CN105608437A - Hybrid fingerprint acquisition chip and acquisition method - Google Patents
Hybrid fingerprint acquisition chip and acquisition method Download PDFInfo
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- CN105608437A CN105608437A CN201510999701.5A CN201510999701A CN105608437A CN 105608437 A CN105608437 A CN 105608437A CN 201510999701 A CN201510999701 A CN 201510999701A CN 105608437 A CN105608437 A CN 105608437A
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1306—Sensors therefor non-optical, e.g. ultrasonic or capacitive sensing
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/1382—Detecting the live character of the finger, i.e. distinguishing from a fake or cadaver finger
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Abstract
The invention provides a multi-mode fingerprint acquisition chip and acquisition method. The chip comprises a two-dimensional sensing unit array with M rows and N columns, a passivation insulating layer which directly covers the two-dimensional sensing unit array, a polyester composite insulating layer which covers the passivation insulating layer, a scanning controller which allows M sensing units to scan effectively from top to bottom or from bottom to top, a driving circuit which provides a time sequence control signal needed by a sensing unit, an ADC array which is configured next to or above a sensing electrode, a buffer shift register, a mode control circuit which controls the working mode of the chip, an antenna metal frame, an RF driving circuit, a detection electrode for detecting a fake finger and a fake finger detection electrode. The parameter of the circuit is controlled through a host machine configuration mode, the multi-mode finger detection and collection can be realized by the chip, different working modes are selected according to different application occasions, thus the chip is more flexible and convenient, a fake finger can be effectively rejected through the fake finger detection electrode, thus the security of fingerprint information is improved.
Description
Technical field
The present invention relates to IC design field, relate in particular to a kind of chip of hybrid fingerprint collectingAnd acquisition method.
Background technology
Along with people are more and more higher to the requirement of information security, the certification of living body biological feature and identification are increasingApply in daily life. Finger print identifying is as have very high reliability and cost performance in biological characteristic authentication,Become the main flow of current biological identification. Meanwhile, also high speed development of fingerprint collecting technology, a low cost, little moreThe fingerprint sensor of volume, low-power consumption and HDR will capture huge market, therefore has the fingerprint of above-mentioned advantageSensor becomes the emphasis of current research, and wherein capacitive fingerprint sensing device becomes one of current main product.
Ripe gradually along with fingerprint sensing technology, purchase AUTHENTEC company of Apple by AUTHENTEC public affairsThe advanced fingerprint sensing technology of department is applied in cell phone and other electronic product, and Chinese third generation identity card need to be stepped onNote finger print information, believes that fingerprint identification technology can be applied to our daily life very soon and widely, meanwhile, rightThe requirement of fingerprint sensor is more and more higher. A good fingerprint recognition decorum, is not only from algorithm and solves in fingerprint sensorThe deficiency existing, more should described in fundamentally solve the acquisition quality problem of sensor, make in some special occasions and someSpecial finger can both collect fingerprint image clearly, the more important thing is the deception of wanting to refuse prosthetic finger.
Existing domestic fingerprint sensor is all pure capacitive fingerprint sensor, as China Patent No. ZL021059608,201220476953 have all been to provide a kind of capacitance type fingerprint reading manner, and wherein the direct contact surface of finger is to sensing arrayInsulating barrier between sensing electrode is only to have the inorganic compound of several um to form by thickness, thereby causes its hydrophobicity, anti-residualThe property stayed, crushing resistance and antistatic property extreme difference. Refer to Fig. 1, the sensing cell structure of the fingerprint sensor that Fig. 1 is prior artSchematic diagram. As shown in the figure, described existing sensing cell 10 comprises: sense capacitance 11, is formed with sensing electrode by finger; Edge electricHold 12, formed by the output electrode of sensing electrode and amplifier; Amplifier 13; This sensing cell is by detecting by radiofrequency signal 14The radiofrequency signal of handling digital reflex of sending, this signal after capacitance integral amplifying circuit by follow-up processing of circuit, according to senseThe difference of surveying capacitance detects different radiofrequency signals, thereby realizes fingerprint collecting, and the method is due to each sensing cell 10All use an amplifier 13, its power consumption is very large, due to technique to affect mismatch very serious. Therefore, RF-type fingerprint passesSensor arises at the historic moment.
RF-type sensor is to expand on the basis of capacitance type sensor, and it is to utilize finger itself as control panelAnd as medium. Finger is placed on to sensor region around, produces a very low radiofrequency signal by finger; SensorThe signal diffusing out according to the mountain valley of fingerprint and ridge detected; Then, sensor array forms calculating according to diffusion signalThe structure of fingerprint; Finally, can dynamic optimization radio frequency signal frequency and level, obtain best fingerprint image. Radio frequency sensingDevice produces high-quality image, and therefore radio frequency is the most reliable and has the most effectively solution. In addition, high quality graphic is also permittedPermitted to reduce sensor, without sacrifice certification reliability, thereby reduce costs and make radio frequency sensor be applied to removable andIn the unconstrained field of size.
Existing external fingerprint sensor only AUTHENTEC and FPC Liang Ge company has been realized RF-type fingerprint collecting, and shouldThe basic homology of RF-type acquisition principle of Liang Ge company, as US Patent No. 6512381, realizes RF-type fingerprint collecting, can be veryGood anti-fingerprint residues and other pollution are residual, but only can refuse the deception of most of prosthetic finger, if in some radio-frequency radiationIts antijamming capability of stronger application scenario is poor.
Therefore, existing fingerprint sensor, no matter be capacitive or the fingerprint sensor of RF-type is all single mouldThe fingerprint detection mode of formula, it can not be applied in different places flexibly, and can not well refuse the special finger print of doing evil through another personType. If prosthetic finger model is plated to the Fingerprint Model that layer of conductive material or semiconductive material and guarantee plate after material to be subject toWhile pressing, the fingerprint valley line degree of depth of model is greater than 2um (concrete numerical value is determined by the sensitivity of sensor), and what this was special does evil through another personFinger print type be can out-trick existing fingerprint sensor detection (although this its manufacturing process of prosthetic finger model is quite multipleAssorted, its cost is very high, utilizes the checking of out-tricking of this special prosthetic finger model but do not get rid of unique people).
Summary of the invention
The object of the present invention is to provide a kind of multi-mode fingerprint collecting chip and a kind of acquisition method thereof, it can be effectiveGround solves above-mentioned unicity, points the identification of residual, anti-interference, prosthetic finger and acquisition quality problem. The present invention is in prior artOn basis, realize multi-mode fingerprint detection and collection by improving the structure of sensing cell, and utilize condenser type and RF-typePluses and minuses compensate mutually, thereby resisting remaining fingerprint, other pollution are residual, anti-electromagnetic-radiation and refusal prosthetic finger improve informationSecurity.
