CN107980142A - A kind of fingerprint recognition circuit, fingerprint sensor and mobile terminal - Google Patents
A kind of fingerprint recognition circuit, fingerprint sensor and mobile terminal Download PDFInfo
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- CN107980142A CN107980142A CN201780001615.8A CN201780001615A CN107980142A CN 107980142 A CN107980142 A CN 107980142A CN 201780001615 A CN201780001615 A CN 201780001615A CN 107980142 A CN107980142 A CN 107980142A
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Classifications
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1306—Sensors therefor non-optical, e.g. ultrasonic or capacitive sensing
Abstract
The application section Example provides a kind of fingerprint recognition circuit, fingerprint sensor and mobile terminal.The fingerprint recognition circuit includes capacitive sensing array and multiple integration modules, and wherein capacitive sensing array includes the multiple Detection electrodes set with array way, and each Detection electrode respectively correspondingly connects an integration module；The Detection electrode is used to couple with the touch part of finger and form fingerprint capacitor；The integration module is used to charge to its corresponding fingerprint capacitor, and the electric charge of the fingerprint capacitor is shifted, and calculates the charging times count value of the fingerprint capacitor when the total amount of electric charge of accumulative transfer meets the preset condition；Wherein, the charging times count value is used for the capacitance for representing the fingerprint capacitor.The embodiment of the present application is conducive to compatibility of the lifting to different type digital algorithm circuit without analog-digital converter；Be conducive to save cost, reduce the design difficulty of fingerprint recognition circuit, reduce power consumption.
Description
Technical field
This application involves fingerprint identification technology field, especially, is related to a kind of fingerprint recognition circuit and uses the fingerprint
The fingerprint sensor and mobile terminal of identification circuit.
Background technology
Fingerprint, since it has otherness, uniqueness, convenience and the identifiability of individual, almost becomes life
The synonym of thing feature recognition, and fingerprint sensor is also widely used in various terminal equipment.Wherein, mobile phone, laptop
Deng consumer electronics product, frequently with the higher capacitive fingerprint sensing device of integrated level, to realize the identification to fingerprint.Due to referring to
There are protrusion and sunk part (i.e. wrinkle ridge and line paddy) in line texture, when pressing with finger capacitive fingerprint sensing device,
The distance between fingerprint detection electrode of wrinkle ridge and line paddy and capacitive fingerprint sensing device can have differences, thus finger print with
Fingerprint detection electrode is also just different in the fingerprint capacitor that wrinkle ridge and line paddy are formed, and thus causes wrinkle ridge and the corresponding fingerprint of line paddy
It is also just different to detect signal.Capacitive fingerprint sensing device is exactly according to this " difference ", to realize the identification to fingerprint.
Currently used capacitive fingerprint sensing device is generally believed above-mentioned fingerprint detection using analog-digital converter (i.e. ADC)
Digital signal number is converted in order to which follow-up digital algorithm is handled.However, the addition of this hardware of analog-digital converter, not only can
This rising is caused, can also increase the difficulty of mounting design, improve power consumption.Moreover, after the conversion of analog-digital converter, subsequently
Digital algorithm circuit eventually receive be a fixed digit digital signal, this will necessarily be to the choosing of digital algorithm circuit
The limitation caused very is selected, because the scope for the digital signal that different digital algorithm circuits can be handled is different.So modulus turns
The addition of parallel operation, also results in and is deteriorated to the compatibility of digital algorithm circuit.
The content of the invention
The purpose of the application section Example is to provide a kind of fingerprint recognition circuit, fingerprint sensor and mobile terminal,
So that analog-digital converter need not be installed, so that it may the capacitance touched between part of each Detection electrode and finger is obtained, so as to obtain
The finger print information of finger is taken, to reduce cost, the design difficulty for reducing fingerprint recognition circuit, reduction power consumption, and is lifted to difference
The compatibility of digital algorithm circuit.
One embodiment of the application provides a kind of fingerprint recognition circuit, including capacitive sensing array and multiple integration moulds
Block, wherein the capacitive sensing array includes the multiple Detection electrodes set with array way, each Detection electrode difference
A correspondingly connected integration module；The Detection electrode is used to couple with the touch part of finger and form fingerprint capacitor；Institute
State integration module to be used to charge to its corresponding fingerprint capacitor, and the electric charge of the fingerprint capacitor is shifted, and
Calculate the charging times count value of the fingerprint capacitor when the total amount of electric charge of accumulative transfer meets the preset condition；Wherein,
The charging times count value is used for the capacitance for representing the fingerprint capacitor.
The embodiment of the present application additionally provides a kind of mobile terminal, including cover board and fingerprint sensor, wherein the fingerprint passes
Sensor is arranged on the lower section of the cover board, and it includes fingerprint recognition circuit as described above.
