TWI838492B - Certification devices and membranes - Google Patents

Abstract

[Abstract] The subject is to provide an authentication device whose authentication does not depend on the orientation angle of the film, and the purpose is to provide an authentication device having a light source, a polarizer, a film and a photosensitivity sensor, and a film with specific characteristics arranged between the polarizer and the authentication object.

Description

Certification devices and membranes

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 are being put into practical use. In particular, biometric authentication devices such as fingerprint authentication, iris authentication, vein authentication, and face authentication are being improved in accuracy and reduced in cost, and are beginning to be used in various electronic products such as mobile phones and vehicles. It is predicted that they will be further used in vehicles, electronic payments, etc. in the future, so authentication devices with higher accuracy, low cost, and durability during long-term use are required.

As shown in Patent Document 1, in general, an optical authentication device irradiates the light emitted from a light source to the authentication object, receives the reflected light with a light sensitivity sensor, and photographs it, and performs authentication by matching it with a pattern of a pre-registered patterned image. In such an authentication device, once light other than the light emitted by the light source enters, it will cause authentication errors, so polarizers are often used to suppress the reflection of external light. In addition, by using a film of thermoplastic resin such as polyester or polycarbonate on the outermost layer, the authentication function is prevented from being reduced due to damage or scratches. [Prior Technical Document] [Patent Document]

[Patent Document 1] International Publication No. 2017/126153

However, if the aforementioned film has polarization or optical rotation, the light from the light source will be polarized/optically rotated. As a result, the polarized/optically rotated light will be blocked by the polarizer before reaching the photosensor, thereby causing a problem of reduced authentication.

There are two possible solutions to this problem. The first method is to use an unstretched or slightly stretched film of optically roughly isotropic polycarbonate or the like as a protective film. However, films with low stretch ratios are sometimes prone to cracking and lack impact resistance. In addition, polycarbonate films with high impact resistance are expensive.

The second method is to use an oriented polyester film as a protective film, so that the main alignment axis of the oriented polyester film is parallel to the transmission axis of the polarizer, thereby substantially eliminating the polarization on the protective film. However, in this method, when the direction of the main alignment axis and the transmission axis of the polarizer are slightly offset several times, the polarization becomes obvious and the authentication is reduced.

Furthermore, in authentication devices using OLED (Organic Light Emitting Diode) as a light source, degradation of OLED due to ultraviolet rays and the like becomes a key issue in long-term use, making improvement of OLED's durability a topic directly related to increasing the service life of authentication devices.

The present invention is dedicated to solving the above-mentioned problem, and is aimed at providing an authentication device whose authentication does not depend on the orientation angle of the film.

The present invention is made to solve the above-mentioned problem. That is, an authentication device has a light source, a polarizer, a film, and a light sensitivity sensor, and its characteristics are: the aforementioned film is arranged between the polarizer and the authentication object, and satisfies the following (1) and (2).

(1) The transmittance of the light emitted from the aforementioned light source is 70% or more and 100% or less at the wavelength of the strongest intensity of the light, (2) There exists an integer n that satisfies the following formula (I), (I) A×n-150≦Re≦A×n+150

Here, A is the wavelength (nm) at which the light emitted from the aforementioned light source exhibits the strongest intensity, and Re is the in-plane phase difference (nm) when the aforementioned film is measured at a wavelength of 587.8nm at an incident angle of 0° using the parallel Nicol rotation method.

According to the present invention, an authentication device can be provided whose authentication does not depend on the orientation angle of the film. In addition, a cheap film can be used, which can improve the durability of the light source and the impact resistance of the screen.

[Form used to implement the invention]

The following is a detailed description of the implementation forms of the present invention, but the present invention is not limited to the implementation forms including the following embodiments. Various changes can be made within the scope of achieving the purpose of the invention and not departing from the gist of the invention.

The authentication device of the present invention is an authentication device having a light source, a polarizer, a film, and a photosensitivity sensor. A film satisfying the following (1) and (2) is arranged between the polarizer and the authentication object.

(1) The transmittance of the aforementioned film at the wavelength with the strongest intensity of the light emitted from the aforementioned light source is 70% or more and 100% or less.

(2) When the wavelength with the strongest intensity of the light emitted from the aforementioned light source is set to A (nm), and the in-plane phase difference of the wavelength of 587.8nm at an incident angle of 0° measured by the parallel Nicol rotation method of the aforementioned film is set to Re (nm), the following formula (I ' ) is satisfied.

(I ' )A×n-150≦Re<A×n+150

Where n is an integer.

In more detail, 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 is characterized in that the aforementioned film is arranged between the polarizer and the authentication object, and satisfies the following (1) and (2).

(1) The transmittance of the light emitted from the aforementioned light source is not less than 70% and not more than 100% at the wavelength of the strongest intensity of the light.

(2) There exists an integer n that satisfies the following formula (I).

(I)A×n-150≦Re≦A×n+150

Here, A is the wavelength (nm) at which the light emitted from the aforementioned light source exhibits the strongest intensity, and Re is the in-plane phase difference (nm) when the aforementioned film is measured at a wavelength of 587.8nm at an incident angle of 0° using the parallel Nicol rotation method.

The authentication device of the present invention is shown in FIG1 and includes a light source (1), a polarizer (2), a film (3), and a light sensitivity sensor (4). Preferably, the light source, the polarizer, and the film are arranged in this order. The following describes the above configurations.

〈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 photosensitivity sensor. For example, any light source such as a hot cathode tube or a cold cathode tube, an inorganic EL or the like, an organic electroluminescent element light source (organic EL), a light emitting diode (LED), an incandescent light source, etc. can be used. In particular, an organic EL or LED is a suitable light source. As described later, it is important to adjust the in-plane phase difference of the film to an approximately integer multiple of the wavelength with the strongest intensity of the light emitted from the aforementioned light source (in some cases, the wavelength with the strongest intensity of the light emitted from the light source is referred to as the light source wavelength) in order to improve authentication. Because the more wavelength light deviates from the approximate factor of the in-plane phase difference of the film, the more the certification will be reduced, so it is better to use a light source with a narrow luminescent wavelength band and adjustable luminescent wavelength. The half-width of the peak with the strongest intensity of the light emitted from the light source is preferably greater than 5nm and less than 150nm. More preferably, it is greater than 5nm and less than 70nm. Particularly preferably, it is greater than 5nm and less than 50nm. The narrower the wavelength band, the closer it is to an integer multiple of the in-plane phase difference of the film, which can suppress the film's dependence on the orientation angle that affects the certification. Here, the so-called orientation angle refers to the angle formed by the transmission axis of the polarizer and the main orientation axis of the film. In addition, in the present invention, the main orientation axis of the film represents the direction of the slow axis obtained by the measurement method described later. Furthermore, when the authentication device is installed on the surface of a curved display, etc., a soft organic EL can be preferably used.

When an organic EL is used as a light source, it is particularly preferable to have a structure that shields ultraviolet light as described below. By shielding ultraviolet light, the advantages of organic EL such as flexibility can be obtained while compensating for the disadvantage of organic EL that is easily degraded by ultraviolet light.

The light source may have one luminous peak or two or more luminous peaks, but in order to improve color purity, it is preferred to have one luminous peak. In addition, from the perspective of improving safety, it is preferred to use a plurality of light sources with different luminous peaks in any combination. When using a plurality of light sources, it is preferred to use a film suitable for each light source (the in-plane phase difference is approximately an integer multiple of the wavelength of the light source).

<Photosensitivity sensor> The authentication device of the present invention must be constructed to include a photosensor in order to identify light reflected from an object. Examples of photosensitivity sensors include Charge-Coupled Device (CCD), Complementary metal-oxide-semiconductor (CMOS), etc. Among them, from the perspective of manufacturing cost and reading speed, it is better to use CMOS (including Live MOS, back-illuminated CMOS, multilayer CMOS, curved CMOS, organic thin film CMOS, Foveon, etc.). In particular, by combining organic thin film CMOS with the ultraviolet shielding described later, an organic thin film CMOS such as a thin film can be obtained, and at the same time, the disadvantage of organic thin film CMOS that is easily degraded by ultraviolet rays can be compensated.

