TWI793281B - Viewer for judging authenticity, photographing device, and method for judging authenticity - Google Patents

Abstract

A viewer for authenticity determination, which includes a linear polarizing plate and a phase difference plate disposed on one side of the linear polarizing plate in the thickness direction, at least one of the linear polarizing plate and the phase difference plate is arranged to be rotatable, and the linear polarizing plate The angle between the absorption axis and the slow axis of the phase difference plate can be switched between +45°±5° and -45°±5°.

Description

Viewer for judging authenticity, photographing device, and method for judging authenticity

The present invention relates to a viewer for judging authenticity, a photographing device, and a judging method for authenticity.

In order to determine the authenticity of an article provided by a regular manufacturer, an identification medium with a mark that cannot be easily copied is sometimes attached to the surface of the article. A resin having cholesterol regularity (hereinafter referred to as "cholesterol resin" as appropriate) is known as one of the materials used for such marking.

Cholesterol resins generally have the function of separating circularly polarized light. The "circular polarization separation function" refers to the function of allowing one of the right-handed circularly polarized light and the left-handed circularly polarized light to pass through, and to partially or completely reflect the other circularly polarized light. The reflection caused by the cholesteric resin is to keep the circularly polarized light in its palm shape and reflect it. In addition, the wavelength range in which the function of separating circularly polarized light is exerted in this way may be referred to as a "selective reflection band".

Therefore, the mark formed using the cholesteric resin shows a different image when observed through a right-handed circular polarizer and when observed through a left-handed circular polarizer. Therefore, the authenticity can be judged by the difference of the above-mentioned images (see Patent Documents 1 and 2). The observation for authenticity determination as described above is generally performed using two circular polarizers, a right-handed circular polarizer and a left-handed circular polarizer.

"Patent Documents" "Patent Document 1": Japanese Patent No. 3821940 "Patent Document 2": Japanese Patent Publication No. 2010-525343

In recent years, systems in which consumers and users can access information held by manufacturers through the Internet have become popular. In this system, for example, a user uses a camera such as a smartphone to take pictures of marks such as identifiers (barcodes, etc.) attached to products. The tagged information obtained from the captured image can be sent to the producer via the Internet. Then, the manufacturer returns the product information corresponding to the sent information (for example: detailed information of the product, related information, etc.) to the user. In this way, the user can obtain product information.

The inventors of the present invention have studied the use of the aforementioned system for authenticity determination. In order to determine the authenticity, it is required to draw a mark through cholesteric resin and take a picture of the mark with a photographic device equipped with a circular polarizing plate. However, it is conceivable that for general consumers and users, the preparation of a dedicated imaging device equipped with a circular polarizing plate is costly and becomes an obstacle to system introduction.

Furthermore, as mentioned above, in order to determine the authenticity of the mark formed by using cholesteric resin, the aforementioned imaging device is required to be capable of both: observation with a right-handed circular polarizer and observation with a left-handed circular polarizer. In order to meet this demand, it is considered to install both a right-handed circular polarizer and a left-handed circular polarizer in the imaging device. However, if two circular polarizing plates are used in this way, an area equivalent to these two sheets is required. Accordingly, it is conceivable that the size of the device becomes large and operability becomes insufficient.

The present invention was made in view of the aforementioned problems, and an object of the present invention is to provide a small-sized authenticity-judging viewer capable of marking marks formed using cholesteric resin by being mounted on the device body of a general-purpose photographing device. The photographing becomes possible; a photographing device comprising the aforementioned viewer for authenticity determination capable of photographing marks formed using cholesterol resin; and a method of authenticity determination using the aforementioned photographing device.

The present inventors devoted themselves to research in order to solve the foregoing problems. As a result, the present inventors have found that: a linear polarizer and a phase difference plate, at least one of the linear polarizer and the phase difference plate can be rotated, and the position between the absorption axis of the linear polarizer and the slow axis of the phase difference plate can be switched. The viewer of the angle can solve the aforementioned problems, and further complete the present invention.

Therefore, the present invention includes the following.

[1] A viewer for authenticity determination, comprising a linear polarizing plate and a phase difference plate provided on one side of the linear polarizing plate in the thickness direction, At least one of the aforementioned linear polarizer and the aforementioned retardation plate is provided to be rotatable, The angle formed by the absorption axis of the linear polarizer relative to the slow axis of the retardation plate can be switched between +45°±5° and −45°±5°.

[2] The viewer for authenticity determination described in [1], wherein the in-plane retardation of the retardation plate is 140 nm±40 nm.

[3] The viewer for authenticity determination according to [1] or [2], wherein the retardation plate has inverse wavelength dispersion.

[4] A photographing device for photographing an identification medium provided with a mark, the mark comprising a resin having cholesterol regularity, the photographing device comprising: A device body having a photographing unit, and the authenticity-judging viewer described in any one of [1] to [3] mounted on the photographing unit of the device body.

[5] A method for judging the authenticity of an identification medium, which is a method for judging the authenticity of an identification medium with a mark, the mark comprising a resin with cholesterol regularity, and the method for judging the authenticity includes: With the photography device as described in [4], under the condition that the angle between the absorption axis of the linear polarizer and the slow axis of the phase difference plate is at +45°±5°, the aforementioned identification medium is photographed to obtain the first image process; The process of photographing the aforementioned identification medium and obtaining a second image with the aforementioned imaging device under the condition that the angle formed by the absorption axis of the linear polarizer relative to the slow axis of the phase difference plate is at -45°±5°; and A process of judging the authenticity of the identification medium based on the first image and the second image.

According to the present invention, it is possible to provide: a small-sized authenticity-judgment viewer which, by being attached to the device body as a general-purpose photographing device, can photograph a mark formed using cholesteric resin; a photographing device A device comprising the aforementioned viewer for authenticity determination capable of photographing a mark formed using cholesteric resin; and a method of authenticity determination using the aforementioned imaging device.

Embodiments and examples are disclosed below to describe the present invention in detail. However, the present invention is not limited to the implementation forms and examples described below, and can be implemented with arbitrary changes without departing from the patent scope of the present invention and its equivalent scope.

In the following description, the so-called slow axis of the phase difference plate means the slow axis of the phase difference plate in the in-plane direction unless otherwise noted.

In the following description, the angle between the optical axes (absorption axis, transmission axis, slow axis, etc.) of the linear polarizer and the retardation plate means the angle viewed from the thickness direction of the linear polarizer unless otherwise noted. .

In the following description, "linear polarizing plate", "retardation plate" and "wavelength plate" include not only rigid members but also flexible members such as resin films, unless otherwise noted.

In the following description, the in-plane retardation Re of the retardation plate is a value represented by Re=(nx-ny)×d unless otherwise noted. Here, nx represents the refractive index in the direction perpendicular to the thickness direction of the phase difference plate (in-plane direction) and in the direction giving the maximum refractive index. ny represents the refractive index in the aforementioned in-plane direction of the phase difference plate and in a direction perpendicular to the nx direction. d represents the thickness of the phase difference plate.

In the following description, the directions of the so-called components are "parallel", "perpendicular" and "orthogonal". Unless otherwise noted, within the range that does not impair the effect of the present invention, for example, ±5° (that is, The error within the range of -5°～+5°).

[1. Implementation type]

FIG. 1 is a schematic perspective view of a viewer 100 for authenticity determination related to an implementation type of the present invention. Moreover, FIG. 2 is a schematic perspective view of the inspector 100 for authenticity determination related to an embodiment of the present invention through the casing 110 . In this FIG. 2, the housing 110 is indicated by a dotted chain line.

As shown in Fig. 1 and Fig. 2 , an inspector 100 for authenticity determination related to an embodiment of the present invention includes: a casing 110; a linear polarizer 120 accommodated in the casing 110; the difference plate 130 ; and the converting portion 140 disposed on the linear polarizer 120 . The linear polarizer 120 and the retardation plate 130 may also be in contact, but in this embodiment, an example in which the linear polarizer 120 and the retardation plate 130 are separated is disclosed.

The housing 110 has a cylindrical wall portion 111 , and forms an inner space surrounded by the wall portion 111 to form an optical path chamber 112 for accommodating the linear polarizer 120 and the phase difference plate 130 . In this embodiment, an example using a cylindrical housing 110 having a cylindrical optical path chamber 112 inside is disclosed. In addition, a long hole 113 penetrating through the wall portion 111 is formed in the wall portion 111 of the casing 110 . The elongated hole 113 is formed extending along the circumferential direction of the casing 110 .

The linear polarizer 120 is installed in the optical path chamber 112 of the housing 110 such that the in-plane direction of the linear polarizer 120 is parallel to the radial direction of the cylinder of the housing 110 . Therefore, the thickness direction of the linear polarizer 120 is parallel to the axial direction of the cylinder of the housing 110 . In this embodiment, an example of using a disc-shaped linear polarizer 120 is disclosed.

The linear polarizer 120 has an absorption axis. Therefore, the linear polarizer 120 can transmit linearly polarized light having a vibration direction perpendicular to the absorption axis, and shield linearly polarized light having a vibration direction parallel to the absorption axis. Here, the vibration direction of the linearly polarized light means the vibration direction of the electric field of the linearly polarized light.

The phase difference plate 130 is installed in the optical path chamber 112 of the housing 110 such that the in-plane direction of the phase difference plate 130 is parallel to the radial direction of the cylinder of the housing 110 . Therefore, the thickness direction of the phase difference plate 130 is parallel to the axial direction of the cylinder of the housing 110 and the thickness direction of the linear polarizer 120 . In addition, the phase difference plate 130 is disposed on one side of the linear polarizer 120 in the thickness direction so that light entering the optical path chamber 112 of the housing 110 can pass through the phase difference plate 130 and the linear polarizer 120 in sequence. In this embodiment, an example of using a disc-shaped phase difference plate 130 is disclosed.

The phase difference plate 130 has an in-plane retardation. The specific in-plane retardation of the retardation plate 130 is preferably set so that the circularly polarized light entering the viewer 100 can be converted into linearly polarized light or elliptically polarized light that can determine authenticity in the wavelength of the light used for authenticity determination. . The aforementioned "wavelength of light used for authenticity determination" specifically means the wavelength of the selective reflection band of the cholesteric resin contained in the mark observed using the viewer 100 . Therefore, the specific in-plane retardation of the retardation film 130 is preferably set so that the retardation film 130 can function as a 1/4 wavelength plate in the selective reflection band of the cholesteric resin contained in the mark.

Especially in an aspect that meets expectations, the in-plane retardation of the retardation plate 130 is preferably 140 nm±40 nm (ie, 100 nm˜180 nm) at a measurement wavelength of 560 nm. In more detail, the in-plane retardation of the retardation plate 130 at a measurement wavelength of 560 nm is preferably greater than 100 nm, more preferably greater than 120 nm, more preferably greater than 130 nm, and preferably less than 180 nm. It is preferably below 160 nm, especially preferably below 150 nm. The retardation plate 130 having an in-plane retardation in the aforementioned range at a measurement wavelength of 560 nm can generally function as a 1/4 wavelength plate in the visible wavelength region. Accordingly, by using such a retardation plate 130, the viewer 100 usable in the visible light wavelength range can be realized.

The retardation plate 130 preferably has reverse wavelength dispersion. The inverse wavelength dispersion here means that the in-plane retardation Re(450) and Re(560) satisfy the following formula (1) at the measurement wavelengths of 450 nm and 560 nm. Re(450)<Re(560) (1)

The retardation plate 130 having inverse wavelength dispersion can exhibit its optical function in a wide wavelength range. Accordingly, by using the retardation plate 130 having inverse wavelength dispersion properties, the viewer 100 usable in a wide wavelength range can be realized.

The phase difference plate 130 has a slow axis in the in-plane direction of the phase difference plate 130 . When the angle between the slow axis of the retardation film 130 and the absorption axis of the linear polarizer 120 is set to approximately 45°, the combination of the linear polarizer 120 and the retardation film 130 can function as a circular polarizer.

In the above-mentioned embodiments, at least one of the linear polarizer 120 and the retardation plate 130 is configured to be rotatable. Moreover, the range of such rotation is to switch the polarizing plate 120 between +45°±5° (that is, +40°～+50°) and -45°±5° (that is, -50°～-40°). The angle θ formed by the absorption axis relative to the slow axis of the phase difference plate 130 is set in such a manner. The positive and negative signs of the aforementioned angle θ indicate the direction of rotation. Therefore, when the angle θ is positive and the angle θ is negative, the direction of the angle θ between the absorption axis of the linear polarizer 120 and the slow axis of the phase difference plate 130 is opposite.

3 and 4 are schematic diagrams showing the linear polarizer 120 and the retardation plate 130 included in the inspector 100 for authenticity determination related to an embodiment of the present invention, respectively. In FIGS. 3 and 4 , a straight line L130 extending in the same direction as the slow axis A130 of the phase difference plate 130 is indicated by a two-dot chain line. FIG. 3 shows an example in which the absorption axis A120 of the linear polarizer 120 forms an angle θ counterclockwise with respect to the slow axis A130 of the phase difference plate 130 . Moreover, FIG. 4 shows an example in which the absorption axis A120 of the linear polarizer 120 forms an angle θ clockwise with respect to the slow axis A130 of the phase difference plate 130 . In this case, the sign of the angle θ shown in FIG. 3 is one of positive and negative, and the sign of the angle θ shown in FIG. 4 is the other of positive and negative.

In the case of the aforementioned angle θ being +45°±5°, the angle θ is preferably +45°±4° (that is, +41°～+49°), and +45°±3° (that is, +42°～+48°) More preferably, +45°±2° (that is, +43°～+47°) is especially preferred. Moreover, in the case where the aforementioned angle θ is -45°±5°, the angle θ is preferably -45°±4° (that is, -49°～-41°), and -45°±3° (also That is, -48° to -42°) is better, and -45°±2° (ie -47° to -43°) is especially preferable. When the angle θ is within the aforementioned range, it is easy to clarify the difference between the first image and the second image to be described later, so authenticity can be easily determined.

In this embodiment, as shown in FIG. 1 and FIG. 2 , an example in which the linear polarizing plate 120 is rotatable around the rotation axis R120 passing through the disc-shaped center of the linear polarizing plate 120 and parallel to the thickness direction of the linear polarizer 120 . However, the aforementioned rotation axis R120 is described to indicate the rotation direction of the linear polarizer 120 , and does not necessarily have to be formed by specific components.

Further, a rod-shaped conversion portion 140 is provided on the edge portion 120E of the linear polarizing plate 120 so as to protrude in the radial direction of the linear polarizing plate 120 . The converting portion 140 passes through the long hole 113 formed in the wall portion 111 of the casing 110 . Furthermore, the conversion part 140 is provided so as to be able to move along the elongated hole 113 . Accordingly, the conversion part 140 is configured such that by moving the conversion part 140 in the circumferential direction of the casing 110 along the long hole 113 , the linear polarizer 120 can be rotated as much as the conversion part 140 moves.

The conversion part 140 is provided so that the end part of the elongated hole 113 in the extension direction may hit the wall part 111 and stop. In this case, the positions of both ends of the elongated hole 113 in the extending direction are preferably set so as to satisfy the following requirements (A1) and (A2). (A1) When the conversion portion 140 is located at one end of the long hole 113, the angle θ is +45°±5°. (A2) When the conversion portion 140 is located at the other end of the elongated hole 113 , the angle θ is −45°±5°.

When the positions of both ends of the elongated hole 113 are set in this way, when the conversion part 140 stops at one end of the elongated hole 113, the angle θ becomes +45°±5°. And, when the conversion part 140 stops at the other end of the long hole 113, the angle θ becomes -45°±5°. Accordingly, the conversion part 140 is provided so that switching of the angle θ by the movement of the conversion part 140 can be easily performed.

The viewer 100 related to this embodiment has the above-mentioned structure. Therefore, the light entering the optical path chamber 112 of the casing 110 of the viewfinder 100 can pass through the phase difference plate 130 and the linear polarizer 120 in sequence. In the case that the aforementioned light is circularly polarized light, the circularly polarized light will be transformed into linearly polarized light by passing through the phase difference plate 130 , and enter the linearly polarized light plate 120 . In the case where the vibration direction of the linear polarized light is perpendicular to the absorption axis of the linear polarizer 120 , the linear polarized light can pass through the linear polarizer 120 . On the other hand, if the vibration direction of the linear polarized light is parallel to the absorption axis of the linear polarizer 120 , the linear polarized light cannot pass through the linear polarizer 120 . In this way, the function as a circular polarizer can be obtained by combining the linear polarizer 120 and the retardation plate 130 .

Moreover, the above-mentioned viewer 100 can switch between +45°±5° and -45°±5° between +45°±5° and -45°±5° by rotating the linear polarizer 120 . The angle θ. When the angle θ is one of +45°±5° and −45°±5°, the vibration direction of the linearly polarized light passing through the retardation plate 130 becomes perpendicular to the absorption axis of the linear polarizer 120 . Also, when the angle θ is the other of +45°±5° and −45°±5°, the vibration direction of the linearly polarized light passing through the retardation plate 130 becomes parallel to the absorption axis of the linear polarizer 120 . Accordingly, in the aforementioned viewer 100 , the circularly polarized light shielded by the viewer 100 can be easily switched to right-handed circularly polarized light and left-handed circularly polarized light by switching the angle θ. Therefore, by using the viewer 100, the authenticity of the mark using the cholesteric resin can be smoothly judged.

Furthermore, the aforementioned inspector 100 can implement a circular polarizing plate capable of both the function of shielding right-handed circularly polarized light and the function of shielding left-handed circularly polarized light by combining at least one set of linear polarizers 120 and retardation plates 130 . In this way, the viewer 100 related to this embodiment, which uses the area of one circular polarizing plate that passes through the combination of the linear polarizing plate 120 and the phase difference plate 130 to determine the authenticity, compared to using two circular polarizing plates (also That is, the conventional viewer of the right-handed circular polarizer and the left-handed circular polarizer), the area can be reduced as much as the number of circular polarizers is reduced. Therefore, the viewer 100 according to this embodiment can be miniaturized.

Next, an example is disclosed to illustrate the authenticity determination method using the viewer 100 . FIG. 5 is a schematic perspective view showing an example of a situation when judging the authenticity of the identification medium 200 attached to the article 10 .

In this example, as shown in FIG. 5 , by judging the authenticity of the identification medium 200 , the authenticity of the item 10 with the identification medium 200 is determined.

FIG. 6 is a schematic cross-sectional view showing a cross-section of an identification medium 200 related to the aforementioned example. In FIG. 6 , the path of light reflected by the mark 230 is schematically shown. In addition, in the actual identification medium 200, in addition to the following descriptions, various kinds of light absorption and reflection may also occur, but in the following descriptions, the main light paths are briefly described for the convenience of explaining the functions. . In addition, in the example shown in FIG. 6 , a mark 230 is provided that includes a cholesteric resin that reflects a part of right-handed circularly polarized light (specifically, light rays in a selective reflection band) in the visible light region, making right-handed circularly polarized light The rest of the circularly polarized light and all of the left-handed circularly polarized light are transmitted.

As shown in FIG. 6 , the identification medium 200 sequentially includes a base material 210 , a base layer 220 disposed on the base material 210 , and a mark 230 comprising cholesterol resin disposed on the base layer 220 . When light L including right circularly polarized light is incident on the upper side of the mark 230 , part of the right circularly polarized light is reflected by the mark 230 to become reflected light LR, and the rest becomes transmitted light LL. Here, reflection may occur not only on the surface of the mark 230 but also inside, but as a schematic presentation, in FIG. 6 , the reflection is shown as occurring on the surface of the mark 230 .

In the authenticity determination method disclosed in this example, as shown in FIG. 5 , a device body 310 with a photographing unit (not shown) capable of photographing the identification medium 200 as the subject is prepared. FIG. 5 shows a smartphone having a lens unit as a camera unit as such a device body 310 . The above-mentioned viewer 100 is attached to the imaging unit of the device main body 310 . At this time, the viewer 100 is mounted so that the linear polarizer 120 and the retardation plate 130 are arranged in order from the imaging unit side. In this way, the photographing device 300 including the device body 310 and the viewer 100 is prepared as a device for photographing the identification medium 200 .

After the photography device 300 is prepared in this way, the identification medium 200 is photographed by the photography device 300 . Specifically, do: With the imaging device 300, the identification medium 200 is photographed under the condition that the angle θ between the absorption axis A120 of the linear polarizer 120 and the slow axis A130 of the phase difference plate 130 is at +45°±5°, and the first image is obtained. process; with With the imaging device 300, the identification medium 200 is photographed to obtain the second image when the angle θ between the absorption axis A120 of the linear polarizer 120 and the slow axis A130 of the phase difference plate 130 is at -45°±5°. process. Whichever of these two processes can be carried out first is all right.

More specifically, the identification medium 200 is photographed by the photographing device 300 in a state where the conversion part 140 of the viewer 100 is moved to one end of the long hole 113 formed in the casing 110 . Thereby, imaging can be performed in a state where the angle θ is at one of +45°±5° and −45°±5°. Then, by moving the conversion part 140 to the other end of the long hole 113, the angle θ is switched between +45°±5° and −45°±5°. Afterwards, in this state, the identification medium 200 is photographed by the photographing device 300 . In this way, according to the imaging device 300 provided with the viewer 100, the first image and the second image can be easily obtained.

During the aforementioned photography, the reflected light LR that is right-handed circularly polarized light is converted by the retardation plate 130 into a light that is linearly polarized with the angle θ at one of +45°±5° and -45°±5°. The linear polarized light in the vibration direction perpendicular to the absorption axis A120 of the plate 120 can pass through the linear polarizing plate 120 . Accordingly, the mark 230 appears on the image captured by the viewer 100 .

However, the reflected light LR, which is right-handed circularly polarized light, is converted by the phase difference plate 130 to have the same shape as the linear polarizer 120 when the angle θ is at the other of +45°±5° and −45°±5°. The linearly polarized light parallel to the vibration direction of the absorption axis A120 is shielded by the linear polarizer 120 . Accordingly, the mark 230 does not appear on the image captured by the viewer 100 .

Therefore, different images appear in the first image and the second image. Specifically, the mark 230 appears in one of the first image and the second image, but does not appear in the other of the first image and the second image.

After the first image and the second image are obtained in this way, a process of judging the authenticity of the identification medium 200 is performed based on the first image and the second image. Specifically, in the case where there is the above-mentioned difference between the first image and the second image, it can be determined that the identification medium 200 is authentic, and therefore, it can be determined that the article 10 with this identification medium 200 is authentic. product. On the other hand, in the case where there is no difference as described above between the first image and the second image, it can be determined that the identification medium 200 is not real, and therefore, it can be determined that the article 10 with this identification medium 200 is counterfeit.

Moreover, in the process of determining the authenticity of the identification medium 200, the authenticity can also be determined by comparing the first image and the second image. In the case of photographing the real identification medium 200 , usually there will be a contrast difference between the first image and the second image depending on whether the mark 230 appears. Accordingly, authenticity can also be determined by comparing the difference instead of the difference caused by the presence or absence of the mark 230 . Specifically, in the case of a contrastive difference between the first image and the second image, it can be determined that the identification medium 200 is authentic. On the other hand, in the case of no contrasting difference between the first image and the second image, it may be determined that the identification medium 200 is not real.

In the case where the photographing device 300 has a display unit that displays the first image and the second image, the aforementioned determination may also be performed by the user. In this case, the user can judge the authenticity by viewing the first image and the second image displayed on the display unit.

In addition, in the case where the imaging device 300 has a transmission unit that transmits the information of the first image and the second image, the determination may be performed at the server by receiving the transmission of the information. In this case, the authenticity judgment is performed on the server according to the information of the first image and the second image, and the result is sent back to the user, so that the user can know the authenticity judgment result.

One embodiment of the present invention has been described above, but the above-mentioned embodiment may be modified and implemented.

