1. Field of the Invention
This application relates generally to in situ conditioning of electrodes in electrohydrodynamic (EHD) or electrostatic fluid handling devices such as EHD air movers.
2. Related Art
Many modern electronic devices (including desktop and laptop computers, all-in-one computers, televisions, video displays and projectors) employ forced air flow as part of a thermal management solution. Mechanical air movers such as fans or blowers have conventionally been employed in many such devices. However, in some applications and devices, mechanical air mover operation may result in undesirable levels of noise or vibration that may degrade the user experience. In some cases, physical scale or flow paths that would otherwise be necessary to accommodate a mechanical air mover may be incompatible with, or unacceptably limit, the design, scale or form factor of a particular design. Worse still, at the extremely thin device form factors popular in certain consumer electronics (e.g., laptops, pad-type computers, televisions, smartphones, book readers and media players), mechanical air mover designs (if even accommodatable) tend to exhibit poor cooling efficiencies. As a result, battery life may be adversely affected or, as a practical matter, device performance throttled to a level compatible with passive cooling.
Technologies have been developed that employ electric fields and principles of ionic movement of a fluid to motivate air flow. Devices that operate based on such principles are variously referred to in the literature as ionic wind machines, electric wind machines, corona wind pumps, electro-fluid-dynamics (EFD) devices, electrohydrodynamic (EHD) thrusters and EHD gas pumps. Some aspects of the technology have been exploited in devices referred to as electrostatic air cleaners or electrostatic precipitators and, indeed, some practical large scale device applications of the technology date back to the early 1900s. More recently, researchers have considered the utility of EHD air movers as part of a thermal management solution in consumer electronics devices. See generally, N. E. Jewell-Larsen, H. Ran, Y. Zhang, M. Schwiebert and K. A. Honer, Electrohydrodynamic (EHD) Cooled Laptop, in proceedings of 25th Annual Semiconductor Thermal Measurement and Management Symposium (March 2009).
In some cases, an ion flow or EHD air mover may improve cooling efficiency and thermal management in some devices and/or applications, while reducing noise, vibration and power consumption. Likewise, EHD air mover designs may provide or facilitate systems or devices that have reduced overall device lifetime costs, device size or volume, and/or improved electronic device performance or user experience.
Ozone (03), while naturally occurring, can also be produced during operation of various electronics devices including EHD devices, photocopiers, laser printers and electrostatic air cleaners, and by certain kinds of electric motors and generators, etc. At high concentrations, ozone can be undesirable and, accordingly, techniques to reduce ozone concentrations are desired. Indeed, techniques have been developed to catalytically or reactively break down ozone (O3) into the more stable diatomic molecular form (O2) of oxygen. See e.g., U.S. Pat. No. 6,603,268 to Lee and U.S. Patent Application Publication 2010-0116469, naming Jewell Larsen et al. as inventors, each of which is commonly-owned by the assignee of the present application.
Improved techniques for ozone management and/or abatement are desired.
It has been discovered that cleaning and otherwise conditioning electrode surfaces can provide significant performance and operational benefits in EHD devices. In particular, conditioning of emitter electrode surfaces with silver (Ag), silver compositions or silver preparations applied in situ at successive times throughout the operating lifetime of an EHD air mover has been found to significantly reduce ozone production, in some cases by 50% or more. Structures and techniques are described for in situ conditioning electrode surfaces and, in particular, emitter electrode surfaces of an EHD device such as an air mover or precipitator, with a conditioning material that includes silver.
In some embodiments in accordance with the present invention, an apparatus includes an electrohydrodynamic (EHD) device that includes an emitter electrode energizable to motivate ion flow and a conditioning surface to frictionally engage the emitter electrode. The conditioning surface and a frictionally engaged surface of the emitter electrode are movable relative to one another to, at successive times throughout the operating life of the apparatus, deposit a conditioning material comprising silver on the frictionally engaged surface of the emitter electrode.
In some cases, the conditioning material comprising silver includes one or more of elemental silver, an oxide of silver, an alloy of silver and an organometallic silver compound. In some cases, conditioning material comprising silver further includes a material selected to at least partially mitigate at least one of electrode erosion, corrosion, oxidation, silica adhesion and dendrite formation. In some cases, the conditioning material comprising silver further includes graphite. In some cases, the conditioning material comprising silver deposited on the emitter electrode at the successive times throughout the operating life of the apparatus constitutes a consumable ozone reducer.
In some embodiments, the emitter electrode includes at least one elongate emitter wire. In some embodiments, positioning and the relative movement of the conditioning surface and the elongate wire with respect to one another provide elastic deformation of the elongate emitter wire at a point of the frictional engagement. the conditioning surface includes a body of the conditioning material at least partially conformal with a surface of the elongate emitter wire.
In some embodiments, the apparatus further includes one or more additional conditioning surfaces positioned for frictional engagement with respective portions of the surface of the emitter electrode. In some embodiments, the apparatus further includes a carriage to which the conditioning surface is affixed; and a drive mechanism operably coupled to the carriage to cause the conditioning surface to transit at least a portion of the emitter electrode. In some embodiments, the apparatus further includes a controller operable to trigger movement, at the successive times, of one of the conditioning surface and the emitter electrode relative to the other.
In some embodiments, the EHD device includes one or more collector electrodes and is energizable to motivate air flow. In some embodiments, the apparatus further includes a heat sink, wherein the EHD device is configured to motivate the air flow past the heat sink. In some embodiments, the apparatus is packaged as one of a laptop computer, a handheld electronic device and a video display, wherein the EHD device is configured to provide the laptop computer, handheld electronic device or video display with ventilating air flow. The conditioning material comprising silver deposited on the emitter electrode at the successive times throughout the operating life of the apparatus constitutes a consumable ozone reducing material. In some embodiments, the EHD device includes one or more collector electrodes and is energizable to precipitate particulates from an air flow.
In some embodiments in accordance with the present invention, a method of managing ozone in an electrohydrodynamic (EHD) device includes (i) energizing an emitter electrode of the EHD device to motivate ion flow; and (ii) at successive times throughout the operating life of the apparatus and in situ, moving a conditioning surface and a frictionally engaged surface of the emitter electrode relative to one another to deposit a consumable conditioning material comprising silver on the frictionally engaged surface of the emitter electrode.
In some cases, the consumable conditioning material comprising silver includes one or more of elemental silver, an oxide of silver, an alloy of silver and an organometallic silver compound. In some cases, the deposited consumable conditioning material comprising silver further includes a material selected to at least partially mitigate at least one of electrode erosion, corrosion, oxidation, silica adhesion and dendrite formation. In some cases, the deposited consumable conditioning material comprising silver further includes graphite.
In some embodiments, the method further includes, at the successive times, triggering the movement based on one or more of an event and sensed or detected condition. In some cases, the triggering event is or corresponds to a power or thermal management event. In some cases, the triggering event is an timed or scheduled event. In some cases, the sensed or detected condition is indicative of electrode arcing. In some cases, the sensed or detected condition is indicative of accumulated detrimental material on the emitter electrode.
In some embodiments, the method further includes, at least during the movement, de-energizing the emitter electrode. In some embodiments, the method further includes, at the successive times throughout the operating life of the apparatus, causing a carriage to which the conditioning surface is affixed to transit at least a portion of the emitter electrode. In some cases, the method further includes, at the successive times throughout the operating life of the apparatus, transiting a cleaning surface affixed to the carriage and in frictional engagement with a collector electrode of the EHD device along a portion of the collector electrode to remove at least some detrimental material therefrom.
In some embodiments, the emitter electrode includes at least one elongate emitter wire; and the method further includes, in correspondence with the relative movement of the conditioning surface and the emitter electrode with respect to one another, elastically deforming the elongate emitter wire at a point of the frictional engagement.
In some embodiments, the method further includes motivating air flow using the EHD device. In some embodiments, the method further includes precipitating particulates from an air flow using the EHD device.
In some embodiments in accordance with the present invention, a method of making an electronic device product capable of renewing in situ a consumable ozone reducing material to at least partially abate ozone otherwise produced during operation of the electronic device product includes the following: (i) tensioning an emitter wire energizable to motivate ion flow; (ii) positioning at least one conditioning surface of a carriage to frictionally engage the emitter wire and to, when transited along the emitter wire, deposit a conditioning material comprising silver on the frictionally engaged surface of the emitter wire; and (iii) mechanically coupling the carriage to a drive mechanism operable, at successive times throughout the operating life of the electronic device product, to transit the conditioning surface along the emitter wire.
In some embodiments, the method further includes mechanically biasing the conditioning surface to elastic deform the emitter wire in correspondence with transit therealong. In some embodiments, the method further includes electrically coupling the emitter wire and at least one collector electrode proximate thereto to opposing supply voltage terminals. In some embodiments, the method further includes providing the tensioned emitter wire, the frictionally engaged conditioning surface and the mechanically coupled drive mechanism as an electrohydrodynamic (EHD) device subassembly-type electronic device product.
In some embodiments, the method further includes introducing an electrohydrodynamic (EHD) air mover device subassembly comprising the tensioned emitter wire, the frictionally engaged conditioning surface and the mechanically coupled drive mechanism into the electronic device product; and electrically coupling a power or thermal management system of the electronic device product to a controller operable to trigger the drive mechanism at the successive times throughout the operating life of the electronic device product.
In some cases, the conditioning material comprising silver includes one or more of elemental silver, an oxide of silver, an alloy of silver and an organometallic silver compound. In some cases, the conditioning material comprising silver further includes graphite.
In some embodiments in accordance with the present invention, an apparatus includes an electrohydrodynamic (EHD) fluid mover that includes emitter and collector electrodes energizable to motivate fluid flow therebetween; and a conditioning mechanism operable to, at successive times throughout the operating life of the apparatus, apply a consumable ozone catalyst to a surface of the emitter electrode.
In some cases, the consumable ozone catalyst comprises silver. In some cases, the consumable ozone catalyst is applied via wearing of a solid material in frictional contact with the emitter during movement of at least one of the emitter electrode and the conditioning mechanism. In some cases, the consumable ozone catalyst is worn from one of a series of contours arranged to induce undulation in the emitter electrode during application of the consumable ozone catalyst. In some cases, at least one of the contours is defined by a blade comprising silver.
In some cases, the conditioning mechanism further applies a conditioning material selected to at least partially mitigate at least one of emitter electrode surface erosion, corrosion, oxidation, silica adhesion, dendrite formation and mechanical adhesion of other detrimental material.
In some cases, the conditioning mechanism includes at least one of a wiper, brush, squeegee and pad configured to remove detrimental materials built up on at least one of the electrodes. In some cases, the consumable ozone catalyst is applied on the emitter electrode in situ via movement of one of the conditioning mechanism and the emitter electrode. In some cases, the conditioning mechanism is configured to induce two or more undulations in the emitter electrode. In some cases, the conditioning mechanism is further operable to remove debris accumulated on the collector electrodes.
In some cases, the the emitter electrode is configured as an endless loop trained about a drive pulley. In some cases, the emitter electrode is configured to travel between a supply spool and a take-up spool.
In some cases, the conditioning mechanism defines complementary surfaces for deflecting the emitter electrode into a controlled bend. In some cases, the complementary surfaces are configured to induce multiple undulations in the emitter electrode such that controlled bending stress in the emitter electrode contributes to break up brittle silica deposits on the emitter electrode. In some cases, the complementary surfaces themselves include undulations for inducing controlled bending stress in the emitter electrode to break up brittle silica deposits on the emitter electrode.
In some cases, the conditioning mechanism includes a frictional cleaning surface engageable with the emitter electrode. In some cases, the frictional cleaning surface comprises a wearable material comprising silver. In some cases, the frictional cleaning surface comprises one of a wiper, blade, and pad comprising silver.
In some cases, the conditioning mechanism comprises one or more surface profiles configured to provide frictional cleaning and deflection of the emitter electrode. In some cases, the emitter electrode and the collector electrodes constitute at least a portion of a thermal management assembly thermally coupled to a heat dissipating device in an electronic device.
In some embodiments of the present invention(s), a method for conditioning an electrode includes operating an electrohydrodynamic (EHD) fluid mover that includes emitter and collector electrodes energizable to motivate fluid flow therebetween; operating a conditioning mechanism at successive times between operation of the EHD fluid mover; and applying in situ, during the operating of the conditioning mechanism, a consumable ozone catalyst to a surface of the emitter electrode. In some cases, the consumable ozone catalyst comprises silver.
In some embodiments, operating the conditioning mechanism includes transiting the emitter electrode in frictional contact with a wearable cleaning surface comprising the consumable ozone catalyst. In some embodiments, operating the conditioning mechanism includes transiting a wearable cleaning surface comprising the consumable ozone catalyst in frictional contact with the emitter electrode.
In some embodiments, the method further includes moving at least one of the conditioning mechanism and the emitter electrode to thereby remove detrimental material from the emitter electrode. In some embodiments, the method further includes applying a conditioning material selected to at least partially mitigate at least one of emitter electrode surface erosion, corrosion, oxidation and dendrite formation. In some cases, the conditioning material includes at least one of silver, palladium, platinum, manganese, nickel, zirconium, titanium, tungsten, aluminum, and a respective oxide or alloy thereof.
In some embodiments, the applying of the consumable ozone catalyst is performed when the emitter electrode is not energized. In some embodiments, the applying is initiated by a controller based upon one or more of an imposed voltage level, a measured electrical potential, determination of the presence of a level of contamination by optical means, detection of an event and detection of a performance parameter.
In some embodiments, the method further includes elastically deforming the emitter electrode to remove undesirable material accumulated on the surface thereof. In some embodiments, the consumable ozone catalyst is applied on the electrode in situ via movement of one of the cleaning device and the electrode with respect to the other under control of a drive mechanism.
These and other embodiments will be understood with reference to the description herein, the drawings and the appended claims.
The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
The use of the same reference symbols in different drawings indicates similar or identical items.
Devices built using the principle of ionic movement of a fluid are variously referred to in the literature as ionic wind machines, electric wind machines, corona wind pumps, electro-fluid-dynamics (EFD) devices, electrostatic fluid accelerators (EFAs), electrohydrodynamic (EHD) thrusters and EHD gas pumps. Some aspects of the technology have also been exploited in devices referred to as electrostatic air cleaners or electrostatic precipitators. In general, EHD technology uses ion flow principles to move fluids (e.g., air molecules). Basic principles of EHD fluid flow are reasonably well understood by persons of skill in the art. Accordingly, a brief illustration of ion flow using corona discharge principles in a simple two-electrode system sets the stage for the more detailed description that follows.
With reference to the illustration in
Notwithstanding the descriptive focus on corona discharge type emitter electrode configurations, persons of ordinary skill in the art will appreciate that ions may be generated by other techniques such as silent discharge, AC discharge, dielectric barrier discharge (DBD), or the like, and once generated, may, in turn, be accelerated in the presence of electrical fields to motivate fluid flow as described herein. For avoidance of doubt, emitter electrodes need not be of a corona discharge type in all embodiments. Also for avoidance of doubt, power supply voltage magnitudes, polarities and waveforms (if any) described or illustrated with respect to particular embodiments are purely illustrative and may differ for other embodiments.
In general, practical EHD air mover implementations may include electrode geometries, channel designs and field shaping features, EMI shielding and/or duct work and heat transfer surfaces that have been adapted for a given application or deployment.
Accordingly, in view of the foregoing, and without limitation, in the EHD air mover illustrated in
During operation of EHD devices (including exemplary devices such as illustrated and described herein), emitter and collector materials and structures are subject to degradation, whether by erosive or accretive electrochemical processes can involve interactions (in a corona discharge region closely proximate the surface of an emitter) of a plasma, chemical constituents of an ambient fluid, surface chemistry of the emitter electrodes, and catalysis. For example, in some cases and operating environments, EHD device performance reduction or failure can be caused by gradual coating of the emitter with silica, including dendritic growth thereon. In some cases and operating environments, EHD devices can produce undesireable concentrations of ozone.
In general, electrodes (including the aforementioned emitter and collector electrodes) may be susceptible to oxidation, corona erosion, or accumulation of detrimental materials. The term “corona erosion” refers to various adverse effects from a plasma discharge environment including enhanced oxidation, and etching or sputter, particularly (though not exclusively) of emitter surfaces. In general, corona erosion can result from any plasma or ion discharge including, silent discharge, AC discharge, dielectric barrier discharge or the like.
Detrimental material such as silica dendrites, surface contaminants, particulate or other debris may accumulate or form on electrode surfaces and may decrease the performance, efficiency and lifetime of such devices. In particular, siloxane vapor breaks down in a plasma or corona environment and forms solid deposits of silica on the electrodes, e.g., emitter or collector electrode. Other detrimental materials may build up on any number of electrode surfaces. Build-up of such detrimental materials can decrease power efficiency, cause sparking or reduce spark-over voltage and contribute to device failure. In some cases, build-up of such detrimental materials, including e.g., the resulting effects on magnitude of electric fields proximate dendritic growths and/or encapsulations of otherwise desirable material compositions of the electrode surface, may contribute to undesirable levels of ozone production.
Accordingly, structures and techniques have been developed for cleaning and otherwise conditioning (EHD) electrode surfaces. In particular, conditioning of emitter electrode surfaces with silver (Ag), silver compositions or silver preparations applied in situ at successive times throughout the operating lifetime of the EHD device has been found to significantly reduce ozone production, in some cases by 50% or more. In general, structures and techniques for in situ conditioning electrode surfaces, and in particular emitter electrode surfaces of an EHD device, with a conditioning material that includes silver will be understood by persons of ordinary skill in the art having benefit of the present disclosure.
In the illustrated cross-sectional view of
In situ Cleaning and/or Conditioning, Generally
The generalized descriptions of in situ cleaning and/or conditioning of electrode surfaces that follow will be understood relative to a variety of EHD device implementations in which such techniques may be employed. One class of such EHD device implementations includes EHD air movers such as illustrated and described above with reference to
In such devices, as well as others, an elongate wire-type emitter electrode may be employed. For generality (though without loss of applicability to the EHD air mover device structures described elsewhere herein), in situ cleaning and/or conditioning may be described relative to simply an “electrode” or “electrode surface.” Based on the description herein, persons of ordinary skill in the art will appreciate applications of the described structures and techniques to emitter-type electrode surfaces as well, in some cases, as collector-type electrode surfaces.
In some implementations of an EHD air mover, a cleaning or conditioning device (e.g., a wiper, pad, surface, edge or the like) may be held and/or moved against an electrode (or electrodes) with a suitable force or pressure to mechanically remove detrimental material while not abrading or otherwise damaging the electrode(s). In some cases, the electrode(s) is (are) moved past the wiper, pad, surface or edge. The wiper, pad, surface or edge may have a composition selected to be hard enough to remove the detrimental material under the selected pressure, and yet soft enough (relative to the electrode surface material) to not harm the electrode. A conditioning device (again a wiper, pad, surface, edge or the like) deposits a conditioning material on an electrode (or electrodes).
