The present invention provides internally damped stators, rotors, and transformers; internally damped cores from which they may be made; and a method of making the aforementioned.

The present invention provides internally damped stators, rotors, and transformers having improved vibration damping performance and the internally damped cores from which they are made.
The internally damped stators are useful, for example, for various electric or magnetic motor applications, specifically electric motors used for disk drive spindle motors and electric motors used for automobiles and power generating equipment. The internally damped stator improves the vibration damping properties of the motor with which it may be used.
The internally damped rotors are useful, for example, for various electric or magnetic motor applications, specifically electric motors used for disk drive spindle motors and electric motors used for automobiles and power generating equipment. The internally damped rotor improves the vibration damping properties of the motor with which it may be used.
The internally damped transformers are useful, for example, for various electric or magnetic applications, specifically power supplies in computers and stereo equipment. The internally damped transformer core improves the vibration damping properties of the transformer in which it may be used.
Methods of making the internally damped cores, stators, rotors, and transformers of the invention are also provided. The preferred method is cost effective and particularly good for manufacturing at high volumes. The internally damped stators, rotors, and transformers can optionally be made in such a manner as to reduce cut and shorted wires.
Periodic or random vibrations or shocks can excite the induction core of a stator, rotor, or transformer to vibrate at its resonant frequencies. These can be problematic due to the resultant formation of undesirable stresses, displacements, fatigue, and sound radiation. Such undesirable vibrations or shocks are typically induced by the interaction of the stator and rotor. The resulting magnetic flux interactions of the stator and rotor can lead to vibration in either of the components.
Flux build-up and flux fields interacting with each other at high rates can lead to a flux field force being applied to the stator or rotor, causing it to vibrate at resonant frequencies resulting in sound radiation, fatigue, and vibrations that can be transmitted to other portions of the motor or items attached to the motor leading to degraded performance (such as in a disk drive where the excessive vibrations transmitted by the stator can cause read and write errors and reduced drive performance) and/or excessive heat build-up from frictional movement. A quiet motor is important to many applications. For example, disk drives often require a motor to operate at less than 30-45 dBA so that when the drive is used in an application, it does not bother the end user of the drive.
Typical stators, rotors, and transformers have many magnetic layers. These layers are stamped or otherwise cut in single individual layers, typically a ring pattern with xe2x80x9cpolesxe2x80x9d extending from the ring. The magnetic layers are stacked by hand or by automated assembly to the desired stack height of the stator, rotor, or transformer. The layers are then joined in a number of ways, such as, for example, by pressing the layers together with a die and using a punch to crimp the layers together, coining, embossing, encasing or coating the outer surfaces of the assembled layers with a rigid non-vibration damping polymeric material (such as an epoxy), applying heat and pressure to form a hydrostatic bond, or combinations of the aforementioned.
Various techniques have been used to reduce vibrational and shock effects (stresses, displacements, etc.) on stators. Three basic techniques include:
1) adding stiffness or mass to the stator so that the resonant modes of the stator are not excited in operation;
2) isolating the stator so that the vibrational or shock energy does not excite other items in the motor construction or items connected to the motor; and
3) damping the stator core by xe2x80x9cpottingxe2x80x9d or encasing the stator core exterior, or portions of the stator core exterior in a polymeric potting material. Typically a polymeric potting material, which optionally may have some damping benefit and/or stiffness benefit, may be used to encase all or a portion of the stator core exterior, thereby reducing the vibration excitation levels and the harmful effects.
Katakura et al., U.S. Pat. No. 5,241,229 discloses a magnetic disc drive motor comprising a hub for carrying magnetic discs on its outer periphery, a drive magnet rigidly fitted to the inner periphery of the hub, a stator core having a coil wound around it and juxtaposed with the drive magnet, and a motor frame having a substantially cylindrical holder for rigidly holding the stator core, wherein the space between the stator core and the motor frame is filled with a resin material. A compact and simply configured magnetic disc drive motor can thus be realized, which is capable of rotating magnetic discs in a very stabilized manner. With such an arrangement, since the space between the stator core and the motor frame, which was not used for any particular purpose, is filled with a resin material, the space within the motor is effectively utilized to enhance the rigidity of the motor frame.
The aforementioned design provides for a stiffer stator thereby reducing some vibration levels. In addition, the resin material can also provide some vibration damping. This design, however, is difficult to manufacture as filling between the poles is difficult. The design can also reduce the heat flow away from the stator increasing the temperature of the windings and creating various problems related to high temperatures of the motor.
This design would also be expensive to manufacture as each stator with windings in place would need to be potted, requiring fixturing, cure ovens, and potential long manufacturing cycles. Variability between stators being potted would be expected as each would have variations due to tolerances of the windings, etc. The potted design would also require a significant amount of organic resin material to be used inside the motor and disk drive assembly. The organic resin material would be largely exposed to the internal motor and drive atmosphere which could lead to outgassing concerns when the drive operates at elevated temperatures (typically greater than 45xc2x0 C., most typically greater than 60xc2x0 C.). The outgassing could lead to corrosion or outgassed material build-up on various parts inside the motor or drive, such as on a disk, read/write heads and other exposed surfaces leading to drive performance reductions or drive failure.
Von Der Heide, et al., U.S. Pat. No. 4,647,803 discloses an electric motor with a substantially cylindrical air gap between the stator and the rotor, the stator being fitted to a bearing support for the rotor shaft bearing. In order to reduce noise emissions, the stator is connected to the bearing support by means of an elastic damper and the stator and bearing support are separated from one another by an air gap adjacent at least part of their facing faces. This design adds damping and isolation, but would be costly to manufacture and also requires additional manufacturing steps to make the motor and precise alignments of parts.
Maughan et al., U.S. Pat. No. 5,365,388 discloses a disk drive that has a stator positioner disposed on a shoulder of a drive shaft housing which is part of a spicule. The positioner secures the stator against movement and references the motor to the spicule which engages and guides the cartridge. An open cell urethane gasket between the printed circuit board and the stator absorbs vibrational forces. This design offers isolation, but does not offer direct damping of the stator, thus its overall effectiveness is limited.
Dunfield et at., U.S. Pat. No. 5,619,389 discloses a spindle motor for rotating at least one disc in a data storage device which includes a base, a shaft, a rotor and a stator. According to the patent a bearing interconnects the rotor with the shaft and allows the rotor to rotate about the shaft. A resilient coupling, such has an O-ring, is compressed between the stator and the base to mechanically isolate the stator from the base and thereby reduce the generation of acoustic noise in the storage device.
The paper appearing in the Journal of the Institution of Engineers, Singapore. Vol. 32 No. 1 February 1992 entitled xe2x80x9cSome Aspects of Spindle Motors for Computer Disk Drivesxe2x80x9d provides an overview of disk drive motor design.
U.S. Pat. No. 5,283,491 entitled, xe2x80x9cAir Bearing Motor Assembly for Magnetic Recording Systemsxe2x80x9d discloses an air bearing motor design. The patent demonstrates that even newer state of the art motors can benefit from an improved method of damping the stator and that prior art methods of damping the stator or isolating the stator have significant performance and manufacturing issues that need to be resolved.
All of the above techniques have drawbacks such as high manufacturing costs, excessive heat retention, significant added mass, difficult assembly procedures for winding wire around the stator core, significant new equipment investment, and high dimensional tolerance design. The aforementioned designs also may not be useful for very high volume motors for disk drives where volumes can be on the order of 1-10 million units a month.
The present invention provides in one embodiment an internally damped core, wherein the core is selected from the group consisting of stator, rotor, and transformer cores.
The present invention provides in another embodiment an internally damped core having at least one inner layer of vibration damping material comprising a viscoelastic material contained therein, wherein the core is selected from the group consisting of stator, rotor and transformer cores.
The present invention provides in another embodiment an internally damped core, wherein the internally damped core comprises a laminate comprising:
(a) two outer magnetic layers;
(b) an inner layer of vibration damping material comprising a viscoelastic material positioned between the two outer magnetic layers;
wherein the core is selected from the group consisting of stator, rotor and transformer cores.
The present invention provides in another embodiment an internally damped core, wherein the internally damped core comprises a laminate comprising:
(a) two outer magnetic layers;
(b) at least two inner vibration damping material layers comprising a viscoelastic material positioned between the two outer magnetic layers;
(c) at least one magnetic layer positioned interior to the outer magnetic layers;
wherein the core is selected from the group consisting of stator, rotor, and transformer cores.
The present invention provides in another embodiment the internally damped core wherein each vibration damping material layer is positioned between two magnetic layers.
The present invention provides in another embodiment the core wherein each magnetic layer comprises a ring having poles extending therefrom.
The present invention provides in another embodiment the core wherein each ring has at least 4 poles extending therefrom.
The present invention provides in another embodiment the core wherein each ring has at least 8 poles extending therefrom.
The present invention provides in another embodiment an internally damped stator comprising the core, wherein the core is a stator core, and wire wrapped around the poles of the core.
The present invention provides in another embodiment an internally damped rotor comprising the core, wherein the core is a rotor core, and wire wrapped around the core.
The present invention provides in another embodiment an internally damped transformer comprising the core, wherein the core is a transformer core, and wire wrapped around the core.
The present invention provides in another embodiment the core wherein the vibration damping material further comprises a thermally conductive additive.
The present invention provides in another embodiment the core wherein the vibration damping material further comprises a magnetic additive.
The present invention provides in another embodiment the core wherein the magnetic layers are non-oriented.
The present invention provides in another embodiment the core wherein the core has edges and wherein the edges are rounded.
The present invention provides in another embodiment the core wherein the core comprises at last 8 magnetic layers and at least 7 vibration damping material layers.
The present invention provides in another embodiment the core which comprises at least 20 magnetic layers and at least 19 vibration damping material layers.
The present invention provides in another embodiment an alternator having the stator installed therein.
The present invention provides in another embodiment a motor having the stator installed therein.
The present invention provides in another embodiment a motor having the rotor installed therein.
The present invention provides in another embodiment a method of making an internally damped core comprising the steps of:
(a) providing a first laminate section and a second laminate section, wherein the first laminate section is formed by a method comprising the steps of
(i) preparing a first laminate comprising a magnetic layer and a layer of vibration damping material bonded thereto; and
(ii) cutting the first laminate section from the first laminate, the first laminate section having a shape; and
wherein the second laminate section is formed by a method comprising the steps of
(i) preparing a second laminate comprising
(A) a first outer magnetic layer;
(B) a second outer magnetic layer; and
(C) a layer of vibration damping material positioned between the outer magnetic layers;
(ii) cutting the second laminate section from the second laminate,
wherein the second laminate section has shape which is substantially the same (typically the same) as the shape of the first laminate section, wherein the second magnetic layer of the second laminate section has a burr thereon caused by the cutting;
(b) joining the first laminate section and the second laminate section to form a core in such a manner that the burr is not on the outside of the core; wherein the core is selected from the group consisting of stator cores, rotor cores and transformer cores.
The present invention provides in another embodiment a method of making an internally damped core comprising the steps of
(a) providing at least two laminate sections, wherein each laminate section is independently selected from the group consisting of first laminate sections and second laminate sections; and
xe2x80x83wherein each first laminate section is independently formed by a method comprising the steps of
(i) preparing a first laminate comprising a magnetic layer and a layer of vibration damping material bonded thereto; and
(ii) cutting a first laminate section from the first laminate, the first laminate section having a shape; and
xe2x80x83wherein each second laminate section is independently formed by a method comprising the steps of
(i) preparing a second laminate comprising
(A) a first outer magnetic layer;
(B) a second outer magnetic layer, and
(C) a layer of vibration damping material positioned between the two outer magnetic layers;
(ii) cutting the second laminate section from the second laminate, wherein the second laminate section has a shape which is substantially the same (typically the same) as the shape of the first laminate section, and wherein the second magnetic layer of the second laminate section has a burr thereon caused by the cutting;
(b) joining the laminate sections together to form a core in such a manner that no exposed burr is present on the core; wherein the core is selected from the group consisting of stator cores, rotor cores and transformer cores.
The present invention provides in another embodiment a method wherein the laminate sections are joined via vibration damping material.
The present invention provides in another embodiment a method wherein the core has edges and wherein the edges are rounded.
The present invention provides in another embodiment a method which further comprises the step of winding wire around the core.
The present invention provides in another embodiment a method wherein the laminate sections are joined via vibration damping material.
The present invention provides in another embodiment the internally damped core made according to a method of the invention.

Internally damped stator, rotor, and transformer and a method of making


Techniques for tight pitch patterning are provided. In one aspect, a patterning method includes: forming mandrels on a substrate; forming spacers that are undoped alongside the mandrels, wherein gaps are present between the spacers; filling the gaps with a sacrificial material having a dopant; forming a mask having an opening marking a cut region of at least one of the spacers; removing the sacrificial material from the cut region of the at least one spacer via the mask; removing the mask; performing an anneal to diffuse the dopant from the sacrificial material into the spacers to form doped spacers, wherein following the anneal the cut region of the at least one spacer remains undoped; removing the cut region of the at least one spacer selective to the doped spacers; and patterning features in the substrate using the doped spacers as a hardmask. A patterning structure is also provided.

Tight pitch patterning has become increasingly essential in semiconductor fabrication. To ease patterning challenges, forming lines everywhere followed by cutting the lines into desired segments has become a primary approach. This approach of forming long lines followed by a cut has been widely adopted, for example, in front-end-of-line (FEOL) processing (fin cut, gate cut), in middle-of-line (MOL) processing (contact cut), and in back-end-of-line (BEOL) processing (metal line or narrow dielectric line cut).
In the ideal case, the cutting opening is perfectly aligned to the underlying lines. Unfortunately, however, due to the inherent variations in lithography overlay (OL) and critical dimension (CD), it is difficult to print the cut openings precisely. If the cut opening is too large, it may result in the undesired cutting of adjacent lines (i.e., excessive cut). On the other hand, if the cut opening is too small, it may undesirably result in incomplete cutting of the line (i.e., incomplete cut). Both an excessive cut and an incomplete cut cause chip yield issues.
Therefore, there is a need for improved tight pitch patterning techniques.

International Business Machines Corporation


The dispenser has a rotary dispenser roller mounted on a reservoir with a telescoping handle. The dispensing head preferably has a valve in its supply channel to control and stop dispensing of cream, lotion, gel or liquid fluids for application to the body surfaces. The dispensing head is angled to conveniently apply fluids to most body surfaces. The dispensing head may carry tools thereon for working with the dispensed fluids.

Body lotions, creams and other fluids are often applied by simple dispensing from a container onto the user's hands, and then the user distributes it over the body. The fluid material is applied to the body, as required, in accordance with the character of the fluid material and its function.
It is desirable to have an improved system wherein a rotary dispenser applies the fluid material to the surface. In addition, in order to aid in the distribution of the fluid over parts of the body which are more difficult to reach, an extended handle is provided. Thus, improved distribution is achieved.

Rotary dispenser with extended handle for cream, lotion, gel or liquid


Medication errors happen frequently in hospital, home, and pharmacy environments. A medication verification and dispensing system provides protection against such errors. The apparatus includes a guide tube that receives a medication and imaging device(s) adjacent to the guide tube that take image(s) of the medication. The imaging devices(s) and light source(s) are oriented for capturing images that reveal markings, color, size, shape, etc., of the medication. A verification system uses a signature of the image to identify the medication or compares the image(s) to reference images to identify the medication and to a prescription record of the patient to ensure it is a correct medication, dose, amount, timing, etc., for administration. If the medication is correct, it is dispensed into a dispensing vessel that locks the medication inside, but unlocks when it recognizes a unique patient identifier worn by a patient that is a correct recipient for the medication.

This invention relates generally to an apparatus and method for verifying and dispensing medication.
Medication errors cause at least one death every day in the United States and injure approximately 1.3 million people annually. A Food and Drug Administration (FDA) study of fatal medication errors found that the most common errors involving medications were related to the administration of an improper dose of medicine (41%) and administration of the wrong medication (14%). Almost half of the fatal medication errors occurred in people over the age of 60, who often take multiple prescription medications. Such medication errors continue to occur despite federal regulations implemented in 1995 that require imprinting of identification codes on all medication solid oral-dosage forms.
The task of administering medications to a patient in a hospital or nursing home environment remains a manual process with limited quality assurance and that is highly subject to human error. Typically, a nurse reads a patient's prescription, opens a bottle of pills with the intended medication, places the pills in a small unlabeled plastic cup, carries the cup to the patient's bedside, and directs the patient to take the pills in the cup. There is no independent quality assurance process to confirm 1) that the correct medication and number of pills are placed in the plastic cup, 2) that the medications are delivered to the correct patient, or 3) that the medication is being administered at the correct time (e.g., not more than every 4 hours).
Patients in the home environment shoulder a substantial amount of responsibility in managing their own medications which can result in medication errors. Common errors in the home include taking the wrong dosage or quantity of pills, forgetting to take certain medications or doses, taking the medication at the wrong time, too many times a day, or not enough times a day, among other problems. For patients taking multiple medications a day or having medication regimes involving complex timing and administration factors, careful day-to-day management of their medications can become quite difficult.
Errors in medications can also arise in the pharmacy environment. Filled prescriptions can be mislabeled with the incorrect dosage or amount of pills, or with the incorrect medication. Pharmacists can dispense the wrong drug, quantity, or dosage, which are mistakes that can result in serious injury or even death of the patient. Pharmacists can make these types of mistakes as a result of being overworked or distracted, or even due to confusion between medication names that are similar, or pills that have similar physical appearances.
What is needed are an apparatus and method for verifying and/or dispensing medication in a manner that that identifies the medication and/or ensures the correct medication, dosage, and number of pills are provided to/taken by the proper individual at the appropriate administration time.


Systems in accordance with embodiments of the present invention can include an adapter having a sliding portion (a slider) slidable to expose an interface, thereby allowing mating—for example, between a test port and a DUT—to be observed and adjusted as required. The slider is removable, allowing an adapter sex change. In one embodiment, an insertion tool is provided which can hold a dual male pin and allow installation and removal of the dual male pin while assisting mating alignment. After calibration, the slider can be locked in place and the adapter can function as a standard coaxial connector.

A coaxial connector used as a test port of a test system (e.g., a vector network analyzer) requires calibration to impart accuracy to the test system. Calibrating test ports typically includes measuring precision coaxial standards having parameters incorporated into the test system. One of the requirements for calibrating test ports is a through measurement of a coaxial standard or alternatively, connection of two test ports. The test ports must either mate with each other or with opposite ends of the coaxial standard. If the test ports are mated without a coaxial standard, then one test port must be a male connector and the other test port must be a female connector. If the test ports are mated with a coaxial standard, the test ports must mate with opposite ends of the coaxial standard. Where the coaxial standard includes opposite ends that are male connectors, the test ports must each be female connectors.
Often, a device under test (DUT) does not have connectors of the same sex as the calibration standard (for instance, the DUT connectors are often female/female and will not mate with the test ports described above). Unfortunately, the use of additional intermediary adapters to change the sex of one or more of the test ports to accommodate the DUT can seriously degrade calibration. It can therefore be desirable to have the ability to change the sex of the test port without degrading calibration.
One method of changing the sex of a test port is described in U.S. Pat. No. 4,891,015 entitled "Universal Connector with Interchangeable Male and Female Sleeves for Use in Network Analyzers and Microwave Devices," issued to Oldfield. The design disclosed in Oldfield '015 can be non-optimal for very high frequency coaxial connectors, such as 1.85 mm and 1 mm connectors. These connectors are very small and pose particular problems. One problem is that calibration components used for the smaller connectors are often line-reflect-line (LRL) components. LRL components are coaxial through-lines that have no center conductor support. Where the length of the lines is long, as is required for lower frequency calibration, the second connection is difficult to consummate because the center conductor is often not centered and will not mate with the test port. Also, the interface between the test port and the LRL can be hidden from view during mating, due to overlapping connection parts of the coaxial connectors. Also problematic for LRL components is installation of a male pin for changing the sex of the connector from female to male. The small diameter of the male pin—the 1 mm connector pin is less than 0.010 inches in diameter—can make installation difficult and less convenient.

Sex changeable adapter for coaxial connectors


A wearable device may store a biometric token associated with a wearer of the wearable device, the wearable device including: a wireless communications interface; a processing circuitry; a memory configured to store a biometric token associated with a wearer of the wearable device, the biometric token including a device identifier that is associated with the wearable device, a biometric template for each of one or more biometric scans of the wearer of the wearable device, and an indication of whether or not the biometric token is valid, wherein the biometric token, if valid, establishes a trust that wearer identifying information, linked to the biometric token, is associated with the wearer; an invalidating event detector configured to determine if an invalidating event has occurred; wherein the processing circuitry is configured to invalidate the biometric token in response to detecting that an invalidating event has occurred for the biometric token.

Wearable technology is growing in popularity. There are a wide variety of wearable devices that are now available, such as smart watches (e.g., which may include a processor, memory, a display, and wireless interface), activity (or fitness) trackers (e.g., to track steps taken, calories burned, time spent exercising), eyewear with a heads-up display, health monitoring devices (e.g., to monitor a variety of health conditions or status of the wearer, such as to track heartrate, pulse, temperature, blood pressure). Some of these wearable devices include technology that would typically be provided in a phone or computer, such as a processor, a memory, a wireless interface, a display, and one or more applications running thereon. However, wearable devices are usually, by design, small, lightweight, stylish, and limited in capability.

Wearable device for trusted biometric identity


The invention described here is a method for using produced fluid compositions to decide how to modify injection/production strategies in oil recovery processes that involve injection of non-aqueous recovery agents ("Injectant"). The procedure is based on the premise that once a given zone is swept by injectant, most subsequent hydrocarbon recovery from that zone will occur by vaporization or extraction into the injectant. Because only the most volatile hydrocarbon components can be extracted, hydrocarbons produced by displacement can be distinguished from those produced by extraction by examining the hydrocarbon composition. Heavy, non-volatile components are recovered only by displacement. The disclosed method determines quantities of displaced vs. extracted hydrocarbons by comparing the produced hydrocarbon composition to that of the original in-place oil. Such information may be used to modify operations in order to most effectively use injectant to recover hydrocarbons from the reservoir.

An oil reservoir consists of a subterranean formation with small interconnected pores filled with hydrocarbon liquid, gas, and water, usually at an elevated pressure. The hydrocarbon liquid phase at reservoir temperature and pressure, hereafter termed "oil", includes liquid crude oils and liquid crude oils containing dissolved gases (e.g., methane (CH.sub.4), ethane (C.sub.2 H.sub.6), propane (C.sub.3 H.sub.8), butanes (C.sub.4 H.sub.10), carbon dioxide (CO.sub.2), nitrogen (N.sub.2), and hydrogen sulfide (H.sub.2 S)). The volume fraction of each phase in the porespace is referred to as its "saturation". The formation in which the oil, water, and gas reside consists of strata of varying ability to conduct fluid. The ability of the formation to conduct fluid is measured by its permeability, defined as the ratio of flow rate to the product of applied pressure gradient and fluid viscosity. In high permeability strata, large flow rates can be sustained with relatively low pressure gradients.
Initially, oil is produced from the formation by "primary" production methods that utilize the energy present in the fluids in the formation. For example, primary production can occur by fluid expansion upon a decrease in reservoir pressure.
A high oil saturation usually remains after primary production. At this point, "secondary" recovery techniques are often implemented to recover additional oil. The most common secondary recovery process is a "waterflood" in which large quantities of water are injected into the formation through specified wells to displace oil towards production wells in the vicinity.
In many cases, a high oil saturation is present after the waterflood. This results in part from the high interfacial tension between oil and water. Interfacial tension traps oil in the porespace. "Tertiary" processes are sometimes initiated at this point. The most common commercially applied tertiary recovery process involves injection of substantially non-aqueous fluids to displace oil towards production wells. These non-aqueous fluids are typically high pressure gases or supercritical fluids, which will be referred to as tertiary recovery fluids.
A supercritical state for a fluid exists when the temperature and pressure exceed the fluid's critical density, temperature, and pressure. Below a fluid's critical temperature (T.sub.c) and critical pressure (P.sub.c) the fluid can consist of both a gas and liquid coexisting in a gas-liquid equilibrium. Above and around T.sub.c, and P.sub.c, however, the fluid can exist only in a single phase, known as a supercritical fluid. For example, water has a T.sub.c =374.degree. C. and a P.sub.c =2.21.times.10.sup.7 pascals. Consequently, if water is at a pressure close to its critical pressure, it will become increasingly turbid and milky as the temperature is lowered from a temperature well above to its critical temperature, 374.degree. C., down to its critical temperature. Upon slight additional cooling below the critical temperature the turbidity disappears and two distinct liquid and vapor phases form. A supercritical fluid's properties, such as density, are intermediate between a gaseous and liquid state for the same substance, but are typically more like the corresponding liquid state. Consequently, a supercritical fluid will normally behave more like a liquid than a gas in terms of its physical behavior thereby enhancing its ability to displace and/or extract hydrocarbons from a formation during tertiary recovery.
Fluids commonly used for tertiary recovery are carbon dioxide, nitrogen, methane, and ethane. Such a process is typically referred to as a "gas injection process." When a tertiary injection fluid, also called the injectant, is used in a gas injection process, hydrocarbon components in the oil vaporize into the injectant, modifying the properties of both the oil and injectant so the interfacial tension between them is reduced. The result is that a substantially non-aqueous injectant can reduce the oil saturation below that seen at the end of the waterflood. The physics of this process are described in petroleum engineering texts well known to those skilled in the art.
FIG. 1 illustrates some of the important recovery mechanisms in a gas injection process. It shows a formation with two zones, 102 and 104, with different values of permeability. The higher permeability zone, 104, is completely swept before the lower permeability zone, 102, is completely swept. Once a zone is completely swept with injectant it is typically referred to as a "swept zone," while a zone where the injectant sweep is incomplete is referred to as an "unswept zone." Note that if a zone is said to be "completely swept", it does not mean that all possible oil has been recovered from that zone; rather, it means that the injectant has passed through the entire zone.
Even in zones that are swept, pockets of bypassed oil are present. After a swept zone has been established, continued injection of the injectant, 101, results in extraction of hydrocarbons from residual pockets of oil, 108, remaining after the initial injectant sweep through the higher permeability zone, 104. The result is that a mixture of injectant and extracted hydrocarbons, 105, is produced from the swept zone, 104. Accordingly, in addition to recovering oil by direct displacement, the injectant extracts, by a vaporization process, some of the more volatile hydrocarbon components in the residual oil that remain in the swept zone. This vaporization process is referred to as "extraction". Extraction results in production of hydrocarbons that are initially comprised of more volatile components and progressively become comprised of less volatile components as injectant is recycled and reinjected through the swept zone.
As shown in FIG. 1, a water and hydrocarbon mixture, 103, is produced as injectant, 101, displaces the water and hydrocarbons originally in place, therefore leaving residual pockets of oil, 106, in the lower permeability zone, 102.
Therefore, injectant is used to (1) recover hydrocarbons by displacing hydrocarbons originally in place in the formation and (2) extract hydrocarbon components from bypassed oil remaining after the injectant completes its first sweep in a particular zone. The result is that during gas injection processes, the produced hydrocarbon fluid will be a mixture of displaced and extracted hydrocarbons.
Examples of such displacement/extraction processes on a laboratory scale are given by Stern (1991), and Shyeh-Yung and Stadler (1994), and in field tests by Fox, Simlote, and Beaty (1984). Mathematical models of the oil recovery process also predict this behavior. For example, Huang, Bellamy, and Ohnimus (1986) have described the results of such mathematical modeling.
In practice, the amount of oil recovered from gas injection processes depends on the injectant's effectiveness in (1) displacing the oil's hydrocarbon components, (2) extracting the oil's hydrocarbon components and (3) uniformly contacting the formation. For example, injectant may flow predominantly through high permeability strata and bypass lower permeability portions of the formation altogether. Computer simulation (mathematical modeling) is used to predict how much oil will be recovered, given a description of the formation and an estimate of the remaining oil saturation after gas flooding.
Despite using all available information to design a gas injection process, there are often large uncertainties about the spatial arrangement of the formation's permeability and porosity. This can have a large impact on the performance of the gas injection process. As a result, it is almost always necessary to modify the injection process based on the formation's actual response to injection of the injectant. In operating gas injection projects, gas, water, and oil production rates at individual production wells are used to determine near-term gas injection strategies. Typically, the injectant is redirected away from wells that are producing at an elevated gas-oil ratio (GOR) and towards low GOR wells. Injectant-oil-ratio is also used for this purpose, when appropriate data are available. This is preferred, since injectant-oil-ratio better indicates how much injectant is produced at a given well. McGuire and Stalkup (1992) have described use of this technique at Prudhoe Bay, a field in Alaska currently under hydrocarbon gas flooding. In this case, complex analyses are required to distinguish produced injectant from produced in-place gas. The problem with either of these approaches is that the engineer cannot precisely determine from the available data what fraction of the produced hydrocarbons result from (1) direct displacement of hydrocarbons by the injectant in the lower permeability zone versus (2) extraction of hydrocarbons by the injectant passing through the swept zone. For example, in certain instances, the injectant may extract economically significant quantities of volatile hydrocarbons, including but not limited to methane (C.sub.1), ethane (C.sub.2), propane (C.sub.3), butane (C.sub.4), pentane (C.sub.5), hexane (C.sub.6), heptane (C.sub.7), and/or octane (C.sub.8), from higher permeability zones in the formation completely swept by injectant. Consequently, the continued injection of the tertiary recovery fluid is economically justified. However, as more of the residual volatile components are extracted from the swept zone, the injectant will inefficiently cycle through the zone. As the zone becomes significantly depleted of its residual hydrocarbons it becomes identified as a "thief zone," because the zone (1) takes injectant that could otherwise be used for directly displacing and/or extracting hydrocarbons, and (2) produces relatively small amounts of hydrocarbons.
Thus, there is a need for a method for determining the relative percentage of hydrocarbons produced by (1) injectant extraction from gas-swept zones and (2) injectant displacement of hydrocarbons from unswept zones of a subterranean formation. Such a method would be valuable in helping to manage and maximize the economically efficient use of injectant in field-scale gas injection processes.

