An interconnected arrangement of photovoltaic cells is achieved using laminating current collector electrodes. The electrodes comprise a pattern of conductive material extending over a first surface of sheetlike substrate material. The first surface comprises material having adhesive affinity for a selected conductive surface. Application of the electrode to the selected conductive surface brings the first surface of the sheetlike substrate into adhesive contact with the conductive surface and simultaneously brings the conductive surface into firm contact with the conductive material extending over first surface of the sheetlike substrate. Use of the laminating current collector electrodes allows facile and continuous production of expansive area interconnected photovoltaic arrays.

Photovoltaic cells have developed according to two distinct methods. The initial operational cells employed a matrix of single crystal silicon appropriately doped to produce a planar p-n junction. An intrinsic electric field established at the p-n junction produces a voltage by directing solar photon produced holes and free electrons in opposite directions. Despite good conversion efficiencies and long-term reliability, widespread energy collection using single-crystal silicon cells is thwarted by the high cost of single crystal silicon material and interconnection processing.
A second approach to produce photovoltaic cells is by depositing thin photovoltaic semiconductor films on a supporting substrate. Material requirements are minimized and technologies can be proposed for mass production. Thin film photovoltaic cells employing amorphous silicon, cadmium telluride, copper indium gallium diselenide (CIGS), dye sensitized polymers and the like have received increasing attention in recent years. Despite significant improvements in individual cell conversion efficiencies for both single crystal and thin film approaches, photovoltaic energy collection has been generally restricted to applications having low power requirements. One factor impeding development of bulk power systems is the problem of economically collecting the energy from an extensive collection surface. Photovoltaic cells can be described as high current, low voltage devices. Typically individual cell voltage is less than about two volts, and often less than 0.6 volt. The current component is a substantial characteristic of the power generated. Efficient energy collection from an expansive surface must minimize resistive losses associated with the high current characteristic. A way to minimize resistive losses is to reduce the size of individual cells and connect them in series. Thus, voltage is stepped through each cell while current and associated resistive losses are minimized.
It is readily recognized that making effective, durable series connections among multiple small cells can be laborious, difficult and expensive. In order to approach economical mass production of series connected arrays of individual cells, a number of factors must be considered in addition to the type of photovoltaic materials chosen. These include the substrate employed and the process envisioned. Since thin films can be deposited over expansive areas, thin film technologies offer additional opportunities for mass production of interconnected arrays compared to inherently small, discrete single crystal silicon cells. Thus a number of U.S. patents have issued proposing designs and processes to achieve series interconnections among the thin film photovoltaic cells. Many of these technologies comprise deposition of photovoltaic thin films on glass substrates followed by scribing to form smaller area individual cells. Multiple steps then follow to electrically connect the individual cells in series array. Examples of these proposed processes are presented in U.S. Pat. Nos. 4,443,651, 4,724,011, and 4,769,086 to Swartz, Turner et al. and Tanner et al. respectively. While expanding the opportunities for mass production of interconnected cell arrays compared with single crystal silicon approaches, glass substrates must inherently be processed on an individual batch basis.
More recently, developers have explored depositing wide area films using continuous roll-to-roll processing. This technology generally involves depositing thin films of photovoltaic material onto a continuously moving web. However, a challenge still remains regarding subdividing the expansive films into individual cells followed by interconnecting into a series connected array. For example, U.S. Pat. No. 4,965,655 to Grimmer et. al. and U.S. Pat. No. 4,697,041 to Okamiwa teach processes requiring expensive laser scribing and interconnections achieved with laser heat staking. In addition, these two references teach a substrate of thin vacuum deposited metal on films of relatively expensive polymers. The electrical resistance of thin vacuum metallized layers significantly limits the active area of the individual interconnected cells.
Many of the legacy techniques used to interconnect individual photovoltaic cells into a modular format involve the use of low melting point metal solders and/or electrically conductive adhesives. These techniques are time consuming, expensive, and often require batch processing. Moreover, the electrical connections achieved with solder and/or electrically conductive adhesives have historically been susceptible to deterioration when exposed to environmental or mechanical stress.
It has become well known in the art that the efficiencies of certain promising thin film photovoltaic junctions can be substantially increased by high temperature treatments. These treatments involve temperatures at which even the most heat resistant plastics suffer rapid deterioration, thereby requiring either ceramic, glass, or metal substrates to support the thin film junctions. Use of a glass or ceramic substrates generally restricts one to batch processing and handling difficulty. Use of a metal foil as a substrate allows continuous roll-to-roll processing. However, despite the fact that use of a metal foil allows high temperature processing in roll-to-roll fashion, the subsequent interconnection of individual cells effectively in an interconnected array has proven difficult, in part because the metal foil substrate is electrically conducting.
U.S. Pat. No. 4,746,618 to Nath et al. teaches a design and process to achieve interconnected arrays using roll-to-roll processing of a metal web substrate such as stainless steel. The process includes multiple operations of cutting, selective deposition, and riveting. These operations add considerably to the final interconnected array cost.
U.S. Pat. No. 5,385,848 to Grimmer teaches roll-to-roll methods to achieve integrated series connections of adjacent thin film photovoltaic cells supported on an electrically conductive metal substrate. The process includes mechanical or chemical etch removal of a portion of the photovoltaic semiconductor and transparent top electrode to expose a portion of the electrically conductive metal substrate. The exposed metal serves as a contact area for interconnecting adjacent cells. These material removal techniques are troublesome for a number of reasons. First, many of the chemical elements involved in the best photovoltaic semiconductors are expensive and environmentally unfriendly. This removal subsequent to controlled deposition involves containment, dust and dirt collection and disposal, and possible cell contamination. This is not only wasteful but considerably adds to expense. Secondly, the removal processes are difficult to control dimensionally. Thus a significant amount of the valuable photovoltaic semiconductor is lost to the removal process. Ultimate module efficiencies are further compromised in that the spacing between adjacent cells grows, thereby reducing the effective active collector area for a given module area.
Thus there remains a need for manufacturing processes and articles which allow separate production of photovoltaic structures while also offering unique means to achieve effective integrated connections.
A further unsolved problem which has thwarted production of expansive surface photovoltaic modules is that of collecting the photogenerated current from the top, light incident surface. "Window electrodes" are commonly employed in the thin film cell stack. Transparent conductive oxide (TCO) layers are often employed for a top surface "window electrode". Other materials, such as intrinsically conductive polymers, conductive nanowires, etc. have also been proposed as alternatives for conductive metal oxides. Transparent conductive oxides are conductive materials based on certain metal oxides such as zinc, tin and indium. They are normally applied as thin layers to the top cell surface, with thicknesses normally less than 1 micrometer. In many cases, the TCO may scatter a portion of the transmitted radiation due to surface roughness and grain boundary effects. However, because of the thinness of the layer, this scattering is not detrimental and indeed is often helpful because of a "light trapping" effect.
Transparent conductive oxide (TCO) layers are relatively resistive compared to pure metals. Thus, efforts must be made to minimize resistive losses in transport of current through the TCO layer. One approach is simply to reduce the surface area of individual cells to a manageable amount. However, as cell widths decrease, the width of the area between individual cells (interconnect area) should also decrease so that the relative portion of inactive surface of the interconnect area does not become excessive. Typical cell widths of one centimeter are often taught in the art. These small cell widths demand very fine interconnect area widths, which dictate delicate and sensitive techniques to be used to electrically connect the top TCO surface of one cell to the bottom electrode of an adjacent series connected cell. Furthermore, achieving good stable ohmic contact to the TCO cell surface has proven difficult, especially when one employs those sensitive techniques available when using the TCO only as the top collector electrode. Another method is to form a current collector grid over the surface. This approach positions highly conductive material in contact with the surface of the TCO in a spaced arrangement such that the travel distance of current through the TCO is reduced. In the case of the classic single crystal silicon or polycrystalline silicon cells, a common approach is to form a collector grid pattern of traces using a silver containing paste and then fuse the paste to sinter the silver particles into continuous conductive silver paths. These highly conductive traces normally lead to a collection buss such as a copper foil strip. One notes that this approach involves use of expensive silver and requires the photovoltaic semiconductors tolerate the high fusion temperatures. Another approach is to attach an array of fine copper wires to a surface using conductive adhesive. The wires may also lead to a collection buss, or alternatively extend to an electrode of an adjacent cell. This wire approach normally involves positioning and fixing individual unsupported fine fragile wires over the surface. Typical of this "wire" approach is that taught in U.S. Pat. No. 5,457,057, to Nath et al. which is incorporated herein in its entirety. Another approach, used with "thin film" cells, is to print a collector grid array on the surface of a TCO using a conductive ink, usually one containing a heavy loading of fine particulate silver. The ink is simply dried or cured at mild temperatures which do not adversely affect the "thin film" cell. These approaches require the use of relatively expensive inks because of the high loading of finely divided silver. In addition, batch printing on the individual cells is laborious and expensive. Finally, conductive traces comprising particulate silver ink are relatively resistive compared to continuous metal traces.
