JP2745902B2 - Display with diffraction grating pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display formed by arranging minute diffraction gratings (gratings) for each dot on the surface of a flat substrate, and particularly to a three-dimensional display having no image skipping. The present invention relates to a display having a diffraction grating pattern capable of expressing a (three-dimensional) image.

[0002]

2. Description of the Related Art Conventionally, a display having a diffraction grating pattern formed by arranging a plurality of minute dots made of a diffraction grating on the surface of a flat substrate has been widely used. As a method for producing a display having this kind of diffraction grating pattern, there is a method disclosed in, for example, Japanese Patent Application Laid-Open No. 60-156004. In this method, minute interference fringes (hereinafter referred to as diffraction gratings) due to two-beam interference are sequentially exposed on a photosensitive film while changing the pitch, direction, and light intensity.

On the other hand, recently, an XY stage on which a planar substrate is mounted is moved by using, for example, an electron beam exposure apparatus and under computer control, so that a plurality of minute The present inventor has proposed a method of manufacturing a display on which a diffraction grating pattern having a certain pattern is formed by arranging various dots. The method is described in “US Patent Application Serial No. 276,4, filed November 25, 1988.
No. 69 ".

[0004]

However, in a display manufactured by such a manufacturing method, a picture of a display having a diffraction grating pattern may be an image input by an image scanner or the like, or a computer graphic. A produced two-dimensional image or the like is used. For this reason, since the pattern represented by the diffraction grating pattern is located on a plane on the substrate on which the diffraction grating is arranged, it can only represent a two-dimensional (two-dimensional) pattern, There is a problem that a (three-dimensional) pattern cannot be expressed.

[0005] The present invention has been made to solve the above-mentioned problems, and a diffraction grating constituting a dot is provided by:
By configuring the same curve as a group of a plurality of lines that have been translated and changing the angle at which light is diffracted,
It is an object of the present invention to provide a display having a diffraction grating pattern capable of expressing a three-dimensional (three-dimensional) image without image skipping.

[0006]

In order to achieve the above object, a display having a diffraction grating pattern according to the present invention comprises a plurality of lines formed by translating a diffraction grating forming dots on the same curve. It consists of.

Here, the diffraction grating is constituted by a group of a plurality of lines obtained by translating the same curve at a constant pitch.

Further, the change in the slope of the curve of the diffraction grating from Ω ₁ to Ω ₂ and the pitch d at which the curve moves are represented by tan (Ω ₁ ) = sin (α ₁ ) / sin (θ) tan (Ω ₂ ) = sin (α ₂ ) / sin (θ) It is preferable to determine d = λ / sin (θ). The incident angle of the illumination light is θ, the angle at which the diffraction grating should be observed (the direction of the first-order diffracted light) is α ₁ to α ₂ , and the wavelength of the first-order diffracted light is λ.

On the other hand, the diffraction grating is constituted by a group of a plurality of lines obtained by translating the same curve by changing the pitch arbitrarily.

[0010] Further, the wavelength of the light forming the diffracted light is made plural,
Each wavelength _{λ 1, λ 2, ...,} λ m, ..., λ n, 1 the intensity of each wavelength _{A, A 2, ..., A} m, ..., and A _n, required to diffract each wavelength diffraction spatial frequencies (reciprocals of the pitches) of the grating _{f 1, f 2, ...,} f m, ..., f n _{is, f 1 = sin (θ)} / λ 1 f 2 = sin (θ) / λ 2: f m = sin (theta) is _{/ λ m f n = sin (} θ) / λ n, a delta function as δ (x), the diffraction grating

[0011]

(Equation 2)

A spatial frequency distribution of F (fx) given by
(X), and the curve is moved in the moving direction so as to have a distribution of f (x).

On the other hand, the dot has a region where no diffraction grating exists.

Here, the region where no diffraction grating is present is divided by a line parallel to the direction in which the curve of the diffraction grating moves.