The embodiment of the present application additionally provides a kind of fingerprint sensor, it includes fingerprint recognition circuit as described above
The embodiment of the present application in terms of existing technologies, (can add up transfer according to the charging times of integration module
Total amount of electric charge meets the charging times count value of fingerprint capacitor during preset condition), to calculate touching for each Detection electrode and finger
Touch the fingerprint capacitor between part.After the fingerprint capacitor touched between part for calculating each Detection electrode and finger, so that it may
The fingerprint capacitor calculated according to these obtains the finger print information of finger.This mode for obtaining finger print information, it is not necessary to by
Analog-digital converter (i.e. ADC), is conducive to save cost, reduces the design difficulty of fingerprint recognition circuit, reduces power consumption；Meanwhile by
No longer it is the digital signal of fixed digit in the digital signal of digital algorithm processing of circuit, also reduces to digital algorithm circuit
It is required that be conducive to compatibility of the lifting to different types of digital algorithm circuit.
In addition, the integration module includes integrator circuit, comparator circuit and counter circuit；The integrator circuit
Connected with corresponding Detection electrode, for charging to fingerprint capacitor, and shift the electric charge of the fingerprint capacitor；The comparison
Device circuit connects the integrator circuit and the counter circuit, and whether the total amount of electric charge for judging currently accumulative transfer is full
Sufficient preset condition, and will determine that result is exported to the counter circuit；The counter circuit is used to control the integration electricity
Road is charged to the fingerprint capacitor and electric charge transfer, and whether meets described preset in the total amount of electric charge of current accumulative transfer
The charging times count value of the fingerprint capacitor is exported during condition.Provide a kind of structure of integration module.
In addition, the counter circuit is additionally operable to when the total amount of electric charge of current accumulative transfer is unsatisfactory for preset condition, control
The integrator circuit is made to charge to the fingerprint capacitor again and electric charge transfer.A kind of counter circuit control product is provided
Point device circuit is charged and the condition of electric charge transfer.
In addition, the integrator circuit includes：Feedback capacity, operational amplifier, first switch and second switch；Wherein,
One end of the first switch is used to receive the first reference voltage, and the other end connects corresponding Detection electrode and the second switch
One end；The other end of the second switch connects the input terminal of the operational amplifier；The output terminal of the operational amplifier
As the integrator circuit output terminal and connect the comparator circuit；The feedback capacity is connected to the operation amplifier
Between the input terminal and output terminal of device.A kind of structure of integrator circuit is provided.
In addition, the integrator circuit controls filling for the fingerprint capacitor by the first switch and the second switch
Electricity and electric charge transfer, wherein its electric charge is transferred to the feedback capacity and described anti-after the fingerprint capacitor charges every time
Feed appearance is accumulated, and electric charge of the voltage of the output terminal of the integrator circuit for indicating presently described feedback capacity
Amount.Can be by adjusting the size of feedback capacity, to adjust the voltage of the output terminal of integrator circuit, so as to control final charging
Number (total amount of electric charge of i.e. accumulative transfer meets the charging times count value of fingerprint capacitor during preset condition).And for final
The control of charging times, can adjust the scope of the digital signal of output, be conducive to further lifting and different type numeral is calculated
The compatibility of method circuit.
In addition, the comparator circuit includes comparator, the first input end of the comparator connects the integrator electricity
The output terminal on road, its second input terminal are used to receive the second reference voltage；The output terminal of the comparator connects the counter
Circuit；The comparator is used to judge to work as when the voltage of the output terminal of the integrator circuit is more than second reference voltage
The total amount of electric charge of preceding accumulative transfer meets preset condition.A kind of comparator circuit is provided.
In addition, the comparator circuit includes comparator, the first partial pressure unit and the second partial pressure unit；The comparator
First input end connects the output terminal of the integrator circuit by first partial pressure unit, and passes through the second partial pressure list
Member ground connection；Second input terminal of the comparator is used to receive the second reference voltage, and its output terminal connects the counter electricity
Road；First partial pressure unit and second partial pressure unit are used to divide the voltage of the output terminal of the score indicator circuit
Pressure, the comparator are used to be more than the described second ginseng in the branch pressure voltage of first partial pressure unit and second partial pressure unit
Judge that the total amount of electric charge of current accumulative transfer meets preset condition when examining voltage.Another comparator circuit is provided.
In addition, the counter circuit is to the integrator circuit by sending enable signal and timing control signal, with
The integrator circuit is controlled to be charged to corresponding fingerprint capacitor and electric charge transfer.A kind of counter circuit control product is provided
Divide the mode of device circuit.
In addition, the counter circuit, when receiving the judging result of the comparator circuit output every time, control is filled
Electric count value adds 1, and represents that the fingerprint capacitor currently adds up transfer in the judging result of comparator circuit output
Total amount of electric charge meet to stop counting during the preset condition and export the charging times count value.A kind of counter electricity is provided
Road obtains the mode of charging times.
In addition, further including digital algorithm circuit, it is connected to the multiple integration module, for according to the multiple integration
The charging times count value of module output, calculates the capacitance of the corresponding fingerprint capacitor of the multiple Detection electrode respectively,
And the finger print information of the finger is obtained according to the capacitance of the fingerprint capacitor.A kind of finger print information for obtaining finger is provided
Mode.
