JP2014156024A - Medium with image formed thereon and method of checking medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medium which is difficult to be forged.SOLUTION: When an image 12 is irradiated with first light having a first emission spectrum 41, the reflectance from a first pattern region 21 and the reflectance from a first background region 22 are recognized visually as light rays of different colors, and the reflectance from a second pattern area 26 and the reflectance from a second background area 27 are recognized visually as light rays of the same color. When the image 12 is irradiated with second light having a second emission spectrum 42, the reflectance from the first pattern area 21 and the reflectance from the first background area 22 are recognized visually as light rays of the same color, and the reflectance from the second pattern area 26 and the reflectance from the second background area 27 are recognized visually as light rays of different colors.

Description

  The present invention relates to a medium on which an image whose appearance changes according to the wavelength spectrum of irradiated light is formed. The present invention also relates to a medium confirmation method.

  It is known to use metameric pair inks that apply metamerism in media that require prevention of counterfeiting, such as securities including gold vouchers and prepaid cards, and identification cards including licenses. The metameric pair ink is a pair of inks that appear to be the same color or different colors depending on the type of light source to be irradiated and the type of filter that transmits only a specific wavelength. It has been proposed to form an image using such a metameric pair ink, thereby preventing forgery.

  For example, in Patent Document 1, the same color appears under normal light from sunlight, fluorescent lamps, incandescent lamps, etc., but when viewed through the desired filter or under the light that has passed through the desired filter, It has been proposed to form an image using two types of inks having metameric properties that appear to have different hues.

JP 54-159004 A

  In recent years, with the development of lighting technology, the emission spectrum of a white light source used indoors has changed compared to the conventional one. For example, fluorescent lamps used indoors have conventionally been fluorescent lamps having a continuous wavelength distribution, which are called ordinary fluorescent lamps and single-wavelength fluorescent lamps. On the other hand, at present, a three-wavelength fluorescent lamp having a peak in each of the red, green, and blue wavelength regions has become mainstream. In addition, there is an increasing number of illuminations using LEDs that have a peak in the blue wavelength region and have a continuous wavelength distribution in other wavelength regions such as green and red. Thus, various light sources are currently used as illumination.

  By the way, the conventional anti-counterfeit medium using the metameric pair ink is configured such that an image is hidden when it is irradiated with a fluorescent lamp or sunlight having a continuous wavelength distribution. However, as described above, in recent years, a white light source having a peak in a specific wavelength region has been widely used. Therefore, in the conventional anti-counterfeit medium, there is a problem that an image that should be hidden appears under a white light source.

  An object of this invention is to provide the medium which can solve such a subject effectively.

  The present invention is a medium in which an image is formed on a substrate, and the image has a first image region and a second image region, and the first image region includes a first picture region, and the first image region. A first background area arranged around one picture area, and the second image area includes a second picture area and a second background area arranged around the second picture area. When the first light having the first emission spectrum is irradiated, the reflected light from the first picture area and the reflected light from the first background area are visually recognized as different color lights, and the second picture The reflected light from the region and the reflected light from the second background region are visually recognized as light of the same color, and when the second light having a second emission spectrum different from the first emission spectrum is irradiated, Reflected light from the pattern area and reflected light from the first background area Are recognized as the same color of light, and reflected light from the reflected light and the second background region from the second picture area is visually recognized as light of different colors, it is a medium.

  In the medium according to the present invention, the first light may be first white light emitted from a first white light source, and the second light may be second white light emitted from a second white light source. . In this case, at least one of the first white light source and the second white light source may be formed of a three-wavelength fluorescent lamp or a white LED.

In the medium according to the present invention, at least one of the first pattern area and the first background area is a hue change area in which a hue changes according to a spectrum of irradiated light, and the second pattern area and the first pattern area At least one of the second background areas may be a hue change area in which the hue changes according to the spectrum of the irradiated light. Here, the hue change region is a negative peak whose reflection spectrum is convex downward from the baseline, and has a depth of 0.5 times or more of the baseline height h ₀ and 50 nm. It is defined as a region containing a negative peak having the following half width.

In the medium according to the present invention, one of the first design area and the first background area is a hue change area, and the other is a non-hue change area, and one of the second design area and the second background area. May be a hue change region, and the other may be a non-hue change region. Here, the non-hue change region does not include a negative peak whose reflection spectrum has a depth of 0.5 times or more of the baseline height h ₀ , or the reflection spectrum has a half width of 50 nm or less. Defined as a region that does not contain negative peaks.

  In the medium according to the present invention, the first design area and the second design area may be a hue change area, and the first background area and the second background area may be a non-hue change area. In this case, both of the first picture area and the second picture area may contain the same hue change ink whose hue changes according to the spectrum of the irradiated light.

  In the medium according to the present invention, the first pattern area and the second background area may be a hue change area, and the first background area and the second pattern area may be a non-hue change area. In this case, both the first picture area and the second background area may include the same hue change ink whose hue changes according to the spectrum of the irradiated light.

  In the medium according to the present invention, the first background area and the second background area may be hue change areas, and the first pattern area and the second pattern area may be non-hue change areas. In this case, both the first background area and the second background area may include the same hue change ink whose hue changes according to the spectrum of the irradiated light.

  In the medium according to the present invention, the hue change ink contained in at least one of the first picture area and the first background area, and the hue contained in at least one of the second picture area and the second background area. The change ink may be different.

  In the medium according to the present invention, each of the first design area, the first background area, the second design area, and the second background area may include a plurality of unit areas arranged apart from each other. . In this case, the unit area may form a dot area or may form a micro character.

  The present invention relates to a method for confirming a medium on which an image is formed on a substrate, the step of preparing the medium described above, and irradiating the medium with a first light having a first emission spectrum, thereby the first image. A step of confirming that the first picture area and the first background area of the area are discriminated and that the second picture area and the second background area of the second image area are not discriminated; Irradiating the medium with second light having an emission spectrum, the first picture area of the first image area and the first background area are not distinguished, and the second picture of the second image area And a step of confirming that the region and the second background region are distinguished from each other.

  ADVANTAGE OF THE INVENTION According to this invention, the medium in which the image for which it was difficult to clarify the whole image was formed can be provided. For this reason, it can suppress that a medium is forged.