<Polarizer> In order to prevent authentication errors caused by external light, the authentication device of the present invention must be constructed to include a polarizer. Here, the so-called external light refers to light that enters the photosensor side from the film other than the light emitted from the light source. The material of the polarizer can be selected arbitrarily, for example, it can be formed by dyeing a polyvinyl alcohol (PVA) film with a dichroic material such as an iodine compound and stretching it. For example, the PVA film can be applied to VF-PS#7500 manufactured by Kuraray.

<Film> The authentication device of the present invention must be constructed to include a film. The aforementioned film must have a transmittance of 70% to 100% at the wavelength of the strongest intensity of the light emitted from the light source (light source light transmittance). When the transmittance is less than 70%, light may not be able to fully reach the photosensor, resulting in reduced authentication. It is more preferably 80% to 100%.

Furthermore, in the authentication device of the present invention, when the wavelength exhibiting the strongest intensity among the light emitted from the light source (light source wavelength) is set to A (nm), and the in-plane phase difference of the wavelength of 587.8nm at an incident angle of 0° measured by the parallel Nicol rotation method of the aforementioned film is set to Re (nm), the formula (I ' ) must be satisfied.

(I ' )A×n-150≦Re<A×n+150

Where n is an integer.

In more detail, 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 is characterized in that the aforementioned film is arranged between the polarizer and the authentication object, and satisfies the following (1) and (2).

(1) The transmittance of the light emitted from the aforementioned light source is not less than 70% and not more than 100% at the wavelength of the strongest intensity of the light.

(2) There exists an integer n that satisfies the following formula (I).

(I)A×n-150≦Re≦A×n+150

Here, A is the wavelength (nm) at which the light emitted from the aforementioned light source exhibits the strongest intensity, and Re is the in-plane phase difference (nm) when the aforementioned film is measured at a wavelength of 587.8nm at an incident angle of 0° using the parallel Nicol rotation method.

(I) shows that the in-plane phase difference of the film is approximately an integer multiple of the wavelength of the light source (in the range of ±150nm from the integer multiple). The in-plane phase difference of the film is preferably in the range of ±120nm from the integer multiple of the wavelength of the light source, and more preferably in the range of ±100nm. When the in-plane phase difference of the film is not within the above range, the light emitted from the light source will be polarized when passing through the film, and the influence of light absorption caused by the polarizer will increase, which will cause the problem of reduced certification. In addition, the degree of polarization depends on the orientation angle. In addition, from the perspective of expanding the process window, the in-plane phase difference is preferably greater than 400nm, more preferably greater than 600nm, and more preferably greater than 800nm. Furthermore, as described later, as one of the means for adjusting the in-plane phase difference, the stretching ratio can be cited. However, from the perspective of improving the film strength, it is not ideal to stretch strongly in one direction, so the in-plane phase difference should be less than 3000nm. Since the in-plane phase difference is greatly affected by the film thickness, it is difficult to make a film with an in-plane phase difference of less than 3000nm when the film thickness is too thick. Similarly, if the film thickness is too thin, it is difficult to make a film with an in-plane phase difference of more than 400nm. In order to set the in-plane phase difference within the above-mentioned preferred range, a thickness of more than 10μm and less than 100μm is preferred from the perspective of the ease of adjusting the in-plane phase difference. More preferably, it is more than 15μm and less than 50μm.

Furthermore, although the certification can be improved by reducing the stretching ratio and bringing the in-plane phase difference close to 0, this is not favorable from the viewpoint of impact resistance because the film becomes fragile.

In addition, the in-plane phase difference is best measured at the wavelength of the light source, and in consideration of the light intensity stability of the measuring device, it is measured at 587.8nm. The difference between the in-plane phase difference at the wavelength of the light source and the in-plane phase difference at a wavelength that can be measured by the measuring device is preferably 40nm or less.

The mechanism by which the light absorption caused by the polarizer increases when the in-plane phase difference is not within the above range is explained. When the authentication object is authenticated in the authentication device of the present invention, the light emitted from the light source passes through the polarizer and the film in sequence and reaches the authentication object. The light reflected by the authentication object passes through the film and the polarizer in sequence and is detected by the photosensitivity sensor. When the light path is represented by an arrow, it becomes as shown in Figure 2.

Polarizers absorb light of a specific polarization state and only transmit light of other polarization states. Therefore, when light emitted from a light source passes through a polarizer, it becomes linearly polarized or circularly polarized. In the case where the film has no polarization (optical isotropy), the polarization state of light emitted from the light source and entering the film through the polarizer, and the light reflected by the object to be authenticated and entering the film, does not change before and after passing through the film. Therefore, in the case where the film has no polarization (optical isotropy), after being emitted from the light source and passing through the polarizer, the polarization state does not change when passing through the film, and until it is reflected by the object to be authenticated and enters the polarizer through the film, so it passes through without being absorbed by the polarizer and is identified by the photosensitivity sensor.

However, in the case of a film with polarization, the polarization state of light emitted from the light source and passing through the polarizer changes when passing through the film and when passing through the film after being reflected by the object to be authenticated. Therefore, a portion of the light is absorbed by the polarizer and cannot pass through. Therefore, the intensity of the light reaching the photosensor is reduced, resulting in a reduction in authentication. The polarization of the film is caused by the difference in optical path length between the main alignment axis direction and the direction perpendicular to the main alignment axis, that is, by the in-plane phase difference. Light vibrating in the main alignment axis direction is faster or slower than light vibrating in the perpendicular direction, causing the phase of the two lights to shift and polarize.

On the other hand, in the authentication device of the present invention, by setting the in-plane phase difference to an approximately integer multiple of the wavelength of the light source and setting the phase shift to an approximately integer multiple of 2π, the phase shift is substantially close to zero. If the phase shift becomes smaller, even if the orientation angle shifts, the decrease in light intensity after the polarizer is transmitted will be suppressed. Therefore, as long as the in-plane phase difference of the film is within the range of the above formula (I), the decrease in authentication can be suppressed.

For example, it was found that when the wavelength of the light source is 525nm, the transmittance is high without depending on the orientation angle when the in-plane phase difference is an integer multiple of 525nm. The authentication was confirmed by the method described below, and it was confirmed that by adjusting the in-plane phase difference, if the authentication is A or B, it exhibits good authentication performance for screen protection purposes of in-screen fingerprint authentication smartphones. In terms of smartphone models, for example, Vivo's X20 Plus UD, X21, and NEX can be cited.

Furthermore, when the light source has multiple colors and any color is received by the photosensitivity sensor, it is preferable to make a film with the following in-plane phase difference, that is, the in-plane phase difference becomes an integer multiple for the wavelength with the second strongest intensity of the light emitted from the light source.

That is, preferably, when the wavelength exhibiting the second strongest intensity among the light emitted from the light source is set as B (nm), and the in-plane phase difference when the above film is measured at a wavelength of 587.8nm with an incident angle of 0° using the parallel Nicol rotation method is set as Re (nm), there exists an integer m satisfying the following formula (II). (II) B×m-150≦Re≦B×m＋150.

In addition, the "wavelength that exhibits the second strongest intensity" is selected from the wavelength that becomes the peak when plotting the wavelength dependence of the intensity of light of each light source. The "peak" here refers to the wavelength that becomes the maximum value when plotting the wavelength dependence of the luminous intensity of light. The "maximum value" here refers to the wavelength whose sign changes from positive to negative when the intensity of light is differentiated by wavelength. When there is only one light source, among the wavelengths that become the peak, the wavelength that has the second strongest intensity after the "wavelength that exhibits the strongest intensity (A)" and does not meet the following two points is set as the "wavelength that exhibits the second strongest intensity (B)". Among them, the intensity of A is set to P(A) and the intensity of B is set to P(B). 1. A-20＜B＜A＋20 2. P(B)×100＜P(A) The above point 1 excludes the following situations: when the front end of the peak of A is split or the peak of A has a shoulder, it is regarded as the peak of B. Therefore, it is also considered that it is necessary to expand the exclusion range beyond the range of ±20nm of A according to the peak shape.

The second point above excludes the case where noise is considered as the peak of B. Therefore, depending on the noise level when measuring the wavelength dependence of the intensity of light from each light source, an intensity of more than 1/100 of A should be considered as noise.

