A thermostatic control valve assembly for use in continuously mixing a hot first fluid with a cold second fluid to continuously produce a mixed fluid at a constant temperature. The valve assembly includes an improved baffled mixing dome defining a mixing chamber that facilitates thorough mixing of the hot and cold fluids over a wide range of flow rates. Also included is an improved multiple response thermostat having a fast response rate adjacent to the entrance of the mixing dome for responding quickly to the temperature of fluid entering the mixing dome. The valve assembly further includes a piston/cylinder configuration which covers and uncovers internal passageways to control the mixed fluid temperature. The internal passageways are shaped to cause a non-linear change in the mixed fluid temperature in the mixing dome as the piston moves in the cylinder.

The present invention relates to the field of fluid mixing valve assemblies. More particularly, the invention concerns thermostatically controlled mixing valve assemblies in which a thermostat is immersed in the fluid flowing through the valve.
Thermostatic control valve assemblies are well known in the art and have long been utilized in various applications including group showers, washing stations, hospital hydrotherapy installations and in many industrial applications where precision thermostatic water blending is essential. In order to operate properly, the hot and cold water entering such a valve assembly must be thoroughly blended before the temperature of the mixture is sensed by the thermostat. If the hot and cold water are not adequately mixed, the valve assembly can behave erratically because the temperature sensor sees pockets of hot and cold water instead of a mixture that is at a single temperature throughout. One problem that has long persisted in the art is the inability of most valve assemblies to adequately mix the hot and cold water over a wide range of flow rates. Consequently, multiple valves often have to be used to satisfy flow requirements.
Another problem that has persisted in the art is the physical size of the valve assembly required for a specific application. Often, the valve assembly is simply too large because of the need for a large mixing chamber to adequately mix the hot and cold water. What is needed is a thermostatic control valve assembly having an improved mixing chamber that has the ability to thoroughly mix the hot and cold water over a wide range of flow rates, and which does so in a smaller physical space than valve assemblies currently known in the art.
Still another problem of previously known thermostatic mixing valves is the performance of the mixing valve at low flow conditions. Because inadequate mixing occurs at low flow conditions, the performance of the valve becomes erratic due to the resulting temperature fluctuations. Locating the thermostat further downstream of the valve inlets and mixing ports improves mixing to reduce the erratic tendencies of the valve. However, because the fluid must travel further to reach the thermostat, the response time of the valve increases. Therefore, an improved thermostatic mixing valve is needed which promotes mixing at low flow conditions to reduce erratic tendencies of the valve while still responding quickly to fluid temperature changes.

Thermostatic control valve with fluid mixing and non-linear response characteristics


A red, green, and blue values for a fluid are received. A standard red, green, and blue values for the fluid are determined. A tolerance red, green, and blue values are determined for the fluid based on the standard red, green, and blue value for the fluid. An updated red, green, and blue values for the fluid are received. Whether any of the updated red, green, and blue values for the fluid are outside of the associated tolerance red, green, and blue values for the fluid is determined.

The present invention relates generally to the field of intravenous infusion, and more particularly to a color sensor-based system to alarm block backflow during intravenous (IV) infusion.
Intravenous (IV) therapy delivers fluids directly into a vein. IV therapy can be administered using two approaches: injections and infusions. IV injections typically use a syringe that has a higher pressure than the vein, therefore the pressure difference causes the fluids to flow into the vein. IV infusions use the pressure supplied by gravity to cause the fluids to flow into the vein. IV therapy is the fastest way to deliver medication and fluid replacement throughout the body. Additionally, IV therapy can be sued for fluid volume replacement, to correct electrolyte imbalances, to deliver medications, and/or for blood transfusions.

Alarm for blood backflow during intravenous infusion

International Business Machines Corporation


A device is disclosed for activating and deactivating magnetic electronic article surveillance (EAS) markers, and particularly those EAS markers that are associated with magnetically recorded media. In one embodiment, the device includes control circuitry comprising a coil, such as a solenoid-type coil, that provides a substantially uniform magnetic field that reliably activates and deactivates the marker, yet doesn""t damage the magnetically-recorded media.

The present invention relates to a device for changing the status of a dual status magnetic electronic article surveillance marker.
Magnetic electronic article surveillance (xe2x80x9cEASxe2x80x9d) markers have been used for many years to protect items of value against theft. These EAS markers typically have a signal producing layer made of a low coercive force, high permeability magnetic material, and a continuous or segmented signal blocking layer made of a permanently magnetizable magnetic material. When the signal blocking layer is activated, it effectively prevents the signal producing layer from providing a signal that is detectable by an EAS detection system, and thus the EAS marker is deactivated. When the signal blocking layer is deactivated, then the EAS marker is activated, and an EAS detection system is able to detect the marker. EAS markers that may be activated and deactivated as described are sometimes referred to as xe2x80x9cdual-statusxe2x80x9d markers, to distinguish them from xe2x80x9csingle-statusxe2x80x9d markers that are always activated. Billions of dual-status EAS markers have been sold to date, and they protect assets such as library materials against theft around the world.
The devices used to activate and deactivate magnetic EAS markers are themselves magnetic. That is, they may include an array of magnets or an electric coil that produces a magnetic field of a desired intensity near a working surface, so that the EAS markers may be passed over that surface to selectively activate or deactivate the marker. Unfortunately, some devices used to change the status of a dual-status marker have the potential to harm magnetically-recorded media, such as videotapes. That is, magnetically-recorded media can be erased, garbled, or damaged by the presence of a magnetic field. Thus, when magnetically-recorded media are passed over a device to change the status of an EAS marker attached thereto, the device may damage the magnetically-recorded media. In view of the foregoing, it is desirable to provide a device for deactivating dual-status magnetic EAS markers that will not damage magnetically-recorded media such as videotapes.
Conventional activation and deactivation systems may reliably activate or deactivate EAS markers positioned along the spine of a book, for example, because the position and orientation of the marker relative to the magnetic field is generally known. With a compact disc, the EAS marker is likely to be positioned on the disc itself, and thus may be at any orientation in the X-Y plane relative to the case in which the disc is contained, and thus relative to the applied magnetic field. Conventional devices have compensated for this uncertainty by generating a more intense magnetic field, and although this increases the reliability of activation and deactivation, it can interfere with cathode-ray tubes (CRTs) located in the vicinity of the device. Furthermore, some patrons may perceive a health concern with elevated magnetic fields (whether justified or not), and thus may not wish to use such a conventional activation/deactivation device. Thus it would also be desirable to provide a device that overcomes these concerns.
Attempts have been made in the past to provide a device for changing the status of dual-status magnetic EAS markers without damaging magnetically-recorded media by controlling the intensity of the magnetic field within a short distance of a working surface, so that the marker may be deactivated or reactivated without damage to the magnetically-recorded media. That is, the magnetic field is strong enough at one distance (corresponding to the expected position of the EAS marker) to deactivate the marker, but is not strong enough at a second, greater distance (corresponding to the expected position of the magnetically-recorded media) to damage the magnetically-recorded media. These fields have generally been created using an array of individual magnets, or an open coil. Although this distance-dependent approach has met with some success, it requires the user to locate the EAS marker so that the EAS marker can be passed over the working surface in the intended manner. This normally requires that the magnetically-recorded media be removed from its case or container, which is time-consuming. Also, if for some reason the magnetic field above the working surface is greater than expected or designed, damage to the magnetic media can still result.
In one embodiment, the present invention overcomes these difficulties in the following manner. A magnetic field that is substantially uniform within an area of interest is produced at an intensity that is sufficiently high to reliably activate or deactivate the EAS marker, but sufficiently low to prevent damage to the magnetically-recorded media, such as videotape. Common videotapes, for example, may be damaged when exposed to magnetic fields of approximately 590 Gauss or more, and may show some negative effects when exposed to magnetic fields of 560 Gauss or more. On the other hand, many magnetic EAS markers require a field of approximately 275 Gauss to be reliably activated and deactivated. Accordingly, if a field that is substantially uniform within an area of interest is created, dual-status EAS markers can be reliably activated and deactivated without risking damage to the magnetically-recorded media to which they are attached.
In another aspect, the device of the present invention can be used to reliably change the status of a dual-status EAS marker attached to optically-recorded media such as a compact disc. The inventive device can provide a constant magnetic field within an area of interest that is sufficient to deactivate or reactivate the marker regardless of its orientation in the X and Y direction, while in at least one embodiment minimizing or eliminating any magnetic field effects to which a person is likely to be exposed while using the device.
In one embodiment, the device of the invention selectively produces magnetic fields of different intensity by changing the reactance of the LCR circuit, rather than by changing the voltage. This is more efficient and requires fewer components, thus enabling the electronic package to be smaller.
These and other aspects of the present invention, including the use of radio-frequency identification (xe2x80x9cRFIDxe2x80x9d) tags and interrogators, are described in much greater detail below.

Device for changing the status of dual status magnetic electronic article surveillance markers


A method for controlling injection molding using a neural network in a control device of an injection molding machine. A measurement monitor value is acquired in a measurement step during test injection molding and an injection monitor value is acquired in an injection step. The acquired measurement monitor value is designated as an input term and the injection monitor value is designated as an output term. A prediction function that incorporates the measurement monitor value is then determined using the neural network. A first value corresponding to the injection monitor value is predicted by substituting into the prediction function a measurement monitor value acquired at completion of a measurement step during mass-production injection molding. On the basis of the predicted first value, a second value corresponding to an injection condition is determined. Injection control and pressure maintenance control are then implemented on the basis of the second value corresponding to the injection condition.

