CN211436890U

CN211436890U - Ultrasonic drive circuit, fingerprint identification device and electronic equipment

Info

Publication number: CN211436890U
Application number: CN201921600089.XU
Authority: CN
Inventors: 张千; 陈佳兴; 向勇
Original assignee: Chengdu Dachao Technology Co ltd
Current assignee: Chengdu core technology Co.,Ltd.
Priority date: 2019-09-24
Filing date: 2019-09-24
Publication date: 2020-09-08
Anticipated expiration: 2029-09-24

Abstract

The utility model relates to ultrasonic drive technical field, in particular to ultrasonic drive circuit, fingerprint identification device and electronic equipment. Wherein ultrasonic drive circuit, including power supply circuit, drive circuit and resonant circuit, carry out electric connection through drive circuit between power supply circuit and the resonant circuit, wherein resonant circuit includes inductance and ultrasonic emission component, inductance one end and drive circuit electric connection, the other end and ultrasonic emission component electric connection, ultrasonic emission component is the ultrasonic emission component who takes parasitic capacitance, drive circuit is used for enlargiing back output drive signal with input signal, drive signal warp the inductance is with generating the signal of telecommunication behind the parasitic capacitance resonance in order to arouse ultrasonic emission component to send the ultrasonic wave. The circuit design sensitivity is high, the power consumption is low, the circuit is relatively simple, and the driving effect is better.

Description

Ultrasonic drive circuit, fingerprint identification device and electronic equipment

[ technical field ] A method for producing a semiconductor device

The utility model relates to ultrasonic drive technical field, in particular to ultrasonic drive circuit, fingerprint identification device and electronic equipment.

[ background of the invention ]

The ultrasonic wave is widely applied to the fields of industrial nondestructive inspection, distance measurement and thickness measurement, agricultural ultrasonic breeding, ultrasonic seedling culture and ultrasonic induced spawning, biomedical diagnosis and operation, fingerprint identification in consumer electronics products and the like.

In the field of ultrasound applications, the ultrasound transmit circuitry is a critical component in the system. With the development of electronic technology and the increasing requirements of measuring devices and the like in terms of performance and precision, such as fingerprint identification modules, it has been developed towards high precision, high sensitivity and low power consumption. However, at present, the design methods of the ultrasonic transmitting circuit are numerous, but the circuit is complex and the driving effect is not good enough.

[ Utility model ] content

For overcoming the problems in the prior art, the utility model provides an ultrasonic drive circuit, fingerprint identification device and electronic equipment.

The utility model provides a technical problem's scheme provides an ultrasonic drive circuit, including power supply circuit, drive circuit and resonant circuit, carry out electric connection through drive circuit between power supply circuit and the resonant circuit, wherein resonant circuit includes inductance and ultrasonic emission component, inductance one end and drive circuit electric connection, the other end and ultrasonic emission component electric connection, ultrasonic emission component is the ultrasonic emission component of taking parasitic capacitance, drive circuit is used for enlargiing back output drive signal with input signal, drive signal warp the inductance sends the ultrasonic wave with exciting ultrasonic emission component with the post-production signal of telecommunication of parasitic capacitance resonance.

Preferably, the driving circuit includes two driving units, the driving unit is used for amplifying the input signal and then outputting the driving signal, the resonance circuit further includes a resonance unit for generating resonance, the input end of the resonance unit is connected with the two driving units, the output end of the resonance unit is electrically connected with the inductor, and the driving signal generates an electric signal after twice resonance with the parasitic capacitor through the resonance unit and the inductor to excite the ultrasonic wave emitting element to emit ultrasonic waves.

Preferably, the driving circuit includes (N +1) driving units, N is a positive integer and N is greater than or equal to 2, the driving units are configured to amplify an input signal and output a driving signal, the resonant circuit further includes N resonant units, each of the N resonant units is a first resonant unit, a second resonant unit, and a first resonant unit, the second resonant unit is sequentially connected in series with the inductor and the ultrasonic emission element, the input ends of the first resonant units are both connected to the driving unit, and the other output ends of the second resonant unit and the N resonant unit are also connected to the driving unit.

Preferably, the resonant unit includes a capacitor and a second inductor, the input ends of the capacitor and the second inductor are respectively connected to the driving unit or the output ends of the driving unit and the other resonant unit, and the output ends of the capacitor and the second inductor are both connected to one of the input ends of the other resonant unit or one end of the first inductor.

Preferably, the driving circuit further includes a switch Q1 and a switch Q2, wherein each of the switch Q1 and the switch Q2 includes a gate, a first electrode and a second electrode, the first electrode of the switch Q1 is electrically connected to the positive electrode of the power circuit, the second electrode of the switch Q1 is electrically connected to the first electrode of the switch Q2 to form an electrical junction J, the resonant circuit includes an inductor L and an ultrasonic wave emitting element, the ultrasonic wave emitting element further includes a parasitic capacitor Cf and an ultrasonic wave emitting element P, wherein the first end of the inductor L is electrically connected to the electrical junction J, the second end of the inductor L is electrically connected to the first end of the parasitic capacitor Cf, the first end of the ultrasonic wave emitting element P, and the second end of the parasitic capacitor Cf is electrically connected to the second end of the ultrasonic wave emitting element P and leads out a lead wire, and finally, the negative electrode of the power supply circuit and the second electrode of the switching tube Q2 are electrically connected and then connected to GND, and the gates G of the switching tube Q1 and the switching tube Q2 are used for receiving input signals and controlling the switching tubes Q1 and Q2 to be alternately conducted.

