JP2002040219A - Computer hologram, reflection plate using computer hologram, reflection type liquid crystal display device using computer hologram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the problem that according to a conventional interference method, diffraction efficiency is low, it is difficult to increase the depth of ruggedness and deep ruggedness is hardly obtained in a copying stage even if a prototype of deep ruggedness can be obtained and to eliminate the conventional problem that the rugged surface of a hologram is hardly adhered closely to the rear side surface of a light transmitting type display element and a light reflective layer along the ruggedness of the surface of the hologram is hardly formed while the thickness is kept constant. SOLUTION: Ruggedness (=blaze) having a tooth-shaped sectional plane is formed on the rear side surface of a transparent plate having high refractive index in such a manner that d=λ/2n is satisfied, when the wavelength of standard light, the refractive index of light of the transparent plate and the depth of the ruggedness are defined as λ, n and d, respectively, or d=λ(N-1)/2nN is satisfied, when the sectional plane is formed as a ruggedness having the tooth-shape and steps having the number of steps of N.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer generated hologram having excellent diffraction efficiency, a reflection plate using the computer generated hologram, and a reflection type liquid crystal display device using such a reflection plate.

[0002]

2. Description of the Related Art As a hologram having an uneven surface,
Rainbow holograms are known. The rainbow hologram is obtained by causing object light and reference light to interfere with each other, recording the intensity distribution of the light of the obtained interference fringes on a recording material as light and shade, and then converting the light and shade into unevenness by a bleaching process.
By providing a slit, parallax information is recorded only in the horizontal direction at the expense of vertical parallax.

However, in the above-mentioned rainbow hologram, the intensity distribution of the light of the interference fringes is recorded as unevenness, so that it can be converted to 0-order light, secondary light, and other high-order light other than the primary light. Since the interference fringes are also recorded, even if observed at an angle where the intensity of the diffracted light is strong, 1
The diffraction efficiency of the secondary light is about 30% at the maximum, which is not sufficient.

Although it is expected that the improvement of the diffraction efficiency can be realized by increasing the depth of the unevenness, depending on the above method, the depth of the unevenness is at most about 1/2 of the wavelength of the diffracted light. In addition, it was difficult to reproduce the deep irregularities in the duplication process, even if a prototype having deep irregularities was obtained.

It is also difficult to make the side of the obtained hologram having irregularities adhere to the back surface of the light transmission type display element. Furthermore, when forming a light-reflective layer along the surface irregularities, unevenness in the thickness impairs the performance of the hologram, but the thickness is kept constant, and the light-reflective layer along the surface irregularities is maintained. It was difficult to form.

[0006]

Therefore, in the present invention, in the prior art, the point that the light diffraction efficiency was low, the point that it was difficult to increase the depth of unevenness in order to improve the light diffraction efficiency, Even if a prototype with deep irregularities is obtained,
In the copying process, it was difficult to obtain deep irregularities, it was difficult to make the irregular surface of the hologram adhere to the back surface of the light transmission type display element, and the thickness of the surface of the hologram was kept constant. An object of the present invention is to eliminate the difficulty in forming a light-reflective layer along irregularities.

[0007]

As a result of the study, a transparent plate having a higher refractive index of light than air is used as a material, and on the back surface thereof, a saw-tooth-shaped unevenness (= blaze) is formed, and the wavelength of the reference light is set to λ. When the refractive index of light of the transparent plate is n, the depth d of the unevenness is
Is equivalent to 波長 wavelength, that is, d = λ
It has been found that a computer generated hologram configured to be / 2n can eliminate the disadvantages of the prior art in terms of diffraction efficiency, production and duplication of a prototype, and application, all of which have led to the present invention.

According to a first aspect of the present invention, irregularities having a sawtooth cross section are formed on the back surface of the transparent plate, and the depth d of the irregularities is a reference wavelength of light λ and a material constituting the transparent plate. Where d is λ / 2n, where n is the refractive index of the light. According to a second aspect of the present invention, on the rear surface of the transparent plate, irregularities having a saw-tooth cross section are formed with a number of steps N, and the depth d of the irregularities is a reference light wavelength λ, the transparent The present invention relates to a computer generated hologram characterized in that d = λ (N−1) / 2nN, where n is the refractive index of light of a material constituting the plate. A third invention relates to a computer generated hologram according to the first or second invention, wherein a light-reflective layer is laminated along the irregularities formed on the back surface of the transparent plate. A fourth invention relates to a computer generated hologram according to any one of the first to third inventions, wherein a front surface of the transparent plate is subjected to an antireflection treatment. A fifth invention relates to a reflector using a computer generated hologram, which has the features of any one of claims 1 to 4. A sixth invention is directed to the reflector according to the fifth invention, wherein a transparent adhesive layer is laminated on a front surface of the transparent plate. A seventh invention relates to a reflection type liquid crystal display device, wherein the front surface of the reflection plate according to claim 5 is in close contact with the back surface of the liquid crystal display device. An eighth invention relates to a reflection type liquid crystal display device, wherein the front surface of the reflection plate according to claim 6 is laminated on the back surface of the liquid crystal display device via the transparent adhesive layer. Ninth
In the seventh or eighth invention, the liquid crystal display element and the reflection plate have substantially the same refractive index of light in the transparent plate, or the liquid crystal display element and the transparent adhesive The present invention relates to a reflection type liquid crystal display device, wherein the refractive index of each light of the transparent plate in the layer and the reflection plate is substantially the same. Tenth
The computer hologram according to claim 5, wherein the computer hologram is disposed between the liquid crystal layer of the liquid crystal display device and the rear substrate such that the front surface of the computer hologram is on the liquid crystal layer side. The present invention relates to a reflection type liquid crystal display device. An eleventh invention relates to a reflection type display device, wherein the front surface of the reflection plate according to claim 5 is in close contact with the back surface of a light transmissive display device.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows a hologram layer 22 having computer hologram irregularities 22a on the lower surface of a transparent plate.
The hologram 1 has a concave-convex portion 22a in which a cross section including a portion 22b forming an inclined surface with respect to the transparent plate and a portion 22c perpendicular to the transparent plate has a sawtooth-shaped groove (so-called blaze type). ), Having a depth d when viewed in a direction perpendicular to the transparent plate.

The computer generated hologram 1 has irregularities 22a.
The light-reflective layer 24 is laminated along the lower surface of the light-receiving layer, so that the incident light 3 incident from the air above the drawing is reflected at the interface between the hologram layer 22 and the light-reflective layer 24 (4),
It is emitted into the air again. The optical path length in the hologram 22 of the light that enters and exits in this manner has a maximum depth d of unevenness.
(N is the medium, that is, the refractive index of light of the transparent plate), and the diffraction efficiency is maximized when the difference in optical path length matches the wavelength λ of the incident light. Therefore, λ = 2nd, in other words, d = λ / 2n.

FIG. 1B shows that the cross section of the groove of the sawtooth-shaped irregularities 22a of the computer generated hologram is not a sawtooth formed by a smooth line, but that the oblique side of the sawtooth has a portion 22b parallel to the transparent plate. And a portion 22c perpendicular to the transparent plate is formed in a repetitively formed stepped shape with four steps (so-called binary type). Here, the number of steps (N) is a number obtained by counting the number of all steps having different heights, and the number of steps is N-1. The unevenness 22a formed of the step-shaped groove has the same diffraction effect as the assumed saw-toothed unevenness 22a 'having a depth d' shown by a dashed line in FIG. Regarding 22a ′, when λ = 2nd ′, light interference occurs. In other words, d ′ = λ / 2
n.

However, when the sawtooth-shaped irregularities 22a of the computer generated hologram are grooves formed in steps, the actual depth d is one step smaller than the assumed d ', and the assumed d'.
Where d = d ′ × {(N−1) / N} = (λ / 2n)
× {(N-1) / N}, so that d = λ (N−
1) / 2nN. Therefore, in the case where the saw-tooth-shaped unevenness is formed in a step-like shape with the number N of steps, the same level of unevenness even if it is shallow by 1 / N compared to the unevenness with a smooth cross-sectional shape as shown in FIG. A computer generated hologram having a diffractive effect is obtained.

In each of the blazed and binary computer-generated holograms, the depth d is inversely proportional to the refractive index n of the light of the transparent plate forming the hologram layer 22. Is used, the depth d can be reduced. For example, in the case of a blazed computer hologram formed using an acrylic resin having a light refractive index of 1.4, the reference wavelength is set to 50.
Assuming 0 nm, d = 500 nm / (2 × 1.4) ≒ 1
80 nm. If light is incident from below the same blazed computer hologram, the medium is air (n
= 1), d = 500 nm / 2 = 250 nm, and the depth is slightly less than 40%, which is greater than when light is incident from above, and it is more difficult to manufacture and duplicate the concave and convex prototype. Become.

Various kinds of computer holograms can be applied as the above-mentioned computer hologram. For example, (1) JP-A-11-187
The computer hologram obtained based on No. 316, or (2) the computer generated hologram obtained based on Japanese Patent Application Laid-Open No. H11-296054, or (3) the computer generated hologram of (1) or (2) above, Japanese Patent Application 200
It is a computer generated hologram obtained based on No. 0-159914 and observable in white in a desired observation area. The computer generated hologram of (1), (2), or (3) may form a single hologram on the entire surface, or may be one in which the same minute element holograms are densely arranged on the entire surface. .

A computer generated hologram 1 shown in FIG. 2 is an example of the latter. A composite computer generated hologram or a computer generated hologram in which minute element holograms 2 each being a computer generated hologram are densely arranged in a plane. Is a compound eye.

The computer generated hologram 1 shown in FIG.
Each of the element holograms 2 has a square shape and is arranged in a vertical and horizontal lattice-like array (also referred to as an array-like array).
As shown in FIG. 2B, the element hologram 2 may be a square, or an array in which the second, fourth, etc. rows are shifted by half a pitch in the horizontal direction. Or Figure 2
As shown in (c), the element holograms 2 may be vertically long rectangles and may be densely arranged horizontally.

In any one of the computer generated holograms 1 described with reference to FIG. 1, adjacent element holograms 2 in the computer generated hologram 1 are all the same.
That is, all have an optical path length that gives the same phase to reflected light or transmitted light. As will be described later, such a computer generated hologram 1 is processed by giving conditions necessary for manufacturing the element hologram 2 directly to a material constituting the hologram 1 or to a concave / convex pattern for giving the hologram 1. By repeating the operation while shifting the position, the structure is suitable for reducing the load on the manufacturing apparatus.

Incidentally, the element holograms 2 are not limited to arranging exactly the same kind. FIG.
As shown in (a), two kinds of minute element holograms 2a and 2b having an optical path length that gives different phases to reflected light or transmitted light, for example, every other one of element holograms 2a The other element hologram 2b is repeatedly arranged in the horizontal direction of the row, and the other element hologram 2a
Are arranged so as to fill in the arrangement, and the element hologram 2 in the present invention may be a set (= set) of such different element holograms 2a and 2b. In addition, the element holograms 2a and 2b constituting this set may be arranged in the vertical direction in addition to the horizontal direction as shown in FIG. 3A.

In addition, as shown in FIG. 3B, the element hologram 2 is composed of three types of element holograms 2a, 2b,
And 2c, or FIG. 3 (c)
As shown in (1), the element hologram 2 may be a set of an array in which one element hologram 2a is surrounded by the other element hologram 2b. As described above, the computer generated hologram 1 in which the element hologram 2 is composed of a plurality of element holograms can have characteristics of each of the plurality of element holograms 2a and 2b. FIG.
The computer generated hologram 1 as shown in FIG. 2 is also processed by giving conditions necessary for manufacturing the element hologram 2 as described later, similarly to the computer generated hologram 1 shown in FIG.
The structure is suitable for reducing the load on the manufacturing apparatus by repeatedly performing the process while shifting the position directly on the material forming the hologram 1 or on the concavo-convex mold for giving the hologram 1.

In the above, the shape of the element hologram 2 is not limited to a square or a rectangle, but may be another polygon. To arrange them densely, the triangular element holograms 2 may be arranged next to each other so that they are upside down, or if they are hexagonal element holograms, as shown in FIG. Then, it may be shifted by half a pitch in the horizontal direction. Alternatively, if the element holograms 2 are composed of an octagonal shape and a square having the same side length as one side of the octagon, a dense arrangement can be made by a set of two types of element holograms having different shapes.

Although the size of the computer generated hologram 1 of the present invention is not particularly limited, for example, the size in the vertical and horizontal directions is about 1 cm to several tens of cm. In any case as described above, for example, it is about several tens μm to about 1 mm. As an example, in the case of the computer generated hologram 1 having a size of 5 cm × 5 cm, the element hologram 2 is 250 μm × 25.
If the size is 0 μm, the size of the elementary hologram 2 is 1 / 40,000 of the entire computer generated hologram 1. Note that in the computer generated hologram 1 of the present invention, the element holograms 2 are densely arranged, even if they are not necessarily arranged closely without gaps, if they are substantially arranged close to each other. Suppose they are arranged.

When the computer generated hologram 1 of the present invention or the computer generated hologram 1 is formed of a dense array of element holograms 2, each of the element holograms 2 is obtained based on (1) Japanese Patent Application Laid-Open No. 11-187316. Japanese Patent Application No. 2000-159914, on the premise that the computer generated hologram, or (2) the computer generated hologram obtained based on JP-A-11-296054, or (3) the computer generated hologram of (1) or (2) above This is a computer generated hologram that can be observed in white in a desired observation area obtained based on the hologram.

First, a computer generated hologram obtained based on Japanese Patent Application Laid-Open No. H11-187316 is composed of an aggregate of minute cells arranged two-dimensionally in an array. It has an optical path length that gives a unique phase to the incident light, and diffracts a vertically incident light flux substantially within a predetermined observation area, but does not substantially diffract outside the observation area. It has a phase distribution obtained by adding a first phase distribution and a second phase distribution that vertically emits a light beam that enters obliquely at a predetermined incident angle.

Here, the first phase distribution is a phase distribution of a computer generated hologram that diffracts light only to a predetermined observation area when illuminated with parallel light perpendicular to the hologram surface.
The phase distribution φ _HOLO as illustrated in FIG.
Further, the second phase distribution is a phase distribution of a computer generated hologram that diffracts light incident from behind at an incident angle θ in the front direction, and converts the phase distribution as indicated by a broken line in FIG. A phase distribution φ _GRAT approximated to a step-like function. The sum of these two phase distributions φ _HOLO and φ _GRAT is shown in FIG.
No. 3716 discloses a phase distribution φ of a computer generated hologram, and the computer generated hologram having the phase distribution φ is a computer generated hologram that diffracts light incident obliquely from behind at an incident angle θ to a predetermined front observation area.

In general, a computer generated hologram is obtained as follows. Now, assuming a certain hologram, the playback distance from it is sufficiently large compared to the size of the hologram, and when illuminated with parallel light perpendicular to the hologram surface,
Diffracted light obtained on the reconstructed image plane is represented by the Fourier transform of the amplitude distribution and the phase distribution on the hologram plane (Fraunhofer diffraction).

Therefore, conventionally, in order to give a predetermined diffracted light to the reconstructed image plane, the Fourier transform and the inverse Fourier transform are alternately repeated while adding a constraint condition between the hologram plane and the reconstructed image plane. Is a method of obtaining a computer generated hologram to be placed in Gerchberg-Saxt
Also known as the on-iteration method. Here, assuming that the light distribution on the hologram surface is h (x, y) and the light distribution on the reconstructed image surface is f (u, v), they are expressed by the following equations (1) and (2), respectively. I can write. h (x, y) = A _HOLO (x, y) exp (iφ _HOLO (x, y)) (1) f (u, v) = A _IMG (u, v) exp (iφ _IMG (u, v) (2) In the above, A _HOLO (x, y) is an amplitude distribution on the hologram surface, φ _HOLO (x, y) is a phase distribution on the hologram surface, and A _IMG (u, v) is a reproduced image surface. Amplitude distribution at φ
_IMG (u, v) is the phase distribution on the reproduced image plane. The above Fourier transform and inverse Fourier transform are expressed by the following equation (3):
And (4).

[0027]

(Equation 1)

It is considered that a computer generated hologram that diffracts light only to a predetermined observation area when the hologram surface is illuminated with parallel light perpendicularly from behind using the Gerchberg-Saxton iterative calculation method is considered. Here, in order to make future discussion easier to understand, the amplitude distribution A _{HO LO} (x, y) on the hologram surface is A _HOLO , the phase distribution φ _HOLO (x, y) on the hologram surface is φ _HOLO , and the reproduced image surface Amplitude distribution A at
_IMG (u, v) is A _IMG , and the phase distribution φ _{IM G on the} reproduced image plane
(U, v) is represented by _φIMG .

FIG. 6 is a flowchart for this purpose. In the step, the hologram surface area x ₀ ≦ x in FIG.
When ≦ x ₁ , y ₀ ≦ y ≦ y ₁ , the hologram amplitude A _HOLO is _set to 1 and the hologram phase φ _HOLO is initialized to a random value.
Is subjected to the Fourier transform. In the step, the amplitude A _IMG on the reproduced image plane obtained by the Fourier transform becomes a substantially constant value within a predetermined area, for example, u ₀ ≦ u ≦ u ₁ , v ₀ ≦ v ≦ v ₁ , and outside the predetermined area. When it is determined that the values are almost 0, the amplitude and phase initialized in step become a desired computer generated hologram.

In the step, such a condition is not satisfied.
If it is determined that the
It is. Specifically, within the above-mentioned predetermined area,
Amplitude A_IMGIs set to 1, for example, to 0 otherwise,
Phase φ on raw image plane_IMGIs maintained as is. That's it
After the constraints are given,
The inverse Fourier transform of (4) is performed. The Fourier inverse
The value on the hologram surface obtained by the exchange is bound in steps
Condition is given, amplitude A_HOLOIs set to 1 and the phase φ _HOLOIs
Multivalued (approximate the original function to a digital step-like function (quantity
Child)). Note that the phase φ_HOLOHas a continuous value
In this case, the multi-value conversion is not always necessary.

Then, in a step, the value is subjected to a Fourier transform, and in a step, the amplitude A _IMG on the reproduced image plane obtained by the Fourier transform is set in a predetermined area, for example, u ₀ ≤u≤
u ₁ , almost constant value within v ₀ ≦ v ≦ v ₁ (Const.)
When it is determined that the value becomes substantially 0 outside the predetermined area, the amplitude and phase to which the constraint condition is given in step become a desired computer generated hologram. If it is determined in step that such a condition is not satisfied, the loop of step →→→→ is repeated until the condition of the step is satisfied (until convergence), and a final desired computer generated hologram is obtained. .

Here, in the step, the amplitude A
_As an evaluation function for determining that the _IMG has converged to a substantially predetermined value, for example, the following equation (5) is used. However,
和 (sum) for u and v is u ₀ ≦ u ≦ u ₁ , v ₀ ≦ v
<A _IMG (u,v)> is the ideal amplitude in the cell, which means taking the sum of the values in the cell of the hologram within ≦ v ₁ . This (evaluation function) is, for example, 0.0
It is determined that the convergence has been reached when the value is 1 or less. In addition, as the evaluation function, the following expression (6) using the difference between the value of the previous amplitude of the iteration of the calculation loop and the current value may be used. Here, A _{IMG i-1} is the previous amplitude value, and A _{IMG i} is the current amplitude value.

[0033]

(Equation 2)

From the phase distribution thus obtained, the actual depth distribution of the hologram is obtained. The method of obtaining the depth distribution is different between the case where the hologram is used in the reflection type and the case where the hologram is used in the transmission type. In the case of the reflection type, the expression (7a) is used. 7b), φ (φ (x, y) in the following equation) in FIG. 3C is converted to a depth D of the computer generated hologram (D (x, y) in the following equation). D (x, y) = λφ (x, y) / (4π) (7a) D (x, y) = λφ (x, y) / {2π (n ₁ −n ₀ )} (7b) Here, (x, y) are coordinates indicating a position on the hologram surface, λ is a reference wavelength, n ₁ and n ₀ are refractive indexes of two materials constituting the transmission hologram, Of the two refractive indices, the larger one is n ₁ and the smaller one is n ₀ .

As will be described later, the above equation (7)
a) and (7b), the depth D determined for each microcell (not an elementary hologram) having a vertical and horizontal size of Δ.
By forming a relief pattern of (x, y) on the surface of a hologram-forming resin layer and laminating a predetermined reflective layer, the hologram can be used as a hologram with enhanced effects. This Δ corresponds to, for example, the exposure light feed pitch.

Next, the computer generated hologram obtained based on Japanese Patent Application Laid-Open No. 11-296054 is also composed of an aggregate of minute cells arranged two-dimensionally in an array. It has an optical path length that gives a unique phase to light or incident light, and substantially diffracts a light beam that enters obliquely at a predetermined incident angle into a predetermined observation area, and substantially deviates outside the observation area. The phase distribution is such that it does not diffract, and the light beam that is vertically incident is substantially diffracted into another area where the position of the predetermined observation area is shifted, and substantially outside the other area. It has a phase distribution that does not cause diffraction.

That is, first, when the hologram surface is illuminated with parallel light from behind, the amplitude distribution A on the reconstructed image plane is obtained.
_The region where _IMG (u, v) is almost constant is defined as u ₀ ≦ u ≦
u ₁ , v ₀ ≦ v ≦ v ₁ , but shifted from u ₀ ′ ≦
Designate a computer hologram in the range of u ′ ≦ u ₁ ′, v ₀ ′ ≦ v ′ ≦ v ₁ ′, and design a computer generated hologram that becomes almost 0 outside of the range ((u, v) is the value on the reproduced image plane). Coordinate). That is, FIG.
As shown in (a), when parallel illumination light 3 is vertically incident, u ₀ ′ ≦ u ′ ≦ u ₁ ′, v ₀ ′ ≦
A computer generated hologram 1 that diffracts light only in the range of v ′ ≦ v ₁ ′ is designed.