In a somewhat removed segment of technology, a number of electrically conductive fillers have been used to produce electrically conductive polymeric materials. This technology generally involves mixing of conductive filler such as silver particles with the polymer resin prior to fabrication of the material into its final shape. Conductive fillers may have high aspect ratio structure such as metal fibers, metal flakes or powder, or highly structured carbon blacks, with the choice based on a number of cost/performance considerations. More recently, fine particles of intrinsically conductive polymers have been employed as conductive fillers within a resin binder. Electrically conductive polymers have been used as bulk thermoplastic compositions, or formulated into paints and inks. Their development has been spurred in large part by electromagnetic radiation shielding and static discharge requirements for plastic components used in the electronics industry. Other known applications include resistive heating fibers and battery components and production of conductive patterns and lines. The characterization "electrically conductive polymer" covers a very wide range of intrinsic resistivities depending on the filler, the filler loading and the methods of manufacture of the filler/polymer blend. Resistivities for filled electrically conductive polymers may be as low as 0.00001 ohm-cm. for very heavily filled silver inks, yet may be as high as 10,000 ohm-cm or even more for lightly filled carbon black materials or other "anti-static" materials. "Electrically conductive polymer" has become a broad industry term to characterize all such materials. In addition, it has been reported that recently developed intrinsically conducting polymers (absent conductive filler) may exhibit resistivities comparable to pure metals.
In yet another separate technological segment, coating plastic substrates with metal electrodeposits has been employed to achieve decorative effects on items such as knobs, cosmetic closures, faucets, and automotive trim. The normal conventional process actually combines two primary deposition technologies. The first is to deposit an adherent metal coating using chemical (electroless) deposition to first coat the nonconductive plastic and thereby render its surface highly conductive. This electroless step is then followed by conventional electroplating. ABS (acrylonitrile-butadiene-styrene) plastic dominates as the substrate of choice for most applications because of a blend of mechanical and process properties and ability to be uniformly etched. The overall plating process comprises many steps. First, the plastic substrate is chemically etched to microscopically roughen the surface. This is followed by depositing an initial metal layer by chemical reduction (typically referred to as "electroless plating"). This initial metal layer is normally copper or nickel of thickness typically one-half micrometer. The object is then electroplated with metals such as copper, bright nickel and chromium to achieve the desired thickness and decorative effects. The process is very sensitive to processing variables used to fabricate the plastic substrate, limiting applications to carefully prepared parts and designs. In addition, the many steps employing harsh chemicals make the process intrinsically costly and environmentally difficult. Finally, the sensitivity of ABS plastic to liquid hydrocarbons has prevented certain applications. ABS and other such polymers have been referred to as "electroplateable" polymers or resins. This is a misnomer in the strict sense, since ABS (and other nonconductive polymers) are incapable of accepting an electrodeposit directly and must be first metallized by other means before being finally coated with an electrodeposit. The conventional technology for electroplating on plastic (etching, chemical reduction, electroplating) has been extensively documented and discussed in the public and commercial literature. See, for example, Saubestre, Transactions of the Institute of Metal Finishing, 1969, Vol. 47., or Arcilesi et al., Products Finishing, March 1984.
Many attempts have been made to simplify the process of electroplating on plastic substrates. Some involve special chemical techniques to produce an electrically conductive film on the surface. Typical examples of this approach are taught by U.S. Pat. No. 3,523,875 to Minklei, U.S. Pat. No. 3,682,786 to Brown et. al., and U.S. Pat. No. 3,619,382 to Lupinski. The electrically conductive film produced was then electroplated. None of these attempts at simplification have achieved any recognizable commercial application.
A number of proposals have been made to make the plastic itself conductive enough to allow it to be electroplated directly thereby avoiding the "electroless plating" process. It is known that one way to produce electrically conductive polymers is to incorporate conductive or semiconductive fillers into a polymeric binder. Investigators have attempted to produce electrically conductive polymers capable of accepting an electrodeposited metal coating by loading polymers with relatively small conductive particulate fillers such as graphite, carbon black, and silver or nickel powder or flake. Heavy such loadings are sufficient to reduce volume resistivity to a level where electroplating may be considered. However, attempts to make an acceptable electroplateable polymer using the relatively small metal containing fillers alone encounter a number of barriers. First, the most conductive fine metal containing fillers such as silver are relatively expensive. The loadings required to achieve the particle-to-particle proximity to achieve acceptable conductivity increases the cost of the polymer/filler blend dramatically. The metal containing fillers are accompanied by further problems. They tend to cause deterioration of the mechanical properties and processing characteristics of many resins. This significantly limits options in resin selection. All polymer processing is best achieved by formulating resins with processing characteristics specifically tailored to the specific process (injection molding, extrusion, blow molding, printing etc.). A required heavy loading of metal filler severely restricts ability to manipulate processing properties in this way. A further problem is that metal fillers can be abrasive to processing machinery and may require specialized screws, barrels, and the like.
Another major obstacle involved in the electroplating of electrically conductive polymers is a consideration of adhesion between the electrodeposited metal and polymeric substrate (metal/polymer adhesion). In most cases sufficient adhesion is required to prevent metal/polymer separation during extended environmental and use cycles. Despite being electrically conductive, a simple metal-filled polymer offers no assured bonding mechanism to produce adhesion of an electrodeposit since the metal particles may be encapsulated by the resin binder, often resulting in a resin-rich "skin".
A number of methods to enhance electrodeposit adhesion to electrically conductive polymers have been proposed. For example, etching of the surface prior to plating can be considered. Etching can be achieved by immersion in vigorous solutions such as chromic/sulfuric acid. Alternatively, or in addition, an etchable species can be incorporated into the conductive polymeric compound. The etchable species at exposed surfaces is removed by immersion in an etchant prior to electroplating. Oxidizing surface treatments can also be considered to improve metal/plastic adhesion. These include processes such as flame or plasma treatments or immersion in oxidizing acids. In the case of conductive polymers containing finely divided metal, one can propose achieving direct metal-to-metal adhesion between electrodeposit and filler. However, here the metal particles are generally encapsulated by the resin binder, often resulting in a resin rich "skin". To overcome this effect, one could propose methods to remove the "skin", exposing active metal filler to bond to subsequently electrodeposited metal.
Another approach to impart adhesion between conductive resin substrates and electrodeposits is incorporation of an "adhesion promoter" at the surface of the electrically conductive resin substrate. This approach was taught by Chien et al. in U.S. Pat. No. 4,278,510 where maleic anhydride modified propylene polymers were taught as an adhesion promoter. Luch, in U.S. Pat. No. 3,865,699 taught that certain sulfur bearing chemicals could function to improve adhesion of initially electrodeposited Group VIII metals.
For the above reasons, electrically conductive polymers employing metal fillers have not been widely used as bulk substrates for electroplateable articles. Such metal containing polymers have found use as inks or pastes in production of printed circuitry. Revived efforts and advances have been made in the past few years to accomplish electroplating onto printed conductive patterns formed by silver filled inks and pastes.
An additional physical obstacle confronting practical electroplating onto electrically conductive polymers is the initial "bridge" of electrodeposit onto the surface of the electrically conductive polymer. In electrodeposition, the substrate to be plated is often made cathodic through a pressure contact to a metal rack tip, itself under cathodic potential. However, if the contact resistance is excessive or the substrate is insufficiently conductive, the electrodeposit current favors the rack tip to the point where the electrodeposit will not bridge to the substrate.
Moreover, a further problem is encountered even if specialized racking or cathodic contact successfully achieves electrodeposit bridging to the substrate. Many of the electrically conductive polymers have resistivities far higher than those of typical metal substrates. Also, many applications involve electroplating onto a thin (less than 25 micrometer) printed substrate. The conductive polymeric substrate may be relatively limited in the amount of electrodeposition current which it alone can convey. Thus, the conductive polymeric substrate does not cover almost instantly with electrodeposit as is typical with metallic substrates. Except for the most heavily loaded and highly conductive polymer substrates, a large portion of the electrodeposition current must pass back through the previously electrodeposited metal growing laterally over the surface of the conductive plastic substrate. In a fashion similar to the bridging problem discussed above, the electrodeposition current favors the electrodeposited metal and the lateral growth can be extremely slow and erratic. This restricts the size and "growth length" of the substrate conductive pattern, increases plating costs, and can also result in large non-uniformities in electrodeposit integrity and thickness over the pattern.
