WO2018041077A1 - 指纹传感器和终端设备 - Google Patents

指纹传感器和终端设备 Download PDF

Info

Publication number
WO2018041077A1
WO2018041077A1 PCT/CN2017/099340 CN2017099340W WO2018041077A1 WO 2018041077 A1 WO2018041077 A1 WO 2018041077A1 CN 2017099340 W CN2017099340 W CN 2017099340W WO 2018041077 A1 WO2018041077 A1 WO 2018041077A1
Authority
WO
WIPO (PCT)
Prior art keywords
excitation signal
sensing unit
voltage
detection
fingerprint sensor
Prior art date
Application number
PCT/CN2017/099340
Other languages
English (en)
French (fr)
Inventor
张自宝
张�杰
徐坤平
杨云
Original Assignee
比亚迪股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201620975816.0U external-priority patent/CN206209764U/zh
Priority claimed from CN201610754542.7A external-priority patent/CN106446780B/zh
Application filed by 比亚迪股份有限公司 filed Critical 比亚迪股份有限公司
Publication of WO2018041077A1 publication Critical patent/WO2018041077A1/zh

Links

Images

Classifications

    • 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
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F18/00—Pattern recognition

Definitions

  • the present invention relates to the field of fingerprint identification technologies, and in particular, to a fingerprint sensor and a terminal device.
  • the detection of the fingerprint is realized by detecting a small capacitance formed by the surface of the finger and the sensing chip of the fingerprint sensor.
  • the excitation signal can be transmitted through the external metal frame and received inside the fingerprint sensor to realize the detection of the fingerprint; or the excitation sensor can be internally generated by the fingerprint sensor to form the detection capacitor with the finger to realize the detection of the fingerprint. .
  • the fingerprint sensor When detecting the fingerprint to detect the fingerprint, the fingerprint is distributed on the surface of the finger.
  • the fingerprint sensor usually has a panel shape and an array sensing unit is disposed on the surface thereof. When the finger is placed on the sensing unit, the sensing unit realizes the detection of the fingerprint. .
  • the emission voltage is limited. Since the emission voltage is affected by the supply voltage and the working range of the fingerprint sensor itself, the emission voltage is greatly restricted, and the smaller the emission voltage, the weaker the signal detected by the fingerprint, which affects the detection accuracy;
  • Fingerprint sensors usually have a large surface area to fully capture the fingerprints distributed on the surface of the finger, but the large surface area is likely to cause large noise and manufacturing process errors of the fingerprint sensor, resulting in degradation of the chip performance;
  • the package thickness is limited. Thicker packages are the development direction of fingerprint sensors, and thicker packages require higher emission voltages and lower noise.
  • FIG. 1 is a schematic diagram of a detection mode of a conventional fingerprint sensing unit.
  • a sensing unit 11 performs fingerprint detection
  • the surrounding sensing unit is in a closed state.
  • the interference of adjacent sensing units is shown in Figure 2.
  • the timing of the excitation (1-9) of each sensing unit in Figure 2 is shown in Figure 3.
  • a is the fingerprint sensing unit array
  • the sensing unit b performs fingerprint detection.
  • the adjacent sensing unit c is in a closed state, and the parasitic capacitance Cp between b and c interferes with b, which reduces the accuracy of fingerprint detection.
  • a first object of the invention is to propose a fingerprint sensor.
  • the fingerprint sensor can improve the fingerprint detection accuracy, thereby improving the fingerprint recognition rate, and has low requirements on the package thickness and good applicability.
  • a second object of the present invention is to provide a terminal device.
  • a first aspect of the present invention provides a fingerprint sensor, including: an inductive chip, the sensing chip includes an array of sensing cells, a first ground terminal, and a first excitation signal for providing a first excitation signal a source, and a second excitation signal source, the second excitation signal source being coupled to the first ground terminal for providing the second excitation signal, and the second excitation signal and the first excitation signal are synchronized
  • the sensing unit includes: a detecting electrode configured to form a detecting capacitance with a user's finger, and a capacitance detecting circuit respectively, the capacitance detecting circuit and the first excitation signal source, and the detecting The electrode is connected to the first ground end for generating a detection voltage according to the detection capacitance, the first excitation signal and the second excitation signal.
  • the fingerprint sensor of the embodiment of the invention completes the excitation signal transmission by superimposing the first excitation signal and the second excitation signal, improves the signal to noise ratio, improves the fingerprint detection precision, and further improves the fingerprint recognition rate, and has low requirements on the package thickness, and is applicable. Good sex.
  • the second aspect of the present invention provides a terminal device, including the fingerprint sensor according to the foregoing embodiment of the present invention.
  • the terminal device of the embodiment of the invention has high fingerprint detection precision, high fingerprint recognition rate, and low requirement on the package thickness of the fingerprint sensor.
  • FIG. 1 is a schematic diagram of a detection mode of a fingerprint sensor sensing unit
  • FIG. 2 is a schematic diagram of parasitic capacitance interference during fingerprint detection in the related art
  • 3 is a schematic diagram of timings of excitation signals of respective sensing units in the related art
  • FIG. 4 is a block diagram showing the structure of a fingerprint sensor according to an embodiment of the present invention.
  • FIG. 5 is a schematic diagram of timings of excitation signals of respective sensing units of a fingerprint sensor according to an embodiment of the present invention
  • FIG. 6 is a schematic structural diagram of a fingerprint detecting circuit of a fingerprint sensor according to an embodiment of the present invention.
  • FIG. 7 is a schematic structural diagram of a fingerprint detecting circuit of a fingerprint sensor according to another embodiment of the present invention.
