Ultrasonic signal detection circuit, detection method, and ultrasonic detection device
Patent Information
- Application Number
- CN202180001241.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-05-21
- Publication Date
- 2026-09-18
- Estimated Expiration
- 2041-05-21
Smart Images
Figure CN115812192B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultrasonic technology, and in particular to an ultrasonic signal detection circuit, detection method, and ultrasonic detection equipment. Background Technology
[0002] Ultrasonic signal detection generally employs signal integration, as follows: The sensing circuit generates and outputs a corresponding piezoelectric signal based on the received ultrasonic echo signal. By integrating the piezoelectric signal, a corresponding integrated voltage is obtained, which reflects the intensity of the ultrasonic echo signal. Summary of the Invention
[0003] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes an ultrasonic signal detection circuit, detection method and ultrasonic detection equipment.
[0004] In a first aspect, embodiments of the present invention provide an ultrasonic signal detection circuit, comprising: a sensing circuit, a unidirectional conduction circuit, and a source follower circuit, wherein the sensing circuit is connected to the input terminal of the source follower circuit through the unidirectional conduction circuit;
[0005] The sensing circuit is configured to generate a corresponding piezoelectric signal based on the received ultrasonic echo signal, and output the piezoelectric signal to the unidirectional conduction circuit, wherein the piezoelectric signal is an AC signal;
[0006] The unidirectional conduction circuit is configured to rectify the AC signal so that only the positive current portion or the negative current portion of the AC signal can pass through. The positive current portion can charge the input terminal of the source follower circuit after passing through the unidirectional conduction circuit, and the negative current portion can discharge the input terminal of the source follower circuit after passing through the unidirectional conduction circuit.
[0007] The source follower circuit is configured to generate a corresponding detection signal based on the voltage at its input terminal and output the detection signal through its output terminal.
[0008] In some embodiments, the unidirectional conduction circuit includes: a diode;
[0009] The first end of the diode is connected to the sensing circuit, and the second end of the diode is connected to the input end of the source follower circuit.
[0010] In some embodiments, the source follower circuit includes: a first transistor;
[0011] The gate of the first transistor is connected to the input terminal of the source follower circuit, the first terminal of the first transistor is connected to the first voltage supply terminal, and the second terminal of the second transistor is connected to the output terminal of the source follower circuit.
[0012] In some embodiments, the unidirectional conduction circuit is configured to allow a portion of the positive current in the AC signal to pass through, the first transistor is an N-type transistor, the first terminal of the diode is the positive terminal, and the second terminal of the diode is the negative terminal;
[0013] Alternatively, the unidirectional conduction circuit is configured to allow the negative current portion of the AC signal to pass through, wherein the first transistor is a P-type transistor, the first terminal of the diode is the negative terminal, and the second terminal of the diode is the positive terminal.
[0014] In some embodiments, the ultrasonic signal detection circuit further includes a voltage regulation circuit, which is connected to the input terminal and the first control signal terminal of the source follower circuit.
[0015] The unidirectional conduction circuit is configured to allow the positive current portion of the AC signal to pass through, and the voltage regulation circuit is configured to increase the voltage at the input terminal of the source follower circuit by a preset voltage value in response to the control of the first control signal provided by the first control signal terminal.
[0016] Alternatively, the unidirectional conduction circuit is configured to allow the negative current portion of the AC signal to pass through, and the voltage regulation circuit is configured to reduce the voltage at the input of the source follower circuit by a preset voltage value in response to the control of the first control signal provided by the first control signal terminal.
[0017] In some embodiments, the voltage regulating circuit includes: a capacitor;
[0018] The first end of the capacitor is connected to the input terminal of the source follower circuit, and the second end of the capacitor is connected to the first control signal terminal.
[0019] In some embodiments, the ultrasonic signal detection circuit further includes: a switching circuit and a readout signal line, wherein the switching circuit is connected to the output terminal of the source follower circuit and the second control signal terminal, respectively;
[0020] The switching circuit is connected to the scan control signal terminal, and the switching circuit is configured to control the connection and disconnection between the output terminal of the source follower circuit and the read signal line in response to the scan control signal provided by the scan control signal terminal.
[0021] In some embodiments, the switching circuit includes: a second transistor;
[0022] The gate of the second transistor is connected to the second control signal terminal, the first terminal of the second transistor is connected to the output terminal of the source follower circuit, and the second terminal of the second transistor is connected to the read signal line.
[0023] In some embodiments, the voltage regulating circuit is configured to increase the voltage at the input terminal of the source follower circuit by a preset voltage value in response to the control of the first control signal, the second transistor is an N-type transistor, and the first control signal terminal and the second control signal terminal are the same control signal terminal;
[0024] Alternatively, the voltage regulating circuit is configured to reduce the voltage at the input terminal of the source follower circuit by a preset voltage value in response to the control of the first control signal, wherein the second transistor is a P-type transistor, and the first control signal terminal and the second control signal terminal are the same control signal terminal;
[0025] The preset voltage value is equal to the voltage difference between the high-level voltage and the low-level voltage in the second control signal.
[0026] In some embodiments, the ultrasonic signal detection circuit further includes a reset circuit;
[0027] The reset circuit is connected to the input terminal, reset voltage supply terminal, and reset control signal terminal of the source follower circuit. The reset circuit is configured to write the reset voltage provided by the reset voltage supply terminal to the input terminal of the source follower voltage in response to the reset control signal provided by the reset control signal terminal.
