Electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency and control method

Abstract

The invention discloses an electronic circuit and a control method for improving electromagnetic ultrasonic transmitting power and receiving efficiency, an electromagnetic ultrasonic transducer adopts N sub-coils as an integral mother coil, and when high voltage is transmitted, the N sub-coils are connected in parallel by using the electronic circuit and are connected to a high-voltage power supply output network; when a signal is received, the electronic circuit connects the N sub-coils in series to form a large coil for receiving an electromagnetic ultrasonic echo signal so as to enhance an electromotive force signal received in the coil. According to the control circuit, the impedance of the transducer is reduced during high-voltage emission, the power of a power supply obtained by the transducer is improved, an ultrasonic echo signal output by the transducer is increased during receiving, differential symmetric output of a transducer signal is realized, common-mode noise of the transducer is suppressed, and the signal-to-noise ratio of a received signal is improved. The problem that the signal-to-noise ratio of electromagnetic ultrasonic echo signals is not high due to the fact that the conversion efficiency of the same transducer is difficult to further improve on the basis of an existing electromagnetic ultrasonic technology is solved.

Description

Technical Field

[0001] The invention relates to the field of ultrasonic nondestructive testing, and in particular to an electronic circuit and a control method for improving electromagnetic ultrasonic transmitting power and receiving efficiency. Background Art

[0002] Since its emergence, electromagnetic ultrasonic transducer technology has greatly enriched the application field of ultrasonic testing equipment, especially in recent years, it has been widely used in industrial production. The advantages of electromagnetic ultrasonic transducer technology include: no coupling agent is required during detection, the detection process is fast, and there is no damage to the tested parts. The application of electromagnetic ultrasonic transducer technology has made a great contribution to ensuring the safety of industrial equipment, improving the safety of production and the yield rate of industrial products, and extending the service life of industrial equipment;

[0003] Electromagnetic ultrasonic transducer technology usually uses a high-power high-voltage power supply to excite the transducer in a constant magnetic field and on the surface of the workpiece to be measured, so as to generate ultrasonic waves in the workpiece to detect the workpiece. Since the conversion efficiency of the electromagnetic transducer is very low, the existing electromagnetic ultrasonic transducer technology generally uses a passive matching network between the transducer and the transmitting power supply to compensate for the low efficiency of the transducer, so as to increase the active power of the transducer receiving the high-voltage transmitting power supply, which improves the detection performance of the electromagnetic ultrasonic sensor instrument system to a certain extent. However, after the transducer is matched, when the frequency of the high-power high-voltage power supply is fixed, the impedance of the power supply is fixed and the power obtained is also constant; under some more severe working conditions, the signal-to-noise ratio of the echo signal of the workpiece to be measured is very poor, and no effective detection signal can be obtained. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide an electronic circuit for improving the electromagnetic ultrasonic transmission power and receiving efficiency, using a special electronic circuit to connect multiple sub-coils in parallel to the output end of an external high-power high-voltage power supply, which can receive more energy output by the high-voltage power supply than connecting these sub-coils in series into a large coil connected to the high-voltage power supply. Secondly, when receiving the signal, a special electronic circuit is used to connect the above-mentioned multiple sub-coils in series into a large coil to receive the electromagnetic ultrasonic echo signal in a very short time, so as to achieve the purpose of enhancing the amplitude of the output signal of the transducer coil.

[0005] The present invention solves two key technical difficulties:

[0006] (1) When the transducer is transmitting in parallel, the high voltage positive terminal and the high voltage negative terminal voltage at the common node of the transducer coil parallel connection are isolated.

[0007] (2) Circuit implementation method for converting the transducer from parallel connection to series connection.

[0008] The technical solution of the present invention is:

[0009] An electronic circuit for improving electromagnetic ultrasonic transmission power and receiving efficiency. The electromagnetic ultrasonic transducer uses N sub-coils as an integral mother coil. The N sub-coils are connected in parallel using an electronic circuit and connected to a high-voltage power supply output network. When receiving signals, the electronic circuit connects the N sub-coils in series into a large coil for receiving electromagnetic ultrasonic echo signals to enhance the electromotive force signal received in the coil.

[0010] Preferably, the electronic circuit includes N current-sinking diode bias current control circuits, N upper diode interconnection circuits, N lower diode interconnection circuits, N current-sourcing diode bias current control circuits, and 2N high-voltage signal return circuits;

[0011] The N sub-coils of the electromagnetic ultrasonic transducer are numbered 1, 2, ..., n, ..., N in order of arrangement, and each sub-coil contains two branch coils numbered Ln_1 and Ln_2; then:

[0012] The current-sinking diode bias current control circuit n is connected to the upper diode interconnection circuit n;

[0013] One end of the upper diode interconnection circuit n is connected to the opposite-name end of the branch coil L(n-1)_2 of the transducer sub-coil (n-1) and the high-voltage signal return circuit (n-1)_1, and the other end is connected to the same-name end of the branch coil Ln_1 of the transducer sub-coil n and the high-voltage power supply output network HVOUT-Ln_1;

[0014] The current sourcing diode bias current control circuit n is connected to the lower diode interconnection circuit n;

[0015] One end of the lower diode interconnection circuit n is connected to the opposite-name end of the branch coil Ln_1 of the transducer sub-coil n and the high-voltage signal return circuit n_2, and the other end is connected to the same-name end of the branch coil Ln_2 of the transducer sub-coil n and the high-voltage power supply output network HVOUT-Ln_2.

[0016] The above circuit features are:

[0017] [1] The current-injection diode bias current control circuit is used to control the presence or absence of bias current in the upper diode interconnection circuit connected to each transducer sub-coil;

[0018] [2] The upper diode interconnection circuit is used to isolate the two transducer sub-coils connected to the two ports of the upper diode interconnection circuit, or to connect the two sub-coils.

[0019] [3] The lower diode interconnection circuit is used to isolate the two transducer sub-coils connected to the two ports of the lower diode interconnection circuit, or to connect the two sub-coils.

[0020] [4] The current-sourcing diode bias current control circuit is used to control the presence or absence of bias current in the lower diode interconnection circuit connected to each transducer sub-coil;

[0021] [5] The high-voltage signal return circuit is used to connect the high-voltage signal to the ground loop when the high-voltage signal is transmitted, or to close the path between the small signal loop and the ground when the small signal is received.