The quality of a product obtained in an injection molding machine for producing a product by performing a plasticizing/measurement process (hereinafter referred to as a measurement process) and an injection/pressure maintenance process (hereinafter referred to as an injection process) is dependent on the injection conditions, and it is therefore important that the injection conditions be adjusted so that a satisfactory product is obtained.
The injection conditions include V-P switching control for switching the screw control from speed control to pressure control, and a technique for obtaining a satisfactory product by correcting the V-P switching position is disclosed in JP 2005-335078 A.
The injection conditions during the abovementioned injection molding will be described hereinafter with reference to the graph of FIG. 18 hereof.
In FIG. 18, the horizontal axis indicates the screw position, and the vertical axis indicates the injection pressure or the injection rate.
The reference symbol Ps indicates the curve of the injection pressure when a satisfactory product is obtained, P indicates the curve of the injection pressure in a certain shot, and V1 through V3 indicate lines that show the injection rate.
The screw position when the pressure curve Ps changes to the screw position correction detection pressure Pm is indicated by "A," the screw position when the pressure curve P in a certain shot changes to the screw position correction detection pressure Pm is indicated by "a," and a deviation of α (wherein α=A−a) exists between the two positions.
At this time, the speed of the screw switches from V1 to V2 (or V2 to V3) in the b positions (2 positions) that are offset by an amount equal to α from the B positions (two positions). Speed control is then switched to pressure maintenance control in the c position that is offset by an amount equal to α from the C position.
Since the pressure curve P of a certain shot can be made to imitate the pressure curve P that produces a satisfactory product by correcting the screw position by an amount equal to α, a satisfactory product can also be obtained in the certain shot.
In FIG. 18, the sequence of operations whereby the deviation α is detected after St, which is the starting point of the injection process, and the speed switching point or the speed-pressure maintenance switching point is corrected by an amount equal to the deviation α is performed within the injection process.
In recent high-speed molding methods, approximately 0.1 second elapses from the start St of the injection process to the start c of pressure maintenance control. The sequence of operations described above is difficult to perform in such a short time, and even if these operations could be performed, a high-sensitivity sensor or a control unit capable of performing high-speed computation is necessary, and device costs increase.
In JP 2005-335078 A, only the relationship between the injection pressure and the screw is managed. In this configuration, a satisfactory product becomes difficult to obtain when the temperature of the heating cylinder, the cycle time, and other factors fluctuate. Specifically, multiple fluctuating factors must be considered in order to obtain a satisfactory product.


The present invention provides a process that employs both non-selective flotation and oxidative leaching of the resulting concentrates to recover an increased amount of copper from porphyry copper ores. The non-selective flotation step uses collectors and conditions, such as pH, that are conducive to the strong flotation of sulfide minerals generally. In the oxidative leach, the copper sulfide minerals in the concentrate fraction are oxidized to copper compounds, which are soluble in the leach solution. The oxidative leach includes the use of ammonia and sulfite under agitation leaching conditions to convert the copper sulfide minerals into ammonia soluble forms.

The vast majority of the world's copper resources are in the form of low-grade (e.g., assaying less than about 1% copper) porphyry copper deposits. In porphyry copper deposits, copper occurs primarily as a copper sulfide and in particular chalcopyrite (CuFeS.sub.2) or chalcocite (Cu.sub.2 S). A sulfide is a compound in which a metal, such as copper, is bonded to one or more sulfur atoms. Other copper sulfides include bornite and covellite.
As a result of post-deposition oxidation of chalcopyrite, deposits typically are zoned with the shallower portions containing copper oxides underlain by chalcocite and the deeper portion containing chalcopyrite with little or no copper oxides or chalcocite. An oxide is a compound in which a metal, such as copper, is bonded to one or more oxygen atoms. Copper oxides include chrysocolla, malachite, cuprite and azurite.
Porphyry copper deposits typically contain other types of minerals associated with the copper minerals. For example, porphyry copper deposits typically contain a significant but highly variable amount of other sulfides associated with copper sulfides, particularly pyrite.
Post-deposition oxidation of the deposit causes the ore to have different proportions of chalcocite, chalcopyrite, other sulfides and copper oxides in the shallower portions of the deposit. The high degree of variability in the proportions of the copper sulfides and copper oxides throughout the deposit renders it difficult and costly to selectively mine copper oxides from copper sulfides such as chalcocite and chalcopyrite.
Different techniques are employed to recover copper from chalcocite and chalcopyrite on the one hand and copper oxides on the other. For copper sulfides, flotation processes are widely used to separate copper sulfides from copper oxides and the remaining ore materials, with the copper in the copper sulfides being recovered by smelting. In contrast, ores predominantly containing copper in the form of copper oxides are typically leached by heap leaching techniques to solubilize the copper oxides.
Flotation processes generally separate the copper sulfides from other sulfides and copper oxides by collecting the copper sulfides in the flotation froth. The froth is removed as a concentrate to be treated by a smelter and the residue is removed as tailings for discard. To form the concentrate, air bubbles are passed through a slurry containing ore particles to form the froth containing air bubbles attached to particles having exposed copper sulfide minerals. The necessary hydrophobic properties of the copper sulfide minerals can be established and recovery of copper sulfides obtained by contacting the slurry with a collector. Typically, the collector contains a hydrocarbon radical attached to a polar group. The polar group attaches to the copper sulfide mineral surface and the hydrocarbon radical which attaches to an air bubble. The particles containing exposed copper sulfide minerals attached to a collector are carried upward by the air bubbles to the froth. The particles in the tailings remain in the flotation cell contents for discharge.
The flotation process generally involves a significant loss of copper to the tailings because of the need to produce a concentrate for treatment by a smelter. Smelters generally require concentrates to assay at least 25% copper to obtain acceptable technical and economic results. To produce such a concentrate, the flotation process is usually designed to include in the concentrate only particles containing higher proportions of copper. To realize such a result, selective collectors and specific flotation conditions are used to recover higher grade particles while suppressing the recovery of lower-grade particles that would reduce the concentrate assay to less than 25% copper. Selective collectors preferentially attach to copper sulfide minerals and not to other sulfides. While residence times in the flotation circuit can be reduced to suppress the recovery of lower-grade particles, this can also cause the loss of slower floating, higher-grade particles. Smelter grade requirements higher than 25% would require even more lower grade particles to be discharged in the tailings. In flotation processes, copper losses also result from the inability of the collector to attach to copper oxide minerals.
Copper loss by flotation processes is significant. In 1991, for example, copper flotation plants in the U.S. recovered about 1.19 million metric tons of copper in concentrate fractions with a copper recovery of about 83%, and an estimated loss in the tailings fraction of about 228,100 metric tons of copper. Chilean government-owned copper mining operations recovered approximately 1.055 million metric tons of copper, with approximately 247,200 metric tons estimated to be lost in the tailings fraction. Additional losses of potentially valuable materials are incurred by the discard of pyrite and other sulfides.
There is a need to provide a methodology for selecting a process for recovering copper from copper-containing material that is appropriate for the specific composition of the copper-containing material, especially for materials containing variable amounts of copper sulfides and oxides and other minerals.
There is a need to provide a flotation process that provides increased recovery of copper from copper-containing materials. There is a related need to provide such a process that can be incorporated into existing flotation operations.
There is a need to provide a process that recovers an increased amount of copper in the concentrate fraction. There is a related need to provide a process that recovers the copper in both copper sulfide and copper oxide minerals.
There is a need to provide a process that can economically recover copper from a lower grade material (e.g., ore or hydrometallurgical tailing), which cannot be upgraded to smelter requirements.
There is a need to provide a process that recovers copper from a concentrate fraction by techniques other than smelting.


This invention relates to binary blends of cellulose esters and aliphatic-aromatic copolyesters, cellulose esters and aliphatic polyesters as well as ternary blends of cellulose esters and/or aliphatic polyesters and/or aliphatic-aromatic copolyesters and/or polymeric compounds as well as fibers, nonwovens, molded objects, and films prepared therefrom.

This invention concerns binary blends of cellulose esters with aliphatic polyesters or aliphatic-aromatic copolyesters as well as ternary blends of cellulose esters with aliphatic polyesters and/or aliphatic-aromatic copolyesters and/or other polymers. These resins are useful as molded or extruded plastic objects, fibers, or films. This invention also concerns random aliphatic-aromatic copolyesters which are useful as molded or extruded plastic objects, fibers, or films. Moreover, various additives can be added to the blends or to the random aliphatic-aromatic copolyesters to enhance properties such as water vapor transmission rates or biodegradability. Additionally, the copolyesters of the invention may be formed into a variety of products, especially fibers, such as binder fibers, for nonwovens, textile/industrial yarns and fabrics, composites, laminates and other molded articles.
It is well known that cellulose esters are important as commercial plastics and as fibers. In general, cellulose esters are used in plastic applications where hard but clear plastics are required. For example, cellulose esters are used in tool handles, eyeglass frames, toys, toothbrush handles, and the like. All of these applications require a combination of high melting and glass transition temperatures as well as high modulus and good tensile strength. Formulations based on cellulose esters which provide plastic films with low modulus but good tensile strength while maintaining sufficient melting and glass transition temperatures (Tg) to allow thermal processing are generally unknown. Formulations based on cellulose esters which allow thermal extrusion of fibers are also generally unknown.
Because of the high melt temperatures and low melt stability of many of the cellulose esters, plasticizers such as dioctyl adipate or triphenyl phosphate are often added to the cellulose ester to lower the melt temperatures during melt processing of the polymer. Although this technique is effective, addition of a monomeric plasticizer often creates secondary problems related to volatile or extractable plasticizers such as die drip during melt extrusion or long-term dimensional stability (creep) in an object made from the cellulose ester.
The most basic requirement for polymer-polymer miscibility is that the free energy of mixing be negative (xcex94G less than 0). Although on the surface it would seem that polymer-polymer miscibility would be common, in reality there are only a few known miscible binary blends and even fewer known miscible ternary blend systems (Brannock, G. R.; Paul, D. R., Macromolecules, 23, 5240-5250 (1990)). The discovery of miscible binary or ternary blends is very uncommon.
The classical experimental techniques for determiing polymer blend miscibility involve the determination of the optical clarity of a film made from the blend, measurement of the appropriate mechanical properties, and measurement of the glass transition temperature by an appropriate thermal analysis technique such as dynamic mechanical thermal analysis (DMTA) or differential scanning calorimeter (DSC). If a blend is miscible, films made from the blend will generally be clear. Likewise, mechanical properties of a blend, such as tensile strength or tangent modulus, are often intermediate between those of the blend components. Furthermore, a miscible amorphous blend will show a single Tg intermediate between that of the component homopolymers while an immiscible or partially miscible blend will show multiple Tg""s. In the case of a completely immiscible blend, the Tg""s will be those of the homopolymers. For partially miscible blends, the Tg""s will be intermediate values corresponding to partially miscible phases rich in one of the components. The variation in binary blend Tg can be modeled by the Fox-Flory equation, Tg12=Tg1(W1)+Tg2(W2), where Tg12 is the Tg of the blend, Tg1 and Tg2 are the Tg""s of homopolymers, and W1 and W2 are the weight percent of each component in the blend. Since the Fox equation does not take into account specific interaction between the blend components the Gordon-Taylor equation, Tg12=Tg1+[kW2(Tg2-Tg12)/W1] where k is a constant, is often preferred in blend analysis. For a homogenous, well mixed system, a plot of Tg12 versus W2(Tg2-Tg12)/W1 will yield a straight line the slope of which is equal to k and the ordinate intercept will be equal to Tg1. The constant k is often taken as a measure of secondary interactions between the blend components. When k is equal to one, the Gordon-Taylor equation reduces to a simple weight average of the component Tg""s.
Miscible blends of cellulose esters and other polymers are generally unknown. The most notable exceptions include the work disclosed by Koleske, et al. (U.S. Pat. No. 3,781,381 (1973)), Bogan and Combs (U.S. Pat. No. 3,668,157 (1972)), Waniczek et al., (U.S. Pat. No. 4,506,045 (1985)), and Wingler et al. (U.S. Pat. No. 4,533,397 (1985)). Koleske et al. reported that blends, formed by solution casting of polycaprolactone and cellulose ester mixtures, are miscible. Later work by Hubbell and Cooper (J. Appl. Polym. Sci., 1977, 21, 3035) demonstrated that cellulose acetate butyrate/polycaprolactone blends are in fact immiscible. Bogan and Combs have reported that block copolymers of polyether-polyesters form miscible blends with some cellulose esters. Critical to the invention of Bogan and Combs was the use of an elastomeric block copolymer; they report that the corresponding homopolymeric elastomers were incompatible with cellulose esters. Waniczek et al., have disclosed that polyester carbonate and polyether carbonate copolymers form miscible blends with many cellulose esters and are useful as thermoplastic resins. Wingler et al. report that contact lenses can be prepared from blends consisting of (A) 97-70% by weight of one or more cellulose esters and (B) 3-30% by weight of an aliphatic polymeric compound having ester moieties, carbonate moieties, or both ester and carbonate moieties in the same polymer chain. The invention of Wingler et al. is limited to aliphatic polymeric compounds; no reference is made to random copolymers consisting of aliphatic diacids, aromatic diacids, and suitable diols or polyols. The invention of Wingler is further limited to cellulose mixed esters having a weight percent hydroxyl of 1.2% to 1.95% (DSOH=0.11-0.19 where xe2x80x9cDSxe2x80x9d or xe2x80x9cDS/AGUxe2x80x9d refers to the number of substituents per anhydroglucose unit where the maximum DS/AGU is three). The invention of Wingler et al. is also limited to binary miscible blends and by the composition range of the blends (3-30% aliphatic polymeric compound). No reference is made to blends containing an immiscible component where the immiscible component is useful for enhancing properties such as water vapor transmission rates or biodegradability. Immiscible blends of cellulose esters and aromatic polyesters have also been disclosed by Pollock et al. (U.S. Pat. No. 4,770,931 (1988)) which are useful in applications such as paper substitutes.
One time use, disposable items are common. Examples of such disposable articles include items such as infant diapers, incontinence briefs, sanitary napkins, tampons, bed liners, bedpads, bandages, food bags, agricultural compost sheets, and the like. Examples of other disposable items include razor blade handles, toothbrush handles, disposable syringes, fishing lines, fishing nets, packaging, cups, clamshells, and the like. For disposable items, environmental non-persistence is desirable.
Disposable articles are typified by disposable diapers. A disposable diaper typically has a thin, flexible polyethylene film cover, an absorbent filler as the middle layer, and a porous inner liner which is typically nonwoven polypropylene. The diaper construction also requires tabs or tape for fastening the diaper (typically polypropylene) as well as various elastomers and adhesives. Although the absorbent filler is usually biodegradable or easily dispersed in an aqueous environment, currently neither the outer or inner liner nor the other parts such as the tabs or adhesives will degrade from microbial action. Consequently, disposable absorbent materials such as diapers accumulate in landfills and place enormous pressure on waste systems. Other disposable articles such as plastic bags or plastic compost sheets suffer from similar problems.
Numerous studies have demonstrated that cellulose or cellulose derivatives with a low degree of substitution, i.e., less than one, are biodegradable. Cellulose is degraded in the environment by both anaerobic or aerobic microorganisms. Typical end products of this microbial degradation include cell biomass, methane(anaerobic only), carbon dioxide, water, and other fermentation products. The ultimate end products will depend upon the type of environment as well as the type of microbial population that is present. However, it has been reported that cellulose esters with a DS greater than about one are completely resistant to attack by microorganisms. For example, Stutzenberger and Kahler (J. Appl. Bacteriology, 66, 225 (1986)) have reported that cellulose acetate is extremely recalcitrant to attack by Thermomonospora curvata.
Polyhydroxyalkanoates (PHA), such as polyhydroxybutyrate (PHB), polycaprolactone (PCL), or copolymers of polyhydroxybutyrate and polyhydroxyvalerate (PHBV), have been known for at least twenty years. With the exception of polycaprolactone, they are generally prepared biologically and have been reported to be biodegradable (M. Kunioka et al., Appl. Microbiol. Biotechnol., 30, 569 (1989)).
Polyesters prepared from aliphatic diacids or the corresponding carboxylic ester of lower alcohols and diols have also been reported to be biodegradable. For example, Fields and Rodriguez (xe2x80x9cProceedings of the Third International Biodegradation Symposiumxe2x80x9d, J. M. Sharpley and A. M. Kaplan, Eds., Applied Science, Barking, England, 1976, p. 775) prepared polyesters from C2-C12 diacids coupled with C4-C12 diols and found that many were biodegradable.
Aliphatic polyesters have been used in very few applications mainly because of their low melting points and low glass transition temperatures (generally less than 65xc2x0 C. and xe2x88x9230xc2x0 C., respectively). At room temperature, the physical form of many of the aliphatic polyesters is as a thick, viscous liquid. Therefore, aliphatic polyesters are not expected to be generally useful.
On the other hand, aromatic polyesters, such as poly(ethylene terephthalate), poly(cyclohexanedimethanol terephthalate), poly(ethylene terephthalate-co-isophthalate), and poly(ethylene napthalatate) have proven to be very useful materials. Aromatic polyesters, however, are generally very resistant to biodegradation (J. E. Potts in xe2x80x9cKirk-Othmer Encyclopedia of Chemical Technologyxe2x80x9d, Suppl. Vol, Wiley-Interscience, New York, 1984, pp. 626-668). Block copolyesters containing both aliphatic and aromatic structures have been prepared and have been shown to be biodegradable. Examples of aliphatic-aromatic block copolyester-ethers include the work of Reed and Gilding (Polymer, 22,499 (1981)) using poly(ethylene terephthalate)/poly(ethylene oxide) where these block copolymers were studied and found to be biodegradable in vitro. Tokiwa and Suzuki have investigated block copolyesters such as those derived from poly(caprolactone) and poly(butylene terephthalate) and found them to be degraded by a lipase (J. Appl. Polym. Sci., 26, 441-448 (1981)). Presumably, the biodegradation is dependent upon the aliphatic blocks of the copolyesters; the blocks consisting of aromatic polyester are still resistant to biodegradation. Random aliphatic-aromatic copolyesters have not been investigated in this regard.
While random copolyesters with low levels of aliphatic diacids are known (e.g., Droscher and Horlbeck, Ange. Makromol. Chemie, 128, 203-213(1984)), copolyesters with high levels ( greater than 30%) of aliphatic dicarboxylic components are generally unknown. Copolyesters with as much as 40% aliphatic dicarboxylic acid components have been disclosed in adhesive applications; however, these copolyesters adhesives contain at least two dialcohol components in order to achieve the desired adhesive properties (Cox, A., Meyer, M. F., U.S. Pat. No. 4,966,959 (1990)).
There are many references to the preparation of films from polymers such as polyhydroxybutyrate (PHB). Production of films from PHB generally involves solvent casting principally because PHB polymers tend to remain sticky or tacky for a substantial time after the temperature has dropped below the melting point of the PHB. To circumvent this problem, Martini et al. (U.S. Pat. Nos. 4,826,493 and 4,880,592) teach the practice of co-extruding PHB with a thermoplastic that is non-tacky. Such thermoplastics remain as a permanent layer on the PHB film or may be a sacrificial film which is removed following extrusion.
PHB has also been reported to be useful in the preparation of disposable articles. Potts (U.S. Pat. Nos. 4,372,311 and 4,503,098) has disclosed that water soluble polymers such as poly(ethylene oxide) may be coated with biodegradable water insoluble polymers such as PHB. In these inventions, the PHB layer, which is distinct from the water soluble layer, degrades exposing the water soluble layer which will then disperse in an aqueous environment.
There have been other reports of the preparation of a biodegradable barrier film for use in disposable articles. Comerford et al. (U.S. Pat. No. 3,952,347) have disclosed that finely divided biodegradable materials such as cellulose, starch, carbohydrates, and natural gums may be dispersed in a matrix of nonbiodegradable film forming materials which are resistant to solubility in water. Wielicki (U.S. Pat. No. 3,602,225) teaches the use of barrier films made of plasticized regenerated cellulose films. Comerford (U.S. Pat. No. 3,683,917) teaches the use of a cellulosic material coated with a water repellent material.
There exists in the market place the need for thermoplastics which are useful in molding, fiber, and film applications. For these applications, it is desirable that the thermoplastic blend be processable at a low melt temperature and have a high glass transition temperature. These thermoplastics should not contain volatile or extractable plasticizers. Moreover, there is a need in the marketplace for a biodegradable material for use in disposable articles such as diapers, razors, and the like. As an example, unlike films prepared from polymers such as PHB, the material should be amenable to both solvent casting and melt extrusion. In melt extruding this material, coextrusion with other thermoplastics should not be a requirement. The barrier properties of this new biodegradable material should be adequate so that coating with a water insoluble polymer is not required. The new material should disperse completely in the environment and not require coating with a water-soluble polymer. The mechanical properties of the material should be such that films of low modulus but of high tensile strength can be prepared.
Additionally, it is noted that there exists a need for biodegradable nonwoven articles. Nonwovens are widely used in a variety of products. For example, nonwoven fabrics are suitable for use in hygiene, sanitary and absorbent products, medical/surgical/hospital articles and applications, filter media, wipes, face masks, protective apparel, geotextiles, pressed board and other construction materials, composites, automotive applications, facing and backing materials, scrims, linings, insulation, agricultural fabrics, paint rollers, bedding, tablecloths, napkins, and many other disposable, limited use, durable and recyclable products. High loft nonwoven battings are used in a wide variety of products, including comforters, robe wear, and bra cups. Disposables include wipes, diapers, sanitary napkins and incontinent products. Generally nonwoven fabrics are based on polyester, cellulosic, acrylic, nylon, carbon, glass and other fibers which may be bonded with latex adhesives, binder fibers, scrims and nonwoven binder forms, or polymers in powder form. The bonding of nonwoven fabrics with binder fibers (webs, scrims or adhesive powders) provides a convenient method for making nonwoven fabrics without the need for water- or solvent-based adhesives which are less environmentally friendly. Nonwoven fabrics bonded with binder fibers are economical to produce, and provide a method for making articles, which are unique or superior in performance. Other applications are uses in yarns to increase strength and reduce pilling or linting, as well as in prepregs, preforms and a wide range of engineered composite structures.
Generally, as described in U.S. Pat. Nos. 4,217,426 and 4,419,507, linear, crystalline or partially crystalline polymers have been reported as useful for forming fusible interlining adhesives and in some instances as binder fibers. Indeed, binder fibers and powders made from poly(hexamethylene terephthalate) copolyesters (PHT) have been sold. Such adhesive powders and binder fibers include Eastobond(copyright) FA-300 which was formed from a copolyester having 20 mole % 1,4-butanediol and had a melting point of 125xc2x0 C. as well as Eastobond(copyright) FA-250 which contained 20 mole % isophthalic acid and 20 mole % 1,4-butanediol and had a melting point of 104xc2x0 C.
While previous polyesters and binder fibers may be suitable for certain purposes, such polyesters have not proven effective for applications where elasticity, compostability and/or biodegradability are needed.
The present invention, in part, concerns binary blends of cellulose esters and aliphatic-aromatic copolyesters, cellulose esters and aliphatic polyesters as well as ternary blends of cellulose esters and/or aliphatic polyesters and/or aliphatic-aromatic copolyesters and/or polymeric compounds as well as fibers, molded objects, and films prepared therefrom which have one or more of the above or below described desirable properties. More specifically, the present invention is directed to a blend comprising:
I.
(A) about 5% to about 98% of a C1-C10 ester of cellulose having a DS/AGU of about 1.7 to 3.0 and an inherent viscosity of about 0.2 to about 3.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane, and
(B) about 2% to about 95% of an aliphatic-aromatic copolyester having an inherent viscosity of about 0.2 to about 2.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane, said percentages being based on the weight of component (A) plus component (B);
II.
(A) about 5% to about 98% of a C1-C10 ester of cellulose having a DS/AGU of about 1.7 to 2.75 and an inherent viscosity of about 0.2 to about 3.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane, and
(B) about 2% to about 95% of an aliphatic polyester having an inherent viscosity of about 0.2 to about 2.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane, said percentages being based on the weight of component (A) plus component (B);
III.
(A) about 4% to about 97% of a C1-C10 ester of cellulose having a DS/AGU of about 1.7 to 3.0 and an inherent viscosity of about 0.2 to about 3.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane,
(B) about 2% to about 95% of an aliphatic polyester and/or an aliphatic-aromatic copolyester having an inherent viscosity of about 0.2 to about 2.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane,
(C) about 1% to about 94% of immiscible, partially miscible, or miscible polymeric compounds having an inherent viscosity of about 0.2 to about 2.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts. by weight solution of phenol/tetrachloroethane, said percentages being based on the weight of component (A) plus component (B) plus component (C);
IV.
(A) about 50% to about 99% of a binary blend of (I) or (II) or a ternary blend of (III) having an inherent viscosity of about 0.4 to about 3.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane,
(B) about 1% to about 50% of biodegradable additives, said percentages being based on the weight of component (A) plus component (B);
V.
(A) about 95% to about 99.95% of a binary blend of (I) or (II) or a ternary blend of (III) having an inherent viscosity of about 0.4 to about 3.0 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solution of phenol/tetrachloroethane,
(B) about 0.05% to about 5% of immiscible hydrophobic agent, said percentages being based on the weight of component (A) plus component (B).
The present invention is also directed to:
VI. An essentially linear, random, semicrystalline aliphatic-aromatic copolyester which has an inherent viscosity of about 0.5 to 1.8 deciliters/gram as measured at a temperature of 25xc2x0 C. for a 0.5 g sample in 100 mL of a 60/40 parts by weight solution of phenol/tetrachloroethane and has a melting point between 75xc2x0 C. and 160xc2x0 C.
VII. A mixture of 50 to 99% of (VI) and about 1% to about 50% of biodegradable additives, said percentages being based on the weight of component (VI) plus biodegradable additives.
VIII. A fiber or mixture of fibers prepared from a copolyester having a dicarboxylic acid component and a diol component where the copolyester contains repeat units of the following structures:
In the above formulas R11 and R12 are selected from the group consisting of C2-C12 alkylene, C5-C10 cycloalkylene, C2-C12 oxyalkylene and mixtures thereof, and R11 and R12 are 100% of the diol component. The dicarboxylic acid component contains an aliphatic dicarboxylic acid R13, and an aromatic or cycloaliphatic dicarboxylic acid component R14. R13 is selected from the group consisting of C0-C10 alkylene or C2-C4 oxyalkylene and mixtures thereof and R14 is selected from the group consisting of C6-C12 aryl and C5-C10 cycloaliphatic and mixtures thereof. The mole % of R13 in the copolyester ranges from about 45 to 95% of the dicarboxylic acid component and the mole % of R14 is from about 5 to 55% of the dicarboxylic acid component. The polyester can be formed in the presence of 0 to about 20 mole % of at least one amine compound selected from the group consisting of aminoalcohols, aminoacids, diamines, lactams and mixtures thereof. Such copolyesters preferably have a melting point ranging from about 75xc2x0 C. to about 160xc2x0 C. These copolyester fibers are in a form selected from the group consisting of melt blown, spunbond, spun fibers and combinations thereof.
IX. A composition formed from at least two polyesters with the first polyester being polylactic acid and the second polyester composition formed from a dicarboxylic acid component and a diol component such that the second polyester contains repeat units of the following structures:
In the above formulas R11 and R12 are selected from the group consisting of C2-C12 alkylene, C5-C10 cycloalkylene, C2-C12 oxyalkylene and mixtures thereof, and R11 and R12 are 100% of the diol component. The dicarboxylic acid component of the second copolyester contains an aliphatic dicarboxylic acid R13, and an aromatic or cycloaliphatic dicarboxylic acid component R14. R13 is selected from the group consisting of C0-C10 alkylene, C5-C10 cycloalkylene, or C2-C4 oxyalkylene and mixtures thereof, and R14 is selected from the group consisting of C6-C12 aryl and cycloaliphatic and mixtures thereof. The mole % of R13 ranges from about 45 to 95% of the dicarboxylic acid component and the mole % of R14 is from about 5 to 55% of the dicarboxylic acid component.
The invention answers the problems occuring in previous polyesters and fibers by providing polyesters and fibers having enhanced elasticity properties and improved dyeing properties. The polyesters and fibers of the invention are capable of demonstrating superior thermoplastic flow characteristics while providing good bonding versatility. Furthermore, the polyesters and fibers of the invention can be used alone or they can be formulated as a polymer additive for imparting improved dyeing, finishing and printing properties to other compositions. Indeed, the polyesters of the invention are suitable for use in a wide variety of applications and are especially suitable for bonding cellulosic, polylactic acid (PLA) and other xe2x80x9cgreenxe2x80x9d (biodegradable/compostable) compositions, as well as some superabsorbent polymers (SAP), in hygiene and other absorbent products.

