CN115394189A

CN115394189A - Image display device with fingerprint verification sensor

Info

Publication number: CN115394189A
Application number: CN202210934475.2A
Authority: CN
Inventors: 柴野博史
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2018-09-28
Filing date: 2019-09-26
Publication date: 2022-11-25
Anticipated expiration: 2039-09-26
Also published as: CN112740304A; JP7405107B2; JP6863530B2; WO2020067243A1; KR102532989B1; KR20220002705A; KR20210046071A; JPWO2020067243A1; TW202018343A; JP2021101250A; KR102344400B1

Abstract

There may be provided: in an image display device having a polarizing plate on the visible side of a fingerprint verification sensor, a fingerprint verification system normally operates even when an alignment film is present on the visible side of the polarizing plate. An image display device comprising a polarizing plate on the visible side of a fingerprint verification sensor and an alignment film on the visible side of the polarizing plate, wherein the angle formed between the main alignment direction of the alignment film and the extinction axis direction of the polarizing plate is 0 DEG + -6 DEG or less or 90 DEG + -6 DEG or less. (in the above description, "hereinafter" merely means a value of "+ -").

Description

Image display device with fingerprint verification sensor

The application is a divisional application of an application with the application date of 2019, 9 and 26, and the application number of 201980061456.X, and the name of the invention of an image display device with a fingerprint verification sensor.

Technical Field

The present invention relates to an image display device having a fingerprint authentication sensor and an alignment film on a visible side thereof.

Background

Conventionally, in an image display device, a surface protective film is bonded for surface protection. The surface protective film is an oriented film such as biaxially stretched polyester having excellent impact resistance, and is used not only for preventing scratches on the surface but also for preventing scattering when the image unit or the surface glass plate is broken. In addition, in the image display device, a biaxially stretched polyester film is used as a member of a touch sensor or a scattering prevention film of a member of glass.

On the other hand, in order to ensure high security in mobile terminals and the like, face authentication systems and fingerprint authentication systems have been increasingly used (patent documents 1 and 2).

Due to the limitation of the size of the movement, the following solutions are proposed for making the mobile terminal large-sized: the entire body is used as a display screen, and a sensor of the authentication system is incorporated in the screen (in the depth of the image display region when viewed from the visible side). In particular, in an organic electroluminescence (organic EL) image display device, a sensor for fingerprint authentication can be operated through a gap between pixels of an image display unit, and such a method is widely used.

In an image display device having a fingerprint authentication system on the screen, a polarizing plate is provided on the visible side of a sensor for authentication, but in such an image display device, when an oriented film is present on the visible side of the polarizing plate, particularly when a biaxially stretched polyester film is used as the oriented film, the fingerprint authentication system may not operate (sense) or malfunction (misidentification value).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-006648

Patent document 2: japanese patent publication (Kohyo) No. 2018-515820

Disclosure of Invention

Problems to be solved by the invention

The present invention was made in view of the above-mentioned problems of the prior art. That is, an object of the present invention is to provide: an image display device having a fingerprint authentication system and further having an orientation film, wherein the fingerprint authentication system can operate normally.

Means for solving the problems

The present inventors have conducted intensive studies to achieve the above object, and as a result, the present invention has been completed. Namely, the representative invention is as follows.

Item 1.

An image display device having a polarizing plate on the visible side of a fingerprint authentication sensor and an alignment film on the visible side of the polarizing plate,

the angle formed between the main orientation direction of the orientation film and the extinction axis direction of the polarizer of the polarizing plate is 0 degree + -6 degrees or less, or 90 degrees + -6 degrees or less.

(in the above, "hereinafter" merely means the value after "+ -.)

ADVANTAGEOUS EFFECTS OF INVENTION

In an image display device having a polarizing plate on the visible side of a fingerprint authentication sensor, even in the case where an alignment film is present on the visible side of the polarizing plate, an image display device in which a fingerprint authentication system normally operates can be provided.

Drawings

Fig. 1 shows an example in which the fingerprint authentication sensor unit is provided outside the display screen (image display unit).