In some cases, cleaning and conditioning may each involve a distinct wiper, pad, surface or edge. In some cases, cleaning and conditioning may both be provided by a same wiper, pad, surface or edge. For example, a wiper, pad, surface or edge used for removal of detrimental material may also include a wearable bulk of conditioning material to leave a low adhesion or non stick layer on the electrode surface during the conditioning process. In some cases, the conditioning material composition may be selected to form a partially conductive layer on the electrode. In some cases, the conditioning material may be selected to at least partially mitigate erosion, corrosion, dendrite formation, oxidation and ozone.
The applied conditioning material layer may be conformal to the electrode surface or may partially coat the surface and smooth the surface. The layer may provide electrode erosion control, reduce the detrimental material and dendrite formation rate, and reduce sharp points that may cause electrode arcing. The layer may be formed of a carbon containing compound selected to inhibit contamination buildup and facilitate the removal of contamination buildup due to the generally low adhesion of carbon surfaces. The layer may include silver, silver oxide, an alloy of silver or an organometallic silver compound as an ozone catalyst or reducing material.
In various implementations, cleaning and/or conditioning may be done with a brush, rotating brush, compliant or conformal surface, or an edge such as a squeegee or wiper blade, or with a material having sufficient softness to not abrade, scratch or damage the surface of the electrode.
In some implementations, carbon may be applied during cleaning by using a wearable carbon wiper blade, thus removing detrimental materials at the same time as forming or renewing a conditioning coating. The lubricating effect of the soft carbon material (for example graphite) may also further reduce damage to the electrode during wiping and during operation under ion bombardment, e.g., in a plasma environment such as found in corona devices.
The cleaning and/or conditioning device or wiper may be formed of two or more blocks that are urged against at least part of the electrode surface. For example, in some cases, the electrode is a wire and the blocks may include graphite and/or silver inserts or layers. The blocks may be pressed towards each other on opposite sides of the wire, and the motion of the wire electrode against the blocks may wear the graphite to form a partial layer of carbon on parts of the wire. Conditioning material including silver may be likewise applied or deposited on an wire-type emitter electrode.
In a particular case, the wire may be substantially wiped and conditioned by rotating or spiraling the graphite and/or silver conditioning material bearing blocks around the circumference of the wire while travelling along the length of the wire. As wiping operations occur at selected intervals, a groove may be worn into the wearable conditioning material on the blocks, such that the blocks may eventually contact each other around the wire. The wearable conditioning portion or the entire cleaning blocks may be replaced as needed. Alternatively, in some implementations, the cleaning blocks may be compliant such that an applied pressure on the blocks causes the block to deform around the wire. Wear tolerant profiles may be provided as described in commonly-owned, co-pending U.S. patent application Ser. No. 12/828,079, filed Jun. 30, 2010, entitled “EMITTER WIRE CLEANING DEVICE WITH WEAR-TOLERANT PROFILE” (now published as US 2012/0000486).
With reference to
The cleaning device comprising portions 104/106 may be moved in contact with the electrode 102 in a linear motion 108, or a rotating motion 110, or a combination of motions, either simultaneously or sequentially. For example, cleaning blocks 104/106 may be translated or otherwise driven by a carriage moveable along a length of electrode 102, such as described elsewhere herein with reference to
Alternatively, electrode 102 may be transited past cleaning blocks 104/106. Thus, detrimental material removal and/or electrode conditioning (collectively “cleaning/conditioning”) may be accomplished by movement of either of the electrode 102 or cleaning blocks 104/106 with respect to the other. For example, electrode 102 may be an endless loop trained about a drive pulley. Alternatively, in some cases, worn or contaminated electrode may be periodically renewed by new wire lengths drawn from a supply spool and the used lengths collected on a take-up spool. In some cases, new electrode lengths may be provided by other feed mechanisms or may simply be manually replaced. A new electrode may be provided after a fixed number of cleaning cycles, after a predetermined period of use or upon detection of deterioration of performance. Thus, an actuator may be used to move at least one of the electrode and the cleaning blocks.
In some implementations, the cleaning/conditioning is performed when the electrode is not in use. Alternatively, the cleaning action may be performed continuously or at timed intervals. In some cases, conditioning or cleaning may be initiated by a controller based upon one or more of an imposed voltage level, a measured electrical potential, determination of the presence of a level of contamination by optical means, by detection of an event or performance parameter, or other methods indicating a benefit from mechanically cleaning and/or conditioning the electrode 102.
It may be seen that block 204 need not contact block 206 in the illustration. In the case of the blocks 204 and 206 being formed of a wearable or relatively soft material such as graphite, the operation of the cleaning device 200 under the pressure resulting from applied force F may result in the removal of some of the block material in the area adjacent to the electrode 202, resulting in a groove forming or deepening in the two blocks as shown. For example, cleaning blocks 204 and 206 may be separated by a spacing 212 that is reduced over time, with the blocks eventually contacting each other.
Thus, the efficacy of removal of detrimental material from or deposition of conditioning material on the surface of the electrode 202 may diminish over time. At this point the user may replace one or both of blocks 204 and 206, or any portion thereof, e.g., a wearable conditioning material insert or pad. Alternatively, block life may be prolonged, in some cases, using a compliant block material such that the applied pressure on the block causes the block to deform around the electrode.
It may be noted that moving the blocks 204 and 206 in the linear fashion shown in
The coating 304 may be formed of multiple conditioning materials or of multiple conditioning material layers by use of multiple wiper blades, cleaning blocks and/or multiple conditioning material surfaces. In a particular case, multiple cavities or channels defined in a cleaning block retain conditioning materials for deposition on the electrode. The material of the coating may be a uniform material, multiple layers of different materials, a material formed by the combination of two different materials wiped onto the electrode 302, or a material formed by chemical action or by plasma action.
In some cases, the conditioning material sublimates from a solid phase to a vapor phase in response to heating of the conditioning material. In some implementations, the conditioning material is applied by wicking onto the electrode, for example, using capillary channels formed in a cleaning block. Alternatively, the electrode itself may wick the conditioning material from a reservoir or other source along a portion of the electrode and the cleaning blocks may further spread the conditioning material along the electrode. Such wicking and spreading may be aided by heating the electrode.
The conditioning material layer 304 provides a sacrificial layer or protective coating. The coating need not be continuous over the entirety of the operating surface of the electrode 302. In some cases, the coating may provide low adhesion or a “non stick” surface, or it may have a surface property that repels silica, which is a common material in dendrite formation. As an illustrative example, the conditioning material layer 304 may include carbon such as graphite, and may reduce adhesion of dendrites and other detrimental materials, and may reduce their formation rate as well as improve the ease of mechanically removing any contamination. Conditioning material layer 304 may serve as a sacrificial layer that is oxidized or eroded by a plasma environment. Replenishment of this sacrificial layer provides erosion protection for the underlying electrode metal, such as tungsten, or another electrode protective coating that may otherwise be eroded or thinned.
