JPH0757065A - Invisible information recording body - Google Patents

Abstract

PURPOSE:To prevent the contrast of an invisible information recording layer which becomes visible by fluorescence light from substantially decreasing and also prevent a base print pattern from overlapping with invisible information by providing the invisible information recording layer and an optical modulation layer. CONSTITUTION:On the top surface of a photochromic layer 24 which functions as the optical modulating layer, a bar code is printed as the invisible information recording layer in ink which is invisible with visible light and becomes visible by fluorescence by being irradiated with light of specific wavelength like ultraviolet rays to form a stealth bar code layer 26. The layer 26 fluoresces, the contrast between the bars and spaces of the stealth bar code which becomes visible does not decrease under the influence of VR2 traveling to the layer 24 below the layer 26 in the visible light generated by the fluorescence of the layer 26, and the base print pattern does not overlap, so a bar code reader can securely read bar code information out of the stealth bar code which is visible by the fluorescence of the layer 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an invisible information recording body provided with an invisible information recording layer which is invisible under visible light and is fluorescent and visible when irradiated with light of a predetermined wavelength. Regarding

[0002]

2. Description of the Related Art Such an invisible information recording medium is known as, for example, an invisible barcode (hereinafter referred to as stealth barcode). In recent years, bar code-based product management has become popular, and it has been widely recognized that the speed, accuracy, and convenience of inputting information using bar codes are widely recognized. As a result, it has come to be used in many fields, and in some fields it is not possible to secure a specific space to print only the barcode on the underlayer, and the barcode cannot be printed on the underlayer. There are demands such as wanting to print it on top of it, or not wanting to print a part of the existing print from an aesthetic point of view. In order to meet this requirement, a stealth barcode has been proposed which is invisible under visible light and becomes fluorescent and visible when irradiated with light of a predetermined wavelength.

For example, a stealth bar code is formed by printing with an ink containing a fluorescent substance which is invisible under visible light but is excited when irradiated with ultraviolet rays to emit visible light to be visible. Can be done.

[0004]

However, the stealth bar code based on such an ultraviolet excitation system has the following drawbacks. In a conventional information recording medium on which a stealth barcode is printed, as shown in the sectional structure of FIG. 5, underprinting in which patterns such as letters, numbers and pictures are printed on the underlayer 10 made of paper, for example. There is a layer 12, and the base printing layer 12
A stealth bar code layer 14 is printed on top of the.

The stealth barcode layer 14 is invisible under visible light, but is formed by printing with an ink containing a fluorescent substance that is excited when irradiated with ultraviolet rays and emits visible light to be visible. Therefore, when irradiated with ultraviolet UV, it fluoresces to emit visible light, and the visible light VR1 goes upward, and the VR1 makes the stealth barcode formed by the stealth barcode layer 14 visible. .

[0006]

However, since visible light due to fluorescence from the stealth barcode layer 14 travels in all directions, the visible light VR2 that is directed below the stealth barcode layer 14 is the underprinting layer. 12
The reflected light VR3 'is reflected by and the pattern such as letters, numbers and pictures of the undercoat printing layer 12 is overlapped with the stealth barcode which is visible by the fluorescence of the stealth barcode layer 14.

As a result, the contrast between the bar and the space in the visible stealth barcode is lowered, and the barcode information cannot be read due to the overlapping background pattern. there were.

In many cases, a fluorescent substance is mixed in the paper of the underlayer 10 to make it look white. In such a case, the UV light illuminating the underlayer 10 causes the underlayer 10 to be exposed.
The fluorescent substance inside will fluoresce. As a result of this,
The visible light VR3 ″ generated from the underlayer 10 lowers the contrast between the bar and the space in the stealth barcode which is visible as described above, and the visible stealth barcode can be obtained by the barcode reading device. Sometimes it was impossible to read the barcode information of.

