CN103679163B - Novel capacitance type fingerprint image acquisition system - Google Patents
Novel capacitance type fingerprint image acquisition system Download PDFInfo
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- CN103679163B CN103679163B CN201210345176.1A CN201210345176A CN103679163B CN 103679163 B CN103679163 B CN 103679163B CN 201210345176 A CN201210345176 A CN 201210345176A CN 103679163 B CN103679163 B CN 103679163B
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Abstract
The invention provides a novel capacitance type fingerprint image acquisition system which comprises a sensing element array, a sensing element array driving circuit, an insulating surface, a comparator array, a programmable reference voltage source and a self-adaptive process algorithm logic circuit, wherein the sensing element array comprises a plurality of sensing elements; the sensing element array driving circuit is used for inputting voltage signals to the sensing element array; the insulating surface covers on the sensing element array and is used as a contact surface of fingers; the comparator array is configured beside the sensing element array and output of the sensing element array is used as the input of the comparator array; the programmable reference voltage source is used as input reference voltage of the comparator array; the self-adaptive process algorithm logic circuit is used for adjusting the programmable reference voltage source in a self-adaptive manner. By adopting the system provided by the invention, the sensitivity of a capacitance sensor can be improved, so that clear fingerprint images of dry, wet, oily and normal fingers can be acquired, and the system is applicable to acquisition of special fingerprint.
Description
Technical field
A kind of the present invention relates to IC design field, more particularly to novel capacitance-type suitable for special finger collection
Fingerprint Vision Gathering System.
Background technology
With the high speed development that automatic electronic is designed, live biometric certification and identification are more and more used
To in the life of people, finger print identifying is had become as having highest reliability and cost performance in biological characteristic authentication
The main flow of current biological certification.At the same time, fingerprint collecting technology also high speed development, one more inexpensive, the biography of smaller volume
Sensor will capture huge market, therefore the sensor with above-mentioned advantage becomes the emphasis of current research.Wherein condenser type
Sensor becomes one of current main-stream product.
It is gradually ripe with fingerprint technique, and cost is more and more lower, it is believed that fingerprint identification technology widely can be answered
Use our daily life.At the same time, the also more and more higher of the requirement to sensor.One good fingerprint recognition system,
It is not only and solves deficiency present in fingerprint recognition system from algorithm, more should fundamentally solves the figure that sensor acquisition is arrived
As quality problems so that some special fingers can collect clearly fingerprint image.Existing capacitance type sensor is logical
Cross using charge sharing principle to realize, have come the structure for sensing small electric capacitance using capacitor charge and discharge principle compared with the past
Very big improvement, such as Chinese patent numbering ZL02105960.8, there is provided a kind of capacitance type fingerprint access chip, comprising with two dimension
Capacitance sensing element array and a class dynamic random access memory DRAM peripheral circuit that mode is arranged, such sensing element array
Using stricture of vagina peak and the stricture of vagina paddy of the charge sharing principle detection fingerprint of DRAM.The sensing element structure of the existing capacitance type sensor is not
Background capacitance can be eliminated（Parasitic capacitance of the sensing electrode to its electrode, including sensing electrode to reference electrode, sensing electrode is to lining
The parasitic capacitance at bottom etc., and the parasitic capacitance of each sensing there may be discordance）, its sensing output signal passes through
Binary system or the image information of gray level that one comparator or A/D converter are obtained, it is only electric by changing the reference of sensing
Capacitance changes the quality that mask capacitor size and the current potential that connect carry out coarse adjustment fingerprint image, and the method is for overly wet or too
Oil finger exist collect it is image blurring unclear, for be dried and rupture finger, the image lines for collecting it is too shallow or
Person can not be identified fingerprint lines at all, cause special finger application to be restricted, if while collecting unsharp fingerprint image
Picture, affects to subsequent fingerprint process and identification
The content of the invention
The present invention is in order to solve the above problems, there is provided a kind of follow-on capacitance type fingerprint image capturing system, existing
Carried out by the reference voltage of the comparator for improving sensing circuit and being passed through to sensing output signal on the basis of technology
Self-adaptative adjustment.
