KR102284460B1 - Optical film for fingerprinting recognition - Google Patents

Abstract

Disclosed is an optical film for fingerprint recognition that transmits infrared rays. The optical film for fingerprint recognition may include a base film and a prism pattern layer adhered to one side of the base film. Here, in the prism pattern layer, a plurality of prisms including an infrared absorber may be disposed parallel to each other at a predetermined interval to form a line pattern that transmits the infrared rays.

Description

Optical film for fingerprint recognition

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 a user's address, e-mail, and financial information, so it is important to secure security through user authentication.

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

A typical method for recognizing a fingerprint is an electrostatic type, an ultrasonic type, or an optical type. Recently, smart phones are equipped with a semiconductor sensor-based capacitive fingerprint recognition function that shows a high recognition rate while maintaining a thin and small size that does not affect the design. In addition, the ultrasonic fingerprint recognition function that recognizes the height difference of the fingerprint by measuring the arrival time of the reflected ultrasonic waves after emitting ultrasonic waves is also installed in smartphones. However, the capacitive fingerprint sensor has a very small size of the fingerprint area recognized at a time compared to the optical fingerprint sensor, and thus has a higher false authentication rate than the optical fingerprint sensor, which may lower security. Although the ultrasonic type has relatively good accuracy and durability, 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 being adopted in various electronic devices. The optical fingerprint recognition method includes a so-called scattering method for detecting light scattered from a ridge portion of a fingerprint that is in direct contact with a transparent fingerprint contact portion of a device, and a light totally reflected from a surface of the fingerprint contact portion corresponding to a valley portion of the fingerprint. It can be divided into the so-called total reflection method for detecting

A general optical film included in the backlight unit of a small electronic device such as a smartphone has a remarkably low infrared transmittance. Accordingly, the optical fingerprint recognition method using infrared rays is not easy to be adopted in a small electronic device having a general optical film.

The present invention has been devised to solve the above problems, and an object of the present invention 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 smart phones.

The optical film for fingerprint recognition that transmits infrared light according to an embodiment of the present invention may include a base film and a prism pattern layer adhered to one side of the base film. Here, in the prism pattern layer, a plurality of prisms including an infrared absorber may be disposed parallel to each other at a predetermined interval to form a line pattern that transmits the infrared rays.

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

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

1 is an exploded perspective view of a backlight unit according to an embodiment of the present invention.
2 is a cross-sectional view of an optical film according to an embodiment of the present invention.
3 illustrates diffuse reflection of infrared rays according to an embodiment of the present invention.
4 shows an infrared image according to an embodiment of the present invention.
5 illustrates diffuse reflection of infrared rays according to another embodiment of the present invention.
6 shows an infrared image according to another embodiment of the present invention.
7 illustrates infrared transmittance for a line pattern according to an embodiment of the present invention.
8 illustrates infrared absorption rates for a plurality of prisms according to an embodiment of the present invention.
9 shows an optical fingerprint recognition system according to an embodiment of the present invention.
10 shows an optical fingerprint recognition system according to another embodiment of the present invention.
11 shows an optical fingerprint recognition system according to another embodiment of the present invention.

Hereinafter, the principle of operation 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 well-known function or configuration may obscure the gist of the present disclosure in describing an embodiment of the present invention, the detailed description thereof will be omitted. And the terms used below are terms defined in consideration of functions in the present invention, which may vary depending on the intention or custom of the user or operator. Therefore, the definitions of the terms used should be interpreted based on the contents and corresponding functions throughout this specification.

The optical film according to various embodiments of the present invention described below may be applied to backlight units of various types of liquid crystal displays (LCDs). However, it goes without saying that the optical film according to various embodiments of the present invention may be used alone or included in a means for providing a backlight in various devices other than the liquid crystal display device.

1 is an exploded perspective view of a backlight unit according to an embodiment of the present invention.

In general, the liquid crystal display device requires a backlight unit 10 that provides uniform light to the entire screen, unlike the conventional cathode ray tube method (CRT). The backlight unit 10 may be provided at the rear of the liquid crystal panel to irradiate light to the liquid crystal panel.

