KR102313975B1 - Finger sensor - Google Patents

Abstract

A fingerprint sensor according to an embodiment includes a substrate; a first electrode on the substrate; a piezoelectric layer on the first electrode; a second electrode on the piezoelectric layer; an intermediate layer on the second electrode; and a cover substrate on the intermediate layer, wherein the intermediate layer includes a plurality of protrusions disposed on at least one surface of one surface and the other surface of the intermediate layer.

Description

fingerprint sensor

Embodiments relate to fingerprint sensors.

A fingerprint sensor is a sensor that detects a person's fingerprint, and is widely used not only for devices such as door locks that have been widely applied in the past, but also for determining whether to turn on/off the power of electronic devices or release the sleep mode. is becoming

The fingerprint recognition sensor may be classified into an ultrasonic type, an infrared type, a capacitive type, and the like according to an operation principle thereof. For example, in the ultrasonic method, when ultrasonic signals of a certain frequency emitted from a plurality of piezoelectric sensors are reflected from the valleys and ridges of the fingerprint, the difference in acoustic impedance between the valleys and the peaks is measured. A method of detecting fingerprints by measuring using a plurality of piezoelectric sensors that are the source of ultrasonic waves. In particular, the advantage of the ultrasonic method is that it goes beyond the simple fingerprint recognition function and generates ultrasonic pulses in the form of pulses to reduce the Doppler effect by the echo. Since it has a function of grasping the blood flow inside the finger by detecting it, it can have the advantage of being able to determine whether or not a fake fingerprint exists using this.

Such a fingerprint sensor may recognize a fingerprint according to the generation of ultrasonic waves by disposing a piezoelectric sensor on a substrate and disposing electrodes on both sides of the piezoelectric sensor. At this time, in order for the ultrasonic wave to be smoothly transmitted from the piezoelectric sensor to the cover substrate, the smaller the difference between the acoustic impedance values of the piezoelectric sensor and the cover substrate, the better. can do.

At this time, when disposing a multi-layered buffer layer rather than a single layer, there is a problem in that the process efficiency is lowered and the thickness is increased.

Accordingly, there is a need for a fingerprint recognition sensor having a new structure capable of solving such a problem.

An embodiment is to provide a fingerprint sensor having improved efficiency and thin thickness.

A fingerprint sensor according to an embodiment includes a substrate; a first electrode on the substrate; a piezoelectric layer on the first electrode; a second electrode on the piezoelectric layer; an intermediate layer on the second electrode; and a cover substrate on the intermediate layer, wherein the intermediate layer includes a plurality of protrusions disposed on at least one surface of one surface and the other surface of the intermediate layer.

The fingerprint sensor according to the embodiment may include an intermediate layer including a plurality of protrusions. Accordingly, it is possible to smoothly move the ultrasonic signal transmitted from the piezoelectric layer toward the cover substrate or received from the cover substrate toward the piezoelectric layer.

The acoustic impedance value may be defined as a density and ultrasonic velocity value in a material, that is, an intermediate layer disposed between the piezoelectric layer and the cover substrate mitigates the difference in the acoustic impedance values of the piezoelectric layer and the cover substrate, so that the piezoelectric An ultrasonic signal transmitted from the layer to the cover substrate or received from the cover substrate to the piezoelectric layer may be smoothly moved.

In addition, when the wavelength of an ultrasonic signal having a wavelength larger than that of the protrusion pattern by forming a protrusion pattern on at least one of the one surface and the other surface of the intermediate layer passes through the intermediate layer, the effect such that the acoustic impedance gradually changes due to the protrusion can have

Therefore, even when the intermediate layer is formed as a single layer, as the acoustic impedance values of the piezoelectric layer and the cover substrate are changed stepwise by the intermediate layer, the ultrasonic signal transmitted or received smoothly moves to realize a thin thickness, and a fingerprint The efficiency of the sensor can be improved.

1 is a diagram illustrating a perspective view of a fingerprint sensor according to a first embodiment.
2 is a diagram illustrating a plan view of the fingerprint sensor according to the first embodiment.
3 is a view showing a cross-sectional view for explaining the operation principle of the fingerprint sensor.
4 to 6 are views illustrating cross-sectional views taken along the area AA′ of FIG. 1 .
7 is a diagram illustrating a perspective view of a fingerprint sensor according to a second embodiment.
8 to 13 are views illustrating cross-sectional views taken by cutting a region BB′ of FIG. 7 .
14 and 15 are diagrams illustrating fingerprint sensors according to various embodiments according to an arrangement position of electrodes.
16 to 19 are diagrams illustrating various devices to which a fingerprint sensor according to embodiments is applied.

In the description of embodiments, each layer (film), region, pattern or structure is “on” or “under” the substrate, each layer (film), region, pad or patterns. The description of being formed in " includes all those formed directly or through another layer. The standards for the upper/above or lower/lower layers of each layer will be described with reference to the drawings.

In addition, when it is said that a certain part is "connected" with another part, it includes not only the case where it is "directly connected" but also the case where it is "indirectly connected" with another member interposed therebetween. In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

In the drawings, the thickness or size of each layer (film), region, pattern, or structure may be changed for clarity and convenience of description, and thus does not fully reflect the actual size.

1 to 6 , the fingerprint sensor according to the first embodiment includes a substrate 100 , a first electrode 210 , a second electrode 220 , a piezoelectric layer 300 , an intermediate layer 400 , and a cover substrate. (500).

The substrate 100 may be rigid or flexible. For example, the substrate 100 may include glass or plastic. In detail, the substrate 100 includes chemically strengthened/semi-tempered glass such as soda lime glass or aluminosilicate glass, or polyimide (PI) or polyethylene terephthalate (PET). , propylene glycol (PPG), reinforced or soft plastic such as polycarbonate (PC), or may include sapphire.

In addition, the substrate 100 may include a photoisotropic film. For example, the substrate 100 may include Cyclic Olefin Copolymer (COC), Cyclic Olefin Polymer (COP), photoisotropic polycarbonate (PC), or photoisotropic polymethyl methacrylate (PMMA).

Also, the substrate 100 may be bent while having a partially curved surface. That is, the substrate 100 may be bent while partially having a flat surface and partially having a curved surface. In detail, the end of the substrate 100 may be curved while having a curved surface, or may have a surface including a random curvature and may be curved or bent.

In addition, the substrate 100 may be a flexible substrate having a flexible characteristic.

Also, the substrate 100 may be a curved or bent substrate. That is, the fingerprint sensor including the substrate may also be formed to have flexible, curved, or bent characteristics. For this reason, the fingerprint sensor according to the embodiment can be easily carried or combined, and can be changed into various designs.

A first electrode 210 , a second electrode 220 , a piezoelectric layer 300 , and an intermediate layer 400 may be disposed on the substrate 100 .

The first electrode 210 may be disposed on the substrate 100 . For example, the first electrode 210 may be disposed on one surface of the substrate 100 .

Also, the piezoelectric layer 300 may be disposed on the substrate 100 . For example, the piezoelectric layer 300 may be disposed on the first electrode 210 . In detail, the piezoelectric layer 300 may be disposed on the substrate 100 while surrounding the first electrode 210 .

Also, the second electrode 220 may be disposed on the substrate 100 . For example, the second electrode 220 may be disposed on the piezoelectric layer 300 .

Referring to FIG. 2 , an effective area AA and an ineffective area UA may be defined in the piezoelectric layer 300 .

The effective area AA may be an area in which a fingerprint is recognized. Also, the ineffective area UA disposed adjacent to the effective area AA may be an area in which a fingerprint is not recognized.

In detail, when a finger approaches or contacts the effective area AA, a fingerprint may be recognized by ultrasonic waves transmitted and received in the effective area. The driving principle of the fingerprint sensor will be described in detail below.

The first electrode 210 and the second electrode 220 may be disposed on the piezoelectric layer 300 . For example, the first electrode 210 and the second electrode 220 may be disposed on at least one of one surface of the piezoelectric layer 300 and the other surface opposite to the one surface.