  • FIG. 8 is a schematic illustration of fingerprint detection in accordance with one embodiment of the present invention.
  • FIG. 9 is a schematic diagram of the principle of a fingerprint detecting circuit in accordance with an embodiment of the present invention.
  • the fingerprint sensor includes a sensing chip 10 and a second excitation signal source 20.
  • the sensing chip 10 includes an array of sensing units 11 (only four sensing units are shown in FIG. 5), a first ground terminal, and a first excitation signal source 12 for providing a first excitation signal, and the sensing unit 11 includes a detection electrode.
  • the detecting electrode 111 is configured to form a detecting capacitance with the user's finger, and the capacitance detecting circuit 112 and the first excitation signal source 12, the detecting electrode 111 and the first grounding end respectively (the capacitance detecting circuit 112 is not shown in FIG.
  • the second excitation signal source 20 is connected to the first ground terminal for providing the second excitation signal, And the second excitation signal is synchronized with the first excitation signal.
  • the overall signal amount for the capacitance detecting circuit 112 is increased, and the signal-to-noise ratio can be increased by Tx_gnd/Tx_in times without adding a new noise source, wherein Tx_in For the first excitation signal, Tx_gnd is the second excitation signal.
  • all the sensing units of the sensing unit array are synchronously excited by the first excitation signal and the second excitation signal, that is, All of the sensing units of the sensing unit array are used to synchronously sense the first excitation signal and the second excitation signal.
  • 1, 2, 3, and 4 respectively indicate the sum of the first excitation signal and the second excitation signal applied to the four sensing units shown in FIG. 4, that is, Tx_in+Tx_gnd.
  • the sensing unit 11 When one of the sensing units 11 performs fingerprint detection (detecting the size of the detection capacitance), the sensing unit 11 is a measurement sensing unit, and the other sensing units 11 are sensing units to be tested, and the measuring sensing unit and the sensing unit to be tested are synchronously The first excitation signal and the second excitation signal are excited, so that the influence of the parasitic capacitance generated between the adjacent sensing units 11 can be eliminated.
  • the measurement sensing unit may be selected by a gating unit (not shown in FIG. 4).
  • the capacitance detecting circuit 112 includes an operational amplifier 1121 and a feedback circuit 1122, wherein the operational amplifier 1121 includes a first input terminal, a second input terminal, and a second a ground terminal and an output terminal, the second ground terminal is connected to the second excitation signal source 20, and the operational amplifier 1121 is configured to generate a detection voltage according to the detection capacitance, the first excitation signal and the second excitation signal; one end of the feedback circuit 1122 and the operational amplifier 1121 of The second input is connected, and the other end of the feedback circuit 1122 is connected to the output of the operational amplifier 1121.
  • the first ground end and the second ground end are both sensing chip ground.
  • the operational amplifier 1121 further includes a power terminal through which the power supply is connected to operate the operational amplifier 1121.
  • the feedback circuit 1122 includes a reference capacitor Ci and a first switch S1, wherein one end of the reference capacitor Ci is connected to the second input terminal of the operational amplifier 1121, and the other end is connected to the output terminal of the operational amplifier 1121; the first switch S1 and The reference capacitors Ci are connected in parallel.
  • the second input terminal is a negative input terminal of the operational amplifier 1121
  • the first input terminal is a positive input terminal of the operational amplifier 1121.
  • the positive input terminal of the operational amplifier 1121 is connected to the first excitation signal source 12, and the negative input terminal of the operational amplifier 1121 is connected to the detection electrode 111.
  • first excitation signal and the second excitation signal may both be square wave signals, and the first excitation signal and the second excitation signal may be in-phase signals of each other, or may be mutually inverted signals.
  • the first excitation signal Tx_in is applied to each sensing unit 11 of the fingerprint chip 10 through the first excitation signal source 12, and the first sensing chip 10 of the fingerprint sensor is passed through the second excitation signal source 20.
  • a second excitation signal Tx_gnd is applied to the ground.
  • a detection capacitance Cf is formed between the user's finger and the detection electrode 111 in the sensing unit 11.
  • m1, m2, and m3 are three different metal layers
  • the metal layer m1 is a plate on the sensing unit 11 of the fingerprint sensor for forming a detecting capacitance Cf with the user's finger (ie, detecting
  • the plate 111) forms a reference capacitance Ci between the metal layer m2 and the metal layer m3, the positive input terminal of the operational amplifier 41 inputs the first excitation signal Tx_in, and the negative input terminal is connected to the metal layer m1 and the metal layer m3, respectively, and the output end is
  • the metal layer m2 is connected, and the second ground terminal inputs a second excitation signal Tx_gnd.
  • the working process of the capacitance detecting circuit 112 is as follows:
  • the first stage the first switch S1 is in a closed state, the negative input end of the operational amplifier 1121 follows the positive input terminal, the input voltage of the positive input terminal (ie, the first excitation signal) Tx_in is a high level, and the second ground terminal inputs
  • the second excitation signal Tx_gnd is also at a high level potential.
  • the second phase the first switch S1 is switched from the closed state to the open state, the first excitation signal Tx_in becomes a low level, and is equal to the second excitation signal Tx_gnd, wherein the second excitation signal Tx_gnd is at a potential of zero.
  • detecting electricity The voltage across the capacitor Cf is equal, and all the stored charge is transferred to the reference capacitor Ci.
  • ⁇ Vout is the amount of change in the detection voltage, that is, the difference between the detection voltage of the finger touch sensing unit and the fingerless sensing unit
  • ⁇ Cf is the amount of change of the detection capacitance, that is, the finger touch sensing unit and the fingerless sensing unit.
  • Ci is the reference capacitance
  • Tx_in is the first excitation signal
  • Tx_gnd is the second excitation signal.
  • the total excitation signal amount is increased by adding the second excitation signal Tx_gnd, and the signal-to-noise ratio is increased by Tx_gnd/Tx_in times without adding a new noise source.
  • the first excitation signal source 12 includes a first voltage source 121 and a second voltage source 122, and the first voltage source 121 is configured to generate a first voltage, a second voltage.
  • Source 122 is used to generate a second voltage.
  • the first voltage source 121 is connected to the negative input terminal of the operational amplifier 1121, and the second voltage source 122 is connected to the positive input terminal of the operational amplifier 1121 through the second switch S2 and the third switch S3 connected in series, and is connected to the second switch.
  • a node A is formed between S2 and the third switch S3, and the node A is connected to the detecting electrode 111.
  • first voltage and the second voltage are both referenced to the second excitation signal Tx_gnd, and the relative voltage between the first voltage and the second excitation signal Tx_gnd is stable, and the relative relationship between the second voltage and the second excitation signal Tx_gnd The voltage is stable.
  • the operational amplifier 1121 clamps the negative input terminal so that the negative input terminal potential is maintained as the positive input terminal to input the first voltage.
  • the first excitation signal Tx_in is applied to each sensing unit 11 of the sensing chip 10 by the first excitation signal source 12, and the first grounding end of the fingerprint sensor is applied by the second excitation signal source 20.
  • Two excitation signals Tx_gnd When the user's finger covers the sensor chip 10, a detection capacitance Cf is formed between the user's finger and the detection electrode 111 in the sensing unit 11.
  • the positive input terminal of the operational amplifier 1121 is input with the first voltage Vref1
  • the negative input terminal of the operational amplifier 1121 is input with the second voltage Vref2 through the second switch S2 and the third switch S3, and the negative input terminal is respectively connected with the detecting capacitor Cf and the reference capacitor Ci
  • One end is connected, the output end is connected to the other end of the reference capacitor Ci, and the second ground end is input to the second excitation signal Tx_gnd, wherein the second voltage Vref2 is greater than the first voltage Vref1.
  • the working process of the capacitance detecting circuit 112 is as follows:
  • the first stage the first switch S1 and the third switch S3 are in a closed state, the second switch S2 is in an off state, and the second excitation signal Tx_gnd is at a high level potential.
  • Tx_in Vref2-Vref1
  • ⁇ Vout is the amount of change of the detection voltage, that is, the difference between the detection voltage of the finger touch sensing unit and the fingerless sensing unit
  • ⁇ Cf is the amount of change of the detection capacitance, that is, the finger touch sensing unit and There is no difference in the detection capacitance of the finger touch sensing unit
  • Ci is the reference capacitance
  • Tx_in is the first excitation signal
  • Vref1 is the first voltage
  • Vref2 is the second voltage
  • Tx_gnd is the second excitation signal.
  • the total excitation signal amount is increased by adding the second excitation signal Tx_gnd, and the signal-to-noise ratio is increased by Tx_gnd/Tx_in times without adding a new noise source.
  • the fingerprint structure can be wrapped around the fingerprint sensor to protect the fingerprint sensor, and the surface of the package structure can be sprayed to enhance the user experience.
  • the fingerprint sensor of the embodiment of the present invention completes the excitation signal transmission by superimposing the first excitation signal and the second excitation signal, thereby improving the emission voltage and the signal-to-noise ratio, thereby improving the fingerprint detection accuracy, and the requirement for the package thickness is low. Can improve the applicability of the fingerprint sensor.
  • the present invention proposes a terminal device including the fingerprint sensor of the above embodiment of the present invention.
  • the terminal device includes, but is not limited to, a smartphone, a portable computer, a tablet or a fingerprint lock, and the like.
  • the terminal device of the embodiment of the invention has high fingerprint detection precision, high fingerprint recognition rate, and low requirements on the packaging structure and thickness of the fingerprint sensor.
  • first and second are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated.
  • features defining “first” or “second” may include at least one of the features, either explicitly or implicitly.
  • the meaning of "a plurality” is at least two, such as two, three, etc., unless specifically defined otherwise.
  • the terms “installation”, “connected”, “connected”, “fixed” and the like shall be understood broadly, and may be either a fixed connection or a detachable connection, unless explicitly stated and defined otherwise. , or integrated; can be mechanical or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction of two elements, unless otherwise specified Limited.
  • the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.
  • the first feature "on” or “under” the second feature may be a direct contact of the first and second features, or the first and second features may be indirectly through an intermediate medium, unless otherwise explicitly stated and defined. contact.
  • the first feature "above”, “above” and “above” the second feature may be that the first feature is directly above or above the second feature, or merely that the first feature level is higher than the second feature.
  • the first feature “below”, “below” and “below” the second feature may be that the first feature is directly below or obliquely below the second feature, or merely that the first feature level is less than the second feature.