This lateral growth is dependent on the ability of the substrate to convey current. Thus, the thickness and resistivity of the conductive polymeric substrate can be defining factors in the ability to achieve satisfactory electrodeposit coverage rates. When dealing with selectively electroplated patterns long thin metal lines are often desired, deposited on a relatively thin electrically conductive polymer substrate. These factors of course often work against achieving the desired result.
This coverage rate problem likely can be characterized by a continuum, being dependent on many factors such as the nature of the initially electrodeposited metal, electroplating bath chemistry, the nature of the polymeric binder and the resistivity of the electrically conductive polymeric substrate. As a "rule of thumb", the instant inventor estimates that coverage rate issue would demand attention if the resistivity of the conductive polymeric substrate rose above about 0.001 ohm-cm. Alternatively, a "rule of thumb" appropriate for thin film substrates would be that attention is appropriate if the substrate film to be plated had a surface "sheet" resistance of greater than about 0.1 ohm per square.
The least expensive (and least conductive) of the readily available conductive fillers for plastics are carbon blacks. Attempts have been made to electroplate electrically conductive polymers using carbon black loadings. Examples of this approach are the teachings of U.S. Pat. Nos. 4,038,042, 3,865,699, and 4,278,510 to Adelman, Luch, and Chien et al. respectively.
Adelman taught incorporation of conductive carbon black into a polymeric matrix to achieve electrical conductivity required for electroplating. The substrate was pre-etched in chromic/sulfuric acid to achieve adhesion of the subsequently electroplated metal. A fundamental problem remaining unresolved by the Adelman teaching is the relatively high resistivity of carbon loaded polymers. The lowest "microscopic resistivity" generally achievable with carbon black loaded polymers is about 1 ohm-cm. Here "microscopic resistivity" refers to the resistivity of the polymer/carbon black matrix absent any additional additives. 1 ohm-cm. is about five to six orders of magnitude higher than typical electrodeposited metals such as copper or nickel. Thus, the electrodeposit bridging and coverage rate problems described above remained unresolved by the Adelman teachings.
Luch in U.S. Pat. No. 3,865,699 and Chien et al. in U.S. Pat. No. 4,278,510 also chose carbon black as a filler to provide an electrically conductive surface for the polymeric compounds to be electroplated. The Luch U.S. Pat. No. 3,865,699 and the Chien U.S. Pat. No. 4,278,510 are hereby incorporated in their entirety by this reference. However, these inventors further taught inclusion of materials to increase the rate of metal coverage or the rate of metal deposition on the polymer. These materials can be described herein as "electrodeposit growth rate accelerators" or "electrodeposit coverage rate accelerators". An electrodeposit coverage rate accelerator is a material functioning to increase the electrodeposition coverage rate over the surface of an electrically conductive polymer independent of any incidental affect it may have on the conductivity of an electrically conductive polymer. In the embodiments, examples and teachings of U.S. Pat. Nos. 3,865,699 and 4,278,510, it was shown that certain sulfur bearing materials, including elemental sulfur, can function as electrodeposit coverage or growth rate accelerators to overcome problems in achieving electrodeposit coverage of electrically conductive polymeric surfaces having relatively high resistivity or thin electrically conductive polymeric substrates having limited current carrying capacity.
In addition to elemental sulfur, sulfur in the form of sulfur donors such as sulfur chloride, 2-mercapto-benzothiazole, N-cyclohexyle-2-benzothiaozole sulfonomide, dibutyl xanthogen disulfide, and tetramethyl thiuram disulfide or combinations of these and sulfur were identified. Those skilled in the art will recognize that these sulfur donors are the materials which have been used or have been proposed for use as vulcanizing agents or accelerators. Since the polymer-based compositions taught by Luch and Chien et al. could be electroplated directly they could be accurately defined as directly electroplateable resins (DER). These directly electroplateable resins (DER) can be generally described as electrically conductive polymers with the inclusion of a growth rate accelerator.
Specifically for the present invention, specification, and claims, directly electroplateable resins, (DER), are characterized by the following features:                (a) presence of an electrically conductive polymer;        (b) presence of an electrodeposit coverage rate accelerator;        (c) presence of the electrically conductive polymer and the electrodeposit coverage rate accelerator in the directly electroplateable composition in cooperative amounts required to achieve direct coverage of the composition with an electrodeposited metal or metal-based alloy.
In his patents, Luch specifically identified unsaturated elastomers such as natural rubber, polychloroprene, butyl rubber, chlorinated butyl rubber, polybutadiene rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber etc. as suitable for the matrix polymer of a directly electroplateable resin. Other polymers identified by Luch as useful included polyvinyls, polyolefins, polystyrenes, polyamides, polyesters and polyurethanes.
When used alone, the minimum workable level of carbon black required to achieve "microscopic" electrical resistivities of less than 1000 ohm-cm. for a polymer/carbon black matrix mix appears to be about 8 weight percent based on the combined weight of polymer plus carbon black. The "microscopic" material resistivity generally is not reduced below about 1 ohm-cm. by using conductive carbon black alone. This is several orders of magnitude larger than typical metal resistivities.
It is understood that in addition to carbon blacks, other well known, highly conductive fillers can be considered in DER compositions. Examples include but are not limited to metallic fillers or flake such as silver. In these cases the more highly conductive fillers can be used to augment or even replace the conductive carbon black. Furthermore, one may consider using intrinsically conductive polymers to supply the required conductivity. In this case, it may not be necessary to add conductive fillers to the polymer.
The "bulk, macroscopic" resistivity of conductive carbon black filled polymers can be further reduced by augmenting the carbon black filler with additional highly conductive, high aspect ratio fillers such as metal containing fibers. Herein, "macroscopic resistivity refers to the resistivity of the entire material mix, including all additives whether they be conductive or non-conductive and regardless of size. This can be an important consideration in the success of certain applications. Furthermore, one should realize that incorporation of non-conductive fillers may increase the "bulk, macroscopic" resistivity of conductive polymers without significantly altering the "microscopic resistivity" of the conductive polymer "matrix" encapsulating the non-conductive filler particles.
Regarding electrodeposit coverage rate accelerators, both Luch and Chien et al. in the above discussed U.S. patents demonstrated that sulfur and other sulfur bearing materials such as sulfur donors and vulcanization accelerators function as electrodeposit coverage rate accelerators when using an initial Group VIII metal electrodeposit "strike" layer. Thus, an electrodeposit coverage rate accelerator need not be electrically conductive, but may be a material that is normally characterized as a non-conductor. The coverage rate accelerator need not appreciably affect the conductivity of the polymeric substrate. As an aid in understanding the function of an electrodeposit coverage rate accelerator the following is offered:                a. A specific conductive polymeric structure is identified as having insufficient current carrying capacity to be directly electroplated in a practical manner.        b. A material is added to the conductive polymeric material forming said structure. Said material addition may have insignificant affect on the current carrying capacity of the structure (i.e. it does not appreciably reduce resistivity or increase thickness).        c. Nevertheless, inclusion of said material greatly increases the speed at which an electrodeposited metal laterally covers the electrically conductive surface.It is contemplated that a coverage rate accelerator may be present as an additive, as a species absorbed on a filler surface, or even as a functional group attached to the polymer chain. One or more growth rate accelerators may be present in a directly electroplateable resin (DER) to achieve combined, often synergistic results.
A hypothetical example might be an extended line or trace of conductive ink having a dry thickness of 1 micrometer. Such inks typically include a conductive filler such as silver, nickel, copper, conductive carbon etc. The limited thickness of the ink reduces the current carrying capacity of this line thus preventing direct electroplating in a practical manner. However, inclusion of an appropriate quantity of a coverage rate accelerator may allow the conductive line to be directly electroplated in a practical manner.
One might expect that other Group 6A elements, such as oxygen, selenium and tellurium, could function in a way similar to sulfur. In addition, other combinations of electrodeposited metals, such as copper and appropriate coverage rate accelerators may be identified. It is important to recognize that such an electrodeposit coverage rate accelerator is important in order to achieve direct electrodeposition in a practical way onto polymeric substrates having low conductivity or very thin electrically conductive polymeric substrates having restricted current carrying ability.
It has also been found that the inclusion of an electrodeposit coverage rate accelerator promotes electrodeposit bridging from a discrete cathodic metal contact to a DER surface. This greatly reduces the bridging problems described above.
Due to multiple performance problems associated with their intended end use, none of the attempts identified above to directly electroplate electrically conductive polymers or plastics has ever achieved any recognizable commercial success. Nevertheless, the current inventor has persisted in personal efforts to overcome certain performance deficiencies associated with the initial DER technology. Along with these efforts has come a recognition of unique and eminently suitable applications employing the DER technology. Some examples of these unique applications for electroplated articles include solar cell electrical current collection grids, electrodes, electrical circuits, electrical traces, circuit boards, antennas, capacitors, induction heaters, connectors, switches, resistors, inductors, batteries, fuel cells, coils, signal lines, power lines, radiation reflectors, coolers, diodes, transistors, piezoelectric elements, photovoltaic cells, emi shields, biosensors and sensors. One readily recognizes that the demand for such functional applications for electroplated articles is relatively recent and has been particularly explosive during the past decade.
