KR20200127454A - Optical film for fingerprinting - Google Patents

Abstract

Disclosed is an optical film for fingerprint recognition which transmits infrared rays. The optical film for fingerprint recognition comprises: a first prism sheet in which a plurality of first prisms aligned in a first direction are disposed on one surface; a second prism sheet in which a plurality of second prisms aligned in a second direction are disposed on one surface and adhered to the first prism sheet; and a diffusion sheet disposed on the other surface of the second prism sheet and adhered to the second prism sheet. Here, the first prism sheet, the second prism sheet, and the diffusion sheet may have a plurality of through-holes formed in a traveling direction of infrared rays so as to transmit the infrared rays.

Description

Optical film for fingerprint recognition {OPTICAL FILM FOR FINGERPRINTING}

The present invention relates to an optical film for fingerprint recognition, and more particularly, to an optical film for fingerprint recognition capable of transmitting infrared rays.

Recently, portable electronic devices such as smartphones and tablet PCs have become common. These portable electronic devices contain personal information such as the user's address, email, and financial information, so it is important to secure security through user authentication.

User authentication technology is evolving as a method of using the user's biometric information. Here, the biometric information may be, for example, information such as a fingerprint, an iris, a face, or a voice. In particular, fingerprint authentication is being adopted in most portable electronic devices due to its convenience and high security.

Representative methods of recognizing fingerprints are electrostatic, ultrasonic, and optical. Recently, smartphones are equipped with a semiconductor sensor-based capacitive fingerprint recognition function that exhibits a high recognition rate while maintaining a small size and thin enough to not affect the design. In addition, an ultrasonic fingerprint recognition function that recognizes the difference in height of the fingerprint by measuring the arrival time of the reflected ultrasonic waves after radiating the ultrasonic waves is also installed in the smartphone. However, the capacitive fingerprint sensor has a very small size of a fingerprint area to be recognized at a time compared to the optical fingerprint sensor, and thus the false authentication rate is higher than that of the optical type, so security may be slightly degraded. The ultrasonic type is relatively good in accuracy and durability, but it is somewhat difficult to manufacture and has disadvantages in terms of price.

On the other hand, the optical fingerprint method guarantees high reliability and has excellent durability, so it is adopted in various electronic devices. The optical fingerprint recognition method is a so-called scattering method that detects light scattered from the ridge of the fingerprint that directly contacts the transparent fingerprint contact of the device, and the light that is totally reflected from the surface of the fingerprint contact corresponding to the valley of the fingerprint. It can be divided into a so-called total reflection method that detects.

The backlight unit of a small electronic device such as a smartphone is provided with various optical films, so it is difficult to transmit infrared rays. Accordingly, it is difficult to utilize an optical fingerprint recognition method using infrared rays.

The present invention has been conceived to solve the above-described problems, and an object thereof is to provide an optical film for fingerprint recognition that smoothly transmits infrared rays so that optical fingerprint authentication using infrared rays is possible even in small electronic devices such as a smart phone.

The optical film for fingerprint recognition that transmits infrared rays according to an embodiment of the present invention includes a first prism sheet in which a plurality of first prisms aligned in a first direction are disposed on one surface, and a first prism sheet is aligned in a second direction. A plurality of second prisms are disposed on one side, a second prism sheet adhered to the first prism sheet, and a diffusion sheet disposed on the other side of the second prism sheet, and adhered to the second prism sheet. I can. Here, the first prism sheet, the second prism sheet, and the diffusion sheet may have a plurality of through-holes formed in the traveling direction of the infrared rays so as to transmit the infrared rays.

According to various embodiments of the present disclosure, the optical film for fingerprint recognition may smoothly transmit infrared rays.

According to various embodiments of the present disclosure, the optical film for fingerprint recognition enables fingerprint recognition on a screen of a small electronic device such as a smartphone, thereby simplifying the structure of a smartphone and improving user convenience.

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.
2 shows an optical film according to an embodiment of the present invention.
3 shows an optical fingerprint recognition system according to another embodiment of the present invention.
4 shows a plurality of through holes according to an embodiment of the present invention.
5 shows a plurality of through holes according to another embodiment of the present invention.
6 shows a plurality of through holes according to another embodiment of the present invention.
7 shows an optical fingerprint recognition system according to another embodiment of the present invention.
8 shows an optical fingerprint recognition system according to another embodiment of the present invention.