For example, the shape of the casing 110 is not limited to a cylindrical shape, and can also be other shapes. And, for example, the casing 110 may not be provided on the viewer 100 . To give a specific example, instead of the case 110 accommodating the linear polarizer 120 and the retardation plate 130 , a frame material supporting the linear polarizer 120 and the retardation plate 130 may be used.

For example, the shapes of the linear polarizer 120 and the retardation plate 130 are not limited to the shape of a circular plate, and may be other shapes.

For example, the phase difference plate 130 may be configured to be rotatable, and both the linear polarizer 120 and the phase difference plate 130 may be configured to be rotatable. In the case where the linear polarizer 120 can be rotated relative to the phase difference plate 130, the absorption axis of the linear polarizer 120 relative to the phase difference plate 130 can be switched between +45°±5° and −45°±5° as described above. The angle θ between the slow axis of .

For example, the conversion unit 140 may not be provided in the viewer 100 . To give a specific example, when the user grasps and rotates the linear polarizing plate 120 or the retardation plate 130 , the conversion unit 140 is not required.

For example, components other than the housing 110 , the linear polarizer 120 , the retardation plate 130 , and the conversion unit 140 may be provided on the viewer 100 . To give a specific example, cover members may also be provided at the entrance and exit of the optical path chamber 112 of the casing 110 . To give another specific example, a fixture for assembling the viewer 100 to be detachable from the device body 310 may also be provided on the housing 110 . To give yet another specific example, a spacer that suppresses contact between the linear polarizer 120 and the retardation plate 130 may be provided.

For example, the identification medium 200 may not have the base material 210 or the base layer 220 . The above-mentioned authenticity determination can be carried out if there is a mark 230 containing cholesterol resin. Accordingly, even in the case where, for example, the mark 230 including cholesterol resin is directly formed on the surface of the article 10, the aforementioned determination of authenticity can be performed.

For example, as the device body 310 , a mobile phone, a tablet terminal, a digital camera, a network camera, a personal computer with a built-in camera, etc. may also be used.

In the above-mentioned embodiments, an example is disclosed in which the circularly polarized light entering the viewer 100 is transformed into linearly polarized light by the phase difference plate 130, but as long as the authenticity can be judged, for example, the circularly polarized light entering the viewer 100 can be converted into linearly polarized light by the phase difference. The difference plate 130 converts into elliptically polarized light. Even in the case where circularly polarized light is converted into elliptically polarized light by the retardation plate 130, usually the elliptical polarized light can pass through the linear polarizing plate 120 to the extent that the angle θ is at +45°±5° and the angle θ is at -45° The case of ±5° is different. Accordingly, like the above-mentioned embodiment, if the identification medium 200 is authentic, there will be a difference between the first image and the second image, so authenticity can be determined.

In the above-mentioned embodiments, the viewer 100 that can penetrate or shield all the reflected light LR on the mark 230 is disclosed as an example, but as long as the authenticity can be judged, for example, a viewer that can penetrate or shield a part of the reflected light LR can also be used. The viewer 100 is used for judgment.

[2. Linear polarizer]

As the linear polarizer, for example, a film provided with a linear polarizer can also be used. As the linear polarizer, it is possible to use, for example, one that has been subjected to appropriate treatments such as dyeing treatment, stretching treatment, and cross-linking treatment using dichroic substances in an appropriate order and method on an appropriate vinyl alcohol-based polymer film. film. Examples of the vinyl alcohol polymer include polyvinyl alcohol, partially formalized polyvinyl alcohol, and the like. Moreover, as a dichroic substance, iodine, a dichroic dye, etc. are mentioned, for example. Among them, a linear polarizer containing a dichroic dye is preferable from the viewpoint of improving heat resistance. In addition, the linear polarizer may also be provided with a polarizer protective film combined with the linear polarizer. The linear polarizing plate is preferably one with an excellent degree of polarization. The thickness of the linear polarizing plate is generally 5 μm to 80 μm, but it is not limited thereto.

[3. Phase difference plate]

As the phase difference plate, for example, a stretched film can be used. Stretched film is a film obtained by stretching a resin film, and by properly adjusting the type of resin, stretching conditions, thickness and other factors, any in-plane retardation can be obtained.

As the resin, a thermoplastic resin is generally used. The thermoplastic resin may contain polymers and optional components as required. Examples of polymers include polycarbonate, polyethersulfone, polyethylene terephthalate, polyimide, polymethyl methacrylate, polysulfide, polyarylate, polyethylene, polyphenylene ether, Polystyrene, polyvinyl chloride, cellulose diacetate, cellulose triacetate and polymers containing alicyclic structures, etc. Moreover, a polymer may be used individually by 1 type, and may use it combining 2 or more types by arbitrary ratios. Among these, alicyclic structure-containing polymers are suitable from the viewpoints of transparency, low hygroscopicity, dimensional stability, and processability. The alicyclic structure-containing polymer is a polymer having an alicyclic structure in a main chain and/or a side chain, for example, those described in Japanese Patent Laid-Open No. 2007-057971 can be used.

