WO2017079912A1

WO2017079912A1 - Fingerprint recognition system

Info

Publication number: WO2017079912A1
Application number: PCT/CN2015/094265
Authority: WO
Inventors: Yapeng DANG; Hong Zhu; Yan LING
Original assignee: Shanghai Oxi Technology Co., Ltd
Priority date: 2015-11-11
Filing date: 2015-11-11
Publication date: 2017-05-18

Abstract

A fingerprint recognition system is provided. The system includes : at least one touch pad formed on a circuit board; a covering plate which includes a touch region, wherein when the touch region is touched by a finger, capacitance of the at least one touch pad to ground changes, and when the whole touch region is touched by the finger, the capacitance of the at least one touch pad to ground meets a preset requirement; and a processor, configured to : when the capacitance of the at least one touch pad to ground meets the preset requirement, activate a fingerprint recognition function of the fingerprint recognition system. The fingerprint recognition system may have an enough space for accommodating the touch pad, relatively high sensitivity, and reduced power consumption, and may be easily modified in development processes.

Description

FINGERPRINT RECOGNITION SYSTEM

FIELD OF THE DISCLOSURE

The present disclosure generally relates to touch recognition technology, and more particularly, to a fingerprint recognition system.

BACKGROUND OF THE DISCLOSURE

Nowadays, fingerprint recognition systems have been widely used in various products, such as a mobile phone, a computer or an entrance guard system. In some solutions, when a finger touches a portion of a touch region on a fingerprint recognition system, the system determines there is a touch event on the touch region, and activates a fingerprint recognition function of the system, which may not detect touch events accurately and cause a waste of power of the system.

SUMMARY

In an embodiment, a fingerprint recognition system is provided, including: at least one touch pad formed on a circuit board； a covering plate which includes a touch region, wherein when the touch region is touched by a finger, capacitance of the at least one touch pad to ground changes, and when the whole touch region is touched by the finger, the capacitance of the at least one touch pad to ground meets a preset requirement； and a processor, configured to: when the capacitance of the at least one touch pad to ground meets the preset requirement, activate a fingerprint recognition function of the fingerprint recognition system.

In some embodiments, the circuit board may be a Print Circuit Board (PCB) or a Flexible Printed Circuit (FPC) board.

In some embodiments, the fingerprint recognition system includes two touch pads, the covering plate covers the circuit board and the two touch pads, and a projection of the touch region on a bottom of the covering plate covers at least a portion of one of the two touch pads and at least a portion of the other of the two touch pads. And the processor is configured to activate the fingerprint recognition function when the capacitance of both the two touch pads to ground changes. As such, the fingerprint recognition function won’ t be activated when the finger is disposed above only one touch pad, i.e., when the finger touches only one side of the touch region.

In some embodiments, a light guide component may be disposed between the two touch pads.

In some embodiments, the covering plate may cover a top surface of the light guide component.

In some embodiments, the covering plate may have a hole exposing the top surface of the light guide component.

In some embodiments, the system may further include a metal shell, and the covering plate includes a metal ring where the touch region is located, wherein a top surface of the metal shell and a surface of the metal ring are insulated, the covering plate covers the top surface of the metal shell, an area of the touch region is at least seventy percent of an area of the metal ring, the at least one touch pad is insulated from the metal shell and adjacent to a bottom surface of the metal shell, and a sensor is disposed between the top surface of the metal shell and the circuit board. When the touch region is touched by the finger, capacitance is formed between the finger and the metal shell. Thus, capacitance of the at least one touch pad to ground may change. When capacitance variation of the at least one touch pad reaches a preset threshold, the processor is configured to activate the fingerprint recognition function of the system.

In some embodiments, the metal shell forms a closed chamber, and the at least one touch pad may be disposed inside the chamber.

In some embodiments, the metal shell may be unclosed, and the at least one touch pad may be disposed under the bottom surface of the metal shell.

In some embodiments, the system may further include a capacitance detection circuit connected with the at least one touch pad, configured to measure a charge amount on the at least one touch pad to obtain the capacitance of the at least one touch pad to ground.

In an embodiment, a method for activating a fingerprint recognition function of a fingerprint recognition system, where the fingerprint recognition system includes: at least one touch pad formed on a circuit board； and a covering plate which includes a touch region, wherein when the touch region is touched by a finger, capacitance of the at least one touch pad to ground changes, and when the whole touch region is touched by the finger, the capacitance of the at least one touch pad to ground meets a preset requirement, the method including: when the capacitance of the at least one touch pad to ground meets the preset requirement, activating the fingerprint recognition function of the fingerprint recognition system.