Abstract

本发明公开了一种指纹传感器和终端设备，其中，指纹传感器包括：感应芯片，感应芯片包括感应单元阵列、第一接地端和用于提供第一激励信号的第一激励信号源，感应单元包括用于与用户手指之间形成检测电容的检测电极，电容检测电路，电容检测电路分别与第一激励信号源、检测电极和第一接地端相连，用于根据检测电容、第一激励信号和第二激励信号生成检测电压；第二激励信号源，第二激励信号源与第一接地端相连，用于提供第二激励信号，且第二激励信号和第一激励信号同步。本发明实施例的指纹传感器能够提高指纹检测精度，进而能够提高指纹识别率，且对封装厚度要求低，适用性好。

Description

指纹传感器和终端设备
相关申请的交叉引用
本申请要求比亚迪股份有限公司于2016年8月29日提交的、发明名称为“指纹传感器和终端设备”的、中国专利申请号“201610754542.7”和“201620975816.0”的优先权。
技术领域
本发明涉及指纹识别技术领域，具体涉及一种指纹传感器和终端设备。
背景技术
在指纹传感器中，通过检测手指表面与指纹传感器的感应芯片形成的微小电容来实现对指纹的检测。具体地，可以通过外部金属框发射激励信号，并在指纹传感器内部接收，以实现对指纹的检测；也可以通过指纹传感器内部发射激励，使感应芯片与手指形成检测电容，以实现对指纹的检测。
当通过检测电容来实现对指纹的检测时，指纹分布于手指表面，指纹传感器通常呈现面板状且其表面分布着阵列式感应单元，当手指置于感应单元上时，感应单元实现对指纹的检测。
然而，通常情况下，手指与感应芯片之间形成的电容很小，因此上述技术中存在如下不足：
1、发射电压受限。由于发射电压受供电电压和指纹传感器本身器件工作范围的影响，发射电压受到很大制约，发射电压越小，指纹检测到的信号越微弱，影响检测精度；
2、易受噪声干扰。指纹传感器通常有较大的表面积，以充分采集手指表面分布的指纹，但较大的表面积易导致指纹传感器较大的噪声和制造工艺上的误差，导致芯片性能下降；
3、封装厚度受限。更厚的封装是指纹传感器的发展方向，更厚的封装需要更高的发射电压与更低的噪声。
同时，指纹感应单元之间会产生寄生电容，在进行指纹检测时，寄生电容相互干扰影响指纹检测精度。图1为现有的指纹感应单元的检测模式示意图，当一感应单元11进行指纹检测时，其周围感应单元处于关闭状态。相邻感应单元的干扰如图2所示，图2中各感应单元发射激励(1-9)的时序如图3所示，图2中a为指纹感应单元阵列，感应单元b进行指纹检测时，其相邻感应单元c处于关闭状态，b与c之间的寄生电容Cp对b产生干扰，降低了指纹检测的精度。
发明内容
本发明旨在至少在一定程度上解决上述技术中的技术问题之一。为此，本发明的第一个目的在于提出一种指纹传感器。该指纹传感器能够提高指纹检测精度，进而能够提高指纹识别率，且对封装厚度要求低，适用性好。
本发明的第二个目的在于提出一种终端设备。
为达到上述目的，本发明第一方面实施例提出了一种指纹传感器，包括：感应芯片，所述感应芯片包括感应单元阵列、第一接地端和用于提供第一激励信号的第一激励信号源，以及第二激励信号源，所述第二激励信号源与所述第一接地端相连，用于提供所述第二激励信号，且所述第二激励信号和所述第一激励信号同步；其中，所述感应单元包括：检测电极，所述检测电极用于与用户手指之间形成检测电容，以及电容检测电路，所述电容检测电路分别与所述第一激励信号源、所述检测电极和所述第一接地端相连，用于根据所述检测电容、所述第一激励信号和第二激励信号生成检测电压。
本发明实施例的指纹传感器，通过第一激励信号和第二激励信号叠加完成激励信号发射，提高了信噪比，提高指纹检测精度，进而能够提高指纹识别率，且对封装厚度要求低，适用性好。
进一步地，本发明第二方面实施例提出了一种终端设备，包括本发明上述实施例所述的指纹传感器。
本发明实施例的终端设备，指纹检测精度高，指纹识别率高，且对指纹传感器的封装厚度要求低。
附图说明
图1是指纹传感器感应单元的检测模式示意图；
图2是相关技术中指纹检测时寄生电容干扰示意图；
图3是相关技术中各个感应单元的激励信号时序的示意图；
图4是根据本发明一个实施例的指纹传感器的结构框图；
图5是根据本发明一个实施例的指纹传感器的各个感应单元的激励信号时序的示意图；
图6是根据本发明一个实施例的指纹传感器的指纹检测电路的结构示意图；
图7根据本发明的另一个实施例的指纹传感器的指纹检测电路的结构示意图；
图8是根据本发明的一个实施例的指纹检测的示意图；
图9是根据本发明一个具体实施例的指纹检测电路的原理示意图。
具体实施方式
下面详细描述本发明的实施例，所述实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，旨在用于解释本发明，而不能理解为对本发明的限制。
下面参考附图描述本发明实施例的指纹传感器和终端设备。
图4是根据本发明一个实施例的指纹传感器的结构框图。如图4所示，该指纹传感器包括：感应芯片10和第二激励信号源20。
