TWI729639B - High-precision fingerprint sensing method - Google Patents

Abstract

A high-precision fingerprint sensing method includes providing a fingerprint sensor having a plurality of transistor switches, a plurality of sensing electrodes, a plurality of gate lines, a plurality of data lines, arranging at least one sampling conductor near the gate lines to form a coupling capacitance between the sampling conductor and the gate lines and to render the sampling conductor sensing noise on the adjacent gate lines, inverting the noise signal obtained from the sampling conductor into a noise-suppressing signal and sending the noise-suppressing signal to the fingerprint sensor to suppress noise of the fingerprint sensor and enhance fingerprint sensing accuracy.

Description

High accuracy fingerprint detection method

The present invention relates to a fingerprint detection method, and more particularly to a fingerprint detection method that improves accuracy by detecting noise.

Due to the rise of e-commerce and the rapid development of remote payment, the commercial demand for biometrics is rapidly expanding. Based on the requirements of efficiency, safety, and non-invasiveness, fingerprint recognition has become the preferred technology of biometrics. Fingerprint recognition technology can be divided into optical, thermal, ultrasonic, and capacitive. Among them, capacitive technology stands out due to comprehensive considerations such as device size, cost, power saving, reliability, and anti-counterfeiting.

The large-area push-type finger identification device has been the first choice for the identification of financial payment and administrative operations. However, the chip-type all-finger fingerprint sensor is expensive and easy to pressure loss. Therefore, the use of thin-film transistor technology to produce all-finger fingerprint sensors outside the chip has become the development trend of large-area fingerprint detection. However, problems such as huge noise and internal capacitance characteristics of thin film transistors have also arisen, especially the gate lines spreading over the sensing area themselves will sense noise from fingers and surroundings, and pass through the interpolar capacitance of each transistor. It is also cross-connected to each sensing electrode, causing noise to flow around and it is difficult to correctly distinguish fingerprint signals.

Therefore, enterprises in the industry need a low-cost, high-performance, low-noise, high-accuracy fingerprint detection method, which can overcome the huge noise or interference caused by the interpolar capacitance of the transistor switch to each sensing electrode. The stray capacitance is cross-connected to the huge noise of the fingerprint sensor power conductor, thus greatly improving the signal-to-noise ratio and the accuracy of fingerprint sensing.

In order to solve the above-mentioned problems, the present invention provides a high-accuracy fingerprint detection method, including: setting a fingerprint sensor, the fingerprint sensor includes: a plurality of transistor switches; a plurality of sensing electrodes, each sensing Electrodes are electrically connected to the source or drain of at least two transistor switches; multiple gate lines, each of which is electrically connected to the gates of multiple transistor switches; multiple data lines, each of the data lines Electrically connect the source or drain of a plurality of transistor switches; at least one sampling conductor is arranged adjacent to the gate lines, and a cross-connected capacitance is formed between the sampling conductor and the gate lines, so that the sampling conductor can sense To the noise signals on the adjacent gate lines; set up a fingerprint detection circuit, select at least one of the sensing electrodes through the plurality of gate lines sequentially or randomly for fingerprint sensing operation, and input through the selected data line A fingerprint sensing signal is used for fingerprint detection operation; the noise signal sensed by the sampling conductor is inversely processed into a noise suppression signal and the noise suppression signal is output to the fingerprint sensor to eliminate the fingerprint sensor To improve the accuracy of fingerprint detection.

The high-accuracy fingerprint detection method of the present invention can use the sampling conductor to detect the main noise, and the noise is inversely amplified and applied to the main conductor to eliminate the noise of the fingerprint sensor.

In order to have a better understanding of the technology, means and effects adopted by the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. I believe that the purpose, features and characteristics of the present invention can be obtained from this in depth and For specific understanding, however, the accompanying drawings are only provided for reference and illustration, and are not intended to limit the present invention.