FIG. 1 is a plan view showing a medium according to the first embodiment of the present invention. FIG. 2 is an enlarged plan view showing an image of the medium shown in FIG. FIG. 3 is a cross-sectional view showing a case where the image of FIG. 2 is viewed from the III-III direction. FIG. 4 is a diagram showing an emission spectrum of the first white light. FIG. 5 is a diagram showing an emission spectrum of second white light. FIG. 6 is a diagram showing an emission spectrum of other white light. FIG. 7 is a diagram illustrating a reflection spectrum of a region including hue change ink. FIG. 8 is a diagram showing a reflection spectrum of a region including the first ink. FIG. 9 is a diagram showing a reflection spectrum of a region including the second ink. FIG. 10 is a diagram showing the spectra shown in FIG. 4 and FIGS. 7 to 9 in an overlapping manner. FIG. 11 is a plan view showing an image when the first white light is irradiated in the first embodiment. FIG. 12 is a diagram showing the spectra shown in FIG. 5 and FIGS. FIG. 13 is a plan view showing an image when the second white light is irradiated in the first embodiment. FIG. 14 is a cross-sectional view showing an image according to the second embodiment of the present invention. FIG. 15 is a plan view showing an image when the first white light is irradiated in the second embodiment. FIG. 16 is a plan view showing an image when the second white light is irradiated in the second embodiment. FIG. 17 is a cross-sectional view showing an image according to the third embodiment of the present invention. FIG. 18 is a plan view showing an image when the first white light is irradiated in the third embodiment. FIG. 19 is a plan view showing an image when the second white light is irradiated in the third embodiment. FIG. 20 is a plan view showing an image in the fourth embodiment of the present invention. 21 is a cross-sectional view showing a case where the image of FIG. 20 is viewed from the XXI-XXI direction. FIG. 22 is a plan view showing an image when the first white light is irradiated in the fourth embodiment. FIG. 23 is a plan view showing an image when the second white light is irradiated in the fourth embodiment. FIG. 24 is a plan view showing an image in a modification of the fourth embodiment.

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, an example of light used for observing the medium 10 according to the present embodiment will be described.

  As light used for observing the medium 10, for example, two types of white light having different emission spectra are used. For example, white light emitted from a three-wavelength fluorescent lamp is used as the first white light having the first emission spectrum, and white light emitted from the white LED is used as the second white light having the second emission spectrum. Used.

  FIG. 4 is a diagram showing a first emission spectrum 41 of the first white light emitted from the three-wavelength fluorescent lamp. The first emission spectrum 41 has peaks in at least three wavelength regions. For example, as shown in FIG. 4, the first emission spectrum 41 includes a first peak 41a existing in the blue wavelength region, a second peak 41b existing in the green wavelength region, and a third peak 41c existing in the red wavelength region. , Including. Each of the peaks 41a, 41b, and 41c is a steep peak whose half width is about 10 nm. In addition, the wavelength and half value width of each peak 41a, 41b, 41c are not specifically limited, According to the optical characteristic of the hue change ink mentioned later, various types of three wavelength form fluorescent lamps can be used.

  FIG. 5 is a diagram showing a second emission spectrum 42 of the second white light emitted from the white LED. The second white light is light having a more continuous wavelength distribution than the first white light described above. For example, as shown in FIG. 5, the second emission spectrum 42 includes a first peak 42 a that exists in the blue wavelength range and a second peak 42 b that continuously spreads over the green wavelength range and the red wavelength range.

  Next, the medium 10 observed using the first white light and the second white light described above will be described. First, the entire medium 10 will be described with reference to FIGS. 1 and 2.

(Medium)
FIG. 1 is a plan view showing an example of a medium 10 on which an image 12 is formed on a substrate 11, and FIG. 2 is an enlarged plan view showing an image 12 of the medium 10 shown in FIG. The medium 10 is configured as securities such as gift certificates. In the present embodiment, the image is not limited to an image indicating specific information or meaning specific information. For example, an image is a concept including a wide range of figures, characters, patterns, patterns, symbols, patterns, marks, colors, and the like.

  In the present embodiment, the image 12 functions as an authenticity determination image for determining the authenticity of the medium 10. The image 12 has a first image region 20 and a second image region 25 as shown in FIG. The first image area 20 includes a first picture area 21 having an outline corresponding to an image “O”, and a first background area 22 arranged around the first picture area 21. The second image area 25 includes a second picture area 26 having an outline corresponding to the image “K” and a second background area 27 arranged around the second picture area 26.

  In FIG. 2, the boundary line 15a between the first image area 20 and the second image area 25, the boundary line 15b between the first pattern area 21 and the first background area 22, and the second pattern area 26 The boundary line 15c between the second background region 27 is drawn for convenience and is not always visually recognized. FIG. 2 shows an example in which the first image area 20 and the second image area 25 are in contact with each other. However, the present invention is not limited to this, and the first image area 20 and the second image area 25 may be separated from each other.

(Composition of pattern area and background area)
Next, a specific configuration of each of the areas 21, 22, 26, and 27 will be described. First, the sectional structure of each of the regions 21, 22, 26, and 27 will be described with reference to FIG. FIG. 3 is a cross-sectional view showing a case where the image 12 of FIG. 2 is viewed from the III-III direction.

  As shown in FIG. 3, each of the regions 21, 22, 26, and 27 includes the base material 11 and any one of inks 31, 33, and 35 provided on the base material 11. Specifically, both the first picture area 21 and the second picture area 26 include the base material 11 and the hue change ink 31 provided on the base material 11. The hue change ink 31 included in the first picture area 21 and the hue change ink 31 included in the second picture area 26 are the same. The first background region 22 includes the base material 11 and the first ink 33 provided on the base material 11. The second background region 27 includes the base material 11 and the second ink 35 provided on the base material 11.

[Hue change ink, first ink and second ink]
The hue change ink 31 and the first ink 33 are configured to be visually recognized as different colors when irradiated with the first white light described above, and to be visually recognized as the same color when irradiated with the second white light described above. Has been. That is, the hue change ink 31 and the first ink 33 are metameric pair inks. Further, the hue change ink 31 and the second ink 35 are visually recognized as the same color when irradiated with the first white light, and are visually recognized as different colors when irradiated with the second white light. It is configured. That is, the hue change ink 31 and the second ink 35 are also metameric pair inks.

Here, “same color” means that the hues of the two colors are close to each other to the extent that the color difference cannot be discerned with the naked eye. More specifically, “same color” means that the color difference ΔE ^* _ab between the two colors is 20 or less, preferably 10 or less, more preferably 3 or less. The “different color” means that the color difference ΔE ^* _ab between the two colors is larger than 20. Here, the color difference ΔE ^* _ab is a value calculated based on L ^* , a ^* and b ^* in the L ^* a ^* b ^* color system, and is an index relating to a color difference when observed with the naked eye. Is the value. ^{Incidentally, L} * in the L ^* a * ^{b *} color system, ^{a *} and ^{b *,} or tristimulus values X in the XYZ color system, Y and Z, is calculated based on the spectrum of light. A relationship according to a well-known conversion equation is established between L ^* , a ^*, and b ^* and the tristimulus values X, Y, and Z.