其中，感应芯片10包括感应单元11阵列(图5中只示出了4个感应单元)、第一接地端和用于提供第一激励信号的第一激励信号源12，感应单元11包括检测电极111，检测电极111用于与用户手指之间形成检测电容，电容检测电路112分别与所述第一激励信号源12、检测电极111和第一接地端(图4中未示出电容检测电路112与第一接地端的连接关系)相连，用于根据检测电容、第一激励信号和第二激励信号生成检测电压；第二激励信号源20与第一接地端相连，用于提供第二激励信号，且第二激励信号和第一激励信号同步。
由此，通过上述第二激励信号的增加，提高了用于电容检测电路112的总体信号量，在没有增加新的噪声源的情况下，能够使信噪比提升Tx_gnd/Tx_in倍，其中，Tx_in为第一激励信号，Tx_gnd为第二激励信号。
同时，为了消除相邻感应单元11之间产生的寄生电容的影响，在本发明的实施例中，感应单元阵列的所有感应单元同步地被第一激励信号和第二激励信号激励，也就是说，感应单元阵列的所有感应单元用于同步地感应第一激励信号和第二激励信号。例如，如图5所示，1、2、3、4分别表示施加在图4中所示的4个感应单元上的第一激励信号与第二激励信号之和，即Tx_in+Tx_gnd。
当对其中的一个感应单元11进行指纹检测(检测检测电容的大小)时，该感应单元11为测量感应单元，其他感应单元11为待测感应单元，测量感应单元和待测感应单元同步地被第一激励信号和第二激励信号激励，这样即可以消除相邻感应单元11之间产生的寄生电容的影响。当需要对其中的测量感应单元进行指纹检测时，通过一选通单元(图4中未示出)选中该测量感应单元即可。
在本发明的一个实施例中，如图6、图7所示，电容检测电路112包括：运算放大器1121和反馈电路1122，其中，运算放大器1121包括第一输入端、第二输入端、第二接地端和输出端，第二接地端与第二激励信号源20相连，运算放大器1121用于根据检测电容、第一激励信号和第二激励信号生成检测电压；反馈电路1122的一端与运算放大器1121的 第二输入端相连，反馈电路1122的另一端与运算放大器1121的输出端相连。
需要说明的是，在本发明的实施例中，第一接地端与第二接地端均为感应芯片地。
可以理解，运算放大器1121还包括电源端，通过该电源端连接供电电源，以使运算放大器1121工作。
进一步地，反馈电路1122包括基准电容Ci和第一开关S1，其中，基准电容Ci的一端与运算放大器1121的第二输入端相连，另一端与运算放大器1121的输出端相连；第一开关S1与基准电容Ci并联连接。
其中，第二输入端为运算放大器1121的负输入端，第一输入端为运算放大器1121的正输入端。
基于上述说明，在本发明的一个实施例中，运算放大器1121的正输入端与第一激励信号源12相连，运算放大器1121的负输入端与检测电极111相连。
可选地，第一激励信号与第二激励信号可以均为方波信号，且第一激励信号与第二激励信号可以互为同相信号，也可以互为反相信号。
具体而言，如图8所示，通过第一激励信号源12对指纹芯片10的各感应单元11施加第一激励信号Tx_in，通过第二激励信号源20对指纹传感器的感应芯片10的第一接地端施加第二激励信号Tx_gnd。当用户手指覆盖感应芯片10时，用户手指与感应单元11中的检测电极111之间形成检测电容Cf。
进一步而言，如图9所示，m1、m2与m3为三个不同的金属层，金属层m1为指纹传感器的感应单元11上用于与用户手指形成检测电容Cf的一个极板(即检测极板111)，金属层m2与金属层m3之间形成基准电容Ci，运算放大器41的正输入端输入第一激励信号Tx_in，负输入端分别与金属层m1、金属层m3相连，输出端与金属层m2相连，第二接地端输入第二激励信号Tx_gnd。电容检测电路112的工作过程如下：
第一阶段：第一开关S1处于闭合状态，运算放大器1121的负输入端跟随正输入端，其正输入端的输入电压(即第一激励信号)Tx_in为的高电平，第二接地端输入的第二激励信号Tx_gnd为也处于高电平电位。此时，检测电容Cf存储的电荷为：QCf＝(Tx_in+Tx_gnd)*Cf。
第二阶段：第一开关S1由闭合状态切换至断开状态，第一激励信号Tx_in变为低电平，且与第二激励信号Tx_gnd相等，其中，第二激励信号Tx_gnd处于0电位。此时，检测电 容Cf两端的电压相等，其存储的全部电荷转移至基准电容Ci，根据电荷守恒定理可以推导出如下公式(1)：
Figure PCTCN2017099340-appb-000001
其中，ΔVout为检测电压的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电压的差值，ΔCf为检测电容的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电容的差值，Ci为基准电容，Tx_in为所述第一激励信号，Tx_gnd为所述第二激励信号。
由此，本发明实施例的指纹传感器中因加入第二激励信号Tx_gnd从而提升了总体激励信号量，在没有增加新的噪声源的情况下，信噪比提升了Tx_gnd/Tx_in倍。
