CN101526990B - Capacitance type fingerprint sensor and penal thereof - Google Patents

Abstract

The invention relates to a capacitance type fingerprint sensor, which comprises a fingerprint capacitor, an integrator, a first transistor, a second transistor and a multiplexer, wherein the capacitance value of the fingerprint capacitor is a valley capacitance value CFV or a convex capacitance value CFR, and the CFV is smaller than the CFR; the integrator is provided with a reference capacitor Cfb; the first transistor is used for controlling the fingerprint capacitor in a scanning line period; the second transistor is used for precharging the fingerprint capacitor and renewedly distributing electric charge between the fingerprint capacitor and the reference capacitor; and the multiplexer is connected to the integrator so as to provide a first voltage VA and a second voltage VB, wherein the first voltage VA is larger than the second voltage VB.

Description

Capacitance-typed fingerprint sensor and panel thereof

Technical field

The present invention relates to a kind of capacitance-typed fingerprint sensor and panel thereof, particularly relate to a plurality of transistorized capacitance-typed fingerprint sensors of a kind of use and panel thereof.

Background technology

Fingerprint inductor is a kind of inductor that is used to recognize finger grain pattern formula and the person identification of fiduciary level is provided.This fingerprint inductor also is used in portable product widely, and for example mobile phone, mobile computer are in order to guarantee the security of individual private data.

Figure 1A and 1B show the equivalent electrical circuit of fingerprint inductor.By and large, fingerprint inductor can be implemented in the chip, represents a protective seam in the numbering 13 of Figure 1A, and it is as capacitor C _dDielectric layer.If this fingerprint inductor is embedded in an image panel, represents an ITO layer in the numbering 11 of Figure 1A, and number 13 and represent glass and film, for example colored filter, Polarizer etc.Following narration is an example with the fingerprint inductor that is embedded in image panel.At Figure 1A, a metal level 11 and a substrate 12 are with the series system combination on the glass 13, one, and this glass 13 persons of being to use point the place that can touch.A common capacitor C _dBe present in the glass 13, and a capacitor C _PBe present between metal level 11 and the substrate 12.At Figure 1B, the surface of user's finger can be divided into protuberance 14 and recess 15.This recess 15 and this glass 13 have one apart from d2, and the thickness of this glass 13 is d1.Based on this structure, an extra capacitor C2 is present in the recess of this user's finger and the surface of this glass 13.This protuberance capacitance C _FRWith C ₁Relevant, recess capacitance C _FVWith C ₁//C ₂Relevant, C ₁With C ₁//C ₂Available following mode is represented:

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="S2008100832619E00031.png,S2008100832619E00051.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=\frac{{\mathrm{\&epsiv;}}_{1}A}{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="S2008100832619E00031.png,S2008100832619E00051.png"\; state="\{\{state\}\}">d</figure-callout>}}_1},$ And ${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="S2008100832619E00031.png,S2008100832619E00051.png"\; state="\{\{state\}\}">C</figure-callout>}}_1//C_2=\frac{1}{\frac{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="S2008100832619E00031.png,S2008100832619E00051.png"\; state="\{\{state\}\}">d</figure-callout>}}_1}{{\mathrm{\&epsiv;}}_{1}A}+\frac{d_2}{{\mathrm{\&epsiv;}}_{2}A}}$

Common this protuberance capacitance C _FRMuch larger than this recess capacitance C _FV

In order to respond to user's finger, a sensing circuit should distinguishable this protuberance capacitance and recess capacitance.Yet it also is not easy to obtain required accuracy, because the factor on some environment, and noise or cross-talk this result that all can detract for example.

Summary of the invention

One embodiment of capacitance-typed fingerprint sensor of the present invention comprises a sensing unit and a control circuit.This sensing unit comprises a fingerprint capacitor and a first transistor.The capacitance of this fingerprint capacitor is a recess capacitance C _FVAn or protuberance capacitance C _FR, and C _FV＜C _FRThis first transistor comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by the one scan line, and this input end is connected to this fingerprint capacitor, and this output terminal is connected to this sense wire.This control circuit comprises a transistor seconds, an operational amplifier, a reference capacitance, one the 3rd transistor and a multiplexer.This transistor seconds comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one first replacement line, and this input end is connected to this sense wire.One input end of this operational amplifier is connected to the output terminal of this transistor seconds.This reference capacitance has a capacitance C _Fb, and be arranged between the input end and output terminal of this operational amplifier.The 3rd transistor comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one second replacement line, and this input end and output terminal are connected to the input end and the output terminal of this operational amplifier respectively.This multiplexer is connected to another input end of this operational amplifier, and wherein the input end of this multiplexer is connected to one first voltage VA and one second voltage VB.