  The tristimulus values can be measured by using a measuring instrument such as a spectrophotometer, a color difference meter, a colorimeter, a color meter, a chromaticity meter, for example. Among these measuring instruments, the spectrophotometer can obtain the spectral reflectance of each wavelength, and therefore can measure the tristimulus values with high accuracy, and is therefore suitable for analyzing the color difference.

In order to calculate the color difference ΔE ^* _ab , for example, first, light from two regions to be compared is measured with a spectrophotometer, and based on the result, tristimulus values X, Y, Z, or L ^* , a ^* , b ^* are calculated. Next, the color difference is calculated from the differences ΔL ^* , Δa ^* , Δb ^* of L ^* , a ^* , b ^* in each region based on the following formula.

  Hereinafter, the reflection spectrum of each ink 31, 33, 35 will be described. 7 is a diagram showing the reflection spectrum of the hue change ink 31, FIG. 8 is a diagram showing the reflection spectrum of the first ink 33, and FIG. 9 is a diagram showing the reflection spectrum of the second ink 35. . Each reflection spectrum is obtained by measuring the intensity ratio between the reflected light from the reference object and the reflected light from the inks 31, 33, and 35 using a spectrophotometer. As the reference object, a standard white plate is usually used. 7 to 9, R on the vertical axis represents the intensity ratio between the reflected light from the reference object and the reflected light from the ink. The reflected light from each ink 31, 33, 35 includes not only the light reflected by each ink 31, 33, 35, but also the light reflected by the substrate 11, and other layers provided as necessary. The light reflected by is also included. Accordingly, it can be said that the reflection spectrum shown in FIGS. 7 to 9 is a reflection spectrum in a region including each of the inks 31, 33, 35 and the corresponding substrate 11 and other layers.

As shown in FIG. 7, the reflection spectrum 32 of the hue change ink 31 includes a negative peak 32b that exists in the green wavelength region and protrudes downward from the base line 32e. The negative peak 32b satisfies the following characteristics (1) and (2).
(1) to have 0.5 times or more the depth d of the height h ₀ of the baseline.
(2) It has a half width w of 50 nm or less.
Note that the method for determining the baseline 32e of the negative peak 32b is not particularly limited, and a general method in spectrum analysis is used. For example, a line connecting the maximum value of reflection in the wavelength region longer than the wavelength of the negative peak 32b and the maximum value of reflection in the wavelength region shorter than the wavelength of the negative peak 32b is the baseline 32e. Drawn as. Further, the wavelength range to be analyzed may be limited when determining the baseline 32e. For example, a line connecting the maximum value of reflection in the range extending from the wavelength of the negative peak 32b to the long wavelength side in the snm range and the maximum value of reflection in the range extending from the wavelength of the negative peak 32b to the short wavelength side snm is the baseline. It may be drawn as 32e. The value of s is appropriately determined according to the required degree of hue change, and is, for example, 50.

Hereinafter, the operation of the negative peak 32b satisfying the above features (1) and (2) will be described.
As described above, the first emission spectrum 41 of the first white light has the steep second peak 41b existing in the green wavelength region. Therefore, when the first white light is applied to the hue change ink 31, the intensity of the green component contained in the first white light is greatly reduced before and after being reflected by the hue change ink 31, and as a result, the first white light is reduced. The hue of light changes greatly. Specifically, the hue of the first white light changes from white to pink before and after reflection. In the following description, the pink portion that appears when the first white light is irradiated to the region including the hue change ink 31 is also referred to as a pink portion Pm.
On the other hand, the second peak 42b of the second emission spectrum 42 of the second white light continuously spreads over the green wavelength range and the red wavelength range. That is, the width of the second peak 42 b of the second emission spectrum 42 is sufficiently wider than the width of the negative peak 32 b of the hue change ink 31. For this reason, even if the second white light is applied to the hue change ink 31 and the intensity of the green component contained in the second white light is reduced by the negative peak 32b of the hue change ink 31, the hue change ink is thereby reduced. The influence of the negative peak 32b of 31 on the hue of the second white light is smaller than that of the first white light. As a result, the hue of the second white light changes, for example, from white to yellow before and after reflection by the hue change ink 31. In the following description, the yellow portion that appears when the second white light is applied to the region including the hue change ink 31 is also referred to as a yellow portion Ym.

  As described above, according to the present embodiment, the reflection spectrum 32 of the hue change ink 31 includes the negative peak 32b that satisfies the characteristics (1) and (2) described above. The hue of can be changed according to the spectrum of the irradiated light. In the following description, a region including the hue change ink 31 and having a negative peak whose reflection spectrum has the above characteristics (1) and (2) is also referred to as a hue change region. In the present embodiment, the first picture area 21 and the second picture area 26 containing the hue change ink 31 are hue change areas.

  Preferably, the hue change ink 31 has a peak wavelength that matches or is close to any of the peak wavelengths of the peaks 41a, 41b, and 41c included in the first emission spectrum 41 of the first white light, and the above-described feature ( Configured or selected to include negative peaks that satisfy 1) and (2). Thereby, the hue change effect of the hue change ink 31 with respect to the first white light can be further increased. As shown in FIG. 7, in addition to the negative peak 32b existing in the green wavelength range, the hue change ink 31 has a negative peak 32a present in the blue wavelength range, a negative peak 32c present in the red wavelength range, and the like. Other negative peaks may be included. These negative peaks 32a and 32c may or may not satisfy the features (1) and (2) described above.

  As the hue change ink 31, various known hue change inks can be appropriately used. For example, as a hue change ink that can exhibit a pink or yellow color according to the spectrum of the irradiated white light, an ink called “CR8” of Stard Materials LLC;

  Next, the first ink 33 and the second ink 35 will be described. As shown in FIG. 8, the reflection spectrum 34 of the first ink 33 clearly does not include a negative peak that satisfies the above features (1) and (2). Therefore, a difference in hue of reflected light according to the spectrum of the irradiated light is unlikely to occur. For example, the first white light reflected by the first ink 33 is viewed as light yellow, while the second white light reflected by the first ink 33 is viewed as yellow. The reflection spectrum 36 of the second ink 35 includes a negative peak 36a that protrudes downward from the base line 36b. However, the half width of the negative peak 36a is clearly larger than 50 nm. Therefore, it can be said that the reflection spectrum 36 of the second ink 35 does not include a negative peak that satisfies the above-described features (1) and (2). Therefore, a difference in hue of reflected light according to the spectrum of the irradiated light is unlikely to occur. For example, the first white light reflected by the second ink 35 is viewed as pink, while the second white light reflected by the second ink 35 is viewed as amber. In the following description, a region containing an ink that hardly causes a difference in hue of reflected light according to the spectrum of the irradiated light, such as the first ink 33 and the second ink 35, that is, its reflection spectrum. Is a region that does not include the negative peak having the above feature (1) or whose reflection spectrum does not include the negative peak having the above feature (2). In the present embodiment, the first background region 22 including the first ink 33 and the second background region 27 including the second ink 35 are non-hue change regions. The first ink 33 and the second ink 35 are also referred to as non-hue change ink.