Phase distribution φ of computer generated hologram 1
_{Assuming that HOLO} (x, y) is a computer _generated hologram, diffraction by the computer generated hologram 1 is expressed by the following expression (8), which is a basic expression of the computer generated hologram. sin θ _d −sin θ _i = mλ / p (8) where m is the diffraction order, p is the pitch of the computer generated hologram, λ is the wavelength, θ _i is the incident angle, and θ _d is the diffraction angle. From design conditions, θ _i = 0 and α ₀ ′ ≦ θ _d ≦ α ₁ ′. Here, α ₀ ′ is the angle of diffraction from the incident position to the position of u ₀ ′ on the reproduction image plane 4, and α ₁ ′ is the angle of diffraction to the position of u ₁ ′.

The computer generated hologram 1 has an incident angle θ
FIG. 5B shows a case where the illumination light 3 obliquely parallel to the light enters. From the basic formula (2) of the computer generated hologram, in this case, θ _i = θ. If the case shown is positive, the range α ₀ ≦ θ _d ≦ α ₁ of the diffraction angle θ _d is α ₀ ′ ≦ will be shifted toward θ smaller than _d ≦ _{α 1} ', as shown in FIG. 5 (b), the diffraction range of the reproducing image plane _{4 u 0 ≦ u d ≦ u} 1 ( however, u ₀ is the incident position From the reconstructed image plane 4 at a diffraction angle α ₀
, And u ₁ is the position of incidence at the diffraction angle α ₁ ), which can be substantially in the front direction of the computer generated hologram 1. The same applies to the v direction.

Accordingly, Japanese Patent Application Laid-Open No. 11-296054 discloses
Computer-generated hologram 1
When parallel light is incident perpendicular to the ram surface,
Observation area (u₀≤u≤u₁, V₀≦ v ≦ v₁) From the position
Another area (u ₀'≤u'≤u₁’, V₀’
≦ v ′ ≦ v₁’) Is a computer hologram that diffracts into
Parallel light obliquely enters the hologram surface from behind.
When a predetermined observation area (u₀≤u≤u₁, V₀
≦ v ≦ v₁2) is a computer generated hologram diffracting to ()).

Also in this case, the obtained phase distribution φ _HOLO (x,
From y), the actual hologram depth distribution is obtained. The depth distribution is obtained by the above equation (7a) in the case of the reflection type and by the above equation (7b) in the case of the transmission type.
Depth D (x,
By forming the relief pattern of y) on the surface of the hologram-forming resin layer and laminating a predetermined reflective layer,
It can be used as a hologram having an enhanced effect as in the case of a computer generated hologram based on Japanese Patent Application Laid-Open No. 11-183716.

The calculation itself of the phase distribution of the computer generated hologram 1 is performed using a known method.
In addition to the above, for example, a method described in JP-A-47-6591 can be used. Further, a method for optimizing the phase distribution may be applied as necessary, and a genetic algorithm, a simulated annealing method (annealing method), or the like can be applied.

Next, a computer generated hologram that can be observed in white in a desired observation area obtained based on Japanese Patent Application No. 2000-159914 is a technique in which incident light of a predetermined reference wavelength incident at a predetermined incident angle is incident at a specific angle. With respect to the zero-order transmitted light or zero-order reflected light that is diffused into the range and is incident at the incident angle, the maximum number of times of the incident light at the incident angle of the shortest wavelength in the wavelength range that can be seen when additive color mixing is performed including the reference wavelength. The bending angle is configured to be larger than the minimum diffraction angle of the incident light having the longest wavelength in the wavelength range. In the following description, only the transmission-type computer hologram will be described so that the description is not redundant, but the same applies to the reflection-type computer hologram.

FIG. 8 conceptually shows how the observation area changes due to the difference in the wavelength of the computer generated hologram 1 when the observation area is set narrow. Reference wavelength λ _{STD of} illumination light
Is between the shortest wavelength λ _MIN and the longest wavelength λ _MAX, and the computer generated hologram 1 is designed for the reference wavelength λ _STD .

As shown in FIG. 8A, the reference wavelength λ_STD
At an oblique angle θ (the angle is the normal to the hologram 1)
The angle from left to right is positive. ) Incident
The illumination light 3 has an angle range β near the front._1STD~ Β_2STD(Subscript 1
Is the minimum diffraction angle, and the suffix 2 is the maximum diffraction angle. The minimum
The diffraction angle is the diffracted light that forms the minimum angle with the 0th order transmitted light.
The maximum diffraction angle is the maximum angle for the 0th order transmitted light.
It is the diffraction angle of the diffracted light that makes a degree. 5) Diffracted light inside_STDWhen
The same oblique incidence when set to spread out
Shortest wavelength λ at angle θ_MINWhen the illumination light 3 of
Hologram 1 is considered as a set of phase computer holograms
Therefore, as shown in FIG._MINIs incident
Observation area (angle range β_1MIN~ Β_2MIN) Is the reference wavelength λ
_STDIs shifted to the lower side (0-order transmitted light side) than in the case of (1). Ma
The longest wavelength λ at the same oblique incidence angle θ _MAXIllumination light 3
When incident, as shown in FIG._MAXBut
Incident observation area (angle range β_1MAX~ Β_2MAX) Is the reference wave
Long λ_STDAbove (the side opposite to the 0th order transmitted light side)
Deviate. Note that the distribution of diffracted light is
Is within the plane containing the normal of hologram 1 and illumination light 3
Yes, including the normal to hologram 1 and perpendicular to its plane
Within, consider the case where diffracted light is distributed on both sides of illumination light 3.
ing.

When the observation area is set narrow,
There is no portion where all of the above diffracted lights 5 _MIN , 5 _STD and 5 _MAX overlap. For this reason, if all wavelengths can be observed at the same time, and if the wavelength range λ _{MIN to} λ _MAX is in the visible light range, there is no white-observable area, and it is observed depending on the observation position (angle). The colors look different.

FIG. 10 conceptually shows how the observation area changes with the wavelength of the computer generated hologram 1 when the observation area is set wide.

Also in this case, when the observation area shown in FIG.
Shortest wavelength λ_MINAnd the longest wavelength λ_MAXField where
(FIG. 10 (b), FIG. 10 (c))
5_MINOr 5_MAX(Angle range β_1MIN~ Β_2MIN,if
H is β_1MAX~ Β_2MAX) Is the reference wavelength λ_STDCase (Fig. 1
0 (a)), which are shifted downward and upward, respectively. I
However, since the observation range is wide, as shown in FIG.
Light 5_MIN, 5_STD, And 5 _MAXNear the front where everything overlaps
Area 6 (angle range β_1MAX~ Β_2MIN)
It is possible to observe all wavelengths simultaneously. Follow
And the wavelength range λ_MIN~ Λ_MAXIs the entire visible light range.
Then, as long as the observer moves in such an area 6,
It can be observed as white.

As is clear from FIG. 11, the condition for the existence of the region 6 in which all the assumed wavelengths can be observed is that the maximum diffraction angle β _2MIN of the shortest wavelength λ _{MIN in} the assumed wavelength range is the longest. That is, it is larger than the minimum diffraction angle β _1MAX of the wavelength λ _MAX . Diffracted light 5 _MIN for 0th order transmitted light,
When 5 _STD and 5 _MAX are distributed on the opposite side to those in FIGS. 8 to 11, the relationship is reversed, so that the shortest wavelength λ formed with respect to the 0th-order transmitted light with respect to the 0th-order transmitted light. _MIN maximum diffraction angle β _2MIN is the longest wavelength λ _MAX minimum diffraction angle β _1MAX
It can be said that it is larger than.