The backlight unit 10 includes a light source 11 , a reflective plate 12 , a light guide plate 13 , an optical film 14 , and a reflective polarizing sheet 15 .

The light source 11 emits light. The light source 11 may be composed of a light emitting body that emits light. The light source 11 may emit light from the side of the light guide plate 13 to transmit light in the direction of the light guide plate 13 . By irradiating the light emitted from the light source 11 to the rear surface of the liquid crystal panel, 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). there is.

The light source 11 is divided into an edge type and a direct type according to the arrangement structure. The direct type can be divided and driven compared to the edge type, thereby realizing a more delicate image than the edge type.

The reflector 12 is disposed behind the light guide plate 13 to reflect the light emitted from the rear of the light guide plate 13 to the light guide plate 13 and thereby minimize light loss.

The light guide plate 13 converts the light incident through the reflection plate 12 into the form of a surface light source.

The optical film 14 is disposed on the light guide plate 13 , collects light transmitted from the light guide plate 13 and moves it upward. The optical film 14 has a plurality of inverted prisms arranged so that the transmitted light is totally reflected inside and refracted upward.

The optical film 14 may include a base film 14-1 and a prism pattern layer 14-2.

The base film 14-1 supports the prism pattern layer 14-2.

For example, the base film 14 - 1 may be a light-transmitting film through which light transmitted from the lower portion can be easily transmitted. In this case, the base film 14-1 may be made of, for example, PET, PC, or PP.

As another example, the base film 14 - 1 may be a reflective polarizing sheet 14 - 1 . In this case, the reflective polarizing sheet 14-1 transmits one polarized light with respect to the light collected from the plurality of prisms 14-2 and reflects the other polarized light downward to recycle the light. For example, the reflective polarizing sheet 14-1 may transmit P-polarized light and reflect S-polarized light.

Here, the reflective polarizing sheet 14-1 is configured by stacking a plurality of layers having different refractive indices. For example, the reflective polarizing sheet 14 - 1 may be configured by stacking tens, hundreds, or thousands of different high refractive index layers and low refractive index layers.

The base film 14-1 may be integrated with the prism pattern layer 14-2.

The prism pattern layer 14-2 condenses the incident light and emits it upward. In the prism pattern layer 14 - 2 , a plurality of prisms may be disposed at a predetermined interval.

For example, the prism pattern layer 14-2 is an optical pattern layer in which an optical pattern in the form of a triangular array having an inclined surface is formed under the translucent base film 14-1 to improve the luminance of the emitted light. can be formed.

Since the description of the reflective polarizing sheet 15 overlaps with the description of the aforementioned reflective polarizing sheet 14-1, a detailed description thereof will be omitted. For example, when the base film 14 - 1 is implemented as the reflective polarizing sheet 14 - 1 , the backlight unit 10 may or may not include the reflective polarizing sheet 15 .

Of course, the configurations included in the above-described backlight unit 10 may be in various combinations. For example, the backlight unit 10 may omit some of the light source 11 , the reflective plate 12 , the light guide plate 13 , the optical film 14 , and the reflective polarizing sheet 15 or further include an additional configuration. .

For example, the backlight unit 10 may further include a diffusion sheet. Here, the diffusion sheet may uniformly disperse the light incident from the light guide plate 13 . The diffusion sheet may cause light diffusion by the light diffusion agent beads by applying a curable resin solution to which light diffusion agent beads are added. In addition, a protrusion pattern (or protrusion) having a uniform or non-uniform size shape (eg, a spherical shape) may be formed in the diffusion sheet to promote light diffusion. As an example, the curable resin solution may be defined as being alone or mixed by selecting at least one of urethane acrylate, epoxy acrylate, ester acrylate, and radical generating monomers.

Hereinafter, a detailed description of the configuration overlapping with the above-described optical film 14 will be omitted for convenience of description.

2 is a cross-sectional view of an optical film according to an embodiment of the present invention.

Referring to FIG. 2 , the optical film 20 includes a base film 21 and a prism pattern layer 22 .

