WO2020196317A1

WO2020196317A1 - Authentication device and film

Info

Publication number: WO2020196317A1
Application number: PCT/JP2020/012450
Authority: WO
Inventors: 遠山秀旦; 松居久登; 合田亘
Original assignee: 東レ株式会社
Priority date: 2019-03-28
Filing date: 2020-03-19
Publication date: 2020-10-01
Also published as: TW202104949A; CN113574427B; KR20210143754A; JPWO2020196317A1; CN113574427A

Abstract

The present invention addresses the problem of providing an authentication device in which authentication performance thereof is not dependent on an alignment angle of a film. This authentication device has a light source, a polarizer, a film, and a photosensitive sensor, wherein the film having specific characteristics is disposed between the polarizer and an object to be authenticated.

Description

Authentication devices and films

The present invention relates to an authentication device having a light source, a polarizer, a film, and a light sensitivity sensor.

With the development of image processing technology and data analysis technology in recent years, various authentication systems have been put into practical use. In particular, biometric authentication devices such as fingerprint authentication, iris authentication, vein authentication, and face authentication have been improved in accuracy and cost reduction, and are beginning to be used in various electronic products such as mobile phones and vehicles. Since it is expected that it will be used in vehicles and electronic payments in the future, there is a demand for an authentication device that has further accuracy, lower cost, and durability for long-term use.

As shown in Patent Document 1, in general, an optical authentication device irradiates an object to be authenticated with light emitted from a light source, receives and images the reflected light with a light sensitivity sensor, and preliminarily captures a patterned image. Authentication is performed by matching with the registered pattern. In such an authentication device, if light other than that emitted from the light source is incident, it causes erroneous authentication. Therefore, in many cases, a polarizing element is used to suppress the reflection of external light. Moreover, by using a film of a thermoplastic resin such as polyester or polycarbonate for the outermost layer, deterioration of the authentication function due to breakage or scratches is prevented.

International Publication No. 2017/126153

However, if the film has polarization or optical rotation, the light from the light source is polarized / rotated, and as a result, the polarized / rotated light is blocked by the polarizer before reaching the light sensitivity sensor. The problem of reduced sex arises.

There are two possible countermeasures for this problem. The first method is to use an unstretched or slightly stretched film such as optically isotropic polycarbonate as a protective film. However, a film having a low draw ratio is easily broken and has difficulty in impact resistance. Further, a polycarbonate film having high impact resistance has a problem that it is expensive.

The second method is to use an oriented polyester film as a protective film and make the main alignment axis of the oriented polyester film parallel to the transmission axis of the polarizer to substantially eliminate the polarization of the protective film. However, such a method has a problem that if the direction of the main orientation axis and the transmission axis of the polarizer deviate by only a few degrees, the polarization property becomes apparent and the authenticity is lowered.

In addition, in an authentication device that uses an OLED (Organic Light Emitting Diode) as a light source, deterioration of the OLED due to ultraviolet rays or the like is a bottleneck for long-term use, and improving the durability of the OLED is the useful life of the authentication device. This is an issue that is directly linked to improvement.

The present invention is intended to solve the above problems, and an object of the present invention is to provide an authentication device in which the authenticity does not depend on the orientation angle of the film.

The present invention is intended to solve the above problems. That is, it is an authentication device having a light source, a polarizer, a film, and a light sensitivity sensor, and the film is arranged between the polarizer and the object to be authenticated, and satisfies the following (1) and (2). It is a characteristic authentication device.
(1) The transmittance of the light beam emitted from the light source is 70% or more and 100% or less at the wavelength of the strongest intensity of the light ray.
(2) There is an integer n that satisfies the following equation (I).
(I) A × n-150 ≦ Re ≦ A × n + 150
Here, A is the wavelength (nm) showing the strongest intensity in the light beam emitted from the light source, and Re is the wavelength when the film is measured at a wavelength of 587.8 nm at an incident angle of 0 ° using the parallel Nicol rotation method. In-plane phase difference (nm).

According to the present invention, it is possible to provide an authentication device whose authenticity does not depend on the orientation angle of the film. In addition, an inexpensive film can be used, and the durability of the light source and the impact resistance of the screen can be improved.

It is a figure which shows typically an example of the structure of the authentication device of this invention. It is a figure which shows an example of the movement of light used for authentication in the authentication device of this invention.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not construed as being limited to embodiments including the following examples, and the object of the invention can be achieved and the gist of the invention can be achieved. Of course, various changes can be made without departing from the above.

The authentication device of the present invention is an authentication device having a light source, a polarizer, a film, and a light sensitivity sensor, and a film satisfying the following (1) and (2) is arranged between the polarizer and the object to be authenticated. Authentication device.
(1) The film has a transmittance of 70% or more and 100% or less at a wavelength having the strongest intensity of light emitted from the light source.
(2) The wavelength having the strongest intensity of the light beam emitted from the light source is A (nm), and the in-plane phase difference of the wavelength 587.8 nm at an incident angle of 0 ° measured by the parallel Nicol rotation method of the film is Re. When (nm) is set, the following equation (I') is satisfied.
(I') A × n-150 ≦ Re <A × n + 150
However, n is an integer.

More specifically, the authentication device of the present invention is an authentication device having a light source, a polarizer, a film, and a photosensitivity sensor, wherein the film is arranged between the polarizer and the object to be authenticated, and the following ( It is an authentication device characterized by satisfying 1) and (2).
(1) The transmittance of the light beam emitted from the light source is 70% or more and 100% or less at the wavelength of the strongest intensity of the light ray.
(2) There is an integer n that satisfies the following equation (I).
(I) A × n-150 ≦ Re ≦ A × n + 150
Here, A is the wavelength (nm) showing the strongest intensity in the light beam emitted from the light source, and Re is the wavelength when the film is measured at a wavelength of 587.8 nm at an incident angle of 0 ° using the parallel Nicol rotation method. In-plane phase difference (nm).

The authentication device of the present invention includes a light source (1), a polarizer (2), a film (3), and a light sensitivity sensor (4) as shown in FIG. It is preferable that the light source, the polarizer, and the film are arranged in this order. Hereinafter, these configurations will be described.

<light source>
The type of light source constituting the authentication device of the present invention can be any light source as long as it emits light in a wavelength region that can be detected by the light sensitivity sensor. For example, any light source such as a hot cathode tube, a cold cathode tube, a fluorescent light source such as an inorganic EL, an organic electroluminescence element light source (organic EL), a light emitting diode (LED), or an incandescent light source can be used. In particular, organic EL or LED is a suitable light source. As will be described later, the in-plane phase difference of the film is an approximately integer of the wavelength having the strongest intensity of the light emitted from the light source (the wavelength having the strongest intensity of the light emitted from the light source may be referred to as the light source wavelength). It is important to double the adjustment to improve the authenticity. It is preferable to use a light source having a narrow emission wavelength band and an adjustable emission wavelength, because the more light having a wavelength far from the in-plane phase difference of the film is, the lower the authenticity is. The half width of the peak having the strongest intensity of the light beam emitted from the light source is preferably 5 nm or more and 150 nm or less. It is more preferably 5 nm or more and 70 nm or less. It is particularly preferably 5 nm or more and 50 nm or less. The narrower the wavelength band and the closer to an integral multiple of the in-plane phase difference of the film, the more the dependence on the orientation angle of the film, which affects the authenticity, can be suppressed. The orientation angle referred to here refers to the angle formed by the transmission axis of the polarizer and the main alignment axis of the film. In the present invention, the main orientation axis of the film represents the direction of the slow axis determined by the measurement method described later. Further, when the authentication device is installed on the surface of a curved display or the like, a flexible organic EL can be preferably used.

When an organic EL is used as a light source, it is particularly preferable to have a configuration that shields ultraviolet rays, which will be described later. By blocking ultraviolet rays, it is possible to compensate for the drawback of organic EL, which is easily deteriorated by ultraviolet rays, while incorporating the advantages of organic EL such as flexibility.

The light source may have one type of emission peak or may have two or more types of emission peaks, but one having one type of emission peak is preferable in order to increase the color purity. It is also preferable to use a plurality of light sources having different types of emission peaks in any combination from the viewpoint of improving security. When a plurality of light sources are used, it is preferable to use a film suitable for each light source (the in-plane phase difference is approximately an integral multiple of the light source wavelength).

<Light sensitivity sensor>
The authentication device of the present invention needs to include a light sensitivity sensor in order to recognize the light reflected from the object. Examples of the photosensitivity sensor include a Charge-Coupled Device (CCD) and a Complementary metal-xide-semiconductor (CMOS). Among them, it is preferable to use CMOS (including Live MOS, back-illuminated CMOS, laminated CMOS, curved CMOS, organic thin film CMOS, Foveon, etc.) from the viewpoint of manufacturing cost and readout speed. In particular, by combining the organic thin film CMOS and the ultraviolet shielding shield described later, it is possible to compensate for the difficulty of the organic thin film CMOS that the ultraviolet rays are easily deteriorated while obtaining the organic thin film CMOS such as a thin film.

<Polarizer>
The authentication device of the present invention needs to include a polarizer in order to prevent erroneous authentication due to the incident of external light. The external light referred to here refers to light that is incident on the light sensitivity sensor side of the film other than the light emitted from the light source. The material of the polarizer can be arbitrarily selected, and can be formed by, for example, dyeing a polyvinyl alcohol (PVA) film with a dichroic material such as an iodine compound and performing a stretching treatment. As an example of the PVA film, VF-PS # 7500 manufactured by Kuraray or the like can be applied.

<the film>
The authentication device of the present invention needs to have a configuration including a film. The film needs to have a transmittance (light source light transmittance) of 70% or more and 100% or less at a wavelength having the strongest intensity of light rays emitted from a light source. If the transmittance is less than 70%, the light may not sufficiently reach the light sensitivity sensor and the authenticity may be deteriorated. More preferably, it is 80% or more and 100% or less.

Further, in the authentication device of the present invention, the wavelength (light source wavelength) showing the strongest intensity in the light beam emitted from the light source is A (nm), and the wavelength 587 at an incident angle of 0 ° measured by the parallel Nicol rotation method of the film. When the in-plane phase difference of .8 nm is Re (nm), it is necessary to satisfy the equation (I').
(I') A × n-150 ≦ Re <A × n + 150
However, n is an integer.

Equation (I) indicates that the in-plane phase difference of the film is approximately an integral multiple of the light source wavelength (range from an integral multiple to ± 150 nm). The in-plane phase difference of the film is preferably in the range of ± 120 nm from an integral multiple of the light source wavelength, and more preferably in the range of ± 100 nm. When the in-plane phase difference of the film is not within the above range, the light emitted from the light source is polarized when it passes through the film, so that the influence of light absorption by the polarizer becomes large, and the deterioration of the authenticity becomes a problem. The degree of polarization depends on the orientation angle. Further, from the viewpoint of widening the process window, the in-plane phase difference is preferably 400 nm or more, more preferably 600 nm or more, and further preferably 800 nm or more. Further, as described later, one of the means for adjusting the in-plane retardation is to adjust the stretch ratio, but from the viewpoint of improving the film strength, it is not preferable to strongly stretch in only one direction, so that the in-plane position is set. The phase difference is preferably less than 3000 nm. Since the in-plane retardation is greatly affected by the film thickness, it is difficult to produce a film with an in-plane retardation of less than 3000 nm if the film thickness is too thick. Similarly, if the film thickness is too thin, the in-plane retardation It is difficult to make a film of 400 nm or more. In order to keep the in-plane phase difference within the above preferable range, it is preferable that the thickness is 10 μm or more and less than 100 μm from the viewpoint of ease of in-plane phase difference adjustment. It is more preferably 15 μm or more and less than 50 μm.

It is also possible to improve the authenticity by making the in-plane phase difference close to 0 by lowering the draw ratio, but it is not preferable from the viewpoint of impact resistance because the film becomes brittle.

The in-plane phase difference is most preferably measured at the wavelength of the light source, but the measurement is performed at 587.8 nm due to the stability of the light intensity of the measuring device. The difference between the in-plane phase difference at the wavelength of the light source and the in-plane phase difference at the wavelength that can be measured by the measuring device is preferably 40 nm or less.

The mechanism by which the light absorption by the polarizer increases when the in-plane phase difference is not within the above range will be described. When the authentication object is authenticated by the authentication device of the present invention, the light emitted from the light source passes through the polarizer and the film in this order, then reaches the authentication object, and the light reflected by the authentication object is emitted. It passes through the film and the polarizer in that order, and is detected by the light sensitivity sensor. The path of light is shown by an arrow as shown in FIG.

The polarizer absorbs light in a specific polarized state and transmits only light in other polarized states. Therefore, when the light emitted from the light source passes through the polarizer, it becomes linearly polarized light or circularly polarized light. When the film is non-polarizing (optically isotropic), the light emitted from the light source, passing through the polarizer and incident on the film, and reflected by the object to be certified and incident on the film. The polarized light does not change its polarization state before and after passing through the film. Therefore, if the film is non-polarizing (optically isotropic), the film is emitted from the light source, passes through the polarizer, passes through the film, and is reflected by the object to be certified. Since the polarization state does not change until it passes through and is incident on the polarizer, it passes through without being absorbed by the polarizer and is recognized by the optical sensitivity sensor.

However, if the film is polarized, the light emitted from the light source and passing through the polarizer changes its polarization state when it passes through the film and when it passes through the film after being reflected by the object to be certified. .. Therefore, some light is absorbed by the polarizer and cannot pass through. Therefore, the intensity of the light reaching the optical sensitivity sensor is reduced, which leads to a decrease in authenticity. The polarization property of the film is generated by the optical path length difference between the main orientation axis direction and the direction perpendicular to the main orientation axis, that is, the in-plane phase difference. Light that oscillates in the main orientation axis is faster or slower than light that oscillates in the vertical direction, so that the two lights are out of phase and polarized.

On the other hand, in the authentication device of the present invention, the in-plane phase difference is set to be approximately an integral multiple of the light source wavelength, so that the phase shift is approximately an integral multiple of 2π, and the phase shift is substantially close to zero. If the phase shift is small, the decrease in light intensity after transmission through the polarizer can be suppressed even if the orientation angle is shifted. Therefore, if the in-plane phase difference of the film is within the range of the above formula (I), the deterioration of the authenticity can be suppressed.

For example, it was found that when the light source wavelength is 525 nm and the in-plane phase difference is an integral multiple of 525 nm, the transmittance is high regardless of the orientation angle. The authentication performance is also confirmed by the method described later, and if the authentication performance becomes A or B by adjusting the in-plane phase difference, it is confirmed that the screen protection application of the in-screen fingerprint authentication smartphone shows good authentication performance. did. Examples of smartphone models include Vivo's X20Plus UD, X21, and NEX.

In addition, if there are multiple colors of light sources and you want the light sensitivity sensor to receive any of these colors, the surface will be an integral multiple of the wavelength with the second strongest intensity of the light rays emitted from the light source. It is preferable to use a film having an internal phase difference.

That is, the wavelength showing the second strongest intensity in the light beam emitted from the light source is B (nm), and the in-plane position when the film is measured at a wavelength of 587.8 nm at an incident angle of 0 ° using the parallel Nicol rotation method. When the phase difference is Re (nm), it is preferable that an integer m satisfying the following equation (II) exists.
(II) B × m-150 ≦ Re ≦ B × m + 150.

The “wavelength showing the second strongest intensity” here is selected from the wavelengths that peak when the wavelength dependence of the intensity of the light rays of each light source is plotted. The "peak" here refers to the wavelength that becomes the maximum value when plotting the wavelength dependence of the emission intensity of light rays. The "maximum value" here refers to a wavelength at which the sign changes from positive to negative when the intensity of light rays is differentiated by wavelength. When there is only one light source, among the peak wavelengths, the wavelength that has the second strongest intensity after the "wavelength showing the strongest intensity (A)" and does not correspond to the following two points is the "second strongest intensity". The indicated wavelength (B) ”. However, the strength of A is P (A), and the strength of B is P (B).
1. 1. A-20 <B <A + 20
2. 2. P (B) x 100 <P (A)
The first point above excludes that when the tip of the peak of A is cracked or the peak of A has a shoulder, it is regarded as the peak of B. Therefore, depending on the peak shape, it may be necessary to extend the exclusion range beyond the range of ± 20 nm of A.

The second point above excludes that noise is regarded as the peak of B. Therefore, depending on the noise level when measuring the wavelength dependence of the intensity of the light rays of each light source, even an intensity of 1/100 or more of A may be regarded as noise.

When there are two light sources, of the "wavelengths with the strongest intensity" for each light source, the one with the strongest intensity is the "wavelength showing the strongest intensity (A)" and the one with the weakest intensity is the "second strongest intensity". The wavelength (B) indicating the above.

Similarly, even when there are three or more light sources, it is preferable that the in-plane phase difference of the film is a common multiple of the "wavelength having the strongest intensity" of each light source.

Also, even if it is not the "wavelength with the strongest intensity" for each light source, it is possible to use a film with an in-plane phase difference that is an integral multiple of the wavelength that plays an important role in the structure of the authentication device. preferable. The important role here is not limited to imaging for authentication, but also includes a role of influencing an object to cause a change and eliminating an influence other than the object.

The method for keeping the in-plane phase difference of the film within the above range is not limited, but it is achieved by adjusting the refractive index of the resin and the stretching ratio and stretching temperature.

Examples of the resin constituting the film of the present invention include polyesters such as polyethylene terephthalate (abbreviation: PET) and polyethylene naphthalate (abbreviation: PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, and cellulose triacetate (abbreviation: TAC). , Cellulose acetate butyrate, Cellulose acetate propionate (abbreviation: CAP), Cellulose acetate phthalate, Cellulose acetate and other cellulose esters and their derivatives, Polyvinylidene chloride, Polyvinyl alcohol, Polyethylene vinyl alcohol, Syndiotactic polystyrene, Polycarbonate (abbreviation: PC), norbornene resin, polymethylpentene, polyether ketone, polyimide, polyether sulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon , Polymethylmethacrylate, acrylic and polyarylates, cycloolefin resins such as Arton (registered trademark) (trade name, manufactured by JSR) and Apel (registered trademark) (trade name, manufactured by Mitsui Chemicals). it can.

Of these resins, at least a film made of polyester is preferably used in terms of physical properties such as cost, availability, width of the process window during film formation, strength and elongation at break.

The polyester described in the present invention is a condensed polymer obtained by polymerization of an aromatic dicarboxylic acid or a monomer containing an aliphatic dicarboxylic acid and a diol as main constituents. As a known method for producing polyester, a transesterification reaction (transesterification method) or a direct esterification reaction (direct polymerization method) is used. Here, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-. Examples thereof include diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, and 4,4'-diphenylsulfone dicarboxylic acid. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecandioic acid, 1,4-cyclohexanedicarboxylic acid and ester derivatives thereof. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid, which exhibit a high refractive index, are preferably used. One of these dicarboxylic acid components may be used, or two or more of them may be used in combination.

Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. , 1,6-Hexanediol, 1,2-Cyclohexanedimethanol, 1,3-Cyclohexanedimethanol, 1,4-Cyclohexanedimethanol, Diethylene glycol, Triethylene glycol, Polyalkylene glycol, 2,2-Bis (4--) Hydroxyethoxyphenyl) propane, isosorbate, spiroglycol and the like can be mentioned. Of these, ethylene glycol is preferably used. Only one type of these diol components may be used, or two or more types may be used in combination.

From the viewpoint of improving the film strength and the stretchability, it is preferable to use a laminated film in which five or more layers made of resin A and layers made of resin C different from resin A are alternately laminated. Further, when the resin A contains a crystalline resin A as a main component and the resin C contains an amorphous resin C as a main component, it is preferable from the viewpoint that the in-plane phase difference can be easily adjusted. As the resin having a low refractive index, an amorphous resin or the like whose refractive index does not easily increase during stretching can be used.

Examples of the crystalline resin include polyethylene terephthalate and its copolymer, polyethylene naphthalate and its copolymer, polybutylene terephthalate and its copolymer, polybutylene naphthalate and its copolymer, and polyhexamethylene terephthalate. And its copolymer, polyhexamethylenenaphthalate and its copolymer, and the like can also be used. At this time, as the copolymerization component, it is preferable that one or more of the above-mentioned dicarboxylic acid component and diol component are copolymerized.

The resin having a low refractive index is not particularly limited, and is not particularly limited. Chain polyolefins such as polyethylene, polypropylene, poly (4-methylpentene-1), and polyacetal, ring-open metathesis polymerization of norbornenes, addition polymerization, and others. Alicyclic polyolefins, which are addition copolymers with olefins, biodegradable polymers such as polylactic acid and polybutylsuccinate, polyamides such as nylon 6, nylon 11, nylon 12, and nylon 66, aramid, and polymethylmethacrylate. Polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglucolic acid, polystyrene, styrene copolymer polymethylmethacrylate, polycarbonate, polypropylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2 , 6-Polypropylene such as naphthalate, polyether sulfone, polyether ether ketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polyarylate, tetrafluoride ethylene resin, trifluoroethylene resin, trifluoride chloride An ethylene resin, an ethylene tetrafluoride-6 propylene fluoride copolymer, a polyvinylidene fluoride, or the like can be used. Among these, it is most preferable that the resin C contains polyester as a constituent component from the viewpoints of strength, heat resistance, transparency and versatility, particularly from the viewpoint of adhesion to the crystalline resin and stackability. Here, the resin having a low refractive index may be a copolymer or a mixture.

For example, polyester containing isophthalic acid can reduce crystallinity, so that in-plane phase difference can be easily suppressed, and even if biaxially stretched, the refractive index in the thickness direction is unlikely to decrease. Therefore, even if the incident angle of the light from the light source changes, the occurrence of rainbow unevenness can be suppressed. Further, as another preferable amorphous polyester, a polyester containing spiroglycol as a copolymerization component is preferable. Polyester containing spiroglycol is less likely to be oriented in film deformation due to biaxial stretching or Boeing, so in-plane retardation fluctuation in the width direction is less likely to occur. Moreover, since the glass transition point has the effect of increasing, the increase in the heat shrinkage rate due to the use of the amorphous resin can be suppressed. Other preferable copolymer amorphous components include cyclohexanedimethanol, neopentyl glycol, cyclohexanedicarboxylic acid, isosorbide and the like.

The above film may be an unstretched film or a stretched film, but a film stretched in at least one direction is preferable from the viewpoint of strength, in-plane retardation adjustment, and productivity. In particular, when the film of the authentication device is supported by a material that may break such as glass, it is preferable that the elongation at the breaking point can be improved by stretching the film appropriately and the scattering of debris due to the surface breakage can be prevented. .. By increasing the draw ratio in either the longitudinal direction or the width direction, the molecules in the film are oriented and the in-plane phase difference can be improved. By increasing the stretching ratio in the width direction, the in-plane retardation and the main orientation axis become uniform in the width direction, and the usable product width can be increased, which is preferable. When heat treatment is performed after stretching in order to reduce the heat shrinkage rate, methods such as further stretching in the width direction during heat treatment, cooling once before heat treatment, and reducing the temperature difference between the stretching temperature and the heat treatment are used. It is also preferable to use the product because the in-plane phase difference and the main orientation axis become uniform in the width direction and the usable product width can be increased. Further, when the stretching temperature is lowered, orientation during stretching is likely to occur, which also makes it possible to improve the in-plane phase difference. On the contrary, when the temperature at the time of stretching is increased, the molecules are stretched without being oriented, so that the in-plane phase difference is unlikely to increase. In the present invention, it is necessary to adjust the stretching ratio and the stretching temperature in order to make the in-plane phase difference a substantially integer multiple of the light source wavelength. However, since the stretching ratio and stretching temperature have a great influence on the physical properties important for using the film, such as the strength of the film and the elongation at the breaking point, the strength of the film, the elongation at the breaking point and the target in-plane phase difference are compatible. It's difficult to do. Therefore, as a method for adjusting the in-plane phase difference, it is preferable to use a film in which five or more layers of two or more kinds of resins are alternately laminated. This is because by adjusting the refractive index of the resin used in addition to the stretching ratio and the stretching temperature, it becomes easy to achieve both the strength and elongation at the breaking point and the design of the in-plane phase difference.

Further, in the authentication device of the present invention, it is preferable that PT (0) and PT (45)) measured by the following methods satisfy the following formulas (III) and (IV).
(III) PT (45) ≧ 0.65
(IV) 1 ≧ PT (45) / PT (0) ≧ 0.6
[Measuring method of PT (0) and PT (45)]
(1) Measurement is performed using a spectrophotometer using a 50 W tungsten lamp as a light source.
(2) Cut the polarizer into two pieces and arrange them so that the surfaces of the two polarizers are perpendicular to the optical axis of the spectrophotometer and the transmission axes of the two polarizers are parallel to each other. To do.
(3) With respect to the two polarizing elements, the amount of transmitted light at the wavelength having the strongest intensity of the light beam emitted from the light source is measured (background measurement). The amount of transmitted light obtained by background measurement when the light source was turned off was defined as PT (D), and the amount of transmitted light when the light source was turned on was defined as PT (L).
(4) The film is placed between two polarizers so that the surface of the film is perpendicular to the optical axis of the spectrophotometer.
(5) While rotating only the film in a plane perpendicular to the optical axis of the spectrophotometer, the amount of transmitted light at the wavelength having the strongest intensity of the light rays emitted from the light source is measured. Let PT'(0) be the amount of transmitted light when the angle formed by the transmission axes of the two polarizing elements and the main orientation axis of the film is 0 °, and PT'(45) be the amount of transmitted light when the angle is 45 °.
(6) PT (0) and PT (45) are obtained from the following formulas.
PT (0) = (PT'(0) -PT (D)) / (PT (L) -PT (D))
PT (45) = (PT'(45) -PT (D)) / (PT (L) -PT (D))
The PT (45) obtained above is understood to be the transmittance when pasted at an angle at which the transmittance is considered to be the lowest. Formula (III) shows that it is preferable that the transmittance is 0.65 or more even in the state where the transmittance is the lowest. If the transmittance is 0.65 or less, it may lead to a decrease in authenticity.

The PT (0) obtained above represents the transparency when the film is attached at an orientation angle of 0 °, that is, an ideal angle from the viewpoint of improving the transmittance. The ratio of PT (45) to (PT (45) / PT (0)) indicates the degree to which the transmittance decreases when the film is attached at an angle deviating from the ideal angle. If the ratio of PT (0) and PT (45) is not within the above range, that is, PT (45) is larger than PT (0) or PT (45) is too small compared to PT (0). In other words, when PT (45) / PT (0) is smaller than 0.6, the transmission axis of the polarizer and the main orientation axis of the film are parallel in order to improve the authenticity of the authentication device. It is necessary to install it so that it becomes, and productivity may decrease. More preferably, it is 0.75 or more and less than 1.0.

The film applicable to the present invention can be produced under specific film-forming conditions, although it is a conventionally known general film-forming method as long as the refractive index, stretching ratio, and stretching temperature of the resin can be adjusted. For example, a resin as a material is melted by an extruder, extruded by an annular die or a T-die, and rapidly cooled to produce an unstretched film that is substantially amorphous and not oriented. As described above, in order to both adjust the in-plane phase difference and improve the film strength, it is also preferable to laminate two or more kinds of resins. From the same viewpoint, it is particularly preferable to include a structure in which five or more layers of two types of resins are alternately laminated. Furthermore, the unstretched film is stretched uniaxially, tenter-type sequentially biaxially stretched, tenter-type simultaneous biaxially stretched, tubular-type simultaneous biaxially stretched, or the like, by a known method such as a longitudinal direction (conveyance direction, vertical axis) of the film. A biaxially stretched film can be produced by stretching in a direction (direction, MD direction) or a direction perpendicular to the longitudinal direction of the film (width direction, horizontal axis direction, TD direction). The draw ratio in this case can be appropriately selected according to the resin used as the raw material of the film, but is preferably in the range of 2 to 10 times in the vertical axis direction and the horizontal axis direction, respectively. It is also preferable to perform heat treatment after stretching in order to suppress shrinkage during processing as an authentication device.

By forming the film within the above conditions, the elongation at the breaking point at 25 ° C. in both the main orientation axis direction and the direction orthogonal to the main orientation axis is 30% or more and 300% or less at the time of processing. It is preferable from the viewpoint of improving the handleability and the strength of the film. It is more preferably 50% or more and 200% or less. If the elongation at the breaking point is 30% or less, the possibility of breaking during processing or damage to the surface of the authentication device increases, which is not preferable. On the other hand, if it exceeds 300%, the slack during processing and the strength as a film are lowered, which may lead to a decrease in authenticity due to scratches and dents.

Further, as will be described later, when it is installed in the authentication device, it is preferable that the transmission axis of the polarizer and the main orientation axis of the film are parallel from the viewpoint of transmittance and thus authentication. Therefore, it is preferable that the direction of the main orientation axis of the film is constant in the MD direction and the TD direction of the film. The method for making the orientation angle constant is not particularly limited, but for example, by increasing the draw ratio in the MD direction or the TD direction with respect to the other draw ratio, 100 ° C. in the main orientation axis direction and the direction orthogonal to the main orientation axis. The ratio (maximum value / minimum value) of the maximum value and the minimum value of the heat shrinkage rate after the treatment for 30 minutes can be set to a certain value or more. The ratio of the maximum value to the minimum value is preferably 1.7 or more, more preferably 2.0 or more, still more preferably 3.0 or more.

The thickness of the film is preferably in the range of 3 to 200 μm, more preferably in the range of 10 to 150 μm, and particularly preferably in the range of 20 to 120 μm. Within the above range, the thickness of the entire authentication device can be reduced while ensuring the strength required for processing.

Further, it is preferable that the angle formed by the main orientation axis of the film and the transmission axis of the polarizer is less than 10 ° from the viewpoint of suppressing deterioration of authenticity. If it exceeds 10 °, the range of the in-plane phase difference with good authenticity becomes narrow, and the variation in the in-plane phase difference in the film surface may lead to a decrease in the authenticity. However, at the time of film forming, a phenomenon called Boeing described in JP-A-2010-240977 occurs, so that the range in which the orientation angles are aligned to the extent that they do not affect the authenticity is limited, and the orientation angles are aligned. The range that is not included is the production loss. Under the film-forming conditions of the present invention, the direction of the main orientation axis is constant over a wide width of the film by setting the longitudinal stretching ratio to 3.5 times or less and / and the transverse stretching ratio to 3.5 times or more. It is preferable from the viewpoint of productivity because it is close to. It is more preferable that the longitudinal stretching ratio is 3.2 times or less and / and the transverse stretching ratio is 4 times or more, the longitudinal stretching ratio is 2.9 times or less and / and the transverse stretching ratio is 4.5 times. The above is particularly preferable. In addition, a multi-layered film is preferable because it makes it easier to suppress changes in the orientation angle in the width direction.

The above-mentioned film used in the authentication device of the present invention preferably has small in-plane phase difference unevenness in the film surface from the viewpoint of reducing unevenness in authentication. As a method for evaluating unevenness, for example, both ends (A, B) indicating the maximum length in the film surface, both ends of a straight film that is orthogonal to the straight line AB connecting the points A and B, and passes through the midpoint of the straight line AB ( A method of measuring the in-plane phase difference of a total of 4 points of C and D) can be mentioned. It is preferable that the difference between the maximum value and the minimum value of the in-plane phase difference of the obtained four points is 200 nm or less. The difference in in-plane phase difference is more preferably 150 nm or less, and particularly preferably 100 nm or less. In order to keep the in-plane phase difference within the above range, the method is not particularly limited, but it is preferable to stabilize the stress applied to the film as a whole by stretching 2.7 times or more at a time when the film is stretched.

Further, in order to prevent deterioration of the internal polarizer and the light source, it is preferable that the film shields ultraviolet rays (here, light having a wavelength of 410 nm or less). When the light source is made of an organic material such as OLED, an ultraviolet shielding effect is particularly desired. It is most preferable to completely block light of 410 nm or less, but for example, by setting the light transmittance at a wavelength of 380 nm to 5% or less, it is possible to prevent deterioration of the internal polarizer and the light source. The method of shielding ultraviolet rays is not particularly limited, but it is preferable to reflect ultraviolet light by a multilayer structure. The setting of the reflection wavelength can be determined by the layer thickness of each layer of the multilayer laminated film as described in Japanese Patent Application Laid-Open No. 2016-215643. In addition to reflection, UV absorbers may be used or used in combination with a reflective design.

As the ultraviolet absorber that can be used in the present invention, it is preferable to use a benzotriazole-based, benzophenone-based, benzoate-based, or triazine-based agent having a molecular weight of 300 g / mol or more. As the ultraviolet absorber, one of these may be selected, or two or more of them may be used in combination. There is a relationship between the molecular weight and the sublimation property of additives such as ultraviolet absorbers, and sublimation is unlikely to occur when an additive having a large molecular weight is used. The molecular weight is more preferably 400 g / mol or more, and further preferably 500 g / mol or more. Many UV absorbers with high molecular weight have long-chain alkyl chains attached to the basic aromatic ring skeleton, which inhibit stacking between UV absorbers and crystallize in the resin to increase haze. It is desirable because it does not cause problems such as inviting.

The ultraviolet absorber that can be added is not particularly limited as the benzotriazole-based ultraviolet absorber, and is, for example, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy). -3', 5'-ditertiary butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-third butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-Hydroxy-5'-third octylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-dicumylphenyl) benzotriazole, 2- (2'-hydroxy-3'-th Examples include 2- (2'-hydroxyphenyl) benzotriazoles such as tributyl-5'-carboxyphenyl) benzotriazoles and 2,2'-methylenebis (4-terioctyl-6-benzotriazolyl) phenols. Be done.
The benzophenone-based ultraviolet absorber is not particularly limited, and for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 5,5'-methylenebis (2-). 2-Hydroxybenzophenones such as hydroxy-4-methoxybenzophenone) can be mentioned.

The benzoate-based ultraviolet absorber is not particularly limited, and is, for example, phenylsalicylate, resorcinol monobenzoate, 2,4-ditertiary butylphenyl-3,5-ditertiary butyl-4-hydroxybenzoate, 2,4-. Examples thereof include di-tertiary amylphenyl-3-3,5-di-tertiary butyl-4-hydroxybenzoate and hexadecyl-3,5-di-tertiary butyl-4-hydroxybenzoate.

The triazine-based ultraviolet absorber is not particularly limited, but is 2- (2-hydroxy-4-octoxyphenyl) -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- (2- (2-). Hydroxy-4-hexyloxyphenyl) -4,6-diphenyl-s-triazine, 2- (2-hydroxy-4-propoxy-5-methylphenyl) -4,6-bis (2,4-dimethylphenyl)- s-Triazine, 2- (2-Hydroxy-4-hexyloxyphenyl) -4,6-dibiphenyl-s-Triazine, 2,4-bis (2-hydroxy-4-octoxyphenyl) -6- (2) , 4-Dimethylphenyl) -s-Triazine, 2,4,6-Tris (2-hydroxy-4-octoxyphenyl) -s-Triazine, 2- (4-isooctyloxycarbonylethoxyphenyl) -4,6 Examples thereof include triaryltriazines such as -diphenyl-s-triazine.

Other UV absorbers include, for example, phenylsalicylate, t-butylphenylsalicylate, p-octylphenylsalicylate, etc. for salicylic acid, and other natural products (eg, oryzanol, shea butter, bicarine) Etc.), biological systems (eg, keratinocytes, melanin, urocanin, etc.) and the like can also be used. A hindered amine compound can also be used in combination with these ultraviolet absorbers as a stabilizer. Inorganic UV absorbers are not preferable because they are incompatible with the base resin and lead to an increase in haze, which deteriorates visibility when an image is displayed on an authentication device.

When an ultraviolet absorber is used, it may be added to the A layer including the outermost layer of the laminated biaxially oriented film, which is a preferred embodiment of the present invention, the B layer which is the inner layer, or both. Above all, it is most preferable that the ultraviolet absorber is contained only in the B layer. When an ultraviolet absorber is added to the outermost layer, a phenomenon in which the added ultraviolet absorber is deposited on the film surface and a phenomenon in which the added ultraviolet absorber is volatilized are likely to occur, which contaminates the film forming machine and processes the precipitate. It is not preferable because it has an adverse effect on the above. By adding it only to the inner layer, the outermost layer acts as a lid to prevent the UV absorber from volatilizing, so that the precipitation phenomenon is less likely to occur, which is preferable.

The film surface may be coated with a coating that imparts functionality such as scratch resistance. As a coating method, a method can be used in which a curable resin is used as a main component, a cross-linking agent such as melamine or oxazoline is added, and the resin is cured by ultraviolet light.

The curable resin is preferably highly transparent and durable, and for example, acrylic resin, urethane resin, fluorine resin, silicon resin, polycarbonate resin, and vinyl chloride resin can be used alone or in combination. In particular, in terms of curability, flexibility, and productivity, the curable resin is preferably made of an active energy ray-curable resin such as an acrylic resin typified by a polyacrylate resin. Further, when adding scratch resistance at the time of bending, which is required for a film applied to a portion where curved surface followability is required, the curable resin is preferably made of a thermosetting urethane resin.

When the authentication device, for example, recognizes the distribution pattern of the melanin pigment existing in the epidermis, the melanin pigment strongly absorbs blue light from ultraviolet rays, so that the light source wavelength is blue light (the maximum peak wavelength is 415 nm or more and 495 nm). The point that a clear pattern can be obtained is that the in-plane phase difference of the film is in the range of ± 120 nm from an integral multiple of the light source wavelength, that is, the existence of an integer n satisfying the following equation (V). Is preferable. If the wavelength of the light source is shorter than 415 nm, there may be a problem of erroneous authentication due to deterioration of the light source due to ultraviolet rays and increased absorption by other than the melanin pigment.
(V) A × n-120 ≦ Re ≦ A × n + 120, and 415 ≦ A ≦ 495.

Further, when the distribution pattern of hemoglobin is to be recognized as in vein recognition, for example, the light source wavelength is in the infrared region (maximum peak wavelength is 800 nm or more and 1200 nm or less) because hemoglobin has a strong absorption peak in the infrared region. It is preferable that the in-plane phase difference of the film is in the range of an integral multiple of the light source wavelength to ± 150 nm, that is, the existence of an integer n satisfying the following equation (VIII) is obtained from the viewpoint of obtaining a clear pattern. .. Further, in the case of retina, iris, face recognition, etc., since the authentication target person directly sees the light, it may be preferable to use infrared rays from the viewpoint of alleviating the discomfort of the authentication target person.
(VIII) A × n-150 ≦ Re ≦ A × n + 150, and 800 ≦ A ≦ 1200.

Similarly, depending on the color and design of the subject to be certified, it may be preferable that the light source wavelength is green (the wavelength of the maximum peak is 495 nm or more and 570 nm or less), that is, an integer n satisfying the following equation (VI) exists. Further, it may be preferable that yellow to red (maximum peak wavelength is 570 nm or more and 800 nm or less), that is, an integer n satisfying the following equation (VII) exists.
(VI) A × n-100 ≦ Re ≦ A × n + 100 and 495 ≦ A ≦ 570.
(VII) A × n-120 ≦ Re ≦ A × n + 120 and 570 ≦ A ≦ 800.

It is also effective to combine a plurality of the above wavelengths for improving the authentication accuracy, but in order to obtain the effect of the present invention, the in-plane phase difference of the film is set to be a substantially common multiple of each light source wavelength using the film. It is preferable to use films having different in-plane retardation for each light source.

The area of the area that can be authenticated in the authentication device of the present invention is not particularly limited, and is appropriately adjusted depending on the object to be authenticated and the application. Since the authentication device of the present invention uses a film having a uniform in-plane retardation and a main orientation axis, a large area of an authenticable region can be taken. In other words, the authentication device of the present invention, the area of authentication available space is 100 cm ² or more, further 225 cm ² or more, further can be suitably used for 400 cm ² or more devices.

As described above, the authentication device of the present invention can accurately recognize various authentication objects, and is therefore suitably used for an authentication device that targets at least one of fingerprint, iris, face, handprint, body shape, and vein. be able to. Further, the authentication device of the present invention can improve the authentication accuracy even if the angle formed by the transmission axis of the polarizer and the main orientation axis of the film is large, so that the yield can be reduced.

[Characteristic evaluation method]
Film evaluation A. In-plane phase difference (Re) and in-plane phase difference difference (Δ phase difference)
Using "KOBRA-21ADH" manufactured by Oji Measuring Instruments Co., Ltd., the in-plane phase difference and the slow axis at a wavelength of 587.8 nm at an incident angle of 0 ° were measured. The direction of the slow axis was taken as the main orientation axis. The sample was cut out from the film at 5 locations × 4 cm × 4 cm at different locations, and the average value measured for each was used.

The unevenness of the in-plane phase difference is orthogonal to both ends (A, B) showing the maximum length in the film plane and the straight line AB connecting the points A and B, and both ends (C) of the straight line passing through the midpoint of the straight line AB. , D), the in-plane phase difference at 4 points was measured, and the difference between the maximum value and the minimum value was used.

