Patent Description:
Electrosurgery involves application of high radio frequency ("RF") electrical current to a surgical site to cut, ablate, desiccate, or coagulate tissue. In monopolar electrosurgery, a source or active electrode delivers RF alternating current from the electrosurgical generator to the targeted tissue. A patient return electrode is placed remotely from the active electrode to conduct the current back to the generator.

In bipolar electrosurgery, return and active electrodes are placed in close proximity to each other such that an electrical circuit is formed between the two electrodes (e.g., in the case of an electrosurgical forceps). In this manner, the applied electrical current is limited to the body tissue positioned between the electrodes. Accordingly, bipolar electrosurgery generally involves the use of instruments where it is desired to achieve a focused delivery of electrosurgical energy between two electrodes.

Electrosurgical generators may include planar magnetic devices, (e.g., transformers and/or inductors), which are constructed using multilayered printed circuit boards. Planar magnetic devices are commonly used to increase magnetic coupling between conducting layers while decreasing skin effect by taking advantage of the proximity and large surface areas of the parallel planes. However, this also increases voltage coupling. This can result in decreased high frequency performance of the planar components, such as increased crosstalk and susceptibility to external electromagnetic interference ("EMI") from the electrosurgical generator. Conventional, e.g., non-planar, magnetic devices usually include EMI shields, such as solid or mesh copper shields, which are not suitable in planar magnetic devices. Although adding a solid or mesh electrostatic shield to a planar magnetic device would shield the device, it would also render the device non-functional. In conventional magnetic devices, a solid shield can be added incorporated into the device because the three dimensional shape of the magnetic device allows the shield to be placed orthogonally to the magnetic field, thereby avoiding any interaction between the field and the shield. However, a planar magnetic device, which is effectively a two dimensional structure, construction techniques limit placement of the solid shields in the desired location, with respect to blocking EMI. <CIT>) and <CIT>) describe electronic devices with PCBs having a planar magnetic device and an overlapping shield assembly.

Furthermore, any such shielding conductors disposed near the winding of the planar component would diminish the magnetic field of the signal, which would generate strong currents, effectively shorting the windings of the planar component. Thus, there remains a need to shield planar magnetics from stray electromagnetic fields.

The present invention provides an electronic device as defined in claim <NUM> appended hereto. The device includes: a multilayered dielectric substrate including a plurality of dielectric layers; a planar magnetic device disposed on at least one internal dielectric layer of the plurality of the dielectric layers; and an overlapping shield assembly including a first shield layer and a second shield layer separated by at least one of the plurality of dielectric layers.

According to one aspect of the above embodiment, the planar magnetic device is a sense transformer. The sense transformer includes: a first outer coil configured to detect a first magnetic field generated by a current; a second outer coil configured to detect the first magnetic field, the second outer coil further configured to cancel an electrical field induced in the first outer coil; and an inner conductor disposed between the first outer coil and the second outer coil, the inner conductor configured to detect a second magnetic field generated by the current. Each of the first outer coil, the second outer coil, and the inner conductor is disposed on a corresponding internal dielectric layer of the plurality of dielectric layers.

According to another embodiment of the present disclosure, an electrosurgical generator is disclosed as defined in claim <NUM> appended hereto. The electrosurgical generator includes: a power supply configured to output a direct current; a power converter coupled to the power supply, the power converter configured to convert the direct current into a radio frequency current; at least one lead coupling the power converter to a terminal configured to couple to an electrosurgical instrument; and a current sensor configured to sense the radio frequency current. The current sensor includes: a multilayered dielectric substrate including a plurality of dielectric layers; at least one component of the current sensor disposed on at least one internal dielectric layer of the plurality of the dielectric layers; and an overlapping shield assembly including a first shield layer and a second shield layer separated by at least one of the plurality of dielectric layers.

The first shield layer includes a plurality of first strips and the second shield layer includes a plurality of second strips. Each of the plurality of first strips has a first width and the plurality of first strips are separated by a first gap width. Each of the plurality of second strips has a second width and the plurality of second strips are separated by a second gap width. The first width may be substantially equal to the second gap width and the second width is substantially equal to the first gap width.

, The first shield layer includes a first perimeter conductor coupled to each of the plurality of first strips and the second shield layer includes a second perimeter conductor coupled to each of the plurality of second strips. The first shield layer is electrically coupled to the second shield layer.