As the first ink 33 and the second ink 35, various known inks corresponding to one of the two colors indicated by the hue change ink 31 can be used.
For example, examples of the ink showing pink color include “UV BF D-330 Pink W” and “NS D-330 Pink” manufactured by DIC Graphics. The former is a UV curable ink, and the latter is an oxidation polymerization type ink. In addition, “UV BF SG20 Crimson Red” and “NS AZ 20 Crimson Red” manufactured by the same company can also be used as ink showing pink.
Examples of yellow ink include “UV BF AZ D-540 Yellow” and “NS D-540 Yellow” manufactured by DIC Graphics. The former is a UV curable ink, and the latter is an oxidation polymerization type ink. In addition, “UV BF SG 24 Red Yellow” manufactured by the same company can also be used as the ink showing yellow.

Regarding the first ink 33, the color difference between light yellow and yellow is sufficiently smaller than the color difference between pink and yellow in the case of the hue change ink 31, and therefore, in the following description, light yellow is changed to yellow. Sometimes called. For example, in the following description, a light yellow portion that appears when the region including the first ink 33 is irradiated with the first white light is referred to as a yellow portion Y1, and the region including the first ink 33 is referred to. The yellow part that appears when the second white light is irradiated may be referred to as a yellow part Y2.
Preferably, in the first ink 33, the color difference between the yellow portion Y2 and the yellow portion Ym generated by the hue change ink 31 is smaller than the color difference between the yellow portion Y1 and the yellow portion Ym. It is configured as such.

Also for the second ink 35, the color difference between pink and dark blue is sufficiently smaller than the color difference between pink and yellow in the case of the hue change ink 31. Sometimes called pink. For example, in the following description, a pink portion that appears when the first white light is irradiated to the region including the second ink 35 is referred to as a pink portion P1, and the region including the second ink 35 is referred to as the first portion. The amber portion that appears when two white light is irradiated may be referred to as a pink portion P2.
Preferably, in the second ink 35, the color difference between the pink portion P1 and the pink portion Pm generated by the hue change ink 31 is smaller than the color difference between the pink portion P2 and the pink portion Pm. It is configured as such.

  The method of providing each ink 31, 33, 35 on the base material 11 is not particularly limited, and a known method is appropriately used. For example, a screen printing method, an offset printing method, or an ink jet printing method can be used. Preferably, the inks 31, 33, and 35 are configured so that their reflection characteristics and diffusion characteristics are substantially equal. For example, the thicknesses of the inks 31, 33, and 35 are substantially equal. Thereby, it is possible to prevent the boundary lines 15a, 15b, and 15c from being visually recognized due to the difference in thickness between the inks 31, 33, and 35.

  3 shows an example in which the hue change ink 31 included in the first picture area 21 and the first ink 33 included in the first background area 22 are in contact with each other. However, the present invention is not limited to this, and a gap that cannot be visually recognized by the naked eye may exist between the hue change ink 31 and the first ink 33. Similarly, the first ink 33 and the second ink 35, and the hue change ink 31 and the second ink 35 may be in contact with each other, or there is a gap between them that cannot be visually recognized by the naked eye. You may do it.

[Base material]
The material of the base material 11 is not particularly limited, and is appropriately selected according to the type of securities constituted by the medium 10. For example, white polyethylene terephthalate having excellent printability and processability is used as the material of the substrate 11. Further, paper for constituting securities paper or banknote paper may be used as the base material 11. The thickness of the base material 11 is appropriately set according to the type of securities constituted by the medium 10.

  Next, the operation and effect of the present embodiment having such a configuration will be described. Here, with reference to FIG. 10 to FIG. 13, a method for confirming whether or not the securities composed of the medium 10 are genuine will be described.

(At first white light irradiation)
First, the medium 10 is irradiated with first white light having the first emission spectrum 41. FIG. 10 is a diagram showing the reflection spectra 32, 34, and 36 in the region including the inks 31, 33, and 35, and FIG. 11 is a plane showing the image 12 when the first white light is irradiated. FIG. In FIG. 10, the first emission spectrum 41 of the first white light is also indicated by a dotted line. As shown in FIG. 10, the second peak 41 b of the first emission spectrum 41 of the first white light overlaps with the negative peak 32 b of the reflection spectrum 32 of the hue change ink 31. For this reason, the first picture area 21 including the hue change ink 31 is visually recognized as a pink portion Pm in which the intensity of the green component is greatly reduced. On the other hand, the first background area 22 including the first ink 33 arranged around the first picture area 21 is visually recognized as a yellow portion Y1. Thus, when 1st white light is irradiated, the reflected light from the 1st pattern area | region 21 and the reflected light from the 1st background area | region 22 are visually recognized as light of a different color. As a result, as shown in FIG. 11, the first picture area 21 and the first background area 22 are discriminated. For this reason, an image “O” appears in the first image area 20.

  Similar to the first picture area 21, the second picture area 26 including the hue change ink 31 is visually recognized as a pink part Pm. Further, the second background area 27 including the second ink 35 arranged around the second picture area 26 is also visually recognized as the pink portion P1. Thus, when 1st white light is irradiated, the reflected light from the 2nd pattern area | region 26 and the reflected light from the 2nd background area | region 27 are visually recognized as light of the same color. As a result, as shown in FIG. 11, the second pattern area 26 and the second background area 27 are not distinguished. That is, the image “K” does not appear in the second image area 25.

(At the time of second white light irradiation)
Next, the medium 10 is irradiated with the second white light having the second emission spectrum 42. FIG. 12 is a diagram showing the reflection spectra 32, 34, and 36 in the region including the inks 31, 33, and 35, and FIG. 13 is a plane showing the image 12 when the second white light is irradiated. FIG. In FIG. 12, the second emission spectrum 42 of the second white light is also shown by a dotted line. As shown in FIG. 12, the width of the second peak 42 b of the second emission spectrum 42 is sufficiently wider than the width of the negative peak 32 b of the hue change ink 31. For this reason, the first pattern region 21 including the hue change ink 31 is visually recognized as a yellow portion Ym including a green component to some extent. On the other hand, the first background area 22 including the first ink 33 arranged around the first picture area 21 is visually recognized as a yellow portion Y2. Thus, when the second white light is irradiated, the reflected light from the first picture area 21 and the reflected light from the first background area 22 are visually recognized as light of the same color. As a result, as shown in FIG. 13, the first pattern area 21 and the first background area 22 are not distinguished. That is, the image “O” does not appear in the first image area 20.