Fig. 2 shows an example in which the fingerprint authentication sensor unit is provided in a display screen (image display unit).

Fig. 3 is a cross-sectional view showing an example of a case where the fingerprint authentication sensor unit is provided in a display screen (image display unit).

Description of the reference numerals

1. Image display device

2. Image display unit

3. Fingerprint verification sensor unit

21. Image display unit

22. Polarizing plate

23. Adhesive layer

24. Orientation film (surface protective film)

31. Fingerprint verification sensor body

Detailed Description

(image display device)

The present invention provides an image display device having a polarizing plate on the visible side of a fingerprint authentication sensor and further having an alignment film on the visible side. The fingerprint authentication sensor (fingerprint authentication sensor portion) may be provided outside the display screen or may be provided within the display screen (in the image display region and in the depth thereof when viewed from the visible side). For example, here, the outside of the display screen refers to the state of fig. 1, and the inside of the display screen (the depth of the image display region when viewed from the visible side) refers to the state of fig. 2. The type of being provided in the display screen is also called a screen-embedded type, and for example, as shown in fig. 3, the fingerprint authentication sensor main body is provided in a deep portion of the screen as viewed from the visible side. In fig. 3, an image display unit (e.g., an organic EL unit) is disposed on the visible side of the fingerprint authentication sensor body. A polarizing plate (preferably, a circularly polarizing plate in the case where the image display unit is an organic EL unit) is disposed on the visible side of the image display unit. An alignment film is disposed on the visible side of the polarizing plate with an adhesive layer interposed therebetween.

In general, since a polarizing plate is provided in an image display region on an image display unit, an image display device of a type in which a fingerprint authentication sensor is provided in a display screen is an object of the present invention, but an image display device of a type in which a fingerprint authentication sensor is provided outside a display screen is also an object of the present invention in which a polarizing plate is provided so as to cover the fingerprint authentication sensor.

The image display device is preferably a smartphone, a mobile PC, a PDA, a mobile phone, a game machine, a camera, an electronic dictionary, or the like.

(image display Unit)

The image display unit used in the image display device of the present invention is not particularly limited, and a liquid crystal display unit and an organic EL (OLED) unit are preferable examples in terms of being able to be reduced in size and thickness. Among them, the organic EL unit is a preferable example in which a sensor for fingerprint authentication can be operated through a gap between pixels of the unit.

(fingerprint authentication sensor)

The fingerprint authentication sensor is not particularly limited, and is preferably an optical type or an ultrasonic type, and particularly preferably an optical type, from the viewpoint of compatibility with the configuration of the image display device of the present invention.

An optical fingerprint verification sensor is commercially available from, for example, synaptics under the trade name "Clear ID".

An ultrasonic Fingerprint verification sensor is commercially available, for example, from Qualcomm Technologies under the trade name "Qualcomm finger Sensors".

(polarizing plate)

As described above, the image display device is in a state where the polarizing plate is provided on the visible side of the fingerprint authentication sensor. The polarizing plate generally includes a polarizing plate having a function of generating polarized light and a polarizing plate protective film for protecting the polarizing plate, but the polarizing plate protective film may be laminated only on one surface of the polarizing plate, or may be only the polarizing plate. Examples of the polarizing plate include: a thin film in which iodine, an organic dichroic dye, or the like is adsorbed in uniaxially aligned polyvinyl alcohol, an alignment film formed of a liquid crystal compound and an organic dichroic dye, or the like can be used without particular limitation.

The polarizer protective film is not particularly limited, and an unstretched or stretched film of cellulose, polyester, cyclic polyolefin, acrylic, polycarbonate, or the like can be used. However, in the case of a stretched film of polyester or the like, the extinction axis of the polarizing plate is preferably parallel to or perpendicular to the main orientation direction of the stretched film. Here, parallel or perpendicular means that the angle formed by the extinction axis of the polarizing plate and the main orientation direction of the stretched film is not strictly 0 degree or 90 degrees, and the allowable range is ± 6 degrees, more preferably ± 5 degrees, further preferably ± 4 degrees, particularly preferably ± 3 degrees, and most preferably ± 2 degrees.

