JP3925035B2 - Method for producing diffraction grating pattern - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pattern expressed by disposing minute cells for forming a diffraction grating on the surface of a substrate and a method for manufacturing the same, and in particular, has a higher resolution and diffracts and scatters light according to the outer shape of the cell. The present invention relates to a pattern with less influence and a manufacturing method thereof.
[0002]
[Prior art]
Patterns composed of diffraction gratings have a directional gloss that cannot be expressed with ordinary printing technology, so they are widely used in display products and security products aimed at preventing counterfeiting. It is required to produce a pattern that is highly effective and difficult to counterfeit.
[0003]
In response to such a demand, a display having a diffraction grating pattern constituted by a collection of cell (dot) -like diffraction gratings is known.
In the following description, a cell that is an element for forming a diffraction grating is referred to as a diffraction grating cell.
[0004]
As a method for producing the display, a method exemplified in JP-A-60-156004 is known. In this method, minute interference fringes (diffraction grating) due to two-beam interference of laser light are successively exposed on a photosensitive film while changing the pitch, direction, and light intensity.
[0005]
On the other hand, by using an electron beam exposure apparatus instead of a laser, and by computer control, an XY stage on which a planar substrate is placed is moved, and a plurality of minute dots made of a diffraction grating are formed on the surface of the substrate. There has also been proposed a method of manufacturing a display in which a diffraction grating pattern is formed by disposing.
The above method is disclosed in JP-A-2-72320 and US Pat. No. 5,058,992.
[0006]
As a parameter of the diffraction grating pattern,
(1) Spatial frequency of diffraction grating (pitch of grating line)
(2) Direction of diffraction grating (direction of grating line)
(3) Diffraction grating drawing area (arrangement of diffraction grating cells)
There are three,
In accordance with (1), the color at which the diffraction grating cell appears shining with respect to a fixed point changes,
In accordance with (2), the direction in which the diffraction grating cell appears shining changes,
A display pattern (picture) is determined according to (3).
[0007]
“Cell” and “dot”, which are the structural units of the display (pattern), are treated as synonyms, but the term “cell” with nuances that are not restricted by shape (outline) and size, The following description is unified as “diffraction grating pattern”.
[0008]
In addition, the spatial frequency of the diffraction grating and the pitch of the grating line are in a reciprocal relationship.
[0009]
By the way, such a diffraction grating pattern becomes an outline of a cell because a cell is defined in pixel units and a diffraction grating is formed inside the cell, thereby diffracting light in an arbitrary direction and color and perceiving an image. In this part, the outline of the grid line is forcibly cut off.
[0010]
For example, when a diffraction grating having a hypotenuse is cut out by an outline of a rectangular cell, a horizontal and vertical outline that cannot be originally formed in the diffraction grating constituted by the hypotenuse is generated in the outline. (See Figure 2)
In FIG. 2, the line segments that define the cell outline are the horizontal and vertical directions, and the line segments that define a different grid pattern are referred to as “slopes”.
[0011]
If the cell area is large, the outline of the cell diffracts and scatters the light in a direction different from the original direction, and the entire image of the diffraction grating pattern may become white or have a different color from the design. There is.
[0012]
In general, even a conventional diffraction grating pattern arranged in a dot matrix shape is so small that the shape of the cell cannot be confirmed with the naked eye and is not a problem in terms of the pattern. At the micro level, diffraction and scattering occur in different directions from the design, and quality cannot be guaranteed.
[0013]
[Problems to be solved by the invention]
For the diffraction grating pattern in which the diffraction grating is arranged on the substrate in dot matrix units, the light scattering generated by the outer shape of the cell is unavoidably a noise component, and this noise component varies depending on the design of the diffraction grating pattern. Difficult to grasp quantitatively, even if the same diffraction grating pattern production method is used, there are few noise components with high quality depending on the type of diffraction grating used, and there are a lot of noise components. Sometimes bad patterns can be produced.
[0014]
In the diffraction grating pattern arranged by the dot matrix, the present invention reduces unnecessary diffraction and scattering that are not in the design concept exerted by the outer shape of the cell, the noise component is not conspicuous, and the observation direction and the observation area (viewing area) are correct. An object of the present invention is to provide a diffraction grating pattern and a manufacturing method thereof.