Hereinafter, the operating principle of a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, when it is determined that a detailed description of a related known function or configuration may obscure the subject matter of the present disclosure in describing an exemplary embodiment of the present disclosure, a detailed description thereof will be omitted. In addition, terms used in the following are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of users or operators. Therefore, the definition of the terms used should be interpreted based on the contents throughout the specification and functions corresponding thereto.

1 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display device (or a liquid crystal display (LCD) device) 1 includes a backlight unit 10 and a liquid crystal panel 20. In general, the backlight unit 10 may be provided at the rear of the liquid crystal panel 20 to irradiate light to the liquid crystal panel 20. The backlight unit 10 includes a light source 11, a reflective plate 12, a light guide plate 13, a diffusion sheet 14, a prism sheet 15, 16, and a reflective polarization sheet 17.

The light source 11 emits light. By irradiating the light emitted from the light source 11 onto the rear surface of the liquid crystal panel 20, an identifiable image may be realized.

For example, the light source 11 may be one of a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp, and a light emitting diode (LED, hereinafter referred to as LED). have.

The light emitted from the light source 11 may be converted into a surface light source by the light guide plate 13. The light source 11 is divided into an edge type and a direct type according to the arrangement structure, and the direct type can realize a more detailed image than the edge type because it can be divided and driven compared to the edge type.

The reflector 12 is disposed behind the light guide plate 13 and reflects the light emitted from the rear of the light guide plate 13 to the light guide plate 13 and enters it, thereby minimizing loss of light.

The diffusion sheet 14 may uniformly disperse light incident from the light guide plate 13. Here, the diffusion sheet may include beads for light diffusion therein. For example, the diffusion sheet 14 contains at least one of a curable resin to which a light diffusing agent bead is added (for example, urethane acrylate, epoxy acrylate, ester acrylate, ester acrylate, and radical-generating monomer). (Selected individually or mixed) The solution can be applied to induce light diffusion by the optical diffuser beads. In addition, the diffusion sheet 14 may have a protrusion pattern (or protrusion) having a uniform or non-uniform size (for example, a spherical shape) to promote light diffusion.

The prism sheets 15 and 16 may condense incident light using an optical pattern formed on the surface and emit light to the liquid crystal panel 20. The prism sheets 15 and 16 may be formed as an optical pattern layer in which an optical pattern in the form of a triangular array having an inclined surface of 45° is formed on the translucent base film in order to improve luminance in the front direction.

The reflective polarization sheet 17 is provided on the prism sheets 15 and 16 and serves to recycle the light by transmitting one polarized light and reflecting the other polarized light to the lower side of the light collected from the prism sheets 15 and 16. .

The liquid crystal panel 20 refracts light irradiated from the light source 11 in a predetermined pattern according to an electric signal. The refracted light passes through a color filter and a polarization filter disposed on the front surface of the liquid crystal panel 20 to form a screen.

It goes without saying that the configuration included in the above-described backlight unit 10 may be in various combinations. For example, in the backlight unit 10, some of the light source 11, the reflective plate 12, the light guide plate 13, the diffusion sheet 14, the prism sheets 15 and 16, and the reflective polarization sheet 17 are omitted, or An additional configuration may be further included.

Hereinafter, the optical film is defined as including a plurality of optical sheets, but is not limited thereto. For example, the optical film and the optical sheet may be defined as the same meaning, or the optical sheet may be defined as including a plurality of optical films.

2 shows an optical film according to an embodiment of the present invention.

The optical film 200 may include a first prism sheet 210, a second prism sheet 220, and a diffusion sheet 230.

The first prism sheet 210 and the second prism sheet 220 collect light transmitted through the diffusion sheet 220.

A plurality of first prisms aligned in a first direction may be disposed on one surface of the first prism sheet 210.

를 형성할 수 있다.A plurality of second prisms aligned in the second direction may be disposed on one surface of the second prism sheet 220. Here, the first direction and the second direction are 90

Can be formed.

