A process for producing a unitary graphene material, comprising: (a) preparing a graphene oxide (GO) gel having GO molecules dissolved in a fluid medium wherein the GO molecules contain higher than 20% by weight of oxygen; (b) dispensing and depositing a layer of GO gel onto a surface of a substrate to form a layer of deposited GO gel thereon, wherein the dispensing and depositing procedure includes shear-induced thinning; (c) removing the fluid medium from the deposited GO gel to form a GO layer having an inter-plane spacing d002 of 0.4 nm to 1.2 nm as determined by X-ray diffraction; and (d) heat treating the GO layer to form the unitary graphene material at a heat treatment temperature higher than 100° C. to an extent that d002 is decreased to a value of 0.3354 nm to 0.4 nm and the oxygen content is decreased to less than 5% by weight.

Advanced thermal management materials are becoming critical for today's microelectronic, photonic, and photovoltaic systems. For instance, as new and more powerful chip designs and light-emitting diode (LED) systems are introduced, they consume more power and generate more heat. This has made thermal management a crucial issue in today's high performance systems. Systems ranging from active electronically scanned radar arrays, web servers, large battery packs for personal consumer electronics, wide-screen displays, and solid-state lighting devices all require high thermal conductivity materials that can dissipate heat more efficiently. On the other hand, the devices are designed and fabricated to become increasingly smaller, thinner, lighter, and tighter. This further increases the difficulty of thermal dissipation. Actually, thermal management challenges are now widely recognized as the key barriers to industry's ability to provide continued improvements in device and system performance.
One group of materials potentially suitable for heat dissipation applications is the graphitic carbon or graphite. Carbon is known to have five unique crystalline structures, including diamond, fullerene (0-D nano graphitic material), carbon nano-tube or carbon nano-fiber (1-D nano graphitic material), graphene (2-D nano graphitic material), and graphite (3-D graphitic material). The carbon nano-tube (CNT) refers to a tubular structure grown with a single wall or multi-wall. Carbon nano-tubes (CNTs) and carbon nano-fibers (CNFs) have a diameter on the order of a few nanometers to a few hundred nanometers. Their longitudinal, hollow structures impart unique mechanical, electrical and chemical properties to the material. The CNT or CNF is a one-dimensional nano carbon or 1-D nano graphite material.
Bulk natural flake graphite is a 3-D graphitic material with each particle being composed of multiple grains (a grain being a graphite single crystal or crystallite) with grain boundaries (amorphous or defect zones) demarcating neighboring graphite single crystals. Each grain is composed of multiple graphene planes that are oriented parallel to one another. A graphene plane in a graphite crystallite is composed of carbon atoms occupying a two-dimensional, hexagonal lattice. In a given grain or single crystal, the graphene planes are stacked and bonded via van der Waal forces in the crystallographic c-direction (perpendicular to the graphene plane or basal plane). Although all the graphene planes in one grain are parallel to one another, typically the graphene planes in one grain and the graphene planes in an adjacent grain are different in orientation. In other words, the orientations of the various grains in a graphite particle typically differ from one grain to another.
A graphite single crystal (crystallite) per se is anisotropic with a property measured along a direction in the basal plane (crystallographic a- or b-axis direction) being dramatically different than if measured along the crystallographic c-axis direction (thickness direction). For instance, the thermal conductivity of a graphite single crystal can be up to approximately 1,920 W/mK (theoretical) or 1,800 W/mK (experimental) in the basal plane (crystallographic a- and b-axis directions), but that along the crystallographic c-axis direction is less than 10 W/mK (typically less than 5 W/mK). Further, the multiple grains or crystallites in a graphite particle are typically all oriented along different directions. Consequently, a natural graphite particle composed of multiple grains of different orientations exhibits an average property between these two extremes (i.e. between5 W/mK and 1,800 W/mK.
It would be highly desirable in many applications to produce a bulk graphite particle (containing single or multiple grains) having sufficiently large dimensions and having all graphene planes being essentially parallel to one another along one desired direction. For instance, it is highly desirable to have one large-size graphite entity (e.g. a fully integrated or unitary layer of multiple graphene planes) having the c-axis directions of all the graphene planes being substantially parallel to one another and having a sufficiently large length and/or width for a particular application (e.g. >5 cm2 for use as a heat-spreading sheet on a CPU of a smart phone) and a sufficient thickness (e.g. >10 μm and more preferably >20 μm) to impart rigidity to a thin film for easy handling. It would be further desirable if such a "giant graphite particle" has only one grain or few grains (thus, no or little grain boundaries) and has few or no defects therein to impede the flow of electrons and phonons. Thus far, it has not been possible to produce this type of large-size unitary graphene entity from existing natural or synthetic graphite particles.
The constituent graphene planes of a graphite crystallite can be exfoliated and extracted or isolated from a graphite crystallite to obtain individual graphene sheets of carbon atoms provided the inter-planar van der Waals forces can be overcome. An isolated, individual graphene sheet of carbon atoms is commonly referred to as single-layer graphene. A stack of multiple graphene planes bonded through van der Waals forces in the thickness direction with an inter-graphene plane spacing of 0.3354 nm is commonly referred to as a multi-layer graphene. A multi-layer graphene platelet has up to 300 layers of graphene planes (<100 nm in thickness), but more typically up to 30 graphene planes (<10 nm in thickness), even more typically up to 20 graphene planes (<7 nm in thickness), and most typically up to 10 graphene planes (commonly referred to as few-layer graphene in scientific community). Single-layer graphene and multi-layer graphene sheets are collectively called "nano graphene platelets" (NGPs). Graphene sheets/platelets or NGPs are a new class of carbon nano material (a 2-D nano carbon) that is distinct from the 0-D fullerene, the 1-D CNT, and the 3-D graphite.
Our research group pioneered the development of graphene materials and related production processes as early as 2002: (1) B. Z. Jang and W. C. Huang, "Nano-scaled Graphene Plates," U.S. Pat. No. 7,071,258 (Jul. 4, 2006), application submitted on Oct. 21, 2002; (2) B. Z. Jang, et al. "Process for Producing Nano-scaled Graphene Plates," U.S. patent application Ser. No. 10/858,814 (Jun. 3, 2004); and (3) B. Z. Jang, A. Zhamu, and J. Guo, "Process for Producing Nano-scaled Platelets and Nanocomposites," U.S. patent application Ser. No. 11/509,424 (Aug. 25, 2006).
NGPs are typically obtained by intercalating natural graphite particles with a strong acid and/or oxidizing agent to obtain a graphite intercalation compound (GIC) or graphite oxide (GO), as illustrated in FIG. 1(a) (process flow chart) and FIG. 1(b) (schematic drawing). The presence of chemical species or functional groups in the interstitial spaces between graphene planes serves to increase the inter-graphene spacing (d002, as determined by X-ray diffraction), thereby significantly reducing the van der Waals forces that otherwise hold graphene planes together along the c-axis direction. The GIC or GO is most often produced by immersing natural graphite powder (20 in FIGS. 1(a) and 100 in FIG. 1(b)) in a mixture of sulfuric acid, nitric acid (an oxidizing agent), and another oxidizing agent (e.g. potassium permanganate or sodium perchlorate). The resulting GIC (22 or 102) is actually some type of graphite oxide (GO) particles. This GIC is then repeatedly washed and rinsed in water to remove excess acids, resulting in a graphite oxide suspension or dispersion, which contains discrete and visually discernible graphite oxide particles dispersed in water. There are two processing routes to follow after this rinsing step:
Route 1 involves removing water from the suspension to obtain "expandable graphite," which is essentially a mass of dried GIC or dried graphite oxide particles. Upon exposure of expandable graphite to a temperature in the range of typically 800-1,050° C. for approximately 30 seconds to 2 minutes, the GIC undergoes a rapid expansion by a factor of 30-300 to form "graphite worms" (24 or 104), which are each a collection of exfoliated, but largely un-separated graphite flakes that remain interconnected. A SEM image of graphite worms is presented in FIG. 2(a).
In Route 1A, these graphite worms (exfoliated graphite or "networks of interconnected/non-separated graphite flakes") can be re-compressed to obtain flexible graphite sheets or foils (26 or 106) that typically have a thickness in the range of 0.1 mm (100 μm)-0.5 mm (500 μm). Alternatively, one may choose to use a low-intensity air mill or shearing machine to simply break up the graphite worms for the purpose of producing the so-called "expanded graphite flakes" (108) which contain mostly graphite flakes or platelets thicker than 100 nm (hence, not a nano material by definition).
Exfoliated graphite worms, expanded graphite flakes, and the recompressed mass of graphite worms (commonly referred to as flexible graphite sheet or flexible graphite foil) are all 3-D graphitic materials that are fundamentally different and patently distinct from either the 1-D nano carbon material (CNT or CNF) or the 2-D nano carbon material (graphene sheets or platelets, NGPs). Flexible graphite (FG) foils can be used as a heat spreader material, but exhibiting a maximum in-plane thermal conductivity of typically less than 500 W/mK (more typically <300 W/mK) and in-plane electrical conductivity no greater than 1,500 S/cm. These low conductivity values are a direct result of the many defects, wrinkled or folded graphite flakes, interruptions or gaps between graphite flakes, and non-parallel flakes (e.g. SEM image in FIG. 2(b)). Many flakes are inclined with respect to one another at a very large angle (e.g. mis-orientation of 20-40 degrees).
In Route 1B, the exfoliated graphite is subjected to high-intensity mechanical shearing (e.g. using an ultrasonicator, high-shear mixer, high-intensity air jet mill, or high-energy ball mill) to form separated single-layer and multi-layer graphene sheets (collectively called NGPs, 33 or 112), as disclosed in our U.S. application Ser. No. 10/858,814. Single-layer graphene can be as thin as 0.34 nm, while multi-layer graphene can have a thickness up to 100 nm, but more typically less than 20 nm.
