Electrosurgical instrument
First Claim
1. An electrosurgical instrument comprising:
- a handpiece, a single treatment electrode projecting from the handpiece, and a generator capable of operating at a substantially fixed frequency under varying load conditions, the generator having an output stage comprising;
an output power device, and, coupled to the power device, an output network including a treatment electrode output node, wherein the output network has a load-dependent resonant condition and includes a variable reactance element arranged to compensate at least partially for output network mistuning effects due to variations in load impedance, the generator treatment electrode output node being connected to the treatment electrode, the instrument being, arranged such that the generator radio frequency return path during use occurs by electromagnetic field transmission through air between the patient and the instrument.
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Accused Products
Abstract
In an electrosurgical instrument susceptible to varying load impedance, particularly varying load reactance, a fixed frequency radio frequency generator has an output stage (Q1, Q2, TR2-TR4, C1, VC2, 42) consisting of at least one output power device and, coupled to the power device, an output network with a load-dependent resonant condition. To compensate for variations in the load reactance, the output network has a dynamically variable capacitor (VC2) which maintains the tuning of the network substantially constant. Variation of the capacitor (VC2) is performed by means of a phase comparator and servo device (44) which are responsive to variations in phase difference occurring in the output stage due to load reactance changes.
1886 Citations
25 Claims
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1. An electrosurgical instrument comprising:
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a handpiece, a single treatment electrode projecting from the handpiece, and a generator capable of operating at a substantially fixed frequency under varying load conditions, the generator having an output stage comprising;
an output power device, and, coupled to the power device, an output network including a treatment electrode output node, wherein the output network has a load-dependent resonant condition and includes a variable reactance element arranged to compensate at least partially for output network mistuning effects due to variations in load impedance, the generator treatment electrode output node being connected to the treatment electrode, the instrument being, arranged such that the generator radio frequency return path during use occurs by electromagnetic field transmission through air between the patient and the instrument. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification