Low capacitance endoscopic system
An endoscopic system can include an endoscope shaft having a proximal end and a distal end, and an electrically active sensor system including at least one sensor mounted proximate the distal end and positioned to sense at least one characteristic of an environment in which the distal end is located. The capacitance of the sensor system relative to earth ground maintains current leakage to a level that meets a cardiac float rating.
1. An endoscopic system comprising:
an endoscope shaft having a proximal end and a distal end;
an electrically active sensor system comprising:
a sensor mounted proximate the distal end and positioned to sense at least one characteristic of an environment in which the distal end is located,
a transceiver circuit coupled to the sensor,
a data signal transmission line connected to the sensor to transmit data signals between the sensor and a signal processor, via the transceiver circuit, and
an electrical power transmission line connected to the sensor to transmit power from a power source to the sensor;
a floating ground element coupled to provide an electrical reference for the sensor system, wherein the floating ground element comprises a conductive material surrounding the data signal transmission line and the electrical power transmission line; and
a power regulator coupled between the electrical power transmission line and the floating ground element, the power regulator to provide electrical power to the sensor system, wherein the power regulator converts ground-referenced power received from an earth ground referenced power source into floating ground element referenced power and outputs the floating ground element referenced power through the electrical power transmission line,
wherein:
the transceiver circuit isolates the sensor from earth grounded elements communicating with the sensor,
an overall capacitance between the electrical power transmission line and the floating ground element is larger than an overall capacitance between the floating ground element and earth ground, and
a capacitance of the sensor system relative to earth ground maintains current leakage from one or more applied parts of the endoscopic system to a patient to a predetermined current leakage criteria.
2. The endoscopic system of claim 1 , further comprising an electrically insulative material separating the floating ground element from each of the data signal and electrical power transmission lines.
3. The endoscopic system of claim 1 , wherein the data signal transmission line is configured to transmit data signals via a differential mode.
4. The endoscopic system of claim 3 , wherein the differential mode is a differential digital mode.
5. The endoscopic system of claim 1 , wherein:
the transceiver circuit comprises an optical transceiver connected to the data signal transmission line and to an optical interface,
the optical transceiver receives input electronic signals from the data signal transmission line and outputs corresponding output optical signals through the optical interface, and
the optical transceiver receives input optical signals through the optical interface and outputs corresponding output electronic signals through the data signal transmission line.
6. The endoscopic system of claim 5 , further comprising:
a Faraday cage coupled to the floating ground element and enclosing the optical transceiver and the power regulator.
7. The endoscopic system of claim 6 , further comprising:
a data interface;
a second optical transceiver coupled to the optical transceiver to exchange optical signals with the optical transceiver and coupled to the data interface to exchange electrical signals through the data interface; and
an earth ground-referenced power interface to receive earth ground-referenced power from the earth ground-referenced power source.
8. The endoscopic system of claim 7 , wherein:
the sensor system transmits sensor data through the data signal transmission line by a differential mode.
9. The endoscopic system of claim 8 , wherein:
the differential mode is a differential digital mode.
10. The endoscopic system of claim 1 , wherein the capacitance of the sensor system relative to earth ground is less than 500 pF under a condition of an earth ground referenced power source providing a nominal 230 volts under alternating current at 60 Hertz.
11. The endoscopic system of claim 1 , wherein the sensor is an electronic image sensor.
12. The system of claim 1 , wherein,
a ratio of the capacitance between the electrical power transmission line and the floating ground element to the capacitance between the floating ground element and earth ground is in a range of from 10,000 to 1 to 55,000 to 1.
13. A method for sensing information at a remote surgical site via an endoscopic system, the method comprising:
at a remote surgical site, sensing a characteristic of the remote surgical site via a sensor disposed proximate a distal end of an endoscope shaft;
during the sensing, transmitting power to the sensor, via a power transmission line and a power regulator, from a ground-referenced power source;
during the sensing, transmitting data signals to the sensor via a data signal transmission line from a processing circuit at a proximate end of the endoscopic shaft, wherein the processing circuit is isolated from the data signal transmission line by a transceiver circuit disposed between the data signal transmission line and the processing circuit;
in response to electromagnetic interference proximate to the remote surgical site, causing, at least in part by a floating ground element arranged to provide an electrical reference for the sensor, induced voltage level changes in the data signal transmission line and the power transmission line to be substantially equalized, wherein an overall capacitance between the power transmission line and the floating ground element is larger than an overall capacitance between the floating ground element and earth ground; and
maintaining current leakage, from one or more applied parts of the endoscopic system to a patient, to a level that meets a predetermined current leakage criteria, wherein the current leakage is maintained using the floating ground element and the transceiver circuit.
14. The method of claim 13 , wherein the remote surgical site comprises a cardiothoracic cavity.
15. The method of claim 13 , wherein the remote surgical site comprises a heart.
16. An endoscopic system comprising:
a sensor mounted proximate a distal end of an endoscopic shaft and positioned to sense at least one characteristic of an environment in which the distal end is located;
a data signal transmission line connected to the sensor to transmit data signals between the sensor and a signal processor, via a transceiver circuit, wherein the transceiver circuit isolates the sensor from earth grounded elements communicating with the sensor;
a floating ground element coupled to provide an electrical reference for the sensor; and
an electrical power transmission line connected to the sensor to transmit power to the sensor, wherein the electrical power transmission line transmits power from a power regulator that converts ground-referenced power received from an earth ground referenced power source into floating ground element referenced power,
wherein:
an overall capacitance between the electrical power transmission line and the floating ground element is larger than an overall capacitance between the floating ground element and earth ground, and
a capacitance of the endoscopic system relative to earth ground maintains current leakage from one or more applied parts of the endoscopic system to a patient within a predetermined current leakage threshold.
17. The endoscopic system of claim 16 , wherein:
the sensor is configured to transmit sensor data through the data signal transmission line by a differential mode.
18. The endoscopic system of claim 16 , wherein,
a ratio of the capacitance between the electrical power transmission line and the floating ground element to the capacitance between the floating ground element and earth ground is in a range of from 10,000 to 1 to 55,000 to 1.
19. The endoscopic system of claim 16 , wherein:
the transceiver circuit comprises an optical transceiver electrically coupled to the data signal transmission line and to an optical interface.
20. The endoscopic system of claim 16 , wherein the capacitance of the endoscopic system relative to earth ground is less than 500 pF under a condition of an earth ground referenced power source providing a nominal 230 volts under alternating current at 60 Hertz.