For example, at least one of the other surface of the first prism sheet 210, the one surface of the second prism sheet, and the other surface of the second prism sheet may further include an adhesive layer. For example, the other surface of the first prism sheet 210 and one surface of the second prism sheet 220 may be adhered by an adhesive layer. In addition, the other surface of the second prism sheet 220 and one surface of the diffusion sheet 230 may be adhered by an adhesive layer.

Here, the adhesive layer may be formed of a pressure sensitive adhesive (PSA). Accordingly, the optical film 200 may be integrated by bonding the first prism sheet 210, the second prism sheet 220, and the diffusion sheet 230 to each other. In this case, the adhesive layer may be formed in an uneven surface.

The diffusion sheet 230 may diffuse light emitted from the light source 11. The diffusion sheet 230 may be disposed on the other surface of the second prism sheet 220.

In the above-described optical film 200, a through hole that transmits infrared rays may be disposed. Hereinafter, it will be described in detail with reference to FIG. 3. Hereinafter, contents overlapping with the configuration of the optical film 200 described above will be omitted for convenience of description.

3 shows an optical fingerprint recognition system according to another embodiment of the present invention.

3, the optical fingerprint recognition system 30 includes an infrared (IR) light source 300-1, an image sensor 300-2, a reflective device 300-3, and an optical film 300-4. It may include.

The infrared light source 300-1 is formed of an LED and can emit infrared light. For example, the infrared light source 300-1 may irradiate infrared rays having a wavelength of 740 nm or more. Here, since infrared rays have a relatively long wavelength, light loss is small and diffuse reflection is small, so that a clear image can be obtained from the image sensor 300-2.

The image sensor 300-2 senses a fingerprint image. The image sensor 300-2 converts infrared rays reflected from the fingerprint into electrical signals and stores them. For example, the image sensor 300-2 may be a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS).

The reflector 300-3 may refract infrared rays. As an example, the reflecting device 300-3 may refract infrared rays emitted from the infrared light source 300-1 or may refract infrared rays reflected from a fingerprint. As an example, the reflecting device 300-3 may include various applications for refracting the direction of light, such as at least one prism and a beam splitter.

Here, the reflecting device 300-3 may be formed under the reflecting plate 12 described in FIG. 1. In addition, it may be formed of a material that transmits visible light and formed on the reflector 12.

The optical film 300-4 may include a first prism sheet 310, a second prism sheet 320, and a diffusion sheet 330.

The first prism sheet 310, the second prism sheet 320, and the diffusion sheet 330 may include a plurality of through holes 301. Here, the plurality of through-holes 301 may be formed in a traveling direction (A or B) of infrared rays so as to transmit infrared rays. In this case, the plurality of through-holes 301 may be formed to connect the infrared light paths inside the first prism sheet 310, inside the second prism sheet 320, and inside the diffusion sheet 330. Accordingly, infrared rays may be transmitted (or passed through) without being reflected to any one of the first prism sheet 310, the second prism sheet 320, and the diffusion sheet 330.

For example, among the plurality of through-holes 301, the first plurality of through-holes are formed in a third direction A, which is a traveling direction of infrared rays emitted from the infrared light source 300-1, and the plurality of through-holes 301 The second plurality of through-holes may be formed in a fourth direction B, which is a direction in which infrared rays emitted from the infrared light source 300-1 are reflected and refracted. Here, the plurality of through holes 301 may be formed to be inclined at a predefined angle according to the traveling direction of infrared rays.

In FIG. 3, the plurality of through holes 301 are illustrated as being formed in the first prism sheet 310, the second prism sheet 320, and the diffusion sheet 330 in a vertical direction, but are not limited thereto. The direction in which the plurality of through holes 301 are formed may be changed according to the traveling direction of infrared rays reflected by the fingerprint. For example, the traveling direction (A or B) of infrared rays before and after reflection is a normal line of one surface of the first prism sheet 310, one surface of the second prism sheet 320, and one surface of the diffusion sheet 330 When it is set to be inclined by a predetermined angle based on the direction in which the plurality of through holes 301 are formed, one side of the first prism sheet 310, one side of the second prism sheet 320, and the diffusion sheet 330 It may be formed to be inclined by the predetermined angle based on the normal of one side of the.

