Load impedance measurement circuit, system and high frequency device

Abstract

The utility model relates to a kind of load impedance measurement circuit, system and equipment, including waveform control circuit, load impedance acquisition circuit, signal amplification circuit, analog signal conversion PWM circuit, filter circuit and MCU connected in turn;Waveform control circuit includes self-oscillation circuit and rectangular wave output circuit, rectangular wave output circuit receives the rectangular wave that self-oscillation circuit exports and reference voltage comparison generates complementary rectangular wave output to load impedance acquisition circuit, load impedance acquisition circuit gathers load impedance and exports direct current signal to signal amplification circuit, analog signal conversion PWM circuit gathers amplified signal conversion as digital signal to filter circuit and carries out filter processing, and MCU receives the signal after filter processing of filter circuit.The utility model uses self-oscillation and complementary rectangular wave output circuit to form sampling circuit combination, the signal gathered is more accurate, and it is easy to be read and further processed by lower circuit, and finally the impedance measurement value of equipment is more accurate.

Description

Technical Field

[0001] This utility model relates to a load impedance measurement circuit, system, and high-frequency equipment, belonging to the field of high-frequency surgical technology. Background Technology

[0002] High-frequency surgical systems are widely used in clinical medicine due to their advantages over traditional surgical instruments. How to fully realize the functions of these devices, perform surgeries precisely according to different clinical situations, reduce surgical risks, minimize postoperative trauma, and improve patient comfort are all top priorities for every medical device developer. Precise and stable output power is particularly important for different tissues. Therefore, accurately identifying the impedance of different tissues has become a significant challenge in medical device development.

[0003] Currently, high-frequency surgical systems on the market use a combination of current transformers (or isolation transformers) and operational amplifier filter circuits to sample the load impedance of the equipment, thereby adjusting the power output. This combination method collects the load impedance signal by charging and discharging an inductive coil through series resistors and capacitors. However, due to limitations such as the inductive characteristics of the current transformer (or isolation transformer) itself, winding process, coil length, and errors in the core parameters, the impedance sampling range identified by each device varies greatly, resulting in poor consistency among the devices. Summary of the Invention

[0004] The technical problem this invention aims to solve is that traditional high-frequency surgical systems have poor load impedance sampling accuracy. Therefore, it is necessary to propose a sampling circuit that can accurately identify load impedance, thereby precisely controlling power output and reducing surgical risks.

[0005] To achieve the above objectives, the present invention provides a technical solution comprising: a waveform control circuit, a load impedance acquisition circuit, a signal amplification circuit, an analog signal to PWM circuit, a filter circuit, and an MCU connected in sequence; the waveform control circuit includes a self-excited oscillation circuit and a rectangular wave output circuit; the rectangular wave output circuit receives the rectangular wave output by the self-excited oscillation circuit, compares it with a reference voltage to generate a complementary rectangular wave, and outputs it to the load impedance acquisition circuit; the load impedance acquisition circuit acquires the load impedance and outputs a DC signal to the signal amplification circuit; the analog signal to PWM circuit acquires the amplified signal, converts it into a digital signal, and sends it to the filter circuit for filtering; the MCU receives the signal after filtering by the filter circuit.

[0006] Furthermore, the rectangular wave output by the self-excited oscillation circuit is divided by resistors on the two rectangular wave output circuits for voltage output.

[0007] Furthermore, the load impedance acquisition circuit uses two MOS transistors connected to resistors with fixed resistance values ​​and is alternately turned on by the two rectangular wave output circuits to output alternating rectangular waves.

[0008] Furthermore, the load impedance measurement circuit also includes an optocoupler isolation circuit located between the analog signal to PWM circuit and the filter circuit.

[0009] To solve the above-mentioned technical problems, this utility model provides a second technical solution: a load impedance measurement system, including a load and a load impedance measurement circuit provided in the first technical solution.

[0010] To solve the above-mentioned technical problems, this utility model provides a third technical solution: a high-frequency device that adopts the load impedance measurement system provided in the second technical solution.

[0011] The device in question is a high-frequency electrosurgical unit.

[0012] The beneficial effects of the technical solution provided by this utility model are as follows: The load impedance measurement circuit, system, and high-frequency equipment provided by this utility model, composed of a sampling circuit combination of self-excited oscillation and complementary rectangular wave output circuit, ensures that the acquired impedance signal is a DC signal, which is fundamentally different from the AC signal acquired using RC devices. The acquired signal is more accurate and easier for downstream circuits to read and further process. Furthermore, the use of complementary rectangular wave alternating conduction of MOS transistors ensures that the waveform of the load impedance acquired clinically from patient tissue impedance is an alternating rectangular wave with stable high and low amplitudes, effectively avoiding the adverse effects on patient tissue caused by spikes or irregular waveforms due to product circuit structure problems. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the load impedance measurement circuit design of this utility model.