It is important to recognize a number of important characteristics of directly electroplateable resins (DERs) which facilitate the current invention. One such characteristic of the DER technology is its ability to employ polymer resins and formulations generally chosen in recognition of the fabrication process envisioned and the intended end use requirements. In order to provide clarity, examples of some such fabrication processes are presented immediately below in subparagraphs 1 through 10.                (1) Should it be desired to electroplate an ink, paint, coating, or paste which may be printed or formed on a substrate, a good film forming polymer, for example a soluble resin such as an elastomer, can be chosen to fabricate a DER ink (paint, coating, paste etc.). For example, in some embodiments thermoplastic elastomers having an olefin base, a urethane base, a block copolymer base or a random copolymer base may be appropriate. In some embodiments the coating may comprise a water based latex. Other embodiments may employ more rigid film forming polymers. The DER ink composition can be tailored for a specific process such flexographic printing, rotary silk screening, gravure printing, flow coating, spraying etc. Furthermore, additives can be employed to improve the adhesion of the DER ink to various substrates. One example would be tackifiers.        (2) Very thin DER lines often associated with collector grid structures can be printed and then electroplated due to the inclusion of the electrodeposit growth rate accelerator.        (3) Should it be desired to cure the DER substrate to a 3 dimensional matrix, an unsaturated elastomer or other "curable" resin may be chosen.        (4) DER inks can be formulated to form electrical lines on a variety of flexible substrates. For example, should it be desired to form electrical structure on a laminating film, a DER ink adherent to the sealing surface of the laminating film can be effectively electroplated with metal and subsequently laminated to a separate surface.        (5) Should it be desired to electroplate a fabric, a DER ink can be used to coat all or a portion of the fabric intended to be electroplated. Furthermore, since DER's can be fabricated out of the thermoplastic materials commonly used to create fabrics, the fabric itself could completely or partially comprise a DER. This would eliminate the need to coat the fabric.        (6) Should one desire to electroplate a thermoformed article or structure, DER's would represent an eminently suitable material choice. DER's can be easily formulated using olefinic materials which are often a preferred material for the thermoforming process. Furthermore, DER's can be easily and inexpensively extruded into the sheet like structure necessary for the thermoforming process.        (7) Should one desire to electroplate an extruded article or structure, for example a sheet or film, DER's can be formulated to possess the necessary melt strength advantageous for the extrusion process.        (8) Should one desire to injection mold an article or structure having thin walls, broad surface areas etc. a DER composition comprising a high flow polymer can be chosen.        (9) Should one desire to vary adhesion between an electrodeposited DER structure supported by a substrate the DER material can be formulated to supply the required adhesive characteristics to the substrate. For example, the polymer chosen to fabricate a DER ink can be chosen to cooperate with an "ink adhesion promoting" surface treatment such as a material primer or corona treatment. In this regard, it has been observed that it may be advantageous to limit such adhesion promoting treatments to a single side of the substrate. Treatment of both sides of the substrate in a roll to roll process may adversely affect the surface of the DER material and may lead to deterioration in plateability. For example, it has been observed that primers on both sides of a roll of PET film have adversely affected plateability of DER inks printed on the PET. It is believed that this is due to primer being transferred to the surface of the DER ink when the PET is rolled up.        (10) Should it be desirable to release a plated DER pattern from a supporting substrate, the DER may be formulated to readily release from the substrate material. In this case, the plated DER pattern may be transferred from its original supporting substrate to a receiving second substrate. The original supporting substrate functions as a surrogate support during formation and electroplating of the pattern and then is subsequently removed during transfer of the electroplated pattern to the second substrate.
All polymer fabrication processes require specific resin processing characteristics for success. The ability to "custom formulate" DER's to comply with these changing processing and end use requirements while still allowing facile, quality electroplating is a significant factor in the teachings of the current invention.
Another important recognition regarding the suitability of DER's for the teachings of the current invention is the simplicity of the electroplating process. Unlike many conventional electroplated plastics, DER's do not require a significant number of process steps prior to actual electroplating. This allows for simplified manufacturing and improved process control. It also reduces the risk of cross contamination such as solution dragout from one process bath being transported to another process bath. The simplified manufacturing process will also result in reduced manufacturing costs.
Another important recognition regarding the suitability of DER's for the teachings of the current invention is the wide variety of metals and alloys capable of being electrodeposited. Deposits may be chosen for specific attributes. Examples may include copper or silver for conductivity, nickel, chromium and gold for corrosion resistance, and tin and tin containing alloys for low temperature solderability or electrical contact improvement.
Yet another recognition of the benefit of DER's for the teachings of the current invention is the ability they offer to selectively electroplate an article or structure. The articles of the current invention often consist of selective metal patterns selectively positioned in conjunction with insulating materials. Such selective positioning of metals is often expensive and difficult. However, the attributes of the DER technology make the technology eminently suitable for the production of such selectively positioned metal structures. As will be shown in later embodiments, it is often desired to electroplate a polymer or polymer-based structure in a selective manner. DER's are eminently suitable for such selective electroplating.
Yet another recognition of the benefit of DER's for the teachings of the current invention is the ability they offer to continuously electroplate an article or structure. As will be shown in later embodiments, it is often desired to continuously electroplate articles. DER's are eminently suitable for such continuous electroplating. Furthermore, DER's allow for selective electroplating in a continuous manner.
Yet another recognition of the benefit of DER's for the teachings of the current invention is their ability to withstand the pre-treatments often required to prepare other materials for plating. For example, were a DER to be combined with a metal, the DER material would be resistant to many of the pre-treatments such as cleaning which may be necessary to electroplate the metal.
Yet another recognition of the benefit of DER's for the teachings of the current invention is that the desired plated structure often requires the plating of long and/or broad surface areas. As discussed previously, the coverage rate accelerators included in DER formulations allow for such extended surfaces to be covered in a relatively rapid manner thus allowing one to consider the use of electroplating of conductive polymers.
These and other attributes of DER's may contribute to successful articles and processing of the instant invention. However, it is emphasized that the DER technology is but one of a number of alternative metal deposition or positioning processes suitable to produce many of the embodiments of the instant invention. Other approaches, such as electroless metal deposition, electroplating onto silver ink patterns, positioning metal forms such as wire or mesh and many other additive or subtractive processes to selectively pattern conductive materials may be suitable alternatives. These choices will become clear in light of the teachings to follow in the remaining specification, accompanying figures and claims.
In order to eliminate ambiguity in terminology, for the present invention, specification and claims the following definitions are supplied.
While not precisely definable, electrically insulating materials may generally be characterized as having electrical resistivities greater than about 10,000 ohm-cm. Also, electrically conductive materials may generally be defined and characterized as materials having electrical resistivities less than 0.001 ohm-cm. Also electrically resistive or semi-conductive materials may generally be characterized as having electrical resistivities in the range of 0.001 ohm-cm to 10,000 ohm-cm., although such materials are also often characterized as simply "conductive". For example, certain metal oxides are characterized as "conductive" even though they may have resistivities greater than 0.001 ohm-cm. Also, the characterization "electrically conductive polymer" covers a very wide range of intrinsic resistivities depending on the application, the filler, the filler loading and the methods of manufacture of the filler/polymer blend. Resistivities for electrically conductive polymers may be as low as 0.00001 ohm-cm. for very heavily filled silver inks, yet may be as high as 10,000 ohm-cm or even more for lightly filled carbon black materials or other "anti-static" materials. "Electrically conductive polymer" has become a broad industry term to characterize all such materials. Thus, the term "electrically conductive polymer" as used in the art and in this specification and claims extends to materials of a very wide range of resitivities from about 0.00001 ohm-cm. to about 10,000 ohm-cm and higher.
"Substantially" means being largely or wholly that which is specified.
"Essentially" means fundamentally or "for all intents and purposes".
A "pattern" is a design or arrangement.
"Direct physical contact" means "touching".
A "low melting point" metal or alloy is one with a melting point less than 600 degrees Fahrenheit.
"Selectively positioned" means that which is specified is positioned in a preselected arrangement or design.
"Terminal edge" is a boundary outside of which there is none of that which is specified.
An "electroplateable material" is a material having suitable attributes that allow it to be coated with a layer of electrodeposited material, either directly or following a preplating process.
