KR102368994B1 - Display protection glass structures capable of ultrasonic fingerprint recognition - Google Patents

Abstract

The present invention relates to a display protection glass structure capable of ultrasonic fingerprint recognition, which is to protect the display of a smart device based on ultrasonic fingerprint recognition. The structure includes: a display protection glass portion positioned in an upper layer portion of a display to protect the display of a lower layer portion; a release film positioned in a lower surface portion of the display protection glass portion to protect an adhesive layer formed in the lower layer portion of the display protection glass portion; and a release layer interposed between the release film and the lower portion of the display protection glass portion such that the release film can be easily attached to and detached from the lower portion of the display protection glass portion. The number of inter-substance interfaces in the display protection glass portion is two or less. In addition, preferably, a functional coating layer is further included that is formed on the upper surface of the display protection glass portion and performs blue light cut and antibacterial functions while preventing contamination from the outside.

Description

Display protection glass structures capable of ultrasonic fingerprint recognition

The present invention relates to a display protection glass structure employed in a smartphone, and more particularly, ultrasonic fingerprint recognition capable of improving fingerprint recognition performance by minimizing factors that interfere with the transmission of ultrasonic waves in an ultrasonic fingerprint recognition system of a smart device. Possible display protective glass structures.

Recently, various mobile terminals such as mobile phones, smart phones, tablet PCs, notebook PCs, and navigation devices are equipped with touch screen type displays that allow direct manipulation and easy confirmation of operating conditions.

These existing portable terminals use a touch screen as a main input device, and various function keys are used as auxiliary input devices. Among them, a fingerprint recognition sensor is embedded in the home key to enable personal authentication.

In accordance with the recent increase in demand for functionality, aesthetics, security, etc. of portable terminals, the conventional home key is not separately provided so as to be directly exposed on the display surface, but the home key and fingerprint are located at a specific location of the display (for example, the lower surface of the display). A mobile terminal using an in-display fingerprint recognition sensor with a built-in recognition sensor is being commercialized.

As described above, a method of recognizing a fingerprint by a fingerprint recognition sensor built into the display of the portable terminal includes an optical type, a capacitive type, an ultrasonic type, and the like.

First, the optical method collects the fingerprint curvature according to the shadow of the reflected light of the light irradiated from the light source. The fingerprint recognition sensor is located on the lower surface of the display, and the production cost is low and the yield is high, but the accuracy of fingerprint recognition is low. The capacitive type measures the difference in capacitance according to the curvature of the fingerprint. The fingerprint recognition sensor is located on the upper surface of the display, and while the accuracy of fingerprint recognition is excellent, durability or yield is poor. The ultrasonic type scans the microscopic features of the epidermal layer of the skin using ultrasound. The fingerprint recognition sensor is located on the lower surface of the display and the fingerprint can be recognized in 3D, so the accuracy of fingerprint recognition is high and security is excellent, but However, there is a disadvantage that the yield is lowered. However, such an ultrasonic fingerprint recognition sensor uses ultrasonic waves to combine biometric information such as depth of fingerprint, pores, shape of skeleton, and movement of blood flow. It has the advantage of blocking the possibility and enabling quick and accurate identification of biometric information.

On the other hand, Korean Patent Application Laid-Open No. 10-2021-0036569 (Patent Document 1) discloses "a liquid crystal protective film capable of ultrasonic fingerprint recognition". It is attached to the upper portion of the liquid crystal of a smart device having a sensor and includes a liquid crystal protection film unit provided to protect the liquid crystal, wherein the liquid crystal protection film unit includes: a first layer attached to the upper portion of the liquid crystal; a second layer formed on top of the first layer; and a liquid crystal adhesive layer formed under the first layer and provided to adhere the liquid crystal and the first layer.

In the case of Patent Document 1 as described above, the impedance difference between the liquid crystal, the first layer, the second layer, and the liquid crystal adhesive layer is controlled so that the fingerprint recognition performance decrease is within 0.35 dB, so that even when the liquid crystal protective film unit is attached to the liquid crystal, high fingerprint Although there is an advantage of maintaining the recognition rate, the first layer, which is the main component that protects the liquid crystal, is polyethylene terephthalate (PET), polyethylene (PE), polycarbonate (PC), polypropylene (PP), polymethyl meta Since it is made of a synthetic resin material such as acrylate (PMMA) or polyurethane (PU), it has a problem in that it is difficult to stably protect the liquid crystal from external impact or heat.