In addition, the cover board is the cover sheet of the mobile terminal, and the cover sheet is in the fingerprint sensor
The thickness of region is less than the thickness in other regions.Be conducive to improve the penetrance of fingerprint detection signal.
In addition, the cover board is the display screen of the mobile terminal, and the fingerprint sensor is fitted in the display screen
Shield lower fingerprint recognition structure to be formed in lower section.The placement location in the terminal of another fingerprint sensor is provided.
In addition, the cover board is the glass cover-plate, ceramic cover plate, sapphire cover board for being arranged on the fingerprint sensor surface
Or coat.There is provided the material of a variety of cover boards so that can flexibly be selected according to actual conditions in practical applications.
Brief description of the drawings
One or more embodiments are illustrative by the picture in corresponding attached drawing, these exemplary theorys
The bright restriction not formed to embodiment, the element for having same reference numbers label in attached drawing are expressed as similar element, remove
Non- have a special statement, and composition does not limit the figure in attached drawing.
Fig. 1 is a kind of structure diagram of typical capacitance type fingerprint identification circuit；
Fig. 2 is the structure diagram according to the fingerprint recognition circuit of the application first embodiment；
Fig. 3 is the structure diagram according to the comparator circuit of the fingerprint recognition circuit of the application second embodiment；
Fig. 4 is the mounting structure of the cover board and capacitive fingerprint sensing device according to the mobile terminal of the application 3rd embodiment
Schematic diagram.
Embodiment
It is with reference to the accompanying drawings and embodiments, right in order to which the object, technical solution and advantage of the application are more clearly understood
The application section Example is further elaborated.It should be appreciated that specific embodiment described herein is only solving
The present invention is released, is not used to limit the application.
Referring to Fig. 1, it, which is applicant, proposes a kind of structure diagram of typical capacitance type fingerprint identification circuit.It is described
Capacitance type fingerprint identification circuit mainly includes capacitive sensing array 101, multiple integrator circuits 102, multiple selector (MUX)
103rd, buffer 104, analog-digital converter 105 and digital algorithm circuit 106.Wherein, the capacitive sensing array 101 includes more
A Detection electrode 1011, the array way distribution that the multiple Detection electrode 1011 is arranged with M rows N is so as to form the capacitive sensing
Array 101, M ＞ 1, N ＞ 1.Each Detection electrode 1011 respectively correspondingly connects an integrator circuit 102.In the capacitance
In formula fingerprint recognition circuit, analog-digital converter 105 is connected to by multiple selector 103 with a line integrator circuit 102；And
And in order to ensure signal quality, buffer 104 can be connected between multiple selector 103 and analog-digital converter 105.Modulus
Converter 105 is further attached to digital algorithm circuit 106, and the fingerprint detection signal that integrator circuit 102 is exported carries out
Exported after analog-to-digital conversion and carry out digital algorithm processing to digital algorithm circuit 106.
In fingerprint detection, each integrator circuit 102 can be successively to fingerprint capacitor CP(that is, its corresponding Detection electrode
1011 with finger touch part formed capacitance) carry out charging and discharging operation, and ceaselessly repeat aforesaid operations, until
Complete predetermined discharge and recharge number.Hereafter, the output signal of integrator circuit 102 can be through multiple selector 103 and buffer 104
It is sent to analog-digital converter 105.The output signal of integrator circuit 102 can be converted to digital signal by analog-digital converter 105, and
It is sent to digital algorithm circuit 106.Digital algorithm circuit 106 leads to after the digital signal of the transmission of analog-digital converter 105 is received
Digital Signal Processing can be calculated the fingerprint capacitor C touched between part of each Detection electrode 1011 and finger by crossingP,
So as to obtain the finger print information of user.
In above-mentioned capacitance type fingerprint identification circuit, the output signal of integrator circuit 102 is converted into by analog-digital converter 105
Digital signal generally there is fixed digit, it can cause to limit to follow-up digital algorithm circuit 106, that is, need selection to locate
Manage the digital algorithm circuit of the digital signal of the fixation digit, it is difficult to compatible different types of digital algorithm circuit.It is additionally, since
The presence of 105 this hardware circuit of analog-digital converter, can also increase cost, increase the difficulty of mounting design, improve power consumption.
In order to solve the above-mentioned technical problem, the application first embodiment provides a kind of fingerprint recognition circuit, without
Analog-digital converter can obtain the fingerprint capacitor touched between part of each Detection electrode and finger, so as to obtain finger
Finger print information.
As shown in Fig. 2, the fingerprint recognition circuit can be applied in capacitive fingerprint sensing device, it includes capacitive sensing battle array
Row 201, multiple integration modules 208 and digital algorithm circuit 205.Wherein, capacitive sensing array 201 includes multiple Detection electrodes
2011, the array way that the multiple Detection electrode 2011 is arranged with M rows N is distributed so as to form the capacitive sensing array 201, its
In each Detection electrode 2011 be respectively correspondingly connected to an integration module 208, and the output of the multiple integration module 208
End is connected to digital algorithm circuit 205.