Preferably, the driving circuit further comprises a switching tube Q3, a switching tube Q4, a switching tube Q5 and a switching tube Q6, wherein each of the switching tube Q3, the switching tube Q4, the switching tube Q5 and the switching tube Q6 comprises a gate G and a first electrode and a second electrode, the first electrodes of the switching tube Q3 and the switching tube Q5 are electrically connected with the positive electrode of the power circuit, the second electrode of the switching tube Q3 is electrically connected with the first electrode of the switching tube Q4 to form an electrical junction J1, the second electrode of the switching tube Q5 is electrically connected with the first electrode of the switching tube Q6 to form an electrical junction J2, the switching tube Q3, the switching tube Q4 and the resonant circuit comprise a primary resonant unit and a secondary resonant unit, wherein the primary resonant unit further comprises an inductor L1 and a capacitor C1, the secondary resonant unit further comprises an inductor L2 and an ultrasonic wave emitting element, and the ultrasonic wave emitting element and a parasitic element Cf and a parasitic element P, a first end of an inductor L1 is electrically connected to the electrical node J1, a first end of a capacitor C1 is electrically connected to the electrical node J2, a second end of the inductor L1 is electrically connected to a second end of the capacitor C1 to form an electrical node J3, a first end of the inductor L2 is electrically connected to the electrical node J3, a second end of the inductor L2 is electrically connected to a first end of a parasitic capacitor Cf, a first end of an ultrasonic wave emitting element P is electrically connected to a second end of the parasitic capacitor Cf and a second end of the ultrasonic wave emitting element P, a conducting wire is led out, a negative electrode of the power circuit, a second electrode of the switching tube Q4 and a second electrode of the switching tube Q6 are electrically connected to the ground GND, and the gate G of the switching tube Q3, the switching tube Q4, the switching tube Q5 and the switching tube Q6 are used for receiving input signals to control the switching tubes Q3942, Q4, Q3, Q1 and the gate G of the switching tube Q6, Q5 and Q6 are alternately turned on.

Preferably, the ultrasonic wave emitting element includes a piezoelectric film.

Preferably, the resonance circuit multi-resonates the drive signal to generate an electric signal to excite the ultrasonic wave emitting element to emit the ultrasonic wave.

Preferably, a fingerprint identification device, it is used for carrying out fingerprint identification, ultrasonic drive circuit, signal generator and ultrasonic signal acquisition circuit that include, signal generator with drive circuit connects and provides input signal for it, ultrasonic emission component and ultrasonic signal acquisition circuit are connected, ultrasonic signal acquisition circuit is used for gathering the ultrasonic wave reflected signal that feeds back to calculate and obtain fingerprint information according to the ultrasonic wave reflected signal that gathers.

Preferably, the touch control device comprises a touch control interface and the fingerprint identification device is arranged on the opposite side of the touch control interface.

Compared with the prior art, the utility model discloses an ultrasonic drive circuit's beneficial effect as follows:

1. the utility model provides an ultrasonic drive circuit, includes power supply circuit, drive circuit and resonant circuit, carries out electric connection through drive circuit between power supply circuit and the resonant circuit. The ultrasonic wave transmitting device comprises a resonant circuit, a driving circuit and an ultrasonic wave transmitting element, wherein the resonant circuit comprises an inductor and the ultrasonic wave transmitting element, one end of the inductor is electrically connected with the driving circuit, the other end of the inductor is electrically connected with the ultrasonic wave transmitting element, the ultrasonic wave transmitting element is an ultrasonic wave transmitting element with a parasitic capacitor, the driving circuit is used for amplifying an input signal and then outputting a driving signal, and the driving signal is resonated by the inductor and the parasitic capacitor to generate an electric signal so as to excite the ultrasonic wave transmitting element to transmit. The circuit has the advantages of high design sensitivity, low power consumption, relatively simple circuit and better driving effect.

2. The utility model discloses ultrasonic drive circuit can provide multistage drive and multistage resonance, easily according to the appropriate increase and decrease drive unit of demand and resonance unit to be suitable for the ultrasonic energy of the difference under the different conditions.

3. The utility model discloses a fingerprint identification device has used ultrasonic drive circuit and drive method, still has used fingerprint identification device in the middle of an electronic equipment, explains this ultrasonic drive circuit and method have using value.

[ description of the drawings ]

Fig. 1 is a schematic block diagram of an ultrasonic drive circuit according to a first embodiment of the present invention;

fig. 2 is a schematic circuit diagram of an ultrasonic driving circuit according to a second embodiment of the present invention;

fig. 2a, 2b and 2c are waveform diagrams of simulation effect of the ultrasonic driving circuit according to the second embodiment of the present invention;

fig. 3 is a block diagram of an ultrasonic driving circuit according to a third embodiment of the present invention;

fig. 4 is a schematic circuit diagram of an ultrasonic driving circuit according to a fourth embodiment of the present invention;

fig. 4a, 4b and 4c are waveform diagrams illustrating simulation effects of the ultrasonic driving circuit according to the fourth embodiment of the present invention;

fig. 5 is a block diagram of an ultrasonic drive circuit according to a fifth embodiment of the present invention;

fig. 6 is a schematic circuit diagram of an ultrasonic drive circuit according to a sixth embodiment of the present invention;

fig. 7 is a schematic flow chart of the working steps of the ultrasonic driving method of the present invention;

fig. 8 is a schematic block diagram of a fingerprint identification device according to an eighth embodiment of the present invention;

fig. 9 is a schematic structural diagram of an electronic device according to a ninth embodiment of the present invention.