10: Fingerprint sensor

SC: sampling conductor

SE: sensing electrode

C1, C2, CV: Capacitance

20: Fingerprint detection circuit

22: Inverting circuit

VH: Positive pressure terminal

VL: negative pressure side

SW1, SW2: Power switch

VGH, VGL: power supply

Cs, Cs1, Cs2: cross-connect capacitance

C11, C12, C21, C22: Interpolar capacitance

Q1~Q4, Q11, Q12, Q21, Q22, Q31, Q32, Q41, Q42: Transistor switch

GL,R1,R2,GY1,~4,G1,G2,1Y1,1Y2,2Y1,2Y2,3Y3,3Y2,4Y1,4Y2,: gate line

DL,D1,D2,11L1~11L2,12L1~12L2,13L1~13L2...1mlL1~1mL2,1nL1~1nL2,21L1~21L2,22L1~22L2,23L1~23L2...2mlL1~2mL2,2nL1~2nL2, 31L1~31L2,32L1~32L2,33L1~33L2...3mlL1~3mL2,3nL1~3nL2,41L1~41L2,42L1~42L2,43L1~43L2...4mlL1~4mL2,4nL1~4nL2: data line

Vs: pattern induction signal

Vf: Fingerprint signal

24: Amplifier

Fst: finger excitation signal

Vst: electrode excitation signal

Vn: Noise signal

Vc: Noise suppression signal

FIG. 1 is a schematic diagram illustrating the applicable hardware of the high-accuracy fingerprint detection method of the present invention.

FIG. 2 is a schematic diagram illustrating an embodiment of the high-accuracy fingerprint detection method of the present invention.

Fig. 3 is a schematic diagram of a fingerprint sensor according to the present invention.

FIG. 4A illustrates a transistor switch signal control method of the high-accuracy fingerprint detection method of the present invention.

FIG. 4B illustrates another transistor switch signal control method of the high-accuracy fingerprint detection method of the present invention.

FIG. 5 is a schematic diagram illustrating another embodiment of the high-accuracy fingerprint detection method of the present invention.

6 is a schematic diagram illustrating yet another embodiment of the high-accuracy fingerprint detection method of the present invention.

FIG. 7 is a schematic diagram illustrating yet another embodiment of the high-accuracy fingerprint detection method of the present invention.

FIG. 8A is a schematic diagram illustrating yet another embodiment of the high-accuracy fingerprint detection method of the present invention.

FIG. 8B is a schematic diagram illustrating yet another embodiment of the high-accuracy fingerprint detection method of the present invention.

9A is a schematic diagram illustrating yet another embodiment of the high-accuracy fingerprint detection method of the present invention.

FIG. 9B is a schematic diagram illustrating yet another embodiment of the high-accuracy fingerprint detection method of the present invention.

The technical content and detailed description of the present invention are described as follows in conjunction with the drawings: Refer to FIG. 3, which is a schematic diagram of the fingerprint sensor 10 according to the present invention. The fingerprint sensor 10 includes multiple regions. Although the illustrated example shows four regions, the illustrated example is not a limitation of the present invention. Each area contains multiple sensing electrodes (no figure numbers are added, see below for details), and each sensing electrode is equipped with two transistor switches (depending on the design situation, more transistor switches can be configured, so the electrical The crystal switch configuration is for illustrative purposes only and is not a limitation of the present invention) for sensing switching and auxiliary application of noise suppression signals. As shown in FIG. 3, the fingerprint sensor of the present invention can be divided into four areas, for example. Take area 1 as an example. Area 1 further includes multiple gate lines 1Y1, 1Y2, 2Y1,2Y2, 3Y3, 3Y2, 4Y1, 4Y2 and multiple data lines 11L1~11L2, 12L1~12L2, 13L1~13L2...1m1L1 ~1mL2,1nL1~1nL2, where m=n-1. With the above-mentioned wiring method, the fingerprint sensor 10 can control the closing and conducting of the gate of the first row through the gate lines 1Y1, 1Y2, and transmit data to the two electrodes of the first row of sensing electrodes through the data lines 11L1~11L2. The crystal switch can sequentially or randomly select at least one sensing electrode through the plurality of gate lines for fingerprint sensing operation, and input a fingerprint sensing signal through the selected data line for fingerprint sensing operation. The connection mode of the gate line and the data line in the remaining areas, and the control of the transistor switch can be deduced by analogy. In the present invention, by arranging at least two transistor switches on each sensing electrode, the sensing electrode can be defined as "selected sensing electrode" and "non-selected sensing electrode"; and for non-selected sensing The electrode is controlled by a transistor switch to apply a noise suppression signal (details will be described later).