Route 2 entails ultrasonicating the graphite oxide suspension for the purpose of separating/isolating individual graphene oxide sheets from graphite oxide particles. This is based on the notion that the inter-graphene plane separation has been increased from 0.3354 nm in natural graphite to 0.6-1.1 nm in highly oxidized graphite oxide, significantly weakening the van der Waals forces that hold neighboring planes together. Ultrasonic power can be sufficient to further separate graphene plane sheets to form separated, isolated, or discrete graphene oxide (GO) sheets. These graphene oxide sheets can then be chemically or thermally reduced to obtain "reduced graphene oxides" (RGO) typically having an oxygen content of 0.001%-40% by weight, more typically 0.01%-5% by weight, most typically and highly desirably less than 2% by weight.
For the purpose of defining the claims of the instant application, NGPs include discrete sheets/platelets of single-layer and multi-layer graphene, graphene oxide, or reduced graphene oxide with an oxygen content of 0-10% by weight, more typically 0-5% by weight, and preferably 0-2% by weight. Pristine graphene has essentially 0% oxygen. Graphene oxide (including RGO) can have 0.001%-46% by weight of oxygen.
The GO molecules in graphene oxide gel, to be described in detail later, typically contains 20-50% by weight oxygen (more typically 30-47%) immediately after removal of the liquid from the GO gel, but prior to a subsequent heat treatment. The GO gel refers to a homogeneous solution of highly hydrophilic aromatic molecules (graphene oxide molecules bearing oxygen-containing groups, such as —OH, —COOH, and >O, on molecular planes or at the edges) that are dissolved (not just dispersed) in a liquid (e.g. acidic water). The GO gel per se does not contain visibly discernible or discrete graphene or GO particles in the form of solid sheets or platelets. These GO molecules and the dispersing liquid medium have comparable indices of refraction, making the resulting gel optically transparent or translucent (if the proportion of GO molecules are bot excessively high), or showing lightly brown color. In contrast, the simple mixture of original graphite particles or discrete NGP sheets/platelets with acids and/or water appears optically dark and totally opaque (even with only <0.1% solid particles suspended in the liquid medium). These particles or NGP platelets are simply dispersed (not dissolved) in the fluid medium.
These GO molecules in a GO gel are highly reactive and may be considered as "living giant molecules". By contrast, the prior art solid sheets/platelets of graphene, GO, and RGO are essentially "dead" species. The GO gel can be formed into a shape with a proper shearing or compression stress (e.g. via casting or molding), dried (with liquid components partially or totally removed), and heat-treated under certain conditions to obtain a unitary graphene material, which is typically a single crystal, a poly-crystal with incomplete or poorly delineated grain boundaries, or a poly-crystal with very large grain sizes (very few grains). The heat treatment serves to chemically link these active or live GO molecules to form a 2-D or 3-D network of chemically bonded graphene molecules of essentially infinite molecular weights, and to drastically reduce the oxygen content of GO down to below 10% by weight, more typically <5%, further more typically <2%, and most typically <<1%. Only a trace amount of oxygen (practically 0%) can survive if the heat treatment temperature is sufficiently high and heat treatment time sufficiently long. This new and unique material called "unitary graphene material" will be further described in detail later.
Although the GO gel per se does not contain visibly discernible/discrete graphene sheets/platelets or NGPs (including "dead" GO sheets/platelets), one can intentionally add discrete graphene sheets/platelets, expanded graphite flakes, and other type of solid filler in the GO gel to form a mixture gel. This mixture gel may be dried and subjected to the same heat treatment to convert the live GO molecules into a unitary graphene material, also enabling these active molecules to chemically bond to the filler particles. This graphene oxide gel-derived graphene material, reinforced with a filler phase (e.g. discrete NGPs, CNTs and carbon fibers), constitutes the presently invented unitary graphene matrix composite as a readily mass-processible material.
It may be noted that flexible graphite foils (obtained by compressing or roll-pressing exfoliated graphite worms) for electronic device thermal management applications (e.g. as a heat sink material) have the following major deficiencies:                (1) As indicated earlier, flexible graphite (FG) foils exhibit a relatively low thermal conductivity, typically <500 W/mK and more typically <300 W/mK. By impregnating the exfoliated graphite with a resin, the resulting composite exhibits an even lower thermal conductivity (typically <<200 W/mK, more typically <100 W/mK).        (2) Flexible graphite foils, without a resin impregnated therein or coated thereon, are of low strength, low rigidity, and poor structural integrity. The high tendency for flexible graphite foils to get torn apart makes them difficult to handle in the process of making a heat sink. As a matter of fact, the flexible graphite sheets (typically 50-200 μm thick) are so "flexible" that they are not sufficiently rigid to make a fin component material for a finned heat sink.        (3) Another very subtle, largely ignored or overlooked, but critically important feature of FG foils is their high tendency to get flaky with graphite flakes easily coming off from FG sheet surfaces and emitting out to other parts of a microelectronic device. These highly electrically conducting flakes (typically 1-200 μm in lateral dimensions and >100 nm in thickness) can cause internal shorting and failure of electronic devices.        (4) Both resin-free flexible graphite and resin-impregnated FG (with resin impregnating step occurring before or after roll-pressing) are not conducive to mass production of finned heat sink structures. It is virtually impossible to use mass production processes (such as extrusion, stamping, forging, and die casting that are commonly used for making aluminum heat sinks, or injection molding for making conductive filler-reinforced plastic-based heat sinks) to make FG-based heat sinks without some kind of subsequent bonding or assembling operations. One has to manually attach individual fin members to a core or base member. For instance, one may produce bonded fin heat sink assemblies in which each fin in the assembly is individually bonded into a heat sink base. A major shortcoming of such heat sinks is their high cost. This cost is related directly to the labor required to individually arrange each fin on some sort of support or substrate (a base or core) and high production cycle time. Further, bonding between a fin and a base is not always reliable and the long-term reliability of flexible graphite-based finned heat sinks is highly questionable.
Similarly, solid NGPs (including discrete sheets/platelets of pristine graphene, GO, and GRO), when packed into a film, membrane, or paper sheet (34 or 114) of non-woven aggregates, typically do not exhibit a high thermal conductivity unless these sheets/platelets are closely packed and the film/membrane/paper is ultra-thin (e.g. <1 μm, which is mechanically weak). This is reported in our earlier U.S. patent application Ser. No. 11/784,606 (Apr. 9, 2007). However, ultra-thin film or paper sheets (<10 μm) are difficult to produce in mass quantities, and difficult to handle when one tries to incorporate these thin films as a heat sink material. In general, a paper-like structure or mat made from platelets of graphene, GO, or RGO (e.g. those paper sheets prepared by vacuum-assisted filtration process) exhibit many defects, wrinkled or folded graphene sheets, interruptions or gaps between platelets, and non-parallel platelets (e.g. SEM image in FIG. 3(b)), leading to relatively poor thermal conductivity, low electric conductivity, and low structural strength. These papers or aggregates of discrete NGP, GO or RGO platelets alone (without a resin binder) also have a tendency to get flaky, emitting conductive particles into air.
Our earlier application (U.S. application Ser. No. 11/784,606) also disclosed a mat, film, or paper of NGPs infiltrated with a metal, glass, ceramic, resin, and CVD carbon matrix material (graphene sheets/platelets being the filler or reinforcement phase, not the matrix phase in this earlier application). Haddon, et al. (US Pub. No. 2010/0140792, Jun. 10, 2010) also reported NGP thin-film paper (aggregates of isolated platelets) and NGP-reinforced polymer matrix composites for thermal management applications. The processes used by Haddon et al to produce NGPs are identical to those disclosed much earlier by us (Jang, et al. U.S. patent application Ser. No. 10/858,814 (Jun. 3, 2004)). The NGP-reinforced polymer matrix composites, as an intended thermal interface material, have very low thermal conductivity, typically <<2 W/mK. The NGP films of Haddon, et al are essentially non-woven aggregates of discrete graphene platelets, identical to those of our earlier invention (U.S. application Ser. No. 11/784,606). Again, these aggregates have a great tendency to have graphite particles flaking and separated from the film surface, creating internal shorting problem for the electronic device containing these aggregates. They also exhibit low thermal conductivity unless made into thin films (10 nm-300 nm, as reported by Haddon, et al) which are very difficult to handle in a real device manufacturing environment. Balandin, et al (US Pub. No. 2010/0085713, Apr. 8, 2010) also disclosed a graphene layer produced by CVD deposition or diamond conversion for heat spreader application. More recently, Kim, et al (N. P. Kim and J. P. Huang, "Graphene Nanoplatelet Metal Matrix," US Pub. No. 2011/0108978, May 10, 2011) reported metal matrix infiltrated NGPs. However, the metal matrix is too heavy and the resulting metal matrix composite does not exhibit a high thermal conductivity. More significantly, all these prior art materials and related processes are not amenable to mass production of heat-dissipation structures, such as finned heat sinks, cost-effectively. In fact, there has been no known report on using these materials for finned heat sink applications.
Another prior art material for thermal management applications is the pyrolitic graphite film. The lower portion of FIG. 1(a) illustrates a typical process for producing prior art pyrolitic graphitic films from a polymer. The process begins with carbonizing a polymer film 46 (e.g. polyimide) at a carbonization temperature of 400-1,000° C. under a typical pressure of 10-15 Kg/cm2 for 2-10 hours to obtain a carbonized material 48, which is followed by a graphitization treatment at 2,500-3,200° C. under an ultrahigh pressure of 100-300 Kg/cm2 for 1-24 hours to form a graphitic film 50. It is technically utmost challenging to maintain such an ultrahigh pressure at such an ultrahigh temperature. This is a difficult, slow, tedious, energy-intensive, and extremely expensive process. Furthermore, carbonization of certain polymers (e.g. polyacrylonitrile) involves the emission of toxic species.
A second type of pyrolytic graphite is produced by high temperature decomposition of hydrocarbon gases in vacuum followed by deposition of the carbon atoms to a substrate surface. This vapor phase condensation of cracked hydrocarbons is essentially a chemical vapor deposition (CVD) process. In particular, highly oriented pyrolitic graphite (HOPG) is the material produced by the application of uniaxial pressure on deposited pyrocarbon or pyrolytic graphite at very high temperatures (typically 3,000-3,300° C.). This entails a thermo-mechanical treatment of combined and concurrent mechanical compression and ultra-high temperature for an extended period of time in a protective atmosphere; a very expensive, energy-intensive, and technically challenging process. The process requires ultra-high temperature equipment (with high vacuum, high pressure, or high compression provision) that is not only very expensive to make but also very expensive and difficult to maintain. Even with such extreme processing conditions, the resulting PG (including HOPG) still possesses many defects, grain boundaries, and mis-orientations (neighboring graphene planes not parallel to each other), resulting in less-than-satisfactory in-plane properties. Typically, the best prepared HOPG sheet or block remains far from being a graphite single crystal; instead, it typically still contains many grains or crystals and a vast amount of grain boundaries and defects. All PG film production processes do not allow for impregnation of a resin matrix. PG or HOPG films, being weak, non-rigid, and not easily processable suffer from the same shortcomings as flexible graphite intended for use to construct finned heat sinks.
Similarly, the most recently reported graphene thin film (<2 nm) prepared by catalytic CVD of hydrocarbon gas (e.g. C2H4) on Ni or Cu surface is not a single-grain crystal, but a poly-crystalline structure with many grain boundaries and defects. With Ni or Cu being the catalyst, carbon atoms obtained via decomposition of hydrocarbon gas molecules at 800-1,000° C. are deposited onto Ni or Cu foil surface to form a sheet of single-layer or few-layer graphene that is poly-crystalline. The grains are typically much smaller than 100 μm in size and, more typically, smaller than 10 μm in size. These graphene thin films, being optically transparent and electrically conducting, are intended for applications such as the touch screen (to replace indium-tin oxide or ITO glass) or semiconductor (to replace silicon, Si). However, these ultra-thin polycrystalline graphene films are not sufficiently thermally conducting (too many grains or too much grain boundaries, and all grains being oriented in different directions) and not sufficiently thick for use as a heat sink or heat spreader material. Furthermore, the Ni- or Cu-catalyzed CVD process does not lend itself to the deposition of more than 5-10 graphene planes (typically <2-4 nm) beyond which the underlying Ni or Cu catalyst can no longer provide any catalytic effect. There has been no experimental evidence to indicate that CVD graphene layer thicker than 5 or 10 nm is possible. Further, CVD is not conducive to the fabrication of a heat sink that is typically complex in shape.
Thus, it is an object of the present invention to provide a process for producing graphene oxide (GO) gel-derived unitary graphene material (monolithic graphene entity) or its composite version (containing, for instance, a carbon/graphite filler phase dispersed in or bonded by a unitary graphene matrix material derived from a GO gel), which exhibits a thermal conductivity comparable to or greater than the thermal conductivities of the PG (including HOPG), CVD graphene film, and/or flexible graphite (including resin-impregnated FG).
This thermally and electrically conductive graphene monolith or graphene matrix composite can be used to produce finned heat sinks cost effectively in large quantities, using commonly used, less complex, and easier-to-control processes with readily available, inexpensive equipment.
It is another object of the present invention to provide a process for producing GO-derived unitary graphene entity and graphene matrix composite that exhibit a combination of exceptional thermal conductivity, electrical conductivity, mechanical strength, surface hardness, and scratch resistance unmatched by any material of comparable thickness range.
It is a specific object of the present invention to provide a highly conductive unitary graphene material or graphene matrix composite that meets the following technical requirements (a) a thermal conductivity greater than 600 W/mK (preferably greater than 1,000 W/mK, and further preferably greater than 1,700 W/mK); (b) an electrical conductivity greater than 2,000 S/cm (preferably >3,000 S/cm, more preferably >5,000 S/cm, even more desirably >10,000 S/cm, and most preferably >15,000 S/cm); (c) Rockwell surface hardness value >60 (preferably >80); and/or (d) a tensile or flexural strength greater than 80 MPa (preferably >100 MPa, more preferably >150 MPa, and most preferably >200 MPa). No prior art material meets this set of technical requirements.
This new class of materials (i.e., a GO gel-derived unitary graphene monolithic and the unitary graphene matrix composite) has the following characteristics (separately or in combination) that distinguish themselves from PG, HOPG, CVD graphene film, flexible graphite sheets, flexible graphite composite, paper/film/membrane of discrete graphene/GO/RGO sheets/platelets, and conventional graphene/GO/RGO platelet-reinforced resin matrix composite, metal matrix composite, and carbon matrix composites:
(1) This unitary graphene material is an integrated graphene entity that is either a graphene single crystal (single grain only) or a poly-crystal (multiple grains but typically having incomplete grain boundaries or having exceptionally large grains). Typically and preferably, with some compression or shearing stresses exerted on the GO during shaping and subsequent heat treating, the unitary graphene material has all the graphene planes in all the grains being essentially oriented parallel to one another (i.e., the crystallographic c-axis of all grains pointing in an identical direction).
(2) The unitary graphene matrix is an integrated graphene entity that is not an aggregate or stack of multiple discrete graphite flakes or discrete platelets of graphene/GO/RGO, and does not contain any discernible or discrete flake/platelet derived from the original GO gel.
(3) This integrated graphene matrix is not made by bonding discrete flakes/platelets together with a binder or adhesive. Instead, GO molecules in the GO gel are chemically active and live species capable of chemically merging with one another mainly in an edge-to-edge manner (forming 2-D giant graphene molecules), but possibly also with adjacent GO molecules below or above (forming 3-D network of graphene chains). Through joining or forming of covalent bonds with one another, the GO molecules are adhered into an integrated graphene entity (the unitary graphene material), without using any externally added linker or binder molecules or polymers. In the presence of discrete carbon/graphite/graphene filler particles (e.g. carbon black particles, CNTs, and NGPs), the GO molecules are also capable of acting as a binder or adhesive that chemically bonds these carbon/graphite filler particles together to form a strong composite.
(4) This unitary or monolithic graphene matrix (a single crystal or poly-crystal with essentially all graphene planes having an identical crystallographic c-axis) is derived from a GO gel, which is in turn obtained from heavy oxidation of natural graphite or artificial graphite particles originally having multiple graphite crystallites. Prior to being chemically oxidized to become GO gel, these starting or original graphite crystallites have an initial length (La in the crystallographic a-axis direction), initial width (Lb in the b-axis direction), and thickness (Lc in the c-axis direction). The resulting unitary graphene entity typically has a length or width significantly greater than the La and Lb of the original graphite crystallites.
(5) It may be noted that there has been numerous reports on "graphene composites." However, these "graphene composites" make use of discrete pristine graphene sheets, graphene oxide platelets, or reduced graphene oxide platelets as the reinforcement phase, which is dispersed in a matrix material selected from a resin (to form a resin matrix composite), a metal (metal matrix composite), a carbon (carbon matrix composite), a glass (glass matrix composite), or a ceramic (ceramic matrix composite). In these prior art "graphene composites," graphene sheets/platelets are the discrete and dispersed phase, not the matrix phase (i.e., not the continuous phase that bonds and protects the dispersed phase). These discrete graphene sheets/platelets are the dispersed phase bonded and protected by a matrix material, such as a resin, metal, carbon (CVD carbon, amorphous carbon, or polymeric carbon), glass, or ceramic. In stark contrast or completely oppositely, in the presently invented unitary graphene matrix composite, graphene is the matrix material that serves to bond, adhere, and protect the dispersed filler phase, such as CNT and carbon black (CB) particles. CNT or CB particles are dispersed in and protected by the unitary graphene matrix. The graphene matrix is a continuous, unified, or integrated material phase.
The present invention also provides a cost-effective method or process for producing a GO gel-derived unitary graphene entity and the graphene matrix composite on a continuous or roll-to-roll basis.
Another object of the present invention is to provide a cost-effective process for producing a GO-derived graphene monolith or a graphene matrix composite that exhibits a combination of exceptional thermal conductivity, electrical conductivity, mechanical strength, surface hardness, and scratch resistance.
In particular, the present invention provides a fast, scalable process capable of mass-producing unitary or monolithic graphene or graphene matrix composites from a GO gel. Advantageously and surprisingly, conventional mass production techniques, such as die casting, injection molding, compression molding, resin-transfer molding, and extrusion, can be adapted for cost-effectively producing these materials.
This process involves significantly lower heat treatment temperatures as compared with the processes for producing pyrolytic graphite (including HOPG) from either carbonized polymers (e.g. polyimide) or the CVD graphite. The presently invented process is simpler (hence, more reliable), less energy-intensive, and highly scalable.

Process for producing unitary graphene materials


A puzzle kit for assembly into a three dimensional representation of a geographic region includes first pieces that form a first layer, second pieces that form a second layer on top of the first layer, and structure pieces mounted on the first and/or second layers. The first and second layers can include retaining elements for retaining the structure pieces. The retaining elements can take the form of voids. The first layer can include image elements visible through the voids of the second layer, and the image elements can include indicia to match the voids with the structure pieces. The first pieces can include anchoring pieces that are elevated and interlock with the second layer. The structure pieces can be sequentially assembled on the first and/or second layers according to an index. The assembled puzzle can represent a city, and the structure pieces can represent buildings within the city.

The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
U.S. Pat. No. 3,558,136 (McFarland) discloses a double jigsaw puzzle game wherein two opposing players or teams are provided with identically cut and illustrated, but differently colored, pieces of a scene. A playing board is provided which also includes the scene depicted by the assembled playing pieces. Each player starts with one of the opposite edge portions of the scene on the board and attempts to complete a major portion of the scene by placing the pieces properly on the board in advance of his opponent. As a player progresses with the placement of contiguous pieces of the puzzle, he is credited with scores as indicated on certain of the puzzle pieces. Further there is provided a plurality of playing pieces for each player which he may advantageously place on indicated sections of the puzzle scene as such sections are completed by the player. A starting strip is formed along each of two opposite sides of the board, the inner edges of these strips interlocking with puzzle pieces having a complementary configuration.
U.S. Pat. No. 3,682,479 (Miller et al.) discloses a three dimensional puzzle formed of several, similarly or differently colored, stacked layers of interlocked puzzle segments with each layer containing one or more voids through which portions of the layers beneath it and the interior surface of a supporting tray are visible to produce a pleasing visual effect.
U.S. Pat. No, 4,469,331 (Rinker) discloses a three dimensional jigsaw comprised of a plurality of single-layered and multi-layered interlocking puzzle pieces which combine to form, when the puzzle is assembled, a plurality of superimposed, concentric planer layers of differing surface area. When the puzzle is properly assembled, a continuous homogenous pictoral illustration is displayed on the surface of each visable planar layer of the puzzle.

Puzzle with three dimensional representation of geographic area


A combination stationary bicycle and step/stair climber exercise device containing a support surface, at least one exercise biking mechanism mounted to the support surface, at least one stepping mechanism mounted to the support surface, at least one pair of pedals connected to the biking mechanism, at least one pair of steps connected to the stepping mechanism, at least one seat connected to the top of the support surface over the biking mechanism, and at least one pair of handle bars mounted to the support surface for use with at least one of the biking mechanisms and the stepping mechanisms.

Stationary exercise bicycles are one of the leading pieces of workout equipment. Recently, stair/step climbers have become highly popular. Both devices are expensive and heavy. Concurrently, there has been an increasing trend for people to exercise on more than one type of machine, whether in gyms or at home. Consequently, a number of exercise devices can be very costly, and take up a lot of space.
There is then a need to reduce the cost and space requirements associated with having a number of pieces of fitness equipment. One way this can be accomplished is by combining two or more types of exercise devices into one machine. This has a number of advantages: less expensive, space saving, more exercise variety for dollar expenditure, convenience factor for circuit training, and permits joint workouts by more than one person.

Combination stationary bicycle and step/stair climber exercise device


A simple and rapid process for synthesizing (Pb,La)(Nb,Sn,Zr,Ti)O.sub.3 precursor solutions and subsequent ferroelectric thin films and powders of the perovskite phase of these materials has been developed. This process offers advantages over standard methods, including: rapid solution synthesis (<10 minutes), use of commercially available materials, film production under ambient conditions, ease of lanthanum dissolution at high concentrations, and no heating requirements during solution synthesis. For lanthanum-doped ferroelectric materials, the lanthanum source can be added with total synthesis time less than 10 minutes. Films and powders are crystallized at approximately 650.degree. C. and exhibit ferroelectric properties comparable to films and powders produced by other techniques which require higher crystallization temperatures.

The present invention relates generally to the preparation of ferroelectric powders and thin films and more particularly to the preparation of solutionderived (Pb,La) (Nb,Sn,Zr,Ti)O.sub.3 thin films and powders.
Due to their electrical and electromechanical properties, thin films of ferroelectric materials are of great interest for a wide range of applications from nonvolatile random access memories (NVRAMs) to micro-electrical mechanical devices, to integratable capacitors. Ferroelectric materials are those that possess a spontaneous polarization that can be reoriented with an applied electric field. This leads to hysteresis in the polarization-voltage response and is the basis for NVRAM applications. The most widely studied class of ferroelectric thin films is based on the perovskite crystal structure of the lead zirconate titanate Pb(Zr.sub.1-x,Ti.sub.x)O.sub.3 ; PZT! family. Aliovalent cations (aliovalent indicates a dopant that has a different valence than the ion it was replacing, either higher or lower) are typically substituted for the A-site (Pb) and B-site (Zr,Ti) cations to modify the solid-state point defect chemistry and, thus, the electrical properties of the material. Lanthanum, an A-site donor, (La.sup.+3 substitutes for Pb.sup.+2) is used to reduce the coercive (switching voltage) and improve the dielectric constant, and reduced fatigue. Niobium and tin are B-site donor dopants (for example, Nb.sup.5+ substitutes for Ti.sup.4+ or Zr.sup.4+) and are typically used to reduce the coercive (switching) voltage and improve the insulation resistance of PZT thin films (see Tuttle, B. A.; Al-Shareef, H. N.; Warren, W. L.; Raymond, M. V.; Headley, T. J.; Voigt, J. A. Microelectronic Engineering, 1995, 29, 223).
Solution routes are widely used for the production of thin films through spin-cast or dip-coating methodologies. These methods are typically used due to the flexibility in the stoichiometry of precursor solutions, the ease of altering processing variables, cost effectiveness (inexpensive), the reduction of the sintering temperatures, and the integratability with existing semi-conductor processes.
The solution methodologies for the preparation of undoped and doped PZT precursor solutions can be divided into three general categories: metallo-organic decomposition (MOD), solution gelation (sol-gel) or hybrids. Both metallo-organic (MOD) routes which utilize large "soap-like" derivatives and the so-called "sol-gel" routes have been extensively studied.
Vest and Zhu (Ferroelectrics, 1991, 119, 61) describe an MOD process for preparing PZT materials by dissolving lead, zirconium, and titanium precursor compounds in xylene to produce a precursor solution which was then decomposed to subsequently produce the ferroelectric material.
Hampden-Smith, in U.S. Pat. No. 5,308,601 issued on May 3, 1994, also describes an MOD method for making metal oxides at low temperatures. Because of the problems associated with achieving adequate solubility, the method of Hampden-Smith requires synthesis of the starting materials as well as acid modification of all precursors and the addition of water.
The "sol-gel" routes which use 2-methoxyethanol or other "chelating" reagents i.e., the Inverted Mixing Order (IMO) method! typically involve altering the commercially available starting materials through the use of alcohol or acid solvents at elevated temperatures. Sol-gel processing generally suffers from limitations due to the relative solubilities of the various metals salts and metal alkoxides. Furthermore, controlling the stoichiometric ratios of two or more metals or metal oxides using sol-gel processing is complicated by the differing hydrolysis or precipitation rates of the precursors. Therefore, the starting materials are often modified to permit adequate solubility, adding processing steps to the method. These methods generally require synthesis of novel starting materials, relatively long mixing times, and/or heating during preparation of the desired precursor solutions. Furthermore, incorporation of lanthanum cations into the starting solutions is not easily accomplished, especially at higher La contents.
Ramamurthi and Payne (J. Am. Ceram. Soc., 1990, 73, 2547) describe a sol-gel method for making PT and PZT materials using alkoxides and acetates prepared in a methoxyethanol solvent system. The processing requires several hours as well as multiple processing steps to get the metal compounds in solution. These steps include refluxing at elevated temperature and hydrolysis.
Ravindranathan et al. (Ferroelectric Letters, 1990, 12, 29) describe a sol-gel process similar to that of Ramamurthi and Payne for making lead magnesium niobate. They also use methoxyethanol as the solvent system and require heating for several hours as well as hydrolysis of the precursor solution.
Miller et al., in U.S. Pat. No. 5,116,643, issued on May 26, 1992, as well as in U.S. Pat. No. 4,946,710 issued on Aug. 7, 1990, and in U.S. Pat. No. 5,028,455 issued on Jul. 2, 1991, describe a sol-gel method for producing ferroelectric thin films using alcohol and acid solvents in proportions sufficient to ensure equal reaction rates. However, Miller et al. also require heating to drive off the solvent, the addition of further reagents to quench reactivity and the introduction of water to hydrolyze the produced precursors.
Improvements to the preparation of PZT-family materials by these methods would be to reduce the preparation or synthesis time, to prepare the ferroelectric materials using commercially-available starting materials, and to reduce the severity of the preparation conditions, particularly the severity of the heating conditions. Once the precursor solutions have been prepared, either thin films or powders can be prepared by standard methods.

Process for production of solution-derived (Pb,La)(Nb,Sn,Zr,Ti)O.sub.3 thin films and powders


A wireless receiver operating in a wireless communication environment in which a beginning of a packet contains a repetitive sequence. The wireless receiver may compute a variance (example of a measure of variations in the cross correlation values) of cross-correlation values obtained by cross correlating a received signal and a copy of the preamble sequence starting at different time instances. When a valid packet is received, the variance of the values resulting from the cross correlation is high, otherwise the variance is low. As a result packet detection is made robust, and false packet detection due to interference signals is reduced. In an embodiment, the wireless receiver is implemented in the context of WLAN 802.11 a/g network.

1. Field of the Invention
The present invention relates generally to wireless systems, and more specifically to reliable packet detection in a wireless receiver when packets contain a known repetitive sequence.
2. Related Art
A wireless receiver receives packets (communication/data) over a wireless medium. Wireless communication is often performed in an asynchronous fashion, wherein the specific time instances of transmission of packets may not be known apriori. Therefore, a wireless receiver may check the wireless medium for the presence of a valid packet (i.e., perform packet detection), and performs further processing (such as decoding the data in the packet) upon detection of a valid packet. Since interference (generally any signal other than a desired signal) may also be present in the wireless medium it is desirable that packets be detected in a reliable manner even in the presence of such interference.
Packets may be designed to contain known repetitive sequences to aid a wireless receiver in packet detection. For example, packets transmitted according to the 802.11a/g standard contain repeated sequences (known to a potential receiver) in a preamble/header portion at the start of a packet.
A prior wireless receiver performs packet detection by cross correlating a locally stored (in the wireless receiver) preamble with a signal (potentially) present in the wireless medium. Cross correlation entails finding similarity between the local preamble and the received continuous signal starting at different time instances. When the compared signal in the wireless medium represents a preamble contained in a valid packet, a cross-correlation operation produces a result with a large value.
Thus, upon producing a large value, the compared signal is deemed to represent (a specific portion of) the preamble, and the packet is deemed to be detected. The signal portion (in the continuous signal) representing the packet is determined in relation to the compared signal. In particular, the portion following the preamble may be deemed to contain the rest of the packet of interest.
However, the cross correlation operation may also produce a similarly large valued result when the signal in the wireless medium is an interference signal, thereby reducing the reliability of the packet detection operation. The resulting false detections may be undesirable for several reasons, such as reduced effective transmission throughput (as the device may decide not to transmit in view of the 'reception' of packets), unneeded power consumption due to processing of packets, etc.
It is thus generally desirable that packets on a wireless network be reliably detected.
In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.

Reliable packet detection in a wireless receiver when packets contain a known repetitive sequence


A serial data transmission system includes a sending terminal for sending data, a receiving terminal for receiving the data sent by the sending terminal, a first connecting capacitor connected between the sending terminal and the receiving terminal, and a second connected capacitor connected between the sending terminal and the receiving terminal. The sending terminal includes a sending terminal driving unit, and an amplitude detecting unit connected to the sending terminal driving unit. The sending terminal driving unit outputs a pair of differential signals according to signals of the received data. The amplitude detecting unit detects changes in amplitudes of the differential signals outputted by the sending terminal driving unit, and outputs an indicating signal for indicating whether the sending terminal is properly connected to the receiving terminal. A serial data transmission method is further provided.

1. Field of Invention
The present invention relates to data transmission system and method, and more particularly to a serial data transmission system having an amplitude detection unit and a method thereof.
2. Description of Related Arts
In the serial data transmission system, before the high-speed data transmission, the sending terminal of the electronic equipment needs to check whether the receiving terminal of the equivalent is properly connected to the sending terminal of the electronic equipment; the high-speed data transmission is initiated only when the sending terminal of the electronic equipment detects the proper connection to the receiving terminal of the equivalent.
Thus, the sending terminal of the electronic equipment is required to have a detection circuit which is capable of detecting whether the sending terminal of the electronic equipment is properly connected to the receiving terminal. Because the peripheral circuit of the serial data transmission system changes relatively significantly, especially because of the alternating current coupling device and the on-board parasitic circuit of the plate electrode channel and the uncertain impedance of the receiving terminal, in the design of the detection circuit, the system needs a high resistance to interference, precise judgment range and possibly low power consumption, so as to satisfy the future low consumption applications.
Thus, it is necessary to provide an improved serial data transmission system or method to overcome the above defects.

This patent is subject to a terminal disclaimer.

Serial data transmission system and method

IPGoal Microelectronics (Sichuan) Co., Ltd.


A method for making a ferroelectric thin film capacitor. A Ti adhesive layer is formed on a silicon substrate covered with a silicon oxide layer. On this, a Pt film is deposited as a lower capacitor electrode, over which a ferroelectric film of high permittivity, such a crystallized BST film, is deposited by sputtering. Then an upper Pt electrode is deposited over the BST film by sputtering to form a capacitor. Finally, the capacitor is heat-treated in an oxidizing atmosphere to eliminate any leakage holes, that cause leakage current, in the ferroelectric thin film caused by the sputtering.

Along with the high integration of semiconductor devices, the miniaturization of their components has also advanced. For a dynamic random access memory (DRAM), a high-capacity capacitor of very small area is required. Ferroelectric thin films with extremely large relative permittivity have attracted consideration for making such capacitors. As a well-known example, the work of P. J. Bhattacharya et al. is mentioned in Japan J. Appl. Phys., Vol. 32 (1993), pp. 4103-4106.
Bhattacharya et al. understood that when a (Ba, Sr)TiO.sub.3 (hereafter "BST") film was formed on a Pt substrate, the crystals of the film grew in a columnar shape, enabling a high relative permittivity of 300 to be achieved. However, when capacitors were made using this thin film, there were many with a large leakage current and short-circuits in the initial stage, so it was difficult to use them for ultra large scale integration (ULSI) such as DRAM. As a result of reviewing such problems in detail, it became understood that the process for forming an upper electrode was related. When capacitors are formed using these thin films, metallic materials such as Pt are often deposited on the film as an upper electrode by sputtering, electron-beam vapor deposition, etc.
When the upper electrode was formed by these methods, a leakage current was generated through the dielectric film, and it was difficult to use dielectric as a capacitor for DRAM. Accordingly, one object of the invention is to provide a method for making a ferroelectric thin film capacitor in which leakage current is kept small even if the upper electrode is deposited on the ferroelectric dielectric film by sputtering or electron-beam vapor deposition.


A novel polyester film and a process for its preparation are disclosed wherein said film is composed of (a) liquid crystal polyester; (b) non-liquid crystal polyester; and (c) fiberizer capable of substantially fiberizing said liquid crystal polyester (a). Said polyester film shows remarkable improvements in various properties compared with the prior art polyester films: polyester film according to the present invention exhibits: (a) a high modulus of elasticity; (b) a high toughness; (c) a small content of: (1) oligomer, (2) thermal decomposition products and (3) gelation products; and (d) excellent electrical properties, so that this film can be used as a base film for electrical insulating material, capacitors, magnetic recording mediums, etc.

One of commonly practiced methods for enhancing the modulus of elasticity of a polyester film is to enhance the degree of molecular orientation by improving the orientation method or the like. Another method is to reinforce the polyester film by finely dispersing a compound having a high modulus of elasticity such as liquid crystal polyester in a non-liquid crystal polyester as disclosed in JP-A-61-78862 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-B-7-37577 (The term "JP-B" as used herein means an "examined Japanese patent publication") and JP-A-57-25354.
However, if the degree of molecular orientation is excessively raised to enhance the modulus of elasticity of the polyester film, the film is apt to break during the orientation. Thus, the practical enhancement of the modulus of elasticity of a polyester film has been limited.
On the other hand, the foregoing method which comprises finely dispersing a liquid crystal polyester having a high modulus of elasticity in a non-liquid crystal polyester to reinforce the polyester film is apparently effective. However, a typical liquid crystal polyester has a bad compatibility with a non-liquid crystal polyester. Thus, voids can easily be formed around the liquid crystal polyester. In particular, the oriented product of a film comprising a large amount of a liquid crystal polyester incorporated therein has a large amount of voids formed therein, making it impossible to provide a polyester film having a high modulus of elasticity.
It was reported in JP-B-7-37577, etc. that if the liquid crystal polyester to be incorporated in the non-liquid crystal polyester is fibrous, it can provide remarkable enhancement of the modulus of elasticity. A molten liquid crystal polyester which has just been extruded from an extruder which gives a shear rate as high as not less than 200 s.sup.-1 often assumes a fibrous form. However, once given a shearing action at a rate as low as 10 s.sup.-1, e.g., by being passed through a filter, even a fibrous liquid crystal polyester which has just been extruded turns spherical. As a result, the enhancement of the modulus of elasticity cannot be recognized as expected.

Polyester film and process for the preparation thereof


A method includes allowing a right-protected asset to be shared by a first device with a second device while they are within a determinable proximity of one another. Subsequent to the sharing, an option to acquire the right-protected asset is presented to the second device when the first device and the second device are not within the determinable proximity of one another.

Manufacturers protect their product using licensing right, copyright, etc. A violation may occur when a user attempts to use a product without legally obtaining permission from the manufacturer. To avoid the violation, the user has to obtain the permission by purchasing the product from official channels such as, for example, the manufacturers' authorized representatives. The authorized representatives may include dealers or sellers who have agreements with the manufacturers and who receive financial incentives resulting from the sale of the manufacturers' products

Methods and systems for distributing right-protected asset


Digital data acquired from individual cameras and images converted to digitized images are projected onto virtual 3D screens, which can be generated by a computer. This can be realized by way of 3D-accelerated hardware. The images are not, however, projected in 3D. The virtual 3D scenario with the current camera images is projected and presented to the users in 2D. This process makes it possible to use simple cameras (2n) with single lenses. There is no need to use cameras with zoom technology.

The invention pertains to a panoramic viewing system especially in a combat vehicle.
A panoramic viewing system is described in, for example, DE 102 17 177 A1. This direct view system with glass lenses is designed as a panoramic viewing device.
A panoramic viewing system of the applicant is described in detail in Jane's "International Defense Review" of Aug. 1, 2004. This system, which was introduced at an exhibition in Paris, comprises eight commercial cameras with 1 megapixel outputs. The cameras themselves can zoom into the areas which they cover. By means of a computer mouse, the operator can also look at images in the rear without having to turn his head in that direction. In this case, for example, digitally superimposed signatures tell the operator what direction he is looking in at the time. Digital correction, as briefly mentioned, is used to improve the transition when the operator switches his view from one camera to another. No further discussion of the panoramic viewing system is provided.
The company called "United Defense" also offers a panoramic viewing system, which it calls the "Enhanced Situational Awareness System—Eagle Vision™", and which covers a 360° horizontal range. A display is located in the helmet of the operator.
At the Internet site www.octec.com/image processing products/functionality/-mosaic.html, a process is presented by means of which it is possible to connect individual digital images of an individual sensor to each other in such a way that a complete image in the form of a panoramic display is created. No overlaps are visible.
A panoramic monitoring system with a stationary camera is described in DE 694 29 028 T2 (EP 0 610 863 B1), where the device and also an algorithm for transforming individual visual or viewing fields with distorted perspective into several normal images with undistorted perspective are discussed. The device comprises means for controlling the omnidirectional view and for digitizing an incoming or previously recorded video signal, etc.

Panoramic viewing system especially in combat vehicles


Medical devices and methods are used to treat cardiac dysfunction conditions which involve delivery of stimulation pulses in cardiac refractory periods in order to modulate an effective refractory period (ERP). Such devices and methods may be used in conjunction with or in place of other therapies, including increased cardiac contractility (ICC) therapy, post extrasystolic potentiation (PESP) therapy, and other therapies to achieve increased heart contractility, provide a safer and more effective regimen for the corresponding stimulation therapies, and reduce the risk of inducing an arrhythmia.

The present invention relates generally to implantable medical devices. Many embodiments of the invention are directed more particularly to monitoring acute, episodic, or chronic cardiac dysfunction conditions, including heart failure (HF), and/or treating such conditions by providing appropriate therapies.
Congestive heart failure is an extremely serious affliction. Heart failure (HF) is not a specific disease, but rather a compilation of signs and symptoms, all of which are caused by an inability of the heart to appropriately increase cardiac output during exertion. HF may be caused by chronic hypertension, ischemia, tachyarrhythmias, infarct or idiopathic cardiomyopathy. HF has a great impact on the quality of life, as the sympathetic nervous system is placed in a state of hyperexcitablity, leading to a loss of heart rate variability and rate responsive mechanisms in the heart. In turn, the ability of the heart to relax is impaired, resulting in elevated filling pressures, pulmonary congestion, and low exercise tolerance. These are just a few of the side effects.
The treatment of severe cardiac dysfunction and decompensated heart failure may include inotropic drug therapies. Although these therapies may be beneficial in specific settings, they require administration of a drug, often by intravenous route, with systemic side effects and the time-consuming involvement of skilled clinicians. Electrical stimulation therapies are attractive alternatives because implanted or external devices may administer them very shortly after dysfunction appears or worsens and because their actions may be confined to the heart.
Delivering stimulation during the refractory period of the cardiac cycle is a type of therapy generally referred to as increased cardiac contractility (ICC). ICC therapy, used in this manner, has been observed to cause release of catecholamines such as norepinephrine within the tissue of the heart, potentially contributing to an observed increase in contractility of the cardiac tissue, which in turn, results in increased cardiac output, fewer symptoms of heart failure, and improved exertional capacity. Such ICC therapy may also alter calcium influx from the intra-cellular space into the cardiac myocyte, which could increase the amount of calcium available for muscles contraction both directly and through greater SR calcium uptake and subsequent release.
Another type of electrical stimulation can be provided during the nonrefractory period of the cardiac cycle to enhance cardiac function. This type of paired and coupled stimulation of heart tissue results in an additional electrical depolarization and, when appropriately timed, results in post extrasystolic potentiation (PESP). The additional depolarization, coming shortly after a first depolarization, is likely not associated with a sizable mechanical contraction, and results in increased contractility of subsequent cardiac cycles.
As is known, the above-described therapies, ICC and PESP, as well as other therapies, including pacing, cardiac resynchronization therapy (CRT), and defibrillation capability, may be used alone or in certain combinations to treat cardiac dysfunction, including HF. However, designers of prior art systems utilizing such therapies have needed to proceed with caution in order to provide systems that are both safe and effective. Specifically, regimens have been designed to provide one or more of the therapies in a manner that is most beneficial without significant risk of initiating potential arrhythmia. Delivery of electrical stimulation as the heart tissue is becoming non-refractory can trigger a tachyarrhythmia. This is particularly true if multiple high-amplitude pacing pulses are utilized. Therefore, becoming familiar with appropriate timing parameters associated with one or more of these types of therapies has been essential.
What is needed are additional systems and/or methods that utilize the one or more known therapies available for treating cardiac dysfunction, including HF, in manners that further optimize mechanical function or cardiac output, while also further minimizing the limitations of known cardiac dysfunction therapies.

Method of delivering PESP/ICC as well as adjusting the refractory period of the heart


An apparatus extracts a main waveform component and a branch waveform component from a pressure waveform detected by a fuel pressure sensor. The main waveform component is caused by pressure change traveling in a main passage. The branch waveform component is caused by pressure change traveling in a branch passage. The apparatus calculates traveling speeds based on the components. Then, the apparatus estimates a main passage temperature based on a detected value of the fuel temperature sensor, the traveling speeds, the fuel pressure waveform and an average pressure.

Documents 1 to 5 all disclose an apparatus which detects a fuel pressure supplied to an injector by a fuel pressure sensor and detects a fuel pressure waveform that is pressure change caused by fuel injection. The apparatus calculates injection condition based on the fuel pressure waveform. For example, since the fuel pressure waveform begins dropping in response to an initiation of injection, it is possible to calculate an injection start timing by detecting a start timing of the pressure dropping. According to the apparatus, it is possible to control injection condition to a desired condition by carrying out a feedback control on operation of an injector based on the calculated injection condition.
A body of the injectors disclosed in the documents 1 to 5 is formed with a supply inlet, a nozzle hole, and passages. The supply inlet receives fuel delivered from a common rail, which is also known as a pressure accumulation container. The nozzle hole is provided to inject fuel. The passages include a main passage extending from the supply inlet to the nozzle hole and a branch passage which is branched from the main passage. The documents 1 to 5 also disclose a fuel pressure sensor disposed to detect a pressure of fuel in the branch passage. According to the structure, fuel pressure in the main passage first drops at a portion close to the nozzle hole in response to a beginning of injection from the nozzle hole. Then, pressure change travels through the main passage and the branch passage, and then, reaches to the fuel pressure sensor. Therefore, the fuel pressure sensor detects the traveled pressure change as a fuel pressure waveform.
However, a traveling speed of pressure in the main passage and the branch passage varies as a temperature of fuel is changed. As a result, a correlation between the fuel pressure waveform and the injection condition is also varied as a temperature of fuel is changed. For example, a delay time from a beginning of injection to the pressure dropping timing is varied as a temperature of fuel is changed.
In order to reduce influences caused by a fuel temperature, the apparatuses in the documents 1 to 5 has sensors for detecting fuel temperature in the branch passage. The apparatuses tried to calculate the injection condition in an accurate manner by correcting the fuel pressure waveform based injection condition calculating processing based on a fuel temperature detected by the fuel temperature sensor.
Document 1: JP-2010-285887A
Document 2: JP-2010-285889A
Document 3: JP-2010-286280A
Document 4: JP-20114842A
Document 5: JP-2011-1915A


A call to an emergency call center from a device is initiated utilizing a relay service. The device may send a non-voice message to the relay service. The relay service, upon receipt and analysis of the message, may initiate a call to the device. The device, upon receiving the call and determining that the call is from the relay service, may place the call on hold and initiate a call to an emergency call center. Subsequently, the device may establish a multi-party call between the device, the relay service, and the emergency call center. Further, the relay service may maintain multiple communications modes in order to conduct non-voice messages with the device and conduct voice communications with the emergency call center.

In an emergency situation, an individual can call 9-1-1 in order to obtain a quick response. The person can explain the emergency situation to the 9-1-1 call taker, and the 9-1-1 call taker can dispatch appropriate personnel to handle the emergency. This may be difficult, if not impossible, for a person with an impaired physical ability. For example, a person with a hearing impairment and/or speech impairment may not be able to speak to a 9-1-1 call taker to describe the emergency situation.

Initiating a call to an emergency call center via a relay service


This invention relates to a memory device and the like that are preferably applied to a case where motion vector is detected using a block matching. Pixel data of a first frame (a reference frame) is stored in a unit A of memory cell array portion 20a in straight binary format. Pixel data of a second frame (a search frame) is stored in a unit B of memory cell array portion 20b in two's complement format. The units A and B have a plurality of memory cells, respectively. Word lines WL related to the pixel data of the first and second frames are simultaneously activated so that charges accumulated in capacitors of each of the memory cells can be combined along one bit line BL. A/D converter 53 outputs a digital signal (absolute difference value) having a value that corresponds to a total amount of charges. When reading the pixel data, a subtraction and a conversion into the absolute difference value are simultaneously performed.

FIG. 1 shows a configuration example of a conventional memory block 300. This memory block 300 has a memory cell array 310, a storage data input/output port 320, a row address decoder 330, and a control circuit 340.
The memory cell array 310 has, as shown in FIG. 2, a plurality of bit lines BL for transferring data that extends in a row direction, a plurality of word lines WL that extends in a column direction to intersect with a plurality of the bit lines BL perpendicularly, and memory cells ML that are arranged in a matrix and connected to these bit lines BL and word lines WL.
The memory cell ML is of a DRAM structure and has an access transistor T and a capacitor C. The capacitor C has its one end grounded and the other end connected via the access transistor T to the bit line BL. The access transistor T, on the other hand, has its gate connected to a word line WL. Write or read operation to or from this memory cell ML is implemented by activating the word line WL and turning ON the access transistor T as conventionally well known.
The storage data input/output port 320 has a column address decoder 321, an address buffer 322, and an I/O buffer 323. The column address decoder 321 includes an I/O gate (column switch), a sense-amplifier. The column address decoder 321 is supplied with column addresses via the address buffer 322.
In response to the column addresses supplied via the address buffer 322, the column address decoder 321 secures its connection with a plurality of bit lines BL that is connected to a predetermined plurality of column directional memory cells ML in the memory cell array 310, to enable write or read operation of storage data to or from this predetermined column directional memory cells ML through the I/O buffer 323 and the column address decoder 321.
The row address decoder 330, on the other hand, is supplied with row addresses via an address buffer 331. In response to the row addresses supplied via the address buffer 331, the row address decoder 330 activates a word line WL that is connected to predetermined row directional memory cells ML in the memory cell array 310, to enable write or read operation of storage data to or from this predetermined row directional memory cells ML through the I/O buffer 323 and the column address decoder 321.
Further, the control circuit 340 controls operations of these circuits in the memory block 300 based on a control input.
To perform an operation, for example, addition by use of data stored in the above-described memory block 300, augend data and addend data are read sequentially from the memory block 300 and added up by an adder arranged separately from this memory block 300. Therefore, this method of reading the items of data and performing the operations sequentially leads to a disadvantage that a computing speed cannot be increased. Further, since the computing unit is necessary separately from the memory block 300, costs are increased by that much disadvantageously. This holds true also with any other operations such as subtraction.
Further, in image processing, detection of a motion vector is one of the important factors and typically represented by block matching. According to it, with respect to a certain pixel block (reference block) that constitutes part of a certain frame (reference frame), correlation of the reference block and same-shape pixel blocks (candidate blocks) at various positions in a frame (search frame) at a different time point is evaluated and a relative positional shift of the reference block to the candidate block having the highest correlation is regarded as a motion vector in that reference block.
It is to be noted that the search range is an assumed range of the candidate blocks. In evaluation of the correlation, a total sum of absolute difference values of pixel data, for each in-block pixel, between pixels in the reference block and the corresponding pixels in the candidate block, that is, a sum of absolute difference value is used often. Although a sum of absolute difference value of the candidate block in the search range for each reference block is given, the least sum of absolute difference value thereof is regarded as a motion vector that is given in pixel units.
FIG. 3 shows a configuration example of a conventional motion vector detection circuit 200.
This motion vector detection circuit 200 has an input terminal 201 to which an image signal Di of a reference frame is input, a reference frame memory 202 for accumulating this image signal Di of the reference frame, and a search frame memory 203 for accumulating an image signal of a search frame. When the image signal Di of a certain frame is supplied from the input terminal 201 to the frame memory 202 and written in it, an image signal of the immediately preceding frame stored in this frame memory 202 is read and supplied to the frame memory 203 and written in it.
The motion vector detection circuit 200 further has an arithmetic circuit 204 for receiving pixel data of a reference block from the frame memory 202 and pixel data of a plurality of candidate blocks in a search range that corresponds to this reference block from the frame memory 203 to compute and output, for each of the plurality of candidate blocks, an absolute difference value between each of the items of pixel data in these candidate blocks and the pixel data in the reference block.
This arithmetic circuit 204 obtains difference data by adding up, at an addition portion 204b, pixel data of the reference block and two's complement format pixel data of the candidate block converted by a convert-to-two's-complement portion 204a from straight binary format data and by converting this difference data into its absolute value at a convert-to-absolute portion 204c, thereby giving an absolute difference value.
The motion vector detection circuit 200 further has a total-sum-computing portion 205 for obtaining a sum of absolute difference values by accumulating the absolute difference values output from the arithmetic circuit 204 for each of the items of pixel data corresponding to each of the plurality of candidate blocks and an absolute-difference-value-sum-holding portion 206 for holding the sum of the absolute difference values obtained by this total-sum-computing portion 205 for each of the plurality of candidate blocks.
The motion vector detection circuit 200 further has a minimum sum decision portion 207 for detecting a motion vector based on the sum of the absolute difference values held in the absolute-difference-value-sum-holding portion 206 for each of the plurality of candidate blocks, a motion-vector-holding portion 208 for holding the motion vector detected by this minimum sum detection portion 207, and an output terminal 209 for sequentially outputting a motion vector MV of each of the reference blocks held in this motion-vector-holding portion 208. The minimum sum decision portion 207 detects a position of one of the candidate blocks that generates a minimum sum of absolute difference values, as a motion vector.
The following will describe operations of the motion vector detection circuit 200 shown in FIG. 3.
The image signal Di input to the input terminal 201 is supplied to the reference frame memory 202 and accumulated as a reference frame image signal. At the same time, further, an image signal of the immediately preceding frame stored in the frame memory 202 is read and supplied to the frame memory 203 and accumulated as a search frame image signal.
The arithmetic circuit 204 is supplied with image data of a reference block read from the frame memory 202. This arithmetic circuit 204 is further supplied with read pixel data of a plurality of candidate blocks in a search range that corresponds to this reference block. Then, on respective candidate blocks, this arithmetic circuit 204 computes an absolute difference value between the items of pixel data of the plurality of candidate blocks and the items of pixel data of the reference block, for each of the items of the corresponding pixel data, and outputs it.
In such a manner, the absolute difference value output from the arithmetic circuit 204 for each of the items of pixel data corresponding to each of the plurality of candidate blocks is sequentially supplied to the total-sum-computing portion 205, thus obtaining a sum of the absolute values. The sum of the absolute difference values from this total-sum-computing portion 205 for each of the plurality of candidate blocks is supplied to the absolute-difference-value-sum-holding portion 206 and held in it. Based on the sum of the absolute difference values held in the absolute-difference-value-sum-holding portion 206 for each of the plurality of candidate blocks, the minimum sum decision portion 207 detects a position of such one of these candidate blocks as to generate a minimum sum of the absolute difference values as a motion vector, which is held in the motion-vector-holding portion 208.
From the frame memory 202, the arithmetic circuit 204 is supplied with pixel data of the plurality of reference blocks in a reference frame sequentially. Corresponding to the pixel data in each of the reference blocks, pixel data of the plurality of candidate blocks is supplied from the frame memory 203 to the arithmetic circuit 204. Therefore, corresponding to each of the reference blocks, the above operations are repeated by the arithmetic circuit 204, the total-sum-computing portion 205, the absolute-difference-value-sum-holding portion 206, the minimum sum decision portion 207, and the motion-vector-holding portion 208, so that motion vectors in accordance with the reference blocks are detected by the minimum sum detection circuit 207 sequentially and held in the motion-vector-holding portion 208 sequentially.
The motion vectors in accordance with the reference blocks held in the motion-vector-holding portion 208 are read sequentially. These read motion vectors MV are provided to the output terminal 209. The read motion vectors MV are used in motion compensation processing to perform, for example, motion compensation predictive encoding.
A flowchart of FIG. 4 shows a procedure for detecting a motion vector MV in the above-described motion vector detection circuit 200.
First, at step ST21, the process starts and, at step ST22, reads an image signal stored in the reference frame memory 202 and writes this image signal as an image signal of a search frame into the search frame memory 203. At step ST23, the process inputs the image signal Di of a reference frame from the input terminal 201 and writes this image signal to the reference frame memory 202.
Next, at step ST24, the process reads pixel data of a reference block from the reference frame memory 202 and, at step ST25, reads from the search frame memory 203 pixel data of such a candidate block in a search range as to correspond to that reference block and converts this straight binary format data into two's complement format data at the convert-to-two's-complement portion 204a at step ST26.
At step ST27, the process adds up the straight binary format pixel data of the reference block and pixel data of the candidate block converted into the two's complement format data, to obtain difference data. At step ST28, the process converts that difference data into its absolute value, thus generating an absolute difference value between the pixel data of the reference block and that of the candidate block.
Next, at step ST29, the process computes a sum of the absolute difference values between a certain reference block and predetermined candidate blocks at the total-sum-computing portion 205 and stores it in the holding portion 206 at step ST30. At step ST31, the process decides whether generation of the sum of absolute difference values between the certain reference block and every candidate block has ended. If such is not the case, the process returns to step ST25, to shift to processing of generating a sum of absolute difference values between the certain reference block and the next candidate block. Otherwise, the process goes to step ST32.
At step ST32, the process detects a position of a candidate block that generates a minimum sum of the absolute difference values among them, based on the sums of absolute difference values held in the holding portion 206 corresponding to the certain reference block, as a motion vector. At step ST33, the process stores this detected motion vector in the z motion-vector-holding portion 208.
Next, at step ST34, the process decides whether this processing of detecting the motion vector for all of the reference blocks in the reference frame has ended. If such is not the case, the process returns to step ST24, to shift to processing of detecting a motion vector that corresponds to the next reference block. Otherwise, at step ST35, the process sequentially outputs motion vectors MV that respectively correspond to the reference blocks held in the motion-vector-holding portion 208 and, at step ST36, ends the processing.
The above motion vector detection circuit 200 has had a disadvantage of higher costs due to a necessity of the circuits for computing difference data, an absolute value, a total sum, etc. as arithmetic circuits.

