CN1035495C - Semi-conductor integrated detector for abstrating fingerprints pattern - Google Patents
Semi-conductor integrated detector for abstrating fingerprints pattern Download PDFInfo
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- CN1035495C CN1035495C CN94119003A CN94119003A CN1035495C CN 1035495 C CN1035495 C CN 1035495C CN 94119003 A CN94119003 A CN 94119003A CN 94119003 A CN94119003 A CN 94119003A CN 1035495 C CN1035495 C CN 1035495C
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Abstract
The present invention relates to a semiconductor integrated detector for extracting fingerprint images. The present invention comprises a sensitive unit, a driving circuit and a surface enhancement element, wherein the sensitive unit is composed of a sensitive electrode, a switching device and a leak resistor; the driving circuit is composed of a row column shift register, a column shift register, a column switching switch and a column charge amplifying circuit; the surface enhancement element is composed of an additional electrode and enhancement metal grids. The present invention outputs extracted fingerprint characteristics which are transmitted to an image processor; a fingerprint identifier compares newly input fingerprint characteristic data with previously stored data so as to achieve the purpose of identification. Compared with a method for extracting the fingerprint images by an optical system, the present invention has small size and provides real images.
Description
The present invention relates to a kind of fingerprint recognition system, relate in particular to the semiconductor integrated detector that finger print image extracts that is used in a kind of fingerprint recognition system.
Fingerprint recognition system is used very extensive, can be used for the place of high security, as the place of bank or low confidentiality, as substituting conventional door lock or the like.The major advantage of this system is easy to use, and is simple, neither needs key also not need password, and can reduce the duplicity use greatly.Detecting device is the very important part of fingerprint recognition system, and the quality of the finger print image that is extracted by it has directly influenced the image processing and the distinguishing ability of back.
Conventional finger print detection device depends on the method for optical detection.A simple optical detection apparatus is easy to be cheated by copying picture of fingerprint, and another kind of method safer and commonly used is to have adopted a glass prism, the image that takes the fingerprint of the frustrated total reflection by inside.Light enters from first face, locates to take place frustrated total reflection at second, and from the 3rd output.Finger is placed on second, and every finger does not all have reflection ray with second part that contacts fully, and only recess and the glass at fingerprint discontiguously has reflection ray just now.Can obtain chequered with black and white scale-of-two finger print image by this method.But there are many shortcomings in this optical detection system, and at first too benzene is heavy for its volume, and secondly it requires the surface of contact must be very clean and tidy and do not have dirt, in addition, when finger is very dry, can produce the discontinuous discontinuous point of fingerprint line.Strengthened the difficulty of image processing like this.
The objective of the invention is to, design a kind of volume little, be easy to be contained in the new-type fingerprint detector on the various fingerprint recognition systems.Make it to reduce fingerprint temperature and dust to the influence of the image that takes the fingerprint and can obtain the scale-of-two finger print image and the finger print image of two and three dimensions can be provided.
The present invention be achieved in that newly-designed detecting device comprise responsive detecting unit several, driving circuit, surface strengthen element three parts and form.Each responsive detecting unit comprises sensitive electrode, switching device and bleeder resistance again, driving circuit comprises line shift register, column shift register, row change-over switch, row charge amplifying circuit, comprises supplemantary electrode in the surface increase element, strengthens metal grill.Insulating material is arranged on sensitive electrode, supplemantary electrode is arranged thereon, between its space, be added with metal grid lines.On-off element is selected field effect transistor (transistor also can) for use.Connect same capable addressed line in fet gate with delegation, the field effect transistor source electrode of same row connects same row addressed line, the drain electrode of each field effect transistor connects sensitive electrode, the drain electrode of each field effect transistor and public ground is bleeder resistance indirectly, in each row shared change-over switch and charge amplifying circuit, the driving circuit of going has in the ranks used shift register to drive, and the driving circuit bit shift register of row, the switch detecting device adopts the two-dimensional matrix structure.So each is listed as responsive detecting unit and all is connected with driving circuit.Each responsive detecting unit contains a responsive detecting electrode, and electrode is coated with insulating material, and is connected with a switching device.Each unit is addressable all, adds a voltage for each electrode by driving circuit.When finger is placed on the detecting device, can measure the capacitance variations between finger and the detecting electrode.
Driving circuit adds a voltage for sensitive electrode by certain time interval in advance, extracts in the operation at continuous finger print image, needs to remove or reduce to add electromotive force in advance on the sensitive electrode.This can add potential value in advance and realize by connecing a stake resistance or changing.In fingerprint and the formed electric capacity of sensitive electrode, the charging current that flows into this electric capacity depends on the size of this electric capacity, and capacitance size depends on the space length between fingerprint surface and the detection means surface.Charge sensitive amplifier in the driving circuit can detect the charging current that flows to each sensitive electrode, can certainly adopt other similar method to detect charging current.
The switching device of sensing unit is a three terminal device, links driving circuit and sensitive electrode by address conductors respectively as its source electrode of field effect transistor and drain electrode, and control signal is added to grid by driving circuit and address conductors, and sensing unit is arranged in matrix structure.
The shared address conductors because the source electrode of each row transistor connects together, the grid of each rowed transistor shared address conductors that connects together.Like this each sensing unit all successively addressing obtain a complete capacitance image for one time.
Insulating material can be selected any appropriate insulation material for use, forms the uniform successive layers of a layer thickness as polyimide and covers on the sensitive electrode.In addition, can make the netted lead of layer of metal on the insulating material surface, to improve the electrically contacting property on fingerprint surface.These netted leads and ground wire join.A complete fingerprint control system generally comprises three parts.The one, the fingerprint image extracts part, this part adopts pick-up unit of the present invention to realize, two parts are that finger print image is handled and finger print image is differentiated in addition, and the class signal of exporting from fingerprint detector of the present invention is similar to the finger print image information of extracting by optical system.The picture intelligence that can adopt the conventional method that is used for optical system that fingerprint detector is exported is handled and is differentiated.
Detecting device of the present invention can provide three-dimensional finger print image, so can improve accuracy of identification greatly, adopts its two-dimensional image also can satisfy the demand in the not too high place of accuracy requirement certainly.
The invention has the advantages that this detection means has adopted similar addressing technique to the active array addressing display device.So this detection means can be used similar techniques manufacturing, on dielectric base, form sensitive electrode with thin-film deposition and photoetching, address conductors and thin film transistor (TFT).Also can adopt the SIC (semiconductor integrated circuit) technology to realize in addition.These two kinds of methods have all reduced the volume of finger print image detection means greatly.
Adopt the detecting unit of active-addressed structure fabrication to significantly reduce driving circuit and line, make this detecting device to do very for a short time.Be easy to be contained on the various fingerprint recognition systems.
When using, formed an electric capacity between finger surface and the detecting electrode.Because of the different electric capacity that forms different capabilities of its distance apart from surface of insulating layer, fingerprint surface and sensitive electrode surface are respectively two utmost points of electric capacity between fingerprint surface and the sensitive electrode.The fingerprint surface is a zero potential.The thickness that depends on insulation course in the local electric capacity of fingerprint projection.Place in the fingerprint depression, electric capacity is decided by the space length between insulation course and insulation course and the fingerprint depression, by such sensing unit display, on behalf of the space length between fingerprint surface and the surface of insulating layer, the electric capacity of measuring change, thereby has obtained the three-dimensional image information of the fingerprint represented with capacitance.Because the image that obtained is three-dimensional,, significantly reduced the duplicity operation compared with above-mentioned optical detection system.Also significantly reduced simultaneously the influence of the temperature of fingerprint and dust to the image that takes the fingerprint.
In addition, also can each sensitive electrode over against surface of insulating layer make a people's supplemantary electrode.Like this, form an electric capacity between each supplemantary electrode and sensitive electrode, middle across insulation course.Whether the projection according to fingerprint obtains different capacitances with the supplemantary electrode contact.Like this, clearly illustrate that the place that the fingerprint projection occurs, like this, be easy to obtain a scale-of-two finger print image.
