractive index layers 37a and low refractive index layers 37b are alternately stacked at a layer interval corresponding to a third wavelength is formed.

The micro-lens sheet 39 used in the process for manufacturing the diffuse reflection plate 31 is a micro-lens array in which minute convex lenses are formed at intervals of about 100 μm vertically and horizontally. In addition, the micro lens sheet 3
Reference numeral 9 may be a lenticular sheet in which micro cylindrical lenses are formed at intervals of about 100 μm.

Next, a wavelength 46 is applied to the diffuse reflection plate 31.
When monochromatic lights of 0 nm, 532 nm, and 647 nm were incident from an angle of 30 ° and the wavelength characteristics of the reflected light in the 0 ° direction were measured, the characteristics shown in FIG. 14 were obtained. In addition, FIG.
Each is normalized by the maximum intensity at each wavelength.

As described above, the diffuse reflection plate 31 according to the present embodiment manufactured by the above-described method has a diffuse reflection light in the range of about 440 nm to about 480 nm, about 520 nm to about 540 nm, and about 630 nm to about 650 nm. Wavelength width.

As described above, three types of minute portions in which high refractive index layers and low refractive index layers are alternately stacked on the glass substrate 34 and volume holograms having different wavelengths for diffuse reflection are formed. According to the diffuse reflection plate 31 in which the (first minute portion 35, second minute portion 36, and third minute portion 37) are disposed in the plane, minute portions having holograms recorded at different wavelengths are reflected by the respective reflection portions. Diffusely reflects light of a wavelength. Therefore, a volume hologram in which a plurality of desired reflection wavelengths are selectively hologram-recorded can be formed on one diffuse reflection plate 31. Therefore, the red
Volume holograms that diffusely reflect wavelength bands corresponding to the three colors of green and blue (the first minute portion 35, the second minute portion 36,
By forming the third minute portions 37), it is possible to manufacture a diffuse reflection plate having good brightness and visual characteristics and capable of color display.

[Embodiment 5] Another embodiment of the present invention will be described with reference to FIGS. 15, 6, and 14.
It is as follows.

As shown in FIGS. 15A and 15B, the diffuse reflection plate 51 according to the present embodiment is such that a glass substrate 52 and three hologram recording films 53, 54, 55 are adhered by an adhesive. It is configured to be worn.

The hologram recording film 53 includes a high refractive index layer 53a having a relatively high refractive index and a low refractive index layer 53 having a low refractive index at a layer interval corresponding to a desired first wavelength.
and a volume hologram in which b is alternately stacked. Then, in a minute portion in the plane, the shape of the interface of each layer of the formed volume hologram is a paraboloid whose central axis is perpendicular to the diffuse reflector 51, or whose central axis is perpendicular to the diffuse reflector 51. It is a paraboloid inclined from the direction, and the minute parts are arranged in the plane.

Similarly, the hologram recording film 54
The high refractive index layer 54a at a layer interval corresponding to the second wavelength.
And a low-refractive-index layer 54b are alternately stacked to form a volume hologram. The hologram recording film 55 is formed with a volume hologram in which high-refractive-index layers 55a and low-refractive-index layers 55b are alternately stacked at a layer interval corresponding to the third wavelength.

The diffuse reflection plate 5 shown in FIG.
1, the hologram recording films 53, 54,
Although only a few layers of interference fringes are shown in FIG. 55, actually several tens to several hundreds of high refractive index layers 53a, 54a, 55
a and the low-refractive-index layers 53b, 54b, 55b are formed.

In addition, the first wavelength is set so that the volume hologram formed on the hologram recording film 53 reflects red. Further, the second wavelength is set so that the volume hologram formed on the hologram recording film 54 reflects green. Further, the third wavelength is set so that the volume hologram formed on the hologram recording film 54 reflects blue.

Here, a method of manufacturing the diffuse reflection plate 51 will be described below with reference to FIGS. 6 and 3, which are explanatory diagrams of the second embodiment.

As shown in FIG. 6, the glass substrate 52
A hologram recording film 53 (Omnidex manufactured by DuPont, USA) with the cover sheet peeled off is adhered to one surface of the substrate with an adhesive. On the other surface of the glass substrate 52, an antireflection layer 15 is coated to prevent ghost light during interference exposure. Further, the microlens sheet 16 is disposed on the hologram recording film 53 side. The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG.
Two-beam interference exposure is performed with Kr laser light of a single wavelength of 7 nm for 15 seconds.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Finally, the sample was placed at 100 ° C. for 3 hours.
Heat treatment is performed by heating for 0 minutes. Thus, a volume hologram in which the high-refractive-index layers 53a and the low-refractive-index layers 53b are alternately laminated so as to reflect red is formed on the hologram recording film 53.

Next, the microlens sheet 16 is disposed on the hologram recording film 54 (Omnidex manufactured by DuPont, USA) from which the cover sheet has been peeled off.
The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG.
Two-beam interference exposure is performed with dYAG laser light for 3 seconds.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Then, the sample is placed at 100 ° C. for 3 hours.
Heat treatment is performed by heating for 0 minutes. Thus, a volume hologram in which the high-refractive-index layers 54a and the low-refractive-index layers 54b are alternately laminated so as to reflect green is formed on the hologram recording film 54.

The obtained hologram recording film 54 is
A hologram recording film 53 of a hologram sheet previously produced by two-beam interference exposure with a wavelength of 647 nm is attached with an adhesive.

Further, the microlens sheet 16 is disposed on the hologram recording film 55 (Omnidex manufactured by DuPont, USA) from which the cover sheet has been peeled off.
The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG.
Two-beam interference exposure is performed for 5 seconds with r laser light.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and the sample is irradiated with ultraviolet light (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Then, the sample is placed at 100 ° C. for 3 hours.
Heat treatment is performed by heating for 0 minutes. Thus, a volume hologram in which the high-refractive-index layers 55a and the low-refractive-index layers 55b are alternately laminated so as to reflect blue is formed on the hologram recording film 55.

The obtained hologram recording film 55 is
The hologram recording film 54 of the hologram sheet previously produced by the two-beam interference exposure with the wavelength of 647 nm and 532 nm
Paste on top with adhesive.

With the above processing, the glass substrate 52
A diffuse reflection plate 51 in which three hologram recording films 53, 54, 55 each having a volume hologram having a different reflection wavelength are stacked is obtained.

