CN105913048B - A kind of finger prints processing device - Google Patents
A kind of finger prints processing device Download PDFInfo
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- CN105913048B CN105913048B CN201610345108.3A CN201610345108A CN105913048B CN 105913048 B CN105913048 B CN 105913048B CN 201610345108 A CN201610345108 A CN 201610345108A CN 105913048 B CN105913048 B CN 105913048B
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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
The embodiment of the invention discloses a kind of finger prints processing devices, comprising: protective layer, glue, fingerprint collecting chip, collector, bucking circuit 1, PGA1, bucking circuit 2, PGA2, ADC, control chip；Collector is for amplifying and converting the capacitance signal of finger capacitor Cf to reduce the influence of noise of subsequent conditioning circuit；Bucking circuit 1 is used to carry out secondary fine counteracting to migration noise；Amplified signal is input in bucking circuit 2 by PGA1 for amplifying to the output signal of bucking circuit 1, and PGA1 uses larger gain to reduce the design requirement of subsequent conditioning circuit；Bucking circuit 2 is used to carry out secondary fine counteracting to migration noise；PGA2 is for properly adjusting signal amplitude；ADC is for output digit signals to control chip；Chip is controlled to be used to carry out feedback control based on digital signal.The migration noise generated in the resolution ratio and offseting signal treatment process of the signal of the valley and a ridge of user's finger when the embodiment of the present invention is conducive to improve acquisition user fingerprints.
Description
Technical field
The present invention relates to fingerprinting technique fields, and in particular to a kind of finger prints processing device.
Background technique
As shown in FIG. 1, FIG. 1 is the exemplary diagrams of common semiconductor fingerprint acquisition device acquisition user fingerprints.Wherein, fingerprint is adopted
Collection chip (i.e. sensor chip) is placed in below protective layer, and centre is combined together by gluing.As shown in Fig. 2, Fig. 2 be based on
The fingerprint collecting principle of semiconductor fingerprint acquisition sensor shown in FIG. 1.Wherein, the metal of finger and fingerprint collecting chip surface
Electrode forms parasitic capacitance.Since the distance of valley and a ridge to the metal electrode of finger is different, thus the parasitic capacitance formed is not yet
Together, so as to reflecting fingerprint graph by measurement parasitic capacitance.Since glue thickness is smaller, do not consider glue to parasitic capacitance
It influences.Parasitic capacitance (hereinafter referred to as finger capacitor Cf) expression formula between finger and metal electrode are as follows: Cf=(Cx*Cy)/(Cx+Cy)
Wherein, Cx=(ε _ 0* ε _ f*S)/df, Cy=(ε _ 0* ε _ x*S)/dx, Cx are finger to the electricity between protective layer
Hold, Cy is protective layer to the capacitor between metal electrode, and S is electrode area, and dx is the thickness of protective layer, and df is finger surface
To the distance of protective layer, ε _ 0 is permittivity of vacuum, and ε _ x is the dielectric constant of protective layer, and ε _ f is finger and protective layer
Between dielectric constant.
The inventor of the technical program has found in the course of the research, protective layer to the parasitic capacitance Cy between metal electrode
Cf is set to manifest offset, i.e. valley and a ridge a part for only accounting for resultant signal amount, in the case where especially wet finger, Cx is very big, and Cf is main
It is dominated by Cy, the resolution ratio of the signal of the valley and a ridge of collected user's finger is lower.
There are in uneven thickness to ask when further, since the protective layer and glue in existing semiconductor fingerprint acquisition device being manufactured
Topic, and when protective layer out-of-flatness, Cy is also different everywhere for acquisition array, so will form migration noise, therefore is also required to
Offset migration noise.
Summary of the invention
The embodiment of the present invention provides a kind of finger prints processing device, to improve acquisition user fingerprints when user's finger paddy and
The migration noise generated in the resolution ratio and offseting signal treatment process of the signal of ridge.
In a first aspect, the embodiment of the invention discloses a kind of finger prints processing devices, comprising:
Protective layer, glue, fingerprint collecting chip, collector, bucking circuit 1, programmable gain amplifier PGA1, bucking circuit
2, PGA2, analog-digital converter ADC, control chip, in which:
The protective layer passes through the glue and the fingerprint collecting die bonding；
The fingerprint collecting chip includes N*M induction electrode, and the N*M induction electrode forms the induction of N row M column
Electrod-array；
Induction electrode in the induction electrode array connects the collector by selection switch, the selection switch by
Row selects enable signal and column selection enable signal to control, and the collector connects the bucking circuit 1, and the bucking circuit 1 connects
The PGA1, the PGA1 connection bucking circuit 2, the bucking circuit 2 connect the PGA2, described in the PGA2 connection
The output end of ADC, the ADC connect the control chip；
The first control signal output end of the control chip connects the bucking circuit 1, described to control the second of chip
Control signal output connects the PGA1, and the third control signal output of the control chip connects the bucking circuit 2,
The first control signal output end of the control chip connects the PGA2；
The fingerprint image signal output end of the control chip is for connecting fingerprint image buffer memory device.