[0028] In some embodiments, the reset circuit includes: a third transistor;
[0029] The gate of the third transistor is connected to the reset control signal terminal, the first terminal of the third transistor is connected to the input terminal of the source follower circuit, and the second terminal of the third transistor is connected to the reset voltage supply terminal.
[0030] In some embodiments, the sensing circuit includes: an ultrasonic sensor, a first end of which is connected to a second voltage supply terminal, and a second end of which is connected to the unidirectional conduction circuit;
[0031] The second voltage supply terminal is configured to provide a reference voltage to the first terminal of the ultrasonic sensor during the signal acquisition phase.
[0032] In some embodiments, the unidirectional conduction circuit is configured to allow a positive current portion of the AC signal to pass through, and the reference voltage is equal to V0;
[0033] The unidirectional conduction circuit is configured to allow the negative current portion of the AC signal to pass through, and the reference voltage is equal to -VO;
[0034] Wherein, VO is the forward conduction voltage drop of the unidirectional conduction circuit, and V0 > 0.
[0035] In some embodiments, the second voltage supply terminal is further configured to provide a drive signal to the first terminal of the ultrasonic sensor during the ultrasonic emission phase.
[0036] Secondly, embodiments of the present invention also provide an ultrasonic testing device, comprising: a support structure and an ultrasonic signal detection circuit as described in the first aspect above, wherein the ultrasonic signal detection circuit is located on the support structure.
[0037] Thirdly, embodiments of the present invention also provide an ultrasonic signal detection method, wherein the ultrasonic signal detection method is based on the ultrasonic signal detection circuit provided in the first aspect above, and the ultrasonic signal detection method includes:
[0038] During the signal acquisition phase, the sensing circuit generates a corresponding piezoelectric signal based on the received ultrasonic echo signal and outputs the piezoelectric signal to the unidirectional conduction circuit. The unidirectional conduction circuit rectifies the AC signal to allow only the positive or negative current portion of the AC signal to pass through.
[0039] During the output phase, the source follower circuit generates a corresponding detection signal based on the voltage at its input terminal and outputs the detection signal through its output terminal.
[0040] In some embodiments, during the signal acquisition phase, the unidirectional conduction circuit only allows the positive current portion of the AC signal to pass through, and the signal acquisition phase and the output phase further include:
[0041] During the voltage regulation phase, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and increases the voltage at the input terminal of the source follower circuit by a preset voltage value.
[0042] Alternatively, during the signal acquisition phase, the unidirectional conduction circuit only allows the negative current portion of the AC signal to pass through, and the signal acquisition phase and the output phase further include:
[0043] During the voltage regulation phase, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and reduces the voltage at the input terminal of the source follower circuit by a preset voltage value.
[0044] In some embodiments, the method further includes the following steps prior to the signal acquisition phase:
[0045] During the reset phase, the reset circuit responds to the reset control signal provided by the reset control signal terminal and writes the reset voltage provided by the reset voltage supply terminal to the input terminal of the source follower voltage. Attached Figure Description
[0046] Figure 1 This is a schematic diagram of the circuit structure of an ultrasonic signal detection circuit involved in related technologies;
[0047] Figure 2 for Figure 1 The diagram shows a timing sequence of an ultrasonic signal detection circuit.
[0048] Figure 3 This is a schematic diagram illustrating how the integral voltage changes as the integration time increases in related technologies.
[0049] Figure 4 This is a schematic diagram of a circuit structure for an ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0050] Figure 5 This is a schematic diagram illustrating how the integral voltage changes accordingly as the integration time increases, according to an embodiment of the present invention.
[0051] Figure 6 A schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0052] Figure 7 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0053] Figure 8 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0054] Figure 9 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0055] Figure 10 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0056] Figure 11 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0057] Figure 12 for Figure 10 The diagram shows a timing sequence of an ultrasonic signal detection circuit.
[0058] Figure 13 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention;
[0059] Figure 14 A flowchart of an ultrasonic signal detection method provided in an embodiment of the present invention;
[0060] Figure 15A flowchart of another ultrasonic signal detection method provided in an embodiment of the present invention. Detailed Implementation
[0061] To enable those skilled in the art to better understand the technical solution of the present invention, the following detailed description of an ultrasonic signal detection circuit, detection method, and ultrasonic detection device provided by the present invention is provided in conjunction with the accompanying drawings.
[0062] Figure 1 This is a schematic diagram of the circuit structure of an ultrasonic signal detection circuit involved in related technologies. Figure 2 for Figure 1 The diagram shown is a timing diagram of an ultrasonic signal detection circuit. Figure 1 and Figure 2 As shown, the ultrasonic signal detection circuit in the related technology includes three transistors T1, T2, and T3, and an ultrasonic sensor 1. The ultrasonic sensor 1 includes a driving electrode 101, a piezoelectric material layer 102, and a receiving electrode 103. The driving electrode 101 is connected to the driving voltage supply terminal TX, and the receiving electrode 103 is connected to the gate of transistor T2. Transistor T1 is controlled by the signal terminal RST, and transistor T3 is controlled by the signal terminal Gate.