Korean Patent Publication No. 10-2021-0036569 (2021.04.05.)

The present invention was created in consideration of the above, and a display protective glass capable of ultrasonic fingerprint recognition that can improve fingerprint recognition performance by minimizing factors that interfere with the transmission of ultrasonic waves in an ultrasonic fingerprint recognition system of a smart device The purpose is to provide a structure.

In order to achieve the above object, a display protection glass structure capable of ultrasonic fingerprint recognition according to an embodiment of the present invention,

As a protective glass structure for protecting the display of a smart device of the ultrasonic fingerprint recognition method,

a display protection glass portion positioned on the upper layer of the display to protect the display of the lower layer;

a release film disposed on the lower surface of the display protective glass part and protecting the adhesive layer formed in the lower layer of the display protective glass part; and

and a release layer interposed between the release film and the lower part of the display protective glass part so that the release film is easily attached to and detached from the lower part of the display protective glass part,

The interface between the materials in the display protection glass portion is characterized in that it is composed of two or less.

Here, it is preferably formed on the upper surface of the display protection glass part, and may further include a functional coating layer that prevents contamination from the outside, and performs a blue light cut function and an antibacterial function.

In addition, the display protection glass portion,

a protective glass for protecting the display of the lower layer;

a first adhesive layer for adhering the protective glass to the lower layer; and

It may be configured to include a second adhesive layer positioned between the first adhesive layer and the release layer to adhere the first adhesive layer and the release layer.

In this case, the first adhesive layer may be configured to have an adhesive strength of 1000 gf/25 mm or more, and the second adhesive layer may be configured to have an adhesive strength of 10 gf/25 mm or less.

In addition, the thickness of the first adhesive layer and the second adhesive layer may be adjusted so that the ultrasonic wavelength λ is a multiple of λ/2.

In addition, the total thickness of the first adhesive layer and the second adhesive layer may be configured to be 100 μm or less, preferably 60 μm or less.

In this case, the first adhesive layer may have a thickness of 20 μm and the second adhesive layer may have a thickness of 30 μm, respectively.

In addition, the average transmittance of the visible light region of the display protection glass portion may be 92% or more, and Haze (opacity) may be configured to 0.5% or less.

In addition, in order to achieve the above object, a display protective glass structure capable of ultrasonic fingerprint recognition according to another embodiment of the present invention,

As a protective glass structure for protecting the display of a smart device of the ultrasonic fingerprint recognition method,

a display protection glass portion positioned on the upper layer of the display to protect the display of the lower layer;

a release film disposed on the lower surface of the display protective glass part and protecting the adhesive layer formed in the lower layer of the display protective glass part; and

and a release layer interposed between the release film and the lower part of the display protective glass part so that the release film is easily attached to and detached from the lower part of the display protective glass part,

It is characterized in that a separate means for enhancing the tensile force between the adhesive layers is provided in the display protection glass part.

Here, it is preferably formed on the upper surface of the display protection glass part, and may further include a functional coating layer that prevents contamination from the outside, and performs a blue light cut function and an antibacterial function.

In addition, the display protection glass portion,

a protective glass for protecting the display of the lower layer;

a first adhesive layer for adhering the protective glass to the lower layer;

a second adhesive layer positioned between the first adhesive layer and the release layer to adhere the first adhesive layer and the release layer; and

A plastic film interposed between the first adhesive layer and the second adhesive layer to enhance tensile force between the first adhesive layer and the second adhesive layer may be included.

In this case, the first adhesive layer may be configured to have an adhesive strength of 1000 gf/25 mm or more, and the second adhesive layer may be configured to have an adhesive strength of 10 gf/25 mm or less.

In addition, the thickness of the first adhesive layer and the second adhesive layer may be adjusted so that the ultrasonic wavelength λ is a multiple of λ/2.

In addition, the total thickness of the first adhesive layer and the second adhesive layer may be configured to be 100 μm or less, preferably 60 μm or less.

In this case, the first adhesive layer may have a thickness of 20 μm and the second adhesive layer may have a thickness of 30 μm, respectively.

In addition, the plastic film may be composed of a plastic film having a thickness of 10 μm or less having an electrostatic capacity.

According to the present invention as described above, there is an advantage in that fingerprint recognition performance can be further improved by minimizing the number of interfaces between materials, which is a major factor among factors that impede the transmission of ultrasonic waves in the ultrasonic fingerprint recognition system of a smart device.

