JP4238396B2 - display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pattern formed by arranging, as a structural unit, cells made of minute diffraction gratings (gratings) on the surface of a substrate.
[0002]
[Prior art]
As a pattern configured by arranging dots (cells) made of a diffraction grating on a substrate surface, a proposal represented by JP-A-2-72320 is well known.
Such a pattern is expressed as follows: “In a pattern in which a plurality of minute dots consisting of diffraction gratings are arranged on the substrate surface, the spatial frequency of the diffraction grating, the direction of the diffraction grating, the pitch at which each dot is arranged, each dot In which at least one of the arrangements of the two is changed.
That is, each of the above dots is a pixel constituting a pattern, but hereinafter, in the present specification, the term “diffraction grating cell” is used to collectively refer to minute dots and cells made of a diffraction grating.
[0003]
As described above, in the conventional pattern, one diffraction grating cell corresponds to one pixel constituting the pattern (image), and by using a diffraction grating cell having a different direction (angle) for each pattern as a pixel, A plurality of types of patterns that can be observed only from the direction corresponding to the direction (angle) of the diffraction grating can be displayed.
[0004]
By making images of the same object having parallax as a plurality of types of patterns, the observer can obtain a three-dimensional effect because he / she visually sees patterns with parallax (both eyes) in the right eye and the left eye. .
A proposal for constructing a stereoscopic image by a diffraction grating pattern is known from Japanese Patent Laid-Open No. 3-201401.
[0005]
[Problems to be solved by the invention]
In order to express many kinds of patterns (images), it is necessary to arrange diffraction grating cells in many kinds of directions (angles), and (1) it takes time to produce. (2) The resolution of the display image becomes coarse. (3) Spatial arrangement of diffraction grating cells becomes difficult. There were problems such as.
Further, in such a pattern, since the diffraction grating cells are spatially arranged, the pattern configuration can be analyzed relatively easily.
[0006]
An object of the present invention is to solve the problems (1) to (3) and to provide a diffraction grating pattern in which many kinds of patterns (images) are mixed in the same pattern.
[0007]
[Means for Solving the Problems]
The present invention
In a display in which a cell composed of a diffraction grating is used as a constituent unit, and a plurality of the cells are arranged on the substrate surface.
The pattern includes a plurality of types of cells composed of diffraction gratings in which at least one of the spatial frequency and direction of the grating is changed, and includes a region where the cells are spatially overlapped as a pixel. It is reproduced by,
The main feature is that it includes an image having a pixel in a region where the cells are spatially overlapped, and an image different from the above in which a cell is formed of a diffraction grating having at least approximately the same grating direction .
[0008]
In the present invention, the case where both the spatial frequency and the direction are equal among the parameters of the diffraction grating is an “equal” diffraction grating, and as shown in FIG. The diffraction grating cell 2 composed of the grating stripes rising to the left has a different grating direction and is treated as a “different” diffraction grating.
[0009]
Even if the spatial frequencies and directions are the same and are “equal” diffraction gratings, if their phases are different, the region where they are superimposed is a diffraction grating containing another spatial frequency component.
[0010]
A region in which the diffraction grating cells overlap spatially (in FIG. 1, a grid-like region in which a diffraction grating cell 1 made up of a right-up grating stripe and a diffraction grating cell 2 made up of a left-up grating stripe partially overlap) Is reproduced by diffracted light due to moire components (or crosstalk components) between overlapping diffraction grating cells.
[0011]
In the present invention,
An image (1) having a region where the diffraction grating cells are spatially overlapped as a pixel and an image (2) different from the above including at least a cell having a diffraction grating having substantially the same grating direction as a pixel are included. Can do.
[0012]
The image (2) may include not only one type but also a plurality of types in the pattern.
[0013]
At this time, by changing the combination of the diffraction grating cells, the above regions can also have different moiré components. Therefore, the image (1) in which the regions where the diffraction grating cells are spatially overlapped can be made into a plurality of types. is there.
[0014]
In the image (2), the gradation of the image (2) can be controlled according to the diffraction efficiency of the diffraction grating cell or the cell size. (Claim 3)
Further, according to the characteristics of the diffraction grating, the color of the cells constituting the image (2) can be controlled by the difference in spatial frequency. Similarly, also in the image (1), the gradation of the image (1) can be controlled according to the diffraction efficiency of the moire component of the diffraction grating cell or the size of the overlapping region.
[0015]
Furthermore, in the present invention, it is also possible to give parallax between different images (2 and 2 ′) having pixels as cells composed of diffraction gratings having at least substantially the same grating direction. (Claim 4)
Further, it is possible to give a parallax between these images (2 and 2 ′) and an image (1) having a pixel in a region where the diffraction grating cells as pixels are spatially overlapped.