[0063] During the signal acquisition phase, the driving voltage supply terminal TX provides a constant voltage (generally the ground voltage Vss) to the driving electrode 101. The ultrasonic sensor 1 receives the ultrasonic echo signal and, based on the positive piezoelectric effect, outputs a piezoelectric signal through the receiving electrode 103. This piezoelectric signal is an AC signal, in which the positive current portion and the negative current portion have approximately equal durations. This AC signal is generally a sine wave signal or approximately a sine wave signal. The AC signal output by the receiving electrode 103 causes a change in the gate voltage of the transistor T2. Specifically, the positive current portion of the AC signal charges the gate of the transistor T2, while the negative current portion discharges the gate of the transistor T2. That is, the positive current portion increases the integrated voltage, and the negative current portion decreases the integrated voltage.
[0064] Figure 3 This is a schematic diagram illustrating how the integral voltage changes with increasing integration time in related technologies, such as... Figure 3 As shown, the integration time is described in detail in the interval [0, T]. When the integration time is in the interval [0, T / 2], the integrated voltage gradually increases, and when the integration time is in the interval (T / 2, T], the integrated voltage gradually decreases, where T is the period of the piezoelectric signal output by ultrasonic sensor 1 (also the period of the ultrasonic echo signal). Based on the above, the integration time is often set to T / 2 to obtain the maximum integrated voltage. The change of the integrated voltage at node NO can be found in [reference]. Figure 3 As shown in the image.
[0065] However, in practical applications, it has been found that the voltage of the integrated voltage obtained by directly integrating the piezoelectric signal in the [0, T / 2] interval is not large enough. The signal quantity of the detection signal (transmitted outward by the reading signal line RL) output by the ultrasonic signal detection circuit based on the integrated voltage is still small, making it difficult to accurately determine the intensity of the ultrasonic echo signal. In addition, only the T / 2 portion of the ultrasonic echo signal is utilized, resulting in a low utilization rate.
[0066] To address at least one of the technical problems existing in the related technologies, embodiments of the present invention provide corresponding solutions.
[0067] Figure 4 This is a schematic diagram of a circuit structure for an ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the ultrasonic signal detection circuit includes: a sensing circuit 2, a one-way conduction circuit 3, and a source follower circuit 4. The sensing circuit 2 is connected to the input terminal of the source follower circuit 4 through the one-way conduction circuit 3.
[0068] The sensing circuit 2 is configured to generate a corresponding piezoelectric signal based on the received ultrasonic echo signal and output the piezoelectric signal to the unidirectional conduction circuit 3. The piezoelectric signal is an AC signal.
[0069] The unidirectional conduction circuit 3 is configured to rectify the AC signal so that only the positive current portion or the negative current portion of the AC signal can pass through. After the positive current portion passes through the unidirectional conduction circuit 3, it can charge the input terminal of the source follower circuit 4, and after the negative current portion passes through the unidirectional conduction circuit 3, it can discharge the input terminal of the source follower circuit 4.
[0070] The source follower circuit 4 is configured to generate a corresponding detection signal based on the voltage at its own input terminal and output the detection signal through its own output terminal.
[0071] Figure 5 This is a schematic diagram illustrating how the integral voltage changes accordingly with the increase of the integration time in an embodiment of the present invention, such as... Figure 5 As shown, taking the case where the unidirectional conduction circuit 3 only allows the positive current portion of the AC signal to flow as an example, the signal output by the unidirectional conduction circuit 3 is an intermittent DC signal. As the integration time increases, the integrated voltage (positive voltage) at the input terminal of the source follower circuit 4 increases in a stepwise manner. Therefore, the integration time set in the ultrasonic signal detection circuit provided by the embodiment of the present invention is no longer limited to T / 2, but can be greater than T / 2, for example, it can be 2T, 3T, 4T or even longer. At this time, a larger integrated voltage can be obtained, thereby effectively improving the utilization rate of the ultrasonic echo signal and increasing the signal quantity of the final output detection signal.
[0072] Similarly, when the unidirectional conduction circuit 3 only allows the negative current portion of the AC signal to flow, as the integration time increases, the integrated voltage (negative voltage) at the input terminal of the source follower circuit 4 decreases in a stepwise manner, and the magnitude of the integrated voltage increases in a stepwise manner, thereby effectively improving the utilization rate of the ultrasonic echo signal and increasing the signal quantity of the final output detection signal.
[0073] Figure 6 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 6 As shown, in some embodiments, the unidirectional conduction circuit 3 includes a diode PD; the first end of the diode PD is connected to the sensing circuit 2, and the second end of the diode PD is connected to the input end of the source follower circuit 4.
[0074] Figure 7 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 7 As shown, in some embodiments, the source follower circuit 4 includes: a first transistor M1; the gate of the first transistor M1 is connected to the input terminal of the source follower circuit 4, the first terminal of the first transistor M1 is connected to the first voltage supply terminal IN1, and the second terminal of the second transistor M2 is connected to the output terminal OUT of the source follower circuit 4.
[0075] In some embodiments, the unidirectional conduction circuit 3 is configured to allow the positive current portion of the AC signal to pass through, the first transistor M1 is an N-type transistor, the first terminal of the diode PD is the positive terminal, and the second terminal of the diode PD is the negative terminal.
[0076] Figure 8 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 8 As shown, with Figure 7 The situations shown are different. Figure 8 The unidirectional conduction circuit 3 is configured to allow the negative current portion of the AC signal to pass through. The first transistor M1 is a P-type transistor, the first terminal of the diode PD is the negative terminal, and the second terminal of the diode PD is the positive terminal.
[0077] Figure 9 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 9 As shown, in some embodiments, the ultrasonic signal detection circuit further includes a voltage regulation circuit 5, which is connected to the input terminal of the source follower circuit 4 and the first control signal terminal CS1.
[0078] When the unidirectional conduction circuit 3 is configured to allow the positive current portion of the AC signal to pass through, the voltage regulating circuit 5 is configured to increase the voltage at the input terminal of the source follower circuit 4 by a preset voltage value in response to the control of the first control signal provided by the first control signal terminal CS1.
[0079] When the unidirectional conduction circuit 3 is configured to allow the negative current portion of the AC signal to pass through, the voltage regulation circuit 5 is configured to reduce the voltage at the input terminal of the source follower circuit 4 by a preset voltage value in response to the control of the first control signal provided by the first control signal terminal CS1.
[0080] In some embodiments, the voltage regulating circuit 5 includes a capacitor C; a first terminal of the capacitor C is connected to the input terminal of the source follower circuit 4, and a second terminal of the capacitor C is connected to a first control signal terminal CS1. The first control signal provided by the first control signal terminal CS1 can jump between a preset high-level voltage and a preset low-level voltage (the voltage difference between the high-level voltage and the low-level voltage is equal to the preset voltage value). Through the bootstrap effect of the capacitor C, the voltage at the input terminal of the source follower circuit 4 is increased by the preset voltage value or decreased by the preset voltage value.
[0081] In some embodiments, the ultrasonic signal detection circuit further includes: a switching circuit 6 and a readout signal line RL. The switching circuit 6 is connected to the output terminal OUT of the source follower circuit 4 and the second control signal terminal CS2, respectively. The switching circuit 6 is connected to a scanning control signal terminal and is configured to control the connection and disconnection between the output terminal OUT of the source follower circuit 4 and the readout signal line RL in response to the control of the scanning control signal provided by the scanning control signal terminal.
[0082] Figure 10 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 10 As shown, in some embodiments, the switching circuit 6 includes: a second transistor M2; the gate of the second transistor M2 is connected to the second control signal terminal CS2, the first terminal of the second transistor M2 is connected to the output terminal of the source follower circuit 4, and the second terminal of the second transistor M2 is connected to the read signal line RL.
[0083] In some embodiments, the voltage regulating circuit 5 is configured to increase the voltage at the input terminal of the source follower circuit 4 by a preset voltage value in response to the control of the first control signal (i.e., the unidirectional conduction circuit 3 is configured to allow the positive current portion of the AC signal to pass through), the second transistor M2 is an N-type transistor, and the first control signal terminal CS1 and the second control signal terminal CS2 are the same control signal terminal; wherein, the preset voltage value is equal to the voltage difference between the high-level voltage and the low-level voltage in the second control signal.
[0084] Figure 11This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 11 As shown, with Figure 10 The situations shown are different. Figure 11 The voltage regulating circuit 5 is configured to reduce the voltage at the input terminal of the source follower circuit 4 by a preset voltage value in response to the control of the first control signal (i.e., the unidirectional conduction circuit 3 is configured to allow the negative current portion of the AC signal to pass through). The second transistor M2 is a P-type transistor. The first control signal terminal CS1 and the second control signal terminal CS2 are the same control signal terminal. The preset voltage value is equal to the voltage difference between the high-level voltage and the low-level voltage in the second control signal.
[0085] exist Figure 10 and Figure 11 In the embodiment shown, the first control signal terminal CS1 and the second control signal terminal CS2 are the same control signal terminal, which can effectively reduce the number of control signal terminals and simplify the circuit structure.
[0086] See Figure 4 , Figures 6 to 11 As shown, in some embodiments, the ultrasonic signal detection circuit further includes a reset circuit 7; the reset circuit 7 is connected to the input terminal, the reset voltage supply terminal, and the reset control signal terminal RST of the source follower circuit 4, and the reset circuit 7 is configured to write the reset voltage provided by the reset voltage supply terminal Vrst to the input terminal of the source follower voltage in response to the control of the reset control signal provided by the reset control signal terminal RST.
[0087] In some embodiments, the reset circuit 7 includes: a third transistor M3; the gate of the third transistor M3 is connected to the reset control signal terminal RST, the first terminal of the third transistor M3 is connected to the input terminal of the source follower circuit 4, and the second terminal of the third transistor M3 is connected to the reset voltage supply terminal.
[0088] See Figure 4 , Figures 6 to 11 As shown, in some embodiments, the sensing circuit 2 includes: an ultrasonic sensor 1, a first end of which is connected to a second voltage supply terminal IN2, and a second end of which is connected to a unidirectional conduction circuit 3; the second voltage supply terminal IN2 is configured to provide a reference voltage to the first end of the ultrasonic sensor 1 during the signal acquisition phase.
