阅读说明：本技术 用于包括指纹认证装置的有机发光二极管显示器的保护膜 (Protective film for organic light emitting diode display including fingerprint authentication device ) 是由 古田旭 寺本晃史 于 2020-04-10 设计创作，主要内容包括：本发明公开了一种用于包括指纹认证装置(30)的有机发光二极管显示器(10)的保护膜(16)。保护膜(16)将覆盖部件(15)的表面覆盖起来。保护膜(16)具有平面内补偿值在25nm以下的基材层。因此,能够抑制误认证,生产效率高。(A protective film (16) for an organic light emitting diode display (10) including a fingerprint authentication device (30) is disclosed. The protective film (16) covers the surface of the covering member (15). The protective film (16) has a base material layer having an in-plane offset value of 25nm or less. Therefore, erroneous authentication can be suppressed, and the production efficiency is high.)

1. A protective film for an organic light-emitting diode display including a fingerprint authentication device, in the organic light-emitting diode display including a fingerprint authentication device, a surface of a covering member being covered by the protective film, characterized in that:

the protective film has a base material layer having an in-plane offset value of 25nm or less.

2. The protective film for an organic light-emitting diode display including a fingerprint authentication device according to claim 1, characterized in that:

the fingerprint authentication device includes a light source that irradiates light to an authentication object, an image sensor that receives reflected light from the authentication object;

the organic light emitting diode display also comprises an organic light emitting diode panel and a circular polarizer arranged on the upper side of the organic light emitting diode panel;

the covering member is disposed on an upper side of the circular polarizer;

the fingerprint authentication device is disposed at a lower side of the organic light emitting diode panel.

3. The protective film for an organic light-emitting diode display including a fingerprint authentication device according to claim 1 or 2, characterized in that:

an adhesive layer is provided on the surface of the base material layer on the covering member side.

4. The protective film for an organic light-emitting diode display including a fingerprint authentication device according to claim 1 or 2, characterized in that:

a hard coat layer is provided on the surface of the base material layer opposite to the covering member.

5. The protective film for an organic light-emitting diode display including a fingerprint authentication device according to claim 1 or 2, characterized in that:

the substrate layer mainly comprises polycarbonate resin, acrylic resin, cycloolefin resin or polyester resin.

Technical Field

The present invention relates to a protective film for an organic light emitting diode display including a fingerprint authentication device.

Background

In recent years, among various information devices such as smartphones and tablet computers, there are increasing models that perform locking and unlocking by performing fingerprint authentication on an Organic Light Emitting Diode (OLED) display (see, for example, patent document 1).

In an optical fingerprint authentication device that performs authentication optically by using a fingerprint, an LED is used as a light source to irradiate an authentication target with light, and reflected light from a fingerprint surface is read by an image sensor.

In an organic light emitting diode display including such an optical fingerprint authentication device, a cover glass is laminated on an organic light emitting diode panel via a circular polarizer that prevents reflection of external light.

When a user drops the organic light emitting diode display (or an information device with the organic light emitting diode display mounted thereon, hereinafter, referred to as a device) on the ground, or the user strongly presses the cover glass, the cover glass may be broken, and the dropped broken glass pieces may cause the device and the organic light emitting diode display to be broken.

Therefore, in order to prevent the cover glass from being damaged and the cullet pieces from falling down around when damaged, the surface of the cover glass is covered with a protective film such as a PET film.

Patent document 1: japanese laid-open patent publication No. 2018-88248

Disclosure of Invention

However, since the conventional PET film used as a protective film of a fingerprint authentication device is uniaxially stretched, the in-plane compensation value (Re) is high, and a retardation occurs due to birefringence. In the optical fingerprint authentication device using the characteristic that the reflection amount of light by a fingerprint is different, the amount of light received by the image sensor changes due to the positional relationship between the protective film and the circular polarizer, and as a result, erroneous authentication occurs.

In order to prevent such false authentication, when the base material to be the protective film is punched and the size of the punched base material is as large as the equipment used, the orientation axis of the film must be aligned with the optical axis of the circular polarizer by determining the angle, and as a result, about 30 to 40% of the base material is wasted. The alignment axis of the film and the optical axis of the circular polarizer may be shifted due to tolerances in the punching process and tolerances in the alignment axis of the film, and defective products having such shifts may be produced, resulting in a reduction in yield.

Accordingly, the object of the present invention is to: provided is a protective film for an organic light emitting diode display including a fingerprint authentication device, with which erroneous authentication can be suppressed and which is excellent in production efficiency.