  Similar to the first picture area 21, the second picture area 26 including the hue change ink 31 is visually recognized as a yellow part Ym. On the other hand, the second background region 27 including the second ink 35 arranged around the second pattern region 26 is visually recognized as a pink portion P2. As described above, when the second white light is irradiated, the reflected light from the second picture region 26 and the reflected light from the second background region 27 are visually recognized as different colors. As a result, as shown in FIG. 13, the second pattern area 26 and the second background area 27 are discriminated. For this reason, an image “K” appears in the second image area 25.

  As described above, according to the present embodiment, even if any one of two types of white light sources having different types is used, either one of the first image region 20 and the second image region 25 is hidden, In addition, any one of the first image region 20 and the second image region 25 can be expressed. For this reason, it is possible to suppress the elucidation of the entire pattern of the image 12. As a result, it is possible to suppress forgery of the securities composed of the medium 10.

  Further, according to the present embodiment, the first background region 22 and the second background region 27, which have a generally larger area than the first pattern region 21 and the second pattern region 26, are the first ink 33 and the second ink 35. Including non-hue change ink. For this reason, the hues of the first background region 22 and the second background region 27 do not change so much regardless of the type of the irradiated white light source. This makes it difficult for the user of the medium 10 to notice that the region in which the image appears changes according to the switching of the white light source. This also can prevent the entire pattern of the image 12 from being clarified. As a result, it is possible to suppress forgery of the securities constituted by the medium 10.

  Further, according to the present embodiment, it is possible to inspect whether or not an image appears in the first image region 20 and the second image region 25 by preparing two types of commonly used white light sources. . For this reason, it is possible to easily and quickly determine whether or not the medium 10 is regular without using special equipment such as a dedicated light source or a filter.

  In addition, according to the present embodiment, when the first white light is irradiated, the color difference between the “O” image between the first pattern region 21 of the pink portion Pm and the first background region 22 of the yellow portion Y1. When the second white light is irradiated, an image of “K” appears based on a color difference between the second picture area 26 of the yellow part Ym and the second background area 27 of the pink part P2. . As described above, the relationship between the hue of the pattern region and the hue of the background region is inverted from the relationship of yellow to pink to the relationship of pink to yellow. For this reason, the reliability of the inspection of whether the securities composed of the medium 10 are legitimate can be further increased by inspecting whether or not such a reversal relationship exists. Further, forgery of the medium 10 can be made more difficult.

  According to the present embodiment, both the first picture area 21 and the second picture area 26 include the same hue change ink 31 whose hue changes according to the spectrum of the irradiated light. For this reason, the medium 10 can be provided at a lower cost than when the first picture area 21 and the second picture area 26 include different hue change inks.

In this embodiment, a three-wavelength fluorescent lamp is used as the first white light source that emits the first white light, and a white LED is used as the second white light source that emits the second white light. showed that. However, the present invention is not limited to this, and other white light sources such as ordinary fluorescent lamps may be used as the first white light source or the second white light source. For reference, an example of an emission spectrum of white light emitted from a normal fluorescent lamp is shown in FIG.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the present embodiment, as shown in FIG. 14, both the first picture area 21 and the second background area 27 include the same hue change ink 31 whose hue changes according to the spectrum of the irradiated light. It is out. That is, the first pattern area 21 and the second background area 27 are hue change areas. On the other hand, the first background area 22 contains the first ink 33, and the second picture area 26 contains the second ink 35. That is, the first background area 22 and the second pattern area 26 are non-hue change areas. In the second embodiment shown in FIG. 14 to FIG. 16, the same parts as those in the first embodiment shown in FIG. 1 to FIG. Moreover, when it is clear that the effect obtained in the first embodiment can be obtained in the present embodiment, the description thereof may be omitted.

  Next, with reference to FIG. 15 and FIG. 16, a method for confirming whether or not the securities composed of the medium 10 are genuine will be described. FIG. 15 is a plan view showing the image 12 when the first white light is irradiated, and FIG. 16 is a plan view showing the image 12 when the second white light is irradiated.

(At first white light irradiation)
First, the medium 10 is irradiated with first white light having the first emission spectrum 41. In this case, as in the case of the first embodiment described above, the first pattern area 21 is visually recognized as the pink part Pm, and the first background area 22 is visually recognized as the yellow part Y1. Thus, the reflected light from the first picture area 21 and the reflected light from the first background area 22 are visually recognized as light of different colors. As a result, as shown in FIG. 15, the first pattern area 21 and the first background area 22 are discriminated. For this reason, an image “O” appears in the first image area 20.

  The second picture area 26 including the second ink 35 is visually recognized as a pink part P1. On the other hand, the second background region 27 including the hue change ink 31 arranged around the second picture region 26 is visually recognized as a pink portion Pm. Thus, when 1st white light is irradiated, the reflected light from the 2nd pattern area | region 26 and the reflected light from the 2nd background area | region 27 are visually recognized as light of the same color. As a result, as shown in FIG. 15, the second pattern area 26 and the second background area 27 are not distinguished. That is, the image “K” does not appear in the second image area 25.

(At the time of second white light irradiation)
Next, the medium 10 is irradiated with the second white light having the second emission spectrum 42. In this case, as in the case of the first embodiment described above, the first pattern area 21 is visually recognized as the yellow part Ym, and the first background area 22 is visually recognized as the yellow part Y2. Thus, the reflected light from the first picture area 21 and the reflected light from the first background area 22 are visually recognized as the same color light. As a result, as shown in FIG. 16, the first pattern area 21 and the first background area 22 are not distinguished. That is, the image “O” does not appear in the first image area 20.

  The second picture area 26 including the second ink 35 is visually recognized as a pink part P2. On the other hand, the second background region 27 including the hue change ink 31 arranged around the second picture region 26 is visually recognized as a yellow portion Ym. As described above, when the second white light is irradiated, the reflected light from the second picture region 26 and the reflected light from the second background region 27 are visually recognized as different colors. As a result, as shown in FIG. 16, the second pattern area 26 and the second background area 27 are discriminated. For this reason, an image “K” appears in the second image area 25.

  As described above, also in the present embodiment, as in the case of the first embodiment described above, the first image region 20 and the first image region 20 can be used regardless of which of the two types of white light sources of different types is used. Any one of the two image areas 25 can be hidden, and any one of the first image area 20 and the second image area 25 can be expressed. As a result, it is possible to suppress forgery of the securities composed of the medium 10.