In the embodiment of the present invention, the collector is for amplifying and converting finger capacitor Cf (user's finger and induction electrode
Between parasitic capacitance) capacitance signal be voltage signal, to reduce the influence of noise of subsequent conditioning circuit, improve signal-to-noise ratio；
The bucking circuit 1 is used for most migration noises of offset input signal, specifically takes switched-capacitor methods,
The primary rough method offset, and use Approach by inchmeal is carried out to shifted signal, connects the average value of the output signal of the ADC
It is bordering on zero, i.e., collected fingerprint signal central value is close to zero, to offset most migration noises；
Amplified signal is input to by the PGA1 for amplifying to the output signal of the bucking circuit 1
In bucking circuit 2, the PGA1 should use larger gain (gain greater than PGA2), to reduce the design requirement of subsequent conditioning circuit；
The bucking circuit 2 carries out secondary fine counteracting for taking switched-capacitor methods, to migration noise, using with support
Same successive approximation approach in electric eliminating road 1, makes output signal central value be approximately equal to zero, thus further remaining in bucking circuit
Migration noise；
The PGA2 is for properly adjusting signal amplitude, to meet ADC input range requirement；
The ADC for output digit signals to control chip, in order to control chip based on received digital signal into
Row feedback control.
As it can be seen that finger prints processing device provided in an embodiment of the present invention passes through bucking circuit 1 for the migration noise in circuit
Carry out it is primary rough offset, secondary fine counteracting is carried out by bucking circuit 2, and cooperate collector, PGA1, PGA2 to fingerprint at
The circuit signal managed in device carries out reasonable range-adjusting, matches so that the signal processing circuit of finger prints processing device is in optimal
Set state, be conducive to improve acquisition user fingerprints when user's finger valley and a ridge signal resolution ratio and offseting signal at
The migration noise generated during reason.
With reference to first aspect, in some possible implementations, the collector includes switching circuit, the switch electricity
Road elder generation's set when acquiring user fingerprints, and when detecting that step occurs for the driving signal Vdr applied to user's finger, output
Variable signal, the converted quantity of the variable signal are as follows:
Δ V=k*Vdr*Cf/ (Cf+Cp)
Wherein, k is the gain factor of the switching circuit, and Vdr is the driving signal applied to user's finger, and Cf is user
Parasitic capacitance between finger and induction electrode, the Cp are the parasitic capacitance of induction electrode, and the driving signal includes sine
Wave or square wave.
With reference to first aspect, in some possible implementations, the bucking circuit 1 includes offsetting capacitor gating to open
It closes, offset capacitor array, feedback score capacitor Ci, signal acquisition capacitor Cs, single-ended amplifier, in which:
The first end of the signal acquisition capacitor Cs connects the output end of the collector, corresponding first input signal Vin；
The N number of input terminal for offsetting capacitor gating switch is used to access and the opposite in phase of the input signal Vin
Second input signal Vcan1, the N number of output end for offsetting capacitor gating switch is correspondingly connected with N number of in counteracting capacitor array
The first end of capacitor is offset, N number of second end, second end of the Cs for offsetting capacitor connects first end and the institute of the Ci
State the negative input end of single-ended amplifier, the positive input terminal ground connection of the single-ended amplifier；
The second end of the Ci connects the PGA1 with the output end of the single-ended amplifier.
With reference to first aspect, in some possible implementations, the PGA1 includes sampled, switched capacitor amplifying circuit
Or continuous time amplifying circuit；
When the PGA1 is continuous time amplifying circuit, the PGA1 includes input resistance Ri, feedback resistance Rf, the second list
Hold amplifier, in which:
The first end of the Ri connects the output end of the bucking circuit 1, and the second end of the Ri connects the defeated of the Rf
Enter the negative input end of end and second single-ended amplifier, the control signal input of the Rf controls signal for insertion gain
Gain1 [m], the gain control signal Gain1 [m] are used to adjust the amplifying circuit gain of the PGA1；
The positive input terminal of second single-ended amplifier is grounded；
The output end of second single-ended amplifier connects bucking circuit 2 with the output end of the Rf.
With reference to first aspect, in some possible implementations, the circuit structure of the bucking circuit 2 and the counteracting
The circuit structure of circuit 1 is identical.
With reference to first aspect, in some possible implementations, the amplifying circuit gain of the PGA1 is greater than described
The amplifying circuit gain of PGA2.
With reference to first aspect, in some possible implementations, the ADC is difference ADC, and the difference ADC's is defeated
Entering range is-Vmax to+Vmax, and the output area of the difference ADC is 0~2Nadc- 1, the bit wide Nadc of the difference ADC is big
In or be equal to M, the maximum input voltage of difference ADC described in Vmax.
With reference to first aspect, in some possible implementations, the protective layer include at least it is following any one: it is blue
Jewel cover board, glass cover-plate and ceramics.