[0022] Preferably, the N current-sinking diode bias current control circuits, wherein the current-sinking diode bias current control circuit n includes a transistor Qsrc_n, a bias resistor Rsrc-t_n, a Rsrc-b_n, a negative feedback resistor Rsrc-f_n, and a load resistor Rsrc_n; wherein the bias resistor Rsrc-t_n is connected in series with Rsrc-b_n, the common end is connected to the base of Qsrc_n, the other end of Rsrc-b_n is grounded, and the other end of Rsrc-t_n is connected to +12V; the emitter of the transistor Qsrc_n is connected to one end of the resistor Rsrc-f_n, and the other end of Rsrc-f_n is connected to VCC controlled by the system processor, and VCC outputs 0V or +12V; the collector of the transistor Qsrc_n is connected to one end of the load resistor Rsrc_n, and the other end of Rsrc_n is connected to the control end of the upper diode interconnection circuit n.

[0023] Preferably, the N upper diode interconnection circuits, wherein the upper diode interconnection circuit n includes diodes D-t1_n and D-t2_n; the positive electrode of diode D-t1_n is connected to the positive electrode of diode D-t2_n, and are connected together to Rsrc_n of the output end of the current injection type diode bias current control circuit n; the other end of D-t1_n is connected to the high-voltage signal return circuit (n-1)_1 and the opposite-name end of the L(n-1)_2 branch coil of the transducer sub-coil (n-1), and the other end of D-t2_n is connected to the high-voltage power supply output network HVOUT-Ln_1 and the same-name end of the Ln_1 branch coil of the transducer sub-coil n.

[0024] Preferably, the N current-sourcing diode bias current control circuits, wherein the current-sourcing diode bias current control circuit n includes a transistor Qsk_n, a bias resistor Rsk-t_n, a Rsk-b_n, a negative feedback resistor Rsk-f_n, and a load resistor Rsk_n; wherein the bias resistor Rsk-t_n is connected in series with Rsk-b_n, the common end is connected to the base of Qsk_n, the other end of Rsk-t_n is grounded, and the other end of Rsk-b_n is connected to a negative voltage of -12V; the emitter of the transistor Qsk_n is connected to one end of the resistor Rsk-f_n, and the other end of Rsk-f_n is connected to VEE controlled by the system processor, and VEE outputs 0V or -12V; the collector of the transistor Qsk_n is connected to one end of the load resistor Rsk_n, and the other end of Rsk_n is connected to the control end of the lower diode interconnection circuit n;

[0025] Preferably, the N lower-end diode interconnection circuits, wherein the lower-end diode interconnection circuit n includes diodes D-b1_n and D-b2_n; the cathode of diode Db1_n is connected to the cathode of diode D-b2_n, and are connected together to Rsk_n, the output end of the current-pulling diode bias current control circuit n; the other end of D-b1_n is connected to the high-voltage signal return circuit n_2 and the opposite-name end of the Ln_1 branch coil of the transducer sub-coil n, and the other end of D-b2_n is connected to the high-voltage power supply output network HVOUT-Ln_2 and the same-name end of the Ln_2 branch coil of the transducer sub-coil n.

[0026] Preferably, the 2N high-voltage signal return circuits; wherein the high-voltage signal return circuit n_1 includes D-hv-t1_n, D-hv-t2_n; the high-voltage signal return circuit n_2 includes D-hv-b 1_n, D-hv-b2_n.

[0027] A control method for an electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency, comprising:

[0028] Step S1: before the high voltage power supply is transmitted, the system controls VCC to output 0V, VEE to output 0V, the triodes of the current-injection type diode bias current control circuit are all cut off, and the triodes of the current-source type diode bias current control circuit are all cut off, so that the upper diode interconnection circuit connected to the current-injection type diode bias current control circuit has no bias current, and the upper diode interconnection circuit is in a cut-off state, and the lower diode interconnection circuit connected to the current-source type diode bias current control circuit has no bias current, and the lower diode interconnection circuit is in a cut-off state; at this time, the two transducer branch coils connected to the upper diode interconnection circuit port are isolated from each other; the two transducer branch coils connected to the lower diode interconnection circuit port are also isolated from each other;

[0029] At this time, the high-voltage pulse output by the high-voltage power supply can be loaded onto each sub-coil of the transducer. Under the magnetic field, the high-voltage pulse voltage excites all sub-coils to generate ultrasonic waves in the tested block, completing an ultrasonic emission.

[0030] Step S2: the high-voltage power supply stops outputting high-voltage pulses, the system controls VCC to output +12V, VEE to output -12V, the triodes of the current-injection type diode bias current control circuit are all turned on, and the collector outputs a constant current. At the same time, the triodes of the current-sourcing type diode bias current control circuit are also turned on, and the collector absorbs a constant current, thereby generating a bias current in the upper diode interconnection circuit connected to the current-injection type diode bias current control circuit, and generating a bias current in the lower diode interconnection circuit connected to the current-sourcing type diode bias current control circuit; therefore, the upper diode interconnection circuit and the lower diode interconnection circuit are both in a conducting state; at this time, the two transducer branch coils connected to the upper diode interconnection circuit port are connected at a low impedance; the two transducer branch coils connected to the lower diode interconnection circuit port are also connected at a low impedance, and all branch coils are connected in series and connected to the ultrasonic signal receiving circuit to complete the reception of a small ultrasonic signal.

[0031] Preferably, step S1 specifically includes:

[0032] When the system controls VCC and VE E to be 0V, the transistors Qsrc_1, Qsrc_2, Qsrc_n…Qsrc_N in the N current-sinking diode bias current control circuits are all in the cut-off state, and their collectors have no static current; the transistors Qsk_1, Qsk_2, Qsk_n…Qsk_N in the N current-sourcing diode bias current control circuits are all in the cut-off state, and their collectors have no static current; therefore, the N upper diode interconnection circuits connected to the N current-sinking diode bias current control circuits and the N lower diode interconnection circuits connected to the N current-sourcing diode bias current control circuits also have no bias current; therefore, the diodes in all the upper diode interconnection circuits are in the cut-off state, and the diodes in all the lower diode interconnection circuits are in the cut-off state; at this time, when the system controls high-voltage transmission, the high-voltage pulse is input from the same-name ends of the 2N branch coils of the N transducer sub-coils, and is connected to the ground after passing through the high-voltage return circuit connected to the opposite-name ends of the 2N branch coils to form a loop.

