CN210142336U - Capacitive fingerprint identification sensor and electronic equipment - Google Patents
Capacitive fingerprint identification sensor and electronic equipment Download PDFInfo
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- CN210142336U CN210142336U CN201921321240.6U CN201921321240U CN210142336U CN 210142336 U CN210142336 U CN 210142336U CN 201921321240 U CN201921321240 U CN 201921321240U CN 210142336 U CN210142336 U CN 210142336U
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Abstract
The application discloses capacitanc fingerprint identification sensor and electronic equipment includes: a substrate; be located the fingerprint induction unit that the substrate surface is array distribution, set up at a plurality of first drive wires and a plurality of second drive wire on substrate surface, second drive wire and first drive wire cross connection form fingerprint induction unit, and every fingerprint induction unit includes: each first driving wire can conduct or cut off the sensing polar plate through the switching device, the sensing polar plate and the fingerprint form a fingerprint capacitor, and each second driving wire is connected with the switching device; the driving unit is connected with at least one second driving wire through a first switch; a signal processing unit comprising: and an integration circuit connected to the at least one second drive line via a second switch, the first switch having an on/off state opposite to that of the second switch. The fingerprint identification sensor provided by the application can realize large-area identification and can improve the sensitivity of fingerprint identification.
Description
Technical Field
The application relates to the technical field of fingerprint identification, in particular to a capacitive fingerprint identification sensor and electronic equipment.
Background
Because of the lifetime invariance, uniqueness and convenience of fingerprints, a higher level of identity security authentication can be provided. Current fingerprint identification sensors typically include: an optical fingerprint identification sensor and a capacitive fingerprint identification sensor. The principle of utilizing the capacitive fingerprint identification sensor for identification is as follows: when the finger is attached to the sensing area, the finger attaching surface and the sensing surface form a fingerprint capacitor. Due to the fact that the surface layer of the finger is uneven, the convex part is called as a ridge, the concave part is called as a valley, actual distances between the ridge and the valley and the sensing surface are different, and formed capacitance values are different, so that fingerprint information can be converted into corresponding electric signals to be output. Finally, the collected signals are processed to obtain an image reflecting the fingerprint information, and the fingerprint identification process is completed by comparing the image with the previously stored fingerprint information.
In the prior art, the sensing area of the fingerprint identification sensor is usually used as a sensing surface, and the sensing area of the fingerprint identification sensor cannot be large in area due to the cost, so that the fingerprint identification area is small, the fingerprint information acquired by the sensor is less, and the identification difficulty is caused.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems, the application provides a capacitive fingerprint identification sensor and an electronic device, which can realize large-area identification and improve the sensitivity of fingerprint identification. The technical scheme is as follows:
a capacitive fingerprint recognition sensor comprising:
a substrate;
the fingerprint sensing units are positioned on the surface of the substrate and distributed in an array manner;
a plurality of first driving lines arranged at intervals of a first predetermined distance on the surface of the substrate;
a plurality of second driving lines arranged on the surface of the substrate at intervals of a second predetermined distance, the second driving lines being cross-connected with the first driving lines to form the fingerprint sensing units, each fingerprint sensing unit comprising: each first driving wire can conduct or cut off the sensing polar plate through the switch device, the sensing polar plate and the fingerprint form a fingerprint capacitor, and each second driving wire is connected with the switch device;
the driving unit is used for providing a conducting signal for the switching device and is connected with at least one second driving wire through a first switch;
a signal processing unit comprising: an integration circuit connected to at least one of the second drive lines through a second switch, the first switch having an on/off state opposite to that of the second switch.
As a preferred embodiment, the switching device has an output terminal, a connection terminal and a control terminal, the connection terminal and the output terminal are connected with the control terminal, the control terminal is connected with the second driving line, the output terminal is connected with the first driving line, the connection terminal is connected with the sensing polar plate,
when the first switch is closed, the second switch is switched off, the driving unit can provide a conducting signal for the control end through the second driving line, the first driving line and the second driving line in sequence, and the fingerprint capacitor stores charges; when the first switch is switched off, the second switch is switched on, and charges can be transmitted to the signal processing unit for processing through the first driving line, the switching device and the second driving line in sequence so as to generate an output signal.