The base film 21 supports the prism pattern layer 22 . For example, one side of the base film 21 and one side of the prism pattern layer 22 may be adhered by an adhesive. Here, the adhesive may be a pressure sensitive adhesive (PSA). Accordingly, the optical film 20 may be integrated with the base film 21 and the prism pattern layer 22 being adhered thereto.

In addition, the base film 21 may transmit light of various frequency bands. For example, the base film 21 may transmit infrared rays smoothly.

보다 크고 90

보다 작게 형성될 수 있다. 예를 들어, 복수의 프리즘의 단면은 삼각형 또는 사다리꼴로 형성될 수 있다.The prism pattern layer 22 is adhered to one side of the base film 21 to condense light. Specifically, the prism pattern layer 22 may be disposed so that the protruding directions of the plurality of prisms face the light source, and may collect light emitted from the light source and passing through the light guide plate 13 . For light collection, the apex angle θ of the plurality of prisms 22 included in the prism pattern layer 22 is 0

greater than 90

It can be formed smaller. For example, the cross-sections of the plurality of prisms may be formed in a triangular or trapezoidal shape.

The prism pattern layer 22 may form a line pattern in which a plurality of prisms are disposed parallel to each other at a predetermined interval to transmit infrared rays. Here, the line pattern may include a plurality of flat lines having the predetermined interval as a width. The line pattern smoothly transmits infrared rays emitted from the infrared light source, thereby greatly improving the fingerprint recognition rate through infrared rays.

The prism pattern layer 22 may include an infrared absorption dye. Specifically, the plurality of prisms included in the prism pattern layer 22 may include an infrared absorber. Here, the plurality of prisms may be formed of an acrylic resin including an infrared absorber. In this case, the optical film 20 can easily transmit visible light while minimizing diffuse reflection caused by infrared rays passing through a plurality of prisms. For example, the infrared absorber may absorb infrared light of 900 nm to 950 nm and transmit visible light of 350 nm to 750 nm.

The diffuse reflection induced by irradiating infrared rays to a plurality of prisms will be described in detail below with reference to FIGS. 3 to 6 .

3 illustrates diffuse reflection of infrared rays according to an embodiment of the present invention.

Referring to FIG. 3 , the infrared effective signal 301 emitted from the infrared light source and irradiated to the line patterns 311 and 312 passes through the line pattern 311 and is reflected by the fingerprint 30 , and then the line pattern 312 is formed. It can be transmitted through and received by an infrared sensor. Here, the line patterns 311 and 312 may be defined as one region of one surface of the base film.

On the other hand, the infrared 303 emitted from the infrared light source and irradiated to the plurality of prisms 320, and the infrared 302 that is reflected by the fingerprint 30 or other object and transmits the plurality of prisms 320 are the plurality of prisms ( 320) may be diffusely reflected or refracted in at least two or more directions.

4 shows a state in which the above-mentioned infrared rays of FIG. 3 are received by the infrared sensor, the infrared effective signal 301 emitted from the infrared light source and irradiated to the line patterns 311 and 312 is a high transmission state 401 without diffuse reflection. shows On the other hand, the infrared rays 303 emitted from the infrared light source and irradiated to the plurality of prisms 320 and the infrared rays 302 reflected by the fingerprint 30 or other objects and transmitted through the plurality of prisms 320 are infrared rays according to diffuse reflection. By being accommodated in the arbitrary areas 402 and 403 of the sensor, it may act as noise that impairs the recognition rate of the fingerprint 30 .

Hereinafter, the function of the infrared absorber for minimizing diffuse reflection of infrared rays will be described in detail with reference to FIGS. 5 and 6 .

5 illustrates diffuse reflection of infrared rays according to another embodiment of the present invention.

Referring to FIG. 5 , the infrared effective signal 501 emitted from the infrared light source and irradiated to the line patterns 511 and 512 passes through the line pattern 511 and is reflected by the fingerprint 50 and then the line pattern 512 is formed. It can be transmitted through and received by an infrared sensor.

On the other hand, the infrared rays 503 and 504 emitted from the infrared light source and irradiated to the plurality of prisms 520 and the infrared rays 502 that are reflected by the fingerprint 50 or other object and transmit the plurality of prisms 520 are a plurality of It may be diffusely reflected or refracted in at least two or more directions while passing through the prism 520 . Here, the plurality of prisms 520 may absorb infrared rays passing through the plurality of prisms 520 because they contain an infrared absorber. Accordingly, the diffuse reflection of the infrared rays 502 , 503 , and 504 penetrating the plurality of prisms 520 may be greatly reduced than the diffuse reflection of the infrared rays 302 , 303 penetrating the plurality of prisms 320 in FIG. 3 .

FIG. 6 shows a state in which the infrared rays of FIG. 5 are accommodated in the infrared sensor. The infrared effective signal 501 emitted from the infrared light source and irradiated to the line patterns 511 and 512 is a high transmission state 601 without diffuse reflection. shows In addition, the infrared rays 503 and 504 emitted from the infrared light source and irradiated to the plurality of prisms 520, and the infrared rays 502 reflected by the fingerprint 50 or other object and transmitted through the plurality of prisms 520 are a plurality of Since it is absorbed by the infrared absorber included in the prism 520 , it does not affect the infrared effective signal 501 as noise.

Hereinafter, with reference to FIG. 7 , the line pattern 21-1 according to the ratio between the width a of the plurality of prisms 22 and the predefined interval b of the line patterns 21-1 to 21-6 to 21-6) will be described, and with reference to FIG. 8 , a change in the infrared absorptivity of the plurality of prisms 22 according to the ratio of the infrared absorbers included in the plurality of prisms 22 will be described. do.

Hereinafter, a is the width of the plurality of prisms 22 (prism pitch), b is the width of the line patterns 21-1 to 21-6 (plate range), c is the height of the plurality of prisms (prism height), P is defined as the sum of the widths of the plurality of prisms and the widths of the line patterns (total pitch).

7 illustrates infrared transmittance for a line pattern according to an embodiment of the present invention.

Referring to FIG. 7 , in Experiment 1, a was set to 15 μm, b was 3 μm, a:b was 5:1, and c was set to 11.1 μm. Next, in Experiment 2, a was set to 12 μm, b was 6 μm, a:b was 2:1, and c was set to 8.8 μm. Finally, in Experiment 3, a was set to 9 μm, b was 9 μm, a:b was 1:1, and c was set to 6.6 μm. Here, the sum of a and b may be set to P. For example, in the experiment, P was set to 18 μm, but the present invention is not limited thereto. That is, P can be variously changed, such as 24um, 30um, etc. in addition to 18um, and accordingly the lengths of a, b, and c can be changed.

In Experiment 1, the straight infrared transmittance with respect to the width b of the line patterns 21-1 to 21-6 was 15%, and in Experiment 2, the straight infrared transmittance with respect to the width b of the line patterns 21-1 to 21-6 was 30%, and the straight infrared transmittance with respect to the width b of the line patterns 21-1 to 21-6 in Experiment 3 was measured to be 45%.

In the optical fingerprint recognition method, since fingerprint recognition is possible when the infrared transmittance is at least 30% or more, the ratio of the width b of the line patterns 21-1 to 21-6 to the width a of the plurality of prisms 22 is 2:1 should be more than That is, the width b of the line patterns 21-1 to 21-6 is preferably at least 1/2 times the width a of the plurality of prisms 22 .

In addition, as the ratio of the width b of the line patterns 21-1 to 21-6 to the width a of the plurality of prisms 22 increases, the luminance of light to the optical films 14 and 20 decreases, so that the plurality of prisms The ratio of the width b of the line patterns 21-1 to 21-6 to the width a of 22 should be 1:1 or less. That is, it is preferable that the width b of the line patterns 21-1 to 21-6 is at least one time or less the width a of the plurality of prisms 22 .

In summary, the width b of the line patterns 21-1 to 21-6 is preferably 1/2 or more of the width a of the plurality of prisms 22 , and preferably less than or equal to 1 time of the width a of the plurality of prisms 22 . do.

8 illustrates infrared absorption rates for a plurality of prisms according to an embodiment of the present invention.

Referring to FIG. 8 , in Experiments 1 to 3, the width of the plurality of prisms 22 is a. In Experiment 1, the content of the infrared absorber was 0.0001%, in Experiment 2, the content of the infrared absorber was 0.00015%, and in Experiment 3, the content of the infrared absorber was 0.0003%.

In Experiment 1, the infrared absorption rate for the plurality of prisms 22 was 35%, the infrared absorption rate for the plurality of prisms 22 in Experiment 2 was 55%, and in Experiment 3, the infrared absorption rate for the plurality of prisms 22 was 35%. The absorption rate is 90%.

It is preferable that the plurality of prisms 22 absorb at least 55% or more of the infrared ray as the noise caused by the diffuse reflection of infrared ray with respect to the plurality of prisms 22 . Therefore, the content of the infrared absorber included in the plurality of prisms 22 is preferably 0.00015% or more.

In addition, when the content of the infrared absorber included in the plurality of prisms 22 exceeds 0.0005%, the luminance may be reduced because absorption of visible light is partially generated. Therefore, the content of the infrared absorber included in the plurality of prisms 22 is preferably 0.0005% or less.

In summary, when the content of the infrared absorber included in the plurality of prisms 22 is 0.00015% or more and 0.0005% or less, it is possible to minimize the decrease in luminance due to loss of visible light while minimizing infrared noise due to the action of the infrared absorber. Accordingly, the content of the infrared absorber included in the plurality of prisms 22 is preferably 0.00015% or more and 0.0005% or less.

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

Referring to FIG. 9 , the optical fingerprint recognition system 90 may include an infrared light source 910 , an image sensor or infrared sensor 920 , a reflector 930 , and an optical film 940 .

The infrared light source 910 may emit infrared LED light. For example, the infrared light source 910 may irradiate infrared rays having a wavelength of 750 nm or more. Since infrared light has a relatively long wavelength, light loss is small and diffuse reflection is low, so that a clear image may be obtained from the image sensor 920 .

The image sensor 920 senses a fingerprint image. The image sensor 920 converts the infrared light reflected by the fingerprint into an electrical signal and stores it. For example, the image sensor 920 may be a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS).

The reflector 930 may refract infrared rays. For example, the reflector 930 may refract infrared rays emitted from the infrared light source 910 or may refract infrared rays reflected by a fingerprint. For example, the reflector 930 may include various applications for refracting the direction of light, such as at least one prism and a beam splitter.

Here, the reflecting device 930 may be formed under the reflecting plate 12 described with reference to FIG. 1 . In addition, it may be formed of a material that transmits visible light and formed on the reflective plate 12 .

The reflector 930 may not be an essential component. For example, when the optical fingerprint recognition system 90 does not include the reflecting device 930, the infrared rays 301 emitted from the infrared light source in FIG. 3 and the infrared rays 501 emitted from the infrared light source in FIG. , of course, infrared rays emitted from the infrared light source 910 may be incident on the optical film 940 obliquely.

The optical film 940 may include a base film 941 and a prism pattern layer 942 .

The prism pattern layer 942 may be disposed to face the infrared light source 910 . Specifically, the prism pattern layer 942 may be disposed in a direction (D) in which infrared rays are incident on the prism pattern layer 942 . In this case, the arrangement direction of the prism pattern layer 942 may be defined as a reverse arrangement.

A plurality of prisms included in the prism pattern layer 942 may be arranged in parallel with a predetermined interval E. Here, the predefined interval E may be defined as the width E of the line pattern.

For example, the content of the infrared absorber included in at least one prism among the plurality of prisms 942 may exceed the content of the infrared absorber included in at least another prism of the plurality of prisms 942 . Specifically, the content of the infrared absorber included in at least one of the prisms 942-1, 942-2, and 942-3 corresponding to the position of the fingerprint among the plurality of prisms 942 is, among the plurality of prisms 942, the fingerprint. The content of the infrared absorber included in the at least one prism 942-4, 942-5, 942-6, and 942-7 corresponding to a region other than the position of may be exceeded. Through this, the infrared transmittance for the region of the optical film 940 corresponding to the position 950 of the fingerprint is relatively improved than the infrared transmittance for the region of the optical film 940 corresponding to the region other than the position 950 of the fingerprint. can be

Also, among the plurality of prisms 942 , the plurality of prisms 942-4, 942-5, 942-6, and 942-7 corresponding to areas other than the position of the fingerprint may not include an infrared absorber. That is, the infrared absorber may be included only in the plurality of prisms 942-1, 942-2, and 942-3 corresponding to the position of the fingerprint among the plurality of prisms 942 . Through this, a decrease in luminance may be minimized.

Hereinafter, a detailed description of the content overlapping with the configuration of the optical fingerprint recognition system 90 described above in FIG. 9 will be omitted for convenience of description.

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

Referring to FIG. 10 , the optical fingerprint recognition system 100 may include an infrared light source 1010 , an image sensor 1020 , a reflection device 1030 , and an optical film 1040 .

The optical film 1040 may include a base film 1041 and a prism pattern layer 1042 .

For example, the prism pattern layers 1042 may be disposed in parallel with a predetermined interval F. Here, the predefined interval F may be defined as the width F of the line pattern.

For example, among the line patterns 1042-1, 1042-2, 1042-3, 1042-4, 1042-5, 1042-6, the line patterns 1042-3 and 1042-4 corresponding to the position 1050 of the fingerprint ) may be different from the widths of the line patterns 1042-1, 1042-2, 1042-5, and 1042-6 corresponding to areas other than the location 1050 of the fingerprint.

For example, the width of the line patterns 1042-1, 1042-2, 1042-5, and 1042-6 corresponding to positions other than the position 1050 of the fingerprint may be formed as F. In this case, the line patterns 1042-3 and 1042-4 corresponding to the position 1050 of the fingerprint among the line patterns 1042-1, 1042-2, 1042-3, 1042-4, 1042-5, and 1042-6. ) may be formed at intervals larger than F.

According to the above-described embodiment of the present invention, among the line patterns 1042-1, 1042-2, 1042-3, 1042-4, 1042-5, 1042-6, the line pattern ( By forming the widths of 1042-3 and 1042-4 to be larger than the widths of the line patterns 1042-1, 1042-2, 1042-5, and 1042-6 corresponding to areas other than the location 1050 of the fingerprint, For the region of the optical film 1040 corresponding to the position 1050, the transmittance of infrared rays is increased, and for the region of the optical film 1040 corresponding to the region other than the position 1050 of the fingerprint, the reduction in light collection performance and brightness can be minimized. there is.

In addition, line patterns 1042-3 and 1042-4 corresponding to the position 1050 of the fingerprint among the line patterns 1042-1, 1042-2, 1042-3, 1042-4, 1042-5, and 1042-6. The width of is formed to be larger than the width of the line patterns 1042-1, 1042-2, 1042-5, and 1042-6 corresponding to areas other than the position 1050 of the fingerprint, and at the same time, the fingerprint of the plurality of prisms 1042 is formed. The content of the infrared absorber included in the at least one prism 1042-3, 1042-4, 1042-5 corresponding to the position of (1042-1, 1042-2, 1042-6, 1042-7) may exceed the content of the infrared absorber included, of course.

Additionally, the optical film 1040 may not form a line pattern in a region other than the position 1050 of the fingerprint. That is, in the optical film 1040 , a line pattern may be formed only in an area corresponding to the position 1050 of the fingerprint. Accordingly, it is possible to minimize a decrease in the light collecting efficiency in the prism pattern layer 1042 .

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

Referring to FIG. 11 , the optical fingerprint recognition system 110 may include an infrared light source 1110 , an image sensor 1120 , a reflector 1130 , and an optical film 1140 .

The optical film 1140 may include a base film 1141 and a prism pattern layer 1142 .