Although not shown, even if the stealth barcode layer is directly formed on the underlayer containing no fluorescent substance, the stealth barcode layer 14
The contrast between the bar and the space in the stealth bar code, which became visible when the visible light due to the fluorescence directed downward from the bottom reaches the base layer 10 and is reflected by the base layer, is reduced, and the barcode reading device Sometimes it becomes impossible to read the bar code information from the stealth bar code that has become visible.

Structures for eliminating these conventional drawbacks are disclosed in JP-A-3-182988 and JP-A-5-12503.
It is disclosed in the publication. In Japanese Patent Application Laid-Open No. 3-182988, in order to prevent the underlying pattern from becoming visible by the irradiation of visible light by the fluorescence of the stealth barcode layer, the light reflectance of the surface of the underlying layer is substantially the same as the reflectance of light for the fluorescent light. It has been proposed to print a background pattern with an ink that has

However, when inks of various colors are used for printing the background pattern, it is difficult to prepare inks of all colors with the above-mentioned reflectance, and moreover, for black inks. Cannot apply such a proposal.

[0012] Further, Japanese Patent Laid-Open No. 12503/1993 proposes a layer provided between the stealth barcode layer and the underlying printing layer to absorb the excitation light of the phosphor and transmit the emission wavelength. However, in this case, the fluorescent light emission of the underlayer can be prevented, but it is not possible to prevent the underlying pattern from becoming visible due to the irradiation of visible light by the fluorescence of the stealth barcode layer.

The present invention has been made under the above circumstances, and an object of the present invention is invisible information recording which is invisible under visible light above the underlayer, and which is visible by being irradiated with light having a predetermined wavelength. An invisible information recording body having a layer, wherein visible light generated by fluorescence of the invisible information recording layer may be interposed between the underlayer or the underlayer and the invisible information recording layer. It lowers the contrast of the invisible information recording layer that is reflected by the layer and becomes visible by fluorescence, and makes it impossible to read information from the invisible information recording layer because the underlying print pattern overlaps with the invisible information. When the ground layer contains a fluorescent substance, some of the excitation light for reading the invisible information recording layer reaches the underlayer and the invisible information is recorded by the visible light generated by causing the fluorescent substance to fluoresce. Fluorescence due to lower the contrast of the invention is to provide invisible information recording medium that can reliably prevent or to impossible to read information from the invisible information recording layer.

[0014]

In order to achieve the above-mentioned object of the present invention, an invisible information recording medium according to the present invention is provided with an underlayer and a visual invisible light provided above the underlayer. It is characterized in that it is provided with an invisible information recording layer which is capable of being visible and emits fluorescence upon irradiation with light having a predetermined wavelength, and a light modulation layer provided between the underlayer and the invisible information recording layer. There is.

[0015]

In the invisible information recording medium according to the present invention, which is characterized as described above, the visible light generated by the fluorescence of the invisible information recording layer is between the underlayer or the underlayer and the invisible information recording layer. The reflected light reflected by an intermediate layer such as an underprinting layer that may be present in the background or a part of the excitation light for reading the invisible information recording layer when the underlayer contains a fluorescent substance causes the above-mentioned fluorescence. The light modulation layer modulates visible light generated by causing the substance to fluoresce before reaching the invisible information recording layer. This modulation prevents a substantial reduction in the contrast of the invisible information recording layer that is visible by fluorescence and prevents the underlying print pattern from overlapping the invisible information.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will now be described in detail with reference to FIGS. 1 to 4 in the accompanying drawings. FIG. 1 shows a cross section of a stealth barcode-equipped recording medium 20 according to a first embodiment of the present invention, which is an invisible information recording medium.

The base layer 21 in this embodiment is, for example, a paper cover of a book, and a fluorescent substance is mixed in the paper cover to make the white of the base look vivid. Underlayer 2
An underprint layer 22 is formed on the surface of 1 by printing a pattern such as letters, numbers or pictures.