A "metallizable material" is a material suitable to be coated with a metal deposited by any one or more of the available metallizing processes, including but not limited to chemical deposition, vacuum metallizing, sputtering, metal spraying, sintering electroless deposition and electrodeposition.
"Metal-based" refers to a material or structure having at least one metallic property and comprising one or more components at least one of which is a metal or metal-containing alloy.
"Alloy" refers to a substance composed of two or more intimately mixed materials.
"Group VIII metal-based" refers to a substance containing by weight 50% to 100% metal from Group VIII of the Periodic Table of Elements.
A "metal-based foil", "bulk metal foil", "bulk metal wire" etc. refers to structure of metal or metal-based material that may maintain its integrity absent a supporting structure. Generally, metal films of thickness greater than about 2 micrometers may have this characteristic (i.e. 2 micrometers, 10 micrometers, 25 micrometers, 100 micrometers, 250 micrometers etc.). Thus, in most cases a "bulk metal foil" will have a thickness between about 2 micrometers and 250 micrometers and may comprise a structure of multiple layers. Metal wires of diameter greater than about 10 micrometers may exhibit self supporting characteristic and therefore be classified as a "bulk metal wire" wire form.
A "self supporting" structure is one that can be expected to maintain its integrity and form absent supporting structure.
"Portion" means a part of a whole item. When used herein, "portion" may indicate 100 percent or less of the whole item (i.e. 100 percent, 90 percent, 80 percent, 70 percent, 60 percent, 50 percent, 40 percent, 30 percent, 20 percent, 10 percent 5 percent, and 1 percent).
A "film" refers to a thin material form having length and width much greater than its thickness that may or may not be self supporting.
The terms "monolithic" or "monolithic structure" are used as is common in industry to describe structure that is made or formed from a single or uniform material. An example would be a "boat having a monolithic plastic hull".
A "continuous form" of material is one that has a length dimension far greater than its width or thickness such that the material can be supplied or produced in its length dimension without substantial interruption.
A "continuous process" is one wherein a continuous form of a material component is supplied to or produced by the process. The material feed or output can be as continuous motion or repetitively intermittent. The output product is normally removed either by continuous motion or repetitively intermittent according to the rate of input.
A "roll-to-roll" process is one wherein a material component is fed to the process from a roll of material and the output of the process is accumulated in a roll form.
The "machine direction" is that direction in which material is transported through a process step.
The term "multiple" is used herein to mean "two or more".
"Sheetlike" characterizes a structure or form having surface dimensions far greater than a thickness dimension. A "sheetlike" structure or form can comprise multiple layers and has a top side (defined by length and width) and an oppositely disposed bottom side.
A "web" is a sheetlike material form often characterized as continuous in a length direction.
An "adhesive" is a material that can bond to a surface or object.
A "laminating adhesive" is an adhesive material in the form of a layer or film. The adhesive will typically be activated using heat or pressure or a combination of both.
"Adhesive affinity" is a characteristic of a material's ability to adhesively bond to a mating surface. A material has "adhesive affinity" for a mating surface if it can form or has formed an adhesive bond directly to that surface using appropriate adhesive processing.
"Substantially planar" or "essentially planar characterize a surface structure which may comprise minor variations in surface topography but from an overall and functional perspective can be considered essentially flat.
The terms "upper", "upward facing", and "top" surfaces or sides of structure refer to those surfaces or sides of structures facing upward in normal use. For example, when used to describe a photovoltaic device, an "upper" surface or side refers to that surface or side intended to face the sun.
The terms "lower", "downward facing" or "bottom" surfaces or sides refer to surfaces or sides facing away from an upper, upward facing or top surface or side of the structure.
The term "polymer" refers to materials comprising repetitive structural units. Polymers are often commonly referred to as "plastics". Polymers comprise a broad class of materials having a wide variety of chemical, physical and mechanical properties. Most common polymers are carbon based (organic polymers) or silicon based (for example silicone materials). "Polymeric" refers to a material or structure comprising a polymer.
"Organic" materials are those based on or having a significant portion of their structure and characteristics defined by carbon. "Inorganic" materials are those substantially absent carbon.
The term "cross-linked" indicates a polymer condition wherein bonding occurs between polymer chains. Prior to "cross-linking", a polymer may be "flowable" under temperature and pressure. After "cross-linking" the polymer resists flow.
A "thermoplastic" material is one that becomes fluid and can flow at an elevated temperature. A thermoplastic material may be relatively rigid and non-tacky at room temperature and "melts" (becomes fluid) at elevated temperature above ambient.
An "ohmic" connection, joining or communication is one that behaves electrically in a manner substantially in accordance with Ohm's Law.
"Conductive joining" refers to fastening two conductive articles together such that ohmic electrical communication is achieved between them. "Conductive joining" includes soldering, welding such as achieved with current, laser, heat etc., conductive adhesive application, mechanical contacts achieved with crimping, twisting and the like, and laminated contacts as described herein.
An "additive process" is one wherein there is no substantial removal of material in order to generate a desired material form. Examples of additive processing are metal electrodeposition and placement of preformed shapes such as metal wires and strips. Examples of non-additive processing (subtractive processing) are photoetching of metal foils to produce selectively patterned metal devices.
A "structural polymer" is a polymer, such as a plastic, that can provide structural support, often to overlying or underlying structure. A "structural polymer" may also be referred to as a "polymeric support" or a "polymeric carrier".
"Heat sealing" is a process of attaching two forms together using heat. Heat sealing normally involves softening of the surfaces of one or both forms to allow material flow and bond activation. "Heat sealing" can involve a simple welding of two similar materials or may employ an intermediary adhesive to bond (seal) the two materials to each other.
"Overlapping" identifies a condition wherein one layer or structure either completely or partially overlays or covers another. Overlapping may comprise either complete or partial coverage.
"Laminating" is a process involving the mating of two or more surfaces. It normally involves partial or complete overlapping of two or more material bodies. The bodies normally have a "sheetlike" form such that the laminating process positions the "sheetlike" forms relative to each other as a layered combination. Laminating often involves the activation of an intermediary "laminating" adhesive medium between the "sheetlike" forms to securely attach the layers to each other. Activation of the "laminating" adhesive is normally accomplished using heat and/or pressure to cause the adhesive to soften and flow to "wet" and intimately contact the mating surface.
"Vacuum lamination" is a process wherein multiple material layers are stacked and a vacuum is drawn encompassing the assembly. Heat is also normally used to activate intermediary adhesive layers to bond the stacked layers together.
"Roll lamination" is a process wherein one or more material layers are fed to a pair of rollers positioned with a determined separation (a "nip"). In passing through the "nip" the layers are squeezed together. The layers may be heated during the squeezing process to cause flow and contact of an intermediary thermoplastic adhesive. Alternatively, a pressure sensitive adhesive may be employed without heating wherein pressure causes flow of adhesive to wet the surfaces.
A "laminated contact" is an electrical and physical contact between two conductive structures which is established and maintained by a polymeric laminating adhesive. A first of the conductive structures is positioned between the polymeric adhesive and a surface of the second conductive structure. Laminating the adhesive to the surface of the second structure keeps the first conductive structure between them. The "blanketing" of the first conductive structure securely holds the first and second conductive structures together.
When describing an object, the adjective "flexible" means that the object may be significantly deformed without breaking. An object may often be flexible because one of its dimensions such as thickness is small. In addition, flexibility is often, though not always, accompanied by elasticity in that the object is not necessarily permanently deformed by bending and can be returned to substantially its original shape after being deformed.
The terms "preponderance" or "major portion" designate a quantity greater than fifty percent (i.e. 50%, 60%, 70%, 80%, 90%, 95%, 100%).
"Transparent" is an adjective characterizing a material or structure that will transmit a preponderance or major portion of impinging light or electromagnetic radiation. When used to characterize a component of a photovoltaic device, transparent describes structure which transmits radiation (such as visible light) to an extent sufficient to allow acceptable performance of the device.
"Translucent" is an adjective characterizing a structure that transmits a preponderance or major portion of impinging light or electromagnetic radiation but diffuses a portion such that transmitted images are rendered cloudy or blurred.
"Metal oxide" is a chemical compound comprising two or more elements one of which is oxygen and a least one of which is a metal.
"Substrate" is a structure that can provide support.
An "interconnection component" or "interconnecting component" is a structure designed to facilitate power collection from one or more photovoltaic cells. An "interconnection component" may comprise a current collector structure, an interconnection structure, or a combination of both a current collector and interconnection structure.
"Solder" is a low melting point metal or metal alloy often used to achieve conductive joining.
"Conductive adhesive" is a conductive polymeric material that can adhesively bond to a surface.
"Conductive adhesives" are often employed to achieve conductive joining.
A "coating" is a layer of material overlaying a base structure.

Collector grid and interconnect structures for photovoltaic arrays and modules


Various embodiments for calculating a motion vector predictor for decoding a motion vector of a current block are provided. The motion vector is selected from a candidate list. When a motion vector used for coding a first block spatially adjacent to the current block in a current picture is useable for coding the current block, one or more first candidates is added to the candidate list based on the motion vector used for coding the first block. A second candidate is added to the candidate list based on a motion vector used for coding a second block within a first collocated picture. When a total number of available candidates in the candidate list is less than a predetermined number, a third candidate is added to the candidate list based on a motion vector used for coding a third block within a second collocated picture.

In moving picture coding processing, in general, the amount of information is reduced by utilizing redundancy in the spatial direction and the temporal direction which moving pictures have. Here, in general, transform to a frequency domain is used as a method utilizing redundancy in the spatial direction. Further, inter-picture prediction (hereinafter, referred to as "inter prediction") coding processing is used as a method utilizing redundancy in the temporal direction. In inter prediction coding processing, when a picture is coded, a coded picture that appears before or after a current picture to be coded in the display time order is used as a reference picture. A motion vector is derived by performing motion detection on the current picture relative to the reference picture. Then, redundancy in the temporal direction is eliminated by calculating a difference between image data of the current picture and predicted image data obtained by performing motion compensation based on the derived motion vector (for example, see Non Patent Literature (NPL) 1). Here, in motion detection, a difference value between a current block in a current picture to be coded and a block in a reference picture is calculated, and a block in the reference picture with which the smallest difference value is obtained is determined as a reference block. Then, a motion vector is detected using the current block and the reference block.

Video encoding method, video encoding apparatus, video decoding method, video decoding apparatus, and video encoding/decoding apparatus


A belt pressure reduction device comprises a combining portion being formed by folding two sides of a plane structure so that one side covers upon another side to form an adhering section so as to form a hollow receiving space within the combining portion for receiving an air cushion and a belt; one end of the air cushion being an airbag and another end thereof being an air inflation unit. The inflation unit serves to inflate air into the air cushion so as to cause the airbag to be elastic. The air cushion is not separated from the combining portion. The inflation unit of the air cushion exposes out of the combining portion. The combining portion is formed with at least one air hole. Two ends of the combining portion are foldable and unfoldable repeatedly.

In the prior art, the belt applies a great pressure to the shoulders of a user. To improve this defect, a shoulder protection portion is formed on the belt so as to reduce the pressure on the shoulders. The protection portion is formed by fiber cloth or sponges. However the elastic coefficients of the fiber cloth and sponge are small. The protection portion will fatigue elastically or deform after being used for a longer time period or as the bag supported by the belt is heavy. Thereby the prior art is a not a preferred one, which can not improve the prior art defect completely.


Disclosed is a crosslinked polymer nanoparticle containing composition, a method for preparing a copolymer using the composition, and a vinyl chloride resin with improved foam molding properties. Processing aid in according with the present invention, provides the effects of improved foam molding properties and processibility of a vinyl chloride resin, during a foam molding process upon being added to the vinyl chloride resin.