[ detailed description ] embodiments

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1, the present invention provides an ultrasonic driving circuit 100, which includes a power circuit 101, a driving circuit 102 and a resonant circuit 103, wherein the power circuit 101 and the resonant circuit 103 are electrically connected through the driving circuit 102. The power circuit 101 is used to provide power for the driving circuit 102 and provide a certain current capability to drive the circuit of the subsequent stage to operate. The drive circuit 102 is used to amplify an input signal to be supplied to the resonance circuit 103 as a drive source. And the resonant circuit 103 includes an inductor (a first inductor) and an ultrasonic wave emitting element (not shown), the inductor is connected in series with the ultrasonic wave emitting element, the ultrasonic wave emitting element is an ultrasonic wave emitting element with a parasitic capacitance, and the resonant circuit 103 is configured to generate a high-frequency high-voltage electrical signal by resonating an output signal amplified by the previous driving circuit 102 through the inductor and the parasitic capacitance to excite the ultrasonic wave emitting element to emit an ultrasonic wave, and preferably, the resonant circuit generates the high-frequency high-voltage signal. The utility model discloses an ultrasonic drive circuit 100 wide application is in the use of various electronic equipment for fingerprint identification, object removal orbit and sound field switch etc..

As an embodiment, the ultrasonic wave emitting element includes a piezoelectric film with its own parasitic capacitance. Preferably, the piezoelectric film is an in-situ polarized piezoelectric film, that is, the piezoelectric film is polarized in an in-situ polarized manner. Specifically, the piezoelectric film is formed in situ on one surface of a substrate, and comprises a first surface and a second surface which are opposite to each other, so that the potential of the first surface of the piezoelectric film is zero; providing a first electric field and a second electric field at the side of the second surface of the piezoelectric film, wherein the potential of the first electric field is higher than that of the second electric field; and ionizing the ambient gas on the side where the second surface of the piezoelectric film is located under the action of the first electric field, wherein the ambient gas passes through the second electric field and is gathered on the second surface of the piezoelectric film, so that an intra-film electric field in the film thickness direction is formed in the piezoelectric film, and the piezoelectric film is polarized to form the piezoelectric film.

In actual production, the piezoelectric film may be formed on the substrate by chemical vapor deposition, physical vapor deposition, plasma sputtering, or the like. In the prior art, the piezoelectric film is usually polarized by purchasing an existing finished product and adhering the finished product on a substrate through an adhesive layer, and the thickness of the piezoelectric film formed by the method is usually more than 30 μm, which is not suitable for the development trend of lightness and thinness of the existing electronic device. And the utility model provides a piezoelectric film normal position forms on the base member, and consequently thickness is very thin, forms simple process moreover to reduce the transmission loss of signal. Furthermore, the utility model discloses compare in direct upper and lower surface at the film and set up the electrode, can not make the piezoelectric film directly bear the high-tension electric field who applys, can avoid the membrane to be punctured. The utility model discloses can adopt plasma polarization (can see specifically that the chinese patent application of application number is 201710108374.9) or the mode of X ray polarization (can see specifically that the chinese patent application of application number is 201611222575.3) forms piezoelectric film, the piezoelectric film who forms can accomplish very thin, and moreover, piezoelectric effect is better and long service life, has carried out the normal position polarization piezoelectric film's piezoelectric effect D33's scope is 20-35 pC/N.

The piezoelectric film is made of a piezoelectric material, and can be selected from but not limited to: polyvinylidene fluoride, polyvinyl chloride, poly-gamma-methyl-L-glutamate, polycarbonate and polyvinylidene fluoride copolymer or a combination of a plurality of the polyvinylidene fluoride, the polyvinyl chloride, the poly-gamma-methyl-L-glutamate, the polycarbonate and the polyvinylidene fluoride copolymer.

In some embodiments of the present invention, the copolymer of polyvinylidene fluoride is polyvinylidene fluoride-trifluoroethylene copolymer, and in order to obtain the piezoelectric film with good piezoelectric effect, the mass ratio of polyvinylidene fluoride to trifluoroethylene is (60-95): (5-30), preferably, the mass ratio thereof is in the range of (75-86): (15-25), further preferably, the mass ratio is 80: 20, compared with the polyvinylidene fluoride selected independently, the polyvinylidene fluoride and trifluoroethylene copolymer can reduce the cost and has better piezoelectric effect.

The thickness of the piezoelectric thin film is less than 30 μm, and the thickness may be further less than 9 μm, and further the thickness may be 1.5 to 7.4 μm, 1.9 to 7.2 μm, 2.2 to 8.6 μm, 2.8 to 8.4 μm, or 3.6 to 6.6 μm, and further, may be specifically 1.8 μm, 2.4 μm, 2.6 μm, 3.7 μm, 3.9 μm, 4.2 μm, 4.6 μm, 5.6 μm, 5.8 μm, 6.7 μm, 8.6 μm, 8.7 μm.

The ultrasonic wave emitting element is taken as an example to explain in all embodiments of the present invention, and the piezoelectric film is a film with electrodes for loading and transmitting the electric signal. It is understood that it may be other ultrasonic wave emitting elements having parasitic capacitance.

It is understood that the power circuit 101 may be any power source capable of providing power, and the number of the power sources is not limited, and it may be one or more, and when the number of the power sources is multiple, it may be completely independent from each other, or partially independent from each other and partially connected in series.

It is understood that the driving circuit 102 may be composed of a switch tube, or a switch tube and one or more of a capacitor and a resistor, and the number of the switch tube, the capacitor and the resistor is not limited, and it may be configured to amplify the input signal.