For achieving the above object, technical scheme of the present invention is as follows:
A kind of multi-mode fingerprint collecting chip, this chip comprises the two-dimentional sensing cell array of the capable N row of M, M and N are greatlyIn 1 integer; Passivation insulation, is directly covered on this two dimension sensing cell array; Polyester complexes insulating barrier is covered inOn this passivation insulation, as the contact-making surface of finger; Scanning monitor, this controller makes the capable sensing cell of M from top to bottomOr effective line by line from top to bottom; The capable N of M is listed as the drive circuit of two-dimentional sensing cell array, and this drive circuit provides sensing cell instituteThe clock signal needing; Row level ADC array, is disposed at sensing cell array side or below, and the signal of telecommunication output of N row sensing cell is doneFor its input; Shift LD buffer, as the buffer area of row level ADC array output; Mode control circuit, controls this chipMode of operation; Antenna metal frame and RF driver circuit, RF driver circuit driven antenna metal frame and other load; Prosthetic fingerDetecting electrode and prosthetic finger testing circuit, this electrode is for detection of prosthetic finger; It passes through host computer configuration mode control circuitParameter is controlled the capable N of M and is listed as the required collection sequential of two-dimentional sensing cell, becomes a kind of capacitance type fingerprint to gather mould this chip configurationPiece or a kind of RF-type finger print acquisition module or a kind of hybrid finger print acquisition module.
In one embodiment of the invention, the antenna metal frame of this capacitance type fingerprint acquisition module is by RF driver circuitDrive, and to detected finger emitting radio frequency signal, the frequency of this radiofrequency signal is in hundreds of KHz arrive the scope of number MHz, noCan damage human body, radiofrequency signal exists only between prosthetic finger detection period; Prosthetic finger testing circuit detects by prosthetic fingerElectrode detection flows through the radio frequency letter that the radiofrequency signal that senses on the current value of this electrode and this electrode and antenna metal frame sendNumber phase difference, determine whether as prosthetic finger according to the current value detecting and phase difference size. Scanning monitor makes sensing listFrom top to bottom or effective line by line from top to bottom, sensing cell array drive circuit is inputted the first pulse signal to sensing list to element arrayElement array, this pulse signal during pulse width to the ginseng in each sensing cell selected in this sensing cell arrayExamine capacitor charging, make these reference capacitance two ends accumulate certain quantity of electric charge, sensing cell array drive circuit input afterwards secondPulse signal is to sensing cell array, and this pulse signal is to sense capacitance and gain in this each selected sensing cellCapacitor discharge, the quantity of electric charge that makes its two ends is zero, then sensing cell array drive circuit input the 3rd pulse signal is to sensingCell array, this pulse signal drives gain electrode to a high level voltage, and meanwhile this is selected for this pulse enable signalReference capacitance in each sensing cell and sense capacitance and gain capacitances are carried out equalizing charge, make this reference capacitance two endsThe quantity of electric charge reduce, then the second pulse signal and the 3rd pulse of sensing cell array drive circuit input fixed cycles number of timesSignal, to sensing cell array, successively subtracts the voltage difference at the reference capacitance two ends in this each selected sensing cellLittle, after circulation finishes, the voltage difference at these reference capacitance two ends is locked, and meanwhile, described row level ADC array is by this voltage differenceSignal converts fingerprint image gray value to, and this fingerprint image gray value is input to shift LD buffer, completes a line fingerprint imageThe collection of picture is uploaded to host computer by the every a line fingerprint image gray value collecting under the effect of host computer.
In a preferred embodiment of the present invention, above-mentioned each sensing cell can also comprise capacitance sensor knotStructure, this capacitor sensor structure comprises: the sensing electrode being formed by the top-level metallic of integrated circuit technology; Sense capacitance insulationLayer, this insulating barrier is formed by the polyester complexes stack on the passivation layer on top-level metallic and this passivation layer, sensing electrodeForm sense capacitance with finger and this sense capacitance insulating barrier; By other metal level outside integrated circuit technology top-level metallicOne or more layers metal multiple gain electrodes of forming, between the plurality of gain electrode and sensing electrode and this two electrodeInsulating barrier forms multiple gain capacitances; Two reference electrodes and this two reference electrode insulating barrier form reference capacitance; MultipleOn-off circuit, these on-off circuits are used for controlling reference capacitance charging, sense capacitance and gain capacitances electric discharge, balanced sensing electricityThe electric charge of appearance, gain capacitances and reference capacitance, the part switch of these on-off circuits is in off-state, and it is for radio frequency mouldSwitch under formula.
Wherein, polyester complexes can be even by quality proportion or the bulk specific gravity on a top by pure polyester species and metallicsBe composited, the thickness of polyester complexes matter can reach tens of um even can reach hundreds of um.
Wherein, polyester complexes also can be pressed by pure polyester species and other organic substance quality proportion or the volume ratio on a topWeight average is even to be composited, and the thickness of polyester complexes matter can reach tens of um even can reach hundreds of um.
In one embodiment of the invention, the antenna metal frame of this RF-type fingerprint collecting chip is by RF driver circuitDrive, and to detected finger emitting radio frequency signal, the frequency of this radiofrequency signal is in hundreds of KHz arrive the scope of number MHz, noCan damage human body, radiofrequency signal be present between prosthetic finger detection period and fingerprint collecting during; Prosthetic finger testing circuit is logicalCrossing prosthetic finger detecting electrode detects and flows through the radiofrequency signal and the antenna metal frame that on the current value of this electrode and this electrode, senseThe phase difference of the radiofrequency signal of sending, determines whether as prosthetic finger according to the current value detecting and phase difference size. Scanning controlDevice processed makes sensing cell array from top to bottom or is effective line by line from top to bottom, and sensing cell array drive circuit is inputted the first pulseSignal is to sensing cell array, this pulse signal during pulse width to each sense selected in this sensing cell arrayReference capacitance charging in measurement unit, makes these reference capacitance two ends accumulate certain quantity of electric charge, and sensing cell array drives afterwardsCircuit is inputted the second pulse signal to sensing cell array, the sense in this each selected sensing cell of this pulse enable signalSurvey electrode charge to a certain fixed voltage, make the fractionated gain electrode charge in this each selected sensing cell arrive a certainFixed voltage, all the other gain electrodes are fixed in some specific potential all the time, meanwhile, antenna metal frame transmitting radio-frequency pulseSignal, makes sensing electrode and the quantity of electric charge at finger electrode two ends reduce (being even zero), makes sensing electrode and gain electrode two endsThe quantity of electric charge reduce (being even zero), afterwards the current potential of sensing electrode is dropped to a certain fixed potential, then sensing cell arrayDrive circuit input the 3rd pulse signal, to sensing cell array, makes the reference capacitance in this each selected sensing cellCarry out equalizing charge with sense capacitance and gain capacitances, the quantity of electric charge at these reference capacitance two ends is reduced, then sensing cellThe second pulse signal of array drive circuit input fixed cycles number of times and the 3rd pulse signal, to sensing cell array, make this quiltThe voltage difference at the reference capacitance two ends in each sensing cell of choosing successively reduces, these reference capacitance two ends after circulation finishesVoltage difference locked, meanwhile, a described row level ADC array converts this voltage differential signal to fingerprint image gray value, shouldFingerprint image gray value is input to shift LD buffer, completes the collection of a line fingerprint image, under the effect of host computer, complies withInferior the fingerprint image gray value collecting is uploaded to host computer.