The microlens sheet 16 used in the process of manufacturing the diffuse reflection plate 11 is a microlens array in which minute convex lenses are formed vertically and horizontally at intervals of about 100 μm. In addition, the micro lens sheet 1
Reference numeral 6 may be a lenticular sheet in which micro cylindrical lenses are formed at intervals of about 100 μm.

The intensity of the laser beam at this time is about 10 m.
W / cm ² . The object light L1 emitted from the microlens sheet 16 side is perpendicularly incident on the sample, and the reference light L2 emitted from the opposite side is 3
It is incident at an angle of 0 °.

Next, when white light was incident on the diffuse reflection plate 51 at an angle of 30 ° and the wavelength characteristic of the reflected light in the 0 ° direction was measured, the characteristic was similar to the characteristic shown in FIG. Obtained.

As described above, the diffuse reflection plate 31 according to the present embodiment manufactured by the above-described method has a diffuse reflection light in the range of about 440 nm to about 480 nm, about 520 nm to about 540 nm, and about 630 nm to about 650 nm. Wavelength width.

As described above, according to the diffuse reflection plate 51 in which the three hologram recording films 53, 54 and 55 having the volume holograms having different reflection wavelengths are laminated on the glass substrate 52, the different wavelengths are used. Are hologram-recorded, and the volume holograms laminated and diffusely reflect light having respective reflection wavelengths. Therefore, it is possible to form a volume hologram in which a plurality of desired reflection wavelengths are selectively hologram-recorded on one diffuse reflection plate. Therefore, by forming a volume hologram that diffuses and reflects wavelengths corresponding to the three colors of red, green, and blue, a color display with good brightness and visual characteristics can be performed.

Further, the diffuse reflector has a structure in which a plurality of volume holograms having different reflection wavelengths are arranged in order from the one having the shorter reflection wavelength when viewed from the light incident direction, so that the intensity of the reflected light is reduced. Can be suppressed.

The reason is that the shorter the wavelength of the hologram recording film material, the higher the absorptance. Therefore, when a plurality of volume holograms having different reflection wavelengths are stacked, it is possible to reduce a decrease in reflected light intensity due to absorption of the volume hologram when the volume hologram having a short reflection wavelength is located on the light incident direction side. it can.

[Embodiment 6] The following will describe another embodiment of the present invention with reference to FIG. 16, FIG. 17, and FIG.

As shown in FIGS. 16A and 16B, the diffuse reflection plate 61 according to the present embodiment has a glass substrate 62 and two hologram recording films 63 and 64 adhered by an adhesive. It is configured.

On the hologram recording film 63, three types of minute portions (first minute portion 65, second minute portion 66, and third minute portion 67) having different wavelengths for diffuse reflection are arranged in the plane. . In the first minute portion 65, a high-refractive-index layer 65a having a relatively high refractive index and a low-refractive-index layer 65b having a relatively low refractive index alternately at a layer interval corresponding to a desired first wavelength. A stacked volume hologram is formed. Here, the shape of the interface of each layer of the volume hologram formed in the first minute portion 65 is a paraboloid whose central axis is perpendicular to the diffuse reflector 61, or whose central axis is perpendicular to the diffuse reflector 61. A paraboloid inclined from the direction may be used. Further, the inclination angle of the interface of each layer of the volume hologram may be different for each minute portion.

Similarly, the second minute portion 66 has the second
The volume hologram in which the high refractive index layers 66a and the low refractive index layers 66b are alternately stacked at a layer interval corresponding to the wavelength of is formed. In the third minute portion 67, a volume hologram in which high refractive index layers 67a and low refractive index layers 67b are alternately stacked at a layer interval corresponding to a third wavelength is formed.

The diffuse reflection plate 6 shown in FIG.
In the cross-sectional view of FIG. 1, only a few layers of interference fringes are shown in each minute portion (first minute portion 65, second minute portion 66, and third minute portion 67) of the hologram recording film 63; Tens to hundreds of high refractive index layers 65a, 66
a, 67a and low-refractive-index layers 65b, 66b, 67b form an interference fringe structure.

Similarly, the hologram recording film 64
Include three types of minute portions (a fourth minute portion 68, a fifth minute portion 69, and a sixth minute portion 7) having different wavelengths for diffuse reflection.
0) is disposed in the plane. In the fourth minute portion 68, a high refractive index layer 68a having a relatively high refractive index and a low refractive index layer 68b having a relatively low refractive index are alternately arranged at a layer interval corresponding to a desired fourth wavelength. A stacked volume hologram is formed. Similarly, the fifth minute portion 69
The high refractive index layer 69a at a layer interval corresponding to the fifth wavelength.
And a low-refractive-index layer 69b are alternately stacked to form a volume hologram. The third minute portion 70 has a high refractive index layer 70a at a layer interval corresponding to the sixth wavelength.
And a low-refractive-index layer 70b are alternately stacked to form a volume hologram.

The hologram recording film 6
3 and the hologram recording film 64 are
An adhesive is applied so that the fourth minute portion 68 overlaps the fifth minute portion 69, the fifth minute portion 69 overlaps the second minute portion 66, and the sixth minute portion 70 overlaps the third minute portion 67. Have been.

In addition, the first wavelength and the fourth wavelength are set so that the first minute portion 65 and the fourth minute portion 68 reflect red. And the fourth wavelength is more than the first wavelength.
Is set somewhat shorter. Also, the second minute portion 66 and the fifth minute portion 69 reflect green,
A second wavelength and a fifth wavelength are set. Then, the fifth wavelength is set to be slightly shorter than the second wavelength.
Further, the third wavelength and the sixth wavelength are set so that the third minute portion 67 and the sixth minute portion 70 reflect blue. The sixth wavelength is set to be slightly shorter than the third wavelength. That is, the volume holograms of the diffuse reflection plate 61 are arranged in ascending order of reflection wavelength as viewed from the light incident direction.

Here, the method of manufacturing the diffuse reflection plate 61 will be described below with reference to FIGS. 13 and 3 which are explanatory views of the fourth embodiment.

[0148] As shown in FIG.
2, a hologram recording film 63 (Omnidex manufactured by DuPont, USA) with the cover sheet peeled off on one surface.
Paste with adhesive. On the other surface of the glass substrate 62, an antireflection layer 38 is coated to prevent ghost light during interference exposure. Further, the microlens sheet 39 is disposed on the hologram recording film 63 side. The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG. Here, as described above, the light-shielding mask 41 is disposed on the glass substrate 62 side of the sample, and the light-shielding mask 42 is disposed on the microlens sheet 39 side. The light-shielding mask 41 is provided with a light-shielding portion 41a and a light-transmitting portion 41b in a slit shape at a ratio of 2: 1. Similarly, the light-shielding mask 42 is also provided with a light-shielding portion 42a and a light-transmitting portion 42b in a slit shape.

