JP2007334076A - Optical diffraction structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical diffraction structure capable of changing grating pitch and grating angle of a diffraction grating simultaneously and continuously and capable of expressing the gradation three-dimensionally by solving the problem of the conventional technique that can not provide the optical diffraction structure capable of expressing the gradation three-dimensionally, although the conventional technique can provide a display which can simply express the gradation even when using a binary device such as electron beam exposure device, and further has a diffraction grating pattern having excellent molding property, capable of performing convenient duplication even in a duplicating process. <P>SOLUTION: The optical diffraction structure 1 is formed from an assembly of diffraction gratings, wherein at least part of the assembly of diffraction gratings has a region where the grating pitch P and grating angle α are changed simultaneously and continuously. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical diffractive structure, and more particularly to an optical diffractive structure in which a grating pitch and a grating angle of a diffraction grating are changed simultaneously and continuously in a technique for expressing a gradation effect by a diffraction grating.

Holograms, diffraction gratings, and the like can express special decorative images and three-dimensional images, and are therefore used for printed materials with improved design. Further, since advanced technology is required for production, it is used as a means for preventing forgery.
Fields used to enhance design properties include high-priced product packaging materials, pamphlets, POPs, book covers, etc., and fields used as anti-counterfeiting means include, for example, credit cards, ID cards, etc. Cards, gift vouchers such as gift certificates, checks, bills, stock certificates, admission tickets, and various certificates.
In addition, as a method of attaching these holograms and diffraction gratings to an object, there are a method of attaching by thermal transfer and a method of attaching as a label.
The thermal transfer method is used for a long time and is often used for the aforementioned cards and cash vouchers that have a flat application surface. The label method is used when the object to be applied does not have a flat surface. The

A “display having a diffraction grating pattern” has been provided as a diffraction grating used to enhance the above-described designability (see, for example, Patent Document 1).
The technique introduced in Patent Document 1 is for producing a display body in a display formed by disposing a plurality of cells made of minute diffraction gratings (gratings) on the surface of a planar substrate. Based on the first original data, the diffracted light intensity of each diffraction grating cell at the time of reproduction is suppressed by appropriately changing the ratio of the line width and the grating interval of the diffraction grating constituting each diffraction grating cell. It is said that.

JP-A-7-84110

The technique disclosed in Patent Document 1 can easily realize gradation expression even when a binary device such as an electron beam exposure apparatus is used, and has a good moldability even in a replication process, and performs simpler replication. It is said that the object is to provide a display having a diffraction grating pattern that can be used, and does not provide an optical diffraction structure that expresses gradation three-dimensionally.
SUMMARY OF THE INVENTION An object of the present invention is to provide an optical diffraction structure in which a grating pitch and a grating angle of a diffraction grating are changed simultaneously and continuously to express a gradation in three dimensions.

  In order to solve the above problems, a first aspect of the light diffraction structure of the present invention is a light diffraction structure formed by a set of diffraction gratings, wherein at least a part of the diffraction grating set includes It has a region where the pitch and the lattice angle change simultaneously and continuously.

  Further, the second aspect is the same as the first aspect, in which the grating angle of the diffraction grating continuously changes in a region where the grating pitch and the grating angle change simultaneously and continuously. The direction in which the grating pitch of the diffraction grating continuously changes is defined as the normal direction.

  The third aspect is characterized in that, in any one of the first and second aspects, the grating pitch of the diffraction grating is in the range of 0.4 to 5.0 μm.