1 and 2 , the first electrode 210 is disposed on one surface of the piezoelectric layer 300 , and the second electrode 320 is disposed on the other surface of the piezoelectric layer 300 . can That is, the first electrode 210 may be disposed between the substrate 100 and the piezoelectric layer 300 .

At least one of the first electrode 210 and the second electrode 220 may include a conductive material.

For example, at least one of the first electrode 210 and the second electrode 220 may include a transparent conductive material. For example, at least one of the first electrode 210 and the second electrode 320 may include indium tin oxide, indium zinc oxide, copper oxide, or tin. It may include a metal oxide such as tin oxide, zinc oxide, or titanium oxide.

Alternatively, at least one of the first electrode 210 and the second electrode 220 may be a nanowire, a photosensitive nanowire film, a carbon nanotube (CNT), graphene, a conductive polymer, or a mixture thereof. may include.

Alternatively, at least one of the first electrode 210 and the second electrode 220 may include various metals. For example, at least one of the first electrode 210 and the second electrode 220 may be silver chromium (Cr), nickel (Ni), copper (Cu), aluminum (Al), or silver (Ag). , molybdenum (Mo). At least one of gold (Au), titanium (Ti), and alloys thereof may be included.

At least one of the first electrode 210 and the second electrode 220 may be formed in a mesh shape. For example, at least one of the first electrode 210 and the second electrode 220 may be formed in a mesh shape by sub-electrodes crossing each other.

The first electrode 210 and the second electrode 220 may have a mesh line width of about 0.1 μm to about 10 μm. A mesh wire having a width of less than about 0.1 μm may be impossible due to a manufacturing process, or a short circuit of the mesh wire may occur. Preferably, the line width of the mesh line LA may be about 0.5 μm to about 7 μm. More preferably, the line width of the mesh wire may be about 1㎛ to about 3.5㎛.

The first electrode 210 and the second electrode 220 may be disposed in a mesh shape by various methods.

For example, an electrode material constituting the first electrode 210 and the second electrode 220, for example, a metal layer such as copper (Cu) is disposed on at least one surface of the piezoelectric layer 300, By etching the metal layer in a mesh shape, the mesh-like first electrode and the second electrode may be formed.

Alternatively, a base substrate, for example, a resin layer is disposed on at least one surface of the piezoelectric layer 300, and an engraved or embossed pattern is formed on the resin layer by using an embossed or engraved mold, and then the pattern By filling and curing a metal paste containing at least one metal among Cr, Ni, Cu, Al, Ag, Mo, and alloys thereof, the first electrode and the second electrode having an intaglio or embossed mesh shape are formed can do.

The first electrode 210 and the second electrode 3220 may be connected to a wiring electrode disposed on the ineffective area UA. The wiring electrode may be connected to a printed circuit board (not shown) disposed on at least one of the effective area AA and the non-effective area UA.

The first electrode 210 and the second electrode 220 may be disposed to cross each other. In detail, the first electrode 210 includes at least one first electrode pattern 211 extending in one direction, and the second electrode 220 includes at least one second electrode pattern 211 extending in a direction different from the one direction. A two-electrode pattern 221 may be included.

1 and 2 show that the first electrode pattern 211 and the second electrode pattern 221 are formed in a bar pattern, the embodiment is not limited thereto, and the first electrode pattern ( 211) and the second electrode pattern 221 may be formed in a pattern of various shapes, such as a polygon such as a square, a diamond, a pentagon, or a hexagon, or a circle.

Accordingly, the first electrode 320 and the second electrode 220 extend in different directions, and in an intersection region where the first electrode pattern 211 and the second electrode pattern 221 intersect, a node A region N may be formed.

In the node region N, a signal may be transmitted or received by an object approaching or coming into contact with the piezoelectric layer 400 direction. In detail, the node region N may transmit and receive an ultrasound signal. That is, the node region N may be a sensor that recognizes a fingerprint according to the approach or contact of a finger.

At least one node region N may be formed on the piezoelectric layer 200 . In detail, a plurality of the node regions N may be formed on the piezoelectric layer 200 . For example, the node region N may be formed with a resolution of about 400 dpi to about 500 dpi with respect to the piezoelectric layer 200 .

Accordingly, the interval between the node regions N may be about 100 μm or less. For example, the node region N may include a first node region N1 and a second node region N2 adjacent to each other, and the first node region N and the second node region ( N2) may be spaced apart at an interval of about 100 μm or less.

For example, at least one of a first interval of the first electrode patterns 311 forming the node region N and a second interval of the second electrode patterns 321 is about 100 μm or less, in detail, They may be spaced apart at intervals of about 70 μm or less, more specifically, about 50 μm or less.

When the interval between the node regions N exceeds about 50 μm, the resolution of the node regions N may be lowered, and accordingly, the ultrasonic wave signal transmitted and received in the node regions N is weak, so that a fingerprint is generated. Since it cannot be accurately recognized, the reliability of the fingerprint sensor may be deteriorated.

The node region N may simultaneously serve to transmit and receive an ultrasound signal. In detail, when a finger touches or approaches, an ultrasound signal may be transmitted in the direction of the finger in the node region N, and ultrasound signals reflected from the finger may be received back to the node region N. The fingerprint sensor according to the embodiment may recognize a fingerprint of a finger due to a signal difference between transmission and reception.

3 is a view for explaining the operation of the fingerprint sensor according to the touch or approach of a finger.

Referring to FIG. 3 , a voltage having a resonance frequency of an ultrasonic band is applied to the first electrode 210 and the second electrode 220 disposed on one surface and the other surface of the piezoelectric layer 200 from an external control unit, An ultrasonic signal may be generated in 400 .

When a finger or the like does not touch or approach such an ultrasonic signal, due to a difference in acoustic impedance between the air and the node region N of the piezoelectric layer 400 from which the ultrasonic signal is emitted, the node region of the piezoelectric layer 300 ( Most of the ultrasonic signals transmitted from N) do not pass through the interface between the piezoelectric sensor 200 and air and return to the inside of the piezoelectric layer 300 .

On the other hand, when a finger touches or approaches as shown in FIG. 3 , a part of the ultrasound signal transmitted from the node region N of the piezoelectric layer 300 penetrates the interface between the skin of the finger and the piezoelectric layer 300 and enters the inside of the finger. As a result, the intensity of the reflected and returned signal is lowered, so that the fingerprint pattern can be detected from it.

Although it is difficult to confirm with the naked eye, the fingerprint of the finger may have a pattern in which numerous valleys and ridges are repeated, and there may be a difference in height as the valleys and ridges are repeated. Accordingly, as shown in FIG. 3 , the piezoelectric layer 300 does not directly contact the skin in the valley 610 of the fingerprint, and the piezoelectric layer 300 may directly contact the skin in the ridge 620 of the fingerprint. .

Accordingly, in the ultrasonic signal transmitted from the node region N of the piezoelectric layer 300 corresponding to the valley 610 of the fingerprint, only a very small signal is emitted to the outside, and most of the ultrasonic signal is reflected inside the node. An ultrasonic signal that is received back to the region N and emitted from the node region N of the piezoelectric layer 400 corresponding to the crest 620 of the fingerprint passes through the finger interface, travels, and is reflected back to the node region ( N), the intensity of the received ultrasound signal is relatively significantly reduced.

Accordingly, the fingerprint pattern of the finger is detected by measuring the intensity or reflection coefficient of the reflected signal received by the ultrasonic signal generated from the acoustic impedance difference according to the valley 610 and the ridge 620 of the fingerprint in each node region N. can do.

4 to 6 , an intermediate layer 400 may be disposed on the piezoelectric layer 300 . A pattern may be formed on at least one surface of the intermediate layer 400 .

