TWI621982B - Fingerprint identification device, manufacturing method thereof and display device - Google Patents

Abstract

A fingerprint identification device includes a cover sheet, a shielding layer, a conductive connection layer, a piezoelectric material layer, and a signal transmitting unit that are sequentially stacked in a layer. A surface of the cover sheet away from the shielding layer is a touch surface The conductive connection layer is sandwiched between the cover plate and the piezoelectric material layer and the cover plate and the piezoelectric material layer are bonded together; the conductive connection layer and the piezoelectric material The layer constitutes a signal receiving unit. The invention also provides a display device using the fingerprint identification device and a method for manufacturing the fingerprint identification device.

Description

Fingerprint recognition device, manufacturing method thereof, and display device

The invention relates to a fingerprint recognition device and a manufacturing method thereof.

In recent years, electronic devices such as smartphones and tablets often use fingerprint recognition devices to implement functions such as data protection, identity authentication, and program control. Fingerprint recognition devices can be divided into optical, capacitive, and sonic. Among them, the sonic fingerprint recognition device is widely used because it is not easily affected by the ambient temperature and humidity, and has the advantages of long life and high resolution.

When using a sonic fingerprint recognition device for fingerprint detection, a finger is placed on the detection surface of the sonic fingerprint recognition device, and the ultrasonic waves sent to the finger are absorbed and the other part is reflected. Because the media at the finger's fingerprint valley and ridge are air and finger skin, respectively, the absorption and reflectance of ultrasonic waves are different, so the difference can be used to generate a series of electrical signals corresponding to the fingerprint valley and ridge, and finally form an image corresponding to the shape of the fingerprint .

A conventional fingerprint recognition device generally includes a cover sheet, a signal receiving unit, a signal transmitting unit, a thin film transistor array substrate, and a flexible circuit board, which are sequentially stacked in order. The cover sheet is then passed through an adhesive. Bonding with the signal receiving unit. The cover sheet is usually coated with a masking ink layer and a color ink layer. When a finger touches the surface of the cover sheet, the ultrasonic wave emitted by the signal transmitting unit passes through the thin film transistor array substrate, the signal receiving unit, The adhesive, the masking ink layer, the color ink layer, and the cover sheet reach contact The surface is reflected, and then passes through the cover sheet, the masking ink layer, the color ink layer, and the adhesive in sequence and is received by the signal receiving unit. It has been found that the ultrasonic transmission path is too long, and each layer of dielectric material on the transmission path will absorb the ultrasonic waves, resulting in excessive attenuation of the ultrasonic signals, which greatly affects the fingerprint detection accuracy of the sonic fingerprint recognition device.

In view of this, it is necessary to provide a fingerprint recognition device with higher fingerprint detection accuracy and a manufacturing method thereof.

A fingerprint identification device includes a cover sheet, a shielding layer, a conductive connection layer, a piezoelectric material layer, and a signal transmitting unit that are sequentially stacked in a layer. A surface of the cover sheet away from the shielding layer is a touch surface The conductive connection layer is sandwiched between the cover plate and the piezoelectric material layer and the cover plate and the piezoelectric material layer are bonded together; the conductive connection layer and the piezoelectric material The layer constitutes a signal receiving unit.

A method for manufacturing a fingerprint recognition device includes: providing a cover sheet, the cover sheet having a touch surface, and forming a shielding layer and a semi-cured conductive connection in sequence on a surface of the cover sheet away from the touch surface. Material, the material of the conductive connection layer has curability; a piezoelectric material layer is provided, which is adhered to the semi-cured conductive connection material and the conductive connection material is cured to form a conductive connection layer.

Compared with the conventional technology, the present invention utilizes the characteristic that the conductive connection material with curing properties changes from a semi-cured state to a solid state during the curing process, and the piezoelectric material layer is bonded to form a signal receiving unit. The piezoelectric material layers are glued together, so that the conductive connection material simultaneously serves as the color ink layer and the electrode layer of the signal receiving unit in the prior art fingerprint identification device, and at the same time, a layer of adhesive is omitted, which effectively shortens the ultrasonic transmission path , Which effectively reduces Less sonic signal attenuation, improving the accuracy of fingerprint detection by the sonic fingerprint recognition device; meanwhile, the process is simplified and the process cost is reduced.