The stretched film of the phase difference plate can be produced by stretching the resin film after producing the resin film from the aforementioned resin.

Examples of methods for producing the resin film include casting molding, inflation molding, and extrusion molding, among which extrusion molding is preferred.

The stretching treatment can be performed by, for example, a roll method, a suspension method, a tenter method, and the like. In the stretching process, the stretching direction is preferably appropriately set so that the slow axis of the stretched film becomes a desired direction. Therefore, depending on the direction of the slow axis in which the stretched film is to appear, the stretching process can be stretching in the width direction of the resin film (transverse stretching), stretching in the long side direction (longitudinal stretching), or conventional stretching. The oblique extension which is neither the width direction nor the longitudinal direction may be a combination of these extensions.

The stretching temperature and stretching ratio can be set arbitrarily within a range in which desired in-plane retardation can be obtained. To give a specific range, the stretching temperature is preferably above Tg-30°C, preferably above Tg-10°C, preferably below Tg+60°C, and preferably below Tg+50°C. In addition, the elongation ratio is preferably at least 1.1 times, more preferably at least 1.2 times, more preferably at least 1.5 times, preferably at most 30 times, preferably at most 10 times, and most preferably at most 5 times. . Here, Tg represents the glass transition temperature of resin.

The thickness of the stretched film is not particularly limited, but it is preferably at least 5 μm, more preferably at least 10 μm, particularly preferably at least 20 μm, preferably less than 1 mm, preferably less than 500 μm, and 200 μm or less is preferred.

As the retardation plate, for example, a film including a liquid crystal solidified layer can be used. The so-called liquid crystal solidified layer is a layer body formed of a cured product of a liquid crystal composition including a liquid crystal compound. Here, the material called "liquid crystal composition" cheaply includes not only a mixture of two or more substances but also a material composed of a single substance. Usually, after forming a layer of the liquid crystal composition and aligning the molecules of the liquid crystal compound contained in the layer of the liquid crystal composition, the layer of the liquid crystal composition is solidified to obtain a liquid crystal solidified layer. The liquid crystal solidified layer can obtain any in-plane retardation by properly adjusting the type of liquid crystal compound, the alignment state of the liquid crystal compound, thickness and other factors.

The type of liquid crystal compound is arbitrary, but in the case of obtaining a retardation plate having reverse wavelength dispersion, it is preferable to use a reverse wavelength dispersion liquid crystal compound. The term "reverse wavelength dispersion liquid crystal compound" refers to a liquid crystal compound that exhibits reverse wavelength dispersion when aligned uniformly. In addition, the so-called homogeneous alignment of the liquid crystal compound means forming a layer containing the liquid crystal compound, and making the long axis direction of the mesogen of the molecules of the liquid crystal compound in the layer parallel to the surface of the layer oriented in a certain direction. Specific examples of reverse wavelength dispersion liquid crystal compounds include, for example, compounds described in International Patent Publication No. 2014/069515, International Patent Publication No. 2015/064581, and the like.

The thickness of the liquid crystal solidified layer is not particularly limited, but it is preferably above 0.5 μm, preferably above 1.0 μm, preferably below 10 μm, preferably below 7 μm, and most preferably below 5 μm .

[4. Marking]

The mark observed by the viewer includes cholesteric resin. Cholesterol resin is a resin having cholesterol regularity as described above. The so-called regularity of cholesterol is like "on a certain plane inside the resin, the molecular axes are arranged in a fixed direction, but the directions of the molecular axes on the plane overlapping with it are slightly staggered, and the angles are even more staggered on the next plane. "Generally, a structure in which the angles of the molecular axes in the planes are staggered (twisted) as the sequential penetration proceeds through overlapping planes. That is, when the molecules inside the layer of a certain material have cholesterol regularity, the molecules are arranged on a certain first plane inside the layer so that the molecular axis becomes a fixed direction. On a second plane inside the layer body that overlaps the first plane, the direction of the molecular axes is slightly offset from the direction of the molecular axes in the first plane. On a third plane further overlapping the second plane, the directions of the molecular axes are further angularly offset from the directions of the molecular axes in the second plane. In this way, in the overlapping and arranged planes, the angles of the molecular axes in the planes are sequentially staggered (twisted). Such a structure in which the direction of the molecular axis is gradually twisted is usually a helical structure and becomes an optical chiral structure. Since the cholesteric resin has the function of separating circularly polarized light, the mark can reflect circularly polarized light corresponding to the color light of the selective reflection band of the cholesteric resin.

As the cholesteric resin, for example, a cured product of a cholesteric liquid crystal composition can be used. The cholesteric liquid crystal composition refers to a composition in which the liquid crystal compound can exhibit a cholesteric regular liquid crystal phase (cholesteric liquid crystal phase) when the liquid crystal compound contained in the liquid crystal composition is oriented. When the cholesteric liquid crystal composition is cured, the liquid crystal compound is usually polymerized in a state where the cholesteric liquid crystal phase is present, so that a non-liquid crystalline cholesteric resin layer that exhibits cholesterol regularity and is cured can be obtained.