With reference to first aspect, in some possible implementations, the surface area of the fingerprint collecting chip is greater than or waits
The center spacing between induction electrode in 1600um2, the fingerprint collecting chip is 50um, the fingerprint collecting chip
Resolution ratio is 508DPI.
With reference to first aspect, in some possible implementations, the fingerprint image buffer memory device include memory and/
Or graphics processor GPU.
Second aspect, the embodiment of the invention provides at a kind of fingerprint of finger prints processing device provided based on first aspect
Reason method, comprising:
Configure target scan areas；
Load the default gain of the PGA1 and the PGA2；
The target scan areas scanning is controlled, and based on default Approach by inchmeal strategy, determine and configures the counteracting electricity
The first of road 1 offsets configuration signal Scan1 [n1]；
The target scan areas scanning is controlled, based on the ADC output area determination and configures the first of the PGA1
Target gain；
The target scan areas scanning is controlled, the default Approach by inchmeal strategy is based on, determines and configure the counteracting
The second of circuit 2 offsets configuration signal Scan2 [n2]；
The target scan areas scanning is controlled, based on the ADC output area determination and configures the second of the PGA2
Target gain；
The target scan areas scanning user fingerprints are controlled, user fingerprint image is obtained；
The user fingerprint image is sent to the fingerprint image buffer memory device.
In conjunction with second aspect, in some possible implementations, the bucking circuit 1 includes: to offset capacitor gating to open
It closes, offset capacitor array, feedback score capacitor Ci, signal acquisition capacitor Cs, single-ended amplifier, in which:
The first end of the signal acquisition capacitor Cs connects the output end of the collector, corresponding first input signal Vin；
The N number of input terminal for offsetting capacitor gating switch is used to access the second input with the opposite in phase of the input signal Vin
Signal Vcan1, the N number of output end for offsetting capacitor gating switch are correspondingly connected with the N number of counteracting capacitor offset in capacitor array
First end, N number of second end, second end of the Cs for offsetting capacitor connect the first end of the Ci and described single-ended put
The negative input end of big device, the positive input terminal ground connection of the single-ended amplifier；The second end of the Ci and the single-ended amplifier
Output end connects the PGA1；
Wherein, N number of counteracting capacitor is illustrated as offsetting capacitor Cc (n) (n=1~N), and the capacitance of Cc (k) is Cc
(k-1) 2 times of capacitance, k=2~N+1, N are the line number of the induction electrode array；
The gating signal for offsetting capacitor gating switch is illustrated as Scan [n], and the Scan [n] effectively when corresponding choosing
It is logical to offset capacitor Cc (n)；
When the gating signal is Scan [n], caused by the first output caused by the Vin and the Vcan1 step
The outbound course of second output is on the contrary, offset, the output voltage after counteracting are as follows:
Wherein, Vout is the output voltage after offsetting.
In conjunction with second aspect, in some possible implementations, the control target scan areas scanning, and base
In default Approach by inchmeal strategy, the first counteracting configuration signal Scan1 [n1] of the bucking circuit 1 is determined and configured, comprising:
If currently the output average value of the enabled corresponding ADC of gating signal Scan [j] is greater than the output of the ADC
The upper limit 2Nadc- 1, it is determined that currently enabled gating signal is next choosing of the currently enabled gating signal Scan [j]
Messenger, and the target scan areas scanning is controlled, obtain the output average value of the ADC；
If currently the output average value of the enabled corresponding ADC of gating signal Scan [j] is less than or equal to the ADC
The output upper limit 2Nadc- 1, it is determined that it is Scan [j] that the first of the bucking circuit 1, which offsets configuration signal Scan1 [n1],.
In conjunction with second aspect, in some possible implementations, the PGA1 includes input resistance Ri, feedback resistance
Rf, the second single-ended amplifier, in which:
The first end of the Ri connects the output end of the bucking circuit 1, and the second end of the Ri connects the defeated of the Rf
Enter the negative input end of end and second single-ended amplifier, the control signal input of the Rf controls signal for insertion gain
Gain1 [m], the gain control signal Gain1 [m] are used to adjust the resistance value of the Rf；Second single-ended amplifier
Positive input terminal ground connection；The output end of second single-ended amplifier connects bucking circuit 2 with the output end of the Rf；
The amplifying circuit gain of the PGA1 are as follows:
Wherein, gain is the amplifying circuit gain of the PGA1.
In conjunction with second aspect, in some possible implementations, the configuration target scan areas, comprising:
When the circuit that receiving host issues initializes notice, target scan areas is configured；
Alternatively,
When detecting touch control operation of the user's finger to the protective layer, target scan areas is configured.
In conjunction with second aspect, in some possible implementations, if the target scan areas is the induction electrode
Array, then user fingerprints are scanned in the control target scan areas, obtain user fingerprint image, comprising:
The induction electrode array scanning user fingerprints are controlled, user fingerprint image is acquired.
