JPS6311671B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document copy prevention tape that is pasted onto a document whose copying is to be prohibited to prevent its copying.

Generally, some means must be taken to prevent top secret documents and other important documents from being copied. Conventionally, caution marks were printed with a fluorescent material that was invisible to the naked eye but could be sensed by the spectral sensitivity of the photoreceptor, and the caution marks were displayed as a visible image when copied, or an electrostatic copying device was used to print the caution marks on the original. There are some products that have a colored light-absorbing part that absorbs the exposure light of Copying machines are effective, but they do not completely prevent copying because they are exposed to light that cannot be absorbed.

In view of the above, the present invention provides a tape for preventing copying of manuscripts that can be easily made into manuscripts that cannot be copied by Carlson type copying machines, which are currently available in large quantities, and that can be read with the naked eye. The purpose is to provide

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, copy prevention tape 1 of the present invention is shown.
is wound around a suitable core 2, and when used, it is pulled out a required length and affixed to the original to prevent copying.

The anti-copying tape 1 is formed by stacking a plurality of layers, and as shown in FIG. 2, a release sheet 3 is formed on the lowest layer in the figure, and this release sheet 3 is made of silicone resin or fluororesin. Become,
During use, this release sheet 3 is peeled off.

A first transparent adhesive layer 4 is attached on the release sheet 3, and the first transparent adhesive layer 4 is made of vinyl acetate, acrylic, or silicone.
The thickness of this adhesive layer is 20 to 30 μm, and the adhesive layer 4 is attached to the document. Said first transparent adhesive layer 4
A transparent base 5 is formed on top, and the transparent base 5 is made of cellophane or polyester film and preferably has a thickness of about 50 μm.

A second transparent adhesive layer 7 for fixing the glass bead layer 6 is formed on the transparent base 5,
This adhesive layer 7 consists of epoxy resin, vinyl acetate, ceramic or isocyanate.
The glass beads b of the glass bead layer 6 have an average spherical diameter of 60μ and a curvature of 1.9 or more, and the second
The larger the difference between the refractive index of the transparent adhesive layer and that of the glass beads, the better, and the closer to 1.0, the more desirable.

The lower half of the glass beads is covered with a semi-transparent reflective film 8 made of a thin metal such as aluminum, and after coating the entire surface of the semi-transparent reflective film 8, the glass beads are attached to the second transparent adhesive layer 7. After drying, the upper half of the film is wiped off with a dilute NaOH solution.

In addition, a thermoplastic transparent resin film is provided on the glass bead layer 6 to more firmly fix the glass beads b, and this thermoplastic transparent resin film is formed of an acrylic resin, and its thickness is set to 10 μm or less. After applying this tape to a manuscript whose copying is prohibited, it may be heated with a hair dryer to fully blend it into the spherical surface of the glass beads.

Further, in this embodiment, the first transparent adhesive layer 4, the transparent base 5, and the second transparent adhesive layer 6 are laminated on the release sheet 3, but the transparent adhesive layer 4 is not formed separately. It is also possible to form a single layer of the same material.

Next, the effect will be explained.

First, the principle will be explained. In Figure 3, when light parallel to the optical axis of the sphere enters glass bead b from point P and is reflected at point R on the back surface of the sphere, and the incident light and reflected light become parallel, the angle of incidence is θ. ₁ , the angle of refraction is θ ₂ , the refractive index of air is n ₁ and the refractive index of the sphere is n ₂ , since the incident point P and the reflection point R are on the surface of the sphere, n ₂ /n ₁ = sinθ ₁ /sinθ The relationship ₂ = 2・cosθ ₂ exists.

Here, the refractive index of air is about 1.0, so n ₂
If the relationship of =2·cosθ ₂ is satisfied, the reflected light and the incident light become parallel.

Now, if n ₂ = 1.9, θ ₂ will be approximately 18° and θ ₁ will be 36°. That is, among the light beams entering the sphere, all the light beams having an incident angle within the range of 0 to 38 degrees are reflected from the back surface of the sphere and become reflected light parallel to the incident light.

The semitransparent reflective film 8 is attached to the hemispherical surface of the glass beads, and the reason why this is semitransparent is that when the tape is pasted on the original, the original pattern can be read with the naked eye. This is because there is also a need to ensure reflection of incident light.
Note that even if the reflectance is set to 50 to 80%, there is no problem in reading the pattern on the document with the naked eye.

Figure 4 shows the optical system of a normal copying machine.
An original 12 on which a pattern 11 is drawn is placed on a contact glass 10. This pattern 11 is irradiated with two light sources 13 and 14, and the reflected light of the pattern A is reflected by the reflecting mirrors 15 and 16 and the imaging lens 1.
The image is formed as A ₁ on the surface of the photosensitive drum 18 via the photosensitive drum 7 . In this case, the reflected light from the patterned surface of the original 12 is scattered reflected light, and reflected light 19 also occurs on the surface of the contact glass 10.
The optical system of the copying machine is designed to form an image on the photosensitive drum 18 using only the effective light beam.

However, in the present invention, as shown in FIG. 5, the light beams from the light sources 13 and 14 are not completely diffusely reflected due to the action of the glass beads covering the original 12, but return to the original irradiation direction again, resulting in an effective light beam. Does not occur. Therefore, a normal copying machine cannot make copies.

In this way, by pasting a tape with a layer of glass beads on the entire surface or a part of a confidential document, it is possible to completely prevent the creation of copies, and there is no problem in directly viewing the confidential document with the naked eye, and when in use, It is very easy to use because it only needs to be cut to an appropriate length, and its manufacture is simple and inexpensive.

The transparent adhesive layer used in this tape may be the one used in commercial cellophane tape.

Since the present invention is constructed as described above, by cutting it to an appropriate length and pasting it on the copy-preventing part when in use, it is possible to easily prevent copying without hindering the reading of the manuscript with the naked eye, and also to protect the surface of important documents. It also has the effect of providing protection.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the anti-copying tape according to the present invention, FIG. 2 is a vertical sectional view of the anti-copying tape, and FIG.
4 is a diagram illustrating the principle of the present invention, FIG. 4 is a diagram illustrating the configuration of an optical system of a conventional copying machine, and FIG. 5 is a diagram illustrating the operation of the present invention. 1... Copy prevention tape, 3... Release sheet, 4...
First transparent adhesive layer, 5... Transparent base, 6... Glass bead layer, 7... Second transparent adhesive layer, 8... Translucent reflective film, 10... Contact glass, 13, 14... Light source.

Claims (1)

[Claims] 1. A glass bead layer consisting of countless glass beads that reflects incident light from the light source of a copying machine and returns to the direction of the incident light, and a glass bead layer supported on one side and a glass bead layer on the opposite side of the glass bead layer. the glass beads have a refractive index of 1.9 or more and an average spherical diameter of 60μ;
A tape for preventing copying of originals, which is characterized by: