Laparoscopic instruments
AssigneeAsalus Medical Instruments Limited
InventorFrancis Kweku Egyin Amoah
Life of this patent
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Abstract
A DC driven ionization apparatus is provided for ionizing a local atmosphere in which a corporeal surgical or cosmetic procedure is to be performed, the ionization apparatus including a safety circuit comprising detector means for detecting when a hazard condition exists, such as a short circuit or high charge level condition, a circuit controller for actuating switch means to turn the DC supply off and thereafter to cyclically reconnect and disconnect the DC supply until the hazard condition has been rectified, and re-set means for thereafter re-setting a continuous DC supply to the circuit until the next occurrence of a hazard condition or until the procedure is complete.
Claims20
A DC driven ionisation apparatus for ionising a local atmosphere in which a corporeal surgical or cosmetic procedure is to be performed on a patient, comprising:
- a power supply providing a DC voltage to a converter via an isolation switch, said converter converting the DC voltage to a high voltage DC current;
- an output electrode connected to the converter and a return electrode connected to the power supply to provide an ionization path in use;
- a high voltage resistor network couples the converter to the output electrode and the return electrode to the power supply, the high voltage resistor network includes a current sense resistor connected between the return electrode and the power supply for sensing a current used in detecting a hazard condition when a potential difference between the output electrode and return electrode is less than 3 kV;
- and
- a comparator to signal a monostable connected to the isolation switch to open the isolation switch for a predefined interruption duration between 2 and 3 seconds when the sensed current indicates the hazard condition;
- wherein the monostable cyclically reconnects and disconnects the power supply until the hazard condition has been rectified each reconnect and disconnect cycle taking place over a period of approximately 200 ms.
A DC driven ionisation apparatus for ionising a local atmosphere in which a corporeal surgical or cosmetic procedure is to be performed on a patient, comprising:
- a power supply providing a DC voltage to a converter via an isolation switch, said converter converting the DC voltage to a high voltage DC current;
- an output electrode connected to the converter and a return electrode connected to the power supply to provide an ionization path in use;
- a high voltage resistor network couples the converter to the output electrode and the return electrode to the power supply, the high voltage resistor network includes a current sense resistor connected between the return electrode and the power supply for sensing a current used in detecting a hazard condition;
- and
- a comparator to signal a monostable connected to the isolation switch to open the isolation switch for a predefined interruption duration when the sensed current indicates the hazard condition;
- wherein the monostable cyclically reconnects and disconnects the power supply until the hazard condition has been rectified, wherein the resistor network includes a first resistor connected in series between the converter and the output electrode and a second resistor connected in series between the return electrode and the converter, wherein the first and second resistors limit a steady-state output current of the converter to no more than 50 microamps, and further comprising a closed loop current limit circuit for reducing the output voltage of the converter, and wherein the closed loop current limit circuit includes a current summer that outputs a difference of the sensed current and a threshold current to an amplifier, said amplifier having a zero output when the current summer output indicates acceptable conditions and an increasing amplitude output when the current summer output indicates excessive output current conditions, the amplifier output is fed to the comparator and a first voltage summer, the first voltage summer receives a voltage demand signal which is reduced by the amplifier output, an output of the first voltage summer is fed to a second voltage summer that outputs a difference of the output of the first voltage summer and a sensed converter output voltage, an output of the second voltage summer is fed to a second amplifier which provides a voltage control signal to the converter.
Dependencies are inferred from the claim text.