In order to achieve the above object, a protective film for an organic light emitting diode display including a fingerprint authentication device according to the present invention covers a surface of a covering member in the organic light emitting diode display including the fingerprint authentication device, and the protective film has a base material layer having an in-plane offset value of 25nm or less.

According to the protective film for an organic light emitting diode display including a fingerprint authentication device according to the present invention, the in-plane compensation value of the base material layer is extremely small, and is 25nm or less, and therefore, a phase difference due to birefringence is less likely to occur. Therefore, even if the protective film is used as a protective film of a fingerprint authentication device, the amount of light received by the image sensor is not easily changed, and as a result, the occurrence of erroneous authentication can be suppressed. The in-plane compensation value is low, and therefore the influence of the orientation of the base material layer is small. Therefore, when the base material to be the base material layer is punched out and the size of the punched base material is as large as the size of the equipment used, the orientation axis of the film and the optical axis of the circular polarizer are aligned without determining the angle, and therefore, the problem that the base material is wasted is difficult to occur. Defective products due to the tolerance of the orientation axis of the film are less likely to occur, and as a result, a decrease in yield can be suppressed.

The protective film for an organic light emitting diode display including a fingerprint authentication device according to the present invention may be such that: the fingerprint authentication device includes: a light source for irradiating light to an authentication object, and an image sensor for receiving reflected light from the authentication object; the organic light emitting diode display further includes: an organic light emitting diode panel, a circular polarizer disposed on an upper side of the organic light emitting diode panel; the covering member is arranged on the upper side of the circular polarizer; the fingerprint authentication device is disposed at a lower side of the organic light emitting diode panel.

Thus, an organic light emitting diode display including the fingerprint authentication device can be easily manufactured. In the organic light emitting diode display including the fingerprint authentication device using the protective film according to the present invention, the visible side thereof is referred to as an upper side, and the opposite side to the visible side thereof is referred to as a lower side.

The protective film for an organic light emitting diode display including a fingerprint authentication device according to the present invention may be such that: an adhesive layer is provided on the surface of the base material layer on the side of the covering member.

Thus, the protective film can be easily attached to the cover member.

The protective film for an organic light emitting diode display including a fingerprint authentication device according to the present invention may be such that: a hard coat layer is provided on the surface of the base material layer opposite to the covering member.

This improves the strength of the protective film.

The protective film for an organic light emitting diode display including a fingerprint authentication device according to the present invention may be such that: the base material layer contains a polycarbonate resin, an acrylic resin, a cycloolefin resin, or a polyester resin as a main component. The "main component" is the largest component by mass (for example, 50 mass% or more).

Thus, a protective film having a low in-plane offset value can be manufactured by a known method such as a T-Die method.

In the case where a protective film is formed by laminating a hard coat layer, an adhesive layer, or the like on a base material layer, heat or tension (tensile force) is applied to the base material layer in the laminating step, and thus the in-plane compensation value of the base material layer changes. However, needless to say, the "in-plane compensation value of the base material layer" described in the present invention means "in-plane compensation value of the base material layer" after the protective film is formed through the above-described laminating step.

Since the hard coat layer and the adhesive layer are amorphous and have no orientation, the in-plane compensation value is not substantially changed by the hard coat layer or the adhesive layer. In other words, the "in-plane compensation value of the entire protective film" in the case where the protective film is formed by laminating a hard coat layer, an adhesive layer, or the like on a base material layer is substantially equal to the "in-plane compensation value of the base material layer".

In the case where a plurality of base material layers are stacked to form the protective film, the "in-plane compensation value of the base material layer" described in the present invention means "the sum of in-plane compensation values of all the base material layers forming the protective film". For example, in the case where the protective film is formed by stacking the hard coat layer, the first base material layer, the adhesive layer, and the second base material layer in this order from top to bottom, the "in-plane compensation value of the base material layer" is the sum of the "in-plane compensation value of the first base material layer" and the "in-plane compensation value of the second base material layer".

Effects of the invention

According to the present invention, it is possible to provide a protective film for an organic light emitting diode display including a fingerprint authentication device, which can suppress erroneous authentication and has good production efficiency.

Drawings

FIG. 1 is a schematic diagram showing an example of an organic light emitting diode display including a fingerprint authentication device using a protective film according to an embodiment;

fig. 2 is a diagram illustrating a fingerprint authentication principle of the fingerprint authentication device shown in fig. 1;

fig. 3 is a schematic view illustrating an organic light emitting diode panel and a circular polarizer in the organic light emitting diode display shown in fig. 1;

fig. 4 is a diagram illustrating an effect of the protective film according to the embodiment;

FIG. 5 is a schematic view of an apparatus for measuring in-plane compensation values;

fig. 6 is a diagram showing a relationship between an in-plane compensation value and a fingerprint authentication success rate of the protective film according to the embodiment.

