Ultrasonic electronic equipment circuit for isolating high-voltage transmission from small signal reception

Abstract

Disclosed in the present invention is an ultrasonic electronic equipment circuit for isolating high-voltage transmission from small signal reception, which is characterized by comprising a diode bias current control circuit and a diode interconnection circuit, the diode bias current control circuit being used for controlling and regulating the current flowing through diodes in the diode interconnection circuit, and the diode interconnection circuit being used for isolating a high-voltage power output network from an input network of a small signal receiving circuit or connecting a transducer output network to the input network of the small signal receiving circuit. The present invention uses program control to enable or disenable the direct-current bias current of two diodes connected in series so as to turn off and turn on the diodes; when the direct-current bias current of the diodes are disenabled, the diodes are turned off so as to isolate a high-voltage power supply from the receiving circuit; when the direct-current bias current of the two diodes are enabled, the diodes are turned on and have very low alternating current impedance, so as to communicate an output signal of an ultrasonic transducer to the small signal receiving circuit at very low impedance.

Description

An ultrasonic electronic device circuit that isolates high-voltage transmission and small-signal reception Technical Field

[0001] The present invention relates to the technical field of ultrasonic measurement, in particular to an ultrasonic electronic equipment circuit for isolating high-voltage transmission and small-signal reception. Background Art

[0002] Industrial ultrasonic testing applications sometimes require higher ultrasonic transmission power, simpler and more reliable transducer structures, and more sensitive signal receiving electronics. These objectives constrain technical parameters, and sometimes meeting one requirement requires sacrificing other specifications. For example, increasing ultrasonic transmission power often increases the receiving signal's blind spot and the size of the electronics. Splitting the transducer into two physical components, transmitting and receiving, to reduce this blind spot increases the transducer's structural complexity. Increasing signal sensitivity solely by increasing the signal receiving gain also increases noise. Meeting the application goals of ultrasonic testing equipment end users requires finding a balance among numerous technical specifications.

[0003] In a self-transmitting and self-receiving ultrasonic detection electronic system, the received signal is usually 2 to 6 orders of magnitude lower than the transmitted signal, so the transmitted signal is considered a high-voltage signal to any received signal. Therefore, it is particularly important to isolate the circuit module for high-voltage transmission and small-signal reception.

[0004] Taking electromagnetic ultrasonic testing equipment as an example, existing electromagnetic ultrasonic technology requires the use of a high-power, high-voltage power supply to excite a transducer placed in a constant magnetic field and on the surface of the workpiece, thereby generating ultrasonic waves on the surface of the workpiece. The ultrasonic waves propagate inside the workpiece, and the reflected ultrasonic waves pass through the transducer coil placed in the constant magnetic field again to generate a weak voltage signal, which is input to the back-end small signal processing circuit. After analog conditioning and software analysis, the detection results are obtained. The high voltage generated by the transmitting circuit is usually on the order of 100V, while the small signal generated by the receiving circuit is usually on the order of 10uV. It can be seen that the interference of the high-voltage transmitting circuit on the small signal receiving circuit may be very large. Therefore, the high-power, high-voltage power supply needs to be isolated from the small signal processing circuit at the back end, and at the same time, the transducer coil and the back-end small signal circuit need to maintain an effective low-impedance connection path;

[0005] Existing mainstream piezoelectric ultrasonic and electromagnetic ultrasonic electronic devices use damping and limiting to isolate high voltage and output small signals. This is achieved by connecting a resistor of several hundred ohms in series between the high-voltage power supply and the input of the small-signal receiving circuit. A pair of positive and negative parallel fast-recovery small-signal diodes are connected to ground at the junction of the resistor and the input of the small-signal receiving circuit. The resistor carries the majority of the high-voltage voltage drop, while the pull-down diodes clamp the residual high-voltage voltage at the small-signal input to a safe level.

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

[0007] Taking the fully focused piezoelectric phased array detection equipment as an example, each measurement of each array element requires a self-transmitting and self-receiving measurement. If the transmitting voltage is too large, the small signal blind area will also be too large, thus missing important information about near-surface sample defects.

[0008] Summary of the Invention

[0009] In response to the above-mentioned technical problems, the purpose of the present invention is to provide an ultrasonic electronic equipment circuit that isolates high-voltage transmission and small-signal reception, instead of using series resistors and limiting diodes to isolate the high-voltage output of the high-voltage power supply from the small-signal receiving circuit, thereby reducing the equivalent output impedance of the transducer, enhancing the signal-to-noise ratio, and reducing the blind spot of the ultrasonic transducer signal that is self-transmitted and self-received.