[0015]
[Means for Solving the Problems]
The present invention achieves the above object by making the size of a cell, which is an element for constituting diffraction grating data, smaller than the pitch of the grating lines in the diffraction grating pattern.
The cell-like element having a size smaller than the pitch of the lattice lines according to the present invention is referred to as a “fine cell”.
[0018]
A method for producing a diffraction grating pattern according to the invention of claim 1 comprises:
In a method for producing a diffraction grating pattern, in which a plurality of types of diffraction gratings are arranged and formed on a substrate surface as a structural unit, and at least one of the spatial frequency of the diffraction grating and the angle of the diffraction grating is changed.
Configuring image data for deriving diffraction grating data in a dot matrix; and
Comparing the color information of any pixel of the image data and neighboring pixels adjacent to the pixel;
Merging pixels that can be approximated as the same color, creating a region with a new outline,
Determining color information for each new area;
A step of deriving diffraction grating data from the color information;
Placing a diffraction grating on a substrate;
It is characterized by comprising.
[0019]
A method for producing a diffraction grating pattern according to the invention of claim 2 comprises:
In a method for producing a diffraction grating pattern, in which a plurality of types of diffraction gratings are arranged on the substrate surface, and at least one of the spatial frequency of the diffraction grating and the angle of the diffraction grating is changed.
Configuring image data for deriving diffraction grating data in a dot matrix; and
Merging each pixel of the image data in a matrix and creating a region having a new outline;
Averaging the color information of the dot matrix constituting the merged pixels and determining the color information of the new area;
A step of deriving diffraction grating data from the color information;
Placing a diffraction grating on a substrate;
A method for producing a diffraction grating pattern, comprising:
[0020]
A method for producing a diffraction grating pattern according to the invention of claim 3 comprises:
In the manufacturing method of the diffraction grating pattern of Claim 1 or 2 ,
A step of creating an image made up of draw data such as straight lines and curves defined by mathematical formulas as image data for deriving diffraction grating data;
A step of creating an image converted from a dot matrix sufficiently fine so as not to lose draw data information;
It is obtained by these.
[0021]
A method for producing a diffraction grating pattern according to the invention of claim 4 comprises:
In the manufacturing method of the diffraction grating pattern of Claim 1 or 2 ,
Image data for deriving diffraction grating data is converted from an image composed of a dot matrix into an image composed of a finer dot matrix;
A step of performing color information smoothing processing (anti-aliasing processing) from information between adjacent pixels of the image;
It is obtained by these.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an example of a conventional diffraction grating pattern in which the cells arranged on the substrate are larger than the outline of the grating lines. Thus, when a pattern and a pattern are arranged on a pattern by a plurality of cells, the outline of the pattern and the pattern can be regarded as smooth as long as the pattern is observed with the naked eye. However, as shown in the enlarged view in the figure, in such a diffraction grating pattern, it is possible to recognize what the outer shape of the cell is, and light is reflected by the outer portion of the grid line cut out by the outer shape of this cell. Diffracting and scattering in a direction different from the original design direction causes the entire image of the diffraction grating pattern to become white.
[0023]
In particular, as shown in FIG. 2, when cells are regularly arranged in a rectangular shape or the like, noise components due to diffraction and scattering that occur in the outer shape of the cell are vertically and horizontally due to periodicity of the cell arrangement. When the diffraction grating pattern is observed from such a direction, some diffracted light is observed from a direction that should not be seen in many cases.
In general, such noise components are likely to occur when there is a shape with a different angle from the design, such as the outer shape of the cell, at a larger interval than the pitch of the diffraction grating, and at a smaller interval than the pitch of the diffraction grating. When such a shape is arranged, the optical behavior is indefinite, and a phenomenon in which noise components are strengthened does not occur and is not recognized.
[0024]
Therefore, let us consider a case where the elements (fine cells) for configuring the diffraction grating are further reduced (the resolution of the original digital image is improved), and the size of the fine cells is smaller than the pitch of the grating lines. In this case, either one microcellular but it would buried in the grid line, or does not belong in the fine cells at all grid lines, or microcellular on grid lines outline are arranged on either of the case of apply.