[0050] For observable overlap all wavelengths in white, it is sufficient to lambda _MIN = 450 nm, and λ _{M AX} = 650nm. Therefore, at least the shortest wavelength λ _MIN =
The maximum diffraction angle β _{2MIN of} 450 nm is the longest wavelength λ _MAX = 6
In the computer _generated hologram 1 larger than the minimum diffraction angle β _{1MAX of} 50 nm, as long as the image is observed in the region 6, it can be observed in white without any color change.

[0051] From the above, in some observation area, if you want to observe all of the desired wavelengths, may it can be seen that if determining the observation area λ _1STD ~λ _2STD reference wavelength lambda _STD by the following procedure. (A) The incident angle θ of the illumination light 3 for reproduction is determined. (A) Determine a desired observation angle range 6 that looks white. That is, the minimum diffraction angle γ ₁ (= β _1MAX ) to the maximum diffraction angle γ
₂ (= β _2MIN ) is determined. Here, the minimum diffraction angle γ ₁ and the maximum diffraction angle γ ₂ are the diffraction angles forming the minimum and maximum angles with respect to the zero-order transmitted light, and in the case of the distributions in FIGS. γ ₁ ≦ γ ₂ , and in the case where light is distributed contrary to FIGS. 8 to 11, there is a relationship θ> γ ₁ ≧ γ ₂ . (C) Determine a desired observation wavelength (shortest wavelength λ _MIN to longest wavelength λ _MAX ). (D) The reference wavelength λ _STD is determined within the range of λ _MIN ≦ λ _STD ≦ λ _MAX . (E) Based on the basic formula (8) of the computer generated hologram, using the following formula (9), the minimum diffraction angle γ ₁ and the longest wavelength λ _MAX
, The minimum diffraction angle β _1STD at the reference wavelength λ _STD is _obtained . _{(Sinγ 1 -sinθ) / λ MAX} = (sinβ 1STD -sinθ) / λ STD sinβ 1STD = sinθ + (sinγ 1 -sinθ) × λ STD / λ MAX ··· (9) ( f) Similarly, the computer-generated hologram Based on the basic equation (8), the following equation (10) is used to calculate the maximum diffraction angle β at the reference wavelength λ _STD from the maximum diffraction angle γ ₂ and the shortest wavelength λ _{MIN.
Find 2STD} . (Sinγ ₂ −sin θ) / λ _MIN = (sin _β 2STD _−sin θ) / λ _STD sin β _2STD = sin θ + (sinγ ₂ −sin θ) × λ _STD / λ _MIN (10)

Then, the incident angle θ of the illumination light and the reference wavelength λ
_{In the STD} , the computer generated hologram 1 is disclosed in Japanese Unexamined Patent Application Publication No. 11-183 so that the minimum diffraction angle β _1STD and the maximum diffraction angle β _2STD are obtained.
716 or the wavelengths λ _{MIN to} λ _MAX within the observation angle range of γ _{1 to} γ ₂ with respect to the incident angle θ of the illumination light 3 for reproduction. A diffusion hologram that looks possible and looks white is obtained. Above, desired angle of incidence of the illumination light theta, diffraction range gamma ₁ to? _2, when a given wavelength range lambda _MIN to [lambda] _MAX, is determined how the diffraction angle range β _1STD ~β _2STD used for calculation .

On the other hand, the reference wavelength λ _STD and the incident angle θ of the illumination light
In contrast, when the minimum diffraction angle β _1STD and the maximum diffraction angle β _2STD are given, there is a condition in which light in the wavelength range λ _{MIN to} λ _MAX can be observed at the same time and there is a region that looks white, and the condition for the longest wavelength the minimum diffraction angle β _{1MA X} = γ ₁ of lambda _MAX, minimum wavelength lambda _MIN
Is given by using the maximum diffraction angle β _2MIN = γ _{2 of}

(1) When the diffracted light exists on the positive side with respect to the zero-order transmitted light (FIGS. 8 to 11), γ ₂ ≧ γ ₁ sin γ ₂ ≧ sin γ ₁ Equations (9) and (10) Is used, sin θ + (sin β _2STD −sin θ) × λ _MIN / λ _STD ≧ sin θ + (sin β _1STD −sin θ) × λ _MAX / λ _STD (sin _β 2STD _−sin θ) / λ _MIN ≧ (sin _β 1STD _−sin θ) × λ _MAX because it is _{sinβ 2STD> sinθ, λ MIN /} λ MAX ≧ (sinβ 1STD -sinθ) / (sinβ 2STD -sinθ) ··· (11)

(2) When the diffracted light exists on the negative side with respect to the zero-order transmitted light (opposite of FIGS. 7 to 10), γ ₂ ≦ γ ₁ sin γ ₂ ≦ sin γ ₁ Equation (9) Using equation (10), sin θ + (sin β _2STD −sin θ) × λ _MIN / λ _STD ≦ sin θ + (sin β _1STD −sin θ) × λ _MAX / λ _STD (sin _β 2STD _−sin θ) / λ _MIN ≦ (sin _β 1STD −sin _θ ) ) × λ _MAX sin β _2STD <sin θ, so that λ _MIN / λ _MAX ≧ (sin _β 1STD _−sin θ) / (sin _β 2STD _−sin θ) (11) , Is an equation that holds for any of the negative sides.

[0056] The equation (11), the incident angle of the illumination light theta, a desired observed when the wavelength range was set lambda _MIN to [lambda] _MAX, this equation diffraction angle range β _1STD ~β _2STD at a reference wavelength lambda _STD If setting is made so as to satisfy (11), a range γ in which all desired observation wavelength ranges λ _{MIN to} λ _MAX can be simultaneously observed.
Which means that _{the 1 ~γ 2} is present.

By transforming equation (11), sin θ ≧ λ _MAX sin β _1STD− λ _MIN sin β _2STD ) / (λ _MAX− λ _MIN ) (12) This equation (12) gives the desired observation wavelength range λ _MIN
~ Λ _MAX , diffraction angle range β at a certain reference wavelength λ _STD
When given a _{1STD ~β 2STD,} only in the case of setting the incident angle θ of the illumination light so as to satisfy the equation (12), which can observe all desired observation wavelength range λ _MIN ~λ _{M AX} simultaneously It means that the range γ _{1 to} γ ₂ exists.

In the above, only the plane including the normal line of the computer generated hologram 1 and the illumination light 3 has been considered.
In a plane including the normal line of the computer generated hologram 1 and orthogonal to the plane, it is assumed that diffracted light is distributed on both sides of the illuminating light.
The distribution range at _MIN is a region that can be observed in white, and the range is obtained by converting the observation region at the reference wavelength λ _STD in the same manner as described above.

The above-described technique for enabling the computer generated hologram 1 to be observed in a desired observation area in white color is used alone.
The invention may be applied to a computer generated hologram that diffracts light incident obliquely from behind at an incident angle θ to a predetermined front observation area based on the above-mentioned JP-A-11-187316, or based on JP-A-11-296554. A computer hologram that diffracts light incident obliquely from behind at an incident angle θ to a predetermined observation area in front and diffracts light incident vertically to another area where the position of the predetermined observation area is shifted. May be applied.

In the present invention, as described above, for example, the depth D (x, y) is obtained for each microcell having a vertical and horizontal size of Δ by the equations (7a) and (7b). A specific computer generated hologram 1 is obtained based on the calculation result, or such a computer generated hologram 1 is obtained.
Is copied for the required number of times. Specifically, in the case of the reflection type, according to the equation (7a), the blaze type follows the following equation: D (x, y) = λφ (x, y) / 4πn. D (x, y) = λφ (x, y) (N−1) / 4πnN. n is the refractive index of light constituting the transparent plate, and N is the number of steps in the case of a sawtooth shape.