[0010] The technical solution of the present invention is:

[0011] 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;

[0012] The diode bias current control circuit is used to control and adjust the current flowing through the diodes in the diode interconnection circuit;

[0013] The diode interconnection circuit is used to isolate the high-power and high-voltage power supply output circuit and the ultrasonic signal receiving circuit, and connect the transducer output network and the ultrasonic signal receiving circuit.

[0014] Preferably, the diode interconnection circuit includes diodes D1, D2, D11, D12 and resistors R1 and R5, wherein the first ends of the resistors R1 and R5 are commonly connected to the control end of the diode bias current control circuit; the second ends of the 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 the 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.

[0015] Preferably, the diode interconnection circuit adopts a type I circuit or a type II circuit;

[0016] In the I-type 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.

[0017] In the type II circuit: the anodes of diodes D1 and D2 are commonly connected to resistor R1, and the anodes of diodes D11 and D12 are commonly connected to resistor R5; the cathodes of diodes D1 and D11 are respectively connected to the two ends of the high-voltage power supply output network; and the cathodes of diodes D2 and D12 are respectively connected to the two ends of the input network of the ultrasonic signal receiving circuit.

[0018] Preferably, the diode bias current control circuit includes a transistor Q1, static bias resistors R2 and R3 and a negative feedback resistor R4, wherein the static bias resistors R2 and R3 are connected in series, the other end of R2 is grounded, and the other end of R3 is connected to the -VCC voltage in the I type circuit and to the +VCC voltage in the II type circuit; the base of the transistor Q1 is connected to the common point 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 the I type circuit and outputs 0V or +VCC in the II type circuit, and the collector is connected to the control end of the diode interconnection circuit.

[0019] Preferably, when the transducer output network is electromagnetic transducers L1_1 and L1_2;

[0020] In the I-type circuit, one end of the electromagnetic transducers L1_1 and L1_2 is connected to the anodes of the diodes D1 and D11 respectively, and the other ends are grounded;

[0021] In the type II circuit, one end of the electromagnetic transducers L1_1 and L1_2 is connected to the cathodes of the diodes D1 and D11 respectively, and the other end is grounded.

[0022] Preferably, when the transducer output network is piezoelectric transducers Y1_1 and Y1_2;

[0023] In the I-type circuit, one end of the piezoelectric transducers Y1_1 and Y1_2 is connected to the anodes of the diodes D1 and D11 respectively, and the other ends are grounded.

[0024] In the type II circuit, one end of the piezoelectric transducers Y1_1 and Y1_2 is connected to the cathodes of the diodes D1 and D11 respectively, and the other end is grounded.

[0025] 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 a 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-connected diodes and the negative-to-transistor emitter branch of the two series-connected 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 through the low-impedance transducer coil to form a loop to the ground, thereby completing the high-voltage transmission;

[0026] After the high-voltage transmission cycle ends, the system processor controls the output of the VEE power supply. In the type I circuit, 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 current of Q1. The collector provides a constant static current output, and the diode in the diode interconnection circuit generates a bias current. For the small AC signal output by the transducer, the two series-connected diodes are in the on state. At this time, the two input terminals of the transducer and the ultrasonic signal receiving circuit are in the on-connection state, completing the reception of the ultrasonic echo.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] 1. The present invention adopts a novel high-voltage isolation and low-impedance small-signal output interface circuit. It uses program control to open or close the DC bias current of two series-connected diodes to achieve diode cutoff and conduction. It also 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.

[0029] 2. The present invention realizes a circuit structure design that realizes high-impedance isolation and low-impedance connection by time-sharing diode interconnection circuit;

[0030] 3. The present invention realizes the rapid startup and rapid shutdown of the diode bias current control circuit; BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0032] FIG1 is a schematic diagram of a high-voltage isolated I-type circuit connected to an electromagnetic transducer in Example 1;

[0033] FIG2 is a schematic diagram of a high-voltage isolation type II circuit connected to an electromagnetic transducer in Example 1;

[0034] FIG3 is a schematic diagram of a high-voltage isolated I-type circuit connected to a piezoelectric transducer in Example 2;

[0035] FIG4 is a schematic diagram of a high-voltage isolation type II circuit connected to a piezoelectric transducer in Example 2;

[0036] FIG5 is a thickness measurement signal of the electromagnetic ultrasonic transducer of the damping and limiting high-voltage isolation circuit in Example 4;

[0037] FIG6 is a thickness measurement signal of the electromagnetic ultrasonic transducer of the high-voltage isolation circuit for the same position of the same sample in Example 4;

[0038] FIG7 is a thickness measurement signal of a piezoelectric ultrasonic transducer of a damped and limited high-voltage isolation circuit in Example 5;

[0039] FIG8 is a thickness measurement signal of the piezoelectric ultrasonic transducer of the high-voltage isolation circuit in Example 5 for the same position of the same sample. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0041] Example 1

[0042] 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.

