Patent ID: 12232694

In the drawings, the first digit of a three digit reference numeral is the figure number in which the element having that reference numeral first appeared.

DETAILED DESCRIPTION

In surgical system100, typically a cable runs between endoscope135-1and imaging system192. The cable has a significant capacitance to ground. When one of the instruments in surgical system100includes or is an energized cautery tool, the cautery tool's energy source provides high frequency energy with the main energy being located in the 400 kHz to 500 kHz range and with harmonics up to the 4 MHz range. The cautery tool energy source can unintentionally supply energy to any object that has a path to ground (earth) by a direct wired connection or by capacitive coupling. The cautery tool energy source can source this energy from either of its two output leads: (1) the High Voltage lead which connects to the cautery tool or (2) the Patient Return lead normally connected to the patient's body.

The cautery tool energy source can drive current into the endoscope's metal shaft137-1by virtue of the shaft being electrically connected to the cable which has a large capacitance to earth. The current can travel by two paths: (1) from the cautery tool energy source High Voltage lead being capacitively coupled (wrapped around) the endoscope cable, or (2) from patient's body (which is connected to the Patient Return lead) touching the endoscope shaft. During cautery activation unintended current flow may cause arcing at the patient-tissue-endoscope-shaft interface. An arc at the patient's tissue, may burn the tissue, and of course is undesirable.

Endoscope200(FIG.2) reduces the unintended current flow by inserting a high impedance component215(which may be high impedance at all signal frequencies, or only within a range of frequencies such as at cautery frequencies) between the endoscope body, e.g., housing201(sometimes referred to as body201), and the large capacitance to ground of cable205. This high impedance component215may also be called a common-mode choke215. Cable205connects endoscope200to imaging system292. Imaging system292is equivalent to imaging system192. At the same time, in various embodiments, component215must not have a high impedance for the data and power wires of cable205. In one aspect, this component is a common-mode choke215. The data and power are differential signals (traveling down one wire and returning on it companion ground wire, whereas the cautery current tries to travel in common down all the wires). Common-mode choke215behaves as a high impedance for common-mode currents and as a low impedance for differential currents.

Common-mode choke215is included within housing201of endoscope200. Common-mode choke215is connected between cable205and a circuit board210and connected between a shield of cable205and housing201, sometimes referred to as body201. In one aspect, common-mode choke215is mounted on circuit board210. Common-mode choke215has an inductance in the tens of millihenries, e.g., 30 millihenries in one aspect, and so attenuates any common-mode current on cable205by over a factor of three. This attenuation is sufficient to reduce the common-mode cautery current to levels accepted by international standards. Common-mode choke215has minimal stray capacitance between its input and output leads. The signal coupling between parallel windings of common-mode choke215is small enough that signal integrity is not compromised.

In one aspect, endoscope200includes a plurality of image capture units in the distal end of main tube202. An illuminator in endoscope200provides light to the distal end of main tube202. Arrow290defines the proximal direction and the distal direction inFIGS.2,4A, and4B.

The circuits included within housing201of endoscope200that power the illuminator and the image capture units, move data from the image capture units to imaging system292, etc. are represented by circuit board210. Circuit board210, in some instances, may be implemented by more than one circuit board. Circuit board210is coupled to units in the distal end of main tube by a cable203. There may be other cables that run from circuit board210to other elements housed within housing201. The size and shape of housing201is fixed by the need for endoscope200to be in close proximity to other instruments, as shown inFIG.1, and to not collide with the other instruments or inhibit the range of motion of the other instruments.

Cable205includes, in one aspect, a power line, a ground line, signal lines, and a shield that encloses these lines. The power line, ground line, and signal lines together are sometimes referred to as a first plurality of wires. For example, a cross-sectional view of cable205is shown inFIG.2and shows the first plurality of wires206(represented inFIG.2by a dashed circle) enclosed by a shield207. Thus, in this aspect, the first plurality of wires is encased in a shield. Cable205is connected to housing201. However, in connecting cable205to housing201, neither the shield nor any of the wires in cable205are permitted to contact housing201.

Common-mode choke215is connected to the first plurality of wires and, in this aspect, is connected to circuit board210, i.e., is connected between cable205and circuit board210. The shield of cable205is also connected thru common-mode choke215to a ground204on housing201. The shield of cable205is electrically isolated from housing201of endoscope200by common-mode choke215, and the shield does not touch any electrically conductive part that is connected to housing201.

Common-mode choke215includes a plurality of non-overlapping windings. A beginning winding in the plurality of non-overlapping windings is separated from an ending winding of the plurality of non-overlapping windings. Since the windings of common-mode choke215do not overlap and the beginning winding is separated from the ending winding, there is minimal capacitance across the input and output leads of common-mode choke215. In this aspect, the core of common-mode choke215does not have an opening and is selected to have the highest AL-value (number of millihenries per turn) possible for the size of the core.

FIG.3Ais an illustration of common-choke315, an embodiment of common-mode choke215.FIG.3Bis a schematic diagram of common-mode choke315. In this aspect, cable205includes a ground line, a power line, four signal lines and the shield surrounding these lines. After cable205enters housing201, the ground line and the shield are twisted together so that there are six lines, a shield and ground line combination, a power line, and four signal lines.

Common-mode choke315includes a second plurality of wires340, which in this example, is six wires. Prior to being wound on core320, second plurality of wires340are twisted together to form a set of twisted wires330. Set of twisted wires330has a first lead330-1, a second lead330-2, and a portion between first lead330-1and second lead330-2. Similarly, each wire of the second plurality of wires340has a first end340-1, a second end340-2and a portion between first end340-1and second end340-2.

Set of twisted wires330, sometime referred to as wires330, are wound around core320so that the windings do not overlap. Avoiding overlap of the windings has several advantages. There is minimal capacitance created between winding, and this helps to minimize the input-to-output capacitance of common-mode choke315.

Since there are no overlapping windings, there is no concern about arcing between overlapping windings due to insulation failure. In one aspect, the common-mode voltage is about 3000 volts, and, in this aspect, common-mode choke315has 28 windings. Thus, each winding drops around 107 volts, which is well within the capability of conventional wire insulation. Thus, the non-overlapping windings eliminate any concern about the insulation on wires330failing.

A first winding331, a beginning winding, around core320is separated by a gap321from a last winding332, an ending winding, around core320. Gap321separates input lead330-1, a first lead, from output lead330-2, a second lead, which also helps to minimize the capacitance of common-mode choke315and also helps to prevent arching between the first lead and second lead. As shown inFIG.3A, the windings around core320have a letter “C” shape, where gap321in the windings is the opening in the letter “C” shape. The size of gap321is selected so that there is no possibility of arcing between input lead330-1and output lead330-2.

Core320is a ferrite toroid core or a ferrite bobbin/pot core. In one aspect, core320is a nano-crystalline ferrite core without a gap. This core material provides a much higher inductance per turn compared to other core materials, which results in less stray capacitance from input lead330-1to output lead330-2. In one aspect, core320is a nano-crystalline ferrite core in a plastic casing. This core has properties such as those in Table 1.

TABLE 1Nominal Core DimensionsOuter Diameter16 mmInner Diameter10 mmHeight6 mmIron Cross SectionAFe0.14 cm2AL10 KHz43.0 μH100 kHz10.1 μHSaturation Current Icm10 KHz0.3 A100 kHz0.6 A

A core having these properties is commercially available from Vacuumschmelze GMBH & Co., Gruner Weg 37, D 63450 Hanau, Germany under Part No. T6006-L2016-W403. While the dimensions of the core are given in Table 1, the cross sectional area of the core is a key factor in setting the maximum current the core can handle before the core saturates (where the inductance droops to a lower value). Another core choice with different dimensions is just as effective if that core has approximately the same AL value and cross-sectional area.

Each of the six wires in the twisted set of wires in input lead330-1of common-mode choke315are either connected to (FIGS.2and4A) or are coupled to (FIG.4B) a different one of the six wires (a shield and ground line combination, a power line, and four signal lines) of cable205. Thus, each of the six wires—an example of a plurality of wires—in the twisted set of wires in input lead330-1are coupled to a different one of the six wires (a shield and ground line combination, a power line, and four signal lines) of cable205.

One of the six wires in the twisted set of wires in output lead330-2of common-mode choke315—the one coupled to the a shield and ground line combination of cable205—is connected to a ground204. The other wires in the six wires in the twisted set of wires in output lead330-2of common-mode choke315are coupled to circuit board210.