1, in order to illustrate a schematic diagram of the hardware applicable to the high-accuracy fingerprint detection method of the present invention, according to the method of the present invention, a sampling conductor SC is arranged in the fingerprint sensor 10, and the sampling conductor SC is adjacent to the electrical The gate line GL of the crystal switch. Although FIG. 1 only shows one sampling conductor SC, according to one implementation of the present invention, there may be multiple sampling conductors SC; according to another implementation of the present invention, the multiple sampling conductors are elongated and connected to the gate. The polar lines are arranged in parallel; according to another possible implementation of the present invention, the size of the sampling conductor SC is 10-100 times or larger than that of a single sensing electrode, which is sufficient to sense noise. Furthermore, a cross-connected capacitance Cs is formed between the sampling conductor SC and the gate lines GL, so that the sampling conductor SC can sense the noise signal Vn on the adjacent gate lines GL. The noise signal Vn is sent to an inverting circuit (inverting amplifier circuit) 22 of the fingerprint detection circuit 20 to be further inverted and amplified into a noise suppression signal Vc. The fingerprint detection circuit 20 then sends the noise suppression signal Vc to part or all of the non-selected sensing electrodes of the fingerprint sensor 10 (details will be described later) or a common point to eliminate the fingerprint sensing The noise of the device and improve the accuracy of fingerprint detection. In the fingerprint sensor 10, the gate lines throughout the sensing area can sense noise from the finger and the surroundings, and are connected to each sensing electrode through the interpolar capacitance of each transistor switch, causing noise everywhere. It is difficult to distinguish fingerprint signals correctly. In the present invention, the most important noise signal can be inverted, and then transmitted to some or all of the non-selected sensing electrodes or a common point, so as to eliminate the noise of the fingerprint sensor And improve the accuracy of fingerprint detection. In the fingerprint sensor 10, the largest noise source comes from the largest conductors, such as non-selected sensing electrodes (because each sensing only selects a small part of the total number of sensing electrodes for detection, the non-selected sensing The measuring electrode occupies a considerable area) or the power terminal conductor, so if the noise source of this conductor can be eliminated, the accuracy of fingerprint detection can be improved.

According to an implementation manner of the present invention, the inverter circuit 22 is an inverting amplifier circuit with a programmable gain value to perform inversion processing of the noise signal. According to another possible implementation manner of the present invention, the gain value (increase or decrease the gain value) of the inverting amplifier circuit can be successively adjusted during the fingerprint sensing operation to obtain the best noise suppression effect. Furthermore, as shown in Figure 1, this fingerprint The detection circuit 20 also controls a plurality of transistor switches in the fingerprint sensor 10 through the data line DL and the gate line GL (see the transistor switches in FIG. 3).

Referring to FIG. 2, it is a schematic diagram to further illustrate an embodiment of the high-accuracy fingerprint detection method of the present invention. Referring to the above description of FIG. 1, after the sampling conductor SC is arranged near the gate line GL of the transistor switch, a cross-connected capacitance Cs is formed between the sampling conductor SC and the gate line GL, and the sampling conductor SC can sense these adjacent The noise signal Vn on the gate line is sent to an inverting circuit 22 of the fingerprint detection circuit 20 to be further inverted and amplified into a noise suppression signal Vc. As described above, if the noise suppression signal Vc is transmitted to some or all of the non-selected sensing electrodes or a common point, the noise of the fingerprint sensor can be eliminated to improve the accuracy of fingerprint detection. In the embodiment of FIG. 2, the fingerprint detection circuit 20 sends the noise suppression signal Vc to the DC power supply terminal of the fingerprint sensor 10 (for example, the negative voltage terminal VL of the DC power supply) to eliminate the fingerprint sensing The noise of the device and improve the accuracy of fingerprint detection. In this embodiment, the fingerprint detection circuit 20 further includes power switching switches SW1, SW2, which disconnect the electrical connections between the power supplies VGH, VGL and the fingerprint sensor 10 (that is, the power switching switch SW1, SW2 is cut off) to prevent power noise from affecting the accuracy of fingerprint detection. At this time, the power of the fingerprint sensor 10 is supplied by the capacitor CV (through the positive voltage terminal VH and the negative voltage terminal VL). It should be noted that the embodiment of FIG. 2 is only an example, and is not a limitation of the scope of the patent of the present invention.