Description of the symbols

10-organic light emitting diode display; 11-organic light emitting diode panel; 11A-a cathode; 11B-an anode; 12-a light source; 13-an image sensor; 14-a circular polarizer; 14A-1/4 wave plate; 14B-a linear polarizer; 15-a covering member; 16-a protective film; 17-irradiating light; 18-reflected light; 20-finger; 21-external light; 22-linearly polarized light; 23-circularly polarized light; 24-circularly polarized light; 25-linearly polarized light; 30-fingerprint authentication means.

Detailed Description

Next, a protective film for an organic light emitting diode display including a fingerprint authentication device according to an embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention.

Fig. 1 is a schematic diagram showing an example of an organic light emitting diode display including a fingerprint authentication device using the protective film according to the embodiment. Fig. 2 is a diagram illustrating a principle of fingerprint authentication of the fingerprint authentication device shown in fig. 1. Fig. 3 is a schematic view illustrating an organic light emitting diode panel and a circular polarizer in the organic light emitting diode display shown in fig. 1.

As shown in fig. 1, the organic light emitting diode display 10 includes: an organic light emitting diode panel 11 constituting a display screen, a fingerprint authentication device 30 provided below the organic light emitting diode panel 11, a circular polarizing plate 14 laminated on the organic light emitting diode panel 11, a cover member 15 laminated on the circular polarizing plate 14, and a protective film 16 covering the surface of the cover member 15. The fingerprint authentication device 30 has a light source 12 and an image sensor 13. The light source 12 irradiates light to the authentication object. The image sensor 13 receives reflected light from the authentication object. The circular polarizer 14 prevents external light from being reflected into the organic light emitting diode display 10. In the organic light emitting diode display 10, the visible side is referred to as an upper side, and the opposite side to the visible side is referred to as a lower side.

As shown in fig. 1 and 2, when a human finger 20 touches the surface (authentication surface 10a) of the protective film 16, the irradiation light 17 from the light source 12 in the fingerprint authentication device 30 is reflected by the authentication surface 10a with which the finger 20 touches, and the reflected light 18 is received by the image sensor 13 in the fingerprint authentication device 30. At this time, total reflection occurs in the fingerprint concave portion of the finger 20, and the amount of the reflected light 18 is substantially equal to the amount of the irradiation light 17. However, diffuse reflection occurs at the fingerprint convex portion of the finger 20, and the amount of reflected light 18 is smaller than the amount of irradiated light 17. So that a shadow 19 corresponding to the shape of the fingerprint of the finger 20 is generated in the reflected light 18 received by the image sensor 13. The fingerprint authentication device 30 records the shadow 19 by a processing circuit, not shown, and performs fingerprint authentication by comparing the shadow 19 with fingerprint information registered in advance.

The organic light emitting diode display 10 shown in fig. 1 can be mounted in various information devices such as a smart phone, a tablet computer, and the like, which can perform, for example, locking or unlocking by performing fingerprint authentication on a display screen.

In the present embodiment, the structure of the organic light emitting diode panel 11 is not particularly limited. For example, as shown in fig. 3, the organic light emitting diode panel 11 may include a cathode 11A provided on the reverse (back) side of the authentication surface 10a and an anode 11B provided to face the cathode 11A. The cathode 11A is formed of, for example, a metal layer having a mirror surface, and the anode 11B is formed of, for example, an ITO (indium tin oxide) layer. Light emitting layers and/or hole and electron transport layers corresponding to the respective colors are provided between the cathode 11A and the anode 11B, but are not shown. A transparent member such as a glass substrate may be located between the anode 11B and the circular polarizer 14. The cathode 11A may not be formed at the installation position of the light source 12 and the image sensor 13, that is, the installation position of the fingerprint authentication device 30.

For example, as shown in fig. 3, the circular polarizer 14 may include 1/4 wave plate 14A disposed on the organic light emitting diode panel 11 side and a linear polarizer 14B laminated on 1/4 wave plate 14A; transparent members may be located between 1/4 wave plate 14A and linear polarizer 14B.

In the organic light emitting diode panel 11, a metal layer having a mirror surface is provided as a cathode 11A serving as a back electrode. Therefore, when the organic light emitting diode display 10 is used in a mobile communication device or the like, which is frequently used under external light, the circular polarizer 14 is provided to prevent the external light from being reflected on the organic light emitting diode display 10. As shown in fig. 3, the influence of the external light 21 can be reduced by using the circular polarizer 14. As a result, the visibility of the organic light emitting diode display 10 is improved.

