CN103870817B

CN103870817B - A kind of radio frequency declines capacitive fingerprint acquisition chip and acquisition method

Info

Publication number: CN103870817B
Application number: CN201410118147.0A
Authority: CN
Inventors: 徐启波; 黄昊
Original assignee: CHENGDU FEIENGEER MICROELECTRONICS TECHNOLOGY Co Ltd; Chengdu Image Design Technology Co Ltd
Current assignee: CHENGDU FEIENGEER MICROELECTRONICS TECHNOLOGY Co Ltd; Chengdu Image Design Technology Co Ltd
Priority date: 2014-03-27
Filing date: 2014-03-27
Publication date: 2019-04-05
Anticipated expiration: 2034-03-27
Also published as: CN103870817A

Abstract

A kind of radio frequency declines capacitive fingerprint acquisition chip and acquisition method, the chip includes multiple with reference to sensing unit, the two-dimentional sensing unit array that multiple sensing units are formed, insulating layer, the insulating substrate of contact surface as finger, radiofrequency signal generation circuit, RF driven electrode, for provide be turned on and off sensing unit needed for source bias switching signal, and the sensing unit array control unit of charge and discharge clock signal needed for sensing unit is provided, analog-to-digital conversion array, control the digital analog converter of analog-to-digital conversion array gain, sensing unit distortion correction circuit, fingerprint image buffer, fingerprint image o controller and image-signal processor.The radio frequency provided by the present invention capacitive fingerprint acquisition chip that declines is made to be able to solve fingerprint residues, the interference of other radio-frequency radiations, prosthetic finger and investigation depth problem by improving the structure of sensing unit and increasing sensing unit distortion correction circuit, and the chip can embed it in capacitance touch screen.

Description

A kind of radio frequency declines capacitive fingerprint acquisition chip and acquisition method

Technical field

The present invention relates to IC design field, more particularly to a kind of radio frequency declines and capacitive fingerprint acquisition chip and its adopts Set method.

Background technique

Requirement with people to information security is higher and higher, and live biometric certification and identification are more and more It applies in daily life.Finger print identifying, which is used as in biological characteristic authentication, has very high reliability and cost performance, Have become the mainstream of current biological certification.At the same time, fingerprint collecting technology also high speed development, one more inexpensive, more Fast speed, small size, low-power consumption, high dynamic range and high investigation depth fingerprint sensor will capture huge market, because This, the fingerprint sensor having the above advantages becomes the emphasis of current research, wherein capacitive fingerprint sensing device becomes current One of main product.

With gradualling mature for fingerprint sensing technology, the advanced fingerprint sensing technology that Apple Inc. releases has been applied to shifting It starts in machine and other electronic products, or even Chinese third generation ID also need to carry out finger print information using fingerprint sensing technology Registration.It is not difficult to predict, fingerprint identification technology quickly and can be widely applied to our daily lifes, especially be applied to shifting In dynamic equipment.

At the same time, necessarily the requirement to the performance of fingerprint sensor can become higher and higher to high demand.One good finger Line identifying system can not only solve deficiency present in fingerprint sensor from algorithm, more should fundamentally solve to sense The acquisition quality problem of device.That is, being applied to the fingerprint sensor in mobile device, there must be very high detection deep Degree to meet application requirement, be preferably capable of fingerprint sensor being placed under touch panel or being integrated into touch panel without Influence the appearance of its performance and mobile device.

Existing country's fingerprint sensor is all the fingerprint sensor of purely capacitive formula, fingerprint residues and other spots residual It is influenced for RF type fingerprint sensor very greatly, and its investigation depth is no more than the dielectric of 20um thickness.Such as China Patent No. ZL021059608 and application No. is 201220476953 to be each provided with a kind of capacitance type fingerprint reading manner, by In finger direct contact surface to sensing array sensing electrode between insulating layer be the inorganic chemical for only having several um by thickness Object is constituted, very poor so as to cause its hydrophobicity, anti-residual, crushing resistance and antistatic property.

It will be apparent to those skilled in the art that the electrostatic protection that reach 20KV or more then requires on sensor sensing electrode The thickness of dielectric is greater than 20um.Fingerprint sensor only tri- companies of AUTHENTEC, FPC and VALIDITY, existing foreign countries RF type fingerprint collecting is realized, the RF type acquisition principle of AUTHENTEC and FPC Liang Ge company is substantially homologous, as the U.S. is special Sharp US6512381 realizes RF type fingerprint collecting, anti-fingerprint can remain and other spots residual, investigation depth well Only tens um detects one or more fingerprint pixels since a radio-frequency pulse is corresponding, in the stronger application of certain radio-frequency radiations Its anti-interference ability of occasion is poor.

When this radio-frequency pulse is interfered, a pixel or multiple pixels will be interfered.VALIDITY company Sensor its use typical structure (Chip-on-flex, abbreviation COF) principle of LCD MODULE, the sensor It can only be that slideably, and the fingerprint sensor of slidingtype is in user experience effect that working principle itself, which limits sensor, On be very poor so that such sensor cannot be used widely.

For example, referring to Fig. 1, Fig. 1 is the sensing unit structural schematic diagram of the fingerprint sensor of the prior art.As schemed Show, existing sensing unit 1 includes: the sense capacitance 11 that is formed by finger 10 with sensing electrode, by sensing electrode and amplifier Edge capacitance 12, amplifier 13 and the reseting switch circuit 14 that output electrode is formed；The sensing unit 1 is believed by detecting by radio frequency Numbers 15 radiofrequency signal sizes for handling digital reflex issued, the signal is after the amplification of capacitance integral amplifying circuit by subsequent circuit It is further processed, the radiofrequency signal of varying strength is detected according to the difference of 11 value of sense capacitance, to realize fingerprint collecting.It should (it is greater than 200u) when method is thick compared with the medium between sensing electrode for finger 10, needs to be corrected sensing unit 1, And correction difficulty is larger, moreover, the corresponding one or more pixels of a RF pulse signal of this method, such radiofrequency signal Part sensing unit will be by serious interference when by radiation interference.

Therefore, existing fingerprint sensor, either capacitive or RF type fingerprint sensor are all detection fingers The paddy ridge capacitance difference that valley line, crestal line and sensor sensing electrode are formed, it is that can be detected for the fingerprint sensor of the existing country In the number of levels of several fF, paddy ridge capacitance difference that can be detected for the fingerprint sensor of existing foreign countries exist paddy ridge capacitance difference The number of levels of 0.1fF, existing domestic and international fingerprint sensor are not met by the particular/special requirement of mobile device.

Summary of the invention

It declines capacitive fingerprint acquisition chip and its acquisition side in order to solve the above technical problem, the present invention provides a kind of radio frequency Method, i.e., do not influence that sensor is placed under touch-control glass panel in the case where mobile device appearance and still be able to sense clearly Fingerprint image.The present invention is able to detect that by improving the structure of sensing unit and increasing the realization of sensing unit distortion correction circuit Paddy ridge capacitance difference in 0.005fF hereinafter, the touch panel of 0.5mm thickness can be placed it in by improved fingerprint sensor Under still be able to sense clearly fingerprint image.

To achieve the above object, technical scheme is as follows:

A kind of radio frequency declines capacitive fingerprint acquisition chip, including L with reference to sensing unit, M*N sensing unit formation Two-dimentional sensing unit array, the radiofrequency signal generation circuit to generate radiofrequency signal, RF driven electrode, sensing unit array Controller, analog-to-digital conversion array, sensing unit distortion correction circuit, fingerprint image buffer, digital analog converter, fingerprint image are defeated Controller and image-signal processor out；The radiofrequency signal that RF driven electrode generates the radiofrequency signal generation circuit is sent out It is mapped to the finger for touching fingerprint sensor；Sensing unit array control unit is turned on and off needed for sensing unit for providing Charge and discharge clock signal needed for the switching signal and offer sensing unit of source bias；Analog-to-digital conversion array is turned by N number of modulus Parallel operation is constituted side by side, and the sense capacitance that the sensing unit array control unit detects is converted into fingerprint image gray value； Sensing unit distortion correction circuit, using L with reference to the collected data of sensing unit corrected as benchmark each sensing unit it Between deviation；Fingerprint image buffer is used to store the fingerprint image sum of the grayscale values sensing unit deviation currently converted Correction data；Digital analog converter controls the gain of the analog-to-digital conversion array；Fingerprint image o controller, to transmit Fingerprint image data；Image-signal processor receives the fingerprint image data that the fingerprint image o controller is sent, root According to the fingerprint image data judge its true or false and it is normal whether and make corresponding processing, wherein N be 1 to 150 it is whole Number, the integer that M is 2 to 300, L are the integer less than N*M, are directly covered in the insulating layer on acquisition chip circuit as institute State the dielectric layer of sense capacitance in sensing unit.

Preferably, each described sensing unit includes to be formed by single sense by the top-level metallic of integrated circuit technology Electrode, sense capacitance dielectric layer, reference capacitance and activated amplifier etc.；Sense capacitance dielectric layer, by being directly covered in top layer The insulating layer with a thickness of 0.1um~150um on metal is constituted, the single sense electrode and finger and sense capacitance medium Layer forms single sense capacitor；Activated amplifier, is connected to unit gain buffer, and input passes through switch connection sensing Electrode, output pass through switch connection bucking electrode；List is formed by by the metal layer except integrated circuit technology top-level metallic A bucking electrode, the single bucking electrode and single sense electrode form single mask capacitor, and the single bucking electrode will Single sense electrode and other electrode isolations, so that the parasitic capacitance formed with single sense electrode is zero；By integrated circuit work Any metal layer of skill is formed by single correcting electrode, and the single correcting electrode and single sense electrode form single correction electricity Hold；The single enhancing electrode formed by any metal layer of integrated circuit technology, the single enhancing electrode and single sense electrode Single enhancing capacitor is formed, enhancing capacitor is for enhancing collection effect；And multiple switch circuit, control reference capacitance, sense It surveys capacitor, enhancing capacitor and corrective capacity and carries out charge and discharge and equalizing charge.

Preferably, the sensing unit distortion correction circuit also includes forward-backward counter array, multiplier array, sensing Unit deviation statistics circuit and sensing unit deviation correction factor counting circuit, wherein the forward-backward counter array computation The deviation of the sensing unit and reference sensing unit；The sensing unit deviation statistics circuit counts the absolute value of the bias Average value；The number that the sensing unit deviation correction factor counting circuit inputs the input of the digital analog converter and host computer The average value of value and the absolute value of the bias carries out mapping calculation and obtains correction factor；The multiplier array by the deviation with The correction factor is multiplied, and exports correction data of the result as the sensing unit distortion correction circuit.The mapping meter The method of calculation are as follows: the correction factor is directly obtained by host computer, and the correction factor is directly equal to what host computer was calculated Correction factor；The method that host computer calculates correction factor is as follows:

K1=B*N1*E1/H1；

Wherein, K1 is the correction factor that host computer is calculated；

B is a fixed coefficient；

N1 is the numerical value that the digital analog converter for the chip that host computer is read by instruction inputs；

E1 is the average value that host computer reads the sensing unit and the absolute value of the bias with reference to sensing unit by instruction；

H1 is the assembly average by testing the actual sensed unit deviation that a large amount of chips obtain；

Or the correction factor is obtained by the chip interior, the calculation method of correction factor is as follows:

K2=B*N2*E2/H2；

Wherein, K2 is the correction factor that the chip is calculated；

B is a fixed coefficient；

N2 is the numerical value that the digital analog converter of the chip inputs；

The deviation of sensing unit distortion correction circuit is calculated described in E2 sensing unit and reference sensing unit is absolute The average value of value；

H1 is that the statistics by testing the actual sensed unit deviation that a large amount of chips obtain inputted by host computer is put down Mean value.

Another object of the present invention is to provide a kind of to be declined the fingerprint collecting side of capacitive fingerprint acquisition chip using above-mentioned radio frequency Method, the fingerprint collecting method are based on the radiofrequency signal generation circuit, the RF driven electrode and have charge pump circuit The sensing unit of structure realizes that finger print information to the conversion of electric signal, specifically comprises the following steps: by charge pump principle

Step S1: when finger is placed on two-dimentional sensing unit array, the sensing unit array control unit selects institute State effective row sensing unit of a line sensing unit as current acquisition fingerprint in two-dimentional sensing unit array；

Step S2: the sensing unit array control unit initializes the currently active row sensing unit；

Step S3: the sensing unit array control unit carries out fingerprint collecting to the currently active row sensing unit；

Step S4: the sensing unit array control unit carries out the collected finger print information of the currently active row sensing unit Correction；Finger print information after the correction of the currently active row sensing unit is taken away；

Step S5: the sensing unit array control unit selects next line sensing unit as the effective of current acquisition fingerprint Row sensing unit, sequence complete initialization, fingerprint collecting, finger print information correction and read finger print information Four processes, Zhi Daosuo State effective row sensing unit that sensing unit array control unit selects last line sensing unit as current acquisition fingerprint, sequence It completes initialization, fingerprint collecting, finger print information correction and reads finger print information Four processes.

Preferably, the step S2 is specifically included:

Step S21: the sensing unit array control unit exports the first pulse signal to the currently active row sensing unit, institute It states pulse signal to charge to the reference capacitance of the currently active row sensing unit during pulse width, makes reference capacitance both ends product The quantity of electric charge that tired value is C1*V1, the C1 are the capacitance of reference capacitance, and the V1 is the voltage value to charge to reference capacitance；

Step S22: the sensing unit array control unit exports the second pulse signal to the currently active row sensing unit, institute Stating the radiofrequency signal that pulse signal and the radiofrequency signal generation circuit generate makes the corrective capacity of the currently active row sensing unit Electric discharge makes the quantity of electric charge at its both ends become zero；The pulse signal makes the enhancing capacitor charging of the currently active row sensing unit, makes it Both ends accumulating value is the quantity of electric charge of C2*V2, and the C2 is the capacitance for enhancing capacitor, and the V2 is to the electricity of enhancing capacitor charging Pressure value；The pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S23: the radiofrequency signal that the radiofrequency signal generation circuit generates first makes the Partial charge of the enhancing capacitor Being transferred on the corrective capacity and being connected to the output of the unit gain buffer of the currently active row sensing unit currently has The bucking electrode of row sensing unit is imitated, the sensing unit array control unit output third pulse signal is sensed to the currently active row Unit, the third pulse signal make the reference capacitance, enhancing capacitor and corrective capacity carry out equalizing charge again；

Step S24: the second pulse signal and third arteries and veins of the sensing unit array control unit output fixed cycles number Signal is rushed to the currently active row sensing unit, the radiofrequency signal generation circuit generates the radio frequency letter of identical fixed cycles number Number, the phase that the second pulse signal and third pulse signal of the fixed cycles number are generated with the radiofrequency signal generation circuit With the radiofrequency signal of fixed cycles number, subtract the voltage difference at the reference capacitance both ends of the currently active row sensing unit gradually Small, the voltage difference at the reference capacitance both ends is locked after circulation terminates, wherein the fixed cycles number in initialization procedure can It is set as 2 N " power, the integer that N " is 2 to 8；The voltage differential signal is converted into currently by the analog-to-digital conversion array simultaneously The initialization value of effective row sensing unit；

Step S25: being passed to fingerprint image buffer for the initialization value of the currently active row sensing unit, completes current The initialization procedure of effective row sensing unit.

Preferably, the step S3 is specifically included:

Step S31: after initialization timing, the sensing unit array control unit exports the first pulse signal again and arrives The currently active row sensing unit, the pulse signal fill the reference capacitance of the currently active row sensing unit during pulse width Electricity, makes the reference capacitance both ends accumulate certain quantity of electric charge, and certain quantity of electric charge can be with the quantity of electric charge phase of initialization Together；

Step S32: the sensing unit array control unit exports the second pulse signal again and senses list to the currently active row The radiofrequency signal that member, the pulse signal and the radiofrequency signal generation circuit generate makes the sensing of the currently active row sensing unit Capacitor and corrective capacity electric discharge, make the quantity of electric charge at its both ends become zero, the pulse signal makes the increasing of the currently active row sensing unit Forceful electric power capacity charge makes the quantity of electric charge of its both ends accumulating value C2*V2, and wherein C2 is the capacitance for enhancing capacitor, and V2 is to enhancing The voltage value of capacitor charging；The pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S33: the radiofrequency signal that the radiofrequency signal generation circuit generates is by the RF driven electrode to outgoing It penetrates, finger, which contacts the radiofrequency signal that the radiofrequency signal generation circuit generates after the RF driven electrode, first makes the enhancing electric The Partial charge of appearance, which is transferred to, on the sense capacitance and corrective capacity and makes the unit gain of the currently active row sensing unit slow The output of storage is connected to the bucking electrode of the currently active row sensing unit, and the sensing unit array control unit exports again For three pulse signals to the currently active sensing unit, the third pulse signal makes the reference capacitance, sense capacitance, enhancing electricity again Hold and corrective capacity carries out equalizing charge；

Step S34: the sensing unit array control unit exports the second pulse signal and of another fixed cycles number For three pulse signals to the currently active row sensing unit, the radiofrequency signal that the radiofrequency signal generation circuit generates passes through the radio frequency Driving electrodes launch outward the radiofrequency signal of identical fixed cycles number, make the reference capacitance of the currently active row sensing unit The voltage difference at both ends gradually reduces, and the voltage difference at the reference capacitance both ends is locked after circulation terminates, wherein the fixation follows M " the power that ring number is 2, the integer that M " is 4 to 16；The voltage differential signal is converted by the analog-to-digital conversion array simultaneously The currently active collected finger print information of row sensing unit；

Step S35: being passed to fingerprint image buffer for the currently active collected finger print information of row sensing unit, complete At the fingerprint collecting process of the currently active row sensing unit.

Preferably, the step S4 is specifically included:

Step S41: the currently active row sensing unit is after completing initialization and fingerprint collecting process, the sensing unit battle array Column controller output the first correction timing, by the initial value of the currently active row sensing unit, the initial value with reference to sensing unit, number It is inclined that the numerical value of the input of mode converter and host computer input is input to the sensing unit distortion correction circuit calculating sensing unit The correction data of difference, and the sensing unit correction for drift data are stored in fingerprint image buffer；

Step S42: the second correction of sensing unit array control unit output timing senses the currently active row single The collected finger print information of member subtracts the information in fingerprint after the sensing unit correction for drift data are corrected；

Step S43: the information in fingerprint after the correction of the currently active row sensing unit is stored in the fingerprint image and is delayed In storage, the information in fingerprint after the correction is taken away under the control of host computer.

To achieve the above object, another technical solution of the invention is as follows:

A kind of radio frequency declines capacitive fingerprint acquisition chip, including L refers to sensing unit, M*N multiple-sensing unit shape At two-dimentional sensing unit array, the radiofrequency signal generation circuit to generate radiofrequency signal, RF driven electrode, compound sensing Cell array controller, analog-to-digital conversion array, multiple-sensing unit distortion correction circuit, fingerprint image buffer, digital-to-analogue conversion Device, fingerprint image o controller and image-signal processor；The multiple-sensing unit is by multiple compound sub- sensing units Composition；RF driven electrode is by emission of radio frequency signals that the radiofrequency signal generation circuit generates to touching fingerprint sensor Finger；Multiple-sensing unit array control unit, for provide be turned on and off sensing unit needed for source bias switch letter Number and provide multiple-sensing unit needed for charge and discharge clock signal；Analog-to-digital conversion array is made of side by side N number of analog-digital converter, Its by the multiple-sensing unit array detection to sense capacitance be converted into fingerprint image gray value；Multiple-sensing unit deviation Correcting circuit, using a deviation corrected as benchmark between each multiple-sensing unit with reference to the collected data of sensing unit of L； Fingerprint image buffer is used to store the fingerprint image sum of the grayscale values multiple-sensing unit deviation correction number currently converted According to；Digital analog converter controls the gain of the analog-to-digital conversion array；Fingerprint image o controller is to transmission fingerprint image Data；Image-signal processor receives the fingerprint image data that the fingerprint image o controller is sent, according to the fingerprint Image data judge its true or false and it is normal whether and make corresponding processing, wherein the integer that N is 1 to 150, M are 2 to 300 Integer, L is integer less than N*M, is directly covered in the insulating layer on acquisition chip circuit as the compound sensing singly The dielectric layer of sense capacitance in member.

Preferably, each described multiple-sensing unit includes that be formed by N ' by the top-level metallic of integrated circuit technology a Sensing electrode, sense capacitance dielectric layer, a sense capacitance of N ' and multiplexing reference capacitance etc.；Sense capacitance dielectric layer, by direct The insulating layer with a thickness of 0.1um~150um on the top-level metallic is covered in constitute；A sensing electrode of the N ' and finger And sense capacitance dielectric layer forms a sense capacitance of N '；It is a by the formed N ' of metal layer except integrated circuit technology top-level metallic Bucking electrode, a bucking electrode of the N ' and a sensing electrode of N ' form N number of mask capacitor；By any metal of integrated circuit technology A correcting electrode of N ' that layer is formed, a correcting electrode of the N ' and a sensing electrode of N ' form a corrective capacity of N '；By integrated electricity A enhancing electrode of the formed N ' of any metal layer of road technique, a enhancing electrode of the N ' and a sensing electrode of N ' form a enhancing of N ' Capacitor, enhancing capacitor is for enhancing collection effect；N ' organizes switching circuit；It is multiplexed activated amplifier, multiplexing unit is connected to and increases Beneficial buffer, input pass through N ' group switch connection a sensing electrode of N ', and output passes through a shielding electricity of a switch connection N ' of N ' Pole；A sensing electrode of the N ', sense capacitance dielectric layer, multiplexing reference capacitance, a mask capacitor of N ', a corrective capacity of N ', N ' A enhancing capacitor, N ' group switching circuit and multiplexing activated amplifier constitute a sub- sensing unit of N '；Wherein, each sub- sensing unit Include: a sensing electrode, sense capacitance dielectric layer, a mask capacitor, a corrective capacity, an enhancing capacitor, one group Switch, multiplexing reference capacitance and multiplexing activated amplifier, wherein multiplexing reference capacitance and multiplexing activated amplifier are sharing unit； It is described multiplexing reference capacitance and be multiplexed activated amplifier be placed on by a sensing electrode institute forming region of the N ' lower section or It is placed in by the side of a sensing electrode institute forming region of the N ', the marginal position of the marginal edge position from the region Vertical range be less than 500um.

Preferably, the sensing unit distortion correction circuit also includes forward-backward counter array, multiplier array, sensing Unit deviation statistics circuit and sensing unit deviation correction factor counting circuit, wherein the forward-backward counter array computation The deviation of the multiple-sensing unit and reference sensing unit；It is absolute that the sensing unit deviation statistics circuit counts the deviation The average value of value；The sensing unit deviation correction factor counting circuit inputs the input of the digital analog converter and host computer Numerical value and the absolute value of the bias average value carry out mapping calculation obtain correction factor；The multiplier array will be described inclined It is poor to be multiplied with the correction factor, export correction data of the result as the multiple-sensing unit distortion correction circuit.

Another object of the present invention is to provide a kind of to be declined the fingerprint collecting side of capacitive fingerprint acquisition chip using above-mentioned radio frequency Method, the fingerprint collecting method are based on the radiofrequency signal generation circuit, the RF driven electrode and have charge pump circuit The multiple-sensing unit of structure realizes that finger print information to the conversion of electric signal, specifically comprises the following steps: by charge pump principle

Step S1 ' multiple-sensing unit array control unit selects a line multiple-sensing unit in two-dimentional sensing unit array Effective row sensing unit of the sub- sensing unit as current acquisition fingerprint；

Step S2 ' multiple-sensing unit array control unit initializes the currently active row sensing unit；

The currently active row sensing unit of step S3 ' multiple-sensing unit array control unit carries out fingerprint collecting；

Step S4 ' multiple-sensing unit array control unit to the currently active collected finger print information of row sensing unit into Row correction；

Finger print information after the currently active row sensing unit correction of step S5 ' reading；

Step S6 ' multiple-sensing unit array control unit successively selects another sub- sensing unit of effective row sensing unit to make For the currently active row sensing unit, step S2 '~step S5 ' is repeated until completing the initialization of all sub- sensing units, referring to Line acquisition, finger print information correction and finger print information read Four processes；

Step S7 ' multiple-sensing unit array control unit successively selects the compound sense of next line in two-dimentional sensing unit array Survey effective row sensing unit of the sub- sensing unit of unit as current acquisition fingerprint, repeat step S2 '~step S6 ' up to It completes entire two-dimentional sensing unit array and four is read to the initialization of fingerprint, fingerprint collecting, finger print information correction and finger print information A process.

Preferably, the step S2 ' is specifically included:

Step S21 ': the multiple-sensing unit array control unit exports the first pulse signal and senses to the currently active row Unit, the pulse signal make the multiplexing reference capacitance of the currently active row sensing unit charge during pulse width, make it Both ends accumulating value is the quantity of electric charge of C1*V1, and the C1 is the capacitance for being multiplexed reference capacitance, and the V1 is to give multiplexing reference capacitance The voltage value of charging；

Step S22 ': the multiple-sensing unit array control unit exports the second pulse signal and senses to the currently active row The radiofrequency signal that unit, the pulse signal and the radiofrequency signal generation circuit generate makes the currently active row sensing unit Corrective capacity electric discharge, makes the quantity of electric charge at its both ends go to zero；The pulse signal makes the enhancing of the currently active row sensing unit Capacitor charging makes the quantity of electric charge of its both ends accumulating value C2*V2, and the C2 is the capacitance for enhancing capacitor, and the V2 is to increasing The voltage value of forceful electric power capacity charge；The pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S23 ': the radiofrequency signal that the radiofrequency signal generation circuit generates first makes the Partial charge of the enhancing capacitor It is transferred on the corrective capacity and is connected to the output of the multiplexing unit gain buffer of the currently active row sensing unit The bucking electrode of the currently active row sensing unit, the multiple-sensing unit array control unit export third pulse signal to working as Preceding effective row sensing unit, the third pulse signal make again the multiplexing reference capacitance, enhancing capacitor and corrective capacity into Row equalizing charge；

Step S24 ': the second pulse signal of multiple-sensing unit array control unit output fixed cycles number and the For three pulse signals to the currently active row sensing unit, the radiofrequency signal generation circuit generates penetrating for identical fixed cycles number Frequency signal, the second pulse signal and third pulse signal and the radiofrequency signal generation circuit of the fixed cycles number generate Identical fixed cycles number radiofrequency signal, make the currently active row sensing unit multiplexing reference capacitance both ends electricity Pressure difference gradually reduces, and the voltage difference at the multiplexing reference capacitance both ends is locked after circulation terminates, wherein in initialization procedure Fixed cycles number may be configured as 2 N " power, the integer that N " is 2 to 8；The analog-to-digital conversion array is by the voltage difference simultaneously Signal is converted into the initialization value of the currently active row sensing unit；

Step S25 ': the initialization value of the currently active row sensing unit is passed to fingerprint image buffer, is completed The initialization procedure of the currently active row sensing unit.

Preferably, the step S3 ' is specifically included:

Step S31 ': after initialization timing, the multiple-sensing unit array control unit exports the first pulse again For signal to the currently active row sensing unit, the pulse signal makes answering for the currently active row sensing unit during pulse width It is charged with reference capacitance, the multiplexing reference capacitance both ends is made to accumulate certain quantity of electric charge, certain quantity of electric charge can be with The quantity of electric charge of initialization is identical；

Step S32 ': the multiple-sensing unit array control unit exports the second pulse signal to the currently active row again The radiofrequency signal that sensing unit, the pulse signal and the radiofrequency signal generation circuit generate keeps the currently active row sensing single Sense capacitance and the corrective capacity electric discharge of member, make the quantity of electric charge at its both ends go to zero, the pulse signal makes the currently active row The enhancing capacitor charging of sensing unit makes the quantity of electric charge of its both ends accumulating value C2*V2, and wherein C2 is the capacitor for enhancing capacitor Value, V2 are to the voltage value of enhancing capacitor charging；The pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S33 ': the radiofrequency signal that the radiofrequency signal generation circuit generates is by the RF driven electrode to outgoing It penetrates, finger, which contacts the radiofrequency signal that the radiofrequency signal generation circuit generates after the RF driven electrode, first makes the enhancing electric The Partial charge of appearance is transferred to the multiplexing unit on the sense capacitance and corrective capacity and making the currently active row sensing unit The output of gain buffer is connected to the bucking electrode of the currently active row sensing unit, the multiple-sensing unit antenna array control Device exports third pulse signal to the currently active row sensing unit again, and the third pulse signal again refers to the multiplexing Capacitor, sense capacitance, enhancing capacitor and corrective capacity carry out equalizing charge；

Step S34 ': the multiple-sensing unit array control unit exports the second pulse signal of another fixed cycles number With third pulse signal to the currently active row sensing unit, the radiofrequency signal that the radiofrequency signal generation circuit generates passes through institute The radiofrequency signal that RF driven electrode launches outward identical fixed cycles number is stated, the currently active row sensing unit is made The voltage difference at multiplexing reference capacitance both ends gradually reduces, and the voltage difference at the multiplexing reference capacitance both ends is locked after circulation terminates It is fixed, wherein the M " power that the fixed cycles number is 2, the integer that M " is 4 to 16；The analog-to-digital conversion array will be described simultaneously Voltage differential signal is converted into the currently active collected finger print information of row sensing unit；

Step S35 ': the currently active collected finger print information of row sensing unit is passed to fingerprint image caching Device completes the fingerprint collecting process of the currently active row sensing unit.

Preferably, the step S4 ' is specifically included:

Step S41 ': the currently active row sensing unit is after completing initialization and fingerprint collecting process, the compound sense Cell array controller output the first correction timing is surveyed, by the initial value of the currently active row sensing unit, with reference to sensing unit Initial value, the digital analog converter the numerical value of input and host computer input be input to multiple-sensing unit deviation correction The sub- sensing unit correction for drift data of circuit counting, and the sub- sensing unit correction for drift data are stored in fingerprint image As in buffer；

Step S42 ': the second correction of multiple-sensing unit array control unit output timing, by effective row sense It surveys the collected finger print information of unit and subtracts the letter of the fingerprint image after the sub- sensing unit correction for drift data are corrected Breath；

Step S43 ': the information in fingerprint after the correction of the currently active row sensing unit is stored in the fingerprint image In buffer, the information in fingerprint after the correction is taken away under the control of host computer.

It can be seen from the above technical proposal that the present invention remains to solve above-mentioned finger, anti-interference, antistatic and detection Depth problem provides a kind of radio frequency and declines capacitive fingerprint acquisition chip, it is intended to is single by improving sensing on the basis of the prior art The structure and increase sensing unit distortion correction circuit of member realize the micro- capacitance detecting of finger, are resisted by special radio frequency method Fingerprint residues, other spots residual and the interference of other radio-frequency radiations, and the investigation depth by improving sensor can be to avoid quiet Discharge of electricity (Electro Static Discharge, abbreviation ESD) effect and will sensor insertion touch capacitance plate under.

Detailed description of the invention

Fig. 1 is the sensing unit electrical block diagram of fingerprint sensor in the prior art

Fig. 2 is the circuit structure diagram that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment

Fig. 3 is the encapsulating structure diagrammatic cross-section that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment

Fig. 4 is the sensing unit electrical block diagram that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment

Fig. 5 is that the multiple-sensing unit circuit structure that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment shows It is intended to

[symbol description in figure]

1, the sensing unit of the prior art

10, finger

11, the sense capacitance of the prior art

12, the fringing capacitance of the prior art

13, amplifier

14, reset switch

15, RF signal used in the prior art

2, radio frequency declines capacitive fingerprint acquisition chip

20, sensing unit array

201, sensing unit

202, with reference to sensing unit

21, sensing unit array control unit

22, column ADC array

221, analog-digital converter (ADC)

23., sensing unit distortion correction circuit

24, fingerprint image buffer

25, fingerprint image o controller

26, fingerprint image processor

27, digital analog converter (DAC)

28, RF signal generating circuit

29, RF driven electrode

3, fingerprint sensor cross section

30, insulating substrate

31, nonconductive adhesive

32a, RF driven electrode

32b, RF driven electrode

33, sensing unit

34, buffering spacer

35, insulating layer

40, sense capacitance

401, finger skin corium

402, sensing electrode

410,411,412,413 switching circuit

420, enhance capacitor

421, sensing unit deviation corrective capacity

422, mask capacitor

423, reference capacitance

430,431 power supply

44, amplifier

45, sensing unit control bus

50a, 50b sense capacitance

501, finger skin corium

502a, 502b sensing electrode

510a, 511a, 512a, 513a, 510b, 511b, 512b, 513b switching circuit

520a, 520b enhance capacitor

521a, 521b sensing unit deviation corrective capacity

522a, 522b mask capacitor

523, it is multiplexed reference capacitance

530a, 531a, 530b, 531b power supply

54, it is multiplexed amplifier

55a, 55b sensing unit control bus

Specific embodiment

Exemplary embodiment is described in detail in conjunction with the accompanying drawings, These characteristics of the invention and advantage will become brighter It is aobvious, in the accompanying drawings, is adopted between each attached drawing and similar element is designated with like reference numerals.The attached drawing is demonstration Rather than it is drawn to scale.

With reference to the accompanying drawing 2 to 5, specific embodiments of the present invention will be described in further detail.The present invention will lead to It crosses embodiment to be illustrated, but thinking of the invention is not limited to the embodiment of the present invention.

Referring to Fig. 2, Fig. 2 is that radio frequency of the present invention declines the electrical block diagram of capacitive fingerprint chip.As shown, should Radio frequency decline capacitive fingerprint chip 2 include two-dimentional sensing unit array 20 (for example, M*N two dimension sensing unit array), it is optional more A reference sensing unit 202 (for example, L refer to sensing unit), sensing unit array control unit 21, analog-to-digital conversion (column ADC) array 22, sensing unit distortion correction circuit 23, fingerprint image buffer 24, fingerprint image o controller 25, image Signal processor 26, digital analog converter 27, radio frequency (RF) signal generating circuit 28 and RF driven electrode 29.Wherein, it is encapsulating In structure, there is a layer insulating to directly overlay on two-dimentional sensing unit array 20 and optional multiple reference sensing units 202. Wherein, the integer that N is 1 to 150, the integer that M is 2 to 300, L are the integer less than N*M.

In the present embodiment, two-dimentional sensing unit array 20 is spliced to form by multiple sensing units 201, sensing unit array Controller 21 be used for provides be turned on and off sensing unit 201 needed for source bias switching signal and offer sensing unit Charge and discharge clock signal needed for 201；RF driven electrode 29 arrives the emission of radio frequency signals that RF signal generating circuit 28 generates Touch the finger of fingerprint sensor；Analog-to-digital conversion array 22 is made of side by side multiple analog-digital converters 221, by sensing unit The sense capacitance that array 20 detects is converted into fingerprint image gray value；Sensing unit distortion correction circuit 23, it is each for correcting Deviation between sensing unit；Fingerprint image buffer 24 is for storing the collected fingerprint gray scale of the currently active row sensing unit Deviation between value and each sensing unit；A series of timing and to acquisition needed for fingerprint image processor 26 generates acquisition fingerprint To finger print information do optimization processing；The control address that fingerprint image o controller 25 is inputted according to fingerprint image processor 26 Collected finger print information is output to fingerprint image processor 26；Also, fingerprint image processor 26 receives the fingerprint image As the fingerprint image data that o controller 25 is sent, according to the fingerprint image data judge its true or false and it is normal whether simultaneously Make corresponding processing.

Referring to Fig. 3, Fig. 3 is that radio frequency of the present invention declines the cross-sectional structure schematic diagram of capacitive fingerprint sensor chip.Such as Shown in figure, a kind of radio frequency provided by the invention decline capacitive fingerprint acquisition chip cross section 3 include multiple sensing units 33, it is more Insulating layer 35, nonconductive adhesive 31, insulating substrate 30 and RF driven electrode 32a, 32b on a sensing unit.Its In, which is closely glued by nonconductive adhesive 31 and insulating layer 35 and together, the insulating substrate 30 is usual Contact surface as finger；In the present embodiment, for the thickness of insulating substrate cross section 30 up to 1mm, nonconductive adhesive is transversal The thickness in face 31 is thinned to 20um or less as far as possible.It in addition to this, in the present embodiment, can also include RF driven electrode 32a, 32b and buffering spacer 34, RF driven electrode 32a, 32b are embeddable into insulating substrate 30.

Sensing unit circuit knot it should be noted that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment Structure can use the following two kinds embodiment.In example 1, it is illustrated in fig. 4 shown below, sensing unit 201 uses a reference Capacitor and an amplifier；And in example 2, it is illustrated in fig. 5 shown below, sensing unit 201 is by 2 compound sub- sensing units Composition, two sub- sensing units of Fig. 5 share a reference capacitance and an amplifier, and sensing unit shown in fig. 5 compares Fig. 4 Shown in the benefit of sensing unit be that amplifier and reference capacitance can be done greatly, and matching is more preferable, and the influence of parasitic capacitance is more It is small.

[embodiment one]

Referring to Fig. 4, Fig. 4 is the sensing unit circuit that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment Structural schematic diagram.As shown, each sensing unit 201 may include: the top-level metallic institute formed by integrated circuit technology The single sense electrode 402 and sense capacitance dielectric layer of formation, the sensed media layer is by the insulating layer structure on top-level metallic 401 At single sense electrode 401 and finger and sense capacitance dielectric layer form single sense capacitor 40.

In addition to this, each sensing unit 201 further include reference capacitance 423, activated amplifier 44, corrective capacity 421, Enhance capacitor 420, reference capacitance 423 and switching circuit 410,411,412,413.Wherein, by any metal of integrated circuit technology The single correcting electrode that layer is formed, the single correcting electrode and single sense electrode form single corrective capacity 421；By integrated electricity Metal layer except the technique top-level metallic of road is formed by single bucking electrode, the single bucking electrode and single sense electrode shape At single mask capacitor 422；Single enhancing electrode is formed by any metal layer of integrated circuit technology, this individually enhances electrode and list A sensing electrode forms single enhancing capacitor 420；4 switching circuits 410,411,412,413 form one group of switch control reference Capacitor 423, sense capacitance 40, enhancing capacitor 420 and corrective capacity 421 carry out charge and discharge and equalizing charge.

In the present embodiment, sensing unit distortion correction circuit 23 also comprising forward-backward counter array, multiplier array, Sensing unit deviation statistics circuit and sensing unit deviation correction factor counting circuit, wherein the forward-backward counter array Calculate the sensing unit 201 and the deviation with reference to sensing unit 202；The sensing unit deviation statistics circuit statistics is described partially The average value of poor absolute value；The sensing unit deviation correction factor counting circuit by the input of the digital analog converter 27 with it is upper The numerical value of position machine input and the average value of the absolute value of the bias carry out mapping calculation and obtain correction factor；The multiplier array The deviation is multiplied with the correction factor, exports result as the sensing unit correction for drift data.It is described to reflect The method for penetrating calculating are as follows: the correction factor is directly obtained by host computer, and the correction factor is directly equal to host computer and calculates The correction factor arrived；The method that host computer calculates correction factor is as follows:

K1=B*N1*E1/H1；

Wherein, K1 is the correction factor that host computer is calculated；

B is a fixed coefficient；

K2=B*N2*E2/H2；

Wherein, K2 is the correction factor that the chip is calculated；

B is a fixed coefficient；

H1 is that the statistics by testing the actual sensed unit deviation that a large amount of chips obtain inputted by host computer is put down Mean value；

It is base using the radio frequency of the said chip circuit capacitive fingerprint acquisition method that declines according to the circuit of above-mentioned acquisition chip Pass through charge pump principle in frequency signal generating circuit 28, RF driven electrode 29 and sensing unit with charge pump circuit structure Realize that the conversion of finger print information to electric signal can specifically comprise the following steps:

Step S1: when finger is placed on two-dimentional sensing unit array 20, the sensing unit array control unit 21 is selected Select effective row sensing unit of a line sensing unit in the two-dimentional sensing unit array 20 as current acquisition fingerprint；

Step S2: the currently active row sensing unit of ordered pair carries out when the output of sensing unit array control unit 21 initialization Initialization；

Step S3: when the sensing unit array control unit 21 exports fingerprint collecting the currently active row sensing unit of ordered pair into Row fingerprint collecting；

Step S4: it is single that the sensing unit array control unit 21 exports the currently active row sensing of finger print information timing ordered pair The collected finger print information of member is corrected；Finger print information after the correction of the currently active row sensing unit is taken away；

Step S5: the sensing unit array control unit 21 selects next line sensing unit having as current acquisition fingerprint Row sensing unit is imitated, sequence completes initialization, fingerprint collecting, finger print information correction and reads finger print information Four processes, until The sensing unit array control unit selects last line sensing unit as effective row sensing unit of current acquisition fingerprint, suitable Sequence completes initialization, fingerprint collecting, finger print information correction and reads finger print information Four processes.

In the present embodiment, above-mentioned steps S2 initializes acquisition timing and may include:

Step S21: first pulse signal of output of sensing unit array control unit 21 to the currently active row sensing unit, The pulse signal charges to the reference capacitance 423 of the currently active row sensing unit during pulse width, makes the reference capacitance 423 both ends accumulating values are the quantity of electric charge of C1*V1, and the C1 is the capacitance of reference capacitance, and the V1 is to charge to reference capacitance Voltage value；

Step S22: second pulse signal of output of sensing unit array control unit 21 to the currently active row sensing unit, The radiofrequency signal that the pulse signal and the radiofrequency signal generation circuit 28 generate makes the correction of the currently active row sensing unit Capacitor 421 discharges, and the quantity of electric charge at its both ends is made to become zero；The pulse signal makes the enhancing capacitor of the currently active row sensing unit 420 chargings make the quantity of electric charge of its both ends accumulating value C2*V2, and the C2 is the capacitance for enhancing capacitor, and the V2 is to enhancing The voltage value of capacitor charging；The pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S23: the output third pulse signal of sensing unit array control unit 21 to the currently active row sensing unit, The radiofrequency signal that the radiofrequency signal generation circuit 28 generates first makes the Partial charge for enhancing capacitor 420 be transferred to the correction electricity Hold upper 421 and the output of the unit gain buffer of the currently active row sensing unit is made to be connected to the currently active row sensing unit Bucking electrode, the third pulse signal make the reference capacitance 423, enhancing capacitor 420 and corrective capacity 421 carry out charge again Equilibrium, so that the quantity of electric charge at 423 both ends of the reference capacitance is reduced；

Step S24: the sensing unit array control unit 21 exports the second pulse signal and third of fixed cycles number For pulse signal to the currently active row sensing unit, the radiofrequency signal generation circuit 28 generates the radio frequency of identical fixed cycles number Signal, the second pulse signal and third pulse signal and the radiofrequency signal generation circuit 28 of the fixed cycles number generate Identical fixed cycles number radiofrequency signal make jointly effective row sensing unit 423 both ends of reference capacitance voltage difference Gradually reduce, the voltage difference at 423 both ends of reference capacitance is locked after circulation terminates, while the analog-to-digital conversion array 22 will The voltage differential signal is converted into the initialization value of the currently active row sensing unit；Wherein, the fixed cycles in initialization procedure Number may be configured as 2 N " power, the integer that N " is 2 to 8；

Step S25: the initialization value of the currently active row sensing unit is passed to fingerprint image buffer 24, completes to work as The initialization procedure of preceding effective row sensing unit.

In the present embodiment, above-mentioned steps S3, that is, fingerprint collecting timing may include:

Step S31: after initialization timing, the sensing unit array control unit 21 exports the first pulse signal again To the currently active row sensing unit, the pulse signal is during pulse width to the reference capacitance of the currently active row sensing unit 423 chargings, make 423 both ends of reference capacitance accumulate certain quantity of electric charge, certain quantity of electric charge can be with initialization The quantity of electric charge is identical；

Step S32: the sensing unit array control unit 21 exports the second pulse signal again and senses to the currently active row The radiofrequency signal that unit, the pulse signal and the radiofrequency signal generation circuit 28 generate makes the currently active row sensing unit Sense capacitance 40 and corrective capacity 421 discharge, and so that the quantity of electric charge at its both ends is become zero, the pulse signal senses the currently active row The enhancing capacitor 420 of unit charges, and makes the quantity of electric charge of its both ends accumulating value C2*V2, and wherein C2 is the capacitance for enhancing capacitor, V2 is to the voltage value of enhancing capacitor charging；The pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S33: the sensing unit array control unit 21 exports third pulse signal again and senses to the currently active row Unit, the radiofrequency signal that the radiofrequency signal generation circuit 28 generates are launched outward by the RF driven electrode 29, finger Radiofrequency signal with the radiofrequency signal with phase will be generated in finger skin corium by contacting after the RF driven electrode 29, described The radiofrequency signal that the radiofrequency signal and the skin corium that radiofrequency signal generation circuit 28 generates generate first makes to enhance capacitor 420 jointly Partial charge be transferred to 421 on the sense capacitance 40 and corrective capacity, the third pulse signal make again it is described with reference to electricity Hold 423, sense capacitance 40, enhancing capacitor 420 and corrective capacity 421 and carry out equalizing charge, so that 40 both ends of the reference capacitance The quantity of electric charge reduce；

Step S34: the sensing unit array control unit 21 export another fixed cycles number the second pulse signal and To the currently active row sensing unit, the radiofrequency signal that the radiofrequency signal generation circuit 28 generates passes through described third pulse signal RF driven electrode 29 launches outward the radiofrequency signal of identical fixed cycles number, the second pulse letter of the fixed cycles number Number and the radiofrequency signal of identical fixed cycles number that generates of third pulse signal and the radiofrequency signal generation circuit and described The radiofrequency signal for the identical fixed cycles number that finger skin corium generates makes the reference capacitance of effective row sensing unit jointly The voltage difference at 423 both ends gradually reduces, and the voltage difference at 423 both ends of reference capacitance is locked after circulation terminates, while described The voltage differential signal is converted into the currently active collected finger print information of row sensing unit by the column of analog-to-digital conversion battle array 22；Wherein institute State the M " power that fixed cycles number is 2, the integer that M " is 4 to 16；

Step S35: being passed to fingerprint image buffer 24 for the currently active collected finger print information of row sensing unit, Complete the fingerprint collecting process of the currently active row sensing unit.

In the present embodiment, above-mentioned steps S4 finger print information correction timing may include:

Step S41: the currently active row sensing unit is after completing initialization and fingerprint collecting process, the sensing unit battle array Column controller 21 output first correction timing, by the initial value of the currently active row sensing unit, with reference to sensing unit initial value, The numerical value of the input of digital analog converter and host computer input is input to the sensing unit distortion correction circuit and calculates sensing unit Correction for drift data, and the sensing unit correction for drift data are stored in fingerprint image buffer 24；

Step S42: the second correction of sensing unit array control unit output timing adopts effective row sensing unit The finger print information collected subtracts the information in fingerprint after the sensing unit correction for drift data are corrected；

Step S43: the information in fingerprint after the correction of the currently active row sensing unit is stored in the fingerprint image and is delayed In storage 24, the information in fingerprint after the correction is taken away under the control of host computer.

[embodiment two]

Referring to Fig. 5, Fig. 5 is the multiple-sensing unit that radio frequency of the present invention declines in capacitive fingerprint sensor chip embodiment Electrical block diagram.As shown,

Each multiple-sensing unit 201 includes optional multiple sub- sensing unit structures；By the top layer gold of integrated circuit technology Category is formed by two sensing electrodes 502a and 502b；Sense capacitance dielectric layer (not shown), by integrated circuit technology top layer Insulating layer, nonconductive adhesive and insulating substrate on metal are constituted, two sensing electrode 502a and 502b and finger corium Layer 501 and sense capacitance dielectric layer form sense capacitance 50a and 50b；By two sensing electrode 502a and 502b and integrated circuit Two enhancing capacitors 520a and 520b that other metal electrodes of technique are formed, two sensing unit deviation corrective capacity 521a and 521b and two mask capacitor 522a and 522b；It is multiplexed reference capacitance 523；It is multiplexed amplifier 54 of having chance with；Multiple switch circuit 510a, 510b, 511a, 511b, 512a, 512b, 513a and 513b, for controlling enhancing capacitor 520a, sense capacitance 50a, sense It surveys unit corrective capacity 521a and multiplexing reference capacitance 523 carries out charge and discharge and equalizing charge, or control enhancing capacitor 520b, sense It surveys capacitor 50b, sensing unit corrective capacity 521b and multiplexing reference capacitance 523 carries out charge and discharge and equalizing charge.

K1=B*N1*E1/H1；

Wherein, K1 is the correction factor that host computer is calculated；

B is a fixed coefficient；

K2=B*N2*E2/H2；

Wherein, K2 is the correction factor that the chip is calculated；

B is a fixed coefficient；

According to the circuit of above-mentioned acquisition chip, using the radio frequency of said chip circuit to decline capacitive fingerprint acquisition method can be with Specifically comprise the following steps:

Step S1 ': when finger 10 is placed on two-dimentional sensing unit array 20, multiple-sensing unit array control unit 21 Select the sub- sensing unit of a line sensing unit 201 in two-dimentional sensing unit array as effective row of current acquisition fingerprint Sensing unit；

Step S2 ': ordered pair the currently active row sensing unit when the output initialization of multiple-sensing unit array control unit 21 It is initialized；

Step S3 ': the currently active row sensing of ordered pair is single when multiple-sensing unit array control unit 21 exports fingerprint collecting Member carries out fingerprint collecting；

Step S4 ' multiple-sensing unit array control unit 21 is to the currently active collected finger print information of row sensing unit It is corrected；

Step S6 ' multiple-sensing unit array control unit 21 successively selects another sub- sensing unit of effective row sensing unit As the currently active row sensing unit, repeat step S2 '~step S5 ' until complete the initialization of all sub- sensing units, Fingerprint collecting, finger print information correction and finger print information read Four processes；

Step S7 ' sensing unit array control unit successively selects the next line sensing unit in two-dimentional sensing unit array Effective row sensing unit of the sub- sensing unit as current acquisition fingerprint repeats step S2 '~step S6 ' until completing entire Two-dimentional sensing unit array reads Four processes to the initialization of fingerprint, fingerprint collecting, finger print information correction and finger print information.