[0043] The diode interconnection circuit includes diodes D1, D2, D11, and D12 and resistors R1 and R5, wherein the first ends of the resistors R1 and R5 are commonly connected to the control end of the diode bias current control circuit; the second ends of the resistors R1 and R5 are respectively connected to the two ends of the high-voltage power supply output network through diodes D1 and D11; and the second ends of the 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.

[0044] As shown in FIG1 and FIG2 , the diode interconnection circuits respectively adopt a Type I circuit and a Type II circuit.

[0045] In the I-type circuit of Figure 1 , 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.

[0046] In the type II circuit of Figure 2: the anodes of diodes D1 and D2 are commonly connected to resistor R1, and the anodes of diodes D11 and D12 are commonly connected to resistor R5; the cathodes of diodes D1 and D11 are respectively connected to the two ends of the high-voltage power supply output network; and the cathodes of diodes D2 and D12 are respectively connected to the two ends of the input network of the ultrasonic signal receiving circuit.

[0047] 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 a type I circuit and to +12V in a type II circuit. The base of the high-voltage bipolar transistor Q1 is connected to the common point of R2 and R3, the emitter is connected to one end of R4, and the other end of R4 is connected to a VEE power supply controlled by a system processor. In the type I circuit, the VEE power supply outputs 0V or -12V, and in the type II circuit, the VEE power supply outputs 0V or +12V. The collector is connected to the control end of the diode interconnection circuit. By controlling the VEE power supply output, the operating state of Q1 is quickly controlled: Q1 is cut off or Q1 outputs a constant current. In these two states of Q1, the collector of Q1 outputs different bias currents, ultimately achieving control of the forward bias current of the diode in the diode interconnection circuit.

[0048] The anodes of diodes D1 and D11 are also connected to the two ends of the transducer output network, which includes electromagnetic transducers L1_1 and L1_2. Electromagnetic transducers L1_1 and L1_2 have one end connected to the anodes of diodes D1 and D11, respectively, and the other end connected to a common ground. The anodes of diodes D2 and D12 are connected to the two ends of the input network of the ultrasonic signal receiving circuit, respectively.

[0049] Example 2

[0050] As shown in Figures 3 and 4 , the ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception in this embodiment includes piezoelectric transducers Y1_1 and Y1_2. One end of each piezoelectric transducer is connected to the anodes of diodes D1 and D11, respectively, and the other end is grounded. The anodes of diodes D2 and D12 are connected to the input network of the ultrasonic signal receiving circuit, respectively.

[0051] Example 3

[0052] 1 and 2 , the circuit scheme of Example 1 is shown in FIG. 1 and FIG. 2 . The working process of the high-voltage isolation and transducer low-loss output circuit is as follows:

[0053] (1) The system processor controls VEE to output 0V, the emitter voltage of transistor Q1 is 0V, and the base voltage of Q1 is set by bias resistors R2 and R3. In the type I circuit, the base voltage of Q1 is -11.04V, and in the 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, and Q1 enters the cut-off state. There is no effective constant current output from the collector of Q1, and there is no effective DC bias current from diodes D1, D2 and D11, D12. Therefore, the impedance of the two paths from the positive pole of D1 to the positive pole of D2 and from the positive pole of D11 to the positive pole of D12 are both high impedance to AC and DC signals. At this time, the system processor controls the high-voltage power supply to output high-voltage pulses, which can only form a loop through the transducer coil to the ground to complete this high-voltage transmission.

[0054] (2) After the high voltage emission is completed, 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 the 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 current of Q1. The collector of Q1 outputs a constant current, which forms a DC loop through four low impedance paths, namely: through R 1, D1, electromagnetic transducer L1_1 to ground; through R1, D2, the input end of the ultrasonic signal receiving circuit to ground, through R5, D11, the electromagnetic transducer L1_2 to ground; through R5, D12, the input end of the ultrasonic signal receiving circuit to ground. At this time, D1, D2 and D11, D12 diodes have a constant forward bias current. Relative to the small AC signal output by the transducer, D1, D2, D11, D12 are conductive and have very low impedance. Therefore, the transducer and the input end of the ultrasonic signal receiving circuit are connected at low impedance through D1, D2, D11, D12, completing the reception of ultrasonic echoes.

