An ultrasonic electronic device circuit for isolating high voltage transmission from small signal reception

Abstract

The application discloses an ultrasonic electronic device circuit for isolating high-voltage emission and small-signal reception, characterized in that the circuit comprises a diode bias current control circuit and a diode interconnection circuit; the diode bias current control circuit is used for controlling and adjusting the current flowing through diodes in the diode interconnection circuit; and the diode interconnection circuit is used for isolating the input network of a small-signal receiving circuit from a high-voltage power supply output network or connecting the input network of the small-signal receiving circuit with a transducer output network. The application adopts program control to open or close the direct current bias current of two series-connected diodes, so as to realize the cut-off and conduction of the diodes; when the direct current bias current of the diodes is closed, the diodes are cut off, and the high-voltage power supply is isolated from the receiving circuit; when the direct current bias current of the two diodes is opened, the diodes are conducted, the alternating current impedance is very small, and the output signal of the ultrasonic transducer is connected with the small-signal receiving circuit with very low impedance.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic measurement technology, and more specifically to an ultrasonic electronic device circuit that isolates high-voltage transmission and low-signal reception. Background Technology

[0002] Industrial ultrasonic testing sometimes requires higher ultrasonic transmission power, simpler and more reliable transducer structures, and more sensitive signal receiving electronics. These objectives are interdependent in terms of technical parameters; sometimes, meeting one requirement necessitates sacrificing others. For example, increasing ultrasonic transmission power typically increases the dead zone of the receiving signal and the size of the electronic circuitry. Reducing the dead zone by splitting the transducer into two physical parts—transmitting and receiving—increases the transducer's structural complexity. Simply increasing the signal receiving gain to improve signal sensitivity may simultaneously increase noise. Finding a balance among these numerous technical specifications is crucial to meeting the application objectives of the end-user of ultrasonic testing equipment.

[0003] In a self-transmitting and self-receiving ultrasonic testing electronic system, the received signal is usually 2 to 6 orders of magnitude lower than the transmitted signal. Therefore, the transmitted signal is considered a high-voltage signal to any received signal. Thus, circuit modules that isolate high-voltage transmission and low-signal reception are particularly important.

[0004] Taking electromagnetic ultrasonic testing equipment as an example, existing electromagnetic ultrasonic technology requires a high-power, high-voltage power supply to excite a transducer placed in a constant magnetic field on the surface of the workpiece. This generates ultrasonic waves on the workpiece surface, which then propagate within the workpiece. The reflected ultrasonic waves are then passed through the transducer coil placed in the constant magnetic field, generating a weak voltage signal. This signal is input to the back-end small-signal processing circuit, where it undergoes analog conditioning and software analysis to obtain the test results. The high voltage generated by the transmitting circuit is typically on the order of 100V, while the small signal generated by the receiving circuit is typically on the order of 10µV. Therefore, the interference from the high-voltage transmitting circuit to the small-signal receiving circuit can be substantial. Consequently, the high-power, high-voltage power supply needs to be isolated from the back-end small-signal processing circuit, and the transducer coil and the back-end small-signal circuit need to maintain an effective low-impedance connection path.

[0005] Existing mainstream piezoelectric ultrasonic electronic devices and electromagnetic ultrasonic electronic devices use damping and limiting methods to isolate high voltage and output small signals. Specifically, a resistor of several hundred ohms is connected in series between the high-voltage power supply and the input terminal of the small signal receiving circuit. A pair of fast recovery small signal diodes connected in parallel to ground are added to the connection point between the resistor and the input terminal of the small signal receiving circuit. The resistor carries most of the high voltage drop, while the pull-down diodes clamp the residual high voltage at the small signal input terminal within a safe range.

[0006] The drawback of the damping limiter is that, since a resistor of several hundred ohms is connected in series from the transducer output to the small signal receiving circuit input, the equivalent output impedance of the transducer is increased, the signal-to-noise ratio at the signal source end is reduced, and the overall signal-to-noise ratio of the instrument decreases.

[0007] Taking the fully focused piezoelectric phased array testing equipment as an example, each measurement of each array element requires a self-transmitting and self-receiving measurement. If the transmission voltage is too high, the small signal blind zone will also be too large, which will miss important information about near-surface sample defects. Summary of the Invention

[0008] To address the aforementioned technical problems, the objective of this invention is to provide an ultrasonic electronic device circuit that isolates high-voltage transmission and low-signal reception, replacing the method of using series resistors and limiting diodes to isolate the high-voltage output and low-signal reception circuit. This reduces the equivalent output impedance of the transducer, enhances the signal-to-noise ratio, and reduces the signal dead zone of the self-transmitting and self-receiving ultrasonic transducer.

[0009] The technical solution of this invention is:

[0010] An ultrasonic electronic device circuit that isolates high-voltage transmission and small signal reception includes a diode bias current control circuit and a diode interconnection circuit.

[0011] The diode bias current control circuit is used to control and adjust the current flowing through the diodes in the diode interconnection circuit.

[0012] The diode interconnection circuit is used to isolate the high-power high-voltage power supply output circuit and the ultrasonic signal receiving circuit, and to connect the transducer output network and the ultrasonic signal receiving circuit.

[0013] Preferably, the diode interconnection circuit includes diodes D1, D2, D11, D12 and resistors R1 and R5, wherein the first ends of resistors R1 and R5 are connected to the control terminal of the diode bias current control circuit; the second ends of resistors R1 and R5 are respectively connected to the two ends of the high-voltage power supply output network through diodes D1 and D11; the second ends of resistors R1 and R5 are also respectively connected to the two ends of the input network of the ultrasonic signal receiving circuit through diodes D2 and D12.

[0014] Preferably, the diode interconnection circuit adopts a type I circuit or a type II circuit;

[0015] In the type I circuit: the cathodes of diodes D1 and D2 are connected to resistor R1, and the cathodes of diodes D11 and D12 are connected to resistor R5; the anodes of diodes D1 and D11 are respectively connected to the two ends of the high-voltage power supply output network; the anodes of diodes D2 and D12 are respectively connected to the two ends of the input network of the ultrasonic signal receiving circuit.

[0016] In the Type II circuit: the anodes of diodes D1 and D2 are connected to resistor R1, and the anodes of diodes D11 and D12 are connected to resistor R5; the cathodes of diodes D1 and D11 are connected to the two ends of the high-voltage power supply output network, respectively; the cathodes of diodes D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit, respectively.

[0017] Preferably, the diode bias current control circuit includes a transistor Q1, static bias resistors R2 and R3, and a negative feedback resistor R4. The static bias resistors R2 and R3 are connected in series, with one end of R2 grounded. The other end of R3 is connected to -VCC voltage in type I circuit and to +VCC voltage in type II circuit. The base of transistor Q1 is connected to the common junction of R2 and R3, the emitter is connected to one end of R4, and the other end of R4 is connected to the VEE power supply controlled by the system processor. The VEE power supply outputs 0V or -VCC in type I circuit and 0V or +VCC in type II circuit. The collector is connected to the control terminal of the diode interconnect circuit.

[0018] Preferably, the transducer output network is an electromagnetic transducer L1_1 or L1_2;

[0019] In the type I circuit, one end of the electromagnetic transducers L1_1 and L1_2 is connected to the anode of diodes D1 and D11 respectively, and the other end is grounded together.

[0020] In the Type II circuit, one end of the electromagnetic transducers L1_1 and L1_2 is connected to the cathodes of diodes D1 and D11 respectively, and the other end is grounded together.

[0021] Preferably, the transducer output network is a piezoelectric transducer Y1_1, Y1_2;

[0022] In the type I circuit, one end of the piezoelectric transducers Y1_1 and Y1_2 is connected to the anode of diodes D1 and D11 respectively, and the other end is grounded together;

[0023] In the Type II circuit, one end of the piezoelectric transducers Y1_1 and Y1_2 is connected to the cathodes of diodes D1 and D11 respectively, and the other end is grounded together.

[0024] Preferably, when the system processor controls the VEE power supply to output 0V, the transistor Q1 in the diode bias current control circuit is cut off, the collector does not provide static current output, the diode in the diode interconnection circuit has no forward bias current, and the positive-to-positive branch of the two series diodes and the negative-to-emitter branch of the two series diodes are both in a cut-off isolation state. At this time, the system processor controls the high-voltage transmitting power supply to output a high-voltage pulse to form a loop through the low-impedance transducer coil to ground, thus completing the high-voltage transmission.

[0025] After the high-voltage transmission cycle ends, the system processor controls the output of the VEE power supply. In the type I circuit, the VEE outputs -VCC, and in the type II circuit, it outputs +VCC. The transistor Q1 in the diode bias current control circuit is turned on, and the negative feedback resistor R4 stabilizes the static operating voltage and current of Q1. The collector provides a constant static current output. The diodes in the diode interconnect circuit generate bias current. For the small AC signal output from the transducer, the two series diodes are in a conducting state. At this time, the two input terminals of the transducer and the ultrasonic signal receiving circuit are in a conducting connection state, completing the reception of the ultrasonic echo.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] 1. This invention employs a novel high-voltage isolation and low-impedance small-signal output interface circuit. It uses program control to turn on or off the DC bias current of two series-connected diodes to achieve diode cutoff and conduction. At the same time, it achieves isolation between the high-voltage power supply and the small-signal receiving circuit and low-impedance connection between the transducer and the small-signal receiving circuit. Based on the existing technology, it reduces the equivalent output impedance of the transducer and improves the signal-to-noise ratio of the system.

[0028] 2. This invention realizes a circuit structure design that achieves high-impedance isolation and low-impedance connection in a time-division multiplexing manner for diode interconnection circuits;

[0029] 3. This invention enables rapid start-up and rapid shutdown of the diode bias control circuit; Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0031] Figure 1 This is a schematic diagram of the high-voltage isolation type I circuit connected to the electromagnetic transducer in Example 1;

[0032] Figure 2 This is a schematic diagram of the high-voltage isolation type II circuit connected to the electromagnetic transducer in Example 1;

[0033] Figure 3 This is a schematic diagram of the high-voltage isolation type I circuit connected to the piezoelectric transducer in Example 2;

[0034] Figure 4 This is a schematic diagram of the high-voltage isolation type II circuit connected to the piezoelectric transducer in Example 2;

[0035] Figure 5 The thickness measurement signal of the electromagnetic ultrasonic transducer in the damped, limited, high-voltage isolation circuit of Example 4;

[0036] Figure 6 This is the thickness measurement signal of the same sample at the same location by the electromagnetic ultrasonic transducer of the high-voltage isolation circuit in Example 4;

[0037] Figure 7 The thickness measurement signal of the piezoelectric ultrasonic transducer in the damped, limited, high-voltage isolation circuit of Example 5;

[0038] Figure 8 The image shows the thickness measurement signal of the same sample at the same location by the piezoelectric ultrasonic transducer with high-voltage isolation circuit in Example 5. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0040] Example 1

[0041] The present invention discloses an ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception, comprising a diode bias current control circuit and a diode interconnection circuit; the diode bias current control circuit is used to control and adjust the current flowing through the diodes in the diode interconnection circuit; the diode interconnection circuit is used to isolate the high-voltage power supply output network from the input network of the small-signal receiving circuit, or to connect the transducer output network with the input network of the small-signal receiving circuit.

[0042] The diode interconnection circuit includes diodes D1, D2, D11, and D12 and resistors R1 and R5. The first ends of resistors R1 and R5 are connected to the control terminal of the diode bias current control circuit. The second ends of resistors R1 and R5 are connected to the two ends of the high-voltage power supply output network through diodes D1 and D11, respectively. The second ends of resistors R1 and R5 are also connected to the two ends of the input network of the ultrasonic signal receiving circuit through diodes D2 and D12, respectively.

[0043] like Figure 1 , Figure 2 As shown, the diode interconnection circuits adopt type I and type II circuits respectively.

[0044] Figure 1 In the Type I circuit: the cathodes of diodes D1 and D2 are connected to resistor R1, and the cathodes of diodes D11 and D12 are connected to resistor R5; the anodes of diodes D1 and D11 are connected to the two ends of the high-voltage power supply output network respectively; the anodes of diodes D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit respectively.

[0045] Figure 2In the Type II circuit: the anodes of diodes D1 and D2 are connected to resistor R1, and the anodes of diodes D11 and D12 are connected to resistor R5; the cathodes of diodes D1 and D11 are connected to the two ends of the high-voltage power supply output network, respectively; the cathodes of diodes D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit, respectively.

[0046] The diode bias current control circuit includes a high-voltage bipolar transistor Q1, static bias resistors R2 and R3, and a negative feedback resistor R4. The static bias resistors R2 and R3 are connected in series, with the other end of R2 grounded. R3 is connected to -12V in type I circuits and to +12V in type II circuits. The base of the high-voltage bipolar transistor Q1 is connected to the common junction of R2 and R3, and its emitter is connected to one end of R4. The other end of R4 is connected to the VEE power supply controlled by the system processor. In type I circuits, the VEE power supply outputs 0V or -12V; in type II circuits, it outputs 0V or +12V. The collector is connected to the control terminal of the diode interconnect circuit. By controlling the output of the VEE power supply, the operating state of Q1 is quickly controlled: Q1 is cut off or Q1 outputs a constant current. In these two states, the collector of Q1 outputs different bias currents, ultimately controlling the forward bias current of the diode in the diode interconnect circuit.