In a preferred embodiment of the present invention, above-mentioned each sensing cell can also comprise capacitance sensor knotStructure, capacitor sensor structure comprises: the sensing electrode being formed by the top-level metallic of integrated circuit technology; One sense capacitance insulationLayer, this insulating barrier is by the polyester complexes on the passivation layer on top-level metallic, this passivation layer, this polyester complexesAir between cuticula and this polyester complexes and the cuticula of detected finger and impurity stack form, sensing electrode and handRefer to that between skin corium electrode and this two electrode, sense capacitance insulating barrier forms sense capacitance; By integrated circuit technology top-level metallicOutside multiple gain electrodes of forming of one or more layers metal of other metal level, the plurality of gain electrode and sensing electricityInsulating barrier between the utmost point and this two electrode forms multiple gain capacitances; Two reference electrodes and this two reference electrode insulating barrierForm reference capacitance; Multiple on-off circuits, these on-off circuits are used for controlling reference capacitance charging, sensing electrode and gain electrodeElectric discharge, the electric charge on balanced sense capacitance, gain capacitances and reference capacitance, the part switch of these on-off circuits is in disconnectingState, it is for the switch under capacitive. Wherein, polyester complexes can be by pure polyester species and metallics by a topQuality proportion or bulk specific gravity are evenly composited, and the thickness of polyester complexes matter can reach tens of um even can reach hundreds of um; OrPerson, polyester complexes also can be evenly compound by quality proportion or the bulk specific gravity on a top by pure polyester species and other organic substanceForm, the thickness of polyester complexes matter can reach tens of um even can reach hundreds of um.
In one embodiment of the invention, the antenna metal frame of this hybrid finger print acquisition module is by RF driver circuitDrive, and to detected finger emitting radio frequency signal, the frequency of this radiofrequency signal, can not at hundreds of KHz within the scope of number MHzHuman body is damaged, radiofrequency signal be present between prosthetic finger detection period and fingerprint collecting during; Prosthetic finger testing circuit passes throughProsthetic finger detecting electrode detects and flows through the radiofrequency signal and the antenna metal frame that on the current value of this electrode and this electrode, sense and send outThe phase difference of the radiofrequency signal going out, determines whether as prosthetic finger according to the current value detecting and phase difference size. Sensing cellBattle array point two phase acquisition information in fingerprint, first stage sensing cell array is transfused to the finger of RF-type fingerprint collecting chipLine gathers sequential, and this sequential is for detection of whether pointing contact sensing cell array, when sensing cell array detection finger in one's handsAfter touching, finish the RF-type fingerprint collecting stage, under the control of host computer, entering second stage is that capacitance type fingerprint gathers rankSection, now sensing cell array is completed the collection of finger print information, two by the fingerprint collecting sequential of defeated people's condenser type acquisition chipThe sensing cell array of acquisition phase is identical, just controls the driving sequential difference of sensing cell array, different drivingsSequential is by the control of control model circuit.
In a preferred embodiment of the present invention, above-mentioned each sensing cell also comprises capacitor sensor structure, electricityHolding sensor construction comprises: the sensing electrode being formed by the top-level metallic of integrated circuit technology; Sense capacitance insulating barrier, this is exhaustedEdge layer is by being detected on the polyester complexes on the passivation layer on top-level metallic, this passivation layer, this polyester complexesAir between cuticula and this polyester complexes and the cuticula of finger and impurity stack form, sensing electrode and finger coriumBetween layer electrode and this two electrode, sense capacitance insulating barrier forms sense capacitance; By outside integrated circuit technology top-level metallicMultiple gain electrodes that one or more layers metal of other metal level forms, the plurality of gain electrode and sensing electrode and shouldInsulating barrier between two electrodes forms multiple gain capacitances; Two reference electrodes and this two reference electrode insulating barrier form ginsengExamine electric capacity; Multiple on-off circuits, these on-off circuits are used for controlling reference capacitance charging, sensing electrode and gain electrode discharge,Electric charge on balanced sense capacitance, gain capacitances and reference capacitance, the part switch of these on-off circuits is under rf-modeIn controllable state, under capacitive in off state. Wherein polyester complexes can be by pure polyester species and metallicsEvenly be composited by quality proportion or the bulk specific gravity on a top, the thickness of polyester complexes matter can reach tens of um even can reach numberHundred um. Wherein polyester complexes also can be pressed quality proportion or the volume ratio weight average on a top by pure polyester species and other organic substanceEven being composited, the thickness of polyester complexes matter can reach tens of um even can reach hundreds of um.
For achieving the above object, the present invention also provides a kind of technical scheme as follows:
A kind of multi-mode fingerprint collecting method, comprises model selection process, points and put testing process and fingerprint collecting mistakeJourney: fingerprint collecting process comprises by sensing cell array and detects from top to bottom or from top to bottom line by line sense capacitance, and will examineThe electric capacity measuring is converted to analog electrical signal, and described row level ADC array converts the electrical signal to data signal, shift register battle arrayThe data signal of row buffer memory ADC conversion output, completes a line collection and sends row collection end interrupt, upper computer detection row collection knotIntrafascicular disconnected, the cache size in read shift register, circle collection is until collect a complete fingerprint image afterwards; PatternSelection course, by the parameter of configuration mode control circuit, can be configured as a kind of capacitance type fingerprint acquisition method or one and penetrateFrequently formula fingerprint collecting method or a kind of hybrid fingerprint collecting method.
In a preferred embodiment of the present invention, in capacitance type fingerprint acquisition step: by the sense capacitance detectingBeing converted to fingerprint image signal comprises the steps:
Input the first pulse signal to sensing cell array, the reference capacitance in each selected sensing cell is filledElectricity, makes these reference capacitance two ends accumulate certain quantity of electric charge, input afterwards the second pulse signal to sensing cell array to selectedIn each sensing cell in sense capacitance and gain capacitances electric discharge, the quantity of electric charge that makes its two ends is zero, then inputs theThree pulse signals are to sensing cell array, and this pulse signal drives gain electrode to a high level voltage, meanwhile this pulseSignal makes reference capacitance in this each selected sensing cell and sense capacitance and gain capacitances carry out equalizing charge, makesThe quantity of electric charge that must these reference capacitance two ends reduces, make reference capacitance in each selected sensing cell and sense capacitance andGain capacitances is carried out equalizing charge, and the quantity of electric charge at reference capacitance two ends is reduced, and then the of sense input fixed cycles number of timesTwo pulse signals and the 3rd pulse signal, to sensing cell array, make the reference capacitance in this each selected sensing cellThe voltage difference at two ends successively reduces, and after circulation finishes, the voltage difference at these reference capacitance two ends is locked, meanwhile, and described row levelADC array converts this voltage differential signal to fingerprint image gray value, and this fingerprint image gray value is input to shift LD buffer memoryDevice, completes the collection of a line fingerprint image, under the effect of host computer, the every a line fingerprint image gray value collecting is uploadedGive host computer.
Each sensing cell also comprises capacitor sensor structure, and it comprises: by the top-level metallic institute of integrated circuit technologyThe sensing electrode forming; Sense capacitance insulating barrier, this insulating barrier is by the passivation layer on top-level metallic and this passivation layerPolyester complexes stack forms, and sensing electrode and finger and this sense capacitance insulating barrier form sense capacitance; By integrated circuit workMultiple gain electrodes that one or more layers metal of other metal level outside skill top-level metallic forms, the plurality of gain electricityInsulating barrier between the utmost point and sensing electrode and this two electrode forms multiple gain capacitances; Two reference electrodes and this two reference electrodeInsulating barrier form reference capacitance; Multiple on-off circuits, these on-off circuits are used for controlling reference capacitance charging, sense capacitanceWith gain capacitances electric discharge, the electric charge of balanced sense capacitance, gain capacitances and reference capacitance, the part switch place of these on-off circuitsIn off-state, it is for the switch under RF acquisition. Wherein, polyester complexes can be pressed by pure polyester species and metallicsQuality proportion or the bulk specific gravity on one top are evenly composited, and the thickness of polyester complexes matter can reach tens of um and even can reach hundreds ofUm. Or polyester complexes also can be pressed quality proportion or the volume ratio weight average on a top by pure polyester species and other organic substanceEven being composited, the thickness of polyester complexes matter can reach tens of um even can reach hundreds of um.
In a preferred embodiment of the present invention, in RF-type fingerprint collecting step, by the sense capacitance detectingBeing converted to fingerprint image signal comprises the steps:
Input the first pulse signal to sensing cell array, this pulse signal during pulse width to this sensing cell battle arrayReference capacitance charging in row in selected each sensing cell, makes these reference capacitance two ends accumulate certain quantity of electric charge,Input afterwards the second pulse signal to sensing cell array, the sense in this each selected sensing cell of this pulse enable signalSurvey electrode charge to a certain fixed voltage, make the fractionated gain electrode charge in this each selected sensing cell arrive a certainFixed voltage, all the other gain electrodes are fixed in some specific potential all the time, meanwhile antenna metal frame transmitting radio-frequency pulseSignal, makes sensing electrode and the quantity of electric charge at finger electrode two ends reduce (being even zero), makes sensing electrode and gain electrode two endsThe quantity of electric charge reduce (being even zero), afterwards the current potential of sensing electrode is dropped to a certain fixed potential, then input the 3rd pulseSignal, to sensing cell array, makes reference capacitance and sense capacitance and gain capacitances in this each selected sensing cellCarry out equalizing charge, the quantity of electric charge at these reference capacitance two ends is reduced, then the input of sensing cell array drive circuit is fixingThe second pulse signal of cycle-index and the 3rd pulse signal, to sensing cell array, make this each selected sensing cellThe voltage difference at interior reference capacitance two ends successively reduces, and after circulation finishes, the voltage difference at these reference capacitance two ends is locked, therewithMeanwhile, row level ADC array converts this voltage differential signal to fingerprint image gray value, and this fingerprint image gray value is input to displacementDeposit buffer, complete the collection of a line fingerprint image, under the effect of host computer successively by the fingerprint image gray scale collectingValue is uploaded to host computer.
Each sensing cell also comprises capacitor sensor structure, and it comprises: by the top-level metallic institute of integrated circuit technologyThe sensing electrode forming; Sense capacitance insulating barrier, this insulating barrier is by gathering on the passivation layer on top-level metallic, this passivation layerAir between cuticula and this polyester complexes and the cuticula of the detected finger on ester complexes, this polyester complexesStack forms with impurity, and between sensing electrode and finger skin corium electrode and this two electrode, sense capacitance insulating barrier forms sensingElectric capacity; The multiple gains that formed by one or more layers metal of other metal level outside integrated circuit technology top-level metallicElectrode, the insulating barrier between the plurality of gain electrode and sensing electrode and this two electrode forms multiple gain capacitances; Two referencesElectrode and this two reference electrode insulating barrier form reference capacitance; Multiple on-off circuits, these on-off circuits are used for controlling ginsengExamine capacitor charging, sensing electrode and gain electrode discharge, the electric charge on balanced sense capacitance, gain capacitances and reference capacitance,The part switch of these on-off circuits is in off-state, and it is for the switch under capacitive. Wherein polyester complexes canEvenly be composited by quality proportion or the bulk specific gravity on a top by pure polyester species and metallics, polyester complexes matter thickThe tens of um of Du Keda even can reach hundreds of um. Or polyester complexes also can press one by pure polyester species and other organic substanceQuality proportion or the bulk specific gravity on top are evenly composited, and the thickness of polyester complexes matter can reach tens of um and even can reach hundreds ofum。
In a preferred embodiment of the present invention, in hybrid fingerprint collecting step, fingerprint collecting also comprises as followsStep: detect finger by RF-type fingerprint collecting step and whether put, make it enter condenser type to refer to when detecting that finger is putWhether line acquisition step, put otherwise continue to detect finger.
In a preferred embodiment of the present invention, a kind of detecting step of prosthetic finger is also provided, it comprises: radio-frequency drivenCircuit drives antenna metal, metal frame is to detected object emitting radio frequency signal, and the frequency of this radiofrequency signal arrives at hundreds of KHzWithin the scope of number MHz, can not damage human body, should be present in prosthetic finger for detection of the special radiofrequency signal of prosthetic finger and detectDuring this time; Because the impedance operator of human finger is different from prosthetic finger, prosthetic finger testing circuit detects by prosthetic finger detecting electrodeFlow through the phase place of the radiofrequency signal that the radiofrequency signal that senses on the current value of this electrode and this electrode and antenna metal frame sendPoor, determine whether as prosthetic finger according to the current value detecting and phase difference size.
Therefore, be different from fingerprint acquisition system or the chip of other single-mode, the present invention is by improving sensing cell knotStructure and increase mode control circuit and can realize multi-mode fingerprint image acquisition, this multi-mode fingerprint collecting chip can be according to notSame applied environment is selected different patterns, and it is that other fingerprint acquisition system or chip are incomparable flexibly and easily, by increasingAdd prosthetic finger detecting electrode and radiofrequency signal and can refuse the deception of any prosthetic finger.
Brief description of the drawings
Fig. 1 is the sensing cell structural representation of the fingerprint sensor of prior art
Fig. 2 is multi-mode fingerprint sensor chip structural representation of the present invention
Fig. 3 is the sensing array peripheric circuit structure schematic diagram of multi-mode fingerprint sensor chip of the present invention
Fig. 4 is the sensing cell structural representation of multi-mode fingerprint sensor chip of the present invention
Fig. 5 is the automatic gain control circuit structure schematic diagram of multi-mode fingerprint sensor chip of the present invention
Fig. 6 is the dry finger print image that multi-mode fingerprint sensor chip of the present invention collects, and wherein Fig. 6 a does not openThe dry finger print image that automatic gain control circuit collects, Fig. 6 b opens the dry hand that automatic gain control circuit collectsRefer to fingerprint image
Fig. 7 is the wet finger print image that multi-mode fingerprint sensor chip of the present invention collects, and wherein Fig. 7 a does not openThe dry finger print image that automatic gain control circuit collects; Fig. 7 b opens the wet hand that automatic gain control circuit collectsRefer to fingerprint image
Symbol description in figure
1. finger
10. sensing cell (prior art)
11. sense capacitance (prior art)
12. edge electric capacity (prior art)
13. amplifiers
14. radiofrequency signals
2. multi-mode fingerprint collecting chip
20. sensing cell arrays
201. sensing cell
21. mode control circuits
22. scan control circuits
23. sensing cell array drive circuits
24. row level ADC arrays
241. analog-digital converter
25. shift LD buffers
26. automatic gain control circuits
27. programmable reference point potential sources
28. gather timing sequence generating and image data read control circuit
29. RF driver circuits
291. prosthetic finger testing circuits
30. fingers
31. fingerprint collecting chip finger contact faces (that is to say sensing cell array)
32. antenna metal frames
321. prosthetic finger detecting electrodes
The megohmite insulant of 322. isolated antennas metal frames and prosthetic finger detecting electrode
33. radiofrequency signals
40. sense capacitance
401. sensing electrode
41. gain electrodes
411412413414415. gain capacitances
421422423424. on-off circuit
43. reference capacitances
441442443. power supply
45. sensing cell drive circuit and RF driver circuit
5. automatic gain control circuit
50. fingerprint image gray value statistical circuit
51. control circuit about when gain electrode
52. can compile reference voltage source
53. sensing cell arrays
54. row level ADC array
55. fingerprint image gray value output state
Detailed description of the invention
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail. It should be noted that, thisInvention will describe the present invention hereinafter with reference to the accompanying drawings in detail, and the present invention will describe by embodiment, but the present invention is notBe limited to embodiments of the invention.
Refer to Fig. 2, Fig. 2 is multi-mode fingerprint sensor chip structural representation of the present invention. As shown in the figure, this multi-modeFingerprint collecting chip 2 comprises: the two-dimentional sensing cell array 20 of MXN, formed by MXN sensing cell 201, and wherein M, N isBe greater than 1 integer; Passivation insulation, is directly covered on sensing cell array 20; Polyester complexes insulating barrier, directly coversOn passivation insulation; Scanning monitor 22, for controlling sensing cell array 20, makes it line by line effectively; Sensing listElement array drive circuit 23; Row level ADC array 24, is made up of side by side N analog-digital converter 241, and sensing array 20 is detectedSense capacitance convert fingerprint image gray value to; Programmable reference voltage source 27, as a reference input of row level ADC;Shift LD buffer 25, by the fingerprint image gray value buffer memory of row level ADC array output; Automatic gain control circuit, controlsRow level ADC reference input terminal voltage and sensing cell 201 sequential that connects; Mode control circuit 21, controls this multi-mode fingerprint and adoptsThe mode of operation of collection chip.
Refer to Fig. 3, Fig. 3 is the sensing array peripheric circuit structure signal of multi-mode fingerprint sensor chip of the present inventionFigure. As shown in the figure, it comprises antenna metal frame 32, and transmitting gathers the required radiofrequency signal 33 of fingerprint and this chip carried out simultaneouslyElectrostatic discharge protection (Electro-Staticdischarge is called for short ESD); Radiofrequency signal 33, driven antenna metal frame 32 andThe load connecting; Prosthetic finger detecting electrode 321 and prosthetic finger testing circuit 291, when finger 30 or prosthetic finger be placed on fingerprint collectingWhen the finger contact face 31 of chip, prosthetic finger testing circuit by prosthetic finger detecting electrode detect flow through this electrode current value andThe phase difference of the radiofrequency signal that the radiofrequency signal sensing on this electrode and antenna metal frame send, according to the current value detectingAnd phase difference size determines whether as prosthetic finger.
Refer to Fig. 4, Fig. 4 is the sensing cell structural representation of multi-mode fingerprint sensor chip of the present invention. As scheme instituteShow, each sensing cell 201 comprises: capacitor sensor structure, comprises the sense being formed by the top-level metallic of integrated circuit technologySurvey electrode 401; Sense capacitance insulating barrier, the passivation insulation on its top-level metallic that comprises integrated circuit technology and polyester are multipleCompound insulating barrier, sensing electrode 401 forms sense capacitance 40 with finger and sense capacitance insulating barrier; By integrated circuit technology top layerMultiple gain electrodes 41 that one or more layers metal of other metal level outside metal forms, sensing electrode 401, multipleInsulating barrier between gain electrode 41 and this two electrode forms multiple gain capacitances 411,412,413,414,415; Two referencesInsulating barrier between electrode and this two reference electrode forms reference capacitance 43; Multiple on-off circuits 421,422,423,424, forRide gain electric capacity 411,412,413,414,415, sense capacitance 40 and reference capacitance 43 discharge and recharge.
In the time that finger 30 is just placed on sensing cell array 20, sensing cell array drive circuit 23 is inputted the first pulseSignal is to sensing cell array 20, this pulse signal during pulse width to selected each in this sensing cell array 20Reference capacitance 43 in individual sensing cell 201 charges, and makes these reference capacitance 43 two ends accumulate certain quantity of electric charge, sensing list afterwardsElement array drive circuit 23 is inputted the second pulse signal to sensing cell array 20, this selected each of this pulse enable signalSensing electrode 401 in sensing cell 201 is charged to a certain fixed voltage, makes in this each selected sensing cell 201Fractionated gain electrode 41 discharge into a certain fixed voltage, all the other gain electrodes be fixed to all the time on some specific voltages, withThis while, antenna metal frame 32 is launched RF pulse signal 33, and sensing electrode 401 and the quantity of electric charge at finger electrode two ends are reduced(being even zero), makes sensing electrode 401 and the quantity of electric charge at gain electrode 41 two ends reduce (being even zero), afterwards by sensing electrode401 current potential drops to a certain fixed potential, and then sensing cell array drive circuit 23 is inputted one the 3rd pulse signal to sensingCell array 20, reference capacitance 43 and sense capacitance 40 in this each selected sensing cell 201 of this pulse enable signalCarry out equalizing charge with gain capacitances 411,412,413,414,415, the quantity of electric charge at these reference capacitance 43 two ends is reduced, soRear sensing cell array drive circuit 23 is inputted the second pulse signal of fixed cycles number of times and the 3rd pulse signal to sensing listElement array 20, successively reduces the voltage difference at reference capacitance 43 two ends of this each selected sensing cell interior 201, circulationAfter end, the voltage difference at these reference capacitance two ends is locked, and meanwhile, row level ADC array 24 converts this voltage differential signal toFingerprint image gray value, this fingerprint image gray value is input to shift LD buffer 25, completes the collection of a line fingerprint image,Under the effect of host computer, successively the fingerprint image gray value collecting is uploaded to host computer.
Refer to Fig. 5, Fig. 5 is the automatic gain control circuit structure signal of multi-mode fingerprint sensor chip of the present inventionFigure. As shown in the figure, it comprises: fingerprint image gray value statistical circuit 50; Gain electrode sequential control circuit 51; Sensing cell battle arrayRow 53; Programmable reference voltage source 52; Row level ADC array 54; Fingerprint image gray value output state 55; This automatic gain controlCircuit processed can strengthen fingerprint collecting effect.
Refer to Fig. 6, Fig. 6 is the dry finger print image that multi-mode fingerprint sensor chip of the present invention collects, whereinFig. 6 a does not open the dry finger print image that automatic gain control circuit collects, and Fig. 6 b adopts for opening automatic gain control circuitThe dry finger print image that collection arrives. The collection of dry finger, by automatic gain control circuit, becomes its fingerprint image gathering outIn normal range (NR).
Refer to Fig. 7, Fig. 7 is the wet finger print image that multi-mode fingerprint sensor chip of the present invention collects, wherein,Fig. 7 a does not open the dry finger print image that automatic gain control circuit collects; Fig. 7 b adopts for opening automatic gain control circuitThe wet finger print image that collection arrives; The collection of wet finger, by automatic gain control circuit, becomes its fingerprint image gathering outIn normal range (NR).
Above-described is only the preferred embodiments of the present invention, and described embodiment not protects in order to limit patent of the present inventionProtect scope, the equivalent structure that therefore every utilization description of the present invention and accompanying drawing content are done changes, and in like manner all should be included inIn protection scope of the present invention.
Claims (15)
1. a multi-mode fingerprint collecting chip, is characterized in that, comprising:
The two-dimentional sensing cell array of the capable N row of M, wherein, M and N are the integer that is greater than 1;
Passivation insulation, is directly covered on described two-dimentional sensing cell array;
Polyester complexes insulating barrier is covered on described passivation insulation, as the contact-making surface of finger;
Scanning monitor, described scanning monitor makes the capable sensing cell of M from top to bottom or is effective line by line from top to bottom;
The capable N of M is listed as the drive circuit of two-dimentional sensing cell array, and described drive circuit provides sensing cell required clock signal;
Row level ADC array, is disposed at described two-dimentional sensing cell array side or below, and the signal of telecommunication of described N row sensing cell is defeatedGo out as its input;
Shift LD buffer, as the buffer area of described row level ADC array output;
Mode control circuit, controls the mode of operation of described chip;
Antenna metal frame and RF driver circuit, RF driver circuit driven antenna metal frame and other load; Wherein, by upperThe parameter of position machine configuration mode control circuit is controlled the capable N of described M and is listed as the required collection sequential of two-dimentional sensing cell, by described coreSheet is configured to a kind of capacitance type fingerprint acquisition module or a kind of RF-type finger print acquisition module or a kind of hybrid fingerprint collecting mouldPiece.
2. multi-mode fingerprint collecting chip according to claim 1, is characterized in that, described capacitance type fingerprint gathers mouldPiece also comprises prosthetic finger detecting electrode and prosthetic finger testing circuit, and described electrode is for detection of prosthetic finger, wherein, and described antenna goldBelong to frame and driven by RF driver circuit, and to detected finger emitting radio frequency signal, the frequency of described radiofrequency signal is hundreds ofIn the scope of KHz～number MHz, described radiofrequency signal exists only between prosthetic finger detection period; Described prosthetic finger testing circuit passes throughDescribed prosthetic finger detecting electrode detects and flows through the radiofrequency signal and the antenna that on the current value of described electrode and described electrode, senseThe phase difference of the radiofrequency signal that metal frame sends, determines whether as prosthetic finger according to the current value detecting and phase difference size;Described scanning monitor makes sensing cell array from top to bottom or is effective line by line from top to bottom, and described sensing cell array drives electricityThe first pulse signal is inputted to described sensing cell array in road, described pulse signal during pulse width to described sensing cellReference capacitance charging in array in selected each sensing cell, makes described reference capacitance two ends accumulate certain electric chargeAmount, sensing cell array drive circuit is inputted the second pulse signal to sensing cell array afterwards, and described pulse signal is to describedSense capacitance in each selected sensing cell and gain capacitances electric discharge, the quantity of electric charge that makes its two ends is zero, then senseMeasurement unit array drive circuit input the 3rd pulse signal is to sensing cell array, and described pulse signal drives gain electrode toHigh level voltage, meanwhile, reference capacitance and sense described in described pulse enable signal in selected each sensing cellSurvey electric capacity and gain capacitances and carry out equalizing charge, the quantity of electric charge at described reference capacitance two ends is reduced, then, described sensing listThe second pulse signal of element array drive circuit input fixed cycles number of times and the 3rd pulse signal, to sensing cell array, make instituteThe voltage difference of stating the reference capacitance two ends in each selected sensing cell successively reduces, and circulation finishes rear described with reference to electricityThe voltage difference of holding two ends is locked, and meanwhile, described row level ADC array converts described voltage differential signal to fingerprint image ashDegree value, described fingerprint image gray value is input to shift LD buffer, completes the collection of a line fingerprint image, at host computerUnder effect, the every a line fingerprint image gray value collecting is uploaded to host computer.