As a preferred embodiment, the second switch has a first end and a second end opposite to each other, the first end of the second switch is connected to the second driving line, the second end of the second switch is connected to the integrating circuit, and the signal processing unit further includes a compensation circuit;
the compensation circuit includes: the compensation capacitor, the fourth switch and the fifth switch; a first end of the fourth switch is connected with a first power voltage, a second end of the fourth switch is connected with an upper pole plate of the compensation capacitor, a first end of the fifth switch is connected with a second power voltage, and a second end of the fifth switch is connected with the upper pole plate of the compensation capacitor;
an upper pole plate of the compensation capacitor is respectively connected with a second end of the fourth switch and a second end of the fifth switch, a lower pole plate of the compensation capacitor is connected with a negative input end of the integrating amplifier, and a lower pole plate of the compensation capacitor is connected with a second end of the second switch;
the fourth switch and the first switch are closed or opened simultaneously, and the fifth switch and the second switch are closed or opened simultaneously.
As a preferred embodiment, the integration circuit includes an integration amplifier, an integration capacitor, and a third switch;
the integrating amplifier comprises a negative input end, a positive input end and an output end, the negative input end of the integrating amplifier is connected with the compensation circuit, the negative input end of the integrating amplifier is connected with the second end of the second switch, and the positive input end of the integrating amplifier is connected with a reference voltage; the upper polar plate of the integrating capacitor is connected with the negative input end of the integrating amplifier, and the lower polar plate of the integrating capacitor is connected with the output end of the integrating amplifier;
the first end of the third switch is connected with the upper pole plate of the integrating capacitor, the second end of the third switch is connected with the lower pole plate of the integrating capacitor, the third switch and the first switch are closed or opened simultaneously, and when the third switch is closed, the integrating circuit is in a reset mode.
In a preferred embodiment, the first driving line and the second driving line are made of transparent metal or oxide conductors.
In a preferred embodiment, the material of the first driving line and the second driving line is indium tin oxide.
In a preferred embodiment, the first predetermined distance and the second predetermined distance are both 100 to 300 μm.
As a preferred embodiment, the angle between the first drive line and the second drive line is 90 °.
As a preferred embodiment, the drive unit is provided with a charge pump for boosting the voltage.
An electronic device comprises the capacitive fingerprint identification sensor.
Has the advantages that:
according to the capacitive fingerprint identification sensor and the electronic equipment, when the first switch is closed, the second switch is disconnected, the driving unit can provide a conducting signal for the switch device in the fingerprint sensing unit through the second driving line, and when a finger presses the identification area, the finger and the sensing electrode plate in the fingerprint sensing unit can form a fingerprint capacitor and store charges; when the first switch is opened, the second switch is closed, and the charges can be output by the switching device and the first driving line and transmitted to the integrating circuit in the signal processing unit by the second driving line for processing so as to generate an output signal.
In this application embodiment, because switching device itself has parasitic capacitance, when first switch was closed, parasitic capacitance and fingerprint electric capacity homoenergetic among the switching device injected electric charge, when the second switch was closed, the electric charge of storage all passes through switching device among fingerprint electric capacity and the parasitic capacitance, first drive wire passes through the second drive wire and transmits for integrator circuit to can reduce the influence that switching device parasitic capacitance brought, be favorable to promoting fingerprint identification's sensitivity. In addition, this application is through setting up the fingerprint sensing unit of array distribution, and fingerprint sensing unit array constitutes this capacitanc fingerprint identification sensor's sensing area, can enlarge fingerprint identification area, when the finger is pressed at sensing area, can select corresponding fingerprint identification area through first drive wire and second drive wire to carry out fingerprint information's collection.
Specific embodiments of the present application are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the application may be employed. It should be understood that the embodiments of the present application are not so limited in scope.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.
It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without inventive labor.
Fig. 1 is a schematic structural diagram of a capacitive fingerprint identification sensor according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a fingerprint sensing unit according to an embodiment of the present disclosure;
FIG. 3 is a diagram of an array of fingerprint sensing units according to an embodiment of the present application;
fig. 4 is a circuit configuration diagram of a signal processing unit according to an embodiment of the present disclosure;
fig. 5 is a schematic view of an electronic device according to an embodiment of the present application.
Description of reference numerals:
1. a substrate; 2. a fingerprint sensing unit; 21. an induction pole plate; 22. a switching device; 23. fingerprint capacitance; 3. a first drive line; 4. a second drive line; 5. a drive unit; 6. a signal processing unit; 61. an integrating amplifier; 10. an electronic screen; 20. identifying an area; s1, a first switch; s2, a second switch; s3, a third switch; s4, a fourth switch; s5 and a fifth switch.
Detailed Description
The technical solution of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments, it should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope, and after reading the present invention, the modifications of the various equivalent forms of the present invention by those skilled in the art will fall within the scope defined by the present application.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.