For example, the optical film 1140 may include a plurality of through holes 1101 . Here, the plurality of through-holes 1101 may be formed in the infrared ray traveling direction (H or I) to transmit the infrared ray. For example, when the traveling direction of infrared rays is inclined at a predetermined angle with respect to the optical film 1140 , the plurality of through holes 1101 may also be formed at an angle inclined according to the traveling direction of infrared rays. In addition, the plurality of through holes 1101 may be formed in a region corresponding to the position 1150 of the fingerprint at a predetermined interval.

Infrared rays may simultaneously pass through the base film 1141 and the prism pattern layer 1142 through the plurality of through holes 1101 . Here, the plurality of through-holes 1101 may be arranged at a predetermined interval.

Referring to FIG. 11 , infrared rays may be effectively transmitted through the line pattern of the prism pattern layer 1142 of the optical film 1140 and the plurality of through holes 1101 .

Of course, the plurality of through-holes 1101 of FIG. 11 described above may be formed in the optical film 940 of FIG. 9 and the optical film 1040 of FIG. 10 .

The above-described optical films 14 , 20 , 940 , 1040 , and 1140 according to various embodiments of the present invention may be included in the backlight unit. Also, it goes without saying that the backlight unit may be included in the LCD device together with the LCD panel.

While the embodiments of the present invention have been shown and described, various changes in form and details may be made by those skilled in the art without departing from the spirit and scope of the embodiments as defined by the appended claims and their equivalents. you will understand that you can

Optical Film: 14, 20, 940, 1040, 1140
Base film: 14-1, 21, 941, 1041, 1141
Prism pattern layer: 14-2, 22, 942, 1042, 1142
Optical fingerprint recognition system: 90, 100, 110
Infrared light source: 910, 1010, 1110

Claims (14)

In the optical film for fingerprint recognition that transmits infrared (infrared),
base film; and
Including; a prism pattern layer adhered to one side of the base film;
The prism pattern layer,
A plurality of prisms formed including an infrared absorber are arranged parallel to each other at a predetermined interval to form a line pattern that transmits the infrared rays,
The predefined interval of the line pattern is,
More than 1/2 times the width of the plurality of prisms, and less than 1 times the width of the plurality of prisms,
Optical film for fingerprint recognition.
According to claim 1,
The content of the infrared absorber included in the plurality of prisms is 0.00015% or more and 0.0005% or less, an optical film for fingerprint recognition.
3. The method of claim 2,
The plurality of prisms,
An optical film for fingerprint recognition, which is formed of an acrylic resin containing the infrared absorber.
delete According to claim 1,
The content of the infrared absorber included in at least one prism corresponding to the position of the fingerprint among the plurality of prisms is,
The optical film for fingerprint recognition, exceeding the content of the infrared absorber contained in at least one prism corresponding to a region other than the position of the fingerprint among the plurality of prisms.
According to claim 1,
An infrared absorber is included in only at least one prism corresponding to the position of the fingerprint among the plurality of prisms, an optical film for fingerprint recognition.
According to claim 1,
The prism pattern layer,
An optical film for fingerprint recognition, which is disposed so that the protruding directions of the plurality of prisms face the light source.
According to claim 1,
The cross-section of the plurality of prisms is a triangular or trapezoidal, optical film for fingerprint recognition.
According to claim 1,
The predefined interval is,
An optical film for fingerprint recognition, which is formed to be larger than the predetermined interval in an area corresponding to the position of the fingerprint.
According to claim 1,
The line pattern is formed only in an area corresponding to the position of the fingerprint, an optical film for fingerprint recognition.
According to claim 1,
The base film and the prism pattern layer,
An optical film for fingerprint recognition to form a plurality of through-holes formed in the traveling direction of the infrared rays to transmit the infrared rays.
11. The method of claim 10,
The plurality of through-holes,
An optical film for fingerprint recognition, which is formed in an area corresponding to the position of the fingerprint at a predetermined interval.
Claims 1 to 3, comprising the optical film for fingerprint recognition of any one of claims 5 to 12, a backlight unit.
LCD (liquid crystal display) panels; and
The LCD device comprising a; the backlight unit according to claim 13 located under the LCD panel.

Images