[0033] Preferably, step S2 specifically includes:

[0034] After the high-voltage transmission is completed, the system controls VCC to output +12V and VE E to output -12V; the transistors Qsrc_1, Qsrc_2, Qsrc_n…Qsrc_N in the N current-sinking diode bias circuits are in the on state, and the negative feedback resistors Rsrc-f_1, Rsrc-f_2, Rsrc-f_n…Rsrc-f_N stabilize the static working current of the transistors connected thereto. At this time, the collector of each transistor outputs a constant static current; at the same time, the transistors Qsk_1, Qsk_2, Qsk_n…Qsk_N in the N current-pulling diode bias current control circuits are in the on state, and the negative feedback resistors Rsk-f_1, Rsk-f_2, Rsk-f_n…Rsk-f_N stabilize the static working current of the transistors connected thereto, and the collector of each transistor absorbs a constant static current; therefore, the Ln_1 coil in the N sub-coils of the transducer is connected In the transmitting and receiving circuit, the collector output current of the transistor Qsrc_n in the current-sinking diode bias current control circuit n passes through D-t1_n of the upper diode interconnection circuit n to the opposite end of the L(n-1)_2 branch coil of the n-1th sub-coil, forming an AC signal low impedance path 2(n-1)+1; the current output by the collector of the transistor Qsrc_n in the current-sinking diode bias current control circuit n flows through the diode D-t2_n in the upper diode interconnection circuit n, the Ln_1 branch coil of the transducer sub-coil n, D-b1_n in the lower diode interconnection circuit n, and Rsk_n of the current-sourcing diode bias current control circuit, and finally converges into the collector of the transistor Qsk_n. At this time, the collector of the transistor Qsk_n in the current-sourcing diode bias current control circuit absorbs a constant current, thereby forming an AC signal low impedance path 2n;

[0035] At the same time, the current flowing into the collector of the transistor Qsk_n of the current-sourcing diode bias current control circuit n also passes through Rsk_n, D-b2_n of the lower diode interconnection circuit n, the Ln_2 branch coil of the transducer sub-coil n, D-t1_(n+1) of the upper diode interconnection circuit n+1, Rsrc_(n+1) of the current-injection diode bias current control circuit n+1, and finally connected to the collector of the transistor Qsrc_(n+1). At this time, the collector of Qsrc_(n+1) outputs a constant current, thereby forming an AC signal low-impedance path 2n+1; the current output by the collector of the transistor Qsrc_(n+1) in the current-injection diode bias current control circuit n+1 flows through the diode D-t2_(n+1) in the upper diode interconnection circuit n+1, the transducer sub-coil n, and Rsrc_(n+1) of the current-injection diode bias current control circuit n+1. The L(n+1)_1 branch coil of the transducer sub-coil n+1, D-b1_(n+1) in the lower diode interconnection circuit n+1, and Rsk_(n+1) of the current-pulling diode bias current control circuit are finally merged into the collector of the transistor Qsk_(n+1), forming an AC signal low-impedance path 2(n+1); the Ln_1 branch coil of the transducer sub-coil n is connected to the L(n-1)_2 branch coil of the previous sub-coil (n-1) through the above-mentioned low-impedance path 2(n-1)+1 and low-impedance path 2n, and the Ln_2 branch coil of the transducer sub-coil n and the L(n+1)_1 branch coil of the sub-coil n+1 are connected together through the low-impedance path 2n+1 and the low-impedance path 2(n+1), realizing the series connection of the sub-coil n with the previous sub-coil n-1 and the next sub-coil n+1;

[0036] By analogy, from the nth sub-coil forward to the transmitting and receiving circuit connected to the first sub-coil, the low impedance path 1 is a path formed by the collector of the transistor Qsrc_1 in the current-injection type diode bias current control circuit 1, the load resistor Rsrc_1, the diode D-t2_1 of the upper diode interconnection circuit 1, and the signal input positive electrode of the ultrasonic signal receiving circuit; the low impedance path 2 is a path formed by the collector of the transistor Qsrc_1 of the current-injection type diode bias current control circuit 1, Rsrc_1, D-t1_1 of the upper diode interconnection circuit 1, Ln_1 of the first sub-coil of the transducer, D-b1_1, Rsk_1, and Qsk_1 collectors of the lower diode interconnection circuit 1;

[0037] By analogy from the nth sub-coil backward to the transmitting and receiving circuit connected to the Nth sub-coil, the low impedance path 2N+1 is a path formed by the collector of the transistor Qsk_N in the current-pulling diode bias current control circuit N, the load resistor Rsk_N, the diode D-b2_N of the lower diode interconnection circuit N, the LN_2 branch coil of the sub-coil N, and the signal input cathode of the ultrasonic signal receiving circuit; the low impedance path 2N is a path formed by the collector of the transistor Qsrc_N of the current-injection diode bias current control circuit N, Rsrc_N, and the D-t2_N of the upper diode interconnection circuit 1. , LN_1 of the Nth sub-coil of the transducer, D-b1_N, Rsk_N, Qsk_N collectors of the lower diode interconnection circuit N form a path, so the 1st sub-coil to the Nth sub-coil are connected in series end to end through the low impedance loop 1, 2, ...2n, 2n+1...2N, 2N+1 to form a coil, one end of the coil is connected to the positive signal input terminal of the ultrasonic signal receiving circuit, and the other end is connected to the negative signal input terminal of the ultrasonic signal receiving circuit; thereby, 2N branch coils of the N sub-coils are connected in series and then connected to the ultrasonic signal receiving circuit to complete the external output of small signals.

[0038] Compared with the prior art, the advantages of the present invention are:

[0039] 1. The present invention manufactures an even number of 2N identical coils as a whole mother coil into the electromagnetic ultrasonic transducer, and uses a circuit to connect all the sub-coils of the transducer in parallel and then connect them to the transmitting high-voltage power supply circuit, thereby reducing the input impedance of the transducer, increasing the output power of the high-voltage power supply, and thus increasing the active power obtained by the transducer; when receiving, the circuit of the present invention connects all the sub-coils in the transducer in series in a very short time and then connects them to the ultrasonic signal receiving circuit; in this way, the amplitude of the ultrasonic echo signal is enhanced. The signal amplitude is increased to 4N compared to the signal amplitude of a single branch coil. 2 times, where 2N is the total number of coils.

[0040] 2. The present invention is a control circuit that reduces the impedance of the transducer during high-voltage transmission, increases the power supply power obtained by the transducer, increases the ultrasonic echo signal output by the transducer during reception, realizes the differential symmetrical output of the transducer signal, and improves the signal-to-noise ratio of the received signal. A plurality of identical sub-coils are manufactured in an electromagnetic ultrasonic sensor, and a program-controllable impedance conversion circuit is used to realize that the same-name ends of the plurality of sub-coils in the transducer are connected to the positive pole of the high-voltage power supply during high-voltage transmission, and the opposite-name ends of the plurality of sub-coils are connected to the negative pole of the high-voltage power supply, thereby reducing the impedance of the transducer and increasing the active power obtained by the transducer. When the high-voltage power supply stops transmitting and the same transducer needs to be used to receive a small ultrasonic signal, the same-name ends of each sub-coil in the transducer are connected to the opposite-name ends of the adjacent sub-coils under the control of the electronic circuit of the present invention, and the opposite-name ends of each sub-coil are connected to the same-name ends of the adjacent sub-coils, forming a mother coil connected to the signal input positive pole and the signal input negative pole of the ultrasonic signal receiving circuit; the problem that the conversion efficiency of the same transducer is difficult to further improve on the basis of the existing electromagnetic ultrasonic technology, resulting in a low signal-to-noise ratio of the electromagnetic ultrasonic echo signal, is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0042] Figure 1 It is a circuit block diagram of an electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency of the present invention;

[0043] Figure 2 yes Figure 1 Schematic diagram of circuit part A;

[0044] Figure 3 yes Figure 1 Schematic diagram of circuit part B;

[0045] Figure 4 yes Figure 1 Schematic diagram of circuit part C;

[0046] Figure 5 It is an equivalent circuit diagram of the present invention for controlling multiple coils of an electromagnetic ultrasonic transducer to realize parallel transmission and series reception;

[0047] Figure 6 It is an equivalent circuit of a typical coil or two coils connected to an electromagnetic ultrasonic transducer electronic device before the disclosure of the present invention;

[0048] Figure 7 It is a comparison of the effects of the electronic circuit scheme of the present invention and the previous typical electromagnetic ultrasonic transducer electronic circuit scheme when the transmitting voltage and receiving gain are equal. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is 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 only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0050] The following is a further description and verification with specific examples.

[0051] Example 1

[0052] like Figure 1 The electronic circuit for improving electromagnetic ultrasound transmission power and receiving efficiency of the present invention comprises circuit parts A, B and C. Among them:

[0053] Circuit part A: It is the circuit diagram of the first two branch coils in the N-branch coil parallel transmission and series receiving circuit, as shown in Figure 2 As shown;

[0054] Circuit part B: It is the circuit diagram of the nth branch coil in the circuit of N branch coils in parallel transmitting and series receiving, as shown in Figure 3 As shown;

[0055] Circuit part C: It is the circuit diagram of the Nth branch coil in the circuit of N branch coils connected in parallel to transmit and receive in series, as shown in Figure 4 shown.

[0056] The circuit part marked with ellipsis between circuit part A and circuit part B is the omitted circuit diagram of parallel transmission and series reception from the 3rd branch coil to the n-1th branch coil;

[0057] The circuit portion marked with ellipsis between circuit portion B and circuit portion C is an omitted circuit diagram of parallel transmission and series reception from the n+1th branch coil to the N-1th branch coil.

[0058] In this embodiment, a new type of electronic circuit controls multiple coils of an electromagnetic ultrasonic transducer to achieve parallel transmission and series reception; it includes a current injection type diode bias current control circuit, an upper diode interconnection circuit, a lower diode interconnection circuit, a current pulling type diode bias current control circuit, and a high-voltage signal return circuit.

[0059] [1] The current-sinking diode bias current control circuit comprises a PNP transistor, two resistors of a PNP transistor base bias circuit, a PNP transistor emitter negative feedback resistor, and a PNP transistor collector load resistor; specifically, the first current-sinking diode bias current control circuit is composed of: PNP P transistor Qsrc_1, transistor base bias circuit resistors Rsrc-t_1, Rsrc-b_1, Rsrc-t_1 and Rsrc-b_1 are connected to the base of Qsrc_1, the other end of Rsrc-t_1 is connected to +12V, and the other end of Rsrc-b_1 is grounded; Qsrc_1 emitter is connected to negative feedback resistor Rsrc-f_1, and the other end of Rsrc-f_1 is connected to VCC controlled by the system, and VCC outputs 0V or +12V; Qsrc_1 collector is connected to load resistor Rsrc_1, and the other end of Rsrc_1 is connected to the upper diode interconnection circuit, which is connected by R src_1 outputs a constant current; and by analogy, the nth current sink diode bias current control circuit n includes: a transistor Qsrc_n, resistors Rsrc-t_n, Rsrc-b_n, one end of Rsrc-t_n and Rsrc-b_n are connected to the base of Qsrc_n, the other end of Rsrc-t_n is connected to +12V, and the other end of Rsk-b_n is grounded; the emitter of Qsrc_n is connected to the feedback resistor Rsrc-f_n, and the other end of Rsrc-f_n is connected to VCC; the collector of Qsrc_n is connected to Rsrc_n, and the other end of Rsrc_n is connected to the upper diode interconnection circuit n.

[0060] [2] The upper diode interconnection circuit includes two diodes, the anodes of which are connected in series and connected to the output load resistor of the current-injection type diode bias current control circuit at the same time; specifically, the first two upper diode interconnection circuits are as follows: the first upper diode interconnection circuit is composed of D-t1_1 and D-t2_1, the anodes of D-t1_1 and D-t2_1 are connected together and connected to the output load resistor Rsrc_1 of the current-injection type diode bias current control circuit 1, and the cathode of D-t1_1 is connected to the same-name end of the transducer sub-coil L1_1, and the same-name end is also connected to the high-voltage The positive electrode HVOUT-L1_1 of the source, the cathode of D-t2_1 is connected to the signal input positive electrode of the ultrasonic receiving circuit; the second upper diode interconnection circuit is composed of D-t1_2 and D-t2_2, the anodes of D-t1_2 and D-t2_2 are connected together, and connected to the output load resistor Rsrc_2 of the current-sinking diode bias current control circuit 2, the cathode of D-t1_2 is connected to the opposite-name end of the transducer sub-coil L1_2, and the opposite-name end is simultaneously connected to the high-voltage signal return circuit 1_1, the cathode of D-t2_2 is connected to the same-name end of the adjacent sub-coil L2_1, and the same-name end of L2_1 is simultaneously connected Connected to the positive pole HVOUT-L2_1 of the high-voltage power supply; the nth upper diode interconnection circuit is composed of D-t1_n and D-t2_n. The anodes of D-t1_n and D-t2_n are connected together and connected to the output load resistor Rsrc_n of the current-sinking diode bias current control circuit n. The cathode of D-t1_n is connected to the opposite-name end of the transducer sub-coil L(n-1)_2, and the opposite-name end is also connected to the high-voltage signal return circuit (n-1)_1. The cathode of D-t2_n is connected to the same-name end of the next adjacent sub-coil Ln_1, and the same-name end of Ln_1 is also connected to the positive pole of the high-voltage power supply. Pole HVOUT-Ln_1; and so on to the Nth upper diode interconnection circuit N: including diodes D-t1_N, D-t2_N; the anodes of D-t1_N and D-t2_N are connected to the output load Rsrc_N of the current-sinking diode bias current control circuit N, the cathode of D-t1_N is connected to the opposite-name end of the N-1th sub-coil L(N-1)_2, and the opposite-name end is also connected to the high-voltage return circuit (N-1)_1, the cathode of D-t2_N is connected to the same-name end of the Nth sub-coil LN_1, and the same-name end is also connected to the positive electrode HVOUT-LN_1 of the high-voltage power supply.

