CN107526993A - Capacitive fingerprint sensing device - Google Patents
Capacitive fingerprint sensing device Download PDFInfo
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- CN107526993A CN107526993A CN201610448202.1A CN201610448202A CN107526993A CN 107526993 A CN107526993 A CN 107526993A CN 201610448202 A CN201610448202 A CN 201610448202A CN 107526993 A CN107526993 A CN 107526993A
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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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Abstract
A kind of capacitive fingerprint sensing device includes a capacitive sense array and an amplifier.Amplifier includes a correlation Double sampling amplifier and a differential amplifier.Correlation Double sampling amplifier has two inputs and two output ends, one of wherein two input is optionally electrically connected with each sensing unit in capacitive sense array, to receive a sensing bias, another input receives a reference bias, and correlation Double sampling amplifier exports gain sensing bias and gain reference bias.Differential amplifier receives the gain sensing bias and gain reference bias that correlation Double sampling amplifier is exported, and the difference of gain amplifier sensing bias and gain reference bias.Above-mentioned capacitive fingerprint sensing device can reduce common-mode noise and through direct current shifting processing, therefore can effectively lift sensing sensitivity.
Description
【Technical field】
The present invention is about a kind of fingerprint sensor, particularly a kind of capacitive fingerprint sensing device.
【Background technology】
The principle of capacitive fingerprint sensing device be detect human finger spine and valley between capacitance variations.Valley
Normal depth is about 20-35 μm, wherein dielectric constant during filling air is 1.The dielectric constant of tissue is about 4-8, because
This, small capacitance variations can be detected by capacitive fingerprint sensing device.
Fig. 1 be refer to illustrate the method for sensing of the capacitive fingerprint sensing device based on charge sharing method.Condenser type refers to
Line sensor includes the sensing unit SU of multiple arrays arrangement.When fingerprint FP contacts with capacitive fingerprint sensing device, fingerprint FP
Spine and valley there is electric capacity C3.And dielectric layer DL can be formed by encapsulating capacitive fingerprint sensing device, it has electric capacity C2.Cause
This, electric capacity C2 and electric capacity C3 is concatenated with one another then has capacitance Cs, it can be calculated with following equation：
1/Cs=1/C2+1/C3, wherein C2 and C3 represent electric capacity C2 and electric capacity C3 capacitance respectively.
Measuring capacitance Cs change can be realized by following steps.First, conducting switchs Sa and disconnects switch Sb, with bias
Va precharges to electric capacity C0.It is then turned off switching the Sa and disconnected pass Sb of conducting, redistributes the electric charge in electric capacity C0, so
Bias V1 is produced, it can be calculated with following equation：
V1=Va*C0/ (C0+C1+Cs), wherein C0 and C1 represent electric capacity C0 and electric capacity C1 capacitance respectively.Electricity
Hold the parasitic stray capacitance that C1 is circuit.The bias V1 of sensing unit SU11 sense node is exported inclined by buffer amplifier BA
V2 is pressed, it can be calculated with following equation：
V2=g*V1
Wherein g is buffer amplifier BA gain.Each sensing unit SU has a buffer amplifier BA, and it is opened by row
Sr1 and the Sc1-Sc3 controls output of row switch are closed to sampling capacitor Csh.For example, sensing unit SU11 is switched by row
Sr1 and row switch Sc1 control outputs；Sensing unit SU12 is by row switch Sr1 and row switch Sc2 control outputs；Sensing
Cell S U13 is by row switch Sr1 and row switch Sc3 control outputs.Finally, analog-to-digital converter ADC is by sampling capacitor
Csh bias V3 is converted to number format.Due to common-mode noise (common mode noise) influence, not only each sensing
The uniformity that unit exports bias is poor, or even same sensing unit exports the uniformity of bias in different charging-discharging cycles
Also it is poor, thus follow-up signal transacting is influenceed, such as direct current displacement (DC subtraction).