B. PT (45) and PT (0)
(1) Cut the polarizing element used in the authentication device or the polarizing element having the same degree of polarization as the polarizing element used (TS wire grid polarizing film (manufactured by Edmond Optics Japan Co., Ltd.)) into two sheets. The surfaces of the two polarizers are arranged so as to be perpendicular to the optical axis of the spectrophotometer using a 50 W tungsten lamp as the light source, and the transmission axes of the two polarizers are arranged to be parallel to each other. Perform background measurement with the light off and the light source on. Let PT (D) be the amount of transmitted light measured when the light source is off, and let PT (L) be the amount of transmitted light measured when the light source is on.
(2) The film is placed between two polarizers so that the surface of the film is perpendicular to the optical axis of the spectrophotometer.
(3) While rotating only the film in a plane perpendicular to the optical axis of the spectrophotometer, the amount of transmitted light at the wavelength having the strongest intensity of the light rays emitted from the light source is measured. Let PT'(0) be the amount of transmitted light when the angle formed by the transmission axes of the two polarizing elements and the main orientation axis of the film is 0 °, and PT'(45) be the amount of transmitted light when the angle is 45 °.
(4) PT (0) and PT (45) are obtained from the following formulas.
PT (0) = (PT'(0) -PT (D)) / (PT (L) -PT (D))
PT (45) = (PT'(45) -PT (D)) / (PT (L) -PT (D))
C. Light Source Transmittance and 380 nm Transmittance The transmittance at an incident angle of 0 ° was measured using a spectrophotometer manufactured by Hitachi High-Technologies Corporation (U-4100 Spectrophotometer).
Measurement conditions: The slit was set to 2 nm, the gain was set to 2, and the scanning speed was set to 600 nm / min. The sample was cut out from the film at 5 locations × 4 cm × 4 cm at different locations, and the average value measured for each was used.

Aluminum oxide was used for the reflector of the integrating sphere, the double beam direct ratio metering method was used for the metering method, and the prism and grating / grating type double monochrome were used for the spectroscope.

The light source light transmittance indicates the transmittance at the wavelength having the strongest intensity of the light beam emitted from the light source of the authentication device.

D. Break point elongation The film is cut out from the center of the sample width in a width of 10 mm x 150 mm. Measurement was performed according to JIS-C-2151 and ASTM-D-882 using a digital micrometer (HKT-1208 manufactured by Matsuo Sangyo) and a tensile tester (RTG1210). The sample was gripped in the main orientation axis direction with a chuck, pulled at a speed of 200 mm / min, and the strength when the sample was cut (broken) (the value obtained by dividing the tensile load value by the cross-sectional area of the test piece) and the elongation were determined. The tensile elongation was calculated by the following formula.
Tensile elongation (%) = 100 × (L-Lo) / Lo
Lo: Sample length before test L: Sample length at break The measurement was performed 5 times, and the average value was used. Similarly, the elongation at the breaking point in the direction orthogonal to the main orientation axis was also measured. The measurement was performed in a room kept at 25 ° C.

E. Light source wavelength and half width of light source A optical fiber of NA0.22 was attached to a mini spectrophotometer (C10083MD, C9914GB) manufactured by Hamamatsu Photonics, and the light of the light source was measured. The wavelength having the highest intensity in the range of 320 nm or more and 1500 nm or less is defined as the light source wavelength, and the peak width at half the intensity of the peak intensity of the light source wavelength is defined as the half width.

F. The central portion of the film was measured according to JIS-C-2151 using a thickness digital micrometer (HKT-1208 manufactured by Matsuo Sangyo Co., Ltd.). The measurement was performed three times, and the average value was used.

Evaluation of authentication device G. Certibility Register the certification target α in an environment of 23 ° C. and 65RH%. In the case of Example 10, the iris is used as the authentication target, and in other cases, the fingerprint is used as the authentication target. After that, the authentication object α and the unregistered authentication object β are alternately recognized by the authentication device 200 times each. The recognition time is 2 seconds each. The probability of rejecting α (false rejection rate: FRR) and the probability of accepting β (false acceptance rate: FAR) are evaluated as follows. A was good, B was acceptable, and C and D were unsuitable.
A: FRR ≤ 1.0%, FAR ≤ 0.5%
B: 1.0% <FRR ≤ 3.0%, FAR ≤ 0.5%
C: 3.0% <FRR ≤ 5.0% or / and 0.5% <FAR ≤ 1.0%
D: 5.0% <FRR or 1.0% <FAR.

H. The light source durability authentication device was maintained in a light source lighting state for 1000 hours under an atmosphere of 23 ° C. and 65 RH%, and changes in authentication performance before and after the test were evaluated. The judgment criteria are as follows. However, ΔFRR and ΔFAR indicate the values obtained by subtracting the FRR and FAR before the test from the FRR and FAR after the test, respectively.
A: ΔFRR = 0 and ΔFAR = 0.
B: "0 <ΔFRR≤1.0 and 0 <ΔFAR≤0.5"
C: "1.0 <ΔFRR ≤ 2.0 and 0 <ΔFAR ≤ 0.5", "0 <ΔFRR ≤ 1.0 and 0.5 <ΔFAR ≤ 1.5" or "1.0 <ΔFRR" ≤2.0 and 0.5 <ΔFAR≤1.5"
D: Not applicable to any of A, B, and C.

I. Impact Durability The impact value was measured by a film impact tester (manufactured by Toyo Seiki Seisakusho) using a hemispherical impact head with a diameter of 1/2 inch in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH. The measurement was performed 5 times per sample. Further, the impact value for each measurement was divided by the film thickness attached to the measurement sample to obtain the impact value per unit thickness, which was obtained from the average value of the five measurements. The measured values were evaluated as follows.
A: 1.0 N ・ m / mm or more
B: 0.5 N ・ m / mm or more and less than 1.0 N ・ m / mm
C: Less than 0.5 N ・ m / mm.

J: Heat shrinkage rate Five samples with a width of 10 mm and a length of 200 mm (measurement direction) are cut out in each of the MD direction and TD direction of the film, and marked as marked lines at positions 25 mm from both ends for universal projection. Measure the distance between the marked lines with a machine and use it as the test length (10). Next, the test piece was sandwiched between papers and placed in an oven kept at 100 ° C. with no load, heated for 30 minutes, taken out, cooled at room temperature, and then the dimension (11) was measured with a universal projector and the following formula was used. The average value of 5 pieces was taken as the heat shrinkage rate.
Heat shrinkage = {(10-11) / 10} x 100 (%)

Hereinafter, the present invention will be described with reference to examples, but the present invention is not necessarily limited thereto.

(Example 1)
As the light source and the light sensitivity sensor, a ClearID FS9500 manufactured by Synaptics (light source wavelength 525 nm, light source half width 30 nm) was used.
As the polarizer, VF-PS # 7500 manufactured by Kuraray was used as a general polarizing film having a degree of polarization of 80% or more. The film was prepared by the following method.

(Resin used for film making)
Resin A: Polyethylene terephthalate (PET) (intrinsic viscosity: 0.65)
Resin B: Polyethylene terephthalate (PET / SPG / CHDC) in which 25 mol% of spiroglycol is copolymerized with respect to the entire diol component and 30 mol% of cyclohexanedicarboxylic acid is copolymerized with respect to the entire dicarboxylic acid component (intrinsic viscosity: 0.72).
Resin C: Resin B (90% by weight) and UV absorber 2,2'-methylenebis [6- (2H-benzotriazole-2-yl) -4- (1,1,3,3-tetramethyl) Butyl) phenol] (10% by weight) was mixed using an extruder and pelletized.
Resin D: Resin A (90% by weight) and 2,2'-methylenebis [6- (2H-benzotriazole-2-yl) -4- (1,1,3,3-tetramethyl), which is an ultraviolet absorber. Butyl) phenol] (10% by weight) was mixed using an extruder and pelletized.
Resin E: Polyethylene terephthalate (PET) containing 0.8% by weight of divinylbenzene / styrene copolymer particles having an average particle size of 0.70 μm and 1.5% by weight of aggregated alumina particles having an average secondary particle size of 0.08 μm. ) (Intrinsic viscosity: 0.65).