It is to be understood that the specific circuit of the resonant circuit 103 is not limited, and it is sufficient that it generates a high-frequency high-voltage electrical signal by resonance to excite the ultrasonic wave emitting element to emit an ultrasonic wave. Electronic components such as a capacitor, an inductor or a resistor can be arranged as required.

It is understood that the electrical signal for exciting the ultrasonic wave emitting element to generate the ultrasonic wave is a high voltage electrical signal or a high frequency high voltage electrical signal.

Referring to fig. 2, a second embodiment of the present invention provides an ultrasonic driving circuit 200, which can be understood as a specific circuit configuration scheme of the first embodiment. The ultrasonic driving circuit 200 includes a power circuit 201, a driving circuit 202 and a resonant circuit 203, wherein the power circuit 201 and the resonant circuit 203 are electrically connected through the driving circuit 202. The power circuit 201 includes a power supply having a positive pole and a negative pole. The driving circuit 202 includes two switching tubes Q1 and Q2, wherein the switching tube Q1 and the switching tube Q2 each include a gate G and a first electrode and a second electrode. The first electrode of the switching tube Q1 is electrically connected to the positive electrode of the power supply, the second electrode of the switching tube Q1 is electrically connected to the first electrode of the switching tube Q2 to form an electrical node J, and the gates G of the switching tube Q1 and the switching tube Q2 are both connected to a signal generator (not shown), and the signal generator provides an input signal of the driving circuit 202, preferably, the input signal is an output pulse control signal. The resonance circuit 203 includes an inductance L (first inductance) and an ultrasonic wave transmitting element P, which is an electronic element having a parasitic capacitance Cf. For convenience of explanation, the parasitic capacitance Cf of the ultrasonic wave emitting element P is independently drawn in the drawings, and it can be understood that the parasitic capacitance Cf belongs to a part of the ultrasonic wave emitting element P, and in an actual product, it does not exist. The first end of the inductor L is electrically connected to the electrical junction J, the second end of the inductor L is electrically connected to the first end of the parasitic capacitor Cf, the first end of the ultrasonic emission element P is electrically connected, the second end of the parasitic capacitor Cf is electrically connected to the second end of the ultrasonic emission element P, a lead is led out for connecting to a signal acquisition circuit (not shown), and finally, the negative electrode of the power supply and the second electrode of the switch tube Q2 are electrically connected and then connected to GND.

With continued reference to fig. 2, the operation principle of the ultrasonic driving circuit 200 is as follows:

1. the power circuit 201 supplies power to the driving circuit 202, and a signal generator (not shown) generates two sets of input signals to be respectively input to the gate G of the switching tube Q1 and the switching tube Q2 in the driving circuit 202.

2. The switch Q1 and the switch Q2 are alternately turned on, the driving circuit 202 amplifies the input signal, and an amplified pulse signal is formed at the first end of the inductor L, the number of the pulse signal is the same as that of the input signal, and the pulse signal has a certain current driving capability.

3. The amplified pulse signal generated by the driving circuit 202 is input to the resonant circuit 203, and when the switching tube is frequently switched, the amplified pulse signal is resonated by the parasitic capacitance Cf and the inductance L in the resonant circuit 203 to generate a high-frequency high-voltage electric signal, and the high-frequency high-voltage electric signal excites the ultrasonic wave emitting element P to emit and generate ultrasonic waves.

Referring to fig. 2, fig. 2a, fig. 2b and fig. 2c, the ultrasonic driving circuit 200 is simulated, specifically:

1. the power circuit 201 supplies power to the driving circuit 202, and a signal generator (not shown) generates two sets of input signals, specifically 15V, with 5 pulses, which are respectively input to the gate G of the switching transistor Q1 and the switching transistor Q2 in the driving circuit 202.

2. In the driving circuit 202, the switch Q1 and the switch Q2 are turned on alternately to amplify the amplitude of the input signal, so that an amplified pulse signal of 30V is formed at the first end of the inductor L, and the number of the pulse signals is the same as the number of the input signals.

3. When a 30V pulse signal generated by the drive circuit 202 is input to the resonant circuit 203, the switching transistor Q1 is turned on at time T1, the switching transistor Q2 is turned off, the inductor L discharges, and the parasitic capacitor Cf charges; at time T2, the switch Q1 is turned off, the switch Q2 is turned on, the inductor L is charged, the parasitic capacitor Cf is discharged, and when the switch is frequently turned on and off, the amplified pulse signal is resonated by the parasitic capacitor Cf and the inductor L in the resonant circuit 203 to generate a high-frequency high-voltage electrical signal, which excites the ultrasonic wave emitting element P to emit ultrasonic waves, as shown in fig. 2c, which are waveforms across the equivalent capacitor of the ultrasonic wave emitting element, i.e., emitted ultrasonic signals.

Referring to fig. 3, a third embodiment of the present invention provides an ultrasonic driving circuit 300, which includes a power circuit 301, a driving circuit 302 and a resonant circuit 303, wherein the power circuit 301 and the resonant circuit 303 are electrically connected through the driving circuit 302. The power circuit 301 is used to provide power for the driving circuit 302 and provide a certain current capability to drive the circuit of the subsequent stage to operate. The drive circuit 302 is used to amplify an input signal to be supplied to the resonance circuit 303 as a drive source. The driving circuit 302 includes two driving units 3021, and the driving units 3021 amplify input signals. The resonant circuit 303 includes a resonant unit 3031, an inductor 3032 (a first inductor), and an ultrasonic transmitting element 3033, the resonant unit 3031 is connected to the two driving units 3021, and is sequentially connected in series with the inductor 3032 and the ultrasonic transmitting element 3033, the ultrasonic transmitting element 3033 is an ultrasonic transmitting element 3033 with a parasitic capacitor, and the resonant circuit 303 is configured to resonate an output signal amplified by the driving circuit 302 of the previous stage with the parasitic capacitor through the resonant unit 3031, the inductor 3032, and generate a high-frequency high-voltage electrical signal to excite the ultrasonic transmitting element 3033 to emit ultrasonic waves.