1) An optical diffractive structure formed by a set of diffraction gratings as in the first aspect of the optical diffractive structure of the present invention, wherein at least part of the set of diffraction gratings includes a grating pitch and a grating angle of the diffraction grating. By having an area that changes at the same time and continuously, the area can produce a three-dimensional design with texture in the direction in which the lattice pitch changes and the direction in which the lattice angle changes, and an unprecedented gradation An effect can be obtained.
2) Also, as in the second aspect, in the first aspect, in the region where both the grating pitch and the grating angle of the diffraction grating continuously change, the direction in which the grating angle of the diffraction grating continuously changes is By defining the normal direction as the direction in which the grating pitch of the diffraction grating continuously changes is defined in the circumferential direction, a gradation effect is generated both in the circumferential direction and in the central direction in the sector area. In addition, it is possible to obtain a light diffraction structure having visibility as if light flows toward the center of the circle.
3) Further, as in the third aspect, in either of the first and second aspects, the diffraction grating pitch is set to 2.0 μm when the grating pitch of the diffraction grating is in the range of 0.4 to 5.0 μm. The above-described region has a reduced ratio of diffraction and appears to absorb light. For example, when the pitch of the diffraction grating is continuously changed in the second mode, a pitch of 2.0 μm or more is used. By doing so, it is possible to obtain an optical diffraction structure as if light is sucked toward a region having a grating pitch of 2.0 μm or more.

Hereinafter, the optical diffraction structure of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining the optical diffraction structure of the present invention, FIG. 2 is a diagram for explaining gradations when the grating pitch is continuously changed, and FIG. 3 is a diagram showing grating angles continuously. FIG. 4 is a diagram for explaining an example of a conventional light diffraction structure, and FIG. 5 is a diagram for explaining an example of the light diffraction structure of the present invention. Fig.

As the hologram, a relief hologram of a three-dimensional image expressed by interference fringes due to interference of light between the object light and the reference light, and a diffraction grating based on a two-dimensional image are often used.
As a means for improving design and as a means for preventing forgery, there are many rainbow holograms and color holograms that are white light reproduction holograms, and synthetic holograms produced by combining these holograms with characters, figures, symbols, etc. used.

The use form of the hologram is roughly classified into a case where it is used in a state where it is transferred onto a substrate and a case where it is used after being labeled on a state where it is formed on the substrate.
When the hologram is used in a transferred state, a release layer is formed on a heat-resistant base film, and, for example, a thermosetting resin layer is formed thereon, and the thermosetting resin layer is formed. An uneven structure is formed, a reflective layer is formed, a heat-sensitive adhesive layer is formed thereon to form a transfer film, and an extremely thin hologram layer including the adhesive layer is formed by a heated metal mold or the like. It is used by transferring onto printed matter such as paper.
When using the hologram in a label state, a thermosetting resin layer is formed on the base film, an uneven structure is formed on the thermosetting resin layer, and a reflective layer is formed on the uneven structure, An adhesive layer is formed on the surface, the adhesive surface is covered with release paper, the base film is punched into a predetermined size together with the release paper to form a label, and the release paper is peeled off and attached to the object. use.

The reflection layer of the hologram is provided to give reflectivity to the uneven surface of the hologram forming layer.
The reflective layer includes an opaque reflective layer and a transparent reflective layer, but when used as a means for enhancing the design effect, an opaque reflective layer made of metal such as aluminum or nickel is formed.
As a method for forming the reflective layer, there are a vacuum vapor deposition method, a sputtering method, an ion plating method, and the like, which are properly used depending on the purpose.
In addition, as a means for forming a release layer, a thermosetting resin layer, an adhesive layer, an adhesive layer, etc., a general coating method such as gravure coating, die coating, knife coating, roll coating, etc., and a printing method such as silk screen Select from and use.

The light diffraction structure of the present invention will be described with reference to FIG.
In FIG. 1a, the optical diffraction structure of the present invention has a vertical axis representing the degree of continuous change in grating pitch and a horizontal axis representing the degree of continuous change in grating angle (hereinafter referred to as brightness). In the case where the vertical axis and the horizontal axis are changed at the same time, the region becomes brighter toward the lower left and darker toward the upper right.
As a result, the rectangular area composed of a plurality of square cells shown in FIG. A is continuous brightness from the lower left to the upper right (in practice, an area in which a predetermined number of cells having the same lattice pitch are embedded). Strictly speaking, it is partly staircase because it is continuous, but in the following description, it is expressed as “continuous”.) This is a region having gradation.