Fig. 2 and Fig. 3 is refer to, to illustrate the direct current shifting processing of sensing signal.Assuming that a sensing unit SUa correspondingly refers to
The initial sensing signal of line valley is Vs1a, and the initial sensing signal of corresponding fingerprint ridges is Vs2a, therefore, this sensing unit
SUa, which corresponds to the valley of fingerprint or spine, has a voltage difference delta V1a, as shown in the left side of fig 2.Similarly, sensing unit SUb is corresponding
The initial sensing signal of fingerprint valley is Vs1b, and the initial sensing signal of corresponding fingerprint ridges is Vs2b, therefore, this sensing unit
SUb, which corresponds to the valley of fingerprint or spine, has a voltage difference delta V1b, as illustrated at the right side of figure 2.Sensing unit SUa, SUb institute is defeated
The initial sensing signal gone out is through direct current shifting processing, that is, after deducting bias DCsub, you can in the scope of a setting voltage Vset
Interior amplification, makes that sensing unit SUa, SUb corresponds to the valley of fingerprint or the voltage difference delta V1a of spine, Δ V1b are enlarged into voltage difference delta
V2a, Δ V2b, as shown in figure 3, can so increase the sensitivity of sensing.However, due to the influence of common-mode noise, difference sensing
Cell S Ua, SUb corresponds to the initial sensing that the valley of fingerprint or spine or same sensing unit are exported in different charging-discharging cycles
Signal and voltage difference delta V1a, Δ V1b have difference, its unfavorable follow-up signal transacting.For example, please with reference to Fig. 2
And Fig. 3, if being put after making direct current shifting processing to the initial sensing signal of sensing unit SUa, SUb with identical bias DCsub
Greatly, sensing unit SUa, SUb corresponds to the valley of fingerprint or the voltage difference of spine is respectively Δ V2a and Δ V2b.It will be apparent that
Sensing unit SUb is relatively low for the valley of fingerprint or the identification of spine.
In view of this, there is provided a kind of influence for reducing common-mode noise is sensed with lifting the capacitance type fingerprint of sensing sensitivity
Device is the target that current pole need to make great efforts.
【The content of the invention】
The present invention provides a kind of capacitive fingerprint sensing device, and it is single using correlation Double sampling amplifier amplification sensing
The sensing bias and a reference voltage and output one gain sensing bias and a gain reference voltage that member is exported, then pass through
The difference of one differential amplifier gain amplifier sensing bias and gain reference voltage can reduce common-mode noise to lift electric capacity
The sensing sensitivity of formula fingerprint sensor.
The capacitive fingerprint sensing device of one embodiment of the invention includes a capacitive sense array and an amplifier.Electric capacity
Formula sensing array includes the sensing unit of multiple arrays arrangement, and each of which sensing unit exports a corresponding sensing bias.
Amplifier includes a correlation Double sampling amplifier and a differential amplifier.Correlation Double sampling amplifier has two
Input and one of two output ends, wherein two input are optionally electrically connected with each sensing unit, with
Sensing bias is received, another input receives a reference bias, and correlation Double sampling amplifier output one gain sensing is inclined
Pressure and gain reference bias.Differential amplifier is electrically connected with correlation Double sampling amplifier, double to receive correlation
The gain sensing bias and gain reference bias that resampling amplifier is exported, and gain amplifier sensing bias and gain ginseng
Examine the difference of bias.
Coordinate appended schema elaborate by specific embodiment below, when being easier to understand the purpose of the present invention, skill
Art content, feature and its it is reached the effect of.
【Brief description of the drawings】
Fig. 1 is a schematic diagram, capacitive fingerprint sensing device known to display.
Fig. 2 is a schematic diagram, shows that different sensing units correspond to the initial sensing signal of fingerprint valley and spine.
Fig. 3 is a schematic diagram, shows that different sensing units correspond to the sensing signal of the amplification of fingerprint valley and spine.
Fig. 4 is a schematic diagram, shows the amplifier of the capacitive fingerprint sensing device of one embodiment of the invention.
Fig. 5 is a schematic diagram, shows the sensing unit of the capacitive fingerprint sensing device of one embodiment of the invention.