[0016]
As multiple types of patterns such as separate images (2 and 2 'and 1), each is an image of the same object having parallax (as obtained by shooting a three-dimensional object while changing the viewpoint) Thereby, the observer can obtain a three-dimensional effect because he / she visually sees a pattern with parallax (both eyes) in the right eye and the left eye.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
As described above, in the present invention, the case where both the spatial frequency and the direction are equal among the parameters of the diffraction grating is an “equal” diffraction grating, and the “type of diffraction grating” is mainly the diffraction grating. It means that the direction is different.
[0018]
However, subtle differences in direction are not distinguished, and the diffraction gratings that emit diffracted light (first-order diffracted light) incident on the observer's monocular (one eye) at the same time during pattern observation are the same type.
[0019]
Also, with regard to the spatial frequency of the diffraction grating, the diffraction gratings that emit the diffracted light (first-order diffracted light) that is simultaneously incident on the observer's monocular are of the same type, and in a special case (that is, the spatial frequency differs greatly and The diffraction grating cell pair (if not recognized by the observer's monocular) is of a different type.
[0020]
FIG. 1 shows examples 1 and 2 of different types of diffraction grating cells, which are constituent elements (pixels) of the pattern of the present invention, and diffraction grating cell 1 when diffraction grating cells 1 and 2 are arranged adjacent to each other (conventional). , 2 will be described with respect to an example (the present invention) in which a part is overlapped.
Examples of diffraction grating patterns are shown in FIG. 6 (conventional) and FIG. 7 (present invention).
[0021]
That is, in the conventional diffraction grating pattern, the diffraction grating cells are arranged in a matrix, but in the diffraction grating pattern of the present invention, the diffraction grating cells other than the image having the diffraction grating cell as a pixel are overlapped due to the overlapping of different types of diffraction grating cells. In addition, another image is expressed.
[0022]
FIG. 2 shows two images (image A and image B) represented by different types of diffraction grating cells (diffraction grating cells 1 and 2) as pixels, and another image (image C). ) Is an example in which the overlapping area of the diffraction grating cells 1 and 2 is expressed as a pixel.
[0023]
In this case, when the display of the present invention is observed from a certain viewpoint, the image A can be recognized, the image B can be observed from another viewpoint, and the image C can be observed from another viewpoint.
[0024]
The effect of the diffraction grating pattern of the present invention will be described in more detail based on the Fourier transform image of the diffraction grating pattern.
FIG. 3 shows a Fourier transform image for a single diffraction grating cell.
A Fourier transform image can be considered as a distribution of light (Fraunhofer diffraction image) projected onto a screen when monochromatic light is incident perpendicularly to the diffraction grating cell and the screen is placed at a position sufficiently away from the diffraction grating cell. .
[0025]
In the figure, the bright spot at the center of the Fourier transform image represents the 0th-order diffracted light (reflected light or transmitted light on the diffraction grating cell surface) from the diffraction grating cell.
Two first-order diffracted lights appear symmetrically around the zeroth-order diffracted light, but here, the first-order diffracted light (or simply “diffracted light”) that is visible to the observer is diffracted light that appears above the zeroth-order diffracted light (+ 1st-order diffracted light). ).
[0026]
The angular position of the 1st-order diffracted light centered on the 0th-order diffracted light depends on the angle of the diffraction grating. Therefore, the positions of the corresponding first-order diffracted light are different between the diffraction grating cells 1 and 2. The position of the first-order diffracted light corresponds to that the position of the diffraction grating cell that has emitted the first-order diffracted light appears to shine on the pattern when the observer puts an eye on it. The dots do not shine and appear dark.
[0027]
At this time, if the diffraction efficiency of the diffraction grating cell is high or the cell size is large, the point looks brighter, otherwise it is recognized as a point that shines darkly.
Therefore, an image in which these diffraction grating cells are expressed as pixels can be observed only from a direction corresponding to the emission direction of the first-order diffracted light of the diffraction grating cell as an image with gradation.
[0028]
When the diffraction grating cells 1 and 2 are arranged adjacent to each other, the Fourier transform images are the sum of the Fourier transform images when they are arranged in a single manner (FIG. 4 (a)).
That is, if a plurality of independent images are represented by different types of diffraction grating cells as pixels, a plurality of images that can be observed only from the corresponding emission direction of the first-order diffracted light can be displayed.
[0029]
Here, with respect to those having regions where different types of diffraction grating cells overlap, the Fourier transform image is as shown in FIG.
That is, diffracted light corresponding to the moire component in the region where the diffraction grating patterns overlap is generated. An image in which the overlapping area between the diffraction grating cells is expressed as a pixel can be observed only from a direction corresponding to the emission direction of the diffracted light of the moire component.
[0030]
As described above, the description has been made based on the Fourier transform image. However, when the diffraction grating pattern is actually observed, the illumination is often performed obliquely from above.
That is, as shown in FIG. 5, the 0th-order diffracted light (reflected light or transmitted light) is emitted obliquely downward.
[0031]
At this time, the discussion based on the Fourier transform image described above holds true if the spatial shift is performed so that the position of the 0th-order diffracted light is matched.