The extinction axis of the polarizer of the polarizing plate is parallel to the long side of the screen, perpendicular to the long side of the screen, or oriented at 45 degrees. These directions are determined according to the kind and purpose of the image display unit, and are not particularly limited in the present invention. For example, in the case of an organic EL display unit, the organic EL display unit is often arranged at 45 degrees.

A phase difference layer may be provided between the polarizing plate and the image display unit. The retardation layer may be a retardation film obtained by stretching a resin, or an alignment film of a liquid crystal compound obtained by applying and aligning a liquid crystal compound.

In the case of an organic EL cell, a circularly polarizing plate provided with a 1/4 wavelength layer is used as a retardation layer in order to suppress reflection of metal wiring of the cell and the like. The retardation layer of the circularly polarizing plate is disposed on the organic EL unit side.

(alignment film)

In the image display device of the present invention, the visible side of the fingerprint authentication sensor is provided with a polarizing plate, and the visible side of the fingerprint authentication sensor is provided with an orientation film. The alignment film is preferably used as a surface protective film for preventing scratching of an image display surface or preventing scattering of glass when a glass member such as an image display unit, a touch sensor, or surface protective glass is broken by an impact, a transparent conductive film also used as an electrode of a touch sensor, a scattering prevention film for preventing scattering of laminated glass by being placed inside a display device and being bonded to the glass member, and the like.

The surface protective film is preferably peeled off and attached to be replaced when the film itself is scratched. The surface protective film is preferably bonded to the image display device by an optical substrate-free adhesive sheet.

The resin constituting the orientation film may be any resin such as polyester, polyamide, polypropylene, polycarbonate, polystyrene, acrylic resin, cyclic polyolefin, cellulose, and the like, and polyester, particularly polyethylene terephthalate is preferable because of the characteristics as a protective film such as heat resistance, mechanical strength, and dimensional stability.

The oriented film is oriented by stretching, and the mechanical strength is improved. The oriented film may be a uniaxially oriented film (uniaxially stretched film) or a biaxially oriented film (biaxially stretched film). From the viewpoint of excellent mechanical strength in all directions, a biaxially oriented film (biaxially stretched film) is preferred. On the other hand, a uniaxially stretched film is preferable from the viewpoint of excellent uniformity of orientation. When a film is biaxially stretched in an industrial tenter, a bow strain (bowing phenomenon) occurs in the main orientation direction in the width direction of the film, but in a uniaxially oriented film uniaxially stretched in the width direction, the strain is reduced, and the uniaxially oriented film has an orientation direction intended for a wide range of purposes in the width direction, and a film excellent in orientation uniformity can be secured, and it is advantageous in terms of improvement in productivity that bonding, punching processing, and the like under the same conditions can be realized. However, in a completely uniaxially stretched film, the mechanical strength sometimes becomes weak against a force orthogonal to the orientation direction. In this case, in order to improve the mechanical strength in the direction orthogonal to the main orientation direction, it is also preferable to apply stretching weakly in the direction orthogonal to the main stretching direction (the film thus obtained is hereinafter referred to as a weakly biaxially stretched film or a weakly biaxially oriented film). The weak stretching may be performed after the main stretching, but is preferably performed before the main stretching, or simultaneously. Of course, it may be completely uniaxially stretched.

The stretching is usually performed by roll stretching using rolls that are continuous in the flow direction (longitudinal direction) of the film, and the simultaneous stretching in the width direction (transverse direction) and longitudinal and transverse directions is performed by stretching using a tenter.

In the present invention, the main orientation direction (main stretching direction) may be the flow direction or the width direction.

Here, when the ratio of (elastic modulus in a direction orthogonal to the main orientation direction)/(elastic modulus in the main orientation direction) is 0.5 or less, or (breaking strength in a direction orthogonal to the main orientation direction)/(breaking strength in the main orientation direction) is 0.5 or less, the film may be a uniaxially oriented film or a weakly biaxially oriented film.

The stretching may be performed at an appropriate temperature, magnification, and speed depending on the respective raw materials. In addition, the biaxial stretching and the weak biaxial stretching are mainly adjusted at each stretching ratio.