【Symbol description】
10 amplifiers
11 correlation Double sampling amplifiers
12 differential amplifiers
ADC analog-to-digital converters
BA buffer amplifiers
C0 electric capacity, sense capacitance
C1~C3 electric capacity
Cr0, reference capacitance
Cr1 electric capacity
Cfb1, Cfb2 feedback capacitor
Cin1, Cin2 input capacitance
Cs capacitances
Csh sampling capacitors
DCsub is biased
DL dielectric layers
FP fingerprints
IL separation layers
OP operational amplifiers
Sa, Sb, Sra, Srb are switched
Sc1~Sc3 rows switch
SF senses surface
Sr1 row switches
The Resetting Switching of Sre1, Sre2 first
The Resetting Switching of Sre3, Sre4 second
Ss1, Ss2 sampling switch
SU sensing units
SU11~SU13 sensing units
SUa, SUb sensing unit
V1~V3 is biased
Va is biased
Vcm fixed-bias transistor circuits
Vgdc bias differences
Vgs gains sensing bias
Vgr gain references bias
Vref reference bias
Vset sets voltage
Vs sensing biass
The sensing signal of Vs1a, Vs1b valley
The sensing signal of Vs2a, Vs2b spine
Δ V1a, Δ V1b voltage differences
Δ V2a, Δ V2b voltage differences
【Embodiment】
Various embodiments of the present invention are will be described below, and coordinate schema illustratively.In addition to the plurality of detailed description,
The present invention also can be widely performed in other embodiments, and the replacement easily of any embodiment, modification, equivalence changes are all
Within the scope of the present invention, and by claim it is defined.In the description of specification, in order that reader is to the present invention
There is more complete understanding, there is provided many specific details；However, the present invention may be before clipped or whole specific details
Put, can still implement.Moreover, it is well known that the step of or element be not described in details, with avoid to the present invention formed not
Necessary limitation.Same or similar element will be represented with same or like symbol in schema.It is specifically intended that schema is only
For the size or quantity of the use of signal, not representation element reality, some details may not drawn completely, in the hope of the letter of schema
It is clean.
Fig. 4 and Fig. 5 is refer to, the capacitive fingerprint sensing device of one embodiment of the invention includes a capacitance type sensing battle array
Row and an amplifier 10.Capacitive sense array includes the sensing unit of multiple arrays arrangement, and each of which sensing unit is defeated
Go out to correspond to spine or a sensing bias of valley and a reference bias for fingerprint.In an embodiment, sensing is biased to
And reference bias has identical common-mode noise (common mode noise).For example, Fig. 5 is refer to, each sensing is single
First SU includes an a sense capacitance C0 and reference capacitance Cr0.Sense capacitance C0 senses table close to the one of capacitive sense array
Face SF is set, and corresponds to fingerprint FP spine with output or the sensing of valley biases Vs.Switch Sa, Sb shown in Fig. 5 and
Electric capacity C1 function and mode of operation are identical with the element that same-sign is indicated in Fig. 1, will not be repeated here.Reference capacitance Cr0
Then the sensing surface SF away from capacitive sense array is set, to avoid spine of the reference capacitance Cr0 capacitance because of fingerprint FP
Or valley contact senses surface SF and changed.In other words, the reference bias Vref that reference capacitance Cr0 is exported can be considered a fixation
Bias.Likewise, switch Sra, Srb shown in Fig. 5 and switch Sa shown in electric capacity Cr1 function and mode of operation and Fig. 5,
Sb and electric capacity C1 are identical, will not be repeated here.
In an embodiment, each sensing unit SU sense capacitance C0 and reference capacitance Cr0 bearing of trend are vertical
The sensing surface SF of capacitive sense array.In short, each sensing unit SU sense capacitance C0 and reference capacitance Cr0 hang down
Intuition surveys surface SF arrangements, to reduce the valley of fingerprint or ridges contact sensing surface SF to reference capacitance Cr0 capacitance
Influence.In an embodiment, each sensing unit SU further includes a separation layer IL, and it is arranged at sense capacitance C0 and with reference to electricity
Between appearance Cr0 and it is grounded.According to this structure, the separation layer of ground connection can further reduce the valley or ridges contact sensing table of fingerprint
Influences of the face SF to reference capacitance Cr0 capacitance.
Refer to Fig. 4, amplifier 10 include a correlation Double sampling (Correlated double sampling,
CDS) the differential amplifier 12 of amplifier 11 and one.Correlation Double sampling amplifier 11 and each sense of capacitive sense array
Cell S U (shown in Fig. 5) is surveyed to be electrically connected with.Correlation Double sampling amplifier 11 has two inputs, and it receives each respectively
The sensing bias Vs and reference bias Vref that sensing unit SU is exported, and two output ends, it exports gain sensing
Bias Vgs and gain reference bias Vgr.
In an embodiment, correlation Double sampling amplifier 11 is the framework of a balanced configuration, and it puts comprising a computing
Big device (Operational Amplifier) OP, two feedback capacitor Cfb1, Cfb2, two input capacitance Cin1, Cin2, two
Individual first Resetting Switching Sre1, Sre2, two second Resetting Switching Sre3, Sre4 and two sampling switches Ss1, Ss2.Computing
Amplifier OP has two inputs and two output ends of balanced configuration, and wherein operational amplifier OP output end is phase
The output end of pass formula Double sampling amplifier 11, and output gain sensing bias Vgs and gain reference bias Vgr.Feedback electricity
The both ends for holding Cfb1, Cfb2 are connected to operational amplifier OP input and output end.Input capacitance Cin1, Cin2
One end is connected to the input of operational amplifier, and the other end is electrically connected with sensing unit SU, to receive sensing bias Vs respectively
And reference bias Vref.