When there are two light sources, among the "wavelengths with the strongest intensity" of each light source, the stronger one is set as the "wavelength presenting the strongest intensity (A)", and the weaker one is set as the "wavelength presenting the second strongest intensity (B)".

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

Furthermore, even if it is not the "wavelength with the strongest intensity" of each light source, it is still preferable to use a film having an in-plane phase difference that is an integer multiple of the wavelength that plays an important role in the structure of the authentication device. The so-called important role here is not limited to the photography used for authentication, but also includes roles that exclude changes that affect the object or influences other than the object.

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

Examples of the resin constituting the film of the present invention include polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate, cellulose nitrate, and their derivatives, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, and the like. alcohol), syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin, polymethylpentene, polyetherketone, polyimide, polyether sulphate (abbreviation: PES), polyphenylene sulfide, polysulphides, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic and polyaromatic esters, cycloolefin resins such as ARTON (registered trademark) (trade name, manufactured by JSR Corporation) and APEL (registered trademark) (trade name, manufactured by Mitsui Chemicals, Inc.), etc.

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

The polyester described in the present invention refers to a condensed copolymer obtained by polymerization of monomers having aromatic dicarboxylic acids or aliphatic dicarboxylic acids and diols as main components. As for the industrial production method of polyester, as is well known, transesterification reaction (transesterification method) and direct esterification reaction (direct polymerization method) can be used. Here, as for aromatic dicarboxylic acids, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4´-diphenyletherdicarboxylic acid, 4,4´-diphenylsulfonyl dicarboxylic acid, etc. are mentioned. As for aliphatic dicarboxylic acids, for example, adipic acid, suberic acid, sebacic acid, dicarboxylic acid, dodecanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and ester derivatives thereof can be mentioned. Among them, terephthalic acid and 2,6-naphthalene dicarboxylic acid, which have high refractive indexes, can be preferably used. The dicarboxylic acid component may be used alone or in combination of two or more.

In addition, as the diol component, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,3-butylene glycol, 1,4-butylene glycol, 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)propylene glycol, isosorbate, spiroglycerol, etc. can be cited. Among them, ethylene glycol can be preferably used. Such diol components can be used alone or in combination of two or more.

From the perspective of improving film strength and elongation, a laminated film in which 5 or more layers containing resin A and layers containing resin C different from resin A are alternately laminated is preferred. Furthermore, if the resin A contains crystalline resin A as the main component and the resin C contains amorphous resin C as the main component, it is preferred from the perspective of facilitating the adjustment of the in-plane phase difference. As a low refractive index resin, an amorphous resin whose refractive index is difficult to increase during stretching can be used.

As crystalline resins, for example, polyethylene terephthalate and its copolymers, polyethylene naphthalate and its copolymers, polybutylene terephthalate and its copolymers, polybutylene naphthalate and its copolymers, poly(hexamethylene terephthalate) and its copolymers, poly(hexamethylene terephthalate) and its copolymers, etc. can be used. At this time, as for the copolymerization components, it is preferred that the aforementioned dicarboxylic acid component and diol component are copolymerized with one or more species respectively.

As for the low refractive index resin, there is no particular limitation, and the following can be used: polyethylene, polypropylene, poly (4-methylpentene-1), chain polyolefins such as polyacetal, alicyclic polyolefins obtained by ring-opening metathesis polymerization, addition polymerization, and addition polymers of norbornenes with other olefins, biodegradable polymers such as polylactic acid and polybutyl succinate, polyamides such as nylon 6, nylon 11, nylon 12, nylon 66, polyarylamide, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral (polyvinyl butyral), ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymer polymethyl methacrylate, polycarbonate, polytrimethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate and other polyesters, polyether sulfones, polyether ether ketones, modified polyphenylene ether, polyphenylene sulfide, polyether imide, polyimide, polyarylate, tetrafluoroethylene resin, trifluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride and the like. Among them, from the viewpoint of strength or heat resistance, transparency and versatility, and especially from the viewpoint of adhesion and stacking properties with crystalline resins, it is best to contain polyester as a constituent as resin C. Here, the low refractive index resin may be a copolymer or a mixture.

For example, polyesters containing isophthalic acid can easily suppress in-plane phase difference because they can reduce crystallinity, and even if biaxially stretched, the refractive index in the thickness direction is difficult to reduce, so even if the incident angle of light from the light source changes, the occurrence of rainbow unevenness can be suppressed. In addition, as for other preferred amorphous polyesters, polyesters containing spiroglycerol are preferably used as copolymer components. Polyesters containing spiroglycerol are difficult to align in film deformation caused by biaxial stretching or bowing, so changes in in-plane phase difference in the width direction are not easy to occur. In addition, because there is an effect of raising the glass transition point, the increase in thermal shrinkage caused by the use of amorphous resins can be suppressed. Other preferred copolymer amorphous components include: cyclohexanedimethanol, neopentyl glycol, cyclohexanedicarboxylic acid, isosorbide, etc.

Furthermore, the above-mentioned film may be an unstretched film or a stretched film, but from the perspective of strength, in-plane phase difference adjustment, and productivity, it is preferably a film that is stretched in at least one direction. In particular, when the film of the authentication device is supported by a material that may break, such as glass, it is preferred to increase the elongation of the fracture point by stretching it appropriately, thereby preventing the scattering of fragments due to surface damage. By increasing the stretching ratio in either the long side direction or the width direction, the molecules in the film can be aligned, and the in-plane phase difference can be increased. By increasing the stretching ratio in the width direction, the in-plane phase difference and the main alignment axis become uniform in the width direction, and the width of the product that can be used can be increased, so it is better. In the case of heat treatment after stretching in order to reduce the thermal shrinkage rate, by using methods such as further stretching in the width direction while performing heat treatment, temporarily cooling before heat treatment, and reducing the temperature difference between the stretching temperature and the heat treatment temperature, the in-plane phase difference and the main orientation axis can be made uniform in the width direction, and the width of the product that can be used can be increased, which is preferred. In addition, when the stretching temperature is lowered, it is easier to orient during stretching, thereby improving the in-plane phase difference. On the contrary, once the temperature during stretching is increased, the molecules are stretched in a non-oriented state, so it is difficult to improve the in-plane phase difference. In the present invention, in order to set the in-plane phase difference to an approximately integer multiple of the wavelength of the light source, the stretching ratio and the stretching temperature must be adjusted. However, the stretching ratio and stretching temperature greatly affect important physical properties such as film strength or elongation at the fracture point, so it is difficult to achieve both the film strength or elongation at the fracture point and the target in-plane phase difference. Therefore, as a method for adjusting the in-plane phase difference, it is better to use a film made of 5 or more layers of two or more resins alternately stacked. The reason is that in addition to the stretching ratio and stretching temperature, by adjusting the refractive index of the resin used, it is easy to achieve both the film strength or elongation at the fracture point and the in-plane phase difference.

In the authentication device of the present invention, it is preferred that the PT(0) and PT(45) measured by the following method satisfy the following formula (III) and formula (IV). (III) PT(45) ≧ 0.65 (IV) 1 ≧ PT(45)/PT(0) ≧ 0.6 [Measurement method of PT(0) and PT(45)] (1) The measurement is performed using a spectrophotometer with a 50W tungsten lamp as a light source. (2) The polarizer is cut into two pieces and arranged 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. (3) The amount of transmitted light at the wavelength with the strongest intensity of the light emitted from the above-mentioned light source is measured for the two polarizers (background measurement). The amount of transmitted light obtained by background measurement in the light source off state is set as PT(D), and the amount of transmitted light in the light source on state is set as PT(L). (4) The aforementioned film is arranged between two polarizers so that the film surface is perpendicular to the optical axis of the spectrophotometer. (5) While rotating the aforementioned film only in a plane perpendicular to the optical axis of the spectrophotometer, the amount of transmitted light in the wavelength with the strongest intensity of the light emitted from the aforementioned light source is measured. The amount of transmitted light when the angle between the transmission axes of the two polarizers and the main orientation axis of the aforementioned film is 0° is set as PT'(0), and the amount of transmitted light when it is 45° is set as PT'(45). (6) PT(0) and PT(45) are obtained by the following formulas. PT(0)=(PT’(0)-PT(D))/(PT(L)-PT(D)) PT(45)=(PT’(45)-PT(D))/(PT(L)-PT(D)) PT(45) obtained above can be interpreted as the transmittance when attached at an angle considered to have the lowest transmittance. Formula (III) indicates that even at the lowest transmittance, the transmittance should be above 0.65. If the transmittance becomes below 0.65, the certification may be reduced.

From the perspective of an alignment angle of 0°, i.e., improved transmittance, the PT(0) obtained above indicates the transmittance when the film is attached at an ideal angle. The ratio to PT(45) (PT(45)/PT(0)) indicates the degree of transmittance reduction when the film is attached at a different angle from the ideal angle. When the ratio of PT(0) to PT(45) is not within the above range, i.e., when PT(45) is greater than PT(0), or when PT(45) is much smaller than PT(0), i.e., when PT(45)/PT(0) is less than 0.6, in order to improve the authentication of the authentication device, the transmission axis of the polarizer must be arranged parallel to the main alignment axis of the film, which results in reduced productivity. More preferably, it is greater than 0.75 and less than 1.0.

The film applicable to the present invention can be any film that can adjust the refractive index, stretching ratio, and stretching temperature of the resin. It can be a conventionally known general film-making method, and can be manufactured under specific film-making conditions. For example, a resin as a material is melted by an extruder, extruded by a ring die or a T-die, and rapidly cooled, so that an unstretched film with substantially no amorphous orientation can be manufactured. As mentioned above, in order to adjust the in-plane phase difference and improve the film strength, it is preferred to layer two or more resins. From the same point of view, a structure including two resins layered alternately is particularly preferred. Furthermore, the unstretched film can be stretched in the long side direction of the film (conveying direction, longitudinal direction, MD direction) or in the direction perpendicular to the long side direction of the film (width direction, transverse direction, TD direction) by known methods such as uniaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular type simultaneous biaxial stretching, etc., to produce a biaxially stretched film. The stretching ratio at this time can be appropriately selected in combination with the resin used as the raw material of the film, but it is preferably within the range of 2 to 10 times in the longitudinal and transverse directions. As a certification device, it is also preferred to perform heat treatment after stretching in order to suppress shrinkage during processing.

By forming the film within the above conditions, the elongation at the break point of the film in the main orientation axis direction and the direction perpendicular to the main orientation axis at 25°C is 30% to 300%, which is preferred from the perspective of improved handling during processing and improved strength as a film. More preferably, it is 50% to 200%. In the case where the elongation at the break point is less than 30%, the possibility of fracture during processing or surface damage to the certification device increases, so it is not ideal. In addition, if it exceeds 300%, there may be a decrease in certification due to scratches or pits caused by relaxation during processing or a decrease in strength as a film.

Furthermore, as described later, when placed in an authentication device, from the perspective of transmittance and thus authentication, it is preferred that the transmission axis of the polarizer is parallel to the main alignment axis of the film. Therefore, the direction of the main alignment axis of the film is preferably constant in the MD direction and the TD direction of the film. There is no particular limitation on the method of making the alignment angle constant, and for example, the stretching ratio in the MD direction or the TD direction is increased relative to the stretching ratio of the other, thereby setting the ratio of the maximum value to the minimum value of the thermal shrinkage rate in the direction of the main alignment axis and the direction orthogonal to the main alignment axis when treated at 100°C for 30 minutes (maximum value/minimum value) to a certain value or more. Preferably, the ratio of the maximum value to the minimum value is 1.7 or more, more preferably 2.0 or more, and even 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. By setting the thickness in the above range, the thickness of the entire authentication device can be reduced while ensuring the strength required for processing.

In addition, it is preferred that the angle between the main alignment axis of the film and the transmission axis of the polarizer is less than 10° from the perspective of suppressing the reduction of certification. When it exceeds 10°, the range of in-plane phase difference with good certification becomes narrower, and the variation of in-plane phase difference within the film surface causes the reduction of certification. However, when the film is made, the bending phenomenon described in Japanese Patent Gazette No. 2010-240976 occurs, so the range of alignment angle alignment to the extent that it does not affect certification is limited, and the range of misaligned alignment angles causes production losses. In the film forming conditions of the present invention, by setting the longitudinal stretch ratio to 3.5 times or less, or/and the transverse stretch ratio to 3.5 times or more, the wide width of the film can be covered and the direction of the main alignment axis can be close to a certain value, so it is better from the perspective of productivity. It is more preferable to set the longitudinal stretch ratio to 3.2 times or less, or/and the transverse stretch ratio to 4 times or more, and it is particularly preferable to set the longitudinal stretch ratio to 2.9 times or less, or/and the transverse stretch ratio to 4.5 times or more. In addition, by setting the film as a multi-layer structure, it is easy to suppress the change of the alignment angle in the width direction, so it is not good.

The above-mentioned film used in the certification device of the present invention is preferably one with a smaller unevenness in the in-plane phase difference within the film surface from the viewpoint of reducing the unevenness of the certification. As for the evaluation method of unevenness, for example, a method of measuring the in-plane phase difference of a total of four points, namely, two ends (A, B) and two ends (C, D), wherein the two ends (A, B) are the two ends showing the maximum length within the connecting film surface, and the two ends (C, D) are the two ends of the film that are orthogonal to the straight line AB connecting the points A and B and pass through the midpoint of the straight line AB. The difference between the maximum and minimum values of the in-plane phase difference of the four points obtained is preferably less than 200nm. The difference in the above-mentioned in-plane phase difference is more preferably less than 150nm, and particularly preferably less than 100nm. There is no particular method for setting the in-plane phase difference within the above range, but it is preferably to stabilize the stress applied to the film as a whole by stretching the film 2.7 times or more at a time when stretching the film.

Furthermore, in order to prevent the internal polarizer and light source from deteriorating, the film is preferably capable of shielding ultraviolet rays (here, light having a wavelength of 410 nm or less). In the case where the light source is composed of organic materials such as OLED, a UV shielding effect is particularly desired. It is best to completely block light below 410 nm, and for example, by setting the transmittance of light with a wavelength of 380 nm to less than 5%, the internal polarizer and light source can be prevented from deteriorating. The method of shielding ultraviolet rays is not particularly limited, and it is preferably to reflect ultraviolet light through a multi-layer structure. The setting of the reflection wavelength is as described in Japanese Patent Application No. 2016-215643, and can be determined by the thickness of each layer of the multi-layer laminate film. In addition to reflection, ultraviolet absorbers can also be used, or in combination with a reflection design.

As the ultraviolet absorber that can be used in the present invention, it is preferred to use benzotriazole, diphenyl ketone, benzoate, tris(III)-containing agents with a molecular weight of 300 g/mol or more. The UV absorber can be selected from one of these, or two or more can be used in combination. It is related to the sublimation of additives headed by the molecular weight and the UV absorber, and it is difficult to cause sublimation when using additives with a large molecular weight. The molecular weight is preferably 400g/mol or more, and more preferably 500g/mol or more. Most UV absorbers with high molecular weight have long alkyl chains attached to the basic aromatic ring skeleton, which will hinder the stacking of UV absorbers and will not cause problems such as crystallization in the resin and increase in haze, so they are preferred.

Regarding the external light absorber that can be added, there is no particular limitation on the benzotriazole-based ultraviolet light absorber, and examples thereof include: 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-diisopropylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'- 2-(2'-hydroxyphenyl)benzotriazoles such as 2,2'-methylenebis(4-tert-octyl-6-benzotriazolyl)phenol, etc. As the phenyl ketone-based ultraviolet absorber, there is no particular limitation, and examples thereof include 2,4-dihydroxyphenyl ketone, 2-hydroxy-4-methoxyphenyl ketone, 2-hydroxy-4-octyloxyphenyl ketone, 5,5'-methylenebis(2-hydroxy-4-methoxyphenyl ketone), and 2-hydroxyphenyl ketones such as 5,5'-methylenebis(2-hydroxy-4-methoxyphenyl ketone).

The benzoate-based ultraviolet absorber is not particularly limited, and examples thereof include phenyl salicylate, resorcinol monobenzoate, 2,4-dibutylphenyl-3,5-dibutyl-4-hydroxybenzoate, 2,4-dipentylphenyl-3,5-dibutyl-4-hydroxybenzoate, and hexadecyl-3,5-dibutyl-4-hydroxybenzoate.