In some embodiments, the fingerprint recognition system includes two touch pads, the covering plate covers the circuit board and the two touch pads, and a projection of the touch region on a bottom of the covering plate covers at least a portion of one of the two touch pads and at least a portion of the other of the two touch pads. The method includes: when the capacitance of both the two touch pads to ground changes, activating the fingerprint recognition function of the fingerprint recognition system. As such, the fingerprint recognition function won’ t be activated when the finger is disposed above only one touch pad, i.e., when the finger touches only one side of the touch region.

In some embodiments, the fingerprint recognition system further includes a metal shell, and the covering plate includes a metal ring where the touch region is located, wherein a top surface of the metal shell and a surface of the metal ring are insulated, the covering plate covers the top surface of the metal shell, an area of the touch region is at least seventy percent of an area of the metal ring, the at least one touch pad is insulated from the metal shell and adjacent to a bottom surface of the metal shell, and a sensor is disposed between the top surface of the metal shell and the circuit board. When the touch region is touched by the finger, capacitance is formed between the finger and the metal shell. Thus, capacitance of the at least one touch pad to ground may change. The method includes activating the fingerprint recognition function of the system when capacitance variation of the at least one touch pad reaches a preset threshold.

In some embodiments, the method includes measuring a charge amount on the at least one touch pad to obtain the capacitance of the at least one touch pad to ground.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a cross-sectional view of a fingerprint imaging system when there is no touch event according to an embodiment of the present disclosure；

FIG. 2 schematically illustrates a topological diagram of FIG. 1；

FIG. 3 schematically illustrates a cross-sectional view of the fingerprint imaging system in FIG. 1 when a finger touches a touch region on the fingerprint imaging system；

FIG. 4 schematically illustrates a topological diagram of FIG. 3；

FIG. 5 schematically illustrates a structural diagram of a touch detection circuit in FIGs. 1 and 3 according to an embodiment of the present disclosure；

FIG. 6 schematically illustrates wave diagrams of electric levels applied to switches in FIG. 5；

FIG. 7 schematically illustrates a cross-sectional view of a fingerprint imaging system when there is no touch event according to an embodiment of the present disclosure；

FIG. 8 schematically illustrates a topological diagram of FIG. 7；

FIG. 9 schematically illustrates a cross-sectional view of the fingerprint imaging system in FIG. 7 when a finger touches a touch region on the fingerprint imaging system；

FIG. 10 schematically illustrates a topological diagram of FIG. 9；

FIG. 11 schematically illustrates a cross-sectional view of a fingerprint imaging system when there is no touch event according to an embodiment of the present disclosure；

FIG. 12 schematically illustrates a topological diagram of FIG. 11；

FIG. 13 schematically illustrates a cross-sectional view of the fingerprint imaging system in FIG. 11 when a finger touches a touch region on the fingerprint imaging system； and

FIG. 14 schematically illustrates a topological diagram of FIG. 13.

DETAILED DESCRIPTION OF THE DISCLOSURE

Embodiments of the present disclosure provide fingerprint recognition systems. A fingerprint recognition function of the fingerprint recognition systems may be activated when a predetermined condition is reached. The fingerprint recognition systems may have an enough space for accommodating touch pads, relatively high sensitivity, and reduced power consumption, and may be easily modified in development processes.

In order to clarify the objects, characteristics and advantages of the disclosure, embodiments of present disclosure will be described in detail in conjunction with accompanying drawings.

In an embodiment, a fingerprint recognition system is provided. The fingerprint recognition system includes a fingerprint imaging system, a touch detection circuit and a processor.

In some embodiments, the fingerprint imaging system may be configured to obtain fingerprint images. The touch detection circuit may be configured to: detect a touch event； generate an interrupt signal when the detected touch event meets a preset requirement； and send the interrupt signal to the processor. The processor may be configured to activate a fingerprint recognition function of the fingerprint recognition system.

In some embodiments, the processor may be Digital Signal Processor (DSP) , Microcontroller Unit (MCU) or Field Programmable Gate Array (FPGA) .

Hereinafter, embodiments of the present disclosure provide various examples of fingerprint imaging systems.

FIG. 1 schematically illustrates a cross-sectional view of the fingerprint imaging system when there is no touch event according to an embodiment of the present disclosure. FIG. 2 schematically illustrates a topological diagram of FIG. 1. Referring to FIG. 1, the fingerprint imaging system 100 includes a sensor 101, a circuit board 102 on the sensor 101, two touch pads 103 formed on the circuit board 102, a covering plate 104 covering the touch pads 103, and a light guide component 105 between the two touch pads 103. A surface of the covering plate 104 includes a touch region, which is represented by a bold line in FIG. 1. A projection of the touch region on a bottom of the covering plate 104 covers at least a portion of one touch pad 103 and at least a portion of the other touch pad 103. Namely, the projection at least covers a portion of both the two touch pads 103.

In some embodiments, the circuit board 102 may be a PCB or a FPC board. In some embodiments, the touch pads 103 are capacitive touch pads.

As the touch pads are formed on the PCB or FPC board, the fingerprint recognition system may have an enough space for accommodating the touch pads, and relatively high sensitivity, and may be easily modified in development processes.

In some embodiments, the covering plate 104 covers a top surface of the light guide component 105. In some embodiments, the covering plate 104 has a hole exposing the top surface of the light guide component 105.

When no finger touches the touch region, capacitance between the first touch pad 103 and the ground is C1, capacitance between the second touch pad 103 and the ground is C2, and capacitance between the two touch pads 103 is C3.

Still referring to FIG. 1, the two touch pads 103 are connected with a capacitance detection circuit 106, respectively. The capacitance detection circuits 106 are configured to measure the capacitance of the two touch pads 103 to ground.

FIG. 3 schematically illustrates a cross-sectional view of the fingerprint imaging system 100 in FIG. 1 when a finger touches the covering plate 104. FIG. 4 schematically illustrates a topological diagram of FIG. 3.

Referring to FIG. 3, when the finger touches the touch region, capacitance C4 between the finger and the ground is formed. Besides, capacitance C5 between the finger and the first touch pad 103, and capacitance C6 between the finger and the second touch pad 103 are formed.

As a result, the capacitance between the two touch pads 103 and the ground changes. The capacitance detection circuit 106 detects the capacitance of the two touch pads 103 to ground, and further whether the capacitance of the touch pads 103 is changed can be determined.

In some embodiments, an AND gate may be employed to determine whether both the two touch pads 103 have capacitance variation. When both the two touch pads 103 have capacitance variation, the AND gate outputs “1” ； or at least one of the two touch pads 103 has no capacitance variation, the AND gate outputs “0” .

To reduce the possibility of misdetection caused by interference in external environment, in some embodiments, if the finger only covers a portion of the touch region, for example, the finger is disposed above only one touch pad 103, the capacitance detection circuit 106 connected with the other touch pad 103 cannot detect capacitance variation on the other touch pad 103. The AND gate outputs 0, which indicates that a touch event does not actually occur on the touch region. As a result, the fingerprint recognition function will not be activated.

In some embodiments, when the finger covers the whole touch region, namely, at least a portion of both the two touch pads 103 are covered, the capacitance detection circuit 106 may detect capacitance variation of both the two touch pads 103 to ground. The AND gate may output “1” as an interrupt signal, and send the interrupt signal to a processor. After receiving the interrupt signal, the processor may activate the fingerprint recognition function of a fingerprint recognition system which includes the fingerprint imaging system 100, the capacitance detection circuit 106, the AND gate and the processor.

In this way, only the capacitance of both the two touch pads to ground changes, the processor may activate the fingerprint recognition function of the fingerprint recognition system； else, the fingerprint recognition system may not read related fingerprint data, which may save power of the fingerprint recognition system.

Hereinafter, the working principle of the capacitance detection circuit 106 is described in detail. FIG. 5 schematically illustrates a structural diagram of the capacitance detection circuit 106 according to an embodiment of the present disclosure, and FIG. 6 schematically illustrates wave diagrams of electric levels applied to switches in FIG. 5.

Referring to FIG. 5, the capacitance detection circuit 106 includes switches 201 to 205, an operational amplifier 206, a differential amplifier 207, an analog-to digital converter 208, and capacitors 209 to 211. A point R is set for connected with the touch pad 103. Referring to FIG. 6, the electric level L1 is applied to the

switches

201 and 202, an inverse electric level of the electric level L1 is applied to the switch 203, the electric level L2 is applied to the switch 204, and the electric level L3 is applied to the switch 205. When a high level is applied, it indicates that the corresponding switch is closed, and when a low level is applied, it indicates that the corresponding switch is open.