10‧‧‧Fingerprint recognition device

110‧‧‧ cover slip

111‧‧‧contact surface

120‧‧‧Signal receiving unit

121‧‧‧ conductive connection layer

122‧‧‧first piezoelectric material layer

130‧‧‧ thin film transistor array substrate

140‧‧‧Signal transmission unit

141‧‧‧first electrode layer

143‧‧‧Second electrode layer

142‧‧‧Second piezoelectric material layer

150‧‧‧flexible circuit board

170‧‧‧Adhesive

20‧‧‧ display device

210‧‧‧ Cover

211‧‧‧display area

212‧‧‧non-display area

FIG. 1 is a schematic diagram of an electronic device with a fingerprint recognition device according to an embodiment of the invention.

FIG. 2 is a schematic cross-sectional view of a fingerprint identification device according to a preferred embodiment of the present invention.

FIG. 3 is a flowchart of a method for manufacturing a fingerprint recognition device according to an embodiment of the present invention.

FIG. 1 is a schematic diagram of a display device 20 to which a fingerprint identification device 10 according to a preferred embodiment of the present invention is applied. The display device 20 includes a transparent cover 210 having a display area 211 for displaying a picture and a non-display area 212 surrounding the display area 211. The fingerprint identification device 10 is disposed in the non-display area 212. The display device 20 may be a smart phone, a tablet computer, or the like.

Please refer to FIG. 2 together. FIG. 2 is a cross-sectional view of the fingerprint identification device 10 along line II-II in FIG. 1. The fingerprint identification device 10 includes a cover sheet 110, a shielding layer 190, a conductive connection layer 121, a first piezoelectric material layer 122, a thin film transistor array substrate 130, a signal transmitting unit 140, and a Flexible circuit board 150. The cover sheet 110 is coplanar with the cover plate 210. The surface of the cover sheet 110 away from the conductive connection layer 121 is the contact surface 111 for fingerprint identification operation.

The material of the cover sheet 110 may be selected from glass, Polymethyl Methacrylate (PMMA), Sapphire, Polyethersulfone Resin (PES), and Polyethylene Terephthalate. , PET) and so on.

The material of the masking layer 190 may be ink or paint, and the masking layer 190 is used to mask the first piezoelectric material layer 122 and the layers below it, so as to realize the aesthetics of the fingerprint identification device 10. In order to print ICON (illustration), the masking layer 190 is a patterned junction. The portion of the cover sheet 110 that is not covered by the shielding layer 190 is covered by the conductive connection layer 121.

The material of the conductive connection layer 121 is a conductive material with curable properties, and its sheet resistance is less than 50 mΩ / sq. The conductive connection layer 121 adheres the cover sheet 110 and the first piezoelectric material layer 122. At the same time, the conductive connection layer 121 functions as an electrode layer, and cooperates with the first piezoelectric material layer 122 to form the signal receiving unit 120 of the fingerprint identification device. In this embodiment, a material of the conductive connection layer 121 is a conductive ink. In other embodiments, a material of the conductive connection layer 121 may be a conductive carbon paste, a conductive silver paste, or the like. In order to print the ICON, the conductive connection layer 121 may also be of different colors.

The first piezoelectric material layer 122 and the thin film transistor array substrate 130 are bonded by an adhesive 170, and the thin film transistor array substrate 130 and the signal transmitting unit 140 are bonded by the adhesive 170. The first electrode layer 141 is bonded, and the second electrode layer 143 of the signal transmitting unit 140 and the flexible circuit board 150 are bonded by an adhesive 170.

The material of the first piezoelectric material layer 122 and the second piezoelectric material layer 142 may be one or a combination of the following materials: Polyvinylidene Fluoride (PVDF), barium titanate, Lead titanate, lead zirconate titanate (PZT), lead tantalate (PST), quartz and copolymers of vinylidene fluoride and trifluoroethylene.

The signal transmitting unit 140 includes a first electrode layer 141, a second piezoelectric material layer 142, and a second electrode layer 143, which are sequentially stacked.

The flexible circuit board 150 is electrically connected to the second electrode layer 143; at the same time, one end of the flexible circuit board 150 extends and surrounds the conductive connection layer 121 and the along the side of the fingerprint identification device 10. The thin film transistor array substrate 130 is electrically connected.

The first electrode layer 141 and the second electrode layer 143 may be made of a metal material with good conductivity, for example, a high-conductivity material such as aluminum, copper, nickel, and gold, or may be made of transparent oxygen. Made of conductive materials such as indium tin oxide, indium zinc oxide, silver, carbon nanotubes or graphene, but not limited to the above materials.

The thickness of the adhesive 170 is less than 5 microns. Preferably, the adhesive is an epoxy-based adhesive.

When the fingerprint identification device 10 is in operation, an external circuit (not shown) applies a voltage to the first electrode layer 141 and the second electrode layer 143 of the signal transmitting unit 140 through the flexible circuit board 150 so that the two An electric field is formed therebetween, and the second piezoelectric material layer 142 generates vibration and emits an ultrasonic signal under the action of the electric field. The ultrasonic signal passes through the signal receiving unit 120 and reaches the contact surface 111 of the cover sheet 110 and passes through the contact surface 111. After the reflection forms a reflection signal, it is received by the signal receiving unit 120. When there is a finger touch on the contact surface 111, because the fingerprint ridge and the fingerprint valley have different reflectivity to ultrasonic waves, the signals transmitted by the ultrasonic wave transmitted to the contact surface 111 at the fingerprint ridge and the fingerprint valley are different. The reflected signal is received by the signal receiving unit 120, the first piezoelectric material layer 122 generates electric charges under the action of the reflected ultrasonic signal, and the first thin film transistor array substrate 130 senses the electric charges and converts the electric charges into electric The signal is transmitted to an external circuit (not shown) through the flexible circuit board 150.

In this embodiment, the signal receiving unit 120 is formed by bonding the conductive material having a curing property from a semi-cured state to a solid state during the curing process, and bonding the piezoelectric material layer 122 to form the signal receiving unit 120. The piezoelectric material layer 122 is glued together, so that the conductive connection material simultaneously serves as the color ink layer and the electrode layer of the signal receiving unit in the fingerprint recognition device of the prior art, while eliminating a layer of adhesive and effectively shortening the ultrasonic wave. The transmission path further reduces the attenuation of the acoustic signal, improves the accuracy of fingerprint detection by the fingerprint identification device 10, and simplifies the process and reduces the process cost.

The present invention provides a method for manufacturing the fingerprint identification device 10 in the above embodiment. Please refer to FIG. 3. The manufacturing method includes the following steps:

In step S301, a cover sheet 110 is provided. The cover sheet has a touch surface 111. On the surface of the cover sheet 110 away from the touch surface 111, a patterned shielding layer 190 and a semi-cured conductive layer are sequentially formed. Connection material. Portions of the cover sheet 110 that are not covered by the shielding layer 190 are covered by the conductive connection material.

The material of the cover sheet 110 may be selected from glass, Polymethyl Methacrylate (PMMA), Sapphire, Polyethersulfone Resin (PES), and Polyethylene Terephthalate. , PET) and so on.

The conductive connection material is a conductive material having a curing property. In this embodiment, the conductive connection material is a conductive ink. In other embodiments, the conductive connection material may be a conductive carbon paste, a conductive silver paste, or the like.

In step S302, a first piezoelectric material layer 122 is provided, the first piezoelectric material layer 122 is adhered to the semi-cured conductive connection material and the conductive connection material is cured to form a conductive connection layer 121, and The first piezoelectric material layer 122 and the conductive connection layer 121 are closely adhered to form a signal receiving unit 120. The square resistance of the conductive connection layer 121 is less than 50 mΩ / sq.

The material of the piezoelectric material layer 122 may be Polyvinylidene Fluoride (PVDF), barium titanate, lead titanate, lead zirconate titanate (PZT), lead tantalate (PST), quartz, and Copolymer of difluoroethylene and trifluoroethylene.