  Further, according to the present embodiment, when the first white light is irradiated, the first background region 22 of the first image region 20 is visually recognized as the yellow portion Y1, and the second background region 27 of the second image region 25 is It is visually recognized as a pink part Pm. On the other hand, when the second white light is irradiated, the first background region 22 of the first image region 20 is visually recognized as a yellow portion Y2, and the second background region 27 of the second image region 25 is visually recognized as a yellow portion Ym. . Accordingly, when the first white light is irradiated, the first background region 22 and the second background region 27 are visually recognized as different color regions, and when the second white light is irradiated, the first background region 22 and the second background region are recognized. The area 27 is visually recognized as an area of the same color. Thus, according to the switching of the white light source, the hue relationship between the background regions of the first image region 20 and the second image region 25 is switched between the same color and the different color. Therefore, by checking whether the background area is the same color, it is possible to further increase the reliability of checking whether the securities composed of the medium 10 are genuine. Further, forgery of the medium 10 can be made more difficult.

  Further, according to the present embodiment, the second background area 27 arranged around the second picture area 26 having a generally larger area than the second picture area 26 includes the hue change ink 31. For this reason, compared with the case of the above-mentioned 1st Embodiment, it becomes easy to notice that the area | region where an image appears switches according to switching of a white light source. As a result, it is possible to more easily check whether the medium 10 is genuine.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS.

  In the present embodiment, as shown in FIG. 17, both the first background area 22 and the second background area 27 include the same hue change ink 31 whose hue changes according to the spectrum of the irradiated light. It is out. That is, the first background area 22 and the second background area 27 are hue change areas. On the other hand, the first picture area 21 contains the first ink 33 and the second picture area 26 contains the second ink 35. That is, the first picture area 21 and the second picture area 26 are non-hue change areas. In the third embodiment shown in FIG. 17 to FIG. 19, the same parts as those in the first embodiment shown in FIG. 1 to FIG. Moreover, when it is clear that the effect obtained in the first embodiment can be obtained in the present embodiment, the description thereof may be omitted.

  Next, with reference to FIG. 18 and FIG. 19, a method for confirming whether or not the securities composed of the medium 10 are genuine will be described. 18 is a plan view showing the image 12 when the first white light is irradiated, and FIG. 19 is a plan view showing the image 12 when the second white light is irradiated.

(At first white light irradiation)
First, the medium 10 is irradiated with first white light having the first emission spectrum 41. In this case, the first picture area 21 including the first ink 33 is visually recognized as a yellow portion Y1. On the other hand, the first background region 22 including the hue change ink 31 arranged around the first pattern region 21 is visually recognized as a pink portion Pm. Thus, when 1st white light is irradiated, the reflected light from the 1st pattern area | region 21 and the reflected light from the 1st background area | region 22 are visually recognized as light of a different color. As a result, as shown in FIG. 18, the first picture area 21 and the first background area 22 are discriminated. For this reason, an image “O” appears in the first image area 20.

  The second picture area 26 including the second ink 35 is visually recognized as a pink part P1. On the other hand, the second background region 27 including the hue change ink 31 arranged around the second picture region 26 is visually recognized as a pink portion Pm. Thus, when 1st white light is irradiated, the reflected light from the 2nd pattern area | region 26 and the reflected light from the 2nd background area | region 27 are visually recognized as light of the same color. As a result, as shown in FIG. 18, the second pattern area 26 and the second background area 27 are not distinguished. That is, the image “K” does not appear in the second image area 25.

(At the time of second white light irradiation)
Next, the medium 10 is irradiated with the second white light having the second emission spectrum 42. In this case, the first picture area 21 including the first ink 33 is visually recognized as a yellow portion Y2. On the other hand, the first background region 22 including the hue change ink 31 arranged around the first picture region 21 is visually recognized as a yellow portion Ym. Thus, when the second white light is irradiated, the reflected light from the first picture area 21 and the reflected light from the first background area 22 are visually recognized as light of the same color. As a result, as shown in FIG. 19, the first pattern area 21 and the first background area 22 are not distinguished. That is, the image “O” does not appear in the first image area 20.

  The second picture area 26 including the second ink 35 is visually recognized as a pink part P2. On the other hand, the second background region 27 including the hue change ink 31 arranged around the second picture region 26 is visually recognized as a yellow portion Ym. As described above, when the second white light is irradiated, the reflected light from the second picture region 26 and the reflected light from the second background region 27 are visually recognized as different colors. As a result, as shown in FIG. 19, the second pattern area 26 and the second background area 27 are discriminated. For this reason, an image “K” appears in the second image area 25.

  As described above, also in the present embodiment, as in the case of the first embodiment described above, the first image region 20 and the first image region 20 can be used regardless of which of the two types of white light sources of different types is used. Any one of the two image areas 25 can be hidden, and any one of the first image area 20 and the second image area 25 can be expressed. As a result, it is possible to suppress forgery of the securities composed of the medium 10.

  Further, according to the present embodiment, the first background region 22 of the first image region 20 and the second background region 27 of the second image region 25 both include the same hue change ink 31. Therefore, the first background area 22 and the second background area 27 are always visually recognized as the same color area. Therefore, when the first background region 22 and the second background region 27 are in contact with each other, the boundary line 15 a does not appear between the first image region 20 and the second image region 25. Accordingly, it is possible to make it difficult for the user of the medium 10 to notice that the image 12 can be divided into two regions, the first image region 20 and the second image region 25. This also can prevent the entire pattern of the image 12 from being clarified. As a result, it is possible to suppress forgery of the securities constituted by the medium 10.

  Further, according to the present embodiment, the first background region 22 and the second background region 27 that have a generally larger area than the first picture region 21 and the second picture region 26 include the hue change ink 31. For this reason, it becomes easier to notice that the region in which the image appears is switched according to the switching of the white light source than in the case of the second embodiment described above. As a result, it is possible to more easily check whether the medium 10 is genuine.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIGS.

  FIG. 20 is a plan view showing the image 12 in the present embodiment, and FIG. 21 is a cross-sectional view showing the image 12 of FIG. 20 viewed from the XXI-XXI direction. In the present embodiment, each of the first picture area 21, the first background area 22, the second picture area 26, and the second background area 27 includes a plurality of unit areas that are spaced apart from each other. In the fourth embodiment shown in FIGS. 21 to 23, the same parts as those in the first embodiment shown in FIGS. Moreover, when it is clear that the effect obtained in the first embodiment can be obtained in the present embodiment, the description thereof may be omitted.

  As shown in FIGS. 20 and 21, the first pattern area 21 and the first background area 22 include a plurality of dot areas 21 a and 22 a that are spaced apart from each other. In this case, the image “O” in the first image region 20 is formed as a latent image on the plurality of dot regions 21 a and 22 a that are two-dimensionally arranged. Specifically, as shown in FIGS. 20 and 21, the dot region 21 a existing at the position surrounded by the virtual boundary line 15 b that defines the image “O” includes the hue change ink 31. . On the other hand, the dot region 22 a existing outside the boundary line 15 b includes the first ink 33. Therefore, also in the present embodiment, as in the case of the first embodiment, the first pattern area 21 is a hue change area, and the first background area 22 is a non-hue change area. Further, the dot region 21 a including the hue change ink 31 and the dot region 22 a including the first ink 33 are not in contact with each other.