Method for improving oil recovery from a formation using hydrocarbon analysis of the fluid produced therefrom


A bi-phase decoder for extraction of an embedded clock in a Manchester encoded signal operating at about ten megahertz. A phase-lock loop (PLL) includes a phase frequency detector and an interruptible voltage controlled oscillator (VCO). The PLL has a narrow bandwidth for stability to reduce effects of five megahertz components on clock extraction. The bi-phase decoder has a fast acquisition time to ensure frequency and phase lock during a preamble portion of an input data packet. A clock reference operates the PLL and the VCO at a nominal frequency of the embedded clock. Receipt of a data packet initiates interruption of the VCO operation to switch in the received data. The VCO resumes operation in phase with the received data packet and at about the proper frequency, therefore acquisition is fast. The VCO is designed to resume operation after operation at a particular phase to help in phase alignment.

The present invention relates to phase-lock loops. Specifically, the invention relates to a phase-lock loop implemented in a complementary metal oxide semiconductor structure. The invention also relates to use of the phase-lock loop in an apparatus to extract an embedded clock in a Manchester-encoded data stream.
Manchester-encoded data, also referred to as a bi-phase signal, results from combining a clock signal with binary data through use of an Exclusive OR function. Encoding 10 megahertz data, for example, in this way produces a data stream having both 5 megahertz (MHz) and 10 MHz signals. The definition of Manchester-encoded data does not restrict an encoding frequency to 10 megahertz. A network which conforms to an IEEE 802.3 Standard requires an encoding frequency of 10 megahertz. A preferred embodiment of the present invention is useful for such a network.
Manchester-encoded data always has a transition in what as referred to as a bit-cell center. Other transitions may or may not occur at a bit cell boundary, depending on the data type. Therefore, it may be said that Manchester-encoded data has signal components at the data rate (10 megahertz, for example) and one half of the data rate (5 megahertz, for example)
To decode this Manchester-encoded data, a detector extracts the embedded clock signal. Combining the extracted clock signal with the encoded signal by forming the Exclusive OR logical sum, reproduces the data. Thereafter, the data and the clock signal are available. Extracting the clock requires that the data of the encoded Manchester signal be sampled in the second half of the bit cell, that is after the bit cell center. The Manchester-encoded signal includes an embedded clock signal, such as 10 megahertz. However, variation in this embedded clock signal will occur. The variation causes uncertainty in the sampling point of the encoded data.
Phase-lock loops track variations in frequency of an input signal. Phase-lock loops are used in circuitry to extract the clock from the Manchester signal. Since the valid Manchester-encoded data has both 5 MHz and 10 MHz components, conventional phase-lock loops cannot properly track the data. That is, if the phase-lock loop receives a succession of 10 MHz pulses followed by a 5 MHz pulse, the phase-lock loop attempts to track the 5 MHz and correct itself. If the 5 MHz pulse is followed by a 10 MHz pulse, the phase-lock loop again tries to correct itself. Alternation of the 5 and 10 MHz pulses results in the phase-lock loop trying to track the changing signal. Phase-lock loops have a characteristic known as bandwidth. The greater a bandwidth, the faster the phase-lock loop can respond to variations in an input signal's frequency. The smaller the bandwidth, the more stable and resistant to change is the phase-lock loop. It is possible with a large bandwidth, that inherent jitter in an encoded Manchester signal can combine with a fluctuating phase-lock loop to cause random sampling of the encoded Manchester signal. Random sampling of the Manchester signal results in incorrect data acquisition providing faulty operation. Therefore, use of small bandwidth circuits relatively immune to changes in input frequency provide insensitivity to frequency fluctuations and remain locked onto nominal 10 MHz components.
Conventional timing circuits frequently use one-shot circuits. Often, a starting edge of a pulse initiates an event. It is desirable to register receipt of a corresponding stop pulse. It is also desirable to register an excessive amount of elapsed time, indicating failure to receive a stop pulse. This one-shot timing is not conveniently done by use of clock signals. A problem results from the fact that many manufactured products cannot simultaneously compensate for voltage, current and capacitance differences which vary independently in these timing circuits. These variations occur from device to device and transistor to transistor of each device. A solution typically uses constant current sources because of the known relationship between current and capacitance represented by: dv/dt=i/C. If a constant current flows into a fixed capacitance, then a change of voltage over time will be constant. Phase-lock loop timing circuits having stable frequencies control these current sources to provide accurate timing. Therefore, variation in a phase-lock loop can disrupt timing sequences controlled by regulated current from the phase-lock loop. Therefore, variation in phase-lock loops are not desired.
A second problem in phase-lock loops, especially those having the desired narrow bandwidth, is that they usually have a slow acquisition time constant. An acquisition time constant is an indication of how long it takes for a phase-lock loop to adjust itself to coincide with an input frequency. The amount of time a phase-lock loop would take to go from 0 Hz frequency to 10 MHz is determinable in a well-known fashion. However, this finite amount of time is typically many orders of magnitude too long for use in devices decoding 10 MHz Manchester data corresponding to the IEEE specification 802.3. This specification is hereby expressly incorporated by reference. The IEEE specification 802.3 clearly identifies a maximum amount of time which a decoding device may add to a received data stream before it may output valid data. Most devices with a narrow bandwidth have a slow acquisition time which would add unacceptable amount of delay to decoding of data. As acquisition times become longer, introduced delays may be of sufficient magnitude that an entire manchester-encoded packet may be fully received and terminated before proper acquisition and decoding of the data by the phase-lock loop. Therefore, there is an inherent tension between a narrow bandwidth requirement and a fast acquisition time constant. The necessary fast acquisition time constant ensures that a phase-lock loop almost immediately locks onto the incoming signal. U.S. Pat. No. 4,565,976 to Campbell describes an interruptable voltage-controlled oscillator and a phase-lock loop using the voltage-controlled oscillator. The Campbell disclosure is useful for decoding Manchester data. The disclosure identifies a phase-lock loop which has a narrow bandwidth and a fast acquisition time. This disclosure hereby incorporates by reference the Campbell patent for all purposes.
The Campbell patent is useful in Manchester decoding apparatus because it establishes a narrow bandwidth phase-lock loop locked onto an external 10 MHz frequency source. When it is desired to decode an incoming Manchester signal, the phase-lock loop operating at the external 10 megahertz reference frequency is temporarily interrupted, the Manchester signal is switched in place of the external reference clock, and the phase-lock loop is then caused to resume operation at a specific phase of the Manchester signal. Thereafter, acquisition is virtually immediate as the phase-lock loop is operating at the nominal 10 megahertz frequency and the phase difference between the phase-lock loop and the embedded 10 megahertz Manchester-encoded clock is virtually zero. As the phase-lock loop has a narrow bandwidth, it is not susceptible to the 5 megahertz component and will continue sampling the data at the 10 MHz embedded clock frequency.
The Campbell invention uses a master-slave phase-lock loop configuration. The Campbell patent incorporates power intensive emitter coupled logic (ECL) to implement the invention. It is desired to provide a narrow bandwidth fast acquisition phase-lock loop from complementary metal oxide semiconductor (CMOS) structures. Additionally, elimination of structures in the Campbell implementation reduces component count.

Bi-phase decoder phase-lock loop in CMOS


A tape cartridge having a tape wound between a pair of rotative reels and the tape can be drawn from the cartridge, an expansive belt or rotative rollers is/are contacted on the surface of parts of the tape which are wound around the reels for eliminating the air between the tape layers, for removing dust adhered on the surface of the tape. Thereby, the appearance of the tape wound the reels can be increased and the occurrence of drop-out or increase in the rate of error can be prevented.

Recently, a thin tape is used in a tape cartridge of video tape and the like comprising a parallel-two-reel system for enabling long recording. However, when a thin tape having a thickness of 15 .mu.m or less is forwarded and rewound at high speed, air layers are formed between each tape layer wound around reels. As a result, the tape slips in its widthwise direction (which is perpendicular to the tape moving direction). When the tape slips in its widthwise direction, the edges of the tape rub the bottom or ceiling of the housing of the tape cartridge, and the edges of the tape are damaged. Additionally, when the tape protrudes from the reels in its widthwise direction, the load for drawing the tape out from the tape cartridge becomes very heavy.
When dust which is created by rubbing the edges of the tape on the bottom or ceiling of the housing or which is naturally present in the air adheres on a recording face of the tape, the dust leads to recording and replaying signal failures. In particular, the tape is affected more by the adhered dust as the recording density becomes higher. Accordingly, the rate of error occurrence worsens enormously when the tape is repeatedly forwarded and rewound, and the number of drop-outs also increases.
An example of the tape cartridge containing the thin tape and used for high-density recording and reproducing is disclosed in U.S. Pat. No. 3,692,255. Another example is disclosed in U.S. Pat. No. 5,081,555.
First, the conventional tape cartridge disclosed in U.S. Pat. No. 3,692,255 is described referring to FIG. 13. This Patent relates to a tape cartridge in which reels are freely pivoted without engaging any driving mechanism and a tape is moved by a belt driving mechanism. As shown in FIG. 13, a cartridge 101 is comprised of a thin box-shaped top cover 103 made of resin and a base plate 102 made of a metal such as an aluminum plate. Top cover 103 is fixed on base plate 102 by screws. On a bottom face of base plate 102, a pair of reels 104 are freely and rotatively pivoted. A magnetic tape 105 is wound around between reels 104. Tape 105 is guided along a front face wall 103b in the inside by a pair of tape guides 106 disposed on base plate 102. Furthermore, a belt driving roller 107 is rotatively pivoted on the front side in the center of base plate 102. Also, a pair of belt guiding rollers 108 which are rotatively pivoted at both ends on the rear side of base plate 102. A belt 109 having elasticity is guided by belt driving roller 107 and both belt guiding rollers 108. Belt 109 is formed substantially in a kind of T form with strong tension of 1.6 N or higher. A part of belt 109 contacts and presses the outer circumference of both parts 105a of tape 105 which are respectively wound around both reels 104.
When tape cartridge 101 is loaded in a recording-reproducing apparatus (not shown in the figure), a door 111, which is rotatively pivoted between base plate 102 and top cover 103, is rotated in the direction shown by arrow A in the figure such that door 111 is to be in a position shown by one dotted chain line in the figure. Thus, a cutout part 110 which is formed at one end on the front side of base plate 102 and top cover 103 is opened. Subsequently, a magnetic head 112 provided on the recording-reproducing apparatus is inserted into cutout part 110, and magnetic head 112 contacts the recording face of tape 105. At the same time, a driving roller 113 provided on the recording-reproducing apparatus is inserted into an opening part 114 which formed on top cover 103, and driving roller 113 presses and rotates an outer circumference of a a part 107b having a larger diameter and integrally formed with and on top of a belt winding face 107a of belt driving roller 107. Then, belt driving roller 107 is rotatively driven by the rotation of driving roller 113, for example, in the direction shown by arrow B in the figure. Thus, belt 109 is driven in the direction shown by arrow C. Due to the movement of belt 109, the part 105a of tape 105 wound around both reels 104 are rotatively driven in the direction shown by arrow D in the figure. Accordingly, tape 105 moves in the direction shown by arrow E in the figure at a relatively high speed of 25 to 120 inch per second. At this time, recording and reproducing are performed by a magnetic head 112 onto the recording face of tape 105.
Next, the conventional tape cartridge disclosed in U.S. Pat. No. 5,081,555 is described referring to FIG. 14 and FIG. 15. This Patent relates to a compact cassette used mainly for music, and has an object of removing dust adhered on a recording face of a magnetic tape. As shown in FIG. 14 or 15, a pair of reels 204a, 204b are rotatively pivoted on a bottom face of a base member 202, and a magnetic tape 205 is wound around between both reels 204a, 204b. Tape 205 is guided by a pair of tape guides 206 disposed on base member 202 and is passed along an opening part 202a in the inside. Furthermore, a ring-shaped or substantially V-letter-shaped flexible strip 207 is provided in the center part of base member 202. Outer faces of flexible strip 207 are respectively in contact with a recording face of parts 205a, 205b of tape 205 wound around both reels 204a, 204b. Flexible strip 207 is formed, for example, of elastic materials such as polytetrafluoroethylene (PTFE). On the surfaces of flexible strip 207 contacting the recording face of tape 205, a non-woven fabric or paper and the like is formed as a cleaning layer.
In general, both of the tape cartridges 101 and 201 described above are configured such that the recording faces of tapes 105 and 205 are respectively pressed by belt 109 and flexible strip 207 while the tape moves. Therefore, it is considered as possible to wind tapes 105 and 205 on reels 104 and 204a, 204b while eliminating the air from gaps between the tape layers. In this case, even if the tape is forwarded at a relatively high speed, tape 105 or 205 does not slip out in the widthwise direction, so as to wind the tape in a stable condition. Furthermore, the dust adhered on the tape is scratched off by belt 109 or flexible strip 207, so that the rate of error occurrence or the occurrence of drop-outs can be reduced.
In order to attain a high-density recording, it is necessary to record and reproduce relatively high-frequency signals with high density. Therefore, a rotary-head system is generally used in which a tape is drawn out from a cartridge and is wound around a rotary-head drum for recording and reproducing. However, since the tape is driven by the belt in the tape cartridge according to U.S. Pat. No. 3,692,255, the friction coefficient between the tape and the belt is high, and in addition, the load due to tension of the belt is also high. As a result, when the tape cartridge 101 is used, a large drawing torque is needed to draw tape 105 out from tape cartridge 101. Thus, the problem with this type is that tape cartridge 101 can not be used for a recording-reproducing apparatus comprising a general rotary head system employed in a video taperecorder or in computer data storage. Also, especially when a thin tape (which dislikes the air layers formed between tapes) is used, when they are taken up on reels, the tape tended to lengthen or be cut off when it was attempted forcibly to draw out the tape against the load.
On the other hand, when the tape cartridge 201 according to U.S. Pat. No. 5,081,555 is used, flexible strip 207 is indeed formed of resin materials such as PTFE, but these materials do not possess the ability to expand and contract, despite being elastic. In other words, the ring-shaped flexible strip 207 does not expand in its full circumference, but remains constant. Therefore, when the tape parts which were wound around reels 204 change their diameters, flexible strip 207 slightly deforms itself responding to these changes, but the deformation is not so great as to cause expansion. As the tape travels, the diameter of the part 205a of tape 205 wound around one reel 204a becomes gradually larger, while the diameter of the other part 205b of tape 205 wound around the other reel 204b becomes smaller, so that flexible strip 207 is considered to traverse between these two reels 204a, 204b.
Since tape 205 travels at a constant speed, when the diameter of the part 205b of tape 205 wound around reel 204b is small, the curvature of the part 205b changes largely. Therefore, since flexible strip 207 can not move and deform itself responding to the changes in diameter of the parts 205a, 205b of tape 205 wound around reels 204a, 204b, it may also happen that flexible strip 207 can not contact the surface of parts 205a, 205b of tape 205 wound around reels 204a, 204b. As a result, air which is present between each tape layer of parts 205a, 205b of tape 205 can not be eliminated, so that the tape 205 slips out in the width direction, which leads to the problem that the tape can not be wound around reels 204a, 204b in a stable condition. Furthermore, the dust adhered on the recording face of tape 205 can not be scratched off, so it was difficult to reduce rate of error occurrence or drop-outs and the like.
Meanwhile, one of the performance characteristics required for a magnetic tape which is used repeatedly for recording and reproducing is a still-life. The still-life indicates durability of a tape when the tape loaded in a rotary head is reproduced while stopped for the purpose of outputting a still picture image in a video taperecorder and the like. The still-life plays a particularly important part in a broadcasting station which conducts video editorial operations, during which the still-life needs to stand for many hours. Also, in case of a domestic video taperecorder or a recording-reproducing apparatus for music use and the like, this system of pausing the moving tape in the loaded condition is used widely for improving quick access. Therefore, the still-life is also extremely important in the field of home electrical devices.
In order to improve the still-life, a lubricant such as fatty acid etc. has been applied on a magnetic layer in the past, so that the lubricity between the magnetic layer of a tape and the magnetic head improves. The more a lubricant is added, the better the lubricity of the applied film with the magnetic head. However, the strength of the applied film is greatly influenced by the amount at lubricant. If too much lubricant is added, the strength of the applied film conversely deteriorates, so that a predetermined still-life can not be secured. To prevent this kind of deterioration in the strength of the applied film from occurring, it is also possible to employ a method of applying a lubricant after forming a magnetic layer of the tape. However, the lubricant must be applied by dissolving it in an organic solvent and the like. In this case, the magnetic layer is eroded by the organic solvent, which leads to deterioration of the applied film, so that a satisfactory still-life can not be attained.
Furthermore, since the positions of reel stands in a recording-reproducing apparatus differ in each case, reels of the tape cartridge comprising a parallel-two-reel system are not fixed to the cartridge. Instead, there is enough tolerance provided to facilitate engagement of the reels with the reel stands. As a result, the reels move with great acceleration due to vibrations caused during transportation or shock etc. when cartridges are accidentally dropped, and the tape (particularly the tape that is wound around with a large volume of tape) is drawn suddenly, it causes damages to the tape. This phenomenon is especially notable for thin tapes. In addition, the vibrations during transportation etc. cause tapes to become loose which then show loading failures when loaded.


