The present disclosure relates to the technical field of ultrasonic waves, and in particular, to an ultrasonic signal detection circuit, an ultrasonic signal detection method and an ultrasonic detection apparatus.
Ultrasonic signal detection generally adopts a signal integration mode. Specifically, a sensing circuit generates a piezoelectric signal according to a received ultrasonic echo signal and outputs the piezoelectric signal, and the piezoelectric signal is integrated to obtain a corresponding integration voltage which may reflect an intensity of the ultrasonic echo signal.
The present disclosure intends to solve at least one of the technical problems of the prior art, and provides an ultrasonic signal detection circuit, an ultrasonic signal detection method and an ultrasonic detection apparatus.
In a first aspect, an embodiment of the present disclosure provides an ultrasonic signal detection circuit, including: a sensing circuit, a unidirectional conduction circuit and a source follower circuit, wherein the sensing circuit is connected to an input terminal of the source follower circuit through the unidirectional conduction circuit;
In some embodiments, the unidirectional conduction circuit includes a diode; and a first terminal of the diode is connected to the sensing circuit, and a second terminal of the diode is connected to the input terminal of the source follower circuit.
In some embodiments, the source follower circuit includes a first transistor; and
In some embodiments, the unidirectional conduction circuit is configured to allow the forward current portion of the alternating current signal to pass through, the first transistor is an N-type transistor, the first terminal of the diode is a positive terminal, and the second terminal of the diode is a negative terminal; or
In some embodiments, the ultrasonic signal detection circuit further includes a voltage regulation circuit, wherein the voltage regulation circuit is connected to the input terminal of the source follower circuit and a first control signal terminal; and
In some embodiments, the voltage regulation circuit includes a capacitor; and
In some embodiments, the ultrasonic signal detection circuit further includes a switching circuit and a reading signal line, wherein the switching circuit is connected to the output terminal of the source follower circuit and a second control signal terminal; and
In some embodiments, the switching circuit includes a second transistor; and
In some embodiments, the voltage regulation circuit is configured to increase the voltage at the input terminal of the source follower circuit by the 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 a same control signal terminal;
In some embodiments, the ultrasonic signal detection circuit further includes a reset circuit;
In some embodiments, the sensing circuit includes an ultrasonic sensor, a first terminal of the ultrasonic sensor is connected to a second voltage supply terminal, and a second terminal of the ultrasonic sensor is connected to the unidirectional conduction circuit; and
In some embodiments, the unidirectional conduction circuit is configured to allow the forward current portion of the alternating current signal to pass through, the reference voltage is equal to V0; or,
In some embodiments, the second voltage supply terminal is further configured to provide a driving signal to the first terminal of the ultrasonic sensor during an ultrasonic emission phase.
In a second aspect, an embodiment of the present disclosure further provides an ultrasonic detection apparatus, including a carrier structure and the ultrasonic signal detection circuit according to the first aspect above, wherein the ultrasonic signal detection circuit is on the carrier structure.
In a third aspect, an embodiment of the present disclosure further provides an ultrasonic signal detection method, which is based on the ultrasonic signal detection circuit according to the first aspect above, the ultrasonic signal detection method including:
In some embodiments, in the signal acquisition phase, the unidirectional conduction circuit only allows the forward current portion of the alternating current signal to pass through, and between the signal acquisition phase and the output phase, the ultrasonic signal detection method further includes:
In some embodiments, before the signal acquisition phase, the ultrasonic signal detection method further includes:
In order to enable one of ordinary skill in the art to better understand the technical solutions of the present disclosure, an ultrasonic signal detection circuit, an ultrasonic signal detection method and an ultrasonic detection apparatus according to the present disclosure are described in detail below with reference to the accompanying drawings.
In a signal acquisition phase, the driving voltage supply terminal TX supplies a constant voltage (generally, ground voltage Vss) to the driving electrode 101, the ultrasonic sensor 1 receives an ultrasonic echo signal, and outputs a piezoelectric signal through the receiving electrode 103 based on a positive piezoelectric effect. The piezoelectric signal is an alternating current signal, the time (duration) of a forward current portion (component) and the time of a reverse current portion of the alternating current signal are substantially equal, and the alternating current signal is generally a sine wave signal or an approximate sine wave signal. The alternating current signal output by the receiving electrode 103 changes a voltage at the gate electrode of the transistor T2. Specifically, the forward current portion of the alternating current signal may charge the gate electrode of the transistor T2, and the reverse current portion may discharge the gate electrode of the transistor T2. That is, the forward current component may cause an integration voltage to increase, while the reverse current component may cause the integration voltage to decrease.
However, in practical applications, it is found that in the related art, a magnitude of the integration voltage obtained by directly integrating the piezoelectric signal in the interval of [0, T/2] is not great enough, and a signal quantity of a detection signal (transmitted from a reading signal line RL) output by the ultrasonic signal detection circuit based on the integration voltage is still small, so that it is difficult to accurately determine the intensity of the ultrasonic echo signal. In addition, only the portion of the ultrasonic echo signal corresponding to T/2 is used, and thus, the utilization rate is low.
In order to solve at least one technical problem in the related art, an embodiment of the present disclosure provide a corresponding solution.
The sensing circuit 2 is configured to generate a piezoelectric signal according to a received ultrasonic echo signal, and output the piezoelectric signal to the unidirectional conduction circuit 3, where the piezoelectric signal is an alternating current signal.
The unidirectional conduction circuit 3 is configured to rectify the alternating current signal to allow only a forward current portion or a reverse current portion of the alternating current signal to pass through, the forward current portion may charge the input terminal of the source follower circuit 4 after passing through the unidirectional conduction circuit 3, and the reverse current portion may discharge the input terminal of the source follower circuit 4 after passing through the unidirectional conduction circuit 3.
The source follower circuit 4 is configured to generate a detection signal according to a voltage at the input terminal thereof and output the detection signal through an output terminal thereof.
Similarly, in a case where the unidirectional conduction circuit 3 only allows the reverse current portion of the alternating current signal to pass through, the integration voltage (negative voltage) at the input terminal of the source follower circuit 4 decreases in a step-like manner with the increase of the integration time, and the magnitude of the integration voltage increases in a step-like manner, so that the utilization rate of the ultrasonic echo signal can be effectively improved, and the signal quantity of the finally output detection signal can be improved.
In some embodiments, the unidirectional conduction circuit 3 is configured to allow the forward current portion of the alternating current signal to pass through, the first transistor M1 is an N-type transistor, the first terminal of the diode PD is a positive terminal, and the second terminal of the diode PD is a negative terminal.
In a case where the unidirectional conduction circuit 3 is configured to allow the reverse current portion of the alternating current signal to pass through, the voltage regulation circuit 5 is configured to decrease the voltage at the input terminal of the source follower circuit 4 by the preset voltage value in response to the control of the first control signal provided by the first control signal terminal CS1.
In some embodiments, the voltage regulation 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 the first control signal terminal CS1. The first control signal provided by the first control signal terminal CS1 may jump between a preset high level voltage and a preset low level voltage (a voltage difference between the high level voltage and the low level voltage is equal to the preset voltage value), so as to increase or decrease the voltage at the input terminal of the source follower circuit 4 by the preset voltage value through a bootstrap action of the capacitor C.
In some embodiments, the ultrasonic signal detection circuit further includes a switching circuit 6 and a reading 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 scan control signal terminal, and the switching circuit 6 is configured to control an electric connection/disconnection between the output terminal OUT of the source follower circuit 4 and the reading signal line RL in response to a control of a scan control signal provided by the scan control signal terminal.
In some embodiments, the voltage regulation circuit 5 is configured to increase the voltage at the input terminal of the source follower circuit 4 by the 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 forward current portion of the alternating current signal to pass through). The second transistor M2 is an N-type transistor. The first control signal terminal CS1 and the second control signal terminal CS2 are a same control signal terminal. The preset voltage value is equal to a voltage difference between a high level voltage and a low level voltage of the second control signal.
In the embodiments shown in
Referring to
In some embodiments, the reset circuit 7 includes a third transistor M3, A gate electrode of the third transistor M3 is connected to the reset control signal terminal RST, a first electrode of the third transistor M3 is connected to the input terminal of the source follower circuit 4, and a second electrode of the third transistor M3 is connected to the reset voltage supply terminal.
Referring to
Alternatively, the ultrasonic sensor 1 includes: a driving electrode 101, a piezoelectric material layer 102, and a receiving electrode 103. The driving electrode 101 serves as the first terminal of the ultrasonic sensor 1, and the receiving electrode serves as the second terminal of the ultrasonic sensor 1. The operation principle of the ultrasonic sensor 1 is as follows:
In an ultrasonic emission phase, a driving signal (for example, a sine wave signal) may be applied to the driving electrode 101, and a constant voltage is applied to the receiving electrode 103, so that an inverse piezoelectric effect occurs in the piezoelectric material layer 102 due to a voltage excitation, which causes the piezoelectric material layer 102 to emit an ultrasonic wave. The emitted ultrasonic wave is reflected when contacting an object (for example, a finger), and an ultrasonic echo wave is generated. A distance between the object and the ultrasonic sensor 1 varies, so that the vibration intensity of the ultrasonic echo wave generated by reflection varies (a frequency of the ultrasonic echo wave is the same as or substantially the same as a frequency of the ultrasonic wave emitted in the emission phase). In the signal acquisition phase, the driving signal is stopped being applied to the driving electrode 101, and the constant voltage (for example, the reference voltage provided by the second voltage supply terminal IN2) is applied to the driving electrode 101, and the constant voltage is stopped being applied to the receiving electrode 103, so that the piezoelectric material layer 102 is affected by the ultrasonic echo wave, and a piezoelectric signal (an alternating current signal, specifically a sine wave signal or an approximate sine wave signal) is generated, at the receiving electrode 103 due to a positive piezoelectric effect.