In conjunction with second aspect, in some possible implementations, if the target scan areas includes P subregion induction
Electrod-array, P are the integer greater than 1, then user fingerprints are scanned in the control target scan areas, obtain user fingerprints figure
Picture, comprising:
Based on the corresponding P group Acquisition Circuit configuration parameter of the P subregion induction electrode array, the P subregion is controlled
Induction electrode array scanning user fingerprints acquire P user fingerprints sectional image；
Splicing is executed for the P user fingerprints sectional image, to obtain user fingerprint image.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
It obtains other drawings based on these drawings.
Fig. 1 is a kind of example of common semiconductor fingerprint acquisition device acquisition user fingerprints provided in an embodiment of the present invention
Figure；
Fig. 2 is that a kind of fingerprint based on semiconductor fingerprint shown in FIG. 1 acquisition sensor provided in an embodiment of the present invention is adopted
Collect schematic illustration；
Fig. 3 is a kind of structural schematic diagram of finger prints processing device provided in an embodiment of the present invention；
Fig. 4 is the reset signal of the collector in a kind of finger prints processing device provided in an embodiment of the present invention and is applied to use
The scene figure and timing diagram of driving signal on the finger of family；
Fig. 5 is a kind of structural schematic diagram of the bucking circuit 1 of finger prints processing device provided in an embodiment of the present invention；
Fig. 6 is the structural schematic diagram of the PGA11 of finger prints processing device provided in an embodiment of the present invention a kind of；
Fig. 7 is a kind of flow diagram of finger prints processing method provided in an embodiment of the present invention.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a kind of finger prints processing devices, comprising: protective layer, glue, fingerprint collecting chip, acquisition
Device, bucking circuit 1, PGA1, bucking circuit 2, PGA2, ADC, control chip；Collector is for amplifying and converting finger capacitor Cf
Capacitance signal to reduce the influence of noise of subsequent conditioning circuit；Bucking circuit 1 is used to carry out secondary fine counteracting to migration noise；
Amplified signal is input in bucking circuit 2, PGA1 by PGA1 for amplifying to the output signal of bucking circuit 1
Larger gain is used to reduce the design requirement of subsequent conditioning circuit；Bucking circuit 2 is used to carry out secondary fine counteracting to migration noise；
PGA2 is for properly adjusting signal amplitude；ADC is for output digit signals to control chip；Control chip is for being based on
Digital signal carries out feedback control.The letter of the valley and a ridge of user's finger when the embodiment of the present invention is conducive to improve acquisition user fingerprints
Number resolution ratio and offseting signal treatment process in the migration noise that generates.
It is further explained below.
Referring to Fig. 3, Fig. 3 is a kind of structural schematic diagram of finger prints processing device provided in an embodiment of the present invention.As schemed
Show, this finger prints processing device includes:
Protective layer, glue, fingerprint collecting chip, collector, bucking circuit 1, programmable gain amplifier PGA1, bucking circuit
2, PGA2, analog-digital converter ADC, control chip, in which:
The protective layer passes through the glue and the fingerprint collecting die bonding；
The fingerprint collecting chip includes N*M induction electrode, and the N*M induction electrode forms the induction of N row M column
Electrod-array；
Induction electrode in the induction electrode array connects the collector by selection switch, the selection switch by
Row selects enable signal and column selection enable signal to control, and the collector connects the bucking circuit 1, and the bucking circuit 1 connects
The PGA1, the PGA1 connection bucking circuit 2, the bucking circuit 2 connect the PGA2, described in the PGA2 connection
The output end of ADC, the ADC connect the control chip；
The first control signal output end of the control chip connects the bucking circuit 1, described to control the second of chip
Control signal output connects the PGA1, and the third control signal output of the control chip connects the bucking circuit 2,
The first control signal output end of the control chip connects the PGA2；
The fingerprint image signal output end of the control chip is for connecting fingerprint image buffer memory device.
In the embodiment of the present invention, the collector is for amplifying and converting finger capacitor Cf (user's finger and induction electrode
Between parasitic capacitance) capacitance signal be voltage signal, to reduce the influence of noise of subsequent conditioning circuit, improve signal-to-noise ratio；
The bucking circuit 1 is used for most migration noises of offset input signal, specifically takes switched-capacitor methods,
The primary rough method offset, and use Approach by inchmeal is carried out to shifted signal, connects the average value of the output signal of the ADC
It is bordering on zero, i.e., collected fingerprint signal central value is close to zero, to offset most migration noises；
Amplified signal is input to by the PGA1 for amplifying to the output signal of the bucking circuit 1
In bucking circuit 2, the PGA1 should use larger gain (gain greater than PGA2), to reduce the design requirement of subsequent conditioning circuit；
The bucking circuit 2 carries out secondary fine counteracting for taking switched-capacitor methods, to migration noise, using with support
Same successive approximation approach in electric eliminating road 1, makes output signal central value be approximately equal to zero, thus further remaining in bucking circuit
Migration noise；
The PGA2 is for properly adjusting signal amplitude, to meet ADC input range requirement；
The ADC for output digit signals to control chip, in order to control chip based on received digital signal into
Row feedback control.