A method for correcting Maxwell field induced distortion, ghosting, and blurring artifacts in non-axially oriented EPI images is disclosed. In one embodiment phase corrections are calculated and used to offset Maxwell term errors during the image reconstruction process, and in another embodiment corrections are made after the image is reconstructed.

The field of the invention is nuclear magnetic resonance imaging methods and systems. More particularly, the invention relates to the correction of image artifacts caused by "Maxwell terms" produced by MRI systems.
When a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B.sub.0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it at their characteristic Larmor frequency. If the substance, or tissue, is subjected to a magnetic field (excitation field B.sub.1) which is in the x-y plane and which is near the Larmor frequency, the net aligned moment, M.sub.z, may be rotated, or "tipped", into the x-y plane to produce a net transverse magnetic moment M.sub.t. A signal is emitted by the excited spins, and after the excitation signal B.sub.1 is terminated, this signal may be received and processed to form an image.
When utilizing these signals to produce images, magnetic field gradients (G.sub.x, G.sub.y, and G.sub.z) are employed. Typically, the region to be imaged is scanned by a sequence of measurement cycles in which these gradients vary according to the particular localization method being used. The resulting set of received NMR signals are digitized and processed to reconstruct the image using one of many well known reconstruction techniques.
It is well known that imperfections in the linear magnetic field gradients (G.sub.x, G.sub.y, and G.sub.z) produce artifacts in the reconstructed images. It is a well known problem, for example, that eddy currents produced by gradient pulses will distort the gradient fields and produce image artifacts. Methods for compensating for such eddy current errors are also well known as disclosed, for example, in U.S. Pat. Nos. 4,698,591; 4,950,994; and 5,226,418.
It is also well known that the gradients may not be perfectly uniform over the entire imaging volume, which may lead to image distortion. Methods for compensating this non-uniformity are described, for example, in U.S. Pat. No. 4,591,789.
Other than uncompensated eddy current errors and gradient non-uniformity errors that escape correction, it can be assumed that the magnetic field gradients (G.sub.x, G.sub.y, and G.sub.z) produce linear magnetic fields exactly as programmed, thus spatially encoding the NMR data accurately. With these gradients, the overall static magnetic field at location (x,y,z) is conventionally given as B.sub.0 +G.sub.x x+G.sub.y y+G.sub.z z, and the direction of the field is usually thought to be along the z-axis. This description, however, is not exactly correct. As long as a linear magnetic field gradient is applied, the overall magnetic field is nutated away from the z-axis and its amplitude exhibits higher-order spatial dependencies (x.sup.2, y.sup.2, z.sup.2, z.sup.3, . . . ). These phenomena are a direct consequence of the Maxwell equations which require that the overall magnetic field satisfy the following two condition: .gradient..multidot.B=0 and .gradient..times.B=0. The higher-order magnetic fields, referred to as "Maxwell terms" (or Maxwell fields), represent a fundamental physics effect, and are not related to eddy currents or imperfection in hardware design and manufacture. Although Maxwell terms have been known for at least a decade, their effect on imaging has been largely ignored because of their minute consequences for conventional imaging conditions.
Echo-planar imaging ("EPI") is one of the ultrafast MR imaging techniques that has many clinical applications. Consider, for example, a superconducting MRI system where the main magnetic field is oriented along the long axis of the patient. EPI can then suffer from severe image distortion when the imaged slice is oriented in a sagittal or coronal plane and frequency or phase encoding is performed along the direction of the polarizing magnetic field B.sub.0. In addition, there is a certain amount of ghosting and blurring in such images. The image distortion, ghosting, and blurring in such images are caused by the Maxwell terms. As a result, EPI has been usually limited in both clinical and research applications to axially oriented slices which are perpendicular to the magnetic field B.sub.0.

Correction of artifacts caused by Maxwell terms in MR echo-planar images


A converter circuit arrangement is specified having a rectifier, an intermediate circuit and an invertor connected thereto. In order to protect the circuit against failures and overvoltage, a protection circuit which comprises, in particular, varistors is connected between the two partial rectifiers of the rectifier.

1. Field of the Invention
The invention relates to the field of power electronics. It is based on a converter circuit arrangement having a rectifier, in particular with a 12-pulse topology, and an invertor which is connected downstream via an intermediate circuit, as claimed in the precharacterizing clause of the first claim.
2. Discussion of Background
A converter circuit arrangement of this generic type comprises a rectifier which has, in particular, a 12-pulse topology and supplies a DC intermediate circuit. The rectifier comprises a first partial rectifier which is connected to a star circuit of an AC power supply, and a second partial rectifier which is connected to a delta circuit of the AC power supply. A DC intermediate circuit which supplies, for example, a downstream converter, can be connected to the partial rectifiers. The use of the 12-pulse topology results in a DC voltage which is distinguished by extremely low ripple. Connected downstream of the DC intermediate circuit is an invertor which, for example, may be in the form of a three-point invertor. The components in this circuit arrangement must be protected against various failures, in the rectifiers, the power supply or the invertor. In particular, the intermediate circuit capacitors must not be overcharged. If a semiconductor in the rectifiers fails, consequential damage must be limited to a minimum. The same applies to failure of an invertor semiconductor. Finally, it should also be possible to cope with unusually high power supply overvoltages without any damage.