When no finger puts on the touch region of the fingerprint imaging system 100, only a self capacitor 212 (i.e., the touch pad 103) is connected to the point R. According to the wave diagrams of the electric levels L1 to L3, when L1 is high level, and L2 and L3 are low level, the

switches

201 and 202 are closed, the switches 203 to 205 are open, and output voltage Vout of the operational amplifier 206 and voltage of the point R are equal to voltage V_CM. When L1 and L2 are high level, and L3 is low level, the

switches

201, 202 and 204 are closed, the

switches

203 and 205 are open, and voltage of the point R and voltages Vout and Vr are equal to V_CM. Afterward, L1 changes to high level, and L2 and L3 change to low level again. In this condition, the voltage Vr retains to be equal to voltage V_CM. When L1, L2 and L3 are low level, the

switches

201, 202, 204 and 205 are open, and the switch 203 is closed. The voltage of the point R is equal to the voltage Vref, and the self capacitor 212 is charged to the voltage Vref. In this case, the voltage Vout ＝ V_CM + (Vref -V_CM) *C₂₁₂ /C₂₀₉, where C₂₁₂ and C₂₀₉ represent capacitance of the

capacitors

212 and 209, respectively. When L1 and L2 are low level, and L3 is high level, the

switches

201, 202 and 204 are open, and the

switches

203 and 205 are closed. The voltage of the point R is equal to the voltage Vref, the self capacitor 212 is charged to the voltage Vref, and the voltage Vs ＝ Vout ＝ V_CM + (Vref -V_CM) *C₂₁₂ /C₂₀₉. The capacitor 211 is used to retain the voltage Vout. Afterward, L1, L2 and L3 change to low level again, the

switches

201, 202, 204 and 205 are open, and the switch 203 is closed. The voltage of the point R is equal to the voltage Vref, the voltage Vr is equal to V_CM, Vs ＝ V_CM + (Vref -V_CM) *C₂₁₂ /C₂₀₉, and output voltage of the analog-to digital converter 208 is (Vref -V_CM) *C₂₁₂ /C₂₀₉. In this condition, the output voltage of the analog-to digital converter 208 is detected. If the output voltage is equal to (Vref -V_CM) *C₂₁₂ /C₂₀₉, it indicates that no touch event substantially occurs. The levels L1, L2 and L3 repeat the change described above.

When a finger puts on the touch region, another capacitor 213 (i.e., the capacitance C5 or C6) is formed and also connected to the point R. When L1 is high level, and L2 and L3 are low level, the

switches

201 and 202 are closed, the switches 203 to 205 are open, and voltage Vout of the operational amplifier 206 and voltage of the point R are equal to voltage V_CM. When L1 and L2 are high level, and L3 is low level, the

switches

201, 202 and 204 are closed, the

switches

203 and 205 are open. As same as the voltage Vout and the voltage of the point R, the voltage Vr is also equal to voltage V_CM. Afterward, L1 changes to high level, and L2 and L3 change to low level again. In this condition, the voltage Vr retains to be equal to voltage V_CM. When L1, L2 and L3 are low level, the

switches

201, 202, 204 and 205 are open, and the switch 203 is closed. The voltage of the point R is equal to the voltage Vref, and the self capacitor 212 is charged to the voltage Vref. In this case, the voltage Vout ＝V_CM + (Vref -V_CM) * (C₂₁₂ + C₂₁₃) /C₂₀₉, where C₂₁₂ and C₂₀₉ represent capacitance of the

capacitors

switches

201, 202 and 204 are open, and the

switches

203 and 205 are closed, the voltage of the point B is equal to voltage Vref, the self capacitor 212 and the capacitor 213 are charged, and Vs ＝ Vout ＝ V_CM + (Vref -V_CM) * (C₂₁₂ + C₂₁₃) /C₂₀₉. In this condition, the capacitor 211 can be used to retain the voltage Vout. Afterward, L1, L2 and L3 change to low level again, the

switches

201, 202, 204 and 205 are open, and the switch 203 is closed. The voltage of the point R is equal to the voltage Vref, the voltage Vr is equal to V_CM, Vs ＝ V_CM + (Vref -V_CM) * (C₂₁₂ + C₂₁₃) /C₂₀₉, and output voltage of the analog-to digital converter 208 is (Vref -V_CM) * (C₂₁₂ + C₂₁₃) /C₂₀₉. In this condition, the output voltage of the analog-to digital converter 208 is detected. If the output voltage is equal to (Vref -V_CM) * (C₂₁₂ + C₂₁₃) /C₂₀₉ rather than (Vref -V_CM) *C₂₁₂ /C₂₀₉, it may indicate that a touch event occurs. The levels L1, L2 and L3 repeat the change described above.