When finger presses the capacitive fingerprint sensing device, multiple Detection electrodes of the capacitive sensing array 201
2011 couple with the touch part of finger respectively, and can form fingerprint between the multiple Detection electrode 2011 and finger respectively
Capacitance Cp.Due to the protrusion and sunk part (i.e. wrinkle ridge and line paddy) and the Detection electrode of its position of fingerprint texture
2011 distance is different, therefore, the fingerprint capacitor C between wrinkle ridge and Detection electrode 2011pWith line paddy and Detection electrode 2011 it
Between fingerprint capacitor CpThere is also difference, so by detecting fingerprint capacitor CpCapacitance just would know that finger which be partly
Wrinkle ridge, which is partly line paddy, so as to obtain the finger print information of finger.In addition, it is noted that in practical applications, institute
201 surface of capacitive sensing array for stating fingerprint recognition circuit usually sets cover sheet (such as glass cover-plate, sapphire cover board, pottery
Porcelain cover board or coating (Coating) layer；Alternatively, when the capacitive fingerprint sensing device is applied in mobile terminal device, institute
The cover sheet of the mobile terminal device can also be used by stating cover board), therefore, above-mentioned finger presses the capacitance type fingerprint and passes
Sensor can essentially refer specifically to the cover board above the finger pressing capacitive fingerprint sensing device, wherein the cover board serves as hand
Refer to the fingerprint capacitor C with coupling formation between each Detection electrode 2011pDielectric layer.Wherein, the capacitance type fingerprint sensing
The structure of cover board is set above device, can preferably protect the Detection electrode 2011 of the capacitive sensing array 201 from infringement.
Each integration module 208 is used for the fingerprint capacitor C corresponding to the Detection electrode 2011 that is connected to itpCharge,
And by the fingerprint capacitor C after fully charged every timepElectric charge transfer to integrating capacitor carry out Integral Processing (i.e. to the fingerprint
Capacitance CpDischarge), and above-mentioned charging and electric charge transfer step are repeated, until the total amount of electric charge satisfaction of accumulative transfer is default
Condition.In the process, integration module 208 can meet the total amount of electric charge of above-mentioned accumulative transfer required during the preset condition
Charging times carry out counting processing, and charging times count value is sent to digital algorithm circuit 205.Digital algorithm circuit
205 can calculate the Detection electrode that the integration module 208 connected according to the charging times count value by digital algorithm
The 2011 and fingerprint capacitor C touched between part of fingerp.Further, the digital algorithm circuit 205 can be with described more
The charging times count value that a integration module 208 exports, be calculated all Detection electrodes 2011 and finger touch part it
Between fingerprint capacitor Cp, so as to get the finger print information of finger.
In the present embodiment, each integration module 208 may include integrator circuit 202, comparator circuit 203 and counter electricity
Road 204.Wherein, the corresponding Detection electrode 2011 of integrator circuit 202 connects, for the Detection electrode 2011 connected to it
Corresponding fingerprint capacitor CpCharge, and by the fingerprint capacitor C after fully chargedpElectric charge transfer to its internal product
Divide capacitance (i.e. feedback capacity Cf).Comparator circuit 203 is then used to judge currently whether the accumulative total amount of electric charge shifted to meet pre-
If condition, and will determine that result is exported to counter circuit 204.If the total amount of electric charge of current accumulative transfer is unsatisfactory for the default bar
Part, then counter circuit 204 can trigger integrator circuit 202 and repeat above-mentioned charging and charge transfer process；If current accumulative turn
The total amount of electric charge of shifting meets the preset condition, then counter circuit 204 can be by the charging of the integrator circuit 202 of current record time
Number, and charging times count value is sent to follow-up digital algorithm circuit 205.The charging times are the electric charge of accumulative transfer
Total amount meets required charging times during the preset condition.In the present embodiment, counter circuit 204 can carry out fingerprint detection
It is preceding that charging times count value is zeroed out, (compare receiving the judging result from comparator circuit 203 every time afterwards
The output signal of device circuit) when, control and charging times count value is added 1 inside it, so current charging times count value is just
It is identical with the charging times of integrator circuit 202.Therefore, in the present embodiment, counter circuit 204 can be by current charging times
Charging times of the count value as current integration device circuit 202, and export to digital algorithm circuit 205.
As a kind of embodiment, as shown in Fig. 2, integrator circuit 202 may particularly include：Feedback capacity Cf, operation amplifier
Device 209, first switch S1, second switch S2, for input the first reference voltage VREF1The first connecting pin and for connecting
The second connection end of Detection electrode 2011.Wherein, one end of first switch S1 connects the first connecting pin, and the other end connects the respectively
Two connecting pins and one end of second switch S2；The inverting input of the other end concatenation operation amplifier 209 of second switch S2；Fortune
Calculate the in-phase input end ground connection of amplifier；Output terminal and company of the output terminal of operational amplifier as the integrator circuit 202
Connect comparator circuit 203；Feedback capacity CfIt is connected between the inverting input of operational amplifier and output terminal.