In some embodiments, a piezoelectric material of the piezoelectric material layer 102 includes polyvinylidene fluoride (PVDF). The polyvinylidene fluoride has advantages of difficult breakage, waterproofness, capability of being continuously drawn in large quantities, low price, wide frequency response range and the like. It should be noted that the piezoelectric material of the piezoelectric material layer 102 may be a piezoelectric single crystal, a piezoelectric ceramic, or the like. The piezoelectric single crystal may include, for example, quartz (SiO2), lithium niobate (LiNbO3), or the like. The piezoelectric ceramic may include, for example, barium titanate (BaTiO3), lead zirconate titanate (Pb(ZritxTix)O3), or the like.
In some embodiments, the unidirectional conduction circuit 3 is configured to allow the forward current portion of the alternating current signal to pass through, and the reference voltage is equal to V0. Alternatively, the unidirectional conduction circuit 3 is configured to allow the reverse current portion of the alternating current signal to pass through, and the reference voltage is equal to −V0. V0 is a forward conduction voltage drop of the unidirectional conduction circuit 3, and V0 is greater than 0.
In some embodiments, the second voltage supply terminal IN2 is further configured to provide a driving signal to the first terminal of the ultrasonic sensor 1 during the ultrasonic emission phase.
The operation procedure of the ultrasonic signal detection circuit shown in FIG. will be described in detail below by taking the ultrasonic signal detection circuit shown in
In an ultrasonic emission phase (also referred to as a reset phase), the second voltage supply terminal IN2 supplies a driving signal (a sine wave signal, 4 cycles are exemplarily shown), the reset control signal terminal RST supplies a high level voltage, and the second control signal terminal CS2 supplies a low level voltage.
When the reset control signal is in a high level state, the third transistor M3 is turned on, and the reset voltage Vrst (generally, having the magnitude of OV) is written into a node N1 to reset the input terminal of the source follower circuit 4, and a node N2 is discharged through the node N1. The diode PD has a forward conduction voltage drop, so that a voltage at the node N2 is maintained at V0. That is, a constant voltage is applied to the receiving electrode 103 in the ultrasonic sensor 1. The ultrasonic sensor 1 transmits ultrasonic waves outward under the action of the driving signal and the constant voltage.
In a 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.
The reset control signal is in a low level state, and the third transistor M3 is turned off. The sensing circuit 2 receives the ultrasonic echo signal and outputs a corresponding piezoelectric signal to the node N2, where the piezoelectric signal is an alternating current signal, and a voltage corresponding to the forward current portion of the alternating current signal is greater than VU, and a voltage corresponding to the reverse current portion of the alternating current signal is less than V0. The unidirectional conduction circuit 3 (diode PD) rectifies the alternating current signal to allow only the forward current portion to pass through, and the voltage at the node increases in a step-like manner. At the end of the signal acquisition phase, the integration voltage at the node N1 is denoted as V1.
It should be noted that in an embodiment of the present disclosure, a duration of the signal acquisition phase is determined by a duration that the second voltage supply terminal IN2 provides the reference voltage VU.
In a 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 changed from a low level voltage to a high level voltage.
The voltage at the second terminal of the capacitor C is changed from a low level voltage to a high level voltage, that is, is increased by a preset voltage value ΔV. Under the bootstrap action of the capacitor C, the voltage at the node N1 is also increased by the preset voltage value ΔV, that is, the voltage at the node N1 is V1+ΔV, so that the magnitude of the integration voltage is increased, the first transistor M1 may operate in an amplification state in an output phase, thereby increasing the signal quantity of the finally output detection signal.
In 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.
Since the second control signal terminal CS2 is in a high level state, the second transistor M2 is turned on. Accordingly, the first transistor M1 is also turned on, and the first transistor M1 outputs a corresponding detection signal according to the voltage at the node N1, the detection signal is transmitted to the reading signal line RI, through the second transistor M2 for further processing.
It should be noted that the operation process of the ultrasonic signal detection circuit shown in
It should be noted that it is only exemplary that the processing circuit includes the current-voltage conversion circuit 8 and the signal amplification circuit 9 in an embodiment of the present disclosure. In practical applications, other circuits having corresponding functions are further provided according to actual needs.