In addition, if the film is a polyethylene terephthalate film, the difference (Δ Nxy) between the refractive index in the main orientation direction and the refractive index in the direction perpendicular thereto is 0.055 or more, preferably 0.06 or more, and it can be referred to as a weakly biaxially stretched film. In addition, if the refractive index of the slow axis is 1.68 or more, preferably 1.685 or more, and Δ Nxy is 0.095 or less, preferably 0.093 or less, it can be said that weak biaxial stretching is applied.

As described above, in order to secure mechanical strength in each direction, a biaxially oriented film (biaxially stretched film) is preferable, and Δ Nxy is preferably less than 0.06, and more preferably less than 0.055, but homogeneous/uniform biaxial orientation is not only difficult, but also the orientation direction in a film produced in the same lot is likely to change due to some fluctuation in production conditions and the like. In production, Δ Nxy is preferably 0.01 or more, more preferably 0.015 or more, and particularly preferably 0.02 or more, in order to have a uniform orientation direction over a large area of the thin film.

In addition, Δ Nxy is preferably 0.065 or more, more preferably 0.070 or more, still more preferably 0.75 or more, particularly preferably 0.80 or more, and most preferably 0.85 or more, in order to improve uniaxiality and stabilize the orientation direction over the entire width of the film. Δ Nxy is preferably 0.16 or less, further preferably 0.15 or less, particularly preferably 0.14 or less, and most preferably 0.13 or less. If the amount exceeds the above range, the film is too easily broken, and the film may not be able to maintain the function of the film when used as a surface protective film.

The method for producing the alignment film is not particularly limited. For example, when a polyethylene terephthalate film is used as an alignment film, the film can be produced by the following method.

Generally, stretching is performed as follows: as the first stage of stretching, stretching was performed on continuous rolls in the longitudinal direction (the flow direction of the film), and then as the second stage of stretching, in the width direction (the direction orthogonal to the flow direction of the film), both ends of the width of the film were held by clips and stretched in a tenter. It should be noted that the first stage drawing and the second stage drawing may be reversed. The draw ratio in the first stage is preferably 1.0 to 3.5 times, and particularly preferably 1.0 to 3.0 times. The stretch ratio in the second stage is preferably 2.5 to 6.0 times, and particularly preferably 3.0 to 5.5 times. In the case of only uniaxial stretching, the stretching ratio in the second stage is preferably used. In any drawing, the drawing temperature is preferably 80 to 130 ℃ and particularly preferably 90 to 120 ℃. Further, both widthwise ends of the unstretched film may be fixed by a jig, and simultaneously biaxially stretched in the longitudinal direction and the widthwise direction. Then, it is desirable to perform heat treatment at preferably 100 to 250 ℃ and more preferably 180 to 245 ℃. The tenter stretching may be performed in the width direction or in an oblique direction with respect to the longitudinal direction.

(angle between extinction axis (absorption axis) of polarizing plate and main alignment direction of alignment film)

In the present invention, the extinction axis (absorption axis) of the polarizing plate and the main alignment direction (direction parallel to the main alignment axis) of the alignment film are preferably parallel or perpendicular. Here, the parallel or perpendicular means that the angle formed by the extinction axis of the polarizing plate and the main alignment direction of the alignment film must be strictly 0 degree or 90 degrees, preferably 0 degree ± 6 degrees or less or 90 degrees ± 6 degrees or less, more preferably 0 degree ± 5 degrees or less or 90 degrees ± 5 degrees or less, further preferably 0 degree ± 4 degrees or less or 90 degrees ± 4 degrees or less, particularly preferably 0 degree ± 3 degrees or less or 90 degrees ± 3 degrees, and particularly preferably 0 degree ± 2 degrees or less or 90 degrees ± 2 degrees or less. It should be noted that the term "below" refers to a numerical value of "+ -" only. Therefore, for example, the term "0 degrees ± 6 degrees or less" means that a range of up and down 6 degrees is allowed with 0 degree as a center. Similarly, "90 degrees ± 6 degrees or less" means that a range of up to and down to 6 degrees is allowed around 90 degrees.