Copolyesters and fibrous materials formed therefrom


A method of forming and a device including an interconnect structure having a unidirectional electrical conductive material is described. The unidirectional conductive material may overlie interconnect materials, and/or may surround interconnect materials, such as by lining the walls and base of a trench and via. The unidirectional conductive material may be configured to conduct electricity in a direction corresponding to a projection to or from a contact point and conductive material overlying the unidirectional conductive material, but have no substantial electrical conductivity in other directions. Moreover, the unidirectional conductive material may be electrically conductive in a direction normal to a surface over which it is formed or in directions along or across a plane, but have no substantial electrical conductivity in other directions. Finally, the unidirectional conductive material may have properties tending to reduce metal diffusion, reduce electron migration, provide adhesion or bonding, and/or act as an etch stop.

Electronic access to and operation of circuit devices (e.g., transistors, resistors, capacitors, and inductors) on a substrate, such as circuit devices on a semiconductor (e.g., silicon) substrate is generally provided by contacts to the devices, and interconnects to the contacts. For example, modern integrated circuits (ICs), including metal oxide semiconductor (MOS) and other transistor devices use conductive contacts and interconnections connected to the individual devices to integrate devices and send and receive signals external to a chip in which the IC is fabricated. In addition, these circuit devices use dielectric layers to isolate the individual devices on a chip from the contacts and interconnects. Therefore, during manufacture or forming of circuit devices, it is generally desired to ensure that conductive materials that make up contacts and interconnects are confined within dielectric layers, and do not diffuse into dielectric layers or electrically conduct to unwanted contacts and interconnects (e.g., such as those within the same metal layer).

Unidirectionally conductive materials for interconnection


A drum, stencil and ink holding member for a stencil printer are disclosed. The stencil is made up of a porous substrate and a thermoplastic resin film. The side of the substrate contacting the film has a surface roughness of 5 .mu.m Rz to 45 .mu.m Rz, preferably 5 .mu.m Rz to 35 .mu.m Rz or more preferably 5 .mu.m Rz to 25 .mu.m Rz.

The present invention relates to a drum and a stencil for use in a stencil printer and, more particularly, to an ink holding member and a stencil for a stencil printer and capable of effectively obviating the transfer of ink from the front of an underlying paper to the rear of an overlying paper.
A digital stencil printer generally includes a thermal head for perforating a thermosensitive stencil in accordance with data representative of a document image. The perforated stencil or master is wrapped around a rotatable drum. The drum is made up of a hollow cylindrical porous support, and an ink holding layer implemented as, e.g., a mesh screen of resin fibers or metal fibers. Ink feeding means is disposed in the drum and feeds ink to the drum. A press roller or similar pressing member presses a paper against the master wrapped around the drum. As a result, the ink is transferred from the drum to the paper via the pores of the drum and the perforations of the master, thereby printing the document image on the paper. The stencil is made up of a thermoplastic resin film (as thin as about 1 .mu.m to 2 .mu.m) and a porous substrate adhered to each other. The porous substrate is implemented by Japanese paper fibers or synthetic fibers or a mixture thereof.
It is a common practice with the above printer to use oil ink or water-in-oil type emulsion ink which is sparingly volatile. This kind of ink obviates defective printings ascribable to evaporation which occurs when the printer is operated after a long interval or after a printing operation. However, such an ink does not dry easily. This brings about a problem that a substantial period of time is necessary for the ink transferred to the paper to infiltrate into the paper and dry to such a degree that it does not run when, e.g., rubbed by finger.
In the stencil printer, papers carrying images thereon, i.e., printings are sequentially stacked on a tray. When the following paper is immediately stacked on the preceding paper existing on the tray, the ink is transferred from the front of the preceding paper to the rear of the following paper due to the short drying time. As a result, the rear of the following paper is smeared by the ink. This kind of smearing, i.e., rear smearing as referred to hereinafter often occurs when the ink transferred to the paper and forming an image is great in amount, particularly when the ink layer on the paper is thick, i.e., high.
Moreover, in the conventional stencil printer, the porous support and ink holding layer of the drum each has pores (bores) greater in size than perforations to be formed in the stencil by the head. Therefore, it is almost impossible to reduce the amount of ink transfer to the paper in order to obviate rear smearing.
In addition, the conventional porous substrate and mesh screen includes many portions which cause the incoming ink to simply flow out without being deflected. In such portions, the ink is transferred to the paper in a great amount and brings about rear smearing.
Japanese Patent Laid-Open Publication Nos. 1-204781 (corresponding to U.S. Pat. No. 4,911,069), 59-218889, and 1-267094, Japanese Patent Publication No. 63-59393, and Japanese Utility Model Publication No. 5-41026 are the prior art appearing to be relevant to the present invention.


An image forming apparatus having: a filter member configured to trap particles floating in the apparatus; a suction section configured to suck air including the particles at a variable suction rate; a determiner configured to determine the suction rate of the suction section; an exhaust path capable of leading the air sucked by the suction section to outside of the apparatus through the filter member; a circulation path capable of allowing the air sucked by the suction section and passing through the filter member to circulate inside the apparatus; a switching member configured to make switches between the exhaust path and the circulation path; and a control unit configured to control at least the suction section and the switching member. The control unit allows the switching member to open the exhaust path only when the suction rate determined by the determiner is equal to or less than a predetermined value.

1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly to a copier, a printer, a facsimile or any other electrophotographic image forming apparatus that transfers a toner image on a recording sheet and thereafter applies heat to the recording sheet for fixation of the toner image thereon.
2. Description of Related Art
An image forming apparatus that forms a toner image on a recording sheet by an electrophotographic process comprises a fixing device configured to apply heat to the recording sheet for fixation of the toner image thereon. It is known that when the fixing device is driven, heat is generated, which causes emanation of a volatile material from rollers and other parts of the fixing device. Further, recently, it has been found that ultrafine particles (particles with diameters not more than about 1000 nm) are generated from the volatile material and discharged from the image forming apparatus.
The ultrafine particles discharged from the image forming apparatus are a tiny amount, and the tiny amount of ultrafine particles themselves cause no particular damage to human health or environments. However, with increasing awareness of environmental issues, it is desirable that such apparatuses are put under emission control to prevent even a tiny amount of emission. Also, it is expected that toner particles become still finer, and it would be necessary to control emission of such toner particles from image forming apparatuses.
For example, Japanese Patent Laid-Open Publication No. 2007-171921 discloses a technical skill to trap exhaust emissions efficiently inside an image forming apparatus. In an image forming apparatus disclosed in Japanese Patent Laid-Open Publication No. 2007-171921, in order to prevent volatile organic compounds generated inside the image forming apparatus from being discharged therefrom, while air is circulated around a fixing device, a filter provided in the circulation path traps the volatile organic compounds.
Japanese Patent Laid-Open Publication No. 2009-151075 discloses an image forming apparatus wherein a circulation path is switchable between an inner circulation path and an outer circulation path for the purpose of dew condensation prevention. The circulation path is switched to the inner circulation path or the outer circulation path, depending on the temperature and the humidity inside and outside the image forming apparatus, and thereby, condensation on an exposure device and contamination of a glass surface by a filter are prevented.
Japanese Patent Laid-Open Publication No. H3-267954 discloses an electrophotographic apparatus wherein while exhaust air from a suction section for sucking and conveying a sheet is circulated inside the apparatus, a filter traps toner, ozone and other matters.
However, as Japanese Patent Laid-Open Publication No. 2007-171921 discusses, circulating the air that has once passed through a filter inside an apparatus is circulating heated air inside an apparatus, which may cause a rise in the temperature inside the apparatus. Also, as Japanese Patent Laid-Open Publication No. 2009-151075 discusses, in a case where the switch of the circulation path between the inner circulation path and the outer circulation path depends on the temperature and the humidity inside and outside the apparatus, relatively large particles such as dust and toner can be trapped.
As concerns ultrafine particles, however, if the discharge speed from the apparatus is too high, the ultrafine particles may pass through the filter and be discharged from the apparatus. Circulating the exhaust air from the suction section inside the apparatus as taught in Japanese Patent Laid-Open Publication No. H3-267954 may cause a problem of a temperature rise inside the apparatus, as in the apparatus disclosed in Japanese Patent Laid-Open Publication No. 2007-171921.
Generally, by heightening the efficiency of removing fine particles by a filter, the trapping efficiency is improved, but the pressure loss becomes higher. In order to address the problem, a greater power source (fan) is necessary, which causes problems in terms of cost, space, energy-saving and noise. With regard to a sheet suction section, lowering the flow rate too much impairs stable sheet conveyance and separation between sheets. Also, with regard to trapping of ultrafine particles, a high flow rate causes ultrafine particles to slip through a filter, which results in a decrease in the trapping efficiency. Thus, in terms of particle trapping efficiency, it is desired that the flow rate is minimized.


An improved sealing element for a facemask and facemasks which include the sealing element are provided. The sealing element may be formed of a flexible material having a durometer value of 60 or less on a Type 000 scale, and the sealing element may have at least three primary external faces including a) a facemask attachment face; b) a skin contact face; and c) a third face. When viewed in cross-section, the skin contact face is the longest of the three faces, and the sealing element is formed into a triangular or trapezoidal cross-sectional configuration during manufacturing. Also when viewed in cross section, the side corresponding to the third face may have a length which is less than 90% of the length of the skin contact face.

Facemasks are used in a variety of context for the purpose of sealing the face, or a portion thereof, from an external environment. A variety of facemask seals are known in the art. An example of a popular facemask seal, and one referred to herein as "a prior art seal" or "the prior art seal" is described below and shown diagrammatically in FIG. 1.
While the prior art seal performs in a satisfactory manner, and is comfortable to a user, leakage can be experienced, particularly in certain areas which are known to be difficult to seal. Such areas include, for example, areas around the nose and the bridge of the nose.


A motor is basically provided with a rotor and a stator. The stator includes a plurality of stacked magnetic entities, a dielectric material disposed between adjacent ones of the magnetic entities, a positive electrode part provided on at least one of the magnetic entities and a negative electrode part provided on at least one of the magnetic entities that does not have the positive electrode part. The positive electrode part is arranged for connecting to a positive side of an external circuit. The negative electrode part arranged for connecting to a negative side of the external circuit.

1. Field of the Invention
The present invention generally relates to a motor having a stator equipped with an integrated capacitor and a motor system incorporating such a motor
2. Background Information
There are situations in which an electric power converting device is used to convert direct current electric power into alternating current electric power and supply the alternating current electric power to an electric motor. Such a conventional electric power converting device requires the use of a capacitor to smooth the voltage. Conventional technology reduces the overall size of a drive apparatus that includes an electric motor and an electric power converting device by providing a dead space inside the motor for a voltage smoothing capacitor. One example of such a drive apparatus is disclosed in Japanese Laid-Open Patent Publication No. 2003-274599.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved motor. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.


In recent years, the telecommunications industry has witnessed the proliferation of a variety of digital vocoders in order to meet bandwidth demands of different wireline and wireless communication systems. The rapid growth in the diversity of networks and the number of users of such networks is increasing the number of instances where two vocoders are placed in tandem to serve a single connection. Such arrangements of low bit-rate codecs can degrade the quality of the transmitted speech. To overcome this problem in the specific situation involving store-and-forward systems (e.g. voicemail), the invention provides a novel method and apparatus including a plurality of different vocoders that can be selectively invoked to process the voice signal so as to reduce signal degradation. Also, the apparatus has the capability to bypass the vocoder bank when exchanging data with a remote signal processor capable of accepting data frames in compressed format.

In recent years, the telecommunications industry has witnessed the proliferation of a variety of digital vocoders in order to meet bandwidth demands of different wireline and wireless communication systems. Vocoders are usually integrated in wireless telephones and base stations of the communication network or a link therefrom. They provide speech compression of a digitized voice signal as well as the reverse transformation. Typically, a voice signal is digitized through one of many quantization techniques. An example of this technique is Pulse Code Modulation (PCM). For the purposes of this description, we will refer to PCM as the input format for the vocoder. Thus a vocoder includes an encoder stage that will accept as input a digitized voice signal and that will output a compressed signal, a possible compression ratio being 8:1. As for the reverse transformation the vocoder is provided with a decoder stage that will accept the compressed speech signal and that will output a digitized signal, such as PCM samples.
The main advantage of compressing speech is that it uses less of the limited available channel bandwidth for transmission. In voice messaging applications, it also minimizes storage memory requirements thereby increasing the number of subscribers that can be served. The main disadvantage is loss of speech quality specially when speech is subjected to multiple instances of vocoders.
The rapid growth in the diversity of networks and the number of users of such networks is increasing the number of instances where two vocoders are placed in tandem to serve a single connection. An example of such a situation is when a wireless user records a message to a voice storage and forwarding device and a wireline terminal then retrieves the message. In such a case, a first encoder is used to compress the speech at the terminal of the wireless user. The compressed speech is transmitted to a base station serving the local wireless terminal where it is decompressed (converted to PCM format samples). The resulting PCM samples are routed to the voice storage and forwarding device where a second encoder is used to compress the input signal for storage in a database. If the person who has access to the voice storage and forwarding device retrieves the message from a wireline terminal, a speech decoder in the voice storage and forwarding device decompresses the stored compressed speech data into PCM format for transmission to the wireline terminal over the PSTN.
The situation is even more complex when the user uses a wireless terminal to retrieve, from a voice storage and forwarding device, a message that was recorded by a wireless terminal user. In such a situation, the compression and decompression of speech occurs three times: once for the wireless terminal/base station combination, a second time in storing and retrieving the message in the voice storage and forwarding device, and finally, a third time in the last base station/wireless terminal combination. Yet other expanding areas of concern are Internet telephony and corporate low bit-rate networks. Indeed, both these types of networks use vocoders as well.
In an attempt to eliminate the condition of vocoder tandeming, a method called "bypass" has been proposed in the past. The basic idea behind this approach is the provision of a digital signal processor including a vocoder and a bypass mechanism that is invoked when the incoming signal is in a format compatible with the vocoder. In use, the digital signal processor associated with the first base station that receives the RF signal from a first wireless terminal determines, through signaling and control, that an identical digital signal processor exists at the second base station associated with the wireless terminal at which the call is directed. The digital signal processor associated with the first base station, rather than converting the compressed speech signals into PCM samples, invokes the bypass mechanism and outputs the compressed speech in the transport network. The compressed speech signal, when arriving at the digital signal processor associated with the second base station is routed such as to bypass the local vocoder. Decompression of the signal occurs only at the second wireless terminal. The "bypass" approach is described in the international application serial number PCT/95CA/00704 dated Dec. 13, 1995. The contents of this disclosure are incorporated herein by reference.
However, the "bypass" solution described above was designed for the base station portion of the telecommunication network. This implies that it is useful only for the tandem situations in which a telecommunication link is established between two wireless users. Also, this solution is only valid for identical vocoders. With the diversity of vocoders quickly increasing, the bypass solution is only valid for a small portion of connections involving tandem vocoding.
Thus, there exists a need in the industry for devices capable of improving voice quality in other situations that involve vocoder tandeming such as in digital voice store-and forward systems.

Method and apparatus for storing and forwarding voice signals


This invention relates to a novel polypeptide involving in the modulation of central nervous system function, circulatory function, immune function, gastrointestinal function, metabolic function, reproductive function, etc., it can be used as a drug for treating or preventing a variety of diseases, e.g. HIV infection or AIDS (acquired immune deficiency syndrome) or the like.

Many hormones and neurotransmitters mediate biological functions through specific receptors present on the cell membrane. Many of these receptors engage themselves in the intracellular transduction of signals through activation of the coupled guanine nucleotide-binding protein (hereinafter sometimes referred to briefly as G protein) and have the common structure comprising 7 transmembrane domains. Therefore, these receptors are collectively referred to as G protein-coupled receptor or 7-transmembrane receptor.
Through the interaction of such hormones or neurotransmitters with G protein-coupled receptors, a variety of regulatory functions of vital importance, for example maintenance of homeostasis, reproduction, development, metabolism and growth, and regulation of the nervous system, circulatory system, immune system, gastrointestinal system and metabolic system are all discharged. While it is known, as mentioned above, that receptor proteins exist for various hormones or neurotransmitters and are playing important roles in the control of vital functions, it is still unknown in many respects whether unknown active substances (hormones or neurotransmitters) and their receptors ever exist or not.
In recent years, by taking advantage of the similarity of such G protein-coupled receptor proteins in partial amino acid sequence, searches for DNAs coding for novel receptor proteins have been undertaken by the polymerase chain reaction technique (abbreviated as PCR) and actually a large number of orphan G protein-coupled receptors, so called because their ligands are unknown, have been cloned to this day (Libert, F., et al., Science, 244, 569-572, 1989; Welch, S. K., et al., Biochem. Biophys. Res. Commun., 209, 606-613, 1995; Marchese, A., et al., Genomics, 23, 609-618, 1994; Marchese, A., Genomics, 29, 335-344, 1995). Furthermore, as the result of random sequencing of genomic DNAs and cDNAs, novel G protein-coupled receptor proteins have been discovered one after another (Nomura, N., et al., DNA Research, vol. 1, 27-35, 1994). The only general means so far available for determining the ligands to such orphan G protein-coupled receptor proteins is a mere estimation based on the similarity in primary structure among G protein-coupled receptor proteins. However, many orphan G protein-coupled receptor proteins have low homology with known receptors and it is, therefore, difficult to estimate their ligands based on the similarity in primary structure alone except in those cases where they are actually subtypes of receptors for known ligands. On the other hand, since many orphan G protein-coupled receptors have been discovered as the result of gene analysis, it is supposed that there still exist many unknown corresponding ligands. However, only in a few cases, ligands have actually been identified for such orphan G protein-coupled receptors.
Recently, investigation for novel opioid peptides by introducing a cDNA coding for a receptor protein which a ligand is unknown, i.e. an orphan G protein-coupled receptor protein, into animal cells have been reported (Reinsheid, R. K. et al., Science, 270, 792-794, 1995, Menular, J.-C., et al., Nature 377, 532-535, 1995). However, in view of similarities to known G protein-coupled receptor proteins and tissue distributions, it could be easily anticipated in these cases that the ligand would be belonging to the family of opioid peptides. The history of research and development in the realm of substances acting on the living body through the opioid receptor dates back to many years ago and various antagonists and agonists have been developed. Therefore, among the compounds artificially synthesized, an agonist of the receptor was picked out and, using it as a probe, expression of the receptor in the receptor cDNA-transfected cells was verified. Then, a search was made for an activator of the intracellular signal transduction which was similar to the agonist, the activator so found was purified, and the structure of the ligand was determined. However, when the homology of an orphan receptor to known G protein-coupled receptor proteins is low, it was very difficult to predict its ligand.
APJ is one of the orphan G protein-coupled receptors so far reported (O'Dowd, B. F., et al., Gene, 436, 355-359, 1993). APJ has low homology with an angiotensin receptor (AT1) but its ligand has remained unknown since no reaction was detected at all with angiotensin II despite the expression of APJ in CHO cells.
Ligands for APJ, which is an orphan G protein-coupled receptor expressed in the central nervous system, circulatory system, reproductive system, immune system, digestive organs and so forth, are expected to be useful as drugs but their structure and functions have not been elucidated as yet.