[0061] [3] The lower diode interconnection circuit includes two diodes, the cathodes of which are connected in series and connected to the output load resistor of the current-sourcing diode bias current control circuit at the same time; specifically, the first two and the nth lower diode interconnection circuits are as follows: the lower diode interconnection circuit 1 is composed of D-b1_1 and D-b2_1, the cathodes of D-b1_1 and D-b2_1 are connected together and connected to the output load resistor Rsk_1 of the current-sourcing diode bias current control circuit 1 at the same time, the anode of D-b1_1 is connected to the opposite-name end of the transducer sub-coil L1_1, and the opposite-name end is connected to the high-voltage signal return circuit 1_2 at the same time; the anode of D-b2_1 is connected to the same-name end of the transducer sub-coil L1_2, and the same-name end is connected to the positive pole HVOUT-L1_2 of the high-voltage power supply at the same time. The lower diode interconnection circuit 2 is composed of D-b1_2 and D-b2_2. The cathodes of D-b1_2 and D-b2_2 are connected together and connected to the output load resistor Rsk_2 of the current-pulling diode bias current control circuit 2. The anode of D-b1_2 is connected to the opposite-name end of the transducer sub-coil L2_1, and the opposite-name end is connected to the high-voltage signal return circuit 2_2. The anode of D-b2_2 is connected to the same-name end of the transducer sub-coil L2_2, and the same-name end is connected to the positive electrode HVOUT-L2_2 of the high-voltage power supply. The lower diode interconnection circuit n is composed of D-b1_n and D-b2_n. The cathodes of D-b1_n and D-b2_n are connected together and connected to the output load resistor Rsk_n of the current-pulling diode bias current control circuit n. The anode of D-b1_n is connected to The opposite-name end of the transducer sub-coil Ln_1 is connected to the high-voltage signal return circuit n_2 at the same time, and the anode of D-b2_n is connected to the same-name end of the transducer sub-coil Ln_2, and the same-name end is connected to the positive electrode HVOUT-Ln_2 of the high-voltage power supply at the same time; and the same analogy is applied to the Nth lower diode interconnection circuit N: it includes diodes D-b1_N and D-b2_N; the cathodes of D-b1_N and D-b2_N are connected to the output load resistor Rsk_N of the current-pulling diode bias current control circuit N, the anode of D-b1_N is connected to the opposite-name end of the Nth sub-coil LN_1, and the opposite-name end is connected to the high-voltage return circuit N_2 at the same time, and the anode of D-b2_N is connected to the same-name end of the Nth sub-coil LN_2, and the same-name end is connected to the positive electrode HVOUT-LN_2 of the high-voltage power supply at the same time.

[0062] [4] The current-pulling diode bias current control circuit includes an NPN transistor, two resistors of the NPN transistor base bias circuit, an NPN transistor emitter negative feedback resistor, and an NPN transistor collector load resistor; the specific components of the current-pulling diode bias current control circuit 1 are: NPN transistor Qsk_1, transistor base bias circuit resistors Rsk-t_1, Rsk-b_1, one end of Rsk-t_1 and Rsk-b_1 are connected to the base of Qsk_1, the other end of Rsk-t_1 is grounded, and the other end of Rsk-b_1 is connected to -12V; the emitter of Qsk_1 is connected to the negative feedback resistor Rsk-f_1, and the other end of Rsk-f_1 is connected to the system-controlled VEE, and VEE outputs 0V or -12V; the collector of Qsk_1 is connected to the load resistor Rsk_1, and the other end of Rsk_1 is connected to the lower diode interconnection circuit 1, from Rsk_1 absorbs a constant current; and by analogy, the nth current-pulling diode bias current control circuit n includes: a transistor Qsk_n, resistors Rsk-t_n, Rsk-b_n, one end of Rsk-t_n and Rsk-b_n are connected to the base of Qsk_n, the other end of Rsk-t_n is grounded, and the other end of Rsk-b_n is connected to -12V; the emitter of Qsk_n is connected to the feedback resistor Rsk-f_n, and the other end of Rsk-f_n is connected to VEE; the collector of Qsk_n is connected to Rsk_n, and the other end of Rsk_n is connected to the lower diode interconnection circuit n.

[0063] [5] The high-voltage signal return circuit includes two diodes, wherein the anode of one diode and the cathode of the other diode are connected together and connected to the opposite ends of each sub-coil of the transducer, and the other ends of the two diodes are connected together and connected to the ground.

[0064] Example 2

[0065] In this embodiment, the working process of a circuit for controlling multiple sub-coils of an electromagnetic ultrasonic transducer to realize parallel transmission and serial reception is as follows:

[0066] Before high-power high-voltage transmission, the system controls VCC to output 0V and VEE to output 0V. At this time, the emitter junctions of the N P transistors Qsrc_1, Qsrc_2, Qsrc_n…Qsk_N in the N current-sinking diode bias current control circuits are all reverse biased, and the collector junctions are also reverse biased, so Qsrc_1, Qsrc_2, Qsrc_n…Qsrc_N are all in the cut-off state; at the same time, VEE outputs 0V, making the emitter junctions of the NPN transistors Qsk_1, Qsk_2, Qsk_n…Qsk_N in the N current-sourcing diode bias current control circuits reverse biased, and the collector junctions are reverse biased, so Qsk_1, Qsk_2, Qsk_n…Qsk_N are also in the cut-off state; and the N current-sinking diode bias current control circuits The N upper diode interconnection circuits connected to the circuit and the N lower diode interconnection circuits connected to the N current-pulling diode bias current control circuits have no forward bias current; therefore, all the upper diode interconnection circuits and the lower diode interconnection circuits are in a cut-off state, and the branch coils connected thereto are isolated from each other; at this time, the high voltage output of the high voltage power supply is input from the same-name end of each transducer branch coil, passes through the opposite-name end of each transducer branch coil, passes through each high voltage signal return circuit, and finally returns to the ground, forming a transmission loop of 2N high voltage signals, completing a transmission of 2N transducer branch coils connected in parallel to the high voltage power supply;