In step S303, a thin-film transistor array substrate 130 is provided, and the thin-film transistor array substrate 130 is bonded to the first piezoelectric material layer 122 through an adhesive layer 170.

In step S304, a signal transmitting unit 140 is provided. The signal transmitting unit 140 includes a first electrode layer 141, a second piezoelectric material layer 142, and a second electrode layer 143, which are stacked in this order. The first electrode layer 141 is bonded to the thin film transistor array substrate 130 through an adhesive layer 170.

In step S305, a flexible circuit board 150 is provided, and the flexible circuit board 150 is bonded by the adhesive layer 170; the flexible circuit board 150 and the second electrode layer 143 are electrically connected, and the flexibility One end of the circuit board 150 extends and surrounds the side of the fingerprint identification device 10 to be electrically connected with the conductive connection layer 121 and the thin film transistor array substrate 130.

In this embodiment, the signal receiving unit 120 is formed by bonding the conductive connection material with a curing property from a semi-cured state to a solid state during curing to form the signal receiving unit 120, thereby eliminating the need for the conductive connection layer. An additional adhesive is provided between 121 and the first piezoelectric material layer 122, eliminating an adhesive layer; at the same time, the conductive connection layer 121 serves as an electrode of the signal receiving unit 120, which effectively shortens the ultrasonic transmission Path, thereby effectively reducing the attenuation of acoustic signals and improving the accuracy of fingerprint detection by the fingerprint identification device 10; meanwhile, the process is simplified and the process cost is reduced.

Claims (9)

A fingerprint identification device includes a cover sheet, a shielding layer, a conductive connection layer, a piezoelectric material layer, and a signal transmitting unit that are sequentially stacked in a layer. A surface of the cover sheet away from the shielding layer is a touch surface. The improvement is that the conductive connection layer is sandwiched between the cover plate and the piezoelectric material layer and the cover plate and the piezoelectric material layer are bonded together, and the conductive connection layer and the piezoelectric material layer are bonded together. The piezoelectric material layer constitutes a signal receiving unit, and the material forming the conductive connection layer has conductivity and curability. The fingerprint identification device of claim 1, wherein the fingerprint identification device is applied to a non-display area of a display device. The fingerprint identification device according to claim 1, wherein a square resistance of the conductive connection layer is less than 50 mΩ / sq. The fingerprint identification device according to claim 1, wherein the fingerprint identification device further comprises a thin film transistor array substrate and a flexible circuit board, the cover plate, the signal receiving unit, the thin film transistor array substrate, The signal transmitting units are sequentially stacked, and the thin film transistor array substrate is electrically connected to the signal transmitting unit; the flexible circuit board is electrically connected to the signal receiving unit and the signal transmitting unit. A display device is improved in that the fingerprint identification device according to any one of claims 1 to 4 is applied to a non-display area of the display device. A method for manufacturing a fingerprint identification device, which is improved, comprising: providing a cover sheet, the cover sheet having a touch surface, and forming a shielding layer and a semi-cured layer on the surface of the cover sheet away from the touch surface in order. State of the conductive connection material, the material of the conductive connection layer has curability; a piezoelectric material layer is provided, which is adhered to the semi-cured conductive connection material and the conductive connection material is cured to form a conductive material. Connection layer. The method for manufacturing a fingerprint identification device according to claim 6, further comprising: providing a thin film transistor array substrate and a signal transmitting unit, so that the thin film transistor array substrate is bonded to the piezoelectric material, and the signal transmitting unit Bonded to the thin film transistor array substrate. The method for manufacturing a fingerprint recognition device according to claim 6, further comprising: providing a flexible circuit board to make the signal transmitting unit of the flexible circuit board adhere, and making the flexible circuit board and the signal transmitting unit respectively, The conductive connection layer and the flexible circuit board are electrically connected. The method for manufacturing a fingerprint identification device according to claim 6, wherein the conductive connection material is conductive ink, conductive carbon, or conductive silver paste.