[0055] Example 4

[0056] As shown in Figures 5 and 6, in this embodiment, a novel high-voltage isolation and low-loss transducer output circuit is implemented alongside a damping and limiting high-voltage isolation circuit for comparison. Figure 5 shows the thickness measurement signal obtained by applying the damping and limiting circuit to the electromagnetic ultrasonic transducer; Figure 6 shows the thickness measurement signal obtained by applying the novel high-voltage isolation and low-loss transducer output circuit disclosed in this invention. It can be seen that the signal amplitude increases after adopting the novel high-voltage isolation and low-loss transducer output circuit disclosed in this invention.

[0057] Example 5

[0058] As shown in Figures 7 and 8, in this embodiment, a novel high-voltage isolation and transducer low-loss output circuit is implemented together with a damping and limiting high-voltage isolation circuit to compare their effects. Figure 7 shows the thickness measurement signal obtained by applying the damping and limiting circuit to two piezoelectric ultrasonic transducers connected in series; Figure 8 shows the thickness measurement signal obtained by applying the novel high-voltage isolation and transducer low-loss output circuit disclosed in this invention. The first wave and the periodic waves generated by it are matching layer signals, and the other waves are effective thickness signals. It can be seen that after adopting the novel high-voltage isolation and transducer low-loss output circuit disclosed in this invention, the signal amplitude has increased.

[0059] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. An ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception, characterized in that: It includes 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-power and high-voltage power supply output circuit and the ultrasonic signal receiving circuit, and connect the transducer output network and the ultrasonic signal receiving circuit.

2. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 1 is characterized in that: The diode interconnection circuit includes diodes D1, D2, D11, D12 and resistors R1, R5, wherein the first ends of the resistors R1, R5 are connected to the output end of the diode bias current control circuit; the second ends of the resistors R1, R5 are connected to the two ends of the high-voltage power supply output network through the diodes D1, D11 respectively; the second ends of the resistors R1, R5 are also connected to the two ends of the input network of the ultrasonic signal receiving circuit through the diodes D2, D12 respectively.

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

4. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 1, characterized in that: The diode bias current control circuit includes a transistor Q1, static bias resistors R2, R3 and a negative feedback resistor R4, wherein the static bias resistors R2 and R3 are connected in series, a common end is connected to the base of the transistor Q1, the other end of R2 is grounded, the other end of R3 is connected to a -VCC voltage in a type I circuit and to a +VCC voltage in a type II circuit; the emitter of the transistor Q1 is connected to one end of R4, the other end of R4 is connected to a VEE power supply controlled by a system processor, the VEE power supply outputs 0V or -VCC in the type I circuit and outputs 0V or +VCC in the type II circuit, and the collector of the transistor Q1 is connected to the control end of the diode interconnection circuit.

5. 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.

6. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 5, characterized in that: When the transducer output network is electromagnetic transducers L1_1 and L1_2, in a type I circuit, one end of the electromagnetic transducers L1_1 and L1_2 is connected to the anodes of diodes D1 and D11 respectively, and the other end is grounded in common; in a 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 in common.

7. The ultrasonic electronic device circuit for isolating high-voltage transmission and small-signal reception according to claim 5, characterized in that: When the transducer output network is piezoelectric transducers Y1_1 and Y1_2; in a type I circuit, one end of the piezoelectric transducers Y1_1 and Y1_2 are respectively connected to the anodes of diodes D1 and D11, and the other end is commonly grounded; in a type II circuit, one end of the piezoelectric transducers Y1_1 and Y1_2 are respectively connected to the cathodes of diodes D1 and D11, and the other end is commonly grounded.

8. 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 a static current output, the diode in the diode interconnection circuit has no forward bias current, and the positive electrode to positive electrode branch of the two series-connected diodes and the negative electrode to transistor emitter branch of the two series-connected diodes are all 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 through the low-impedance transducer coil to the ground to form a loop, 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, 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 current of Q1. The collector of Q1 provides a constant static current output. The diode in the diode interconnection circuit generates a bias current. For the small AC signal output by the transducer, the two series diodes are in a conductive state. At this time, the two input ends of the transducer and the ultrasonic signal receiving circuit are in a conductive connection state, completing the reception of ultrasonic echoes.

Images