[0067] After the high voltage power supply stops outputting, the system controls VCC to output +12V and VEE to output -12V; the emitter junctions of the N PN P transistors Qsrc_1, Qsrc_2, Qsrc_n…Qsrc_N in the N current-sinking diode bias current control circuits are all forward biased, and the collector junctions are reverse biased, so Qsrc_1, Qsrc_2, Qsrc_n…Qsrc_N are all in an amplification state, and the collector of each PN P transistor outputs a constant DC current; at the same time, VEE outputs -12V, which makes the emitter junctions of the N PN transistors Qsk_1, Qsk_2, Qsk_n…Qsk_N in the N current-sourcing diode bias current control circuits forward biased, and the collector junctions reverse biased, Qsk_1, Qsk_2, Qsk_n…Qsk_N are also in an amplification state, and each N The collector of the PN transistor absorbs a constant DC current; the N upper diode interconnection circuits connected to the N current-sinking diode bias current control circuits and the N lower diode interconnection circuits connected to the N current-sourcing diode bias current control circuits generate a constant forward bias current; therefore, all the upper diode interconnection circuits and the lower diode interconnection circuits are in the on state, and the branch coils connected thereto are interconnected with each other, and this connection is achieved by connecting the like-name end of one coil with the opposite-name end of the other coil in two adjacent branch coils, so that the 2N branch coils are finally connected in series into one coil, which is connected to the ultrasonic signal receiving circuit to complete the reception of a small signal; specifically, the receiving circuit of each branch coil is as follows: the like-name end of the branch coil L1_1 is connected to the signal input positive pole of the ultrasonic signal receiving circuit through the upper diode interconnection circuit 1 , the opposite-name end of L1_1 is connected to the same-name end of branch coil L1_2 through the lower diode interconnection circuit 1; at the same time, the opposite-name end of branch coil L1_2 is connected to the same-name end of the next branch coil L2_1 through the upper diode interconnection circuit 2, and the opposite-name end of L2_1 is connected to the same-name end of branch coil L2_2 through the lower diode interconnection circuit 2; the opposite-name end of L2_2 is connected to branch coil L3_1 through the upper diode interconnection circuit 3, and the opposite-name end of L3_1 is connected to branch coil L3_2 through the lower diode interconnection circuit 3; the subsequent branch coils are connected to the last 2N branch coils in the same way through the upper diode interconnection circuits, and the lower diode interconnection circuits are finally connected to the last 2N branch coils, and the opposite-name end of branch coil LN_2 is finally connected to the signal input cathode of the ultrasonic signal receiving circuit, completing the output of the signal after the series connection of 2N branch coils.

[0068] Example 3

[0069] In this embodiment, we use the circuit disclosed in the present invention to control multiple branch coils of the electromagnetic ultrasonic transducer to realize parallel transmission and series reception to compare the effect with the previously commonly used electromagnetic ultrasonic transducer electronic circuit. The biggest feature of the electronic circuit disclosed in the present invention is that it can dynamically adjust the impedance of the electromagnetic ultrasonic transducer coil. The feature of the previously commonly used electromagnetic ultrasonic transducer electronic circuit is that once the transmission frequency is fixed, the impedance of the coil is fixed. In order to simplify the description, we can draw an equivalent transmission and reception circuit. Figure 6 (a) is an equivalent transmitting and receiving circuit diagram of an electromagnetic ultrasonic transducer coil connected to a commonly used electronic circuit; Figure 6 (b) The equivalent transmitting and receiving circuit diagrams of two coils connected in series in the previously commonly used electromagnetic ultrasonic transducer electronic circuit; Figure 6 (c) is the equivalent transmitting and receiving circuit diagram of two coils connected in parallel in the previously commonly used electromagnetic ultrasonic transducer electronic circuit.

[0070] Figure 7 (a) Yes Figure 6 (a) The test results are as follows: the outer diameter of the coil is 18 mm, the inner diameter is 6 mm, the electromagnetic ultrasonic transducer is 2 mm away from the workpiece surface, the transmitting frequency is 4.3 MHz, the gain is 73.3 dB, and the tested sample is 10 mm thick low-carbon steel. Figure 6 (b) and Figure 6 The test results of (c) are almost the same. We take one of the equivalent circuit structures as an example. Figure 7 (b) Yes Figure 6 (c) Use 2 Figure 6 (a) The test results of the same coil. We can see that compared Figure 7 (a) a single coil, Figure 7 (b) The signal amplitude obtained by the parallel transmitting and receiving double coils is twice that of the single coil. Figure 7 (c) is the electronic circuit of the present invention Figure 7 (a) shows the test results of two identical coils. The coil equivalent circuit diagram is shown in Figure 2 We can see that its signal amplitude is 4 times that of a single coil and 2 times that of a parallel transmitting and receiving coil. Figure 7 (d) is the circuit of the present invention Figure 7 (a) shows the test results of the four identical coils. The coil equivalent circuit is shown in Figure 2 , we can see that its signal amplitude is 16 times that of a single coil and 4 times that of a parallel transmitting and receiving coil.

Claims

1. An electronic circuit for improving electromagnetic ultrasonic transmission power and receiving efficiency, characterized in that: The electromagnetic ultrasonic transducer uses N sub-coils as an integral mother coil. When transmitting high voltage, the N sub-coils are connected in parallel using electronic circuits and connected to the high-voltage power supply output network; when receiving signals, the electronic circuit connects the above N sub-coils in series into a large coil for receiving electromagnetic ultrasonic echo signals to enhance the electromotive force signal received in the coil.