A sample having a wavelength of 488 nm is applied to the sample via the light shielding masks 41 and 42 set at the first light shielding position.
Two-beam interference exposure is performed for 3 seconds with Ar laser light having a single wavelength of m. Next, the light-shielding masks 41 and 42 are set at the second light-shielding positions, respectively, and a single wavelength K of 568 nm is used.
Two-beam interference exposure is performed for 15 seconds with r laser light. Finally,
The light-shielding masks 41 and 42 are set at the third light-shielding positions, respectively, and are irradiated with a single wavelength Kr laser beam having a wavelength of 676 nm.
Two-beam interference exposure is performed for 0 second. The laser beam intensity at this time is about 10 mW / cm ² . The object light L1 emitted from the hologram recording film 63 is perpendicularly incident on the sample, and the reference light L2 emitted from the glass substrate 62 is incident on the sample at an angle of 30 °.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 39 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Thereby, the first minute portion 65, the second minute portion 66, and the third minute portion 6 each having the volume hologram formed on the hologram recording film 63.
7 is formed.

Similarly, the microlens sheet 39 is disposed on the hologram recording film 64 (Omnidex manufactured by DuPont, USA) from which the cover sheet has been peeled off.
The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG. Here, as described above, the light shielding mask 42 is provided on the microlens sheet 39 side, and the light shielding mask 41 is provided on the opposite side (FIG. 1).
3).

The light having a wavelength of 458 n is applied to the sample via the light shielding masks 41 and 42 set at the first light shielding position.
Two-beam interference exposure is performed for 15 seconds with an Ar laser beam having a single wavelength of m. Next, the light-shielding masks 41 and 42 are set to the second light-shielding positions, respectively, and two-beam interference exposure is performed with NdYAG laser light having a single wavelength of 532 nm for 3 seconds. Finally, the light-shielding masks 41 and 42 are respectively set at the third light-shielding position, and two-beam interference exposure is performed for 5 seconds with a single wavelength Kr laser beam having a wavelength of 647 nm. The laser beam intensity at this time is about 10 mW / cm ² . The object light L1 emitted from the microlens sheet 39 side is perpendicularly incident on the sample, and the reference light L2 emitted from the opposite side is incident on the sample at an angle of 30 °.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 39 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Thereby, the fourth minute portion 68, the fifth minute portion 69, and the sixth minute portion 7 each having a volume hologram formed on the hologram recording film 64.
0 is formed.

Thereafter, the hologram recording film 64 is adhered with an adhesive to the hologram sheet on which the glass substrate 62 and the hologram recording film 63 previously produced are adhered. At this time, the fourth minute portion 6 is placed on the first minute portion 65.
8 is adhered such that the fifth minute portion 69 overlaps the second minute portion 66 and the sixth minute portion 70 overlaps the third minute portion 67, respectively.

Finally, the attached diffuse reflection plate 61 is
Heat treatment is performed by heating at 0 ° C. for 30 minutes.

By the above processing, a plurality of volume holograms having different reflection wavelengths are arranged on the hologram recording film 63 in order from the one having the shortest reflection wavelength when viewed from the light incident direction.

The micro-lens sheet 39 used in the process for manufacturing the diffuse reflection plate 61 is a micro-lens array in which minute convex lenses are formed at intervals of about 100 μm vertically and horizontally. In addition, the micro lens sheet 3
Reference numeral 9 may be a lenticular sheet in which micro cylindrical lenses are formed at intervals of about 100 μm.

Next, white light was incident on the respective portions of the diffuse reflection plate 61 having different reflection wavelengths from an angle of 30 °, and the wavelength characteristics of the reflected light in the 0 ° direction were measured. 17 (a), (b),
The characteristic shown in (c) was obtained. FIG. 17 is normalized by the maximum intensity at each wavelength.

As described above, the diffuse reflection plate 61 according to the present embodiment manufactured by the above-described method has a diffuse reflection light in the range of about 440 nm to about 500 nm, about 520 nm to about 570 nm, and about 630 nm to about 680 nm. Wavelength width. This is better than the characteristic shown in FIG.
It can be seen that the wavelength width of each of the red, green, and blue colors has almost doubled.

As described above, six types of minute portions in which high refractive index layers and low refractive index layers are alternately stacked on the glass substrate 62 and volume holograms having different wavelengths for diffuse reflection are formed. According to the diffuse reflection plate 61 in which the first minute portion 65, the second minute portion 66, and the third minute portion 67 are arranged in a plane, a volume hologram recorded by recording holograms at different wavelengths and stacked is provided. , And diffusely reflects light of each reflection wavelength. Therefore, it is possible to form a volume hologram in which a plurality of desired reflection wavelengths are selectively holographically recorded on one diffuse reflection plate 61. Further, by setting the reflection wavelength so that the reflection bands are adjacent to each other and stacking the volume holograms, the reflection band width can be increased.

Accordingly, a volume hologram for diffusing and reflecting wavelengths corresponding to the three colors of red, green and blue is formed, and a volume hologram having a reflection wavelength adjacent to each color is also formed to reduce the reflection bandwidth. By expanding, the appropriate reflection bandwidth as the wavelength band of each color is secured,
Color display with good brightness and visual characteristics can be performed.

In addition, by configuring the diffuse reflector to have a configuration in which a plurality of volume holograms having different reflection wavelengths are arranged in ascending order of the reflection wavelength when viewed from the light incident direction, the intensity of the reflected light is reduced. The decrease can be suppressed.

This is because the hologram recording film material has a higher absorptance for light having a shorter wavelength. Therefore, when a plurality of volume holograms having different reflection wavelengths are stacked, it is possible to reduce a decrease in reflected light intensity due to absorption of the volume hologram when the volume hologram having a short reflection wavelength is located on the light incident direction side. it can.

[Embodiment 7] Another embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 18A and 18B, the diffuse reflection plate 71 according to the present embodiment has a hologram recording film 73, a color tuning film 75, and a glass substrate 74 bonded with an adhesive. It is configured to be worn.

As with the hologram recording film 13 of the second embodiment, the hologram recording film 73 includes a high refractive index layer 73a having a relatively high refractive index at a layer interval corresponding to a desired reflection wavelength, and a refractive index A low-refractive-index layer 73b having a low refractive index is alternately stacked to form a volume hologram. However, in the hologram recording film 73, in particular,
The layer interval of the formed volume hologram monotonically expands in the thickness direction of the hologram recording film 73 from the light incident direction side.

The diffuse reflection plate 7 shown in FIG.
1 shows only a few layers of interference fringes in the hologram recording film 73, but in practice,
An interference fringe structure composed of 00 high refractive index layers 73a and low refractive index layers 73b is formed.

Normally, the color tuning film takes a sufficiently long heat treatment time to uniformly diffuse the monomer from the color tuning film into the hologram recording film to expand the hologram recording film, thereby causing interference fringes of the recorded volume hologram. Is used to shift the reproduction wavelength of the volume hologram to the longer wavelength side by increasing the interval of. In the present embodiment, the color tuning film 75 adjusts the concentration gradient of the monomer diffused from the color tuning film 75 in the thickness direction of the hologram recording film 73 by adjusting the temperature and time of the heat treatment at the time of color tuning. By changing the amount of expansion of the hologram recording film 73 in the thickness direction, the reflection bandwidth of the volume hologram is expanded.

Here, the method of manufacturing the diffuse reflection plate 71 will be described with reference to FIGS. 6 and 3.

The microlens sheet 16 is placed on the hologram recording film 73 (Omnidex manufactured by DuPont, USA) from which the cover sheet has been peeled off. The sample prepared in this way is connected to the two-beam interference optical system 10 shown in FIG.
At 0, it is mounted in place of the sample 8, and two-beam interference exposure is performed for 5 seconds with Ar laser light of a single wavelength of 458 nm. The laser beam intensity at this time is about 10 mW / cm ² . The object light L1 emitted from the microlens sheet 16 side is perpendicularly incident on the sample, and the reference light L2 emitted from the opposite side is incident on the sample at an angle of 30 °.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing.

Next, a color tuning film (hologram wavelength adjusting film manufactured by DuPont, USA) 75 is adhered to the glass substrate 74 with an adhesive, and the hologram recording film 73 is further adhered thereon.
Heating is performed at 30 ° C. for 30 minutes. By this heat treatment, the monomer in the color tuning film 75 diffuses into the hologram recording film 73. Lastly, UV curing (5 mW / cm ² ) from a mercury lamp is applied for 2 minutes to perform UV curing.

By the above processing, the hologram recording film 73 is alternately provided with the high refractive index layer 73a having a relatively high refractive index and the low refractive index layer 73b having a low refractive index at a layer interval corresponding to a desired reflection wavelength. Thus, the diffuse reflection plate 11 having the volume hologram laminated thereon is obtained. Then, the layer spacing of the volume hologram formed by the color tuning film 75 is adjusted to the hologram recording film 7.
3 monotonically spreads from the light incident direction side.

The micro-lens sheet 16 used in the process of manufacturing the diffuse reflection plate 71 is a micro-lens array in which minute convex lenses are formed vertically and horizontally at intervals of about 100 μm. In addition, the micro lens sheet 1
Reference numeral 6 may be a lenticular sheet in which micro cylindrical lenses are formed at intervals of about 100 μm.

Next, when white light was incident on the diffuse reflection plate 71 at an angle of 30 ° and the wavelength characteristic of the reflected light in the 0 ° direction was measured, the characteristic shown in FIG. 19 was obtained. In addition,
The measurement conditions are the same as those of the second embodiment.

As described above, in the diffuse reflection plate 11 according to the present embodiment manufactured by the above-described method, the diffuse reflection light has a wavelength width in a range from about 440 nm to about 520 nm. This is because the wavelength width of the diffuse reflection light is wider than the result of the second embodiment.

As described above, on the glass substrate 74, the high-refractive-index layers 73a having a relatively high refractive index and the low-refractive-index layers 73b having a relatively low refractive index are alternately arranged at a layer interval corresponding to a desired reflection wavelength. A stacked volume hologram is formed,
According to the diffuse reflection plate 71 in which the volume interval of the volume hologram monotonically spreads from the light incident direction side in the thickness direction of the hologram recording film 73, the layer interval is set to the diffuse reflection plate 71.
As the wavelength changes monotonically in the thickness direction, the reflection wavelength changes. Thereby, the reflection bandwidth of the volume hologram can be increased. Therefore, by increasing the reflection bandwidth, it is possible to adjust the diffuse reflection plate so as to have an appropriate reflection bandwidth.

In the method of modulating the layer interval in the thickness direction of the hologram recording film 73, the number of manufacturing steps can be greatly reduced as compared with the method of laminating many volume holograms having different layer intervals.

Further, by adopting a configuration in which the layer spacing of the volume hologram is continuously changing in the thickness direction of the diffuse reflection plate, the narrower layer spacing is located on the light incident direction side. In addition, a decrease in the intensity of the reflected light can be suppressed.

This is because the hologram recording film material has a higher absorptance for light having a shorter wavelength. Therefore, when a plurality of volume holograms having different layer intervals are stacked, it is possible to reduce a decrease in reflected light intensity due to absorption of the volume hologram when the surface side having a smaller layer interval is located on the light incident direction side. .

[Embodiment 8] Another embodiment of the present invention will be described below with reference to FIGS. 20, 21, 6, and 14. FIG.

As shown in FIGS. 20A and 20B, a projector screen 81 according to the present embodiment has three hologram recording films 83, 84 and 85 adhered on a base film 82 in this order. Hologram sheet 8
9, a light absorbing layer 86 is coated on a base film 82, and a protective layer 87 and a reflection reducing layer 88 are sequentially coated on a hologram recording film 85.

The base film 82 is made of PET (poly)
ethylene terephthalate) about 300μm thick
Film.

The hologram recording film 83 has a high refractive index layer 83a having a relatively high refractive index and a low refractive index layer 83 having a relatively low refractive index at a layer interval corresponding to a desired first wavelength.
and a volume hologram in which b is alternately stacked. The shape of the interface of each layer of the formed volume hologram in a minute portion in the plane is a paraboloid whose central axis is perpendicular to the projector screen 81, or whose central axis is perpendicular to the projector screen 81. It is a paraboloid inclined from the direction, and the minute parts are arranged in the plane.

Similarly, the hologram recording film 84
A volume hologram in which high refractive index layers 84a having a relatively high refractive index and low refractive index layers 84b having a low refractive index are alternately stacked at a layer interval corresponding to a desired first wavelength. Have been. The hologram recording film 8
5 includes a volume hologram in which high refractive index layers 85a having a relatively high refractive index and low refractive index layers 85b having a low refractive index are alternately stacked at a layer interval corresponding to a desired third wavelength. Is formed.

In the sectional view of the projector screen 81 shown in FIG. 20B, only several layers of interference fringes are shown in the hologram recording films 83, 84 and 85. Several hundred high refractive index layers 83
a, 84a, 85a and low refractive index layers 83b, 84b, 85
b are formed, respectively.

In addition, the first wavelength is set so that a minute portion of the hologram recording film 83 reflects red. The second wavelength is set so that a minute portion of the hologram recording film 84 reflects green. Further, the third wavelength is set so that a minute portion of the hologram recording film 84 reflects blue.

The projector screen 8
The following is a description of the method of manufacturing No. 1 with reference to FIGS. 6 and 3, which are explanatory views of Embodiment 2 described above.

As shown in FIG. 6, on one surface of the base film 82, a hologram recording film 83 (Omnidex, manufactured by DuPont, USA) from which the cover sheet has been peeled off is adhered with an adhesive. On the other surface of the base film 82, an anti-reflection layer 15 is coated to prevent ghost light during interference exposure. Further, the microlens sheet 16 is disposed on the hologram recording film 83 side. The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG. 3 in place of the sample 8, and subjected to two-beam interference exposure with a single-wavelength Kr laser beam having a wavelength of 647 nm for 15 seconds. Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and ultraviolet light (5 mW / cm ² ) from a mercury lamp is applied to the sample.
For 2 minutes to perform UV cure. Finally, the sample is heated at 100 ° C. for 30 minutes to perform a heat treatment.

Next, the microlens sheet 16 is disposed on the hologram recording film 84 (Omnidex manufactured by DuPont, USA) from which the cover sheet has been peeled off.
The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG.
Two-beam interference exposure is performed with dYAG laser light for 3 seconds. Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Then, the sample is heated at 100 ° C. for 30 minutes,
Heat treatment is performed. The obtained hologram recording film 84
Is adhered with an adhesive onto the hologram recording film 83 of the hologram sheet previously produced by two-beam interference exposure with a wavelength of 647 nm.

Further, the microlens sheet 16 is disposed on the hologram recording film 85 (Omnidex manufactured by DuPont, USA) from which the cover sheet has been peeled off.
The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG.
Two-beam interference exposure is performed for 5 seconds with r laser light. Then,
After the exposure by the two-beam interference optical system 100, the microlens sheet 16 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Then, a heat treatment is performed by heating the sample at 100 ° C. for 30 minutes. The obtained hologram recording film 85 is attached with an adhesive onto a hologram recording film 84 of a hologram sheet previously produced by two-beam interference exposure at a wavelength of 647 nm and a wavelength of 532 nm.

The laser beam intensity of the two-beam interference exposure by the two-beam interference optical system 100 is about 10 mW / cm ² . The object light L1 emitted from the microlens sheet 16 side is perpendicularly incident on the sample, and the reference light L2 emitted from the opposite side is incident on the sample at an angle of 30 °.

By the above processing, a hologram sheet 89 in which three hologram recording films 83, 84 and 85 each having a volume hologram having a different reflection wavelength are laminated on the base film 82 is obtained.

The micro-lens sheet 16 used in the process of manufacturing the projector screen 81 is a micro-lens array in which minute convex lenses are formed vertically and horizontally at intervals of about 100 μm. Further, the micro lens sheet 16 is composed of about one minute cylindrical lens.
Lenticular sheets formed at intervals of 00 μm may be used.

The light absorbing layer 86 is a resin layer mixed with a black dye, and the hologram sheet 89 prepared in advance.
Is applied on the base film 82.

The protective layer 87 is a deposited film of silicon dioxide having a thickness of about 0.1 μm, and is formed by being deposited on the hologram recording film 85 of the hologram sheet 89 prepared above.

The reflection reducing layer 88 has a refractive index of about 1.3.
Is applied on the protective layer 87 previously applied.

The projector screen 8
1, white light was incident from an angle of 30 °, and the wavelength characteristic of the reflected light in the 0 ° direction was measured. As a result, the same characteristic as the characteristic shown in FIG. Was.

Next, as shown in FIG. 21, the projector screen 81 manufactured as described above is
Projection light L3 emitted from a D (liquid crystal display) projector 121 is projected from, for example, an angle of 30 °. Then, the projection light L3 is diffusely reflected from the projector screen 81 as diffuse reflection light L4, and the diffuse reflection light L4 is observed by the observer 122.

The conventional projector screen is white under illumination, and the contrast of an image is deteriorated. On the other hand, the projector screen 81 according to the present embodiment is black even under illumination, and has good contrast even when an image is projected under illumination.

As described above, on the base film 82,
By using the projector screen 81 in which three hologram recording films 83, 84, 85 each having a volume hologram having a different reflection wavelength are laminated, the diffuse reflection light L4 can be limited to a desired angle range, and the range within the visual field can be reduced. , Uniform brightness is obtained, there is no reflection of illumination light,
The direction of the projection light L3 is adjusted so that good visibility can be obtained even when viewed from the normal direction.
The center of the viewing area can be positioned in the normal direction of the projector screen 81 even if the angle is different from the normal direction of the projector.

Further, since only the wavelength band of the projection light L3 can be diffusely reflected by using projection light having a narrow wavelength width such as a laser projector, the brightness of the projector screen 81 is not impaired. , The contrast during illumination can be increased.

Therefore, by diffusely reflecting the wavelength bands corresponding to the three colors of red, green and blue, a color display having good brightness and visual characteristics can be performed.

Ninth Embodiment Another embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 22, the liquid crystal display element 91 according to the present embodiment has a diffuse reflection plate 31 ′, a glass substrate 92, a polarizing plate 93, a transparent electrode 94, and an alignment film 95.
, A light absorption layer 96, a protective layer 97, and a liquid crystal layer 98.

The diffuse reflector 31 'is different from the diffuse reflector 31 according to the fourth embodiment by using the color tuning film described in the seventh embodiment to change the layer interval of the volume hologram. In the thickness direction, a process of monotonically expanding from the light incident direction side is performed.