The present disclosure may be understood by reference to the accompanying drawings, when consideredin conjunction with the subsequent detailed description, in which:.

Particular embodiments of the present disclosure will be described below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Those skilled in the art will understand that embodiments of the present disclosure may be adapted for use with any electrosurgical system, generator, and/or instrument. It should also be appreciated that different electrical and mechanical connections and other considerations may apply to each particular type of instrument.

Briefly, an overlapping shield assembly according to the present disclosure is described below with respect to shielding planar magnetic devices in an electrosurgical generator. Although the present disclosure is described with respect to an electrosurgical generator, it is envisioned that the overlapping shield assembly may be utilized with any planar magnetic device in any electronic device in which EMI protection is desired.

The electrosurgical generator according to the present disclosure may be used in monopolar and/or bipolar electrosurgical procedures, including, for example, cutting, coagulation, ablation, and vessel sealing procedures. The generator may include a plurality of outputs for interfacing with various electrosurgical instruments (e.g., monopolar instruments, return electrode pads, bipolar electrosurgical forceps, footswitches, etc.). Further, the generator may include electronic circuitry configured to generate radio frequency energy specifically suited for powering electrosurgical devices operating in various electrosurgical modes (e.g., cut, blend, coagulate, division with hemostasis, fulgurate, spray, etc.) and procedures (e.g., monopolar, bipolar, vessel sealing).

Referring to <FIG>, an electrosurgical system <NUM> according to the present disclosure includes one or more monopolar electrosurgical instruments <NUM> having one or more active electrodes <NUM> (e.g., electrosurgical cutting probe, ablation electrode(s), etc.) for treating tissue of a patient. Electrosurgical alternating RF current is supplied to the instrument <NUM> by a generator <NUM> via a supply line <NUM> that is connected to an active terminal <NUM> (<FIG>) of the generator <NUM>, allowing the instrument <NUM> to cut, coagulate, and/or otherwise treat tissue. The RF current is returned to the generator <NUM> through a return electrode pad <NUM> via a return line <NUM> at a return terminal <NUM> (<FIG>) of the generator <NUM>. For monopolar operation, the system <NUM> may include a plurality of return electrode pads <NUM> that, in use, are disposed on a patient to minimize the chances of tissue damage by maximizing the overall contact area with the patient. In addition, the generator <NUM> and the return electrode pads <NUM> may be configured for monitoring tissue-to-patient contact to ensure that sufficient contact exists therebetween.

The system <NUM> may also include one or more bipolar electrosurgical instruments, for example, a bipolar electrosurgical forceps <NUM> having one or more electrodes for treating tissue of a patient. The electrosurgical forceps <NUM> includes a housing <NUM> and opposing jaw members <NUM> and <NUM> disposed at a distal end of a shaft <NUM>. The jaw members <NUM> and <NUM> have one or more active electrodes <NUM> and a return electrode <NUM> disposed therein, respectively. The active electrode <NUM> and the return electrode <NUM> are connected to the generator <NUM> through cable <NUM> that includes the supply and return lines <NUM>, <NUM>, which may be coupled to the active and return terminals <NUM>, <NUM>, respectively (<FIG>). The electrosurgical forceps <NUM> is coupled to the generator <NUM> at a port having connections to the active and return terminals <NUM> and <NUM> (e.g., pins) via a plug (not shown) disposed at the end of the cable <NUM>, wherein the plug includes contacts from the supply and return lines <NUM>, <NUM> as described in more detail below.

With reference to <FIG>, a front face <NUM> of the generator <NUM> is shown. The generator <NUM> may include a plurality of ports <NUM>-<NUM> to accommodate various types of electrosurgical instruments (e.g., monopolar electrosurgical instrument <NUM>, electrosurgical forceps <NUM>, etc.).

The generator <NUM> includes a user interface <NUM> having one or more display screens <NUM>, <NUM>, <NUM> for providing the user with variety of output information (e.g., intensity settings, treatment complete indicators, etc.). Each of the screens <NUM>, <NUM>, <NUM> is associated with a corresponding port <NUM>-<NUM>. The generator <NUM> includes suitable input controls (e.g., buttons, activators, switches, touch screen, etc.) for controlling the generator <NUM>. The screens <NUM>, <NUM>, <NUM> are also configured as touch screens that display a corresponding menu for the instruments (e.g., electrosurgical forceps <NUM>, etc.). The user can adjust inputs by simply touching corresponding menu options.