For clarity and descriptive focus, electrode 302 is presented herein primarily as an exposed electrode surface without particular regard to internal structure or metallurgy. It will be appreciated by persons of ordinary skill in the art having benefit of the present description that engineered emitter electrode structures may provide desirable levels of surface hardness, robustness to erosion and electrochemical effects in the corona, tensile strength and elastic deformability, etc. In this regard, commonly-owned co-pending U.S. patent application Ser. No. 13/302,811, filed Nov. 22, 2011, entitled “EMITTER WIRE WITH LAYERED CROSS-SECTION” and naming Gao, Jewell-Larsen and Humpston as inventors illustrates describes and further details particular emitter wire structures and metallurgy suitable for some EHD air mover embodiments. Application Ser. No. 13/105,343 is incorporated herein by reference for the limited purpose of its further description of emitter wire structures and metallurgy, which may optionally be employed in embodiments in accordance with the present invention(s).
In some implementations, the material of the layer 304 may be selected to have an ozone reduction function, e.g., to reduce ozone generated by the device. As an illustrative example, a material that includes silver (Ag) may be used to reduce ozone in an air flow. Silver may also be used to prevent silica growth.
Reapplication of the layer 304 during wiping operations may be controlled via the applied pressure and composition of the wiping surface to form a coating with a thickness approximately equal to an erosion thickness. Thus, the conditioning material layer 304 may be repeatedly eroded and reformed on the surface of electrode 302.
The cleaning device 404 may have any shape and is not limited to the cylindrical shape shown. The cleaning device 404 may be removed from the surface, placed and urged against the surface of electrode 402 by a pressure device 408. The cleaning device 404 may be movable in any combination of motions 412 and 414 to cover any selected portion of the electrode 402. Various combinations of motions 412 and 414 may be linear, reciprocating, circular or elliptical. The shape of the electrode 402 is shown as planar (and is generally consistent with planar collector electrodes such as illustrated and described above with reference to
With reference to
With reference to
In some instances, elastic deformation of the electrode can increase cleaning or conditioning efficacy or control. For example, a degree of deformation of the electrode or a degree of friction at certain points of contact may be controlled to vary cleaning and conditioning parameters. Tension in the electrode or pressure or spacing between cleaning blocks 504/506 may be variable in some cases. For example, cleaning blocks 504/506 may initially be spaced a distance apart and may then gradually move closer together and contact as the blocks wear from extended cleaning and conditioning cycles.
Cleaning blocks 504/506 may be formed of a wearable material including a conditioning material composed to reduce adhesion, reduce ozone, mitigate oxidation or otherwise mitigate adverse effects of ion bombardment or a plasma environment. In a particular implementation, blocks 504/506 are formed of a substantially sold, wearable graphite conditioning material. In some implementations, the wearable conditioning material is substantially softer than the electrode plating to avoid plating damage during cleaning/conditioning. In some cases, conditioning material compositions can include silver, platinum, manganese, palladium, nickel, or oxides or alloys of the same. In some cases, the condition composition includes carbon, organometallic materials that decompose under plasma conditions, and combinations thereof.
In some implementations, blocks 504/506 are formed of different materials or include different conditioning materials. For example, one block may bear a felt cleaning material while the other block includes a wearable graphite conditioning material. In some implementations, cleaning blocks 504/506 both include harder carbon wiping and conditioning materials. In some implementations, at least one of cleaning blocks 504/506 includes a softer wiper material, e.g., a felt pad or mohair.
Cleaning blocks 504/506 are depicted as defining apertures 510 for receiving fasteners to install blocks 504/506. Blocks 504/506 may be positionally fixed within a device and the electrode transited therebetween, e.g., as an endless electrode loop trained about a drive pulley. Alternatively, blocks 504/506 may be attached, e.g., as a fixture, to a movable carriage (see e.g.,
With reference to
With reference to
With reference to
Alternatively, a substantially liquid or flowable conditioning material may be dispensed to channels formed in one or both of surfaces 710 and 712 during conditioning operations. In some cases, heat can be used to render a conditioning material flowable or to alter the composition of the conditioning material before or after application to electrode 708.
In some implementations, a cleaning block can bear different materials for coating the electrode. In some implementations, the cleaning blocks define multiple channels for conveying materials to be applied to the electrode. For example, a first cleaning block channel or area can include a binder and a second channel or area can include graphite. In some cases, a binder and/or carbon bearing liquid may be injected into adjacent channels to thereby be sequentially deposited on an electrode passing by a portion of the channel as the cleaning block travels along the electrode or as the electrode is transited past the cleaning block. Accordingly, in some cases, a conditioning material may be replenished without the need to replace a cleaning block or a conditioning portion of the cleaning block.
In some cases, the binder and/or graphite may be in the form of inserts or pads disposed on the cleaning block. In some cases, the binder and/or graphite may be in the form of coatings applied to different areas of the cleaning block. In a particular case, the binder is oxidized leaving a residual conditioning material, e.g., a paraffin binder leaves a graphite residue or a solvent evaporates to leave a silver or manganese residue. In some cases, different coating materials may be positioned on a cleaning block to be sequentially applied to the electrode during single or multiple cleaning block cleaning movements.
Pressure can be provided between blocks 704/706 by a foam block 714 or spring disposed between at least one of the cleaning blocks 704/706 and a corresponding support structure, e.g., carriage arm 716. Cleaning blocks 704/706 and foam block 714 are arranged to provide pressure between cleaning blocks sufficient to frictionally clean electrode 708, which can also be deflected thereby for cleaning or conditioning.
With reference to
Conditioning material inserts 810 may be removable and replaceable as needed, or may be integral with and replaceable with cleaning blocks 804/806 as needed. Conditioning material inserts 810 can include similar or different conditioning material compositions. For example, one conditioning material composition can provide an electrode shielding composition to protect against oxidation, and another conditioning material composition can include an ozone reducer. In some implementations, conditioning material compositions include a low adhesion or silicon-phobic material. In some implementations, conditioning material compositions include an organic material. In some cases, the organic material is carbon. In some cases, a conditioning material forms a sacrificial layer that inhibits dendrite formation or adhesion of detrimental materials.