在本发明的另一个实施例中，如图7所示，第一激励信号源12包括第一电压源121和第二电压源122，第一电压源121用于产生第一电压，第二电压源122用于产生第二电压。其中，第一电压源121与运算放大器1121的负输入端相连，第二电压源122通过串联连接的第二开关S2和第三开关S3与运算放大器1121的正输入端相连，并在第二开关S2和第三开关S3之间形成节点A，节点A与检测电极111相连。
其中，第一电压和第二电压均可以第二激励信号Tx_gnd为参考地，且第一电压与第二激励信号Tx_gnd之间的相对电压稳定，第二电压与第二激励信号Tx_gnd之间的相对电压稳定。
需要说明的是，运算放大器1121通过对负输入端的钳位，使得负输入端电位保持为正输入端输入第一电压。
具体而言，如图8所示，通过第一激励信号源12对感应芯片10的各感应单元11施加第一激励信号Tx_in，通过第二激励信号源20对指纹传感器的第一接地端施加第二激励信号Tx_gnd。当用户手指覆盖感应芯片10时，用户手指与感应单元11中的检测电极111之间形成检测电容Cf。运算放大器1121的正输入端输入第一电压Vref1，运算放大器1121的负输入端通过第二开关S2和第三开关S3输入第二电压Vref2，且负输入端分别与检测电容Cf和基准电容Ci的一端相连，输出端与基准电容Ci的另一端相连，第二接地端输入第二激励信号Tx_gnd，其中，第二电压Vref2大于第一电压Vref1。电容检测电路112的工作过程如下：
第一阶段：第一开关S1、第三开关S3处于闭合状态，第二开关S2处于断开状态，第二激励信号Tx_gnd为高电平电位。此时，检测电容Cf存储的电荷为：QCf＝(Vref2+Tx_gnd)*Cf，其中，Vref2为第二电压。
第二阶段：第一开关S1、第三开关S3由闭合切换至断开状态，第二开关S2由闭合切换至断开状态，第二激励信号Tx_gnd变为0电位。此时，检测电容Cf存储的电荷为：QCf＝Vref1*Cf，其中，Vref1为第一电压。根据电荷守恒定理可以推导出如下公式(1)：
Figure PCTCN2017099340-appb-000002
其中，Tx_in＝Vref2-Vref1，ΔVout为检测电压的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电压的差值，ΔCf为检测电容的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电容的差值，Ci为基准电容，Tx_in为第一激励信号，Vref1为第一电压，Vref2为第二电压，Tx_gnd为第二激励信号。
同理，本发明实施例的指纹传感器中因加入第二激励信号Tx_gnd从而提升了总体激励信号量，在没有增加新的噪声源的情况下，信噪比提升了Tx_gnd/Tx_in倍。
可以理解的是，可以设置封装结构包绕该指纹传感器，以对指纹传感器进行保护，同时，封装结构表面可以喷涂涂层，以提升用户使用体验。
综上，本发明实施例的指纹传感器，通过第一激励信号和第二激励信号叠加完成激励信号发射，提高了发射电压和信噪比，进而能够提高指纹检测精度，且其对封装厚度要求低，能够提高指纹传感器的适用性。
基于上述实施例，本发明提出了一种终端设备，包括本发明上述实施例的指纹传感器。
在本发明的一个实施例中，该终端设备包括但不限于智能手机、便携式计算机、平板电脑或指纹锁等。
本发明实施例的终端设备，指纹检测精度高，指纹识别率高，且对指纹传感器的封装结构和涂层的厚度要求低。
另外，根据本发明实施例的终端设备的其它构成以及作用对于本领域的普通技术人员而言都是已知的，为了减少冗余，此处不做赘述。
在本发明的描述中，需要理解的是，术语“中心”、“长度”、“宽度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示 所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本发明的描述中，“多个”的含义是至少两个，例如两个，三个等，除非另有明确具体的限定。
在本发明中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系，除非另有明确的限定。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本发明中，除非另有明确的规定和限定，第一特征在第二特征“上”或“下”可以是第一和第二特征直接接触，或第一和第二特征通过中间媒介间接接触。而且，第一特征在第二特征“之上”、“上方”和“上面”可是第一特征在第二特征正上方或斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”可以是第一特征在第二特征正下方或斜下方，或仅仅表示第一特征水平高度小于第二特征。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
尽管上面已经示出和描述了本发明的实施例，可以理解的是，上述实施例是示例性的，不能理解为对本发明的限制，本领域的普通技术人员在本发明的范围内可以对上述实施例进行变化、修改、替换和变型。