When a plurality of alignment films are present, it is preferable that all the alignment films have the above relationship.

If the angle between the extinction axis of the polarizing plate and the main alignment direction of the alignment film exceeds a preferable range, the sensor may not operate, resulting in a malfunction. This is considered to be because the optical fingerprint sensor irradiates light from below onto the display device surface and reads a fingerprint by the reflected light, but if a polarizing plate is present on the sensor (on the visible side), the light that has become linearly polarized light advances within the alignment film having a phase difference at an angle deviating from the optical axis due to the polarizing plate, and becomes elliptically polarized light, and is also affected by the alignment film having a phase difference when passing through the polarizing plate again after being reflected, and the amount of light in a specific wavelength region in the image reception image of the sensor decreases, and therefore, when the light reception wavelength of the sensor is determined, it becomes difficult to detect an accurate pattern of a fingerprint. It is also considered that this is because, even when the sensor receives light in a wide wavelength region, the overall light amount is reduced, and it is not possible to maintain the accuracy of the sensor and the subsequent processing. The reason is merely to be assumed, and the present technology is not limited thereto.

The main orientation direction is a direction in which a slow axis and a fast axis are measured using a molecular orientation meter (for example, MOA-6004 type molecular orientation meter, manufactured by prince measuring instruments), and the slow axis is used as a main orientation axis. In addition, styrene resins and the like having a negative photoelastic coefficient have a fast axis as a main orientation direction.

The thickness of the alignment film may be suitably set according to the purpose, and is preferably 5 to 200. Mu.m. Further preferably 10 to 150. Mu.m, particularly preferably 20 to 100. Mu.m. If the thickness is less than 5 μm, the thickness is too small, and not only the workability may be deteriorated, but also sufficient mechanical strength may not be secured for the purpose when the composition is used as a surface protective film or the like. If it exceeds 200 μm, the rigidity becomes excessively high, and not only the workability may be deteriorated, but also the display device may not be thin.

The in-plane retardation of the alignment film is not particularly limited as long as it is not less than a level at which a clear state can be observed as the orientation direction of molecules, and is preferably not less than 1000 nm. In addition, in the case of a smartphone or the like, the operation is often performed in a state where polarized sunglasses are worn in the field, and when the polarized sunglasses are worn, coloration or rainbow unevenness may occur in some cases when viewed from an oblique direction. In order to reduce rainbow unevenness generated when the image display device is observed from an oblique direction, the in-plane retardation of the alignment film is preferably 3000nm or more. Further preferably 4500nm or more, particularly preferably 6000nm or more. The in-plane retardation is preferably 30000nm or less, more preferably 10000nm or less, and still more preferably 9000nm or less. Even if the in-plane retardation exceeds 30000nm, it is difficult to expect a significant improvement in the effect of improving the iridescence, and further, a thickness is required, and it is necessary to significantly increase the uniaxial orientation for thinning, and the mechanical strength in the direction perpendicular to the orientation direction may be lowered.

(surface working, etc.)

The alignment film may be surface-processed according to the purpose. For example, if the surface protective film is used, it is a hard coat layer, an antireflection coating layer, a low reflection coating layer, an antistatic coating layer, or the like. In addition, an easy adhesion coating may also be provided.

In the case where a fingerprint is pressed against the surface of the alignment film to detect the reflection thereof, the visible side of the surface protective film is preferably smooth to the extent that the fingerprint can be recognized. The surface roughness SRa of the visible-side surface is preferably 100nm or less, more preferably 50nm or less, and particularly preferably 30nm or less.

The total light transmittance of the alignment film is preferably 80% or more, more preferably 85% or more, and particularly preferably 88% or more. The haze of the alignment film is preferably 3% or less, more preferably 2.5% or less, and particularly preferably 2% or less.

Examples

The present invention will be further described in detail with reference to examples, but the present invention is not limited thereto.

(1) Breaking strength

Measured according to JIS C-2318.

(2) Modulus of elasticity

Measured according to JIS C-2318.