Memory device and device and method for detecting motion vector


A vehicle electric drive system includes an internal combustion engine, an electric motor/generator driven by the engine, a first inverter/rectifier coupled to motor/generator, a bus coupled to the first inverter/rectifier, a second inverter/rectifier coupled to the bus, and a traction motor/generator coupled to an output of the second inverter/rectifier, an operator speed control member, and a controller coupled to the second inverter/rectifier for controlling a current output of the second inverter/rectifier as a function of a position of the speed control member. Also included is an operator controlled foot pedal and a transducer coupled to the foot pedal and generating a signal representing foot pedal position which is supplied to the controller. The controller limits current supplied by the second inverter/rectifier to the traction motor/generator to a limit current as a function of the transducer signal. The controller, foot pedal and transducer cooperate to vary the limit current in response to movement of the foot pedal. A spring biases the foot pedal to an upper limit position. The controller causes the second inverter/rectifier to supply to the traction motor/generator a maximum amount of current, (such maximum current being a function of the foot pedal position), but not more than that required to achieve the speed commanded by the speed control.

This invention relates to an electric drive system for a vehicle.
Vehicle electric drive systems or AC electric traction drives have been proposed to overcome some of the deficiencies of mechanical transmission systems, such as a limited number of speeds, increased costs of engineering and manufacturing components, and limiting vehicle configuration options. Such an electric drive system, as shown in U.S. Pat. No. 5,568,023 issued Oct. 22, 1996 to Grayer et al., typically includes an engine-driven 3-phase electric motor/generator coupled to an inverter/rectifier, which, in turn, is coupled to a DC bus. The bus feeds an inverter/rectifier which supplies power to a traction motor/generator which drives an axle or a wheel. The inverter/rectifiers invert the DC current on the bus to 3-phase AC current at a frequency to drive the wheels at the speed directed by the operator. An external power source applied to the tractor through the drive wheels and tending to move the tractor at a speed faster than the requested speed will cause the motors to act as generators and the whole sequence of power conversion will be reversed, regenerating mechanical power back into the engine. This regeneration action causes the engine to absorb power from externally forced loads in a manner similar to that of current mechanical transmissions.
Typically, the speed of the traction motor/generators is controlled by controlling the frequency of the current driving the motor. When the speed control is engaged, the drive will engage with full force or torque authority. Operators of conventional tractors with mechanical transmissions can depress a clutch pedal to release or reduce the torque driving the vehicle. By slowly engaging or disengaging such a mechanical clutch, the operator can control the torque being applied by the engine to move the vehicle. Therefore, by modulating the engagement of the clutch, the operator controls movement of the vehicle by controlling the driving force or torque that the wheels can exert. It would be desirable to have a similar clutch type control capability in an electric drive system.
Accordingly, an object of this invention is to provide a vehicle electric drive system with a control which operates in a manner similar to a clutch control of a conventional mechanical drive vehicle.
These and other objects are achieved by the present invention, wherein a vehicle electric drive system includes an engine driven electric motor/generator, a first inverter/rectifier coupled to motor/generator, a bus coupled to the first inverter/rectifier, a second inverter/rectifier coupled to the bus, and a traction motor/generator coupled to an output of the second inverter/rectifier. Electronic controllers control operation of the inverter/rectifiers in response to an operator speed control member. In addition, an operator controlled foot pedal is coupled to a transducer which generates a limit command signal representing the position of the foot pedal. An electronic control unit receives the limit command signal and limits current supplied by the second inverter/rectifier to the traction motor/generator to a limit current which is a function of the limit command signal and motor speed.

Variable current limit control for vehicle electric drive system


A road information provision system or route search system has a terminal device such as a car navigation device 20a, portable telephone 20b, or PC 20c which specifies routes and issues requests for road information; a VICS center 40 which provides congestion information; a road information provision/route search server 10 which, in response to requests from terminal devices 20a to 20c, generates road information based on congestion information from the VICS center 40, and provides the road information to the terminal devices 20a to 20c; a dedicated circuit network 50 which connects the road information provision server 10 and VICS center 40 by dedicated circuits; a network 30 which connects the terminal devices 20a to 20c and road information provision/route search server 10 to enable communication; and a GPS 60 which provides position information. The system can determine shortest-route information of distance or time and congestion information.

In the prior art, such information as the beginning position and ending position of a congested road interval, the total length of the interval, and the time required to traverse the congested interval from the end to the beginning, has been provided as congestion information to the drivers of automobiles by means of radio broadcasts, photoelectric billboards installed along major arteries, and in addition by means of navigation equipment installed in automobiles.
In recent years in particular, systems (for example, the Vehicle Information and Communication System (VICS) for communication of road traffic information) have been introduced in which vehicle detectors and similar which detect traveling vehicles are installed on roadsides, and the information obtained from such vehicle detectors is analyzed at a center to calculate congested intervals and other information. Drivers can reliably obtain detailed congestion information, such as the beginning position and total length of a congested interval, from such a system.
For example, Japanese Patent Laid-open No. 2002-257561 discloses a congestion information provision system and congestion information provision equipment. In this congestion information provision system, such information as the number of vehicles in transit on each road and the vehicle velocity of vehicles in transit is acquired, and based on this traffic information, the beginning position of a congested interval, the congestion length and other information is calculated, and this traffic information is transmitted by wireless means to users. One such congestion information provision system is the Vehicle Information and Communication System (VICS), in which traffic information is transmitted to users from optical beacons, radio beacons, FM multiplex broadcast antennas, and similar.
As traffic information transmitted to users, in addition to construction information indicating the locations of construction sites, accident information indicating the locations of accident sites, road closure information indicating road closures, and similar, there is also common congestion information, necessary to provide individual congestion information (described below) to users. In particular, this common congestion information comprises such information as road numbers which can specify roads in which congestion has occurred for navigation equipment, the beginning and ending positions of congestion, and congestion quantities (for example, congestion lengths).
On the other hand, in order to receive traffic information provided by the congestion information provision system, user vehicles are equipped with navigation equipment comprising the functions of congestion information provision devices. Here, congestion information provision devices are configured so as to receive traffic information provided by a congestion information provision system via a receiving antenna. As this reception portion, for example, an optical beacon receiver or radio beacon receiver which receives traffic information transmitted from the Vehicle Information and Communication System (VICS) to vehicles, as well as an FM receiver which receives traffic information transmitted to vehicles via FM multiplexed broadcasts, may be used.
Thus by means of conventional congestion information provision system and congestion information provision device, through the reception, by a navigation device comprising functions of a congestion information provision device, of traffic information comprising information on a congested interval through which the vehicle itself is passing from the Vehicle Information and Communication System (VICS), congestion information for individual vehicles can be provided to drivers.
Further, Japanese Patent Laid-open No. 2002-73758 discloses an information provision system which performs route searches. In this information provision system, a management server of the information provision system receives a search request for a route, from a departure point to a destination point, from a terminal over the Internet, performs route search processing, and transmits the search result to the terminal. The management server searches public transportation facilities and performs a route search for movement using public transportation facilities, searches road network information and taxi position information and performs a route search for movement using a taxi, searches road network information and performs a route search for movement using an automobile, and searches pedestrian road information and performs a route search for movement on foot, and combines these search results, to perform a route search from the departure point to the destination point.
By this means, a route search can be performed which combines movement using transportation facilities and movement on foot, based on the search conditions, and this search result can be transmitted to a terminal.

Road information provision server, road information provision system, road information provision method, route search server, route search system, and route search method


A lift-off procedure is provided which enables prevention of damage to a wiring pattern caused by contact of a metal being peeled off from a wafer with a wiring pattern at a time of lift-off procedure. A wafer having a surface on which a pattern is formed which contains a pattern portion to be removed is soaked into a chemical liquid at an angle at which the surface faces downward.

1. Field of the Invention
The present invention relates to a lift-off procedure and lift-off device capable of reducing a failure in wiring in the lift-off procedure being one of wiring forming processes to form a semiconductor device on a wafer.
2. Description of the Related Art
Conventionally, a lift-off procedure is available as one of methods for forming a semiconductor device.
FIG. 10 is a diagram showing configurations of a conventional lift-off device. In a general lift-off device, as shown in FIG. 10, on an exclusive jig such as a wafer chuck 30 is mounted a wafer 31 with a portion where a metal is adhered and a pattern, is formed being faced upward and a chemical liquid is spewed from a chemical liquid nozzle 32 while the wafer substrate 31 is being rotated to remove unwanted metal together with a resist. Thereafter, in order to wash away unwanted metal, a rinsing liquid is spewed from a rinsing liquid nozzle 33 for cleaning.
Additionally, another conventional lift-off device is also available in which a wafer is put into a tank containing a chemical liquid and unwanted metal, together with a resist, is removed while the tank is being shaken.
However, in the case of the above method shown in FIG. 10, since the portion where a metal is adhered on the wafer is faced upward, when the lift-off procedure is performed, a metal portion being removed from a metal face easily comes into contact with a wiring pattern causing a scratch on the wiring pattern. Moreover, if the lift-off procedure is performed with a pattern face being faced upward, a metal in the course of the lift-off procedure comes into contact with the wiring pattern, which causes the wiring pattern to be scratched in some cases. The scratched wiring produces a defective outward appearance and, since a part of the wiring is scraped out, a problem of migration or a like occurs.

Lift-off method and chemical liquid tank