FIGS. 12A to 12D are views showing an example of a method for forming a concave / convex pattern on a substrate, which is preferable for duplicating the computer generated hologram 1, and for producing a photomask for producing a semiconductor circuit. The process can be used, and a photomask blank and a laser writing device, which is a writing device, or an electron beam writing device can be used.

In the case of using these drawing devices, if the computer generated hologram 1 is the one in which the same ones of the element holograms 2 are arranged, the data of the element hologram 2 and the pitch such as the vertical and horizontal directions required for the arrangement are provided to the drawing device. , The load on the data processing of the drawing apparatus can be greatly reduced, and the load of the operation for obtaining the data of the element hologram 2 can be significantly reduced as compared with the operation for the entire computer hologram 1. As exemplified earlier,
The computer generated hologram 1 has a size of 5 cm × 5 cm,
This is because, when the size of the element hologram 2 is 250 μm × 250 μm, the data related to the element hologram 2 is 1 / 40,000 in terms of area ratio compared to the data of the entire computer hologram 1.

First, 15 cm × 15 cm, thickness 6.4 m
m low-reflection chromium thin film 1 on a substrate 11 of synthetic quartz
On the chromium thin film 12 of the photomask blank plate 10 on which the layer 2 is laminated, a resist (positive type in the illustrated example) 13 having dry etching resistance is formed into a thin film having a thickness of, for example, about 400 nm. As a material of the resist for dry etching, for example, ZEON Corporation, ZE
P7000 or the like can be used, and the lamination of the resist layer 13 is performed by spin coating using a spinner or the like.

The resist layer 13 is subjected to pattern exposure. The pattern exposure is performed by using a laser writing apparatus or an electron beam writing apparatus in addition to using the pattern 14 as shown in FIG.
Alternatively, it can be performed by scanning with an electron beam. For example, an electron beam lithography system "M" manufactured by ETEC
EBES4500 "is used.

Since the solubilized portion 13b and the unexposed portion 13a in which the resist resin is hardened by the exposure are partitioned, the solubilized portion 13b is removed by solvent development by spray development performed by spraying a developing solution. Then, a resist pattern 13a is formed. In addition, as a resist,
A negative type can be used, and development can also be performed by immersion in a developer. In the subsequent steps, in addition to the dry etching, wet etching by immersion can be performed, so that the resist used is not limited to a resist having dry etching resistance.

Using the formed resist pattern 13a, the portion of the chromium thin film 12 that is not covered with the resist is etched and removed by dry etching.
In the removed portion, the lower quartz substrate 11 is exposed. Next, the exposed quartz substrate 11 is similarly subjected to dry etching to etch the quartz substrate 11, and the concave portion 15 generated by the progress of the etching, the chromium thin film 12, and the resist thin film 13 a are sequentially covered from the bottom. And a convex portion formed of the original portion of the quartz substrate. Thereafter, the resist thin film is removed by dissolving or the like, and a quartz substrate having a concave portion 15 formed by etching the quartz substrate and a convex portion 16 formed on the top with a laminated portion of the chromium thin film 12 is obtained.

With only the above method, only the so-called binary (the number of steps: 2, another level of another surface is generated in addition to the surface of the original quartz substrate) of the convex portion and the concave portion can be obtained. However, the photo-etching process consisting of resist formation, pattern exposure, resist development, dry etching of a chromium thin film, dry etching of a quartz substrate, and resist removal was repeated on the obtained one. Recesses caused by the second photoetching,
Photo-etching can be applied to the projections and the projections. By controlling the etching depth, in addition to the surface of the original quartz substrate, three more levels of surface are generated, and the surface of the original quartz substrate In addition, the number of stages is four if counted. At this time, as a resist, for example, a novolak resin-based i-line resist having dry etching resistance is used, a thin film of about 465 nm is used, and exposure is performed using, for example, an ALTA3500 as a drawing apparatus.

FIG. 13 is a diagram showing the number of repetitions of the above-mentioned photoetching step and the number of steps that occur.
Indicates that two steps are generated in one process. FIG.
By repeating and applying the above steps to each of the upper and lower stages in (a), as shown in FIG. 13 (b), a maximum of four stages occur, and the process is further repeated for a total of three times By repeating the above steps, as shown in FIG. 13C, the maximum number of stages is eight.

Therefore, the number of photoetching times N_PE(Attach
The letter PE indicates photoetching and N_PEIs a natural number
You. ) For a maximum of 2 N_PESince the number of stages of the power occurs,
Accuracy of concave and convex type, performance of computer generated hologram 1
According to N of 2_PE, That is, 2, 4, 8, 16, ...
And the number of photoetching N_PERelationship with
In consideration of the above, the specifications of the manufacturing process should be determined. N of 2_PESquared
Number of photo-etching even if it is increased by 1 from the number of steps
Is preferably increased once, so that the N of 2 _PESquared
The number of stages or a smaller number of stages is preferred. This
After obtaining a predetermined number of steps,
Removed by spot etching, leaving the surface of the quartz substrate 11
Computer generated hologram 1 with irregularities with a fixed number of steps
To obtain a concave-convex pattern.

In the computer generated hologram 1 of the present invention, although it is sufficient to perform the operation again to reproduce the data of the phase distribution, it takes time and effort to perform the operation.
There may be accidents such as sudden contamination or damage. Therefore, in the production using this type of concave and convex mold, one or a very small number of duplicate molds are made from the mold obtained first, and the necessary number of molds for production are produced from this duplicate mold, and the production is performed. (= Duplication). In order to increase the durability of the concave / convex mold, it is preferable to use a metal plating mold obtained by plating and peeling the mold surface of the concave / convex mold.
In addition, the production of the concavo-convex mold can also be performed by mechanically engraving an appropriate substrate with a diamond needle or the like.

As a replication method for replicating the computer generated hologram 1 using a concave / convex mold (preferably the above-mentioned production mold), a concave / convex mold 20 as shown in FIG. A pressing method, an injection molding method, or a casting method can be used. As a resin used in these methods, any of a thermoplastic resin and a thermosetting resin can be used.

A more efficient and industrially preferable duplication method is as follows. First, the mold surface of the concavo-convex mold 20 (FIG. 1)
4 (a), an uncured resin composition containing an ultraviolet curable resin is brought into contact with the uncured resin composition by coating or the like, and a plastic film 23 serving as a base material is placed between the uncured resin composition and the uncured resin composition. The plastic film 23 is laminated through a layer 22a of the uncured resin composition having a required thickness by applying pressure with a roll or the like from above to prevent bubbles from entering. This uncured resin composition layer 22a is
In a state sandwiched between the mold surface of No. 0 and the plastic film 23, the uncured resin composition of the layer 22a is cured by irradiating ultraviolet rays, etc. A hologram layer 22 composed of
A laminate 21 made of a plastic film 23 is produced, and then the laminate 21 is peeled off from the concave / convex mold 20 (FIG. 1).
4 (b)). After the resin composition is cured, the plastic film 23 may be peeled off for convenience (FIG. 14).
(C)). In addition, in this specification, when it says "transparent plate",
Not only the hologram layer 22 alone, but also the hologram layer 2
2 and a plastic film 23.

The ultraviolet curable resin in the above is
As an example, unsaturated polyester, melamine, epoxy, polyester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, polyether (meth) acrylate, polyol (meth)
A thermosetting resin such as acrylate, melamine (meth) acrylate, or triazine acrylate, or a UV-curable resin obtained by adding a radical polymerizable unsaturated monomer, an initiator, or the like thereto can be used. . Note that, instead of curing with ultraviolet rays, curing can also be performed using an electron beam.