According to the exemplary embodiment of the present invention described above, infrared rays emitted from the infrared light source 300-1 and infrared rays reflected by the fingerprint may pass through the optical film 300-4 through the plurality of through holes 301. . Accordingly, an optical fingerprint recognition system 30 using infrared rays can be implemented. In addition, since the above-described optical fingerprint recognition system 30 uses infrared rays, fingerprint recognition is possible even in the display area of miniaturized electronic devices (eg, smartphones, tablet PCs, etc.), thereby simplifying the structure of electronic devices, User convenience can be improved.

Hereinafter, with reference to FIGS. 4 to 6, the above-described plurality of through-holes formed on the optical film will be described.

4 shows a plurality of through holes according to an embodiment of the present invention.

Referring to FIG. 4, regions 420 and 420 ′ in which a plurality of through holes are formed may be disposed on a display 410 of a smartphone. Here, the region 420 ′ in which the plurality of through holes are formed is an enlarged view of the region 420 in which the plurality of through holes are formed.

In the regions 420 and 420 ′ in which a plurality of through holes are formed, a plurality of through holes may be disposed at predetermined intervals. The regions 420 and 420' in which the plurality of through holes are formed may be set to a size of a predefined diameter (Τ). For example, the diameter (Τ) of the regions 420 and 420 ′ in which a plurality of through holes are formed may be set to 10 mm. Here, the farthest distance between at least two of the plurality of through holes may be set as a predefined distance. For example, the farthest distance between at least two of the plurality of through holes may be 10 mm.

As an example, referring to FIG. 5, a diameter of each of the plurality of through-holes may be 1 μm to 30 μm, and an interval of each of the plurality of through-holes may be randomly set to 1.5 μm to 60 μm. As another example, referring to FIG. 6, the diameters of each of the plurality of through-holes are the same as above, and the spacing of each of the plurality of through-holes may be set equally to one of 1.5 μm to 60 μm.

That is, the plurality of through-holes may be arranged in a random or grid form, and specifically, the spacing of the through-holes should be at least 1.5 times the diameter of the through-holes, and preferably 1.5 to 2 times.

When the distance between the through-holes is less than 1.5 times the diameter of the through-hole, the image sensor recognizes infrared rays reflected through adjacent through-holes as infrared rays reflected from one through-hole. If it exceeds twice the diameter of the through hole, the fingerprint recognition rate may be reduced, resulting in a problem that the fingerprint cannot be accurately recognized.

Hereinafter, other embodiments of the optical films 200 and 300-4 will be described in detail with reference to FIGS. 7 to 8. Hereinafter, contents overlapping with the configurations of the optical films 200 and 300-4 described above will be omitted for convenience of description.

7 shows an optical fingerprint recognition system according to another embodiment of the present invention.

Referring to FIG. 7, the optical fingerprint recognition system 70 may include an infrared light source 700-1, an image sensor 700-2, a reflector 700-3, and an optical film 700-4. .

The optical film 700-4 may include a first prism sheet 710, a second prism sheet 720, and a diffusion sheet 730. Here, upper ends of the plurality of first prisms 711 and upper ends of the plurality of second prisms 721 may be formed in a plane. For example, the upper ends of the plurality of first prisms 711 may be formed to be parallel to one surface of the first prism sheet 710. In addition, the upper end of the plurality of second prisms 721 may be formed to be parallel to one surface of the second prism sheet 720.

In the above-described optical film 700-4, since the upper ends of the plurality of first prisms 710 and the upper ends of the plurality of second prisms 720 are formed in a plane, the refractive index of infrared rays is minimized, so that the transmittance of infrared rays is improved. I can.

8 shows an optical fingerprint recognition system according to another embodiment of the present invention.

Referring to FIG. 8, the optical fingerprint recognition system 80 may include an infrared light source 800-1, an image sensor 800-2, a reflector 800-3, and a prism sheet 800-4. .

The prism sheet 800-4 may include a base film 811 and a plurality of prisms 812.