1. Field of the Invention
The present invention relates to a crosslinked polymer nanoparticle containing composition, a method for preparing a copolymer using the composition, and a vinyl chloride resin with improved foam molding properties comprising the same, and more particularly, to a crosslinked polymer nanoparticle containing composition capable of providing improved foam molding properties upon being added to a vinyl chloride resin (PVC), a method of preparing a copolymer using the composition, and a vinyl chloride resin with improved foam molding properties comprising the copolymer.
2. Description of the Related Art
Vinyl chloride resins that are polymers containing more than 50% of vinyl chloride have various applications due to its affordable, easy to control as hardness, and can be applied to most of the processing equipment. In addition, since they provide molded products having excellent physical and chemical properties, vinyl chloride resins have been widely used in various fields.
Such widely used vinyl chloride resins have several disadvantages in terms of impact strength, processibility, thermal stability, and thermal deformation temperature. Thus, additives have been developed to compensate these drawbacks. Additives such as impact modifiers, processing aids, stabilizers, fillers, and the like, were appropriately selected depending on the purpose and use thereof.
Recently, an attention has been increased to foam molding as a means to be lightweight and reduce prices of molded products. However, if it foam-molded vinyl chloride resins alone, it cannot have sufficient elongation and melt strength, so that the products have poor appearance, and cannot get low foaming magnification due to large size and non-uniform of foaming cell size. Thus, in order to complement these drawbacks, a method of adding a processing aid including methyl methacrylate as the main ingredient and a foaming agent to a vinyl chloride resin has been generally used.
U.S. Pat. No. 6,140,417 discloses a polymerization method of one compound selected from the group consisting of methyl methacrylate, alkyl acrylate, and alkyl methacrylate with a copolymerizable vinyl monomer in a three-stage process to improve processibility and foamability. The three-stage polymerization process comprises first stage polymerization of adjusting low glass transition temperature (Tg), second stage polymerization of adjusting the Tg higher than that of the first stage polymerization, and third stage polymerization of adjusting the Tg lower than that of the second stage polymerization.
In addition, U.S. Pat. No. 6,221,966 discloses a two-stage polymerization method to improve processibility, transparency, and foaming properties of the vinyl chloride resin, which decreases the size of the particle diameter, the outer layer of the two-stage has relatively higher glass transition temperature(Tg), and the inner layer has relatively lower glass transition temperature(Tg) of the two-stage by reducing the content of methyl methacrylate. However, this method provides insufficient processibility enhancement and uniformity of foamed cells.
U.S. Pat. No. 6,391,976 also discloses a method of adding a small amount of a processing aid consisting of methyl methacrylate and alkyl methacrylate having 3 to 5 of carbon number, however, the method does not meet processibility and foaming properties.

Crosslinked polymer nanoparticles containing composition, method for preparing a copolymer using the composition, and vinyl chloride with improved foam molding properties


A current to current charge pump including two flying capacitors, a capacitor driver, two rectifying inverters, a bypass capacitor coupled between an input node and a control node, a current control transistor circuit coupled between the control node and a reference node, and an output circuit coupled between upper and lower nodes. One of the upper and lower nodes is held at a constant voltage level. A storage capacitor is coupled between the upper and lower nodes. The capacitor driver drives each of the flying capacitors to opposite states between the control and input nodes using a clock signal. The rectifying inverters are cross-coupled between the flying capacitors, and have supply terminals coupled between the upper and lower nodes. The current control transistor circuit develops an input current at the control node based on a reference current. The output transistor circuit develops an output current that follows the input current.

Field of the Invention
The present invention relates in general to charge pumps, and more particularly to a self-regulating, current in, current out (current to current) charge pump.
Description of the Related Art
Conventional charge pumps typically convert one voltage to another voltage. Many configurations operate as doublers or triplers or the like in which the output voltage is a selected multiple of the input voltage. In many applications it is desired to provide a current in, current out (or current to current) charge pump, that is, a charge pump that converts an input current to an output current. One such application is an analog comparator, in which it is desired to provide the tail current (or common source current) for PMOS transistors connected as a differential pair at the input of the analog comparator. It is beneficial to have the output current track the input current over process and temperature variations so that the ratio of the output current to the input current remains approximately constant. A conventional approach is to provide regulation circuitry with feedback to maintain the desired current conversion ratio between the input and output of the charge pump. It has been determined, however, that such regulation circuitry can lead to instabilities caused by the feedback regulation circuitry.

Self regulating current to current charge pump


An impeller is applied to a centrifugal fan and includes fan blades and a hub. Each fan blade includes a first portion and a second portion. The first portion is located relatively close to the hub and the first portion is coupled to the second portion. The first portion has a windward side and a leeward side, and the windward side is parallel to the leeward side. The second portion is located relatively far away from the hub. The second portion has a windward side and a leeward side, and the windward side and the leeward side are two curved surfaces with different specific curvatures.

In a conventional system, since its internal electronic element is a large heat source, and the performance of the internal electronic element degrades with the increase of the temperature thereof, the heat generated thereby has to be quickly removed so as to keep the internal electronic element's regular performance. Therefore, a blower having high air pressure is commonly used to achieve the objective of rapidly dissipating heat.
Conventionally, a fan with high air pressure is known as a centrifugal fan or blower. Please refer to both FIG. 1 and FIG. 2, the conventional impeller 100 has a hub 102, fan blades 104 and a rib 106. The rib 106 is disposed and connected between the fan blades 104 and the hub 102. The curvatures of the surfaces 108 and 110 (i.e. a windward side and a leeward side) of the fan blade 104 are the same and can be considered as two concentric arcs, which means the thickness of the fan blade 104 is uniform.
While the performance of an electronic element is enhanced, the heat generated by the electronic element is also greatly increased accordingly. Hence, the rotational speed of the conventional blower used has to be greatly increased so as to obtain the desired air pressure and air flow. However, when the rotational speed is increased, the noise level generated thereby raises correspondingly.
Although the noise level can be reduced by lowering the rotational speed of the conventional blower, the heat generated by the aforementioned electronic element can't be removed completely due to the less air flow and air pressure thereof.


A magnetic shift register utilizes a data column comprising a thin wire of magnetic material. A writing element selectively changes the direction of the magnetic moment in the magnetic domains to write the data to the data column. Associated with each domain wall are large magnetic fringing fields concentrated in a very small space. These magnetic fringing fields write to and read from the magnetic shift register. When the domain wall is moved close to another magnetic material, the fringing fields change the direction of the magnetic moment in the magnetic material, effectively “writing” to the magnetic material. A reading element similar to a tunneling junction comprises a free layer and a pinned layer of magnetic material. Fringing fields change the direction of the magnetic moment in the free layer with respect to the pinned layer, changing electrical resistance of the reading element and “reading” data stored in the magnetic shift register.

The two most common conventional non-volatile data storage devices are disk drives and solid-state random access memories (RAM). Disk drives are capable of inexpensively storing large amounts of data, i.e., greater than 100 GB. However, disk drives are inherently unreliable. A hard drive comprises a fixed read/write head and a moving medium upon which data are written. Devices with moving parts tend to wear out and fail. Solid-state random access memories currently store data on the order of 1 GB (gigabyte) per device, and are relatively expensive, per storage unit, compared to a disk drive.
The most common type of solid-state RAM is flash memory. Flash memory relies on a thin layer of polysilicon that is disposed in oxide below an on-off control gate of a transistor. This layer of polysilicon is a floating gate, isolated by the silicon from the control gate and the transistor channel. Flash memory is relatively slow, with reading and writing times on the order of a microsecond. In addition, flash memory cells can begin to lose data after less than a million write cycles. While this may be adequate for some applications, flash memory cells may begin to fail rapidly if used constantly to write new data, such as in the main memory of a computer. Further, the access time for flash memory is much too long for computer applications.
Another form of RAM is the ferroelectric RAM, or FRAM. FRAM stores data based on the direction that ferroelectric domains point. FRAM has access times much faster than Flash memory and consumes less energy than standard dynamic random access memory (DRAM). However, commercially available memory capacities are currently low, on the order of 1 MB (megabyte). In addition, memory storage in a FRAM relies on physically moving atoms, leading to eventual degradation of the medium and failure of the memory.
Yet another form of RAM is the Ovonic Unified Memory (OUM) that utilizes a material that alternates between crystalline and amorphous phases to store data. The material used in this application is a chalcogenide alloy. After the chalcogenide alloy experiences a heating and cooling cycle, it can be programmed to accept one of two stable phases: polycrystalline or amorphous. The differences in the respective resistances of the two phases allow the chalcogenide alloy to be used as memory storage. Data access time is on the order of 35 ns. However, the size of these memories is still small, on the order of 4 MB currently. In addition, OUM relies on physically changing a material repeatedly to and from crystalline and amorphous states, likely causing the material to eventually degrade and fail.
Semiconductor magnetoresistive RAM (MRAM) encodes data bits in a ferromagnetic material by utilizing the direction of the magnetic moment of the material. Atoms in ferromagnetic materials respond to external magnetic fields, aligning their magnetic moments to the direction of the applied magnetic field. When the field is removed, the magnetic moments of the atoms still remain aligned in the induced direction. A field applied in the opposite direction causes the atoms to realign themselves with the new direction. Typically, the magnetic moments of the atoms within a volume of the ferromagnetic material are aligned parallel to one another by a magnetic exchange interaction. These atoms then respond together, largely as one macro-magnetic moment, or magnetic domain, to the external magnetic field.
One approach to MRAM uses a magnetic tunneling junction as the memory cell. The magnetic tunneling junction comprises two layers of ferromagnetic material separated by a thin insulating material. The direction of the magnetic domains is fixed in one layer. In the second layer, the domain direction is allowed to move in response to an applied field. Consequently, the direction of the domains in the second layer can either be parallel or opposite to the first layer, allowing the storage of data in the form of ones and zeros. However, currently available MRAM can only store up to 4 Mb (megabits), much less than needed for most memory applications. Larger memories are currently in development. In addition, each MRAM memory cell stores only one bit of data, thereby limiting the maximum possible memory capacity of such devices.
A magnetic shift register replaces many conventional memory devices including but not limited to magnetic recording hard disk drives, and many solid-state memories such as Flash, DRAM, SRAM, FeRAM, and MRAM. The magnetic shift register provides capacious amounts of storage comparable to those provided in conventional memory devices but without any moving parts and at a cost comparable to hard disk drives.
What is needed is an improved configuration for the magnetic data tracks and a method for writing to and reading from the improved configuration.