As the cholesteric resin that is a cured product of the cholesteric liquid crystal composition, for example, those described in JP-A-2014-174471 and JP-A-2015-27743 can be used.

Markers can usually be formed as a layer containing cholesteric resin. Such a mark, for example, can be formed into a layer having a desired planar shape and provided on an identification medium such as a label. In this case, the mark can be attached to the article by attaching the aforementioned identification medium to the article. In addition, the mark can also be formed by drawing a desired planar shape on an article using, for example, a paint containing "a pigment containing a layer containing a cholesteric resin".

There is no limitation on the object as the target to be marked, and a wide range of objects can be employed. Examples of such articles include: cloth products such as clothing; leather products such as leather bags and shoes; metal products such as screws; paper products such as price tags; rubber products such as tires; however, the articles are not limited to these examples. .

10‧‧‧items 100‧‧‧Viewer 110‧‧‧Shell 111‧‧‧wall 112‧‧‧light path room 113‧‧‧long hole 120‧‧‧Linear polarizer 130‧‧‧Phase plate 140‧‧‧Transformation Department 200‧‧‧identify media 210‧‧‧Substrate 220‧‧‧Base layer 230‧‧‧mark 300‧‧‧Photography installation 310‧‧‧Device body A120‧‧‧absorption shaft A130‧‧‧Slow axis R120‧‧‧rotation shaft

<FIG. 1> FIG. 1 is a schematic perspective view of a viewer for authenticity determination related to an implementation type of the present invention.

<Fig. 2> Fig. 2 is a three-dimensional schematic diagram of a viewer for authenticity determination related to an embodiment of the present invention through the casing.

<FIG. 3> FIG. 3 is a schematic diagram showing a linear polarizer and a phase difference plate included in an inspector for authenticity determination related to an embodiment of the present invention.

<FIG. 4> FIG. 4 is a schematic diagram showing a linear polarizer and a phase difference plate included in an inspector for authenticity determination related to an embodiment of the present invention.

<FIG. 5> FIG. 5 is a schematic perspective view showing an example of the situation when judging the authenticity of the identification medium attached to the article.

<Fig. 6> Fig. 6 is a schematic cross-sectional view showing a cross-section of an example of a relevant identification medium.

100‧‧‧Viewer

110‧‧‧Shell

111‧‧‧wall

112‧‧‧light path room

113‧‧‧long hole

120‧‧‧Linear polarizer

120E‧‧‧edge

130‧‧‧Phase plate

140‧‧‧Transformation Department

R120‧‧‧rotation shaft

Claims (4)

A photographing device for photographing an identification medium provided with a mark, the mark comprising a resin having cholesterol regularity, the photographing device comprising: a device body having a photographing part, and a photographing device mounted on the device body The inspector for authenticity judgment of the section, the inspector for authenticity judgment is equipped with a linear polarizing plate and a retardation plate disposed on one side of the thickness direction of the linear polarizing plate, at least one of the linear polarizing plate and the retardation plate One is set to be able to rotate, and the angle between the absorption axis of the aforementioned linear polarizing plate and the slow axis of the aforementioned phase difference plate can be switched between +45°±5° and -45°±5° for authenticity determination The viewer, the above-mentioned photographing device is further equipped with: it is possible to photograph the above-mentioned identification medium under the condition that the angle formed by the absorption axis of the above-mentioned linear polarizing plate relative to the slow axis of the above-mentioned retardation plate is at +45°±5°. The first image and the angle between the absorption axis of the linear polarizing plate and the slow axis of the retardation plate are at -45°±5°, and the identification medium is captured to obtain the second image and sent to the server of the transmission department. The imaging device according to claim 1, wherein the in-plane retardation of the retardation plate is 140nm±40nm. The imaging device according to claim 1 or 2, wherein the retardation plate has inverse wavelength dispersion. A method for judging the authenticity of an identification medium, which is a method for judging the authenticity of an identification medium with a mark, the mark comprising a resin with cholesterol regularity, and the method for judging the authenticity includes: by claim 1 The photographic device described in any one of to 3, under the condition that the angle between the absorption axis of the linear polarizing plate and the slow axis of the phase difference plate is at +45°±5°, the aforementioned identification medium is photographed to obtain the first The process of image: by means of the above-mentioned photographing device, under the condition that the angle between the absorption axis of the linear polarizer and the slow axis of the retardation plate is at -45°±5°, the above-mentioned identification medium is photographed to obtain the second image process; and the process of judging the authenticity of the aforementioned identification medium based on the aforementioned first image and the aforementioned second image, which includes transmitting the aforementioned first image and the aforementioned second image intermediary transmission unit to the server, and the aforementioned determination is performed on the aforementioned server In progress, receive the result of the aforementioned determination sent back by the server.

Images