3. multi-mode fingerprint collecting chip according to claim 1 and 2, is characterized in that sensing cell described in eachAlso comprise a capacitor sensor structure; Described capacitor sensor structure comprises: the institute of the top-level metallic by an integrated circuit technology shapeThe sensing electrode becoming; One sense capacitance insulating barrier, described insulating barrier by the passivation layer on top-level metallic and described passivation layer itOn polyester complexes stack form, sensing electrode and finger and described sense capacitance insulating barrier formation sense capacitance; One by collectingThe multiple gain electrodes that become one or more layers metal of other metal level outside circuit technology top-level metallic to form, described inInsulating barrier between multiple gain electrodes and sensing electrode and described two electrodes forms multiple gain capacitances; Two reference electrodes andDescribed two reference electrodes insulating barrier form reference capacitance; Multiple on-off circuits, described multiple on-off circuits are used for controlling ginsengExamine capacitor charging, sense capacitance and gain capacitances electric discharge, the electric charge of balanced sense capacitance, gain capacitances and reference capacitance, wherein,The described on-off circuit of part in off-state, for the switch under rf-mode.
4. multi-mode fingerprint collecting chip according to claim 3, is characterized in that, described polyester complexes can be by pure poly-Ester material and metallics are evenly composited by certain mass proportion or bulk specific gravity, and the thickness of polyester complexes matter is tens ofUm～hundreds of um; Or described polyester complexes can be pressed certain quality proportion or volume by pure polyester species and organic substanceProportion is evenly composited, and the thickness of described polyester complexes matter is tens of um～hundreds of um.
5. multi-mode fingerprint collecting chip according to claim 1, is characterized in that, described RF-type fingerprint collecting coreSheet module also comprises prosthetic finger detecting electrode and prosthetic finger testing circuit, and described electrode is for detection of prosthetic finger; Described prosthetic fingerTesting circuit is detected and is flow through the radio frequency letter sensing on the current value of described electrode and described electrode by prosthetic finger detecting electrodeThe phase difference of the radiofrequency signal of number sending with antenna metal frame, according to the current value detecting and phase difference size determine whether intoProsthetic finger; Described scanning monitor makes sensing cell array from top to bottom or is effective line by line from top to bottom, and sensing cell array drivesMoving circuit is inputted the first pulse signal to sensing cell array, described pulse signal during pulse width to described sensing cellReference capacitance charging in array in selected each sensing cell, makes described reference capacitance two ends accumulate certain electric chargeAmount, sensing cell array drive circuit is inputted the second pulse signal to sensing cell array afterwards, described in described pulse enable signalSensing electrode in each selected sensing cell is charged to a certain fixed voltage, makes described each selected sensingFractionated gain electrode charge in unit is to a certain fixed voltage, and all the other gain electrodes are fixed in some specific potential all the time,Meanwhile, antenna metal frame transmitting RF pulse signal, reduces even sensing electrode and the quantity of electric charge at finger electrode two endsBe zero, it is even zero that sensing electrode is reduced with the quantity of electric charge at gain electrode two ends, afterwards the current potential of sensing electrode is dropped to certainOne fixed potential, then sensing cell array drive circuit input the 3rd pulse signal, to sensing cell array, makes described selectedIn each sensing cell in reference capacitance and sense capacitance and gain capacitances carry out equalizing charge, make described with reference to electricityThe quantity of electric charge that holds two ends reduces, then the second pulse signal of sensing cell array drive circuit input fixed cycles number of times and theThree pulse signals, to sensing cell array, make the voltage difference at the reference capacitance two ends in described each selected sensing cellSuccessively reduce, it is locked that circulation finishes the voltage difference at rear described reference capacitance two ends, meanwhile, and described row level ADC array generalDescribed voltage differential signal converts fingerprint image gray value to, and described fingerprint image gray value is input to shift LD buffer, completeBecome the collection of a line fingerprint image, under the effect of host computer, successively the fingerprint image gray value collecting is uploaded to upperMachine.
6. multi-mode fingerprint collecting chip according to claim 1 or 5, is characterized in that sensing cell described in eachAlso comprise: capacitor sensor structure, it comprises: the sensing electrode being formed by the top-level metallic of integrated circuit technology; Sensing electricityHold insulating barrier, described insulating barrier is by the polyester complexes on the passivation layer on top-level metallic, described passivation layer, described polyesterAir between the cuticula of the detected finger on compound and described polyester complexes and cuticula and impurity stack shapeBecome, between sensing electrode and finger skin corium electrode and described two electrodes, sense capacitance insulating barrier forms sense capacitance; By collectingThe multiple gain electrodes that become one or more layers metal of other metal level outside circuit technology top-level metallic to form, described inInsulating barrier between multiple gain electrodes and sensing electrode and described two electrodes forms multiple gain capacitances; Two reference electrodes andDescribed two reference electrodes insulating barrier form reference capacitance; Multiple on-off circuits, described multiple on-off circuits are used for controlling ginsengExamine the electric charge on capacitor charging, sensing electrode and gain electrode discharge, balanced sense capacitance, gain capacitances and reference capacitance,The part switch of described multiple on-off circuits is in off-state, for the switch under capacitive.
7. multi-mode fingerprint collecting chip according to claim 6, is characterized in that, described polyester complexes can be by pure poly-Ester material and metallics are evenly composited by certain mass proportion or bulk specific gravity, and the thickness of polyester complexes matter is tens ofUm～hundreds of um; Or described polyester complexes can be pressed certain quality proportion or volume by pure polyester species and organic substanceProportion is evenly composited, and the thickness of described polyester complexes matter is tens of um～hundreds of um.
8. multi-mode fingerprint collecting chip according to claim 1, is characterized in that, described multi-mode fingerprint collecting mouldAntenna metal frame in piece is driven by RF driver circuit, and to detected finger emitting radio frequency signal, this radiofrequency signalFrequency at hundreds of KHz within the scope of number MHz, described radiofrequency signal be present between prosthetic finger detection period and fingerprint collecting during; InstituteStating prosthetic finger testing circuit is detected and is flow through penetrating of sensing on the current value of this electrode and this electrode by prosthetic finger detecting electrodeThe phase difference of the radiofrequency signal that frequently signal and antenna metal frame send, according to the current value detecting and phase difference size is definite isNo is prosthetic finger; Described sensing cell battle array is divided two phase acquisition information in fingerprint, and the first stage, sensing cell array was by defeatedEnter the fingerprint collecting sequential of RF-type fingerprint collecting chip, described sequential is for detection of whether pointing contact sensing cell array,When sensing cell array detection finishes the RF-type fingerprint collecting stage after finger contact, under the control of host computer, enterTwo-stage is capacitance type fingerprint acquisition phase, and now sensing cell array is by the fingerprint collecting sequential of defeated people's condenser type acquisition chipComplete the collection of finger print information. The sensing cell array of two acquisition phase is identical, just controls sensing cell arrayDriving sequential difference, different driving sequential is by the control of control model circuit.