Comparator circuit 203 mainly includes comparator 207, the first input end connection integrator electricity of comparator circuit 203
The output terminal (i.e. the output terminal of operational amplifier 209) on road 202, the second input terminal of comparator circuit 203 are used to input second
Reference voltage VREF2；The output terminal linkage counter circuit 204 of comparator circuit 203.In the embodiment shown in Figure 2, compare
Inverting input, in-phase input end and the output terminal of device 207 can be connected respectively to the first input of the comparator circuit 203
End, the second input terminal and output terminal.
In the present embodiment, in fingerprint capacitor CpAfter charging, fingerprint capacitor CpElectric charge be transferred to positioned at integrator circuit
Feedback capacity C in 202f；Wherein, it is transferred to feedback capacity CfThe quantity of electric charge directly influence the output terminal of operational amplifier 209
Voltage.Comparator circuit 203 is according to the voltage of the voltage of the output terminal of current operation amplifier 209, to judge currently to tire out
Whether the total amount of electric charge of meter transfer meets preset condition.Specifically, the capacitive fingerprint sensing device is pressed simultaneously in finger
Fingerprint capacitor C is formed with Detection electrode 2011pIn the case of, i.e., described integrator circuit 202 can be according to counter circuit 204
The enable signal EN and clock signal clk of offer, control first switch S1 are closed and are controlled second switch S2 to disconnect, at this time, institute
State the first reference voltage V that the first connecting pin of integrator circuit 202 receivesREF1Can be by first switch S1 to fingerprint capacitor
CpCharge.In charging complete (i.e. described fingerprint capacitor CpVoltage reach the first reference voltage VREF1) after, the integrator
Circuit 202 can control first switch S1 to disconnect and control second switch S2 to close, at this time, fingerprint capacitor CpStart to feedback capacity
CfElectric discharge, i.e. fingerprint capacitor CpElectric charge can be transferred to feedback capacity Cf, therefore feedback capacity CfVoltage can become Vcf=Q/
Cf, wherein, Q represents the electric charge of current accumulative transfer, CfRepresent the capacitance of feedback capacity.After current charge transfer is completed,
The integrator circuit 202 is according to the enable signal EN's and clock signal clk control first switch S1 and second switch S2
Closure and off-state, to repeat above-mentioned to be directed to fingerprint capacitor CfCharging and the obtained electric charge transfer of charging to feeding back
Capacitance CfProcess.With repeating for above-mentioned charging and electric charge transfer, the feedback capacity CfCharge accumulated can gradually increase
More, i.e., the quantity of electric charge Q of current accumulative transfer can be more and more.Specifically, charge Q=N*V of current accumulative transferREF1*Cp,
VREF1Represent the first reference voltage, N represents current charging times (or transfer number of electric charge), CpRepresent the electricity of fingerprint capacitor
Capacitance.Since the in-phase input end of operational amplifier 209 is grounded, the feedback capacity CfVoltage just equivalent to the product
Divide the input voltage V of the output voltage, the i.e. first input end of comparator circuit 203 of device circuit 202in=Vcf=Q/Cf, compare
The meeting of device circuit 203 the second reference voltage V that it is received with the second input terminal by input voltageREF2It is compared, it is current to judge
Whether the total amount of electric charge of accumulative transfer meets preset condition.It is noted that it is the inverting input work with comparator in Fig. 2
It is first input end, in-phase input end as illustrating exemplified by the second input terminal, in practical applications, can also be with mutually defeated
Enter end and be used as first input end, inverting input is without limitation as the second input terminal, present embodiment.In addition, value
One be mentioned that, calculated to simplify, in practical applications, the first reference voltage and the second reference voltage can be also arranged to
Size, i.e. VREF1=VREF2。
In present embodiment, as the input voltage V of the first input end of comparator circuit 203in=Q/CfLess than the second ginseng
Examine voltage VREF2When, comparator circuit 203 will export high level signal to counter circuit 204；When comparator circuit 203
The input voltage V of first input endin=Q/CfMore than the second reference voltage VREF2When, comparator circuit 203 will be to counter
Circuit 204 exports low level signal.Suitable second reference voltage V may be selected in the present embodimentREF2And it is arranged on comparator electricity
The input voltage V of the first input end on road 203in=Q/CfMore than the second reference voltage VREF2When (counter circuit 204 is connecing
When receiving low level signal), judge that the total amount of electric charge of current accumulative transfer meets preset condition.