[0015]

Therefore, when observing the display of the present invention,
The plane image that should be seen when observed from the right direction is observed from the right direction, and the plane image that should be seen when observed from the front direction is observed from the front direction and when observed from the left direction Since the two-dimensional image to be viewed is viewed from the left direction, the observer sees an image with parallax on the left, front, and right, and can observe a three-dimensional (three-dimensional) image. In this case, the diffraction grating
With the configuration in which the lines are translated, horizontal
There is no color change in the direction, that is, observe the left and right eyes of the observer
The same point in the image looks the same color, which is extremely important in stereoscopic vision
It has a great effect. In addition, the diffraction grating is
Consists of a collection of multiple lines translated at a constant pitch
By doing so, to the viewpoint where the diffracted light moves in the horizontal direction,
The same color wavelength can always be observed.

Further, when a diffraction grating is formed in a dot shape as in the present invention, no diffraction grating is formed at a position where there is no data, so that there is no need to create an unnecessary diffraction grating. Noise.

Further, according to the present invention, since an ideal diffraction grating can be digitally formed, an image brighter than a conventional hologram can be reproduced.

Further, the diffraction grating is constituted by a group of a plurality of lines that are translated in parallel by arbitrarily changing the pitch of the same curve, so that the color of the diffracted light for each dot can be changed.
Since the color can be any color, not just a single wavelength color, the observer can observe a more natural stereoscopic image.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A display having a diffraction grating pattern according to the present invention will be described below with reference to FIGS. In this embodiment, the display is manufactured using an electron beam.

First, a method of inputting a plurality of planar images will be described with reference to FIG.

A planar image 80 of an object 85 to be displayed three-dimensionally
Is photographed using the television camera 81. That is, 1
The two television cameras 81 are arranged at a plurality of positions defined by an interval p, and photograph a plurality of planar images 85 of an object 85 corresponding to each position. The data of these plane images 85 is converted into a computer 82 using a digitizer 83.
And store it as image data. By the way, the data of these planar images 85 is
To input the data, data recorded on a video tape may be used, or photograph or movie data may be used. Further, the object 85 to be displayed three-dimensionally is not limited to an existing object, and may be computer graphics.

Next, a method for determining the direction Ω of the diffraction grating and the pitch d of the diffraction grating will be described with reference to FIGS.

As shown in FIG. 2, assume that an observer observes a display 15 having dots 16 made according to the present invention. As shown in FIG.
Assuming that the incident angle of θ is θ, the direction of the first-order diffracted light 92 diffracted by the diffraction grating 18 is α, and the wavelength of the first-order diffracted light 92 is λ, the direction Ω of the diffraction grating 18 and the diffraction grating as shown in FIG. The pitch d (reciprocal of the spatial frequency) of 18 can be obtained by the following equation. The illumination light 91
Is assumed to pass on the YZ plane, and the diffracted light is assumed to pass on the XZ plane.

Tan (Ω) = sin (α) / sin (θ) d = λ / {sin ² (θ) + sin ² (α)} ^1/2 By using the above expression, the illumination light 91 can be directed to an arbitrary direction. It is possible to obtain the direction Ω and the pitch d of the diffraction grating 18 for diffracting the light to the above. That is, the incident angle θ of the illumination light 91, the direction α of the first-order diffracted light 92, and the first-order diffracted light 92
Is given, the direction Ω of the diffraction grating 18 and the pitch d can be obtained.

Here, a pitch d 'of the diffraction grating that diffracts to the front (α = 0) is obtained. d ′ = λ / sin (θ) Therefore, d = d ′ · sin (θ) / {sin ² (θ) + sin ² (α)} ^1/2 = d ′ · cos (Ω) As shown in FIG. In a configuration in which the same curve is translated at a constant pitch, the above equation is always satisfied, so that a diffraction grating configuration that can always observe the wavelength of the same color from the viewpoint where the diffracted light moves in the horizontal direction is used. Has become. In the dot of FIG. 4, the curve forming the dot changes from the slope Ω1 to Ω2, and the curves are arranged at the pitch d ′. That is, in order to obtain a grating dot in which the range of diffracted light in the horizontal direction is an angle α1 to α2 with respect to the normal to the surface on which the grating is present, tan (Ω ₁ ) = sin (Α ₁ ) / sin (θ) tan (Ω ₂ ) = sin (α ₂ ) / sin (θ) d = λ / sin (θ) Thus, the curve changes from the slope Omega ₁ to Omega _2, may be used Gratings translation at a pitch d'.