[0047] The anodes of diodes D1 and D11 are also connected to the two ends of the transducer output network, respectively. The transducer output network includes electromagnetic transducers L1_1 and L1_2. One end of electromagnetic transducers L1_1 and L1_2 is connected to the anodes of diodes D1 and D11, respectively, and the other end is grounded together; the anodes of D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit, respectively.

[0048] Example 2

[0049] like Figure 3 , Figure 4 The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception described in this embodiment includes piezoelectric transducers Y1_1 and Y1_2 in its transducer output network. One end of each piezoelectric transducer Y1_1 and Y1_2 is connected to the anodes of diodes D1 and D11, respectively, and the other end is grounded together. The anodes of D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit, respectively.

[0050] Example 3

[0051] Reference Figure 1 and Figure 2 The circuit scheme of Embodiment 1 shown in this embodiment describes the operation of the high-voltage isolation and low-loss output circuit of the transducer as follows:

[0052] (1) The system processor controls the VEE output to 0V, the emitter voltage of transistor Q1 is 0V, and the base voltage of Q1 is set by bias resistors R2 and R3. In type I circuit, the base voltage of Q1 is -11.04V, and in type II circuit, the base voltage of Q1 is +11.04V. At this time, the emitter junction of Q1 is reverse biased, the collector junction is reverse biased, Q1 enters the cutoff state, and there is no effective constant current output from the collector of Q1. Diodes D1, D2 and D11, D12 also have no effective DC bias current. Therefore, the impedance of the two paths from the positive terminal of D1 to the positive terminal of D2 and from the positive terminal of D11 to the positive terminal of D12 is high impedance for both AC and DC signals. At this time, the high voltage pulse output by the system processor can only be formed through the transducer coil to ground to complete this high voltage transmission.

[0053] (2) After the high-voltage emission ends, the system processor controls the VEE output. The VEE output of the type I circuit is -12V, and the VEE output of the type II circuit is +12V. The emitter voltage of transistor Q1 is -11.65V for the type I circuit and +11.65V for the type II circuit. At this time, the emitter junction of Q1 is forward biased, and the collector junction is reverse biased. Q1 enters the linear amplification state. R4 converts the emitter current of Q1 into a voltage and connects it in series with the base voltage of Q1 to form negative feedback, stabilizing the static operating voltage and current of Q1. The collector output of Q1 has a constant current, which forms a DC loop through four low-impedance paths, namely: The ultrasonic signal receiving circuit connects to ground via R1 and D1, electromagnetic transducer L1_1; to ground via R1 and D2, ultrasonic signal receiving circuit input terminal; to ground via R5 and D11, electromagnetic transducer L1_2; and to ground via R5 and D12, ultrasonic signal receiving circuit input terminal. At this point, diodes D1, D2, D11, and D12 have a constant forward bias current. Relative to the small AC signal output by the transducer, D1, D2, D11, and D12 are conducting and have very low impedance. Therefore, the transducer and the ultrasonic signal receiving circuit input terminal achieve low-impedance connection through D1, D2, D11, and D12, completing the reception of the ultrasonic echo.

[0054] Example 4

[0055] like Figure 5 , Figure 6 In this embodiment, a novel high-voltage isolation and low-loss transducer output circuit was implemented together with a damped and limited high-voltage isolation circuit, and the effects were compared. Figure 5 It is a thickness measurement signal obtained by applying a damping limiting circuit on an electromagnetic ultrasonic transducer. Figure 6 The thickness measurement signal was obtained by applying the novel high-voltage isolation and low-loss transducer output circuit disclosed in this invention, while keeping almost all conditions unchanged. It can be seen that the signal amplitude increased after adopting the novel high-voltage isolation and low-loss transducer output circuit disclosed in this invention.

[0056] Example 5

[0057] like Figure 7 , Figure 8 In this embodiment, a novel high-voltage isolation and low-loss transducer output circuit was implemented together with a commonly used damped and limited high-voltage isolation circuit, and the effects were compared. Figure 7 The thickness measurement signal is obtained by applying a damping limiting circuit to two piezoelectric ultrasonic transducers connected in series. Figure 8 The thickness measurement signal is obtained by applying the novel high-voltage isolation and low-loss transducer output circuit disclosed in this invention while keeping almost all conditions unchanged. The first wave and its generated periodic wave are the matching layer signal, while the other waves are the effective thickness signal. It can be seen that the signal amplitude increases after using the novel high-voltage isolation and low-loss transducer output circuit disclosed in this invention.

