WO2017084003A1

WO2017084003A1 - Fingerprint system and mobile phone

Info

Publication number: WO2017084003A1
Application number: PCT/CN2015/094666
Authority: WO
Inventors: Shiwen HU; Hong Zhu; Yan LING
Original assignee: Shanghai Oxi Technology Co., Ltd
Priority date: 2015-11-16
Filing date: 2015-11-16
Publication date: 2017-05-26

Abstract

A fingerprint system and a mobile phone are provided. The fingerprint system includes: a sensor module which includes a sensor adapted for obtaining fingerprint signals, and a protection layer disposed on the sensor; a cover plate disposed above the sensor module, where the cover plate has a first opening exposing the protection layer; and a ground loop disposed around the protection layer. The ground loop can prevent the fingerprint system or the mobile phone from ESD damages.

Description

FINGERPRINT SYSTEM AND MOBILE PHONE

TECHNICAL FIELD

The present disclosure generally relates to imaging technology, and more particularly, to a fingerprint system and a mobile phone.

BACKGROUND

Fingerprint recognition technology can be used for personal identification or verification. Specifically, in a fingerprint recognition system, fingerprint images are captured by a fingerprint sensor. Thereafter, a matching process between the fingerprint images captured and templates stored in the system is performed, so as to determine if they are matching or not. Since the fingerprint recognition technology is kindly to user and fingerprint is distinctive, the fingerprint recognition technology is widely used in various applications, such as personal identification in policeman stations, physical access control in buildings, device access control in personal computers or mobile phones, and so on.

Generally, a conventional fingerprint system includes a sensor module and a cover plate. The cover plate has an opening exposing a top layer of the sensor module for finger touching. However, because there is always a gap between the cover plate and the sensor module, the fingerprint system can be easily damaged by Electrostatic Discharge (ESD) .

SUMMARY

In one embodiment, a fingerprint system is provided. The fingerprint system includes: a sensor module which includes a sensor adapted for obtaining fingerprint signals, and a protection layer disposed on the sensor； a cover plate disposed above the sensor module, where the cover plate has a first opening exposing the protection layer； and a ground loop disposed around the protection layer.

In some embodiments, the fingerprint system further includes: a flexible printed circuit (FPC) , wherein the FPC includes a first part and a second part, the first part of the FPC is disposed under the light guide plate, the second part of the FPC is disposed above the sensor and has a second opening exposing the protection layer of the sensor module.

In some embodiments, the ground loop is disposed on the second part of the FPC.

In some embodiments, the fingerprint system further includes: a touch detection electrode and a touch detection Integrated Circuit (IC) chip disposed on the second part of the FPC, wherein the touch detection electrode is electrically connected with the touch detection IC chip.

In some embodiments, the ground loop is disposed between the protection layer and the touch detection electrode.

In some embodiments, the ground loop is formed by a cladding process.

In some embodiments, the ground loop is made of metal wire or metal foil, and is pasted around the protection layer.

In some embodiments, the ground loop includes copper, tin, or iron.

In some embodiments, the ground loop has a circular shape, a square shape or a track shape.

In some embodiments, the sensor is an optical sensor, and the sensor module further includes: a light guide plate disposed below a bottom surface of the sensor； a light source disposed on one end of the light guide plate； and a readout IC chip connected with the sensor, wherein the readout IC chip is adapted for processing the fingerprint signals obtained by the sensor.

In some embodiments, the sensor is a capacitance sensor.

Correspondingly, in one embodiment of the present disclosure, a mobile phone is also provided. The mobile phone includes the fingerprint system described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

FIG. 1 schematically illustrates a structural diagram of a conventional fingerprint system；

FIG. 2 schematically illustrates a Flexible Printed Circuit (FPC) of the fingerprint system shown in FIG. 1；

FIG. 3 schematically illustrates a structural diagram of a fingerprint system according to one embodiment of the present disclosure；

FIG. 4 schematically illustrates a Flexible Printed Circuit (FPC) of the fingerprint system shown in FIG. 3；

FIG. 5 is a partial enlarged view of the fingerprint system shown in FIG. 3； and

FIG. 6 schematically illustrates a structural diagram of a mobile phone according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

Referring to FIG. 1, a structure diagram of an existing fingerprint system is illustrated. In a sensor module of the fingerprint system, a light guide plate 120 is used to guide lights emitted from a light source 140 to illuminate a protection layer 160. When a finger touches the top surface of the protection layer 160, light emitted from the light guide plate 120 penetrates through a sensor 110 and the protection layer 160, and reaches an interface between the finger and the top surface of the protection layer 160. Light reflection and refraction occur at the interface. The reflected light penetrates through the protection layer 160 and reaches the sensor 110. The sensor 110, which includes an array of pixels (not shown, e.g., photodiode or transistor) , implements photo-electronic conversion to the received reflected light. Thus, electronic signals proportional to the intensity of the reflected light can be obtained, based on which a fingerprint image of the finger can be generated. Then the electronic signals are processed by a readout IC chip 150, and are transmitted to a connection board 130. Generally, the connection board 130 is a Flexible Printed circuit (FPC) , and is bonded onto the sensor module by an FPC On Glass (FOG) process.

A structure diagram of the FPC 130 is illustrated in FIG. 2. The FPC 130 includes a first part 130a and a second part 130b. The first part 130a of the FPC 130 is disposed below the light guide plate 120, and the second part 130b of the FPC 130 is disposed above the sensor 110. The second part 130b of the FPC 130 has an opening 132 exposing the protection layer 160 of the sensor module. Generally, one or more touch detection electrodes 170 may be formed on the second part of the FPC. The touch detection electrode 170 is connected with an IC chip for detecting whether a finger touches the fingerprint system.

The fingerprint system shown in FIG. 1 further includes a cover plate 180. The cover plate 180 includes an opening exposing the protection layer of the fingerprint module. Due to assembly variations in the fabrication process, there is always a gap between cover plate 180 and the protection layer 160 of the fingerprint system. Because this gap place is always touched by a human finger, there may be Electrostatic Discharge (ESD) at this place, which may result in damages of the fingerprint system.

In order to solve the above problems, embodiments of the present disclosure disclose a fingerprint system. Referring to FIG. 3, the fingerprint system includes a sensor module, a cover plate 280 and a ground loop 290. The sensor module includes a sensor 210 adapted for obtaining fingerprint signals, and a protection layer 260 disposed on the sensor 210. The cover plate 280 is disposed above the sensor module, and has a first opening (not illustrated) exposing the protection layer 260. The ground loop 290 is disposed around protection layer 260. The ground loop 290 can transmit electrostatic charges to ground, and prevent the fingerprint system from ESD damage.

Specifically, the sensor module is adapted for obtaining fingerprint signals. A plurality of sensing devices and circuits may be formed on a top surface of the sensor 210. The plurality of sensing devices and circuits may be formed by amorphous silicon Thin Film Transistor (TFT) technology, or Low Temperature Poly Silicon (LTPS) TFT technology.

In some embodiments, the sensor 210 may be an optical sensor. A plurality of photodiodes are formed in the sensor 210. The plurality of photodiodes may be arranged in an array form, and can receive optical signals reflected from a human finger and then convert the optical signals to electronic signals. Because the sensor 210 is an optical sensor, the fingerprint system further includes a light guide plate 220 and a light source 240 disposed on one end of the light guide plate 220. In some embodiments, a top surface of the light guide plate 220 is attached to a bottom surface of the sensor 210 through a glue layer. The light guide plate 220 is adapted for guiding lights emitted from the light source 240 towards the protection layer 260. In some embodiments, the light source 240 may be a light-emitting diode (LED) .

In other embodiments, the sensor 210 may be a capacitance sensor. The capacitance sensor can obtain a fingerprint image by detecting capacitance variations of different parts of the human finger.

It should be noted that, any type of sensor can be used in the fingerprint system as long as it can capture fingerprint signals.

Referring to FIG. 3, the protection layer 260 is disposed on a top surface of the sensor 210, and is used for protecting the sensor from scratching or contamination. A bottom surface of the protection layer 260 may be attached to the top surface of the sensor 210, and a top surface of the protection layer 260 is used for finger touching. In a working process of the optical sensor, a finger touches the protection layer 260, and then the sensor can capture lights reflected from friction ridges of the finger. Hence, the protection layer 260 should be made of transparent material. In some embodiments, the protection layer 260 may be a fibre-optic plate. The fibre-optic plate has advantages of high light transmission efficiency, small inter-stage coupling loss, etc. In other embodiments, the protection layer 260 may be a sapphire layer, a glass layer, a plastic layer, an Ethylene Terephthalate (PET) layer, a rubber layer or a resin layer.

Referring to FIG. 3, the fingerprint system further includes a readout IC chip 250. The readout IC chip 250 is disposed on the top surface of the sensor 210. The readout IC chip 250 is connected to the sensor 210, so that the readout IC chip 250 can obtain and process the fingerprint signals transmitted from the sensor 210. In some embodiments, the readout IC chip 250 may be bonded on the top surface of the sensor 210 by a Chip on Glass (COG) process. For example, an Anisotropic Conductive Film (ACF) layer may be used between the readout IC chip 250 and the top surface of the sensor 210 for bonding them together.

In some embodiments, as shown in FIG. 3, the fingerprint system further includes a Flexible Printed Circuit (FPC) 230. An expanded view of the FPC 230 is schematically illustrated in FIG. 4. The FPC 230 is adapted for transmitting electronic signals between the finger print system and an external system. For example, the fingerprint system may be used in a mobile phone, a computer, or a fingerprint identification system, and the external system may a subsystem thereof. The FPC 230 consists of a thin insulating polymer film having conductive circuits patterns affixed thereto, and is typically supplied with a thin coating to protect the conductor circuits.

Specifically, as shown in FIG. 3 and FIG. 4, the FPC 230 includes a first part 230a and a second part 230b. The first part 230a of the FPC 230 is disposed under the light guide plate 220, and the second part 230b is disposed above the sensor 210. For example, the first part 230a may be attached to the bottom surface of the light guide plate 220 through a glue layer. Then the FPC 230 is folded, such that the second part 230b can cover the sensor 210. As shown in FIG. 4, the second part 230b of the FPC 230 has a second opening 232. After the second part 230b of the FPC 230 is folded to cover the sensor 210, the second opening 232 exposes the protection layer 260 of the sensor module.

In some embodiments, the fingerprint system further includes a touch detection electrode 270 and a touch detection IC chip (not shown) . The touch detection electrode 270 and the touch detection IC chip may be disposed on the second part 230b of the FPC 230. The touch detection electrode 270 is electrically connected with the touch detection IC chip for detecting whether a finger touches the protection layer 260. In the embodiment shown in FIG. 4, the touch detection electrode 270 includes two discontinuous parts having arcuate shapes. The touch detection electrode 270 may be made of conductive materials, for example, metal, conducting resin, etc.

As shown in FIG. 3, the cover plate 280 is disposed above the sensor module. For example, the cover plate 280 is attached to the second part 230b of the FPC 230 by a glue layer. The first opening of the cover plate 280 (not illustrated) exposes the protection layer 260 of the sensor module. The cover plate 280 may be a touch screen of a mobile phone, a computer or a fingerprint identification device.

A partial enlarged view of the fingerprint system shown in FIG. 3 is illustrated in FIG. 5. Referring to FIG. 5, due to assembly variations in the fabrication process, there is always a gap 265 between cover plate 280 and the protection layer 260 of the fingerprint system. Because the protection layer 260 is used for finger touching, electrostatic charges carried on human fingers may discharge through the gap 265, which may result in damages of the fingerprint system.