While in this aspect, a gapless nano-crystalline ferrite is used, in other aspects, a gapless ferrite core could be used if the performance characteristics of the gapless ferrite core are acceptable for the common mode currents encountered during a surgical procedure and if there is space for the resulting common-mode choke within the instrument. Similarly, a gapped ferrite core could be used if the performance characteristics of the gapped ferrite core are acceptable for the common mode currents encountered during a surgical procedure and if there is space for the resulting common-mode choke within the instrument.

Electrical optical couplers have been considered in electrically isolating cable205from housing201of endoscope400A. Typically, an electrical optical coupler functions properly so long as the common-mode voltages are less than about 25,000 volts/microsecond. With an arcing cautery instrument, a typical voltage is 3000 volts, and the rise time of the arc is on the order of five to ten nanoseconds, which results in about 500,000 volts/microsecond. Hence, an electrical optical coupler alone would not work properly in the presence of common-mode voltages generated by an arcing cautery instrument. However, a common-mode choke combined with an electrical optical coupler attenuates the common-mode voltage so that the electrical optical coupler works properly.

FIGS.4A and4Billustrate two equivalent ways of utilizing a common-mode choke with an optical coupler. InFIG.4A, common-mode choke415A is inserted between an electrical optical coupler416A on circuit board210A and cable205. In one aspect, common mode choke415A is also mounted on circuit board210A. InFIG.4B, electrical optical coupler416B is on a circuit board410and cable205is connected to optical coupler416B. Common mode choke415B is connected between electrical optical coupler416B and circuit board210.

Common-mode chokes415A and415B are constructed in a way that is equivalent to the way that common-mode choke215was constructed, except common-mode chokes415A and415B are each smaller than common-mode choke215. While common-mode choke215has an inductance in the tens of millihenries, each of common-mode chokes415A and415B has an inductance of about 100 microhenries. This means that a smaller core and a smaller number of windings can be used. However, the windings still do not overlap and the first winding is separated from the last winding so that the windings have the letter “C” shape. The other aspects of common-mode chokes415A and415B are the same as common-mode choke215, and so are not repeated here.

As used herein, “first,” “second,” “third,” etc. are adjectives used to distinguish between different components or elements. Thus, “first,” “second,” and “third” are not intended to imply any ordering of the components or elements or to imply any total number of components or elements.

The above description and the accompanying drawings that illustrate aspects and embodiments of the present inventions should not be taken as limiting—the claims define the protected inventions. Various mechanical, compositional, structural, electrical, and operational changes may be made without departing from the spirit and scope of this description and the claims. In some instances, well-known circuits, structures, and techniques have not been shown or described in detail to avoid obscuring the invention.

Further, this description's terminology is not intended to limit the invention. For example, spatially relative terms—such as “beneath”, “below”. “lower”, “above”, “upper”, “proximal”, “distal”, and the like—may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., locations) and orientations (i.e., rotational placements) of the device in use or operation in addition to the position and orientation shown in the figures. For example, if the device in the figures were turned over, elements described as “below” or “beneath” other elements or features would then be “above” or “over” the other elements or features. Thus, the exemplary term “below” can encompass both positions and orientations of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Likewise, descriptions of movement along and around various axes include various special device positions and orientations.

The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. The terms “comprises”, “comprising”, “includes”, and the like specify the presence of stated features, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups. Components described as coupled may be electrically or mechanically directly coupled, or they may be indirectly coupled via one or more intermediate components.

All examples and illustrative references are non-limiting and should not be used to limit the claims to specific implementations and embodiments described herein and their equivalents. Any headings are solely for formatting and should not be used to limit the subject matter in any way, because text under one heading may cross reference or apply to text under one or more headings. Finally, in view of this disclosure, particular features described in relation to one aspect or embodiment may be applied to other disclosed aspects or embodiments of the invention, even though not specifically shown in the drawings or described in the text.

Embodiments described above illustrate but do not limit the disclosure. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the present disclosure. For example, in many aspects the devices described herein are used as single-port devices; i.e., all components necessary to complete a surgical procedure enter the body via a single entry port. In some aspects, however, multiple devices and ports may be used.