Therefore, the diffuse reflection plate 31 ′ is formed on the hologram recording film 33 ′ on the glass substrate 34 by three types of minute portions (first minute portion 35 ′ and second minute portion 36 ′) having different wavelengths for diffuse reflection. , Third minute portion 37 ')
Are arranged in the plane. Then, the first minute portion 3
5 ', high refractive index layers 35'a having a relatively high refractive index and low refractive index layers 35'b having a low refractive index are alternately laminated at a layer interval corresponding to a desired first wavelength. Volume hologram is formed. Similarly, the second minute portion 3
6 ′, the high-refractive-index layers 3 are arranged at layer intervals corresponding to the second wavelength.
A volume hologram in which 6′a and low refractive index layers 36′b are alternately stacked is formed. A volume hologram in which high-refractive-index layers 37′a and low-refractive-index layers 37′b are alternately stacked at a layer interval corresponding to a third wavelength is formed in the third minute portion 37 ′. I have. Further, the layer spacing of the volume holograms of the three types of minute portions monotonically expands in the thickness direction of the hologram recording film 33 'from the light incident direction side.

In the sectional view of the diffuse reflection plate 31 'shown in FIG. 22, each minute portion (first minute portion 35', second minute portion 36 ', and third minute portion 37' of the hologram recording film 33 'is shown. ), Only several layers of interference fringes are shown, but actually several tens to several hundreds of high refractive index layers 35 ′ are shown.
a, 36'a, 37'a and the low refractive index layers 35'b, 36 '
b, 37'b are formed.

In addition, the first wavelength is set so that the first minute portion 35 'reflects red. Also, the second
The second wavelength is set so that the minute portion 36 'reflects green. Further, the third wavelength is set so that the third minute portion 37 'reflects blue.

[0210] The glass substrate 92 is provided with a diffuse reflection plate 31 '.
To form an electrode substrate facing the electrode substrate on the side.

The polarizing plate 93 uses a dichroic dye.

The transparent electrode 94 is made of ITO (indium tin).
oxide), and an electrode substrate on the side of the diffuse reflection plate 31 ',
It is deposited in a stripe shape orthogonal to the electrode substrate on the glass substrate 92 side.

The alignment film 95 has a thickness of about 50 nm.
A VA (polyvinyl alcohol) film, which is subjected to a rubbing treatment so as to be in a parallel orientation.

The light absorbing layer 96 is a resin layer mixed with a black dye.

The protective layer 97 is a deposited film of silicon dioxide having a thickness of about 0.1 μm, and is formed by being deposited on the hologram recording film 33 ′ which has been manufactured previously.

The liquid crystal layer 98 is of a nematic phase guest-host type.

Here, a method for manufacturing the liquid crystal display element 91 will be described as follows.

First, the diffuse reflection plate 31 'is manufactured by the method described in the fourth embodiment.

As shown in FIG. 13, a microlens sheet 39 was placed on a hologram recording film 33 ′ (Omnidex manufactured by DuPont, USA) from which the cover sheet had been peeled off.
The hologram recording film 33 'is disposed so as to overlap with the hologram recording film 33' side. The sample thus prepared is mounted on the two-beam interference optical system 100 shown in FIG. Here, as described above, the light shielding mask 41 is placed on the glass substrate 34 side of the sample.
The light-shielding mask 42 is provided on the microlens sheet 39 side.

A sample having a wavelength of 458 n is applied to the sample via the light shielding masks 41 and 42 set at the first light shielding position.
Two-beam interference exposure is performed for 5 seconds with Ar laser light having a single wavelength of m. Next, the light-shielding masks 41 and 42 are set at the second light-shielding positions, respectively, and a single wavelength N of 532 nm is set.
Two-beam interference exposure is performed with dYAG laser light for 3 seconds. Finally, the light-shielding masks 41 and 42 are set at the third light-shielding positions, respectively, and two-beam interference exposure is performed for 15 seconds with a single wavelength Kr laser beam having a wavelength of 647 nm. The laser beam intensity at this time is about 10 mW / cm ² . Further, the object light L1 emitted from the hologram recording film 33 'is perpendicularly incident on the sample, and the reference light L2 emitted from the glass substrate 34 is incident on the sample at an angle of 30 °.

Subsequently, after exposure by the two-beam interference optical system 100, the microlens sheet 39 is removed, and the sample is irradiated with ultraviolet rays (5 mW / cm ² ) of a mercury lamp for 2 minutes to perform UV curing. Further, a color tuning film (a hologram wavelength adjusting film manufactured by DuPont, USA) 75 is attached to the glass substrate 34 with an adhesive, and the hologram recording film 33 'is further attached thereon, and then heated at 100 ° C. for 30 minutes. Then, heat treatment is performed.
By this heat treatment, the color tuning film 75
The monomer therein diffuses into the hologram recording film 33 '. Finally, the ultraviolet light of the mercury lamp (5 mW / c
m ² ) for 2 minutes and UV cure.

The absorbing layer 96 is applied on the glass substrate 34 of the thus-produced diffuse reflection plate 31 ', and the protective layer 97 is applied on the hologram recording film 33'. Further, an IT mask is formed on the protective layer 97 by using an evaporation mask.
O is vapor-deposited in a stripe shape to form a transparent electrode 94.

On the other electrode substrate, ITO is vapor-deposited on a glass substrate 94 in a stripe form to form a transparent electrode 94.

Thereafter, an orientation film 95 is applied on the transparent electrodes 94 of both electrode substrates, rubbed so as to be in a parallel orientation, subjected to seal printing, and then dispersed with spacers (not shown). And the liquid crystal is injected. Thereafter, the polarizing plate 9 is placed on the surface of the glass substrate 92.
The simple matrix type liquid crystal display element 91 can be manufactured by attaching 3.

When a color pattern was displayed using the liquid crystal display element 91 manufactured as described above, good brightness and visual characteristics could be confirmed.

As described above, the high-refractive-index layer having a relatively high refractive index and the low-refractive-index layer having a low refractive index alternate with the layer spacing corresponding to the three desired wavelengths of red, green and blue. A hologram recording film 33 'having a minute portion in which a volume hologram laminated on the hologram is formed, and a layer interval of the volume hologram monotonically expands in a thickness direction from a light incident direction side. According to the liquid crystal display element 91 provided with ', the diffuse reflection light can be limited to a desired angle range, uniform brightness can be obtained in the viewing zone, there is no reflection of illumination light, and when viewed from the normal direction. Even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be positioned in the normal direction of the diffuse reflector so that good visibility is obtained. And control the wavelength characteristics of diffusely reflected light It can be.

That is, by diffusing and reflecting the wavelength bands corresponding to the three colors of red, green and blue, it is not necessary to separately add a color filter, and a color display having good brightness and visual characteristics can be performed. Can be.