[0089] Optionally, the ultrasonic sensor 1 includes a driving electrode 101, a piezoelectric material layer 102, and a receiving electrode 103, wherein the driving electrode 101 serves as the first terminal of the ultrasonic sensor 1, and the received voltage serves as the second terminal of the ultrasonic sensor 1. The working principle of the ultrasonic sensor 1 is as follows:
[0090] During the ultrasonic wave emission phase, a driving signal (e.g., a sinusoidal signal) can be applied to the driving electrode 101, while a constant voltage is applied to the receiving electrode 103. The piezoelectric material layer 102, excited by the voltage, generates an inverse piezoelectric effect, emitting ultrasonic waves. When the emitted ultrasonic waves come into contact with an object (e.g., a finger), they are reflected, generating ultrasonic echoes. The distance between the object and the ultrasonic sensor 1 varies, resulting in differences in the vibration intensity of the reflected ultrasonic echoes (the frequency of the ultrasonic echoes is the same as or substantially the same as the frequency of the ultrasonic waves emitted during the emission phase). During the signal acquisition phase, the driving signal is stopped from being applied to the driving electrode 101, and a constant voltage (e.g., a reference voltage provided by the second voltage supply terminal IN2) is applied instead. The constant voltage applied to the receiving electrode 103 is also stopped. Influenced by the ultrasonic echoes, the piezoelectric material layer 102 generates a piezoelectric signal (an AC signal, specifically a sinusoidal or approximately sinusoidal signal) on the receiving electrode 103 due to the positive piezoelectric effect.
[0091] In some embodiments, the piezoelectric material in the piezoelectric material layer 102 includes polyvinylidene fluoride (PVDF). PVDF has advantages such as being resistant to breakage, waterproof, capable of being produced in large quantities continuously, inexpensive, and having a wide frequency response range. It should be noted that the piezoelectric material in the piezoelectric material layer 102 can also be a piezoelectric single crystal, piezoelectric ceramic, etc. Piezoelectric single crystals may include, for example, quartz (SiO2), lithium niobate (LiNbO3), etc., and piezoelectric ceramics may include, for example, barium titanate (BaTiO3), lead zirconate titanate (Pb(Zr11xTix)O3), etc.
[0092] In some embodiments, the unidirectional conduction circuit 3 is configured to allow the positive current portion of the AC signal to pass through, with a reference voltage equal to V0; the unidirectional conduction circuit 3 is configured to allow the negative current portion of the AC signal to pass through, with a reference voltage equal to -VO; wherein, VO is the forward conduction voltage drop of the unidirectional conduction circuit 3, and V0 > 0.
[0093] In some embodiments, the second voltage supply terminal IN2 is further configured to provide a drive signal to the first terminal of the ultrasonic sensor 1 during the ultrasonic emission phase.
[0094] The following will be based on Figure 10 Taking the ultrasonic signal detection circuit shown as an example, we will use it to... Figure 10 The working process of the ultrasonic signal detection circuit shown is described in detail. Figure 10 The third transistor M3 inside is an N-type transistor, and the first voltage supply terminal IN1 provides the power supply voltage VDD.
[0095] Figure 12 for Figure 10 The diagram shown is a timing diagram of an ultrasonic signal detection circuit. Figure 12As shown, the operation of this ultrasonic signal detection circuit can specifically include the following stages:
[0096] During the ultrasonic wave transmission phase (also the reset phase), the second voltage supply terminal IN2 provides a drive signal (sine wave signal, 4 cycles are shown in the figure as an example), the reset control signal terminal RST provides a high-level voltage, and the second control signal terminal CS2 provides a low-level voltage.
[0097] When the reset control signal is at a high level, the third transistor M3 is turned on, and the reset voltage Vrst (typically 0V) is written to node N1 to reset the input of the source follower circuit 4. At the same time, node N2 discharges through node N1. Since diode PD has a forward voltage drop, the voltage at node N2 is maintained at V0, which can be regarded as applying a constant voltage to the receiving electrode 103 inside the ultrasonic sensor 1. Under the action of the drive signal and the constant voltage, the ultrasonic sensor 1 sends out ultrasonic waves.
[0098] During the signal acquisition phase, the second voltage supply terminal IN2 provides the reference voltage V0, the reset control signal terminal RST provides a low-level voltage, and the second control signal terminal CS2 provides a low-level voltage.
[0099] When the reset control signal is low, the third transistor M3 is off. Sensing circuit 2 receives the ultrasonic echo signal and outputs a corresponding piezoelectric signal to node N2. The piezoelectric signal is an AC signal, and the voltage corresponding to the positive current portion of the AC signal is greater than V0, while the voltage corresponding to the negative current portion is less than V0. The unidirectional conduction circuit 3 (diode PD) rectifies the AC signal so that only the positive current portion passes through, causing the voltage at node N1 to rise in a step-like manner. At the end of the signal acquisition phase, the integrated voltage at node N1 is recorded as V1.
[0100] It should be noted that, in this embodiment of the invention, the duration of the signal acquisition phase is determined by the duration for which the second voltage supply terminal IN2 provides the reference voltage V0. Figure 12 The illustration only shows a case where the duration of the signal acquisition phase is 4 ultrasonic echo signal cycles. This case is merely illustrative and does not limit the technical solution of the present invention.