1 is a view schematically showing the configuration of a display protective glass structure capable of ultrasonic fingerprint recognition according to an embodiment of the present invention.
2 is a view schematically showing the configuration of a display protective glass structure capable of ultrasonic fingerprint recognition according to another embodiment of the present invention.

The terms or words used in the present specification and claims should not be construed as limited to their ordinary or dictionary meanings, and the inventor may appropriately define the concept of the term in order to best describe his invention. Based on the principle, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, terms such as “…unit”, “…group”, “module”, and “device” described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. can be implemented as

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing the configuration of a display protective glass structure capable of ultrasonic fingerprint recognition according to an embodiment of the present invention.

Referring to FIG. 1 , a display protection glass structure 100 capable of ultrasonic fingerprint recognition according to an embodiment of the present invention is a protective glass structure for protecting the display of a smart device of an ultrasonic fingerprint recognition method, and a display protection glass part (110), the release film 130, and is configured to include a release layer (140). Here, preferably, the functional coating layer 120 may be further included.

The display protection glass unit 110 is positioned on the upper layer of the display to protect the display of the lower layer. Such a display protection glass portion 110 includes a protective glass 111 for protecting the display of the lower layer, and a first adhesive layer 112 for adhering the protective glass 111 and the lower layer; and a second adhesive layer 113 positioned between the first adhesive layer 112 and the release layer 140 to adhere the first adhesive layer 112 and the release layer 140 . Here, the protective glass 111 may be made of tempered glass. In addition, the first adhesive layer 112 is configured to have a relatively strong adhesive force compared to the second adhesive layer 113, and the second adhesive layer 113 is configured to have a relatively weak adhesive force having a self-adhesive function. can be For example, the first adhesive layer 112 may be configured to have an adhesive strength of 1000 gf/25 mm or more, and the second adhesive layer 113 may be configured to have an adhesive strength of 10 gf/25 mm or less. In addition, in the first adhesive layer 112 and the second adhesive layer 113 , the thickness of the first adhesive layer 112 and the second adhesive layer 113 is such that the ultrasonic wave λ is a multiple of λ/2. can be adjusted. Here, the total thickness of the first adhesive layer 112 and the second adhesive layer 113 may be 100 μm or less, preferably 60 μm or less. In this case, the first adhesive layer 112 may have a thickness of 20 μm, and the second adhesive layer 113 may have a thickness of 30 μm, respectively. Here, the first adhesive layer 112 as described above may be made of an acrylic material, and the second adhesive layer 113 may be made of a silicone-based material.

The functional coating layer 120 is formed on the upper surface of the protective glass 111 of the display protective glass unit 110, and has a function of preventing contamination by contaminants from the outside, a blue light cut function, and an antibacterial function. carry out Here, blue light is a blue light that exists in a wavelength between 380 and 500 nm, and is widely emitted from displays and LED lighting devices of smart devices such as TVs and computers, and has the shortest wavelength and strong energy among visible light. It is a light source with It has been reported that such blue light is controversial, and long exposure to blue light may cause eye fatigue as well as dry eye syndrome, and in severe cases may cause damage to the retina or lens in the eye.

The release film 130 is positioned on the lower surface of the display protection glass unit 110 , and protects the adhesive layer (ie, the second adhesive layer 113 ) formed on the lower layer of the display protection glass unit 110 . plays a role Here, such a release film 130 is a portion that is removed when attaching the display protective glass structure 100 of the present invention to a mobile phone (smartphone).

The release layer 140 is interposed between the release film 130 and the display protection glass unit 110 (more precisely, the second adhesive layer 113 ) so that the release film 130 is formed on the display protection glass unit 110 . ) to be easily detached from the lower part.

The display protection glass structure 100 capable of ultrasonic fingerprint recognition according to the present invention having the above configuration is between materials in the display protection glass unit 110 (that is, the protection glass 111, the first adhesive layer 112) , the interface between the second adhesive layer 113) is two or less (that is, in this embodiment, the interface between the protective glass 111 and the first adhesive layer 112 (the first interface) and the first adhesive layer ( 112) and the second adhesive layer 113 (having two interfaces as the interface (second interface)) is configured. As described above, in the present invention, the fingerprint recognition performance can be further improved by minimizing the number of interfaces between materials, which is a major factor among factors that impede the transmission of ultrasonic waves in the ultrasonic fingerprint recognition system of a smart device.