The following is set forth in a scenario in which user fingerprint information is obtained as a main description. However, as can be seen from the above description, the scope of the embodiments of the present invention is not limited thereto. In this specification, the direction pointing or facing the user is defined as "up" and the opposite direction, or the direction facing away from the user is defined as "down" in the normal use state of the capacitive fingerprint sensor according to the embodiment of the present invention.
The capacitive fingerprint sensor according to the embodiment of the present invention will be explained and explained with reference to fig. 1 to 5. It should be noted that, for convenience of description, like reference numerals denote like parts in the embodiments of the present invention. And for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments, and the descriptions of the same components may be mutually referred to and cited.
Specifically, the upward direction illustrated in fig. 1 to 5 is defined as "up", and the downward direction illustrated in fig. 1 to 5 is defined as "down". It should be noted that the definitions of the directions in the present specification are only for convenience of describing the technical solution of the present invention, and do not limit the directions of the capacitive fingerprint sensor according to the embodiments of the present invention in other scenarios, including but not limited to use, test, transportation, and manufacture, which may cause the orientation of the device to be reversed or the position of the device to be changed.
As shown in fig. 1 to 3, the present application provides a capacitive fingerprint recognition sensor, including: a substrate 1; the fingerprint sensing units 2 are positioned on the surface of the substrate 1 and distributed in an array manner; a plurality of first driving lines 3 arranged at intervals of a first predetermined distance on a surface of the substrate 1; a plurality of second driving lines 4 arranged on the surface of the substrate 1 at intervals of a second predetermined distance, the second driving lines 4 being cross-connected with the first driving lines 3 to form the fingerprint sensing units 2, each fingerprint sensing unit 2 comprising: the fingerprint sensing device comprises a sensing polar plate 21 and a switching device 22 connected with the sensing polar plate, wherein each first driving wire 3 can conduct or cut off the sensing polar plate 21 through the switching device 22, the sensing polar plate 21 and a fingerprint form a fingerprint capacitor 23, and each second driving wire 4 is connected with the switching device 22; a driving unit 5 for providing a conducting signal to the switching device 22, the driving unit 5 being connected to at least one of the second driving lines 4 through a first switch S1; the signal processing unit 6, include: an integration circuit connected to at least one of the second drive lines 4 through a second switch S2, the closed/open state of the first switch S1 being opposite to the second switch S2.
According to the capacitive fingerprint identification sensor and the electronic device provided by the embodiment of the application, when the first switch S1 is closed, the second switch S2 is turned off, the driving unit 5 can provide a conducting signal for the switch device 22 in the fingerprint sensing unit 2 through the second driving line 4, and at this time, when a finger presses the identification area, the finger and the sensing electrode plate 21 in the fingerprint sensing unit 2 can form the fingerprint capacitor 23 and store charges; when the first switch S1 is opened, the second switch S2 is closed, and the charge can be output through the switching device 22 and the first driving line 3 and transferred to the signal processing unit 6 through the second driving line 4 for processing to generate an output signal.
In the embodiment of the present application, because the switching device 22 itself has a parasitic capacitance, when the first switch S1 is closed, the parasitic capacitance in the switching device 22 and the fingerprint capacitance 23 can both inject charges, and when the second switch S3 is closed, the charges stored in the fingerprint capacitance 23 and the parasitic capacitance are both transmitted to the signal processing unit 6 through the switching device 22 and the first driving line 3 via the second driving line 4, so that the influence caused by the parasitic capacitance of the switching device 22 can be reduced, which is beneficial to improving the sensitivity of fingerprint identification. In addition, this application is through setting up array distribution's fingerprint induction unit 2, and the fingerprint induction unit 2 array constitutes this capacitanc fingerprint identification sensor's sensing area, can enlarge fingerprint identification area, when the finger is pressed at sensing area, can select corresponding fingerprint identification area through first drive wire 3 and second drive wire 4 to carry out fingerprint information's collection.