  Similarly, the second picture area 26 and the second background area 27 include a plurality of dot areas 26a and 27a that are spaced apart from each other. For this reason, the image “K” in the second image region 25 is formed as a latent image on the plurality of dot regions 26 a and 27 a that are two-dimensionally arranged. Specifically, as shown in FIGS. 20 and 21, the dot region 26 a existing at the position surrounded by the virtual boundary line 15 c that defines the image “K” includes the hue change ink 31. . On the other hand, the dot region 27 a existing outside the boundary line 15 c includes the second ink 35. Therefore, also in the present embodiment, as in the case of the first embodiment, the second pattern area 26 is a hue change area, and the second background area 27 is a non-hue change area. Further, the dot area 26 a including the hue change ink 31 and the dot area 27 a including the second ink 35 are not in contact with each other.

Each dot areas 21a, 22a, 26a, the dimension _{d 1} of 27a is preferably 300μm or less. Each dot areas 21a, 22a, 26a, at 27a, distance _{d 2} between two dots adjacent areas is preferably 100μm or less.

  Next, with reference to FIG. 22 and FIG. 23, a method for confirming whether the securities composed of the medium 10 are genuine will be described. FIG. 22 is a plan view showing the image 12 when the first white light is irradiated, and FIG. 23 is a plan view showing the image 12 when the second white light is irradiated.

(At first white light irradiation)
First, the medium 10 is irradiated with first white light having the first emission spectrum 41. In this case, each dot area 21a of the first picture area 21 is visually recognized as a pink part Pm. On the other hand, each dot region 22a of the first background region 22 is visually recognized as a yellow portion Y1. As described above, when the first white light is irradiated, the reflected light from each dot region 21a of the first pattern region 21 and the reflected light from each dot region 22a of the first background region 22 are visually recognized as different colors. The As a result, as shown in FIG. 22, a latent image “O” appears in the first image region 20 based on the difference in hue of the dot regions.

  Each dot area 26a of the second picture area 26 is visually recognized as a pink part Pm. In addition, each dot region 27a of the second background region 27 is also visually recognized as a pink portion P1. Thus, when the first white light is irradiated, the reflected light from each dot region 26a of the second pattern region 26 and the reflected light from each dot region 27a of the second background region 27 are visually recognized as light of the same color. The As a result, as shown in FIG. 22, the second pattern area 26 and the second background area 27 are not distinguished. That is, the latent image “K” does not appear in the second image area 25.

(At the time of second white light irradiation)
Next, the medium 10 is irradiated with the second white light having the second emission spectrum 42. In this case, each dot area 21a of the first picture area 21 is visually recognized as a yellow portion Ym. On the other hand, each dot region 22a of the first background region 22 is visually recognized as a yellow portion Y2. Thus, when the second white light is irradiated, the reflected light from each dot region 21a of the first pattern region 21 and the reflected light from each dot region 22a of the first background region 22 are visually recognized as light of the same color. The As a result, as shown in FIG. 23, the first pattern area 21 and the first background area 22 are not distinguished. That is, the latent image “O” does not appear in the first image area 20.

  Each dot area 26a of the second picture area 26 is visually recognized as a yellow portion Ym. On the other hand, each dot region 27a of the second background region 27 is visually recognized as a pink portion P2. In this way, when the second white light is irradiated, the reflected light from each dot region 26a of the second pattern region 26 and the reflected light from each dot region 27a of the second background region 27 are visually recognized as different colors. The As a result, as shown in FIG. 23, the second picture area 26 and the second background area 27 are discriminated, and therefore a latent image “K” appears in the second image area 25.

  As described above, also in the present embodiment, as in the case of the first embodiment described above, the first image region 20 and the first image region 20 can be used regardless of which of the two types of white light sources of different types is used. Any one of the two image areas 25 can be hidden, and any one of the first image area 20 and the second image area 25 can be expressed. As a result, it is possible to suppress forgery of the securities constituted by the medium 10.

Further, according to the present embodiment, the hue change ink 31 included in the first picture area 21 and the first ink 33 included in the first background area 22 are not in contact with each other. That is, when the second white light is irradiated, there is no portion where the yellow portion Ym and the yellow portion Y2 are in contact. For this reason, even if there is a slight color difference between the yellow portion Ym and the yellow portion Y2, the region between the yellow portion Ym and the yellow portion Y2 is prevented from being visually recognized as a boundary region. be able to. Further, since the hue change ink 31 and the first ink 33 are not in contact with each other, light is reflected or refracted at the boundary between the hue change ink 31 and the first ink 33 based on a difference in refractive index. There is no such thing. Also in this point, it can suppress that the area | region between the yellow part Ym and the yellow part Y2 is visually recognized as a boundary area | region.
Similarly, according to the present embodiment, the hue change ink 31 included in the second pattern area 26 and the second ink 35 included in the second background area 27 are not in contact with each other. That is, when the first white light is irradiated, there is no portion where the pink portion Pm and the pink portion P1 are in contact. For this reason, it can suppress that the area | region between the pink part Pm and the pink part P1 is visually recognized as a boundary area | region similarly to the case of the yellow part Ym and the yellow part Y2.
As a result, it is possible to further suppress the elucidation of the entire pattern of the first image region 20 and the second image region 25 of the image 12. Thereby, it is possible to further suppress forgery of the securities constituted by the medium 10.

(Modification)
In the present embodiment, an example is shown in which the unit areas included in the first picture area 21, the first background area 22, the second picture area 26, and the second background area 27 form a dot area. However, the present invention is not limited to this, and the unit area included in each of the areas 21, 22, 26, and 27 may form a micro character. In the example shown in FIG. 24, each of the areas 21, 22, 26, and 27 includes micro characters 21b, 22b, 26b, and 27b of “D”, “N”, and “P”, respectively. In this case, the images “O” and “K” in the first image region 20 and the second image region 25 are formed as latent images on the columns of the micro characters 21b, 22b, 26b, and 27b.

Each micro characters 21b, 22b, 26b, 27b dimension _{d 3} of, preferably not more than 300μm square. Each micro characters 21b, 22b, 26b, at 27b, distance _{d 4} between the two micro adjacent characters is preferably 100μm or less.

The resolution of the human eye with the naked eye varies depending on the visual acuity and the distance to the object. For example, the resolution limit that a human with visual acuity 1.5 can recognize at a clear visual distance of 250 mm is:
250 * tan (1 / 1.5 / 60) * 2 = 0.1 (mm)
It becomes.
The resolution limit here refers to a distance at which two adjacent points can be identified as two points. When the size of a micro character is set to 300 μm square or less, in many characters, the interval between lines constituting the character is about 100 μm, and usually cannot be identified as a character with the naked eye. Moreover, when the space | interval of a character is 100 micrometers or less, an adjacent character cannot be identified as a different character.