Claims (11)

  1. 一种指纹传感器，其特征在于，包括：
    感应芯片，所述感应芯片包括感应单元阵列、第一接地端和用于提供第一激励信号的第一激励信号源，以及
    第二激励信号源，所述第二激励信号源与所述第一接地端相连，用于提供所述第二激励信号，且所述第二激励信号和所述第一激励信号同步；
    其中，所述感应单元包括：
    检测电极，所述检测电极用于与用户手指之间形成检测电容，以及
    电容检测电路，所述电容检测电路分别与所述第一激励信号源、所述检测电极和所述第一接地端相连，用于根据所述检测电容、所述第一激励信号和第二激励信号生成检测电压。
  2. 如权利要求1所述的指纹传感器，其特征在于，所述感应单元阵列的所有感应单元同步地被所述第一激励信号和第二激励信号激励。
  3. 如权利要求2所述的指纹传感器，其特征在于，还包括选通单元，所述感应单元阵列包括测量感应单元和待测感应单元，所述测量感应单元和待测感应单元同步地被所述第一激励信号和第二激励信号激励，通过所述选通单元选中测量感应单元并输出相应的检测电压。
  4. 如权利要求1-3中任一项所述的指纹传感器，其特征在于，所述第二激励信号和所述第一激励信号同相或反相。
  5. 如权利要求1-3中任一项所述的指纹传感器，其特征在于，所述电容检测电路包括：
    运算放大器，所述运算放大器包括第一输入端、第二输入端、第二接地端和输出端，所述第二接地端与所述第二激励信号源相连；
    反馈电路，所述反馈电路的一端与所述运算放大器的第二输入端相连，所述反馈电路的另一端与所述运算放大器的输出端相连。
  6. 如权利要求5所述的指纹传感器，其特征在于，所述反馈电路包括：
    基准电容，所述基准电容的一端与所述运算放大器的第二输入端相连，另一端与所述运算放大器的输出端相连，其中，所述第二输入端为所述运算放大器的负输入端；
    第一开关，所述第一开关与所述基准电容并联。
  7. 如权利要求6所述的指纹传感器，其特征在于，所述运算放大器的第一输入端与所述第一激励信号源相连，所述运算放大器的第二输入端与所述检测电极相连。
  8. 如权利要求7所述的指纹传感器，其特征在于，所述检测电压的变化量用如下公式 表示：
    Figure PCTCN2017099340-appb-100001
    其中，ΔVout为所述检测电压的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电压的差值，ΔCf为所述检测电容的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电容的差值，Ci为所述基准电容，Tx_in为所述第一激励信号，Tx_gnd为所述第二激励信号。
  9. 如权利要求6所述的指纹传感器，其特征在于，所述第一激励信号源包括第一电压源和第二电压源，所述第一电压源用于产生第一电压，所述第二电压源用于产生第二电压，其中，
    所述第一电压源与所述运算放大器的第一输入端相连，所述第二电压源通过串联连接的第二开关和第三开关与所述运算放大器的第二输入端相连，并在所述第二开关和所述第三开关之间形成节点，所述节点与所述检测电极相连。
  10. 如权利要求9所述的指纹传感器，其特征在于，所述检测电压的变化量用如下公式表示：
    Figure PCTCN2017099340-appb-100002
    其中，Tx_in＝Vref2-Vref1，ΔVout为所述检测电压的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电压的差值，ΔCf为所述检测电容的变化量，即有手指触摸感应单元和没有手指触摸感应单元的检测电容的差值，Ci为所述基准电容，Tx_in为所述第一激励信号，Vref1为所述第一电压，Vref2为所述第二电压，Tx_gnd为所述第二激励信号。
  11. 一种终端设备，其特征在于，包括如权利要求1-10中任一项所述的指纹传感器。
PCT/CN2017/099340 2016-08-29 2017-08-28 指纹传感器和终端设备 WO2018041077A1 (zh)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CN201620975816.0U CN206209764U (zh) 2016-08-29 2016-08-29 指纹传感器和终端设备
CN201610754542.7 2016-08-29
CN201620975816.0 2016-08-29
CN201610754542.7A CN106446780B (zh) 2016-08-29 2016-08-29 指纹传感器和终端设备

