JPS6234783Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to counterfeit-proof printed matter, and more specifically, the invention relates to counterfeit-proof printed matter, and more specifically, securities, etc. whose authenticity can be easily determined visually by recognizing the pattern of diffracted light by applying laser light or white light. Regarding anti-counterfeit printed matter.

Advances in photographic technology and the spread of color copying machines have created a social environment in which it is extremely easy to forge securities. On the other hand, with conventional printing technology, originality is maintained by simply printing ink on paper and adding complex patterns and markings, but with the spread of copying machines mentioned above, it has become extremely difficult to maintain originality. Counterfeit products with high similarities are being made,
Anti-counterfeiting has become a strong requirement in the banking, securities, and other fields.

As a result of various studies to effectively prevent counterfeiting, the inventors of the present invention have found that by using a transmission diffraction grating in a part of printed matter, counterfeiting using general photographic methods or color copying machines can be easily prevented. We discovered that this could be done and came up with this idea.

That is, the present invention is an anti-counterfeit printed material having a transmission type diffraction grating having two or more portions with different pitches on the same side in an opening provided in a part of a printed base sheet.

Hereinafter, the above-mentioned present invention will be explained in detail.

FIG. 1 is a plan view schematically showing an example of the anti-counterfeit printed matter of the present invention in the case of securities;
The security has a configuration in which a transmission type diffraction grating 3 is provided in an opening provided in a part of a base sheet (in this case, paper) 2 on which a printed portion 1 is provided.

In the above, various types of paper or plastic sheets are used as the base sheet, and ordinary printing methods such as gravure, offset, letterpress, etc. are used to print on the base sheet.

The transmission type diffraction grating used in the above invention is
For example, it is manufactured as follows.

First, as shown in the second figure, on a photoresist layer 5 with a thickness of about 0.5 to 2μ provided on one surface of a substrate 4, a laser beam 6 divided into two beams is made to interfere with each other, and a diffraction grating is formed in the photoresist layer 5. form a latent image. Next, by developing, a prototype diffraction grating 8 having a photoresist interference fringe pattern 7 is created on the substrate 4 as shown in the third figure. still,
Regarding the interference fringe pattern and the shape of the interference fringe above,
The number of interference fringes and the intersection angle may be determined arbitrarily, but
Preferably, interference fringes are created by rotating the dry plate at equal angles and sequentially exposing the plate to light. Also, any pitch can be applied to the interference fringes, but
It is particularly desirable to set the thickness to about 0.5 to 4 μm because visual discrimination becomes easy.

Next, as shown in FIG. 4, a metal thin film layer 9 is provided on the surface of the original diffraction grating 8 having the interference fringe pattern 7. This thin film layer 9 is provided to serve as an electrode when plating the embossing metal, and can be made of, for example, a gold vapor deposited layer. This layer is preferably thin, and is used at a thickness of 0.5 μm or less. A metal plating layer 10 having a thickness of about 50 to 100 microns is provided on the thin film layer 9. As the metal plating material, nickel or the like is preferably used from the viewpoint of strength, embossing reproducibility, quality stability, etc.

Next, the metal plating layer 10 is replaced with a metal thin film layer 9.
As shown in FIG. 5, a metal plating layer 10 having a metal thin film layer 9 on the surface is used as the original A, and a transparent thermoplastic plastic sheet or plate 11 is stacked on the uneven surface of the original plate so as to face each other. For example, if the original plate A is heated under the conditions of 150 to 200°C, 5 to 50 kg/cm ² , and 60 to 180 seconds, and then the original A is removed, the interference fringe pattern is the same as that recorded on the photoresist. A transmission type diffraction grating 12 having the following is created. The transmission grating thus obtained exhibits a hardening that diffracts transmitted light without impairing the transparency of the plastic sheet or plate.