In the above, the plastic film 23 serving as the base material is preferably one having high transparency and smoothness, and has a thickness of 1 μm to 1 mm, preferably 10 μm to 1 mm.
μm to 100 μm polyethylene terephthalate film, polyethylene film, polypropylene film,
Transparent synthetic resin films such as a polyvinyl chloride film, an acrylic film, a triacetyl cellulose film, and a cellulose acetate butyrate film can be used.

The copied laminate 21 having the hologram irregularities (FIG. 14B) or the hologram layer 22 without the plastic film 23 (FIG. 14B)
(C)) shows the surface of the hologram having no unevenness (FIG. 14).
(B) and (c) are used as the observation side. These can be used as they are, but in order to further improve the light reflection function, it is more preferable to use the light reflection layer 24 laminated on the uneven surface of the hologram layer 22 (FIG. 14D). .

The light-reflective layer 24 may be a metal-reflective layer such as a light-impermeable metal thin film (transparent if the film thickness is extremely small) or a light-transmissive hologram layer. Can use two types of so-called transparent reflective layers having different refractive indexes of light.

The metal reflection layer is made of Cr, Fe, Co, Ni,
Cu, Ag, Au, Ge, Al, Mg, Sb, Pb, C
It is a thin film formed of a metal such as d, Bi, Sn, Se, In, Ga, or Rb, an oxide thereof, or a nitride thereof, alone or in combination. Of these, Al, Cr, Ni, Ag, or Au
And the like are particularly preferred. In order to form a metal reflective layer on the uneven surface of the hologram layer using these thin films, a thin film forming method such as a vacuum evaporation method, a sputtering method, and an ion plating method is used. When the thickness of the metal reflective layer is 200 ° or less, the light transmittance is relatively small, so that the metal reflective layer can be used as the light reflective layer 24 while being transparent.

As the light reflecting layer, a transparent reflecting layer made of a thin film of a substance which is light transmitting and has a different refractive index of light from the hologram layer 22 can be used. The thickness of the transparent reflective layer may be any thickness as long as it is a transparent region of the material forming the thin film, but is usually preferably 100 to 1000 °. In order to form the transparent reflection layer on the uneven surface of the hologram layer, a thin film formation method such as a vacuum evaporation method, a sputtering method, and an ion plating method is used as in the case of the metal reflection layer. The transparent reflective layer may have a refractive index higher or lower than the refractive index of the hologram layer 22, but the difference between the refractive index of the transparent reflective layer and the hologram layer is preferably 0.3 or more,
This difference is more preferably 0.5 or more, and more preferably 1.0 or more.

The transparent reflective layer having a higher refractive index than the hologram layer 22 includes ZnS, TiO ₂ , Al ₂ O ₃ , Sb ₂
Examples include S ₃ , SiO, TiO, and SiO ₂ .
Examples of the transparent reflection layer having a lower refractive index than the hologram layer 22 include LiF, MgF ₂ , and AlF ₃ . Further, a transparent synthetic resin having a different refractive index from that of the hologram layer 22, for example, a layer of polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl acetate, polyethylene, polypropylene, or polymethyl methacrylate may also be used as the light reflective layer. These resins may be dissolved in a solvent and applied to the uneven surface of the hologram layer 22 by coating or the like to be laminated.

When the light reflecting layer 24 is made of a metal reflecting layer, the metal reflecting layer (which itself is light-impermeable) has an infinite number of fine holes formed by an appropriate method such as laser drawing. By doing so, it is possible to secure light transmittance while having light reflectivity. Therefore, such a material may be used as the light reflective layer 24.

In the present invention, when the light reflecting layer 24 is laminated on the side of the hologram layer 22 having irregularities, it is sufficient if refraction of light occurs at the interface between the hologram layer 22 and the light reflecting layer. As the reflective layer 24, along the unevenness,
It is sufficient that there is no partial unlaminated portion such as a pinhole. Even if there is unevenness in the thickness of the light-reflective layer 24, it is sufficient that the light-reflective layer 24 has a required minimum thickness. There is an advantage that the burden of management is reduced.

The computer generated hologram 1 of the present invention is composed of a hologram laminate 21 (FIG. 14 (b)) and a hologram layer 22 depending on whether or not a plastic film 23 and / or a light reflective layer 24 is provided. (FIG. 14C), a light-reflective layer 24 laminated on the lower surface of the hologram laminate 21 (FIG. 14D),
Alternatively, the light reflective layer 24 is provided on the lower surface of the hologram layer 22 alone.
14 (e) can be used, but in any case, it is highly effective when applied to a display element, especially a liquid crystal display device, with the hologram layer 22 having no unevenness as the observation side. .

FIG. 15A shows an example in which the computer generated hologram 1 is applied to the non-observation side of the liquid crystal display element 30 which is a main part of the liquid crystal display device. , A glass substrate 32, a transparent electrode 33, a liquid crystal 34, a transparent electrode 33 ′, a glass substrate 32 ′, and a polarizing plate 31 ′ are laminated in this order, and the computer generated hologram 1 is arranged on the back surface. FIG. 15 (a)
In the above, a hologram layered body composed of the hologram layer 22 and the light-reflective layer 24 is represented, but another type described above may be arranged. Fig. 1
As in FIG. 5A, the computer generated hologram 1 may be closely attached to the liquid crystal display element 30 in parallel with the liquid crystal display element 30 but not at a distance. The computer hologram 1 and the liquid crystal display element 30 may be laminated with an adhesive layer interposed between the upper surface of the computer hologram 1 and the polarizing plate 31 '. It is preferable to prepare and use an adhesive layer laminated on the side having no irregularities). It is preferable to use a highly transparent adhesive layer.

When the computer generated hologram 1 of the present invention is applied to a liquid crystal display device, the liquid crystal 34 in the liquid crystal display element is used.
And a rear substrate below the liquid crystal 34. As shown in FIG. 15B, the light reflective layer 24, the hologram layer 22, and the adhesive layer 25 are formed on the lower surface of the liquid crystal 34. Can be prepared in advance and arranged. Of course, as the computer generated hologram 1 to be arranged, FIGS. 14B to 14E
And those having an adhesive layer laminated on the lower surface thereof. Since the computer generated hologram 1 of the present invention has a smooth upper surface, when it is brought into close contact with the back surface of the display element or the like, it can be completely adhered without tilting or partly floating. Can occur.

When the computer generated hologram 1 of the present invention is applied to a display device such as a liquid crystal display device, light of the display device and the computer generated hologram (excluding the light reflective layer when a light reflective layer is involved) is used. It is preferable that the refractive indices be substantially the same. When the computer hologram and the liquid crystal display element are laminated via the adhesive layer, the display element, the computer hologram (excluding the light reflective layer when a light reflective layer is involved), and the light of the adhesive layer. Are preferably made to have substantially the same refractive index. In the description of applying the computer generated hologram 1 to a display device such as a liquid crystal display device, the adhesive layer includes a pressure-sensitive adhesive layer.

Since the computer generated hologram 1 of the present invention is used so that the hologram layer 22 or the plastic film 23 is on the observation side, the outermost surface, ie, the surface of the hologram layer 24 or the plastic film 23, is further subjected to light reflection. It is preferable to form a prevention layer.