Screen <NUM> controls monopolar output and the devices connected to the ports <NUM> and <NUM>. Port <NUM> is configured to couple to a monopolar electrosurgical instrument (e.g., electrosurgical instrument <NUM>) and port <NUM> is configured to couple to a foot switch (not shown). The foot switch provides for additional inputs (e.g., replicating inputs of the generator <NUM>). The port <NUM> is configured to couple to the return electrode pad <NUM>. Screen <NUM> controls monopolar and bipolar output and the devices connected to the ports <NUM> and <NUM>. Port <NUM> is configured to couple to other monopolar instruments. Port <NUM> is configured to couple to a bipolar instrument (e.g., electrosurgical forceps <NUM>).

Screen <NUM> controls the electrosurgical forceps <NUM> that may be plugged into one of the ports <NUM> and <NUM>, respectively. The generator <NUM> outputs energy through the ports <NUM> and <NUM> suitable for sealing tissue grasped by the electrosurgical forceps <NUM>. In particular, screen <NUM> outputs a user interface that allows the user to input a user-defined intensity setting for each of the ports <NUM> and <NUM>. The user-defined setting may be any setting that allows the user to adjust one or more energy delivery parameters, such as power, current, voltage, energy, etc. or sealing parameters, such as energy rate limiters, sealing duration, etc. The user-defined setting is transmitted to a controller <NUM> (<FIG>) where the setting may be saved in a memory (not shown). In embodiments, the intensity setting may be a number scale, such as for example, from one to ten or one to five. In embodiments, the intensity setting may be associated with an output curve of the generator <NUM>. The intensity settings may be specific for each electrosurgical forceps <NUM> being utilized, such that various instruments provide the user with a specific intensity scale corresponding to the electrosurgical forceps <NUM>. The active and return terminals <NUM> and <NUM> (<FIG>) may be coupled to any of the desired ports <NUM>-<NUM>.

With reference to <FIG>, the generator <NUM> also includes a controller <NUM>, a power supply <NUM>, and a power converter <NUM>. The power supply <NUM> may be a high voltage, DC power supply connected to an AC source (e.g., line voltage) and provides high voltage, DC power to the power converter <NUM>, which then converts high voltage, DC power into RF energy and delivers the energy to the active terminal <NUM>. (<FIG>) The energy is returned thereto via the return terminal <NUM>. In particular, electrosurgical energy for energizing the monopolar electrosurgical instrument <NUM> and/or electrosurgical forceps <NUM> is delivered through the active and return terminals <NUM> and <NUM>. The active and return terminals <NUM> and <NUM> are coupled to the power converter <NUM> through an isolation transformer <NUM>. More specifically, the isolation transformer <NUM> includes a primary winding 340a coupled to the power converter <NUM> and a secondary winding 340b having an active lead <NUM> coupled to the active terminal <NUM> and a return lead <NUM> coupled to the return terminal <NUM>. The output of power converter <NUM> transmits current through the isolation transformer <NUM> to the load "Z", e.g., tissue being treated.

The power converter <NUM> is configured to operate in a plurality of modes, during which the generator <NUM> outputs corresponding waveforms having specific duty cycles, peak voltages, crest factors, etc. It is envisioned that in other embodiments, the generator <NUM> may be based on other types of suitable power supply topologies. Power converter <NUM> may be a resonant RF amplifier or a non-resonant RF amplifier. A non-resonant RF amplifier, as used herein, denotes an amplifier lacking any tuning components, e.g., inductors, capacitors, etc., disposed between the power converter and the load "Z" intended to establish a fixed operating frequency.

The controller <NUM> includes a processor (not shown) operably connected to a memory (not shown), which may include one or more of volatile, non-volatile, magnetic, optical, or electrical media, such as read-only memory (ROM), random access memory (RAM), electrically-erasable programmable ROM (EEPROM), non-volatile RAM (NVRAM), or flash memory. The processor may be any suitable processor (e.g., control circuit) adapted to perform the operations, calculations, and/or set of instructions described in the present disclosure including, but not limited to, a hardware processor, a field programmable gate array (FPGA), a digital signal processor (DSP), a central processing unit (CPU), a microprocessor, and combinations thereof. Those skilled in the art will appreciate that the processor may be substituted for by using any logic processor (e.g., control circuit) adapted to perform the calculations and/or set of instructions described herein.