As three The ultraviolet light absorber is not particularly limited, and examples thereof include 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-s-tri , 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl-s-triphenyl , 2-(2-hydroxy-4-butoxy-5-methylphenyl)-4,6-bis(2,4-dimethylphenyl)-s-tri , 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-biphenyl-s-triphenyl , 2,4-bis(2-hydroxy-4-octyloxyphenyl)-6-(2,4-dimethylphenyl)-s-tri 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-s-tris , 2-(4-isooctyloxycarbonyloxyphenyl)-4,6-diphenyl-s-triphenyl Triaryltri Category, etc.

As other ultraviolet absorbers, among the salicylic acid series, for example, phenyl salicylate, tertiary butylphenyl sulfate, p-octylphenyl sulfate, etc. can be used. In addition, natural substances (for example, oryzanol, shea butter, baicalin, etc.) and biological systems (for example, keratinocytes, melanin, urocanin, etc.) can also be used. Such ultraviolet absorbers can also be used in combination with hindered amine compounds as stabilizers. Inorganic ultraviolet absorbers are not compatible with the resin that serves as the base, which leads to an increase in haze, making the recognition of the image displayed on the authentication device worse, so they are not ideal.

When using a UV absorber, it can also be added to the outermost layer A of the laminated biaxial alignment film in the preferred embodiment of the present invention, or to the inner layer B, or both. Among them, it is best to contain the UV absorber only in the B layer. If the UV absorber is added to the outermost layer, the added UV absorber will precipitate on the surface of the film and easily evaporate, thereby contaminating the film forming machine, and the precipitate will have an adverse effect in the processing step, so it is not good. By adding it only to the inner layer, the outermost layer plays the role of a cover to prevent the UV absorber from evaporating, so precipitation is not easy to occur, which is better.

It is also possible to apply a coating to the film surface to impart functional properties such as scratch resistance. As a coating method, a coating with a hardening resin as the main component and melamine added can be used. A method of curing a crosslinking agent such as oxazoline by ultraviolet light.

As for the hardening resin, it is preferred to be highly transparent and durable. For example, acrylic resin, urethane resin, fluorine resin, silicone resin, polycarbonate resin, and vinyl chloride resin can be used alone or in combination. In particular, in terms of hardening, flexibility, and productivity, the hardening resin is preferably an active energy ray-hardening resin including acrylic resin represented by polyacrylate resin. In addition, when the film is applied to a portion where curved surface tracking is desired and the abrasion resistance when bent is required, the hardening resin is preferably a thermosetting urethane resin.

Furthermore, when the authentication device uses the distribution pattern of melanin existing in the epidermis as the identification object, since melanin strongly absorbs blue light from ultraviolet light, the wavelength of the light source is blue light (the wavelength of the maximum peak is 415nm or more and 495nm or less), and from the point of view of obtaining a clear pattern, the in-plane phase difference of the film is preferably in the range of ±120nm from an integer multiple of the wavelength of the light source, that is, there is an integer n that satisfies the following formula (V). When the wavelength of the light source is shorter than 415nm, there may be a problem of authentication error due to the degradation of the light source due to ultraviolet light and the increase of absorption other than melanin. (V) A×n-120≦Re≦A×n+120, and 415≦A≦495.

For example, in the case of using the distribution pattern of hemoglobin as the identification target as shown in venous authentication, hemoglobin has a strong absorption peak in the infrared region, so the wavelength of the light source is in the infrared region (the wavelength of the maximum peak is 800nm or more and 1200nm or less), and from the point of view of obtaining a clear pattern, it is better that the in-plane phase difference of the film is in the range of ±150nm, which is an integer multiple of the wavelength of the light source, that is, there is an integer n that satisfies the following formula (VIII). In addition, in the case of retina, iris, and face authentication, since the authentication target will directly see the light, it is sometimes better to use infrared light from the point of view of alleviating the discomfort of the authentication target. (VIII)A×n-150≦Re≦A×n+150, and 800≦A≦1200.

Similarly, depending on the color or design of the object to be authenticated, the wavelength of the light source may be green (the wavelength of the maximum peak is 495nm to 570nm), that is, there is an integer n that satisfies the following formula (VI). In addition, yellow to red may be preferred (the wavelength of the maximum peak is 570nm to 800nm), that is, there is an integer n that satisfies the following formula (VII). (VI) A×n-100≦Re≦A×n＋100, and 495≦A≦570. (VII) A×n-120≦Re≦A×n＋120, and 570≦A≦800.

In addition, combining multiple of the above wavelengths is also effective in improving authentication accuracy. In order to obtain the effect of the present invention, it is better to set the in-plane phase difference of the used film to an approximate common multiple of the wavelengths of each light source, or to use a film with a different in-plane phase difference for each light source.

The area of the authenticatable region in the authentication device of the present invention is not particularly limited and can be appropriately adjusted according to the object to be authenticated or the purpose. Since the authentication device of the present invention uses a film with a uniform in-plane phase difference and a main alignment axis, a larger area of the authenticatable region can be obtained. That is, the authentication device of the present invention can be preferably used in a device with an authenticatable region area of ¹⁰⁰ cm2 or more, further 225 ^cm2 or more, and further ⁴⁰⁰ cm2 or more.

As described above, the authentication device of the present invention can accurately identify various authentication objects, so it can be appropriately used in authentication devices that use at least one of fingerprints, irises, faces, hand shapes, body shapes, and veins as authentication objects. In addition, since the authentication device of the present invention can achieve good authentication accuracy even if the angle formed by the transmission axis of the polarizer and the main alignment axis of the film is large, the yield rate can be reduced.

[Evaluation method of characteristics] Evaluation of film A. In-plane phase difference (Re) and difference in in-plane phase difference (Δ phase difference) The in-plane phase difference and slow axis at a wavelength of 587.8nm with an incident angle of 0° were measured using "KOBRA-21ADH" manufactured by Oji Instruments Co., Ltd. The direction of the slow axis was set as the main alignment axis. The sample was cut into 5 pieces of 4cm×4cm from the film change site, and the average value of each measurement was used.

The unevenness of the in-plane phase difference is measured by measuring the in-plane phase difference at a total of four points: the two ends (A and B) showing the maximum length in the film plane, and the two ends (C and D) of the film that are perpendicular to the straight line AB connecting points A and B and passing through the midpoint of the straight line AB, and the difference between the maximum value and the minimum value is used.

B. PT(45) and PT(0) (1) Cut the polarizer used in the authentication device or a polarizer with the same polarization degree as the polarizer used (TS grid polarizing film (manufactured by Edmund Optics Japan Co., Ltd.)) into two pieces, arrange the two polarizers so that the surfaces of the two polarizers are perpendicular to the optical axis of a spectrophotometer with a 50W tungsten lamp as the light source, and the transmission axes of the two polarizers are parallel to each other, and perform background measurement in the light source off state and the light source on state. The amount of transmitted light measured in the light source off state is set as PT(D), and the amount of transmitted light measured in the light source on state is set as PT(L). (2) Arrange the above film between the two polarizers so that the surface of the film is perpendicular to the optical axis of the spectrophotometer. (3) The film is rotated only in a plane perpendicular to the optical axis of the spectrophotometer, and the amount of transmitted light at the wavelength with the strongest intensity of the light emitted from the light source is measured. The amount of transmitted light when the angle between the transmission axes of the two polarizers and the main alignment axis of the film is 0° is set as PT'(0), and the amount of transmitted light when the angle is 45° is set as PT'(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 380nm transmittance Using a spectrophotometer (U-4100 Spectrophotometer) manufactured by Hitachi High-Tech Co., Ltd., the transmittance at the incident angle = 0° was measured. Measurement conditions: slit was set to 2nm, gain was set to 2, and scanning speed was set to 600nm/min. The sample was cut out at 5 locations of 4cm×4cm from the film change site, and the average value of each measurement was used.

The reflector of the integrating sphere is made of alumina, the photometry method is a double-beam direct ratio photometry method, and the beam splitter is a prism, grating, and grating double monochromatic.

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

D. Elongation at break The film was cut from the center of the sample width into 10mm x 150mm width. A digital micrometer (HKT-1208 manufactured by Matsuo Sangyo) and a tensile testing machine (RTG1210) were used for measurement in accordance with JIS-C-2151 and ASTM-D-882. The sample was held with a chuck in the main orientation axis direction and stretched at a speed of 200mm/min to obtain the strength (the value obtained by dividing the cross-sectional area of the test piece by the tensile load value) and elongation when the sample was cut (broken). The tensile elongation was calculated using the following formula.

Tensile extension (%) = 100 × (L-Lo) / Lo

Lo: Length of sample before test

L: Length of the sample at fracture

The measurement was performed 5 times and the average value was used. Similarly, the elongation at the break point in the direction perpendicular to the main orientation axis was also measured. The measurement was performed in a room maintained at 25°C.

E. Light source wavelength and light source half-height width

A NA0.22 optical fiber was installed on a Hamamatsu Photonics mini spectrophotometer (C10083MD, C9914GB) to measure the light from the light source. The wavelength with the highest intensity in the range of 320nm to 1500nm was set as the light source wavelength, and the width of the peak intensity of 1/2 of the peak intensity of the light source wavelength was set as the half-height width.

F.Thickness

Use a digital micrometer (HKT-1208 manufactured by Matsuo Sangyo) to measure the center of the film in accordance with JIS-C-2151. Perform three measurements and use the average value.

Evaluation of certification devices G. Authenticity

In an environment of 23℃65RH%, the authentication object α is registered. In the case of Example 10, the iris is used as the authentication object, and in other cases, the fingerprint is used as the authentication object. Afterwards, the authentication object α and the unregistered authentication object β are alternately identified by the authentication device 200 times each. The identification time is set to 2 seconds each. The evaluation is based on the probability of rejecting α (false rejection rate: FRR (False Rejection Rate)) and the probability of accepting β (false acceptance rate: FAR (False acceptance rate)) as follows. A is good, B is acceptable, and C and D are not good. 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. Light source durability Maintain the light source of the certification device in a 23℃65RH% environment for 1000 hours, and evaluate the changes in the certification performance before and after the test. The judgment criteria are as follows. Among them, ΔFRR and ΔFAR represent the value of 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: Does not meet any of A, B, and C.

I. Impact durability Using a Film Impact Tester (manufactured by Toyo Seiki Seisaku-sho), using a hemispherical impact head with a diameter of 1/2 inch, the impact value was measured in an environment of temperature 23°C and humidity 65%RH. Each sample was measured 5 times. Then, the impact value of each time was divided by the film thickness of the attached measurement sample, and the average impact value per unit thickness was obtained from the average value of the 5 measurements. The measured values were evaluated as follows.

A: 1.0N‧m/mm or more

B: 0.5N‧m/mm or more, less than 1.0N‧m/mm

C: less than 0.5N‧m/mm.

J: Thermal shrinkage rate

For each of the MD and TD directions of the film, five samples with a width of 10 mm and a length of 200 mm (measurement direction) were cut out, and marks were added at 25 mm from both ends as marking lines. The distance between the marking lines was measured by a universal projector and set as the sample length (10). Then, the test piece was sandwiched between paper and kept in an oven at 100°C under zero load. After heating for 30 minutes, it was taken out and cooled at room temperature. The dimensions were measured with a universal projector (11) and the following formula was used to calculate the thermal shrinkage rate. The average value of the five strips was set as the thermal shrinkage rate.

Thermal shrinkage rate = {(10-11)/10}×100(%)

[Implementation example]

Although the present invention is described below with reference to the embodiments, the present invention is not necessarily limited to these limitations. In addition, Embodiment 13 and Embodiment 14 are used as Reference Examples 1 and 2.

(Implementation Example 1)

The light source and light sensitivity sensor used are ClearID FS9500 manufactured by Synaptics (light source wavelength 525nm, light source half-height width 30nm).

The polarizer used was VF-PS#7500 manufactured by Kuraray, which is a general polarizing film with a polarization degree of 80% or more. The film was prepared as follows.

(Resins used for film production) Resin A: Polyethylene terephthalate (PET) (intrinsic viscosity: 0.65) Resin B: Polyethylene terephthalate (PET/SPG/CHDC) copolymerized with 25 mol% of spiroglycerol relative to the total diol component and 30 mol% of cyclohexane dicarboxylic acid relative to the total dicarboxylic acid component (intrinsic viscosity: 0.72) Resin C: Resin B (90 wt%) and 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol] (10 wt%) as a UV absorber were mixed and pelletized using an extruder. Resin D: Resin A (90 wt%) and 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-(1,1,3,3,-tetramethylbutyl)phenol] (10 wt%) as a UV absorber were mixed and granulated using an extruder. Resin E: Polyethylene terephthalate (PET) containing 0.8 wt% of divinylbenzene/styrene copolymer particles with an average particle size of 0.70 μm and 1.5 wt% of agglomerated alumina particles with an average secondary particle size of 0.08 μm (intrinsic viscosity: 0.65).

(Film formation) Resin A is used as the resin constituting layer A, and resin C is used as the resin constituting layer B. Resin C is an amorphous resin with an intrinsic viscosity of 0.72, and the average refractive index in the plane after film formation is 1.55. Thermoplastic resin A and thermoplastic resin C were melted at 280°C by an extruder, respectively, and passed through five FSS-type leaf disc filters. Then, a gear pump was used to adjust the discharge ratio (layer ratio) to resin A/resin C = 1.5/1. The film thickness after biaxial stretching was measured to be 35 μm, and the feed blocks were alternately merged with 201 layers (101 layers for layer A and 100 layers for layer B). Then, it is supplied to a T-shaped die, formed into a sheet, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25°C while applying an electrostatic voltage of 8kV with a wire, thereby obtaining an unstretched multi-layer laminate film. This unstretched film is subjected to biaxial stretching in sequence. First, it is conveyed at 105°C with a Teflon (registered trademark) roller, and then, in the long-side direction, it is heated with an infrared heater with an output of 500W, and stretched 2.8 times at 95°C to obtain a uniaxially stretched film. This uniaxially stretched film was stretched 4.5 times in the width direction at 100°C in a tenter, and then heat-set at 220°C, at which time it was relaxed by 1.7% in the width direction and cooled in the conveying step, and then the edge was cut and rolled up to obtain a film. The physical properties of the obtained film are shown in Tables 1 and 3.

(Production of authentication device) Using optically clear adhesive (OCA), ClearID (light source, light sensitivity sensor), polarizer, and film are sequentially attached to obtain an authentication device. At this time, the main alignment axis of the film and the transmission axis of the polarizer are arranged in parallel. The authenticatable area of the authentication device is set to 1 cm ² . The characteristics of the obtained authentication device are shown in Table 2 and Table 4. An authentication device with excellent authentication and durability is obtained.

(Example 2) Except that the main orientation axis of the film attached to the device is set to 45° relative to the transmission axis of the polarizer, the authentication device is obtained in the same manner as in Example 1. As shown in Table 2, an authentication device with excellent authentication and durability can be obtained.

(Example 3) Except that the stretching ratio in the width direction is set to 5.5 times, the film and the authentication device are obtained in the same manner as in Example 2. An authentication device with excellent authentication and durability can be obtained.

(Example 4) Except that the stretching ratio in the long-side direction is set to 3.0 times, the film and the authentication device are obtained in the same manner as in Example 1. An authentication device with excellent authentication and durability can be obtained.

(Example 5) Except that the main orientation axis of the film is set to 10° relative to the transmission axis of the polarizer, the authentication device is obtained in the same manner as in Example 4. An authentication device with good authentication and excellent durability can be obtained.

(Example 6) Except that the main orientation axis of the film is set to 45° relative to the transmission axis of the polarizer, the authentication device is obtained in the same manner as in Example 4. An authentication device with good authentication and excellent durability can be obtained.

(Example 7) Except that the stretching ratio in the long side direction is set to 2.6 times, the film and the authentication device are obtained in the same manner as in Example 2. An authentication device with good authentication and excellent durability can be obtained.

(Example 8) Except for using resin D as the resin constituting layer B, the membrane and the authentication device are obtained in the same manner as in Example 2. An authentication device having good authentication and durability can be obtained.

(Example 9) Except that the temperature when stretching in the longitudinal direction is set to 90°C and the temperature when stretching in the width direction is set to 120°C, the film and the authentication device are obtained in the same manner as in Example 2. An authentication device with good authentication and excellent durability can be obtained.