[0087] Representative anti-reflection layer is the outermost surface of the computer generated hologram 1, indium tin oxide which also serves as a antistatic (in an In ₂ 0 ₃ doped with tin, known as ITO)
A transparent conductive thin film having a lower refractive index than that of the transparent conductive thin film for preventing reflection, for example, a thin film of SiO ₂ is formed on the transparent conductive thin film. May have a hard coat layer made of a polymethyl methacrylate resin or the like interposed between the outermost surface and the above-mentioned outermost surface to prevent damage. Alternatively, it is more preferable to use a plastic film having a dielectric multilayer film (for example, trade name; manufactured by Meles Griot Company, USA; using HEBBAR coating).

[0088]

According to the first aspect of the present invention, unlike a rainbow hologram, there is no influence of interference fringes derived from high-order light other than the primary light, and the light diffraction efficiency can be increased. The back side allows light to reciprocate in the transparent plate, which has a higher refractive index than air, so the depth of the unevenness is smaller than when the front side of the transparent plate is used. On the back side of the transparent plate,
It is possible to provide a computer generated hologram having a sawtooth-shaped unevenness in cross section without having to consider generation of thickness unevenness or the like in forming the light reflective layer. According to the second aspect of the invention, it is possible to provide a computer hologram having substantially the same effect as that of the first aspect and having a saw-tooth unevenness having a stepped cross section. According to the third aspect of the invention, in addition to the effects of the first or second aspect of the present invention, the light reflection layer is further laminated on the back surface of the transparent plate along the irregularities, so that the light reflection property is more excellent. Computer hologram can be provided. According to the invention of claim 4, claims 1 to
In addition to the effect of any one of the third inventions, since the front surface of the transparent plate is subjected to the anti-reflection treatment, so-called external light in the surroundings and light incident to cause light reflection are unnecessary on the front surface of the transparent plate. It is possible to provide a computer generated hologram in which the reflection of light causes a glare or a part of necessary incident light is prevented from being lost due to unnecessary reflection.
According to the fifth aspect of the present invention, it is possible to provide a reflection plate capable of exhibiting the effects of any one of the first to fourth aspects of the invention. According to the invention of claim 6, in addition to the effect of the invention of claim 5, reflection by a transparent adhesive layer laminated on the front surface of the transparent plate can be easily applied to the back surface of a display device such as a liquid crystal display device. Boards can be provided. According to the seventh aspect of the invention, since the reflection plate exhibiting the effect of the fifth aspect of the invention is applied to the liquid crystal display device, a reflection type liquid crystal display device having high light reflection efficiency and high image contrast is provided. Can be provided. According to the eighth aspect of the present invention, the reflection plate exhibiting the effect of the sixth aspect of the invention is laminated on the back surface of the liquid crystal display device via the transparent adhesive layer, so that the light reflection efficiency and the image quality can be improved. It is possible to provide a reflection type liquid crystal display device having high contrast, which is reliably and easily stacked with a reflection plate and a liquid crystal display device. According to the ninth aspect of the present invention, in addition to the effects of the seventh or eighth aspect, the reflection type liquid crystal display device in which unnecessary diffraction is prevented is provided because the refractive index of light in each portion to be used is substantially the same. it can. Claim 10
According to the invention, a reflection type liquid crystal display device having high light reflection efficiency and high image contrast is provided by arranging the reflection plate exhibiting the effect of the invention of claim 5 inside the liquid crystal display device. can do. According to the eleventh aspect of the present invention, since the reflection plate exhibiting the effect of the fifth aspect of the invention is applied to a light transmissive display device, the reflection type display has high light reflection efficiency and high image contrast. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a computer generated hologram of the present invention.

FIG. 2 is a diagram showing a computer generated hologram composed of an array of element holograms.

FIG. 3 is a diagram showing an element hologram composed of a combination of holograms.

FIG. 4 is a diagram illustrating an example of a phase distribution of a computer generated hologram.

FIG. 5 is a diagram illustrating a state where an observation position is shifted.

FIG. 6 is a flowchart showing computation steps of a computer generated hologram.

FIG. 7 is a diagram illustrating a range of outgoing light with respect to incident light.

FIG. 8 is a diagram for individually explaining diffraction at each wavelength when an observation range is narrow.

FIG. 9 is a diagram illustrating diffraction at each wavelength when the observation range is narrow.

FIG. 10 is a diagram for individually explaining diffraction at each wavelength when the observation range is wide.

FIG. 11 is a diagram illustrating diffraction at each wavelength when the observation range is wide.

FIG. 12 is a diagram illustrating a method of manufacturing a hologram.

FIG. 13 is a diagram illustrating the number of photo-etching steps and the number of uneven steps.

FIG. 14 is a diagram showing a concavo-convex pattern and a copied hologram.

FIG. 15 is a diagram showing a state applied to a liquid crystal display element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Computer hologram 2 element hologram 3 Incident light 5 Outgoing light 6 Observation range 11 Substrate 12 Mask 13 Resist 20 Concavo-convex type 22 Hologram layer 23 Plastic film 24 Light reflective layer 30 Liquid crystal display element 31 Polarizer 32 Glass substrate 33 Transparent electrode 34 Liquid crystal

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G02F 1/1335 520 G02F 1/1335 520 G03H 1/18 G03H 1/18 (72) Inventor Tomotsugu Hamano Shinjuku-ku, Tokyo 1-1-1 Ichigaya Kagacho F-term in Dai Nippon Printing Co., Ltd. (Reference) 2H042 BA09 BA12 BA14 BA20 BA21 DA21 DD01 DE04 2H049 AA25 AA33 AA37 AA40 AA43 AA48 AA63 AA65 CA01 CA05 CA08 CA15 CA22 CA28 2H091 FA14Y FA14 FA19 FD15 GA17 KA01 LA12 LA16 2K008 AA10 FF27 HH19 HH23

Claims (11)

[Claims] 1. A surface of a transparent plate is provided with irregularities having a saw-tooth shape in cross section. The depth d of the irregularities is determined by a wavelength λ of a reference light, a refraction of light of a material constituting the transparent plate. A computer generated hologram, wherein d is λ / 2n, where n is a ratio. 2. On the back surface of the transparent plate, irregularities having a saw-tooth cross section are formed with steps of the number N. The depth d of the irregularities is a wavelength λ of light serving as a reference, the transparent plate Where n is the refractive index of light of the material that constitutes d, d = λ (N−1) / 2
A computer generated hologram characterized by being nN. 3. The computer generated hologram according to claim 1, wherein a light reflective layer is laminated along the irregularities formed on the back surface of the transparent plate. 4. The computer generated hologram according to claim 1, wherein a front surface of said transparent plate is subjected to an anti-reflection treatment. 5. A reflector using a computer generated hologram, having the requirements of claim 1. Description: 6. The reflector according to claim 5, wherein a transparent adhesive layer is laminated on a front surface of the transparent plate. 7. A reflection type liquid crystal display device, wherein the front surface of the reflection plate according to claim 5 is in close contact with the back surface of the liquid crystal display device. 8. A reflection type liquid crystal display device, wherein the front surface of the reflection plate according to claim 6 is laminated on the rear surface of the liquid crystal display device via the transparent adhesive layer. 9. The liquid crystal display element and the transparent plate in the reflection plate have substantially the same refractive index of light, or the liquid crystal display element, the transparent adhesive layer, and the reflection plate 9. The reflective liquid crystal display device according to claim 7, wherein the transparent plates have substantially the same refractive index of light. 10. The reflector according to claim 5, wherein the reflector is disposed between the liquid crystal layer and the rear substrate of the liquid crystal display device such that the front surface of the reflector is on the liquid crystal layer side. Reflective liquid crystal display device. 11. The reflecting plate according to claim 5, wherein the front surface is:
A reflective display device, which is in close contact with the back surface of a light-transmitting display device.