Refer to FIG. 4A to illustrate a transistor switch signal control method of the high-accuracy fingerprint detection method of the present invention; refer to FIG. 4B to illustrate another transistor switch signal control method of the high-accuracy fingerprint detection method of the present invention. As shown in Figure 4A, when the sensing electrode SE is selected for fingerprint detection operation, the signal of the gate line GY1 is in a logic high state, the transistor switch Q1 is turned on, and the electrode excitation signal can be transmitted through the signal line S1 and the transistor switch Q1 To the sensing electrode SE; at the same time, the fingerprint sensing signal sensed on the sensing electrode SE is input to the reading circuit through the transistor switch Q1 and the signal line S1. At this time, the gate lines GY2 and GY3 are in a logic low state. When the sensor electrode SE is not selected for fingerprint detection operation, the signals of the gate lines GY1 and GY2 are in the logic low state and the signal of the gate line GY3 is in the logic high state, the transistor switch Q3 is turned on, The signal line R1 and the transistor switch Q3 transmit a specific DC or AC suppression signal to the non-selected sensing electrode SE; or when the non-selected sensing electrode SE performs a fingerprint detection operation, the signals of the gate lines GY1 and GY3 It is a logic low state and the gate line GY2 is a logic high state, the transistor switch Q2 is turned on, and another specific DC or AC suppression signal can be transmitted to the non-selected sensing electrode SE via the signal line R2 and the transistor switch Q2. In this way, it is possible to prevent the unselected sensing electrode SE from floating and contributing to noise.

Referring to Figure 4B, if the transistor switches Q1 and Q2 are complementary transistors, for example, the transistor switch Q1 is a PMOS transistor, and the transistor switch Q2 is an NMOS transistor (or vice versa), one gate line can be omitted , And achieve the same function as the circuit of Figure 4A. For example, when the sensing electrode SE is selected for fingerprint detection operation, when the signal of the gate line GY1 is in a logic high state, the transistor switch Q1 is turned on, and the transistor switch Q2 is turned off, and the electrode excitation signal can pass through the signal line S1 and the transistor switch Q1 is transmitted to the sensing electrode SE; at the same time, the fingerprint sensing signal sensed on the sensing electrode SE is input to the reading circuit through the transistor switch Q1 and the signal line S1. . When the sensor electrode SE is not selected for fingerprint detection operation, the signal of the gate line GY2 is in a logic high state, the transistor switch Q3 is turned on, and the signal of the gate line GY1 is in a logic low state, and the transistor switch Q2 is turned on. A specific DC or AC suppression signal is transmitted to the non-selected sensing electrode SE via the signal line R1, the transistor switch Q3 and the transistor switch Q2; or when the non-selected sensing electrode SE performs a fingerprint detection operation, the gate electrode The signal on the line GY2 is in the logic low state, the transistor switch Q4 is turned on, and the signal on the gate line GY1 is in the logic low state, and the transistor switch Q2 is turned on. The signal line R2 and the transistor switch Q4 and the transistor switch Q2 can be connected A specific DC or AC suppression signal is transmitted to the non-selected sensing electrode SE. As mentioned above, the present invention can utilize complementary transistor switch pairs to save one gate line.