2. The electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 1, characterized in that: The electronic circuit includes N current-sinking diode bias current control circuits, N upper diode interconnection circuits, N lower diode interconnection circuits, N current-sourcing diode bias current control circuits, and 2N high-voltage signal return circuits; The N sub-coils of the electromagnetic ultrasonic transducer are numbered 1, 2, ..., n, ..., N in order of arrangement, and each sub-coil contains two branch coils numbered Ln_1 and Ln_2; then: The current-sinking diode bias current control circuit n is connected to the upper diode interconnection circuit n; One end of the upper diode interconnection circuit n is connected to the opposite-name end of the branch coil L(n-1)_2 of the transducer sub-coil (n-1) and the high-voltage signal return circuit (n-1)_1, and the other end is connected to the same-name end of the branch coil Ln_1 of the transducer sub-coil n and the high-voltage power supply output network HVOUT-Ln_1; The current sourcing diode bias current control circuit n is connected to the lower diode interconnection circuit n; One end of the lower diode interconnection circuit n is connected to the opposite-name end of the branch coil Ln_1 of the transducer sub-coil n and the high-voltage signal return circuit n_2, and the other end is connected to the same-name end of the branch coil Ln_2 of the transducer sub-coil n and the high-voltage power supply output network HVOUT-Ln_2.

3. The electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 2, characterized in that: The N current-sinking diode bias current control circuits, wherein the current-sinking diode bias current control circuit n includes a transistor Qsrc_n, a bias resistor Rsrc-t_n, a Rsrc-b_n, a negative feedback resistor Rsrc-f_n, and a load resistor Rsrc_n; wherein the bias resistor Rsrc-t_n is connected in series with Rsrc-b_n, the common end is connected to the base of Qsrc_n, the other end of Rsrc-b_n is grounded, and the other end of Rsrc-t_n is connected to +12V; the emitter of the transistor Qsrc_n is connected to one end of the resistor Rsrc-f_n, and the other end of Rsrc-f_n is connected to VCC controlled by the system processor, and VCC outputs 0V or +12V; the collector of the transistor Qsrc_n is connected to one end of the load resistor Rsrc_n, and the other end of Rsrc_n is connected to the control end of the upper diode interconnection circuit n.

4. The electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 2, characterized in that: The N upper diode interconnection circuits, wherein the upper diode interconnection circuit n includes diodes D-t1_n and D-t2_n; the anode of diode D-t1_n is connected to the anode of diode D-t2_n, and both are connected to Rsrc_n of the output end of current injection type diode bias current control circuit n; the other end of D-t1_n is connected to the high-voltage signal return circuit (n-1)_1 and the opposite-name end of L(n-1)_2 branch coil of transducer sub-coil (n-1), and the other end of D-t2_n is connected to the high-voltage power supply output network HVO UT-Ln_1 and the same-name end of Ln_1 branch coil of transducer sub-coil n.

5. The electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 2, characterized in that: The N current-sourcing diode bias current control circuits, wherein the current-sourcing diode bias current control circuit n includes a transistor Qsk_n, a bias resistor Rsk-t_n, a Rsk-b_n, a negative feedback resistor Rsk-f_n, and a load resistor Rsk_n; wherein the bias resistor Rsk-t_n is connected in series with Rsk-b_n, the common end is connected to the base of Qsk_n, the other end of Rsk-t_n is grounded, and the other end of Rsk-b_n is connected to a negative voltage of -12V; the emitter of the transistor Qsk_n is connected to one end of the resistor Rsk-f_n, and the other end of Rsk-f_n is connected to VEE controlled by the system processor, and VEE outputs 0V or -12V; the collector of the transistor Qsk_n is connected to one end of the load resistor Rsk_n, and the other end of Rsk_n is connected to the control end of the lower diode interconnection circuit n.

6. The electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 2, characterized in that: The N lower-end diode interconnection circuits, wherein the lower-end diode interconnection circuit n includes diodes Db1_n and D-b2_n; the cathode of diode Db1_n is connected to the cathode of diode D-b2_n, and both are connected to Rsk_n, the output end of the current-pulling diode bias current control circuit n; the other end of D-b1_n is connected to the high-voltage signal return circuit n_2 and the opposite-name end of the Ln_1 branch coil of the transducer sub-coil n, and the other end of D-b2_n is connected to the high-voltage power supply output network HVOUT-Ln_2 and the same-name end of the Ln_2 branch coil of the transducer sub-coil n.

7. The electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 2, characterized in that: The 2N high-voltage signal return circuits; wherein the high-voltage signal return circuit n_1 includes D-hv-t1_n, D-hv-t2_n; the high-voltage signal return circuit n_2 includes D-hv-b 1_n, D-hv-b2_n.

8. A control method for an electronic circuit for improving electromagnetic ultrasonic transmission power and receiving efficiency, characterized in that: include: Step S1: before the high voltage power supply is transmitted, the system controls VCC to output 0V, VEE to output 0V, the triodes of the current-injection type diode bias current control circuit are all cut off, and the triodes of the current-source type diode bias current control circuit are all cut off, so that the upper diode interconnection circuit connected to the current-injection type diode bias current control circuit has no bias current, and the upper diode interconnection circuit is in a cut-off state, and the lower diode interconnection circuit connected to the current-source type diode bias current control circuit has no bias current, and the lower diode interconnection circuit is in a cut-off state; at this time, the two transducer branch coils connected to the upper diode interconnection circuit port are isolated from each other; the two transducer branch coils connected to the lower diode interconnection circuit port are also isolated from each other; At this time, the high-voltage pulse output by the high-voltage power supply can be loaded onto each sub-coil of the transducer. Under the magnetic field, the high-voltage pulse voltage excites all sub-coils to generate ultrasonic waves in the tested block, completing an ultrasonic emission. Step S2: the high-voltage power supply stops outputting high-voltage pulses, the system controls VCC to output +12V, VEE to output -12V, the triodes of the current-injection type diode bias current control circuit are all turned on, and the collector outputs a constant current. At the same time, the triodes of the current-sourcing type diode bias current control circuit are also turned on, and the collector absorbs a constant current, thereby generating a bias current in the upper diode interconnection circuit connected to the current-injection type diode bias current control circuit, and generating a bias current in the lower diode interconnection circuit connected to the current-sourcing type diode bias current control circuit; therefore, the upper diode interconnection circuit and the lower diode interconnection circuit are both in a conducting state; at this time, the two transducer branch coils connected to the upper diode interconnection circuit port are connected at a low impedance; the two transducer branch coils connected to the lower diode interconnection circuit port are also connected at a low impedance, and all branch coils are connected in series and connected to the ultrasonic signal receiving circuit to complete the reception of a small ultrasonic signal.