Here, we will try to add a little more explanation in relation to the interface as described above.

When a sound wave is incident on the interface of two materials having different acoustic resistances, a portion of the sound wave is reflected, and the size of the sound wave is reflected by the difference in acoustic resistance between the two materials. As the difference in acoustic resistance increases, reflection increases. This is because the greater the difference in density between the two materials, the greater the difference in acoustic resistance forms an interface. Here, the acoustic resistance can be expressed by the following equation.

Here, Z is the acoustic resistance, ρ is the density, C is the speed of sound waves, and E is the bulk modulus of elasticity, respectively.

In addition, the acoustic resistance (Z), density (ρ), sound wave velocity (C), and bulk modulus (E) of materials used for general display protection glass are summarized in Table 1 below.

Acoustic resistance (Z) Density (ρ) speed of sound (C) bulk modulus (E) Glass 14.50 2.45 5.92 85.82 Acrylic 3.15 1.20 2.63 8.27 PET Film 2.10 1.40 1.50 3.00 Silicon 1.40 2.30 0.61 0.85

In Table 1, "Glass", "Acrylic", and "Silicon" are the protective glass 111, the first adhesive layer 112, and the second adhesive layer ( 113), respectively.

Table 2 below summarizes the evaluation results of optical characteristics and fingerprint recognition performance of the display protection glass structure capable of ultrasonic fingerprint recognition according to the present invention and Comparative Examples.

Display protection glass structure optical properties Fingerprint recognition performance Average
transmittance YI Haze recognize
Performance recognize
speed recognize
Sensitivity Comparative Example 1 Protective glass/commercially available AB Film 91.5% 0.87 1.19 △ ◇ × the present invention Protective glass / 1st adhesive layer / 2nd adhesive layer 92.8% 0.35 0.17 ◎ ◎ ○ Comparative Example 2 Protective Glass / 1st Adhesive Layer / Plastic Film / 2nd Adhesive Layer - - - ◇ ◇ ×

(◎:Excellent, ○:Good, ◇:Not good, △:Bad, ×:Too bad)

As can be seen from Table 2 above, the display protection glass structure of the present invention has significantly superior fingerprint recognition performance compared to Comparative Examples. It can be seen that the optical properties are also better. Here, in relation to the above optical properties, the average transmittance of the visible light region of the display protection glass part 110 in the display protection glass structure 100 according to an embodiment of the present invention is 92% or more, Haze (opacity) may be composed of 0.5% or less.

Meanwhile, FIG. 2 is a view schematically showing the configuration of a display protective glass structure capable of ultrasonic fingerprint recognition according to another embodiment of the present invention.

Referring to FIG. 2 , the display protection glass structure 200 capable of ultrasonic fingerprint recognition according to another embodiment has the same basic configuration as the display protection glass structure 100 capable of ultrasonic fingerprint recognition according to the embodiment described above. . However, the case of this other embodiment is different from the case of the embodiment described above in that the plastic film 214 is interposed between the first adhesive layer 212 and the second adhesive layer 213 . That is, the plastic film 214 for enhancing the tensile force between the first adhesive layer 212 and the second adhesive layer 213 is further interposed between the first adhesive layer 212 and the second adhesive layer 213 . Of course, since the plastic film 214 is further interposed in this way, the number of interfaces between materials, which is a main factor among factors that interfere with the transmission of ultrasonic waves in the display protective glass unit 210 in the ultrasonic fingerprint recognition system of a smart device, is increased. This may lead to a problem in which the fingerprint recognition performance is degraded. However, in the present invention, a plastic film 214 that does not affect the fingerprint recognition rate was prepared through various experiments. That is, it was confirmed through self-experiment that the use of a plastic film with a thickness of 10 μm or less having a capacitance has little effect on the fingerprint recognition rate.

Then, the display protection glass portion 210, the release film 230, and the release layer 240 in the display protection glass structure 200 capable of ultrasonic fingerprint recognition according to another embodiment will be described below. Here, preferably, the functional coating layer 220 may be further included in this other embodiment.