It will be appreciated that the resonant unit 3031 is a unit that participates in the resonance of the drive signal, and may be a complete resonant network or a part of a resonant network.

In the embodiment, two driving units 3021 are provided, and a secondary resonant network is formed among the resonant unit 3031, the inductor 3032 and the parasitic capacitance of the ultrasonic transmitting element 3033, so that a stronger ultrasonic transmitting signal can be obtained.

Referring to fig. 4, a fourth embodiment of the present invention provides an ultrasonic driving circuit 400. It is to be understood that this embodiment is a specific circuit configuration scheme of the first embodiment or the third embodiment. The ultrasonic driving circuit 400 includes a power circuit 401, a driving circuit 402 and a resonant circuit 403, wherein the power circuit 401 and the resonant circuit 403 are electrically connected through the driving circuit 402. Specifically, the power circuit 401 includes a power supply, the driving circuit 402 includes two driving units, namely a first driving unit 4021 and a second driving unit 4022, the resonant circuit 403 includes a resonant unit 4031, an inductor L2 (a first inductor), and an ultrasonic wave emitting element P, which are sequentially connected in series, and the resonant unit 4031 is electrically connected to the two driving units.

The power supply has a positive pole and a negative pole. The first driving unit 4021 includes two switching tubes Q3 and Q4, and the second driving unit 4022 includes two switching tubes Q5 and Q6, wherein the switching tube Q3, the switching tube Q4, the switching tube Q5, and the switching tube Q6 each include a gate G, a first electrode, and a second electrode. The first electrodes of the switching tube Q3 and the switching tube Q5 are electrically connected to the positive electrode of the power supply, the second electrode of the switching tube Q3 is electrically connected to the first electrode of the switching tube Q4 to form an electrical node J1, the second electrode of the switching tube Q5 is electrically connected to the first electrode of the switching tube Q6 to form an electrical node J2, and the gates G of the switching tube Q3, the switching tube Q4, the switching tube Q5 and the switching tube Q6 are all connected to a signal generator (not shown), and the signal generator provides an input signal of the driving circuit 402, preferably, the input signal is a pulse control signal. The resonance unit 4031 includes an inductance L1 (second inductance) and a capacitance C1, and the ultrasonic wave transmitting element P thereof is an electronic element of the parasitic capacitance Cf. A first end of the inductor L1 is electrically connected to the electrical node J1, a first end of the capacitor C1 is electrically connected to the electrical node J2, a second end of the inductor L1 is electrically connected to a second end of the capacitor C1 to form an electrical node J3, a first end of the inductor L2 is electrically connected to the electrical node J3, a second end of the inductor L2 is electrically connected to a first end of the parasitic capacitor Cf, a first end of the ultrasonic wave emitting element P is electrically connected to a second end of the parasitic capacitor Cf, and a lead is led out from the second end of the ultrasonic wave emitting element P to access a signal collecting circuit (not shown), and finally, a negative electrode of the power supply, a second electrode of the switch Q4, and a second electrode of the switch Q6 are electrically connected to ground.

Referring to fig. 4, fig. 4a, fig. 4b and fig. 4c, the operation principle and simulation effect of the ultrasonic driving circuit 400 are as follows:

1. the power circuit 401 supplies power to the driving circuit 402, and a signal generator (not shown) generates four sets of input signals to be respectively input to the gate G of the switching tube Q3, the switching tube Q4, the switching tube Q5 and the switching tube Q6 in the driving circuit 402.

2. The switch tube Q3, the switch tube Q4, the switch tube Q5 and the switch tube Q6 are alternately conducted, the driving circuit 402 amplifies the input signal, an amplified pulse signal of 30V is respectively formed at the first end of the inductor L1 and the first end of the capacitor C1, the number of the pulse signals is the same as that of the input signals, and the pulse signals also have certain current driving capability.

3. The amplified pulse signal generated by the driving circuit 402 is input into the resonant circuit 403, at time T1, the switching tube Q3 is turned off, the switching tube Q4 is turned on, the switching tube Q5 is turned on, and the switching tube Q6 is turned off, the equivalent circuit is that the inductor L1 and the capacitor C1 are connected in parallel and then connected in series with the inductor L2, that is, the capacitor C1 is charged, and the inductor L1 and the inductor L2 are discharged; at the time of T2, the switching tube Q3 is turned on, the switching tube Q4 is turned off, the switching tube Q5 is turned off, and the switching tube Q6 is turned on, and an equivalent circuit is that the capacitor C1 is connected in series at a preceding stage after the inductor L1 and the inductor L2 are connected in parallel, that is, the capacitor C1 discharges, and the inductor L1 and the inductor L2 charge; at the time T3 (i.e., repeating T1), the switching tube Q3 is turned off, the switching tube Q4 is turned on, the switching tube Q5 is turned on, and the switching tube Q6 is turned off, so that the equivalent circuit is that the inductor L1 and the capacitor C1 are connected in parallel and then connected in series with the inductor L2, that is, the capacitor C1 is charged, and the inductor L1 and the inductor L2 are discharged. Under the frequent switching of the switching tube, the amplified pulse signal generates two-stage resonance through the first resonance unit 4031 in the resonance circuit 403 and two ends of the parasitic capacitor Cf and the inductor L to generate a high-frequency high-voltage electric signal, and the high-frequency high-voltage electric signal excites the ultrasonic wave emitting element P to emit and generate ultrasonic waves.