In the present embodiment, above-mentioned steps S2 ' is that sub- sensing unit initialization acquisition timing specifically includes:

Step S21 ': the multiple-sensing unit array control unit 21 exports the first pulse signal to the currently active row sense Unit is surveyed, the pulse signal charges to the multiplexing reference capacitance 523 of the currently active row sensing unit during pulse width, Making the quantity of electric charge of the multiplexing 523 both ends accumulating value C1*V1 of reference capacitance, the C1 is the capacitance for being multiplexed reference capacitance, The V1 is the voltage value to charge to multiplexing reference capacitance；

Step S22 ': the multiple-sensing unit array control unit 21 exports the second pulse signal to the currently active row sense Unit is surveyed, the radiofrequency signal that the pulse signal and the radiofrequency signal generation circuit 28 generate keeps the currently active row sensing single The corrective capacity electric discharge 521a or 521b of member, makes the quantity of electric charge at its both ends go to zero；The pulse signal makes the currently active row Enhancing the capacitor 520a or 520b of sensing unit charge, and make the quantity of electric charge of its both ends accumulating value C2*V2, and the C2 is enhancing electricity The capacitance of appearance, the V2 are to the voltage value of enhancing capacitor charging；The pulse signal makes the current potential at mask capacitor both ends all For V2；

Step S23 ': the multiple-sensing unit array control unit 21 exports third pulse signal to the currently active row sense Survey unit, the radiofrequency signal that the radiofrequency signal generation circuit generates first make effective row sensing unit enhancing capacitor 520a or The Partial charge of 520b is transferred on the corrective capacity 521a or 521b of effective row sensing unit, the third pulse letter Number make enhancing the capacitor 520a or 520b and corrective capacity 521a of the multiplexing reference capacitance 523, effective row sensing unit again Or 521b carries out equalizing charge, so that the quantity of electric charge at multiplexing 523 both ends of reference capacitance is reduced；

Step S24 ': the multiple-sensing unit array control unit 21 export fixed cycles number the second pulse signal and For third pulse signal to the currently active row sensing unit, the radiofrequency signal generation circuit 28 generates identical fixed cycles number Radiofrequency signal, the second pulse signal and third pulse signal of the fixed cycles number and the radiofrequency signal generation circuit The radiofrequency signal of the identical fixed cycles number generated makes 523 liang of multiplexing reference capacitance of effective row sensing unit jointly The voltage difference at end gradually reduces, and the voltage difference at multiplexing 523 both ends of reference capacitance is locked after circulation terminates, while the mould The voltage differential signal is converted into the initialization value of the currently active row sensing unit by number conversion array 22；Wherein, it initializes Fixed cycles number in the process may be configured as 2 Nth power, the integer that N is 2 to 8；

Step S25 ': the initialization value of the currently active row sensing unit is passed to the fingerprint image buffer 24, complete the initialization procedure of the currently active row sensing unit.

In the present embodiment, above-mentioned steps S3 ' is that sub- sensing unit fingerprint collecting timing specifically includes:

Step S31 ': after initialization timing, the multiple-sensing unit array control unit 21 exports the first arteries and veins again Signal is rushed to the currently active row sensing unit, the pulse signal is during pulse width to the currently active row sensing unit It is multiplexed reference capacitance 523 to charge, multiplexing 523 both ends of reference capacitance is made to accumulate certain quantity of electric charge, these quantities of electric charge can be with It is identical with the quantity of electric charge of initialization；

Step S32 ': the multiple-sensing unit array control unit 21 exports the second pulse signal to the currently active row again The radiofrequency signal that sub- sensing unit, the pulse signal and the radiofrequency signal generation circuit 28 generate makes the currently active row sense Sense capacitance 50a or 50b and corrective capacity 521a or the 521b electric discharge for surveying unit, make the quantity of electric charge at its both ends go to zero, described Pulse signal makes enhancing the capacitor 520a or 520b of the currently active row sensing unit charge, and makes its both ends accumulating value C2*V2 The quantity of electric charge, wherein C2 be enhance capacitor capacitance, V2 be capacitor charging to enhancing voltage value；The pulse signal makes to shield The current potential for covering capacitor both ends is all V2；

Step S33 ': the multiple-sensing unit array control unit 21 exports third pulse signal to the currently active row again Sub- sensing unit, the radiofrequency signal that the radiofrequency signal generation circuit 28 generates is by the RF driven electrode 29 to outgoing It penetrates, finger will be believed with the radiofrequency signal with the radio frequency of phase after contacting the RF driven electrode 29 in the generation of finger skin corium Number, the radiofrequency signal that the radiofrequency signal and the skin corium that the radiofrequency signal generation circuit 28 generates generate first makes effectively jointly The Partial charge of the enhancing capacitor of the sub- sensing unit of row is transferred to the sense capacitance 50a or 50b of effective row sensing unit On corrective capacity 521a or 521b, the third pulse signal make again the multiplexing reference capacitance 523, sense capacitance 50a or 50b, enhancing capacitor 520a or 520b and corrective capacity 521a or 521b carry out equalizing charge, so that the multiplexing reference capacitance The quantity of electric charge at 523 both ends is reduced；

Step S34 ': the multiple-sensing unit array control unit 21 exports the second pulse letter of another fixed cycles number Number and third pulse signal arrive the currently active row sensing unit, the radiofrequency signal that the radiofrequency signal generation circuit 28 generates is led to Cross the radiofrequency signal that the RF driven electrode 29 launches outward identical fixed cycles number, the second of the fixed cycles number The radiofrequency signal for the identical fixed cycles number that pulse signal and third pulse signal are generated with the radiofrequency signal generation circuit And the radiofrequency signal of the identical fixed cycles number of the finger skin corium generation makes effective row sensing unit jointly The voltage difference at multiplexing 523 both ends of reference capacitance gradually reduces, after circulation terminates the voltage difference at multiplexing 523 both ends of reference capacitance It is locked, while the voltage differential signal is converted into the currently active row sensing unit and collected by the analog-to-digital conversion array 22 Finger print information；Wherein M " the power that the fixed cycles number is 2, the integer that M " is 4 to 16；

Step S35 ': the currently active collected finger print information of row sensing unit is passed to fingerprint image buffer 24, complete the fingerprint collecting process of the currently active row sensing unit.

In the present embodiment, above-mentioned steps S4 ' is that finger print information correction timing specifically includes:

Step S41 ': the currently active row sensing unit is after completing initialization and fingerprint collecting process, the compound sense The output of cell array controller 21 first correction timing is surveyed, by the initial value of the currently active row sensing unit 201, with reference to sensing It is inclined that the numerical value of the initial value of unit 202, the input of the digital analog converter 27 and host computer input is input to the sensing unit Poor correcting circuit 23 calculates sub- sensing unit correction for drift data, and the sub- sensing unit correction for drift data are stored In fingerprint image buffer；

Step S42 ': second correction of the output of multiple-sensing unit array control unit 21 timing, by effective row The collected finger print information of sensing unit subtracts the fingerprint image after the sub- sensing unit correction for drift data are corrected Information；

Step S43 ': the information in fingerprint after the correction of the currently active row sensing unit is stored in the fingerprint image In buffer 24, the information in fingerprint under the control of host computer after the correction is taken away.

Above-described to be merely a preferred embodiment of the present invention, the patent that the embodiment is not intended to limit the invention is protected Range is protected, therefore all with the variation of equivalent structure made by specification and accompanying drawing content of the invention, similarly should be included in In protection scope of the present invention.

Claims

The capacitive fingerprint acquisition chip 1. a kind of radio frequency declines characterized by comprising

L refer to sensing unit；

The two-dimentional sensing unit array that M*N sensing unit is formed；

Radiofrequency signal generation circuit, to generate radiofrequency signal；

RF driven electrode, the emission of radio frequency signals that the radiofrequency signal generation circuit is generated is to touching fingerprint sensor Finger；Further include:

Sensing unit array control unit, for provide be turned on and off sensing unit needed for source bias switching signal and mention For charge and discharge clock signal needed for sensing unit；

Analog-to-digital conversion array is made of side by side N number of analog-digital converter, the sense that the sensing unit array control unit is detected It surveys capacitor and is converted into fingerprint image gray value；

Sensing unit distortion correction circuit corrects each sensing list as benchmark with reference to the collected data of sensing unit using L Deviation between member；

Fingerprint image buffer is used to store the fingerprint image sum of the grayscale values sensing unit deviation correction number currently converted According to；

Digital analog converter controls the gain of the analog-to-digital conversion array；

Fingerprint image o controller, to transmission fingerprint image data；

Image-signal processor receives the fingerprint image data that the fingerprint image o controller is sent, according to the finger Print image data judge its true or false and it is normal whether and make corresponding processing, wherein the integer that N is 1 to 150, M are 2 to arrive 300 integer, L are the integer less than N*M, are directly covered in the insulating layer on acquisition chip circuit as the sensing unit The dielectric layer of middle sense capacitance.
The capacitive fingerprint acquisition chip 2. radio frequency according to claim 1 declines, which is characterized in that the two dimension sensing unit Each of array sensing unit includes:

Single sense electrode is formed by by the top-level metallic of integrated circuit technology；

Sense capacitance dielectric layer, by the insulating layer structure with a thickness of 0.1um~150um being directly covered on top-level metallic At the single sense electrode and finger and sense capacitance dielectric layer form single sense capacitor；

Reference capacitance；

Activated amplifier, is connected to unit gain buffer, and input is passed through by switch connection sensing electrode, output Switch connection bucking electrode；

Single bucking electrode is formed by by the metal layer except integrated circuit technology top-level metallic, the single bucking electrode with Single sense electrode forms single mask capacitor；

The single correcting electrode formed by any metal layer of integrated circuit technology, the single correcting electrode and single sense electrode Form single corrective capacity；

The single enhancing electrode formed by any metal layer of integrated circuit technology, the single enhancing electrode and single sense electrode Single enhancing capacitor is formed, enhancing capacitor is for enhancing collection effect；And

Multiple switch circuit, control reference capacitance, sense capacitance, enhancing capacitor and corrective capacity carry out charge and discharge and charge is equal Weighing apparatus.
The capacitive fingerprint acquisition chip 3. radio frequency according to claim 1 declines, which is characterized in that the sensing unit deviation Correcting circuit also includes forward-backward counter array, multiplier array, sensing unit deviation statistics circuit and sensing unit deviation Correction factor counting circuit, wherein

Sensing unit described in the forward-backward counter array computation and the deviation with reference to sensing unit；

The sensing unit deviation statistics circuit counts the average value of the absolute value of the bias；

The numerical value that the sensing unit deviation correction factor counting circuit inputs the input of the digital analog converter and host computer And the average value of the absolute value of the bias carries out mapping calculation and obtains correction factor；

The deviation is multiplied by the multiplier array with the correction factor, exports result as the sensing unit deviation The correction data of correcting circuit.
4. a kind of declined the fingerprint collecting method of capacitive fingerprint acquisition chip using the radio frequency any in claim 1,2 or 3, It is characterized in that, the fingerprint collecting method is based on the radiofrequency signal generation circuit, the RF driven electrode and has electricity The sensing unit of lotus pump circuit structure realizes the conversion of finger print information to electric signal by charge pump principle, comprising:

Step S1: when finger is placed on two-dimentional sensing unit array, the sensing unit array control unit selection described two Tie up effective row sensing unit of a line sensing unit as current acquisition fingerprint in sensing unit array；

Step S2: the sensing unit array control unit initializes the currently active row sensing unit；

Step S3: the sensing unit array control unit carries out fingerprint collecting to the currently active row sensing unit；

Step S4: the sensing unit array control unit carries out school to the currently active collected finger print information of row sensing unit Just；Finger print information after the correction of the currently active row sensing unit is taken away；

Step S5: the sensing unit array control unit selects next line sensing unit as effective row sense of current acquisition fingerprint Unit is surveyed, sequence completes initialization, fingerprint collecting, finger print information correction and reads finger print information Four processes, until the sense Effective row sensing unit that cell array controller selects last line sensing unit as current acquisition fingerprint is surveyed, sequence is completed Initialization, fingerprint collecting, finger print information correction and reading finger print information Four processes.
5. fingerprint collecting method according to claim 4, which is characterized in that the step S2 is specifically included:

Step S21: the sensing unit array control unit exports the first pulse signal to the currently active row sensing unit, and described the One pulse signal charges to the reference capacitance of the currently active row sensing unit during pulse width, makes reference capacitance both ends product The quantity of electric charge that tired value is C1*V1, the C1 are the capacitance of reference capacitance, and the V1 is the voltage value to charge to reference capacitance；

Step S22: the sensing unit array control unit exports the second pulse signal to the currently active row sensing unit, and described the The radiofrequency signal that two pulse signals and the radiofrequency signal generation circuit generate makes the corrective capacity of the currently active row sensing unit Electric discharge, makes the quantity of electric charge at its both ends go to zero；Second pulse signal fills the enhancing capacitor of the currently active row sensing unit Electricity makes the quantity of electric charge of its both ends accumulating value C2*V2, and the C2 is the capacitance for enhancing capacitor, and the V2 is to give enhancing capacitor The voltage value of charging；Second pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S23: the radiofrequency signal that the radiofrequency signal generation circuit generates first makes the Partial charge transfer of the enhancing capacitor On to the corrective capacity and the output of the unit gain buffer of the currently active row sensing unit is made to be connected to the currently active row The bucking electrode of sensing unit, the sensing unit array control unit export third pulse signal and sense list to the currently active row Member, the third pulse signal make the reference capacitance, enhancing capacitor and corrective capacity carry out equalizing charge again；

Step S24: the second pulse signal and third pulse letter of the sensing unit array control unit output fixed cycles number Number the currently active row sensing unit is arrived, the radiofrequency signal generation circuit generates the radiofrequency signal of identical fixed cycles number, institute The second pulse signal and third pulse signal for stating fixed cycles number generate identical solid with the radiofrequency signal generation circuit The radiofrequency signal for determining cycle-index reduces the voltage difference at the reference capacitance both ends of presently described effective row sensing unit gradually, The voltage difference at the reference capacitance both ends is locked after circulation terminates, wherein the fixed cycles number setting in initialization procedure For 2 N " power, the integer that N " is 2 to 8；The voltage differential signal is converted into the currently active by the analog-to-digital conversion array simultaneously The initialization value of row sensing unit；

Step S25: the initialization value of the currently active row sensing unit is passed to fingerprint image buffer, is completed the currently active The initialization procedure of row sensing unit.
6. fingerprint collecting method according to claim 4, which is characterized in that the step S3 is specifically included:

Step S31: after initialization timing, the sensing unit array control unit exports the first pulse signal to currently again Effective row sensing unit, first pulse signal fill the reference capacitance of the currently active row sensing unit during pulse width Electricity, makes the reference capacitance both ends accumulate certain quantity of electric charge, and certain quantity of electric charge is identical with the quantity of electric charge of initialization；

Step S32: the sensing unit array control unit exports the second pulse signal to the currently active row sensing unit, institute again Stating the radiofrequency signal that the second pulse signal and the radiofrequency signal generation circuit generate makes the sensing of the currently active row sensing unit Capacitor and corrective capacity electric discharge, make the quantity of electric charge at its both ends become zero, second pulse signal makes the currently active row sensing unit Enhancing capacitor charging, make the quantity of electric charge of its both ends accumulating value C2*V2, wherein C2 be enhance capacitor capacitance, V2 be to Enhance the voltage value of capacitor charging；Second pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S33: the radiofrequency signal that the radiofrequency signal generation circuit generates is launched outward by the RF driven electrode, hand The radiofrequency signal that the radiofrequency signal generation circuit generates after RF driven electrode described in abutment first makes the enhancing capacitor Partial charge is transferred to the unit gain buffer on the sense capacitance and corrective capacity and making the currently active row sensing unit Output be connected to the bucking electrode of the currently active row sensing unit, the sensing unit array control unit exports third arteries and veins again Signal is rushed to the currently active row sensing unit, the third pulse signal makes the reference capacitance, sense capacitance, enhancing capacitor again Equalizing charge is carried out with corrective capacity；

Step S34: the sensing unit array control unit exports the second pulse signal and third arteries and veins of another fixed cycles number Signal is rushed to the currently active row sensing unit, the radiofrequency signal that the radiofrequency signal generation circuit generates passes through the radio-frequency driven Electrode launches outward the radiofrequency signal of identical fixed cycles number, makes the reference capacitance both ends of the currently active row sensing unit Voltage difference gradually reduce, the voltage difference at the reference capacitance both ends is locked after circulation terminates, wherein the fixed cycles time M " the power that number is 2, the integer that M " is 4 to 16；The voltage differential signal is converted into currently by the analog-to-digital conversion array simultaneously The collected finger print information of effective row sensing unit；

Step S35: the currently active collected finger print information of row sensing unit is passed to fingerprint image buffer, completes to work as The fingerprint collecting process of preceding effective row sensing unit.
7. fingerprint collecting method according to claim 4, which is characterized in that the step S4 is specifically included:

Step S41: the currently active row sensing unit is after completing initialization and fingerprint collecting process, the sensing unit array control The first correction of device output timing processed, by the initial value of the currently active row sensing unit, the initial value with reference to sensing unit, the number It is inclined that the numerical value of the input of mode converter and host computer input is input to the sensing unit distortion correction circuit calculating sensing unit The correction data of difference, and the sensing unit correction for drift data are stored in fingerprint image buffer；

Step S42: the second correction of sensing unit array control unit output timing adopts the currently active row sensing unit The finger print information collected subtracts the information in fingerprint after the sensing unit correction for drift data are corrected；

Step S43: the information in fingerprint after the correction of the currently active row sensing unit is stored in the fingerprint image buffer In, the information in fingerprint after the correction is taken away under the control of host computer.
The capacitive fingerprint acquisition chip 8. a kind of radio frequency declines characterized by comprising

L refer to sensing unit；

The two-dimentional sensing unit array that M*N multiple-sensing unit is formed；The multiple-sensing unit is felt by two compound sons Survey unit composition；

Radiofrequency signal generation circuit, to generate radiofrequency signal；

RF driven electrode, the emission of radio frequency signals that the radiofrequency signal generation circuit is generated is to touching fingerprint sensor Finger；Further include:

Multiple-sensing unit array control unit, for provide be turned on and off multiple-sensing unit needed for source bias switch Charge and discharge clock signal needed for signal and offer multiple-sensing unit；

Analog-to-digital conversion array is made of side by side N number of analog-digital converter, and the multiple-sensing unit array control unit is detected Sense capacitance be converted into fingerprint image gray value；

Multiple-sensing unit distortion correction circuit is corrected as benchmark using L with reference to the collected data of sensing unit each multiple Close the deviation between sensing unit；

Fingerprint image buffer is used to store the fingerprint image sum of the grayscale values multiple-sensing unit deviation school currently converted Correction data；

Digital analog converter controls the gain of the analog-to-digital conversion array；

Fingerprint image o controller, to transmission fingerprint image data；

Image-signal processor receives the fingerprint image data that the fingerprint image o controller is sent, according to the finger Print image data judge its true or false and it is normal whether and make corresponding processing, wherein the integer that N is 1 to 150, M are 2 to arrive 300 integer, L are the integer less than N*M, are directly covered in the insulating layer on acquisition chip circuit as the compound sensing The dielectric layer of sense capacitance in unit.
9. fingerprint collecting chip according to claim 8, which is characterized in that

Each of two dimension sensing unit array multiple-sensing unit includes:

A sensing electrode of N ' is formed by by the top-level metallic of integrated circuit technology；

Sense capacitance dielectric layer, by the insulating layer with a thickness of 0.1um~150um being directly covered on the top-level metallic It constitutes；

A sensing electrode of N ' and finger and sense capacitance dielectric layer form a sense capacitance of N '；