By detecting the output voltage of the analog-to digital converter 208 as described above, the capacitance detection circuit 106 can determine the capacitance of the touch pad 103 to ground. Further, whether the capacitance of the touch pad 103 to ground changes can be determined.

FIG. 7 schematically illustrates a cross-sectional view of a fingerprint imaging system when there is no touch event according to an embodiment of the present disclosure. FIG. 8 schematically illustrates a topological diagram of FIG. 7. Referring to FIG. 7, the fingerprint imaging system 300 includes a sensor 301, a circuit board 302 under the sensor 301, a touch pad 303 formed on a surface of the circuit board 302 which surface faces away from the sensor 301, and a light guide component 304 formed on the sensor 301. The fingerprint imaging system 300 further includes a shell 305 encompassing the sensor 301, the circuit board 302, the touch pad 303 and side surfaces of the light guide component 304. The shell 305 forms a closed chamber. Namely, the touch pad 303 is disposed inside the shell 305. A covering plate 306 covers a top surface of the shell 305 and a top surface of the light guide component 304. The covering plate 306 has a metal ring 307 formed thereon, where a surface of the metal ring 307 is insulated. The surface of the metal ring 307 includes a touch region which is represented by a bold line in FIG. 7. An area of the touch region occupies at least seventy percent of an area of the metal ring 307.

In some embodiments, the circuit board 302 may be a PCB or a FPC board. In some embodiments, the touch pad 303 is a capacitive touch pad.

In some embodiments, the top surface of the shell 305 is insulated, and other portions of the shell 305 are made of a conductive material, such as metal. The touch pad 303 is disposed adjacent to a bottom surface of the shell 305, namely, a conductive portion of the shell 305.

When no finger touches the touch region, capacitance between the touch pad 303 and a lower portion of the shell 305 is C1, and capacitance between the lower portion of the shell 305 and the ground is C2.

Still referring to FIG. 7, the touch pad 303 is connected with a capacitance detection circuit 308 which is configured to detect the capacitance of the touch pad 303 to ground.

FIG. 9 schematically illustrates a cross-sectional view of the fingerprint imaging system 300 in FIG. 7 when a finger touches the touch region. FIG. 10 schematically illustrates a topological diagram of FIG. 9.

Referring to FIG. 9, when the finger touches the touch region, capacitance C3 between the finger and the ground is formed. Besides, capacitance C4 between the finger and the lower portion of the shell 305 is formed.

As a result, the capacitance between the touch pad 303 and the ground changes. The capacitance detection circuit 308 may detect the capacitance of the touch pad 303 to ground, and further the capacitance variation can be determined.

To reduce the possibility of misdetection caused by interference in external environment, in some embodiments, if the finger only covers a portion of the touch region, capacitance variation of the touch pad 303 detected by the capacitance detection circuit 308 may not reach a preset threshold. Accordingly, the fingerprint recognition function will not be activated.

In some embodiments, when the finger covers the whole touch region, based on the capacitance of the touch pad 303 to ground detected by the capacitance detection circuit 308, it is determined that the capacitance variation of the touch pad 303 reaches the preset threshold, namely, a touch event actually occurs on the touch region. An interrupt signal may be generated by a touch detection circuit which includes the capacitance detection circuit 308, and sent to a processor. In some embodiments, the capacitance detection circuit 308 may measure a charge amount on the touch pad 303 to obtain the capacitance of the touch pad 303 to ground. After receiving the interrupt signal, the processor may activate the fingerprint recognition function of a fingerprint recognition system which includes the fingerprint imaging system 300, the touch detection circuit and the processor.

In the embodiment, the fingerprint imaging system 300 includes one touch pad 303. However, the present disclosure is not limited thereto. In some embodiments, the fingerprint imaging system 300 may include a plurality of touch pads 303 formed on the circuit board 302.

From above, only the capacitance variation of the touch pad reaches a preset threshold, the processor may activate the fingerprint recognition function of the fingerprint recognition system； else, the fingerprint recognition system may not read related fingerprint data, which may save power of the fingerprint recognition system.