[0101] During the voltage regulation phase, the second voltage supply terminal IN2 provides a low-level voltage (generally ground voltage), the reset control signal terminal RST provides a low-level voltage, and the voltage provided by the second control signal terminal CS2 is modulated from a low-level voltage to a high-level voltage.
[0102] The voltage at the second terminal of capacitor C is modulated from a low level voltage to a high level voltage, that is, the preset voltage value ΔV is increased. Under the bootstrap effect of capacitor C, the voltage at node N1 will also increase by the preset voltage value ΔV, that is, the voltage at node N1 is V1+ΔV, thereby realizing the voltage magnitude of the integral voltage. This allows the first transistor M1 to work in the amplification state during the output stage, which is beneficial to improving the signal quantity of the final output detection signal.
[0103] During the output phase, the second voltage supply terminal IN2 provides a low-level voltage (generally ground voltage), the reset control signal terminal RST provides a low-level voltage, and the second control signal terminal CS2 provides a high-level voltage.
[0104] Since the second control signal terminal CS2 is in a high-level state, the second transistor M2 is turned on; correspondingly, the first transistor M1 is also turned on. The first transistor M1 outputs a corresponding detection signal according to the voltage at node N1. This detection signal is transmitted to the read signal line RL through the second transistor M2 for further processing.
[0105] It should be noted that, Figure 11 The working process of the ultrasonic signal detection circuit shown is as follows: Figure 10 The operation of the ultrasonic signal detection circuit shown is similar, wherein in the signal acquisition stage... Figure 11 The voltage at node N1 in the ultrasonic signal detection circuit shown will decrease in a step-like manner during the voltage regulation stage. Figure 11 The voltage at node N1 in the ultrasonic signal detection circuit shown will drop by a preset voltage value ΔV. The specific working process will not be described here.
[0106] Figure 13 This is a schematic diagram of another circuit structure of the ultrasonic signal detection circuit provided in an embodiment of the present invention, as shown below. Figure 13 As shown, unlike the previous embodiments, Figure 13 The illustrated embodiment also includes a circuit for further processing the detection signal. This processing circuit can be used to further process the detection signal for subsequent acquisition. In some embodiments, this processing circuit may include a current-to-voltage conversion circuit 8, a signal amplification circuit 9, etc. The current-to-voltage conversion circuit 8 performs current-to-voltage conversion processing on the detection signal, and the signal amplification circuit 9 amplifies the detection signal after the current-to-voltage conversion processing. The present invention does not limit the specific circuit structure of the current-to-voltage conversion circuit 8 and the signal amplification circuit 9.
[0107] It should be noted that the processing circuit in this embodiment of the invention, which includes the current-to-voltage conversion circuit 8 and the signal amplification circuit 9, is only for illustrative purposes. In actual applications, other circuits with corresponding functions may be set according to actual needs.
[0108] Based on the same inventive concept, this invention also provides an ultrasonic testing device, which includes a support structure and an ultrasonic signal detection circuit. The ultrasonic signal detection circuit is located on the support structure and can be the ultrasonic signal detection circuit provided in the above embodiments.
[0109] As an alternative implementation, the ultrasonic signal detection circuit can be applied to fingerprint recognition. More specifically, the ultrasonic detection device is a display panel with ultrasonic detection function, which enables fingerprint recognition. In this case, the supporting structure can be the display panel, and the ultrasonic signal detection circuit can be located on the outside of the display panel or integrated inside the display panel.
[0110] The display panel can be used in any product or component with a display function, such as mobile phones, tablets, televisions, monitors, laptops, digital photo frames, and navigators.
[0111] Of course, the ultrasonic signal detection circuit in this invention can also be applied to other ultrasonic applications, such as ultrasonic spatial positioning and ultrasonic medical treatment; correspondingly, the ultrasonic detection equipment can specifically be ultrasonic spatial positioning equipment, ultrasonic medical equipment, etc.
[0112] It should be noted that the different structural features within the ultrasonic signal detection circuits provided in the above embodiments can be combined with each other, and the ultrasonic signal detection circuits obtained by such combinations should also fall within the protection scope of this invention.
[0113] Based on the same inventive concept, embodiments of the present invention also provide an ultrasonic signal detection method, which is based on the ultrasonic signal detection circuit provided in the above embodiments. The following description is in conjunction with the accompanying drawings.
[0114] Figure 14 A flowchart of an ultrasonic signal detection method provided in an embodiment of the present invention is shown below. Figure 14 As shown, the ultrasonic signal detection method includes:
[0115] Step S101: In the signal acquisition stage, the sensing circuit generates a corresponding piezoelectric signal based on the received ultrasonic echo signal and outputs the piezoelectric signal to the unidirectional conduction circuit. The unidirectional conduction circuit rectifies the AC signal so that only the positive current part or the negative current part of the AC signal is allowed to pass through.
[0116] Step S102: In the output stage, the source follower circuit 4 generates a corresponding detection signal based on the voltage at its own input terminal and outputs the detection signal through its own output terminal.
[0117] For a detailed description of steps S101 and S102 above, please refer to the corresponding content in the previous embodiments, which will not be repeated here.