It is multiplexed reference capacitance；

By a bucking electrode of the formed N ' of metal layer except integrated circuit technology top-level metallic, a bucking electrode of the N ' and N ' A sensing electrode forms a mask capacitor of N '；

A correcting electrode of N ' formed by any metal layer of integrated circuit technology, a correcting electrode of the N ' and a sensing electrode of N ' Form a corrective capacity of N '；

By a enhancing electrode of the formed N ' of any metal layer of integrated circuit technology, a enhancing electrode of the N ' and a sensing electrode of N ' A enhancing capacitor of N ' is formed, enhancing capacitor is for enhancing collection effect；

N ' organizes switching circuit；

It is multiplexed activated amplifier, is connected to multiplexing unit gain buffer, input passes through N ' group switch connection a sensing of N ' Electrode, output pass through a switch connection a bucking electrode of N ' of N '；

A sensing electrode of the N ', sense capacitance dielectric layer, multiplexing reference capacitance, a mask capacitor of N ', a corrective capacity of N ', N ' A enhancing capacitor, N ' group switching circuit and multiplexing activated amplifier constitute a sub- sensing unit of N '；Wherein, each sub- sensing unit Include: a sensing electrode, sense capacitance dielectric layer, a mask capacitor, a corrective capacity, an enhancing capacitor, one group Switch, multiplexing reference capacitance and multiplexing activated amplifier, wherein multiplexing reference capacitance and multiplexing activated amplifier are sharing unit；

The multiplexing reference capacitance and multiplexing activated amplifier are placed on by under a sensing electrode institute forming region of the N ' Side is placed in by the side of a sensing electrode institute forming region of the N ', the edge of the marginal edge position from the region The vertical range of position is less than 500um.
10. fingerprint collecting chip according to claim 8, which is characterized in that the multiple-sensing unit deviation correction electricity Road also include forward-backward counter array, multiplier array, sensing unit deviation statistics circuit and sensing unit deviation correction because Sub- counting circuit, wherein

Multiple-sensing unit described in the forward-backward counter array computation and the deviation with reference to sensing unit；

The sensing unit deviation statistics circuit counts the average value of the absolute value of the bias；

The numerical value that the sensing unit deviation correction factor counting circuit inputs the input of the digital analog converter and host computer And the average value of the absolute value of the bias carries out mapping calculation and obtains correction factor；

The deviation is multiplied by the multiplier array with the correction factor, exports result as the multiple-sensing unit The correction data of distortion correction circuit.
11. a kind of declined the fingerprint collecting side of capacitive fingerprint acquisition chip using the radio frequency any in claim 8,9 or 10 Method, which is characterized in that the fingerprint collecting method is based on the radiofrequency signal generation circuit, the RF driven electrode and has The multiple-sensing unit of charge pump circuit structure realizes the conversion of finger print information to electric signal by charge pump principle, comprising:

Step S1 ' multiple-sensing unit array control unit selects the son of a line multiple-sensing unit in two-dimentional sensing unit array Effective row sensing unit of the sensing unit as current acquisition fingerprint；

Step S2 ' multiple-sensing unit array control unit initializes the currently active row sensing unit；

The currently active row sensing unit of step S3 ' multiple-sensing unit array control unit carries out fingerprint collecting；

Step S4 ' multiple-sensing unit array control unit carries out school to the currently active collected finger print information of row sensing unit Just；

Finger print information after the currently active row sensing unit correction of step S5 ' reading；

Step S6 ' multiple-sensing unit array control unit successively selects another sub- sensing unit of effective row sensing unit as working as Preceding effective row sensing unit repeats step S2 '~step S5 ' until completing the initialization of all sub- sensing units, fingerprint is adopted Collection, finger print information correction and finger print information read Four processes；

Step S7 ' multiple-sensing unit array control unit successively selects the compound sensing of next line in two-dimentional sensing unit array single Effective row sensing unit of the sub- sensing unit of member as current acquisition fingerprint, repeats step S2 '~step S6 ' until completing Entire two dimension sensing unit array reads four mistakes to the initialization of fingerprint, fingerprint collecting, finger print information correction and finger print information Journey.
12. fingerprint collecting method according to claim 11, which is characterized in that the step S2 ' is specifically included:

Step S21 ': the multiple-sensing unit array control unit exports the first pulse signal and senses list to the currently active row Member, first pulse signal make the multiplexing reference capacitance of the currently active row sensing unit charge during pulse width, make Its both ends accumulating value is the quantity of electric charge of C1*V1, and the C1 is the capacitance for being multiplexed reference capacitance, and the V1 is to multiplexing with reference to electricity The voltage value of capacity charge；

Step S22 ': the multiple-sensing unit array control unit exports the second pulse signal and senses list to the currently active row The radiofrequency signal that member, second pulse signal and the radiofrequency signal generation circuit generate makes the currently active row sensing unit Corrective capacity electric discharge, so that the quantity of electric charge at its both ends is gone to zero；Second pulse signal makes the currently active row sensing unit Enhancing capacitor charging, make the quantity of electric charge of its both ends accumulating value C2*V2, the C2 is the capacitance for enhancing capacitor, the V2 For the voltage value to enhancing capacitor charging；Second pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S23 ': the radiofrequency signal that the radiofrequency signal generation circuit generates first makes the Partial charge transfer of the enhancing capacitor On to the corrective capacity and it is connected to the output of the multiplexing unit gain buffer of the currently active row sensing unit currently The bucking electrode of effective row sensing unit, the multiple-sensing unit array control unit export third pulse signal to currently having The sub- sensing unit of effect row, the third pulse signal make the multiplexing reference capacitance, enhancing capacitor and corrective capacity carry out electricity again Lotus is balanced；

Step S24 ': the second pulse signal and third arteries and veins of the multiple-sensing unit array control unit output fixed cycles number Signal is rushed to the currently active row sensing unit, the radiofrequency signal generation circuit generates the radio frequency letter of identical fixed cycles number Number, the phase that the second pulse signal and third pulse signal of the fixed cycles number are generated with the radiofrequency signal generation circuit With the radiofrequency signal of fixed cycles number, make the voltage difference at the multiplexing reference capacitance both ends of the currently active row sensing unit Gradually reduce, the voltage difference at the multiplexing reference capacitance both ends is locked after circulation terminates, wherein the fixation in initialization procedure Cycle-index is set as 2 N " power, the integer that N " is 2 to 8；The analog-to-digital conversion array turns the voltage differential signal simultaneously Change the initialization value of the currently active row sensing unit into；

Step S25 ': being passed to fingerprint image buffer for the initialization value of the currently active row sensing unit, completes current The initialization procedure of effective row sensing unit.
13. fingerprint collecting method according to claim 11, which is characterized in that the step S3 ' is specifically included:

Step S31 ': after initialization timing, the multiple-sensing unit array control unit exports the first pulse signal again To the currently active row sensing unit, first pulse signal makes the currently active row sensing unit during pulse width It is multiplexed reference capacitance charging, so that the multiplexing reference capacitance both ends is accumulated certain quantity of electric charge, certain quantity of electric charge is with first The quantity of electric charge of beginningization is identical；

Step S32 ': the multiple-sensing unit array control unit exports the second pulse signal again and senses to the currently active row The radiofrequency signal that unit, second pulse signal and the radiofrequency signal generation circuit generate keeps the currently active row sensing single Sense capacitance and the corrective capacity electric discharge of member, make the quantity of electric charge at its both ends go to zero, second pulse signal makes the currently active The enhancing capacitor charging of the sub- sensing unit of row, makes the quantity of electric charge of its both ends accumulating value C2*V2, and wherein C2 is the electricity for enhancing capacitor Capacitance, V2 are to the voltage value of enhancing capacitor charging；Second pulse signal makes the current potential at mask capacitor both ends all be V2；

Step S33 ': the radiofrequency signal that the radiofrequency signal generation circuit generates is launched outward by the RF driven electrode, Finger, which contacts the radiofrequency signal that the radiofrequency signal generation circuit generates after the RF driven electrode, first makes the enhancing capacitor Partial charge be transferred on the sense capacitance and corrective capacity and increase the multiplexing unit of the currently active row sensing unit The output of beneficial buffer is connected to the bucking electrode of the currently active row sensing unit, the multiple-sensing unit array control unit Output third pulse signal makes the multiplexing with reference to electricity again to the currently active row sensing unit, the third pulse signal again Appearance, sense capacitance, enhancing capacitor and corrective capacity carry out equalizing charge；

Step S34 ': the multiple-sensing unit array control unit exports the second pulse signal and of another fixed cycles number Three pulse signals to the currently active row sensing unit, penetrated by described by the radiofrequency signal that the radiofrequency signal generation circuit generates Frequency driving electrodes launch outward the radiofrequency signal of identical fixed cycles number, make the multiplexing of the currently active row sensing unit The voltage difference at reference capacitance both ends gradually reduces, and the voltage difference at the multiplexing reference capacitance both ends is locked after circulation terminates, Described in fixed cycles number be 2 M " power, M " be 4 to 16 integer；The analog-to-digital conversion array is by the voltage simultaneously Difference signal is converted into the currently active collected finger print information of row sensing unit；

Step S35 ': being passed to fingerprint image buffer for the currently active collected finger print information of row sensing unit, complete At the fingerprint collecting process of the currently active row sensing unit.
14. fingerprint collecting method according to claim 11, which is characterized in that the step S4 ' is specifically included:

Step S41 ': for the currently active row sensing unit after completing initialization and fingerprint collecting process, the compound sensing is single Element array controller output the first correction timing, by the initial value of the currently active row sensing unit, with reference to the first of sensing unit The numerical value of initial value, the input of the digital analog converter and host computer input is input to the multiple-sensing unit distortion correction circuit Sub- sensing unit correction for drift data are calculated, and the sub- sensing unit correction for drift data are stored in fingerprint image and are delayed In storage；

Step S42 ': the second correction of multiple-sensing unit array control unit output timing, by the currently active row sense It surveys the collected finger print information of unit and subtracts the letter of the fingerprint image after the sub- sensing unit correction for drift data are corrected Breath；

Step S43 ': the information in fingerprint after the correction of the currently active row sensing unit is stored in the fingerprint image and is cached In device, the information in fingerprint after the correction is taken away under the control of host computer.