Further, in the above, the metal thin film layer 9 shown in FIG.
An original plate A consisting of a metal plating layer 10 having on the surface
A metal such as nickel is plated on the metal thin film layer 9, and this metal plating layer is peeled off to once create a reverse original plate B consisting of a metal plating layer having an uneven surface opposite to that of the original plate A. Then, the uneven surface of the reverse master B is naturally oxidized, a metal oxide layer is provided by anodizing or chromate treatment, and then a metal such as nickel is plated again on the metal oxide layer to form a metal oxide layer. If the plating layer is peeled off from the metal oxide layer and an original C having the same uneven surface as the original A is created, the original C does not have a metal thin film layer on its surface, so its durability is significantly improved compared to the original. . Moreover, if you create many reverse originals B from original A and arrange them in succession to create original C, original C can be made several times the size of original A. Since a large transmission type diffraction grating can be obtained, it is extremely effective for mass production. Furthermore, in this case, there is an advantage that by storing the above-mentioned reverse master B, it is possible to create the master C and a transmission diffraction grating at a desired time.

In the present invention, various methods can be used to attach the transmission diffraction grating to the opening of the base sheet, such as attaching with an adhesive or thermal lamination. Note that the number of openings in the present invention is not limited to one location, but may be provided in two or more locations.

In the present invention, as shown in FIG. 7, a plurality of transmission diffraction gratings 12A, 12B,
12C arranged in a planar direction and integrated (hereinafter referred to as composite diffraction grating 13) is attached to the opening. Further, in this composite diffraction grating, each transmission type diffraction grating can be formed discontinuously in a plane with a thermoplastic film 14 interposed therebetween, as shown in FIG. In this way, a composite diffraction grating can be created by arbitrarily combining two or more different types of transmission diffraction gratings on one plane. To create the composite diffraction grating, the method for manufacturing a transmission type diffraction grating described above can be applied.

When a laser beam is applied to the printed matter of this invention, diffracted light corresponding to each pitch is generated. Using the position and pattern of this diffracted light as a signal,
By associating numbers or letters, information that cannot be reproduced by a copying machine can be recorded on the transmission diffraction grating.

When a laser beam is applied to a diffraction grating, the transmitted light exhibits a diffraction development, forming a certain pattern corresponding to the pitch of the diffraction grating. 0 of transmitted diffracted light
The second diffraction light refers to the incident laser light that is not diffracted and passes through as it is. The diffraction angle of the first-order diffracted light is determined by the pitch of the diffraction grating. 0
The angle θ between the second diffracted light and the first diffracted light is inversely proportional to the pitch d of the diffraction grating, and is expressed as sin=λ/d. Here, λ is the wavelength of light. Using this principle, the pitches of the diffraction gratings 12A, 12B, and 12C shown in FIG. 7 or 8 can be adjusted respectively.
If dA, dB, dC (dA>dB>dC), the angles θ of the first-order diffracted light corresponding to these are θA, θ
B, θC (θA<θB<θC), and the difference in pitch of the diffraction grating can be converted into two-dimensional coordinates on a plane. By arranging photo sensors on this plane, the diffracted light can be read optically.
The pitch of the diffraction grating can be made to correspond one-to-one to numbers or letters. In this way, the code can be mechanically read in addition to visual discrimination, and authenticity can be determined more accurately.

In the present invention, the diffraction angle of light can be limited by narrowing the pitch within the above-mentioned desirable pitch range. The pitch is 1
It is preferably less than μ, more preferably about 0.5μ. For example, when the pitch is 0.5 μ, even if the light is incident on the diffraction grating surface at maximum θ = 36° 51', the permissible range for washing the diffraction grating surface with water is only θ ₀ = ±1° 23' ( (See Figure 9). In particular, if a diffraction grating produced under such conditions is attached to an opening provided in a part of a printed matter, it is effective in preventing counterfeiting because it can only be viewed from a certain angle. Furthermore, for example, it is very preferable to form a pattern 15 on the thermoplastic film 14 using a diffraction grating with such a narrow pitch as shown in FIG. 10, since the pattern 15 will appear iridescent. In this case, the non-patterned portion can be formed with a diffraction grating having a different pitch from the diffraction grating constituting the pattern 15 to form a composite diffraction grating.

