An apparatus for add/drop multiplexing of a wavelength channel multiplex comprises an MMI coupler and MI arm section. The MMI coupler includes a multiplex input, an add channel input, a drop channel output, a multiplex output, and at least four input/output terminals. The MI arm section includes four waveguides, wherein each waveguide is optically connected to a respective one of said input/output terminals of the MMI coupler; and is at least provided with a first phase control element, a reflection grating, a second phase control element, and a wide frequency range reflection means. Further, each of the reflection gratings are provided with a heater means for tuning the respective reflection grating to the wavelength channel to be added/dropped and the wide frequency range reflection means reflect all other channels. The first and second phase control elements are adapted to direct the channel to be added/dropped to the multiplex output/drop channel output and to direct remaining channels to the multiplex output.

This application claims priority under 35 U.S.C. xc2xa7xc2xa7 119 and/or 365 to 0002081-8 filed in Sweden on Jun. 5, 2000; the entire content of which is hereby incorporated by reference.
The present invention generally relates to optical transmission techniques, particularly single mode integrated optics, for tele and data communication.
More specifically, the invention relates to apparatus for tunable add/drop multiplexing and to methods for tunable add/drop multiplexing.
Tunable optical add-drop multiplexers are needed in different kind of networks. Especially in ring and bus configurations the add-drop functionality is vital. Add-drop multiplexers have been implemented using various principles.
A multiplexer provided with Bragg gratings and based on an MZI structure (MZI, Mach-Zehnder interferometer) is depicted in Low Crosstalk Optical Add-Drop Multiplexer based on a Planar Silica-On-Silicon Mach-Zehnder Interferometer with UV-induced Bragg Gratings and UV-Trimming, J.-M. Jouanno et al., Tech. Dig. Bragg Gratings, Photosensitivity, and Poling in Glass Fibers and Waveguides: Applications and Fundamentals, OSA, 1997, Williamsburg, Va., pp. 259-261. In principle, an add/drop multiplexer may be achieved using such a device, which comprises two directional couplers interconnected by two interference arms, a so-called MZI structure. In practice, however, possibly two separate devices are required in order to achieve complete add/drop functionality. Alternatively, two Bragg gratings may be cascaded in each Mach-Zehnder arm. Further, coupling to so-called cladding modes may occur in the grating structures, which would result in deteriorated performance of the device, particularly for channels at carrier wavelengths shorter than the Bragg wavelength.
A wavelength selectively tunable device, called MMIMZI demultiplexer, (MMIMZI, multimode interference Mach-Zehnder interferometer) may be utilized as a reconfigurable demultiplexer, see e.g. the publication A new type of tunable demultiplexer using a multi-leg Mach-Zehnder interferometer, J.-P. Weber et al., Proc. ECIO ""97 EthE5, Stockholm, pp. 272-275, 1997. Cascading of two such devices may result in a complete tunable add/drop multiplexer. Such a multiplexer has though a very narrow range within which the crosstalk performance is good. This may be solved, but then very complex interference circuits are required to achieve nonlinear phase response in the Mach-Zehnder arms of the multiplexer. Further, interference problems may occur for transmitted channels when two MMIMZI devices are cascaded.
A wavelength selective device based on an MMIMIBg structure (MMIMIBg, Bragg grating assisted multimode interference Michelson interferometer), which offers completely individual switching, is depicted in Bragg grating assisted MMIMI coupler for wavelength selective switching, T. Augustsson, Electron. Lett., Vol. 34(25), pp. 2416-2418, 1998. Even though the theory of the technique indicates low crosstalk, e.g. fabrication process dependent variations may increase the crosstalk. Possibly, two separate devices are needed to obtain add/drop-functionality.
An MMI-based device provided with Bragg gratings is disclosed in the publication Bragg Grating-Assisted MMI coupler for Add-Drop Multiplexing, T. Augustsson, J. Lightwave Technol., Vol. 16(8), pp. 1517-1522, 1998. It is, however, difficult to realize such a device, which can handle channels separated by less than 400 GHz, and still exhibit good filter performance.
It is a main object of the present invention to provide an apparatus and method for add/drop multiplexing of a wavelength channel multiplex, which are capable of handling a large number of channels simultaneously.
It is in this respect a particular object of the invention to provide such apparatus and method for add/drop multiplexing of a wavelength channel multiplex, which are capable of handling wavelength channels that are closely spaced.
It is still a further object of the invention to provide such apparatus and method for add/drop multiplexing of a wavelength channel multiplex, which exhibit tunability between a plurality of closely spaced wavelength channels.
It is yet a further object of the invention to provide an apparatus for add/drop multiplexing of a wavelength channel multiplex, which is compact and which includes short propagation lengths for the wavelength channels.
These objects among others are, according to a first aspect of the present invention, attained by an apparatus for optical add/drop multiplexing comprising an MMI coupler at least of size 4xc3x974 and an MI arm section.
The MMI coupler includes a multiplex input terminal for input of said wavelength channel multiplex into said MMI coupler; an add channel input terminal for input of a wavelength channel to be added to said multiplex into said MMI coupler; a drop channel output terminal for output of a wavelength channel to be dropped from said multiplex from said MMI coupler; a multiplex output terminal for output of said wavelength channel multiplex from said MMI coupler; and at least four input/output terminals. The MMI coupler is further effective to split light incoming on one of its input terminals into light shares delivered onto its input/output terminals, and to combine light shares incoming on its input/output terminals into combined light delivered onto one of its output terminals in dependence on the mutual phase relation of the incoming light shares.
The MI arm section includes at least four waveguides, wherein each waveguide is optically connected to a respective one of the input/output terminals of the MMI coupler, and wherein each of all, or of all but one, of the waveguides is at least provided with, as seen from the MMI coupler, a first phase control element, a narrow band reflection grating, preferably a Bragg grating, a second phase control element, and a wide frequency range reflection means.
According to the invention each of said narrow band reflection gratings is provided with a heater means, preferably a Peltier element, for tuning the respective narrow band reflection grating to the wavelength channel to be added and/or to the wavelength channel to be dropped; the first phase control elements are effective to direct the channel to be added to the multiplex output terminal of the MMI coupler and/or to direct the channel to be dropped to the drop channel output terminal of the MMI coupler; the wide frequency range reflection means are effective to reflect all wavelength channels comprised in the input wavelength channel multiplex except the wavelength channel to be dropped; and the second phase control elements are effective to direct all wavelength channels comprised in the input wavelength channel multiplex except the wavelength channel to be dropped to the multiplex output terminal of the MMI coupler.
The apparatus, and particularly the Bragg gratings, are preferably made of a material having a strongly temperature dependent refractive index, i.e. a high |dn/dT|, such as a monomer or a polymer.
In a particularly advantageous embodiment of the invention each of the wide frequency range reflection means has a reflection coefficient below 1 for the wavelength channels comprised in the input wavelength channel multiplex. The reflection coefficient may be between 0.82 and 0.98, preferably between 0.86 and 0.94, more preferably between 0.88 and 0.92, and most preferably around 0.90.
In yet a particularly advantageous embodiment of the invention, the wide frequency range reflection means are each comprised of a loop mirror device, particularly an MMI-based device.
According to a second aspect of the present invention an apparatus for optical drop multiplexing comprising an MMI coupler at least of size 3xc3x973 and an MI arm section is provided.
The MMI coupler includes a multiplex input terminal for input of said wavelength channel multiplex into said MMI coupler; a drop channel output terminal for output of a wavelength channel to be dropped from said multiplex from said MMI coupler; a multiplex output terminal for output of the remaining wavelength channel multiplex from said MMI coupler; and at least three input/output terminals. Further, the MMI coupler is effective to split light incoming on its input terminal into light shares delivered onto its input/output terminals, and to combine light shares incoming on its input/output terminals into combined light delivered onto one of its output terminals in dependence on the mutual phase relation of the incoming light shares.
The MI arm section includes at least three waveguides, wherein each waveguide is optically connected to a respective one of said input/output terminals of the MMI coupler; and wherein each of all, or of all but one, of the waveguides is at least provided with, as seen from the MMI coupler, a first phase control element, a narrow band reflection grating, a second phase control element, and a wide frequency range reflection means.
Each of said narrow band reflection gratings is provided with a heater means for tuning the respective narrow band reflection grating to the wavelength channel to be dropped; the first phase control elements are effective to direct the channel to be dropped to the drop channel output terminal of the MMI coupler; the wide frequency range reflection means are effective to reflect all wavelength channels comprised in the input wavelength channel multiplex except the wavelength channel to be dropped; and the second phase control elements are effective to direct all wavelength channels comprised in the input wavelength channel multiplex except the wavelength channel to be dropped to the multiplex output terminal of the MMI coupler.
According to a third aspect of the present invention, an apparatus for optical add multiplexing of an add channel and a wavelength channel multiplex is provided, the apparatus comprising an MMI coupler at least of size 3xc3x973 and an MI arm section.
The MMI coupler includes a multiplex input terminal for input of said wavelength channel multiplex into said MMI coupler; an add channel input terminal for input of the wavelength channel to be added to said multiplex into said MMI coupler; a multiplex output terminal for output of the wavelength channel multiplex from said MMI coupler; and at least three input/output terminals. Further, the MMI coupler is effective to split light incoming on one of its input terminals into light shares delivered onto its input/output terminals, and to combine light shares incoming on its input/output terminals into combined light delivered onto its output terminal in dependence on the mutual phase relation of the incoming light shares.
The MI arm section includes at least three waveguides, wherein each waveguide is optically connected to a respective one of said input/output terminals of the MMI coupler; and wherein each of all, or of all but one, of the waveguides is at least provided with, as seen from the MMI coupler, a first phase control element, a narrow band reflection grating, a second phase control element, and a wide frequency range reflection means.
Each of said narrow band reflection gratings is provided with a heater means for tuning the respective narrow band reflection grating to the wavelength channel to be added; the first phase control elements are effective to direct the channel to be added to the multiplex output terminal of the MMI coupler; the wide frequency range reflection means are effective to reflect all wavelength channels comprised in the input wavelength channel multiplex; and the second phase control elements are effective to direct all wavelength channels comprised in the input wavelength channel multiplex to the multiplex output terminal of the MMI coupler.
According to fourth and fifth aspects of the present invention methods for add and drop multiplexing, respectively, are provided for using the apparatus according to the first three aspects of the invention.
An advantage of the present invention is that it provides for a very effective and flexible add/drop multiplexing.
A further advantage of the present invention is that it provides for the handling of a large number of closely spaced wavelength channels.
Further characteristics of the invention and advantages thereof will be evident from the following detailed description of embodiments of the invention.