For example, the intermediate layer 400 may include one surface 401 and the other surface 402 opposite to the one surface 401 . In detail, the intermediate layer 400 may include one surface 401 in direct or indirect contact with the piezoelectric layer 300 and the other surface 402 in direct or indirect contact with the cover substrate 500 .

A plurality of protrusions may be disposed on at least one of the first surface 401 and the other surface 402 of the intermediate layer 400 .

Referring to FIG. 4 , protrusions 450 may be disposed only on one surface 401 of the intermediate layer 400 . That is, the protrusions 450 may be disposed on one surface 401 that is an interface between the intermediate layer 400 and the piezoelectric layer 300 .

Alternatively, referring to FIG. 5 , the protrusions 450 may be disposed only on the other surface 402 of the intermediate layer 400 . That is, the protrusions 450 may be disposed on the other surface 402 that is the interface between the intermediate layer 400 and the cover substrate 500 .

Alternatively, referring to FIG. 6 , protrusions 450 may be disposed on one surface 401 and the other surface 402 of the intermediate layer 400 . That is, protrusions 450 are formed on one surface 401 that is an interface between the intermediate layer 400 and the piezoelectric layer 300 and the other surface 402 that is an interface between the intermediate layer 400 and the cover substrate 500 . can be placed.

The protrusion 450 may include at least one of a flat surface and a curved surface. For example, the protrusion 450 may have a curved surface as a whole and may have a circular or elliptical shape. Alternatively, the protrusion 450 may include a flat surface as a whole, and may include a polygonal shape such as a quadrangle or a triangle. Alternatively, the protrusion 450 may include a complex shape partially having a flat surface and partially having a curved surface.

The protrusion 450 may include a first sub protrusion 451 and a second sub protrusion 452 spaced apart from each other and disposed to be spaced apart from each other. The first sub-protrusion 451 and the second sub-protrusion 452 may have the same or similar shape. Alternatively, the first sub-protrusion 451 and the second sub-protrusion 452 may have different shapes.

The first sub-protrusion 451 and the second sub-protrusion 452 may be disposed at the same, similar or different heights. For example, the height h1 of the first sub-protrusion 451 and the height h2 of the second sub-protrusion 452 are the same, similar, or different from each other at a height of about 50 nm to about 200 nm. It can be placed at a height.

When the height h1 of the first sub-protrusion 451 and the height h2 of the second sub-protrusion 452 are less than about 50 nm or more than about 200 nm, grating according to the protrusion effectiveness may be reduced.

In addition, the first sub-protrusion 451 and the second sub-protrusion 452 may be disposed to be spaced apart from each other by a predetermined interval or a pitch. For example, a distance or pitch between the first sub-projection 451 and the second sub-projection 452 may be smaller than a wavelength of an acoustic impedance of a transmitted or received ultrasound signal. In detail, a pitch p of the first sub-protrusion 451 and the second sub-protrusion 452 may be about 50 nm to about 200 nm.

When the pitch p between the first sub-protrusion and the second sub-protrusion 452 is less than about 50 nm or greater than about 200 nm, a grating effect according to the protrusion may be reduced.

The intermediate layer 400 and the protrusion 450 may include a transparent or translucent material. Preferably, the intermediate layer 400 and the protrusion 450 may include a transparent material.

In addition, the intermediate layer 400 and the protrusion 450 may include a resin. For example, the intermediate layer 400 and the protrusion 450 may include a resin-based material such as Optically Clear Adhesive (OCA), Liquid-Optically Clear Adhesive (LOCA), or Optically Clear Resin (OCR).

The piezoelectric layer 300 , the intermediate layer 400 , and the cover substrate 500 may have different acoustic impedance values. For example, acoustic impedance values of the piezoelectric layer 300 , the intermediate layer 400 , and the cover substrate 500 may satisfy Equation 1 below.

[Formula 1]

Acoustic impedance value of piezoelectric layer < Acoustic impedance value of intermediate layer < Acoustic impedance value of cover substrate

When the acoustic impedance values of the piezoelectric layer 300 , the intermediate layer 400 , and the cover substrate 500 deviate from Equation 1 above, the piezoelectric layer 300 in the direction of the cover substrate 500 or the cover substrate Since the ultrasonic signal transmitted or received in the direction of the piezoelectric layer 400 in 500 does not move smoothly, the efficiency of the fingerprint sensor may be reduced.