FIG. 11 schematically illustrates a cross-sectional view of a fingerprint imaging system when there is no touch event according to an embodiment of the present disclosure. FIG. 12 schematically illustrates a topological diagram of FIG. 11. Referring to FIG. 11, the fingerprint imaging system 400 includes a sensor 401, a light guide component 402 formed on the sensor 401, a shell 403 covering the sensor 401 and side surfaces of the light guide component 402. The fingerprint imaging system 400 further includes a covering plate 404 which covers a top surface of the shell 403 and a top surface of the light guide component 402. A circuit board 405 is disposed under the shell 403 with a touch pad 406 formed thereon. The touch pad 406 is adjacent to a bottom surface of the shell 403. The covering plate 404 has a metal ring 407 formed thereon, where a surface of the metal ring 407 is insulated. The surface of the metal ring 407 includes a touch region which is represented by a bold line in FIG. 11. An area of the touch region occupies at least seventy percent of an area of the metal ring 407.

In some embodiments, the circuit board 405 may be a PCB or a FPC board. In some embodiments, the touch pad 406 is a capacitive touch pad.

In some embodiments, the top surface of the shell 403 is insulated, and other portions of the shell 403 are made of a conductive material, such as metal.

When no finger touches the touch region, capacitance between the touch pad 406 and the ground is C1, capacitance between a lower portion of the shell 403 and the ground is C2, and capacitance between the touch pad 406 and the lower portion of the shell 403 is C3.

Still referring to FIG. 11, the touch pad 406 is connected with a capacitance detection circuit 408 which is configured to detect the capacitance of the touch pad 406 to ground.

FIG. 13 schematically illustrates a cross-sectional view of the fingerprint imaging system 400 in FIG. 13 when a finger touches the touch region. FIG. 14 schematically illustrates a topological diagram of FIG. 13.

Referring to FIG. 13, when the finger touches the touch region, capacitance C4 between the finger and the ground is formed. Besides, capacitance C5 between the finger and the lower portion of the shell 303 is formed.

As a result, the capacitance between the touch pad 406 and the ground changes. The capacitance detection circuit 408 may detect the capacitance of the touch pad 406 to ground, and further the capacitance variation can be determined.

To reduce the possibility of misdetection caused by interference in external environment, in some embodiments, if the finger only covers a portion of the touch region, capacitance variation of the touch pad 406 detected by the capacitance detection circuit 408 may not reach a preset threshold. Accordingly, the fingerprint recognition function will not be activated.

In some embodiments, when the finger covers the whole touch region, based on the capacitance of the touch pad 406 to ground detected by the capacitance detection circuit 408, it is determined that the capacitance variation of the touch pad 406 reaches the preset threshold, namely, a touch event actually occurs on the touch region. An interrupt signal may be generated by a touch detection circuit which includes the capacitance detection circuit 408, and sent to a processor. In some embodiments, the capacitance detection circuit 408 may measure a charge amount on the touch pad 406 to obtain the capacitance of the touch pad 406 to ground. After receiving the interrupt signal, the processor may activate the fingerprint recognition function of a fingerprint recognition system which includes the fingerprint imaging system 400, the touch detection circuit and the processor.

In the embodiment, the fingerprint imaging system 400 includes one touch pad 406. However, the present disclosure is not limited thereto. In some embodiments, the fingerprint imaging system 400 may include a plurality of touch pads 406 formed on the circuit board 405. For example, two touch pads 406, both of which are adjacent to the bottom surface of the shell 403, are formed on the circuit board 405.

In the above embodiments, only the capacitance variation of the touch pad reaches a preset threshold, the processor may activate the fingerprint recognition function of the fingerprint recognition system； else, the fingerprint recognition system may not read related fingerprint data, which may save power of the fingerprint recognition system.

From above, in embodiments of the present disclosure, fingerprint recognition systems are provided, each of which includes a fingerprint imaging system, a touch detection circuit and a processor. At least one touch pad is formed on a circuit board in the fingerprint imaging system. When capacitance of the at least one touch pad meets a preset requirement, a fingerprint recognition function of the fingerprint recognition system is activated. The fingerprint recognition system may have an enough space for accommodating the touch pad, relatively high sensitivity, and reduced power consumption, and may be easily modified in development processes.