[0014] Figure 2 This is a schematic diagram of the waveform control circuit for the load impedance measurement circuit of this utility model.

[0015] Figure 3 This diagram shows the waveform control circuit, load impedance acquisition circuit, signal amplification circuit, and analog signal to PWM conversion circuit of the load impedance measurement circuit of this utility model.

[0016] Figure 4 This is a schematic diagram of the filter circuit of this utility model.

[0017] Figure 5 This is a graph showing the test data of the load impedance measuring device of this utility model. Detailed Implementation

[0018] Example

[0019] This utility model designs a load impedance measurement circuit, such as Figure 1 and Figure 2 As shown, the circuit includes a waveform control circuit, a load impedance acquisition circuit, a signal amplification circuit, an analog signal to PWM circuit, a filter circuit, and an MCU connected in sequence. The waveform control circuit includes a self-excited oscillation circuit and a rectangular wave output circuit. The rectangular wave output circuit receives the rectangular wave output by the self-excited oscillation circuit, compares it with the reference voltage, generates a complementary rectangular wave, and outputs it to the load impedance acquisition circuit. The load impedance acquisition circuit acquires the load impedance and outputs a DC signal to the signal amplification circuit for further amplification. Then, the signal is converted into a digital signal by the analog signal to PWM circuit and filtered by the filter circuit. The MCU receives the filtered signal and reads the impedance value.

[0020] In one embodiment, an optocoupler isolation circuit is also included for electrical isolation to prevent high-voltage interference from affecting the control circuit, and is located between the analog signal to PWM circuit and the filter circuit.

[0021] In one embodiment, the rectangular wave output by the self-excited oscillation circuit is divided by resistors on two rectangular wave output circuits. In another embodiment, the load impedance acquisition circuit uses two MOSFETs connected to resistors of fixed resistance values, which are alternately turned on by the two rectangular wave output circuits to output alternating rectangular waves. The output impedance signal is periodically acquired and processed before being transmitted to the MCU, resulting in more accurate impedance readings.

[0022] The following is combined with Figure 2 This invention provides a detailed description of the circuit design of each module in the load impedance measurement circuit provided by this utility model.

[0023] In this embodiment, the self-excited oscillation circuit and the complementary rectangular wave output circuit are composed of Figure 3 The selected portion is comprised of the boxed area. Figure 3 Operational amplifier U2A, capacitors C1 / C5, and resistors R3 / R5 / R9 / R17 form a self-excited oscillation circuit, outputting a square wave with a frequency of Fs (sampling frequency, the same below) and an amplitude of VCC1. Changing the values ​​of resistor R17 and capacitor C5 adjusts the frequency Fs. Capacitor C1 is a decoupling capacitor for the power supply pin of operational amplifier U2A. Figure 3The operational amplifiers U1A / U1B, resistors R2 / R6 / R15 / R16, and capacitor C4 form a rectangular wave output circuit. Resistors R2 and R16 divide VCC1, comparing it with the rectangular wave output from pin 1 of operational amplifier U2A. These are then used by operational amplifiers U1A and U1B to output complementary rectangular waves with frequencies Fs and amplitudes VCC1, respectively. R6 and R15 are current-limiting resistors for MOSFETs Q1 and Q2, and capacitor C4 is a decoupling capacitor for the power supply pin of operational amplifier U1A. To avoid insufficient rectangular wave drive capability, operational amplifiers U1A / U1B can be selected as rail-to-rail operational amplifiers, or push-pull circuits can be added to the two output terminals of operational amplifier U1 to enhance the drive capability.

[0024] The load impedance acquisition circuit consists of Figure 3 The section highlighted in the middle is the main structure. NP1 and NP2 are the input terminals for the load impedance. MOSFETs Q1 and Q2 are alternately turned on. When MOSFET Q1 is on, resistor R8 and the load impedance form the first-stage voltage divider circuit to divide VCC1. Resistors R10 and R1 form the second-stage voltage divider circuit to further divide the voltage after the voltage division by resistor R8 and the load impedance. Capacitor C6 is the filter capacitor. When MOSFET Q2 is on, resistor R4 and the load impedance form the first-stage voltage divider circuit to divide VCC1. Resistors R10 and R1 form the second-stage voltage divider circuit to further divide the voltage after the voltage division by resistor R4 and the load impedance. Capacitor C6 is the filter capacitor. This circuit outputs DC power.