In general, integrator circuit 202 by once charge and electric charge transfer after, the first of comparator circuit 203
The input voltage V of input terminalin=Q/Cf=VREF1*Cp/CfIt will be generally less than the second reference voltage VREF2；By repeatedly charging
And after electric charge transfer, the input voltage V of the first input end of comparator circuit 203in=Q/Cf=N*VREF1*Cp/CfGradually
Increase is until more than the second reference voltage VREF2.More specifically, comparator circuit 203 is by the input voltage of its first input end
Vin=Q/Cf=VREF1*Cp/CfWith the second reference voltage VREF2After carrying out multilevel iudge first, high level letter can be generally exported
Number.Counter circuit 204 can be sent after the high level signal from comparator circuit 203 is received to integrator circuit 202
Enable signal EN and timing control signal (i.e. clock signal clk), triggering integrator circuit 202 control first switch S1 and second
The on off state of S2 is switched, with to fingerprint capacitor CpSecond is carried out to charge and electric charge is again transferred to feedback capacity Cf, at this time
Feedback capacity CfVoltage can bring up to Vin=Q/Cf=2*VREF1*Cp/Cf.Comparator circuit 203 may proceed to first input end
Input voltage and the reference voltage of the second input terminal compared for the second time, that is, compare the input voltage V of first input endin=
Q/Cf=2*VREF1*Cp/CfWith the second reference voltage VREF2.If counter circuit 204 still receives high level signal, can control
Integrator circuit 202 carries out fingerprint capacitor C againpCharging and electric charge transfer operation, until feedback capacity CfVoltage Vin
=Q/CfThe input voltage that the first input end that can cause comparator circuit 203 is had reached due to charge accumulated is more than second
Reference voltage VREF2, counter circuit 204 will receive comparator circuit 203 and export at this time low level signal, its is bright current
The total amount of electric charge of accumulative transfer has met preset condition.At this time, counter circuit 204 can count current charging times
Value is sent to digital algorithm circuit 205.
After digital algorithm circuit 205 receives charging times count value, you can calculated and referred to according to the charging times count value
Line capacitance Cp.In general, feedback capacity CfVoltage Vcf=Q/CfSlowly increase, the output letter of comparator circuit 203
Number from high level be turned into low-voltage when, feedback capacity CfVoltage Vcf=Q/CfWith the second reference voltage VREF2Between difference
It is very small.Therefore, when the output signal of comparator circuit 203 is turned into low-voltage from high level, it is believed that anti-at this time
Feed holds CfVoltage Vcf=Q/CfEqual to the second reference voltage VREF2, i.e. N*VREF1*Cp/Cf=VREF2, wherein, current charging
Times N, the first reference voltage VREF1, feedback capacity CfWith the second reference voltage VREF2Numerical value it is known that therefore, digital algorithm
Circuit 205 can calculate fingerprint capacitor C according to this equationp.Especially, as setting VREF1=VREF2When, at this time, above-mentioned equation is
It can be reduced to N*Cp/Cf=1.
Digital algorithm circuit 205 calculates the finger touched between part of each Detection electrode and finger according to the above method
Line capacitance Cp, so as to know the finger print information of finger.
In addition, it is noted that to ensure that comparator circuit 203 exports the accuracy of result, the present embodiment can also be adopted
With the method for copped wave, comparator 207 is inputted into mismatch calibration to than relatively low level.
Present embodiment can be by adjusting feedback capacity CfSize, to control (the i.e. accumulative transfer of final charging times
Total amount of electric charge meet required charging times during preset condition), so as to adjust the numeral for being output to digital algorithm circuit 205
The scope of signal, is conducive to further lifting to the compatibility of digital algorithm circuit 205.In addition, the finger that present embodiment provides
Line identification circuit need not be also beneficial to save cost, reduce the design of fingerprint recognition circuit by analog-digital converter (i.e. ADC)
Difficulty, reduce power consumption.
The application second embodiment is related to a kind of fingerprint recognition circuit.The present embodiment is right on the basis of first embodiment
The structure of comparator circuit has made further improvement.Mainly the improvement is that, in the present embodiment, in comparator circuit 207 also
Including a bleeder circuit.
As shown in figure 3, in the present embodiment, comparator circuit includes comparator and by the first partial pressure unit and the second partial pressure list
The bleeder circuit of member composition.First partial pressure unit includes resistance R1, and the second partial pressure unit includes resistance R2.Wherein, comparator
First input end the output terminal (i.e. the output terminal of operational amplifier) of integrator circuit is connected to by resistance R1, comparator
Second input terminal is used to input the second reference voltage VREF2.The first input of one end connection resistance R1 and comparator of resistance R2
End, the other end are then grounded.
" V in Fig. 3in" represent current integration device circuit output terminal voltage, " Vout" represent that the output of comparator is believed
Number.The input voltage V of the first input end of comparatorCOMP=Vin* R2/ (R1+R2)=(N*VREF1*Cp/Cf)*R2/(R1+R2)。
Comparator is by comparing VCOMPWith VREF2Magnitude relationship, to judge whether the total amount of electric charge of currently accumulative transfer meets default bar
Part.
The present embodiment, both can be by adjusting feedback capacity C for first embodimentfSize it is final to control
Charging times, also can control final charging times by the ratio of regulation resistance R1 and resistance R2, be output to so as to adjust
The scope of the digital signal of digital algorithm circuit.
The 3rd embodiment of the application is related to a kind of mobile terminal.The mobile terminal includes the fingerprint described in above-described embodiment
Identification circuit.
The mobile terminal can be the intelligent terminals such as mobile phone, tablet computer.As shown in figure 4, in practical applications, can be by electricity
Appearance formula fingerprint sensor 210 is placed in the lower section of cover board 206.Specifically, the cover board 206 can be the cover sheet of mobile terminal (i.e.