As it can be seen that finger prints processing device provided in an embodiment of the present invention passes through bucking circuit 1 for the migration noise in circuit
Carry out it is primary rough offset, secondary fine counteracting is carried out by bucking circuit 2, and cooperate collector, PGA1, PGA2 to fingerprint at
The circuit signal managed in device carries out reasonable range-adjusting, matches so that the signal processing circuit of finger prints processing device is in optimal
Set state, be conducive to improve acquisition user fingerprints when user's finger valley and a ridge signal resolution ratio and offseting signal at
The migration noise generated during reason.
Further, referring to Fig. 4, Fig. 4 is the collector in a kind of finger prints processing device provided in an embodiment of the present invention
Reset signal and the scene figure and timing diagram of the driving signal that are applied in user's finger；As shown, the collector packet
It includes:
Switching circuit, switching circuit elder generation's set when acquiring user fingerprints, and apply detecting to user's finger
Driving signal Vdr occur step when, export variable signal, the converted quantity of the variable signal are as follows:
Δ V=k*Vdr*Cf/ (Cf+Cp)
Wherein, k is the gain factor of the switching circuit, and Vdr is the driving signal applied to user's finger, and Cf is user
Parasitic capacitance between finger and induction electrode, the Cp are the parasitic capacitance of induction electrode, and the driving signal includes sine
Wave or square wave.
Further, referring to Fig. 5, Fig. 5 is a kind of bucking circuit 1 of finger prints processing device provided in an embodiment of the present invention
Structural schematic diagram, as shown, this bucking circuit 1 includes:
It offsets capacitor gating switch, offset capacitor array, feedback score capacitor Ci, signal acquisition capacitor Cs, single-ended amplification
Device, in which:
The first end of the signal acquisition capacitor Cs connects the output end of the collector, corresponding first input signal Vin；
The N number of input terminal for offsetting capacitor gating switch is used to access and the opposite in phase of the input signal Vin
Second input signal Vcan1, the N number of output end for offsetting capacitor gating switch is correspondingly connected with N number of in counteracting capacitor array
The first end of capacitor is offset, N number of second end, second end of the Cs for offsetting capacitor connects first end and the institute of the Ci
State the negative input end of single-ended amplifier, the positive input terminal ground connection of the single-ended amplifier；
The second end of the Ci connects the PGA1 with the output end of the single-ended amplifier.
Further, referring to Fig. 6, Fig. 6 is the knot of the PGA11 of finger prints processing device provided in an embodiment of the present invention a kind of
Structure schematic diagram, as shown, this PGA1 includes:
Sampled, switched capacitor amplifying circuit or continuous time amplifying circuit；
When the PGA1 is continuous time amplifying circuit, the PGA1 includes input resistance Ri, feedback resistance Rf, the second list
Hold amplifier, in which:
The first end of the Ri connects the output end of the bucking circuit 1, and the second end of the Ri connects the defeated of the Rf
Enter the negative input end of end and second single-ended amplifier, the control signal input of the Rf controls signal for insertion gain
Gain1 [m], the gain control signal Gain1 [m] are used to adjust the amplifying circuit gain of the PGA1；
The positive input terminal of second single-ended amplifier is grounded；
The output end of second single-ended amplifier connects bucking circuit 2 with the output end of the Rf.
Optionally, in the embodiment of the present invention, the circuit knot of the circuit structure of the bucking circuit 2 and the bucking circuit 1
Structure is identical.
Optionally, in the embodiment of the present invention, amplifying circuit of the amplifying circuit gain greater than the PGA2 of the PGA1 increases
Benefit, to reduce the design requirement of subsequent conditioning circuit.
Optionally, in the embodiment of the present invention, the ADC is difference ADC, the input range of the difference ADC be-Vmax extremely
The output area of+Vmax, the difference ADC are 0~2NadcThe bit wide Nadc of -1, the difference ADC are greater than or equal to M, Vmax
The maximum input voltage of the difference ADC.
Optionally, in the embodiment of the present invention, the protective layer include at least it is following any one: sapphire cover board, glass
Cover board and ceramics.Wherein, the protective layer must have certain hardness and electrology characteristic, unlike material, different acquisition side
It is different that thickness degree is claimed in case.
Optionally, in the embodiment of the present invention, the surface area of the fingerprint collecting chip is greater than or equal to 1600um2, described
Center spacing between induction electrode in fingerprint collecting chip is 50um, and the resolution ratio of the fingerprint collecting chip is
508DPI。
Optionally, in the embodiment of the present invention, the fingerprint image buffer memory device includes memory and/or graphics processor
GPU。
Finger prints processing device in conjunction with disclosed in above-described embodiment is detailed below based on above-mentioned finger prints processing device
Finger prints processing method.