Bragg grating assisted MMIMI-coupler for tunable add-drop multiplexing

Telefonaktiebolaget LM Ericsson Stockholm


A method and system for supporting wireless and/or wireline features of telecommunications subscribers utilizing existing wireline interfaces includes a processor for provisioning the wireline interfaces to support predetermined wireless and/or wireline features. A service logic, such as a Service Control Point (SCP), assigns the wireline interfaces to the telecommunications subscribers on a call-by-call basis based on the features subscribed to by the subscriber. The processor is further operative to reprovision the wireline interfaces based on the number of subscribers assigned to the wireline interfaces.

As the demand for wireless communications services increases, both wireless and wireline service providers alike continue to seek ways to supply such services to satisfy the needs of their existing and potential customers. These service providers normally accomplish this task by adding new hardware and software to allow increased usage in existing networks and to expand such networks to new coverage areas. For wireline service providers, however, the task is far more complicated. Because wireline service providers generally do not have existing wireless networks, substantial time and expense must be incurred to set up the required infrastructure. This infrastructure includes, for example, Mobile Switching Centers (MSCs) which, unlike conventional wireline switches, have the ability to assign features such as three-way calling and call forwarding on a call-by-call basis. This capability is necessary due to the nature of wireless communications wherein it is inherent that one or more of the call participants have mobility.
As a partial solution to this problem, wireline service providers have utilized what is known in the art as one-to-one mapping. In this approach, a maximum number of subscribers are each assigned a resource at a switch located at the wireline network that accommodates the features subscribed to by the subscriber. When a subscriber is not utilizing his/her line, their corresponding switch resource remains idle. Furthermore, a fixed number of transport facilities between the two networks are shared by a fixed number of subscribers. Thus, the system is limited to a fixed number of subscribers, and blocking occurs when the number of subscribers trying to make a call exceeds the number of transport facilities. For example, in a GR-303 application the maximum number of subscribers may be 2048. Each of these 2048 subscribers are then assigned a specific switch resource at the wireline network. If there are only 96 transport facilities, then blocking would occur when the 97th subscriber attempts to make a call at the same time that 96 subscribers are already engaged in a conversation.
As readily seen, the above approach, while an advance over the prior art, still has limitations since sharing of resources is limited to a fixed maximum number of subscribers sharing a fixed number of transport facilities.
Consequently, a need exists for an integrated wireline/wireless network which has the capability to provide wireless and/or wireline services using existing switching infrastructure, but which is not limited by the above-noted drawbacks of one-to-one mapping. Such a system should utilize a single switching platform so as to afford the service provider the opportunity to offer feature portability between wireline and wireless access to communications services, as well as offer a common user interface.

Method and system for dynamically assigning features and users to wireline interfaces


A connecting box with a printed circuit board is described which has electrical components electrically connected to conductor rails of the connecting box. The printed circuit board is preferably held in the connecting box by an adhesive layer. Simple assembly and disassembly of the components is possible as a result of the use of the printed circuit board. In addition, the heat generated in the components can be better dissipated via the printed circuit board.

Connecting boxes are used in a wide variety of technical sectors in order to make electrical connections between electric lines and an electrical device. Solar panels have a large number of solar cells which are used to convert power from sunlight. The power generated by the solar cells is conveyed via electric lines, for example to a rectifier, for feeding into an alternating current (AC) network or to a battery. A connecting box is generally provided for electrical connection to the lines of the solar panel.
A corresponding connecting box is known from European patent application EP 1 102 354 A2. The connecting box has a housing, in the base board of which is provided an opening for introducing the electric lines of the solar panel. Electrical contacts for contacting the electric lines are provided in the connecting box. The electrical contacts are in turn connected to terminal pins which are arranged in a side wall of the housing and are used for connecting electric lines. The connected electric lines lead to the rectifier or to the battery. Conductor rails comprising a contact region for detachable connection of a foil conductor of the solar panel are provided in the housing as the electrical contacts. The contact region comprises a metal clamping spring to which the foil contact can be securely clamped. For introducing the foil contact, the clamping spring is opened in a clamping region by means of a tool, then the foil contact is introduced into the clamping spring and the tool then removed from the clamping spring, so the clamping spring recoils into the starting position and in the process securely clamps the foil contact.
The known connecting box has the drawback that components which are connected to the electrical contact elements of the connecting box are relatively complex to assemble.

Connecting box for connecting to a solar panel


A variety of techniques for color mixing support a user-controllable palette of colors for use when fabricating three-dimensional objects.

Three dimensional printers can create physical models from digital designs. While current printers can use a variety of different colors of build materials for greater flexibility in realizing aesthetic or functional objects, attempts to mix different colors have generally provided unsatisfactory results in extrusion-based processes due in large part to the highly viscous nature of thermoplastics and other typical build materials. There remains a need for color mixing in three dimensional printing to provide greater user control over the look of fabricated items.


A rapid acting control system for a gas turbine in an electrical system that is adapted to control fuel and air supply to the turbine to prevent flameout condition in the turbine and includes: a turbine control unit having an air supply controller that controls the position of a plurality of turbine inlet guide vanes (IGVs) in correspondence with at least one turbine condition signal; a load rejection module coupled to the air supplier controller and to a turbine electrical load sensor so as to generate a transient IGV correction signal in correspondence with a sensed turbine electrical load drop condition. A method of operating a gas turbine to maintain the turbine on-line during a loss of load condition includes the steps of sensing a loss of load condition for the turbine; supplying an inlet guide vane correction signal into an air supply controller coupled to control the position of a plurality of turbine IGVs, the IGV correction signal being independent of other turbine operating condition signals applied to the air supply controller; and adjusting the position of the plurality of IGVs in response to the IGV correction signal to adjust the turbine fuel air mixture in the gas turbine to prevent flameout during a loss of electrical load condition. The method typically further includes the step of removing the IGV correction signal after a correction time delay.

Gas turbines coupled to electric generators are commonly used in power generation service. It is desirable to optimize operation of a gas turbine in order to provide reliable power generation while reducing undesirable emissions from the combustion process in the turbine. For example, the gas turbine combustion process results in generation of, among other things, nitrogen oxides (NO.sub.x), unburnt hydrocarbons, and carbon monoxide (CO). Control of such undesirable emissions requires control of the fuel-air ratio (FAR) of the combustible mixture being fed into the combustion chamber of the turbine. One approach to minimize emissions has been to design a turbine so that when it is operating at full load conditions the FAR has an equivalence ratio (actual FAR divided by the stoichiometric FAR) that corresponds to a desired point between the lean burnout point (when turbine combustor flameout occurs because the FAR is too lean) and the rich burnout point (flameout due to FAR being too rich). For emission and fuel economy reasons, turbines are commonly operated with a fuel air mixture for which the equivalence ratio is less than one (that is, leaner than the stoichiometric FAR).
Controllers for gas turbines typically employ a decentralized control strategy in which fuel supply to the turbine and air supply to the turbine are controlled by reference to different measured turbine performance parameters (typically represented by respective turbine condition signals). For example, in a typical gas turbine controller, fuel supply to the turbine is controlled primarily via a feedback loop that seeks to match turbine power output with the electrical load demand on the generator driven by the turbine. This feedback is typically accomplished through monitoring turbine speed, with a speed error signal (that is variation of the measured turbine speed with a reference (or set point) value) being processed to increase or decrease fuel supply to the turbine as appropriate.
Air supply to the turbine in such a system is determined by the compressor inlet geometries which are controlled based on the error between measured turbine exhaust temperature and a reference temperature value; the compressor inlet guide vanes are positioned to increase or decrease air flow into the turbine as necessary to obtain the optimal exhaust temperature. In such a control system, a change in load on the turbine results in a substantially immediate change in fuel flow to the turbine, leading to a change in the power output and exhaust temperature, which change in exhaust temperature causes the controller commanding the inlet guide vanes to appropriately change air flow to the turbine. There is thus a lag between fuel supply control and air supply control. Systems can be designed such that the lag can be acceptable for some range of turbine operating conditions.
The control system lag presents significant challenges, however, in the event of a loss of load condition occurs (e.g., an electrical breaker opens) unloading the electrical generator driven by the turbine. Due to the magnitude of the change in load, the control system lag (that is, the delay in adjusting air supply to the turbine due to the exhaust temperature feedback loop) may cause one or more combustors in the turbine to flame out due to the fuel-air mixture becoming too lean to sustain combustion (too much air admitted for amount of fuel being supplied). Flameout of a sufficient number of combustors results in the turbine control system shutting the turbine down for safety reasons. Such a shutdown takes the turbine off line and necessitates the initiation of a restart process that delays reloading the turbine. The flameout also imposes thermal and mechanical cycles on the turbine that are desirably avoided.
It is thus desirable that a turbine control system be able to control a gas turbine so that the turbine is maintained in an operating condition (e.g., it does not flame out) even in the event of a full load rejection condition.