Referring to FIG. 5, it is a schematic diagram illustrating the high-accuracy fingerprint detection method of the present invention, in which the noise suppression signal is applied to the non-selected electrodes. As mentioned above, if the noise suppression signal is transmitted to some or all of the non-selected sensing electrodes or a common point, the fingerprint sensor noise can be eliminated to improve the accuracy of fingerprint detection; This embodiment is to transmit the noise suppression signal to some or all of the non-selected sensing electrodes. However, it should be understood that this embodiment is only an example, and is not a limitation of the scope of the present invention. In the Ming Dynasty, the noise suppression signal can also be transmitted to some non-selected sensing electrodes (or all non-selected sensing electrodes) and a common point (such as the negative voltage terminal VL of the DC power supply shown in FIG. 2) at the same time. As shown in FIG. 5, if the gate line GY3 is in the logic high state and the gate line GY4 is in the logic low state, the transistor switch Q21 is turned on and the transistor switch Q22 is turned off, and the sensing electrode SE1 is the selected sensing electrode at this time. Furthermore, at this time, the gate line GY1 is in a logic low state and the gate line GY2 is in a logic high state, and the transistor switch Q11 is off and the transistor switch Q12 is on. At this time, the sensing electrode SE2 is a non-selected sensing electrode. The electrode excitation signal Vst can be transmitted to the source or drain of the transistor switch Q21 via the switch SW and the signal line S1, and applied to the selected sensing electrode SE1; at the same time, a fingerprint detection signal is read via the signal line S1. Fingerprint detection operation. When detecting the fingerprint sensing signal for the selected sensing electrode SE1, the gate line GY1 is in a logic low state and the gate line GY2 is in a logic high state, and the transistor switch Q11 is turned off and the transistor switch Q12 is turned on. Therefore, the electrode excitation signal Vst will not be transmitted to the non-selected sensing electrode SE2 via the signal line S1 and the transistor switch Q11. Cross-connected capacitors Cs1, Cs2 are formed between the sampling conductor SC and the gate lines GY1, GY2, and after the sampling conductor SC senses the noise signal Vn on the adjacent gate lines, the noise signal Vn is sent to the fingerprint detection An inverting circuit 22 of the measuring circuit 20 is further inverted and amplified into a noise suppression signal Vc. The noise suppression signal Vc is sent to the non-selected sensing electrode SE2 through the signal line R1 and the transistor switch Q12 to overcome the huge noise that is cross-connected to each sensing electrode through the interpolar capacitances C11, C12, C21, and C22 of the transistor switch. And improve the accuracy of fingerprint detection.

Refer to FIG. 6, which is a schematic diagram illustrating the high-accuracy fingerprint detection method of the present invention, in which the noise suppression signal is also applied to the non-selected electrodes. This embodiment is similar to the embodiment in FIG. 5, but in the same way as in FIG. 4B, a complementary transistor switch is used to save the gate line. If the gate line GY1 is in the logic low state and the gate line GY2 is in the logic high state, the transistor switch Q21 is turned on and the transistor switch Q22 is turned off, and the sensing electrode SE1 is the selected sensing electrode at this time. Furthermore, the electrode excitation signal Vst can be transmitted to the source or drain of the transistor switch Q21 via the switch SW and the signal line S1, and applied to the selected sensing electrode SE1. The fingerprint sensing signal can be automatically selected via the amplifier 24. The sensing electrode SE1 reads the fingerprint signal Vf. And here When the transistor switch Q11 is turned off and the transistor switch Q12 is turned on (the gate line GY1 is in a logic low state), the electrode excitation signal Vst will not be transmitted to the source or drain of the transistor switch Q11 via the signal line S1, so it is not Will be transmitted to the non-selected sensing electrode SE2. A cross-connected capacitor Cs is formed between the sampling conductor SC and the gate line GY1. The sampling conductor SC can sense the noise signal Vn on the adjacent gate lines, and the noise signal Vn is sent to the fingerprint detection circuit 20. The phase circuit 22 is further inverted and amplified into a noise suppression signal Vc. The noise suppression signal Vc is sent to the non-selected sensing electrode SE2 through the transistor switch Q12 to overcome the huge noise that is cross-connected to each sensing electrode through the interpolar capacitance C11, C12, C21, C22 of the transistor switch and improve fingerprints. Correctness of detection.

Referring to FIG. 7, in order to illustrate another embodiment of the high-accuracy fingerprint detection method of the present invention, this embodiment uses a complementary transistor switch and electrically connects the source (or drain) of the transistor switch to the gate. In order to further simplify the wiring, that is, save the data line. If the gate line G1 is in the logic high state and the gate line G2 is in the logic low state, and the electrode excitation signal is transmitted through the data line D1 (therefore the data line D2 is in the logic low state), then the sensing electrode SE1 is selected for sensing The other sensing electrodes SE2, SE3, SE4 are non-selected sensing electrodes. Since the source or drain of the transistor switch Q12 is electrically connected to the gate, the gate line G1 can also be used as the data line of the sensing signal to receive the fingerprint sensing signal of the selected sensing electrode SE1. Furthermore, because the gate line G2 is in a logic low state (connected to the negative voltage terminal of the DC power supply), this embodiment may also include the circuit shown in FIG. 2 (the sampling conductor SC and the fingerprint detection circuit 20). Similarly, for the circuit of FIG. 7, the fingerprint detection circuit 20 also processes the noise signal of the sampling conductor SC (near the gate line of the circuit shown in FIG. 7) into a noise suppression signal and supplies it to the negative voltage terminal of the DC power supply. .