Specifically, the substrate 1 is made of an insulating material to improve the isolation between the fingerprint sensing units 2 on the surface of the substrate 1. Preferably, the substrate 1 is a glass substrate. As shown in fig. 3, the fingerprint sensing units 2 are arranged in an array on the surface of the substrate 1. The fingerprint sensing unit 2 array constitutes the sensing plane of this capacitanc fingerprint identification sensor, is formed with the plane transmission electric field between this sensing plane and the finger fingerprint that can electrically conduct for gather fingerprint information. Each fingerprint sensing unit 2 comprises a sensing pole plate 21 and a switch device 22, the switch device 22 is connected with the sensing pole plate 21, and the sensing pole plate 21 and a fingerprint form a fingerprint capacitor 23. Specifically, when a finger presses on the sensing area, the capacitance of the sensing electrode plate 21 and the fingerprint capacitor 23 formed by the fingerprint in the planar transmission electric field is related to the distance between the sensing plane and the fingerprint, and the capacitive fingerprint identification sensor acquires corresponding fingerprint information according to the voltage signal related to the fingerprint capacitor 23. The switch device 22 is used for controlling the voltage signal output obtained by the sensing electrode plate 21 in the fingerprint sensing unit 2, and when the switch device 22 is turned on, the fingerprint sensing unit 2 outputs the voltage signal.
As shown in fig. 1 and 2, a surface of the substrate 1 is provided with a plurality of first driving lines 3 arranged at intervals of a first predetermined distance, and a plurality of second driving lines 4 arranged at intervals of a second predetermined distance. The first driving lines 3 and the second driving lines 4 are made of conductive materials, and the first driving lines 3 and the second driving lines 4 are arranged in a crossing manner and electrically connected with each other, so that the fingerprint sensing unit 2 is formed. Wherein, each first driving line 3 can be conducted or cut off with the sensing plate 21 through the switch device 22 in the fingerprint sensing unit 2, that is, when the switch device 22 is conducted, the voltage signal obtained by the sensing plate 21 can be output through the first driving line 3, and each second driving line 4 is connected with the switch device 22, so as to transmit the conducting signal for the switch device 22.
The actual number of the first driving lines 3 and the second driving lines 4 is not limited in this application and can be adjusted according to the desired fingerprint identification sensing area. In the present embodiment, the angle between the first driving line 3 and the second driving line 4 is preferably 90 °, that is, the first driving line 3 and the second driving line 4 may be disposed in the row direction and the column direction. The first driving lines 3 and the second driving lines 4 are arranged in a crossed manner to form an array of fingerprint sensing units 2.
In this embodiment, the first driving line 3 and the second driving line 4 are made of transparent metal or oxide conductors, and transparent electrodes are formed by disposing the transparent driving lines on the surface of the substrate 1, so that the display effect of the electronic screen is not affected while the electrical connection is ensured. Preferably, the material of the first driving line 3 and the second driving line 4 is indium tin oxide.
In the present embodiment, the first predetermined distance and the second predetermined distance are both 100 to 300 μm. Through setting up first predetermined distance and the predetermined interval 100 ~ 300 mu m of second for fingerprint induction element 2's size is in this within range, when can guaranteeing that fingerprint induction element 2 gathers the fingerprint signal of telecommunication steadily, "millet" and "spine" of fingerprint can also be prevented and the unable signal of telecommunication that distinguishes is located same fingerprint induction element 2.
The driving unit 5 is used for providing a conducting signal for the switching device 22, and the driving unit 5 is connected with at least one second driving line 4 through a first switch S1. Preferably, the driving unit 5 is provided with a charge pump for boosting the voltage, thereby improving the sensitivity of the fingerprint recognition sensor. The signal processing unit 6 is used for reading the voltage signal transmitted by the first driving line 3, the signal processing unit 6 comprises an integrating circuit, the integrating circuit is used for amplifying and outputting the voltage signal, and the integrating circuit is connected with at least one second driving line 4 through a second switch S2. The closed/open state of the first switch S1 is opposite to that of the second switch S2.
Specifically, the first switch S1 may be switched under the control of the first clock signal PH1, and the first switch S1 is closed when the first clock signal PH1 is at a high level, and the first switch S1 is opened when the first clock signal PH1 is at a low level. When the first switch S1 is in a closed state, the driving unit 5 provides a voltage signal to the switching device 22 through the second driving line 4 and the first driving line 3 cross-connected with the second driving line 4 corresponding to the touch operation of the user, and when the finger of the user presses on the sensing area, a fingerprint capacitor 23 is formed with the sensing plate 21 in the array of the fingerprint sensing unit 2, and the fingerprint capacitor 23 stores charges.
The second switch S2 may be switched under the control of a second clock signal PH2, the second clock signal PH2 being inverted from the first clock signal PH 1. That is, when the first clock signal PH1 is at a high level, the second clock signal PH2 is at a low level, and when the first clock signal PH1 is at a low level, the second clock signal PH2 is at a high level. When the first clock signal PH1 is at a high level, the first switch S1 is closed and the second switch S2 is open. When the second clock signal PH2 is at a high level, the first switch S1 is opened and the second switch S2 is closed. In the present embodiment, when the first clock signal PH1 is at a high level and the first switch S1 is closed, the second switch S2 is open and the fingerprint capacitor 23 stores charges, and when the first clock signal PH1 is at a low level, the first switch S1 is open and the second switch S2 is closed and the charges stored in the fingerprint capacitor 23 are transmitted to the signal processing unit 6 through the switching device 22 and the first driving line 3 via the second driving line 4 connected in a crossing manner.
Further, as shown in fig. 2, the switching device 22 may be specifically a thin film transistor device. The switching device 21 has an output end, a connection end and a control end, the connection end and the output end are all connected with the control end, the control end is connected with the second driving wire 4, the output end is connected with the first driving wire 3, and the connection end is connected with the induction polar plate 21. When the first switch S1 is closed, the second switch S2 is turned off, the driving unit 5 can sequentially provide a conducting signal to the control terminal through the second driving line 4, the first driving line 3 and the second driving line 4, and the fingerprint capacitor 23 stores charges. When the first switch S1 is opened, the second switch S2 is closed, and charges can be transmitted to the signal processing unit 6 via the first driving line 3, the switching device 22 and the second driving line 4 in sequence for processing to generate an output signal.
In this embodiment, the switching device 22 has a parasitic capacitance in the array of fingerprint sensing elements 2. When the first clock signal PH1 is at a high level, the first switch S1 is closed and the second switch S2 is opened, the switching device 22 turns on the driving voltage provided by the driving unit 5, and the switching device 22 and the fingerprint capacitor 23 both inject charges. When the first clock signal PH1 is at a low level, the first switch S1 is turned off, the second switch S2 is turned on, and both the parasitic capacitance of the switching device 22 and the fingerprint capacitance 23 can output charges through the switching device 22 and the first driving line 3, so that the influence of the parasitic capacitance of the switching device 22 can be reduced.
As shown in fig. 4, the second switch S2 has a first end and a second end opposite to each other, the first end of the second switch S2 is connected to the second driving line 4, the second end of the second switch S2 is connected to the integrating circuit of the signal processing unit 6, and the signal processing unit 6 includes: an integration circuit and a compensation circuit, wherein the amount of change of the charge stored in the compensation circuit is equal to the amount of charge stored in a substrate capacitor (not shown) in the fingerprint capacitor 23 during the process of switching the first switch S1 from the closed state to the open state. The integrating circuit comprises an integrating amplifier 61, an integrating capacitor Cref and a third switch S3, wherein the integrating amplifier 61 comprises a negative input terminal, a positive input terminal and an output terminal, the negative input terminal of the integrating amplifier 61 is connected with the compensating circuit, the negative input terminal is connected with the second terminal of the second switch S2, and the positive input terminal of the integrating amplifier 61 is connected with a reference voltage Vref. The upper electrode plate of the integrating capacitor Cref is connected with the negative input end of the integrating amplifier 61, and the lower electrode plate of the integrating capacitor Cref is connected with the output end of the integrating amplifier 61. The third switch S3 has a first end and a second end opposite to each other, the first end of the third switch S3 is connected to the upper plate of the integrating capacitor Cref, the second end of the third switch S3 is connected to the lower plate of the integrating capacitor Cref, the third switch S3 is simultaneously closed or opened with the first switch S1, and when the third switch S3 is closed, the integrating circuit is in a reset mode.
Specifically, the third switch S3 may be switched under the control of the first clock phase PH 1. That is, when the first clock phase PH1 is at a high level, the second clock phase PH2 is at a low level, the first switch S1 is closed, the second switch S2 is open, the third switch S3 is closed, the fingerprint capacitor 23 stores a capacitor, and the integration circuit is in a reset mode; when the first clock phase PH1 is at a low level, the second clock phase PH2 is at a high level, the first switch S1 is open, the second switch S2 is closed, the third switch S3 is open, and the integrating circuit and the compensating circuit participate in the transfer of charges.