In any case, if the same type of fine cell exists alone, a pattern depending on the external shape of the fine cell , which has nothing to do with the shape of the lattice line, is created. It is assumed that there is a group of sufficient number of identical fine cells to configure, but by making the fine cells sufficiently smaller than the outline of the lattice lines, it is finer and optically smoother than the pitch of the lattice lines It is possible to construct a grid line having an outer shape that can be regarded as (see FIG. 3).
[0025]
In this way, by handling a plurality of fine cells as a group and configuring each grating line, the outline of the grating line is often finer than the pitch of the diffraction grating, so that it can be considered optically smooth.
[0026]
Even in this case, diffraction and scattering of light occurs in the outline of the grating line. However, in FIG. 3, diffraction and scattering occur regardless of the outer shape of the fine cell because the side of the fine cell is finer than the pitch of the diffraction grating. Therefore, it is possible to suppress a phenomenon in which a noise component appears strongly in a direction depending on the external shape of the fine cell as a whole.
[0027]
In general, the pitch of the diffraction grating arranged on the diffraction grating pattern is 2 μm or less. Therefore, in order to expect the effect of the present invention, it is desirable that the size of the fine cell is 2 μm or less at the maximum.
[0028]
As the pattern and pattern drawn on the diffraction grating pattern, an image obtained by digitizing an image by a computer graphic, a photograph, a printed matter, a hand-drawn design or the like by a reading device such as a scanner is usually used. In these images, pixels are arranged in a matrix, and each has unique color information. It is impossible to define a grating line if those pixels are smaller than the grating line drawn on the diffraction grating pattern. Therefore, an arbitrary pixel and the pixels arranged in the periphery of the pixel are merged to define a “region” having a new outline, ensuring an area sufficient to function as a diffraction grating, and a grid inside the “region”. It is necessary to place a line. In this paper, an area having a free outline having an area sufficient to function as a diffraction grating is referred to as a “region”, and a conceptual diagram thereof is shown in FIG.
[0029]
Examples of region generation methods are shown in FIGS.
FIG. 5 is a conceptual diagram of a process of generating one new region by merging pixels determined to be able to compare and approximate information of adjacent pixels. In this case, the outer shape of the region has a free shape, and if the original pixel is sufficiently small, the outline of the region can be regarded as a curve. This generation method requires complicated processing steps, but it is possible to draw patterns with various accuracy by adjusting approximate conditions.
[0030]
FIG. 6 is a conceptual diagram of a process of merging adjacent pixels in a matrix and generating one or a plurality of new areas therein. In this case, there may be pixels with various colors as well as approximate colors in the matrix, so the matrix is divided into appropriate areas, and the colors of the pixels in each area are averaged to create new colors. Need to be defined. In this generation method, since processing is performed for each matrix, a relatively easy processing step is sufficient, and the accuracy can be changed by adjusting the size of the matrix.
[0031]
Further, a method called CAE (Computer Aided Engineering) is used to design a body such as an automobile or an airplane or an industrial workpiece having a curved surface or a curve using a computer (see FIG. 7).
Curve and curved surface data defined by this method is generally called draw data, which is expressed by mathematical formulas and vectors, etc. Unlike a dot matrix image, it holds a smooth shape in the data. . Even when a diffraction grating pattern is generated from such draw data, if the dot data is converted into a fine dot matrix to an accuracy that does not impair the information of the draw data according to the present invention, the dot matrix diffraction grating is formed on the substrate as usual. It can be handled as an arranged diffraction grating pattern.
[0032]
Also, as shown in FIG. 8A, when each pixel of a rough image (with a small number of pixels) is subdivided to create a finer image (with a large number of pixels), the number of pixels increases as it is. There will be no change in image resolution and quality.
Here, as shown in FIG. 8 (b), it is used in the field of computer graphics in which pixels having data such as a mixture of these pixels based on the data of adjacent pixels are arranged between them. By applying an image smoothing technique called anti-aliasing to the entire image, it is possible to create an image that achieves a resolution that was not possible with the original rough image, and to produce the high-quality diffraction grating pattern shown in FIG. Can be produced.