Load rejection rapid acting fuel-air controller for gas turbine


Methods and apparatus are provided for self-detection of lost device status using device-to-device communications with one or more expected neighboring devices. A device can detect when the device itself is lost, by determining one or more expected neighboring devices for one or more time periods; monitoring a local environment for one or more of the expected neighboring devices using device-to-device communication; detecting when the device is lost based on device-to-device communication and whether a threshold criteria of the expected neighboring devices in proximity to the device for a given interval of time; and sending at least one relay message to notify an owner of the lost device. The threshold criteria comprises, e.g., whether a minimum number of expected neighboring devices are nearby or whether at least one fixed neighboring device is nearby. The device-to-device communications employ one or more of short range relay communications and low-power mesh communications.

Devices are often lost or misplaced. Many devices, such as keys, television remote controls and cordless phones have a place where the device is typically kept, at particular times of day. Some devices may come with a base station (e.g., in the case of a telephone) that can be used to force the missing device, if within range, to emit a distinctive sound so that the device can be found. Such a system will fail, however, in the event that the lost device is sufficiently far away that it is outside the range of the base station or the sound generated by the lost device cannot be heard by a person in the vicinity of the base station.
A number of techniques have been proposed or suggested to assist a user with locating a lost or misplaced item. For example, the user may be required to clap or whistle to acoustically signal a locator device to provide a notification of the location of the item. Other systems employ a transmitting device that communicates a wireless signal to a receiving/locator device, which then responds with a visual or aural indication that the transmitted signal has been received. Such a system, however, requires the user to keep track of yet another object, i.e., the transmitter used in the locator system.
Key Finders, for example, are small electronic devices used to recover misplaced or lost sets of keys. Key Finders aim to reduce the time it takes to locate keys or other personal items without being obtrusive. For example, the key finders may emit a sound on-demand or otherwise guide a user towards the lost item.
Nonetheless, a need remains for a device to be able to determine for itself that it has become lost or misplaced and to provide an appropriate notification to an owner of its lost or misplaced status.

Self-detection of lost device status using device-to-device communications with one or more expected neighboring devices

International Business Machines Corporation


An engine cover assembly having an integrally attached captive fastener or part-in-assembly fastener for attachment to an engine is disclosed. The engine cover assembly includes an engine cover having a fastener aperture formed in a recessed area thereof and a captive fastener assembly integrally attached to the cover. The captive fastener assembly includes an elongated fastener having a head or shoulder, a load limiting spacer disposed next to the shoulder of the elongated fastener, and a load limiter positioned next to the load limiting spacer. The load limiter has shoulders formed at both ends. The elongated fastener has a threaded end for attachment to a threaded insert positioned in the engine. Insulators are attached to the load limiting spacer and are positioned to either side of an area of the engine cover adjacent the fastener aperture, thus capturing the engine cover between the elongated fastener head and the load limiter.

The engine compartment of the modern vehicle has an appearance that is quite different from that of its predecessors. For decades following the introduction of the motor vehicle, the engine compartment was generally ignored by designers who, instead, focused on the exterior and interior of the vehicle. The engine compartment of the production vehicle (as opposed to the show vehicle) was left entirely to engineers and thus was solely functional.
Nowadays, however, designers are engaged to improve the overall appearance of the engine compartment. The general result of these efforts is the inclusion in the engine compartment of an engine cover that covers at least some of the vehicle's engine. Known covers have a variety of shapes and styles and vary in the degree to which they cover the engine.
Known methods for attaching the engine cover to the engine itself include fitting stud bolts to strategic locations on the engine, applying appropriate torque to the stud bolts, installing the engine cover, and running down attachment nuts to secure the engine cover in position. These steps add to production time and, ultimately, play a role in increasing final product cost.
Accordingly, a common challenge for the designer of the modern engine cover is the need to combine functionality and serviceability with aesthetics in the relatively small space typically provided in the modern engine compartment. Consideration must therefore be given to ease of installation to maintain competitive assembly costs and ease of removability to maintain competitive repair costs. In addition to satisfying these requirements, the attachment elements for allowing easy installation and removal must also be simple, relatively light weight, inexpensive to produce, and integrated with the cover itself.
As in so many areas of vehicle technology there is always room for improvement related to the design of engine covers and to their methods of installation.

Engine cover integrated captive fastener


An appliance may include a cabinet, a door, a mullion, and a damping assembly. The cabinet may define a chamber. The door may be coupled to the cabinet and rotatable between an open position and a closed position to selectively seal the chamber. The mullion may have an inner face and an outer face. The mullion may be rotatably coupled to the door via a hinge defining an axial direction between a first position and a second position. The damping assembly may include a stopper wedge and a mated wedge. The stopper wedge may be fixed to the door. The stopper wedge may have a primary face extending along a nonparallel angle relative to the longitudinal plane. The mated wedge may be fixed to the mullion. The mated wedge may have a receiving face complementary to the primary face of the stopper wedge to engage therewith in the first position.

Appliances, such as refrigerator appliances, often include one or more assemblies for sealing air therein. In the case of refrigerator appliances, one of the reasons for such a seal is to mitigate food spoilage, which presents significant health hazards and causes billions of dollars of waste around the world each year. Specifically, in order to prevent spoilage, refrigerators and freezers maintain foods at low temperatures. Properly sealing in the cold air while still allowing the consumer to easily access the freezer and fresh food compartments is one of the most important considerations in refrigerator design.
Many refrigerators provide one or more hinged doors for accessing the refrigerator cabinet. The doors generally include gaskets, which seal the door against the refrigerator cabinet when the door is closed. French-style doors are desirable because they reduce the weight load on the door hinge. French doors divide the cabinet opening in two, such that each door weighs less than a single door would weigh. That allows the size of the support structure of each door to be reduced. French doors also increase accessibility to the refrigerator cabinet and provide additional storage arrangements that are not possible with a single-door design.
However, one problem with French doors is that they require additional seals; in particular, the middle of the refrigerator opening (i.e., where the two doors meet) must maintain a seal when the doors are closed. One solution to that problem is to position a stationary vertical mullion bar in the middle of the opening, upon which each door can create a seal. A stationary mullion limits the size of items that can be put into the refrigerator. Some French door refrigerators include a movable mullion attached to one of the doors such that access to the corresponding compartment via the respective opening is not obstructed by the mullion when the door to which the mullion is attached is opened. However, in some instances, the movable mullion may become misaligned and, as a result, may impair the sealing engagement of the doors or may inhibit the doors from opening or closing.
Accordingly, it would be useful to provide an appliance addressing one or more of the above issues. In particular, it may be advantageous to provide an appliance having an appliance having one or more features for maintaining a mullion in a correct position or alignment.

Appliance having an articulating mullion and damping assembly


The disclosure is related to providing service continuity between heterogeneous networks in user equipment. A first cell change procedure may be performed from a packet switched network to a circuit switched network in a first idle mode. Availability of a packet switched domain of the circuit switched network may be determined. A location area update (LAU) may be initiated when a packet switched domain of the circuit switched network is barred.

In a heterogeneous wireless network environment, various wireless networks use different telecommunication technologies. For example, heterogeneous wireless networks may include a global system for mobiles (GSM) network, a wideband code division multiple access (WCDMA) network, and/or a Long Term Evolution (LTE) network,
Each of the WCDMA network and/or GSM network supports both a circuit switched (CS) service and a packet switched (PS) service. However, the LTE network is a wireless communication network which delivers information at a high data transmission rate with low latency, and supports only a packet switched (PS) service. In the LTE network, a CS service (e.g., voice call service) may be provided through a circuit switched (CS) fallback and/or an internet protocol multimedia subsystem (IMS). Herein, the CS fallback may provide CS services such as voice call services, short message services (SMS), location services (LCS), and/or unstructured supplementary service data (USSD) by reuse of the WCDMA and/or GSM networks when user equipment (UE) is served by the LTE network. The CS fallback is available when a LTE service coverage is overlapped with a service coverage of the WCDMA network or the GSM network.
Typically, when UE supporting an LTE technology and a WCDMA/GSM technology redirects from an LTE network to a WCDMA/GSM network, UE may perform a location area update (LAU) or a routing area update (RAU) such as a normal routing area update (normal RAU) or a combined RAU.
However, when a cell change procedure (i.e., inter-radio access technology (Inter-RAT) cell change procedure) due to a cell reselection is performed from the LTE network to the WCDMA/GSM network, a PS domain of the WCDMA/GSM network may have already been barred. In this case, UE may not be able to perform a normal location update procedure. Accordingly, the UE present in the WCDMA/GSM network may not be able to receive paging signals from the WCDMA/GSM network since a position of the UE is not known to the WCDMA/GSM network. Further, the UE holds a temporary identity used in the next update (TIN) value being set to a GUTI value even though the UE is back to the LTE network.
Meanwhile, when an Inter-RAT cell change procedure due to CS fallback is performed from the LTE network to the WCDMA/GSM network, the PS domain of the WCDMA/GSM network may have already been barred. Thereafter, UE may be transferred back to the LTE network by a cell reselection procedure. In this case, the UE typically holds a TIN value being set to a GUTI value, and therefore the UE may not be able to perform a tracking area update (TAU). Therefore, the UE may not be able to receive paging signals from the LTE network.
Accordingly, there is a need to ensure service continuity between such different types of networks in heterogeneous wireless network environment by avoiding a loss of paging signals.