Because the fingerprint capacitor 23 includes the ridge capacitor and the valley capacitor of the fingerprint, and the ridge capacitor and the valley capacitor can be equivalent to the substrate capacitor and the effective capacitor, the fingerprint detection is mainly completed according to the effective capacitors respectively included in the ridge capacitor and the valley capacitor. However, the substrate capacitance in the ridge capacitance and the valley capacitance is much larger than the respective corresponding effective capacitance, so that the substrate capacitance of the fingerprint capacitance 23 can also generate a fixed substrate signal, the substrate signal will cause output saturation after integral amplification processing is completed, the output dynamic range is greatly reduced, and the output signal is seriously distorted. In the present embodiment, by providing the compensation circuit, in the process of switching the first switch S1 from the closed state to the open state, the amount of change in the charge stored in the compensation circuit is equal to the amount of charge stored in the substrate capacitance in the fingerprint capacitance 23 and the parasitic capacitance in the switching device 22, so that the influence of the substrate capacitance and the parasitic capacitance on the integration circuit can be eliminated.
In this embodiment, the compensation circuit includes: a compensation capacitor Cs, a fourth switch S4, and a fifth switch S5. A first end of the fourth switch S4 is connected to a first power voltage V1, a second end of the fourth switch S4 is connected to the upper plate of the compensation capacitor Cs, a first end of the fifth switch S5 is connected to a second power voltage V2, and a second end of the fifth switch S5 is connected to the upper plate of the compensation capacitor Cs. An upper plate of the compensation capacitor Cs is connected to the second end of the fourth switch S4 and the second end of the fifth switch S5, respectively, a lower plate of the compensation capacitor Cs is connected to the negative input end of the integrating amplifier 61, and a lower plate of the compensation capacitor Cs is connected to the second end of the second switch S2. The fourth switch S4 is closed or opened simultaneously with the first switch S1, the third switch S3, and the fifth switch S5 is closed or opened simultaneously with the second switch S2.
Specifically, the fourth switch S4 may be switched under the control of the first clock phase PH 1. That is, when the first clock phase PH1 is at a high level, the second clock phase PH2 is at a low level, the first switch S1 is closed, the second switch S2 is open, the third switch S3 is closed, the fourth switch S4 is closed, the fingerprint capacitor 23 stores a capacitor, and the integration circuit is in a reset mode; when the first clock phase PH1 is at a low level, the second clock phase PH2 is at a high level, the first switch S1 is open, the second switch S2 is closed, the third switch S3 is open, and the fourth switch S4 is open.
The fifth switch S5 may be switched under the control of the second clock phase PH 2. That is, when the second clock phase PH2 is at a high level, the first clock phase PH1 is at a low level, the first switch S1 is open, the second switch S2 is closed, the third switch S3 is open, the fourth switch S4 is open, and the fifth switch S5 is closed; when the second clock phase PH2 is at a low level, the first clock phase PH1 is at a high level, the first switch S1 is closed, the second switch S2 is open, the third switch S3 is closed, the fourth switch S4 is closed, and the fifth switch S5 is open.
In the present embodiment, one integration process period of the capacitive fingerprint sensor includes a first phase when the first clock phase PH1 is at a high level while the second clock phase PH2 is at a low level, and a second phase when the first clock signal PH1 is at a low level while the second clock signal PH2 is at a high level. When in the first stage, the first switch S1, the third switch S3, and the fourth switch S4 are in a closed state, and the second switch S2 and the fifth switch S5 are in an open state; when in the second phase, i.e., the second switch S2 and the fifth switch S5 are in the closed state, the first switch S1, the third switch S3 and the fourth switch S4 are in the open state.
Referring to fig. 1 and 4, in the first phase, the first switch S1, the third switch S3, and the fourth switch S4 are in a closed state, and the second switch S2 and the fifth switch S5 are in an open state. The fingerprint sensing unit 2 is connected with the driving unit 5 through the first driving line 3 and the second driving line 4, and the fingerprint capacitor 23 stores charges. The fingerprint capacitance is set to Cf and the voltage supplied by the drive unit 5 is set to Vd. When in the first phase, the first switch S1 is closed, the amount of charge stored by the fingerprint capacitor 23 is Cf · Vd, and the amount of charge stored by the parasitic capacitor in the fingerprint sensing unit 2 is CParasitic elementVd; the third switch S3 is closed and the integration circuit is in reset mode; the fourth switch S4 is closed, the upper plate of the compensation capacitor Cs is connected to the first power voltage V1 through the fourth switch S4, and the lower plate of the compensation capacitor Cs is connected to the integrating circuit, so that the charge amount stored in the compensation capacitor Cs is Cs (V1-Vref).
