Push-Pull Generator With Switchable Capacitors for Half-Wave Control
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Solution Overview
Problem
Existing electrosurgical generators lack the ability to effectively influence the waveform of the output voltage and current, which is crucial for achieving specific physiological effects during medical procedures.
Innovation Solution
A generator design featuring at least two amplifiers with a resonant circuit and additional capacitors that allow for control over the amplitude and duration of half-waves, enabling the generation of asymmetrical and modulated output voltage and current waveforms through a push-pull oscillator configuration with electronic switches and a control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional generator design with a single resonant circuit is used, then the structure is simple, but the ability to influence the waveform of output voltage and current is limited
Solution Approach 1:
The generator is divided into multiple independent amplifier stages (first amplifier and second amplifier) that can be controlled separately. Each amplifier has its own control circuit, allowing independent manipulation of different portions of the output waveform. This segmentation enables sophisticated waveform control while maintaining modular circuit design.
Solution Approach 2:
The circuit incorporates dynamically switchable capacitors that can be connected or disconnected during operation. The second capacitor connected to the first amplifier and the third capacitor connected to the second amplifier can be switched via control circuits, allowing real-time adjustment of the resonant frequency and waveform characteristics without changing the physical circuit structure.
2Adaptability or versatility
If additional capacitors and control circuits are added to influence the waveform, then waveform control capability is improved, but device complexity increases
Solution Approach 1:
The control circuits serve multiple functions: they control the switching of capacitors, regulate the amplifiers' operation, and adjust the resonant frequency. The capacitors themselves serve dual purposes by affecting both the frequency and the shape of the output waveform. This multi-functionality reduces the need for separate dedicated components for each control function.
Solution Approach 2:
The invention controls waveform characteristics by changing electrical parameters such as capacitance values and switching timing rather than by adding complex physical structures. By varying the capacitance of the switchable capacitors and adjusting when they are connected or disconnected, the system achieves versatile waveform control through parameter modulation instead of structural complexity.
3Adaptability or versatility
If the generator uses a push-pull oscillator configuration with switchable capacitors, then asymmetric waveforms can be generated, but the control circuit complexity increases
Solution Approach 1:
The push-pull oscillator configuration inherently provides asymmetry capability through the switchable capacitors. When the second capacitor or third capacitor is connected, it creates an asymmetric capacitive loading on one side of the push-pull configuration, resulting in asymmetric output waveforms. This allows the generator to produce both symmetric and asymmetric waveforms as needed.
Solution Approach 2:
The control circuits operate periodically, switching the capacitors on and off in synchronization with the oscillator's operating cycle. This periodic switching action allows precise control over when the asymmetric capacitance is applied during each oscillation cycle, enabling fine-tuned waveform shaping while using simple switching logic rather than complex continuous control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for precise control over the output voltage and current waveforms, enabling tailored physiological effects such as promoting or inhibiting spark formation on instrument electrodes, thus expanding the generator's applicability in medical procedures.
Implementation Method 1
A generator according to the invention is based on a concept with at least two amplifiers, between whose outputs an inductor of a resonant circuit is arranged. At least one first capacitor is assigned to the inductor, with which it forms an oscillating circuit
Implementation Method 2
from which the energy is extracted via a transformer to power the connected instrument
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A push-pull generator (12) designed to supply a medical instrument (10) has at least one preferably switchable capacitive branch to ground in parallel with at least one of its two transistors (T1, T2). Such a switchable capacitive branch can consist of a capacitor (C2) and a switch (SW1) connected in series. This allows one of the two half-waves of the output voltage of the generator (12) to be selectively influenced, while the other half-wave remains largely unaffected. The concept according to the invention thus allows for the selective influencing of half-cycles of an otherwise symmetrical push-pull generator, thereby increasing the range of applications for supplying medical instruments with treatment current.