JPH0820158A - Recording medium and data recording method - Google Patents

Abstract

PURPOSE:To prevent an unjust act while making imitation or forgery hard to perform, in a recording medium wherein a recording layer capable of reading optical data from reflection density and transmission density is provided on a base material, by forming the recording layer by irregularly arranging a plurality of units stepwise changed in density with predetermined density difference. CONSTITUTION:A recording medium such as a ticket, a pass, a credic card or a prepaid card is obtained by forming a reflection layer 20 reflecting incident light, a recording layer 30 having optical data, a concealing layer 40 and a protective layer 50 on a base material. For example, infrared rays are absorbed into the recording layer 30 as incident light and reflected by the reflection layer 20 to be again absorbed into the recording layer 30 and reflection density is detected from the quantity of reflected light to perform the reading of data. In this case, the recording layer 30 is formed by irregularly arranging a plurality of units stepwise changed in density with predetermined density difference. By this constitution, a plurality of the units are confirmed as different patterns to make the presence of data hard to remember.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium and an information recording method in which it is difficult to forge information.

[0002]

2. Description of the Related Art Among cards used for boarding tickets, commuter passes, credit cards, prepaid cards, etc., information is read by utilizing reflection or absorption of incident light. I have a card. For example,
The bar code shown in FIG. 5 in which several bars made of ink that reflects or absorbs infrared rays are arranged is used. The bar code is read by a detection device that is a combination of a light source, an optical filter, a light receiver, etc., and the authenticity of the card is determined, and further information is read.

However, since the detecting device combined with each other can easily obtain each part and read out information easily, counterfeiting such as imitation or alteration is easy and fraud is occurring. .

Therefore, it is an object of the present invention to provide a recording medium and an information recording method capable of preventing imitation and forgery because it is difficult to recognize that information is included.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording medium having a recording layer capable of reading optical information from the reflection density or the transmission density on a base material, wherein the recording layers have a stepwise difference in density. The recording medium is characterized by arranging a plurality of units changing in a random manner. It is preferable that the plurality of units have irregular shapes. A different aspect of the present invention is an information recording method for recording information by changing the density of reflected light or transmitted light, wherein the information has a plurality of units whose density changes stepwise with a predetermined density difference, and is arranged irregularly. Moreover, the information recording method is characterized in that the shapes of the plurality of units are irregular.

The predetermined density difference referred to in the present invention means a minimum density difference which can be detected by a detecting device for reading optical information. The irregular shape of the plurality of units means that the shape of each unit is not a fixed shape, for example, a boundary line is a curve, and the curve has a different shape for each boundary.

[0007]

According to the recording medium and the information recording method of the present invention, since the information is irregularly composed of an array of units having different densities, it looks like a simple pattern. Also, if the unit is not a fixed form, it looks more like a pattern and it is hard to recall that information is included.

[0008]

EXAMPLES Examples will be described below, but the present invention is not limited thereto. FIG. 1 is a sectional view showing an example of a recording medium used in the present invention. FIG. 2 shows a plurality of units formed in the recording layer shown in FIG. FIG. 3 shows an example of a recording layer different from that of FIG. FIG. 4 shows a signal obtained from the recording layer shown in FIG. FIG. 5 shows a conventionally used bar code.

In the embodiment shown in FIG. 1, a reflective layer 20 for reflecting incident light on a substrate 10, a recording layer 30 having optical information,
The concealing layer 40 and the protective layer 50 are formed. Reflective layer 20
For example, a metal can be formed by a vapor deposition method or a sputtering method, or an ink or the like obtained by dispersing a pigment having a high reflectance with respect to incident light in a binder can be formed by coating. Alternatively, the ink layer may be transferred and formed.

The recording layer 30 may be coated with a dye that absorbs incident light, or may be coated with a dispersion of the dye in a resin or a pigment in a binder. The hiding layer 40 was coated with an ink composed of a black dye, a color developer, and an infrared transmissive dye. The protective layer 50 is formed by applying a UV curable acrylic resin or the like.

In reading information, for example, infrared rays emitted as incident light are absorbed by the recording layer 30, further reflected by the reflective layer 20 to be reflected light, and then absorbed again by the recording layer 30. The reflection density is detected from the obtained amount of reflected light. The hiding layer 40 absorbs visible light and transmits infrared light, and hides the recording layer 30 from visible light.

FIG. 2 shows an example in which a plurality of units provided in the recording layer 30 are formed by units having different densities from light white to dark black. The unit shape is a rectangle. Recording layer 3
The units formed at 0 appear to be just a pattern. On the other hand, the conventional bar code shown in FIG. 5 is composed of two types of units in which a plurality of bars made of reflective or absorbing ink are arranged.
The composition is simple and it is easy to remember that information is included.

FIG. 3 uses a circle as a method of indicating the density of a unit, and since the boundary line between adjacent units is a curve and the unit shape is irregular, a plurality of units formed on the recording layer are It looks like a simple pattern, and it is hard to recall the existence of information.
It is more difficult to recall the existence of information if the boundaries that do not adjoin are also curved.

FIG. 4 is a waveform of a signal obtained from the recording layer shown in FIG. 3 when the diameters of the incident and reflection optical systems are substantially equal to the unit width. The vertical axis represents a value obtained by normalizing the density, and the horizontal axis represents the scanning position when the optical system scans in the arrow direction shown in FIG. If the diameter of the optical system is almost equal to the unit width, a signal with a peak is obtained as shown in FIG.
The signal can be contrasted, and reading errors are less likely to occur.

As a method of indicating the density of a unit, it may be divided from light white to dark black in several steps to several tens of steps depending on the resolution of the reading sensor, and may be divided into dots, line segments, cross marks, characters, It is also possible to indicate the shading by using symbols or the like.
Also, the color tone may be changed.

[0016]

As described above, since the recording medium and the information recording method of the present invention use the recording method capable of preventing imitation and forgery, fraud is unlikely to occur.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a recording medium used in the present invention.

FIG. 2 is a diagram showing a configuration of units included in the recording layer shown in FIG.

FIG. 3 is a diagram showing a configuration of a unit different from that in FIG.

FIG. 4 is a diagram showing a signal obtained from the recording layer shown in FIG.

FIG. 5: Conventionally used bar code.

[Explanation of symbols]

 10 Base Material 20 Reflective Layer 30 Recording Layer 40 Concealing Layer 50 Protective Layer

Claims (3)

[Claims] 1. A recording medium having a recording layer capable of reading optical information from a reflection density or a transmission density on a substrate, wherein the recording layer does not include a plurality of units whose density changes stepwise with a predetermined density difference. A recording medium characterized by being arranged in a regular manner. 2. The recording medium according to claim 1, wherein the shapes of the plurality of units are irregular. 3. An information recording method for recording information by changing the density of reflected light or transmitted light, wherein the information has a plurality of units whose density changes stepwise with a predetermined density difference and which is irregularly arranged. An information recording method, wherein the plurality of units have irregular shapes.