In the second phase, the second switch S2 and the fifth switch S5 are closed, while the first switch S1, the third switch S3 and the fourth switch S4 are open. When the second switch S2 is closed, the sensing plate 21 in the fingerprint capacitor 23 switches on the integrating circuit and the compensating circuit through the second switch S2, and the charges on the fingerprint capacitor 23 and the parasitic capacitor are transferred to the compensating capacitor Cs and the integrating capacitor Cref. The upper plate of the compensation capacitor Cs is connected with a second power supply voltage V2, the variation of the charge stored by the compensation capacitor Cs is Cs (V1-Vref) -Cs (V2-Vref), and the charge stored by the integrating capacitor Cref is Cref (Vref-Vout). From the law of conservation of charge:
(Cf+Cparasitic element)·(Vd-Vref)＝Cs·(V1-Vref)-Cs·(V2-Vref)+Cref·(Vref-Vout) (1)
(Cf+CParasitic element)·(Vd-Vref)＝Cs·(V1-V2)+Cref·(Vref-Vout) (2)
The following can be derived from equation (2):
wherein, Cf＝CSubstrate+CIs effectiveAnd then:
(Cf+Cparasitic element)·(Vd-Vref)＝CSubstrate·(Vd-Vref)+CIs effective·(Vd-Vref)+CParasitic element(Vd-Vref) (4)
Bringing equation (4) into equation (3) can yield:
Vout＝Vref-[Csubstrate·(Vd-Vref)+CIs effective·(Vd-Vref)+CParasitic element(Vd-Vref)—Cs·(V1-V2)]/Cref
By setting Cs·(V1-V2)＝CSubstrate·(Vd-Vref)+CParasitic element(Vd-Vref) Specifically, the difference value of V1-V2 or the size of Cs can be adjusted, so that the charge quantity on the substrate capacitor and the parasitic capacitor is completely transferred to the compensation capacitor Cs, the influence of the substrate capacitor and the parasitic capacitor on the output signal of the integrating circuit is counteracted, the output dynamic range of the integrating circuit is further improved, and the sensitivity of fingerprint identification is favorably improved.
The embodiment of the application also provides an electronic device, as shown in fig. 5, including the capacitive fingerprint identification sensor. The capacitive fingerprint sensor may correspond to the identification area 20 in fig. 5. In this embodiment, through setting up large tracts of land capacitanc fingerprint identification sensor, increased fingerprint identification's sensing area, also can be used to comprehensive screen fingerprint identification, electronic screen 10's display area all can be identification area 20 promptly to improve user experience.
In order to realize the basic functions of the electronic device, the electronic device in the embodiments of the present invention may further include other necessary modules or components. Taking a mobile smartphone as an example, it may also include external circuitry, a communication module, a battery, and the like.
It should be noted that any other necessary modules or components included in the electronic device may be used in any suitable existing configuration. In order to clearly and briefly explain the technical solutions provided by the present invention, the above parts will not be described again, and the drawings in the specification are also simplified correspondingly. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.
Specifically, when the utility model discloses capacitanc fingerprint identification sensor is disposed in electronic equipment when, electronic equipment can acquire user's fingerprint characteristic information based on this capacitanc fingerprint identification sensor for match with the fingerprint information of storage, with the realization to current user's authentication, thereby confirm whether it has corresponding authority to carry out relevant operation to electronic equipment.
The utility model discloses capacitanc fingerprint identification sensor can be used in electronic equipment such as including but not limited to mobile smart mobile phone, dull and stereotyped electronic equipment, computer, GPS navigator, personal digital assistant, intelligent wearable equipment.
It should be noted that, in the description of the present application, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is intended or should be construed to indicate or imply relative importance. In addition, in the description of the present application, "a plurality" means two or more unless otherwise specified.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes.
Claims (10)
1. A capacitive fingerprint recognition sensor, comprising:
a substrate;
the fingerprint sensing units are positioned on the surface of the substrate and distributed in an array manner;
a plurality of first driving lines arranged at intervals of a first predetermined distance on the surface of the substrate;
a plurality of second driving lines arranged on the surface of the substrate at intervals of a second predetermined distance, the second driving lines being cross-connected with the first driving lines to form the fingerprint sensing units, each fingerprint sensing unit comprising: each first driving wire can conduct or cut off the sensing polar plate through the switch device, the sensing polar plate and the fingerprint form a fingerprint capacitor, and each second driving wire is connected with the switch device;
the driving unit is used for providing a conducting signal for the switching device and is connected with at least one second driving wire through a first switch;
a signal processing unit comprising: an integration circuit connected to at least one of the second drive lines through a second switch, the first switch having an on/off state opposite to that of the second switch.