Describe fingerprint detector of the present invention in detail below in conjunction with the accompanying drawing example.
Fig. 1 is that a complete fingerprint recognition system is implemented block diagram.
Fig. 2 is the use synoptic diagram of detecting device.
Fig. 3 is whole schematic diagrams that this detecting device is realized, detecting unit and driving circuit are arranged above.
Fig. 1 complete fingerprint recognition system of having drawn realizes block diagram.Fingerprint detection device 66 has wherein adopted detecting device of the present invention, and is similar from the fingerprint signal that the signal and the conventional fluorescence detector of detecting device 66 outputs are exported.Therefore, the circuit of other except fingerprint detector is all similar with conventional optical fingerprint identification system.Image processing circuit 67 is delivered in the output of detecting device 66, and with the feature that takes the fingerprint, fingerprint discriminator circuit 68 fingerprint characteristic data that will newly import and the data that are stored in the memory 69 in advance compare the purpose that reaches discriminating then.
Each responsive detecting unit has a sensitive electrode 3 to be connected on the active device shown in Fig. 2,3, and this active device is that a trigistor 2 is field effect transistor (FET).The row that each responsive detecting unit links to each other, (selection) and row (detection) addressed line 7 and 8 are carried out addressing, with all responsive detecting units of delegation all continuously on same capable addressed line 7, the responsive detecting unit of all of same row all is connected on same the row addressed line 8, and an end of row addressed line 7 is linked on the horizontal drive circuit 11.One end of row addressed line 8 is continuously to testing circuit 12.As shown in Figure 2, the grid of field effect transistor FET connects capable addressed line 7, and source electrode is received capable addressed line 8, and drain electrode connects sensitive electrode 3.
Referring to Fig. 3 detecting device is an active-addressed detecting device 9, responsive detecting unit 1 by the X-Y direction forms r capable (1～r), the C row (have only been drawn a part of row, column among 1～C) certain figure, have been embodied as the array that 300 row, 200 row form a well-regulated 3CM * 2CM.
Fig. 3 is the simple principle figure that this detecting device is realized, though this is a detection wafer but has reflected whole detector concept basically, it has comprised detection sensing unit 1, is respectively the row, column lead comprising switching device 2 and continuous sensitive electrode 3 and bleeder resistance 4,7,8.Ranks shift register 11,12 and row charge amplifier 40, row switch 15 consists of driving circuit, and links to each other with sensing unit respectively, and 14 are signal output, 16 is output line, and control circuit 10 provides the reset signal of shift register pulse and charge amplifier.46 is supplemantary electrode, and 45 metal grid lines.
The manufacturing of this detecting device can be adopted and be similar to the active array addressing display device, as the manufacturing technology of liquid crystal display device.This technology is widely used in production large tracts of land active matrix array now.
In brief, can adopt photoetching technique on the semiconductor-based end, can form sensitive electrode 3 and address conductors 7,8.
Fig. 2 is a specific embodiment, and this is the partial cross section view of detecting device, contains several sensitive electrodes 3 and form thin film transistor (TFT) TFT in substrate 21.Sputter one deck polycrystalline silicon material in substrate is cut into one by one independently TFT raceway groove then earlier.Can adopt suitable isolated material to form gate isolation similarly.Sensitive electrode 3 and addressed line the 7, the 8th, metal level form drain electrode and the source electrode of the inside extension formation TFT of the two.The place that intersects with row addressed line 7 on row addressed line 8 covers the last layer isolated material then, and by the metal level photoetching trip addressed line 7 of sputter, its inner extension is the grid of TFT on this layer isolated material.
Covered one deck barrier film 22 on substrate 21, this barrier film is deposited in by polyimide and forms one deck continuous detection face 23 in the substrate 21, above finger just is placed on.
This detecting device adopts ranks to be spaced apart the sensitive electrode array structure of 100 μ M.The thickness of separation layer 22 and material all have certain requirement.It is 4 that present embodiment is selected specific inductive capacity for use, and thickness is that the separation layer of 4 μ M is realized.