When illuminating obliquely from above, the first-order diffracted light in the above discussion can be emitted in a direction substantially perpendicular to the display surface and the first-order diffracted lights are aligned in the horizontal direction (that is, different in the horizontal direction). The horizontal viewpoint can be used to view the image).
If this principle is applied and an image sequence with parallax is used as an image that can be observed from each viewpoint, a stereoscopic image using binocular parallax can be displayed.
[0032]
As described above, when the diffraction grating cells are arranged side by side as in the prior art, the number of types of diffraction grating cells increases in proportion to the number of images to be displayed. In the present invention, the overlapping region of two types of diffraction grating cells is used. Therefore, even if the type of the diffraction grating cell is the same as the conventional one, a larger number of images can be displayed.
[0033]
This also makes it difficult to analyze the pattern configuration, and is effective in preventing forgery and counterfeiting of patterns.
[0034]
In the above, diffraction gratings having different angles have been discussed as types of diffraction gratings, but diffraction gratings having significantly different spatial frequencies can also be used.
However, in general, the spatial frequency difference is not so large, and the spatial frequency of the diffraction grating is closely related to the display color of the diffraction grating cell during observation.
[0035]
Therefore, in the present invention, the diffraction gratings that can be observed simultaneously at the time of observation are regarded as the same type. Specifically, for example, differences in spatial frequency up to about 400 lines / mm are considered as the same type of diffraction grating.
[0036]
In the above example, the case where the size of the diffraction grating cell is uniform has been described. However, the present invention is not limited to this, and even if the size of the diffraction grating cell differs depending on the type of the diffraction grating cell, or locally differs. In other words, the gradation of an image can be expressed by the overlapping area of different types of diffraction grating cells and the diffraction efficiency in that region.
[0037]
The diffraction grating pattern of the present invention uses a plurality of types of diffraction grating cells as shown in FIG. 7, and displays an image 1 (image C in FIG. 2) using a region in which different types of diffraction grating cells are spatially overlapped as pixels. The main feature is to do.
Here, apart from the image expressed by the overlapping region of the diffraction grating cells, it is possible to express an independent image 2 (images A and B in FIG. 2) using diffraction grating cells having substantially the same angle as pixels. is there. It can be considered that these images are displayed using the diffraction grating shown in the lower part of FIG. 2 as pixels in the diffraction grating pattern.
[0038]
At this time, the gradation of the image 2 can be expressed by the diffraction efficiency of the diffraction grating cell or the size of the cell. Differences in spatial frequency are mainly observed as differences in image colors.
In addition, a plurality of types of images 2 can be displayed using a diffraction grating cell group having substantially the same angle as each pixel.
Furthermore, the gradation of the image 1 can be expressed based on the size of the region where the diffraction grating cells overlap or the size of the region and the diffraction efficiency of each diffraction grating cell.
[0039]
【The invention's effect】
In order to improve the security of the diffraction grating pattern, etc., if it is intended to express many kinds of images in the same pattern, it is necessary to arrange diffraction grating cells in many kinds of directions (angles). It takes time to make. (2) The resolution of the display image becomes coarse. (3) Spatial arrangement of diffraction grating cells becomes difficult. There was a problem such as
According to the present invention, since it is possible to display an image using a region where two types of diffraction grating cells overlap as pixels, even if the type of the diffraction grating cell is the same as the prior art, more types of images can be patterned. Can be displayed within.
As a result, the analysis of the pattern configuration becomes difficult, and the effect of preventing pattern forgery and counterfeiting is improved.
[0040]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a diffraction grating cell and its arrangement.
FIG. 2 is an explanatory diagram showing the correspondence between different types of images and cells that constitute the pixels in the diffraction grating pattern of the present invention.
FIG. 3 is an explanatory diagram showing Fourier transform images for each diffraction grating cell.
FIG. 4 is an explanatory diagram showing a Fourier transform image according to the arrangement of diffraction grating cells.
FIG. 5 is an explanatory diagram showing a display state of a diffraction grating pattern.
FIG. 6 is an explanatory diagram showing an enlarged cell arrangement for a conventional diffraction grating pattern.
FIG. 7 is an explanatory diagram showing an enlarged cell arrangement for the diffraction grating pattern of the present invention.

Claims (4)

In a display in which a cell composed of a diffraction grating is used as a constituent unit, and a plurality of the cells are arranged on the substrate surface.
The pattern includes a plurality of types of cells composed of diffraction gratings in which at least one of the spatial frequency and direction of the grating is changed, and includes a region where the cells are spatially overlapped as a pixel. It is reproduced by,
An image having an area where the cells are spatially overlapped as a pixel, and an image different from the above, in which at least a cell formed of a diffraction grating having substantially the same grating direction is used as a pixel. display.   2. The display according to claim 1, further comprising, as a pixel, a region where the cells made of different types of diffraction gratings are spatially overlapped. The display according to claim 1, wherein the gradation of the configured image is expressed by the size of the pixel or the diffraction efficiency. The display according to any one of claims 1 to 3, wherein different images having at least cells formed of diffraction gratings having substantially the same grating direction as pixels have parallax.

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