For the non-selected sensing electrodes SE3 and SE4, because the gate line G2 is in a logic low state (connected to the negative voltage terminal of the DC power supply), the noise suppression signal transmitted to the negative voltage terminal of the DC power supply can be respectively passed through the transistor switch Q32 And the transistor switch Q42 is transmitted to the non-selected sensing electrodes SE3, SE4 to further eliminate the noise of the fingerprint sensor to improve the accuracy of fingerprint detection. For the non-selected sensing electrode SE2, because the data line D2 is also in a logic low state (connected to the negative voltage terminal of the DC power supply) and is connected to the transistor The source or drain of the body switch Q21. Therefore, the noise suppression signal transmitted to the negative voltage terminal of the DC power supply can also be respectively transmitted to the non-selected sensing electrode SE2 through the transistor switch Q21 to further eliminate the noise of the fingerprint sensor and improve the accuracy of fingerprint detection. Sex.

If the gate line G1 is in the logic high state and the gate line G2 is in the logic low state, and the electrode excitation signal is transmitted through the data line D2 (the data line D1 is in the logic low state), then the sensing electrode SE2 is selected for sensing Electrodes, and the remaining sensing electrodes SE1, SE3, SE4 are non-selected sensing electrodes. If the gate line G1 is in the logic low state and the gate line G2 is in the logic high state, and the electrode excitation signal is transmitted via the data line D1 (therefore the data line D2 is in the logic low state), then the sensing electrode SE3 is selected for sensing Electrodes, and the remaining sensing electrodes SE1, SE2, SE4 are non-selected sensing electrodes. If the gate line G1 is in the logic low state and the gate line G2 is in the logic high state, and the electrode excitation signal is transmitted through the data line D2 (the data line D1 is in the logic low state), then the sensing electrode SE4 is selected for sensing Electrodes, and the remaining sensing electrodes SE1, SE2, SE3 are non-selected sensing electrodes. In the above three states, regarding the application of the electrode excitation signal, the reading of the induction signal and the application of the noise suppression signal, you can also refer to the operation mode of the first state. The embodiment of FIG. 7 can provide the noise suppression signal to the negative voltage terminal of the DC power supply and the non-selected sensing electrode at the same time while saving the gate line and the data line.

Referring to FIG. 8A, in order to illustrate another embodiment of the high-accuracy fingerprint detection method of the present invention, this embodiment can be combined with the embodiments of FIGS. 1-7 and is a self-capacitance architecture. As shown in this figure, the electrode excitation signal Vst is applied to a selected sensing electrode SE3, and the fingerprint sensing signal Vs is read by the selected sensing electrode SE3 therefrom and processed into a fingerprint signal Vf by the amplifier 24. Similarly, the noise suppression signal can be applied to some non-selected sensing electrodes (such as the sensing electrode SE1) or all non-selected sensing electrodes to eliminate the noise of the fingerprint sensor and improve fingerprint detection. The correctness of the test.

Referring to FIG. 8B, in order to illustrate another embodiment of the high-accuracy fingerprint detection method of the present invention, this embodiment can be combined with the embodiments of FIGS. 1-7 and has a self-capacitance/mutual-capacitance hybrid architecture. In addition to applying the electrode excitation signal Vst and providing a sampling conductor to provide a noise suppression signal, the implementation in FIG. 8B The example further provides a finger excitation signal Fst, and the finger excitation signal Fst is applied to the non-selected sensing electrode. For example, in the embodiment of FIG. 8B, the sensing electrode SE3 is the selected sensing electrode, the finger excitation signal Fst can be applied to all non-selected sensing electrodes or some non-selected sensing electrodes (for example, the sensing electrode SE1). The finger excitation signal Fst causes an inductive capacitance Cfs1 to be generated between the operating finger and the non-selected sensing electrode SE1. The relationship between the finger excitation signal Fst and the electrode excitation signal Vst is in-phase, reverse phase, out-of-phase, same-frequency or different-frequency signals, so as to eliminate the noise of the fingerprint sensor and further improve the accuracy of fingerprint detection. Sex.