Continue described above, and first Resetting Switching Sre1, Sre2 both ends are connected to feedback capacitor Cfb1, Cfb2
Both ends.When first Resetting Switching Sre1, Sre2 is turned on, that is, feedback capacitor Cfb1, Cfb2 are reset to a predetermined bias.Second weight
The one end for putting switch Sre3, Sre4 is connected between input capacitance Cin1, Cin2 and operational amplifier OP input, another
End is connected to a fixed-bias transistor circuit Vcm.When second Resetting Switching Sre3, Sre4 is turned on, that is, reset input capacitance Cin1, Cin2 in
One predetermined bias.For example, when the second Resetting Switching Sre3 is turned on, input capacitance Cin1 predetermined bias about senses partially
Pressure Vs subtracts fixed-bias transistor circuit Vcm.Similarly, when the second Resetting Switching Sre4 is turned on, input capacitance Cin2 predetermined bias is about
Reference bias Vref subtracts fixed-bias transistor circuit Vcm.Sampling switch Ss1, Ss2 are connected to second Resetting Switching Sre3, Sre4 and returned
Feed holds between Cfb1, Cfb2.When sampling switch Ss1, Ss2 are turned on, input capacitance Cin1, Cin2 is connected to computing
Amplifier OP two inputs.According to the framework of above-mentioned correlation Double sampling amplifier 11, gain sensing bias Vgs and
Gain reference bias Vgr gain is determined by feedback capacitor Cfb1, Cfb2 and input capacitance Cin1, Cin2 capacitance
It is fixed.In an embodiment, feedback capacitor Cfb1, Cfb2 capacitance are less than the capacitance of input capacitance Cin1, Cin2, so i.e.
Output gain sensing bias Vgs and gain reference bias Vgr can be amplified.
Differential amplifier 12 is electrically connected with correlation Double sampling amplifier 11, to receive the amplification of correlation Double sampling
The gain sensing bias Vgs and gain reference bias Vgr that device 11 is exported, and gain amplifier sensing bias Vgs and one
Gain reference biases Vgr difference.In an embodiment, differential amplifier 12 is a programmable gain amplifier
(programmable gain amplifier, PGA).It is understood that the gain of programmable gain amplifier can be by one
External signal is controlled by.
Illustrate the mode of operation of amplifier 10 below.By the row switch and row switch in capacitive fingerprint sensing device
(as shown in Figure 1), selected sensing unit SU can be made to be connected to the input of correlation Double sampling amplifier 11, to read sense
Survey cell S U sensing result.Then, first Resetting Switching Sre1, Sre2 and second Resetting Switching Sre3, Sre4 is turned on,
Sampling switch Ss1, Ss2 disconnect, to reset feedback capacitor Cfb1, Cfb2 and input capacitance Cin1, Cin2.Now correlation is double
Resampling amplifier 11 is a replacement pattern.Then, by first Resetting Switching Sre1, Sre2 and the second Resetting Switching Sre3,
Sre4 disconnects, and sampling switch Ss1, Ss2 conducting, input capacitance Cin1, Cin2 is connected to operational amplifier OP input.This
When correlation Double sampling amplifier 11 be a sampling mode.It is understood that first Resetting Switching Sre1, Sre2 and
Needed during two Resetting Switching Sre3, Sre4 conducting with it is different during sampling switch Ss1, Ss2 conducting.
Correlation Double sampling amplifier 11 output gain sensing bias Vgs and gain reference bias when sampling mode
Vgr.Gain sensing bias Vgs and gain reference bias Vgr can be calculated and obtained with equation (1), (2)：
Vgs=Cin/Cfb × [(Vs_s-Vs_re)-Vcm]
(1)
Vgr=Cin/Cfb × [(Vref_s-Vref_re)-Vcm]
(2)
Wherein, Cfb is feedback capacitor Cfb1, Cfb2 capacitance, and Cin is the capacitance of input capacitance Cin1, Cin2,
Input capacitance Cin1 bias when Vs_re is replacement pattern, input capacitance Cin1 bias, Vref_ when Vs_s is sampling mode
Input capacitance Cin2 bias when re is replacement pattern, input capacitance Cin2 bias, Vcm are solid when Vref_s is sampling mode
Fixed bias.