(3) Retardation amount,. DELTA.Nxy

The retardation is a parameter defined as a product (Δ Nxy × d) of anisotropy of refractive index (Δ Nxy = | nx-ny |) of biaxial perpendicular to the film and the film thickness d (nm), and is a measure representing optical isotropy and anisotropy. The biaxial refractive index anisotropy (Δ Nxy) is obtained by the following method. The slow axis direction of the film was determined using a molecular orientation meter (MOA-6004, manufactured by Oji scientific instruments), and a rectangle of 4 cm. Times.2 cm was cut out so that the slow axis direction was parallel to the long side of the measurement sample, and used as the measurement sample. For this sample, refractive indices of two orthogonal axes (refractive index in the slow axis direction: nx, refractive index in the direction orthogonal to the slow axis direction in the plane (i.e., refractive index in the fast axis direction: ny) and refractive index in the thickness direction (nz) were obtained by an Abbe refractometer (manufactured by ATAGO, NAR-4T, measurement wavelength 589 nm), and the absolute value of the difference in refractive indices of the two axes (| nx-ny |) was used as the anisotropy of refractive index (. DELTA Nxy). The thickness D (nm) of the thin film was measured by an electronic micrometer (Millitron 1245D, manufactured by FEINPRUF corporation), and the unit was converted to nm. The retardation (Re) is determined from the product (Δ Nxy × d) of the anisotropy of the refractive index (Δ Nxy) and the thickness d (nm) of the thin film.

(4) Extinction axis of polarizing plate

An image display device which is formed by peeling off a surface protection film and the like to enable linear polarized light to emit light is turned on, a polarization filter with a known extinction axis is placed on the image display device, the direction of the extinction axis of the polarization filter in the darkest state is obtained, and the direction which is 90 degrees to the direction is taken as the extinction axis direction.

(5) Main direction of orientation

The measurement was carried out using a molecular orientation meter (MOA-6004 molecular orientation meter, manufactured by Oji molecular instruments Co., ltd.).

(6) Light transmittance

Measured according to JIS K-7105.

(7) Haze (haze)

Measured according to JIS K-7105.

(8) Three-dimensional center plane average surface roughness (SRa):

a film having an area of 50mm × 50mm was cut out, and the film was measured from a direction perpendicular to the film surface using a three-dimensional surface shape measuring apparatus (manufactured by Ryoka systems Inc., micromap 550N (measurement conditions: wave mode, measurement wavelength 560nm, and objective lens magnification)), and a CCD camera image collection area of 400 μm × 400 μm was specified to obtain SRa according to the following formula. The number of measurements on both surfaces of the film was 16, and the average value of the numbers was determined. The mantissa of the decimal point or less is rounded up to an integer.

Here, S _M And = Lx × Ly, lx and Ly are ranges in the x and y directions, and f (x, y) is the height of the measurement point (x, y) from the average plane.

(9) Number of successful verifications

10 starts were attempted using fingerprint verification, expressed as the number of starts that can be made. After wiping dirt with a wet towel, the fingertips were wiped off, and then the moisture was removed with a dry towel, and after about 3 seconds, the fingertips were placed on the sensor portion.

(10) Surface protection characteristics

An alignment film was attached to a commercially available surface protective glass for a smartphone using an optical adhesive to prepare a test sample. The sample was placed on a stage (film surface was on) with a spacer having a thickness of 5mm provided at each side of the sample, and a steel ball was dropped from above. The test was carried out on 5 samples. When the glass did not break, the steel ball was dropped again.

O: the glass, although broken, did not have a film broken sample.

And (delta): there was a sample in which minute film cracking was confirmed at the collision portion of the steel ball.

X: samples with the film substantially cracked.

(11) Iridescent speckle Observation

An image display device for fingerprint verification test is observed from an oblique direction in a state that polarized sunglasses are arranged.

O: no iridescent plaque was confirmed

And (delta): weak rainbow spots were confirmed

X: a clear rainbow spot was confirmed.

(preparation of alignment film)

The following alignment films a, B, and C were prepared. The properties are shown in table 1.