The operating process of this detecting device is as follows, and finger to be detected is placed on the detection faces 23, can see that from Fig. 2 the fingerprint projection of finger surface 24 contacts with detection faces 23, and the fingerprint depression has certain distance from detection faces.The projection of fingerprint is the thickness of separation layer 22 apart from the minor increment of sensitive electrode 3, each sensitive electrode 3 and above it corresponding finger surface be respectively the two poles of the earth of an electric capacity 26.As shown in phantom in Figure 2, this earth potential very of fingerprint surface, separation layer 22 has become the insulating material of electric capacity 26 with the space between detection faces 23 and the fingerprint surface, changes in capacitance becomes certain functional relation with space length d between fingerprint surface and the detection faces 23, high spot electric capacity at fingerprint is big, and is little at the recess electric capacity of fingerprint.
Concrete capacitance variations is that capacitor C x is PF/mm, and isolated material 22 specific inductive capacity are 4, and thickness is 4 μ M.Therefore, the detected changes in capacitance of sensing unit has formed a width of cloth three-dimensional electronic image on fingerprint surface.Because the variation of electric capacity has shown the three-dimensional information of fingerprint, so, can't carry out the duplicity operation with the duplicate of fingerprint.
The circuit of capacitance variations that detects each responsive detecting unit is as follows, and each sensing unit can be listed as (detection) addressed line 7 and 8 addressing by the row (selections) that it links to each other.Add a gate pulse by driving circuit 11 to row addressed line 7, make field effect transistor 2 (FET) conducting of all sensing unit product on this row.Meanwhile, add the voltage about 10V by 12 pairs of all row addressed line 8 of circuit, the electric capacity 26 that links to each other with all field effect transistor 2 is recharged immediately like this.Circuit 12 can detect the charging current that flows through row addressed line 8.The size of charging current depends on the size of electric capacity 26.
Therefore, by measuring the size that charging current on each row addressed line can record each electric capacity.Repeat this process up to all line scannings one time.Then can obtain a complete finger print image.
Fig. 3 has drawn and has been used for the charge detection circuit of two adjacent column wires.In this scheme, row address conductors 8 is connected to the amplifier 40 of capacitor feedback.Output on the output line 16 by shift register 12 and change-over switch 15.Need reset to amplifier 40 in continuous capable addressing gap.This is by controlling reset switch and discharge electric charge on the feedback capacity adding a reset pulse on the reset line 41.
Import a few width of cloth finger print images continuously, needing in time to eliminate the electric charge on the sensitive electrode 3.The present invention lets out resistance 4 and the electric charge of eliminating on the sensitive electrode 3 by what the capable lead 7 that is adjacent at sensitive electrode or the publicly-owned ground wire that adds all sensing units in addition linked to each other.
Certainly, for solving the problem of continuous input finger print image, also can adopt other to solve such as the voltage method that change is added in the row hunting.The method that also can adopt whole responsive detecting units to reset once solves continuous input problem.
Also can do following improvement to existing implementation, can on the detection surface of contact of detecting device, add the gap that layer of metal mesh lines 45 covers responsive detecting unit again.
With these metal wire ground connection, like this, can improve the degree that electrically contacts of finger surface.
In addition, in order to obtain finger print image more clearly, can be on the detection faces of original sensitive electrode 3 correspondences the metal electrode 46 of the identical size of superposition again.(day supplemantary electrode again).
Embodiment of the present invention, the SIC (semiconductor integrated circuit) technology of employing is made the TFT transistor on quartz substrate, and driving circuit 11 and testing circuit 12 all are integrated into the realization of a slice chip.