Therefore, in the present invention, the basic configuration of one dot of the diffraction grating image is as shown in FIG.

Next, as shown in FIG. 5, the dots are divided into three in the vertical direction. Then, the divided regions into three, and r _1, r _2, r ₃ from the left. Then, the light incident on the portion r ₁ is diffracted leftward, the light incident on the portion r ₂ is diffracted frontward, and the light incident on the portion r ₃ is diffracted rightward. Will do. Here, if the dots, if you want to be able to observe only the left direction, the only portion of r _1, the diffraction grating drawing, parts of the r _2, r _3, if nothing is drawn Good. In that case, the observer sees this dot shining only when the viewpoint is in the range of e1.
In the case of FIG. 5, the dots of the diffraction grating are vertically divided into three for the sake of explanation, but it is also possible to divide the dots more than that. That is, the dots of the diffraction grating are divided by the number of parallax images to be input.

Here, for the sake of explanation, it is assumed that three parallax images of an object have been photographed. For example, it is assumed that this object looks like “T” when viewed from the left, “O” when viewed from the front, and “P” when viewed from the right (although such an object does not actually exist). Since the number of parallax images used is three, the dots are divided into three in the vertical direction. As shown in FIG. 6, “T” represents the left part of the dot, “O” represents the center part of the dot, and “P” represents the diffraction grating of the right part of the dot. Can be obtained.

The diffraction grating image thus obtained is reproduced as shown in FIG. At this time,
"T" can be observed in the left direction, "O" in the middle, and "P" in the right direction. Although the number of input images is three here, it is possible to use different parallax images to make different images enter the left and right eyes of the observer. That is, the observer observes images with parallax separately for the left and right eyes, and can obtain a three-dimensional (three-dimensional) image. Further, even when the observer's observation position is moved in the horizontal direction, a parallax image viewed from another direction can be obtained, so that a natural stereoscopic effect can be obtained.

The drawing of the diffraction grating by the electron beam exposure apparatus will be described below with reference to FIGS.

As shown in FIG. 8, the electron beam exposure apparatus includes an electron gun 50, an alignment 52, a blanker 54,
It comprises a condenser lens 56, a stig meter 58, a deflector 60, an objective lens 62, and an XY stage 20. On the XY stage 20, a dry plate 14 coated with an EB resist is placed. The blanker 54, the deflector 60, and the XY stage 20 are connected to a computer 66 via a control interface 64. The electron beam emitted from the electron gun 50 scans the dry plate 14 under the control of the computer 66.

FIG. 9 shows the dry plate 14 placed on the XY stage 20. The electron beam 70 emitted from the electron gun 50 draws the diffraction grating pattern 18 in units of the dots 16. By moving the XY stage 20, the diffraction grating pattern 1
8 is drawn.

An operation procedure for forming a diffraction grating pattern for actually displaying a three-dimensional image from a plurality of original images having parallax will be described below with reference to FIG.

First, in step a1, various parameters for drawing a diffraction grating pattern are input.
Then, in steps a2 and a3, a calculation for obtaining other parameters is performed based on the input parameters. Here, the number of original images is L, the number of drawing areas in the X direction is n, the number of drawing areas in the Y direction is m, the number of dots in the X direction in one drawing area is O, and the number of dots in the Y direction. Is P. In addition, since the drawing area of an electron beam using an electron beam exposure apparatus is generally a few mm square, an XY area is required to draw a pattern larger than that.
The drawing area needs to be imposed using the stage, and a range of several mm square at this time is called a drawing area.

Next, in step a4, data for one dot is generated. Basically, the pattern data is as shown in FIG. Then, this is divided in the vertical direction by the number of original images and stored.

Next, a diffraction grating pattern is generated for each drawing area. The data of the portion corresponding to the drawing area of the original image is checked one dot at a time, and if the data exists, it is placed at the position corresponding to the dot in the data area (array space indicating the pattern of the diffraction grating). A portion (one of the divided dots) corresponding to the original image is copied from the calculated data for one dot. By performing this operation for all drawing areas, all original images, and all dots, a diffraction grating pattern can be obtained. Then, the pattern of the diffraction grating obtained in this manner is dropped into a file for each drawing area.