Converter circuit arrangement with protection circuit


A commutator main body 11 includes a plurality of commutator pieces 13 arranged along a circumference, the center of which is a rotation axis L of a motor, and a main body insulator 14 holding the commutator pieces. A short-circuit member 12 is arranged on an end portion of the commutator main body 11 and includes a short-circuit conductor 21, which short-circuits predetermined ones of the commutator pieces, and a short-circuit insulator 22, in which the short-circuit member is embedded. A boss is formed integrally with the short-circuit insulator so as to project from the end portion of the commutator main body.

The present invention relates to a commutator in which predetermined commutator pieces are short-circuited, and to an armature.
In the prior art, an armature for a motor having power feeding brushes may include a commutator in which a plurality of commutator pieces are short-circuited. Such a motor allows electric current to flow even to commutator pieces that are not in contact with power feeding brushes by short-circuiting predetermined commutator pieces. This enables a reduction in the number of power feeding brushes required in the motor.
In one example, in a rotation machine described in Japanese Laid-Open Patent Publication No. 2000-134873, short-circuit wires for short-circuiting commutator pieces are arranged on an end portion of a commutator.
However, when the short-circuit wires are arranged on the end portion of the commutator, the short-circuit wires may rub against one another or the short-circuit wires may rub against coils and cause an electric connection (layer short). This would lower yield during the manufacturing of the armature or cause erroneous operation.


An apparatus comprising a first circuit configured to receive a first clock signal and delaying the first clock signal by a first delay to generate a second clock signal, the first delay being a first function of a first signal; a phase-frequency detector configured to receive the first clock signal and the second clock signal and generate a second signal dependent on the first delay; a second circuit configured to receive tile second signal and generate a third signal, the third signal being a digital signal; and a current mirror configured to generate the first signal, the first signal being a second function of the third signal.

1. Field of the Invention
The present invention relates to the field of generating a periodic signal-, more particularly, the present invention relates to a method and apparatus for generating a periodic signal using a delay locked loop.
2. Description of Related Art
Phase-locked loops (PLLs), synchronous delay lines (SDLs), and delay locked loops (DLLs) are used to generate an output clock signal that locks onto the period of an input clock signal.
These circuits use a charge pump that drives an analog control voltage to be received by sample and hold (S/H) circuits. The sampled analog control voltage is used to control a voltage-controlled oscillator (VCO) in a PLL and a voltage-controlled delay line in an SDL or DLL. Noise and mismatching between capacitors of the S/H circuits causes instability in the output clock signal (clock jitter). Clock jitter reduces the maximum frequency of operation of a device and may lead to device malfunction. In addition, charge pumps use large capacitors. The cost of a silicon device is related to the silicon area. Thus, these circuits may be relatively expensive to produce.
Lock time is the number of clock cycles required for the output clock signal to lock onto the period of the input clock signal. Since the device operation does not reliably begin until after a stable output clock is generated, the lock time is a component of the latency for the device to operate after power-up. SDLs, PLLs, and DLLs have lock times on the order of thousands of clock cycles. Thus, there is; a delay of thousands of clock cycles before the device begins to operate after power up. High latency leads to reduced performance. Furthermore, test procedures for a device during a manufacturing process typically include many power-up sequences. Thus, the latency increases the time to test the device and therefore increases manufacturing costs.
Similarly, if the period of the input clock signal is changed, there may be a latency of thousands of clocks for the output clock signal to lock onto the new period of the input clock signal. Thus, there is a delay of thousands of clock cycles before the device begins to operate after an operating frequency change. An operating frequency change may be performed, for example, to conserve power when the device is idle.
Furthermore, the use of analog circuitry in a digital device, such as a microprocessor, typically tends to make manufacturing more complex. Optimal manufacturing process conditions for analog circuitry is often different than that of digital circuitry. Compromises are often required. Thus, it is desirable to manufacture a purely digital device to permit the use of a manufacturing process that is optimized for digital circuitry without the additional complexity and, in some cases, reduced performance and/or yield due to the use of analog circuitry.
What is needed is a method and apparatus to reduce clock jitter in a device used to lock an output clock signal onto the period of an input clock signal. What is needed is a method and apparatus to reduce cost in a device used to lock an output clock signal onto the period of an input clock signal. What is needed is a method and apparatus to reduce the lock time in a device used to lock an output clock signal onto the period of an input clock signal. What is needed is a purely digital device to lock an output clock signal onto the period of an input clock signal.


An initial arrangement is effected based on a net list and a cell library. Combination functions are extracted from a cost function. An optimum estimated temperature is calculated based on the difference between values of the cost function before and after two adjacent elements that have been selected randomly from elements to be arranged are interchanged in position, while near-optimum estimated temperatures are calculated based on the differences between respective values of the combination functions before and after the positional interchange. Of the near-optimum estimated temperatures, those lower than the optimum estimated temperature are recorded in a temperature schedule list together with the optimum estimated temperature. Thereafter, the Monte-Carlo method based on a random positional interchange between the elements to be arranged using the cost function is executed in order of the decreasing temperatures recorded in the temperature schedule list, whereby the initial arrangement is improved.

The present invention relates to a method of optimizing placement of elements in designing a semiconductor device.
As a method for combinational optimization, simulated annealing (SA) has been proposed (S. Kirkpatrick et al., xe2x80x9cOptimization by Simulated Annealingxe2x80x9d, SCIENCE, Vol. 220, No. 4598, pp.671-680, May 1983). SA is a method of accomplishing combinational optimization by using the Monte-Carlo (MC) method, which is a method for a computer simulation in the field of thermodynamics. In the case of using an SA process to solve an element placement problem, the element placement problem is regarded as a physical problem and a cost function for evaluating element placement is regarded as an energy function. Then, an estimated temperature is determined and a physical structure (placement structure) of a state of thermal equilibrium at the temperature is evaluated by the MC method based on the energy function (cost function). An arrangement of elements having a low cost function is determined approximately on the analogy of a physical state which approaches a minimum energy state as the temperature is gradually decreased.
Although it has been proved that SA provides a good approximate solution, the problem is encountered that enormous processing time is required for the solution to converge because it is necessary to gradually reduce the estimated temperature from an extremely high level to a low level.
To solve the problem, a simulated phase transition (SPT) method in which an optimum estimated temperature is determined previously to the execution of the MC method has been proposed (M. Toyonaga et al., xe2x80x9cPlacement Optimization by Simulated Phase Transitionxe2x80x9d, Technical Report of IEICE, CAS98-20, VLD98-20, DSP98-49, pp. 37-44, June 1998). In accordance with the SPT method, a temperature which improves the value of a cost function (cost value) most efficiently, i.e., an optimum estimated temperature Tc is determined first. By executing the MC method at the temperature Tc, the gradual cooling process from the extremely high temperature to the temperature Tc, which has been necessary in the case of implementing SA, becomes no more necessary.
In accordance with the SPT method described above, only one optimum estimated temperature Tc is obtained from one cost function. In addition, the temperature Tc is lower than the temperature at which the MC method in SA is initiated but higher than the temperature at which the approximate solution is obtained by it. In the SPT method, therefore, a new optimum estimated temperature Tcxe2x80x2 ( less than Tc) is determine sequentially by repeatedly performing the fixation of part of element placement in a range of estimated temperatures not more than Tc. However, there are cases where the approximate solution obtained may be inferior to that obtained by SA if the standard for the fixation of element placement has randomness and the setting of the standard is inappropriate.
It is therefore an object of the present invention to allow easy determination of a temperature effectiv in executing the MC method in a range of temperatures lower than an optimum estimated temperature derived from a cost function and ensure the achievement of improved element placement.
To attain the object, the present invention extracts at least one combination function from one cost function and determines an optimum estimated temperature derived from the combination function, thereby allowing easy determination of the temperature effective in executing the MC method in a range of temperatures lower than the optimum estimated temperature Tc derived from the original cost function.
Specifically, a method of optimizing placement of elements in accordance with the present invention is a method of optimizing placement of elements in designing a semiconductor device by using a cost function for evaluating the placement of elements, the cost function being expressed as a sum of p (p is an integer not less than 2) partial functions and varying with an estimated temperature as a parameter, the method comprising: a first step of inputting a net list and a cell library and effecting an initial arrangement of elements to be arranged; a second step of extracting functions each expressed with either one of the p partial functions of the cost function or, when p is an integer not less than 3, expressed as a sum of a combination of not less than 2 and not more than (pxe2x88x921) partial functions of the p partial functions of the cost function as q (q is an integer not less than 1 and not more than (2pxe2x88x922)) combination functions; a third step of randomly selecting two elements adjacent to each other from the elements to be arranged, calculating one optimum estimated temperature based on a difference between values of the cost function before and after the two elements are interchanged in position, and calculating q optimum estimated temperatures based on differences between respective values of the q combination functions before and after the interchange; a fourth step of recording, in a temperature schedule list, the temperatures of the q optimum estimated temperatures derived from the q combination functions which are lower than the optimum estimated temperature derived from the cost function together with the optimum estimated temperature derived from the cost function; and a fifth step of executing a Monte-Carlo method based on a random positional interchange between the elements to be arranged using the cost function in order of the decreasing temperatures recorded in the schedule list and thereby improving the initial arrangement.
The second step may include a step of extracting all or part of the p functions expressed with the respective p partial functions of the cost function as all or part of the q combination functions. When p is an integer not less tan 3, the second step may include a step of extracting all or part of (2pxe2x88x92pxe2x88x922) functions each expressed as a sum of a combination of not less than 2 and not more than (pxe2x88x921) partial functions of the p partial functions of the cost function as all or part of the q combination functions.
Preferably, the fourth step includes a step of updating the temperature schedule such that a plurality of temperatures having a difference not exceeding a given threshold value therebetween are represented by one of the temperatures.