[0025] The signal amplification circuit and the analog signal to PWM conversion circuit are composed of Figure 3 The portion highlighted in the middle is the main structure. Operational amplifier U2B and resistors R13 / R14 form a non-inverting amplifier with an output gain of 1 + R14 / R13. Resistor R7 and capacitor C2 form an RC filter circuit to filter out noise from the amplified signal before it is input to integrated chip U3. In one embodiment, U3 is a chip that integrates an analog signal to PWM digital signal conversion circuit, and capacitor C3 is a decoupling capacitor for the power supply pin of integrated chip U3.

[0026] Optocoupler isolation circuit consists of Figure 3 The section within the middle box constitutes the circuit. This circuit section serves as high-voltage isolation, with the isolation voltage value being the insulation strength value between optocoupler U4 and the insulation strength value between phototransmitter L1 and photoreceiver L2. In this embodiment, the withstand voltage can reach 6.5kV. Resistors R11 / R12, optocoupler U4, and phototransmitter L1 constitute the signal transmitting end, while resistor R18, inverter U5, and photoreceiver L2 constitute the signal receiving end. NP_PWM is the output signal of the receiving end, connected to... Figure 4 The filtering circuit in the middle is used for further processing.

[0027] like Figure 4The filter circuit shown consists of inverter U6, operational amplifier U7B, resistors R19 / R20, capacitors C7 / C8, and TVS diode D1. Inverters U6 and U5 enhance the signal read from photodetector L2. Operational amplifier U7B is a unit follower to reduce interference. Resistor R20 and capacitor C8 form an RC filter circuit to convert the acquired signal into a DC signal. TVS diode D1 serves as surge or overvoltage protection and also acts as a clamp, ensuring that the lowest value acquired by the MCU is the forward voltage drop of TVS diode D1. This part of the circuit makes the value acquired by the MCU more accurate and stable.

[0028] This invention also provides a load impedance measurement system, which adopts the above-mentioned load impedance measurement circuit structure design. Depending on the different load impedance values ​​connected, the impedance sampling value can be read from the MCU, and it has good consistency.

[0029] This invention also provides a load impedance measuring device, which employs the aforementioned load impedance measuring system. In one embodiment, the load impedance measuring device provided by this invention is a high-frequency electrosurgical unit. Figure 5 This is a graph showing the input-output impedance of the high-frequency electrosurgical impedance acquisition circuit of this invention. The horizontal axis represents the input impedance, and the vertical axis represents the output impedance. The linear relationship in the graph shows that the output impedance and input impedance are essentially consistent, indicating very high accuracy.

[0030] In terms of circuit cost, this solution uses conventional integrated chips, which are lower in cost than circuits using current transformers (or isolation transformers) which require customized inductive components. Moreover, it is not limited by the processing time of customized parts, saving equipment manufacturing time.

[0031] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A load impedance measurement circuit, characterized in that: The system includes a waveform control circuit, a load impedance acquisition circuit, a signal amplification circuit, an analog signal to PWM circuit, a filter circuit, and an MCU connected in sequence. The waveform control circuit includes a self-excited oscillation circuit and a rectangular wave output circuit. The rectangular wave output circuit receives the rectangular wave output by the self-excited oscillation circuit, compares it with a reference voltage to generate a complementary rectangular wave, and outputs it to the load impedance acquisition circuit. The load impedance acquisition circuit acquires the load impedance and outputs a DC signal to the signal amplification circuit. The analog signal to PWM circuit acquires the amplified signal, converts it into a digital signal, and sends it to the filter circuit for filtering. The MCU receives the filtered signal from the filter circuit.

2. The load impedance measuring circuit according to claim 1, characterized in that: The rectangular wave output by the self-excited oscillation circuit is divided by resistors on the two rectangular wave output circuits and then output.

3. The load impedance measurement circuit according to claim 1, characterized in that: The load impedance acquisition circuit uses two MOS transistors connected to resistors with fixed resistance values ​​and is alternately turned on by the two rectangular wave output circuits to output alternating rectangular waves.

4. The load impedance measuring circuit according to claim 1, characterized in that: The load impedance measurement circuit also includes an optocoupler isolation circuit, located between the analog signal to PWM circuit and the filter circuit.

5. A load impedance measurement system, characterized in that: Includes a load and the load impedance measurement circuit according to any one of claims 1-4.

6. A high-frequency device, characterized in that: Includes the load impedance measurement system as described in claim 5.

7. The high-frequency device according to claim 6, characterized in that: The device is a high-frequency electrosurgical unit.

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