The dry plate having the pattern of the diffraction grating thus formed is used as a master for duplication. To perform the duplication, a well-known embossing method is used.

As described above, in the display having the diffraction grating pattern according to the present embodiment, the diffraction grating (grating) forming the dot is formed by a group of a plurality of lines obtained by translating the same curve at a constant pitch. And the angle at which light is diffracted is changed, so that the observer sees an image with parallax between the left and right eyes when observing from the front of the display. Therefore, a three-dimensional image (three-dimensional image) can be observed on the display. Also, if the observer moves the viewpoint horizontally,
Accordingly, the image to be observed also changes smoothly, and the effect of seeing around is obtained. Therefore, a natural three-dimensional effect can be obtained.

Further, since the diffraction grating (grating) is constituted by parallel curves, it is possible to produce diffracted light that spreads in the horizontal direction. Therefore, it is possible to observe a three-dimensional image in which the image does not fly and the color does not change when the viewpoint is moved in the horizontal direction with good reproducibility. That is, in the related art, since the diffraction grating (grating) is formed by parallel straight lines, the diffracted light becomes a light beam with respect to light having a certain wavelength, and cannot generate light that spreads in the horizontal direction. . Therefore, when such a display is observed while moving in a horizontal direction at a distant position, a position where an image is visible and a position where the image is not visible occur (image jump). Therefore, if the image cannot be seen by one of the right and left eyes, stereoscopic vision cannot be performed, and the jump of the image gives an observer discomfort. In this regard, the display according to the present embodiment can solve all such problems.

Further, the dot shape of the diffraction grating is calculated from the relationship with the diffraction range of the diffracted light in the manufactured display, and the diffraction grating is not drawn in the dot shape from the diffraction range of the diffraction light in each dot. By determining the area, the dot shape for each dot is determined. For this reason, compared with the conventional method, the amount of data is small, complicated calculations are eliminated, and the operation time and work time can be reduced. That is, conventionally, only the relationship between the direction in which the diffracted light is diffracted and the direction of the diffraction grating is shown. For this reason, in order to calculate the shape of the diffraction grating, it was necessary to calculate one by one from all the diffracting directions at all the dots.
Although the processing is enormous, such a problem can be solved by the display of this embodiment.

Further, the display of this embodiment is
It is possible to obtain a brighter image with less noise than a stereoscopic display such as a hologram.

The present invention is not limited to the above embodiment, but can be implemented in the following manner.

[0043] In the above embodiment, the diffraction grating has been described for the case of constituting a group of a plurality of lines that translating the same curve at a constant pitch, not limited to this, a diffraction grating, the same curve If it is composed of a collection of multiple lines that have been translated in parallel by changing the pitch arbitrarily, it is possible to arbitrarily determine the color of the diffracted light recognized by the observer by using multiple wavelengths of the light forming the diffracted light. Becomes

For example, the wavelengths of the diffracted light to be recognized by the observer and the intensities of the respective wavelengths are represented by λ ₁ , λ ₂ ,
.., Λ _m ,..., Λ _n , and A ₁ , A _{2 ,.}
..., and A _n. At this time, the spatial frequency (reciprocal of the pitch) of the diffraction grating required to diffract each wavelength
f ₁ , f ₂ ,..., f _m ,..., f _n are obtained by the following equations, respectively.

F ₁ = sin (θ) / λ ₁ f ₂ = sin (θ) / λ ₂ : f _m = sin (θ) / λ _m f _n = sin (θ) / λ _n and the delta function is δ When expressed by (x), the diffraction grating

[0046]

(Equation 3)

It suffices to have a spatial frequency distribution of F (fx) represented by Therefore, if F (fx) is obtained by performing an inverse Fourier transform on f (x), the curve is expressed as f (x) in the moving direction.
What is necessary is just to move so that it may have distribution of (x).