With reference to
In some implementations, the cleaning blocks can include multiple cleaning or conditioning regions or surfaces. In some cases, the cleaning blocks each include at least a first region for removing dendrites from the electrode through scraping or frictional cleaning, and at least a second region for depositing a conditioning material coating on the electrode. In some cases, the cleaning and conditioning are simultaneously performed by movement of the cleaning device. The cleaning blocks may include any combination of surface profiles, including flat, curved, grooved, undulating, and the like to provide a desired degree of frictional contact and/or electrode deflection during cleaning.
Similarly, the electrode may be formed as a block, strip, or other form and the cleaning block can be constructed to contact any desired portion of the electrode. In some cases, the cleaning block may generally conform to the electrode to provide detrimental material removal across all or a major portion of the electrode. For example, the cleaning block can be constructed as a ring or cylinder enclosing an elongated electrode wire. Alternatively, the cleaning block may be positioned to clean adjacent or overlapping regions of the electrode with sequential cleaning passes. In some cases, the electrode is cleaned periodically with a single pass of the cleaning blocks. In some cases, the electrode is cleaned periodically with an initial pass and a return pass in a given conditioning cycle.
Although not specifically shown in the drawings, it will be appreciated by persons of ordinary skill in the art having benefit of the present description that granular abrasives, including granular abrasives with silver as a conditioning material constituent, may be provided. Commonly-owned co-pending U.S. application Ser. No. 12/819,966, filed Jun. 21, 2010, entitled “GRANULAR ABRASIVE CLEANING OF AN EMITTER WIRE” and naming Gao, Jewell-Larsen and Tseng as inventors illustrates, describes and further details suitable materials and structures for such granular abrasives. Application Ser. No. 12/819,966 is incorporated herein by reference for the limited purpose of its further description of materials and structures for such granular abrasives, which may optionally be employed in embodiments in accordance with the present invention(s).
Illustrative Cleaning and/or Conditioning Carriage Designs
With reference to
In a particular case, an electrode wire is placed in tension, e.g., 20 g, and is cleaned using grooved carbon cleaning blocks (like those shown in
Carriage 1001 can carry multiple cleaning block pairs positioned to clean multiple electrodes. Device 1000 can further include grounding electrodes, repelling electrodes, backflow electrodes or other electrodes arranged to motivate air through the device to exhaust heat delivered, e.g., from a heat sink via a heat pipe. Carriage 1001 may be fitted with additional cleaning mechanisms to be transited past any number of electrodes, filters, or other system features prone to accumulation of detrimental material or in need of mechanical conditioning.
With continued reference to
In this particular implementation, brush 1026 is positioned along an end portion of the path of travel of carriage 1001 such that advancement of carriage 1001 against brush 1026 causes brush 1026 to deflect and to thereby wipe across the affected area of the blocks and/or carriage 1001. In some implementations, other mechanisms may be used to dislodge detrimental material that accumulates on the cleaning device surfaces or carriage surfaces during electrode cleaning or conditioning operations. Brush 1026 may be positioned outside of an airflow path.
The detrimental material dislodged by brush 1026 can be accumulated in a receptacle area 1028, which can be positioned adjacent where the carriage is stowed between cleaning cycles. Passages (not shown) in the receptacle area 1028 can be provided to allow escape of the dislodged detrimental material from the system, for example, upon tipping of the system during transport. In some cases, the receptacle area 1028 may include a removable bin. Still in some implementations, passages are provided below the electrode wire such that dislodged detrimental material simply falls out of the electronic device, e.g., as a fine powder through vents in a lower surface.
While the foregoing description emphasizes structures (carriage and transit/drive mechanisms) and techniques for cleaning and/or conditioning an elongate electrode (e.g., a wire-type emitter wire such as illustrated in
Commonly owned, co-pending U.S. application Ser. No. 12/820,009, filed Jun. 21, 2010, entitled “CLEANING MECHANISM WITH TANDEM MOVEMENT OVER EMITTER AND COLLECTOR SURFACES” and naming Jewell-Larsen, Honer and Schwiebert as inventors, which is incorporated by reference herein, includes additional description relative to such tandem embodiments. Nonetheless to summarize regarding conditioning materials, cleaning blocks may be formed of a substantially sold, wearable graphite conditioning material. In some implementations, the wearable conditioning material is substantially softer than the electrode plating to avoid plating damage during cleaning/conditioning. In some cases, conditioning material compositions can include carbon, silver, platinum, magnesium, manganese, palladium, nickel, or oxides or alloys of the same. In some cases, the condition material composition includes carbon, organometallic materials that decompose under plasma conditions or ion bombardment, and combinations thereof. In some implementations, the conditioning material may be selected to have an ozone reduction function, e.g., to reduce the amount of ozone generated by the device. As an illustrative example, a material that includes silver (Ag) may be used to reduce ozone production and may also be used to prevent silica growth.
Turning to structural and operational aspects of exemplary tandem embodiments,
Emitter electrode 1008 and collector electrode 1006 are positioned relative to one another and energizable to generate ions to motivate fluid flow along a fluid flow path. Thus, emitter electrode 1008 and collector electrode 1006 may at least partially define an electrohydrodynamic fluid accelerator. Any number of additional electrodes may be positioned upstream and downstream of the electrohydrodynamic fluid accelerator along the fluid flow path. Additional cleaning surfaces can be provided to frictionally engage and travel over surfaces of the additional electrodes in tandem with travel of cleaning surfaces 1002 along a longitudinal extent of emitter electrode 1008. In some implementations, a collector electrode (or an additional collector electrode) can be disposed upstream of the electrohydrodynamic fluid accelerator along the fluid flow path (or laterally adjacent thereto) and can operate as an electrostatic precipitator.
While electrodes 1008 and 1006 are generally depicted as elongated or wire-type emitter and collector electrodes, any combination of electrode types and electrode surfaces may be cleaned in tandem via cleaning surfaces 1002 and 1004 via movement of cleaning mechanism 1001.
For example, a first respective cleaning surface 1002 may travel along a longitudinal extent of emitter electrode 1008 and a second respective cleaning surface, e.g., cleaning surface 1004, travels in tandem over a major dimension of a surface of collector electrode 1006 or another electrode. For example, an ESP or EHD device can include grounding electrodes, repelling electrodes, backflow electrodes or other electrodes arranged to motivate air through the device to exhaust heat delivered, e.g., from a heat sink via a heat pipe.