Referring to FIG. 9A, in order to illustrate another embodiment of the high-accuracy fingerprint detection method of the present invention, this embodiment can be combined with the embodiments of FIGS. 1-7 and is a mutual capacitance structure. In addition to providing a sampling conductor to provide a noise suppression signal, the embodiment in FIG. 9A further provides a finger excitation signal Fst, and the finger excitation signal Fst is applied to the user's operating finger via a cross-connected conductor LC. A cross-connected impedance Z is formed between the operating finger and the cross-connected conductor LC. The cross-connected impedance Z is a capacitive impedance (for example, the cross-connected conductor LC touches the operating finger through an insulating layer) or a resistive impedance (for example, the cross-connected conductor LC is a contact line or It is to touch the pressure ring so that the operating finger can directly touch). During the fingerprint sensing operation, a finger excitation signal Fst is transmitted to the operating finger via the cross-connect conductor LC; the fingerprint sensing signal Vs is read by the selected sensing electrode SE3 and processed by the amplifier 24 into a fingerprint signal Vf. Similarly, the noise suppression signal can be applied to some non-selected sensing electrodes (such as sensing electrode SE1) or all non-selected sensing electrodes, which can eliminate the noise of the fingerprint sensor to improve fingerprint detection. The correctness of the test. The relationship between the finger excitation signal Fst and the electrode excitation signal Vst is in-phase, reverse phase, out-of-phase, same-frequency or different-frequency signals, so as to eliminate the noise of the fingerprint sensor and further improve the accuracy of fingerprint detection. Sex. In the embodiment of FIG. 9A, the cross-connected conductor LC is a contact pressure wire, a contact pressure ring, an electrode or a sensing electrode.

Referring to FIG. 9B, in order to illustrate another embodiment of the high-accuracy fingerprint detection method of the present invention, this embodiment can be combined with the embodiments of FIGS. 1-7 and has a self-capacitance/mutual-capacitance hybrid architecture. In addition to applying the electrode excitation signal Vst and providing a noise suppression signal by providing a sampling conductor, the embodiment of FIG. 9B further provides a finger excitation signal Fst, and the finger excitation signal Fst is applied through a cross-connect conductor LC On the user's finger. A cross-connected impedance is formed between the operating finger and the cross-connected conductor, and the cross-connected impedance is a capacitive impedance or a resistive impedance. During fingerprint sensing, the electrode excitation signal Vst is applied to a selected sensing electrode SE3, and thereafter the selected sensing electrode SE3 reads the fingerprint sensing signal Vs and is processed by the amplifier 24 into a fingerprint signal Vf. Similarly, the noise suppression signal can be applied to some non-selected sensing electrodes (such as sensing electrode SE1) or all non-selected sensing electrodes, which can eliminate the noise of the fingerprint sensor to improve fingerprint detection. The correctness of the test. In addition, during the fingerprint sensing operation, a finger excitation signal Fst is transmitted to the operating finger via the cross-connected conductor LC. The relationship between the finger excitation signal Fst and the electrode excitation signal Vst is in-phase, reverse phase, out-of-phase, same-frequency or Different frequency signals can further improve the accuracy of fingerprint detection in addition to eliminating the noise of the fingerprint sensor. Similarly, in the embodiment of FIG. 9B, the cross-connected conductor LC is a contact pressure wire, a contact pressure ring, an electrode or a sensing electrode.

In summary, the high-accuracy fingerprint detection method of the present invention can use sampling conductors to detect the main noise, and the noise is inverted and amplified before being applied to the main conductor (such as non-selected sensing electrodes or DC power supply). End) to eliminate the noise of the fingerprint sensor.

Furthermore, the present invention also provides a finger excitation signal, which has a phase or frequency relationship with the electrode excitation signal, so as to further improve the accuracy of fingerprint detection.