Referring to Fig. 7, Fig. 7 is a kind of flow diagram of finger prints processing method provided in an embodiment of the present invention；Such as Fig. 7 institute
Show, this finger prints processing method specifically includes the following steps:
S701 configures target scan areas；
S702 loads the default gain of the PGA1 and the PGA2；
Wherein, the default gain is curable, can also be reconfigured.
S703 controls the target scan areas scanning, and based on default Approach by inchmeal strategy, determines and configure described support
The first of electric eliminating road 1 offsets configuration signal Scan1 [n1]；
S704 controls the target scan areas scanning, based on the ADC output area determination and configures the PGA1's
First object gain；
S705 controls the target scan areas scanning, is based on the default Approach by inchmeal strategy, determines and configures described
The second of bucking circuit 2 offsets configuration signal Scan2 [n2]；
S706 controls the target scan areas scanning, based on the ADC output area determination and configures the PGA2's
Second target gain；
S707 controls the target scan areas scanning user fingerprints, obtains user fingerprint image；
S708, Xiang Suoshu fingerprint image buffer memory device send the user fingerprint image.
Wherein, the output signal of the ADC should cover ADC gamut as far as possible.
In the specific implementation, since above-mentioned bucking circuit 1 includes: to offset capacitor gating switch, counteracting capacitor array, feedback product
Divide capacitor Ci, signal acquisition capacitor Cs, single-ended amplifier, in which: adopt described in the first end connection of the signal acquisition capacitor Cs
The output end of storage, corresponding first input signal Vin；The N number of input terminal for offsetting capacitor gating switch is for access and institute
State the second input signal Vcan1 of the opposite in phase of input signal Vin, the N number of output end pair for offsetting capacitor gating switch
Should connect the first end for offsetting N number of counteracting capacitor in capacitor array, it is described it is N number of offset the second end of capacitor, the Cs the
Two ends connect the first end of the Ci and the negative input end of the single-ended amplifier, the positive input termination of the single-ended amplifier
Ground；The second end of the Ci connects the PGA1 with the output end of the single-ended amplifier；
Wherein, N number of counteracting capacitor is illustrated as offsetting capacitor Cc (n) (n=1~N), and the capacitance of Cc (k) is Cc
(k-1) 2 times of capacitance, k=2~N+1, N are the line number of the induction electrode array；
The gating signal for offsetting capacitor gating switch is illustrated as Scan [n], and the Scan [n] effectively when corresponding choosing
It is logical to offset capacitor Cc (n)；
So the first output and the Vcan1 step caused by the Vin are led when the gating signal is Scan [n]
The outbound course of the second output caused is on the contrary, offset, the output voltage after counteracting are as follows:
Wherein, Vout is the output voltage after offsetting.
In conjunction with the output voltage after the above-mentioned counteracting derived calculation formula it is found that the control targeted scans area
Domain scanning, and based on default Approach by inchmeal strategy, it determines and configures the first of the bucking circuit 1 and offset configuration signal Scan1
[n1] specifically includes the following steps:
If currently the output average value of the enabled corresponding ADC of gating signal Scan [j] is greater than the output of the ADC
The upper limit 2Nadc- 1, it is determined that currently enabled gating signal is next choosing of the currently enabled gating signal Scan [j]
Messenger, and the target scan areas scanning is controlled, obtain the output average value of the ADC；
If currently the output average value of the enabled corresponding ADC of gating signal Scan [j] is less than or equal to the ADC
The output upper limit 2Nadc- 1, it is determined that it is Scan [j] that the first of the bucking circuit 1, which offsets configuration signal Scan1 [n1],.
As an example it is assumed that N is 8, the capacitor array of offsetting in corresponding bucking circuit 1 is 8 counteracting capacitors in parallel,
And the gating signal Scan [8] that offsets capacitor gating switch it is effective when, it is maximum to offset the corresponding gating capacitance of capacitor gating switch
Counteracting capacitor Cc (8), and so on it is found that offset capacitor gating switch gating signal Scan [n] it is effective when, offset capacitor
The corresponding gating maximum counteracting capacitor Cc (n) of capacitance of gating switch, if first offsets the n1's in configuration signal Scan1 [n1]
Value is 7, then corresponding finger prints processing device controls the target scan areas scanning, and based on default Approach by inchmeal strategy, really
Determine and configure the first of the bucking circuit 1 detailed process for offsetting configuration signal Scan1 [n1] are as follows:
The gating signal Scan [8] for offsetting capacitor gating switch enabled first, the i.e. corresponding gating of counteracting capacitor gating switch
The maximum counteracting capacitor Cc (8) of capacitance controls chip controls induction electrode array scanning, and acquire it is right during present scan
The output average value for the ADC that should be received；
The output average value for comparing the corresponding ADC of present scan process is greater than the output area upper limit of the ADC
2Nadc- 1, then forbidden energy offsets the gating signal Scan [8] of capacitor gating switch；
Secondly, the enabled gating signal Scan [7] for offsetting capacitor gating switch, the i.e. corresponding gating of counteracting capacitor gating switch
Time big counteracting capacitor Cc (7) of capacitance, controls chip controls induction electrode array scanning, and acquire it is right during present scan
The output average value for the ADC that should be received；
The output average value for comparing the corresponding ADC of present scan process is less than or equal to the output model of the ADC
Place limit 2Nadc- 1, then it controls chip and determines that the value of n1 is 7, and exit current Approach by inchmeal process.