9. The control method of an electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 8, characterized in that: Step S1 specifically includes: When the system controls VCC and VE E to be 0V, the transistors Qsrc_1, Qsrc_2, Qsrc_n…Qsrc_N in the N current-sinking diode bias current control circuits are all in the cut-off state, and their collectors have no static current; the transistors Qsk_1, Qsk_2, Qsk_n…Qsk_N in the N current-sourcing diode bias current control circuits are all in the cut-off state, and their collectors have no static current; therefore, the N upper diode interconnection circuits connected to the N current-sinking diode bias current control circuits and the N lower diode interconnection circuits connected to the N current-sourcing diode bias current control circuits also have no bias current; therefore, the diodes in all the upper diode interconnection circuits are in the cut-off state, and the diodes in all the lower diode interconnection circuits are in the cut-off state; at this time, when the system controls high-voltage transmission, the high-voltage pulse is input from the same-name ends of the 2N branch coils of the N transducer sub-coils, and is connected to the ground after passing through the high-voltage return circuit connected to the opposite-name ends of the 2N branch coils to form a loop.

10. The control method of an electronic circuit for improving electromagnetic ultrasonic transmitting power and receiving efficiency according to claim 8, characterized in that: Step S2 specifically includes: After the high-voltage transmission is completed, the system controls VCC to output +12V and VE E to output -12V; the transistors Qsrc_1, Qsrc_2, Qsrc_n...Qsrc_N in the N current-sinking diode bias circuits are in the on state, and the negative feedback resistors Rsrc-f_1, Rsrc-f_2, Rsrc-f_n,..., Rsrc-f_N stabilize the static working current of the transistors connected thereto, and at this time, the collector of each transistor outputs a constant static current; at the same time, the transistors Qsk_1, Qsk_2, Qsk_n,..., Qsk_N in the N current-pulling diode bias current control circuits are in the on state, and the negative feedback resistors Rsk-f_1, Rsk-f_2, Rsk-f_n...Rsk-f_N stabilize the static working current of the transistors connected thereto, and the collector of each transistor absorbs a constant static current; therefore, the Ln_1 coil in the N sub-coils of the transducer In the connected transmitting and receiving circuit, the collector output current of the transistor Qsrc_n in the current-sinking diode bias current control circuit n passes through D-t1_n of the upper diode interconnection circuit n to the opposite end of the L(n-1)_2 branch coil of the n-1th sub-coil, forming an AC signal low impedance path 2(n-1)+1; the current output by the collector of the transistor Qsrc_n in the current-sinking diode bias current control circuit n flows through the diode D-t2_n in the upper diode interconnection circuit n, the Ln_1 branch coil of the transducer sub-coil n, D-b1_n in the lower diode interconnection circuit n, and Rsk_n of the current-sourcing diode bias current control circuit, and finally converges into the collector of the transistor Qsk_n. At this time, the collector of the transistor Qsk_n in the current-sourcing diode bias current control circuit absorbs a constant current, thereby forming an AC signal low impedance path 2n; At the same time, the current flowing into the collector of the transistor Qsk_n of the current-sourcing diode bias current control circuit n also passes through Rsk_n, D-b2_n of the lower diode interconnection circuit n, the Ln_2 branch coil of the transducer sub-coil n, D-t1_(n+1) of the upper diode interconnection circuit n+1, Rsrc_(n+1) of the current-injection diode bias current control circuit n+1, and finally connected to the collector of the transistor Qsrc_(n+1). At this time, the collector of Qsrc_(n+1) outputs a constant current, thereby forming an AC signal low-impedance path 2n+1; the current output by the collector of the transistor Qsrc_(n+1) in the current-injection diode bias current control circuit n+1 flows through the diode D-t2_(n+1) in the upper diode interconnection circuit n+1, the transducer sub-coil n, and Rsrc_(n+1) of the current-injection diode bias current control circuit n+1. The L(n+1)_1 branch coil of the transducer sub-coil n+1, D-b1_(n+1) in the lower diode interconnection circuit n+1, and Rsk_(n+1) of the current-pulling diode bias current control circuit are finally merged into the collector of the transistor Qsk_(n+1), forming an AC signal low-impedance path 2(n+1); the Ln_1 branch coil of the transducer sub-coil n is connected to the L(n-1)_2 branch coil of the previous sub-coil (n-1) through the above-mentioned low-impedance path 2(n-1)+1 and low-impedance path 2n, and the Ln_2 branch coil of the transducer sub-coil n and the L(n+1)_1 branch coil of the sub-coil n+1 are connected together through the low-impedance path 2n+1 and the low-impedance path 2(n+1), realizing the series connection of the sub-coil n with the previous sub-coil n-1 and the next sub-coil n+1; By analogy, from the nth sub-coil forward to the transmitting and receiving circuit connected to the first sub-coil, the low impedance path 1 is a path formed by the collector of the transistor Qsrc_1 in the current-injection type diode bias current control circuit 1, the load resistor Rsrc_1, the diode D-t2_1 of the upper diode interconnection circuit 1, and the signal input positive electrode of the ultrasonic signal receiving circuit; the low impedance path 2 is a path formed by the collector of the transistor Qsrc_1 of the current-injection type diode bias current control circuit 1, Rsrc_1, D-t1_1 of the upper diode interconnection circuit 1, L1_1 of the first sub-coil of the transducer, and the collectors Db1_1, Rsk_1, and Qsk_1 of the lower diode interconnection circuit 1; By analogy from the nth sub-coil backward to the transmitting and receiving circuit connected to the Nth sub-coil, the low impedance path 2N+1 is a path formed by the collector of the transistor Qsk_N in the current-pulling diode bias current control circuit N, the load resistor Rsk_N, the diode D-b2_N of the lower diode interconnection circuit N, the LN_2 branch coil of the sub-coil N, and the signal input cathode of the ultrasonic signal receiving circuit; the low impedance path 2N is a path formed by the collector of the transistor Qsrc_N of the current-injection diode bias current control circuit N, Rsrc_N, and D-t2_N of the upper diode interconnection circuit N. , LN_1 of the Nth sub-coil of the transducer, D-b1_N, Rsk_N, Qsk_N collectors of the lower diode interconnection circuit N form a path, so the 1st sub-coil to the Nth sub-coil are connected in series end to end through the low impedance loop 1, 2, ...2n, 2n+1...2N, 2N+1 to form a coil, one end of the coil is connected to the positive signal input terminal of the ultrasonic signal receiving circuit, and the other end is connected to the negative signal input terminal of the ultrasonic signal receiving circuit; thereby, 2N branch coils of the N sub-coils are connected in series and then connected to the ultrasonic signal receiving circuit to complete the external output of small signals.

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