[0118] Figure 15 A flowchart of another ultrasonic signal detection method provided in an embodiment of the present invention is shown below. Figure 15 As shown, the ultrasonic signal detection circuit includes not only a sensing circuit, a unidirectional conduction circuit, and a source follower circuit 4, but also a reset circuit and a voltage regulation circuit. This ultrasonic signal detection method includes:
[0119] Step S201: During the reset phase, the reset circuit responds to the reset control signal provided by the reset control signal terminal and writes the reset voltage provided by the reset voltage supply terminal to the input terminal of the source follower voltage.
[0120] Step S202: In the signal acquisition stage, the sensing circuit generates a corresponding piezoelectric signal based on the received ultrasonic echo signal and outputs the piezoelectric signal to the unidirectional conduction circuit.
[0121] Step S203: During the voltage regulation stage, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and adjusts the voltage at the input terminal of the source follower circuit 4.
[0122] If the unidirectional conduction circuit only allows the positive current portion of the AC signal to pass through, then in step S203, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and increases the voltage at the input terminal of the source follower circuit 4 by a preset voltage value.
[0123] If the unidirectional conduction circuit only allows the negative current portion of the AC signal to pass through, then in step S203, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and reduces the voltage at the input terminal of the source follower circuit 4 by a preset voltage value.
[0124] Step S204: In the output stage, the source follower circuit 4 generates a corresponding detection signal based on the voltage at its own input terminal and outputs the detection signal through its own output terminal.
[0125] For a detailed description of steps S201 to S204 above, please refer to the corresponding content in the previous embodiments, which will not be repeated here. It should be noted that in some embodiments, step S201 or step S203 may not be performed, and such technical solutions should also fall within the protection scope of this invention.
[0126] Those skilled in the art should understand that the embodiments described in the specification are all optional embodiments, and the actions and structures involved are not necessarily essential to the present invention.
[0127] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0128] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0129] The ultrasonic signal detection circuit, detection method, and ultrasonic detection device provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.
Claims
1. An ultrasonic signal detection circuit, wherein, include: The system includes a sensing circuit, a one-way conduction circuit, and a source follower circuit, wherein the sensing circuit is connected to the input terminal of the source follower circuit through the one-way conduction circuit. The sensing circuit is configured to generate a corresponding piezoelectric signal based on the received ultrasonic echo signal, and output the piezoelectric signal to the unidirectional conduction circuit, wherein the piezoelectric signal is an AC signal; The unidirectional conduction circuit is configured to rectify the AC signal so that only the positive current portion or the negative current portion of the AC signal can pass through. The positive current portion can charge the input terminal of the source follower circuit after passing through the unidirectional conduction circuit, and the negative current portion can discharge the input terminal of the source follower circuit after passing through the unidirectional conduction circuit. The source follower circuit is configured to generate a corresponding detection signal based on the voltage at its own input terminal, and output the detection signal through its own output terminal. The ultrasonic sensor includes: a driving electrode, a piezoelectric material layer, and a receiving electrode, wherein the driving electrode serves as the first end of the ultrasonic sensor, and the receiving voltage serves as the second end of the ultrasonic sensor; During the ultrasonic wave emission phase, a driving signal is applied to the driving electrode, and a constant voltage is applied to the receiving electrode, so that the piezoelectric material layer generates an inverse piezoelectric effect due to voltage excitation and emits ultrasonic waves outward. During the signal acquisition phase, the driving signal is stopped from being applied to the driving electrode and a constant voltage is applied instead. The constant voltage is also stopped from being applied to the receiving electrode, so that the piezoelectric material layer is affected by the ultrasonic echo and generates a positive piezoelectric effect, thus generating a piezoelectric signal on the receiving electrode.
2. The ultrasonic signal detection circuit according to claim 1, wherein, The unidirectional conduction circuit includes: a diode; The first end of the diode is connected to the sensing circuit, and the second end of the diode is connected to the input end of the source follower circuit.
3. The ultrasonic signal detection circuit according to claim 2, wherein, The source follower circuit includes: a first transistor; The gate of the first transistor is connected to the input terminal of the source follower circuit, the first terminal of the first transistor is connected to the first voltage supply terminal, and the second terminal of the second transistor is connected to the output terminal of the source follower circuit.
4. The ultrasonic signal detection circuit according to claim 3, wherein, The unidirectional conduction circuit is configured to allow the positive current portion of the AC signal to pass through, the first transistor is an N-type transistor, the first terminal of the diode is the positive terminal, and the second terminal of the diode is the negative terminal; Alternatively, the unidirectional conduction circuit is configured to allow the negative current portion of the AC signal to pass through, wherein the first transistor is a P-type transistor, the first terminal of the diode is the negative terminal, and the second terminal of the diode is the positive terminal.
5. The ultrasonic signal detection circuit according to claim 1, wherein, Also includes: A voltage regulating circuit is connected to the input terminal and the first control signal terminal of the source follower circuit; The unidirectional conduction circuit is configured to allow the positive current portion of the AC signal to pass through, and the voltage regulation circuit is configured to increase the voltage at the input terminal of the source follower circuit by a preset voltage value in response to the control of the first control signal provided by the first control signal terminal. Alternatively, the unidirectional conduction circuit is configured to allow the negative current portion of the AC signal to pass through, and the voltage regulation circuit is configured to reduce the voltage at the input of the source follower circuit by a preset voltage value in response to the control of the first control signal provided by the first control signal terminal.