Referring to fig. 5, a fifth embodiment of the present invention provides an ultrasonic driving circuit 500, which includes a power circuit 501, a driving circuit 502 and a resonant circuit 503, wherein the power circuit 501 and the resonant circuit 503 are electrically connected through the driving circuit 502. The power supply circuit 501 is used to provide power to the driving circuit 502 and provide a certain current capability to drive the circuit of the subsequent stage to operate. The driving circuit 502 is used to amplify an input signal to be supplied to the resonance circuit 503 as a driving source. The driving circuit 502 includes three driving units, and the driving unit 5021 is used for amplifying an input signal. The resonant circuit 503 includes two resonant units, an inductor 5033 (a first inductor) and an ultrasonic wave emitting element 5034, the 3 driving units are respectively a first driving unit 5021, a second driving unit 5022 and a third driving unit 5023, the resonant units include the first resonant unit 5031 and the second resonant unit 5032, the first driving unit 5021 and the second driving unit 5022 are connected with the power circuit and the first resonant unit 5031, the output end of the first resonant unit 5031 and the output end of the third driving unit 5023 are connected to the two input ends of the second resonant unit 5032, the output end of the second resonant unit 5032 is connected with the inductor 5033, and the inductor 5033 is connected in series with the ultrasonic wave emitting element 5034. The ultrasonic wave emitting component 5034 is an ultrasonic wave emitting component 5034 with a parasitic capacitor, and the resonant circuit 503 is configured to resonate an output signal amplified by the front-stage driving circuit 502 with the parasitic capacitor through the resonant unit, the inductor 5033 to generate a high-frequency and high-voltage electrical signal so as to excite the ultrasonic wave emitting component 5033 to emit an ultrasonic wave.

It will be appreciated that the resonant unit 5031 is a unit that participates in the resonance of the drive signal, and may be a complete resonant network or part of a resonant network.

In this embodiment, a three-stage resonant network is formed between the two resonant units, the inductor 5032 and the parasitic capacitor of the ultrasonic wave emitting element 5033, so that a stronger ultrasonic wave emitting signal can be obtained.

Referring to fig. 6, a sixth embodiment of the present invention provides an ultrasonic driving circuit 600. It is to be understood that this embodiment is a specific circuit configuration scheme of the fifth embodiment. The ultrasonic driving circuit 600 includes a power circuit 601, a driving circuit 602, and a resonant circuit 603, wherein the power circuit 601 and the resonant circuit 603 are electrically connected through the driving circuit 602. Specifically, the power circuit 601 includes a power supply, the driving circuit 602 includes three driving units, namely a first driving unit 6021, a second driving unit 6022 and a third driving unit 6023, the resonant circuit 603 includes two resonant units, an inductor L5 (a first inductor) and an ultrasonic emitting element P, which are sequentially connected in series, the two resonant units are a first resonant unit 6031 and a second resonant unit 6032, which are electrically connected, respectively, wherein the first resonant unit 6031 is electrically connected with the first driving unit 6021 and the second driving unit 6022, and the second resonant unit 6032 is electrically connected with the third driving unit 6023.

The power supply has a positive pole and a negative pole. The first driving unit 6021 comprises two switching tubes Q7 and Q8, the second driving unit 6022 comprises two switching tubes Q9 and Q10, and the third driving unit 6023 comprises two switching tubes Q11 and Q12, wherein the switching tube Q7, the switching tube Q8, the switching tube Q9, the switching tube Q10, the switching tube Q11 and the switching tube Q12 each comprise a gate G and a first electrode and a second electrode. The first electrodes of the switching tube Q7, the switching tube Q9 and the switching tube Q11 are electrically connected to the positive electrode of the power supply, the second electrode of the switching tube Q7 is electrically connected to the first electrode of the switching tube Q8 to form an electrical junction J4, the second electrode of the switching tube Q9 is electrically connected to the first electrode of the switching tube Q10 to form an electrical junction J5, the second electrode of the switching tube Q11 is electrically connected to the first electrode of the switching tube Q12 to form an electrical junction J6, and the gate G of the switching tube Q7, the switching tube Q8, the switching tube Q9, the switching tube Q10, the switching tube Q11 and the switching tube Q12 are all connected to a signal generator (not shown), and the signal generator provides an input signal of the driving circuit 602, preferably, the input signal is a pulse control signal. The first resonance unit 6031 includes an inductance L3 (second inductance) and a capacitance C3, and the second resonance unit 6032 includes an inductance L4 (second inductance) and a capacitance C4, and its ultrasonic wave transmitting element P is an electronic element with its own parasitic capacitance Cf. Wherein the first end of the inductor L3 is electrically connected to the electrical node J4, the first end of the capacitor C3 is electrically connected to the electrical node J5, the first end of the capacitor C4 is electrically connected to the electrical node J6, the second end of the inductor L3 is electrically connected to the first end of the inductor L4 and the second end of the capacitor C3 to form an electrical node J7, the second end of the inductor L4 is electrically connected to the first end of the inductor L5 and the second end of the capacitor C4 to form an electrical node J8, the second end of the inductor L5 is electrically connected to the first end of the parasitic capacitor Cf, and the first end of the ultrasonic wave emitting device P is electrically connected to the first end of the parasitic capacitor Cf, and the second end of the parasitic capacitor Cf is electrically connected with the second end of the ultrasonic wave emitting element P, and a lead is led out to access a signal acquisition circuit (not shown), and finally, the negative electrode of the power supply, the second electrode of the switching tube Q8, the second electrode of the switching tube Q10 and the second electrode of the switching tube Q12 are electrically connected and then are connected to the ground GND.

Referring to fig. 6, the operation principle of the ultrasonic driving circuit 600 is as follows:

1. the power circuit 601 provides power for the driving circuit 602, and six sets of input signals generated by a signal generator (not shown) are respectively input to the gates G of the switching tube Q7, the switching tube Q8, the switching tube Q9, the switching tube Q10, the switching tube Q11 and the switching tube Q12 in the driving circuit 602.

2. The switch tube Q7, the switch tube Q8, the switch tube Q9, the switch tube Q10, the switch tube Q11 and the switch tube Q12 are alternately turned on, the driving circuit 602 amplifies the input signal, and an amplified pulse signal is respectively formed at the first end of the inductor L3, the first end of the capacitor C3 and the first end of the capacitor C4, the number of the pulse signals is the same as that of the input signal, and the driving circuit also has certain current driving capability.

3. The amplified signal pulse generated by the drive circuit 602 is input to the resonance circuit 603 to resonate. Under the frequent switching of the switching tube, the amplified pulse signal generates three-level resonance through the first resonance unit 6031, the second resonance unit 6032, the parasitic capacitance Cf and the inductance L5 in the resonance circuit 603 to generate a high-frequency high-voltage electric signal, which excites the ultrasonic wave emitting element P to emit and generate ultrasonic waves.

Referring to fig. 7, a seventh embodiment of the present invention provides an ultrasonic driving circuit 700, including:

the power circuit provides power, and the signal generator sends an input signal to be input into the multi-stage driving circuit;

step S2: the multi-stage driving circuit can amplify an input signal and then output a driving signal to the multi-stage resonant circuit;

step S3: the driving signal generates a high-frequency high-voltage electric signal through resonance generated in the resonance circuit to excite the ultrasonic wave emitting element to emit ultrasonic waves, the ultrasonic wave emitting element comprises a parasitic capacitor, and the driving signal generates resonance at least through the parasitic capacitor.

Referring to fig. 8, the ultrasonic driving circuit of the present invention is applied to a fingerprint identification apparatus 800, which is mainly used for fingerprint identification, and includes a power circuit 801, a driving circuit 802, a resonant circuit 803, a signal generator 804 and a signal collecting circuit 805, wherein the resonant circuit 803 further includes an ultrasonic emitting element 8031. The power circuit 801 provides power for the whole circuit system of the fingerprint identification device 800, the signal generator 804 is electrically connected to the driving circuit 802 and provides input signals for the driving circuit 802, the driving circuit 802 is electrically connected to the resonant circuit 803, and the ultrasonic wave emitting element 8031 in the resonant circuit 803 is electrically connected to the signal collecting circuit 805. The signal acquisition circuit 805 is configured to acquire the ultrasonic emission signal fed back, and calculate to obtain fingerprint information according to the acquired ultrasonic emission signal.

It is understood that the ultrasonic driving circuit disclosed in other embodiments of the present invention can be used as the ultrasonic driving circuit for driving the fingerprint identification device 800 to generate ultrasonic waves in this embodiment.

Referring to fig. 9, the fingerprint identification device 800 of the ultrasonic driving circuit of the present invention is applied to an electronic device 900, which includes a touch interface 901, and the fingerprint identification device 800 is disposed on the opposite side of the touch interface 901.

The electronic device 900 may be a mobile phone, a computer, an intelligent wearable device, an intelligent home device, or the like. Preferably, the signal generator outputs a signal with an amplitude of 2.8-15V and a number of pulses of 5-7.

It should be noted that the ultrasonic driving circuit of the present invention can adopt a multi-stage driving and multi-stage resonance mode to improve the signal emission intensity and the signal stability of the ultrasonic generating element. The driving circuit may include (N +1) driving units, where N is a positive integer and N is greater than or equal to 2, the driving units are configured to amplify an input signal and output a driving signal, the resonant circuit further includes N resonant units, each of the N resonant units is a first resonant unit, a second resonant unit, and a first resonant unit, the second resonant unit is sequentially connected in series with the first inductor and the ultrasonic emitting element, an input end of the first resonant unit is connected to the driving unit, and another output end of the second resonant unit is also connected to the driving unit.

The switch tube can be any one of an N-type field effect tube or a P-type field effect tube.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, and improvements made within the principle of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultrasonic drive circuit, includes power supply circuit, drive circuit and resonant circuit, its characterized in that: carry out electric connection through drive circuit between power supply circuit and the resonant circuit, wherein resonant circuit includes inductance and ultrasonic emission component, inductance one end and drive circuit electric connection, the other end and ultrasonic emission component electric connection, ultrasonic emission component is the ultrasonic emission component of taking parasitic capacitance, drive circuit is used for enlargiing back output drive signal with input signal, drive signal warp generate the signal of telecommunication after inductance and the parasitic capacitance resonance in order to arouse ultrasonic emission component and send the ultrasonic wave.

2. The ultrasonic drive circuit according to claim 1, wherein: the drive circuit comprises two drive units, the drive units are used for amplifying input signals and then outputting drive signals, the resonance circuit further comprises a resonance unit used for generating resonance, the input end of the resonance unit is connected with the two drive units, the output end of the resonance unit is electrically connected with the inductor, and the drive signals generate electric signals to excite the ultrasonic transmitting element to emit ultrasonic waves after two-stage resonance is carried out on the drive signals through the resonance unit and the inductor and the parasitic capacitor.

3. The ultrasonic drive circuit according to claim 1, wherein: the drive circuit comprises (N +1) drive units, wherein N is a positive integer and is more than or equal to 2, the drive units are used for amplifying an input signal and then outputting a drive signal, the resonance circuit further comprises N resonance units, the N resonance units are respectively a first resonance unit, a second resonance unit, an inductor and an ultrasonic emission element, the input ends of the first resonance units are connected with the drive units, and the other output ends of the second resonance unit and the N resonance unit are also connected with the drive units.

4. An ultrasonic drive circuit according to claim 2 or 3, characterized in that: the resonance unit comprises a capacitor and a second inductor, the input ends of the capacitor and the second inductor are respectively connected with different driving units or the output ends of the driving unit and the other resonance unit, and the output ends of the capacitor and the second inductor are respectively connected to one of the input ends of the other resonance unit or one end of the first inductor.

5. The ultrasonic drive circuit according to claim 1, wherein: the driving circuit further comprises a switch tube Q1 and a switch tube Q2, wherein the switch tube Q1 and the switch tube Q2 both comprise a gate, a first electrode and a second electrode, the first electrode of the switch tube Q1 is electrically connected with the positive electrode of the power circuit, the second electrode of the switch tube Q1 is electrically connected with the first electrode of the switch tube Q2 to form an electrical junction J, the resonant circuit comprises an inductor L and an ultrasonic transmitting element, the ultrasonic transmitting element further comprises a parasitic capacitor Cf and an ultrasonic transmitting element P, the first end of the inductor L is electrically connected with the electrical junction J, the second end of the inductor L is electrically connected with the first end of the parasitic capacitor Cf, the first end of the ultrasonic transmitting element P, the second end of the parasitic capacitor Cf is electrically connected with the second end of the ultrasonic transmitting element P, a lead is led out, and finally, the negative electrode of the power circuit, The second electrode of the switching tube Q2 is electrically connected and then connected to GND, and the gates G of the switching tube Q1 and the switching tube Q2 are used for receiving input signals and controlling the switching tubes Q1 and Q2 to be alternately turned on.

6. The ultrasonic drive circuit according to claim 1, wherein: the driving circuit further comprises a switching tube Q3, a switching tube Q4, a switching tube Q5 and a switching tube Q6, wherein each of the switching tube Q3, the switching tube Q4, the switching tube Q5 and the switching tube Q6 comprises a gate G, a first electrode and a second electrode, the first electrodes of the switching tube Q3 and the switching tube Q5 are electrically connected with the positive electrode of the power circuit, the second electrode of the switching tube Q3 is electrically connected with the first electrode of the switching tube Q4 to form an electrical junction J1, the second electrode of the switching tube Q5 is electrically connected with the first electrode of the switching tube Q6 to form an electrical junction J2, the switching tube Q3, the switching tube Q4 and the resonant circuit comprise a primary resonant unit and a secondary resonant unit, wherein the primary resonant unit further comprises an inductor L1 and a capacitor C1, the secondary resonant unit further comprises an inductor L2 and an ultrasonic wave transmitting element, and the ultrasonic wave transmitting element further comprises a parasitic capacitive element Cf and a parasitic capacitor P, wherein the first end of the inductor L1 is electrically connected to the electrical node J1, the first end of the capacitor C1 is electrically connected to the electrical node J2, the second end of the inductor L1 is electrically connected to the second end of the capacitor C1 to form an electrical node J3, the first end of the inductor L2 is electrically connected to the electrical node J3, the second end of the inductor L2 is electrically connected to the first end of the parasitic capacitor Cf and the first end of the ultrasonic wave emitting element P, and the second end of the parasitic capacitor Cf and the second end of the ultrasonic wave emitting element P are electrically connected and lead out a lead, and finally the negative electrode of the power circuit, the second electrode of the switch tube Q4 and the second electrode of the switch tube Q6 are electrically connected and then connected to the ground GND, the gates G of the switching tube Q3, the switching tube Q4, the switching tube Q5 and the switching tube Q6 are used for receiving input signals and controlling the switching tubes Q3, Q4, Q5 and Q6 to be alternately conducted.

7. The ultrasonic drive circuit according to claim 1, wherein: the ultrasonic wave emitting element includes a piezoelectric film.

8. The ultrasonic drive circuit according to claim 1, wherein: the resonance circuit performs multi-stage resonance on the drive signal to generate an electric signal to excite the ultrasonic wave emitting element to emit the ultrasonic wave.

9. A fingerprint identification device, it is used for carrying on fingerprint identification, characterized by that: the ultrasonic fingerprint sensor comprises an ultrasonic driving circuit according to any one of claims 1 to 8, a signal generator and an ultrasonic signal acquisition circuit, wherein the signal generator is connected with the driving circuit and provides input signals for the driving circuit, the ultrasonic emitting element is connected with the ultrasonic signal acquisition circuit, and the ultrasonic signal acquisition circuit is used for acquiring ultrasonic reflection signals fed back and calculating fingerprint information according to the acquired ultrasonic reflection signals.

10. An electronic device, characterized in that: comprising a touch interface and a fingerprint recognition device according to claim 9, said fingerprint recognition device being arranged on the opposite side of the touch interface.