In the illustrated implementation, cleaning mechanism 1001 includes multiple cleaning surface pairs 1002 and 1004 positioned to clean opposite surfaces of respective electrodes 1008 and 1006. Cleaning surfaces 1002, 1004 can be contoured to clean all or part of a respective electrode. For example, cleaning surfaces 1002 can provide substantially complete circumferential contact with emitter electrode 1008 via grooves formed in cleaning surfaces 1002. Cleaning and/or conditioning aspects of cleaning surfaces 1002 will be understood based on the description herein of like surfaces and materials (recall e.g., the foregoing description of in situ cleaning/conditioning and
Referring again to
Cleaning mechanism 1001 can be driven or translated via a drive cable 1010 trained about a drive pulley 1012 and idler pulley 1014, with drive pulley 1012 being rotatable by a drive motor 1016. Other types of drive mechanisms may be used to move cleaning mechanism 1001 to thereby clean and/or condition an electrode.
Alternatively, in some implementations, electrodes may be driven in tandem past respective cleaning surfaces. Referring illustratively to features illustrated in
Cleaning mechanism 1001 may be movable in single passes such that cleaning mechanism 1001 moves between alternate ends of electrodes 1008 and 1006 in each cycle. Alternatively, cleaning mechanism 1001 may reciprocate or move bidirectionally in a single cycle or it in may perform any number of movements at any desired speed in a given cycle. In some implementations, cleaning operations may be repeated, extended, or tailored to achieve a desired degree of cleaning as determined by testing performance characteristics between cleaning cycles. For example, after a first cleaning cycle, an emitter electrode can be energized and various performance characteristics measured, e.g., voltage, current, sparking, and the like. Additional cleaning cycles may then be initiated as needed and additional performance checks conducted to determine sufficiency of electrode cleaning.
With continued reference to
In some implementations, electrodes 1008 and/or 1006 are elongated wire electrodes that are placed in tension and the cleaning mechanism 1001 defines respective cleaning surfaces 1002 and 1004 contoured or otherwise shaped to contact a desired portion of electrodes 1008 and 1006. For example, in some cases, cleaning surfaces substantially conform to a profile or shape of a surface of a respective electrode 1008 or 1006. Thus, a grooved cleaning surface may receive an elongated electrode to travel along a longitudinal extent or surface thereof. Similarly, a substantially planar cleaning surface may be transited over a substantially planar major portion of a respective electrode. In some cases, the electrode is substantially rigid and the cleaning surface conforms to the electrode. In other cases, the electrode may conform somewhat to the cleaning surface, for example, in the case of a wire electrode and a contoured cleaning surface.
In some implementations, the respective opposed cleaning surfaces are urged against one another or against the respective electrode by an applied force. In a particular case, elongated electrode wires are positioned in spaced relation, e.g., 1-5 mm and energizable to establish a corona discharge therebetween. The electrodes are placed in tension, e.g., 10-30 g, and are cleaned using grooved carbon cleaning surfaces, with a 40-80 g preload between the cleaning surfaces and the respective electrode. The carbon bearing cleaning surfaces are transited in tandem along the respective electrodes at about 13 mm/s in both an initial pass and a return pass. The carbon present on the cleaning surfaces preferably has a hardness selected to effectively remove detrimental material from the electrode while not abrading the electrode material or electrode surface coating. In some cases, the carbon is sufficiently soft to wear and deposit a carbon coating on the electrode. Carbon is but one example of a conditioning material that may be present on cleaning surfaces 1002 and 1004. Other conditioning materials may be used, e.g., to provide ozone reducing coatings, sacrificial coatings, electrode surface refinishing, electrode lubrication, or other useful conditioning of electrodes. In some cases, the conditioning material includes silver.
Sufficient dendrites can form on the electrode wire to potentially affect the performance of the electrode in a relatively short period of operation, 2-4 hours under extreme conditions. Accordingly, cleaning may be advantageously initiated as a function of time, detection of dendrite growth, or in response to various events, e.g., power cycles or electrode arcing.
With reference to
In some implementations, electrodes 1206 can serve as a guide for movement and alignment of cleaning mechanism 1200. In some cases, cleaning mechanism 1200 can be slidingly retained on electrodes 1206. For example, cleaning mechanism 1200 can extend between electrodes 1206 from the rear to the front of electrodes 1206 with cleaning surfaces 1204 retained thereby adjacent respective surfaces of electrodes 1206. Cleaning surfaces 1202 are shown positioned on either side of emitter electrode 1208 in a vertical orientation.
With continued reference to
With particular reference to
The projections can be in the form of wearable blades that are spaced apart and offset from one or more opposed blades to produce a desired deformation of emitter electrode 1008. The blades further serve to wipe undesirable material from the emitter electrode 1008 and to deposit the conditioning material(s), typically including silver. In some implementations such as that illustrated, the blades are formed as legs of a generally C-shaped or U-shaped conditioning structure. With reference to
With reference to
Device 1120 is powered by high voltage power supply 1130 and is positioned proximate to heat sink 1142. Electronic device 1100 may also comprise many other circuits, depending on its intended use; to simplify illustration of this second implementation, other components that may occupy interior area 1122 of housing 1120 have been omitted from
With continued reference to
A controller 1132 is connected to device 1120 and may use sensor inputs to determine the state of the air cooling system, e.g., to determine a need for cleaning electrodes. Alternatively, the cleaning may be initiated by controller 1132 on a timed or scheduled basis, on a system efficiency measurement basis or by other suitable methods of determining when to clean electrodes. For example, detection of electrode arcing or other electrode performance characteristics may be used to initiate movement of the cleaning mechanism to condition the electrode.
In some implementations, the cleaning or other conditioning is performed when the electrode is not in use. Alternatively, cleaning operations may be performed at timed intervals. In some cases, conditioning or cleaning may be initiated by controller 1132 based upon one or more of an imposed voltage level, a measured electrical potential, determination of the presence of a level of contamination by optical means, be detection of an event or performance parameter, or other methods indicating a benefit from mechanically cleaning the electrode.
Thus, the electrode(s) to be cleaned or conditioned can constitute at least a portion of a thermal management assembly thermally coupled to a heat dissipating device in an electronic device. At least one of the electrode and the cleaning device is moveable in response to detection of one of a low thermal duty cycle, power on cycle and a power off cycle of the electronic device. For example, a low CPU usage cycle may be an appropriate time to de-energize an electrode for cleaning/conditioning.