Therefore, the fingerprint system of the present disclosure further includes a ground loop around the protection layer 260. The ground loop 290 is connected to the ground. In some embodiments, as shown in FIG. 3 and FIG. 5, the ground loop 290 is disposed on the second part 230b of the FPC 230. The ground loop 290 may be disposed between the protection layer 260 and the touch detection electrode 270. Because the ground loop 290 is closer to the gap 265 than the touch detection electrode 270, the electrostatic charges carried on human fingers or an electrode head in an ESD testing can be preferentially transmitted to ground through the ground loop 290.

In some embodiments, the ground loop 290 may be formed on the second part 230b of the FPC 230 by a cladding process. The ground loop 290 is made of conductive materials, for example, copper, tin, or iron. In some embodiments, the ground loop 290 may be made of metal wire or metal foil, and may be pasted on the second part 230b of the FPC 230.

In some embodiments, as shown in FIG. 4, the ground loop 290 is a closed loop, and may have a circular shape, a square shape or a track shape. However, the present disclosure is not limited thereto. In other embodiments, the ground loop 290 may includes a plurality of discontinuous parts.

Correspondingly, a mobile phone is also provided in embodiments of the present disclosure. Referring to FIG. 6, a mobile phone 10 includes a fingerprint system 20. The structure of the fingerprint system 20 is similar to the fingerprint system described above, and is not described in detail herein. A cross-sectional view along the line A-A1 of the fingerprint system 20 in FIG. 6 is shown in FIG. 3. In this embodiment, the fingerprint system 20 can be used to recognize a user’s unique fingerprint to unlock mobile phone 10.

In conclusion, the fingerprint system of the present disclosure has a ground loop around the protection layer of the sensor module. The ground loop can discharge electrostatic charges carried on human fingers or an electrode head in an ESD testing. Therefore, the ground loop can prevent the fingerprint system or the mobile phone from ESD damages.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

A fingerprint system, comprising:

a sensor module which comprises a sensor adapted for obtaining fingerprint signals, and a protection layer disposed on the sensor；

a cover plate disposed above the sensor module, where the cover plate has a first opening exposing the protection layer； and

a ground loop disposed around the protection layer.
The fingerprint system according to claim 1, further comprising: a Flexible Printed Circuit (FPC) ,

wherein the FPC comprises a first part and a second part, the first part of the FPC is disposed under the light guide plate, the second part of the FPC is disposed above the sensor and has a second opening exposing the protection layer of the sensor module.
The fingerprint system according to claim 2, wherein the ground loop is disposed on the second part of the FPC.
The fingerprint system according to claim 3, further comprising: a touch detection electrode and a touch detection Integrated Circuit (IC) chip disposed on the second part of the FPC, wherein the touch detection electrode is electrically connected with the touch detection IC chip.
The fingerprint system according to claim 4, wherein the ground loop is disposed between the protection layer and the touch detection electrode.
The fingerprint system according to claim 1, wherein the ground loop is formed by a cladding process.
The fingerprint system according to claim 1, wherein the ground loop is made of metal wire or metal foil, and is pasted around the protection layer.
The fingerprint system according to claim 1, wherein the ground loop comprises copper, tin, or iron.
The fingerprint system according to claim 1, wherein the ground loop has a circular shape, a square shape or a track shape.
The fingerprint system according to claim 1, wherein the sensor is an optical sensor, and the sensor module further comprises:

a light guide plate disposed below a bottom surface of the sensor；

a light source disposed on one end of the light guide plate； and

a readout IC chip connected with the sensor, wherein the readout IC chip is adapted for processing the fingerprint signals obtained by the sensor.
The fingerprint system according to claim 1, wherein the sensor is a capacitance sensor.
A mobile phone, comprising: the fingerprint system according to any one of claims 1-11.