In the specific implementation, since above-mentioned PGA1 includes input resistance Ri, feedback resistance Rf, the second single-ended amplifier, in which:
The first end of the Ri connects the output end of the bucking circuit 1, and the second end of the Ri connects input terminal and the institute of the Rf
The negative input end of the second single-ended amplifier is stated, the control signal input of the Rf controls signal Gain1 for insertion gain
[m], the gain control signal Gain1 [m] are used to adjust the resistance value of the Rf；The positive input of second single-ended amplifier
End ground connection；The output end of second single-ended amplifier connects bucking circuit 2 with the output end of the Rf；
So the amplifying circuit gain of the PGA1 can be derived are as follows:
Wherein, gain is the amplifying circuit gain of the PGA1.
In the specific implementation, the configuration target scan areas, comprising:
When the circuit that receiving host issues initializes notice, target scan areas is configured；
Alternatively,
When detecting touch control operation of the user's finger to the protective layer, target scan areas is configured.
In the specific implementation, the control target is swept if the target scan areas is the induction electrode array
Sector scanning user fingerprints are retouched, user fingerprint image is obtained, comprising:
The induction electrode array scanning user fingerprints are controlled, user fingerprint image is acquired.
In the specific implementation, P is the integer greater than 1 if the target scan areas includes P subregion induction electrode array,
Then user fingerprints are scanned in the control target scan areas, obtain user fingerprint image, comprising:
Based on the corresponding P group Acquisition Circuit configuration parameter of the P subregion induction electrode array, the P subregion is controlled
Induction electrode array scanning user fingerprints acquire P user fingerprints sectional image；
Splicing is executed for the P user fingerprints sectional image, to obtain user fingerprint image.
It is understood that causing to acquire due to the possible out-of-flatness of protective layer in above-mentioned finger prints processing device
Migration noise is generated in journey, for such situation, can carry out multidomain treat-ment for induction electrode array, i.e., by induction electrode battle array
Column are divided into P subregion induction electrode array, in each subregion induction electrode array, it can be assumed that corresponding protective layer
It is smooth, and the adjustment process for executing above-mentioned Acquisition Circuit configuration parameter for each subregion induction electrode array (is supported
The gain adjustment process for approaching adjustment process and PGA1 and PGA2 for the first time on electric eliminating road 1 and bucking circuit 2), to obtain every
The corresponding Acquisition Circuit configuration parameter of one subregion induction electrode array, in this way, can be further improved finger prints processing device
Resolution ratio reduces migration noise to the image of acquisition precision.
Finger prints processing device is provided for the embodiments of the invention above to be described in detail, it is used herein specifically
Principle and implementation of the present invention are described for a example, the present invention that the above embodiments are only used to help understand
Method and its core concept；At the same time, for those skilled in the art is being embodied according to the thought of the present invention
There will be changes in mode and application range, in conclusion the contents of this specification are not to be construed as limiting the invention.
Claims (10)
1. a kind of finger prints processing device characterized by comprising
Protective layer, glue, fingerprint collecting chip, collector, bucking circuit 1, programmable gain amplifier PGA1, bucking circuit 2,
PGA2, analog-digital converter ADC, control chip, in which:
The protective layer passes through the glue and the fingerprint collecting die bonding；
The fingerprint collecting chip includes N*M induction electrode, and the N*M induction electrode forms the induction electrode of N row M column
Array；
Induction electrode in the induction electrode array connects the collector by selection switch, and the selection switch is selected by row
Enable signal and the control of column selection enable signal, the collector connect the bucking circuit 1, and the bucking circuit 1 connects described
PGA1, the PGA1 connection bucking circuit 2, the bucking circuit 2 connect the PGA2, the PGA2 connection ADC,
The output end of the ADC connects the control chip；
The first control signal output end of the control chip connects the bucking circuit 1, the second control of the control chip
Signal output end connects the PGA1, and the third control signal output of the control chip connects the bucking circuit 2, described
The first control signal output end for controlling chip connects the PGA2；
The fingerprint image signal output end of the control chip is for connecting fingerprint image buffer memory device.