The cover substrate 500 may be disposed on the intermediate layer 400 . The cover substrate 500 may include the same or similar material to the substrate 100 described above.

The fingerprint sensor according to the first embodiment may include an intermediate layer including a plurality of protrusions. Accordingly, it is possible to smoothly move the ultrasonic signal transmitted from the piezoelectric layer toward the cover substrate or received from the cover substrate toward the piezoelectric layer.

The acoustic impedance value may be defined as a density and ultrasonic velocity value in a material, that is, an intermediate layer disposed between the piezoelectric layer and the cover substrate mitigates the difference in the acoustic impedance values of the piezoelectric layer and the cover substrate, so that the piezoelectric An ultrasonic signal transmitted from the layer to the cover substrate or received from the cover substrate to the piezoelectric layer may be smoothly moved.

In addition, when the wavelength of an ultrasonic signal having a wavelength larger than that of the protrusion pattern by forming a protrusion pattern on at least one of the one surface and the other surface of the intermediate layer passes through the intermediate layer, the effect such that the acoustic impedance gradually changes due to the protrusion can have

Therefore, even when the intermediate layer is formed as a single layer, as the acoustic impedance values of the piezoelectric layer and the cover substrate are changed stepwise by the intermediate layer, the ultrasonic signal transmitted or received smoothly moves to realize a thin thickness while implementing a fingerprint The efficiency of the sensor can be improved.

Hereinafter, a fingerprint sensor according to a second embodiment will be described with reference to FIGS. 7 to 12 . In the description of the fingerprint sensor according to the second embodiment, descriptions that are the same as or similar to those of the fingerprint sensor according to the first embodiment described above will be omitted. In addition, the same reference numerals are assigned to the same components as those of the first embodiment.

Referring to FIG. 7 , the fingerprint sensor according to the second embodiment may include a first intermediate layer 410 and a second intermediate layer 420 . In detail, the fingerprint sensor according to the second embodiment may include a first intermediate layer 410 disposed on the second electrode 220 and a second intermediate layer 420 disposed on the first intermediate layer 410 . can

Also, at least one of the first intermediate layer 410 and the second intermediate layer 420 may include a plurality of protrusions.

Referring to FIG. 8 , the first intermediate layer 410 may include a plurality of first protrusions 431 . For example, in the first intermediate layer 410 , the first protrusions 431 may be disposed on one surface 411 of the first intermediate layer 410 and the piezoelectric layer 300 facing each other.

Alternatively, referring to FIG. 9 , the second intermediate layer 420 may include a plurality of second protrusions 432 . For example, in the second intermediate layer 420 , the second protrusions 432 may be disposed on a surface 421 where the second intermediate layer 420 and the cover substrate 500 face each other.

Alternatively, referring to FIG. 10 , the first intermediate layer 410 or the second intermediate layer 420 may include a plurality of protrusions 430 . For example, the other surface 412 opposite to the one surface 411 of the first intermediate layer 410 and the other surface 421 opposite to the one surface 421 of the second intermediate layer 420 have a plurality of protrusions 430 . can be placed.

Also, referring to FIGS. 11 to 13 , protrusions may be respectively disposed on the first intermediate layer 410 and the second intermediate layer 420 .

For example, referring to FIG. 11 , first protrusions 431 are disposed on one surface 411 of the first intermediate layer 410 , and the second protrusions 421 are disposed on one surface 421 of the second intermediate layer 420 . 432 may be disposed.

Alternatively, referring to FIG. 12 , first protrusions 431 are disposed on one surface 411 of the first intermediate layer 410 , and the second protrusions 432 are disposed on the other surface 422 of the second intermediate layer 420 . ) can be placed.

Alternatively, referring to FIG. 13 , first protrusions 431 are disposed on the other surface 411 of the first intermediate layer 410 , and the second protrusions 432 are disposed on one surface 421 of the second intermediate layer 420 . ) can be placed.