A photochromic layer 24 functioning as a light modulating layer is formed by printing on the surface of the base printing layer 22, and the surface of the photochromic layer 24 is invisible under visible light and has a predetermined wavelength such as ultraviolet rays. A stealth bar code layer 26 is formed by printing a bar code composed of an ink that is fluorescent and visible when irradiated with light as an invisible information recording layer.

The photochromic layer 24 contains a photochromic material which is transparent under visible light but has a property of being blackened or colored by irradiation of ultraviolet rays. With such a configuration, under normal visible light, both the stealth barcode layer 26 and the photochromic layer 24 are transparent, so that patterns such as letters, numbers, and pictures of the base printing layer 22 can be seen from the outside through them. .

When it is necessary to read the bar code information from the stealth bar code layer 26, a bar code reader (not shown) equipped with an ultraviolet ray source is used as an illuminator.
The stealth barcode layer 26 is irradiated with ultraviolet UV.

The ultraviolet rays UV are stealth barcode layers 2
6 and the photochromic layer 2
4 causes blackening or coloring. VR1 directed upward in the visible light generated from the fluorescence of the stealth barcode layer 26 makes the stealth barcode visible, and VR2 directed downward from the stealth barcode layer 26.
Is mostly absorbed by the blackened or colored photochromic layer 24 and does not reach the underlying printing layer 22.

Further, even if the ultraviolet rays UV which have reached the underlayer 21 through the photochromic layer 24 and the underlayer printing layer 22 fluoresce the fluorescent substance in the underlayer 21, the underlayer 2
The visible light VR3 ″ generated by the fluorescence of No. 1 is absorbed by the photochromic layer 24 and does not go out to the outside.

From these results, the contrast between the bar and the space in the stealth bar code which is fluorescent and visible in the stealth bar code layer 26 is that the stealth bar code in the visible light generated from the fluorescence of the stealth bar code layer 26. Photochromic layer 2 below the code layer 26
No. 4, the stealth bar code which is fluorescent and visible in the stealth bar code layer 26 is not deteriorated under the influence of VR2 and the underlying print pattern does not overlap. The device can reliably read the bar code information.

After reading the bar code information, the bar code reader (not shown) is used to stealth the bar code layer 2.
When the ultraviolet ray irradiation to the stealth barcode layer 26 is stopped away from 6, the fluorescence of the stealth barcode layer 26 is stopped and the stealth barcode layer 26 becomes transparent,
Further, the photochromic layer 24 is erased and returned to a transparent state by being exposed to visible light in the external space or by absorbing heat in the external space.

As a result of these, it becomes possible to see the patterns such as letters, numbers and pictures of the underprinting layer 22 from the outside again through the stealth barcode layer 26 and the photochromic layer 24 which are transparent by ordinary visible light.

In general, the photochromic layer 24 is formed by mixing the photochromic material molecules with a binder material and printing it to form the base printing layer 22 or a solid thin film on the base layer 21 when the base printing layer 22 is not present. The photochromic material molecules tend to slow the coloring reaction and the decoloring reaction, and it takes a lot of time to read the bar code information from the stealth bar code as a result of the decrease in the coloring reaction rate, which may be practically inconvenient. In addition, the decrease in the erasing reaction speed is inconvenient when it is necessary to re-examine the characters, numbers, or a pattern such as a picture of the undercoat printing layer 22 located under the stealth barcode immediately after reading the barcode information. is there.

These inconveniences can be eliminated by constructing the bar code reader as shown in FIG. The barcode reading device 30 includes a preliminary light source 36 for coloring the photochromic layer and a light source 38 for erasing the photochromic layer before and after the barcode reading optical system 32 and the ultraviolet source 34.
have.

In this bar code reading device 30, when the bar code information is read from the stealth bar code layer 26, the stealth bar coded recording medium 20 shown in FIG. As shown, the preliminary light source 36 for coloring the photochromic layer, the ultraviolet source 34, and the light source 38 for erasing the photochromic layer are relatively passed in this order.