9. according to the multi-mode fingerprint collecting chip described in claim 1 or 8, it is characterized in that the sensing list described in eachUnit also comprises capacitor sensor structure, and described capacitor sensor structure comprises: the top-level metallic by integrated circuit technology is formedSensing electrode; Sense capacitance insulating barrier, this insulating barrier is multiple by the polyester on the passivation layer on top-level metallic, this passivation layerAir between cuticula and this polyester complexes and the cuticula of the detected finger on compound, this polyester complexes and assortedMatter stack forms, and between described sensing electrode and finger skin corium electrode and this two electrode, sense capacitance insulating barrier forms sensingElectric capacity; The multiple gains that formed by one or more layers metal of other metal level outside integrated circuit technology top-level metallicElectrode, the insulating barrier between the plurality of gain electrode and sensing electrode and this two electrode forms multiple gain capacitances; Two referencesElectrode and this two reference electrode insulating barrier form reference capacitance; Multiple on-off circuits, described multiple on-off circuits are for controlElectricity on reference capacitance charging processed, sensing electrode and gain electrode discharge, balanced sense capacitance, gain capacitances and reference capacitanceLotus, the part switch of these on-off circuits under rf-mode in controllable state, under capacitive in off state.
10. multi-mode fingerprint collecting chip according to claim 9, is characterized in that, described polyester complexes can be by purePolyester species and metallics are evenly composited by certain mass proportion or bulk specific gravity, and the thickness of polyester complexes matter is numberTen um～hundreds of um; Or described polyester complexes can be pressed certain quality proportion or body by pure polyester species and organic substanceLong-pending proportion is evenly composited, and the thickness of described polyester complexes matter is tens of um～hundreds of um.
11. 1 kinds of multi-mode fingerprint collecting methods, is characterized in that, comprise finger put testing process, fingerprint collecting process andModel selection process: described fingerprint collecting process detects sensing electricity line by line from top to bottom or from top to bottom by sensing cell arrayHold, and the electric capacity detecting is converted to analog electrical signal; Described fingerprint collecting process row level ADC array converts the electrical signal toData signal, the data signal of shift register array buffer memory ADC conversion output, completes a line collection and sends during row collection finishesDisconnected, upper computer detection row gathers end interrupt, the cache size in described model selection process read shift register, afterwards circulationGather until collect a complete fingerprint image; By the parameter of configuration mode control circuit, be configured as a kind of electric capacityFormula fingerprint collecting step or a kind of RF-type fingerprint collecting step or a kind of hybrid fingerprint collecting step.
12. multi-mode fingerprint collecting methods according to claim 11, is characterized in that, in described capacitance type fingerprint collectionIn step, describedly the sense capacitance detecting is converted to fingerprint image signal comprises the steps:
Step S11: input the first pulse signal is to sensing cell array, to the reference electricity in each selected sensing cellCapacity charge, makes described reference capacitance two ends accumulate certain quantity of electric charge;
Step S12: input the second pulse signal to sensing cell array to the sensing electricity in each selected sensing cellHold and gain capacitances electric discharge, the quantity of electric charge that makes its two ends is zero;
Step S13: input the 3rd pulse signal is to sensing cell array, and described pulse signal drives gain electrode to a high levelVoltage, meanwhile described in described pulse enable signal the reference capacitance in selected each sensing cell and sense capacitance andGain capacitances is carried out equalizing charge, and the quantity of electric charge at described reference capacitance two ends is reduced, and makes each selected sensing listReference capacitance in unit and sense capacitance and gain capacitances are carried out equalizing charge, and the quantity of electric charge at reference capacitance two ends is reduced;
Step S14: the second pulse signal of input fixed cycles number of times and the 3rd pulse signal are to sensing cell array, described in makingThe voltage difference at the reference capacitance two ends in each selected sensing cell successively reduces, and circulation finishes rear described reference capacitanceThe voltage difference at two ends is locked, and meanwhile, described row level ADC array converts described voltage differential signal to fingerprint image gray scaleValue, described fingerprint image gray value is input to shift LD buffer, completes the collection of a line fingerprint image, at the work of host computerWith lower, the every a line fingerprint image gray value collecting is uploaded to host computer.
13. multi-mode fingerprint collecting methods according to claim 11, is characterized in that, at described RF-type fingerprint collectingIn step, describedly the sense capacitance detecting is converted to fingerprint image signal comprises the steps:
Step S21: input the first pulse signal to sensing cell array, described pulse signal during pulse width to described senseReference capacitance charging in measurement unit array in selected each sensing cell, makes the accumulation of described reference capacitance two ends certainThe quantity of electric charge;
Step S22: input the second pulse signal is to sensing cell array, each selected sense described in described pulse enable signalSensing electrode in measurement unit is charged to a certain fixed voltage, makes the fractionated gain in described each selected sensing cellElectrode charge is to a certain fixed voltage, and all the other gain electrodes are fixed in some specific potential all the time, meanwhile antenna metalFrame is launched a RF pulse signal, and it is even zero that sensing electrode is reduced with the quantity of electric charge at finger electrode two ends, makes sensing electrodeReducing with the quantity of electric charge at gain electrode two ends is even zero;
Step S23: the current potential of sensing electrode is dropped to a certain fixed potential, then input the 3rd pulse signal to sensing cell battle arrayRow, make reference capacitance in described each selected sensing cell and sense capacitance and gain capacitances carry out equalizing charge,The quantity of electric charge at described reference capacitance two ends is reduced;
Step S24: the second pulse signal and the 3rd pulse signal of sensing cell array drive circuit input fixed cycles number of timesTo sensing cell array, the voltage difference at the reference capacitance two ends in described each selected sensing cell is successively reduced,It is locked that circulation finishes the voltage difference at rear described reference capacitance two ends, and meanwhile, described row level ADC array is by described voltage differenceSignal converts fingerprint image gray value to, and described fingerprint image gray value is input to shift LD buffer, completes a line fingerprintThe collection of image is uploaded to host computer by the fingerprint image gray value collecting successively under the effect of host computer.
14. multi-mode fingerprint collecting methods according to claim 11, is characterized in that, at described hybrid fingerprint collectingIn step, described fingerprint collecting comprises the steps:
Detect finger by RF-type fingerprint collecting step and whether put, make it enter capacitance type fingerprint when detecting that finger is putWhether acquisition step, put otherwise continue to detect finger.
15. according to the multi-mode fingerprint collecting method described in claim 12,13 or 14, it is characterized in that, also comprises prosthetic fingerTesting process, it comprises following steps:
RF driver circuit driven antenna metal, metal frame is to detected object emitting radio frequency signal, the frequency of this radiofrequency signalRate is at hundreds of KHz within the scope of number MHz, and the described special radiofrequency signal for detection of prosthetic finger is present in prosthetic finger detection periodBetween; Prosthetic finger testing circuit is detected and is flow through penetrating of sensing on the current value of this electrode and this electrode by prosthetic finger detecting electrodeThe phase difference of the radiofrequency signal that signal and antenna metal frame send frequently, and determine according to the current value detecting and phase difference sizeWhether be prosthetic finger.
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