However, the above are only detailed descriptions and drawings of the preferred embodiments of the present invention. However, the characteristics of the present invention are not limited to these, and are not intended to limit the present invention. The full scope of the present invention should be referred to the following application The scope of the patent shall prevail. All embodiments that conform to the spirit of the scope of the patent application of the present invention and similar variations should be included in the scope of the present invention. Anyone familiar with the art in the field of the present invention can easily think of it. Changes or modifications can be covered in the following patent scope of this case.

10: Fingerprint sensor

SC: sampling conductor

SE: sensing electrode

C1, C2: Capacitance

20: Fingerprint detection circuit

22: Inverting circuit

DL: Data line

GL: Gate line

Claims (15)

A fingerprint detection method with high accuracy, comprising: setting a fingerprint sensor, the fingerprint sensor comprising: a plurality of transistor switches; a plurality of sensing electrodes, each sensing electrode is electrically connected to at least two transistors The source or drain of the switch; multiple gate lines, each of which is electrically connected to the gates of multiple transistor switches; multiple data lines, each of which is electrically connected to multiple of the transistor switches The source or the drain; at least one sampling conductor is arranged adjacent to the gate lines, and a cross-connected capacitance is formed between the sampling conductor and the gate lines, so that the sampling conductor can sense the adjacent gates Noise signal on the line; set up a fingerprint detection circuit, select at least one of the sensing electrodes through the multiple gate lines for fingerprint sensing operation sequentially or randomly, and input a fingerprint sensing signal through the selected data line for fingerprint sensing Detection operation; inverting the noise signal sensed by the sampling conductor into a noise suppression signal and outputting the noise suppression signal to the fingerprint sensor to eliminate the noise of the fingerprint sensor to improve The correctness of fingerprint detection; wherein the noise suppression signal is transmitted to the non-selected sensing electrode via other data lines and corresponding transistor switches of other sensing electrodes to improve the accuracy of fingerprint detection. The high-accuracy fingerprint detection method according to claim 1, wherein the noise suppression signal is output to the DC power terminal of the fingerprint sensor. The high-accuracy fingerprint detection method according to claim 2, wherein the noise suppression signal is output to the negative voltage terminal of the DC power supply of the fingerprint sensor. The high-accuracy fingerprint detection method according to claim 1, wherein each of the sensing electrodes is electrically connected to the source or the drain of two transistor switches, and the source or drain of one of the transistor switches is The pole is electrically connected to the gate. The high-accuracy fingerprint detection method according to claim 1, wherein the fingerprint detection circuit further includes a power switch, which is turned off during the fingerprint detection operation. The high-accuracy fingerprint detection method described in claim 1 further includes providing a cross-connected conductor to form a cross-connected impedance between the operating finger and the cross-connected conductor, and the cross-connected impedance is a capacitive impedance or a resistive impedance. The high-accuracy fingerprint detection method according to claim 6, wherein a finger excitation signal is transmitted to the operating finger via the cross-linked impedance during the fingerprint sensing operation. The high-accuracy fingerprint detection method according to claim 7, wherein during the fingerprint sensing operation, an electrode excitation signal is transmitted to the selected sensing electrode via the selected data line. The high-accuracy fingerprint detection method according to claim 8, wherein the relationship between the finger excitation signal and the electrode excitation signal is in-phase, anti-phase, out-of-phase, same-frequency or different-frequency signals. The high-accuracy fingerprint detection method according to claim 6, wherein the cross-connected conductor is a contact pressure wire, a contact pressure ring, an electrode or a sensing electrode. The high-accuracy fingerprint detection method according to claim 1, wherein an electrode excitation signal is transmitted to the selected sensing electrode via the selected data line during the fingerprint sensing operation. The high-accuracy fingerprint detection method according to claim 1, wherein the noise suppression signal can suppress noise on the wire connected to the gate connected to the sensing electrode via the interpolar capacitance of the transistor switch, thereby improving fingerprints Correctness of sensing. The high-accuracy fingerprint detection method according to claim 1, wherein the plurality of sampling conductors are elongated and arranged in parallel with the gate lines. The high-accuracy fingerprint detection method according to claim 1, wherein an inversion circuit with a programmable gain value is used to perform the inversion processing of the noise. The high-accuracy fingerprint detection method according to claim 14, wherein the gain value of the inverter circuit is successively adjusted during the fingerprint sensing operation to increase or decrease the gain value to obtain the best noise suppression effect.

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