In apparatus for counting a succession of falling liquid drops having teardrop shape, with a downwardly convex down side, the combination that includes a beam provider for providing a beam of electromagnetic radiation to sidewardly pass into the drop at its convex lower side, to be refracted within the drop to pass out of the drop at its convex lower side, and a beam detector located to detect the refracted beam that has passed sidewardly out of the drop at its convex lower side.

This invention relates generally to counting or sensing of liquid drips, as for example is employed in determining the frequency of drop fall; and more particularly concerns improvements in instrumentation to accurately sense the falling of liquid drops.
Counting of falling drops is useful for many purposes. Among these are liquid flow rate determination, intravenous infusion systems, and others. There is need for enhanced reliability and accuracy of drip or drop counting, or drop fall sensing instrumentation.


An electrical connection is provided for connecting electrically transmitting cables and/or wires to one another or any other component in a manner that provides an environmentally sealed connection. The electrical connection includes an electrical connector for connecting electrical cables or wires that includes seals which are disposed in grooves in the threaded portions of the electrical connector. The electrical connector may also include a second set of grooves separated from the first set of grooves, in order to cause moisture and other debris to migrate away from the seals. When the end connectors of electrical cables or wires are connected to the electrical connector, the interior threads of end connectors cover and deform the surface of the seals to create an enhanced seal between the connector and the end connectors. Thus, the electrical connector effectively seals the interface between the connector and the end connectors of electrical cables or wires, such that moisture and other debris are prevented and/or substantially deterred from migrating into the interior of the cable or wire.

Electrical signal-type distribution cables or wires are used to deliver data transmission services, such as those for telecommunications, cable television and internet, to commercial and residential buildings. These distribution systems are located outside of the buildings and do not directly enter the structures. Rather, the buildings include an internally wired system to distribute the electrical signal or transmission throughout the structure. Thus, there generally is an interconnection between the distribution system bringing the service to the buildings and the internal wiring which transmits the service into and throughout the buildings. Often, this interconnection is outside of the building and, therefore, is exposed to the elements, such as rain, snow, and other forms of moisture and foreign debris.
Likewise, electrical signal-type cables or wires are used to distribute services throughout the interior of commercial and residential buildings. These internal wiring systems often involve interconnections between lengths of cable and other components using electrical connectors, such as splices or splitters, as well as other similar hardware. In some cases, the interconnections may be exposed to high levels of moisture, such as high levels of humidity in buildings located in humid climates or in a basement of a building, and/or foreign debris, such as high levels of dust which may be present in a workshop or similar location. Therefore, under certain circumstances the internal wiring of a building also may be exposed to conditions that would benefit from an environmentally sealed connection.
When the interconnection between the ends of two cables, such as coaxial cable from a service distribution system and a coaxial cable running through the interior of a structure, is located on the outside of the structure or in certain areas within a structure, moisture or other foreign debris, such as dirt or dust, can migrate into the connection and the interior of the cables through the cable connection at an electrical connector, such as an F-connector. The migration of moisture and other debris into the connection and/or the interior of the cables is found to interfere with the integrity of the signal. This interference results from a deterioration of the cable and connector component and the electrical contact between such components.
Prior art electrical connectors have attempted to prevent the migration of moisture and other debris into the connection and the interior of the cables by mounting an o-ring at the ends of the threads of the connector (i.e., against the hexagonal flange of the connector), such that the end connector was intended to form a seal by pressing the o-ring against the flange when it was tightened onto the electrical connector. However, due to manufacturing variations of both the electrical connectors and the end connectors of the electrical cables and wires, the end connector often "bottoms out" before coming into contact with the o-ring or before pressing the o-ring sufficiently against the flange to form an effective seal. Thus, the end connector could not be tightened onto the electrical connector a distance sufficient to use the o-ring to form an environmental seal. In such cases, therefore, the connection between the end connectors of the cables or wires and the electrical connectors was not environmentally sealed and moisture and other debris was free to migrate into the interior of the connection and of the cables or wires, and the interference discussed above was not prevented.


Data transfer between processors is efficiently performed in a multiprocessor including a shared cache memory. Each entry in a tag storage section 220 of a cache memory holds a reference number field 224 in addition to a tag address field 221, a valid field 222, and a dirty field 223. The reference number field 224 is set in a data write, and the value thereof is decremented after each read access. When the value of the reference number field 224 is changed from “1” to “0”, the entry is invalidated without performing a write-back operation. When the cache memory is used for communication between processors in the multiprocessor system, the cache memory functions as a shared FIFO, and used data is automatically deleted.

In multiprocessor systems, data transfer between processors may be necessary in the course of a process. In a multiprocessor system including a shared cache memory, it is considered to perform data transfer through the shared cache memory used as a shared FIFO. As a control technique for the shared cache memory in related art, the MESI protocol having four states, i.e., M (Modified), E (Exclusive), S (Shared), and I (Invalid) is known. More specifically, a need for a write-back to a main memory is allowed to be determined by controlling each cache line to be marked with one of the four states. As related art of this kind, for example, an inclusive shared cache among multiple core-cache clusters with use of the MESI protocol is proposed (for example, refer to PTL 1).

Cache memory and cache memory control unit


In one implementation, a method for causing display of a subset of objects of a data set can including causing a first visual indication to display at a first area of a user interface that a first object is a focal object, causing a second area of the user interface to display a filter applied to the data set, and causing a third area of the user interface to display a subset of objects of the data set based on the focal object and the filter.

Data is ubiquitous. Data creation, storage, and analysis are common operations in information technology ("IT") industry and solutions for facilitating those operations are commonly developed for industry-specific or problem-specific purposes. For example, a database of IT service tickets can be maintained to discover common bugs in a system or a log of security alerts can be searched and/or analyzed to discover a system breach. Often, IT monitoring tools rely on strictly typed models that are populated with many details. One form of data consumption is through data exploration and/or navigation. For example, data sets may be presented in tabular form or aggregated as charts.

Display a subset of objects on a user interface


A disk drive is disclosed comprising a spindle motor having a plurality of windings including at least a first winding, a second winding, and a third winding. During a spin-up operation, a voltage is applied to the first winding and a first rise time is measured for current flowing through the first winding to reach a predetermined threshold. A voltage is applied to the second winding and a second rise time is measured for current flowing through the second winding to reach a predetermined threshold. A voltage is applied to the third winding and a third rise time is measured for current flowing through the third winding to reach a predetermined threshold. A difference is computed in response to the first rise time, the second rise time, and the third rise time, and an angular position of the spindle motor is estimated by computing an arctangent in response to the difference.

1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to a disk drive estimating angular position of spindle motor during spin-up by computing differences in winding current rise times.
2. Description of the Prior Art
FIG. 1 shows a prior art disk drive 2 comprising a disk 4 having a plurality of tracks, a head 6, a voice coil motor 8 for actuating the head 6 radially over the disk 4, and an interface 10 for receiving a primary supply voltage 12 and a secondary supply voltage 14 from a host computer. The disk drive 2 further comprises a multi-phase spindle motor 16 for rotating the disk 4, the multi-phase spindle motor 16 comprising a plurality of windings (e.g., φA, φB, φC), each winding comprising a first end and a second end, the second ends connected together at a center tap 18. A spindle driver 20, responsive to the primary supply voltage 12, commutates the windings over commutation intervals. The spindle motor 16 is shown as comprising three windings (φA, φB, φC) corresponding to three phases. However, any suitable number of windings may be employed to implement any suitable multi-phase spindle motor. Further, any suitable commutation sequence may be employed to commutate the windings. For example, the commutation logic 22 may control switches 23 to commutate the windings of the spindle motor 16 in a two-phase, three-phase, or hybrid two-phase/three-phase commutation sequence.
Disk control circuitry 24 communicates with the host computer over interface 11 and executes various operations (e.g., servo control, read/write channel, etc.) to perform read and write commands. The disk control circuitry 24 generates a control signal 26 and a pulse width modulated (PWM) signal 28 applied to the spindle driver 22. The control signal 26 comprises control information (such as a starting state and a commutation clock), and the PWM signal 28 is used to modulate the driving current in the windings. The windings are connected to a back EMF detector 30 which detects threshold crossings (e.g., zero crossings) in the back EMF voltage generated by the windings with respect to the center tap 18. Since the back EMF voltage is distorted when current is flowing, the spindle driver 20 supplies a control signal 32 to the back EMF detector 30 identifying the "open" winding generating a valid back EMF signal. At each back EMF threshold crossing the back EMF detector 30 toggles a signal to generate a square wave signal 34. The frequency of the back EMF threshold crossings and thus the frequency of the square wave signal 34 represent the speed of the spindle motor 16. The disk control circuitry 24 evaluates the square wave signal 34 and adjusts the PWM signal 28 in order to control the speed of the spindle motor 16.
The disk drive 2 of FIG. 1 further comprises a voice coil motor (VCM) driver 36 responsive to the primary and secondary supply voltages 12 and 14. The VCM driver 36 applies the primary supply voltage 12 to the voice coil motor 8 through driver 37 either in a linear power amplifier mode or in a modulated sequence (e.g., PWM) to control the speed of the voice coil motor 8 while actuating the head 6 radially over the disk 4. The secondary supply voltage 14 powers circuitry within the VCM driver 36 as well as other circuitry within the disk drive 2, such as the spindle driver 20 and disk control circuitry 24. In one embodiment, the primary supply voltage 12 comprises twelve volts and the secondary supply voltage 14 comprises five volts. In an alternative embodiment, the disk drive 2 receives a single supply voltage (e.g., five volts) for driving the VCM 8 and spindle motor 16 and for powering circuitry in the disk drive 2.
When the disk drive 2 is powered on, the disk control circuitry 24 performs a "spin-up" operation to spin the spindle motor 16 up to speed. At low speeds the back EMF voltages generated by the spindle motor 16 do not provide a reliable estimate of velocity. Therefore, the disk control circuitry 24 typically estimates the velocity of the spindle motor 16 during the spin up operation by evaluating the rise times in the winding currents to estimate the angular position of the spindle motor 16 (and taking the derivative to estimate velocity). Once the velocity of the spindle motor 16 exceeds a predetermined threshold, the disk control circuitry 24 switches to the back EMF voltages for estimating the velocity and control the speed of the spindle motor 16 in a closed loop servo system.
It is known to evaluate the winding current rise times to estimate the velocity of the spindle motor 16 during spin-up. For example, U.S. Pat. No. 5,530,326 discloses a technique wherein the primary voltage 12 is applied to each phase of the spindle motor 16 and the corresponding current rise time is measured. Since the inductance of each phase varies depending on the angular position of the rotor with respect to the stator, the relative durations in the winding current rise times for each phase provides a rough estimate of the angular position of the rotor. This rough estimate of angular position can be used to clock the commutation sequence as well as estimate the velocity for switching to back EMF feedback control. For example, the phase which generates the shortest rise time may be energized first since it is considered to be aligned closest with the magnetic fields emanating from the rotor magnets. However, estimating the angular position by finding the shortest winding current rise time provides only a "quadrant" position with a ±30 electrical degree of uncertainty. This uncertainty leads to errors in clocking the commutation sequence and increases the target exit velocity for switching to back EMF control, thereby increasing the overall spin-up time.
U.S. Pat. No. 6,100,656 discloses an inductive sense technique for measuring a more exact angular position of the spindle motor during spin-up by computing sinusoidal components of forward current and reverse current rise times in each phase of the spindle motor. However, measuring the rise time for both a forward current and a reverse current increases the delay required to estimate the angular position of the spindle motor, which degrades performance of the spin-up operation particularly if implemented using a closed loop servo system.
There is, therefore, a need for a simple, relatively fast technique for measuring the angular position of a spindle motor to facilitate a spin-up operation in a disk drive.

Disk drive estimating angular position of spindle motor during spin-up by computing differences in winding current rise times


The present invention provides a filtration control agent and a drilling fluid containing the same. The filtration control agent comprises the product obtained from the reaction of water, lignite, aldehyde and sulfonate polymer at 180-220° C. and the units containing sulfonate groups in the molecular chains of sulfonate polymer are at least 30 wt %. The filtration control agent provided by the present invention features a good filtration loss reduction effect and a low viscosity effect and can improve the rheological behavior of the drilling fluid, thereby meeting the requirements of the drilling of deep wells, ultra-deep wells and ultra high pressure formations.

Polymer filtration control agents can not only effectively control the filtration loss of drilling fluids but also guarantee the performance of the drilling fluids with a normal density (<1.5 g/cm3 in general) and play an important role in drilling operation. However, when they are used in a high density drilling fluid (>1.8 g/cm3 in general) or an ultra high density drilling fluid (>2.5 g/cm3 in general), usually the drilling fluid is thickened and its rheological behavior is worsened due to a high molecular weight and a large viscosity effect.
In an ultra high density drilling fluid, the weight fraction of its weighting material accounts for about 70% of the total weight of the drilling fluid (calculated by taking the drilling fluid with a density of 2.5 g/cm3 prepared from barite with a density of 4.2 g/cm3 for example), while the free water in the system is relatively small, so improper use of the additives that maintain good performance of the drilling fluid may cause rise of viscosity and yield point of the drilling fluid, worsen of the quality of filter cakes and difficulty in controlling filtration loss at high temperature and high pressure. The ultra-low viscosity carboxymethyl cellulose (ultra-low viscosity CMC) and ultra-low viscosity polyanionic cellulose (ultra-low viscosity PAC) filtration control agent currently applied on site may cause quick rise of the viscosity and yield point of an ultra high density drilling fluid and worsen of the rheological behavior of the drilling fluid even if the amount is small. With regard to filtration control agent sulfonated phenolic resin (SMP), viscosity reducer sulfonated lignite (SMC) and sulfonated tannin extract (SMK) as well as their modified products often used on site, when solid content and mineralization are high, usually they must be used in a combined way and the dosage of filtration control agent and/or viscosity reducer must be increased so that they can show an effect. As a result, the cost of the drilling fluid is increased, the rheological behavior is worsened and labor intensity is increased. More importantly, its filtration loss reduction effect is not obvious under the condition of high salt content and high temperature.
Lignite features rich resources and low price. The products made by using it as a basic raw material are often used in drilling fluids. For example, literature "research of the synthesis and performance of heat and salt-resistant filtration control agent SHK-AN" discloses a method for preparing filtration control agent SHK-AN which shows a good effect in temperature and salt resistance and filtration loss reduction, but its synthetic process is complex and the lignite powder needs to undergo oxidative degradation by nitric acid, extraction by alkali and sulfomethylation, the obtained sulfomethyl potassium humate needs to undergo graft polymerization with acrylonitrile obtained after hydrolysis of waste acrylic fiber, and then concentration, drying and pulverization are needed in order to obtain SHK-AN graft copolymer. The research indicates this graft copolymer has a high molecular weight and a large viscosity effect.
Literature "synthesis and evaluation of filtration control agent AMPS/AM/sodium humate" discloses a method for preparing filtration control agent AMPS/AM/sodium humate and specifically discloses that sodium humate is prepared from lignite and the obtained sodium humate is copolymerized with 2-acrylamide-2-sodium methyl-propanesulfonate and acrylamide to obtain filtration control agent AMPS/AM/sodium humate. The filtration control agent has a desirable ability in reducing filtration loss in fresh water, but its salt resistance is poor. Literature "research and application of heat and salt resistant filtration control agent SHK" discloses a method for preparing filtration control agent SHK from lignite and amide derivative as well as complexing agent, cross-linking agent, formaldehyde, soda ash and pyrosulfurous acid. The filtration control agent has high resistance to temperature and salt, strong thinning capacity and good wall building and lubricating properties. However, the maximum density of the drilling fluid using it is 1.97 g/cm3.

Filtration control agent and a drilling fluid containing the same

SINOPEC Research Institute of Petroleum Engineering


A N-level cell memory controlled by the memory controller of the invention have an internal configuration in which the plurality of data input/output terminals connected to the second data bus are separated into first through Mth data input/output terminal groups, such that there is no redundancy in the n bits of data associated with one N-level cell. Together with this, the memory controller separates the plurality of data bits on the first data bus into first through Mth data groups, the ECC circuits generate error-correction codes for each of these data groups, and the first through Mth data groups and first through Mth error correction codes are input to the first through Mth data input/output terminals of the N-level cell memory, via the second data bus.

1. Field of the Invention
This invention relates to a memory controller for a multilevel cell memory, and in particular to a memory controller having an ECC circuit which generates error detection/correction codes and performs an error detection and correction for multilevel cells.
2. Description of the Related Art
Flash memory is coming into widespread use primarily in portable data terminals, portable telephone sets, and other portable information equipment. Flash memory is nonvolatile semiconductor memory, which can retain stored data even if the power supply is turned off, and so is widely adopted mainly in battery-driven portable information equipment.
Trends toward greater functionality and broadband communications in recent years have been accompanied by mounting demand for flash memory with greater storage capacity. In order to satisfy such demands, multilevel-cell flash memory has been proposed. Broadly defined, this multilevel-cell memory is memory in which cells store states with three or more values; normally, in this memory cells store 2n states (where n is an integer greater than or equal to 2). Hence if there are four charge states, two bits of data are stored in a single cell; if there are eight charge states, three bits of data are stored in a single cell; and if there are 2n charge states, then n bits of data are stored in a single cell.
Semiconductor memory such as flash memory has a high per-bit cost, and therefore the use of ECC code, which requires numerous bits, is not suited to flash memory. On the other hand, flash memory is more reliable than hard disks or other storage media, with a defect occurring in at most one cell. Hence many conventional one-bit-cell memory devices adopt as the ECC code a Hamming code, for which correction of up to one-bit errors is possible. This is because, for an ECC code capable of correction of errors in a plurality of bits, the number of bits required to the ECC becomes too great, and there is no need for correction of errors in a plurality of bits. That is, when, as in the case of flash memory, the per-bit cost is high, but reliability is high enough that a defect occurs in at most one bit, a Hamming code enabling correction of up to one bit error using a small number of bits is appropriate as the ECC code.
If a defect occurs in a certain cell of a multilevel cell memory supporting large storage capacity, the n bits of data associated with the defective cell may simultaneously become defective bits. Consequently an error correction code using the above Hamming code capable of correction of up to one-bit errors cannot correct the errors in n bits (where n is two or greater) accompanying a single defective cell, and so a different type of ECC code other than the Hamming code, with a greater number of bits, must be used. For example, a complex ECC code adopted in hard disks might be used. However, such ECC codes with a large number of bits are not suited to flash memory with its high per-bit cost.
In order to address the above problem, it has been proposed, in U.S. Pat. No. 5,754,566, that an ECC circuit be provided in a memory device, that this ECC circuit be designed to separate serial data into a plurality of data words, so that within a data word there is only one bit associated with the n bits of one cell, and that an ECC code be generated for each data word, and stored in an n-bit cell.
However, incorporation of an ECC circuit in a memory device will tend to increase the cost of the memory device, and so is undesirable. Particularly in a system in which are installed a plurality of memory devices, the same ECC circuit is provided redundantly in a plurality of memory devices, driving up the cost of the overall system.

Memory controller for multilevel cell memory