In FIG. 1, a continuously changing rectangular area is a locus area formed as a result of the vertical axis having continuous gradations being rotated 90 ° rightward toward the horizontal axis.
That is, the rectangular region has a predetermined width, and a band having a predetermined shape continuously changing from a lattice pitch of 1.4 μm to 0.8 μm starts from a lattice angle of 45 °, with the lower left corner as an axis. This is a region formed as a result of rotating while changing the lattice angle and setting the lattice angle to be 135 ° at the portion reaching the horizontal axis.
In other words, the rectangular region is a locus region in which the grating pitch of the diffraction grating continuously changes in the normal direction of the above-described band when the grating angle of the diffraction grating changes in the circumferential direction when rotated to the right. Can do.

FIG. 1b is an enlarged view of a part of the cell 10 in FIG. 1, and the cell is composed of a plurality of dots 100 formed with a predetermined lattice angle α and a predetermined lattice pitch P. FIG.
Here, the smaller the grid angle α (number), the brighter the brightness, and the larger the grid pitch P (number), the brighter.
As for the value of the grating pitch, when a circle is formed by continuously changing the grating angle, a smooth gradation can be obtained by setting the grating pitch of the diffraction grating within the range of 0.4 to 5.0 μm. This has been confirmed experimentally.
In particular, in the region where the diffraction grating pitch is 2.0 μm or more, the ratio of reflecting and diffracting incident light is reduced, and it seems as if light is absorbed.
As a result, if a pitch of 2.0 μm or more is used when continuously changing the pitch of the diffraction grating, it is as if light is sucked toward the region of the grating pitch of 2.0 μm or more. An optical diffraction structure having a gradation effect is obtained.

With reference to FIG. 2, the gradation when the lattice pitch is continuously changed will be described.
When the grating density and the grating angle of the dots forming the diffraction grating are made constant and the grating pitch is continuously changed, FIG. 2 is obtained.
The bright region of the optical diffraction structure 1c is formed by a diffraction grating having a grating pitch close to 1.4 μm, and the dark region is formed by a diffraction grating having a grating pitch close to 0.8 μm.

With reference to FIG. 3, the gradation when the lattice angle is continuously changed will be described.
When the grating density and the grating pitch of the dots forming the diffraction grating are made constant and the grating angle is continuously changed, the result is as shown in FIG.
The bright region of the optical diffraction structure 1d is formed by a diffraction grating having a grating angle close to 45 °, and the dark region is formed by a diffraction grating having a grating angle close to 135 °.

An example of a conventional light diffraction structure will be described with reference to FIG.
As shown in the figure, a gradation pattern is created by fixing only the remaining elements and fixing the grating density, grating pitch, and grating angle of the dots constituting the diffraction grating described in FIGS. Become.
If the light diffractive structure 2 is composed of a background pattern with shading and a foreground design with shading is also superimposed in front of it, a three-dimensional design can be expressed, but the entire design becomes static. It is difficult to express a feeling of movement.

An example of the light diffraction structure of the present invention will be described with reference to FIG.
In the example of the optical diffraction structure 3 shown in FIG. 5, the grating density of the dots constituting the diffraction grating, the grating pitch, and the grating angle are fixed, and the remaining elements, the grating pitch and the grating angle, are changed. Is a depiction of a square.
In the example of the optical diffraction structure 3, the grating pitch outside the circle inscribed in the square is set to 1 μm or less, for example, the grating pitch is widened toward the inside of the inscribed circle, and the grating pitch near the center is set to 3. This is an example of 5 μm.
Although it is possible to form a set of four cells as illustrated in FIG. 1a, the cells at the same distance from the center of the square are formed with a common lattice pitch and different lattice angles. You can also.

With reference to FIG. 5c and Table 1, the above contents will be described in detail.
In a region where the grating pitch and the grating angle change continuously at the same time, the direction in which the grating angle of the diffraction grating changes continuously is defined as the outer circumferential direction, and the direction in which the grating pitch of the diffraction grating changes continuously from the outer circumference. By defining in the direction toward the center, a gradation effect is generated in the sector-shaped region in the direction toward the center, and an optical diffraction structure in which light flows into the center of the circle is obtained.
In FIG. c, as shown in Table 1, a diffraction grating of a cell with coordinates “A1” on a line segment orthogonal to the upper side of the square from the center of the square is created with a grating angle of 90 degrees and a grating pitch of 1.7 μm. . Then, the cells “A2”, “A3”, “A4”, “A5”, “A6”, “A7”, “A8” on the circumference existing at the coordinates “A1” from the center of the square are A cell in which the lattice angle is continuously changed at a lattice pitch of 1.7 μm (common) is used.
Similarly, the cells “B2”, “B3”, “B4”, “B5”, “B6”, “B7”, “B8” on the circumference existing at the coordinates “B1” from the center of the square. , A cell in which the lattice angle is continuously changed at a lattice pitch of 2.5 μm (common).
The coordinates “A1”, “A2”, “A3”, “A4”, “A5”, “A6”, “A7”, “A8”, and “B1”, “B2”, “B3”, “ The lattice angles of the cells “B4”, “B5”, “B6”, “B7”, and “B8” are changed as shown in the table.
By the way, “A1”, “B1”, “A5”, “B5” are the coordinates on the line segment that bisects the square vertically, “A3”, “B3”, “A7”, “B7” are horizontal The coordinates on the bisecting line segment, “A2”, “B2”, “A6”, “B6”, and “A4”, “B4”, “A8”, “B8” are the coordinates on the diagonal of the square is there.

According to the prototype data, in the region where the diffraction grating pitch is 2.0 μm or more, the ratio of reflecting and diffracting incident light decreases, and it seems as if light is absorbed.
As a result, when the pitch of the diffraction grating is continuously changed, if the pitch of the grating is set to 2.0 μm or more, it is as if light is sucked into a region having a grating pitch of 2.0 μm or more. In addition, a light diffraction structure having a gradation effect can be obtained.

For special printed materials, there are fields where high-priced product packaging materials, pamphlets, POPs, book covers and the like are used.
For prevention of counterfeiting, for example, there are fields that are used by attaching to cards such as credit cards and ID cards, gift certificates, checks, bills, stock certificates, admission tickets, and various certificates.

It is a figure for demonstrating the light diffraction structure of this invention. It is a figure for demonstrating the gradation at the time of changing a lattice pitch continuously. It is a figure for demonstrating the gradation at the time of changing a lattice angle continuously. It is a figure for demonstrating an example of the conventional light diffraction structure. It is a figure for demonstrating an example of the light diffraction structure of this invention.

Explanation of symbols

1, 1c, 1d Light diffraction structure 2 Example of conventional light diffraction structure 3 Example of light diffraction structure of the present invention 10 Cell 21 Background design 22 Foreground design 100 dots P Grid pitch α Grid angle

Claims (3)

A light diffraction structure formed by a set of diffraction gratings,
The optical diffraction structure figure which has the area | region where the grating | lattice pitch and grating | lattice angle of a diffraction grating change simultaneously and continuously in at least one part of the aggregate | assembly of a diffraction grating. In the light diffraction structure according to claim 1,
In the region where both the grating pitch and the grating angle of the diffraction grating continuously change, the direction in which the grating angle of the diffraction grating continuously changes is defined as the circumferential direction, and the grating pitch of the diffraction grating changes continuously. The light diffraction structure figure characterized by the direction being defined by the normal direction. The optical diffraction structure according to any one of claims 1 and 2, wherein the grating pitch of the diffraction grating is in the range of 0.4 to 5.0 µm.

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