The present invention provides a kind of Novel capacitance type fingerprint image acquisition system, including a sensing element array, comprising multiple senses
Survey unit；One sensing array drive circuit, for sensing element array input voltage signal；One insulating surface, is covered in the sense
Survey on element array, as the contact surface of a finger；One comparator array, is configured at by the sensing element array, senses element array
Output as its be input into；One programmable reference voltage source, used as an input reference voltage of comparator array；One self adaptation
Process algorithm logic circuit, for the programmable reference voltage source of Automatic adjusument；Characterized in that, sensing element array connects defeated
Enter a first voltage signal, make reference capacitance two ends or sense capacitance two ends in each sensing produce a voltage
Difference；A second voltage signal is input into afterwards, makes reference capacitance two ends poor with mask capacitor two ends no-voltage, or sense capacitance two
End and mask capacitor two ends no-voltage are poor；Then a tertiary voltage signal is input into, is made bucking electrode be linked to a voltage, is made the sense
Electric capacity is surveyed, and the mask capacitor disconnects the reference capacitance and the sense capacitance again and is somebody's turn to do after charge share being carried out with the reference capacitance
The link of mask capacitor；Order repeatedly inputs second, and each compares again by tertiary voltage signal until comparator occurs upset
Export compared with the energizing signal of device, as the gray level image information for collecting.
Each sensing is also included：One sensor construction, including：One sensing electrode, forms sense with finger, insulating surface
Survey electric capacity；
Two reference electrodes；And an insulating barrier, it is configured between two reference electrodes, and in two reference electrodes and insulating barrier
Between can form reference capacitance；One bucking electrode and the insulating barrier being configured between bucking electrode and sensing electrode, in shielding electricity
Mask capacitor is formed between pole, insulating barrier and sensing electrode；And multiple switch circuit.
The real-time com-parison and analysis device array of adaptive process algorithm logic circuit is input into grayscale fingerprint image information therein,
A feedback signal is exported afterwards for adjusting the reference voltage level of comparator array.
The domain structure of multiple sensings is as follows：
Last layer of metal as sensing electrode, to several second layer metals as bucking electrode, for completely cutting off other circuits
So as to eliminate background capacitance, between the insulating barrier and the double layer of metal between this double layer of metal, mask capacitor is formed；Each sensing
The bucking electrode of unit is sequentially divided into polylith, wherein two pieces of edge connection constant voltage so that the edge between each sensing
Parasitic capacitance is identical, and remaining block is connected on variable voltage source, is driven by sensing drive circuit.
The present invention according to charge sharing principle, the ginseng of the comparator passed through by self-adaptative adjustment sensing output signal
Voltage is examined, improving existing sensing element array carries out the detection of capacitance, and the system can increase the susceptiveness of capacitance sensor,
Dry, wet, oil, and normal finger can be caused to collect clearly fingerprint image, be more applicable for some special handss
The collection of finger.Adaptive process algorithm is realized by Digital Logical Circuits.
The present invention separately provides a kind of domain structure of sensing so that the charge share concordance of hundreds of thousands of sensings
（The concordance of each sensing parasitic capacitance）, further improve the quality of fingerprint output image.
Description of the drawings
Fig. 1 is capacitance type fingerprint acquisition system schematic diagram of the present invention；
Fig. 2 is the sensing element structure schematic diagram of the capacitance type fingerprint acquisition system of the embodiment of the present invention；
Fig. 3 is the sensing domain structure schematic diagram of the capacitance type fingerprint acquisition system of the embodiment of the present invention；
Fig. 4 is the dry finger print image that capacitance type fingerprint acquisition system of the present invention is collected, and wherein Fig. 4 a are not adjust
The image that comparator reference magnitude of voltage is collected；Fig. 4 b are to adjust the image that comparator reference magnitude of voltage is collected.
Fig. 5 is the wet finger print image that capacitance type fingerprint acquisition system of the present invention is collected, and wherein Fig. 5 a are not adjust
The image that comparator reference magnitude of voltage is collected；Fig. 5 b are to adjust the image that comparator reference magnitude of voltage is collected.
Symbol description in figure：
1 fingerprint acquisition system
10 sensing element array
11 sensing array drive circuits
The programmable comparator array of 12 input reference voltages
The programmable comparator of 121 input reference voltages
13 adaptive process algorithm logic circuits
14 programmable reference voltage sources
2 fingers
20 sensing electrodes
201 sense capacitances
202 reference capacitances
203a, 203b, 203c, 203d, 203e, 203e mask capacitor
301302303304a 304b 305a 305b 306a 306b are switched
401402403404a 404b 405a 405b 406a 406b voltage sources
5 nodes
Specific embodiment
The invention provides a kind of capacitance type fingerprint image capturing system, comprising：One sensing element array, comprising multiple sensings
Unit；One sensing array drive circuit；One insulating surface, is covered on the sensing element array, as the contact surface of a finger；
One comparator array, is configured at by the capacitance sensing element array, and the output for sensing element array is input into as which；One programmable ginseng
Voltage source is examined, as an input reference voltage of comparator array；One adaptive process algorithm logic circuit, adjusts for self adaptation
Save programmable reference voltage source.The sensing element array is transfused to a first voltage signal, makes in each sensing
Reference capacitance two ends produce a voltage difference；A second voltage signal is input into afterwards, makes sense capacitance two ends and mask capacitor two ends
No-voltage is poor；Then a tertiary voltage signal is input into, makes bucking electrode be linked to a certain voltage, make the sense capacitance, the shielding
Electric capacity disconnects the reference capacitance again with the sense capacitance and the chain of the mask capacitor after carrying out charge share with the reference capacitance
Connect；Order repeatedly inputs second, and the upset of each comparator believed again by tertiary voltage signal until comparator occurs upset
Number output as the gray level image information for collecting.
The output signal feeds back to a signal for adjusting and can compile after being input to adaptive process algorithm logic processing of circuit
Journey reference voltage source, the iterative cycles processes, until exporting a pair clearly fingerprint image.
An embodiment of the invention, this capacitance type fingerprint image capturing system, comprising：One sensing element array, a sense
Survey element array drive circuit, an insulating surface, a comparator array, a programmable reference voltage source and an adaptive process to calculate
Method logic circuit；Wherein sense element array and include multiple sensings, each sensing：A sensor construction is included also, including
One sensing electrode, two reference electrodes and the insulating barrier being configured between reference electrode, a bucking electrode and it is configured at bucking electrode
An insulating barrier, multiple switch circuit between sensing electrode.
Wherein, insulating surface is covered on sensing element array, as proficiency abutment face；Finger, insulating surface and sense
Survey electrode and can form sense capacitance, reference capacitance can be formed between two reference electrodes and insulating barrier, in bucking electrode, insulating barrier
And mask capacitor between sensing electrode, can be formed；Multiple switch completes capacitance sensing in the presence of sensing array drive circuit
The charge share of unit；Wherein sensing array drive circuit is input into a first voltage signal, makes in each sensing
Reference capacitance two ends produce a voltage difference（Or sense capacitance two ends produce voltage difference）；A second voltage signal is input into afterwards, is made
Sense capacitance two ends（Or reference capacitance two ends）It is poor with mask capacitor two ends no-voltage；Then a tertiary voltage signal is input into, is made
Bucking electrode is linked to a certain voltage, makes the sense capacitance, and the mask capacitor and the reference capacitance are carried out after charge share again
Disconnect linking for the reference capacitance and the sense capacitance and the mask capacitor；Order repeatedly inputs second, tertiary voltage signal,
Again the energizing signal of each comparator is exported as the gray level image information for collecting until comparator occurs upset.
According to another embodiment of the present invention, the domain structure of this sensing is as follows：
Last layer of metal as sensing electrode, to several second layer metals as bucking electrode, for completely cutting off other circuits
So as to eliminate background capacitance, the insulating barrier between this double layer of metal and the double layer of metal forms mask capacitor.Each sensing
Bucking electrode is sequentially divided into polylith, wherein two pieces of edge connection constant voltage so that the edge parasitic between each sensing
Electric capacity is identical, and remaining block is connected on variable voltage source, is driven by sensing drive circuit.
In being originally embodiment, each sensing bucking electrode is divided into 5 fritter A, B, C, D, E, and wherein A, E connection is permanent
Determine voltage so that the edge parasitic capacitance between each sensing is roughly the same, B, C, D are connected on variable voltage source, by feeling
Survey first drive circuit to drive.The variable voltage source linked by adjusting B, C, D can obtain a kind of sensing of optimal susceptiveness
Unit.Reference capacitance and on-off circuit are placed under the double layer of metal.The domain structure causes the electric charge of hundreds of thousands of sensings
Share concordance（The concordance of each sensing parasitic capacitance）, further improve the quality of fingerprint output image.
Different from other capacitance type fingerprint image capturing systems, circuit structure and its version by improving sensing of the invention
Graph structure improving collection image quality, while adjust an input reference voltage by an adaptive algorithm process can compile
The comparator of journey is realizing the collection to special finger.Either gather normal fingerprint or gather special fingerprint, by reality
When the adaptive adjustment programmable comparator of input reference voltage, so as to adjust the output fingermark image quality of comparator, all
Can collect and compare clearly fingerprint image.
Referring to Fig. 1, which is capacitance type fingerprint acquisition system schematic diagram of the present invention.The fingerprint acquisition system 1 is included：One sensing
Element array 10, comprising multiple sensings 101, for detecting sense capacitance that finger surface and sensing electrode are formed;Sensing
Array drive circuit 11, for sensing element array input voltage signal；The programmable comparator array of one input reference voltage
12, comprising multiple comparators 121, the output of sensing is converted to into binary system grayscale fingerprint image information;One self adaptation mistake
Journey algorithm logic circuit 13, for the binary system grayscale fingerprint image information therein of analysis input in real time, output one is anti-afterwards
Feedback signal is used for adjusting the reference voltage level of comparator array 12;One programmable reference voltage source 14, used as comparator array 12
Input.
Referring to Fig. 2, which is the structural representation of the one of sensing of embodiment of the present invention capacitance type fingerprint acquisition system.
The sensing is included：One sense capacitance 201, the electric capacity formed by finger 2, sensing electrode 20 and insulating surface 21；One reference
Electric capacity 202；Multiple mask capacitor 203a, 203b, 203c, 203d, 203e；Multiple switch 301,302,303,304a, 304b,
305a、305b、306a、306b；Multiple voltage sources 401,402,403,404a, 404b, 405a, 405b, 406a, 406b；Work as handss
When referring to 2 contact sensing surface 21, sensing array drive circuit 11 can be input into a first voltage so that switch 303 cuts out, ginseng
Examine electric capacity 202 and be charged to a certain magnitude of voltage, such as VDD disconnects switch 303 afterwards.The input of sensing array drive circuit 11 afterwards one
Second voltage so that 301,304a, 305a of switch, 306a are closed, switchs 304b, and 305b, 306b disconnect, make in sensing electrode
Electric charge is that zero (both end voltage such as sense capacitance and mask capacitor is zero) disconnects pass 301,304a, 305a, 306a afterwards.Then it is defeated
Enter a tertiary voltage so that switch 302,304b, 305b, 306b cuts out, and electric capacity 203b, 203c, 203d are linked to a certain voltage
On, such as VDD, sense capacitance, reference capacitance and mask capacitor disconnect switch 302,304b, 305b, 306b after there is charge share.
After repeatedly inputting second, third voltage for several times, until the voltage of reference capacitance 202 drops to the reference voltage level of comparator, make
There is reversion in comparator.Finally by the output of comparator incoming real-time adaptive process algorithm logic circuit 13, self adaptation mistake
Journey algorithm logic circuit 13 feeds back to a digital signal for adjusting programmable reference voltage source 14.Either normal finger or
Special finger, after the fingerprint acquisition system, can export a width clearly fingerprint image.