As described above, by changing the moving direction of the curve constituting the diffracted light, the color of the diffracted light for each dot can be made not only a single wavelength color but also an arbitrary color. Thereby, the observer can observe a more natural three-dimensional image.

[0049]

As described above, according to the present invention, the diffraction gratings constituting the dots can be made to have the same curve as needed.
It is composed of a group of a plurality of lines that are translated in parallel at a constant pitch or arbitrarily changing the pitch, and the angle at which light is diffracted is changed, so that three-dimensional (three-dimensional) without image skipping It is possible to express a beautiful image and it is horizontal
There is no color change in the direction, i.e.
The same point in the image looks the same color, which is extremely heavy
A display having a diffraction grating pattern having a significant effect can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for capturing an original image according to the present invention.

FIG. 2 is an explanatory diagram of a method for observing dots created by the present invention.

FIG. 3 is an enlarged view of a dot according to the present invention.

FIG. 4 shows a basic example of a diffraction grating image according to the present invention.
An enlarged view of a dot.

FIG. 5 is an explanatory diagram of a method of dividing one dot according to the present invention.

FIG. 6 is an explanatory diagram of a method for manufacturing a display according to the present invention.

FIG. 7 is an explanatory diagram of a display observation method created by the present invention.

FIG. 8 is a schematic view of an electron beam exposure apparatus used for manufacturing a display having a diffraction grating pattern according to one embodiment of the present invention.

FIG. 9 is a view showing an EB resist dry plate placed on an XY stage.

FIG. 10 is a flowchart of a manufacturing method according to one embodiment of the present invention.

[Explanation of symbols]

14 ... Dry plate, 16 ... Dot, 18 ... Diffraction grating pattern,
20 XY stage, 70 electron beam, 80 planar image, 81 television camera, 82 computer, 83
... digitizer, 85 ... object.

Claims (7)

(57) [Claims] In a display formed by arranging minute diffraction gratings (gratings) for each dot on the surface of a planar substrate, the diffraction gratings forming the dots translate the same curve in parallel. A display having a diffraction grating pattern, wherein the display is constituted by a collection of a plurality of lines. 2. The display having a diffraction grating pattern according to claim 1, wherein the diffraction grating is constituted by a group of a plurality of lines obtained by translating the same curve at a constant pitch. 3. The change in the slope of the curve of the diffraction grating from Ω1 to Ω2 and the pitch d at which the curve moves are: tan (Ω ₁ ) = sin (α ₁ ) / sin (θ) tan (Ω ₂ ) = sin (Α ₂ ) / sin (θ) d = λ / sin (θ), where the incident angle of the illumination light is θ, the angle at which the diffracted light should be observed (the direction of the first-order diffracted light) is α ₁ to α ₂ , The display having the diffraction grating pattern according to claim 1, wherein the wavelength of the first-order diffracted light is λ. 4. The display having the diffraction grating pattern according to claim 1, wherein the diffraction grating is constituted by a group of a plurality of lines obtained by translating the same curve while changing the pitch arbitrarily. 5. The method according to claim 1, wherein the wavelength of the diffracted light is plural.
Each wavelength _{λ 1, λ 2, ...,} λ m, ..., λ n, the intensity of each wavelength _{A 1, A 2, ...,} A m, ..., and A _n, for diffracting each of said wavelengths The required spatial frequencies (reciprocal of pitch) f ₁ , f ₂ ,..., F _m ,..., F _n of the diffraction grating are as follows: f ₁ = sin (θ) / λ ₁ f ₂ = sin (θ) / λ ₂ : f _m = sin (θ) / λ _m f _n = sin (θ) / λ _n , and the delta function is δ (x). A spatial frequency distribution of F (fx) represented by the following equation is obtained, and the inverse Fourier transform of the F (fx) is defined as f (x).
The display having a diffraction grating pattern according to claim 4, wherein the curve is moved in the moving direction so as to have the distribution of f (x). 6. The display having a diffraction grating pattern according to claim 1, wherein the dot has an area where no diffraction grating is present. 7. The display having a diffraction grating pattern according to claim 6, wherein the area where the diffraction grating does not exist is divided by a line parallel to a moving direction of a curve of the diffraction grating.