Claims (9)
1, a kind of semiconductor integrated detector of finger print image extraction is characterized in that: it comprises that driving circuit, surface increase element and some responsive detecting units, and each responsive detecting unit contains: sensitive electrode, switching device and bleeder resistance; Driving circuit contains: row, column shift register, row change-over switch, row charge amplifying circuit; The surface strengthens element and contains: supplemantary electrode, strengthen metal grill: switching device is a field effect transistor, grid with delegation's field effect transistor connects same capable addressed line, the source electrode of same row field effect transistor connects same row addressed line, drain electrode connects sensitive electrode, drain electrode and the indirect bleeder resistance in public ground, every row are shared change-over switch and charge amplifying circuit, this detecting device adopts the two-dimensional matrix structure, each is listed as responsive detecting unit and all is connected with driving circuit, the responsive detecting electrode of each responsive detecting unit, connect a switching device, each unit is addressable all, adds a voltage for each electrode by driving circuit, can survey finger changes with interelectrode capacitance, insulating material is arranged on sensitive electrode, supplemantary electrode is arranged thereon, between its space, be added with metal grid lines.
2, detecting device according to claim 1 is characterized in that: the driving circuit bit shift register driving of row, the driving circuit bit shift register of row.
3, detecting device according to claim 1, it is characterized in that: the insulating material on the sensitive electrode, can select any suitable insulating material for use, forming the even successive layers of a layer thickness as polyimide covers on the sensitive electrode, can make the netted lead of layer of metal on the insulating material surface, and be connected with ground wire.
4, detecting device according to claim 1 is characterized in that: detecting device is to form sensitive electrode with thin-film deposition and photoetching on dielectric base, address conductors and thin film transistor (TFT) or realize with the SIC (semiconductor integrated circuit) technology.
5, detecting device according to claim 1 is characterized in that: supplemantary electrode be each sensitive electrode over against surface of insulating layer on make, form an electric capacity like this between each additional capacitor and sensitive electrode, middle across insulation course.
6, detecting device according to claim 1, it is characterized in that: charge detection circuit row address conductors (8) is linked the amplifier (40) of capacitor feedback, link on the output line (16) by shift register (12) and change-over switch (15), reset line (41) is linked on the reset switch.
7, detecting device according to claim 1 is characterized in that: can on the detection surface of contact of detecting device, add the layer of metal mesh lines again, cover the gap of responsive detecting unit, and with these metal wire ground connection.
8, detecting device according to claim 1 is characterized in that: can be on the corresponding detection faces of original sensitive electrode (3), and the metal electrode of the identical size of superposition (46) again.
9, detecting device according to claim 1 is characterized in that: adopt the SIC (semiconductor integrated circuit) technology to make the TFT transistor on quartz substrate, and driving circuit (11) and testing circuit (12) all are integrated on the chip piece.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94119003A CN1035495C (en) | 1994-12-26 | 1994-12-26 | Semi-conductor integrated detector for abstrating fingerprints pattern |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94119003A CN1035495C (en) | 1994-12-26 | 1994-12-26 | Semi-conductor integrated detector for abstrating fingerprints pattern |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1125872A CN1125872A (en) | 1996-07-03 |
| CN1035495C true CN1035495C (en) | 1997-07-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94119003A Expired - Fee Related CN1035495C (en) | 1994-12-26 | 1994-12-26 | Semi-conductor integrated detector for abstrating fingerprints pattern |
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| CN (1) | CN1035495C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4366921B2 (en) * | 2002-07-12 | 2009-11-18 | セイコーエプソン株式会社 | Personal verification device, card-type information recording medium, and information processing system using the same |
| CN101762820B (en) * | 2009-12-18 | 2012-07-04 | 东南大学 | Flat panel detector |
| CN104866803B (en) * | 2014-02-20 | 2018-06-05 | 上海思立微电子科技有限公司 | A kind of finger print information detection circuit |
| CN104077565B (en) * | 2014-06-17 | 2018-04-06 | 京东方科技集团股份有限公司 | Fingerprint identification unit and electronic equipment |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4787742A (en) * | 1984-07-12 | 1988-11-29 | Fingermatrix, Inc. | Direct finger reading |
-
1994
- 1994-12-26 CN CN94119003A patent/CN1035495C/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4787742A (en) * | 1984-07-12 | 1988-11-29 | Fingermatrix, Inc. | Direct finger reading |
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| CN1125872A (en) | 1996-07-03 |
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