The controller <NUM> includes output ports that are operably connected to the power supply <NUM> and/or the power converter <NUM> allowing the controller <NUM> to control the output of the generator <NUM> according to either open and/or closed control loop schemes. A closed loop control scheme is a feedback control loop, in which a plurality of sensors measure a variety of tissue and energy properties (e.g., tissue impedance, tissue temperature, output power, current and/or voltage, etc.), and provide feedback to the controller <NUM>. The controller <NUM> then controls the power supply <NUM> and/or the power converter <NUM>, which adjusts power delivered to and/or from the power converter <NUM>, respectively. The controller <NUM> also receives input signals from the input controls of the generator <NUM>, the electrosurgical instrument <NUM> and/or electrosurgical forceps <NUM>. The controller <NUM> utilizes the input signals to adjust power outputted by the generator <NUM> and/or performs other control functions thereon.

The controller <NUM> may perform various mathematical computations in order to control the power supply <NUM> and/or the power converter <NUM> to generate an RF waveform having a desired shape and energy content. Examples of computations performed by the controller <NUM> include, but are not limited to, calculating instantaneous and/or root mean square power levels, amount of energy delivered on a cycle by cycle basis, load impedance, etc..

The generator <NUM> according to the present disclosure may also include a plurality of sensors, namely, a voltage sensor <NUM> and a current sensor <NUM>. The voltage sensor <NUM> is coupled to the active and return leads <NUM>, <NUM> and measure RF voltage supplied to the active and return terminals <NUM>, <NUM>. The current sensor <NUM> is coupled to the active and/or return leads <NUM>, <NUM> and measures RF current supplied to the active and return terminals <NUM>, <NUM>. In embodiments, the generator <NUM> may also include additional sensors (not shown) coupled to the power supply <NUM>.

With reference to <FIG> and <FIG>, the current sensor <NUM> includes a planar magnetic device <NUM>, e.g., a current sense coil, which is disposed on a printed circuit board ("PCB") <NUM>. The PCB <NUM> may be a multilayer PCB formed from any suitable dielectric material, including, but not limited to composite materials composed of woven fiberglass cloth with an epoxy resin binder such as FR-<NUM> grade as designated by the National Electrical Manufacturers Association. The PCB <NUM> defines an opening <NUM> therethrough for passage of the active lead <NUM>. The planar magnetic device <NUM> includes an outer coil <NUM> and an inner conductor <NUM>. The outer coil <NUM> is formed by a plurality of upper and lower conductive traces 470a and 470b interconnected by a plurality of inner conductive vias 470c and outer conductive vias 470d. The upper and lower conductive traces 470a and 470b may be printed on respective upper and lower surfaces 400a, 400b (<FIG>) of the PCB <NUM>. The inner conductor <NUM> is disposed in between the upper and lower conductive traces 470a and 470b and is embedded within the PCB <NUM> (<FIG>).

<FIG> shows an overlapping shield assembly <NUM> disposed over the upper surface 400a of the PCB <NUM>. The overlapping shield assembly <NUM> includes a first layer <NUM> and a second layer <NUM>, which are separated by one or more dielectric layers 400c, 400d,. 400n of the PCB <NUM>. In embodiments, the overlapping shield assembly <NUM> may also be disposed on the bottom surface 400b of the PCB <NUM>. In other embodiments, the overlapping shield assembly <NUM> may be disposed internally, i.e., within the planar magnetic device <NUM>, namely, between the upper conductive traces 470a and lower conductive traces 470b. This configuration provides significant internal device E-field shielding and isolation and is suitable to control crosstalk and leakage currents. In further embodiments, the first layer <NUM> may be disposed on the upper surface 400a of the PCB <NUM> and the second layer <NUM> may be disposed on the lower surface 400b of the PCB <NUM>. A single layer of shielding (e.g., the first layer <NUM> or the second layer <NUM>) may be on each surface 400a, 400b of the PCB <NUM> and may provide sufficient E-field shielding and may be adequate for many applications. In additional embodiments, a pair of overlapping shield assemblies <NUM> may be disposed on the PCB <NUM>, one on each surface 400a, 400b, respectively, to provide an additional order of magnitude of shielding.