While the foregoing is illustrative of a particular computer-type electronic device, it will be appreciated that EHD devices, including EHD air mover devices such as described herein with cleaning and/or conditioning mechanisms for in situ conditioning of emitter electrode surfaces with a conditioning material that includes silver (Ag), have broad applicability to varied devices such as a laptop, notebook, netbook, pad or tablet-type computing device, a projector, a copy machine, a fax machine, a printer, a radio, an audio or video recording device, an audio or video playback device, a communications device, a charging device, a power inverter, a light source, a medical device, a home appliance, a power tool, a toy, a game console, a set-top console, a television, a video display device, etc. Nothing in
Some implementations of thermal management systems described herein employ EFA or EHD devices to motivate flow of a fluid, typically air, based on acceleration of ions generated as a result of corona discharge. Other implementations may employ other ion generation techniques and will nonetheless be understood in the descriptive context provided herein. Using heat transfer surfaces that may or may not be monolithic or integrated with collector electrodes, heat dissipated by electronics (e.g., microprocessors, graphics units, etc.) and/or other components can be transferred to the fluid flow and exhausted. Typically, when a thermal management system is integrated into an operational environment heat transfer paths (often implemented as heat pipes or using other technologies) are provided to transfer heat from where it is dissipated (or generated) to a location (or locations) within the enclosure where air flow motivated by an EFA or EHD device (or devices) flows over heat transfer surfaces.
In some implementations, an EFA or EHD air cooling system or other ion motive or flow generating device employing an electrode cleaning system may be integrated in an operational system such as a laptop or desktop computer, a projector or video display device, etc., other implementations may take the form of subassemblies. Various features may be used with different ion motive or flow generating devices including EFA and EHD devices such as air movers, film separators, film treatment devices, air particulate cleaners, photocopy machines and cooling systems for electronic devices such as computers, laptops and handheld devices.
While the forgoing represents a description of various implementations or implementations of the invention, it is to be understood that the claims below recite the features of the present invention, and that other implementations, not specifically described hereinabove, fall within the scope of the present invention.
Some implementations of thermal management systems described herein employ EFA or EHD devices to motivate flow of a fluid, typically air, based on acceleration of ions generated as a result of corona discharge. Other implementations may employ other ion generation techniques and will nonetheless be understood in the descriptive context provided herein. Using heat transfer surfaces, heat dissipated by electronics (e.g., microprocessors, graphics units, etc.) and/or other electronic system components can be transferred to the fluid flow and exhausted. Heat transfer paths, e.g., heat pipes, are provided to transfer heat from a heat source within the internal plenum to a location(s) within the enclosure where air flow motivated by an EHD device(s) flows over heat transfer surfaces to dissipate the heat.
In some implementations, enclosure and/or duct surfaces along the flow path can be provided with an ozone reducing material. In some applications, an ozone catalytic or reactive material can be provided on surfaces exposed to the internal air plenum. Similarly, ozone resistive or tolerant coatings can be provided on surfaces exposed to the internal air plenum. Ozone reducing materials can include ozone catalysts, ozone binders, ozone reactants or other materials suitable to react with, bind to, or otherwise reduce or sequester ozone. In some implementations, the ozone reducing material is a catalyst selected from a group that includes: manganese (Mn); manganese dioxide (MnO2); gold (Au); silver (Ag); silver oxide (Ag2O); and an oxide of nickel (Ni); and an oxide of manganese preparation. Ozone reducing material can be applied to internal enclosure surfaces and/or to the surface of electronic components within an enclosure. Ozone reducing material can additionally be applied to electronic system components. Similarly, surfaces of any number of the electronic components within an enclosure, and even internal enclosure surfaces can be provided with ozone tolerant, or ozone resistant coating to mitigate the effects of ozone.
In some implementations, an EFA or EHD air cooling system or other similar ion action device may be integrated into an operational system such as a laptop, tablet or desktop computer, a projector or video display device, etc., while other implementations may take the form of subassemblies. previously incorporated U.S. patent application Ser. No. 13/105,343, filed May 11, 2011, illustrates relative to certain thin (high-aspect ratio) laptop/notebook computer, tablet or pad-type computer and display device exploitations, EFA or EHD air cooling system deployments in which in situ emitter electrode conditioning techniques may be advantageously included. More generally features described herein may be used with different devices including EFA or EHD devices such as air movers, film separators, film treatment devices, air particulate cleaners, photocopy machines and cooling systems for electronic devices such as computers, laptops and handheld devices. One or more EHD cooled devices can include one of a computing device, projector, copy machine, fax machine, printer, radio, audio or video recording device, audio or video playback device, communications device, charging device, power inverter, light source, medical device, home appliance, power tool, toy, game console, set-top console, television, and video display device. Furthermore, in some cases, emitter-wire type ion source subassemblies used in devices that provide electrostatic printing or copying may be augmented to provide in situ emitter electrode conditioning such as described herein.
While the foregoing represents a description of various implementations of the invention, it is to be understood that the claims below recite the features of the present invention, and that other implementations, not specifically described hereinabove, fall within the scope of the present invention.
The present application claims benefit of U.S. Provisional Application Nos. 61/582,305, filed Dec. 31, 2011, 61/530,954, filed Sep. 3, 2011, and 61/652,812, filed May 29, 2012. The present application is also a continuation-in-part of U.S. application Ser. No. 12/771,967, filed Apr. 30, 2010, entitled “ELECTRODE CONDITIONING IN AN ELECTROHYDRODYNAMIC FLUID ACCELERATOR DEVICE” and naming Honer, Gao and Jewell-Larsen as inventors. The present application is also a continuation-in-part of U.S. application Ser. No. 12/820,009, filed Jun. 21, 2010, entitled “CLEANING MECHANISM WITH TANDEM MOVEMENT OVER EMITTER AND COLLECTOR SURFACES” and naming Jewell-Larsen, Honer and Schwiebert as inventors. The present application is also a continuation-in-part of U.S. application Ser. No. 12/819,966, filed Jun. 21, 2010, entitled “GRANULAR ABRASIVE CLEANING OF AN EMITTER WIRE” and naming Gao, Jewell-Larsen and Tseng as inventors. Each of the foregoing applications is incorporated herein by reference in its respective entirety.
Number | Name | Date | Kind |
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8405951 | Schwiebert et al. | Mar 2013 | B2 |
Number | Date | Country | |
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20130021715 A1 | Jan 2013 | US |
Number | Date | Country | |
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61652812 | May 2012 | US | |
61530954 | Sep 2011 | US | |
61582305 | Dec 2011 | US |
Number | Date | Country | |
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Parent | 12771967 | Apr 2010 | US |
Child | 13602256 | US | |
Parent | 12820009 | Jun 2010 | US |
Child | 12771967 | US | |
Parent | 12819966 | Jun 2010 | US |
Child | 12820009 | US |