The first protrusion 431 and the second protrusion 432 may be disposed to overlap each other. Alternatively, the first protrusion 431 and the second protrusion 432 may be disposed at positions that do not overlap each other. That is, the first protrusion 431 and the second protrusion 432 may be alternately disposed, that is, alternately disposed.

The acoustic impedance values of the first intermediate layer 410 and the second intermediate layer 420 may satisfy Equation 2 below.

[Formula 2]

The acoustic impedance value of the second intermediate layer < the acoustic impedance value of the first intermediate layer

When the acoustic impedance values of the first intermediate layer 410 and the second intermediate layer 420 deviates from Equation 2, the piezoelectric layer 300 toward the cover substrate 500 or in the cover substrate 500 Since the ultrasonic signal transmitted or received in the direction of the piezoelectric layer 400 does not move smoothly, the efficiency of the fingerprint sensor may be reduced.

In addition, acoustic impedance values of the cover substrate 500 , the first intermediate layer 410 , the second intermediate layer 420 , and the piezoelectric layer 300 may satisfy Equation 3 below.

[Equation 3]

Acoustic impedance value of the piezoelectric layer < Acoustic impedance value of the second intermediate layer < Acoustic impedance value of the first intermediate layer < Acoustic impedance value of the cover substrate

When the acoustic impedance values of the cover substrate 500 , the first intermediate layer 410 , the second intermediate layer 420 , and the piezoelectric layer 300 deviate from Equation 3 above, the piezoelectric layer 300 forms the cover substrate (500) direction or the ultrasonic signal transmitted or received from the cover substrate 500 to the piezoelectric layer 400 direction does not move smoothly, so that the efficiency of the fingerprint sensor may be reduced.

Also, a height of at least one of the first protrusions 431 and the second protrusions 432 may be about 50 nm to about 200 nm.

In addition, the first protrusions 431 are spaced apart from each other at a first interval, and the second protrusions 432 are spaced apart from each other at a second interval, and in this case, at least one of the first interval and the second interval. The spacing of the may be about 50 nm to about 200 nm.

The fingerprint sensor according to the second embodiment may include a plurality of intermediate layers including a plurality of protrusions. Accordingly, it is possible to smoothly move the ultrasonic signal transmitted from the piezoelectric layer toward the cover substrate or received from the cover substrate toward the piezoelectric layer.

In detail, by forming a multi-layered intermediate layer that mitigates the difference in acoustic impedance values, and arranging protrusions for buffering the acoustic impedance values in stages on at least one of the respective layers, from the piezoelectric layer to the cover substrate direction An ultrasonic signal transmitted or received from the cover substrate to the piezoelectric layer may be smoothly moved.

Therefore, by changing the acoustic impedance values of the piezoelectric layer and the cover substrate in stages by the intermediate layers, it is possible to improve the efficiency of the fingerprint sensor while implementing a thin thickness by smoothing the movement of the transmitted or received ultrasonic signal. .

Hereinafter, with reference to FIGS. 14 and 15 , fingerprint sensors of various embodiments according to the arrangement positions of electrodes will be described.

Referring to FIG. 14 , the first electrode 210 may be disposed on the cover substrate 500 , and the second electrode 220 may be disposed on the piezoelectric layer.

For example, the first electrode 210 is disposed on the intermediate layer 400 including the above-described protrusions disposed on the cover substrate 500 , and the second electrode 220 is disposed on the piezoelectric layer ( 300 ) and the substrate 100 .

Alternatively, referring to FIG. 15 , the first electrode 210 and the second electrode 220 may be disposed on the substrate 100 . For example, the first electrode 210 and the second electrode 220 may be disposed on the same surface of the substrate 100 .

The fingerprint sensor according to the embodiments may be applied to a locking device. For example, the fingerprint sensor according to the embodiments may be applied as a locking device by being applied to an electronic product or the like.