With reference to <FIG>, the first and second layers <NUM> and <NUM> may be formed as conductive traces on their corresponding dielectric layers 400c and 400d (<FIG>) of the PCB <NUM>. Thus, the first layer <NUM> is disposed in a first plane "A-A" and the second layer <NUM> is disposed in a second plane "B-B" (<FIG>). Each of the layers <NUM> and <NUM> includes a plurality of strips <NUM> and <NUM>, respectively. The strips <NUM> and <NUM> are arranged in parallel with periodic gaps <NUM> and <NUM> that are defined therebetween. As shown in <FIG>, the strips <NUM> of the first layer <NUM> have a strip width s1 and the gaps <NUM> have a gap width w1. Similarly, the strips <NUM> of the second layer <NUM> have a strip width s2 and the gaps <NUM> have a gap width w2. The strip width s1 of the strips <NUM> is substantially equal to the gap width w2 of the gaps <NUM> of the second layer <NUM> and conversely, strip width s2 of the strips <NUM> is substantially equal to the gap width w1 of the gaps <NUM> of the first layer <NUM>. This configuration allows for the strips <NUM>, <NUM> and the gaps of <NUM>, <NUM> to overlap, respectively, thus forming an EMI shield.

Strip widths s1 or s2 may be from about <NUM> millimeters (mm) to about <NUM>, in embodiments from about <NUM> to about <NUM>. Since gap widths w1 and w2 are related to the strip widths s1 and s2, gap widths w1 and w2 may also have the same dimensions. In further embodiments, the strip width s1 or s2 of each of the strips <NUM> and <NUM> may be different, i.e., have a non-uniform width.

Each of the first layer <NUM> and the second layer <NUM> also includes a perimeter conductor <NUM> and <NUM>, respectively. The perimeter conductor <NUM> is coupled to each of the strips <NUM> of the first layer and the perimeter conductor <NUM> is coupled to each of the strips <NUM> of the second layer <NUM>. In addition, the first and second layers <NUM> and <NUM> are interconnected by one or more conductors <NUM> to form the EMI shield.

Because the strips <NUM> and <NUM> are spaced apart, i.e., do not form a continuous conductive surface across one plane "A-A" or "B-B," respectively, and are open ended, they do not form a complete circuit for stray current to flow therethrough. Furthermore, because the strips <NUM> and <NUM> are relatively narrow, Eddy currents, also known as Foucalt currents, do not have a significant impact. However, because the first and second layers <NUM> and <NUM> are separated by one or more PCB layers of the PCB <NUM>, the height between the layers is comparatively small, thereby forming a continuous surface when viewed along an axis "C-C," which is transverse with respect to each of the planes "A-A" and "B-B" (<FIG>). Put differently, the first and second layers <NUM> and <NUM> complement each other to form, i.e., complete, the overlapping shield assembly <NUM>.

Claim 1:
An electronic device comprising:
a multilayered dielectric substrate (<NUM>) including a plurality of dielectric layers (400c, 400d...400n);
a planar magnetic device (<NUM>) disposed on at least one internal dielectric layer of the plurality of dielectric layers; and
an overlapping shield assembly (<NUM>) including a first shield layer (<NUM>) and a second shield layer (<NUM>) separated by at least one of the plurality of dielectric layers (400c, 400d... .400n) wherein the first shield layer includes a plurality of first strips (<NUM>) and the second shield layer includes a plurality of second strips (<NUM>), wherein each of the plurality of first strips (<NUM>) has a first width (s1) and the plurality of first strips are separated by a first gap width (w1) wherein the first shield layer (<NUM>) includes a first perimeter conductor (<NUM>) coupled to each of the plurality of first strips (<NUM>) and the second shield layer (<NUM>) includes a second perimeter conductor (<NUM>) coupled to each of the plurality of second strips (<NUM>), wherein each of the plurality of second strips has a second width (s2) and the plurality of second strips are separated by a second gap width (w2)
characterized in that
the first and second layers have a configuration which complements the other to form the overlapping shield assembly.