Main glass cover-plate), be the lower section that capacitive fingerprint sensing device 210 is hidden in cover sheet, using the above structure when, it is described
Cover sheet can be by doing reduction processing in the relevant position of the capacitive fingerprint sensing device 210 so that the condenser type
The cover sheet thickness of 210 region of fingerprint sensor is less than the thickness in other regions, so as to improve fingerprint detection signal
Penetrance.Alternately, which could be provided as the display screen (such as OLED display screen) of the mobile terminal, be
Capacitive fingerprint sensing device 210 is fitted in below display screen so as to form the lower fingerprint recognition structure of screen, using the lower fingerprint knot of screen
Structure can meet the needs of user shields accounting for the positive height of mobile terminal.Alternatively, the cover board 206 may also mean that and be attached to
Glass cover-plate, ceramic cover plate, sapphire cover board or the coat on 210 surface of capacitive fingerprint sensing device.Wherein, condenser type refers to
The semiconductor sensor chip that line sensor 210 is made by semiconductor fabrication process, capacitive sensing array 201 are placed in electricity
The superiors of appearance formula fingerprint sensor 210.Finger can by pressing the cover board 206 so that the pressing part of finger with it is each
Detection electrode 2011 couples forms fingerprint capacitor C respectivelyp.In the present embodiment, capacitive fingerprint sensing device 210 is placed in cover board
206 lower sections, can preferably protect the capacitive sensing array 201 on 21 surface of capacitive fingerprint sensing device.
The present embodiment can be by adjusting feedback capacity CfSize or the ratio of resistance R1 and resistance R2, be output to adjust
The scope of the digital signal of digital algorithm circuit, is conducive to compatibility of the lifting to digital algorithm circuit.In addition, present embodiment
The fingerprint recognition circuit of offer need not be also beneficial to save cost, reduce fingerprint recognition electricity by analog-digital converter (i.e. ADC)
The design difficulty on road, reduce power consumption.
The fourth embodiment of the application is related to a kind of fingerprint sensor.The fingerprint sensor may include first embodiment or
Fingerprint recognition circuit described in second embodiment.The fingerprint sensor can be applied in the mobile terminals such as mobile phone, tablet computer.
It will be understood by those skilled in the art that the various embodiments described above are to realize the specific embodiment of the application, and
In practical applications, can to it, various changes can be made in the form and details, without departing from spirit and scope.
Claims (15)
1. a kind of fingerprint recognition circuit, it is characterised in that including capacitive sensing array and multiple integration modules, wherein the capacitance
Induction arrays include the multiple Detection electrodes set with array way, and each Detection electrode respectively correspondingly connects a product
Sub-module；
The Detection electrode is used to couple with the touch part of finger and form fingerprint capacitor；
The integration module is used to charge to its corresponding fingerprint capacitor, and the electric charge of the fingerprint capacitor is turned
Move, and the charging times for calculating the fingerprint capacitor when the total amount of electric charge of accumulative transfer meets the preset condition count
Value；
Wherein, the charging times count value is used for the capacitance for representing the fingerprint capacitor.
2. fingerprint recognition circuit as claimed in claim 1, it is characterised in that the integration module includes integrator circuit, ratio
Compared with device circuit and counter circuit；
The integrator circuit is connected with corresponding Detection electrode, is charged for the fingerprint capacitor, and shifts the finger
The electric charge of line capacitance；
The comparator circuit connects the integrator circuit and the counter circuit, for judging the electricity of currently accumulative transfer
Whether lotus total amount meets preset condition, and will determine that result is exported to the counter circuit；
The counter circuit is used to control the integrating circuit to charge to the fingerprint capacitor and electric charge transfer, and is working as
Whether the total amount of electric charge of preceding accumulative transfer meets the charging times count value that the fingerprint capacitor is exported during the preset condition.
3. fingerprint recognition circuit as claimed in claim 2, it is characterised in that the counter circuit is additionally operable to add up currently
When the total amount of electric charge of transfer is unsatisfactory for preset condition, control the integrator circuit charged again to the fingerprint capacitor and
Electric charge transfer.
4. fingerprint recognition circuit as claimed in claim 2, it is characterised in that the integrator circuit includes：Feedback capacity, fortune
Calculate amplifier, first switch and second switch；
Wherein, one end of the first switch is used to receive the first reference voltage, and the other end connects corresponding Detection electrode and institute
State one end of second switch；The other end of the second switch connects the input terminal of the operational amplifier；The operation amplifier
The output terminal of device as the integrator circuit output terminal and connect the comparator circuit；The feedback capacity is connected to institute
State between the input terminal of operational amplifier and output terminal.
5. fingerprint recognition circuit as claimed in claim 4, it is characterised in that the integrator circuit passes through the first switch
Charging and the electric charge transfer of the fingerprint capacitor are controlled with the second switch, wherein the fingerprint capacitor every time after charging its
Electric charge is transferred to the feedback capacity and is accumulated in the feedback capacity, and the electricity of the output terminal of the integrator circuit
Pressure is used for the quantity of electric charge for indicating presently described feedback capacity.