Gain sensing bias Vgs and gain reference bias Vgr difference can be calculated with equation (3)：
Vgs-Vgr=Cin/Cfb × [(Vs_s-Vs_re)-(Vref_s-Vref_re)] (3)
It is understood that assume sense capacitance C0 and reference capacitance Cr0 capacitance it is identical, and sense capacitance C0 with
And reference capacitance Cr0 in one reset during with identical voltage source Va charge, then the bias Vs_re in equation (3) and partially
Press the influence of common-mode noise suffered by Vref_re that convergence is consistent.From aforesaid equation (3), the institute of differential amplifier 12 is defeated
Bias difference Vgdc after the amplification gone out will not be influenceed by common-mode noise.In an embodiment, the first Resetting Switching Sre1,
During Sre2 and second Resetting Switching Sre3, Sre4 conducting (when i.e. correlation Double sampling amplifier 11 is replacement pattern)
It is same (i.e. during sensing unit SU sense capacitance C0 and reference capacitance Cr0 charging) during being reset with the one of sensing unit SU
Step can exclude the influence of common-mode noise.
In addition, if bias Vref_s and bias Vref_re are different, that is, the difference of the two is not 0, then biases Vref_s
And bias Vref_re difference can be as the voltage potential for carrying out direct current displacement (DC subtraction) processing.Yu Yishi
Apply in example, sense capacitance C0 and reference capacitance Cr0 capacitance are identical.Therefore, in fingerprint FP not in contact with capacitance type sensing battle array
In the case of the sensing surface SF of row, bias Vs_s, Vs_re difference are approximately equal to bias Vref_s, Vref_re difference.Due to
Bias Vref_s, Vref_re will not because fingerprint FP whether touch mode capacitive sensing array sensing surface SF change, therefore,
After direct current shifting processing, the value of [(Vs_s-Vs_re)-(Vref_s-Vref_re)] can contract as far as possible in equation (3)
It is small, and output is amplified with the gain of larger multiplying power.
It is understood that each sensing unit SU can carry out direct current shifting processing with an identical voltage potential.Citing
For, there is provided the reference bias Vref of fixed voltage potential inputs correlation Double sampling amplifier 11, then each sensing unit
SU all will carry out direct current shifting processing with identical voltage potential.Or in an embodiment, each sensing unit SU is with relative
The respective voltage current potential answered carries out direct current shifting processing.For example, it is correspondingly arranged a reference in each sensing unit SU
Electric capacity Cr0, as shown in figure 5, then reference capacitance Cr0 capacitance is influenceed by processing procedure, encapsulation or other factorses, may with not
Capacitance with the reference capacitance Cr0 in sensing cell S U is variant.Therefore, carrying out direct current shifting processing will be according to sensing out of the ordinary
The reference bias that cell S U is exported.It is understood that between different sensing unit SU caused by processing procedure, encapsulation or other factorses
Sense capacitance C0 differences can be compensated for corresponding reference capacitance Cr0, make what is exported between different sensing unit SU
Sensing signal is more uniform.
Summary, capacitive fingerprint sensing device of the invention are to utilize correlation Double sampling amplifier amplification sensing
The sensing bias and a reference voltage that unit is exported, to export gain sensing bias and a gain reference voltage.
The difference of bias and gain reference voltage is sensed through a differential amplifier gain amplifier can not only reduce common-mode noise, and pass through
Direct current shifting processing, therefore the sensing sensitivity of capacitive fingerprint sensing device can be lifted effectively.
Embodiment described above is only technological thought and feature to illustrate the invention, and its purpose makes to be familiar with this skill
The personage of skill can understand the content of the present invention and implement according to this, when can not with restriction the present invention the scope of the claims, i.e., generally
The equivalent change made according to disclosed spirit or modification, should cover in the scope of the claims of the present invention.
Claims (14)
1. a kind of capacitive fingerprint sensing device, it is characterised in that include：
One capacitive sense array, it includes the sensing unit of multiple arrays arrangement, and each of which sensing unit output is relative
The sensing bias answered；And
One amplifier, it is included：
One correlation Double sampling amplifier, it has two inputs and two output ends, wherein two inputs its
One of be optionally electrically connected with each sensing unit, to receive sensing bias, another input receives a ginseng
Bias is examined, and the correlation Double sampling amplifier exports gain sensing bias and gain reference bias；And
One differential amplifier, it is electrically connected with the correlation Double sampling amplifier, put with receiving the correlation Double sampling
The gain sensing bias and gain reference bias that big device is exported, and amplify gain sensing bias and gain ginseng
Examine the difference of bias.