Another embodiment of capacitance-typed fingerprint sensor of the present invention comprises a fingerprint capacitor, an integrator, a first transistor, a transistor seconds and a multiplexer.The capacitance of this fingerprint capacitor is a recess capacitance C _FVAn or protuberance capacitance C _FR, and C _FV＜C _FRThis integrator has a reference capacitance C _FbThis first transistor is used in this fingerprint capacitor of one scan line periodic Control.This transistor seconds is used for this fingerprint capacitor of precharge, reaches redistributing charges between this fingerprint capacitor and reference capacitance.This multiplexer is connected to this integrator so that one first voltage VA and one second voltage VB to be provided, and wherein this first voltage VA is greater than this second voltage VB.

An embodiment who comprises the panel system of capacitance-typed fingerprint sensor of the present invention comprises active-matrix zone, a data driver, one scan driver, a sensing circuit and the image-processing circuit with a plurality of capacitance type fingerprint sensing units.This data driver is used for driving data.This scanner driver is used for the sweep trace of control linkage to this capacitance-typed fingerprint sensor.The kind that this sensing circuit is used to receive the data of this capacitance-typed fingerprint sensor and recognizes this fingerprint capacitor.This image-processing circuit is connected to this sensing circuit.

Description of drawings

Figure 1A and 1B show the equivalent electrical circuit of fingerprint inductor;

Fig. 2 shows a specific embodiment of panel of the present invention;

Fig. 3 shows a specific embodiment of fingerprint inductor of the present invention;

The sequential chart of Fig. 4 displayed map 3 circuit;

Pre-charging stage, translate phase and the estimating stage of Fig. 5 A to 5C displayed map 3 circuit; And

Fig. 6 shows a part of sensing circuit of a specific embodiment of the present invention.

The reference numeral explanation

Sheet metal 12 substrates on 11

13 protective seams, 14 fingerprint protuberances

15 fingerprint recesses

21 data drivers, 22 scanner drivers

23 sensing circuits, 24 image-processing circuits

25 panels

31 capacitance type fingerprint sensing units, 32 the first transistors

33 fingerprint capacitor, 34 transistor secondses

35 the 3rd transistors, 36 operational amplifiers

37 multiplexers, 38 control circuits

61 comparers, 62 multiplexers

C _FbReference capacitance

Embodiment

Fig. 2 shows a specific embodiment of panel of the present invention.This panel system comprises an active-matrix zone 25, a data driver 21, one scan driver 22, a sensing circuit 23 and an image-processing circuit 24.This active-matrix zone 25 comprises a capacitance-typed fingerprint sensor and/or a plurality of image pixel.This capacitance-typed fingerprint sensor has a plurality of capacitance type fingerprint sensing units 31, and each capacitance type fingerprint sensing unit 31 can optionally coexist as a pixel cell with an image pixel.This data driver 21 is used for driving data.This scanner driver 22 is used for the sweep trace of control linkage to this capacitance type fingerprint sensing unit 31.By and large, when this capacitance type fingerprint sensing unit 31 was operated, the sweep trace that is connected to this capacitance type fingerprint sensing unit 31 was activated in the whole operation process.This sensing circuit 23 is used to receive the analog signal of the sense wire of this capacitance type fingerprint sensing unit 31, and recognizes the pattern of this fingerprint capacitor 31, for example recess capacitance C _FVOr protuberance capacitance C _FRThis image-processing circuit 24 is connected to this sensing circuit 23.The structure of Fig. 2 is an example with the damascene structures of image panel, but those skilled in the art can know that all the structure of Fig. 2 can be changed and be applied in the chip easily.

Fig. 3 shows a specific embodiment of fingerprint inductor of the present invention.This sensing circuit 23 comprises a control circuit 38.Capacitance type fingerprint sensing unit 31 comprises a first transistor 32 and a fingerprint capacitor C _F, its capacitance is a recess capacitance C _FVAn or protuberance capacitance C _FR, and C _FV＜C _FRThe first transistor that is positioned at the same row in this active-matrix zone 25 is controlled by same sweep trace.This first transistor 32 comprises a gate terminal, an input end and an output terminal, wherein this gate terminal is controlled by the one scan line, and this input end is connected to this fingerprint capacitor, and this output terminal is connected to a sense wire, and wherein this sense wire also is connected to an input end of this control circuit 38.This control circuit 38 can be the part of this sensing circuit 23, and another part 61 is shown in Fig. 6.This control circuit 38 comprises a transistor seconds 34, an operational amplifier 36, a reference capacitance C _Fb, one the 3rd transistor 35 and a multiplexer 37, wherein this operational amplifier 36 and this reference capacitance C _FbAs an integrator.This transistor seconds 34 comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one first replacement line Reset1, and this input end is connected to this sense wire.One input end of this operational amplifier 36 is connected to an output terminal of this transistor seconds 34.This reference capacitance C _FbBe connected to the input end and the output terminal of this operational amplifier 36.The 3rd transistor 35 comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one second replacement line Reset, and this input end and output terminal are connected to the input end and the output terminal of this operational amplifier 36.This multiplexer 37 is connected to another input end of this operational amplifier 36, and wherein the input end of this multiplexer is connected to one first voltage VA and one second voltage VB.With regard to present embodiment, this first voltage VA is greater than this second voltage VB.

The sequential chart of Fig. 4 displayed map 3 circuit.By and large, share same sweep trace R in the fingerprint capacitor of same row _n, it is activated in the whole operation process that this is listed as all fingerprint capacitor.The sequential of one-period is divided into a pre-charging stage (phase one), a translate phase (subordinate phase) and an estimating stage (phase III), and does not overlap each other.This first replacement line Reset1 is activated in this pre-charging stage and estimating stage, and this second replacement line Reset is activated in this pre-charging stage and translate phase.When estimating stage, sense wire selects RLS in proper order by Vout ₁To Vout _xTransfer data to this image-processing circuit 24.

Fig. 5 A is presented at pre-charging stage, the equivalent electrical circuit of this fingerprint inductor.In pre-charging stage, this transistor seconds 34 and the 3rd transistor 35 are enabled, and this multiplexer 36 is selected VB.In view of the above, reference capacitance C _FbBe reset, and this second voltage VB is input to this fingerprint capacitor.At this moment, the electric charge that is stored in this fingerprint capacitor is C _F* VB.

Fig. 5 B is presented at translate phase, the equivalent electrical circuit of this fingerprint inductor.At translate phase, transistor seconds 34 is closed, and the 3rd transistor 35 is enabled, and VA selected by this multiplexer 36 so that this operational amplifier 36 output VA.

Fig. 5 C is presented at estimating stage, the equivalent electrical circuit of this fingerprint inductor.In estimating stage, this transistor seconds 34 is enabled, and the 3rd transistor 35 is closed, and this multiplexer 36 is still selected VA.At this moment, the electric charge that is stored in this fingerprint capacitor is redistributed to reference capacitance C _Fb, and the position that is detected according to user finger of this operational amplifier 36, promptly fingerprint protuberance or recess are output as and change it $\mathrm{VA}+\frac{(\mathrm{VA}-\mathrm{VB})\&times;C_{\mathrm{FR}}}{C_{\mathrm{fb}}}$ Or $\mathrm{VA}+\frac{(\mathrm{VA}-\mathrm{VB})\&times;C_{\mathrm{FV}}}{C_{\mathrm{fb}}}$

Fig. 6 shows a part of sensing circuit of a specific embodiment of the present invention.This sensing circuit 23 also comprises a multiplexer 62 and a comparer 61.This selects part 63 by Vout ₁To Vout _xAccept data and be resent to this image-processing circuit 24.The input end of this multiplexer 62 is connected to by Vout ₁To Vout _xThe data of selecting, and the output terminal of this multiplexer 62 is connected to this comparer 61.This position of comparer 61 outputs is to this image-processing circuit 24.In order to differentiate protuberance electric capacity and recess electric capacity, this comparer 61 uses a threshold voltage V _REF, and $\mathrm{VA}+\frac{(\mathrm{VA}-\mathrm{VB})\&times;C_{\mathrm{FR}}}{C_{\mathrm{fb}}}>V_{\mathrm{REF}}>\mathrm{VA}+\frac{(\mathrm{VA}-\mathrm{VB})\&times;C_{\mathrm{FV}}}{C_{\mathrm{fb}}}.$ In view of the above, if these comparer 61 output logic high level, the data that representative is received by fingerprint inductor are protuberance electric capacity.Otherwise, then be recess electric capacity.

Technology contents of the present invention and technical characterstic disclose as above, yet those skilled in the art still may be based on teaching of the present invention and announcements and done all replacement and modifications that does not deviate from spirit of the present invention.Therefore, protection scope of the present invention should be not limited to those disclosed embodiments, and should comprise various do not deviate from replacement of the present invention and modifications, and is contained by claim of the present invention.

Claims (6)

1. capacitance-typed fingerprint sensor comprises:

One sensing unit comprises:

One fingerprint capacitor, its capacitance are a recess capacitance C _FVAn or protuberance capacitance C _FR, and C _FV＜C _FRAnd

One the first transistor comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by the one scan line, and this input end is connected to an end of this fingerprint capacitor, the other end ground connection of this fingerprint capacitor, and this output terminal is connected to this sense wire; And

One control circuit comprises:

One transistor seconds comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one first replacement line, and this input end is connected to this sense wire;

One operational amplifier, its first input end is connected to the output terminal of this transistor seconds;

One reference capacitance has a capacitance C _Fb, and be arranged between the first input end and output terminal of this operational amplifier;

One the 3rd transistor comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one second replacement line, and this input end and output terminal are connected to the first input end and the output terminal of this operational amplifier respectively; And

One multiplexer, its output terminal are connected to second input end of this operational amplifier, and wherein the input end of this multiplexer is connected to one first voltage VA and one second voltage VB, and wherein this first voltage VA is greater than this second voltage VB.

2. capacitance-typed fingerprint sensor as claimed in claim 1, its operation serial word be in a pre-charging stage, a translate phase and an estimating stage,

Wherein in this pre-charging stage, this sweep trace, the first replacement line and the second replacement line are activated, and this multiplexer exports this second voltage VB,

Wherein at this translate phase, this sweep trace and the second replacement line are activated, and this first replacement line is not activated, and this multiplexer exports this first voltage VA,

Wherein in this estimating stage, this sweep trace and the first replacement line are activated, and this second replacement line is not activated, and this multiplexer is exported this first voltage VA.

3. panel system that comprises capacitance-typed fingerprint sensor comprises:

One has the active-matrix zone of a plurality of capacitance type fingerprint sensing units, and respectively this capacitance type fingerprint sensing unit comprises:

One fingerprint capacitor, its capacitance are a recess capacitance C _FVAn or protuberance capacitance C _FR, and C _FV＜C _FRAnd

One the first transistor comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by the one scan line, and this input end is connected to an end of this fingerprint capacitor, the other end ground connection of this fingerprint capacitor, and this output terminal is connected to this sense wire;

The one scan driver is used to control described sweep trace;

One sensing circuit comprises:

One transistor seconds comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one first replacement line, and this input end is connected to this sense wire;

One operational amplifier, its first input end is connected to the output terminal of this transistor seconds;

One reference capacitance has a capacitance C _Fb, and be arranged between the first input end and output terminal of this operational amplifier;

One the 3rd transistor comprises a gate terminal, an input end and an output terminal, and wherein this gate terminal is controlled by one second replacement line, and this input end and output terminal are connected to the first input end and the output terminal of this operational amplifier respectively; And

One multiplexer, its output terminal are connected to second input end of this operational amplifier, and wherein the input end of this multiplexer is connected to one first voltage VA and one second voltage VB, and wherein this first voltage VA is greater than this second voltage VB; And

One image-processing circuit is connected to this sensing circuit,

Wherein this sensing circuit also comprises an output multiplexer and a comparer, the input end of this output multiplexer is connected to the output terminal of this operational amplifier, the output terminal of this output multiplexer is connected to an input end of this comparer, and another input end of this comparer is connected to a threshold voltage V _REF, the output terminal of this comparer is connected to this image-processing circuit.

4. panel system as claimed in claim 3, wherein this comparer is exported one to this image-processing circuit.

5. panel system as claimed in claim 3, wherein

6. panel system as claimed in claim 3, wherein when this capacitance type fingerprint sensing unit was operated, the one scan line that is connected to this capacitance type fingerprint sensing unit was activated.

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