Additionally, after repeatedly inputting the certain number of times of second, third voltage, can make mask capacitor 203a, 203b, 203c,
It is zero that 203d, 203e contribute to the net charge of node 5, so as to eliminate the impact of background capacitance.
Referring to Fig. 3, which is the domain of the sensing of embodiment of the present invention capacitance type fingerprint acquisition system, by double layer of metal structure
Into last layer of metal（102）As sensing electrode, to several second layer metals (101) as bucking electrode, for completely cutting off other
So as to eliminate background capacitance, the insulating barrier between 101,102 and this double layer of metal forms mask capacitor to circuit.Each sensing screen
Cover electrode and be divided into 5 pieces（101a, 101b, 101c, 101d, 101e）, wherein 101a, 101e connection constant voltage so that each
Edge parasitic capacitance between sensing is roughly the same, 101b, 101c, and 101d is connected on variable voltage, is driven by sensing
Drives.By adjusting 101b, 101c, the variable voltage linked by 101d can obtain a kind of sensing of optimal susceptiveness
Unit.Reference capacitance and on-off circuit are placed under the double layer of metal.The domain structure causes the electric charge of hundreds of thousands of sensings
Share concordance（The concordance of each sensing parasitic capacitance）, further improve the quality of fingerprint output image.
Referring to Fig. 4 and Fig. 5, wherein Fig. 4 a figures are the fingerprint images obtained by conventional condenser acquisition system collects dry finger
Picture, it appears that fingerprint lines is too shallow to be difficult identification, and Fig. 4 b are capacitance type fingerprint acquisition systems of the present invention by real-time self adaptation
Process algorithm circuit is adjusting the fingerprint image that the programmable comparator array of input reference voltage is obtained, it appears that clearly may be used
See.Fig. 5 a figures are the fingerprint images obtained by conventional condenser acquisition system collects wet finger, it appears that fingerprint lines is obscured
Unclear to be difficult identification, Fig. 5 b figures are that capacitance type fingerprint acquisition system of the present invention is adjusted by real-time adaptive process algorithm circuit
The fingerprint image that the programmable comparator array of section input reference voltage is obtained, it appears that high-visible.
Those skilled in the art is gone back under conditions of the spirit and scope of the present invention determined without departing from claims
Various modifications can be carried out to above content.Therefore the scope of the present invention is not limited in the explanation of the above, but by
The scope of claims is determining.
Claims (1)
1. Novel capacitance type fingerprint image acquisition system, including
One sensing element array, comprising multiple sensings；
One sensing array drive circuit, for sensing element array input voltage signal；
One insulating surface, is covered on the sensing element array, as the contact surface of a finger；
One comparator array, is configured at by the sensing element array, and the output for sensing element array is input into as which；
One programmable reference voltage source, used as an input reference voltage of comparator array；
One adaptive process algorithm logic circuit, for the programmable reference voltage source of Automatic adjusument；
Characterized in that, sensing element array connects and is transfused to a first voltage signal, in each sensing one is made with reference to electricity
Hold two ends or sense capacitance two ends produce a voltage difference；A second voltage signal is input into afterwards, makes reference capacitance two ends and shielding
Electric capacity two ends no-voltage is poor, or sense capacitance two ends and mask capacitor two ends no-voltage it is poor；Then it is input into tertiary voltage letter
Number, make bucking electrode be linked to a voltage, make the sense capacitance, after the mask capacitor carries out charge share with the reference capacitance
Linking for the reference capacitance and the sense capacitance and the mask capacitor is disconnected again；Order repeatedly inputs second, tertiary voltage letter
Number, again the energizing signal of each comparator is exported until comparator occurs upset, as the gray level image letter for collecting
Breath；
Each sensing is also included：
One sensor construction, including：
One sensing electrode, forms sense capacitance with finger, insulating surface；
Two reference electrodes；And
One insulating barrier, is configured between two reference electrodes, and can form reference capacitance between reference electrode and insulating barrier at two；
One bucking electrode and the insulating barrier being configured between bucking electrode and sensing electrode, in bucking electrode, insulating barrier and sensing
Mask capacitor is formed between electrode；And
Multiple switch circuit；
The real-time com-parison and analysis device array of adaptive process algorithm logic circuit is input into grayscale fingerprint image information therein, afterwards
A feedback signal is exported for adjusting the reference voltage level of comparator array；
The domain structure of multiple sensings is as follows：
Last layer of metal as sensing electrode, layer metal second from the bottom as bucking electrode, for completely cut off other circuits so as to
Background capacitance is eliminated, between the insulating barrier and the double layer of metal between this double layer of metal, mask capacitor is formed；Each sensing
Bucking electrode is sequentially divided into polylith, wherein two pieces of edge connection constant voltage so that the edge parasitic between each sensing
Electric capacity is identical, and remaining block is connected on variable voltage source, is driven by sensing drive circuit.