2. The capacitive fingerprint sensor of claim 1 wherein said switching device has an output terminal, a connection terminal and a control terminal, said connection terminal and said output terminal both being connected to said control terminal, said control terminal being connected to said second drive line, said output terminal being connected to said first drive line, said connection terminal being connected to said sensing plate,
when the first switch is closed, the second switch is switched off, the driving unit can provide a conducting signal for the control end through the second driving line, the first driving line and the second driving line in sequence, and the fingerprint capacitor stores charges; when the first switch is switched off, the second switch is switched on, and charges can be transmitted to the signal processing unit for processing through the first driving line, the switching device and the second driving line in sequence so as to generate an output signal.
3. The capacitive fingerprint recognition sensor of claim 1, wherein said second switch has opposite first and second ends, said first end of said second switch being connected to said second drive line, said second end of said second switch being connected to said integration circuit, said signal processing unit further comprising a compensation circuit;
the compensation circuit includes: the compensation capacitor, the fourth switch and the fifth switch; a first end of the fourth switch is connected with a first power voltage, a second end of the fourth switch is connected with an upper pole plate of the compensation capacitor, a first end of the fifth switch is connected with a second power voltage, and a second end of the fifth switch is connected with the upper pole plate of the compensation capacitor;
an upper pole plate of the compensation capacitor is respectively connected with a second end of the fourth switch and a second end of the fifth switch, a lower pole plate of the compensation capacitor is connected with the integrating circuit, and a lower pole plate of the compensation capacitor is connected with a second end of the second switch;
the fourth switch and the first switch are closed or opened simultaneously, and the fifth switch and the second switch are closed or opened simultaneously.
4. The capacitive fingerprint recognition sensor of claim 3 wherein said integration circuit comprises an integrating amplifier, an integrating capacitor, and a third switch;
the integrating amplifier comprises a negative input end, a positive input end and an output end, the negative input end of the integrating amplifier is connected with the compensation circuit, the negative input end of the integrating amplifier is connected with the second end of the second switch, and the positive input end of the integrating amplifier is connected with a reference voltage; the upper polar plate of the integrating capacitor is connected with the negative input end of the integrating amplifier, and the lower polar plate of the integrating capacitor is connected with the output end of the integrating amplifier;
the first end of the third switch is connected with the upper pole plate of the integrating capacitor, the second end of the third switch is connected with the lower pole plate of the integrating capacitor, the third switch and the first switch are closed or opened simultaneously, and when the third switch is closed, the integrating circuit is in a reset mode.
5. The capacitive fingerprint recognition sensor of claim 1, wherein the first drive line and the second drive line are both made of transparent metal or oxide conductors.
6. The capacitive fingerprint recognition sensor of claim 5, wherein the material of the first drive line and the second drive line is indium tin oxide.
7. The capacitive fingerprint sensor of claim 1 wherein said first predetermined distance and said second predetermined distance are each 100-300 μm.
8. The capacitive fingerprint recognition sensor of claim 1, wherein an angle between the first drive line and the second drive line is 90 °.
9. The capacitive fingerprint recognition sensor of claim 1, wherein said drive unit is provided with a charge pump for boosting voltage.
10. An electronic device, characterized in that it comprises a capacitive fingerprint recognition sensor according to any one of claims 1-9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921321240.6U CN210142336U (en) | 2019-08-15 | 2019-08-15 | Capacitive fingerprint identification sensor and electronic equipment |
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| CN201921321240.6U CN210142336U (en) | 2019-08-15 | 2019-08-15 | Capacitive fingerprint identification sensor and electronic equipment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021203418A1 (en) * | 2020-04-10 | 2021-10-14 | 京东方科技集团股份有限公司 | Fingerprint recognition detection circuit and method for controlling same, and fingerprint recognition control chip |
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2019
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021203418A1 (en) * | 2020-04-10 | 2021-10-14 | 京东方科技集团股份有限公司 | Fingerprint recognition detection circuit and method for controlling same, and fingerprint recognition control chip |
| CN113785300A (en) * | 2020-04-10 | 2021-12-10 | 京东方科技集团股份有限公司 | Fingerprint identification detection circuit, control method thereof and fingerprint identification control chip |
| US20220114827A1 (en) * | 2020-04-10 | 2022-04-14 | Beijing Boe Sensor Technology Co., Ltd. | Fingerprint recognition detection circuit and control method thereof, fingerprint recognition control chip |
| US11568671B2 (en) | 2020-04-10 | 2023-01-31 | Beijing Boe Sensor Technology Co., Ltd. | Fingerprint recognition detection circuit and control method thereof, fingerprint recognition control chip |
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