[0058] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. An ultrasonic electronic device circuit that isolates high-voltage transmission and small-signal reception, characterized in that, Includes diode bias current control circuit and diode interconnection circuit; The diode bias current control circuit is used to control and adjust the current flowing through the diodes in the diode interconnection circuit. The diode interconnection circuit is used to isolate the high-power high-voltage power supply output circuit and the ultrasonic signal receiving circuit, and to connect the transducer output network and the ultrasonic signal receiving circuit. The diode bias current control circuit includes a transistor Q1, static bias resistors R2 and R3, and a negative feedback resistor R4. The static bias resistors R2 and R3 are connected in series, with their common terminal connected to the base of transistor Q1. The other end of R2 is grounded, and the other end of R3 is connected to -VCC or +VCC. The emitter of transistor Q1 is connected to one end of R4, and the other end of R4 is connected to the VEE power supply controlled by the system processor. The collector of transistor Q1 is connected to the control terminal of the diode interconnect circuit. The diode interconnection circuit includes diodes D1, D2, D11, and D12 and resistors R1 and R5. The first ends of resistors R1 and R5 are connected to the output terminal of the diode bias current control circuit. The second ends of resistors R1 and R5 are connected to the two ends of the high-voltage power supply output network through diodes D1 and D11, respectively. The second ends of resistors R1 and R5 are also connected to the two ends of the input network of the ultrasonic signal receiving circuit through diodes D2 and D12, respectively.

2. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 1, characterized in that, The diode interconnection circuit adopts a type I circuit or a type II circuit; In the type I circuit: the cathodes of diodes D1 and D2 are connected to resistor R1, and the cathodes of diodes D11 and D12 are connected to resistor R5; the anodes of diodes D1 and D11 are respectively connected to the two ends of the high-voltage power supply output network; the anodes of diodes D2 and D12 are respectively connected to the two ends of the input network of the ultrasonic signal receiving circuit. In the Type II circuit: the anodes of diodes D1 and D2 are connected to resistor R1, and the anodes of diodes D11 and D12 are connected to resistor R5; the cathodes of diodes D1 and D11 are connected to the two ends of the high-voltage power supply output network, respectively; the cathodes of diodes D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit, respectively.

3. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 2, characterized in that, In the diode bias current control circuit, the other end of R3 is connected to -VCC voltage in type I circuit and to +VCC voltage in type II circuit; the VEE power supply outputs 0V or -VCC in type I circuit and 0V or +VCC in type II circuit.

4. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 1, characterized in that, The transducer output network is an electromagnetic transducer L1_1, L1_2 or a piezoelectric transducer Y1_1, Y1_2.

5. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 4, characterized in that, When the output network of the transducer is an electromagnetic transducer L1_1 and L1_2, in type I circuit, one end of the electromagnetic transducer L1_1 and L1_2 is connected to the anode of diodes D1 and D11 respectively, and the other end is grounded together; in type II circuit, one end of the electromagnetic transducer L1_1 and L1_2 is connected to the cathode of diodes D1 and D11 respectively, and the other end is grounded together.

6. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 4, characterized in that, When the transducer output network is a piezoelectric transducer Y1_1 and Y1_2; in type I circuit, one end of piezoelectric transducer Y1_1 and Y1_2 is connected to the anode of diode D1 and D11 respectively, and the other end is grounded together; in type II circuit, one end of piezoelectric transducer Y1_1 and Y1_2 is connected to the cathode of diode D1 and D11 respectively, and the other end is grounded together.

7. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 1, characterized in that, When the system processor controls the VEE power supply to output 0V, the transistor Q1 in the diode bias current control circuit is cut off, the collector does not provide static current output, the diode in the diode interconnection circuit has no forward bias current, and the positive-to-positive branch of the two series diodes and the negative-to-emitter branch of the two series diodes are both in a cut-off isolation state. At this time, the system processor controls the high-voltage transmitting power supply to output a high-voltage pulse to form a loop to ground through the low-impedance transducer coil, thus completing the high-voltage transmission. After the high-voltage transmission cycle ends, the system processor controls the output of the VEE power supply. In the type I circuit, the VEE outputs -VCC, and in the type II circuit, it outputs +VCC. The transistor Q1 in the diode bias current control circuit is turned on, and the negative feedback resistor R4 stabilizes the static operating voltage and current of Q1. The collector of Q1 provides a constant static current output. The diodes in the diode interconnect circuit generate bias current. For the small AC signal output by the transducer, the two series diodes are in the conducting state. At this time, the two input terminals of the transducer and the ultrasonic signal receiving circuit are in the conducting connection state, completing the reception of the ultrasonic echo.

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