(Creation of film)
Resin A was used as the resin constituting the A layer, and resin C was used as the resin constituting the B layer. The intrinsic viscosity of this resin C was 0.72, and the in-plane average refractive index after film formation was 1.55. The thermoplastic resin A and the thermoplastic resin C are each melted at 280 ° C. by an extruder, passed through five FSS type leaf disc filters, and then the discharge ratio (lamination ratio) is resin A / resin by a gear pump. While measuring so that C = 1.5 / 1 and the film thickness after biaxial stretching is 35 μm, they are alternately merged by a 201-layer feed block (101 layers for A layer and 100 layers for B layer). It was. Next, it was supplied to a T-die, molded into a sheet, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatically applied voltage of 8 kV with a wire to obtain an unstretched multilayer laminated film. It was. This unstretched film was sequentially biaxially stretched. First, the film was conveyed by a Teflon (registered trademark) roll at 105 ° C., and then stretched 2.8 times at 95 ° C. while heating with an infrared heater having an output of 500 W in the longitudinal direction to obtain a uniaxially stretched film. This uniaxially stretched film was stretched 4.5 times in the width direction at 100 ° C. and then heat-fixed at 220 ° C., at which time it was relaxed by 1.7% in the width direction and cooled in a transporting step. After cutting the edges, they were wound up to obtain a film. The physical properties of the obtained film are shown in Tables 1 and 3.

(Creating an authentication device)
A clear ID (light source, light sensitivity sensor), a polarizer, and a film were adhered in this order using an optically clear adhesive (OCA) to obtain an authentication device. At that time, the main orientation axis of the film was arranged so as to be parallel to the transmission axis of the polarizer. The area that can be authenticated by the authentication device is 1 cm ² . The characteristics of the obtained authentication device are shown in Tables 2 and 4. An authentication device with excellent authentication and durability was obtained.

(Example 2)
An authentication device was obtained in the same manner as in Example 1 except that the main orientation axis of the film attached to the device was 45 ° with respect to the transmission axis of the polarizer. As shown in Table 2, an authentication device having excellent authenticity and durability was obtained.

(Example 3)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the width direction was 5.5 times. An authentication device with excellent authentication and durability was obtained.

(Example 4)
A film and an authentication device were obtained in the same manner as in Example 1 except that the stretching ratio in the longitudinal direction was 3.0 times. An authentication device with excellent authentication and durability was obtained.

(Example 5)
An authentication device was obtained in the same manner as in Example 4 except that the main orientation axis of the film was set to 10 ° with respect to the transmission axis of the polarizer. An authentication device with good authenticity and excellent durability was obtained.

(Example 6)
An authentication device was obtained in the same manner as in Example 4 except that the main orientation axis of the film was 45 ° with respect to the transmission axis of the polarizer. An authentication device with good authenticity and excellent durability was obtained.

(Example 7)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction was set to 2.6 times. An authentication device with good authenticity and excellent durability was obtained.

(Example 8)
A film and an authentication device were obtained in the same manner as in Example 2 except that the resin D was used as the resin constituting the B layer. An authentication device with good authenticity and durability was obtained.

(Example 9)
A film and an authentication device were obtained in the same manner as in Example 2 except that the temperature for stretching in the longitudinal direction was 90 ° C. and the temperature for stretching in the width direction was 120 ° C. An authentication device with good authenticity and excellent durability was obtained.

(Example 10)
A film and an authentication device were obtained in the same manner as in Example 2 except that the Panasonic BM ET-200 was used as a light source and a light sensitivity sensor instead of ClearID to set the elongation ratio in the longitudinal direction to 3.2 times. An authentication device with excellent authentication and durability was obtained.

(Example 11)
A film and an authentication device were obtained in the same manner as in Example 2 except that a 3-layer feed block (A layer is 2 outer layers and B layer is 1 inner layer) is used. It has become an authentication device with excellent authenticity.

(Example 12)
A film and an authentication device were obtained in the same manner as in Example 2 except that resin B was used as the resin constituting the B layer. It has become an authentication device with excellent authenticity.

(Example 13)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction was 1.05 times and the stretching ratio in the width direction was 1.05 times and no heat treatment was performed. It has become an authentication device with excellent authenticity.

(Example 14)
A film and an authentication device were obtained in the same manner as in Example 2 except that a polycarbonate film (Teijin Panlite PC-7129) was used as the film. It has become an authentication device with excellent authenticity.

(Example 15)
An authentication device was obtained in the same manner as in Example 1 except that the certifiable area was 50 cm ² . It has become an authentication device with excellent authenticity.

(Example 16)
A film and an authentication device were obtained in the same manner as in Example 15 except that the stretching ratio in the longitudinal direction was 4.2 times and the stretching ratio in the width direction was 2.3 times. It became an authentication device with good authentication performance.

(Example 17)
A film and an authentication device were obtained in the same manner as in Example 1 except that the stretching ratio in the width direction was 4.4 times. In this film, when measuring the in-plane phase difference, the measurement was performed with the light source wavelength set to 587.8 nm and the light source wavelength set to 525 nm with a color filter. The results measured at 525 nm are shown in parentheses in the Re (nm) column in Table 3. As shown in Table 4, in the authentication test, it became an authentication device having a particularly excellent authentication property with FRR = 0%.

(Example 18)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the width direction was 4.4 times. In this film, when measuring the in-plane phase difference, the measurement was performed with the light source wavelength set to 587.8 nm and the light source wavelength set to 525 nm with a color filter. The results measured at 525 nm are shown in parentheses in the Re (nm) column in Table 3. As shown in Table 4, in the authentication test, it became an authentication device having a particularly excellent authentication property with FRR = 0%.

(Example 19)
An authentication device was obtained in the same manner as in Example 2 except that the light source and light sensitivity sensor of ClearID and the light source and light sensitivity sensor of BM ET-200 were used at the same time. In ClearID and BM ET-200, the intensity of the light beam of the light source was higher in ClearID. Only the data from the ClearID optical sensitivity sensor has become an authentication device with excellent authenticity. Among the measurement items in Tables 3 and 4, for the items in which the light source wavelength is required for measurement, the measurement results at 525 nm are shown outside the parentheses, and the results at 850 nm are shown inside the parentheses.

(Example 20)
A film and an authentication device were obtained in the same manner as in Example 19 except that the stretching ratio in the width direction was set to 5.7 times. In ClearID and BM ET-200, the intensity of the light beam of the light source was higher in ClearID. Data from both the ClearID optical sensitivity sensor and the BM ET-200 optical sensitivity sensor have become authentication devices with excellent authenticity. Among the measurement items in Tables 3 and 4, for the items in which the light source wavelength is required for measurement, the measurement results at 525 nm are shown outside the parentheses, and the results at 850 nm are shown inside the parentheses.

(Example 21)
A film and an authentication device were obtained in the same manner as in Example 5 except that the heat treatment temperature was set to 240 ° C. As shown in Table 4, the authentication device has good authenticity.

(Example 22)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction was 2.6 times and the stretching ratio in the width direction was 4.0 times. As shown in Table 4, although the in-plane phase difference varies slightly, the authentication device has good authentication performance as a whole.

(Example 23)
A film and an authentication device were obtained in the same manner as in Example 5 except that the resin E was used instead of the resin A. As shown in Table 4, the authentication device has good authenticity.

(Example 24)
A film and an authentication device were obtained in the same manner as in Example 2 except that a 9-layer feed block (A layer is the outer 5 layers and B layer is the inner 4 layers) is used. As shown in Table 4, the authentication device has excellent authentication properties.

(Example 25)
A 101-layer feed block (51 layers on the outside for the A layer and 50 layers on the inside for the B layer) was used, and the film and certification were performed in the same manner as in Example 2 except that the discharge amount was adjusted to make the thickness after stretching 18 μm. Got the device. Although the impact resistance is slightly reduced due to the thinning, the film can be applied to applications that require a thin film. As shown in Table 4, the authentication device has excellent authentication properties.

(Comparative Example 1)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction was 3.2 times and the main orientation axis of the film was 10 ° with respect to the transmission axis of the polarizer. It became an authentication device with slightly inferior authentication performance.

(Comparative Example 2)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction was 3.2 times. It became an authentication device with poor authentication performance.

(Comparative Example 3)
A film and an authentication device were obtained in the same manner as in Example 2 except that the stretching ratio in the width direction was 4.9 times. It became an authentication device with poor authentication performance.