Publications (1)

Publication Number Publication Date
WO2018041077A1 true WO2018041077A1 (zh) 2018-03-08

Family

ID=61300026

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2017/099340 WO2018041077A1 (zh) 2016-08-29 2017-08-28 指纹传感器和终端设备

Country Status (1)

Country Link
WO (1) WO2018041077A1 (zh)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111353406A (zh) * 2020-02-24 2020-06-30 成都世纪天知科技有限公司 一种无激励信号无boost芯片的指纹传感器采集单元
CN113030621A (zh) * 2021-03-18 2021-06-25 江阴邦融微电子有限公司 具有防干扰功能的指纹传感器测试装置及测试方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW201624345A (zh) * 2014-12-22 2016-07-01 指紋卡公司 具有在感測元件內的解調變電路系統之電容式指紋感測裝置
CN106446780A (zh) * 2016-08-29 2017-02-22 比亚迪股份有限公司 指纹传感器和终端设备
CN206209764U (zh) * 2016-08-29 2017-05-31 比亚迪股份有限公司 指纹传感器和终端设备

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TW201624345A (zh) * 2014-12-22 2016-07-01 指紋卡公司 具有在感測元件內的解調變電路系統之電容式指紋感測裝置
CN106446780A (zh) * 2016-08-29 2017-02-22 比亚迪股份有限公司 指纹传感器和终端设备
CN206209764U (zh) * 2016-08-29 2017-05-31 比亚迪股份有限公司 指纹传感器和终端设备

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111353406A (zh) * 2020-02-24 2020-06-30 成都世纪天知科技有限公司 一种无激励信号无boost芯片的指纹传感器采集单元
CN113030621A (zh) * 2021-03-18 2021-06-25 江阴邦融微电子有限公司 具有防干扰功能的指纹传感器测试装置及测试方法
CN113030621B (zh) * 2021-03-18 2023-10-31 江阴邦融微电子有限公司 具有防干扰功能的指纹传感器测试装置及测试方法

Similar Documents

Publication Publication Date Title
JP6750059B2 (ja) 改良された感知素子を備えた容量指紋センサ
KR101872368B1 (ko) 감지소자에 복조회로를 갖는 정전용량식 지문감지장치
JP6538056B2 (ja) 基準感知素子を備えた指紋感知システムおよび方法
EP3238134B1 (en) Capacitive fingerprint sensor with sensing elements comprising timing circuitry
WO2019144303A1 (zh) 电容检测电路、触控装置和终端设备
US9236861B2 (en) Capacitive proximity sensor with enabled touch detection
US20190005291A1 (en) Capacitive fingerprint sensor
WO2020047844A1 (zh) 电容检测电路、触控芯片及电子设备
TW201604746A (zh) 增加訊號雜訊比之方法及使用其之電容感測器與觸控面板
US9176597B2 (en) Directional capacitive proximity sensor with bootstrapping
CN106446780B (zh) 指纹传感器和终端设备
TW201248475A (en) Capacitance sensing devices and control methods
WO2018041077A1 (zh) 指纹传感器和终端设备
JP2018500052A (ja) 同期信号入力を備える指紋センサ
CN110471578A (zh) 湿度补偿的电容性传感电路
TWI426325B (zh) 影像顯示系統與觸控面板控制方法
US9766759B2 (en) Mutual capacitance touch sensing device and its sine wave measuring method
US11427465B2 (en) Capacitive sensors having temperature stable output
US11126298B2 (en) Touch detection apparatus, touch control apparatus, touch and display driver integration chip, touch control display apparatus, and touch detection and resistance measurement method
JP6513286B2 (ja) 容量性構造体及び容量性構造体を用いて電荷量を特定する方法
WO2022087974A1 (zh) 电容检测电路、触控芯片和电容检测电路的参数调整方法
Schrag et al. Finite element simulations combined with statistical analysis of variance: Exploring the potential of piezoelectric MEMS microphones

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17845379

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17845379

Country of ref document: EP

Kind code of ref document: A1