The anti-counterfeit printed matter of the present invention has a white light source, reflected or transmitted light such as sunlight, which appears to be dispersed in rainbow colors,
The visible rainbow-colored diffracted light sways or remains stationary with respect to the movement of the base sheet surface. However, when trying to copy anti-counterfeit printed matter with a transmission type diffraction grating installed using a copying machine, it is possible to record on the normal base sheet surface, but not on the area where the transmission type diffraction grating is, and no diffraction grating is generated. . In this way, it is possible to easily determine authenticity.

In this way, in this invention, by using a transmission type diffraction grating in a part of printed matter such as securities,
A part of the image that cannot be copied by a copying machine is created, and the genuine article can be distinguished from the original by the fact that it appears rainbow-colored due to the light diffraction effect of the diffraction grating. Furthermore, by applying a laser beam, it is possible to detect information other than the printed information, which has the advantage of making it possible to determine authenticity. Therefore, the present invention is particularly effective in preventing counterfeiting of securities and cash vouchers.

Next, a manufacturing example of a transmission type diffraction grating used in the present invention will be specifically explained.

First, an azide-based photoresist (manufactured by Shipley, AZ-1350J) was spinner-coated on the cleaned glass, and then prebaked at 90°C for 30 minutes.
The thickness of the resist film was approximately 2 μm. Interference fringes were recorded on this photoresist dry plate by two-beam interference method using a wavelength of 488 nm of an argon laser. Exposure conditions are output
The exposure time was 450 mW and 10 minutes. Next, this dry plate was rotated 90 degrees and interference fringes were produced again under the above exposure conditions. In this way, a prototype diffraction grating in which interference fringes intersect at right angles was fabricated. In addition, a positive film was used for patterning. In this case, only the character portion of the diffraction grating becomes a diffraction grating. Exposure conditions are 3KW light source
It took 10 to 20 seconds with a UV printer using an ultra-high pressure mercury lamp 75 cm away from the original. In addition, development is AZ-
This was carried out for about 10 seconds using a 1:4 mixture of 303A developer and water. The period of the diffraction grating of the photoresist was approximately 2 μ, and the intersection angle of the two incident laser beams in this case was 7°.

Gold was deposited on the interference fringes on the photoresist thus produced. The amount of gold deposited is about 0.1 to 0.5μ. This metal-deposited dry plate is placed in a nickel sulfamate solution, and this dry plate is connected to the negative electrode.
Electric field nickel plating was applied using a high-purity nickel plate as the positive electrode. I put on a nickel. Nickel plating was carried out at a speed of 1 μ/min, and a thickness of 60 μ was obtained. Next, the plated dry plate was immersed in an acetone solution, and the photoresist was peeled off from the nickel plate. On the nickel plated surface, a diffraction grating surface was formed in which the phase of the pitch of the original resist was shifted by π. Using this nickel plate as an original plate, it was pressed onto a polyvinyl chloride sheet using a press machine. Press pressure is 10Kg/cm ² , heating temperature is 180-190
℃, pressing time was 1 to 2 minutes, and interference fringes were transferred onto a 0.3 mm polyvinyl chloride sheet to produce a transmission type diffraction grating.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing an example of the anti-counterfeit printed matter of the present invention in the case of securities, and FIGS. 2 to 6 are examples of a method for manufacturing a transmission diffraction grating to be attached to the anti-counterfeit printed matter of the present invention. FIG. 7, FIG. 8, and FIG. 10 are plan views showing modified examples of the transmission type diffraction grating, and FIG. 9 shows the incident light and viewing angle in a preferred example of the transmission type diffraction grating. FIG. 1...Printing section, 2...Base sheet, 3...Transmission type diffraction grating.

Claims (1)

[Claims for Utility Model Registration] (1) An anti-counterfeiting printed matter having a transmission diffraction grating having two or more portions with different pitches on the same side in an opening provided in a part of a printed base sheet. (2) The anti-counterfeit printed matter according to claim 1, wherein the transmission diffraction grating has a pitch of 0.5 to 1μ. (3) The anti-counterfeiting printed matter according to claim 2 of the utility model registration claim, in which a transmission diffraction grating is patterned.