An alignment film A:

a film having a film thickness of 75 μm made by Toyobo Co., ltd, COSMOSHINE (registered trademark) A4300 was used. Since the main orientation direction differs depending on the slit position of the film roll, a portion of the main orientation direction that is 90 degrees ± 6 degrees or less with respect to the longitudinal direction of the film roll is cut out and used.

An alignment film B:

after drying polyethylene terephthalate pellets (intrinsic viscosity 0.60dl/g (dissolved in a mixed solvent of phenol: 1, 2-tetrachloroethane = 6: 4 and measured at 30 ℃), which contained 0.7 mass% of porous silica having an average particle diameter of 0.9 μm, the pellets were melted at 280 ℃ by a melt extruder and extruded into a sheet form on a cooling roll to obtain an undrawn polyethylene terephthalate sheet. Then, a coating agent for an easy-adhesion layer containing a water-dispersible polyester resin and a blocked isocyanate-modified polyurethane aqueous dispersion was applied to one surface of the unstretched sheet, and the resultant was introduced into a tenter type simultaneous biaxial stretching machine, introduced into a hot air zone at a temperature of 125 ℃ while holding the ends of the film with clips, and stretched 1.8 times in the longitudinal direction and 4 times in the width direction. The treatment was carried out at 225 ℃ for 10 seconds while keeping the state, and further 2.5% relaxation treatment was carried out in the vertical and horizontal directions, respectively. The produced film roll was slightly subjected to orientation strain due to bowing at the end position, and therefore, a portion in which the main orientation direction is 90 degrees ± 6 degrees or less with respect to the longitudinal direction of the film roll was cut out and used.

An alignment film C:

a film of 80 μm thick of COSMOSHINE (registered trademark) super birefringent type (SRF) manufactured by Toyobo Co., ltd was used. It is noted that the main orientation direction is substantially stable in the width direction of the film roll, and therefore, it was confirmed that the main orientation direction is 90 degrees ± 6 degrees or less with respect to the longitudinal direction of the film roll by arbitrary selection.

[ Table 1]

	Alignment film A	Alignment film B	Alignment film C
				Breaking Strength (MPa) in the principal orientation Direction	250	300	330
Breaking Strength (MPa) in the direction orthogonal to the principal orientation direction	190	140	85
				Modulus of elasticity (GPa) in the main orientation direction	4.2	-	-
Elastic modulus (GPa) in the direction orthogonal to the main orientation direction	3.9	-	-
				Retardation in plane (nm)	2780	5300	8320
nx	1.687	1.689	1.691
				ΔNxy	0.037	0.071	0.104
Thickness (μm)	75	75	80
				Light transmittance (%)	92	90	91
Haze (%)	1.3	1.5	1.3

(production of an alignment film having a hard coat layer and an adhesive layer laminated thereon)

The easy-adhesion coating layer surfaces of the alignment films a, B, and C were coated with a UV-curable hard coating agent and dried, and then irradiated with ultraviolet light under a high-pressure mercury lamp to obtain alignment films a, B, and C having a hard coating layer on one surface. Further, with respect to a commercially available optical adhesive (non-substrate type), a light release sheet was peeled off and laminated on the surface of each alignment film opposite to the surface on which the hard coat layer was laminated, in a roll-to-roll manner. The measurement results of the three-dimensional center plane average surface roughness SRa on the hard coat layer side of each alignment film are shown in table 2.

[ Table 2]

	Alignment film A	Alignment film B	Alignment film C
				Three-dimensional center plane average surface roughness SRa (nm)	7	10	7

(Assembly of image display device with surface protective film)

Examples 1 to 15 and comparative examples 1 and 2

The alignment film having the hard coat layer and the adhesive layer laminated thereon was cut into a size of the entire screen of X20 Plus UD manufactured by VIVO corporation, an organic EL display device having an optical fingerprint authentication sensor incorporated in the display screen. The film was used as a surface protective film and adhered to the screen of the organic EL display device with an adhesive surface interposed therebetween. The surface protective film attached at the time of purchase was peeled off. The angles at the time of bonding and the evaluation results are shown in tables 3 to 5. The angle was confirmed and bonded to the cut alignment film in which each hard coat layer and adhesive layer were laminated.