[0033]
【The invention's effect】
As described above, the diffraction grating pattern of the present invention is expected to have the following effects because each fine cell is sufficiently fined until the outer shape of the fine cell becomes smaller than the pitch of the grating line.
(1) Since the external shape of the micro cell is so fine that it cannot be recognized, the information of the object read by the scanner and the information of the shape defined by the draw data are not impaired, and the image (appearance, atmosphere) of the object is faithfully preserved. Can be reproduced, and the difference from the counterfeit product can also be expressed clearly.
(2) light diffraction occurring on the outer shape of microcellular, since the direction of the scattering is dispersed in a direction that does not depend on the outer shape of the fine cells can be avoided that the noise component appears strongly in a particular direction.
(3) Compared with the conventional pattern in which diffraction gratings are drawn in cell units by making the grating lines continuous throughout the cell group, which is the same diffraction grating , the original image is reproduced more faithfully and color representation with high saturation is achieved. Is possible.
(4) Although it is a diffraction grating pattern based on dot matrix data, even if observation is performed at a magnification of the diffraction grating level, the fine cell shape is not recognized. Have difficulty.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an example of a conventional diffraction grating pattern in which cells arranged on a substrate are larger than the outline of a grating line.
FIG. 2 is an explanatory diagram showing a noise component generated in an outer portion of a cell.
3 is a conceptual diagram showing an example of a diffraction grating pattern according to the present invention that can improve the resolution of the original digital image shown in FIG. 1 and can expect a smooth change not only in design but also in light diffraction.
FIG. 4 is a diagram showing the concept of “region” defined in the present invention.
FIG. 5 is an explanatory diagram showing an example of a region generation method. Here, an area having a free shape is generated by merging pixels having approximate colors.
FIG. 6 is an explanatory diagram illustrating an example of a region generation method. Here, the pixels are merged in a matrix to generate a region.
FIG. 7 is an explanatory diagram showing that the present invention can be applied to image data that is not defined as a dot matrix, such as draw data, and that a diffraction grating pattern can be obtained with an accuracy equivalent to that of draw data.
FIG. 8: An anti-aliasing process, which is one of computer graphics techniques, is applied to a low-resolution image to convert it into a smooth and high-resolution image, improving the visual quality and diffracting and scattering light at the diffraction grating. Explanatory drawing which shows that the influence of can also be reduced.

Claims (4)

In a method for producing a diffraction grating pattern, in which a plurality of types of diffraction gratings are arranged and formed on a substrate surface as a structural unit, and at least one of the spatial frequency of the diffraction grating and the angle of the diffraction grating is changed.
Configuring image data for deriving diffraction grating data in a dot matrix; and
Comparing the color information of any pixel of the image data and neighboring pixels adjacent to the pixel;
Merging pixels that can be approximated as the same color, creating a region with a new outline,
Determining color information for each new area;
A step of deriving diffraction grating data from the color information;
Placing a diffraction grating on a substrate;
A method for producing a diffraction grating pattern, comprising: In a method for producing a diffraction grating pattern, in which a plurality of types of diffraction gratings are arranged on the substrate surface, and at least one of the spatial frequency of the diffraction grating and the angle of the diffraction grating is changed.
Configuring image data for deriving diffraction grating data in a dot matrix; and
Merging each pixel of the image data in a matrix and creating a region having a new outline;
Averaging the color information of the dot matrix constituting the merged pixels and determining the color information of the new area;
A step of deriving diffraction grating data from the color information;
Placing a diffraction grating on a substrate;
A method for producing a diffraction grating pattern, comprising: In the manufacturing method of the diffraction grating pattern of Claim 1 or 2 ,
A step of creating an image made up of draw data such as straight lines and curves defined by mathematical formulas as image data for deriving diffraction grating data;
A step of creating an image converted from a dot matrix sufficiently fine so as not to lose draw data information;
A method for producing a diffraction grating pattern, which is obtained by: In the manufacturing method of the diffraction grating pattern of Claim 1 or 2 ,
Image data for deriving diffraction grating data is converted from an image composed of a dot matrix into an image composed of a finer dot matrix;
A step of performing color information smoothing processing (anti-aliasing processing) from information between adjacent pixels of the image;
A method for producing a diffraction grating pattern, which is obtained by:

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