Specifically, the external light 21 passes through the linear polarizer 14B and becomes linearly polarized light 22, the linearly polarized light 22 passes through the 1/4 wave plate 14A and becomes circularly polarized light 23, and the circularly polarized light 23 passes through the anode 11B and is reflected by the cathode 11A. At this time, the reflected light becomes circularly polarized light 24 having a polarization direction opposite to that of circularly polarized light 23. If circularly polarized light 24 transmits anode 11B and then passes through 1/4 wave plate 14A, circularly polarized light 24 becomes linearly polarized light 25 having a polarization direction 90 ° different from linearly polarized light 22, and thus linearly polarized light 25 does not transmit linear polarizer 14B.

For example, an LED or the like may be used as the light source 12. Meanwhile, the image sensor 13 may be a CCD type image sensor or a CMOS type image sensor or the like. The covering member 15 is not particularly limited as long as it is formed of a material having light transmittance. For example, the covering member may be formed of glass, plastic, or the like.

In the present embodiment, a thin film having an in-plane offset value of 25nm or less is used as the base material layer of the protective film 16. The in-plane compensation value (Re) is a value obtained by Re ═ Ny-Nx × d. Here, Nx is a refractive index of a fast axis (an axis parallel to the plane direction) of the thin film, Ny is a refractive index of a slow axis (an axis parallel to the plane direction and perpendicular to the fast axis) of the thin film, and d is a thickness of the thin film.

The base layer of the protective film 16 may be formed of a material mainly composed of a polycarbonate resin, an acrylic resin, a cycloolefin resin, or a polyester resin, for example. Thus, a thin film having an in-plane offset value of 25nm or less can be manufactured by a known method such as a T-mode method.

The base material layer of the protective film 16 may contain other components than the main components such as an ultraviolet absorber, a stabilizer, an antibacterial agent, and an antifungal agent.

The protective film 16 may have an adhesive layer on the surface of the base material layer (the surface of the base material layer on the side of the cover member 15). This makes it easy to mount the protective film 16 on the cover member 15. The adhesive layer can be formed of a known adhesive resin such as an acrylic resin or a urethane resin.

The protective film 16 may have a hard coat layer covering the surface of the base material layer (the surface of the base material layer opposite to the covering member 15). This improves the strength of the protective film 16. Preferably, the hard coat layer has properties such as transparency, scratch resistance, chemical resistance, heat resistance, impact resistance, stain resistance, and fingerprint adhesion resistance, and may be formed of, for example, a thermosetting resin or an active energy ray-curable resin.

When forming the adhesive layer or the hard coat layer on the protective film 16, it is necessary to pay special attention to the thickness, material, manufacturing method, and the like of the adhesive layer or the hard coat layer in order not to increase the in-plane compensation value of the entire protective film 16.

According to the present embodiment described above, the in-plane compensation value of the base material layer of the protective film 16 is very small, and is 25nm or less, and therefore, a retardation due to birefringence is less likely to occur. Therefore, even if the protective film 16 of the organic light-emitting diode display 10 is used, the amount of light received by the image sensor 13 is not easily changed, and therefore, the occurrence of the false authentication can be suppressed.

Further, according to the present embodiment, since the in-plane offset value is low, the influence of the orientation of the base material layer of the protective film 16 is small. Therefore, when the base material to be the base material layer is punched out and the size of the punched base material is as large as the equipment used, the orientation axis of the film and the optical axis of the circular polarizer 14 are aligned without determining the angle, and therefore, the problem of wasting the base material is difficult to occur. Defective products due to the tolerance of the film orientation axis are less likely to occur, and as a result, a decrease in yield can be suppressed.

According to the present embodiment, the organic light emitting diode display 10 includes the above protective film 16, and thus the fingerprint authentication accuracy of the fingerprint authentication device 30 is improved. The organic light emitting diode display 10 including the fingerprint authentication device 30 using the protective film 16 is mounted on various information devices such as a smart phone and a tablet computer, and fingerprint authentication can be performed with high accuracy in the information devices.

Fig. 4 is a diagram illustrating the effect of the protective film 16 of the present embodiment. As shown in fig. 4, the irradiation light 17 irradiated from the light source 12 passes through the 1/4 wave plate 14A as random light, passes through the linear polarizer 14B, and then becomes linearly polarized light. The linearly polarized light is transmitted through the covering member 15 and is reflected on the surface of the protective film 16 which the finger 20 contacts. The reflected light 18 is transmitted as linearly polarized light through the cover member 15 and the linear polarizer 14B, and after being transmitted through the 1/4 wave plate 14A, it becomes circularly polarized light and is received by the image sensor 13.