6. The ultrasonic signal detection circuit according to claim 5, wherein, The voltage regulating circuit includes: a capacitor; The first end of the capacitor is connected to the input terminal of the source follower circuit, and the second end of the capacitor is connected to the first control signal terminal.
7. The ultrasonic signal detection circuit according to any one of claims 5 or 6, wherein, Also includes: A switching circuit and a read signal line are provided, wherein the switching circuit is connected to the output terminal and the second control signal terminal of the source follower circuit, respectively. The switching circuit is connected to the scan control signal terminal, and the switching circuit is configured to control the connection and disconnection between the output terminal of the source follower circuit and the read signal line in response to the scan control signal provided by the scan control signal terminal.
8. The ultrasonic signal detection circuit according to claim 7, wherein, The switching circuit includes: a second transistor; The gate of the second transistor is connected to the second control signal terminal, the first terminal of the second transistor is connected to the output terminal of the source follower circuit, and the second terminal of the second transistor is connected to the read signal line.
9. The ultrasonic signal detection circuit according to claim 8, wherein, The voltage regulating circuit is configured to increase the voltage at the input terminal of the source follower circuit by a preset voltage value in response to the control of the first control signal. The second transistor is an N-type transistor, and the first control signal terminal and the second control signal terminal are the same control signal terminal. Alternatively, the voltage regulating circuit is configured to reduce the voltage at the input terminal of the source follower circuit by a preset voltage value in response to the control of the first control signal, wherein the second transistor is a P-type transistor, and the first control signal terminal and the second control signal terminal are the same control signal terminal; The preset voltage value is equal to the voltage difference between the high-level voltage and the low-level voltage in the second control signal.
10. The ultrasonic signal detection circuit according to claim 1, wherein, Also includes: Reset circuit; The reset circuit is connected to the input terminal, reset voltage supply terminal, and reset control signal terminal of the source follower circuit. The reset circuit is configured to write the reset voltage provided by the reset voltage supply terminal to the input terminal of the source follower voltage in response to the reset control signal provided by the reset control signal terminal.
11. The ultrasonic signal detection circuit according to claim 10, wherein, The reset circuit includes: a third transistor; The gate of the third transistor is connected to the reset control signal terminal, the first terminal of the third transistor is connected to the input terminal of the source follower circuit, and the second terminal of the third transistor is connected to the reset voltage supply terminal.
12. The ultrasonic signal detection circuit according to claim 1, wherein, The sensing circuit includes: an ultrasonic sensor, the first end of which is connected to a second voltage supply terminal, and the second end of which is connected to the unidirectional conduction circuit. The second voltage supply terminal is configured to provide a reference voltage to the first terminal of the ultrasonic sensor during the signal acquisition phase.
13. The ultrasonic signal detection circuit according to claim 12, wherein, The unidirectional conduction circuit is configured to allow the positive current portion of the AC signal to pass through, and the reference voltage is equal to V0; The unidirectional conduction circuit is configured to allow the negative current portion of the AC signal to pass through, and the reference voltage is equal to -VO; Wherein, VO is the forward conduction voltage drop of the unidirectional conduction circuit, and V0 > 0.
14. The ultrasonic signal detection circuit according to claim 12, wherein, The second voltage supply terminal is also configured to provide a drive signal to the first terminal of the ultrasonic sensor during the ultrasonic emission phase.
15. An ultrasonic testing device, wherein, include: The support structure and the ultrasonic signal detection circuit as described in any one of claims 1-14, wherein the ultrasonic signal detection circuit is located on the support structure.
16. A method for detecting ultrasonic signals, wherein, The ultrasonic signal detection method is based on any one of the ultrasonic signal detection circuits described in claims 1-14, and the ultrasonic signal detection method includes: During the signal acquisition phase, the sensing circuit generates a corresponding piezoelectric signal based on the received ultrasonic echo signal and outputs the piezoelectric signal to the unidirectional conduction circuit. The unidirectional conduction circuit rectifies the AC signal to allow only the positive or negative current portion of the AC signal to pass through. During the output phase, the source follower circuit generates a corresponding detection signal based on the voltage at its input terminal and outputs the detection signal through its output terminal.
17. The ultrasonic signal detection method according to claim 16, wherein, The ultrasonic signal detection circuit is the ultrasonic signal detection circuit described in claim 5; During the signal acquisition phase, the unidirectional conduction circuit only allows the positive current portion of the AC signal to pass through. Between the signal acquisition phase and the output phase, the circuit also includes: During the voltage regulation phase, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and increases the voltage at the input terminal of the source follower circuit by a preset voltage value. Alternatively, during the signal acquisition phase, the unidirectional conduction circuit only allows the negative current portion of the AC signal to pass through, and the signal acquisition phase and the output phase further include: During the voltage regulation phase, the voltage regulation circuit responds to the control of the first control signal provided by the first control signal terminal and reduces the voltage at the input terminal of the source follower circuit by a preset voltage value.
18. The ultrasonic signal detection method according to claim 16, wherein, The ultrasonic signal detection circuit is the ultrasonic signal detection circuit as described in claim 10, and further includes the following before the signal acquisition stage: During the reset phase, the reset circuit responds to the reset control signal provided by the reset control signal terminal and writes the reset voltage provided by the reset voltage supply terminal to the input terminal of the source follower voltage.
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