Although the present disclosure has been disclosed as above with reference to preferred embodiments thereof but will not be limited thereto. Those skilled in the art can modify and vary the embodiments without departing from the spirit and scope of the present disclosure. Accordingly, without departing from the scope of the present invented technology scheme, whatever simple modification and equivalent variation belong to the protection range of the present invented technology scheme.

Claims

A fingerprint recognition system, comprising:

at least one touch pad formed on a circuit board；

a covering plate which comprises a touch region, wherein when the touch region is touched by a finger, capacitance of the at least one touch pad to ground changes, and when the whole touch region is touched by the finger, the capacitance of the at least one touch pad to ground meets a preset requirement； and

a processor, configured to: when the capacitance of the at least one touch pad to ground meets the preset requirement, activate a fingerprint recognition function of the fingerprint recognition system.
The system according to claim 1, wherein the circuit board is a print circuit board or a flexible printed circuit board.
The system according to claim 1, wherein the fingerprint recognition system comprises two touch pads, the covering plate covers the circuit board and the two touch pads, and a projection of the touch region on a bottom of the covering plate covers at least a portion of one of the two touch pads and at least a portion of the other of the two touch pads, wherein the processor is configured to activate the fingerprint recognition function of the system when the capacitance of both the two touch pads to ground changes.
The system according to claim 3, wherein a light guide component is disposed between the two touch pads.
The system according to claim 4, wherein the covering plate covers a top surface of the light guide component.
The system according to claim 4, wherein the covering plate has a hole exposing a top surface of the light guide component.
The system according to claim 1, wherein the system further comprises a metal shell, and the covering plate comprises a metal ring where the touch region is located,

wherein a top surface of the metal shell is insulated, the covering plate covers the top surface of the metal shell, an area of the touch region is at least seventy percent of an area of the metal ring, the at least one touch pad is insulated from the metal shell and adjacent to a bottom surface of the shell, and a sensor is disposed between the top surface of the metal shell and the circuit board,

wherein when capacitance variation of the at least one touch pad reaches a preset threshold, the processor is configured to activate the fingerprint recognition function of the system.
The system according to claim 7, wherein the metal shell forms a closed chamber, and the at least one touch pad is disposed inside the chamber.
The system according to claim 7, wherein the metal shell is unclosed, and the at least one touch pad is disposed under the bottom surface of the metal shell.
The system according to claim 1, further comprising a touch detection circuit connected with the at least one touch pad, configured to obtain the capacitance of the at least one touch pad to ground.
The system according to claim 10, wherein the touch detection circuit is configured to measure a charge amount on the at least one touch pad to obtain the capacitance of the at least one touch pad to ground.
A method for activating a fingerprint recognition function of a fingerprint recognition system, where the fingerprint recognition system comprises: at least one touch pad formed on a circuit board； and a covering plate which comprises a touch region,

wherein when the touch region is touched by a finger, capacitance of the at least one touch pad to ground changes, and when the whole touch region is touched by the finger, the capacitance of the at least one touch pad to ground meets a preset requirement,

the method comprising: when the capacitance of the at least one touch pad to ground meets the preset requirement, activating the fingerprint recognition function of the fingerprint recognition system.
The method according to claim 12, wherein the fingerprint recognition system comprises two touch pads, the covering plate covers the circuit board and the two touch pads, and a projection of the touch region on a bottom of the covering plate covers at least a portion of one of the two touch pads and at least a portion of the other of the two touch pads, the method comprising: when the capacitance of both the two touch pads to ground changes, activating the fingerprint recognition function of the fingerprint recognition system.
The method according to claim 12, wherein the fingerprint recognition system further comprises a metal shell, and the covering plate comprises a metal ring where the touch region is located, wherein a top surface of the metal shell is insulated, the covering plate covers the top surface of the metal shell, an area of the touch region is at least seventy percent of an area of the metal ring, the at least one touch pad is insulated from the metal shell and adjacent to a bottom surface of the metal shell, and a sensor is disposed between the top surface of the metal shell and the circuit board, the method comprising: when capacitance variation of the at least one touch pad reaches a preset threshold, activating the fingerprint recognition function of the fingerprint recognition system.
The method according to claim 14, wherein the metal shell forms a closed chamber, and the at least one touch pad is disposed inside the chamber.
The method according to claim 14, wherein the metal shell is unclosed, and the at least one touch pad is disposed under the bottom surface of the metal shell.
The method according to claim 12, further comprising measuring a charge amount on the at least one touch pad to obtain the capacitance of the at least one touch pad to ground.