Example 16

In a case where a transparent conductive film of a polyester film is used as a touch sensor, alignment films a and C in which a hard coat layer and an adhesive layer are laminated and bonded in the same manner as described above.

[ Table 3]

[ Table 4]

[ Table 5]

In tables 3 to 5, positive values indicate clockwise directions and negative values indicate counterclockwise directions when the main orientation axes are viewed from the visible side with respect to the transmission axis of the polarizing plate.

Claims

1. An image display device having a polarizing plate on a visible side of a fingerprint authentication sensor and an orientation film on a visible side of the fingerprint authentication sensor,

an angle formed by the main orientation direction of the orientation film and the extinction axis direction of the polarizer of the polarizing plate is 0 degree +/-6 degrees or less, or 90 degrees +/-6 degrees or less,

in the above description, "below" refers only to values after "±".

2. The image display device according to claim 1, wherein an in-plane retardation of the alignment film is 1000nm or more and 30000nm or less.

3. The image display device according to claim 1, wherein the alignment film has a thickness of 10 μm or more and 150 μm or less.

4. The image display device according to claim 1 or 2, wherein a surface roughness SRa of a surface of the visible side of the alignment film is 100nm or less.

5. The image display device according to claim 1, wherein the orientation film has a haze of 3% or less.

6. The image display device according to claim 1, wherein the alignment film is surface-processed by at least one selected from a hard coat layer, an antireflection coating layer, a low reflection coating layer, and an antistatic coating layer.

7. The image display device according to claim 1, wherein the alignment film is at least any one of a surface protective film, a transparent conductive film, and an anti-scattering film.

8. The image display device according to claim 1, wherein the alignment film is attached to the image display device with a substrate-free adhesive sheet.

9. The image display device according to any one of claims 1 to 8, wherein a difference Δ Nxy between a refractive index in a main alignment direction and a refractive index in a direction orthogonal thereto of the alignment film is 0.055 or more and 0.095 or less, and a refractive index in a slow axis is 1.68 or more.

10. The image display device according to any one of claims 1 to 8, wherein a difference Δ Nxy between a refractive index in a main alignment direction and a refractive index in a direction orthogonal thereto of the alignment film is 0.01 or more and less than 0.055.

11. The image display device according to any one of claims 1 to 8, wherein a difference Δ Nxy between a refractive index in a main alignment direction and a refractive index in a direction orthogonal thereto of the alignment film is 0.075 or more and 0.16 or less.

12. The image display device according to claim 11, wherein a difference Δ Nxy between a refractive index in a main alignment direction and a refractive index in a direction orthogonal thereto of the alignment film is 0.085 or more and 0.13 or less.

13. The image display device according to claim 1, wherein the alignment film is formed of

The difference Delta Nxy between the refractive index in the main orientation direction and the refractive index in the direction orthogonal thereto is 0.055 to 0.095,

the refractive index of the slow axis is 1.68 or more,

an in-plane retardation of 3000nm to 30000nm,

a thickness of 20 to 150 μm,

the surface roughness SRa of the visible side surface is 30nm or less,

the haze is 2% or less.

14. The image display device according to claim 1, wherein the alignment film is formed of

The difference Deltanxy between the refractive index in the main orientation direction and the refractive index in the direction perpendicular thereto is 0.01 or more and less than 0.055,

a thickness of 20 to 150 μm,

the surface roughness SRa of the surface on the visible side is 30nm or less,

the haze is 2% or less.

15. The image display device according to claim 1, wherein the alignment film is formed of

The difference Deltanxy between the refractive index in the main orientation direction and the refractive index in the direction perpendicular thereto is 0.085 to 0.13,

an in-plane retardation of 6000nm to 30000nm,

a thickness of 20 to 150 μm,

the surface roughness SRa of the visible side surface is 30nm or less,

the haze is 2% or less.

16. The image display device of claim 1, comprising an organic EL unit.