As described with reference to fig. 2, it is preferable that the amount of reflected light 18 changes only in accordance with the irregularities of the fingerprint of the finger 20 when the fingerprint authentication is performed. However, in practice, the amount of the reflected light 18 is affected by the polarization state of the protective film 16, i.e., the phase difference, due to the presence of the protective film 16. Here, the phase difference () is represented by 2 pi · Re/λ (Re is an in-plane compensation value, λ is a wavelength of light).

Therefore, as in the protective film 16 of the present embodiment, the smaller the in-plane compensation value, the smaller the phase difference, and the amount of the reflected light 18 substantially changes only in accordance with the unevenness of the fingerprint. As a result, the accurate fingerprint shape can be obtained by measuring the reflected light 18 with the image sensor 13, and thus the fingerprint authentication accuracy is improved.

On the other hand, in the case where a conventional protective film having a large in-plane compensation value is used as the protective film 16, as shown in fig. 4, the reflected light 18' formed after the reflection of the protective film 16 generates linearly polarized light having an angle different from that of the irradiation light 17 due to the phase difference of the protective film 16. Therefore, when the reflected light 18 'transmits through the linear polarizer 14B, the amount of the reflected light 18' is reduced. That is, the amount of the reflected light 18' varies due to the phase difference of the protective film 16, so that an accurate fingerprint shape cannot be obtained, and a false authentication may occur.

In the case of using a conventional protective film having a large in-plane compensation value, if the amount of the reflected light is reduced during fingerprint registration, the light and shade of the reflected light corresponding to the shape of the fingerprint is blurred, and accurate fingerprint authentication cannot be performed thereafter.

(examples and comparative examples)

The following describes examples and comparative examples with reference to the drawings.

When the in-plane offset value (Re) of the protective film (base material layer portion) in each of examples and comparative examples was measured, an Otsuka electronic tongue was usedRE-200 from GmbH. In this Re measurement, the measurement point was 38.5mm²The measurement wavelength is 550nm, and the light source is an LED. In the present Re measurement, when a photonic crystal element (polarizing element) is arranged, it is ensured that the angle of the photonic crystal element can be changed, and therefore, an in-plane compensation value can be measured without rotating the measurement sample.

Fig. 5 is a schematic view of the structure of the measuring apparatus used in the present Re measurement. As shown in fig. 5, the measuring apparatus 50 includes a light-emitting head 51, a sample holder 52 on which a measurement sample 60 is placed, and a light-receiving head 53 which faces the light-emitting head 51 with the sample holder 52 therebetween. The light projecting head 51 is provided with a light projecting fiber 54, a lens barrel 55, an interference filter (wavelength 550nm)56, a polarizer 57, and a wave plate 58 along the optical path. The light projecting fiber 54 introduces light from a light source (LED). The polarizer 57 and the wave plate 58 have manual attachment/detachment mechanisms, respectively. The light receiving head 53 is constituted by a CCD camera.

In this Re measurement, a measurement sample 60 cut to have a size of 38.5mm × 38.5mm was irradiated with light having a wavelength of 550nm from a light projecting head 51 by using a measurement apparatus 50 shown in fig. 5, a polarized light intensity image was sensed by a light receiving head 53, the phase difference and the orientation of the principal axis of the measurement sample 60 were measured, and an in-plane compensation value was obtained.

Comparative example 1

In comparative example 1, for R17 (smartphone) having a fingerprint authentication device manufactured by OPPO corporation, fingerprint authentication was performed 20 times for unlocking after the original protective film (SRF (registered trademark)) of the product was peeled off. The fingerprint authentication results are shown in table 1. The fingerprint registration is performed in a state where the protective film is peeled off.

Comparative example 2

In comparative example 2, fingerprint authentication for unlocking was performed 20 times using the original protective film (Re about 10000nm) of R17 produced by OPPO corporation as it is. The fingerprint authentication results are shown in table 1. The fingerprint registration is performed in a state where the protective film is peeled off.

Comparative example 3

In comparative example 3, the original protective film of the product was re-stuck after being turned 45 ° from the original orientation for R17 manufactured by OPPO corporation, and fingerprint authentication was performed 20 times for unlocking. The fingerprint authentication results are shown in table 1. The fingerprint registration is performed in a state where the protective film is peeled off.

(example 1)