2. finger prints processing device according to claim 1, which is characterized in that the collector includes switching circuit, described
Switching circuit elder generation's set when acquiring user fingerprints, and detecting the driving signal Vdr generation step applied to user's finger
When, export variable signal, the converted quantity of the variable signal are as follows:
Δ V=k*Vdr*Cf/ (Cf+Cp)
Wherein, k is the gain factor of the switching circuit, and Vdr is the driving signal applied to user's finger, and Cf is user's finger
Parasitic capacitance between induction electrode, the Cp be induction electrode parasitic capacitance, the driving signal include sine wave or
Person's square wave.
3. according to claim 1 or 2 described in any item finger prints processing devices, which is characterized in that the bucking circuit 1 includes supporting
Electric eliminating holds gating switch, offsets capacitor array, feedback score capacitor Ci, signal acquisition capacitor Cs, single-ended amplifier, in which:
The first end of the signal acquisition capacitor Cs connects the output end of the collector, corresponding first input signal Vin；
The N number of input terminal for offsetting capacitor gating switch is used to access second with the opposite in phase of the input signal Vin
Input signal Vcan1, the N number of output end for offsetting capacitor gating switch are correspondingly connected with the N number of counteracting offset in capacitor array
The first end of capacitor, it is described it is N number of offset capacitor second end, the second end of the Cs connect the Ci first end and the list
Hold the negative input end of amplifier, the positive input terminal ground connection of the single-ended amplifier；
The second end of the Ci connects the PGA1 with the output end of the single-ended amplifier.
4. finger prints processing device according to claim 3, which is characterized in that the PGA1 includes sampled, switched capacitor amplification
Circuit or continuous time amplifying circuit；
When the PGA1 is continuous time amplifying circuit, the PGA1 includes input resistance Ri, feedback resistance Rf, second single-ended puts
Big device, in which:
The first end of the Ri connects the output end of the bucking circuit 1, and the second end of the Ri connects the input terminal of the Rf
Signal is controlled for insertion gain with the control signal input of the negative input end of second single-ended amplifier, the Rf
Gain1 [m], the gain control signal Gain1 [m] are used to adjust the amplifying circuit gain of the PGA1；
The positive input terminal of second single-ended amplifier is grounded；
The output end of second single-ended amplifier connects bucking circuit 2 with the output end of the Rf.
5. finger prints processing device according to claim 4, which is characterized in that the circuit structure of the bucking circuit 2 and institute
The circuit structure for stating bucking circuit 1 is identical.
6. finger prints processing device according to claim 5, which is characterized in that the amplifying circuit gain of the PGA1 is greater than institute
State the amplifying circuit gain of PGA2.
7. finger prints processing device according to claim 6, which is characterized in that the ADC is difference ADC, the difference ADC
Input range be-Vmax to+Vmax, the output area of the difference ADC is 0~2Nadc- 1, the bit wide of the difference ADC
Nadc is greater than or equal to M, the maximum input voltage of difference ADC described in Vmax.
8. finger prints processing device according to claim 7, which is characterized in that the protective layer includes at least following any one
Kind: sapphire cover board, glass cover-plate and ceramics.
9. finger prints processing device according to claim 8, which is characterized in that the surface area of the fingerprint collecting chip is greater than
Or it is equal to 1600um2 , the center spacing between induction electrode in the fingerprint collecting chip is 50um, the fingerprint collecting core
The resolution ratio of piece is 508DPI.
10. finger prints processing device according to claim 9, which is characterized in that the fingerprint image buffer memory device includes depositing
Reservoir and/or graphics processor GPU.
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| CN2016101778885 | 2016-03-25 | ||
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| CN106203409A (en) * | 2016-09-08 | 2016-12-07 | 成都感芯科技有限公司 | A kind of fingerprint collecting framework |
| US10311279B2 (en) * | 2016-10-21 | 2019-06-04 | Novatek Microelectronics Corp. | Fingerprint sensor device and operation method thereof |
| US11497411B2 (en) * | 2018-11-23 | 2022-11-15 | Mediatek Inc. | Circuit applied to bio-information acquisition system |
| CN112560640A (en) * | 2020-12-08 | 2021-03-26 | 京东方科技集团股份有限公司 | Fingerprint acquisition circuit, driving method, fingerprint sensor and fingerprint acquisition equipment |
| CN113033302B (en) * | 2021-02-09 | 2023-12-26 | 敦泰电子（深圳）有限公司 | Fingerprint acquisition circuit, chip and electronic equipment |
| CN114018298B (en) * | 2021-10-22 | 2022-07-22 | 西安电子科技大学 | Capacitance-voltage conversion circuit for MEMS capacitive sensor |
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Address after: 518000 East of Building A, 22, Shenzhen International Innovation Center, 1006 Shennan Avenue, Huafu Street, Futian District, Shenzhen City, Guangdong Province Patentee after: Shenzhen Biocome Security Technology Co.,Ltd. Address before: 518000 East of Building A, 22, Shenzhen International Innovation Center, 1006 Shennan Avenue, Huafu Street, Futian District, Shenzhen City, Guangdong Province Patentee before: SHENZHEN BIOCOME SECURITY TECHNOLOGY CO.,LTD. |