In detail, as shown in FIG. 16 , the fingerprint sensor according to the embodiments may be coupled to a door lock and applied as a locking device of the door lock. Alternatively, it may be combined with a mobile phone as shown in FIG. 17 and applied to a locking device of the mobile phone.

Alternatively, the fingerprint sensor according to the embodiments may be applied to a power supply device. For example, the fingerprint sensor according to the embodiments may be applied to home appliances, vehicles, and the like.

In detail, as shown in FIG. 18 , it may be applied as a power supply by being coupled to a home appliance such as an air conditioner. Alternatively, as shown in FIG. 19 , it may be applied to a vehicle, etc., and may be applied to a power supply device such as a vehicle starting device and a car audio system.

Features, structures, effects, etc. described in the above-described embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiments have been described above, these are merely examples and do not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiments may be implemented by modification. And the differences related to these modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Claims (14)

Board;
a first electrode on the substrate;
a piezoelectric layer on the first electrode;
a second electrode on the piezoelectric layer;
an intermediate layer on the second electrode; and
a cover substrate on the intermediate layer;
The intermediate layer includes a plurality of protrusions disposed on at least one surface of one surface and the other surface of the intermediate layer,
The protrusion includes a first sub protrusion and a second sub protrusion spaced apart from each other,
The height of the first sub-projection and the second sub-projection is 50 nm to 200 nm,
An interval between the first sub-projection and the second sub-projection is 50 nm to 200 nm,
The intermediate layer and the protrusion include an optically clear adhesive (OCA), a liquid-optically clear adhesive (LOCA), or an optically clear resin (OCR). delete delete The method of claim 1,
The acoustic impedance values of the cover substrate, the intermediate layer, and the piezoelectric layer satisfy Equation 1 below.
[Formula 1]
Acoustic impedance value of piezoelectric layer < Acoustic impedance value of intermediate layer < Acoustic impedance value of cover substrate The method of claim 1,
The middle layer is a transparent or translucent fingerprint sensor. The method of claim 1,
The protrusion includes at least one of a flat surface and a curved surface. Board;
a first electrode on the substrate;
a piezoelectric layer on the first electrode;
a second electrode on the piezoelectric layer;
an intermediate layer on the second electrode; and
a cover substrate on the intermediate layer;
The intermediate layer is
The intermediate layer may include a first intermediate layer disposed on the second electrode; and
a second intermediate layer on the first intermediate layer;
At least one intermediate layer of the first intermediate layer and the second intermediate layer includes a plurality of protrusions,
The first intermediate layer includes a plurality of first protrusions disposed on at least one surface of one surface and the other surface of the first intermediate layer,
The second intermediate layer includes a plurality of second protrusions disposed on at least one surface of one surface and the other surface of the second intermediate layer,
The height of at least one of the first protrusion and the second protrusion is 50 nm to 200 nm,
The first protrusions are spaced apart from each other at a first interval,
The second protrusions are spaced apart from each other at a second interval,
At least one of the first interval and the second interval is 50 nm to 200 nm,
The first intermediate layer, the second intermediate layer, the first protrusion and the second protrusion may include optically clear adhesive (OCA), liquid-optically clear adhesive (LOCA), or optically clear resin (OCR). delete 8. The method of claim 7,
The first protrusion and the second protrusion are disposed at positions overlapping each other. 8. The method of claim 7,
The first protrusion and the second protrusion are disposed at positions alternate with each other. 8. The method of claim 7,
The acoustic impedance values of the first intermediate layer and the second intermediate layer satisfy Equation 2 below.
[Formula 2]
The acoustic impedance value of the second intermediate layer < the acoustic impedance value of the first intermediate layer 8. The method of claim 7,
The acoustic impedance values of the cover substrate, the first intermediate layer, the second intermediate layer, and the piezoelectric layer satisfy Equation 3 below.
[Equation 3]
Acoustic impedance value of the piezoelectric layer < Acoustic impedance value of the second intermediate layer < Acoustic impedance value of the first intermediate layer < Acoustic impedance value of the cover substrate delete delete

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