  Also in this modification, it is possible to suppress the elucidation of the entire pattern of the first image region 20 and the second image region 25 of the image 12 as in the case of the dot region described above. Thereby, it is possible to further suppress forgery of the securities constituted by the medium 10.

(Other variations)
In the present embodiment and the modification, an example is shown in which the first picture area 21 and the second picture area 26 are hue change areas, and the first background area 22 and the second background area 27 are non-hue change areas. . However, as in the case of the second embodiment described above, the first picture area 21 and the second background area 27 are configured as hue change areas, and the first background area 22 and the second picture area 26 are not changed in hue. It may be configured as a region. Similarly to the case of the third embodiment described above, the first background area 22 and the second background area 27 are configured as hue change areas, and the first picture area 21 and the second pattern area 26 are non-hue change areas. It may be configured as.

  Further, in each of the embodiments and modifications, the example in which the hue change area configured in the first image area 20 and the hue change area configured in the second image area 25 include the same hue change ink 31 is shown. However, the present invention is not limited to this, and the hue change ink included in the hue change area configured in the first image area 20 and the hue change ink included in the hue change area configured in the second image area 25 are included. May be different. This can further suppress the elucidation of the entire pattern of the image 12. Thereby, it is possible to further suppress forgery of the securities constituted by the medium 10. Examples of hue change inks that can be used in each embodiment and modification include “P8” and “CB7” manufactured by the same company in addition to the above-mentioned “CR8” of Stard Materials LLC.

  In each embodiment and modification, an example in which two types of white light having different emission spectra are used as light used for observing the medium 10 has been described. However, when the first light is irradiated, the reflected light from the first picture area 21 and the reflected light from the first background area 22 are visually recognized as different colors, and the reflected light from the second picture area 26 and The reflected light from the second background region 27 is visually recognized as light of the same color. On the other hand, when the second light is irradiated, the reflected light from the first picture region 21 and the reflected light from the first background region 22 are the same color. As long as the reflected light from the second picture area 26 and the reflected light from the second background area 27 are visually recognized as different colors, the type and spectrum of the first light and the second light are particularly There is no limit.

  In addition, although some modified examples with respect to the above-described embodiment have been described, naturally, a plurality of modified examples can be applied in combination as appropriate.

DESCRIPTION OF SYMBOLS 10 Medium 11 Base material 12 Image 20 1st image area 21 1st pattern area 22 1st background area 25 2nd image area 26 2nd pattern area 27 2nd background area 31 Hue change ink 33 1st ink 35 2nd ink 41 First emission spectrum 42 Second emission spectrum

Claims (13)

A medium having an image formed on a substrate,
The image has a first image region and a second image region;
The first image area includes a first picture area, and a first background area arranged around the first picture area,
The second image area includes a second picture area and a second background area arranged around the second picture area,
When the first light having the first emission spectrum is irradiated, the reflected light from the first picture area and the reflected light from the first background area are visually recognized as different colors, and the second picture area The reflected light from the second background region and the reflected light from the second background region are visually recognized as the same color light,
When the second light having the second emission spectrum different from the first emission spectrum is irradiated, the reflected light from the first picture area and the reflected light from the first background area are visually recognized as the same color light. And the reflected light from the said 2nd pattern area | region and the reflected light from the said 2nd background area | region are visually recognized as light of a different color. The first light is first white light emitted from a first white light source;
The medium according to claim 1, wherein the second light is second white light emitted from a second white light source.   The medium according to claim 2, wherein at least one of the first white light source and the second white light source is configured by a three-wavelength fluorescent lamp or a white LED. At least one of the first pattern area and the first background area is a hue change area in which the hue changes according to the spectrum of the irradiated light,
At least one of the second picture area and the second background area is a hue change area in which the hue changes according to the spectrum of the irradiated light,
Hue change area, the reflection spectrum, a negative peak which is convex from the base line below, 50 nm or less semi and has a height 0.5 times or more the depth of h ₀ Baseline 4. A medium according to any one of the preceding claims, defined as a region comprising a negative peak having a value range. One of the first picture area and the first background area is a hue change area, and the other is a non-hue change area,
One of the second pattern area and the second background area is a hue change area, and the other is a non-hue change area,
The non-hue change region does not include a negative peak whose reflection spectrum has a depth of 0.5 times or more of the baseline height h ₀ , or a negative spectrum whose reflection spectrum has a half width of 50 nm or less. 5. The medium of claim 4, defined as a region that does not include a peak. The first design area and the second design area are hue change areas,
The medium according to claim 5, wherein the first background area and the second background area are non-hue change areas. The first pattern area and the second background area are hue change areas,
The medium according to claim 5, wherein the first background area and the second pattern area are non-hue change areas. The first background area and the second background area are hue change areas,
The medium according to claim 5, wherein the first design area and the second design area are non-hue change areas.   The medium according to any one of claims 6 to 8, wherein each of the areas configured as the hue change area includes the same hue change ink whose hue changes according to a spectrum of light to be irradiated.   The hue change ink contained in at least one of the first picture area and the first background area is different from the hue change ink contained in at least one of the second picture area and the second background area. The medium of claim 4.   The said 1st pattern area | region, the said 1st background area | region, the said 2nd pattern area | region, and the said 2nd background area | region all contain the several unit area | region arrange | positioned mutually spaced apart. The medium according to any one of the above.   The medium according to claim 11, wherein the unit area forms a micro character. In the confirmation method of the medium on which the image is formed on the substrate,
The image of the medium has a first image region and a second image region;
The first image area includes a first picture area, and a first background area arranged around the first picture area,
The second image area includes a second picture area and a second background area arranged around the second picture area,
When the first light having the first emission spectrum is irradiated on the image of the medium, the reflected light from the first picture area and the reflected light from the first background area are visually recognized as different colors of light, and The reflected light from the second pattern area and the reflected light from the second background area are visually recognized as light of the same color,
When the second light having a second emission spectrum different from the first emission spectrum is irradiated on the image of the medium, the reflected light from the first picture area and the reflected light from the first background area are: The reflected light from the second pattern area and the reflected light from the second background area are visually recognized as light of the same color,
The method for checking the medium is as follows:
Preparing the medium;
Irradiating the medium with first light having a first emission spectrum, the first picture area of the first image area and the first background area are discriminated, and the second of the second image area Confirming that the pattern area and the second background area are not discriminated;
Irradiating the medium with the second light having the second emission spectrum, the first picture area of the first image area and the first background area are not distinguished, and the second image area of the second image area is not distinguished. And a step of confirming that the two pattern areas and the second background area are discriminated.