At this time, the preliminary light source 36 for coloring the photochromic layer irradiates a large amount of relatively strong ultraviolet rays toward the recording medium 20 with the stealth bar code to accelerate the coloring of the photochromic layer 24, and the ultraviolet rays are emitted from the ultraviolet source 34. Before reading the bar code information from the stealth bar code layer 26 by the bar code reading optical system 32, the photochromic layer 24 is colored to such an extent that the bar code information reading is not hindered.

The photochromic layer erasing light source 38 irradiates a large amount of relatively strong visible light toward the recording medium 20 with the stealth bar code to accelerate the erasing of the photochromic layer 24 after the reading of the bar code information. ,
Even immediately after the stealth barcode-equipped recording medium 20 is moved away from the barcode reading device 30, it is difficult to re-examine the pattern such as letters, numbers and pictures of the underprinting layer 22 from the outside through the stealth barcode layer 26 and the photochromic layer 24. The photochromic layer 24 is decolored to the extent that there is not any.

Since the photochromic layer 24 can be decolored by heating the photochromic layer 24, a heat source can be used instead of the photochromic layer decoloring light source 38.

Immediately after the reading of the bar code information, when it is not necessary to re-examine the pattern such as letters, numbers and pictures of the underprint layer 22 located under the stealth bar code from the outside, the photochromic layer erasing The light source 38 and the heat source for erasing the photochromic layer can be omitted.

As the photochromic material which is colored by irradiation with ultraviolet rays, for example, borosilicate glass in which silver halide is dispersed in a colloidal form, organic compounds of spiropyrans, 1,3,3-trimethyl-6 'are used. Organic compounds such as -nitro (indoline-2,2'-benzopyran) and spirooxazines can be used.

Here, a colloidal dispersion of silver halide in borosilicate glass is usually called photochromic glass, and is practically used as light control glasses. 1,3,3-Trimethyl-6'-nitro (indoline-2,2'-benzopyran) is colored reddish purple by irradiation with ultraviolet rays, and patterns such as letters, numbers and pictures of the underlying printing layer 22 are almost invisible. . Since the photochromic material made of an organic substance such as spirooxazine has good durability against repeated use and has a fast decoloring property, the photochromic layer decoloring light source 38 in the bar code reading device 30 as shown in FIG. No heat source is needed.

As the photochromic material other than the above, stilbene, salicylidene aniline, acridine aniline, anthracene, thioindigo photochromic organic compounds or fulgide photochromic organic compounds can be used.

Since the wavelength spectrum of the light emitted by the fluorescent substance contained in the stealth barcode layer 26 by fluorescence is not white light but has a narrow narrow range, the fluorescence of the stealth barcode layer 26 is generated. In order for the photochromic layer 24 to absorb and block the reflected light from the undercoat printing layer 22 and the underlayer 21 and the visible light generated by the fluorescence of the underlayer 21, the fluorescent substance contained in the stealth barcode layer 26 is fluorescent. The photochromic layer 24 may be colored in a color that absorbs only the wavelength region of the light emitted by, and does not necessarily have to be colored in black.

Considering the wavelength of the light emitted by the fluorescent substance contained in the stealth barcode layer 26 due to the fluorescence and the wavelength of the light absorbed by the coloring in the photochromic layer 24,
The selection range of photochromic materials can be expanded.

A photochromic material, which is usually called a photochromic glass in which silver halide is dispersed in a colloidal state in borosilicate glass, is blackened by ultraviolet irradiation and absorbs wavelengths in the entire visible light in the same manner. The selection range of the fluorescent material contained in the code layer 26 can be expanded.

However, when the above-mentioned photochromic glass is applied to the photochromic layer 24 of the present invention to obtain a desired effect by coloring, the thickness of the photochromic layer 24 becomes considerably large. As a result, when the underlayer 21 is made of a relatively flexible material such as paper, when the recording medium 20 with the stealth barcode is bent, the photochromic layer 24 is damaged and a desired effect can be obtained. It's gone.

In order to apply the above-mentioned photochromic glass to the photochromic layer 24 of the present invention to obtain a desired effect by coloring and to prevent the recording medium 20 with the stealth bar code from being bent, it is necessary to use (A) in FIG. ), The photochromic glass 40 in the form of particles is mixed with a binder 42 made of a flexible plastic having a refractive index substantially the same as that of the photochromic glass 40, and if the underprinting layer 22 or the underprinting layer 22 is not present, the underlayer Two
The photochromic layer 24 may be formed by applying it to No. 1.

It is necessary to use a binder material that sufficiently transmits ultraviolet rays. Since the refractive index of the photochromic glass 40 and the refractive index of the binder 42 are substantially the same, the particulate photochromic glass 40 cannot be seen under normal visible light, and the pattern such as letters, numbers, or pictures of the underprinting layer 22 can be seen. Visible through the photochromic layer 24 without distortion.

Further, as shown in FIG. 3B, the fiber-shaped photochromic glass 50 is bonded by a flexible plastic binder 42 having a refractive index substantially the same as that of the photochromic glass 40 to bond the photochromic glass 50 to the underprint layer 22. When the underlayer printing layer 22 is not provided, the same effect as that of the photochromic layer 24 shown in FIG. 3A can be obtained by forming the photochromic layer 24 by disposing it on the underlayer 21. .

FIG. 4 shows a cross section of a recording medium 60 with a stealth bar code according to a second embodiment of the present invention, which is an invisible information recording medium. The recording medium 60 with a stealth barcode of this embodiment uses a polarizing film 62 as a light modulation layer instead of the photochromic layer 24 in the recording medium 20 with a stealth barcode shown in FIG. Since the structure other than the polarizing film 62 is the same as the structure of the recording medium 20 with the stealth barcode described above, the same members as those of the recording medium 20 with the stealth barcode described above are denoted by the same reference numerals, and detailed description thereof will be given. Is omitted.

In order to read the bar code information from the recording medium 60 with the stealth bar code of the second embodiment, an ultraviolet source 64 is provided as an illuminating device and a stealth bar is provided on the light incident side of the bar code reading optical system 66. A barcode reading device 70 in which a polarizing plate (analyzer) 68 having a polarization plane orthogonal to the polarization plane of the polarization film 62 of the coded recording medium 60 is arranged is prepared.

In this embodiment, the stealth barcode layer 2 is used.
When the ultraviolet ray source 64 of the barcode reading device 70 irradiates the ultraviolet ray UV toward the stealth barcode layer 26 to read the barcode information from 6, the ultraviolet ray UV emits visible fluorescence VR1 and VR2 from the stealth barcode layer 26. Let

Since the fluorescence VR1 and VR2 are non-polarized,
Fluorescence V toward the barcode reading optical system 66 of the barcode reading device 70 above the stealth barcode layer 26.
R1 is a polarizing plate (analyzer) 68 in the polarizing plate (analyzer)
The light of the polarization direction component 68 passes and enters the barcode reading optical system 66.

The fluorescent light VR2 directed downward from the stealth barcode layer 26 passes through the polarizing film 62 and passes through the underprint layer 2.
The fluorescence reflected light VR3 'is emitted from the light source 2, reflected from here, passes through the polarizing film 62 again, and travels toward the barcode reading optical system 66 of the barcode reading device 70.

The fluorescence reflection light VR3 'is converted into light having only the polarization direction component of the polarization film 62 by the polarization film 62.
Moreover, since this polarization direction is orthogonal to the polarization direction of the polarizing plate (analyzer) 68 arranged on the light incident side of the barcode reading optical system 66, the fluorescence reflection light V
R3 ′ is blocked by the polarizing plate (analyzer) 68 and cannot reach the barcode reading optical system 66.

Further, ultraviolet UV which has reached the underlayer 21
Due to this, the fluorescent substance in the underlayer 21 may emit light, but this fluorescent light VR3 ″ is also converted into polarized light in a direction orthogonal to the polarizing direction of the polarizing plate (analyzer) 68 when passing through the polarizing film 62. Therefore, when it reaches the polarizing plate (analyzer) 68, it is blocked by the polarizing plate (analyzer) 68 and cannot reach the barcode reading optical system 66.

After all, the bar code reading optical system 6 of the bar code reading device 70 above the stealth bar code layer 26.
Only the fluorescent light VR1 toward 6 can reach the bar code reading optical system 66, and the bar code information can be read from the stealth bar code layer 26 with good contrast without being disturbed by the underlying print pattern.

Although the invisible information recording layer is the stealth bar code layer 26 in the two embodiments described above, the invisible information recording layer may be another information recording means instead of the bar code.

Further, in this specification, the term "light modulation layer" means a base printing layer as in the case of the first embodiment of the present specification,
We are also considering the function to prevent UV rays from entering the underlayer.

[0053]

As described in detail above, the invisible information recording medium according to the present invention is invisible under visible light above the underlayer, and becomes visible when irradiated with light of a predetermined wavelength. An invisible information recording body having an invisible information recording layer, wherein visible light generated by fluorescence of the invisible information recording layer may be interposed between the underlayer or the underlayer and the invisible information recording layer. Such as lowering the contrast of the invisible information recording layer which is visible by fluorescence due to reflection by the intermediate layer and makes the underlying print pattern overlap with the invisible information, making it impossible to read information from the invisible information recording layer. Alternatively, when the underlayer contains a fluorescent substance, the visible light generated by the ultraviolet light reaching the underlayer causes the fluorescent substance to fluoresce, and the contrast of the invisible information recording layer is caused by the fluorescence. It is possible to reliably prevent the lowers or impossible to read information from the invisible information recording layer.

[Brief description of drawings]

FIG. 1 is a sectional view of a recording medium with a stealth barcode according to a first embodiment of the present invention, which is an invisible information recording medium.

FIG. 2 is a diagram schematically showing a preferred configuration of a barcode reading device for reading barcode information from the stealth barcode-attached recording medium of FIG.

3A and 3B are enlarged cross-sectional views showing two configuration examples of a stealth barcode layer which is not damaged by bending of the recording medium with a stealth barcode of FIG. 1.

FIG. 4 is a block diagram of a recording medium with a stealth barcode according to a second embodiment of the present invention, in which the barcode information is read from the recording medium with a stealth barcode. It is sectional drawing shown.

FIG. 5 is an enlarged cross-sectional view of a conventional example of a recording medium with a stealth barcode, which is a kind of invisible information recording medium.

[Explanation of symbols]

20 ... Recording medium with stealth barcode, 21 ... Underlayer, 22 ... Underlayer printing layer, 24 ... Photochromic layer, 2
6 ... Stealth bar code layer, 30 ... Bar code reader, 32 ... Bar code reading optical system, 34 ... Ultraviolet source, 3
6 ... Preliminary light source for coloring photochromic layer, 38 ... Light source for erasing photochromic layer, 40 ... Photochromic glass, 42 ... Binder, 50 ... Photochromic glass, 60 ... Stealth barcode-attached recording medium, 62 ... Polarizing film, 64 ... UV source , 66 ... Bar code reading optical system, 68 ... Polarizing plate (analyzer), 70 ... Bar code reading device.

Claims (1)

[Claims] 1. An underlayer, an invisible information recording layer provided above the underlayer, which is invisible under visible light and which is visible by irradiating with light of a predetermined wavelength to fluoresce. And an optical modulation layer provided between the information recording layer and the information recording layer.