[0228]

As described above, the diffuse reflection plate according to the first aspect of the present invention has a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index at a layer interval corresponding to the reflection wavelength. And a volume hologram alternately laminated is formed,
In this configuration, a lens sheet or a lenticular sheet is provided on the optical path in front of the volume hologram.

Therefore, the diffuse reflection light can be limited to a desired angle range, uniform brightness can be obtained in the viewing zone, there is no reflection of illumination light, and good visibility can be obtained when viewed from the normal direction. Thus, even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be positioned in the normal direction of the diffuse reflector. Further, there is an effect that the reflection bandwidth of the volume hologram can be controlled by the refractive index of each layer.

As described above, the diffuse reflection plate according to the second aspect of the present invention comprises a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index at a layer interval corresponding to the reflection wavelength. Alternatingly stacked volume holograms are formed, and in a minute portion in the plane of the volume hologram, the shape of the interface of each layer of the formed volume hologram is a paraboloid whose central axis is perpendicular to the diffuse reflection plate. Alternatively, the central axis is a paraboloid inclined from the vertical direction of the diffuse reflection plate, and the minute portion is disposed in the plane.

Therefore, the diffuse reflection light can be limited to a desired angle range. Therefore, the illumination direction is the same as the normal direction of the diffuse reflector so that uniform brightness is obtained in the viewing zone, there is no reflection of illumination light, and good visibility is obtained when viewed from the normal direction. Even at different angles, there is an effect that the center of the viewing zone can be positioned in the normal direction of the diffuse reflection plate.

As described above, the diffuse reflection plate according to the third aspect of the present invention comprises a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index at a layer interval corresponding to the reflection wavelength. Alternatingly stacked volume holograms are formed, and in a minute portion in the plane of the volume hologram, the inclination angle of the interface of each layer of the formed volume hologram differs between the minute portions in the plane,
The minute portion is arranged in a plane, and a diffuse transmission plate is arranged on an optical path in front of the volume hologram.

Therefore, the diffuse reflection light can be limited to a desired angle range, uniform luminance can be obtained in the viewing zone, there is no reflection of illumination light, and good visibility can be obtained when viewed from the normal direction. Thus, even if the illumination direction is at an angle different from the normal direction of the diffuse reflector, the center of the viewing zone can be positioned in the normal direction of the diffuse reflector.

[0234] As described above, in the diffuse reflection plate according to the fourth aspect of the present invention, in addition to the configuration of any one of the first to third aspects, the volume hologram has a plurality of types of minute portions having different reflection wavelengths. In addition, in each of the sets each including a small portion of various types, the minute portions are arranged in a plane.

Therefore, in addition to the effect of any one of the first to third aspects, a volume hologram in which a plurality of desired reflection wavelengths are selectively hologram-recorded on one diffuse reflector is formed. This has the effect that it can be performed. Therefore, by forming a volume hologram that diffusely reflects wavelength bands corresponding to the three colors red, green, and blue,
There is an effect that color display with good brightness and visual characteristics can be performed.

According to a fifth aspect of the present invention, as described above, in addition to any one of the first to fourth aspects, the volume hologram is formed by stacking a plurality of volume holograms having different reflection wavelengths. Configuration.

Therefore, in addition to the effect of any one of the first to fourth aspects, a volume hologram in which a plurality of desired reflection wavelengths are selectively hologram-recorded is formed on one diffuse reflection plate. This has the effect that it can be performed. Further, by setting the reflection wavelength so that the reflection bands are adjacent to each other and stacking the volume holograms, there is an effect that the reflection band width can be increased.

Accordingly, a volume hologram for diffusing and reflecting wavelengths corresponding to the three colors of red, green and blue is formed, and a volume hologram having a reflection wavelength for each color is formed so that the reflection band is adjacent to each other to reduce the reflection bandwidth. By expanding, the appropriate reflection bandwidth as the wavelength band of each color is secured,
There is an effect that color display with good brightness and visual characteristics can be performed.

[0239] As described above, in the diffuse reflection plate according to the sixth aspect of the present invention, in addition to any one of the first to fifth aspects, the volume hologram may have a layer spacing in the thickness direction of the diffusion reflection plate. The configuration is monotonically changing.

Therefore, in addition to the effect of any one of the first to fifth aspects, the reflection bandwidth of the volume hologram can be increased. Therefore, by increasing the reflection bandwidth, there is an effect that the diffuse reflection plate can be adjusted to have an appropriate reflection bandwidth.

As described above, the projector screen according to the seventh aspect of the invention has a configuration in which the diffuse reflection plate according to any one of the first to sixth aspects is provided as a screen.

Therefore, by diffusing and reflecting only the wavelength band corresponding to the wavelength of the projection light, it is possible to provide good brightness and visual characteristics, and to perform display with good contrast even during illumination. It works.

According to an eighth aspect of the present invention, in order to solve the above-mentioned problems, the diffuse reflection plate according to any one of the first to sixth aspects is provided on a light path as a reflection type color filter. Configuration.

Therefore, by diffusely reflecting the wavelength bands corresponding to the three colors of red, green and blue, it is not necessary to separately add a color filter, and a color display having good brightness and visual characteristics is performed. It has the effect of being able to do so.

[Brief description of the drawings]

FIGS. 1A and 1B schematically show the configuration of a diffuse reflection plate according to an embodiment of the present invention, wherein FIG. 1A is a perspective view, and FIG. 1B is AA in FIG. FIG.

FIG. 2 is an explanatory view showing an arrangement of a sample used for hologram recording performed in a process of manufacturing the diffuse reflection plate shown in FIG.

FIG. 3 is an explanatory view schematically showing a configuration of a two-beam interference optical system used for hologram recording performed in a process of manufacturing the diffuse reflection plate shown in FIG.

4A and 4B are diagrams for explaining the optical characteristics of the diffuse reflection plate shown in FIG. 1, wherein FIG. 4A is a graph of angle characteristics, and FIG. 4B is a graph of wavelength characteristics.

FIGS. 5A and 5B schematically show the configuration of a diffuse reflection plate according to another embodiment of the present invention, wherein FIG. 5A is a perspective view, and FIGS. BB in (a)
FIG.

FIG. 6 is an explanatory diagram showing an arrangement of a sample used for hologram recording performed in a process of manufacturing the diffuse reflection plate shown in FIG.

FIG. 7 is an explanatory view schematically showing a configuration of a two-beam interference optical system used for hologram recording performed in the process of manufacturing the diffuse reflection plate shown in FIGS. 5A and 5B.