(Comparative Example 4)
A film and an authentication device were obtained in the same manner as in Comparative Example 2 except that the stretching ratio in the longitudinal direction was 3.2 times and the stretching ratio in the width direction was 4.4 times. It became an authentication device with poor authentication performance.

In the authentication device of the present invention, the authentication performance does not depend on the orientation angle of the film, and the film absorbs and reflects ultraviolet rays to improve the durability of the light source and the polarizer. In addition, inexpensive polyester is used as the raw material of the film. Can be. Therefore, it has good certification performance and durability, is inexpensive, and is excellent in productivity.

1: Light source 2: Polarizer 3: Film 4: Light sensitivity sensor 5: Light emitted from the light source reflected by the object to be authenticated 6: Light emitted from the light source

Claims

An authentication device having a light source, a polarizer, a film, and a photosensitivity sensor, wherein the film is arranged between the polarizer and an object to be authenticated and satisfies the following (1) and (2). Authentication device.
(1) The transmittance of the light beam emitted from the light source is 70% or more and 100% or less at the wavelength of the strongest intensity of the light ray.
(2) There is an integer n that satisfies the following equation (I).
(I) A × n-150 ≦ Re ≦ A × n + 150
Here, A is a wavelength (nm) showing the strongest intensity in the light beam emitted from the light source.
Re is the in-plane phase difference (nm) when the film is measured at a wavelength of 587.8 nm at an incident angle of 0 ° using a parallel Nicol rotation method.
The authentication device according to claim 1, wherein an integer m satisfying the above equation (I) and satisfying the following equation (II) exists.
(II) B × m-150 ≦ Re ≦ B × m + 150
Here, B is a wavelength (nm) that exhibits the second strongest intensity in the light beam emitted from the light source.
Re is the in-plane phase difference (nm) when the film is measured at a wavelength of 587.8 nm at an incident angle of 0 ° using a parallel Nicol rotation method.
The authentication device according to claim 1 or 2, wherein the film satisfies the following formulas (III) and (IV).
(III) PT (45) ≧ 0.65
(IV) 1 ≧ PT (45) / PT (0) ≧ 0.6
Here, PT (45) and PT (0) are obtained as follows.
(1) The polarizer is cut into two pieces so that the surfaces of the two polarizers are perpendicular to the optical axis of the spectrophotometer using a 50 W tungsten lamp as a light source, and the transmission axes of the two polarizers are connected to each other. Are arranged so that they are parallel to each other, and background measurement is performed in the light source off state and the light source on state. Let PT (D) be the amount of transmitted light measured when the light source is off, and let PT (L) be the amount of transmitted light measured when the light source is on.
(2) The film is placed between two polarizers so that the surface of the film is perpendicular to the optical axis of the spectrophotometer.
(3) While rotating only the film in a plane perpendicular to the optical axis of the spectrophotometer, the amount of transmitted light at the wavelength having the strongest intensity of the light rays emitted from the light source is measured. Let PT'(0) be the amount of transmitted light when the angle formed by the transmission axes of the two polarizing elements and the main orientation axis of the film is 0 °, and PT'(45) be the amount of transmitted light when the angle is 45 °.
(4) PT (0) and PT (45) are obtained from the following equations.
PT (0) = (PT'(0) -PT (D)) / (PT (L) -PT (D))
PT (45) = (PT'(45) -PT (D)) / (PT (L) -PT (D)).
The authentication device according to any one of claims 1 to 3, wherein the half width of the peak showing the strongest intensity in the light beam emitted from the light source is 5 nm or more and 70 nm or less.
The authentication device according to any one of claims 1 to 4, wherein an integer n satisfying the following equation (V) exists.
(V) A × n-120 ≦ Re ≦ A × n + 120, and 415 ≦ A ≦ 495.
The authentication device according to any one of claims 1 to 4, wherein an integer n satisfying the following equation (VI) exists.
(VI) A × n-100 ≦ Re ≦ A × n + 100 and 495 ≦ A ≦ 570.
The authentication device according to any one of claims 1 to 4, wherein an integer n satisfying the following equation (VII) exists.
(VII) A × n-120 ≦ Re ≦ A × n + 120 and 570 ≦ A ≦ 800.
The authentication device according to any one of claims 1 to 4, wherein an integer n satisfying the following equation (VIII) exists.
(VIII) A × n-150 ≦ Re ≦ A × n + 150 and 800 ≦ A ≦ 1600.
The authentication device according to any one of claims 1 to 8, wherein the in-plane phase difference of the film is 400 nm or more and 3000 nm or less.
The authentication device according to any one of claims 1 to 9, wherein the film is a laminated film in which five or more layers of a layer made of resin A and a layer made of resin B different from resin A are alternately laminated.
The resin B constituting the film contains at least one of cyclohexanedimethanol, spiroglycol, neopentyl glycol, isophthalic acid, cyclohexanedicarboxylic acid, and isosorbide, and is characterized by containing polyester as a main component. Item 10. The authentication device according to item 10.
The authentication device according to any one of claims 1 to 11, wherein the elongation at the breaking point at 25 ° C. in both the main orientation axis direction and the direction orthogonal to the main orientation axis of the film is 30% or more and 300% or less.
The ratio (maximum value / minimum value) of the maximum value and the minimum value of the heat shrinkage rate when the film is treated at 100 ° C. for 30 minutes in the main orientation axis direction and the direction orthogonal to the main orientation axis is 1.7 or more. The authentication device according to any one of claims 1 to 12.
The authentication device according to any one of claims 1 to 13, wherein the angle formed by the main orientation axis of the film and the transmission axis of the polarizer is less than 10 °.
Both ends (C, D) of a straight line in which the film is orthogonal to both ends (A, B) showing the maximum length in the film plane and a straight line AB connecting points A and B, and passes through the midpoint of the straight line AB. The authentication device according to any one of claims 1 to 14, wherein the difference between the maximum value and the minimum value is 200 nm or less in the in-plane phase difference of a total of four points.
The authentication device according to any one of claims 1 to 15, wherein the area of the area that can be authenticated is 10 cm 2 or more.
The method according to any one of claims 1 to 16, wherein the light source includes either an organic EL (organic electroluminescent element) or a light emitting diode (LED), and the light transmittance of the film at a wavelength of 380 nm is 5% or less. Authentication device.
The authentication device according to any one of claims 1 to 17, wherein the optical sensitivity sensor is a CMOS (Complementary metal-axis-simiconductor) sensor.
A film used for an authentication device having a light source, a polarizer, a film, and a light sensitivity sensor, which satisfies the following (1) and (2).
(1) The transmittance of light rays emitted from the light source of the film is 70% or more and 100% or less at the wavelength of the strongest intensity of the light rays.
(2) There is an integer n that satisfies the following equation (I).
(I) A × n-150 ≦ Re ≦ A × n + 150
Here, A is a wavelength (nm) showing the strongest intensity in the light beam emitted from the light source.
Re is the in-plane phase difference (nm) when the film is measured at a wavelength of 587.8 nm at an incident angle of 0 ° using a parallel Nicol rotation method.
The film according to claim 19, wherein the film satisfies the following formulas (III) and (IV).
(III) PT (45) ≧ 0.65
(IV) 1 ≧ PT (45) / PT (0) ≧ 0.6
Here, PT (45) and PT (0) are obtained as follows.
(1) The polarizer is cut into two pieces so that the surfaces of the two polarizers are perpendicular to the optical axis of the spectrophotometer using a 50 W tungsten lamp as a light source, and the transmission axes of the two polarizers are connected to each other. Are arranged so that they are parallel to each other, and background measurement is performed. Let PT (D) be the amount of transmitted light measured when the light source is off, and let PT (L) be the amount of transmitted light measured when the light source is on.
(2) The film is placed between two polarizers so that the surface of the film is perpendicular to the optical axis of the spectrophotometer.
(3) While rotating only the film in a plane perpendicular to the optical axis of the spectrophotometer, the amount of transmitted light at a wavelength showing the strongest intensity in the light rays emitted from the light source is measured. Let PT'(0) be the amount of transmitted light when the angle formed by the transmission axes of the two polarizing elements and the main orientation axis of the film is 0 °, and PT'(45) be the amount of transmitted light when the angle is 45 °.
(4) PT (0) and PT (45) are obtained from the following equations.
PT (0) = (PT'(0) -PT (D)) / (PT (L) -PT (D))
PT (45) = (PT'(45) -PT (D)) / (PT (L) -PT (D)).