(Example 10) The film and the authentication device were obtained in the same manner as in Example 2 except that the BM ET-200 manufactured by Panasonic was used as the light source and photosensitivity sensor instead of ClearID, and the elongation ratio in the long side direction was set to 3.2 times. An authentication device with excellent authentication and durability was obtained.

(Example 11) Except for using a three-layer feed block (layer A is the outer two layers, layer B is the inner one layer), the rest is the same as Example 2 to obtain a membrane and a certification device. It becomes a certification device with excellent certification.

(Example 12) Except for using resin B as the resin constituting layer B, the membrane and the authentication device are obtained in the same manner as in Example 2. The authentication device has excellent authentication properties.

(Implementation Example 13)

The film and the certification device were obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction was set to 1.05 times, the stretching ratio in the width direction was set to 1.05 times, and no heat treatment was performed. The certification device with excellent certification was obtained (as Reference Example 1).

(Example 14)

The film and the certification 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. The resulting certification device had excellent certification properties (as Reference Example 2).

(Example 15)

The authentication device was obtained in the same manner as in Example 1 except that the authenticatable area was set to 50 ^cm2 . This resulted in an authentication device with excellent authenticatability.

(Example 16)

Except that the stretching ratio in the long side direction is set to 4.2 times and the stretching ratio in the width direction is set to 2.3 times, the rest is the same as in Example 15 to obtain the film and the certification device. It becomes a certification device with good certification.

(Example 17)

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

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

(Example 19) Except for using the light source and light sensitivity sensor of ClearID and the light source and light sensitivity sensor of BM ET-200 at the same time, the authentication device is obtained in the same manner as in Example 2. Of ClearID and BM ET-200, the light intensity of the light source of ClearID is higher. This makes it possible to obtain an authentication device that has excellent authentication using only the data from the light sensitivity sensor of ClearID. Among the measurement items in Tables 3 and 4, the items necessary for the measurement of the wavelength of the light source are recorded outside the brackets for the measurement results at 525nm, and inside the brackets for the results at 850nm.

(Example 20) Except for setting the stretching ratio in the width direction to 5.7 times, the film and the certification device were obtained in the same manner as in Example 19. Of ClearID and BM ET-200, the light intensity of the light source of ClearID is higher. The certification device is one in which the data from either the light sensitivity sensor of ClearID or the light sensitivity sensor of BM ET-200 have excellent certification. Among the measurement items in Tables 3 and 4, the items that are necessary for the measurement of the light source wavelength are recorded outside the brackets for the measurement results at 525nm, and inside the brackets for the results at 850nm.

(Example 21) Except that the heat treatment temperature was set to 240°C, the membrane and the certification device were obtained in the same manner as in Example 5. As shown in Table 4, a certification device with good certification was obtained.

(Example 22) Except that the stretching ratio in the longitudinal direction was set to 2.6 times and the stretching ratio in the width direction was set to 4.0 times, the film and the authentication device were obtained in the same manner as in Example 2. As shown in Table 4, although the variation of the in-plane phase difference was slightly large, it was an authentication device with good authentication overall.

(Example 23) Except for using resin E instead of resin A, the membrane and the authentication device were obtained in the same manner as in Example 5. As shown in Table 4, an authentication device with good authentication properties was obtained.

(Example 24) Except for using 9 layers of feed blocks (5 layers on the outside of layer A and 4 layers on the inside of layer B), the membrane and certification device were obtained in the same manner as in Example 2. As shown in Table 4, a certification device with excellent certification was obtained.

(Example 25) Except for using a 101-layer feed block (51 layers on the outer side of layer A and 50 layers on the inner side of layer B) and adjusting the discharge rate to set the thickness after stretching to 18μm, the film and certification device were obtained in the same manner as in Example 2. Due to the thin film, the impact resistance is slightly reduced, but it becomes a film that can also be used for applications requiring a thin film. As shown in Table 4, it becomes a certification device with excellent certification.

(Comparative Example 1) Except that the stretching ratio in the long-side direction was set to 3.2 times and the main orientation axis of the film was set to 10° relative to the transmission axis of the polarizer, the film and the certification device were obtained in the same manner as in Example 2. The certification device was slightly inferior in certification.

(Comparative Example 2) Except for setting the stretching ratio in the long-side direction to 3.2 times, the film and the authentication device were obtained in the same manner as in Example 2. The authentication device was poor in authentication.

(Comparative Example 3) Except for setting the stretching ratio in the width direction to 4.9 times, the film and the authentication device were obtained in the same manner as in Example 2. The authentication device was poor in authentication.

(Comparative Example 4) Except that the stretching ratio in the longitudinal direction was set to 3.2 times and the stretching ratio in the width direction was set to 4.4 times, the film and the authentication device were obtained in the same manner as in Comparative Example 2. The authentication device was poor in authentication.

[Table 1] Film preparation conditions Membrane properties Main Layer Sublayer Vertical magnification (times) Magnification (times) PT(45) PT(45)/PT(0) Re (nm) Δ phase difference (nm) Transmittance(%) 380nm transmittance (%) Thermal shrinkage (MD/TD) (%) Elongation at break Direction perpendicular to the main orientation axis (%) Main orientation axis direction (%) Embodiment 1 A C 2.8 4.5 0.9 0.95 1050 50 91 <1% 0.7/1.5 140 80 Embodiment 2 A C 2.8 4.5 0.9 0.95 1050 50 91 <1% 0.7/1.5 140 80 Embodiment 3 A C 2.8 5.5 0.9 0.95 2100 20 90 <1% 0.5/1.8 150 60 Embodiment 4 A C 3 4.5 0.65 0.7 950 40 90 <1% 0.8/1.4 130 80 Embodiment 5 A C 3 4.5 0.65 0.7 950 40 90 <1% 0.8/1.4 130 80 Embodiment 6 A C 3 4.5 0.65 0.7 950 40 90 <1% 0.8/1.4 130 80 Embodiment 7 A C 2.6 4.5 0.65 0.7 1150 50 91 <1% 0.5/1.3 160 80 Embodiment 8 A D 2.8 4.5 0.9 0.95 2000 70 91 3% 0.7/2.0 100 60 Embodiment 9 A C 2.8 4.5 0.65 0.7 950 100 89 <1% 0.7/1.5 140 80 Embodiment 10 A C 3.2 4.5 0.9 0.95 850 30 90 <1% 1.0/1.4 130 100 Embodiment 11 A C 2.8 4.5 0.9 0.95 1050 50 90 30 0.7/1.5 90 40 Embodiment 12 A B 2.8 4.5 0.9 0.95 1050 50 90 5 0.7/1.5 140 80 Embodiment 13 A C 1.05 1.05 0.9 0.95 50 30 90 5 0.2/0.2 10 10 Embodiment 14 Polycarbonate - - 0.9 0.95 50 10 90 30 0.1/0.1 10 10 Embodiment 15 A C 2.8 4.5 0.9 0.95 1050 50 91 <1% 0.7/1.5 140 80 Embodiment 16 A C 4.2 2.3 0.85 0.95 1050 50 91 <1% 1.3/0.8 90 130

[table 3] Film preparation conditions Membrane properties Main Layer Sublayer Vertical magnification (times) Magnification (times) PT(45) PT(45)/PT(0) Re(nm) Δ phase difference (nm) Transmittance(%) 380nm transmittance (%) Thermal shrinkage (MD/TD) (%) Elongation at break Direction perpendicular to the main orientation axis (%) Main orientation axis direction (%) Embodiment 17 A C 2.8 4.4 0.9 0.95 1030 (1050) 50 91 <1% 0.7/1.4 140 85 Embodiment 18 A C 2.8 4.4 0.9 0.95 1030 (1050) 50 91 <1% 0.7/1.4 140 85 Embodiment 19 A C 2.8 4.5 0.9 (0.3) 0.95 (0.35) 1050 50 91 (91) <1% 0.7/1.5 140 80 Embodiment 20 A C 2.8 5.7 0.85 (0.85) 0.9 (0.9) 2600 50 91 (91) <1% 0.5/2.2 160 40 Embodiment 21 A C 3 4.5 0.65 0.7 950 40 90 <1% 0.8/1.1 130 80 Embodiment 22 A C 2.6 4 0.9 0.95 1050 120 91 <1% 0.7/1.5 140 80 Embodiment 23 E C 3 4.5 0.6 0.7 950 40 90 <1% 0.8/1.4 130 80 Embodiment 24 A C 2.8 4.5 0.9 0.95 1050 50 90 30 0.7/1.5 100 60 Embodiment 25 A C 2.8 4.5 0.9 0.95 525 20 91 <1% 0.9/1.9 120 60 Comparison Example 1 A C 3.2 4.5 0.45 0.5 850 30 90 <1% 1.0/1.4 140 80 Comparison Example 2 A C 3.2 4.5 0.45 0.5 850 30 90 <1% 1.0/1.4 140 80 Comparison Example 3 A C 2.8 4.9 0.05 0.05 1300 50 90 <1% 0.6/1.7 140 70 Comparison Example 4 A C 3.2 4.4 0.05 0.05 800 60 90 <1% 1.0/1.4 100 100