8A and 8B are diagrams for explaining the optical characteristics of the diffuse reflection plate shown in FIG. 5, wherein FIG. 8A is a graph of angle characteristics, and FIG. 8B is a graph of wavelength characteristics.

FIGS. 9A and 9B schematically show the configuration of a diffuse reflection plate according to another embodiment of the present invention. FIG. 9A is a perspective view, and FIG. FIG. 3 is a sectional view taken along line C of FIG.

FIG. 10 is an explanatory diagram showing an arrangement of a sample used for hologram recording performed in a process of manufacturing the diffuse reflection plate shown in FIG.

11A and 11B are diagrams for explaining the optical characteristics of the diffuse reflection plate shown in FIG. 9; FIG. 11A is a graph of angle characteristics, and FIG. 11B is a graph of wavelength characteristics.

FIG. 12 schematically shows the structure of a diffuse reflection plate according to another embodiment of the present invention, wherein FIG.
FIG. 2B is a cross-sectional view taken along line DD in FIG.

13 is an explanatory diagram showing an arrangement of a sample used for hologram recording performed in a process of manufacturing the diffuse reflection plate shown in FIG.

FIG. 14 is a graph showing wavelength characteristics of the diffuse reflection plate shown in FIG.

FIG. 15 schematically shows a configuration of a diffuse reflection plate according to another embodiment of the present invention. FIG. 15 (a) is a perspective view,
FIG. 2B is a sectional view taken along line EE in FIG.

FIG. 16 schematically shows a configuration of a diffuse reflection plate according to another embodiment of the present invention. FIG. 16 (a) is a perspective view,
FIG. 2B is a sectional view taken along line FF in FIG.

FIG. 17 is a diagram for explaining the optical characteristics of the diffuse reflection plate shown in FIG. 16, and FIGS. 17A to 17C are graphs of wavelength characteristics of reflected light with respect to white light.

FIG. 18 schematically shows the structure of a diffuse reflection plate according to another embodiment of the present invention, wherein FIG.
FIG. 2B is a cross-sectional view taken along line GG in FIG.

FIG. 19 is a graph showing wavelength characteristics of the diffuse reflection plate shown in FIG. 18;

FIGS. 20A and 20B schematically show the configuration of a projector screen according to another embodiment of the present invention, wherein FIG. 20A is a perspective view, and FIG.
FIG. 3 is a sectional view taken along line H.

FIG. 21 is an explanatory view schematically showing an arrangement when the projector screen shown in FIG. 20 is used.

FIG. 22 is a sectional view schematically showing a configuration of a liquid crystal display element according to another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 diffuse reflection plate 3 hologram recording film (volume hologram) 3a high refractive index layer 3b low refractive index layer 6 micro lens sheet (lens sheet, lenticular sheet) 11, 11 'diffuse reflection plate 13, 13' hologram recording film (volume hologram) 13a, 13a 'High refractive index layer 13b, 13b' Low refractive index layer 21 Diffuse reflective plate 23 Hologram recording film (volume hologram) 23a High refractive index layer 23b Low refractive index layer 25 Diffusion transmission plate 31 Diffuse reflection plate 33 Hologram recording Film (Volume hologram) 35 First minute portion (minute portion) 36 Second minute portion (minute portion) 37 Third minute portion (minute portion) 35a, 36a, 37a High refractive index layer 35b, 36b, 37b Low refractive index layer 51 Diffuse reflector 53, 54, 55 Hologram recording film (volume hologram) Ram) 53a, 54a, 55a High refractive index layer 53b, 54b, 55b Low refractive index layer 61 Diffuse reflector 63, 64 Hologram recording film (volume hologram) 65 First minute part (minute part) 66 Second minute part (minute) 67) Third minute portion (minute portion) 68 Fourth minute portion (minute portion) 69 Fifth minute portion (minute portion) 70 Sixth minute portion (minute portion) 65a, 66a, 67a, 68a, 69a, 70a Height Refractive index layer 65b, 66b, 67b, 68b, 69b, 70b Low refractive index layer 71 Diffuse reflector 73 Hologram recording film (volume hologram) 75 Color tuning film 73a High refractive index layer 73b Low refractive index layer 81 Projector screen 83, 84, 85 Hologram recording film (volume hologram) 83a, 84a, 85a High refractive index layer 83b, 84b, 85b Low refractive index layer 91 Liquid crystal display element 31 'Diffuse reflector 33' Hologram recording film (volume hologram) 35 'First minute portion (minute portion) 36' Second minute portion (minute portion) 37 'Third minute portion (small portion) 35'a, 36'a, 37'a High refractive index layer 35'b, 36'b, 37'b Low refractive index layer

Claims (8)

[Claims] 1. A volume hologram in which high refractive index layers having a relatively high refractive index and low refractive index layers having a low refractive index are alternately laminated at a layer interval corresponding to a reflection wavelength, and A diffuse reflection plate, wherein a lens sheet or a lenticular sheet is disposed on an optical path in front of the volume hologram. 2. A volume hologram in which a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index are alternately stacked at a layer interval corresponding to the reflection wavelength, and said volume hologram is formed. In the in-plane minute part, the shape of the interface of each layer of the formed volume hologram is parabolic whose central axis is perpendicular to the diffuse reflector, or the central axis is inclined from the perpendicular direction of the diffuse reflector. Wherein the minute portion is disposed in the plane. 3. A volume hologram in which a high refractive index layer having a relatively high refractive index and a low refractive index layer having a low refractive index are alternately laminated at a layer interval corresponding to the reflection wavelength, and the volume hologram is formed. In the minute part in the plane, the inclination angle of the interface of each layer of the formed volume hologram is different in the minute part in the plane, and the minute part is arranged in the plane, and the front surface of the volume hologram is A diffuse reflection plate, wherein a diffusion transmission plate is provided on an optical path. 4. The volume hologram has a plurality of types of minute portions having different reflection wavelengths, and the minute portions are arranged in a plane for each set of one minute portion of various types. The diffuse reflection plate according to claim 1, wherein: 5. The diffuse reflector according to claim 1, wherein the volume hologram is formed by stacking a plurality of volume holograms having different reflection wavelengths. 6. The diffuse reflector according to claim 1, wherein the layer spacing of the volume hologram monotonously changes in the thickness direction of the diffuse reflector. 7. A projector screen, wherein the diffuse reflection plate according to any one of claims 1 to 6 is provided as a screen. 8. A liquid crystal display device, wherein the diffuse reflection plate according to claim 1 is provided on an optical path as a reflection type color filter.