6. fingerprint recognition circuit as claimed in claim 4, it is characterised in that the comparator circuit includes comparator, described
The first input end of comparator connects the output terminal of the integrator circuit, its second input terminal is used to receive second with reference to electricity
Pressure；The output terminal of the comparator connects the counter circuit；The comparator is used for the output in the integrator circuit
Judge that the total amount of electric charge of current accumulative transfer meets preset condition when the voltage at end is more than second reference voltage.
7. fingerprint recognition circuit as claimed in claim 4, it is characterised in that the comparator circuit includes comparator, first
Partial pressure unit and the second partial pressure unit；
The first input end of the comparator connects the output terminal of the integrator circuit by first partial pressure unit, and leads to
Cross the second partial pressure unit ground connection；Second input terminal of the comparator is used to receive the second reference voltage, and its output terminal
Connect the counter circuit；First partial pressure unit and second partial pressure unit are used for the defeated of the score indicator circuit
The voltage of outlet carries out partial pressure, and the comparator is used in the partial pressure of first partial pressure unit and second partial pressure unit electricity
Judge that the total amount of electric charge of current accumulative transfer meets preset condition when pressure is more than second reference voltage.
8. fingerprint recognition circuit as claimed in claim 2, it is characterised in that the counter circuit is by the integrator
Circuit sends enable signal and timing control signal, to control the integrator circuit to charge corresponding fingerprint capacitor and
Electric charge transfer.
9. fingerprint recognition circuit as claimed in claim 8, it is characterised in that the counter circuit is described in each receive
During the judging result of comparator circuit output, control charging times count value adds 1, and in the judgement of comparator circuit output
As a result represent that the total amount of electric charge that the fingerprint capacitor currently adds up to shift meets to stop counting and exporting institute during the preset condition
State charging times count value.
10. fingerprint recognition circuit as claimed in claim 1, it is characterised in that further include digital algorithm circuit, it is connected to institute
Multiple integration modules are stated, for the charging times count value exported according to the multiple integration module, are calculated respectively the multiple
The capacitance of the corresponding fingerprint capacitor of Detection electrode, and according to the finger of the capacitance of the fingerprint capacitor acquisition finger
Line information.
11. a kind of mobile terminal, it is characterised in that including cover board and fingerprint sensor, wherein the fingerprint sensor is arranged on
The lower section of the cover board, and it includes the fingerprint recognition circuit as any one of claims 1 to 10.
12. mobile terminal as claimed in claim 11, it is characterised in that the cover board is the protection cap of the mobile terminal
Plate, and thickness of the cover sheet in the fingerprint sensor region is less than the thickness in other regions.
13. mobile terminal as claimed in claim 11, it is characterised in that the cover board is the display screen of the mobile terminal,
And the fingerprint sensor is fitted in below the display screen to form the lower fingerprint recognition structure of screen.
14. mobile terminal as claimed in claim 11, it is characterised in that the cover board is to be arranged on the fingerprint sensor table
Glass cover-plate, ceramic cover plate, sapphire cover board or the coat in face.
15. a kind of fingerprint sensor, it is characterised in that it includes the fingerprint recognition as any one of claims 1 to 10
Circuit.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2017/108875 WO2019084832A1 (en) | 2017-11-01 | 2017-11-01 | Fingerprint recognition circuit, fingerprint sensor and mobile terminal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107980142A true CN107980142A (en) | 2018-05-01 |
| CN107980142B CN107980142B (en) | 2021-07-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201780001615.8A Active CN107980142B (en) | 2017-11-01 | 2017-11-01 | Fingerprint identification circuit, fingerprint sensor and mobile terminal |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN107980142B (en) |
| WO (1) | WO2019084832A1 (en) |
Cited By (3)
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|---|---|---|---|---|
| CN109977911A (en) * | 2019-04-08 | 2019-07-05 | 成都费恩格尔微电子技术有限公司 | A kind of fingerprint recognition circuit shields lower fingerprint acquisition system and acquisition method |
| WO2021031612A1 (en) * | 2019-08-16 | 2021-02-25 | 神盾股份有限公司 | Fingerprint sensing device |
| US11301708B2 (en) | 2019-10-01 | 2022-04-12 | Novatek Microelectronics Corp. | Image sensing circuit and method |
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|---|---|---|---|---|
| CN112255523A (en) | 2020-04-30 | 2021-01-22 | 神亚科技股份有限公司 | Measuring circuit for measuring passive element |
| CN112073047A (en) * | 2020-09-09 | 2020-12-11 | 上海东软载波微电子有限公司 | Capacitive touch key system and control method thereof |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN107980142B (en) | 2021-07-20 |
| WO2019084832A1 (en) | 2019-05-09 |
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Denomination of invention: A fingerprint recognition circuit, fingerprint sensor, and mobile terminal Effective date of registration: 20231219 Granted publication date: 20210720 Pledgee: Agricultural Bank of China Limited Shenzhen Futian Branch Pledgor: SHENZHEN GOODIX TECHNOLOGY Co.,Ltd. Registration number: Y2023980072606 |