Method of optimizing placement of elements

Matsushita Electric Industrial Co., Ltd.


Provided are an apparatus of adsorbing solder balls and a method of attaching the solder balls using the same. The solder ball adsorbing apparatus includes a body, a plurality of eject pins disposed in the body and configured to move in downward and upward directions with respect to a substrate on which the solder balls are to be loaded, and a solder ball holder disposed in the body and configured to hold the solder balls at the eject pins and release the solder balls therefrom. The eject pins include a first eject pin disposed at a center of the body in parallel with a vertical surface that is perpendicular to a bottom surface of the body, a second eject pin disposed at an edge of the body at a first angle with respect to the vertical surface, and a third eject pin disposed between the first and second eject pins.

Apparatuses and methods consistent with exemplary embodiments relate to manufacturing a semiconductor package, and more particularly, to adsorbing a solder ball in manufacturing the semiconductor package.
Semiconductor devices are being widely used in various electronic industrial fields due to their characteristics such as miniaturization, multifunction, and/or low manufacturing costs. Also, demands for high integration of semiconductor devices are increased. These demands are no exception to the semiconductor packages. Recently, a distance between pads having the same pitch is expanded according to a molding material and a package structure to cause misalignment of solder balls, resulting in a limitation in electrical connection.

Apparatus for adsorbing solder ball and method of attaching solder ball using the same


DRAM memory device (1) comprising at least one array of memory cells (2, 3, 4, 5), each memory cell (12) being connected to a bit line (BL) and a word line (WL), each of said bit lines (BL) being connected to a sense amplifier and a pre-charge circuit (15); a controllable active-current generator (7, 8, 9, 10) for providing power to the sense amplifiers and pre-charge circuits (15) for a time interval that is limited by a time at which a command for a read or write access is applied to the DRAM memory device (1) and an assigned switching time; a controllable standby-current generator (6) for providing power to the sense amplifiers and pre-charge circuits (15) after the switching time; a control circuit (11) for receiving external data, address and control signals (C, A, D) and for controlling the active-current generator (7, 8, 9, 10) and the standby-current generator (6); wherein the control circuit (11) is adapted to control the time for switching the respective power generator (6, 7, 8, 9, 10) to the sense amplifiers and to the pre-charge circuits (15) subject to an external test mode signal for reducing the overall testing time in a test of the serviceability of the bit lines (BL), sense amplifiers and pre-charge circuits (15).

Random access memories are usually used as the main computer memory to store instructions and data for fast access by the processing units. In those random access devices, the storage elements are organized in a matrix, sometimes also quoted memory cell array, that facilitates short access times which are independent on the location of the data. A memory cell array is made up of a plurality of bit lines and a plurality of crossing word lines. At the crossing points memory cells are located for the actual storage of the binary states 0 and 1 reflected by logic low and high voltage potentials.
RAM devices are classified into volatile and nonvolatile RAM. The volatile RAM comprises static RAM (SRAM) and employs FLIP-FLOP-based latches as storage elements or memory cells, while the so-called dynamic RAM (DRAM) uses a tiny capacitor with two different charge state levels to represent binary information.
FIG. 1 shows an exemplary DRAM memory chip according to prior art. The memory chip M comprises a memory cell array MCA, a row address decoder RAD, a column address decoder CAD, a control CT, an active-current generator AG and a standby-current generator ST. The memory cell array MCA comprises a plurality of bit lines BL and a plurality of word lines WL of which only one of each is shown as an example. At the crossing points of the word and bit lines, a memory cell MC is situated which comprises an access transistor T and a storage capacitor CS. The access or select transistor T is implemented as a switch controlled by a signal on the word line and connects the storage capacitor CS between the respective bit line BL and a reference potential GND which is chosen as ground, here.
The row address decoder RAD is connected to the word lines for selecting the word lines and has for each word line a respective word line driver WLD. The column address decoder CAD is connected to the bit lines and has a sense amplifier and pre-charge circuit SA for each bit line for reading and writing data from and into the memory cells.
The active-current generator AG or the standby-current generator SG serves as a power supply for the sense amplifiers and pre-charge circuits SA. The control CT is connected by a plurality of lines to a control input IC and an address input IA and a data in- and output BD of the DRAM memory chip M for receiving respective control, address and data signals C, A, D. The control CT sends row address signals RA to the row address decoder RAD and column address signals CA and data signals D to the column address decoder CAD. Further, the control CT is adapted to control the active-current generator AG by a respective power control signal PC.
The active-current generator AG is capable of providing relatively high power to the sense amplifiers and pre-charge circuits SA when a read or write operation is initiated. After a predetermined time period, the active-current generator AG sends a timing signal TS to the standby-current generator SG for taking over the power supply to the sense amplifiers and pre-charge circuits SA. The standby-current generator SG provides a relatively low, but sufficient power to the sense amplifiers and pre-charge circuits SA when no read or write process is active in the memory chip M.
A simplified timing scheme of the switching between the active-current and the standby-current generators AG, SG and the voltage characteristics during an exemplary read process from a memory cell MC on a bit line BL. The upper curve shows the time evolution of the voltage VBL, VBLB on a bit line BL with respect to ground, and the lower curve shows the respective time evolution of a voltage at a complementary bit line BLB. The voltages are normalized with respect to the nominal voltage VBLH corresponding to a logic high. In modern memory chips VBLH is for instance 1.8 volts.
At the time t0, a read command, address and control signals are applied to the memory chip inputs IC, IA, BD and brings the chip into an active state. This means, the active-current generator AG is switched on through a respective power control signal PC by the control CT. Usually, a short-delay time t1 passes until the respective word line driver WLD selects a word line and the select transistor T provides connectivity between the storage capacitor CS and the selected bit line BL. During a time interval t2-t1, the charge stored in the storage capacitor CS is distributed between the inherent capacitance of the bit line and the storage capacitor.
Between the times t2 and t3, a respective sense amplifier amplifies the changing voltage generated by the additional charge on the bit line and brings it to the nominal value VBLH. The analog process occurs for a complementary bit line, wherein in case of a written 1 or logic high in the corresponding complementary memory cell, the voltage on the complementary bit line drops through the redistribution of stored charge in the corresponding storage capacitor and is amplified to 0-level. The voltages on the bit line BL and complementary bit line BLB then represent a logic high.
In memory chips M according to the prior art, the active-current generator AG switches itself off after an elapsed time t4 after activation and contemporaneously switches the standby-current generator SG on for providing power to the sense amplifiers and pre-charge circuits. The time t4 is usually in the order of a hundred nanoseconds after activation. The power supply of the sense amplifiers and pre-charge circuits can be switched to the low power standby-current generator, because power is in particular consumed during the amplification phase between t1 and t3. When the active power generators are switched off after t4—mainly due to leakage between neighboring bit lines or other acceptable defects—the voltage at the bit line decreases until a pre-charge operation is executed. During a pre-charge, the respective word line is deselected, i. e. the select transistor de-couples the storage capacitor from the bit line such that the current voltage at t5 or the corresponding charge in the storage capacitor CS is stored in the memory cell. Contemporaneously, the voltage at the bit line is pre-charged to exactly one half of the nominal bit line high voltage VBLH. This time t5 is set to about 80 microseconds complying to industry standards for DRAM memories.
Before delivering memory chips to customers, tests of their proper functioning have to be performed. It is in particular important to test the serviceability of all the bit lines and their respective sense amplifiers and pre-charge circuits. This is usually done by writing a state into the memory cell and waiting a significant time after the active-current generator is switched off. Then, at a time t5 a pre-charge is executed and then the written data into the respective memory cell is read out and compared to the test data. If the bit line sense amplifier and pre-charge circuit works properly, both data, the test data and read-out data are the same. However, should there occur any significant and undesired leakage between bit lines or sense amplifiers are defective, the written test data and read-out data differ from each other.
However, this method of testing the serviceability of the bit line infrastructure in a memory chip according to the prior art has a major disadvantage: for every bit line to be tested, a minimum amount of time of t4 has to be invested until the decrease of the voltage on a bit line can be detected in a test by repeated read-outs of the test data. Since such lengthy chip testing deteriorates the throughput of a DRAM memory device production, faster test methodes are desired.

Method for testing the serviceability of bit lines in a DRAM memory device