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| CN201210345176.1A CN103679163B (en) | 2012-09-18 | 2012-09-18 | Novel capacitance type fingerprint image acquisition system |
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| CN201210345176.1A CN103679163B (en) | 2012-09-18 | 2012-09-18 | Novel capacitance type fingerprint image acquisition system |
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| CN103679163B true CN103679163B (en) | 2017-03-22 |
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| CN104156709B (en) * | 2014-08-26 | 2019-07-16 | 南昌欧菲生物识别技术有限公司 | Fingerprint recognition detection components, terminal device and fingerprint authentication method |
| CN105512714B (en) * | 2014-09-26 | 2019-02-15 | 上海思立微电子科技有限公司 | A kind of fingerprint Identification sensor and its induction region |
| CN107092896A (en) | 2014-12-30 | 2017-08-25 | 深圳市汇顶科技股份有限公司 | Fingerprint Identification sensor and terminal device |
| WO2016139857A1 (en) * | 2015-03-04 | 2016-09-09 | ソニー株式会社 | Analog-digital converter, solid-state imaging device, and electronic apparatus |
| TWI515665B (en) * | 2015-03-25 | 2016-01-01 | 速博思股份有限公司 | Finger-swiping biometric recognition apparatus |
| KR101908211B1 (en) * | 2015-04-24 | 2018-10-15 | 선전 구딕스 테크놀로지 컴퍼니, 리미티드 | Pixel sensing circuit for fingerprint identification, system and electronic device |
| TWI598827B (en) * | 2015-04-24 | 2017-09-11 | 速博思股份有限公司 | Biometric feature identification device and method |
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| TWI591509B (en) * | 2015-08-27 | 2017-07-11 | 瑞鼎科技股份有限公司 | Capacitive fingerprint sensing apparatus and capacitive fingerprint sensing method |
| CN106096374B (en) * | 2016-07-21 | 2019-03-22 | 珠海市魅族科技有限公司 | The control method and associated electronic device of electronic equipment |
| TWI602100B (en) * | 2016-07-29 | 2017-10-11 | 義隆電子股份有限公司 | Operating method for a fingerprint sensing device and fingerprint sensing system |
| EP3321849B1 (en) | 2016-09-27 | 2020-07-22 | Shenzhen Goodix Technology Co., Ltd. | Fingerprint recognition system and electronic device |
| WO2018098779A1 (en) * | 2016-12-01 | 2018-06-07 | 深圳市汇顶科技股份有限公司 | Capacitive sensing system and related voltage correction method therefor |
| CN108256407B (en) * | 2017-01-05 | 2023-08-04 | 广州市晶密电子有限公司 | Method and device for jointly collecting and identifying fingerprints by using multiple sensors |
| CN108985136B (en) * | 2017-06-02 | 2021-08-24 | 旭景科技有限公司 | Noise reduction capacitive image sensor and operation method thereof |
| US10395084B2 (en) * | 2017-09-29 | 2019-08-27 | Superc-Touch Corporation | Fingerprint identification device |
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