An access circuit selectively couples an externally accessible terminal to each of a plurality of isolated DRAM wells in which respective DRAM arrays are fabricated. The access circuit for each well includes first and second transistors fabricated in respective wells coupled between the externally accessible terminal and a respective one of the DRAM wells. The well of the first transistor is coupled to the externally accessible terminal, and the well of the other transistor is coupled to a respective DRAM well. A control circuit applies select signals to gate electrodes of the first and second transistors. The control circuit includes respective shunt transistors that shunt the gate electrodes to the source regions of the first and second transistors when the transistors are turned off to isolate the respective DRAM wells from the external terminal regardless of the magnitude and polarity of a test voltage applied to the externally accessible terminal.

With reference to FIG. 1, a semiconductor structure 10 includes a substrate 12 having formed therein a well 14, which is a region of the substrate 12 that is doped oppositely to the doping of the substrate 12. For example, the substrate 12 of FIG. 1 is a p-type substrate. A deep n-type well 16 is implanted into the substrate 12 to form a buried layer. A surface n-well in areas 18, 20 surrounds the buried layer n-type well 16 to form a doughnut shape where the center is a p-type well 14 that is now completely isolated from the substrate 12, thus allowing a separate bias voltage. Various semiconductor devices can be fabricated into the well 14, such as an n-channel transistor 22. In practice, a large number of semiconductor devices can be fabricated into the well 14 to form an integrated circuit.
The junction between the well 14 and the deep n-well 16 forms a p-n junction or diode 24 that is schematically illustrated in phantom in FIG. 1. A similar diode 26 is formed by a p–n junction between the deep n-well 16 and the p-type substrate 12. The diodes 24, 26 are inherently formed with a back-to-back connection, thereby isolating the p-well 14 from the substrate 12, and, therefore, from other devices that are also fabricated into the substrate 12. The p-well 14 is often biased to a negative bias voltage, which is often provided by a negative voltage charge pump, commonly known as a Vbb charge pump. By fabricating the memory cell arrays in respective wells, each of several array wells can be isolated from each other and from other circuitry fabricated in the substrate 12. Similar diodes (not shown) are formed by the p–n junctions between the n-wells 18, 20 and both the p-well 14 and the substrate 12. However, the diodes are inherently coupled to each other back-to-back to isolate the p-well from the substrate 12. In practice, the n-wells 18, 20 are typically biased to a relatively large positive voltage, such as a supply voltage VCC or a positive pumped voltage VCCP, to maintain the diodes reverse or back-bias.
As explained above, fabricating integrated circuits into the wells also allows the wells 14 to be biased to a voltage that enhances the performance of integrated circuits fabricated in the wells 14. For example, it is common to bias the wells 14 in which DRAM arrays have been fabricated to a negative voltage, which reduces the leakage of access transistors (not shown) coupled to respective DRAM memory cells. As is well known in the art, reducing access transistor leakage allows the memory cells to store data for a longer period to reduce refresh rates. However, it is desirable to perform post-fabrication testing of the integrated circuit under "worst case" conditions for the purpose of detecting failures that are likely to occur after the integrated circuit is placed in service. Again using the example of DRAM arrays, it is desirable to test the data retention time of a DRAM array fabricated in the well 14 with the well 14 biased to ground voltage. If the data retention time is achieved with the well 14 biased to ground or a less negative voltage, then it will inherently do so when the well 14 is biased to a more negative voltage during operation. The test voltage can be applied to the well 14 from an externally accessible terminal 30. To allow the terminal 30 to be used for other purposes during use of an integrated circuit fabricated in the substrate 12, the terminal 30 is preferably coupled to the well 14 through a transistor 34 fabricated into the substrate 12.
FIG. 2 shows a semiconductor structure 40 in which a p-type well or core 42 is fabricated in a substrate 44, and a DRAM array is 46 fabricated in the p-type core 42. Like the p-well 14 of FIG. 1, the core 42 is isolated from the substrate 12 by n-wells 18, 20 (not shown in FIG. 2) and the deep n-well 16. The core 42 is coupled through a p+region 47 to an externally accessible terminal 48 through an n-channel transistor 50. The transistor 50 is fabricated in a p-type well 52 in which first and second n-type source-drain regions 56, 58 are fabricated. The p-well 52 is also isolated from the substrate 12 by n-wells 18, 20 and the deep n-well 16. A gate electrode 60 is fabricated between the source-drain regions 56, 58 and is insulated from the well 42 by a gate insulating layer 62 to form an MOS device. The externally accessible terminal 48 is connected to the first source-drain region 56 The second source-drain region 58 is connected to the well 52 through a p+ region 54 that is more positively doped than the doping of the p-well 52 and to the core 42 in which the array 46 is fabricated through a similar p+ region 55. As is well-known in the art, coupling the terminal 48 to the well 52 and to the core 42 through p+ regions 54, 55, respectively, reduces the resistance of the contact with the well 52 and to the core 42. As explained above with reference to FIG. 1, the junction between each p-type region and each n-type region forms a diode, one of which 68 is shown in phantom in FIG. 2. The significance of this diode 68 will be explained with reference to FIG. 3. There is also a diode created by the junction between the n-type source-drain region 58 and the p-type well 52, but since this diode would be shorted out by the direct connection between the region 58 and well 52, it is not shown in FIG. 2.
In operation, the transistor 50 isolates the externally accessible terminal 48 from the core 42 during normal use of an integrated circuit, such as a DRAM device, fabricated in the substrate 44. During this time, the core 42 can be biased to a negative voltage while the substrate 44 remains at ground potential. When the array 46 is to be tested under "worst-case" conditions, a positive voltage is applied to the gate electrode 60 by suitable means to form a conductive n-type channel between the source-drain regions 56, 58. The transistor 50 then couples the externally accessible terminal 48 to the core 42 so that a positive test voltage can be applied to the core 42 through the terminal 48. A negative test voltage can also be applied to the core 42 through the terminal 48 when the transistor 50 is turned ON. However, if the negative test voltage is more than about 0.6 v less than the voltage to which the core 42 is biased by a Vbb charge pump (not shown in FIG. 2), the diode 68 will be forward biased. As a result, the core 42 will be coupled to the externally accessible terminal 48 regardless of the conductive state of the transistor 50.
The problem caused by the diode 68 becoming forward-biased by a negative test voltage will now be explained with reference to FIG. 3. FIG. 3 shows a portion of a DRAM device 70 having two DRAM cores 72, 74 coupled to respective Vbb charge pumps 76, 78. The cores 72, 74 are also coupled to an externally accessible terminal 80 by respective transistors 82, 84, each of which is controlled by a respective select signal, Sel. A and Sel. B, respectively. The diodes 68 coupled between the source-drain regions 56, 58 (FIG. 2) of the transistors 82, 84 are also shown in FIG. 3. Although the DRAM device 70 is shown in FIG. 3 as having two DRAM cores 72, 74, it will be understood that other DRAM devices can have a large number of DRAM cores.
During testing of the DRAM device 70, it is desirable to individually test the operation of each of the cores 72, 74 without affecting the operation of the core not being tested. For example, it is desirable to be able to apply a negative or positive test voltage to the terminal 80, and then individually turn ON each of the transistors 82, 84 to couple the test voltages to the respective cores 72, 74. However, when a test voltage is applied to the terminal 80 that is significantly more negative than the bias voltages being supplied to the cores 72, 74 by the Vbb charge pumps 76, 78, the OFF transistor 82, 84 will effectively be rendered conductive by the diode 68 becoming forward-biased. For example, when the Sel. B signal is driven high to turn ON the transistor 84, a large negative test voltage can be applied to the core 74 from the terminal 80. However, this test voltage will also be applied to the core 72 through the diode 68 formed in parallel with the transistor 82. For this reason, it is not possible to adequately test the cores of an integrated circuit using the circuitry shown in FIG. 2, since a large negative voltage cannot be applied to the individual cores. There is therefore a need for a circuit and method that would allow integrated circuit cores to be individually tested with relatively large negative and positive test voltages.

Access circuit and method for allowing external test voltage to be applied to isolated wells


A gaming method is disclosed and comprises the following steps, which need not necessarily be performed in the exact order: providing at least two card representations to a player, each card representation comprising a symbol, the symbol having a corresponding predetermined value; providing at least two card representations to a dealer, each card representation comprising a symbol, the symbol having a corresponding predetermined value; evaluating a blackjack game outcome by comparing the values of the player and the dealer's card representations, wherein the player wins the blackjack game if the sum of the predetermined values of the player's card representations is higher than the dealer's; using two of the player's card representations for a game of poker; using two of the dealer's card representations for a game of poker; defining values for a plurality of combinations of two card representations; and evaluating a poker game outcome based on the player and the dealer's two card representations, wherein the player wins the poker game when the player possesses a two card combination that has a higher predetermined value than any of the dealer's two card combination.

Conventional betting games, such as slot machines, video poker games, and various table games, such as roulette, blackjack, poker, and craps, are the main attractions of casinos and gambling places like Las Vegas, as they have been for many years. Many casino patrons enjoy playing these conventional betting games for many reasons, including the patrons may have developed what they believe to be winning techniques or strategies; they may have become accustomed to the frequency and size of the awards; or, they may have become very well accustomed with the rules. Some of these casino patrons desire some change in these games to add flavor and excitement to these old games and to add new challenges to their gaming experiences. The applicant has discovered ways to modify existing blackjack and poker games in a manner that the applicant believes preserves the attractiveness and familiarity of players with conventional blackjack and poker games while at the same time providing the flavor, excitement, and challenge that casino patrons seek.
Several patents and patent applications disclose modifications to the conventional games of blackjack and poker. For instance, U.S. Patent Application Publication number US 2004/0000758 of Yurkins appear to disclose a game that combines blackjack and poker. The Yurkins patent application involves the players being invited to play either blackjack, poker, or both games, and the players who have opted to play poker are given a total of five cards.
At least one problem with the game disclosed in Yurkins is that it requires the dealer to use substantially more cards than the conventional blackjack game. In the game of blackjack, players often seek high cards, such as kings, jacks, queens, tens, and aces, for their two initial cards to maximize their chances of having two initial cards with the highest possible predetermined value, or to minimize the chances of having to "hit" or obtain an additional card and "busting" or exceeding twenty one. Some players may feel that high cards are being used up quickly in the game of Yurkins, which makes the game of blackjack more favorable to the house. A modified blackjack and poker game that uses fewer cards than the card consumption in Yurkins is desired.
Another problem with the game of Yurkins is that it utilizes five cards to play poker. Blackjack players who are not familiar with conventional five card poker combinations, such as straight, flush, royal flush, and full house, may feel disinterested in learning a game that is substantially different from blackjack. A blackjack/poker game combination that does not require players to be able to form or evaluate conventional five card poker combinations, such as straights, flushes, full house, or variations thereof, is desired.
Yet another problem with the game disclosed by Yurkins is that dealers have to evaluate substantially more winning combinations than the winning combinations involved in conventional blackjack. Thus, Yurkins's game appears to require that the dealers be trained in evaluating both blackjack and five card poker combinations. This poses additional operating cost or overhead expenses to casino operators. Yurkins's game may also require casino operators or dealers to take extra time during each game to evaluate the outcomes of blackjack plus the five card poker. A modified blackjack and poker game that allows dealers to move quickly from one game to another is desired.
Another blackjack/poker combination is disclosed in U.S. Pat. Nos. 6,854,733, 6,012,719, and 6,523,831, which are all issued to Webb. Webb discloses a three card poker and blackjack combination wherein the poker hand consists of two cards that the player obtains from playing blackjack and the card of the dealer that is shown to the player. Webb provides certain definitions of winning three card hands and losing three card hands. Like the problem with the game of Yurkins, the dealers executing the games of Webb may have to be trained with the definitions of winning three card hands and losing three card hands. The dealers may have to take extra time during each game to evaluate the outcomes of blackjack and the three card poker.
From the players' perspective, players may have to get acquainted with these definitions as well. Some players may find the definitions of winning three card hands and losing three card hands overwhelming, and they may be hesitant to learn them. A blackjack/poker game combination that allows both players and dealers to quickly learn and understand the game is desired. Finally, a blackjack/poker game combination that does not substantially have the disadvantages of the references cited above is desired.


A lens barrel for holding an optical lens system including a molded plastic lens having decentering eccentricity is provided with a location and joining mechanism that places the plastic lens with a desired axial position with an optical axis coaxial with a geometric axis and secures the plastic lens to the barrel. The locating and joining mechanism includes three axial projections extending from the plastic lens at regular intervals on a circle with a specified radius and three groups of locating members, each group including three sets of axial bores in the barrel disposed at regular intervals on a circle with the specified radius. The bores of a set have equal depth. Each set has a different depth. Circles of the locating members have different centers. The projections are fitted in the bores selected for axial position adjustment of the lens and selected for coaxial adjustment of the lens.

1. Field of the Invention
The present invention relates to a lens barrel of a type capable of fixedly holding a plastic lens in a location where the plastic lens is placed in a desired axial position and an optical axis of the plastic lens is substantially coaxial with a geometric axis of the lens barrel.
2. Description of Related Art
There has been known a projector equipped with a projection lens system for enlarging and projecting an image modulated by an image display element on a remote screen The projection lens system is capable of changing its magnification power by shifting an axial position of a front lens (a distance between a front lens and a neighboring lens). Since it is common to use a super-wide-angle lens for the front lens, a plastic lens, that can be comparatively easily manufactured at low costs by molding even though it is complicated in shape, is often used for the front lens.
Conventionally, in incorporating the projection lens system in a lens barrel, the front lens is adjusted in an axial position by inserting a spacer having an appropriate thickness, which is selected from spacers different in thickness, between a back face of the front lens and a bearing wall of the lens barrel. However, it is troublesome and expensive to always have a stock of various thickness of spacers ready.
In order to skirt around this advantage, it has been proposed in Unexamined Japanese Patent Publication Nos. 2002-350702, 2004-212822 and 2005-49599 to adjust an axial position of a lens element by selectively using a plurality of shoulders different in axial position which are formed in either one of the lens element or a lens holder for the lens element and a bearing wall of a lens barrel. Further, it has been proposed in Unexamined Japanese Patent Publication No. 10-319291 to incorporate an adjuster ring having locating means between a back face of a lens element and a bering wall of a lens barrel. The locating means comprises a plurality of axial projections extending from the back of the lens element and a multiple sets of locating recesses different in axial depth by set so that when placing the lens element in a desired axial position in the lens barrel, the adjuster ring is turned so as to receive the axial projections by an appropriate set of locating recesses having an appropriate axial depth.
Meanwhile, injection molding is commonly used to manufacture plastic lenses. However, the problem encountered by such a plastic lens is that a molded plastic lens possibly has eccentricity, i.e. a deviation of a geometric axis decentered from an optical axis of the plastic lens, due to dimensional differences of the molded plastic lens from a design specification which occur depending upon marginal production accuracy of a molding die. In particular, when using a multi-molding die having a plurality of molding cavities, plastic lenses molded by the multi-molding die are apt to have eccentricity different from one another according to the molding cavities.
When incorporating such a plastic lens having eccentricity into a lens barrel, the problem encountered by the plastic lens is that it is hard to bring an optical axis of the plastic lens almost coaxial with a geometric axis of the lens barrel in the case where the technique of axial lens position adjustment described in Unexamined Japanese Patent Publication No. 2004-212822 or No. 10-319291, or that, it is possible but somewhat troublesome to bring an optical axis of the plastic lens almost coaxial with a geometric axis of the lens barrel in despite of the capability of axial adjustment in the case where the technique of axial position adjustment of a lens described in Unexamined Japanese Patent Publication No. 2002-350702 or No. 2005-49599 2004-212822. In addition, since it is essential to fixedly hold the plastic lens in the lens barrel with an adhesive, it is hard to remove the plastic lens from the lens barrel after having been incorporated in the lens barrel once. If using a projection lens system including a lens element whose optical axis remains decentered from a geometric axis of a lens barrel, the projection lens system entails quality deterioration of an image projected thereby.


A method and apparatus for utilizing satellite update information are disclosed. In the preferred embodiment satellite update information, comprising satellite position, polarity, name, and abbreviation, are accumulated at a first location and transmitted via satellite to at least one of a plurality of satellite receivers. The satellite receiver is operable to receive and automatically utilize the satellite update information such that the end user of the satellite receiver in unaware of the automated process of updating satellite information in the satellite receiver. The satellite receiver uses a portion of the satellite update information to calculate a pulse count for positioning an antenna to receive radio signals from a satellite for which satellite update information has been received.

Satellite broadcast systems have been in operation for many years. In a typical system, an uplink site transmits a radio signal to a satellite which receives the radio signal and then retransmits the radio signal towards Earth. The retransmitted radio signal is received at a downlink site, thereby completing the satellite radio broadcast transmission.
The antennas used at both the uplink and downlink sites utilize very high signal gain and narrow directivity due to the long transmission distances and the relatively low transmission powers involved in such systems. The directivity of these antennas also provide for selectivity between satellites which are operating at or near the same frequency band and which are spaced relatively near one another.
The aforementioned radio signals are typically modulated with information. Audio, video, and data information are commonly transmitted. Often times a given satellite receives and transmits one or more of these three types of information simultaneously.
Satellites are classified by the altitude at which they orbit Earth. Correspondingly, the altitude at which a satellite orbits determines the period of its orbit around Earth. A certain class of satellites, which are stationed at an altitude above earth such that the satellite's period of orbit is equal to the earth's orbital period and which are located at a zenith with respect to a point along the Earth's equator, are called geosynchronous orbit satellites. Or, geosynchronous satellites. Geosynchronous satellites are advantageous because they appear to be stationary from earth and they allow a downlink site with a fixed position antenna to continuously receive radio signals without a need to track any relative movement between the satellite and Earth.
International agreement and United States federal law have provided for the operation of a plurality of geosynchronous satellites which receive and rebroadcast television receive-only (TVRO) signals. These satellites operate in the C and Ku frequency bands. The C-band operates at uplink frequencies in the 6 GHz range and downlink frequencies in the 4 GHz range, the Ku-band operates at uplink frequencies in the 14 GHz frequency range and downlink frequencies in the 12 GHz range. In some types of satellite systems, other frequency bands may be used. End users who operate TVRO downlink sites are enabled to receive TVRO signals.
Each of the C-band and Ku-band TVRO satellites employ several transponders, usually twenty-four in C-band and 32 in Ku-band, that each have a given operational bandwidth, usually 36 MHz. In operation, each of the transponders can be viewed as a separate satellite radio channel. The frequencies of operation of each of the transponders are distinct from others on a given satellite, however, the range of frequencies covered by all the transponders in any given geosynchronous satellite are usually contiguous. In order to improve the isolation of adjacent transponder signals in a given satellite, satellite designers employ the use of orthogonal signal field polarity between transponders that are adjacent in frequency. An arbitrary use of the horizontal and vertical electric signal field polarity descriptors used in terrestrial radio systems is used in satellite systems. Therefore, every-other transponder in most geosynchronous satellites has a vertical electric field polarity and the alternate every-other transponder has a horizontal electric field polarity, the two polarities being orthogonal to one another. This scheme is typically used in C-band satellites and sometimes used in Ku-band satellites. Ku-band satellites do not necessarily alternate between the vertical and horizontal polarities. However, other polarization formats may be used, circular polarization for example.
In a further use of signal isolation through polarity management, separate satellites that are adjacent to one another in orbit are sometimes given opposite polarities with respect to each transponder starting with the first, or the number one, transponder. Thus, if the first transponder in a given satellite has a vertical polarity, then that satellite is said to have a normal polarity. Alternatively, if the first transponder in a given satellite has horizontal polarity, then that satellite is said to have an inverse polarity.
By definition, all geosynchronous satellites orbit directly above the equator and therefore, each satellite's location can be defined by its position in degrees of longitude. Satellites useful for broadcast to the continental United States and other territories are located from about 69 degrees west to 139 degrees west longitude.
As a practical matter, satellites do not stay at a precise location, but rather tend to drift slightly in their relative position with respect to each and the earth. Further, satellites have a finite life span and need to be decommissioned and replaced from time to time. Also, new satellites are occasionally added to the geosynchronous orbit so that total channel capacity can be increased. Also, sometimes a satellite is decommissioned without being replaced. Sometimes, a replacement satellite will have the same characteristics as the satellite it replaces. Other times, the replacement satellite may be located at a different angle of longitude or have the opposite polarity of the satellite it replaced.
In order for a TVRO satellite receiver to properly receive satellite signals, it must have information about the position of the satellite, the polarity of the satellite, and the frequency of operation of the satellite. Further, in order for the selection of satellite signals and programming choices to be convenient and useful to an end user, the satellites are given names and abbreviations so that program guides, user interfaces displays and in other instances, the particular satellites can be identified.
When a TVRO satellite receiver is initially installed at an end user's downlink site, a service technician, who is skilled in things related to satellite downlink sites and receivers, usually installs the equipment and programs a memory in the satellite receiver with the satellite information for the various satellites from which signals are to be received. However, as changes occur in the satellite information for the reasons described above, it is necessary to provide satellite update information to the satellite receiver in order to keep the satellite memory programmed with current satellite information so that the end user can receive all desired satellite radio signals.
The loading of satellite update information into a memory in the satellite receiver poses a problem to the end user. First the end user must make himself aware of the need to add satellite update information, then the user must manually program such satellite update information into the memory of the satellite receiver. Clearly there is a need to streamline and automate the process of maintaining and entering satellite update information into a satellite receiver.


A coil assembly includes a first magnetic mother board, and a second magnetic mother board. A coil is formed on the first magnetic mother board and composed of stacked coil conductors and insulating layers. A recess or groove is formed in the second magnetic mother board and has a shape corresponding to the shape of the coil. The coil is closely fit into the recess so as to insure connection of the first and second magnetic mother boards. Direct connection of the first and second magnetic mother boards provides a completely closed magnetic path. The insulating layers have no magnetic materials so as to provide a better electromagnetic connection.

1. Field of the Invention
The present invention relates to a coil assembly, particularly a coil assembly used as a transformer, an inductor or other components.
2. Description of the Related Art
A conventional coil assembly is shown in FIG. 10. Specifically, a coil assembly 41 includes a core 42 and a wire 43 wound around the core 42. The core 42 has a rectangular base. The wire 43 has ends connected to respective external terminals 44 which, in turn, are attached to the rectangular base of the core 42.
FIG. 11 shows another coil assembly known in the art and made from stacked green sheets. Specifically, a coil assembly 51 includes stacked green sheets made of a magnetic material, and a plurality of coil conductors 52a, 52b, 52c, and 52d provided on the surface of the stacked green sheets. Two external electrodes 56 and 57 are attached to the green sheets after the green sheets are integrally sintered. The green sheets include via holes through which the coil conductors 52a to 52d are electrically connected in series to form a coil 52.
FIG. 12 also shows a conventional coil assembly 61 which includes a coil 62 composed of stacked green sheets and including coil conductors, and two magnetic cores 63 and 64 between which the coil 62 is sandwiched. The green sheets are made of an insulating material and have no magnetic material.
Of these, the coil assembly 41 shown in FIG. 10 is low in productivity and is costly since it is necessary to wind the wire 43 around each core 42. It is also necessary to solder or otherwise electrically connect the wire 43 and the external terminals 44 together because these two parts are made of different materials. This connection is required for each coil assembly. The coil assembly 41 can not be made into a compact arrangement since it is difficult to handle the core 42 and the wire 43 if they are small.
The coil assembly 51 shown in FIG. 11 is high in productivity and is easy to handle as the coil conductors 52a to 52d can be formed by a printing or photolithographic process and major parts can be incorporated into the board. The coil assembly 51 can also be made into a compact arrangement since the coil conductors 52a to 52d are thin and fine. However, the electric property of the coil assembly 51 varies based on the degree of contraction of the magnetic green sheets during sintering process. Also, a closed magnetic path is formed in each of the magnetic green sheets, thereby deteriorating the electromagnetic property of the coil 52. Particularly, when the coil assembly 51 is used as a transformer, such closed magnetic path weakens the electromagnetic coupling between the coils and deteriorates the performance of the coil assembly.
The coil assembly 61 provides a better electromagnetic property as the insulating green sheets forming the coil 62 have no magnetic material. This assembly, however, requires a separate effective magnetic path. It is thus necessary to provide the magnetic cores 63 and 64. This results in a reduction in the productivity of the coil assembly 61. It is known to form a magnetic path by printing or otherwise applying a resin mixed with magnetic powder to encase the coil 62, each of the thus formed magnetic cores 63 and 64 having rugged mating surfaces. The resulting resinous material has a magnetic permeability one hundredth to one ten thousandth that of the magnetic material per se and can not provide an effective magnetic path.


Liquid hydrocarbon lubricant viscosity index improver compositions are disclosed having high shear stability. The compositions comprise the homopolymer or copolymer product of the oligomerization of C.sub.3 to C.sub.5 alpha-olefin or mixtures thereof, with or without ethylene as co-monomer. The process is carried out under oligomerization conditions in contact with a reduced valence state Group VIB metal catalyst on porous support. The viscosity index improver of the invention has a regio-irregularity of at least 20%, weight average molecular weight between 6,000 and 30,000 and molecular weight distribution between 2 and 5.

Efforts to improve upon the performance of natural mineral oil based lubricants by the synthesis of oligomeric hydrocarbon fluids have been the subject of important research and development in the petroleum industry for at least fifty years and have led to the relatively recent market introduction of a number of superior polyalpha-olefin (PAO) synthetic lubricants, primarily based on the oligomerization of alpha-olefins or 1-alkenes. In terms of lubricant property improvement, the thrust of the industrial research effort on synthetic lubricants has been toward fluids exhibiting useful viscosities over a wide range of temperature, i.e., improved viscosity index (VI), while also showing lubricity, thermal and oxidative stability and pour point equal to or better than mineral oil. These new synthetic lubricants lower friction and hence increase mechanical efficiency across the full spectrum of mechanical loads from worm gears to traction drives and do so over a wider range of operating conditions than mineral oil lubricants.
In accordance with customary practice in the lubricant arts, PAO's have been blended with a variety of additives such as functional chemicals, oligomers and high polymers and other synthetic and mineral oil based lubricants to confer or improve upon lubricant properties necessary for applications such as engine lubricants, hydraulic fluids, gear lubricants, etc. Blends and their additive components are described in Kirk-Othmer Encyclopedia of Chemical Technology, third edition, volume 14, pages 477-526, incorporated herein in its entirety by reference. A particular goal in the formulation of blends is the enhancement of viscosity index (VI) by the addition of VI improvers which are typically high molecular weight synthetic organic molecules. Such additives are commonly produced from polyisobutylenes, polymethacrylates and polyalkylstyrenes, and used in the molecular weight range of about 45,000 to about 1,700,000. While effective in improving viscosity index, these VI improvers have been found to be deficient in that the very property of high molecular weight that makes them useful as VI improvers also confers upon the blend a vulnerability in shear stability during actual applications. This deficiency dramatically reduces the range of usefulness applications for many VI improver additives. VI enhancers more frequently used are high molecular weight acrylics. Their usefulness is further compromised by cost since they are relatively expensive polymeric substances that may constitute a significant proportion of the final lubricant blend. Accordingly, workers in the lubricant arts continue to search for additives to produce better lubricant blends with high viscosity index. However, VI improvers and lubricant mixtures containing VI improvers are preferred that are less vulnerable to viscosity degradation by shearing forces in actual applications. Preferred liquids are those that exhibit Newtonian behavior under conditions of high temperature and high shear rate, i.e., viscosities which are independent of shear rate.
Recently, novel lubricant compositions (referred to herein as HVI-PAO and the HVI-PAO process) comprising polyalpha-olefins and methods for their preparation employing as catalyst reduced chromium on a silica support have been disclosed in U.S. patent applications Ser. No. 210,434 and 210,435 filed Jun. 23, 1988, now U.S. Pat. Nos. 4,827,064 and 4,827,023 to M. Wu, incorporated herein by reference in their entirety. The process comprises contacting C.sub.6 -C.sub.20 1-alkene feedstock with reduced valence state chromium oxide catalyst on porous silica support under oligomerizing conditions in an oligomerization zone whereby high viscosity, high VI liquid hydrocarbon lubricant is produced having branch ratios of less than 0.19 and pour point below -15 .degree. C. The process is distinctive in that little isomerization of the olefinic bond occurs compared to known oligomerization methods to produce polyalpha-olefins using Lewis acid catalyst. Their very unique structure provides opportunities for the formulation of superior lubricant blends.
Considering the abundance of C.sub.2 to C.sub.5 alpha-olefins in the petroleum refinery, and their low cost, it has long been been recognized that they could be a preferred source of low cost lubricant if they could be oligomerized to provide high viscosity index lubricant in good yield with a manageable, regenerable, non-corrosive catalyst such as reduced chromium on porous support as taught in the foregoing patents to M. Wu. These objectives are taught and reached in the process and compositions of U.S. Pat. No. 4,990,709. The products of the process taught in U.S. Pat. 4,990,709 exhibit a very unique structure that confers upon the products the properties of novel compositions. In conventional Ziegler oligomerization of alpha olefins it is well known in the art that the oligomers produced contain a high degree of structural regularity, or regio-regularity, as exhibited by a preponderance of head-to-tail bonding in the oligomerization of these alpha olefins. In the products from Ziegler catalyzed oligomerization not more than twenty percent of the repeating units are linked by head-to-head and tail-to-tail bonding. In the olefin oligomers produced from the reduced metal oxide catalysts taught in the patents to M. Wu it has been found that at least forty percent of the repeating units are bonded by head-to-head or tail-to-tail connections. The oligomers contain not more than 60% regio-regularity, where 100% regio-regularity corresponds with all head-to-tail connections for the recurring oligomeric unit. At least twenty percent of the repeating units are bonded by irregular head-to-head or tail-to-tail connections. These oligomers have a regio-irregularity of at least twenty percent, usually from 20 to 40 percent, and in most cases, not more than 60 percent.
Accordingly, it is an object of the present invention to provide novel, low viscosity lubricant VI improver compositions having high viscosity index and shear stability from alpha-olefins.
It is a further object of the present invention to provide novel lubricant basestock blends from low viscosity, high viscosity index C.sub.2 -C.sub.5 copolymers or homopolymers in conjunction with synthetic and natural petroleum lubricant.

C.sub.2 -C.sub.5 olefin oligomer compositions as shear stable viscosity index improvers


A method and system are described for estimating resource provisioning. An example method may include obtaining a workflow path including an external invocation node and respective groups of service nodes, node connectors, and hardware nodes, and including a directed ordered path indicating ordering of a flow of execution of services associated with the service nodes, from the external invocation node, to a hardware node, determining an indicator of a service node workload based on attribute values associated with a service node and an indicator of a propagated workload based on combining attribute values associated with the external invocation node and other service nodes or node connectors preceding the service node in the workflow path based on the ordering, and provisioning the service node onto a hardware node based on combining the indicator of the service node workload and an indicator of a current resource demand associated with the hardware node.

Enterprise business software companies are increasingly altering the architecture of their software products in order to provide greater flexibility for corporations or other users of their systems. Conventional business software may include a layered architecture design, for example, a three-layer architecture which may include a database layer, application server layer and user interface layer. However, more recent business software may be designed based on a Service Oriented Architecture (SOA).
There are a number of differences between a layered architecture and a SOA. For example, a layered architecture may be constructed using server silos wherein a single software layer such as a database may be maintained on a single hardware resource or a cluster of resources. Tight coupling of entire software layers to hardware resources may thus be a characteristic of example layered architectures.
In contrast, an SOA may provide system functionality distributed over many software services that each provide their own programming interface for inter-communication with other services. Since software services encapsulate functionality at a much greater level of granularity they may provide looser-coupling and higher flexibility than a layered architecture. Such a system may be generated based on an orchestration of all services combined into workflows. Services in themselves may be layered but this may be considered unimportant to the overall system as only the service interface may be exposed to the system.
Characteristics that may determine hardware resource provisioning on a system based on SOA may be much more complex than that of a typical layered architecture because of the higher numbers and granularity of services in the SOA approach. However, resource provisioning for a SOA may be equally as important as resource provisioning for a layered architecture. Thus, it may be desirable to provide techniques which may improve estimates for resource provisioning of architectures such as service oriented architectures.

Method and system for estimating resource provisioning


A peripheral bus error containment and recovery system enables a bus device to experience a fatal bus error and recover without stopping execution of an operating system. When a fatal bus error is detected at the bus device, a bus controller may deactivate a data link layer for a downstream port populated by the bus device, causing an operating system device driver to be uninstalled for the bus device. Then, the operating system device driver may be reinstalled without physically removing the bus device.

Field of the Disclosure
This disclosure relates generally to information handling system displays and, more particularly, peripheral bus error containment and recovery.
Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Many information handling systems include peripheral buses in the system architecture. A peripheral bus enables connectivity to external devices, such as plug-in cards, thereby providing a hardware expansion mechanism for the information handling system. Accordingly, peripheral buses may be supported by corresponding software architecture, including support by an operating system executing on the information handling system. One common example of a peripheral bus is a Peripheral Component Interconnect (PCI) bus, which has been used in information handling systems for many hardware and software generations. A current version of the PCI bus is the PCI Express (PCI-E) bus.
When an error occurs at a PCI device, certain error messages may be sent to the operating system for handling. In some instances, error messages from PCI devices result in a non-maskable interrupt (NMI) that stops operation of the information handling system, which is undesirable.

Peripheral bus error containment and recovery


A system and method are provided for informing business management personnel of business risk. The method can include the operation of defining a plurality of business risk rules that are tied to specific risk events and information. The plurality of business risk rules can be stored in encapsulated data points. Another operation is defining predicate risk rules and core risk rules for the business risk rules in the data points. A query can be made of whether predicate risk rules in a section of data points are satisfied using the predicate risk rule in a core data point. The core risk rules for the core data points can be applied after predicate risk rules for the core risk rule have been satisfied. A further operation is displaying a graphic icon to an end user for core risk rule status representing whether a core risk rule has been satisfied.

In today's business marketplace, each ongoing business entity desires to manage the risks and possible losses associated with its business, regardless of the business size. Certainly there are risks associated with operating a smaller business but the risks tend to multiply as the size of a business increases. Not only do the risks increase as the relative size of the business increases but the possibility of loss is also multiplied because of the widespread operations of larger businesses. In fact, some business consultants believe that reducing or avoiding losses can be just as important as working on generating profits.
In addition to managing simple risk and loss, there are many other complex issues in today's business world that complicate the management of risk factors. Of course, there is the possibility of the simple loss of profits or merchandise damage, but there are also government rules and regulations that can apply to businesses. For example, some businesses are at risk that governmental regulators could shut down the business or that large fines could be accrued for misdeeds. In addition to governmental regulation, there is also the risk of loss through litigation or other similar legal means. Other risks that contribute to the overall risk analysis for a business are safety concerns, environmental quality, product quality, product liability, insurance, bonding, employee misdeeds, security clearances, disadvantaged business compliance, and similar risks that can be considered by the operating executives or owners of businesses. Furthermore, there are other extraneous risks that need to be assessed and managed such as acts of nature, explosions, fire, and computer failure.
In the past, businesses and corporations have been able to manage this risk by applying specific policies or training rules to their employees to minimize business risks. These policies and rules have included specific types of training, certifications, management and/or monitoring to avoid identified risks. In addition, companies have been able to purchase insurance to cover their own internal risks.
During recent years, many companies have outsourced various functions to third party suppliers or independent contractors. This shift has occurred in part because of the focus of many companies on their core competencies, as opposed to the vertical integration favored in the past. Unfortunately, it is difficult for a company to directly control the behavior of a supplier or independent contractor. For example, a relationship with a supplier or independent contractor can include an inherent level of risk in the following areas: regulatory compliance, insurance expiration, supply interruptions, citation histories, bonding, financial stability, environmental performance, safety reporting, quality performance, employee testing, security, and licensing. Notwithstanding the difficulty in managing the risk created by using outside suppliers, companies desire to manage the risk because this risk flows back to the customer or company.
A larger company may hire a smaller contractor to do a specific job that has inherent risks. Previously, the company may have had this service provided by its own employees and the employees would have been reasonably trained, tested, and appropriately bonded or insured. However, a small supplier or independent contractor who is providing products or services to a larger company may not take these types of precautions. Then when an accident occurs, the larger company or customer may be liable in litigation for problems or accidents resulting from the services or products.
For instance, a petroleum company may hire a welding supplier to work on the petroleum company's oil pipeline system. This welding supplier may be a small welding company that is locally owned or operated. If this welding company hires a welder who is untrained, uninsured, or has a substance abuse problem, then an accident may occur. The welding accident on the oil pipeline might produce an explosion that kills innocent bystanders. Thus, the petroleum company will almost certainly be named in, and may ultimately be held responsible for the resulting litigation that comes from the entire matter, even though the services were provided by an independent supplier.
When a relationship is formed between a customer company and a supplier, at least one contract is typically signed between them. Larger companies typically require the contract with the supplier to include certain terms, conditions, and compliance with government regulations. The terms, conditions, and applicable regulatory provisions that are included in these contracts are quite detailed and can run into the range of hundreds of pages of contract requirements. Once the supplier has agreed to a set of extensive terms, conditions, and applicable government regulations, the customer company is left in the position of determining whether there is actual compliance with all the provisions.
The typical way in which companies have attempted to determine whether a supplier is in compliance with the terms, conditions, and applicable regulations of the contract is to perform further due diligence and research about compliance. For example, a long form or document with questions may be sent to the supplier and the supplier can be asked to disclose an extensive list of information to the customer. It is not atypical for such a compliance due diligence questionnaire or form to range anywhere from 1 to 100 pages or more. The types of questions the supplier is asked to answer can cover a wide range of areas from the executed contract. These issues can include safety, environmental, product liability, insurance, bonding, and other similar issues.
The supplier sends this extensive survey or form to their own compliance department, which fills out the form in detail and supplies the requested compliance information to the customer. If the supplier does not have a compliance or due diligence staff, then the supplier may employ the valuable time of their management staff, servicing staff or others to reply to these information requests. The research and employee time involved in filling out due diligence surveys for such terms, conditions, and applicable regulations can involve tens or even hundreds of man hours. As can be imagined, this amount of compliance work can incur a significant cost for the supplier.
When the customer receives this due diligence information covering compliance with the contract's terms, conditions, and applicable regulations, then the customer must also spend tens or hundreds of hours in organizing and analyzing this information on the paper form to determine if the information received is appropriate, complete, and accurate. This exercise in due diligence helps the customer to better manage the risk associated with having many suppliers. Otherwise, the contract terms and conditions are merely agreed upon but are not necessarily implemented or supported.
Regrettably, there are a number of disadvantages with the current system. Many companies have found that when there is a problem with a supplier, then the compliance documents for the terms and conditions of the contract are pulled out of a physical archive system and reviewed. What may be found is that much of the original survey information is incomplete, missing, old, or incorrect. Principally, it is difficult to monitor continued compliance during the term of the contract.
The entire process of determining whether or not a supplier conforms to the appropriate terms, conditions, and applicable regulations of a customer's contract is an extremely expensive and time consuming process for a customer company. Regardless of how much time and energy is spent on these due diligence processes, there may be overlooked items or incomplete information which will be later brought forth in litigation, government compliance inspections, or governmental hearings that are to the detriment of the company. Despite the reduced risk provided by human monitoring, the risk is not reduced as much as the customer's executive officers and directors would like because of the gaps and inconsistencies in the compliance process. Indeed, when many company executives have been asked what one of their most serious problems is, they reply that it is managing general risk and supplier risk.

System and method for informing business management personnel of business risk


The present invention relates to a compression load cell used to monitor pressure in a diapragm cassette pumping system. A plunger is axially slidable in a linear bearing and has a first end in contact with the cassette and the second end in contact with the load cell. The force signals have a direct relationship with the pressure in the cassette.

In the health care field, it is becoming increasingly common to use disposable pumping cassettes for pumping medical solutions. The cassettes are made of plastic and are operated by non-disposable driver mechanisms external to the cassette. Disposable cassette pumps offer many advantages over pumps with permanent pumping chambers. For example, disposable cassette pumps can be easily set up and readily changed over from prior pumping procedures without the need for sterilizing the permanent pump apparatus. Further, the disposable cassette pump apparatus allows for regular changing of the pumping pathway to reduce the risk of contamination without taking the pump equipment out of use for the period of time needed to sterilize the equipment.
Monitoring the pressure of the fluid being pumped through the cassette can provide useful information for controlling the pump. As disclosed in U.S. Pat. No. 4,457,753 monitoring cassette pressure permits the detection of occlusions or plugged filters in the cassette outlet line leading to a patient, for example. As disclosed in U.S. Pat. No. 4,842,584 monitoring cassette pressure also permits the valves to be checked for leakage. Further, when used as an infusion system, monitoring the discharge pressure of the cassette can be used to determine the patient's blood pressure.
U.S. Pat. No. 4,950,244 to Fellingham et al, hereby incorporated by reference, discloses a pressure transducer which can detect occlusions in the cassette inlet line from the solution container to the cassette.
However, while the above described pressure monitors are accurate, they are very complex and various parameters associated with the cassette must be strictly controlled. The need to control the parameters reduces the flexibility that the pumping apparatus can be used in and creates the potential for inaccurate results if the pump is used outside the controlled range of parameters. Thus there is a need for a simplified pressure sensor than can make accurate pressure measurements without the need for strict control of certain parameters.

Load cell pressure sensor for pump cassette


A spin-valve magnetoresistive element includes an antiferromagnetic layer, a first pinned magnetic layer, a nonmagnetic interlayer, a second pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer, a pair of longitudinal biasing layers, and a pair of lead layers. When a detecting current is applied from the lead layers, the magnetization vector of the free magnetic layer is aligned in a direction intersecting the magnetization vector of the second pinned magnetic layer, and the magnetization vector of the second pinned magnetic layer is tilted by an angle xcex8 from the normal of a track width direction toward a direction opposite to a longitudinal biasing magnetic field, in order to reduce asymmetry of the output.

1. Field of the Invention
The present invention relates to spin-valve magnetoresistive elements exhibiting variable electrical resistance in response to the relationship between the magnetization vector of a free magnetic layer and the magnetization vector of a pinned magnetic layer, relates to thin-film magnetic heads provided therewith, and relates to methods for making the same. In particular, the present invention relates to a structure of a spin-valve magnetoresistive element having two separated pinned magnetic layers and relates to a technology for reducing asymmetry when a detecting current magnetic field is applied.
2. Description of the Background
Anisotropic magnetoresistive (AMR) heads using anisotropic magnetoresistive effects and giant magnetoresistive (GMR) heads using spin-dependent scattering phenomena of conduction electrons are known as magnetoresistive reading (MR) heads. One of the known GMR heads is a spin-valve head exhibiting a high magnetoresistive effect with respect to a low external magnetic field.
FIG. 22 is a cross-sectional view of a conventional spin-valve magnetoresistive element when viewed from a face opposing a recording medium. In this spin-valve magnetoresistive element, an antiferromagnetic layer 102 and a pinned magnetic layer 103 are deposited on a substrate 101, in that order. The pinned magnetic layer 103 is in contact with the antiferromagnetic layer 102, and an exchange coupling magnetic field (exchange anisotropic magnetic field) is generated at the interface between the pinned magnetic layer 103 and the antiferromagnetic layer 102. The pinned magnetic layer 103 is magnetized, for example, in the Y direction in the drawing.
A nonmagnetic conductive layer 104 composed of copper or the like is formed on the pinned magnetic layer 103, and free magnetic layer 105 is formed on the nonmagnetic conductive layer 104. Hard biasing layers 106 formed of, for example, a cobalt-platinum (CoPt) alloy, are formed on both sides of the free magnetic layer 105 and are magnetized in the X direction in the drawing so that the free magnetic layer 105 is aligned to a single-domain state in the X direction. Thus, the variable magnetization of the free magnetic layer 105 and the pinned magnetization of the pinned magnetic layer 103 are substantially orthogonal to each other. Current lead layers 108 are provided on the hard biasing layers 106.
In this spin-valve magnetoresistive element, a detecting current (sensing current) from the current lead layers 108 flows in the element. When the magnetization vector of the free magnetic layer 105 varies with a fringing magnetic field from a magnetic recording medium such as a hard disk, the electrical resistance varies due to the relationship with the pinned magnetization direction of the pinned magnetic layer 103. Thus, the spin-valve magnetoresistive element detects the fringing magnetic field from the magnetic recording medium as a variable voltage due to the variable electrical resistance.
It is preferable that asymmetry of the output waveform be as small as possible in the spin-valve magnetoresistive element. The asymmetry is determined by the relationship between the variable magnetization vector of the free magnetic layer 105 and the pinned magnetization vector of the pinned magnetic layer 103. When no external magnetic field is applied, it is preferable that the variable magnetization vector of the free magnetic layer 105 be orthogonal to the pinned magnetization vector of the pinned magnetic layer 103.
With reference to a schematic view in shown in FIG. 23, the variable magnetization vector of the free magnetic layer 105, which affects the output asymmetry, will be described. In the spin-valve magnetoresistive element, which reads magnetic information with a detecting current, the magnetization of the free magnetic layer 105 is affected by a demagnetizing field (dipole magnetic field) Hd generated by the magnetization Mp of the pinned magnetic layer 103, a detecting current magnetic field (sensing current magnetic field) Hj due to the detecting current J, and an interactive magnetic field Hint due to interlayer interaction between the free magnetic layer 105 and the pinned magnetic layer 103 (a magnetic field, which affects so that the magnetization of the pinned magnetic layer 103 and the magnetization of the free magnetic layer 105 are parallel to each other).
It is considered that the asymmetry is reduced when these magnetic fields are relatively small with respect to the variable magnetization Mf of the free magnetic layer 105. Thus, when no external magnetic field is applied, canceling these magnetization vectors, as represented by the following equation, minimizes the asymmetry:
Hj+Hd+Hint=0
As shown in FIG. 23, the magnetization of the free magnetic layer 105, the detecting current magnetic field Hj and the interactive magnetic field Hint are in the same direction, whereas the demagnetizing field Hd is in a different direction. Thus, in order to minimize the asymmetry, such a spin-valve magnetoresistive element is preferably produced so as to satisfy the equation Hd=Hj+Hint based on the above relationship.
With reference to FIGS. 25A to 25E, a method for making a spin-valve magnetoresistive element of a composite ferri-pinned structure shown in FIG. 24 will be described. As shown in FIG. 24, in the composite ferri-pinned structure, the pinned magnetic layer is divided into a first pinned magnetic layer 111 and a second pinned magnetic layer 112. In FIGS. 25A to 25E, only an antiferromagnetic layer 110, the first pinned magnetic layer 111, the second pinned magnetic layer 112, and a free magnetic layer 113 are depicted for simplicity, and thus a nonmagnetic interlayer provided between the first pinned magnetic layer 111 and the second pinned magnetic layer 112 and a nonmagnetic conductive layer provided between the second pinned magnetic layer 112 and the free magnetic layer 113 are not depicted. Moreover, the depicted layers are shifted to show magnetization vectors of these layers. The magnetic thickness of the first pinned magnetic layer 111 is smaller than the magnetic thickness of the second pinned magnetic layer 112 in which the magnetic thickness corresponds to the product of the intensity of the magnetization and the thickness.
The spin-valve magnetoresistive element shown in FIG. 24 is produced as follows. The antiferromagnetic layer 110 composed of PtMn or the like, the first pinned magnetic layer 111 composed of Co or the like, the nonmagnetic interlayer (not shown in the drawing), the second pinned magnetic layer 112 composed of Co or the like, the nonmagnetic conductive layer (not shown in the drawing), and the free magnetic layer 113 composed of NiFe or the like are deposited on a substrate to form a composite. In this process, the first pinned magnetic layer 111 and the second pinned magnetic layer 112 are deposited while a magnetic field is applied in a direction perpendicular to the track width direction, then the nonmagnetic conductive layer is formed. Moreover, the first pinned magnetic layer 111 is formed while a magnetic field is applied in the track width direction. As a result, as shown in FIG. 25A, the magnetization vector of the first pinned magnetic layer 111 and the magnetization vector of the second pinned magnetic layer 112 are orthogonal to the magnetization vector of the free magnetic layer 113.
With reference to FIG. 25B, the composite is annealed while an annealing magnetic field H100 of 400 kA/m or more, which is perpendicular to the track width direction, is applied so that the PtMn antiferromagnetic layer 110 has an ordered structure. After the annealing, an intense exchange coupling magnetic field (exchange anisotropic magnetic field) occurs at the interface between the PtMn antiferromagnetic layer 110 and the first pinned magnetic layer 111. As a result, the magnetization vector of the first pinned magnetic layer 111 is pinned in the direction of the annealing magnetic field H100, which is perpendicular to the track width direction. After the annealing magnetic field is removed, the magnetization vector of the second pinned magnetic layer 112 is pinned in a direction, which is opposite to the annealing magnetic field H100, due to an exchange coupling magnetic field generated between the first pinned magnetic layer 111 and the second pinned magnetic layer 112 by the RKKY interaction. Moreover, this annealing in the magnetic field aligns the vector of the magnetic anisotropy in the free magnetic layer 113 in a direction perpendicular to the track width direction as shown in FIG. 25B.
With reference to FIG. 25C, the composite is annealed while an annealing magnetic field H200 is applied in the track width direction so that the vector of the uniaxial anisotropy is aligned along the annealing magnetic field H200. As a result, the magnetization vector of the first pinned magnetic layer 111 and the magnetization vector of the second pinned magnetic layer 112 are orthogonal to the anisotropic magnetic field of the free magnetic layer 113. The vector of the annealing magnetic field H200 may be either the right or the left.
In the single pinned magnetic layer configuration shown in FIG. 23, the demagnetizing field is large at edges of the element. Thus, a leakage magnetic field to the exterior is large, and the pinning force acting from the antiferromagnetic layer 102 to the pinned magnetic layer 103 is not large. The spin-valve magnetoresistive element having the composite ferri-pinned structure shown in FIG. 24 has been developed to solve the above problem. As shown in FIG. 24, the magnetization vector of the first pinned magnetic layer 111 and the magnetization vector of the second pinned magnetic layer 112 are antiparallel to each other and the magnetic moment of one of these is larger than the magnetic moment of the other. Thus, a strong pinning force is achieved by an effective magnetostatic coupling magnetic field from the antiferromagnetic layer 110 to these two pinned magnetic layers.
In the spin-valve magnetoresistive element of the composite ferri-pinned structure shown in FIG. 24, the fringing magnetic field of the first pinned magnetic layer compensates for most of the fringing magnetic field of the two pinned magnetic layers to reduce the effect of the demagnetizing field (dipole magnetic field) Hd on the free magnetic layer 113. Since the demagnetizing field Hd is reduced in such a mechanism, the detecting current magnetic field Hj is larger than the demagnetizing field Hd. Thus, it is difficult to reduce the asymmetry since the detecting current magnetic field Hj is too large to compensate for the demagnetizing field Hd. In particular, when the demagnetizing field Hd is small in the composite structure shown in FIG. 24, the detecting current magnetic field Hj affects the magnetization vector of the free magnetic layer 105. That is, the magnetization vector of the free magnetic layer 105 tilts toward the lower right side, as shown by the vector Mf1 in FIG. 24. As a result, the orthogonal magnetizations of the first pinned magnetic layer 111 and the second pinned magnetic layer 112 are not achieved.
When the demagnetizing field Hd is increased so as to be balanced with the detecting current magnetic field Hj in order to reduce asymmetry, the pinning force of the antiferromagnetic layer 110 to the first pinned magnetic layer 111 and the second pinned magnetic layer 112 is decreased. Accordingly, the control of the asymmetry in the spin-valve magnetoresistive element having the composite ferri-pinned structure requires another mechanism.
A thin-film magnetic head having the spin-valve magnetoresistive element as a reading element generally has a composite configuration including an inductive element (magnetic inductive head) as a writing element. The write head has an inductive coil for recording, and a magnetic pole for writing formed of a magnetic film and a magnetic gap provided at the edge of the inductive coil. An insulating layer formed of resin is provided to insulate the inductive coil from other layers. In the formation of the insulating resin layer for covering the inductive coil, an uncured resin is applied and is cured by heat. After the uniaxial anisotropy is imparted to the free magnetic layer 113 as shown in FIG. 25C, the write head is formed, and then these are annealed together with an upper shield 114 and a lower shield 115. The annealing temperature exceeds 473 K (200xc2x0 C.) for achieving curing of the resin. Such a high annealing temperature disorders the uniaxial anisotropy in the free magnetic layer 113, resulting in the generation of Barkhausen noise, as shown in FIG. 25E. Thus, the reading head does not have desired characteristics.
In the thin-film magnetic head, the upper shield 114 provided on the magnetoresistive element also functions as a lower core layer of the write head (inductive head). When disorder of the uniaxial anisotropy in the free magnetic layer 113 and the disorder of the magnetization easy axis in the upper shield 114 simultaneously occur in such a configuration, the magnetization, that is, the magnetic domain structure, of the upper shield 114 is irreversibly varied with recording of magnetic information on a magnetic recording medium by the inductive head. An unstable magnetic field generated by the irreversible magnetic domain will result in unstable read output from the magnetoresistive element.
It is an object of the present invention to provide a spin-valve magnetoresistive element exhibiting reduced asymmetry in which the magnetization vectors of pinned magnetic layers and a free magnetic layer are aligned to predetermined directions when a detecting current magnetic field is applied.
It is another object of the present invention to provide a thin-film magnetic head using the spin-valve magnetoresistive element.
It is another object of the present invention to provide a spin-valve magnetoresistive element having a composite ferri-pinned structure which exhibits reduced asymmetry, a thin-film magnetic head having the spin-valve magnetoresistive element, a method for making the spin-valve magnetoresistive element, and a method for making the thin-film magnetic head.
It is another object of the present invention to provide a spin-valve magnetoresistive element exhibiting reduced asymmetry in which the directions of applied magnetic fields are adjusted when individual layers are magnetized in response to the relationship between the magnetic thickness of the first pinned magnetic layer and the magnetic thickness of the second pinned magnetic layer.
According to a first aspect of the present invention, a spin-valve magnetoresistive element includes: an antiferromagnetic layer; a first pinned magnetic layer in contact with the antiferromagnetic layer, an exchange anisotropic magnetic field being formed between the antiferromagnetic layer and the first pinned magnetic layer for pinning the magnetization vector of the first pinned magnetic layer; a nonmagnetic interlayer; a second pinned magnetic layer, the nonmagnetic interlayer being disposed between the first pinned magnetic layer and the second pinned magnetic layer, the magnetization vector of the second pinned magnetic layer being aligned in a direction antiparallel to the magnetization vector of the first pinned magnetic layer; a nonmagnetic conductive layer in contact with the second pinned magnetic layer; a free magnetic layer in contact with the nonmagnetic conductive layer; longitudinal biasing layers for applying a longitudinal biasing magnetic field in a track width direction to the free magnetic layer; and a pair of lead layers for supplying a detecting current to the second pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer; wherein, when the detecting current is supplied from the lead layers, the magnetization vector of the free magnetic layer is aligned in a direction intersecting the magnetization vector of the second pinned magnetic layer, and the magnetization vector of the second pinned magnetic layer is tilted from the direction perpendicular to the track width direction toward a direction opposite to the longitudinal biasing magnetic field.
When the detecting current is applied, the magnetization vector of the free magnetic layer and the magnetization vectors of the pinned magnetic layers intersect with a predetermined angle. This configuration produces a large change in resistance when an external magnetic field is applied from a magnetic recording medium compared to a state where no external magnetic field is applied. Moreover, the asymmetry of the output from the magnetic information on a magnetic recording medium is reduced.
According to a second aspect of the present invention, a spin-valve magnetoresistive element includes an antiferromagnetic layer; a first pinned magnetic layer in contact with the antiferromagnetic layer, an exchange anisotropic magnetic field being formed between the antiferromagnetic layer and the first pinned magnetic layer for pinning the magnetization vector of the first pinned magnetic layer; a nonmagnetic interlayer; a second pinned magnetic layer, the nonmagnetic interlayer being disposed between the first pinned magnetic layer and the second pinned magnetic layer, the magnetization vector of the second pinned magnetic layer being aligned in a direction antiparallel to the magnetization vector of the first pinned magnetic layer; a nonmagnetic conductive layer in contact with the second pinned magnetic layer; a free magnetic layer in contact with the nonmagnetic conductive layer; longitudinal biasing layers for applying a longitudinal biasing magnetic field in a track width direction to the free magnetic layer; and a pair of lead layers for supplying a detecting current to the second pinned magnetic layer, the nonmagnetic conductive layer, and the free magnetic layer; wherein, when the detecting current is supplied from the lead layers, the magnetization vector of the free magnetic layer is aligned in a direction intersecting the magnetization vector of the second pinned magnetic layer, and the magnetization vector of the free magnetic layer is tilted from the track width direction toward the magnetization vector of the second pinned magnetic layer.
When the detecting current is applied, the magnetization vector of the free magnetic layer and the magnetization vectors of the pinned magnetic layers intersect with a predetermined angle. Thus, the asymmetry of the output from the magnetic information on a magnetic recording medium is reduced.
In the first and second aspects, the angle of tilt of the free magnetic layer, xcex8, is preferably in a range of 2xc2x0 to 30xc2x0, more preferably 3xc2x0 to 15xc2x0, and most preferably 3xc2x0 to 10xc2x0. The asymmetry can be more effectively reduced within the range without reducing the output. At an angle exceeding this range, the output is reduced. At an angle of less than this range, the asymmetry is not significantly improved.
When the detecting current is supplied and when no external magnetic field is applied, the angle defined by the magnetization vector of the free magnetic layer and the magnetization vector of the second pinned magnetic layer is preferably 90xc2x0. The magnetization vector of the free magnetic layer is tilted by the effect of the detecting current magnetic field due to the detecting current. Since the magnetization vector of the second pinned magnetic layer and the tilted magnetization vector of the second pinned magnetic layer are orthogonal to each other, the asymmetry is most effectively reduced while maintaining high output.
Preferably, the magnetic thickness of the first pinned magnetic layer is smaller than the magnetic thickness of the second pinned magnetic layer, the direction of the detecting current magnetic field applied to the free magnetic layer is opposite to the magnetization vector of the second pinned magnetic layer, and the direction of the detecting current magnetic field applied to the second pinned magnetic layer is opposite to the magnetization vector of the second pinned magnetic layer, where the magnetic thickness is defined as the product of the saturation magnetization and the thickness. This configuration stabilizes the magnetization vector of the first pinned magnetic layer and the magnetization vector of the second pinned magnetic layer, and produces a large change rate of resistance xcex94R/R.
Preferably, the antiferromagnetic layer includes one of an XMn alloy and an XMnXxe2x80x2 alloy, wherein X is at least one element selected from the group consisting of Pt, Pd, Rh, Ir, Ru, and Os, and Xxe2x80x2 is at least one element selected from the group consisting of Au, Ag, Cr, Ni, Ne, Ar, Xe, and Kr.
Since these alloys have higher blocking temperatures than those of conventional antiferromagnetic materials such as FeMn, the resulting spin-valve magnetoresistive element is thermally stable.
Preferably, the overall exchange anisotropic magnetic field of the antiferromagnetic layer affecting a composite pinned magnetic layer including the first pinned magnetic layer and the second pinned magnetic layer is 96 kA/m or more. When the overall exchange anisotropic magnetic field has such a high value, a hard biasing magnetic field from the longitudinal biasing layers does not extraordinarily tilt the magnetization of the pinned magnetic layer at the peripheral portions.
Preferably, the antiferromagnetic layer, the first pinned magnetic layer, the nonmagnetic interlayer, the second pinned magnetic layer, and the free magnetic layer are deposited in that order on a substrate. In the bottom-type spin-valve magnetoresistive element in which the antiferromagnetic layer is deposited near the substrate, the anisotropic magnetic field of the pinned magnetic layer can be increased.
Preferably, the free magnetic layer comprises a first free magnetic layer and a second free magnetic layer separated by a conductive interlayer provided therebetween.
Alternatively, the free magnetic layer, the nonmagnetic conductive layer, the second pinned magnetic layer, the conductive interlayer, the first pinned magnetic layer, and the antiferromagnetic layer are deposited in that order on a substrate.
According to a third aspect of the present invention, a method for making a spin-valve magnetoresistive element includes: a composite forming step for forming a composite having an antiferromagnetic layer, a first pinned magnetic layer, a nonmagnetic interlayer, a second pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer on a substrate, the free magnetic layer being formed while applying a first magnetic field in one of a first direction along a track width direction and a direction opposite to the first direction to impart uniaxial anisotropy in the track width direction to the free magnetic layer; a first annealing step for annealing the composite at a first annealing temperature while applying a second magnetic field in one of a second direction tilted by an angle xcex8 from the normal of the track width direction and a third direction opposite to the second direction to generate an exchange anisotropic magnetic field at the interface between the antiferromagnetic layer and the first pinned magnetic layer, to pin the magnetization of the first pinned magnetic layer and the magnetization of the second pinned magnetic layer in directions which are tilted by the angle xcex8 from the normal of the track width direction and which are antiparallel to each other; a biasing layer forming step for forming longitudinal biasing layers, for applying a biasing magnetic field to the free magnetic layer, on both sides of the laminate; a second annealing step for annealing the laminate at a second annealing temperature while applying a third magnetic field to the free magnetic layer in one of the first direction and a direction opposite to the first direction to impart uniaxial anisotropy to the free magnetic layer; and a biasing layer magnetizing step for applying a fourth magnetic field in a fourth direction opposite to the component in the track width direction of the magnetization vector of the second pinned magnetic layer to magnetize the longitudinal biasing layers.
The first annealing step at the first annealing temperature while applying the second magnetic field in the second direction pins the magnetization vector of the first pinned magnetic layer with a tilt angle xcex8. Next, the uniaxial anisotropy of the free magnetic layer is aligned in the track width direction during the second annealing step so that the magnetization vector of the pinned magnetic layer and the free magnetic layer intersect each other when the detecting current magnetic field is applied.
When the magnetic thickness of the first pinned magnetic layer is smaller than the magnetic thickness of the second pinned magnetic layer, the intensity of the second magnetic field may be 400 kA/m or more so as to align the magnetization vector of the first pinned magnetic layer in the second direction and the magnetization vector of the second pinned magnetic layer in the third direction, or the intensity of the second magnetic field may be 8 to 80 kA/m so as to align the magnetization vector of the first pinned magnetic layer in the third direction and the magnetization vector of the second pinned magnetic layer in the second direction, where the magnetic thickness is defined as the product of the magnetic moment and the thickness of the corresponding pinned magnetic layer.
When the magnetic thickness of the first pinned magnetic layer is larger than the magnetic thickness of the second pinned magnetic layer, the intensity of the second magnetic field may be 400 kA/m or more so as to align the magnetization vector of the first pinned magnetic layer in the second direction and the magnetization vector of the second pinned magnetic layer in the third direction, or the intensity of the second magnetic field may be 8 to 80 kA/m so as to align the magnetization vector of the first pinned magnetic layer in the second direction and the magnetization vector of the second pinned magnetic layer in the second direction, where the magnetic thickness is defined as the product of the magnetic moment and the thickness of the corresponding pinned magnetic layer.
The method for making a spin-valve magnetoresistive element may further comprises a recording head annealing step for forming an inductive recording magnetic head onto the composite, the recording head annealing step being provided between the first annealing step and the second annealing step. The annealing step for forming the inductive recording magnetic head disorders the uniaxial anisotropy of the free magnetic layer, but the subsequent second annealing step aligns the uniaxial anisotropy of the free magnetic layer. Thus, the spin-valve magnetoresistive element has a uniaxially anisotropic free magnetic layer.
The method for making a spin-valve magnetoresistive element may further comprise an additional annealing step, prior to the recording head annealing step, for annealing the composite while applying a magnetic field to the free magnetic layer in one of the first direction and the direction opposite to the first direction to impart uniaxial anisotropy in the track width direction to the free magnetic layer.
Preferably, the third magnetic field applied in the second annealing step is smaller than the second magnetic field applied in the first annealing step. Since the third magnetic field is smaller than the second magnetic field, the uniaxial anisotropy of the free magnetic layer is aligned without adversely affecting the magnetization vector of the pinned magnetic layer.
Preferably, the intensity of the third magnetic field applied in the second annealing step is 8 kA/m to 40 kA/m.
Preferably, the first annealing temperature is in a range of 230xc2x0 C. (503 K) to 280xc2x0 C. (553 K) and the second annealing temperature is in a range of 160xc2x0 C. (433 K) to 240xc2x0 C. (513 K).
Preferably, the antiferromagnetic layer includes one of an XMn alloy and an XMnXxe2x80x2 alloy wherein X is at least one element selected from the group consisting of Pt, Pd, Rh, Ir, Ru, and Os, and Xxe2x80x2 is at least one element selected from the group consisting of Au, Ag, Cr, Ni, Ne, Ar, Xe, and Kr.
The antiferromagnetic layer may be disposed between the substrate and the free magnetic layer in the composite.
According to a fourth aspect of the present invention, a method for making a spin-valve magnetoresistive element includes: a composite forming step for forming a composite having an antiferromagnetic layer, a first pinned magnetic layer, a nonmagnetic interlayer, a second pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer on a substrate, the free magnetic layer being formed while applying a first magnetic field in one of a first direction along a track width direction and a direction opposite to the first direction to impart uniaxial anisotropy in the track width direction to the free magnetic layer; a first annealing step for annealing the composite at a first annealing temperature while applying a second magnetic field in a second direction orthogonal to the track width direction to generate an exchange anisotropic magnetic field at the interface between the antiferromagnetic layer and the first pinned magnetic layer so as to pin the magnetization of the first pinned magnetic layer and the magnetization of the second pinned magnetic layer in a direction orthogonal to the track width direction; a biasing layer forming step for forming longitudinal biasing layers, for applying a biasing magnetic field to the free magnetic layer, on both sides of the laminate; a second annealing step for annealing the laminate at a second annealing temperature while applying a third magnetic field to the free magnetic layer in one of the first direction and a direction opposite to the first direction to impart uniaxial anisotropy to the free magnetic layer and to tilt by an angle xcex8 from the normal of the track width direction the magnetization vector of the first pinned magnetic layer and the magnetization vector of the second pinned magnetic layer; and a biasing layer magnetizing step for applying a fourth magnetic field in a fourth direction opposite to the component in the track width direction of the magnetization vector of the second pinned magnetic layer to magnetize the longitudinal biasing layers.
The first annealing step while applying the second magnetic field in the second direction pins the magnetization vector of the first pinned magnetic layer in contact with the antiferromagnetic layer and the magnetization vector of the second pinned magnetic layer in a direction orthogonal to the track width direction. The subsequent annealing in the magnetic field applied in the track width direction tilts the magnetization vectors of the pinned magnetic layers by an angle xcex8 from the direction orthogonal to the track width direction. Thus, in the spin-valve magnetoresistive element, the magnetization vectors of the pinned magnetic layers and the magnetization vector of the free magnetic layer intersect each other when a dipole magnetic field is applied.
When the magnetic thickness of the first pinned magnetic layer is larger than the magnetic thickness of the second pinned magnetic layer, the magnetization vector of the first pinned magnetic layer is aligned in the second direction, and the magnetization vector of the second pinned magnetic layer is aligned in a direction opposite to the second direction, where the magnetic thickness is defined as the product of the magnetic moment and the thickness of the corresponding pinned magnetic layer.
When the magnetic thickness of the first pinned magnetic layer is larger than the magnetic thickness of the second pinned magnetic layer, the intensity of the second magnetic field may be 400 kA/m or more so as to align the magnetization vector of the first pinned magnetic layer in the second direction and the magnetization vector of the second pinned magnetic layer in a third direction opposite to the second direction, or the intensity of the second magnetic field may be 8 to 80 kA/m so as to align the magnetization vector of the first pinned magnetic layer in the second direction and the magnetization vector of the second pinned magnetic layer in the third direction, where the magnetic thickness is defined as the product of the magnetic moment and the thickness of the corresponding pinned magnetic layer.
When the magnetic thickness of the first pinned magnetic layer is smaller than the magnetic thickness of the second pinned magnetic layer, the intensity of the second magnetic field may be 400 kA/m or more so as to align the magnetization vector of the first pinned magnetic layer in the second direction and the magnetization vector of the second pinned magnetic layer in a third direction opposite to the second direction, or the intensity of the second magnetic field may be 8 to 80 kA/m so as to align the magnetization vector of the first pinned magnetic layer in the third direction and the magnetization vector of the second pinned magnetic layer in the second direction, where the magnetic thickness is defined as the product of the magnetic moment and the thickness of the corresponding pinned magnetic layer.
The method for making a spin-valve magnetoresistive element may further include a recording head annealing step for forming an inductive recording magnetic head onto the composite, the recording head annealing step being provided between the first annealing step and the second annealing step. The annealing step for forming the inductive recording magnetic head disorders the uniaxial anisotropy of the free magnetic layer, but the subsequent second annealing step aligns the uniaxial anisotropy of the free magnetic layer. Thus, the spin-valve magnetoresistive element has a uniaxially anisotropic free magnetic layer.
Preferably, the third magnetic field applied in the second annealing step is smaller than the second magnetic field applied in the first annealing step.
Preferably, the first annealing temperature is in a range of 230xc2x0 C. (503 K) to 280xc2x0 C. (553 K) and the second annealing temperature is in a range of 160xc2x0 C. (433 K) to 240xc2x0 C. (513 K).
Preferably, the antiferromagnetic layer includes one of an XMn alloy and an XMnXxe2x80x2 alloy wherein X is at least one element selected from the group consisting of Pt, Pd, Rh, Ir, Ru, and Os, and Xxe2x80x2 is at least one element selected from the group consisting of Au, Ag, Cr, Ni, Ne, Ar, Xe, and Kr.
The antiferromagnetic layer may be disposed between the substrate and the free magnetic layer in the composite.
In the present invention, a thin-film magnetic head is produced by a step for forming a spin-valve magnetoresistive element as a read element and by a step for forming an inductive read magnetic head on the spin-valve magnetoresistive element.

Spin-valve magnetoresistive element and method for making the same


An approach that manages moving surveillance cameras is described. In one embodiment, there is a system for managing images generated from a movable camera. In this embodiment, the system comprises a motion estimation component configured to determine camera motion. A camera motion alert component is configured to generate an alert in response to a determination that the camera has moved or the camera has ceased moving.

This disclosure relates generally to video camera systems and more particularly to steerable video surveillance cameras.
Most currently available video surveillance analytics systems rely on background subtraction to detect objects of interest by comparing incoming frames of video with a background model that provides a reference representation of what a video camera should see if no moving objects were present. The background model is created by a background maintenance procedure that learns the normal appearance of each pixel or local area of the field of view of the camera. These types of video surveillance analytics systems work on the assumption that the camera does not move and that any pixel will continue to see the same region of the real world. If this assumption is violated, i.e., the camera is moved, then a pixel will receive light from a different part of the scene from the real world and differences not due to scene changes will be detected. The analytics component of the surveillance system detects these differences through background subtraction, and because the detected differences are not due to scene changes, the system generates many false positives, creating tracks for artifacts that are not due to moving objects. In addition, the system is quite likely to fail to track true moving objects because of the number of false tracks being generated.
Camera motions that can cause false positives to occur in video surveillance analytics systems that use background subtraction can occur for several reasons. For example, wind and vibration can cause the camera to make small movements that result in the camera oscillating around its normal position. Also, steerable surveillance cameras that are controlled by an operator such as a security guard or by an automated procedure that moves the camera can be subject to false positives because of the visual changes caused by the camera motion. Other reasons for camera motion can be the result of direct physical movement of the camera. For example, a maintenance worker could turn the camera, a truck could collide with the camera or an intruder could turn the camera so that it could no longer be used to observe activity in a certain area under surveillance.
Various approaches have been employed to stabilize camera motions that occur for the above-noted reasons. These stabilization approaches can use mechanical, electromechanical or electronic methods to remove the effects of movement from the images delivered to the background subtraction detection component of the video surveillance analytics systems. Mechanical and electromechanical methods may move the lens or sensor of the camera in such a way that the image formed on the sensor maintains the same alignment with it, while electronic methods may detect the offset in the obtained image and shift it back to counteract the detected motion.
These approaches work well in stabilizing small camera motions but are not effective in stabilizing large camera motions that are beyond the range of mechanical actuators' ability to move the lens or sensor to compensate or motions that are so great that compensation mechanisms introduce image distortions of other kinds that are in themselves problematic. In addition, these approaches fail to work well for camera motions that cannot be dealt with by a compensation method that can compensate for movements of the camera such as the twisting of the camera about its optical axis.

System and method for managing moving surveillance cameras

International Business Machines Corporation