For example, the prism sheet 800-4 may include a plurality of through holes 801. Here, the plurality of through-holes 801 may be formed in a traveling direction (C or D) of infrared rays so as to transmit infrared rays. Accordingly, infrared rays may simultaneously transmit (or pass) the base film 811 and the plurality of prisms 812. Here, the plurality of through holes 801 may be disposed at predefined intervals. For example, the diameter of the plurality of through-holes 801 is formed to be 10 μm, and the distance between the plurality of through-holes 801 is uniformly arranged at 15 μm.

For example, as shown in FIG. 7, the apex ends of the plurality of prisms 812 may be formed in a plane. For example, the end portions of the plurality of prisms 812 may be formed to be parallel to one surface of the prism sheet 800-4. In this case, since the end portions of the plurality of prisms 812 are formed in a plane shape, the refractive index of infrared rays is minimized, so that the transmittance of infrared rays may be improved.

As described above, embodiments of the present invention have been shown and described, but those skilled in the art will make various changes in form and detail without departing from the spirit and scope of the present embodiment as defined by the appended claims and equivalents thereto. You will understand that you can.

Liquid crystal display: 1 Backlight unit: 10
Light source: 11 Reflector: 12
Light guide plate: 13 Diffusion sheet: 14, 230, 330
Reflective polarization sheet: 17 Liquid crystal panel: 20 Optical film: 200, 300-4, 700-4 Optical fingerprint recognition system: 30, 70, 80
Prism sheet: 15, 16, 210, 220, 310, 320, 710, 720, 800-4

Claims (13)

In the optical film for fingerprint recognition that transmits infrared (infrared),
A first prism sheet in which a plurality of first prisms aligned in a first direction are disposed on one surface;
A second prism sheet having a plurality of second prisms aligned in a second direction disposed on one surface and adhered to the first prism sheet; And
Including; a diffusion sheet disposed on the other side of the second prism sheet and bonded to the second prism sheet,
The first prism sheet, the second prism sheet, and the diffusion sheet,
An optical film for fingerprint recognition, in which a plurality of through-holes formed in the traveling direction of the infrared rays are disposed to transmit the infrared rays.
The method of claim 1,
The plurality of through holes,
An optical film for fingerprint recognition formed by being connected to the inside of the first prism sheet, inside the second prism sheet, and inside the diffusion sheet.
The method of claim 1,
The first plurality of through-holes among the plurality of through-holes are formed in a third direction, which is a traveling direction of infrared rays emitted from the light source,
The second plurality of through-holes among the plurality of through-holes are formed in a fourth direction, which is a direction in which the infrared rays emitted from the light source are reflected and refracted.
The method of claim 1,
Each of the plurality of through holes,
An optical film for fingerprint recognition, arranged at predefined intervals.
The method of claim 4,
The spacing of each of the plurality of through holes,
Formed to be 1.5 to 2 times the diameter of the plurality of through-holes, fingerprint recognition optical diffusion film.
The method of claim 1,
The farthest distance between the two of the plurality of through holes is set to a predefined distance, the optical film for fingerprint recognition.
The method of claim 1,
At least one of the other surface of the first prism sheet and the other surface of the second prism sheet further comprises an adhesive layer, an optical film for fingerprint recognition.
The method of claim 6,
The adhesive layer is an optical film for fingerprint recognition that is formed in a non-uniform uneven shape.
The method of claim 1,
The diffusing sheet includes beads for light diffusion therein.
The method of claim 1,
The plurality of through-holes are formed to be inclined at a predefined angle, the optical film for fingerprint recognition.
The method of claim 1,
Upper ends of the plurality of first prisms and upper ends of the plurality of second prisms,
An optical film for fingerprint recognition, formed in a flat surface.
The method of claim 11,
The upper end portion of the plurality of first prisms is formed to be parallel to the one surface of the first prism sheet,
The upper end portion of the plurality of second prisms is formed to be parallel to the one surface of the second prism sheet, a fingerprint recognition optical film.
The method of claim 1,
Each of the plurality of first prisms and each of the plurality of second prisms are arranged in parallel at a predefined interval. An optical film for fingerprint recognition.

Images