The display protection glass part 210 is positioned on the upper layer of the display to protect the display of the lower layer. The display protective glass portion 210 includes a protective glass 211 for protecting the display of the lower layer, and a first adhesive layer 212 for adhering the protective glass 211 and the lower layer; a second adhesive layer 213 positioned between the first adhesive layer 212 and the release layer 240 to adhere the first adhesive layer 212 and the release layer 240; and a plastic film 214 interposed between the first adhesive layer 212 and the second adhesive layer 213 to enhance tensile force between the first adhesive layer 212 and the second adhesive layer 213 . can be Here, the protective glass 211 may be made of tempered glass. In addition, the first adhesive layer 212 is configured to have a relatively strong adhesive force compared to the second adhesive layer 213 , and the second adhesive layer 213 is configured to have a relatively weak adhesive force having a self-adhesive function. can be For example, the first adhesive layer 212 may be configured to have an adhesive strength of 1000 gf/25 mm or more, and the second adhesive layer 213 may be configured to have an adhesive strength of 10 gf/25 mm or less. In addition, the first adhesive layer 212 and the second adhesive layer 213 have the thickness of the first adhesive layer 212 and the second adhesive layer 213 such that the ultrasonic wave λ is a multiple of λ/2. can be adjusted. Here, the sum of the thicknesses of the first adhesive layer 212 and the second adhesive layer 213 may be 100 μm or less, preferably 60 μm or less. In this case, the first adhesive layer 212 may have a thickness of 20 μm, and the second adhesive layer 213 may have a thickness of 30 μm, respectively. Here, the first adhesive layer 212 as described above may be made of an acrylic material, and the second adhesive layer 213 may be made of a silicone-based material. Also, the plastic film 214 may be formed of a plastic film having a capacitance of 10 μm or less. Here, the plastic film may include a polyethylene terephthalate (PET) film, a polypropylene (PP) film, a polyethylene naphthalate (PEN) film, and a polycarbonate (PC) film.

The functional coating layer 220 is formed on the upper surface of the protective glass 211 of the display protective glass part 210, and has a function of preventing contamination by contaminants from the outside, a blue light cut function, and an antibacterial function. carry out

The release film 230 is positioned on the lower surface of the display protection glass unit 210 and protects the adhesive layer (ie, the second adhesive layer 213 ) formed on the lower layer of the display protection glass unit 210 . plays a role

The release layer 240 is interposed between the release film 230 and the display protection glass unit 210 (more precisely, the second adhesive layer 213 ) so that the release film 230 is formed on the display protection glass unit 210 . ) to be easily detached from the lower part.

As described above, the display protective glass structure capable of ultrasonic fingerprint recognition according to the present invention improves fingerprint recognition performance by minimizing the number of interfaces between materials, which are the main factors among factors that impede the transmission of ultrasonic waves in the ultrasonic fingerprint recognition system of smart devices. There are advantages to further improvement.

As mentioned above, although the present invention has been described in detail through preferred embodiments, the present invention is not limited thereto, and it is common in the art that various changes and applications can be made without departing from the technical spirit of the present invention. self-explanatory to the technician. Accordingly, the true protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent scope should be construed as being included in the scope of the present invention.

110,210: display protective glass portion 111,211: protective glass
112,212: first adhesive layer 113,213: second adhesive layer
120,220: functional coating layer 130,230: release film
140,240: release layer 214: plastic film

Claims (18)

As a protective glass structure for protecting the display of a smart device of the ultrasonic fingerprint recognition method,
a display protection glass portion positioned on the upper layer of the display to protect the display of the lower layer;
a release film disposed on the lower surface of the display protection glass unit and configured to protect the adhesive layer formed on the lower layer of the display protection glass unit; and
and a release layer interposed between the release film and the lower part of the display protective glass part so that the release film is easily attached to and detached from the lower part of the display protective glass part,
The interface between the materials in the display protection glass part consists of two or less,
The display protection glass portion,
a protective glass for protecting the display of the lower layer;
a first adhesive layer for adhering the protective glass to the lower layer; and
It is positioned between the first adhesive layer and the release layer and is configured to include a second adhesive layer for adhering the first adhesive layer and the release layer,
The first adhesive layer is configured to have a relatively strong adhesive force compared to the second adhesive layer, and the second adhesive layer is configured to have a relatively weak adhesive force compared to the first adhesive layer, having a self-adhesive function. Display protection glass structure capable of ultrasonic fingerprint recognition, characterized in that.
delete delete The method of claim 1,
The first adhesive layer is configured to have an adhesive strength of 1000 gf/25 mm or more, and the second adhesive layer is configured to have an adhesive strength of 10 gf/25 mm or less. delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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