[Possibility of industrial application]

The authentication performance of the authentication device of the present invention does not depend on the film's orientation angle, and the durability of the light source and polarizer can be improved by the film absorbing and reflecting ultraviolet rays, and cheap polyester can be used as the raw material of the film. Therefore, it has good authentication performance and durability, is cheap and has excellent productivity.

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

FIG1 is a diagram schematically showing an example of the structure of the authentication device of the present invention.

FIG. 2 is a diagram showing an example of the role of the authentication light used in the authentication device of the present invention.

without.

Claims (19)

An authentication device comprises a light source, a polarizer, a film, and a light sensitivity sensor, wherein the film is disposed between the polarizer and the authentication object and satisfies all of the following (1), (2), (3), and (4): (1) the transmittance of light emitted from the light source is 70% or more and 100% or less at the wavelength of the strongest intensity of the light; (2) there exists an integer n satisfying the following formula (I): (I) A×n-150≦Re≦A×n+ 150 Here, A is the wavelength (nm) at which the light emitted from the aforementioned light source exhibits the strongest intensity, Re is the in-plane phase difference (nm) when the aforementioned film is measured at a wavelength of 587.8nm with an incident angle of 0° using the parallel Nicol rotation method, (3) the in-plane phase difference of the aforementioned film is 400nm or more, (4) the elongation at the break point of the aforementioned film at 25°C in the direction of the main alignment axis and in the direction orthogonal to the main alignment axis is 30% or more and 300% or less. As in claim 1, the authentication device satisfies the above formula (I), and there exists an integer m that satisfies the following formula (II), (II) B×m-150≦Re≦B×m+150, where B is the wavelength (nm) of the second strongest intensity of the light emitted from the above light source, and Re is the in-plane phase difference (nm) when the above film is measured at a wavelength of 587.8nm with an incident angle of 0° using the parallel Nicol rotation method. A certification device as claimed in claim 1 or 2, wherein the aforementioned 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, and the surfaces of the two polarizers are perpendicular to the optical axis of a spectrophotometer using a 50 W tungsten lamp as a light source, and the transmission axes of the two polarizers are arranged in parallel to each other, and background measurement is performed in the light source off state and the light source on state, and the transmitted light amount measured in the light source off state is set as PT(D), and the transmitted light amount measured in the light source on state is set as PT(L), (2) the aforementioned polarizer is placed between the two polarizers. The film is arranged so that the surface of the film is perpendicular to the optical axis of the spectrophotometer. (3) The amount of transmitted light in the wavelength with the strongest intensity of the light emitted from the light source is measured while the film is rotated only in the plane perpendicular to the optical axis of the spectrophotometer. The amount of transmitted light when the angle between the transmission axes of the two polarizers and the main orientation axis of the film is 0° is set as PT'(0), and the amount of transmitted light when the angle is 45° is set as PT'(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)). For example, in the authentication device of claim 1 or 2, the half-width of the peak value of the strongest intensity in the light emitted from the aforementioned light source is greater than 5nm and less than 70nm. For example, in the authentication device of claim 1 or 2, there exists an integer n satisfying the following formula (V), (V)A×n-120≦Re≦A×n+120, and 415≦A≦495. For example, in the authentication device of claim 1 or 2, there exists an integer n satisfying the following formula (VI), (VI) A×n-100≦Re≦A×n+100, and 495≦A≦570. For example, in the authentication device of claim 1 or 2, there exists an integer n satisfying the following formula (VII), (VII) A×n-120≦Re≦A×n+120, and 570≦A≦800. For example, in the authentication device of claim 1 or 2, there exists an integer n satisfying the following formula (VIII), (VIII) A×n-150≦Re≦A×n+150, and 800≦A≦1600. As in claim 1 or 2, the certification device, wherein the in-plane phase difference of the aforementioned film is less than 3000nm. As in claim 1 or 2, the aforementioned film is alternately laminated with 5 or more layers containing resin A and layers containing resin C different from resin A. As in the authentication device of claim 10, the resin C constituting the aforementioned membrane contains at least one of cyclohexanedimethanol, spiroglycerol, neopentyl glycol, isophthalic acid, cyclohexanedicarboxylic acid, and isosorbide, and has polyester as the main component. As claimed in claim 1 or 2, the ratio of the maximum value to the minimum value of the thermal shrinkage rate of the aforementioned film in the direction of the main alignment axis and the direction perpendicular to the main alignment axis when treated at 100°C for 30 minutes (maximum value/minimum value) is greater than 1.7. As in claim 1 or 2, the authentication device, wherein the angle between the main alignment axis of the aforementioned film and the transmission axis of the aforementioned polarizer is less than 10°. The certification device of claim 1 or 2, wherein the difference between the maximum and minimum values of the in-plane phase difference of the aforementioned film at the two ends (A, B) showing the maximum length in the film surface and the two ends (C, D) of the film perpendicular to the straight line AB connecting points A and B and passing through the midpoint of the straight line AB is less than 200 mm. An authentication device as claimed in claim 1 or 2, wherein the area of the authenticatable region is greater than ¹⁰ cm2. The authentication device of claim 1 or 2, wherein the light source comprises any one of an organic EL (organic electroluminescent element) and a light emitting diode (LED), and the light transmittance of the film at a wavelength of 380nm is less than 5%. The authentication device of claim 1 or 2, wherein the aforementioned light sensitivity sensor is a CMOS (Complementary metal-oxide-semiconductor) sensor. A film is used in an authentication device having a light source, a polarizer, a film, and a photosensor, the film satisfying the following (1), (2), (3), and (4), (1) the transmittance of the film from the light source to the light is 70% or more and 100% or less at the wavelength of the strongest intensity of the light, (2) there exists an integer n satisfying the following formula (I), (I) A×n-150≦Re≦A×n+150, where A is The wavelength (nm) at which the light emitted from the aforementioned light source exhibits the strongest intensity, Re is the in-plane phase difference (nm) of the aforementioned film when measured at a wavelength of 587.8nm with an incident angle of 0° using the parallel Nicol rotation method, (3) the in-plane phase difference of the aforementioned film is 400nm or more, (4) the elongation at the break point of the aforementioned film at 25°C in the direction of the main alignment axis and in the direction orthogonal to the main alignment axis is 30% or more and 300% or less. The film of claim 18, 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 in the following manner: (1) the polarizer is cut into two pieces, and the surfaces of the two polarizers are perpendicular to the optical axis of a spectrophotometer using a 50 W tungsten lamp as a light source, and the transmission axes of the two polarizers are arranged in parallel to each other, and background measurement is performed, and the amount of transmitted light measured when the light source is off is set as PT(D), and the amount of transmitted light measured when the light source is on is set as PT(L); (2) the film is placed between the two polarizers so that the surface of the film is perpendicular to the optical axis of the spectrophotometer using a 50 W tungsten lamp as a light source. The optical axis of the spectrophotometer is arranged in a manner perpendicular to the optical axis of the spectrophotometer. (3) The film is rotated in a plane perpendicular to the optical axis of the spectrophotometer while the amount of transmitted light at the wavelength with the strongest intensity among the light emitted from the light source is measured. The amount of transmitted light when the angle between the transmission axes of the two polarizers and the main alignment axis of the film is 0° is set as PT'(0), and the amount of transmitted light when the angle is 45° is set as PT'(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)).