Based on the same inventive concept, an embodiment of the present disclosure further provides an ultrasonic detection apparatus, wherein the ultrasonic detection apparatus includes a carrier structure and an ultrasonic signal detection circuit located on the carrier structure, and the ultrasonic signal detection circuit may be the ultrasonic signal detection circuit according to the above embodiments.
As an alternative embodiment, the ultrasonic signal detection circuit may be applied to fingerprint recognition. More specifically, the ultrasonic detection apparatus is a display panel having an ultrasonic detection function, from which fingerprint recognition may be implemented in the display panel. In this case, the carrier structure may be a display panel, and the ultrasonic signal detection circuit may be disposed outside the display panel or may be integrated inside the display panel.
The display panel may be applied to any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop, a digital photo frame, a navigator and the like.
Alternatively, the ultrasonic signal detection circuit of the present disclosure may also be applied to other ultrasonic applications such as ultrasonic space positioning, ultrasonic medical treatment and the like. Accordingly, the ultrasonic detection apparatus may be specifically an ultrasonic space positioning apparatus, an ultrasonic medical apparatus, or the like.
It should be noted that different structural features in the ultrasonic signal detection circuit according to the above embodiments may be combined with each other, and the ultrasonic signal detection circuit obtained by combining the structural features also falls within the protection scope of the present disclosure.
Based on the same inventive concept, an embodiment of the present disclosure also provides an ultrasonic signal detection method, which is based on the ultrasonic signal detection circuit according to the above embodiments. The following description will be made with reference to the accompanying drawings.
Step S101, in a signal acquisition phase, a sensing circuit generates a piezoelectric signal according to a received ultrasonic echo signal and outputs the piezoelectric signal to a unidirectional conduction circuit, and the unidirectional conduction circuit rectifies an alternating current signal so as to only allow a forward current portion or a reverse current portion of the alternating current signal to pass through.
Step S102, in an output phase, the source follower circuit 4 generates a detection signal according to a voltage at an input terminal thereof, and outputs the detection signal through an output terminal thereof.
For the specific description of the step S101 and the step S102, reference may be made to corresponding contents in the foregoing embodiments, and details are not repeated here,
Step S201, in a reset phase, the reset circuit writes a reset voltage provided by a reset voltage supply terminal to the input terminal of the source follower circuit in response to a control of a reset control signal provided by a reset control signal terminal.
Step S202, in a signal acquisition phase, the sensing circuit generates a piezoelectric signal according to the received ultrasonic echo signal and outputs the piezoelectric signal to the unidirectional conduction circuit.
Step S203, in a voltage regulation phase, the voltage regulation circuit regulates the voltage at the input terminal of the source follower circuit 4 in response to a control of a first control signal provided by a first control signal terminal.
If the unidirectional conduction circuit only allows the forward current portion of the alternating current signal to pass through, in step S203, the voltage regulation circuit increases 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.
If the unidirectional conduction circuit only allows the reverse current portion of the alternating current signal to pass through, in step S203, the voltage regulation circuit decreases the voltage at the input terminal of the source follower circuit 4 by the preset voltage value in response to the control of the first control signal provided by the first control signal terminal.
Step S204, in an output phase, the source follower circuit 4 generates a detection signal according to the voltage at the input terminal thereof, and outputs the detection signal through an output terminal thereof.
For the specific description of the steps S201 to S204, reference may be made to the corresponding contents in the foregoing embodiments, and details are not repeated here. It should be noted that in some embodiments, the step S201 or the step S203 may not be performed, which also belongs to the protection scope of the present disclosure.
One of ordinary skill in the art should appreciate that the embodiments described in the specification are optional embodiments, and the actions and structures involved are not necessarily required for the claimed invention.
The embodiments in the present specification are all described in a progressive manner, and each embodiment focuses on differences between the embodiment and other embodiments, and portions that are the same and similar among the embodiments may be referred to each other.
Finally, it should further be noted that in this document, relational terms such as “first”, “second”, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the term “comprises” “comprising”, or any other variation thereof, is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element described by the phrase “comprising a . . . ” does not exclude the presence of other like elements in a process, method, article, or apparatus that includes the element.
The above detailed description is provided for the ultrasonic signal detection circuit, the ultrasonic signal detection method and the ultrasonic detection apparatus according to the present disclosure, and the principle and the implementation mode of the present disclosure are explained by applying specific examples, and the description of the above embodiments is only used to understand the method and the core idea of the present disclosure. Meanwhile, for one of ordinary skill in the art, according to the idea of the present disclosure, the specific embodiments and the application range may be changed. In summary, the content of the present specification should not be construed as a limitation to the present disclosure.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/CN2021/095156 | 5/21/2021 | WO |