Providing service continuity between heterogeneous wireless networks


A diesel fuel delivery system that maintains optimum fuel delivery to the engine despite the presence of an ice blockage at the fuel strainer. Ice formation in diesel fuel can cause fuel blockage at the fuel strainer and generate high vacuum conditions as the engine tries to draw fuel from the tank. A normally closed bypass valve automatically opens in response to an engine vacuum condition higher than normal engine vacuum levels. Upon the bypass valve opening, fuel is drawn through an auxiliary inlet port and line located above the ice formation in the tank.

Present day diesel fuel delivery systems may include an assembly commonly referred to as a "modular reservoir assembly" or "MRA". An MRA includes a fuel reservoir and is located within the fuel tank. The reservoir collects fuel from the tank via a "passive fill" valve located on the bottom of the reservoir and an "active fill" jet pump operating on return fuel from the engine. An engine or frame mounted fuel pump pulls the fuel from the reservoir through fuel lines leading to the engine. A strainer is provided at the inlet to the fuel line to capture particulate from the fuel prior to entering the fuel line.
Diesel fuel is known to absorb moisture and form ice at low engine start-up temperatures (e.g., at or below about −20° C.). Ice formation at the bottom of the fuel reservoir may block the fuel strainer inlet. Should this occur, the engine may not start or will run inefficiently until the ice has melted. Therefore, there exists a need for a diesel fuel delivery system which will not be adversely affected by ice forming in the fuel reservoir.


An embodiment of the invention is a logic minimization method that provides improved user design performance without a substantial increase in user design area. Alternate factorizations are determined for portions of the user design. For each factorization, a delay metric is computed. The user design is optimized by selecting factorizations based on a balance of performance and area considerations. The optimized design is then mapped to the hardware architecture of the programmable device. A first portion of the user design is mapped to maximize performance, while a second portion of the user design is mapped to minimize area. The first portion of the user design includes a set of data paths each having a delay metric above a delay threshold. The delay metric can be derived from a unit delay computation or from timing analysis.

The present invention relates to the field of programmable devices, and the systems and methods for programming the same. Programmable devices, such as FPGAs, typically includes thousands of programmable logic cells that use either a combination of logic gates or a look-up table to perform a logic operation. Programmable devices also include a number of functional blocks having specialized logic devices adapted to a specific logic operations. The logic cells and functional blocks are interconnected with a configurable switching circuit. The configurable switching circuit selectively routes connections between the logic cells and functional blocks. By configuring the combination of logic cells, functional blocks, and the switching circuit, a programmable device can be adapted to perform virtually any type of information processing function.
A typical design cycle for determining the configuration of a programmable device starts with an extraction phase, followed by a logic synthesis phase, a fitting phase, and an assembly phase. The extraction phase takes a user design, typically expressed as a netlist in a hardware description language such as verilog or VHDL, and produces a set of logic gates implementing the user design. In the logic synthesis phase, the set of logic gates is permutated over the hardware architecture of the programmable device in order to match elements of the user design with corresponding portions of the programmable device. The fitting or routing phase assigns the various portions of the user design to specific logic cells and functional blocks of the programmable device, taking care to satisfy the user timing constraints as much as possible. In the assembly phase, a configuration file defining the programmable device configuration is created. The configuration can then be loaded into a programmable device to implement the user design.
Typically, the logic synthesis phase optimizes the netlist describing a user design to minimize the usage of the programmable device hardware, for example the number logic cells or functional blocks. By minimizing the usage of programmable device hardware, referred to generally as area, the design can be implemented using the simplest and presumably least expensive programmable device. However, minimizing the area of a user design tends to create data paths that pass through a large number of logic cells and/or functional blocks. This in turn increases the delay on data paths and decreases the maximum operating speed of the user design.
Alternatively, some logic synthesis methods optimize strictly for maximum operating speed. Unfortunately, these methods substantially increase the area requirements for a user design. As a result, the cost to implement the speed-optimized user design also increases. Furthermore, many speed optimization techniques increase area so much that the performance improvements gained from using additional programmable device hardware are negated by the additional path-induced delays introduced by the increased area of the design. Thus, the actual speed increase from these methods often falls short of theoretical projections.
It is therefore desirable for a logic synthesis method to provide improved design performance without a substantial increase in design area. It is further desirable that a logic synthesis method enables users to select whether a design should be optimized for improved speed, decreased area, or a balance of these two goals.

Timing-driven synthesis with area trade-off


The present invention relates to a system for the reversible anticoagulation of blood utilizing a nucleic acid ligand which binds thrombin and a reversing agent which has greater affinity for the nucleic acid ligand than does thrombin. When used with a blood sample, the nucleic acid ligand binds thrombin, preventing it from converting fibrinogen to fibrin, and thus anticoagulating the blood. Subsequently, the reversing agent may be added to the anticoagulated blood sample, and by competitive binding, replaces thrombin bound to the ligand, thus freeing the thrombin to convert fibrinogen to fibrin and allowing the blood to coagulate.

Blood samples are routinely taken in evacuated tubes, such as glass VACUTAINER.RTM. Brand evacuated sample collection tubes (Becton Dickinson and Company). One end of a double-ended needle is inserted into a patient's vein. The other end of the needle then punctures a septum covering the open end of the evacuated sample collection tube so that the vacuum in the tube draws the blood sample through the needle into the tube. Using this technique a plurality of samples can be taken using a single needle puncture of the skin. Plastic tubes have also been proposed for blood collection. Plastic offers several advantages related to lower breakage than glass tubes, less weight in shipment, and easier disposal by incineration for examples. Similarly, sample collection tubes designed for gravity based collection of smaller samples, such as a blood sample from an infant are also used with the same techniques. One such type of smaller tube is the MICROTAINER.RTM. Brand sample collection tube sold by Becton Dickinson and Company.
Blood samples collected in evacuated tubes are prepared for clinical examination in either the coagulated or non-coagulated (anticoagulated) state. In the latter category, which is the object of this invention, anticoagulation agents are utilized. There are a variety of anticoagulants routinely used in the art. These can be broadly classified as either calcium chelator or thrombin inhibitors. Calcium chelators function by removing calcium from solution in blood as a free ion. This inhibits coagulation because calcium is a necessary divalent ion for blood enzyme function. Citric acid, ethylenediaminetetraacetate (EDTA), fluorides, and oxalates are chemical anticoagulants that fall into calcium chelator category.
Thrombin is a serine protease derived from blood that converts fibrinogen to fibrin. Fibrin, in turn, polymerizes into a network that causes blood to gel or coagulate. As such, thrombin is a pivotal enzyme in hemostasis, and interruption of thrombin function can thus prevent blood coagulation. Thrombin inhibitors directly interfere with thrombin enzymatic function by blocking interaction with fibrinogen. Hirudin and heparin (through the antithrombin-heparin complex ATIII) are biochemical anticoagulants falling into the thrombin inhibitor category. Hirudin and heparin are well known in the field of hematology.
Calcium chelator and thrombin inhibitor anticoagulants have characteristic interferences with downstream clinical analysis. As examples, EDTA is successfully used in about 35% of hematology tubes (tripotassium, disodium, dipotassium, and liquid forms), but can induce blood cell aggregation. EDTA is not generally acceptable for use in nucleic acid diagnostics applying DNA amplification reactions such as polymerase chain reaction (PCR), which is important in growing markets of cellular analysis and viral load testing. Also, EDTA is inhibitory in T-cell stimulation assays. Oxalates can cause blood cells to shrink or expand, thus complicating cell volume measurements. Fluorides used in glucose testing are relatively poor anticoagulants and can cause hemolysis. Heparin can not be used in coagulation tubes because heparin interferes with enzymes of the coagulation cascade as well as with PCR.
Citrate is in widespread use for coagulation assays and is the anticoagulant of choice for PCR, but citrate causes some problems in cell or virus culture. Hirudin, a strong anticoagulant derived from leeches, and synthetic hirudin analogs are not yet in widespread commercial applications due to cost and availability.
Also, a nucleic acid ligands or aptamers to thrombin have been developed which inhibit coagulation of blood (Kubik, M. F. et al., Nuc. Acids Res. 22, 2619 (1994) and Bock L. C. et al., Nature 355, 564 (1992)). These nucleic acid ligands have not been used in any commercial products.
Another issue in anticoagulation is that of reversibility. In certain blood diagnostic tests it is useful to potentiate the coagulation cascade by reversing the anticoagulated state. For example, in the testing for blood coagulation dysfunctionality, it is customary in the art to use citrated blood plasma because the anticoagulated state can be rapidly reversed by addition of exogenous calcium which replenishes the necessary calcium for blood enzyme function. Anticoagulation of heparinized blood can be reversed by addition of heparinase, an enzyme that digests heparin and eliminates the coagulation-inhibiting heparin-ATIII complex. Unlike calcium and heparin, however, no reversing agents for hirudin are known. Thus hirudin is only appropriate for permanently anticoagulated blood specimens. Reversibility of the effects of nucleic acid ligands has also not been demonstrated in the art.
Blood testing would be significantly simplified if a single specimen of blood could be used for whole blood, plasma, and serum applications. Thus, there is need in the art for a "universal anticoagulant" that does not interfere with downstream clinical or hematological testing and is reversible by addition of a suitable reversing agent.

Rapidly reversed thrombin binding oligonucleotide anticoagulants


The present invention is directed to compounds of the formula (I) (wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R27, R28, R29, R30, R31, X, m, n and the dashed line are defined herein) which are useful as modulators of chemokine receptor activity. In particular, these compounds are useful as modulators of the chemokine receptor CCR-2

The chemokines are a family of small (70-120 amino acids), proinflammatory cytokines, with potent chemotactic activities. Chemokines are chemotactic cytokines that are released by a wide variety of cells to attract various cells, such as monocytes, macrophages, T cells, eosinophils, basophils and neutrophils to sites of inflammation (reviewed in Schall, Cytokine, 3, 165-183 (1991) and Murphy, Rev. Immun., 12, 593-633 (1994)). These molecules were originally defined by four conserved cysteines and divided into two subfamilies based on the arrangement of the first cysteine pair. In the CXC-chemokine family, which includes IL-8, GROα, NAP-2 and IP-10, these two cysteines are separated by a single amino acid, while in the CC-chemokine family, which includes RANTES, MCP-1, MCP-2, MCP-3, MIP-1α, MIP-1β and eotaxin, these two residues are adjacent.
The α-chemokines, such as interleukin-8 (IL-8), neutrophil-activating protein-2 (NAP-2) and melanoma growth stimulatory activity protein (MGSA) are chemotactic primarily for neutrophils, whereas β-chemokines, such as RANTES, MIP-1α, MIP-1β, monocyte chemotactic protein-1 (MCP-1), MCP-2, MCP-3 and eotaxin are chemotactic for macrophages, monocytes, T-cells, eosinophils and basophils (Deng, et al., Nature, 381, 661-666 (1996)).
The chemokines are secreted by a wide variety of cell types and bind to specific G-protein coupled receptors (GPCRs) (reviewed in Horuk, Trends Pharm. Sci., 15, 159-165 (1994)) present on leukocytes and other cells. These chemokine receptors form a sub-family of GPCRs, which, at present, consists of fifteen characterized members and a number of orphans. Unlike receptors for promiscuous chemoattractants such as C5a, fMLP, PAF, and LTB4, chemokine receptors are more selectively expressed on subsets of leukocytes. Thus, generation of specific chemokines provides a mechanism for recruitment of particular leukocyte subsets.
On binding their cognate ligands, chemokine receptors transduce an intracellular signal though the associated trimeric G protein, resulting in a rapid increase in intracellular calcium concentration. There are at least seven human chemokine receptors that bind or respond to β-chemokines with the following characteristic pattern: CCR-1 (or "CKR-1" or "CC-CKR-1") [MP-1α, MIP-1β, MCP-3, RANTES] (Ben-Barruch, et al., J. Biol. Chem., 270, 22123-22128 (1995); Beote, et al, Cell, 72, 415-425 (1993)); CCR-2A and CCR-2B (or "CKR-2A"/"CKR-2A" or "CC-CKR-2A"/"CC-CKR-2A") [MCP-1, MCP-2, MCP-3, MCP-4]; CCR-3 (or "CKR-3" or "CC-CKR-3") [Eotaxin, Eotaxin 2, RANTES, MCP-2, MCP-3] (Rollins, et al., Blood, 90,908-928 (1997)); CCR-4 (or "CKR-4" or "CC-CKR-4") [MIP-1α, RANTES, MCP-1] (Rollins, et al., Blood, 90, 908-928 (1997)); CCR-5 (or "CKR-5" or "CC-CKR-5") [MIP-1α, RANTES, MIP-1β] (Sanson, et al., Biochemistry, 35, 3362-3367 (1996)); and the Duffy blood-group antigen [RANTES, MCP-1] (Chaudhun, et al., J. Biol. Chem., 269, 7835-7838 (1994)). The β-chemokines include eotaxin, MIP ("macrophage inflammatory protein"), MCP ("monocyte chemoattractant protein") and RANTES ("regulation-upon-activation, normal T expressed and secreted") among other chemokines.
Chemokine receptors, such as CCR-1, CCR-2, CCR-2A, CCR-2B, CCR-3, CCR-4, CCR-5, CXCR-3, CXCR-4, have been implicated as being important mediators of inflammatory and immunoregulatory disorders and diseases, including asthma, rhinitis and allergic diseases, as well as autoimmune pathologies such as rheumatoid arthritis and atherosclerosis. Humans who are homozygous for the 32-basepair deletion in the CCR-5 gene appear to have less susceptibility to rheumatoid arthritis (Gomez, et al., Arthritis & Rheumatism, 42, 989-992 (1999)). A review of the role of eosinophils in allergic inflammation is provided by Kita, H., et al., J. Exp. Med. 183, 2421-2426 (1996). A general review of the role of chemokines in allergic inflammation is provided by Lustger, A. D., New England J. Med., 338(7), 426-445 (1998).
A subset of chemokines are potent chemoattractants for monocytes and macrophages. The best characterized of these is MCP-1 (monocyte chemoattractant protein-1), whose primary receptor is CCR2. MCP-1 is produced in a variety of cell types in response to inflammatory stimuli in various species, including rodents and humans, and stimulates chemotaxis in monocytes and a subset of lymphocytes. In particular, MCP-1 production correlates with monocyte and macrophage infiltration at inflammatory sites. Deletion of either MCP-1 or CCR2 by homologous recombination in mice results in marked attenuation of monocyte recruitment in response to thioglycollate injection and Listeria monocytogenes infection (Lu et al., J. Exp. Med., 187, 601-608 (1998); Kurihara et al. J. Exp. Med., 186, 1757-1762 (1997); Boring et al. J. Clin. Invest., 100, 2552-2561 (1997); Kuziel et al. Proc. Natl. Acad. Sci., 94, 12053-12058 (1997)). Furthermore, these animals show reduced monocyte infiltration into granulomatous lesions induced by the injection of schistosomal or mycobacterial antigens (Boring et al. J. Clin. Invest., 100, 2552-2561 (1997); Warmington et al. Am J. Path., 154, 1407-1416 (1999)). These data suggest that MCP-1-induced CCR2 activation plays a major role in monocyte recruitment to inflammatory sites, and that antagonism of this activity will produce a sufficient suppression of the immune response to produce therapeutic benefits in immunoinflammatory and autoimmune diseases
Accordingly, agents which modulate chemokine receptors such as the CCR-2 receptor would be useful in such disorders and diseases.
In addition, the recruitment of monocytes to inflammatory lesions in the vascular wall is a major component of the pathogenesis of atherogenic plaque formation. MCP-1 is produced and secreted by endothelial cells and intimal smooth muscle cells after injury to the vascular wall in hypercholesterolemic conditions. Monocytes recruited to the site of injury infiltrate the vascular wall and differentiate to foam cells in response to the released MCP-1. Several groups have now demonstrated that aortic lesion size, macrophage content and necrosis are attenuated in MCP-1 −/− or CCR2 −/− mice backcrossed to APO-E −/−, LDL-R −/− or Apo B transgenic mice maintained on high fat diets (Boring et al. Nature, 394, 894897 (1998); Gosling et al. J. Clin. Invest., 103, 773-778 (1999)). Thus, CCR2 antagonists may inhibit atherosclerotic lesion formation and pathological progression by impairing monocyte recruitment and differentiation in the arterial wall.

Tetrahydropyranyl cyclopentyl benzylamide modulators of chemokine receptor activity


A zoom lens system including a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group. Upon, all the lens groups move towards the object. A lens group other than the first one is a lens group for focusing, and a ratio K of traveling distance of the first to that of the second lens groups is made constant in any part of the focal length range. Furthermore, the zoom lens system satisfies the following condition:

1. Field of the Invention
The present invention relates to a four-lens-group zoom lens system and a zoom lens barrel thereof.
2. Description of the Related Art
As a four-lens-group zoom lens system of the prior art, the so-called xe2x80x9cfour-lens-group non-linearxe2x80x9d zoom lens system has been known, in which ratios of traveling distances among the lens groups are varied in the focal length range defined by the short focal length extremity and the long focal length extremity. Accordingly, a four-lens-group zoom lens system of the above type is advantageous for miniaturization of the zoom lens system and for maintaining freedom on the correcting of aberrations, since each of the four lens groups moves without being influenced by the movement of other lens groups. For example, the zoom lens systems, taught in U.S. Pat. No. 5,699,198 and Japanese Unexamined Patent Publication No. Hei-8-248319, are the four-lens-group non-linear zoom lens systems, each of which includes a positive lens group, a negative lens group, a positive lens group, and a positive lens group, in this order from the object. Furthermore, upon zooming, each lens group moves independently from other lens groups (i.e., moving the four lens groups non-linearly), thereby aberrations are suitably corrected over the entire focal length range, and miniaturization of the lens system can be attained. On the other hand, in order to move each lens group non-linearly, a cam mechanism has been required. Even when one lens group out of the four lens groups is moved linearly, a cam mechanism is still required for other three lens groups.
However, a cam mechanism is structured to move cam followers in cam grooves, and the cam followers come into contact with the cam grooves in a point-contact manner. Therefore the cam mechanism tends to be deformed due to shock occurring when the cam mechanism is being operated. If a cam groove and/or a cam follower are deformed, a smooth movement of the cam mechanism cannot be maintained, and the position of the lens group is shifted according to the amount of deformation; accordingly, an in-focus state cannot be obtained. In a conventional four-lens-group non-linear zoom lens system, since at least three cam mechanisms are required, the mechanism for zooming has inevitably become complicated, thereby it is difficult to attain high precision in the operations of the zoom lens system.
It is an object of the present invention to provide a four-lens-group zoom lens system in which the zoom mechanism thereof can be simplified, and has increased precision in operations.
In order to achieve the above-mentioned object, there is provided a zoom lens system including a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity towards the long focal length extremity, all the lens groups move towards the object so that the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the fourth lens group decreases. In the zoom lens system, a lens group other than the first one is arranged to be a lens group for focusing (hereinafter, a focusing lens group), and a ratio K of traveling distance of the first lens group to that of the second lens group is made constant in any part of the focal length range defined by the short focal length extremity and the long focal length extremity. Furthermore, the zoom lens system satisfies the following condition:
0.16 less than K less than 0.50xe2x80x83xe2x80x83(1)
wherein
K=xcex94X2/xcex94X1;
xcex94X1 designates the traveling distance of the first lens group, upon zooming, from the short focal length extremity to the long focal length extremity; and
xcex94X2 designates the traveling distance of the second lens group, upon zooming, from the short focal length extremity to the long focal length extremity.
As explained, in the case where the ratio of the traveling distance of the first lens group to that of the second lens group is made constant, the zooming mechanism can be simplified, and precision in the operations of the zoom lens system can be increased. For example, the first lens group and the second lens group can be driven by a screw mechanism. Still further, the second lens group is arranged to be a focusing lens group.
The zoom lens system according to the present invention preferably satisfies the following condition:
1.10 less than xcex94X1/fs less than 1.45xe2x80x83xe2x80x83(2)
wherein
fs designates the focal length of the entire zoom lens system at the short focal length extremity.
Further, the zoom lens system according to the present invention can satisfy the following condition:
0.25 less than fs/f1 less than 0.38xe2x80x83xe2x80x83(3)
wherein
f1 designates the focal length of the first lens group.
The fourth lens group includes a biconvex positive lens element and a biconcave negative lens element, in this order from the object, and preferably satisfies the following condition:
xe2x88x920.66 less than f4p/f4n less than xe2x88x920.35xe2x80x83xe2x80x83(4)
wherein
f4p designates the focal length of the biconvex positive lens element; and
f4n designates the focal length of the biconcave negative lens element.
In the above arrangement, the biconcave negative lens element can satisfy the following condition:
xe2x88x921 less than SF4n less than 0xe2x80x83xe2x80x83(5)
wherein
SF4n=(r2+r1)/(r2xe2x88x92r1);
SF4n designates the shape factor of the biconcave negative lens element in the fourth lens group;
r1 designates the radius of curvature of the object-side surface of the biconcave negative lens element in the fourth lens group;
r2 designates the radius of curvature of the image-side surface of the biconcave negative lens element in the fourth lens group.
The zoom lens system according to the present invention can satisfy the following condition:
0.82 less than fs/f3 less than 1.10xe2x80x83xe2x80x83(6)
wherein
f3 designates the focal length of the third lens group.
The zoom lens system according to the present invention preferably satisfies the following condition:
0.45 less than fs/f4 less than 0.56xe2x80x83xe2x80x83(7)
wherein
f4 designates the focal length of the fourth lens group.
The present invention can also be applied to a zoom lens barrel which contains a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group, in this order from the object. The zoom lens barrel is arranged to move all the lens groups towards the object upon zooming from the short focal length extremity towards the long focal length extremity so that the distance between the first and the second lens groups increases, the distance between the second and the third lens groups decreases, and the distance between the third and the fourth lens groups decreases. In the zoom lens barrel, a first frame by which the first lens group is supported, and a second frame by which the second lens group is supported are moved, upon zooming, forwardly or backwardly through a linear-moving mechanism, such as screw mechanism and the like.
The linear-moving mechanism is arranged to move the first and second frames along the optical axis, with respect to a fixed frame. More concretely, in the case where a screw mechanism is employed, the screw mechanism can includes a single driving ring, helicoids respectively formed on outer and inner surfaces of the driving ring, and the corresponding helicoids respectively formed on the first and second frames, so that through the rotation of the driving ring, the first and second frames move forwardly or backwardly along the optical axis.
Instead of the above screw mechanism in which the outer-surface helicoid of the driving ring directly engages with the first-frame helicoid, and the inner-surface helicoid of the driving ring directly engage with the second-frame helicoid, another arrangement of the screw mechanism can be employed, e.g., (i) the inner-surface helicoid of the driving ring engages with a fixed frame; (ii) the driving ring and the second frame are arranged to rotate relatively, and to move together along the optical axis, and (iii) the outer-surface helicoid of the driving ring engages with the first frame. With this arrangement, if the outer-surface and inner-surface helicoids of the driving ring are formed in the same direction, the traveling distance of the first frame can be made longer.
There are various ways to non-linearly move the third lens group and the fourth lens group, with respect to the first and second lens groups which can be moved by the above-explained linear-moving mechanism. For example, the third and fourth lens groups can be arranged to non-linearly move along cam grooves which are formed on a cylindrical body which rotates in association with the driving ring or formed on the driving ring itself, while the third and fourth lens groups are linearly guided along the optical axis.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2000-018785 (filed on Jan. 27, 2000) which is expressly incorporated herein by reference in its entirety.

Zoom lens system and a zoom lens barrel therefor

Abstract: wherein

Abstract: xcex94X1 and xcex94X2 designate the traveling distances of the first lens group and the second lens group, from the short focal length extremity to the long focal length extremity.


Methods according to some embodiments include writing servo patterns on a data storage medium including a plurality of timing patterns in response to phase correction values generated using a phase correction value (PCV) kernel having a length that is less than the number of timing patterns on the data storage medium.

Disk drives are commonly used in microprocessor based electronic devices, such as workstations, personal computers, laptops and other computer systems, to store and retrieve large amounts of data. A typical disk drive includes a plurality of magnetic disks that are rotated by a spindle motor and an actuator arm assembly that includes read/write heads mounted to flexure arms. An actuator motor (e.g., voice coil motor) can rotate the flexure arms and heads about a pivot bearing relative to the disks. The heads are configured to fly upon air bearings in very close proximity to the rotating disks.
The surface of each disk is divided into a series of data tracks which are spaced radially from one another across a band having an inner diameter and an outer diameter. The data tracks extend circumferentially around the disks and store data in the form of magnetic flux transitions on the disk surfaces. Each data track is divided into a number of data sectors that store fixed sized blocks of user data. Embedded among the data sectors on each track are servo fields that define servo information that enables the disk drive to control the radial position of the heads relative to tracks on the disks and to determine the circumferential location of the heads.
The servo fields may be written to the disks during the manufacture of a disk drive using a highly precise servo track writer, which utilizes the heads of the disk drive to write the servo fields. Because the servo fields are used to define the radial locations of tracks and the location of data along a track, it is important to precisely control the locations on the disk surfaces at which the servo fields are written. Thus, a typical servo track writer includes a precise clock signal generator and an additional recording element that is used to write a reference clock pattern on a disk surface responsive to the clock signal. The reference clock pattern is then read back from the disk surface by the additional recording element to generate a disk reference clock signal synchronized to the rotation of the disks, which is used to determine where to write the servo fields through the read/write heads onto the disks.
Disk drives have been developed that self-servo write the servo patterns without a servo writer. For example, an incremental two-pass self-servo write process begins with a first pass that writes reference servo patterns at a position determined by a crash-stop (the mechanical limit of the head's movement) and then servos on the reference servo patterns and writes the next set of reference servo patterns. The first pass repeats as the head moves radially across the disk, with each step servoing on the previously written reference servo patterns to write the next reference servo patterns at the next radial position. During the first pass, the servo loop has no absolute reference to ensure placement of the reference servo patterns at the appropriate radius. After the first pass finishes the complete stroke, a second pass writes the final servo patterns using the reference servo patterns to find the appropriate positions. However, the second pass substantially increases the self-servo writing time.
In some disk drives, spiral patterns are written onto the disk, and the disk drive self-writes servo patterns on the disk using the spiral patterns as a reference for servoing the head. For example, 100-200 spirals may be written onto the surface of the disk. The spirals generally form an outwardly-expanding pattern from an inner diameter of the disk to an outer diameter of the disk. However, there may be small variations in the circumferential spacing of the spirals. Some aspects of these variations are predictable, however, because the variations repeat with each revolution of the disk. Such variations may cause the servo patterns to be written at incorrect locations on the disk. Accordingly, when self-writing the servo patterns on the disk, it is desirable to predict and account for these variations.

Reduced convolution for repetitive disturbance rejection


A device for mixing and dispensing a paste, such as bone cement, comprises a housing (H) with a feeding mechanism (53), and a cylinder (51) for mixing a powder component and a liquid component forming the paste. A piston assembly includes a paste feeding member (57) located in the cylinder, and a tubular member (54). A mixing member (55) is located in the cylinder (51), and a mixing rod (52) extends within the tubular member (54) of the piston assembly. The mixing rod (52) is movable in the tubular member (54) of the piston assembly. The tubular member (54) is provided with external engagement means (T) by which the paste feeding member (57) is movable within the cylinder (51) in a feeding direction. The feeding movement is operated by the feeding mechanism.

In general terms, bone cement is used for instance in connection with surgery like replacement of hip joints and spinal disc enhancements. When applying the bone cement e.g. to the hip, it is crucial that the injection instrument is sterile. Otherwise the patient runs the risk of getting bacteria into the body, and in a worst case scenario the bacteria is multi-resistant. On a personal level, the recovery time for the patient may increase as well as be more painful. Besides the patient may be forced to further surgery, and in the worse case scenario he/she may even decease. From the society's point of view this kind of mistake in the treatment is very expensive.
Examples of equipment used in practice are the devices for mixing and dispensing bone cement paste described in U.S. Pat. No. 7,513,679B2 and U.S. Pat. No. 8,845,647B2. Devices of this kind, also referred to as mixing guns, comprise a handle assembly with a trigger mechanism by means of which the paste is fed out of a cylinder attached to the handle assembly.
Before dispensing, a liquid (monomer) and bone powder are mixed within the cylinder by means of mixing means which are reciprocated therein. The paste mixing and feeding mechanism includes a rod and spring members of metal, whereas the rest of the device is of plastic.
In U.S. Pat. No. 4,994,065A another injection gun for injecting low volume, high pressure shots of bone cement is disclosed. The injection gun comprises a rod provided with notches extending through a tube. The notches interact with pawls in a trigger assembly. The feeding mechanism requires several parts: two sets of pivot pins, springs, and pawls as well as a compression spring. The multitude of parts provides the injector with a large amount of possible error sources.
A device for controlling the injection of bone cement into a cavity is described in U.S. Pat. No. 4,546,767A. This device comprises a ratchet rod provided with notches on its underside, which interacts with a ratchet trigger, together affecting a plunger for feeding of cement.
A further injection gun for injecting high-viscosity masses into the human body is described in WO2014/202350. This gun comprises a cylinder and a mixing assembly operated by a rod which is axially movable. Furthermore, the gun has a feeding assembly including a threaded rod which upon turning (by a handle) pushes the material within the cylinder. The mixing and the injection of the bone cement are performed in two separate steps. The injection of the bone cement is performed by using two hands, where one hand holds the gun and the other hand is used for turning the handle. This procedure thus involves several steps which take up valuable time in the stressful environment in which the operation is performed.
As to further background art, the mixing and injection guns known from U.S. Pat. No. 6,439,439B1 and DE10252027A1 should be mentioned.
Surgery, such as hip joints replacement, is conducted in stressful environments under high time pressure. Long patient waiting lists force the surgeons to be time efficient in order to manage a plurality of patients each day. It is crucial that the bone cement has the right viscosity when applied to the human body, and the time frame from mixing to applying is thus very short. Furthermore, due to the complex injection guns existing on the market a surgery is performed by at least three persons; a surgeon, a nurse and/or an assisting nurse or doctor. From the above it is understood that there is room for improvements.


A diamond tool comprises a circular core plate and a peripherally attached cutting segment. The cutting segment comprises a plurality of abrasive particles, a holding body that holds the abrasive particles, and a plurality of non-abrasive inserts. The abrasive particles are dispersed within the holding body and the non-abrasive inserts are embedded in the holding body. The non-abrasive inserts are sized and distributed so that the peripheral average density of the abrasive particles in the holding body of the cutting segment varies across the peripheral edge in discrete steps or continuously.

1. Field of the Invention
The invention is related to a diamond tool. More particularly, the present invention is related to a rotating diamond blade that is used to cut hard material such as granite, tiles, concrete, asphalt and so on.
2. Description of the Prior Art
Diamond tools comprise numerous artificially-made diamond particles embedded in a soft material, which is usually metal. A diamond tool blade provided in a form of rotating saw disc is widely used at building sites, to cut hard and brittle construction material including ceramic tiles and stone slabs. A diamond tool blade is a disposable part, as the diamond particles are consumed and removed from the blade during cutting process. Speed, accuracy and efficiency of cutting and service life of the blade depend heavily on proper distribution of diamond particles in the blade.
One approach by prior art is the turbo blade. It includes repetition of a cutting block and a blank space back to back along the periphery of a blade disk. The cutting blocks are provided in staggered fashion along both sides of the periphery. The turbo blade has advantages in manufacturing small, portable diamond blades and high cutting speed. A disadvantage of the turbo blade is that it incurs substantial vibration during cutting process and the cut surface is not smooth. In addition, the accuracy of cut material is low and often requires additional finishing operation.
Another prior art blade comprises multiple layers of sintered metal powder and diamond particles arranged on the surface of and between the layers. The layers are provided on the rim of a blade disc. This structure provides efficient arrangement of diamond particles and enhances speed and accuracy of cutting, and service life of the blade. However, this layered blade has disadvantages that it requires expensive manufacturing devices and only suitable for larger and thicker segmented blades due to its structural complexity.
A new portable diamond tool blade, which is economic, durable and provides fast and accurate cutting of stone or ceramic materials, has long been in need.


A retractable top covering system has a top covering configured to cover an open top area of a container having sides that define an interior space. The top covering is connected to a retractable top drive mechanism that selectively retracts and deploys the retractable top covering. A track is supported along an upper edge of the container around a portion of the open top area. The track supports at least one trolley for relative movement along the upper edge of the container. A support bow is connected the trolley and supports the retractable top covering. A cable, connected between the retractable top drive mechanism and the trolley, moves the trolley along the track in response to retraction and deployment action of the retractable top drive mechanism.

This invention relates in general to covering systems used in tractor-trailer hauling applications. In particular, this invention relates to a power actuated top covering system for selectively covering the open top area of a trailer having rigid side walls.
Commercial truck trailers are produced in a variety of forms to support and haul a variety of goods. Flat bed trailers are designed to haul heavy loads, such as coiled steel or larger pieces of equipment, and permit these loads to be placed on the trailer surface easily. Box trailers tend to haul lighter packaged goods that need to be protected from wind loads during transport. Open top, dump trailers configured to haul generally loose and dry goods, such as grain, sand, gravel and the like, have generally rigid side walls and a rear mounted gate or a bottom-mounted chute or door. The open top permits the goods to be loaded into the trailer. The gate permits goods to be released as the trailer is tilted. The bottom-mounted door permits unloading without the need to tilt the trailer.
Open top dump trailers, because of the loose nature of their cargo, are often covered to prevent road wind from blowing the trailer contents onto the roadway and onto other vehicles following behind. Many states require certain types of loose cargo to be covered to prevent debris from impacting other vehicles. These top coverings may be canvas or rigid panels. Canvas coverings are usually rolled, either to one side or an end of the trailer, to deploy or remove the cover. The rolling mechanism may include a U-shaped "towel" bar that extends along the outer surface of the side walls and pivotally mounts to the lower portion of the trailer. The tarp is rolled onto or off of the towel bar portion that extends across the trailer as the side arms are pivoted. Other types of deployment mechanisms may include a hand operated crank that rotates a take-up bar to roll up the tarp covering. These types of deployment devices are prone to damage because they mount on the exterior of the trailer bed or become cumbersome to operate. Thus, it would be desirable to provide a tarp deployment system for an open top trailer that improves deployment and durability.


Frames of image data representative of a scene containing deformable geometry subject to global illumination are computed in real-time. Frame animation data is computed for a series of frames representative, in animated sequence, of a scene containing deformable geometry. The frame animation data includes vertex attributes of a control mesh descriptive of the three dimensional surface of graphical elements occurring within the scene. Based on the frame animation data, respective illumination values are computed for the individual polygons of the control mesh to determine the global illumination of the scene. The computation is performed iteratively with respect to each frame set of frame animation data until a qualified convergence of global illumination is achieved. Within each iteration, the respective illumination values are determined based on the frame-to-frame coherent polygon illumination values determined in a prior iteration. Qualified convergence is achieved within the frame-to-frame interval defined by a real-time frame rate.

1. Field of the Invention
The present invention is generally related to the computer graphics rendering of dynamic scenes subject to global illumination and, in particular, to the real-time rendering of complex, deformable geometries with global illumination computed shading to obtain realistic scene lighting.
2. Description of the Related Art
A key requirement in the realistic rendering of computer generated graphical images is the accurate computation of the interdependent light distribution among the various element surfaces within the image scene. To address the accurate synthesis of scene lighting, various physics-based global illumination techniques have been developed. These techniques, including radiosity, ray tracing, and photon mapping, approach realistic image rendering by directly simulating the physical phenomenon of light distribution within a set three-dimensional environment. Many of the theoretical and practical implementation issues of physics-based global illumination techniques are explored in Advanced Global Illumination by Philip Dutre, Philippe Bekaert, and Kavita Bala, AK Peters, Ltd., (July 2003).
The principal limitation of known physics-based global illumination techniques is the computational intensity of the physics-based simulations. The computational requirements of the algorithms implementing the simulations for scenes of even modest complexity well-exceed usable display frame-rates. Trade-offs, such as reducing the simulation accuracy, directly impact the realism of the rendered scene. Other trade-offs, such as pre-computation of light distribution for static elements, have been explored. Unfortunately, all but a small portion of a typical scene has to be statically pre-computed in order to achieve useable frame-rates. This results in quite visible lighting inaccuracies whenever the any dynamic element is repositioned within the overall scene. Even with the substantial improvements in the processing performance of general purpose central processing units (CPUs) and peripheral graphical processing units (GPUs), known physics-based global illumination techniques are conventionally accepted as too computationally expensive achieve real-time rendering of fully dynamic scenes.
Consequently, a need exists for a physics-based global illumination technique that is fully capable of the real-time rendering of fully dynamic scenes.

System and methods for real-time rendering of deformable geometry with global illumination


A transmission clutch including: a carrier; a clutch pack; friction plates; a compression plate including a portion; and a first ramp ring including: a first portion in contact with the portion of the compression plate; and a second portion. The clutch includes a second ramp ring including a third portion axially aligned with the second portion; a lever spring; and a piston. The piston displaces the spring in an axial direction such that: the spring applies a force to the second portion; the first ramp ring rotates in a circumferential direction and axially displaces in the axial direction; and the first ramp ring urges the compression plate in the axial direction to contact the clutch pack. The piston displaces the lever spring further in the axial direction such that the compression plate clamps pressure plates and friction plates in the clutch pack to rotationally fix the carrier to the housing.

In general, clutches have two objectives: to transmit full torque when closed and to transmit no torque when open. The prior art teaches wet clutches with clutch drag from frictional contact between rotating components of the clutch such as a piston, pressure plates, and friction plates, when open. The clutch drag reduces the efficiency of a component, such as a transmission, including the clutch. The prior art teaches reducing such clutch drag by separating a piston, pressure plates, and friction plates by greater respective amounts. However, the prior art also teaches that greater amounts of hydraulic fluid are needed to displace the separated elements, increasing the time needed to close the clutch. For example, if the piston is located further from the pressure plates, more fluid is needed to displace the piston the further distance. The above options create a conflict between fuel economy (reduced by clutch drag) and acceptable driveability (response time for closing the clutch).
There are other problems associated with reducing clutch drag by increasing gaps in the clutch. When using a fixed lever or hydraulic ratio to engage a clutch, it becomes difficult to find the touch point (when torque begins to be transmitted) when attempting to close the increased gaps quickly. The difficulty in finding the touch point may result in either slow shift times or rough shifts. Furthermore, clutch drag is often exacerbated in the case of wet clutches in order to control tolerances in fabrication. That is, because a smaller lift-off gap is easier to control, gaps between components in the clutch are even further reduced. Variable ratio mechanisms have been proposed; however, such mechanisms have problems with complexity, friction, or are difficult to apply to rotating clutches.


A method of fabricating a magnetic transducer is described which uses a trailing shield throat pad to set the trailing shield throat height. The trailing shield throat pad is used as a part of the structural form over which the material for the trailing shield is formed. The trailing shield throat pad is preferably made of a material which can selectively be removed from the gap layer with a selective etching process such as reactive-ion etching (RIE). The front edge of the trailing shield throat pad is used to define a peninsula on the trailing shield and thereby the throat of the trailing shield.

In a typical prior art magnetic disk recording system a slider containing magnetic transducers for reading and writing magnetic transitions flies above the disk while it is being rotated by a spindle motor. The disk includes a plurality of thin films and at least one ferromagnetic thin film in which the recording (write) head records the magnetic transitions in which information is encoded. The magnetic domains in the media on can be written longitudinally or perpendicularly. The read and write head portions of the slider are built-up in layers using thin film processing techniques. Typically the read head is formed first, but the write head can also be fabricated first. The conventional write head is inductive.
In a disk drive using perpendicular recording the recording head is designed to direct magnetic flux through the recording layer in a direction which is generally perpendicular to the plane of the disk. Typically the disk for perpendicular recording has a hard magnetic recording layer and a magnetically soft underlayer. During recording operations using a single-pole type head, magnetic flux is directed from the main pole of the recording head perpendicularly through the hard magnetic recording layer, then into the plane of the soft underlayer and back to the return pole in the recording head. The shape and size of the main pole and any shields are the primary factors in determining the track width.
FIG. 1 illustrates a prior art head 26 for perpendicular recording and the associated media 27 in a disk drive 20. The section is taken perpendicular to the ABS. This figure and the others included herein are not to scale, in part, because the smaller components and spacings would be unclear. Places where the relative sizes and dimensions are significant will be noted if not known to those skilled in the art. The ABS is shown without a thin film protective overcoat which would normally be present in a production head. The term ABS as used herein means the plane as shown in the drawings without regard to whether an overcoat is present. The read sensor and its shields are not shown in FIG. 1, but could be located either to the left or right side of the write head. This design has a single coil 35. The yoke is composed of ferromagnetic pole pieces 41, 42, 43, 45 and 46. The floating trailing shield 44 is not part of the yoke. The movement of the magnetic recording medium is from the main pole piece or write pole 42 to the trailing shield 44, hence the label "trailing." The stitch pole piece 41 provides the needed mass of ferromagnetic material for the main pole piece 42, but does not extend to the ABS. Only the small area of the main pole 42 appears at the ABS. The back of the yoke 46 (often called the "back gap" for historical reasons) directly connects the stitch pole piece 41 to the return pole piece 43. The trailing shield 44 has a simple rectangular cross-section in this design, but other shapes are possible. The conventional method for producing a head as shown in FIG. 1 is to form the structures starting with the return pole piece 43 on the right. The ABS is exposed when the wafer is cut after the structures have been formed. FIG. 2 illustrates a wafer 25 on which a plurality of write heads are being fabricated. The full film trailing shield gap layer 47 has been deposited on completed main pole piece 42. A photoresist 49 has been patterned with a void which will be used to form the trailing shield in subsequent steps. The right hand edge of the photoresist 49 determines the final back edge of the trailing shield. The dimension of the trailing shield measured perpendicular from the ABS into the head is known as the "throat." The term trailing shield thickness is used to mean the dimension of the trailing shield along the ABS from the trailing shield gap layer 47 to the left edge as shown in FIG. 1. The cut for the ABS (and any lapping) determines the final ABS plane of the trailing shield. The use of a conventional photoresist for determining the throat of the trailing shield leads to imprecision which is unacceptable as the dimensions of write head designs shrink. The photoresist material is subject to erosion by the processes which are used to deposit the ferromagnetic material for the trailing shield which include plasma ashing and acid dipping as preparatory steps for electroplating NiFe. The photoresist for the electroplating process must be relatively thick which limits the achievable aspect ratio (thickness:throat ratio) for the trailing shield. Future write heads require a higher aspect ratio for the trailing shield than the current photoresist technique provides.

Method of making a magnetic write head with trailing shield throat pad

Hitachi Global Storage Technologies Netherlands B.V.


A position/pose acquisition unit acquires a position and a pose of a viewpoint in a real space. A site data disposition unit disposes site data which is three-dimensional data representing a shape of a construction site in a virtual space on the basis of the position and the pose of the viewpoint. A machine data disposition unit disposes machine data which is three-dimensional data representing a shape of a work machine at a position corresponding to the site data in the virtual space. A rendering unit renders the disposed machine data.

PTL 1 discloses a technique in which, in order to cause an operator of a work machine to recognize other workers who are working around the work machine, an image indicating the presence of a worker is combined with a marker portion drawn on a helmet worn by the worker in a captured image displayed on display means.

Display control device, display control method, program, and display system


An aspiration device is described, including a bulb aspirator including a bulb body, a first collar and tip, the bulb body includes an upper portion configured for receiving one end of the first collar and lower portion configured for receiving in a first configuration a stop and in a second different configuration a second collar associated with a suction tube, the tip is configured for insertion into a passageway; the stop being configured for detachable connection to the lower portion of the bulb body when in the first configuration; and the suction tube including the second collar, a tube portion and an adaptor, the second collar is disposed at a first end of the suction tube and being adapted to be coupled to the lower portion of the bulb body, the adaptor is configured to adapt to a human mouth to enable suction to be applied at the adaptor.

Nasal aspirator systems are commonly used in the cleansing of a human's or any other animal's nostrils. For example, babies lack the ability to clear their own nostrils with great efficiency, so that blockage in the nostrils can remain for extended periods of time, impairing breathing, eating, breast feeding, and mood. Due to the frequency of a runny or congested nose, parents may purchase nasal aspirators of various types and functionalities. One common nasal aspirator is a rubber bulb that includes a tip which may be inserted into a baby's nostril. The squeezing of the bulb pushes air from the bulb through the tip. Release of the bulb creates a low (i.e., negative) pressure area in the bulb, bringing air (and potentially mucus) through the tip and into the bulb and will result in equalizing the pressure (a return to a neutral state) when the bulb is re-inflated due to elasticity. This equalization process creates a suction from the tip and quite literally sucks out mucus or nasal secretions from the nostril (assuming the tip has been placed there at the time of release).

This patent is subject to a terminal disclaimer.


System and method for controlling voltage in a non-volatile memory system is provided. The system includes a voltage regulator that monitors an output voltage (VDD) and a mirror voltage (Vmirror). When the voltage VDD is greater than the voltage Vmirror beyond a threshold value, a control signal turns off a control transistor, which prevents the voltage VDD to increase beyond a certain value. The method includes comparing an output voltage (VDD) with a mirror voltage (Vmirror); and generating a control signal to turn off a control transistor if the voltage VDD is greater than the voltage Vmirror.

1. Field of the Invention
The present invention relates generally to non-volatile memory devices and particularly, to voltage regulators used in non-volatile memory devices.
2. Background of the Invention
Non-volatile semiconductor memory devices have become popular for use in various electronic devices. For example, non-volatile semiconductor memory (including Electrical Erasable Programmable Read Only Memory (EEPROM) and flash memory) is used in cellular telephones, digital cameras, personal digital assistants, mobile computing devices and other electronic devices.
Voltage regulators are commonly used to regulate internal voltage in non-volatile memory systems, for example, in a NAND based flash memory system. A typical voltage regulator provides an output voltage (VDD) based on an externally provided input voltage (VEXT). Typically, VDD is used by various components within the memory system.
Conventional voltage regulators have inherent drawbacks. For example, the regulated output voltage is susceptible to load current variations. In conventional systems, if a load current is lower than a specified value then the output voltage from the voltage regulator increases substantially. To limit this effect, typically, a current sink is provided at an output node of the voltage regulator. The current sink increases power consumption in the voltage regulator, which is not desirable in high-density flash memories.
Furthermore, VDD spikes during start-up operation of the memory system, because an output transistor is always on. This may cause undesirable stress for plural circuit components.
Therefore, there is a need for a method and system for better controlling output voltage in voltage regulators.

Voltage regulator in a non-volatile memory device