2. capacitive fingerprint sensing device as claimed in claim 1, it is characterised in that the correlation Double sampling amplifier bag
Contain：
One operational amplifier, it has two inputs and two output ends of balanced configuration, and the wherein operational amplifier is defeated
Go out gain sensing bias and gain reference bias；
Two feedback capacitors, the both ends of each of which feedback capacitor be connected to the operational amplifier the input and
The output end；
Two input capacitances, one end of wherein one of input capacitance are connected to the input of the operational amplifier, separately
One end is electrically connected with each sensing unit to receive sensing bias, and one end of another input capacitance is connected to the fortune
The input of amplifier is calculated, the other end receives the reference bias；
Two the first Resetting Switchings, the both ends of each of which first Resetting Switching be connected to the feedback capacitor this two
End；
Two the second Resetting Switchings, one end of each of which second Resetting Switching is connected to the input capacitance and the computing is put
Between the input of big device, the other end is connected to a fixed-bias transistor circuit；And
Two sampling switches, each of which sampling switch are connected between second Resetting Switching and the feedback capacitor.
3. capacitive fingerprint sensing device as claimed in claim 2, it is characterised in that two first Resetting Switchings and this two
During the conducting of individual second Resetting Switching with it is different during the conducting of two sampling switches.
4. capacitive fingerprint sensing device as claimed in claim 2, it is characterised in that two first Resetting Switchings and this two
It is synchronous during being reset during the conducting of individual second Resetting Switching with the one of the sensing unit.
5. capacitive fingerprint sensing device as claimed in claim 2, it is characterised in that it is defeated that the capacitance of the feedback capacitor is less than this
Enter the capacitance of electric capacity.
6. capacitive fingerprint sensing device as claimed in claim 2, it is characterised in that the differential amplifier is opened in this two samplings
The bias for inputting the differential amplifier is subjected to stream displacement (DC subtraction) processing always during the conducting of pass.
7. capacitive fingerprint sensing device as claimed in claim 6, it is characterised in that each sensing unit is with an identical voltage
Current potential carries out the direct current displacement (DC subtraction) processing.
8. capacitive fingerprint sensing device as claimed in claim 6, it is characterised in that each sensing unit is with corresponding one
Respective voltage current potential carries out the direct current shifting processing.
9. capacitive fingerprint sensing device as claimed in claim 1, it is characterised in that the sensing biases and reference bias tool
There is identical common-mode noise (common mode noise).
10. capacitive fingerprint sensing device as claimed in claim 1, it is characterised in that the differential amplifier is a programmable
Gain amplifier.
11. capacitive fingerprint sensing device as claimed in claim 1, it is characterised in that each sensing unit includes：
One sense capacitance, it is set close to a sensing surface of the capacitive sense array, to export sensing bias；And
One reference capacitance, its sensing surface away from the capacitive sense array is set, to export the reference bias.
12. capacitive fingerprint sensing device as claimed in claim 11, it is characterised in that the sense capacitance and the reference capacitance
Charged during one resets with identical voltage source.
13. capacitive fingerprint sensing device as claimed in claim 11, it is characterised in that the sense capacitance and the reference capacitance
Capacitance it is identical.
14. capacitive fingerprint sensing device as claimed in claim 11, it is characterised in that each sensing unit further include one every
Absciss layer, it is arranged between the sense capacitance and the reference capacitance and is grounded.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610448202.1A CN107526993A (en) | 2016-06-20 | 2016-06-20 | Capacitive fingerprint sensing device |
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|---|---|---|---|
| CN201610448202.1A CN107526993A (en) | 2016-06-20 | 2016-06-20 | Capacitive fingerprint sensing device |
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| CN201610448202.1A Withdrawn CN107526993A (en) | 2016-06-20 | 2016-06-20 | Capacitive fingerprint sensing device |
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| US11837013B2 (en) * | 2020-08-21 | 2023-12-05 | Shenzhen GOODIX Technology Co., Ltd. | Image sensor, fingerprint detection apparatus and electronic device |
| CN113257184A (en) * | 2021-05-10 | 2021-08-13 | 京东方科技集团股份有限公司 | Sampling circuit, driving method, pixel sampling circuit and display device |
| CN113257184B (en) * | 2021-05-10 | 2022-10-25 | 京东方科技集团股份有限公司 | Sampling circuit, driving method, pixel sampling circuit and display device |
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