This patent is subject to a terminal disclaimer.

System and method for transferring data to and from a magnetic shift register with a shiftable data column

International Business Machines Corporation


A semiconductor sensing device (10) for sensing a lateral acceleration includes a field effect transistor (132) fabricated along a sidewall (114) of a trench (112) formed in a substrate (11). A movable gate (12) overlies a channel region (138) of the field effect transistor (132). In response to a lateral acceleration perpendicular to the sidewall (114) of the trench (112), the movable gate (12) moves relative to the substrate (11) in a direction substantially perpendicular to the sidewall (114). The conductive state of the channel region (138) depends on the distance between the movable gate (12) and the channel region (138) and changes in response to the lateral acceleration Thus, the motion of the movable gate (12) modulates a current flowing in the field effect transistor (132). The lateral acceleration is sensed by sensing the current flowing in the field effect transistor (132).

The present invention relates, in general, to semiconductor devices and, more particularly, to semiconductor sensing devices.
Acceleration sensors are used in motion sensing applications such as, for example, motion sensing for controlling air bags in automobiles. One type of acceleration sensor includes a field effect transistor having a movable gate structure. When the substrate on which the field effect transistor is fabricated experiences an acceleration in a normal direction perpendicular to the front surface of the substrate, the movable gate moves towards or away from the front surface of the substrate. A current flowing in the field effect transistor changes in response to the motion of the movable gate in the normal direction. An amplifier coupled to the field effect transistor amplifies the current change and senses the normal acceleration.
To sense an acceleration in a lateral direction substantially parallel to the front surface of the substrate, a field effect transistor is fabricated to have a movable gate that is movable in the lateral direction. When the substrate experiences a lateral acceleration, the motion of the movable gate changes the channel width of the field effect transistor, thereby modulating the current carrying capability of the field effect transistor. An amplifier coupled to the field effect transistor amplifies the current change in the field effect transistor and senses the lateral acceleration. However, the change in the channel width is usually very small compared with the channel width of the field effect transistor. Therefore, the sensitivity of the field effect transistor to the lateral acceleration is low, usually at least ten time lower than the sensitivity of a field effect transistor of comparable size to the normal acceleration.
Accordingly, it would be advantageous to have a semiconductor sensing device and a method for fabricating the semiconductor sensing device. It is desirable for the sensing device to be able to accurately sense a lateral acceleration. It is also desirable for the method for fabricating the sensing device to be cost efficient and compatible with standard Metal Oxide Semiconductor (MOS) technologies. It would be of further advantage if the sensing device is simple, reliable, and can be easily implemented with other integrated circuit devices in a monolithic semiconductor chip.

Semiconductor sensing device and method for fabricating the same


In order to insert a regenerator into a wavelength cross-connect equipment, there is provided at least one port that demultiplexes one wavelength among the wavelength multiplexed signals that are input to a wavelength selective switch. An output of the port that demultiplexes one wavelength is input to the regenerator, and an output of the regenerator is again input to the WSS. The wavelength output from the regenerator is converted into another wavelength different from the wavelength that is input to the regenerator and can be processed by the WSS in advance. The output from the regenerator is input to the WSS through an optical coupler or another input port of the WSS.

The present invention relates to an optical transmission equipment and an optical network therefor, and more particularly to an optical transmission equipment using a wavelength selective switch and an optical network therefor.
In switching for each of wavelengths at a transmission equipment node in a wavelength division multiplexing (WDM) optical network in which optical signals of plural wavelengths are multiplexed within one optical fiber, an optical add/drop multiplexer (OADM) that demultiplexes and receives a part of wavelength within the plural wavelengths, and adds and transmits a part of wavelength within the plural wavelengths is commercially introduced, and is mainly being used in the optical network. In the future, development is expected of a wavelength cross-connect (WXC) equipment using a wavelength selective switch that not only demultiplexes and receives a part of wavelength, but also distributes and transmits an arbitrary wavelength to plural routes, and adds a part of wavelength, and distributes and transmits the added wavelength to an arbitrary route, with the prospect of the wavelength cross-connect equipment to be diversified into the optical network.
Referring to FIGS. 1A to 1D, the topology of a wavelength control optical network using the OADM and the WXC will be described. FIGS. 1A to 1D are block diagrams showing the optical network. For simplification of drawing, transmission/reception in one direction is shown in FIGS. 1A to 1D. Also, FIGS. 1A and 1B show only one node. Add and drop are represented by typical nodes. In FIGS. 1A to 1D and subsequent figures, bold solid lines represent an optical signal that is equal to larger than 1 in the number of wavelengths, and thin solid lines represent an optical signal that is 1 in the number of wavelength.
The OADM optical network is formed of a linear or ring network as shown in FIGS. 1A and 1C. The WDM signal into which plural wavelengths are multiplexed conducts the operation of drop, add, and through in each of the wavelengths by an OADM equipment 100, and transmits or receives the optical signal between the respective nodes.
The WXC node of the WXC optical network is applied to a node of a mesh network or a node of connection between the rings as shown in FIGS. 1B and 1D. A WXC equipment 20 conducts the operation of drop, add, and through in each of the wavelengths of the WDM signals that come from plural routes, distributes the WDM signals in the plural routes, and transmits or receives the optical signal between the respective nodes.
Referring to FIG. 1D, nodes other than between-ring connection nodes are formed of the OADM equipments 100, but may be formed of the WXC equipment 200. Referring to FIGS. 1A to 1D, a drop optical signal is output to a first optical transponder not shown. On the other hand, an add optical signal is an output signal of a second optical transponder (not shown) having a predetermined wavelength.
Referring to FIG. 2, the configuration of the OADM equipment will be described. FIG. 2 is a block diagram of the OADM equipment. Referring to FIG. 2, the WDM signal that is a wavelength multiplexed signal is demultiplexed, dropped or goes through in each of the wavelengths by a demultiplexer (DMUX) 11. Also, the added wavelengths are multiplexed with the through signals by a multiplexer (MUX) 12, and then transmitted. The OADM equipment 100 has a configuration of two routes/directions of a route a and a route b. In this example, the through signal is demultiplexed in each of the wavelengths, one by one. For that reason, when the transmitted optical signal is deteriorated by the low OSNR (optical signal to noise ratio), photoelectric conversion and electro-optical conversion are conducted by a regenerator (RGN) 3 to newly transmit an optical signal.
However, in the WXC equipment using the wavelength selective switch, because there exists no port where the through signal is demultiplexed wavelength by wavelength, no regenerator cannot be inserted, as disclosed in JP 2003-125430A.

Optical transmission equipment and optical network